JP2023005048A - Document conveyance device - Google Patents

Abstract

To provide a document conveyance device capable of solving a problem caused by taking-out of a document stacked on a paper feed tray.SOLUTION: This document conveyance device comprises: a document detection sensor 123 that detects a document on a paper feed tray 43; a discharge tray 45 provided below the paper feed tray 43; a lifting mechanism 125 for lifting the paper feed tray 43 between an upper limit position where the document is pressed to a delivery roller 103 to raise the delivery roller 103 to a prescribed paper height and a lower limit position separated downward from the delivery roller 103; and an upper limit position detection sensor 115 that detects rising of the paper feed tray 43 to the upper limit position. When the document detection sensor 123 detects the document in a standby state, the lifting mechanism 125 raises the paper feed tray 43 to the upper limit position and then lowers it, and the paper feed tray 43 is stopped with the passage of prescribed time after the upper limit position detection sensor 115 no longer detects the paper feed tray 43.SELECTED DRAWING: Figure 3

Description

The present invention relates to a document conveying device that conveys a document to a document reading device.

2. Description of the Related Art Along with the conversion of various documents (original documents) into electronic data in response to the recent paperless trend, improvements in quality and functions required for document feeders of multifunction peripherals (MFPs) have been sought. One of the required functions is high-speed reading of large-capacity originals. This demand is met by increasing the reading speed or increasing the stacking amount of originals. Furthermore, in order to ensure the reliability of the read data, it is equipped with a sensor that detects double feeding to prevent skipping of documents and functions to protect documents in the event of a paper jam.

For example, Japanese Patent Application Laid-Open No. 2002-200000 discloses an elevating means for elevating a paper feed tray and an elevation control means for elevating the paper feed tray in accordance with feeding out of a document from the paper feed tray. A document feeder (corresponding to a document feeder) has been proposed that is configured to move up and down by the same amount as the paper tray moves up and down. Specifically, the paper feed tray is positioned at the lowest position based on a detection signal from a lower limit sensor that detects that the paper feed tray has reached the lower limit position with no document placed thereon, while the document is placed thereon. When the presence/absence sensor detects this, the paper feed tray is raised based on this detection signal until the uppermost document comes into contact with the pickup roller.

JP-A-2005-8283

In the document feeder described in Patent Document 1, when the presence or absence of documents is detected by the document presence/absence sensor, the paper feed tray rises until the uppermost document comes into contact with the pickup roller. . Then, for example, when you want to add a document, when you remove the document from the paper feed tray, the top document and the pickup roller will rub against each other, and the document will be damaged or the pickup roller will wear out. There's a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a document feeder capable of solving problems caused by taking out documents stacked on a paper feed tray.

In order to achieve the above object, the document conveying apparatus of the present invention comprises: a paper feed tray on which documents are stacked and which can be moved up and down; a discharge tray provided below the paper tray; a transport path along which the document is conveyed from the paper feed tray to the discharge tray via a reading position; a delivery roller that rotates to feed the document onto the transport path; an upper limit position that presses the stacked document against the delivery roller to raise the delivery roller to a predetermined sheet feeding height; an elevating mechanism for elevating the paper feed tray between a lower limit position spaced downward from a roller; When the document detecting sensor detects the document during standby in which the conveying operation is not performed, the lifting mechanism raises the paper feed tray to the upper limit position and then lowers it, and the upper limit position detecting sensor detects the upper limit position. The lift mechanism stops the paper feed tray after a predetermined time has passed since the paper feed tray is no longer detected.

In the document conveying device of the present invention, the predetermined time is the time from when the upper limit position detection sensor stops detecting the paper feed tray to when the document on the paper feed tray is separated from the delivery roller. It may be characterized by

In the document conveying apparatus of the invention, the predetermined time may be changeable.

According to the present invention, by appropriately selecting the predetermined time after the upper limit position detection sensor stops detecting the paper feeding tray, after placing the document on the paper feeding tray and before starting the document conveying operation, The uppermost document can be separated from the delivery roller. Therefore, it is possible to prevent friction between the document and the delivery roller when the document is taken out from the paper feed tray.

1 is a front view schematically showing an internal configuration of a multi-function machine including a document conveying device according to one embodiment of the present invention; FIG. 1 is a perspective view showing a document conveying device (with an outer cover removed) according to an embodiment of the present invention; FIG. 1 is a cross-sectional view showing a document conveying device according to one embodiment of the present invention; FIG. FIG. 2 is a front view showing an elevating mechanism for a paper feed tray in the document conveying device according to one embodiment of the present invention; 1 is a perspective view mainly showing an elevating arm of an elevating mechanism for a paper feed tray in the document conveying apparatus according to one embodiment of the present invention; FIG. 2 is a perspective view mainly showing a lower limit sensor of an elevating mechanism for a paper feed tray in the document conveying apparatus according to one embodiment of the present invention; FIG. 3 is a block diagram showing a control section of the document conveying device according to one embodiment of the present invention; FIG. 5 is a flowchart showing an example of document transport processing in the document transport device according to one embodiment of the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-function machine including a document conveying device according to an embodiment of the present invention will be described below with reference to the drawings.

A multi-function device 1 will be described with reference to FIG. FIG. 1 is a front view schematically showing the internal configuration of the multifunction machine 1. As shown in FIG. Fr, Rr, L, and R shown in each figure indicate the front side, rear side, left side, and right side of the multifunction machine 1, respectively.

The multifunction device 1 includes an image forming device 3 , a document reading device 5 and a document conveying device 7 . The image forming device 3 forms an image on a sheet based on the image of the document G read by the document reading device 5 . The document conveying device 7 conveys the document G to the document reading device 5 .

First, the image forming apparatus 3 will be briefly described. The image forming apparatus 3 includes a paper feeding section 11 , an image forming section 13 and a fixing section 15 . The paper feeding unit 11 feeds sheets accommodated in the paper feeding cassette 17 and conveys them to the conveying path 19 . The image forming unit 13 electrophotographically forms a toner image on the sheet conveyed along the conveying path 19 based on the image of the document G read by the document reading device 5 . The fixing device 15 fixes the toner image formed on the sheet to the sheet. The sheet on which the toner image is fixed is stacked on the discharge tray 21 .

Next, the document reading device 5 will be described. The document reading device 5 includes a contact glass 31 on which a document G can be placed, and a scanner section 33 arranged below the contact glass 31 for reading an image of the document G placed. The scanner unit 33 includes a first carriage 35 and a second carriage 37 that interlock and move in a predetermined direction (horizontal direction), and an imaging unit 39 that is fixed at a predetermined position.

The first carriage 35 accommodates a light source 35a and a first mirror 35b. The first carriage 35 is movable rightward from a home position below the left end of the contact glass 31 . The second carriage 37 accommodates second and third mirrors 37a and 37b. The second carriage 37 can move rightward under the first carriage 35 from a home position on the left side of the home position of the first carriage 35 .

The imaging unit 39 includes a CCD sensor 39a and an imaging lens 39b that forms an optical image on the CCD sensor 39a. The imaging unit 39 is fixed below the right end of the contact glass 31 at the same height as the third mirror 37 b of the second carriage 37 .

When reading the document G placed on the contact glass 31, the first carriage 35 moves rightward from the home position at a predetermined speed while emitting light from the light source 35a, and the second carriage 37 moves to the home position. , to the right at half the speed of the first carriage 35 . As a result, the reading position of the document G (the position where the light emitted from the light source 35a is reflected toward the contact glass 31 by the first mirror 35b of the first carriage 35) is moved, and the image of the entire surface of the document G is displayed. read. The light reflected by the document G is reflected to the left by the first mirror 35b, is further reflected by the second and third mirrors 37a and 37b of the second carriage 37, and is imaged on the CCD sensor 39a by the imaging lens 39b. be done. The formed optical image is converted into an electrical signal and transmitted to the control unit 201 (see FIG. 7).

On the other hand, when reading a document G conveyed by the document conveying device 7, which will be described later, the first carriage 35 and the second carriage 37 are stopped at their home positions, and the document G conveyed to the reading position P is read. read the image. As the document G passes through the reading position P, the image of the entire surface of the document G is read.

Next, the document conveying device 7 will be described with reference to FIGS. 1, 2 and 3. FIG. 2 is a perspective view showing the document feeder 7 (with the outer cover 63 removed), and FIG. 3 is a sectional view showing the document feeder 7. As shown in FIG.

The document conveying device 7 includes a main body 41 (see FIGS. 2 and 3), a paper feed tray 43 on which a document G whose image is to be read is placed, and a paper feed tray 43 which is provided below the paper feed tray 43 so that the image can be read. A discharge tray 45 on which the document G is stacked, a transport section 47 in which the document G is transported from the paper feed tray 43 to the discharge tray 45 via the reading position P, and a document from the paper feed tray 43 to the transport section 47. and a delivery unit 49 for feeding G. As described above, the reading position P is a state in which the first carriage 35 and the second carriage 37 of the document reading device 5 are stopped at the home position, and the light emitted from the light source 35a of the first carriage 35 reaches the first mirror 35b. is a position reflected on the contact glass 31 by .

As shown in FIG. 2 , the main body 41 includes a rectangular bottom plate 51 , a front wall 53 standing along the left half of the front edge of the bottom plate 51 , and a wall extending along the entire rear edge of the bottom plate 51 . and an upright rear wall 55 . Left and right rear corners of the body portion 41 are rotatably supported by the document reading device 5 . By rotating the body portion 41 upward, the original can be placed on the contact glass 31 of the original reading device 5 and the original can be taken out from the contact glass 31 . Further, when the body portion 41 is rotated downward, the document on the contact glass 31 is pressed against the contact glass 31 by the bottom plate 51 and positioned.

Next, the transport section 47 will be described. The conveying portion 47 has an inner guide 61 and an outer cover 63 that covers the upper surface and the left side surface of the inner guide 61, and is located on the bottom plate 51 of the main body portion 41 between the front wall 53 and the rear wall 55. is provided.

As shown in FIG. 3, the transport section 47 is provided with a transport path 69 leading from the receiving port 65 to the reading position P and a discharge path 73 extending from the reading position P to the discharge port 71 . A transport path 69 is formed between the outer cover 63 and the inner guide 61 . The discharge path 73 is disposed inside the inner guide 61 and formed between upper and lower plate-like guide members 75 and 77 facing each other with a gap through which the document G can pass.

The transport path 69 is formed so as to extend substantially straight leftward from the receiving port 65 and then curve downward toward the reading position P. As shown in FIG. The discharge path 73 is formed to extend obliquely upward to the right from the reading position P toward the discharge port 71 . In this manner, the document G is transported from the receiving port 65 to the reading position P along the transport path 69, transported from the reading position P to the discharge port 71 along the discharge path 73, and passes through the reading position P. , the image of the document G is read by the document reading device 5 . In the following description, the terms "upstream side" and "downstream side" refer to the upstream side and the downstream side in the direction in which the document G is conveyed. The width direction is defined as the direction intersecting the conveying direction.

First to fourth transport roller pairs 81, 83, 85 and 87 are arranged in the transport path 69 in order from the upstream side.

The first to fourth conveying roller pairs 81, 83, 85, 87 are arranged at predetermined intervals along the conveying direction. Each transport roller pair has a drive roller and a driven roller that rotates in contact with the drive roller. Each drive roller is supported by the inner guide 61 so as to be rotatable around a drive shaft parallel to the width direction. Each driven roller is rotatably supported by the outer cover 63 around a rotation axis parallel to the width direction.

An opening 51 a corresponding to the reading position P is formed in the bottom plate 51 of the main body 41 . A shading plate 91 is arranged in the inner guide 61 so as to face the opening 51a. Between the shading plate 91 and the contact glass 31 of the document reading device 5, there is a space through which the document G can pass. The shading plate 91 performs shading correction of the CCD sensor 39a.

A fifth transport roller pair 95 and a discharge roller pair 97 are arranged in the discharge path 73 in this order from the upstream side.

The fifth transport roller pair 95 is arranged downstream of the shading plate 91 and has a driving roller and a driven roller that rotates in contact with the driving roller. The drive roller is supported by the upper guide member 75 so as to be rotatable around a drive shaft parallel to the width direction. The driven roller is rotatably supported by the lower guide member 77 around a rotation axis parallel to the width direction.

The discharge roller pair 97 is arranged upstream of the discharge port 71 and has a drive roller and a driven roller that rotates in contact with the drive roller. The drive roller is supported by the upper guide member 75 so as to be rotatable around a drive shaft parallel to the width direction. The driven roller is rotatably supported by the lower guide member 77 around a rotation axis parallel to the width direction.

Next, the feeding portion 49 will be described. The feeding section 49 is arranged downstream of the receiving port 65 and includes a feeding roller 103 and a conveying belt 105 housed in a holder 101 , and an auxiliary roller 107 . The holder 101 has a box shape with an open bottom surface. A projecting piece 101a protrudes from the upper surface of the top plate of the holder 101 . The delivery roller 103 is arranged on the upstream side inside the holder 101 and is rotatably supported around a rotation axis parallel to the width direction. The conveying belt 105 is arranged inside the holder 101 on the downstream side of the feeding roller 103 and is wound around the driving roller 109 and the driven roller 111 . The driving roller 109 is arranged on the downstream side of the driven roller 111 and rotates about a driving shaft and a rotating shaft parallel to the width direction. As shown in FIG. 2, the holder 101 is arranged in the center in the width direction, and both ends of the driving shaft 109a of the driving roller 109 are rotatably supported by the front wall 53 and the rear wall 55 of the main body 41. there is A rear end of the drive shaft 109a is connected to a drive motor 113 (see FIG. 3).

A one-way clutch (not shown) is arranged between the drive shaft 109 a and the holder 101 . When the drive shaft 109a rotates counterclockwise in FIG. 3, the holder 101 swings upward around the drive shaft 109a together with the drive shaft 109a. On the other hand, the drive shaft 109a rotates with respect to the holder 101 when the drive shaft 109a rotates clockwise. As a result, the driving roller 109 rotates and the conveying belt 105 runs clockwise in FIG. Furthermore, the clockwise rotation of the drive shaft 109a is transmitted to the delivery roller 103 via a gear (not shown), and the delivery roller 103 rotates clockwise in FIG.

Further, the auxiliary roller 107 is arranged in the inner guide 61 so as to contact the lower running surface of the transport belt 105, and is rotatably supported about a rotation axis parallel to the width direction.

As described above, the holder 101 swings vertically around the drive shaft 109a. At the uppermost position where the holder 101 has swung upwards, the delivery roller 103 rises to a predetermined sheet feeding height. The holder 101 is supported by a stopper (not shown) at the lower limit position where the holder 101 swings downward. The conveying section 47 is provided with an upper limit position detection sensor 115 that detects that the holder 101 has risen to the upper limit position.

The upper limit position detection sensor 115 is, for example, a transmissive photosensor. A transmissive optical sensor has a light emitting portion and a light receiving portion, outputs an on signal when an optical path formed between the light emitting portion and the light receiving portion is blocked, and outputs an off signal when the optical path is formed. Output. Upper limit position detection sensor 115 is supported by outer cover 63 above holder 101 . When the holder 101 rotates to the upper limit position, the projecting piece 101a enters between the light emitting portion and the light receiving portion of the upper limit position detection sensor 115 to block the optical path, and the upper limit position detection sensor 115 outputs an ON signal.

Next, the paper feed tray 43 and the discharge tray 45 will be described. The paper feed tray 43 is a plate-like member on which the maximum size document G can be placed. As shown in FIG. 2, the paper feed tray 43 supports a pair of side cursors 121 for positioning the placed document G in the width direction so as to be movable in the width direction.

Further, the paper feed tray 43 is provided with a document detection sensor 123 for detecting the presence or absence of the document G. As shown in FIG. The document detection sensor 123 is, for example, a reflective optical sensor having a light emitting portion and a light receiving portion. An opening is formed in the upper plate of the paper feed tray 43 at the end on the downstream side. The document detection sensor 123 is arranged below the opening. When the document G is placed on the paper feed tray 43, the document G reflects the light emitted from the light emitting portion through the opening. When the reflected light passes through the opening and is received by the light receiving portion, the original detection sensor 123 outputs an ON signal. On the other hand, when the original document G is not placed on the paper feed tray 43, the light emitted from the light emitting unit is not reflected by the original document G, so that it is not received by the light receiving unit, and the original detection sensor 123 outputs an OFF signal. do.

The paper feed tray 43 is arranged above the right half of the bottom plate 51 of the main body 41, and is tilted downward toward the receiving port 65. The paper feed tray 43 is vertically supported by a lifting mechanism 125 (see FIG. 4). there is The lifting mechanism 125 will be described later.

The discharge tray 45 is formed on the right half of the bottom plate 51 of the main body 41 . The discharge tray 45 is inclined upward from below the discharge port 71 toward the side (right side) away from the discharge port 71 .

Next, the elevating mechanism 125 for the paper feed tray 43 will be described with reference to FIGS. 4 to 6. FIG. 4 is a front view showing the lifting mechanism 125, FIG. 6 is a perspective view mainly showing the lifting arm 133 of the lifting mechanism 125, and FIG. 7 is a perspective view mainly showing the lower limit position detection sensor 177 of the lifting mechanism 125.

The elevating mechanism 125 includes a rail 131 along the vertical direction, an elevating arm 133 that supports the paper feed tray 43 and engages with the rail 131 , and a driving unit 135 that elevates the elevating arm 133 along the rail 131 . I have. The lifting mechanism 125 is provided on the front wall 53 and the rear wall 55 of the body portion 41 below the feeding portion 49 . Specifically, the front wall 53 has a front plate and a front cover that covers the front surface of the front plate, and the rear wall 55 has a rear plate and a rear cover that covers the rear surface of the rear plate. The lifting mechanism 125 is provided on the front surface of the front side plate and the rear surface of the rear side plate. Hereinafter, the front side plate will be referred to as the front wall 53 and the rear side plate will be referred to as the rear wall 55 for ease of explanation. 3 and 4 show the lifting mechanism 125 provided on the front wall 53, and FIG. 5 shows the lifting mechanism 125 provided on the rear wall 55. FIG.

The rail 131 is formed along the vertical direction on the front wall 53 (and the rear wall 55) and has a pair of parallel rail pieces 131a along the vertical direction. The lifting arm 133 includes an engaging portion 141 that engages with the rail 131, a supporting portion 143 that is provided upstream of the engaging portion 141 and supports the downstream end of the paper feed tray 43, and an engaging portion. and a connecting portion 145 that is provided on the downstream side of 141 and connects to the driving portion 135 . The engaging portion 141 includes upper and lower bearings 151 (see FIGS. 5 and 6). The upper and lower bearings 151 are supported between a pair of rail pieces 131a of the rail 131. As shown in FIG. A projecting piece 155 projecting outward is formed on the connecting portion 145 .

The driving portion 135 is arranged downstream of the rail 131 . The drive unit 135 includes a driving sprocket 161 that rotates around a drive shaft parallel to the width direction, a plurality of sprockets 163 (163A, 163B) that rotate around a rotation shaft parallel to the width direction, and a drive sprocket. 161 and a timing belt 167 wound around a plurality of sprockets 163 .

The drive sprocket 161 is arranged downstream of the upper end of the rail 131, and the drive shaft is rotatably supported by the front wall 53 (and the rear wall 55). A lift motor 173 (see FIG. 4) is connected to one end of the drive shaft. The lift motor 173 is, for example, a DC motor. The lift motor 173 is supported by a bracket 171 (see FIG. 6) fixed to the front wall 53 (and rear wall 55).

One sprocket 163A out of the plurality of sprockets 163 is arranged below the driving sprocket 161, and its rotary shaft is rotatably supported by the front wall 53 (and the rear wall 55). Another sprocket 163B is arranged downstream of the driving sprocket 161, and its rotating shaft is rotatably supported by the front wall 53 (and the rear wall 55). A timing belt 167 is wound around these sprockets 161 and 163 .

The driving shaft is driven by the lifting motor 173 to rotate the driving sprocket 161, so that the timing belt 167 runs in both directions. At this time, the linear portion 167x of the timing belt 167 between the drive sprocket 161 and the sprocket 163A arranged below it runs along the vertical direction parallel to the rails 131. As shown in FIG.

The connecting portion 145 of the lifting arm 133 is connected to the linear portion 167x of the timing belt 167. As shown in FIG. As a result, when the timing belt 167 runs, the lift arm 133 moves up and down along the rail 131 . Specifically, the upper and lower bearings 151 of the engaging portion 141 of the lifting arm 133 slide along the inner surfaces of the pair of rail pieces 131 a of the rail 131 . As the lift arm 133 moves up and down in this way, the paper feed tray 43 moves up and down.

The paper feed tray 43 is moved up and down between the upper limit position and the lower limit position by the lifting mechanism 125 . The lower limit position is, for example, a position where a large amount of documents G (eg, 500 sheets) can be placed. The lifting mechanism 125 is provided with a lower limit position detection sensor 177 (see FIG. 6) that detects that the paper feed tray 43 has been lowered to the lower limit position. Lower limit position detection sensor 177 is supported by bracket 171 . The lower limit position detection sensor 177 is, for example, a transmissive optical sensor having a light emitting portion and a light receiving portion. When an optical path is formed between the light emitting portion and the light receiving portion, the lower limit position detection sensor 177 outputs an ON signal, and outputs an OFF signal when the optical path is blocked. When the paper feed tray 43 is lowered to the lower limit position, the projecting piece 155 of the connecting portion 145 of the lifting arm 133 enters between the light emitting portion and the light receiving portion to block the optical path, and the lower limit position detection sensor 177 outputs an ON signal.

On the other hand, when the paper feed tray 43 is lifted, the top document among the documents G stacked on the paper feed tray 43 comes into contact with the delivery roller 103 (see FIGS. 2 and 3) of the delivery section 49 . When the paper feed tray 43 is further raised, the delivery roller 103 is pushed up by the document G, and the holder 101 rotates upward around the drive shaft 109a. The paper feed tray 43 rises until the holder 101 swings to the upper limit position, that is, the feed roller 103 rises to a predetermined paper feed height. Thus, the paper feed tray 43 rises to the upper limit position where the projecting piece 101a of the holder 101 blocks the optical path of the upper limit position detection sensor 115 and the upper limit position detection sensor 115 transmits an ON signal.

At this upper limit position, the feeding roller 103 is raised to the predetermined sheet feeding height as described above, so by rotating the driving shaft 109a of the driving roller 109 of the feeding section 49, the sheet is placed on the sheet feeding tray 43. The fed document G is appropriately delivered by the delivery roller 103 , and the delivered document G is transported to the transport path 69 by the transport belt 105 and the auxiliary roller 107 .

Next, the control section 201 of the document conveying device 7 will be described with reference to the block diagram of FIG. The control unit 201 receives the detection results (ON signal or OFF signal) is sent. The control unit 201 also controls driving of the drive motor 113 (see FIG. 3) of the feeding unit 49 and the lift motor 173 of the lift mechanism 125 (see FIG. 4).

Upon receiving the ON signal from the document detection sensor 123 , the control unit 201 determines that the document G is placed on the paper feed tray 43 .

Further, when receiving the ON signal from the upper limit position detection sensor 115, the control unit 201 determines that the holder 101 has been rotated to the upper limit position, that is, that the paper feed tray 43 has been raised to the upper limit position. Further, when receiving an ON signal from the lower limit position detection sensor 177, the control unit 201 determines that the paper feed tray 43 has been lowered to the lower limit position.

An example of document transport processing in the document transport device 7 having the above configuration will be described with reference to the flowchart of FIG. During standby when the document conveying operation is not executed, the paper feed tray 43 is lowered to the lower limit position in order to cope with the case where a large number of documents G such as about 500 sheets are placed on the paper feed tray 43 .

In step S<b>1 , the control unit 201 determines whether or not an ON signal has been received from the document detection sensor 123 , that is, whether or not the document G has been placed on the paper feed tray 43 . If it is determined in step S1 that an ON signal has been received from the document detection sensor 123, ie, that the document G has been placed on the paper feed tray 43, the process proceeds to step S2. If it is not determined that the ON signal has been received from the document detection sensor 123, the process of step S1 is repeated.

In step S<b>2 , the control unit 201 drives the elevation motor 173 to raise the paper feed tray 43 . As a result, the document G placed on the paper feed tray 43 is lifted. When the paper feed tray 43 rises in this way, the feed roller 103 is pushed up by the uppermost document G, and the holder 101 rotates upward (see FIG. 3).

After that, in step S3, the control unit 201 determines whether or not an ON signal has been received from the upper limit position detection sensor 115, that is, whether or not the paper feed tray 43 has risen to the upper limit position. Until the ON signal is received from the upper limit position detection sensor 115 in step S3, the control unit 201 repeats the process of step S3.

If it is determined in step S3 that an ON signal has been received from the upper limit position detection sensor 115, that is, if it is determined that the paper feed tray 43 has risen to the upper limit position, the process proceeds to step S4. In step S<b>4 , the control unit 201 stops driving the lifting motor 173 . As a result, the paper feed tray 43 stops while the uppermost document G is in contact with the delivery roller 103 . After that, the process proceeds to step S5.

In step S<b>5 , the control unit 201 drives the elevation motor 173 to lower the paper feed tray 43 . As a result, the document G descends and the holder 101 rotates downward.

After that, in step S6, the control unit 201 determines whether an OFF signal has been received from the upper limit position detection sensor 115, that is, whether the paper feed tray 43 has been lowered from the upper limit position. If it is determined that an OFF signal has been received from the upper limit position detection sensor 115, ie, that the paper feed tray 43 has descended from the upper limit position, the process proceeds to step S7. Control unit 201 repeats the process of step S<b>6 until an OFF signal is received from upper limit position detection sensor 115 .

In step 7, the control unit 201 determines whether or not a predetermined time has elapsed after determining that an OFF signal has been received from the upper limit position detection sensor 115, that is, that the paper feed tray 43 has been lowered from the upper limit position. do. The predetermined time is, for example, 300 ms. As a result, the uppermost document G is separated downward from the delivery roller 103 by a predetermined distance. The control unit 201 repeats the process of step S7 until a predetermined time has passed. If the paper feed tray 43 is lowered to the lower limit position before the predetermined time elapses in step S7, the lower limit position detection sensor 177 transmits an ON signal to the controller 201. FIG. The control unit 201 stops driving the lifting motor 173 upon receiving the ON signal.

After the predetermined time has elapsed in step S7, the process proceeds to step S8. In step S8, the control unit 201 stops driving the lifting motor 173 and ends the process.

After the above process is finished, the operation of conveying the document can be started. For example, the user presses a start key provided on an operation panel (not shown) of the image forming apparatus 3 (see FIG. 1) to start the operation of conveying the document G. FIG.

When the start key is pressed, the control unit 201 drives the elevation motor 173 to raise the paper feed tray 43 to the upper limit position. After that, the control unit 201 drives the drive motor 113 to rotate the drive shaft 109a (see FIG. 3), feeds the document G by the feeding roller 103, and conveys the fed document G by the transport belt 105 and the auxiliary roller 107. transport to path 69; The document G conveyed to the conveying path 69 is conveyed to the reading position P by the first to fourth conveying roller pairs 81 , 83 , 85 and 87 . Then, when passing through the reading position P, the image of the document G is read by the document reading device 5 . After that, the document G is transported along the discharge path 73 by the fifth transport roller pair 95 , discharged from the discharge port 71 by the discharge roller pair 97 , and stacked on the discharge tray 45 .

As described above, according to the present invention, by appropriately selecting the time after the upper limit position detection sensor 115 stops detecting the paper feed tray 43, after the document G is placed on the paper feed tray 43, Before starting the document conveying operation (before the start key is pressed), the uppermost document G can be moved downward away from the delivery roller 103 . Therefore, for example, when a manuscript is to be added or replaced before the start key is pressed, the manuscript G does not come into contact with the feeding roller 103, so that the manuscript G is not damaged. and wear of the delivery roller 103 can be prevented.

Further, when the start key is pressed to start the document transport operation, the paper feed tray 43 is raised to a position where the uppermost document G is slightly below the delivery roller 103 . In this manner, the distance between the delivery roller 103 and the document G is shortened, and the distance for raising the paper feed tray 43 can be shortened, so that the document transport operation can be started quickly.

In addition, since the elevation motor 173 generally uses a DC motor, it is difficult to strictly control the position (height) of the paper feed tray 43 by controlling the rotation speed. Therefore, by determining whether to stop the downward movement of the paper feed tray 43 based on the elapsed time after receiving the OFF signal from the upper limit position detection sensor 115 , the paper feed tray 43 is stopped at an appropriate position spaced apart from the delivery roller 103 . can be made

Further, as described above, the holder 101 of the feeding portion 49 swings between the upper limit position and the lower limit position. The top document among the documents G placed on the tray 43 may remain in contact with the feeding roller 103 . That is, even after the OFF signal is received from the upper limit position detection sensor 115 , the uppermost document among the documents G placed on the paper feed tray 43 may remain in contact with the delivery roller 103 .

Therefore, by setting the time (predetermined time) from when the OFF signal is received from the upper limit position detection sensor 115 to when the paper feed tray 43 is stopped is about 300 ms, the paper feed tray 43 is moved below the lower limit position of the holder 101. , and the uppermost document can be separated from the delivery roller 103 .

In the present embodiment, the predetermined time may be changeable according to user settings. In this case, for example, the operation panel of the image forming apparatus 1 is provided with an input unit capable of inputting a predetermined time, and a desired elapsed time is input to the input unit. Alternatively, an adjustment unit is provided to lengthen or shorten the predetermined elapsed time. For example, if the predetermined time is set to 0, the feed roller 103 remains in contact with the document G, and the paper feed tray 43 stops. Alternatively, the delivery roller 103 remains in contact with the document G even when the paper feed tray 43 stops within the swinging range of the holder 101 . In this case, since it is not necessary to raise the paper feed tray 43 when starting the document conveying operation, the document conveying operation can be started more quickly.

Although the invention has been described with respect to certain embodiments, the invention is not limited to the above embodiments. Those skilled in the art can modify the above embodiments without departing from the scope and spirit of the present invention.

7 Document transport device 43 Paper feed tray 45 Ejection tray 69 Transport path 103 Delivery roller 115 Upper limit position detection sensor 123 Document detection sensor 125 Lifting mechanism

Claims (3)

A paper feed tray on which documents are stacked and which can be raised and lowered;
a document detection sensor that detects the presence or absence of the document on the paper feed tray;
a discharge tray provided below the paper feed tray;
a transport path along which the document is transported from the paper feed tray to the discharge tray via a reading position;
a feed roller that rotates in contact with the originals stacked on the paper feed tray to feed the originals onto the transport path;
The paper feed tray is moved between an upper limit position where the stacked documents are pressed against the delivery roller and the delivery roller is raised to a predetermined paper feed height, and a lower limit position spaced downward from the delivery roller. a lifting mechanism for lifting and lowering;
an upper limit position detection sensor that detects that the paper feed tray has risen to the upper limit position;
When the document detection sensor detects the document during standby in which the document transport operation is not executed, the elevating mechanism raises the paper feed tray to the upper limit position and then lowers it so that the upper limit position detection sensor detects the document. wherein the elevating mechanism stops the paper feeding tray after a predetermined time has elapsed since the detection of the paper feeding tray ceased. 2. The predetermined time is a time from when the upper limit position detection sensor stops detecting the paper feed tray to when the document on the paper feed tray is separated from the delivery roller. The document conveying device described in . 2. The document conveying apparatus according to claim 1, wherein said predetermined time can be changed.

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