Document carrier device

Abstract

To detect only a document in contact with an elevation wall part and also to avoid misdetection due to reflected light from a delivery roller.SOLUTION: A document carrier device 120 comprises: a paper feed tray 44 where a document is loaded; a paper feed mechanism 31 which feeds the document loaded in the paper feed tray 44 in a predetermined paper feed direction Z; a paper feed tray elevation mechanism which elevates the paper feed tray 44; a top plate part 21 which adjoins the paper feed tray 44 on the downstream side in the paper feed direction Z and contacts with the lower surface of the fed document G; a fixed wall part 23 which is provided below an end part of the top plate part 21 on the upstream side in the paper feed direction Z, and has its position fixed; an elevation wall part 25 which is provided above an end part of the paper feed tray 44 on the downstream side in the paper feed direction Z, and moves up / down together with the paper feed dray 44 along the fixed wall part 23; and a reflection type optical sensor 47 which detects the document G loaded in the paper tray 44, and the reflection type optical sensor 47 emits light not vertically upward, but in a direction inclined to the downstream side in the paper feed direction Z.SELECTED DRAWING: Figure 19

Description

[Technical Field]

[0001] The present invention relates to a document transport device. [Background technology]

[0002] A document transport device that transports a document to a reading position of an image reading device is known. The document transport device includes, for example, a paper feed tray on which the document is loaded, a discharge tray provided below the paper feed tray, and a transport mechanism that transports the document from the paper feed tray to the reading position of the document reading device and then to the discharge tray.

[0003] The convenience of a document transport device increases with the capacity (amount of documents that can be loaded) of the paper feed tray and the discharge tray. Therefore, technologies for realizing a document transport device with a larger capacity have been studied. For example, Patent Document 1 discloses an image reading device including: a supply tray including a movable plate that moves upward as the number of sheets supported in the supply tray decreases; a discharge tray located below the supply tray for supporting discharged sheets; a transport guide for transporting sheets from the supply tray to the discharge tray; a discharge unit having a discharge opening for discharging sheets to the discharge tray and moving upward as the number of sheets supported in the supply tray decreases; and a regulating surface provided between the transport guide and the movable plate that can abut against sheets supported in the supply tray, wherein the regulating surface is movable upward as the discharge unit moves. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-131351 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned supply tray is generally provided with a reflective optical sensor that detects documents. The reflective optical sensor needs to detect only documents that are in contact with the above-mentioned regulating surface (hereinafter referred to as the lifting wall). This is because even if the feed roller is driven in response to the detection of a document that is not in contact with the lifting wall, there is a possibility that the document will not be able to be fed. In order to detect only documents that are in contact with the lifting wall, it is desirable to install the reflective optical sensor as close to the lifting wall as possible. However, a feed roller is provided above the reflective optical sensor. If the reflective optical sensor is positioned to emit light vertically upward, there is a risk of false detection occurring due to the light being reflected by the feed roller.

[0006] SUMMARY OF THE INVENTION In consideration of the above circumstances, an object of the present invention is to detect only a document that is in contact with a lifting wall portion and to avoid erroneous detection due to light reflected from a feed roller. [Means for solving the problem]

[0007] In order to solve the above problem, the document transport device of the present invention comprises a paper feed tray on which documents are loaded, a paper feed mechanism that feeds the documents loaded on the paper feed tray in a predetermined paper feed direction, a paper feed tray lifting mechanism that raises and lowers the paper feed tray, a top plate portion adjacent to the paper feed tray on the downstream side of the paper feed direction and with which the underside of the document being fed comes into contact, a fixed wall portion that is provided below the upstream end of the top plate portion in the paper feed direction and is fixed in position, a lifting wall portion that is provided above the downstream end of the paper feed tray in the paper feed direction and rises and falls together with the paper feed tray along the fixed wall portion, and a reflective optical sensor that detects the documents loaded on the paper feed tray, wherein the reflective optical sensor emits light in a direction that is inclined downstream in the paper feed direction rather than vertically upward.

[0008] The paper feed mechanism may include a feed roller that feeds the documents loaded on the paper feed tray in the paper feed direction, the feed roller including a shaft and a roller body attached to the shaft, and the reflective optical sensor may be provided at a position different from the roller body in a width direction intersecting the paper feed direction, and may emit light downstream of the shaft in the paper feed direction.

[0009] The lifting wall may include a groove that is aligned with the optical path of the reflective optical sensor.

[0010] The fixed wall portion is provided at intervals along the upstream end of the top plate portion in the paper feed direction, and includes a plurality of convex portions that protrude toward the paper feed tray and have a hollow structure with an open lower end, and a plurality of concave portions that are provided alternately with the plurality of convex portions, and the lifting wall portion is provided with a plurality of convex portion fitting portions that fit inside the plurality of convex portions and a plurality of concave portion fitting portions that fit inside the plurality of concave portions, and the groove may be provided in any one of the plurality of concave portion fitting portions.

[0011] The document transport device includes an output tray located below the paper feed tray and onto which the documents fed by the paper feed mechanism are discharged, an output document sensor that detects the documents discharged to the output tray, and a control unit that controls the paper feed tray lifting mechanism, and the control unit may drive the paper feed tray lifting mechanism when the output signal of either the reflective optical sensor or the output document sensor changes. [Effects of the Invention]

[0012] According to the present invention, it is possible to detect only the document that is in contact with the lifting wall portion, and to avoid erroneous detection due to light reflected from the feed roller. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a front view schematically illustrating an internal configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2]1 is a perspective view showing the appearance of a document transport device according to an embodiment of the present invention; [Figure 3] FIG. 2 is a front view schematically showing a paper feed mechanism and a transport mechanism according to an embodiment of the present invention. [Figure 4] FIG. 2 is a front view schematically showing a conveyance mechanism and a paper feed tray lifting mechanism according to an embodiment of the present invention. [Figure 5] FIG. 2 is a rear view schematically showing the paper feed tray lifting mechanism according to the embodiment of the present invention. [Figure 6] FIG. 2 is a front view schematically showing a conveyance mechanism and a paper feed tray lifting mechanism according to an embodiment of the present invention. [Figure 7] FIG. 2 is a perspective view showing a fixed wall portion, a liftable wall portion, and a paper feed tray. [Figure 8] FIG. 2 is a perspective view showing a fixed wall portion, a liftable wall portion, and a paper feed tray. [Figure 9] FIG. 2 is a perspective view showing a fixed wall portion, a liftable wall portion, and a paper feed tray. [Figure 10] FIG. 2 is an exploded view showing the fixed wall portion and the liftable wall portion. [Figure 11] FIG. 2 is an exploded view showing the fixed wall portion and the liftable wall portion. [Figure 12] FIG. 2 is a perspective view showing the front of a fixed wall portion, a liftable wall portion, a paper feed tray, and a discharge tray. [Figure 13] FIG. 2 is a perspective view showing a cross section of the front portion of the lift-up wall portion, the paper feed tray, and the discharge tray. [Figure 14] FIG. [Figure 15] FIG. [Figure 16] FIG. 4 is a perspective view showing a cross section of an engagement portion. [Figure 17] FIG. 2 is a cross-sectional view showing a paper feed mechanism, a fixed wall portion, a liftable wall portion, and a paper feed tray. [Figure 18] FIG. 2 is a cross-sectional view showing a paper feed mechanism, a fixed wall portion, a liftable wall portion, and a paper feed tray. [Figure 19] FIG. 2 is a cross-sectional view showing a paper feed mechanism, a fixed wall portion, a liftable wall portion, and a paper feed tray. [Figure 20] FIG. 2 is a cross-sectional view showing a paper feed mechanism and a paper feed tray. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a document transport device 120 and an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0015] First, the overall configuration of image forming apparatus 100 will be described. Fig. 1 is a front view that schematically shows the internal configuration of image forming apparatus 100. In the following description, the front side of the paper in Fig. 1 is the front side (front side) of image forming apparatus 100, and left and right directions will be described based on the direction when image forming apparatus 100 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr represent up, down, left, right, front, and rear, respectively.

[0016] The image forming apparatus 100 includes a printer 1, a scanner 110, and a document feeder 120. The scanner 110 is provided above the printer 1, and the document feeder 120 is provided above the scanner 110. The document feeder 120 feeds a document G via a reading position A of the scanner 110. The scanner 110 is a flatbed image scanner that reads the document G and generates image data. The printer 1 forms an image based on the image data on a sheet S. Note that, although this embodiment illustrates an example in which the printer 1 forms an image using an electrophotographic method, the printer 1 may also be configured to form an image using another method (for example, an inkjet method).

[0017] The printer 1 includes a rectangular parallelepiped main body housing 3. At the bottom inside the main body housing 3 are a paper feed cassette 4 that stores sheets S, and a paper feed roller 5 that feeds sheets S from the paper feed cassette 4 to the right. Above the paper feed cassette 4 is an imaging device 6 that forms a toner image using an electrophotographic method, and above and to the right of the imaging device 6 is a fixing device 7 that fixes the toner image to the sheet S. Above the fixing device 7 are an ejection roller 8 that ejects the sheet S with the fixed toner image, and an ejection tray 9 on which the ejected sheet S is stacked.

[0018] Inside the main body housing 3, there is provided a conveyance path 10 that runs from the paper feed roller 5 through the image forming device 6 and the fixing device 7 to the discharge roller 8. The conveyance path 10 is mainly formed of plate-like members that face each other with a gap therebetween to allow the sheet S to pass through, and conveyance rollers 17 that sandwich and convey the sheet S are provided at multiple locations in the conveyance direction Y. A registration roller 18 is provided upstream of the image forming device 6 in the conveyance direction Y. To the right of the fixing device 7, there is provided a reversing conveyance path 10R that branches off from the conveyance path 10 downstream of the fixing device 7 in the conveyance direction Y and merges with the conveyance path 10 upstream of the registration roller 18 in the conveyance direction Y.

[0019] The control unit 2 includes a calculation unit and a storage unit (not shown). The calculation unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit performs various processes by reading and executing control programs stored in the storage unit. Note that the control unit 2 may be realized by an integrated circuit only, without using software.

[0020] A display operation unit (not shown) is provided on the front side of the scanner 110. The display operation unit includes a display panel, a touch panel superimposed on the display surface of the display panel, and a keypad adjacent to the display panel (not shown). The control unit 2 displays screens showing operation menus and statuses of the printer 1 and scanner 110 on the display panel, and controls each part of the printer 1 and scanner 110 in response to operations detected by the touch panel and keypad.

[0021] The basic image formation operation of the printer 1 is as follows: When a print job for single-sided printing is input to the printer 1 from the display operation unit or an external computer, the paper feed rollers 5 feed the sheet S from the paper feed cassette 4 to the transport path 10, the registration rollers 18, which have stopped rotating, correct any skew in the sheet S, and the registration rollers 18 feed the sheet S to the image creating device 6 at a predetermined timing. The image creating device 6 forms a toner image on the sheet S using an electrophotographic method. Next, the fixing device 7 fuses the toner image onto the sheet S while clamping and transporting the sheet S, and the discharge rollers 8 discharge the sheet S onto the discharge tray 9. In the case of double-sided printing, the sheet S with the toner image fixed on its first side is sent into the transport path 10 via the reverse transport path 10R, where the toner image is transferred to the second side.

[0022] [scanner] The scanner 110 comprises a first carriage 81 equipped with a light source and a reflecting mirror, a second carriage 82 equipped with two reflecting mirrors, a lens 83 that focuses the light, an image sensor 84 that converts the focused light into image data, and a contact glass 85 on which the original G is placed.

[0023] The basic document reading operation of the scanner 110 is as follows: When a user places a document G on the top surface of the contact glass 85 and gives a reading command to the scanner 110, the first carriage 81 moves to the right at a speed V, and in conjunction with this, the second carriage 82 moves to the right at a speed V / 2. During this time, the light source irradiates light onto the document G, and the light reflected by the document G is reflected by the reflecting mirrors of the first carriage 81 and the second carriage 82 and directed to the lens 83, where it is imaged on the imaging element 84 and converted into an image signal. The image signal is output to the control unit 2 of the printer 1 and converted into image data.

[0024] [Document transport device] Next, the document transport device 120 will be described. Fig. 2 is a perspective view showing the appearance of the document transport device 120. Fig. 3 is a front view schematically showing the paper feed mechanism 31 and the transport mechanism 32. Figs. 4 and 6 are front views schematically showing the transport mechanism 32 and the paper feed tray lifting / lowering mechanism 33. Fig. 5 is a rear view schematically showing the paper feed tray lifting / lowering mechanism 33. Of these, Figs. 3, 4, and 5 show the paper feed tray 44 positioned near the upper limit position, and Fig. 6 shows the paper feed tray 44 positioned near the lower limit position.

[0025] The document transport device 120 (see FIGS. 2 and 3) has a flat, generally rectangular bottom 40 and a first wall 41 and a second wall 42 that face each other in the front-to-rear direction (the width direction intersecting the document feed direction Z of the document G). The rear edge of the bottom 40 is hinged to the rear of the contact glass 85 (see FIG. 1) of the scanner 110. The bottom 40 also functions to hold down the document G on the contact glass 85. The first wall 41 extends from the left end of the front edge of the bottom 40 to the center. The second wall 42 extends across the entire rear edge of the bottom 40. The cover 46 covers the upper and left sides of the space between the first wall 41 and the second wall 42. The lower left end of the cover 46 is hinged to the left end of the bottom 40.

[0026] [Paper Tray] The paper feed tray 44 (see FIGS. 2 and 3) is provided to the right of the center in the left-right direction of the document transport device 120 and in front of the second wall portion 42. The paper feed tray 44 is a plate-shaped member that is inclined so that the left side is lower. A pair of cursors 45 that align the front-to-rear edges of the document G are provided on the top surface of the paper feed tray 44. The cursors 45 are slidable in the front-to-rear direction.

[0027] [Output tray] The discharge tray 43 is provided below the paper feed tray 44. The discharge tray 43 is integral with the bottom portion 40.

[0028] [Paper feed mechanism] The paper feed mechanism 31 (see FIG. 3) is provided in the space between the first wall portion 41 and the second wall portion 42. The paper feed mechanism 31 has a box-shaped holder 53 that is open at the bottom. Inside the holder 53, a feed roller 51, a driven roller 55, a drive roller 52, and a retard roller 57 are arranged with their axial direction aligned in the front-to-rear direction. The driven roller 55 is provided to the left of the feed roller 51. The drive roller 52 is provided to the left of the driven roller 55. The endless belt 56 is wound around the drive roller 52 and the driven roller 55. The retard roller 57 is pressed against the underside of the lower part of the endless belt 56.

[0029] The front and rear ends of the drive shaft 54 ​​of the drive roller 52 are supported by the first wall portion 41 and the second wall portion 42, and are connected to a drive unit (not shown) including a motor and a reduction gear. The holder 53 is supported by the drive shaft 54 ​​and can swing around the drive shaft 54. The driving force is transmitted from the drive shaft 54 ​​to the feed roller 51 and the retard roller 57 by a transmission mechanism (not shown), such as a gear train or an endless belt.

[0030] Sensor 58 is a transmission or reflection type optical sensor, and is provided on the inner surface of cover part 46. A light shielding plate 59 that protrudes upward or to the side is provided on the upper part of holder 53. Sensor 58 outputs a detection signal to control part 2 at a different level depending on whether light from sensor 58 is blocked by light shielding plate 59 or not.

[0031] [Paper feed tray lifting mechanism] The paper feed tray lifting mechanism 33 (see FIGS. 4 and 5) is provided on the front surface of the first wall portion 41 and the rear surface of the second wall portion 42. The drive pulley 71 and the driven pulley 72 (see FIG. 5) are provided at the upper and lower central portions of the rear surface of the second wall portion 42, respectively. The driven pulley 73 is provided at a height between the drive pulley 71 and the driven pulley 72 and to the left of the drive pulley 71 and the driven pulley 73. The guide pulley 76 is provided above and to the left of the driven pulley 72 and to the right of the driven pulley 73. The endless belt 70 is wound around the drive pulley 71, the driven pulleys 72 and 73, and the guide pulley 76. The drive unit 78 includes a motor 78M, a worm gear 78W, an idler gear 78i, and a drive gear 71G. The drive gear 71G is attached to the shaft of the drive pulley 71.

[0032] The driven pulleys 91, 92, 93 and the guide pulley 96 (see FIG. 4) are provided on the front surface of the first wall portion 41 at positions facing the drive pulley 71, the driven pulleys 72, 73 and the guide pulley 76, respectively. The endless belt 90 is wound around the driven pulleys 91, 92, 93 and the guide pulley 96. The driven pulley 93 and the driven pulley 73 are provided on a common shaft.

[0033] The sliding portion 74 (see FIG. 5) is provided at the left end of the rear edge of the paper feed tray 44. The second wall portion 42 is provided with a slit 42S with the vertical direction as the longitudinal direction. The slit 42S is provided at a position corresponding to the left end of the rear edge of the paper feed tray 44. The sliding portion 74 passes through the slit 42S and is coupled to a portion of the endless belt 70 between the drive pulley 71 and the driven pulley 72.

[0034] A lift guide 75 is provided on the rear surface of the second wall 42. The lift guide 75 is a rail-shaped member with its longitudinal direction extending in the vertical direction. The sliding part 74 is slidable in the vertical direction along the lift guide 75.

[0035] The sliding portion 94 (see FIG. 4) is provided at the left end of the front edge of the paper feed tray 44. The sliding portion 94 is coupled to the endless belt 90 at a portion between the driven pulley 91 and the driven pulley 92.

[0036] An elevation guide portion 95 is provided on the front surface of the first wall portion 41. The elevation guide portion 95 is a rail-shaped member whose longitudinal direction is the up-down direction. The sliding portion 94 is slidable in the up-down direction along the elevation guide portion 95.

[0037] The basic operation of the paper feed tray lifting mechanism 33 is as follows: The driving force generated by the motor 78M is transmitted to the drive gear 71G via the worm gear 78W and the idler gear 78i. The rotation of the drive pulley 71 together with the drive gear 71G causes the endless belt 70 to rotate, which in turn causes the driven pulleys 72 and 73 to rotate. The rotation of the driven pulley 93 together with the driven pulley 73 causes the endless belt 90 to rotate in synchronization with the endless belt 70. Because the paper feed tray 44 is connected to the endless belts 70 and 90 via the sliding portions 74 and 94, the forward and reverse rotation of the motor 78M causes the paper feed tray 44 to move up and down.

[0038] The control unit 2 causes the paper feed tray 44 to rise using the paper feed tray lifting mechanism 33. When the top surfaces of the documents G loaded on the paper feed tray 44 are pressed against the feed roller 51, the holder 53 swings upward. When the holder 53 swings upward by a predetermined amount, the light shielding plate 59 blocks the light from the sensor 58. At this time, an appropriate load acts between the top surfaces of the documents G and the feed roller 51, allowing the feed roller 51 to feed out the documents G. In other words, the control unit 2 controls the paper feed tray lifting mechanism 33 to raise the paper feed tray 44 as the amount of documents G loaded on the paper feed tray 44 decreases.

[0039] [Transport mechanism] The transport mechanism 32 (see FIG. 3) includes a transport path 61 extending from the paper feed mechanism 31 to a discharge roller 69 via an opening 40A, and a plurality of transport rollers 62 arranged on the transport path 61. The transport path 61 is formed primarily of plate-like members facing each other with a gap therebetween that allows the document G to pass through. The opening 40A is a slit with its longitudinal direction extending in the front-to-rear direction, provided in an area of ​​the bottom 40 that faces the first carriage 81 (see FIG. 1) located at the home position. The opening 40A is an example of a reading position A, where the scanner 110 reads the document G. At the reading position A, an opening 61A corresponding to the opening 40A is provided in the plate-like member below the transport path 61, and the underside of the document G being transported is exposed downward through the opening 40A and the opening 61A.

[0040] The transport roller 62 includes a drive roller 62D and a driven roller 62N (see FIG. 3). A driven pulley 63N (see FIG. 4) is provided on the shaft of the drive roller 62D. The drive pulley 63D is connected to a drive unit (not shown) including a motor and a reduction gear. The endless belt 60 is wound around the drive pulley 63D, multiple driven pulleys 63N, and a guide pulley 63G. When the drive pulley 63D is driven, the multiple driven pulleys 63N rotate synchronously as the endless belt 60 rotates, and therefore the multiple transport rollers 62 also rotate synchronously.

[0041] A guide portion 64 (FIG. 3) is provided in a portion of the transport path 61 downstream of the opening 40A in the paper feed direction Z. The guide portion 64 is an integrated pair of plate-shaped members facing each other in the vertical direction, and can swing around the drive roller 62D or driven roller 62N of the transport roller 62 adjacent to the right side of the opening 40A. A description of the mechanism for swinging the guide portion 64 will be omitted.

[0042] [Configuration of fixed wall and lifting wall] Next, the fixed wall portion 23 and the lift-up wall portion 25 will be described. Figures 7 to 9 are perspective views showing the fixed wall portion 23, the lift-up wall portion 25, and the paper feed tray 44. Of these, Figure 7 shows the lift-up wall portion 25 and the paper feed tray 44 in their lowest positions. Figure 8 shows the lift-up wall portion 25 in their highest position, and the paper feed tray 44 in their intermediate position. Figure 9 shows the lift-up wall portion 25 in their highest position, and the paper feed tray 44 in their highest position. Figures 10 and 11 are exploded views showing the fixed wall portion 23 and the lift-up wall portion 25.

[0043] The document transport device 120 includes a paper feed tray 44 on which documents G are loaded, a paper feed mechanism 31 that feeds the documents G loaded on the paper feed tray 44 in a predetermined paper feed direction Z, a paper feed tray lifting mechanism 33 that raises and lowers the paper feed tray 44, a top plate portion 21 that is adjacent to the paper feed tray 44 on the downstream side in the paper feed direction Z and that comes into contact with the underside of the document G being fed, a fixed wall portion 23 that is provided below the upstream end of the top plate portion 21 in the paper feed direction Z and has a fixed position, and a lifting wall portion 25 that is provided above the downstream end of the paper feed tray 44 in the paper feed direction Z and that rises and falls together with the paper feed tray 44 along the fixed wall portion 23.

[0044] [Top panel] The top panel 21 (see FIGS. 7 to 11) is disposed generally horizontally. An opening 21A is provided in the center of the top panel 21 in the front-to-rear direction. The retard roller 57 included in the paper feed mechanism 31 described above is disposed in the opening 21A. The document G fed by the feed roller 51 is transported along the upper surface of the top panel 21 while the lower surface of the document G contacts the upper surface of the top panel 21.

[0045] [Fixed wall] The fixed wall portion 23 is a rectangular member whose longitudinal direction is the front-to-rear direction as a whole, and is provided in an upright position downward from the upstream end of the top panel portion 21 in the paper feed direction Z and is integrated with the top panel portion 21. The fixed wall portion 23 includes a plurality of protrusions 23T1, 23T2, 23T3, 23T4, 23T5, 23T6, and 23T7 and a plurality of recesses 23U1, 23U2, 23U3, 23U4, 23U5, and 23U6. The plurality of protrusions 23T1 to 23T7 are provided at intervals along the upstream end of the top panel portion 21 in the paper feed direction Z, protrude toward the paper feed tray 44, and have a hollow structure with an open lower end. The plurality of recesses 23U1 to 23U6 are provided alternately with the plurality of protrusions 23T1 to 23T7. From the front side, the convex portion 23T1, the concave portion 23U1, the convex portion 23T2, the concave portion 23U2, the convex portion 23T3, the concave portion 23U3, the convex portion 23T4, the concave portion 23U4, the convex portion 23T5, the concave portion 23U5, the convex portion 23T6, the concave portion 23U6, and the convex portion 23T7 are arranged in this order.

[0046] The multiple protrusions 23T1 to 23T7 are formed in a generally rectangular parallelepiped shape with a smaller horizontal dimension than the vertical dimension. The upper ends of the multiple protrusions 23T1 to 23T7 and the multiple recesses 23U1 to 23U6 are inclined so that the height increases downstream in the paper feed direction Z. The shapes and dimensions of the multiple protrusions 23T1 to 23T7 may be different from each other as shown in the figures, or may be the same. Furthermore, the shapes and dimensions of the multiple recesses 23U1 to 23U6 may be different from each other as shown in the figures, or may be the same.

[0047] [Restriction section] The wall portion 23W is provided in an upright position downward from both the front and rear ends of the top plate portion 21. The wall portion 23W is integrated with the top plate portion 21 and the fixed wall portion 23. The limiting portion 23R is a slit provided in the wall portion 23W along the up-down direction. The upper end of the limiting portion 23R is closed, and the lower end is open.

[0048] [Lifting wall section] The bottom plate 26 faces the top plate 21 below the top plate 21. The lift-up wall 25 is provided in an upright position extending upward from the upstream end of the bottom plate 26 in the paper feed direction Z and is integrated with the bottom plate 26. The lift-up wall 25 includes a plurality of protrusion fitting portions 25T1, 25T2, 25T3, 25T4, 25T5, 25T6, and 25T7 and a plurality of recess fitting portions 25U1, 25U2, 25U3, 25U4, 25U5, and 25U6. The protrusion fitting portions 25T1, 25T2, 25T3, 25T4, 25T5, 25T6, and 25T7 fit into the insides of the protrusions 23T1, 23T2, 23T3, 23T4, 23T5, 23T6, and 23T7, respectively. The recessed portion fitting portions 25U1, 25U2, 25U3, 25U4, 25U5, and 25U6 fit into the insides of the recessed portions 23U1, 23U2, 23U3, 23U4, 23U5, and 23U6, respectively. As the paper feed tray 44 moves up and down, the protruding portion fitting portions 25T1 to 25T7 slide along the protruding portions 23T1 to 23T7, and the recessed portion fitting portions 25U1 to 25U6 slide along the recessed portions 23U1 to 23U6.

[0049] End The front and rear end portions 25E of the lift-up wall portion 25 are inserted into the aforementioned limiting portion 23R and slide along the limiting portion 23R. Because the upper end portion of the limiting portion 23R is closed, the lift-up wall portion 25 stops moving upward when the end portion 25E comes into contact with the upper end portion of the limiting portion 23R. When the end portion 25E comes into contact with the upper end portion of the limiting portion 23R, the upper end portion of the lift-up wall portion 25 becomes flush with the upper end portion of the fixed wall portion 23. The protrusions 25B protrude in the front-rear direction from the front and rear end portions 25E of the lift-up wall portion 25.

[0050] [Biasing member] The biasing member 27 (see FIGS. 10 and 11) is a tension coil spring arranged in an upright position between the top plate portion 21 and the bottom plate portion 26. The upper end of the biasing member 27 is attached to the underside of the top plate portion 21, and the lower end is attached to the upper surface of the bottom plate portion 26. Because the top plate portion 21 is fixed, the bottom plate portion 26 and the lift-up wall portion 25 are biased upward.

[0051] [Engagement part] Fig. 12 is a perspective view showing the front portions of the fixed wall portion 23, the lift-up wall portion 25, the paper feed tray 44, and the discharge tray 43. Fig. 13 is a perspective view showing cross sections of the front portions of the lift-up wall portion 25, the paper feed tray 44, and the discharge tray 43. Fig. 14 is a perspective view showing the discharge tray 43. Fig. 15 is a perspective view showing the engagement portion 44R. Fig. 16 is a perspective view showing a cross section of the engagement portion 44R.

[0052] The engagement portions 44R (see Figures 12, 13, 15, and 16) protrude in the paper feed direction Z from both the front and rear ends of the downstream end of the paper feed tray 44 in the paper feed direction Z. In the figures, only the front engagement portion 44R is shown, but the rear engagement portion 44R is configured in the same way. The engagement portion 44R has a recess 44G that opens downward. By accommodating the protrusion 25B of the lift-up wall portion 25 in the recess 44G, the engagement portion 44R engages with the protrusion 25B.

[0053] As described above, the lift-up wall portion 25 is biased upward by the biasing member 27, so that the protrusion 25B is pressed against the recess 44G. This configuration restricts the lift-up wall portion 25 from rising, and the lift-up wall portion 25 is kept protruding upward by a predetermined height from the downstream end of the paper feed tray 44 in the paper feed direction Z.

[0054] [Restriction on lowering of output tray] The discharge tray 43 (see FIG. 14) includes a main body 43M, walls 43W1 and 43W2, and downward restriction portions 43T1 and 43T2. The document G discharged from the discharge roller 69 is stacked on the main body 43M. The wall 43W1 is provided over a predetermined range including the left end of the front edge of the main body 43M. The wall 43W2 is provided over substantially the entire rear edge of the main body 43M. The document G discharged from the discharge roller 69 passes through the space between the wall 43W1 and the wall 43W2.

[0055] The left ends of the upper edges of the wall portions 43W1 and 43W2 are provided with downward restriction portions 43T1 and 43T2, respectively (see FIGS. 12 to 14). In other words, the downward restriction portions 43T1 and 43T2 are provided outside the space through which the document G discharged from the discharge roller 69 passes. The downward restriction portions 43T1 and 43T2 protrude upward. The upper ends of the downward restriction portions 43T1 and 43T2 are formed approximately horizontally. The downward restriction portion 43T1 is disposed below the front protrusion 25B. The downward restriction portion 43T2 is disposed below the rear protrusion 25B.

[0056] Next, the operation of this embodiment will be described. When the lift-up wall portion 25 is located at the lowest position (see FIG. 7), the upper end of the lift-up wall portion 25 is located slightly higher than the lower end of the fixed wall portion 23, so that no gap is formed in the vertical direction between the lift-up wall portion 25 and the fixed wall portion 23. In this case, the height of the wall formed by the lift-up wall portion 25 and the fixed wall portion 23 is maximized, and the capacity of the paper feed tray 44 (the amount of documents G that can be loaded) is maximized. Furthermore, when the lift-up wall portion 25 is located at the lowest position, a clearance is provided between the protrusion 25B and the downward restriction portions 43T1 and 43T2, so that the protrusion 25B does not come into contact with the downward restriction portions 43T1 and 43T2.

[0057] Because the lifting wall 25 is urged upward by the urging member 27, when the sheet feed tray 44 is raised by the sheet feed tray lifting mechanism 33, the lifting wall 25 also rises together with the sheet feed tray 44. At this time, the convex portion fitting portions 25T1 to 25T7 of the lifting wall 25 slide along the convex portions 23T1 to 23T7 of the fixed wall 23, and the concave portion fitting portions 25U1 to 25U6 of the lifting wall 25 slide along the concave portions 23U1 to 23U6 of the fixed wall 23.

[0058] When both front and rear ends 25E of the lift-up wall 25 come into contact with the upper end of the limiting portion 23R (see FIG. 8), the lift-up wall 25 stops rising and reaches the upper limit position. At this time, the paper feed tray 44 is located at an intermediate position between the lower limit position and the upper limit position. When the paper feed tray 44 rises further, the recess 44G of the engaging portion 44R separates from the protrusion 25B of the lift-up wall 25, and only the paper feed tray 44 rises.

[0059] When the paper feed tray 44 reaches its upper limit position (see FIG. 9), the downstream end of the top surface of the paper feed tray 44 in the paper feed direction Z is positioned slightly lower than the top surface of the top plate 21. In this case, the height of the wall formed by the lift-up wall 25 and the fixed wall 23 is minimized, and the capacity of the paper feed tray 44 is minimized. As described above, the upper ends of the convex portions 23T1 to 23T7 and concave portions 23U1 to 23U6 of the fixed wall 23 are inclined so that the downstream side in the paper feed direction Z is higher, so that the document G is smoothly fed from the paper feed tray 44 toward the top plate 21.

[0060] When the paper feed tray 44 starts to descend from the upper limit position and reaches the intermediate position (see FIG. 8), the recess 44G of the engagement portion 44R comes into contact with the protrusion 25B of the lift-up wall portion 25. When the paper feed tray 44 further descends, the recess 44G presses down the protrusion 25B, and the lift-up wall portion 25 descends together with the paper feed tray 44.

[0061] According to the above configuration, the wall formed by the fixed wall 23 and the lift-up wall 25 positions the downstream end of the document G in the paper feed direction Z. As the paper feed tray 44 is lowered, the height of the wall increases, thereby increasing the capacity of the paper feed tray 44. Therefore, the capacity of the paper feed tray 44 can be increased without increasing the vertical size of the wall of the paper feed tray 44 downstream in the paper feed direction Z. As a result, the height of the discharge opening through which the document G is discharged to the discharge tray 43 can be changed over a wide range, thereby enabling an increase in the capacity of the discharge tray 43. Furthermore, since the multiple convex engaging portions 25T1 to 25T7 slide against the multiple convex portions 23T1 to 23T7 and the multiple concave engaging portions 25U1 to 25U6 slide against the multiple concave portions 23U1 to 23U6, the lift-up wall 25 can be raised and lowered smoothly and in a stable position.

[0062] In the above configuration, the lifting wall portion 25 is suspended from the fixed wall portion 23 via the biasing member 27, but the fixed wall portion 23 does not have the function of restricting the descent of the lifting wall portion 25. Therefore, when an external force (vibration, impact, etc.) is applied to the document transport device 120, the lifting wall portion 25 may swing up and down, and depending on the magnitude of the external force, the biasing member 27 may come off. In such a case, however, the descent restricting portions 43T1 and 43T2 come into contact with the protrusion 25B of the lifting wall portion 25 to restrict the descent of the lifting wall portion 25, thereby preventing the lifting wall portion 25 from falling off.

[0063] According to the document transport device 120 of the present embodiment described above, there are provided a sheet feed tray 44 on which the documents G are stacked, a sheet feed mechanism 31 that feeds the documents G stacked on the sheet feed tray 44 in a predetermined sheet feed direction Z, a discharge tray 43 that is provided below the sheet feed tray 44 and onto which the documents G fed by the sheet feed mechanism 31 are discharged, a sheet feed tray lifting mechanism 33 that lifts and lowers the sheet feed tray 44, and a sheet feed mechanism 34 that is adjacent to the sheet feed tray 44 on the downstream side in the sheet feed direction Z and onto which the documents G are fed. The discharge tray 43 includes a top panel 21 with which the underside of the document G comes into contact, a fixed wall 23 that is provided below the upstream end of the top panel 21 in the paper feed direction Z and is fixed in position, and a lifting wall 25 that is provided above the downstream end of the paper feed tray 44 in the paper feed direction Z and moves up and down along the fixed wall 23 together with the paper feed tray 44, and the discharge tray 43 includes descent restriction portions 43T1 and 43T2 that contact the lifting wall 25 to restrict the descent of the lifting wall 25. This configuration makes it possible to prevent the lifting wall 25 from falling off.

[0064] Furthermore, according to the document transport device 120 of this embodiment, the downward restriction units 43T1 and 43T2 are provided outside the space through which the document G passes. This configuration makes it possible to prevent the downward restriction units 43T1 and 43T2 from interfering with the passage of the document G.

[0065] Furthermore, according to the document transport device 120 of this embodiment, the descent restriction portions 43T1 and 43T2 do not come into contact with the lifting wall portion 25 when the paper feed tray 44 is located at the lower limit position of the lifting range of the paper feed tray lifting mechanism 33. This configuration makes it possible to avoid collision between the lifting wall portion 25 and the descent restriction portions 43T1 and 43T2 when the paper feed tray 44 reaches the lower limit position.

[0066] Furthermore, the document transport device 120 according to this embodiment includes protrusions 25B protruding from both ends of the lift-up wall 25 in the width direction intersecting with the paper feed direction Z, an engagement portion 44R provided on the paper feed tray 44, positioned above the protrusions 25B, and engaging with the protrusions 25B, and a biasing member 27 that biases the lift-up wall 25 upward. With this configuration, by engaging the engagement portion 44R with the protrusions 25B from above, the biasing member 27 presses the protrusions 25B against the engagement portion 44R, thereby lifting and lowering the lift-up wall 25 together with the paper feed tray 44. Furthermore, the lift-up wall 25 and the paper feed tray 44 can be assembled by the simple operation of engaging the engagement portion 44R with the protrusions 25B from above. Furthermore, by integrally molding the protrusions 25B with the lift-up wall 25, the number of parts can be reduced. Furthermore, by integrally molding the engagement portion 44R with the paper feed tray 44, the number of parts can be reduced.

[0067] Furthermore, according to the document transport device 120 of this embodiment, the fixed wall portion 23 is provided with a plurality of convex portions 23T1 to 23T7 arranged at intervals along the upstream end of the top plate portion 21 in the paper feed direction Z, protruding toward the paper feed tray 44, and having a hollow structure with an open lower end, and a plurality of concave portions 23U1 to 23U6 arranged alternately with the plurality of convex portions 23T1 to 23T7, and the lifting wall portion 25 is provided with a plurality of convex portion fitting portions 25T1 to 25T7 that fit inside the plurality of convex portions 23T1 to 23T7, and a plurality of concave portion fitting portions 25U1 to 25U6 that fit inside the plurality of concave portions 23U1 to 23U6. According to this configuration, the plurality of convex engaging portions 25T1 to 25T7 slide against the plurality of convex portions 23T1 to 23T7, and the plurality of concave engaging portions 25U1 to 25U6 slide against the plurality of concave portions 23U1 to 23U6, so that the lifting wall portion 25 can be raised and lowered smoothly and in a stable posture.

[0068] In the case of this configuration, in the assembly work, the multiple protrusion fitting portions 25T1 to 25T7 are inserted into the multiple protrusions 23T1 to 23T7 from below, but if a configuration for restricting the descent of the lift-up wall portion 25 is provided on the fixed wall portion 23 side, the assembly work becomes complicated. In contrast, in this embodiment, the descent restriction portions 43T1 and 43T2 are provided on the discharge tray 43, so the ease of the assembly work is not impaired.

[0069] [Reflective optical sensor] 17 to 19 are cross-sectional views showing the paper feed mechanism 31, fixed wall 23, lift-up wall 25, and paper feed tray 44. Of these, FIG. 17 shows the lift-up wall 25 and paper feed tray 44 in their lowest positions. FIG. 18 shows the lift-up wall 25 in their highest position and the paper feed tray 44 in their intermediate position. FIG. 19 shows the lift-up wall 25 in their highest position and the paper feed tray 44 in their highest position. FIG. 20 is a cross-sectional view showing the paper feed mechanism 31 and the paper feed tray 44.

[0070] The reflective optical sensor 47 includes a light-emitting element and a light-receiving element (not shown), and detects the originals G loaded on the paper feed tray 44 by the light-receiving element receiving the reflected light of the light emitted by the light-emitting element. An opening 44A is provided at the end of the upper surface of the main body 44M on the downstream side in the paper feed direction Z (see FIGS. 7 to 9 and 17 to 20). The reflective optical sensor 47 is provided in the opening 44A. The reflective optical sensor 47 is embedded at a position lower than the upper surface of the main body 44M so as not to obstruct the passage of the originals G. The light emitted by the light-emitting element is emitted through the opening 44A.

[0071] The reflective optical sensor 47 needs to detect only the document G that is in contact with the lift-down wall portion 25. This is because even if the feed roller 51 is driven in response to the detection of the document G that is not in contact with the lift-down wall portion 25, there is a possibility that the document G will not be able to be fed out. In order to detect only the document G that is in contact with the lift-down wall portion 25, it is desirable to install the reflective optical sensor 47 as close to the lift-down wall portion 25 as possible.

[0072] However, a feed roller 51 is provided above the reflective optical sensor 47. If the reflective optical sensor 47 were positioned to emit light vertically upward, the light could be reflected by the feed roller 51, resulting in a false detection. To prevent false detection, the reflective optical sensor 47 should emit light in a direction that is not reflected by the feed roller 51, i.e., in a direction other than vertically upward. However, if the reflective optical sensor 47 were to emit light in a direction inclined toward the upstream side in the paper feed direction Z, it would detect a document G that is not in contact with the lift-down wall 25. Therefore, in this embodiment, the reflective optical sensor 47 emits light in a direction inclined toward the downstream side in the paper feed direction Z rather than vertically upward (see FIGS. 17 to 20 ). The reflective optical sensor 47 detects the document G within a detection range 47L. This configuration makes it possible to detect only the document G in contact with the lift-down wall 25 and avoid false detection due to light reflected from the feed roller 51.

[0073] The delivery roller 51 includes a shaft 51S and a roller body 51R attached to the shaft 51S. If the roller body 51R were configured to emit light in a direction inclined toward the downstream side in the paper feed direction Z, the inclination angle of the light relative to the vertically upward direction would be large, causing the light to be reflected by the lift-up wall 25. Therefore, in this embodiment, the reflective optical sensor 47 is provided at a different position from the roller body 51R in the width direction intersecting with the paper feed direction Z, and emits light downstream in the paper feed direction Z relative to the shaft 51S (see FIG. 20 ). With this configuration, the inclination angle of the light relative to the vertically upward direction is small, making it possible to avoid reflection of the light by the lift-up wall 25.

[0074] The lift-up wall 25 has a groove 25G that runs along the optical path of the reflective optical sensor 47 (see FIGS. 7 to 9). Specifically, the groove 25G is provided in one of the recessed portion fitting portions 25U1 to 25U6. As an example, in this embodiment, the groove 25G is provided in the recessed portion fitting portion 25U4. This configuration makes it possible to avoid reflection of light on the lift-up wall 25. Furthermore, since the recessed portion fitting portions 25U1 to 25U6 are portions that fit into the recessed portions 23U1 to 23U6 of the fixed wall 23, there is an advantage in that it is easy to ensure a space for the groove 25G.

[0075] In document transport device 120, when reflective optical sensor 47 detects documents G loaded on paper feed tray 44, paper feed tray lifting mechanism 33 lifts paper feed tray 44. When the top surfaces of documents G loaded on paper feed tray 44 reach the upper limit position, light shielding plate 59 blocks the light of sensor 58, detecting that the top surfaces of documents G loaded on paper feed tray 44 have been pressed against feed roller 51, and control unit 2 stops the lifting of paper feed tray 44.

[0076] As described above, the control unit 2 controls the paper feed tray lifting mechanism 33 to lift the paper feed tray 44 as the amount of documents G stacked on the paper feed tray 44 decreases. Specifically, when the stacked documents G are fed out one by one by the feed roller 51, the upper surfaces of the stacked documents G move downward, so that the light shielding plate 59 no longer blocks the light from the sensor 58. When the reflective optical sensor 47 detects the documents G and the light shielding plate 59 no longer blocks the light from the sensor 58, the paper feed tray lifting mechanism 33 lifts the paper feed tray 44 by a predetermined amount. When the upper surfaces of the stacked documents G are pressed against the feed roller 51 and the light shielding plate 59 blocks the light from the sensor 58, the control unit 2 stops the lifting of the paper feed tray 44.

[0077] In addition, when the last sheet of the document G stacked on the paper feed tray 44 is fed out and the reflective optical sensor 47 no longer detects the document G, the control unit 2 causes the paper feed tray lifting mechanism 33 to lower the paper feed tray 44.

[0078] [Document ejection sensor] The discharge tray 43 is provided with a discharged document sensor 65 that detects documents G discharged onto the discharge tray 43 (see FIG. 3). The discharged document sensor 65 may be a sensor of any type, for example, a sensor similar to the reflective optical sensor 47. The level of the output signal from the discharged document sensor 65 changes depending on whether or not a document G is present on the discharge tray 43. The control unit 2 checks the output of the discharged document sensor 65 when the output signal from the reflective optical sensor 47 changes from a level indicating the presence of a document to a level indicating the absence of a document and an operation to lower the paper feed tray 44 is performed.

[0079] When the output signal of discharged document sensor 65 is at a level indicating that a document is present, control unit 2 lowers paper feed tray 44 from the upper limit position shown in Fig. 9 to the intermediate position shown in Fig. 8. Next, when the user removes document G from discharge tray 43 and the output signal of discharged document sensor 65 changes from the level indicating that a document is present to a level indicating that a document is absent, control unit 2 lowers paper feed tray 44 from the intermediate position to the lower limit position shown in Fig. 7.

[0080] The distance between the discharge tray 43 and the paper feed tray 44 when the paper feed tray 44 is positioned at the intermediate position is such that the lower surface of the paper feed tray 44 does not interfere with the upper surface of the discharged document G even when the document G is discharged to the discharge tray 43 in a volume that can be placed on the paper feed tray 44 when the paper feed tray 44 is positioned at the lower limit position.

[0081] When the user places a document G on the paper feed tray 44 with the paper feed tray 44 lowered to the intermediate position or the lowest position and the reflective optical sensor 47 detects the document G, the control unit 2 causes the paper feed tray lifting mechanism 33 to raise the paper feed tray 44 until the light shielding plate 59 blocks the light from the sensor 58, as described above, and starts feeding the document G with the paper feed mechanism 31. When reading jobs for multiple document stacks are to be executed consecutively, the reading job is executed automatically by simply placing the next document stack on the paper feed tray 44 with the paper feed tray 44 lowered to the intermediate position after the reading job for the previous document stack has finished, so multiple reading jobs can be executed efficiently with simple operations.

[0082] The document transport device 120 according to the present embodiment described above includes a paper feed tray 44 on which documents G are loaded, a paper feed mechanism 31 that feeds the documents G loaded on the paper feed tray 44 in a predetermined paper feed direction Z, a paper feed tray lifting mechanism 33 that raises and lowers the paper feed tray 44, a top plate portion 21 adjacent to the paper feed tray 44 on the downstream side in the paper feed direction Z and with which the underside of the fed documents G comes into contact, a fixed wall portion 23 that is provided below the upstream end of the top plate portion 21 in the paper feed direction Z and is fixed in position, a lifting wall portion 25 that is provided above the downstream end of the paper feed tray 44 in the paper feed direction Z and rises and falls together with the paper feed tray 44 along the fixed wall portion 23, and a reflective optical sensor 47 that detects the documents G loaded on the paper tray 44, and the reflective optical sensor 47 emits light in a direction inclined downstream in the paper feed direction Z rather than vertically upward. According to this configuration, it is possible to detect only the document G that is in contact with the lift-up wall portion 25, and it is possible to avoid erroneous detection due to light reflected from the feed roller 51.

[0083] Furthermore, according to the document transport device 120 of this embodiment, the paper feed mechanism 31 includes a feed roller 51 that feeds out the documents G loaded on the paper feed tray 44 in the paper feed direction Z, the feed roller 51 including a shaft 51S and a roller body 51R attached to the shaft 51S, and the reflective optical sensor 47 is provided at a position different from the roller body 51R in the width direction intersecting with the paper feed direction Z, and emits light downstream in the paper feed direction Z from the shaft 51S. With this configuration, it is possible to avoid reflection of light on the lift-up wall 25.

[0084] Furthermore, according to the document transport device 120 of this embodiment, the lifting wall portion 25 has a groove 25G that is aligned with the optical path of the reflective optical sensor 47. With this configuration, reflection of light on the lifting wall portion 25 can be avoided.

[0085] Furthermore, in the document transport device 120 according to this embodiment, the fixed wall 23 is provided at intervals along the upstream end of the top panel 21 in the paper feed direction Z, and includes a plurality of hollow protrusions 23T1 to 23T7 that protrude toward the paper feed tray 44 and have an open lower end, and a plurality of recesses 23U1 to 23U6 that are arranged alternately with the plurality of protrusions 23T1 to 23T7. The lift-up wall 25 includes a plurality of protrusion fitting portions 25T1 to 25T7 that fit inside the plurality of protrusions 23T1 to 23T7 and a plurality of recess fitting portions 25U1 to 25U6 that fit inside the plurality of recesses 23U1 to 23U6. The groove 25G is provided in one of the plurality of recess fitting portions 25U1 to 25U6. This configuration makes it easy to secure a space to serve as the groove 25G.

[0086] Furthermore, the document transport device 120 according to this embodiment includes a discharge tray 43 that is provided below the paper feed tray 44 and onto which the document G fed by the paper feed mechanism 31 is discharged, a discharged document sensor 65 that detects the document G discharged onto the discharge tray 43, and a control unit 2 that controls the paper feed tray lifting / lowering mechanism 33, and the control unit 2 drives the paper feed tray lifting / lowering mechanism 33 when there is a change in the output signal of either the reflective optical sensor 47 or the discharged document sensor 65. According to this embodiment, the user can use the document transport device 120 without performing complicated operations. [Explanation of symbols]

[0087] 21 Top plate 23 Fixed wall section 23T1, 23T2, 23T3, 23T4, 23T5, 23T6, 23T7 convex part 23U1, 23U2, 23U3, 23U4, 23U5, 23U6 recess 25 Lifting wall 25G groove 25T1, 25T2, 25T3, 25T4, 25T5, 25T6, 25T7 Convex mating part 25U1, 25U2, 25U3, 25U4, 25U5, 25U6 Recessed fitting part 31 Paper feed mechanism 33 Paper feed tray lifting mechanism 43 Output tray 44 Paper tray 47 Reflective optical sensor 51 Feed roller 51R roller body 51S axis 65 Document ejection sensor 120 Document transport device G Manuscript Z feed direction

Claims

1. a paper feed tray on which documents are loaded; a paper feed mechanism that feeds the documents loaded on the paper feed tray in a predetermined paper feed direction; a paper feed tray lifting mechanism for lifting and lowering the paper feed tray; a top plate portion adjacent to the paper feed tray on the downstream side in the paper feed direction, with which the underside of the document being fed comes into contact; a fixed wall portion provided below an end portion of the top plate portion on the upstream side in the paper feed direction and fixed in position; a vertically movable wall portion provided above an end portion of the sheet feed tray on a downstream side in the sheet feed direction, the vertically movable wall portion moving up and down together with the sheet feed tray along the fixed wall portion; a reflective optical sensor that detects the document loaded on the paper feed tray, The document transport device is characterized in that the reflective optical sensor emits light in a direction inclined toward the downstream side of the paper feed direction rather than vertically upward.

2. the paper feed mechanism includes a feed roller that feeds the documents loaded on the paper feed tray in the paper feed direction; The feed roller is Axle and a roller body provided on the shaft, 2. The document transport device according to claim 1, wherein the reflective optical sensor is provided at a position different from the roller body in a width direction intersecting the paper feed direction, and emits light downstream of the shaft in the paper feed direction.

3. 3. The document transport device according to claim 1, wherein the elevation wall portion has a groove that is aligned with the optical path of the reflective optical sensor.

4. The fixed wall portion is a plurality of protrusions provided at intervals along an upstream end of the top plate portion in the paper feed direction, protruding toward the paper feed tray, and having a hollow structure with an open lower end; a plurality of recesses provided alternately with the plurality of protrusions, The lifting wall portion is a plurality of protrusion fitting portions that fit inside the plurality of protrusions; a plurality of recess fitting portions that fit inside the plurality of recesses, 4. The document transport device according to claim 3, wherein the groove is provided in one of the plurality of recessed fitting portions.

5. an ejection tray provided below the paper feed tray and onto which the original documents fed by the paper feed mechanism are ejected; a discharged document sensor that detects the document discharged onto the discharge tray; a control unit that controls the paper feed tray lifting mechanism, 2. The document transport device according to claim 1, wherein the control unit drives the paper feed tray lifting mechanism when an output signal from either the reflective optical sensor or the discharged document sensor changes.

Images