Sheet conveyance device, and image processing device including sheet conveyance device

Abstract

To provide a sheet conveyance device which secures safety of a user, and which can quickly raise a discharge part to a position according to a discharge amount of sheets (manuscripts), and to provide an image processing device including the sheet conveyance device.SOLUTION: In an image forming device 100, a control part 2 raises a discharge guide part upward from the lowermost position toward a discharge height position according to a loading amount of manuscripts loaded on a paper discharge tray (S13), and in the case where the discharge guide part has reached a stand-by position P3, the rising of the discharge guide part is stopped (S15, S16).SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a sheet conveying device for conveying a sheet.

Background Art

[0002] There is known a document conveying device that conveys a document (sheet) to a reading position of an image reading device. The document conveying device includes, for example, a paper feed tray on which documents are stacked, a paper discharge tray provided below the paper feed tray, and a conveying mechanism that conveys a document along a conveying path extending from the paper feed tray through a reading position of the document reading device to the paper discharge tray. A paper discharge port is formed at an end portion on the downstream side in the conveying direction of the conveying path, and the document is discharged from the paper discharge port to the paper discharge tray.

[0003] For the document conveying device, the higher the stacking capacity (the amount of documents that can be stacked) of the paper discharge tray, the higher the convenience. To increase the capacity of the paper discharge tray, it is necessary to raise the position of the discharge portion relative to the paper discharge tray. However, simply raising the position of the discharge portion will disrupt the position and posture of the discharged document, making it time-consuming for the user to align the documents taken out from the paper discharge tray. Therefore, conventionally, a technique for raising and lowering the discharge portion to change the discharge position in the vertical direction has been studied. For example, a mechanism in which the discharge portion moves up and down in conjunction with the paper feed tray (see Patent Document 1 and Patent Document 2) has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a conventional document conveyance device that employs a configuration in which the discharge unit is moved up and down independently without being linked to the paper feed tray, there are cases where documents are placed on the discharge tray when the conveyance of documents on the paper feed tray is not in progress, i.e., in a standby state. In this case, the control unit moves the discharge unit upward according to the amount of documents on the discharge tray. In this case, for example, with a user's finger inserted into the gap between the frame located near the paper feed tray or the paper feed tray itself and the discharge unit, the discharge unit rises, and there is a risk that the user's finger will be pinched and injured. On the other hand, in order to prevent this, in the standby state where the conveyance of documents on the paper feed tray is not in progress, for safety reasons, it is conceivable to lower the discharge unit to the lower position regardless of the amount of documents on the discharge tray. For example, there are cases where the next document conveyance process is performed with a large number of documents remaining on the discharge tray. In this case, if the interval between the paper feed tray or the like and the discharge unit is made too large for safety reasons, it will take a long time for the discharge unit to rise, and the timing of starting the conveyance of documents on the paper feed tray will have to be delayed.

[0006] An object of the present invention is to provide a sheet conveyance device capable of quickly raising a discharge unit to a position corresponding to the discharge amount of sheets (documents) while ensuring user safety, and an image processing apparatus including the sheet conveyance device.

Means for Solving the Problems

[0007] A sheet conveying device according to one aspect of the present invention includes a feeding tray on which sheets are stacked, a discharge tray provided below the feeding tray, a conveying mechanism that conveys the sheets along a conveying path from the feeding tray to the discharge tray, a discharge guide that extends from a discharge port formed at a downstream end in the conveying direction of the sheets in the conveying path to the upstream side in the conveying direction, a lifting mechanism that includes a driving unit for lifting and lowering the discharge guide in the vertical direction, a control unit that drives the driving unit to control the lifting and lowering of the discharge guide, and a sensor that detects the amount of the sheets stacked on the discharge tray. The control unit raises the discharge guide according to the amount of the sheets detected by the sensor, and stops the raising of the discharge guide when the discharge guide reaches a first discharge position spaced a predetermined distance downward from the lower surface of the feeding tray.

[0008] An image processing apparatus according to another aspect of the present invention includes the sheet conveying device and an image processing unit that performs image processing on the sheets conveyed by the sheet conveying device.

Advantages of the Invention

[0009] According to the present invention, it is possible to ensure the safety of the user and quickly raise the discharge guide to a position corresponding to the discharge amount of the sheets (documents).

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. Note that the embodiments described below are merely examples embodying the present invention, and do not limit the technical scope of the present invention.

[0012] FIG. 1 is a diagram showing the internal configuration of an image forming apparatus 100 including a document conveying apparatus 120 according to an embodiment of the present invention. Note that the document conveying apparatus 120 is an example of the sheet conveying apparatus of the present invention. Further, the image forming apparatus 100 is an example of the image processing apparatus of the present invention.

[0013] Hereinafter, the front side (front side) of the image forming apparatus 100 will be the front side (front side) of the drawing in FIG. 1, and the left and right directions will be described with reference to the direction when the image forming apparatus 100 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate up, down, left, right, front, and rear, respectively.

[0014] The image forming apparatus 100 includes a printer 1, a document conveying device 120 that conveys a document G (an example of a sheet in the present invention), a scanner 110 (an example of an image processing unit in the present invention) that performs image reading processing on the document G, and a control unit 2 (an example of a control unit in the present invention) that comprehensively controls these components. The scanner 110 is provided above the printer 1, and the document conveying device 120 is provided above the scanner 110. The document conveying device 120 conveys the document G via the reading position A of the scanner 110. The scanner 110 is a flatbed type image scanner that reads the image of the document G and generates image data. The printer 1 forms an image based on the image data on a sheet S. In this embodiment, an example is shown in which the printer 1 forms an image by an electrophotographic method, but the printer 1 may be configured to form an image by another method (for example, an inkjet method).

[0015] Note that the image processing apparatus of the present invention may be an image reading apparatus configured by the document conveying device 120 and the scanner 110.

[0016] The printer 1 includes a rectangular parallelepiped main body housing 3. Inside the lower part of the main body housing 3, a paper feed cassette 4 for accommodating the sheet S and a paper feed roller 5 for feeding the sheet S to the right from the paper feed cassette 4 are provided. Above the paper feed cassette 4, an image forming device 6 for forming a toner image by an electrophotographic method is provided, and above the upper right of the image forming device 6, a fixing device 7 for fixing the toner image on the sheet S is provided. Above the fixing device 7, a discharge roller 8 for discharging the sheet S on which the toner image is fixed and a discharge tray 9 on which the discharged sheets S are stacked are provided.

[0017] Inside the main body housing 3, a conveyance path 10 is provided that extends 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 by plate-like members that face each other with a gap for passing the sheet S therebetween. A plurality of conveyance rollers 17 that sandwich and convey the sheet S are provided at appropriate intervals along the conveyance path 10. 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, a reverse conveyance path 10R is provided that branches off from the conveyance path 10 downstream of the fixing device 7 in the conveyance direction Y and merges into the conveyance path 10 upstream of the registration roller 18 in the conveyance direction Y.

[0018] 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 provided over the display surface of the display panel, and a keypad adjacent to the display panel (not shown).

[0019] The control unit 2 controls the operation of the image forming apparatus 100. The control unit 2 causes the display panel to display screens representing the operation menus and statuses of the printer 1 and the scanner 110, and controls each part of the printer 1, the scanner 110, and the document conveyance apparatus 120 according to operations detected by the touch panel and the keypad.

[0020] The basic image forming operation of the printer 1 is as follows. When a single-sided printing job is input to the printer 1 from the display operation unit or an external computer or the like, the paper feed roller 5 sends out the sheet S from the paper feed cassette 4 to the conveyance path 10, the registration roller 18 whose rotation has stopped corrects the skew of the sheet S, and the registration roller 18 sends out the sheet S to the image forming device 6 at a predetermined timing. The image forming device 6 forms a toner image on the sheet S by an electrophotographic method. Subsequently, the fixing device 7 sandwiches and conveys the sheet S while melting the toner image to fix the toner image on the sheet S, and the discharge roller 8 discharges the sheet S to the discharge tray 9. In the case of double-sided printing, the sheet S with the toner image fixed on the first side is fed into the conveyance path 10 via the reverse conveyance path 10R, so that the toner image is transferred to the second side.

[0021] [Scanner 110] Scanner 110 includes a first carriage 81 having a light source and a reflecting mirror, a second carriage 82 having two reflecting mirrors, a lens 83 for imaging light, an image sensor 84 for converting the imaged light into image data, and a contact glass 85 on which a document G is placed.

[0022] The basic document reading operation of Scanner 110 is as follows. When the user places a document G on the upper surface of the contact glass 85 and gives an instruction to Scanner 110 to read, the second carriage 82 moves to the right at a speed of V / 2 in conjunction with the first carriage 81 moving to the right at a speed of V. During this time, the light source irradiates the document G with light, and the reflected light reflected by the document G is reflected by the reflecting mirrors of the first carriage 81 and the second carriage 82 and guided to the lens 83, where it is imaged on the image sensor 84 and converted into an image signal. The image signal is output to the control unit 2 of the image forming apparatus 100 and converted into image data.

[0023] Also, when the user places one or more documents G on the paper feed tray 44 and gives an instruction to Scanner 110 to read, with the first carriage 81 positioned at the home position below the reading position A, Scanner 110 starts feeding the document G by the document conveying apparatus 120. Then, when the document G being conveyed passes through the reading position A, the light source irradiates the document G with light, and the reflected light reflected by the document G is reflected by the reflecting mirrors of the first carriage 81 and the second carriage 82 and guided to the lens 83, where it is imaged on the image sensor 84 and converted into an image signal. The image signal is output to the control unit 2 of the image forming apparatus 100 and converted into image data.

[0024] [Document conveying apparatus 120] Next, the document conveying device 120 will be described. FIG. 2 is a perspective view showing the appearance of the document conveying device 120. FIGS. 3 to 5 are diagrams schematically showing the internal configuration of the document conveying device 120. Here, FIG. 3 shows a state in which the discharge guide portion 66 described later is disposed at the lowest position. FIG. 4 shows a state in which the discharge guide portion 66 is disposed at the upper limit position. FIG. 5 shows a state in which the discharge guide portion 66 is disposed at a standby position P3 (an example of the second setting position of the present invention) above the lowest position P1.

[0025] The document conveying device 120 includes a paper feed tray 44 (an example of the paper feed tray of the present invention), a paper discharge tray 43 (an example of the discharge tray of the present invention), a paper feed mechanism 31, a conveying mechanism 32, a discharge mechanism 36, a lifting mechanism 70 (an example of the lifting mechanism of the present invention), a swing drive amount measuring unit 16 (see FIG. 6), an upper limit detection sensor 19, a paper discharge document sensor 21 (an example of the sensor of the present invention), and a document detection sensor 22. The paper feed mechanism 31, the conveying mechanism 32, and the discharge mechanism 36 are an example of the conveying mechanism of the present invention that conveys a document from the paper feed tray 44 to the paper discharge tray 43.

[0026] In the present embodiment, the control unit 2 (see FIG. 1) controls the discharge guide portion 66 of the discharge mechanism 36 to move in the vertical direction by the lifting mechanism 70 based on the presence or absence of the document G detected by the paper discharge document sensor 21, so that the drop between the discharge port 69 and the upper surface of the document G stacked on the paper discharge tray 43 is within a predetermined range. That is, the control unit 2 moves the discharge guide portion 66 upward until the paper discharge document sensor 21 detects the absence of the document G.

[0027] As shown in FIGS. 2 and 3, the document conveying device 120 has a generally rectangular bottom portion 40 formed in a flat shape, and a first wall portion 41 and a second wall portion 42 that face each other in the front-rear direction (the width direction intersecting the conveying direction Z of the document G). The rear edge portion of the bottom portion 40 is hinged behind the contact glass 85 (see FIG. 1) of the scanner 110. The bottom portion 40 also serves as a pressing plate for pressing the document G on the contact glass 85. The first wall portion 41 is provided from the left end portion to the central portion of the front edge portion of the bottom portion 40. The second wall portion 42 is provided over the entire rear edge portion of the bottom portion 40. The cover portion 46 covers the upper portion and the left side portion of the space between the first wall portion 41 and the second wall portion 42. The lower left end portion of the cover portion 46 is hinged to the left end portion of the bottom portion 40.

[0028] [Paper feed tray 44] The paper feed tray 44 is a document placement portion on which the document G to be conveyed is placed. The paper feed tray 44 is provided on the right side of the center in the left-right direction of the document conveying device 120 and in front of the second wall portion 42. The document G to be conveyed is placed on the paper feed tray 44. The paper feed tray 44 is a plate-like member inclined so that the left side is lower. A plate-like cover frame 47 for preventing the downward exposure of a retard roller 57 described later is provided on the left side of the left end portion of the paper feed tray 44. Both the front and rear end portions of the cover frame 47 are fixed to the first wall portion 41 and the second wall portion 42 (see FIG. 2). A paper feed wall portion 47A extending in the vertical direction is provided at the right end portion of the cover frame 47. The leftward movement of the document G stacked on the paper feed tray 44 is restricted by this paper feed wall portion 47A. Note that the cover frame 47 may be a holder for holding the retard roller 57 from below.

[0029] A pair of cursors 45 for aligning the front and rear end portions of the document G are provided on the upper surface of the paper feed tray 44. The cursors 45 are slidable in the front-rear direction.

[0030] [Paper discharge tray 43] The paper discharge tray 43 is a document storage unit that stores the document G discharged through the conveyance path 61 and the discharge path 65 on the stacking surface. The paper discharge tray 43 is provided below the paper feed tray 44. The paper discharge tray 43 is integral with the bottom portion 40. An inclined surface that slopes downward on the left side is provided at the center of the paper discharge tray 43 in the left-right direction.

[0031] [Paper feed mechanism 31] The paper feed mechanism 31 takes out the document G placed on the paper feed tray 44 one by one and feeds it to the conveyance path 61. As shown in FIG. 3, the paper feed mechanism 31 is provided in the space between the first wall portion 41 and the second wall portion 42. The paper feed mechanism 31 includes a box-shaped holder 53 with an open lower portion. Inside the holder 53, a feed roller 51, a driven roller 55, a drive roller 52, an endless belt 56, and a retard roller 57 are arranged with the front-rear direction as the axial 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 lower surface of the lower portion of the endless belt 56.

[0032] Both 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. The drive shaft 54 is 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 is swingable about the drive shaft 54. The driving force of the drive shaft 54 is transmitted 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.

[0033] A sensor 58 is provided on the inner surface of the cover portion 46. The sensor 58 is used to detect that the original document G is placed on the paper feed tray 44 and the approximate number or bulk of the placed original document G. The sensor 58 is, for example, a transmissive or reflective optical sensor. When the sensor 58 is a transmissive optical sensor, a light shielding plate 59 protruding upward or laterally is provided above the holder 53. Also, when the sensor 58 is a reflective optical sensor, a reflector is provided above the holder 53.

[0034] When no original document G is placed on the paper feed tray 44, the holder 53 holds the posture in which the roller surface of the feed roller 51 abuts on the upper surface of the paper feed tray 44. When one or a plurality of original documents G are placed on the paper feed tray 44 and the leading end of the original document G is pressed toward the feed roller 51 side, the feed roller 51 is lifted upward by the leading end portion of the original document G, and thereby, the holder 53 is also displaced upward.

[0035] When the sensor 58 is transmissive, due to the upward displacement of the holder 53, the light shielding plate 59 enters the detection area of the sensor 58. The amount of entry is proportional to the amount of the original document G placed on the paper feed tray 44. The sensor 58 outputs a document detection signal with a signal level corresponding to the amount of entry of the light shielding plate 59 to the control unit 2. The control unit 2 can determine that the original document G is placed on the paper feed tray 44 and the approximate number or bulk of the placed original document G based on the signal level of the document detection signal.

[0036] [Conveying mechanism 32] The conveying mechanism 32 further conveys the original document G sent out by the paper feeding mechanism 31 to the downstream side in the conveying direction. The conveying mechanism 32 includes a conveying path 61 formed in a U-shaped curve that curves from the paper feeding mechanism 31 via the opening 40A to the upper right of the opening 40A, and a plurality of conveying roller pairs 62 arranged along the conveying path 61.

[0037] The conveyance path 61 is mainly formed by plate-like members facing each other with a gap through which the original document G can pass. The opening 40A is provided in a region of the bottom 40 that faces the first carriage 81 (see FIG. 1) located at the home position. The opening 40A is a slit having the longitudinal direction in the front-rear direction. The opening 40A is an example of a reading position A where the scanner 110 reads the original document G. At the reading position A, an opening 61A corresponding to the opening 40A is provided in the plate-like member below the conveyance path 61, and the lower surface of the original document G being conveyed is exposed downward through the opening 40A and the opening 61A.

[0038] The pair of conveyance rollers 62 includes a drive roller 62D and a driven roller 62N. The shaft of each drive roller 62D is connected to a drive unit (not shown) including a motor and a reduction gear. When the motor of the drive unit is driven, the plurality of pairs of conveyance rollers 62 also rotate synchronously.

[0039] [Discharge mechanism 36] The discharge mechanism 36 further conveys the original document G conveyed through the conveyance path 61 to the downstream side in the conveyance direction and discharges the original document G to the paper discharge tray 43. The discharge mechanism 36 includes a discharge path 65 extending from near the downstream end of the conveyance path 61 in the conveyance direction to the paper discharge tray 43, a discharge guide portion 66 (an example of the discharge guide of the present invention) forming the discharge path 65, a pair of conveyance rollers 67 disposed at the upstream end of the discharge path 65 in the conveyance direction, and a pair of discharge rollers 68 disposed at the downstream end of the discharge path 65 in the conveyance direction.

[0040] The discharge guide portion 66 extends from the discharge port 69 opened at the downstream end of the discharge path 65 to the upstream side in the conveyance direction and reaches near the opening 61A.

[0041] The discharge path 65 is formed by the discharge guide portion 66 having a gap through which the original document G passes. The discharge guide portion 66 is composed of plate-like guide members 66A and 66B facing each other with the gap provided therebetween.

[0042] The conveying roller pair 67 is rotatably supported at the upstream end of the guide members 66A and 66B in the conveying direction. The discharge roller pair 68 is rotatably supported at the downstream end of the guide members 66A and 66B in the conveying direction. The conveying roller pair 67 includes a driving roller 67D supported by the upper guide member 66A and a driven roller 67N supported by the lower guide member 66B. The discharge roller pair 68 includes a driven roller 68N supported by the guide member 66A and a driving roller 68D supported by the guide member 66B. The driving rollers 67D and 68D are connected to a driving unit (not shown) including a motor and a reduction gear. A discharge port 69 through which the document G is discharged is formed in the contact area between the driving roller 68D and the driven roller 68N of the discharge roller pair 68.

[0043] [Lifting mechanism 70] The lifting mechanism 70 is a mechanism that vertically moves the discharge guide portion 66 together with the discharge mechanism 36. The lifting mechanism 70 includes a swing shaft 71, an eccentric cam 72, and a driving unit 73 (see FIG. 6). The swing shaft 71 is provided at the upstream end of the discharge path 65 in the conveying direction with the front-rear direction as the axial direction. In the present embodiment, the driving shaft of the conveying roller pair 67 also serves as the swing shaft 71, but the driven shaft of the conveying roller pair 67 may also serve as the swing shaft 71, or a swing shaft 71 different from the driving shaft and the driven shaft of the conveying roller pair 67 may be provided on the guide members 66A and 66B. The eccentric cam 72 is rotatable about a cam shaft 72A having the front-rear direction as the axial direction. The driving unit 73 is a driving source such as a motor. The cam shaft 72A is connected to the output shaft of the driving unit 73. The sliding surface of the eccentric cam 72 is in contact with the lower surface of the lower guide member 66B.

[0044] When a driving force in, for example, the forward rotation direction is input from the drive unit 73 to the camshaft 72A, the eccentric cam 72 rotates in the forward rotation direction in response to the driving force, and by this rotation operation, a force is applied to the discharge mechanism 36 in a direction to push it upward. As a result, the discharge mechanism 36 swings upward about the swing shaft 71. Along with this swinging operation, the position of the discharge port 69 moves upward. Also, when a driving force in, for example, the reverse rotation direction is input from the drive unit 73 to the camshaft 72A, the eccentric cam 72 rotates in the reverse rotation direction in response to the driving force, and by this rotation operation, the eccentric cam 72 rotates in a direction away from the discharge mechanism 36. As a result, the discharge mechanism 36 swings downward about the swing shaft 71 due to its own weight. Along with this swinging operation, the position of the discharge port 69 moves downward.

[0045] [Swing drive amount measurement unit 16] The swing drive amount measurement unit 16 (see FIG. 6) is a sensor used to detect the position of the discharge port 69 in the vertical direction. The swing drive amount measurement unit 16 is provided in the lifting mechanism 70. The swing drive amount measurement unit 16 is, for example, an optical rotary encoder and is provided on the camshaft 72A of the eccentric cam 72. The swing drive amount measurement unit 16 outputs a pulse signal indicating the rotation amount of the camshaft 72A. The control unit 2 (see FIG. 1) analyzes the pulse signal to obtain the rotation amount, and calculates the position of the discharge port 69 in the vertical direction based on this rotation amount. Note that the rotary encoder may be provided on the output shaft of the motor that drives the eccentric cam 72. Also, the swing drive amount measurement unit 16 may include a calculation unit that calculates the position of the discharge port 69 in the vertical direction based on a pulse signal indicating the rotation amount of the camshaft 72A.

[0046] [Upper limit detection sensor 19] The upper limit detection sensor 19 (see FIG. 3) is a sensor that detects the discharge guide portion 66. The upper limit detection sensor 19 is fixed to the lower surface of the cover frame 47. Note that the upper limit detection sensor 19 may be provided at any position as long as it can detect the discharge guide portion 66 that moves upward. The upper limit detection sensor 19 is, for example, a reflective optical sensor having a light emitting element and a light receiving element, and emits light downward (toward the discharge guide portion 66) from the light emitting element. Further, when the light emitted from the light emitting element is reflected by the discharge guide portion 66, the light receiving element of the upper limit detection sensor 19 receives the reflected light. The upper limit detection sensor 19 outputs an electrical signal indicating the presence or absence of light reception in the light receiving element to the control unit 2. Specifically, when the light receiving element receives the reflected light, an ON signal (HIGH level signal) is output to the control unit 2. Further, when the light receiving element does not receive the reflected light, or when the intensity of the received reflected light is less than a predetermined reference value, an OFF signal (LOW level signal) is output to the control unit 2. The control unit 2 detects that the discharge guide portion 66 has approached the lower surface of the cover frame 47 where the upper limit detection sensor 19 is provided based on the signal level of the electrical signal. When the control unit 2 detects that the discharge guide portion 66 has approached the lower surface of the cover frame 47, the upward movement of the discharge guide portion 66 is stopped, and further upward movement of the discharge guide portion 66 is prohibited.

[0047] [Paper discharge original sensor 21] The paper discharge original document sensor 21 is a sensor for detecting the stacking amount of the original document G present on the paper discharge tray 43. The paper discharge original document sensor 21 is provided at the right end of the lower guide member 66B. The paper discharge original document sensor 21 is, for example, a reflection-type optical sensor having a light emitting element and a light receiving element, and emits light from the light emitting element in the right direction (toward the paper discharge tray 43). Further, when the light emitted from the light emitting element is reflected from the side surface (left side surface) of the bundle of original documents G on the paper discharge tray 43, the light receiving element of the paper discharge original document sensor 21 receives the reflected light. The paper discharge original document sensor 21 outputs an electrical signal indicating the presence or absence of light reception in the light receiving element to the control unit 2. Specifically, when the light receiving element receives the reflected light, an ON signal (HIGH level signal) is output to the control unit 2. Further, when the light receiving element does not receive the reflected light, or when the intensity of the received reflected light is less than a predetermined reference value, an OFF signal (LOW level signal) is output to the control unit 2. The control unit 2 determines whether the original document G is located below the discharge port 69 based on the signal level of the electrical signal. That is, the control unit 2 determines that the original document G is located above the discharge port 69 when the light receiving element receives the reflected light, and determines that the original document G is located below the discharge port 69 when the reflected light is not received.

[0048] [Original document detection sensor 22] The original document detection sensor 22 is a sensor used to determine whether the original document G being conveyed through the discharge path 65 has reached the discharge port 69. The original document detection sensor 22 is provided on the lower surface of the upper guide member 66A in the vicinity of the upstream side in the conveyance direction of the discharge port 69. The original document detection sensor 22 is, for example, a reflection-type optical sensor having a light emitting element and a light receiving element. The control unit 2 determines whether the leading end of the original document G in the conveyance direction has passed below the original document detection sensor 22 based on the intensity of the reflected light emitted downward from the light emitting element and reflected by the original document G. The control unit 2 determines that the time when a predetermined time has elapsed after the leading end of the original document G is detected is the time when the original document G has reached the discharge port 69.

[0049] By the way, in a conventional document conveyance device, in a standby state where the document G on the paper feed tray 44 is not being conveyed, the document G may be placed on the paper discharge tray 43. In this case, the paper discharge document sensor 21 detects the document G. In this case, when it is determined by the control unit 2 that the document G is located above the discharge port 69, the discharge guide unit 66 is moved upward by the control unit 2. In this case, with the user's finger caught in the gap between the frame located near the paper feed tray 44 or in its vicinity and the discharge guide unit 66, the discharge guide unit 66 rises, and there is a risk that the user's finger may be pinched and injured. On the other hand, in order to prevent this, in the standby state where the conveyance of the document G is not being performed, regardless of the amount of the document G on the paper discharge tray 43, it is conceivable to lower the discharge guide unit 66 to the lower position. For example, the next document conveyance process may be performed with a large number of documents G remaining on the paper discharge tray 43. In this case, if the interval between the paper feed tray 44 or the like and the discharge guide unit 66 is made too large for safety, it will take a long time for the discharge guide unit 66 to rise, and the timing of starting the conveyance of the document G on the paper feed tray 44 will have to be delayed.

[0050] In the document conveyance device 120 of the present embodiment, it is possible to quickly raise the discharge guide unit 66 to a position corresponding to the discharge amount of the document G while ensuring the safety of the user.

[0051] [Configuration of Control Unit 2] With reference to FIG. 6, the configuration of the control unit 2 and the lifting control executed by the control unit 2 will be described. As shown in FIG. 6, the control unit 2 is a microcomputer composed of a CPU 101, a ROM 102, a RAM 103, a storage unit 104, etc. The CPU 101 performs various processes by reading and executing control programs stored in storage devices such as the ROM 102 and the storage unit 104. The storage unit 104 is a non-volatile storage device such as a flash memory, and stores information and data (position information of the discharge guide unit 66, conveyance path length of the document G, conveyance speed of the document G, etc.) used for various processes. The control unit 2 may be realized by an IC such as an ASIC without using a control program or software.

[0052] The control unit 2 comprehensively controls the image forming apparatus 100. Hereinafter, the control unit 2 will be described as controlling the vertical movement of the discharge guide unit 66 of the document conveyance apparatus 120.

[0053] The control unit 2 raises and lowers the discharge guide unit 66 based on a signal obtained from the upper limit detection sensor 19 or the discharged document sensor 21.

[0054] In the present embodiment, the control unit 2 raises and lowers the discharge guide unit 66 between the lowest position P1 (the position shown in FIG. 3) and the upper limit position P2 (the position shown in FIG. 4). Further, the control unit 2 performs control to lower the discharge guide unit 66 to the lowest position P1 and standby at that position in a state where an execution signal for conveying the document on the paper feed tray 44 is not input. Further, when a predetermined condition is satisfied, the control unit 2 performs control to move the discharge guide unit 66 to a predetermined standby position P3 defined above the lowest position P1. The position information of each of the above-described positions P1 and P3 is stored in, for example, the storage unit 104 of the control unit 2.

[0055] Here, the lowest position P1 is an initial position where the discharge guide unit 66 is arranged before the conveyance of the document G is executed. Specifically, it is a position where the position of the discharge port 69 is the lowest in the vertical movement range of the discharge guide unit 66. The lowest position P1 is a position where the document G can be discharged to the discharge tray 43 without disturbing the document G when the conveyance of the document is executed in a state where the document G is not stacked on the discharge tray 43.

[0056] Further, the upper limit position P2 is the position where the upper limit detection sensor 19 detects the discharge guide portion 66, is a position where the document G to be discharged in a state where the discharge of the document G is possible does not contact the lower surface of the cover frame 47, and is a position where the discharge guide portion 66 is arranged at the highest position in the vertical movement range. Specifically, it is the position where the position of the discharge port 69 is the highest. The upper limit position P2 is a position where the gap D between the upper end portion on the downstream side of the discharge guide portion 66 and the paper feed tray 44 or the cover frame 47 becomes infinitely small in order to sufficiently secure the stacking amount of the document G in the paper discharge tray 43. For example, the gap D is set to a position where the fingers of the user or maintenance worker cannot enter.

[0057] Further, the standby position P3 is an example of the second set position of the present invention. The standby position P3 is a position above the lowest position P1 and is a position spaced downward by a predetermined interval from the lower surface of the paper feed tray 44 or the cover frame 47. The predetermined interval is an interval such that the fingers of the user or maintenance worker can be inserted into the gap D (see FIG. 5) between the upper end portion on the downstream side of the discharge guide portion 66 and the paper feed tray 44 or the cover frame 47. The gap D is, for example, about 20 mm. The standby position P3 may be determined, for example, at a position lower by a specified length (for example, 20 mm) from the upper limit position P2.

[0058] In this embodiment, when the control unit 2 detects a predetermined trigger signal, it controls to raise the discharge guide unit 66 from the lowest position P1 toward a predetermined discharge height position (an example of the first position of the present invention). The trigger signal is, for example, the ON signal output from the paper discharge original document sensor 21 when the paper discharge original document sensor 21 detects an original document in a standby state where the conveyance of the original document G is not being performed. Then, when the discharge guide unit 66 reaches the standby position P3 before the paper discharge original document sensor 21 stops detecting the original document G, the control unit 2 stops the raising of the discharge guide unit 66 and arranges the discharge guide unit 66 at the standby position P3. At this time, if the paper discharge original document sensor 21 stops detecting the original document before the discharge guide unit 66 reaches the standby position P3, the raising of the discharge guide unit 66 is stopped at that position (discharge height position), and the discharge guide unit 66 is arranged at that position. Note that the position when the paper discharge original document sensor 21 stops detecting the original document G is the discharge height position of the discharge guide unit 66 determined according to the amount of the original document G stacked on the paper discharge tray 43, and is an example of the first set position of the present invention.

[0059] Here, it is assumed that when the paper discharge original document sensor 21 stops detecting the original document G on the paper discharge tray 43, the raising of the discharge guide unit 66 is stopped at that position. However, in order to ensure that the original document G can be appropriately discharged onto the paper discharge tray 43 without being disturbed, after the paper discharge original document sensor 21 stops detecting the original document G on the paper discharge tray 43, the discharge guide unit 66 may be raised by a predetermined distance and then the raising of the discharge guide unit 66 may be stopped. This distance is a position where the drop between the discharge port 69 and the upper surface of the original document G stacked on the paper discharge tray 43 becomes a predetermined specified value. For example, it is a position where the discharge port 69 is above the height position of the upper surface of the original document G by a specified length (for example, 10 mm).

[0060] The trigger signal is, for example, the ON signal output when the paper discharge original document sensor 21 detects the original document G on the paper discharge tray 43 in the standby state where the conveyance of the original document G on the paper feed tray 44 is not being performed. However, a document detection sensor may be provided on the paper discharge tray 43, and the signal output when this sensor detects the presence of a document from the absence of a document may be used as the trigger signal.

[0061] Further, in the present embodiment, the control unit 2 performs control to raise the discharge guide unit 66 to a position where the discharge original document sensor 21 no longer detects the original document G on the condition that the original document conveyance operation for conveying the original document G from the paper feed tray 44 to the discharge tray 43 is started.

[0062] Furthermore, while the discharge guide unit 66 is rising to a position where the discharge original document sensor 21 no longer detects the original document G on the discharge tray 43, when it is determined that the original document G conveyed from the paper feed tray 44 to the discharge tray 43 has reached the discharge port 69, the control unit 2 temporarily stops the conveyance of the original document G. In this case, if the image reading process of the original document G has not been completed, the image reading process is also temporarily interrupted. After that, when the discharge guide unit 66 is raised to a position where the discharge original document sensor 21 no longer detects the original document, the conveyance of the original document G is restarted. Note that the determination process as to whether the original document G has reached the discharge port 69 is performed as follows. For example, while the discharge guide unit 66 is rising to a position where the discharge original document sensor 21 no longer detects the original document G, when the original document sensor 22 (see FIG. 3) provided near the upstream side in the conveyance direction of the discharge port 69 detects the original document G being conveyed, the control unit 2 determines that the original document G has reached the discharge port 69.

[0063] [Lift control process (processing example 1)] Hereinafter, with reference to the flowchart of FIG. 7, an example of the procedure of the lifting control process of the discharge guide unit 66 executed by the control unit 2 will be described. In the flowcharts of each figure, steps S11, S12, ··· indicate the process step (step) numbers. In the following description, it is assumed that the lifting control process is executed when a plurality of original manuscripts G are conveyed to the original manuscript conveying device 120 in the image reading process of a plurality of original manuscripts G. Further, hereinafter, it is assumed that the discharge guide unit 66 is arranged at the lowermost position P1 before the conveyance of the original manuscript G. Further, hereinafter, a processing example using the above-described discharged original manuscript sensor 21 as a sensor for detecting the presence or absence or the stacking amount of the original manuscript G on the paper discharge tray 43 will be described. Further, in the following description, it is assumed that a plurality of original manuscripts G with a predetermined thickness are placed on the paper discharge tray 43 before the conveyance operation of the original manuscript G on the paper feed tray 44 is performed.

[0064] Note that the execution order of each step in the lifting control process may be different as long as the same operational effects are produced.

[0065] Further, the control unit 2 includes not only the CPU 101 but also, for example, a plurality of CPUs. In this case, each step of the lifting control process may be executed in a distributed manner by the plurality of CPUs.

[0066] Further, the present invention can be regarded as an invention of a method in which one or a plurality of steps included in the lifting control process are executed by the CPU 101 of the control unit 2 or another processor, and can also be regarded as a program for causing the CPU 101 of the control unit 2 or another processor to execute each step.

[0067] First, in step S11, the control unit 2 determines whether a plurality of original documents G are placed on the paper feed tray 44. For example, when receiving the original document detection signal output from the sensor 58 when a plurality of original documents G are placed on the paper feed tray 44, the control unit 2 determines whether a plurality of original documents are placed on the paper feed tray 44 based on the signal level of the original document detection signal. Note that the determination process in step S11 is for determining the start timing of the lifting control process. For example, as the start timing, it is also possible to use the setting input signal, the execution signal, etc.

[0068] In the next step S12, the control unit 2 determines whether it has received the ON signal from the discharged original document sensor 21. Note that when the discharge guide portion 66 is located at the lowermost position P1 and furthermore, a plurality of original documents G with a predetermined thickness are placed on the paper discharge tray 43, the discharged original document sensor 21 receives the light reflected from the left side surface of the original document G on the paper discharge tray 43 and outputs the ON signal to the control unit 2.

[0069] In step S12, when receiving the ON signal from the discharged original document sensor 21, the control unit 2 drives and controls the drive unit to raise the discharge guide portion 66 from the lowermost position P1 (S13).

[0070] Before the discharge guide portion 66 reaches the standby position P3, the control unit 2 determines whether the output signal of the discharged original document sensor 21 has changed from the ON signal to the OFF signal (S14). Then, when the control unit 2 determines that the output signal of the discharged original document sensor 21 has changed from the ON signal to the OFF signal (Yes in S14), the control unit 2 stops the ascent of the discharge guide portion 66 (S16). Thereby, the discharge guide portion 66 is arranged at the discharge height position corresponding to the stacking amount of the original documents G on the paper discharge tray 43.

[0071] On the one hand, in step S14, when the output signal of the paper discharge original document sensor 21 remains the ON signal, the control unit 2 determines whether the discharge guide unit 66 has reached the standby position P3. Note that the control unit 2 calculates the rising amount of the discharge port 69 of the discharge guide unit 66 based on the rising speed of the discharge guide unit 66 and the elapsed time after the start of the rise of the discharge guide unit 66, and determines whether the discharge guide unit 66 has reached the standby position P3 based on the rising amount and the height position of the standby position P3.

[0072] Before the output signal of the paper discharge original document sensor 21 changes from the ON signal to the OFF signal, if the control unit 2 determines that the discharge guide unit 66 has reached the standby position P3 (Yes in S15), the control unit 2 stops the rise of the discharge guide unit 66 (S16). Thereby, the discharge guide unit 66 is placed at the standby position P3 and waits at the standby position P3 until the conveyance of the original document G on the paper feed tray 44 is started.

[0073] In step S17, when a document conveyance instruction is input, the control unit 2 determines whether the output signal of the paper discharge original document sensor 21 is the ON signal (S18). If it is determined in step S18 that the output signal of the paper discharge original document sensor 21 is the OFF signal, a series of processes ends. Note that when the output signal of the paper discharge original document sensor 21 is the OFF signal at the time of input of the document conveyance instruction, it means that the discharge height position of the discharge guide unit 66 is lower than the standby position P3.

[0074] If it is determined in step S18 that the output signal of the paper discharge original document sensor 21 is the ON signal, the control unit 2 raises the discharge guide unit 66 from the standby position P3 (S19). Note that when the output signal of the paper discharge original document sensor 21 is the ON signal at the time of input of the document conveyance instruction, it means that the discharge height position of the discharge guide unit 66 is higher than the standby position P3.

[0075] Thereafter, when the output signal of the paper discharge original document sensor 21 changes from the ON signal to the OFF signal (S20), the control unit 2 stops the raising of the discharge guide unit 66 (S21). As a result, the discharge guide unit 66 that had stopped at the standby position P3 before the conveyance of the original document G is moved to the discharge height position after the start of the conveyance of the original document G. Therefore, the original document G is discharged from the discharge guide unit 66 toward the paper discharge tray 43 from an appropriate height position.

[0076] As described above, in the image forming apparatus 100 of the present embodiment, the control unit 2 raises the discharge guide unit 66 upward from the lowermost position P1 toward the discharge height position corresponding to the stacking amount of the original documents G stacked on the paper discharge tray 43, and when the discharge guide unit 66 reaches the standby position P3, stops the raising of the discharge guide unit 66. As a result, even if the discharge height position is above the standby position P3, the further raising is stopped when the discharge guide unit 66 reaches the standby position P3. For this reason, while ensuring the safety of the user, it is possible to quickly raise the discharge guide unit 66 to a position corresponding to the discharge amount of the original document G. Specifically, even if a finger of a user or a maintenance worker enters the gap between the upper end portion on the downstream side of the discharge guide unit 66 and the paper feed tray 44 or the cover frame 47 when the discharge guide unit 66 is raised, the finger will not be pinched by the discharge guide unit 66. Further, after the start of the conveyance of the original document G, the discharge guide unit 66 that had been raised to the standby position P3 is raised toward the discharge height position, so the raising time to the discharge height position is shortened.

[0077] [Lift control process (processing example 2)] As another embodiment of the present invention, the control unit 2 may execute a lift control process according to the flowchart shown in FIG. 8.

[0078] For example, after the process of step S19 described above is executed, the control unit 2 determines whether the document G being conveyed through the discharge path 65 has reached the discharge port 69 (S31). When it is determined that the document G has reached the discharge port 69, the conveyance of the document G is temporarily stopped (S32). Thereafter, when the output signal of the paper discharge document sensor 21 changes from the ON signal to the OFF signal (S33), the control unit 2 stops the raising of the discharge guide unit 66 (S34) and resumes the conveyance of the document G (S35). As a result, before the document G is discharged from the discharge port 69, the discharge guide unit 66 can be raised to the discharge height position. As a result, it is possible to prevent the document G from colliding with the stack of documents on the paper discharge tray 43 when the document G is discharged.

[0079] On the other hand, in step S31, when it is determined that the document G has not reached the discharge port 69, in step S20, it is determined whether the output signal of the paper discharge document sensor 21 has changed from the ON signal to the OFF signal. When it has changed to the OFF signal, the control unit 2 stops the raising of the discharge guide unit 66 (S21). On the other hand, in step S20, when it is determined that the output signal of the paper discharge document sensor 21 remains the ON signal, the process returns to step S31 and the processes after step S31 are executed.

[0080] [Lift control process (processing example 3)] As another embodiment of the present invention, the control unit 2 may execute the lift control process according to the flowchart shown in FIG. 9.

[0081] In step S14 in FIG. 7 or FIG. 8, when the output signal of the paper discharge document sensor 21 remains the ON signal and in step S15, it is determined that the discharge guide unit 66 has not reached the standby position P3, in the next step S41, the control unit 2 determines whether the discharge guide unit 66 has reached the upper limit position P2. And when it is determined that the discharge guide unit 66 has reached the upper limit position P2, the control unit 2 lowers the discharge guide unit 66 from the upper limit position P2 to the standby position P3 below the specified length (S42).

[0082] [Supplementary Note of the Invention] The following is a supplementary note on the outline of the invention extracted from the above-described embodiments. It should be noted that each configuration and each processing function described in the following supplementary note can be arbitrarily combined by making selections.

[0083] [Supplementary Note 1] A feed tray on which sheets are loaded, A discharge tray provided below the feed tray, A transport mechanism for transporting the sheet along a transport path from the feed tray to the discharge tray, A discharge guide extending from the upstream side in the transport direction of the sheet from a discharge port formed at the downstream end in the transport direction of the sheet in the transport path, A lifting mechanism including a drive unit for lifting the discharge guide in the vertical direction, A control unit for driving the drive unit to control the upward movement of the discharge guide, A sensor for detecting the amount of the sheets loaded on the discharge tray, and The control unit lifts the discharge guide toward a first set position according to the amount of the sheets loaded on the discharge tray, and stops the upward movement of the discharge guide when the discharge guide reaches a second set position spaced a predetermined distance downward from the lower surface of the feed tray. A sheet transport device.

[0084] [Supplementary Note 2] The control unit according to Supplementary Note 1, wherein when the first set position is above the second set position, the control unit stops the discharge guide at the second set position.

[0085] [Supplementary Note 3] When the discharge guide stops at the second set position, the control unit raises the discharge guide from the second set position to the first set position on the condition that a sheet transport operation for transporting the sheet from the feed tray to the discharge tray is started. The sheet transport device according to Supplementary Note 1 or 2.

[0086] [Supplementary Note 4] A sheet conveying device according to any one of Supplementary Notes 1 to 3, and an image processing unit that performs image processing on a sheet conveyed by the sheet conveying device. An image processing apparatus comprising.

Explanation of Signs

[0087] 1: Printer 2: Control unit 16: Swing drive amount measurement unit 19: Upper limit detection sensor 21: Paper discharge original document sensor 22: Original document detection sensor 31: Paper feeding mechanism 32: Conveying mechanism 36: Discharge mechanism 43: Paper discharge tray 44: Paper feeding tray 47: Cover frame 58: Sensor 59: Light shielding plate 61: Conveying path 65: Discharge path 66: Discharge guide part 66A: Guide member 66B: Guide member 68: Discharge roller pair 69: Discharge port 70: Lifting mechanism 71: Swing axis 72: Eccentric cam 100: Image forming apparatus 101: CPU 102: ROM 103: RAM 104: Storage unit 110: Scanner 120: Original document conveying device

Claims

1. A feed tray on which a sheet is loaded, A discharge tray provided below the feed tray, A conveying mechanism for conveying the sheet along a conveyance path from the feed tray to the discharge tray, A discharge guide extending from the upstream side in the conveyance direction to a discharge port formed at the downstream end in the conveyance direction of the sheet in the conveyance path, A lifting mechanism including a drive unit for lifting the discharge guide in the vertical direction, A control unit for driving the drive unit to control the upward movement of the discharge guide, A sensor for detecting the amount of the sheet loaded on the discharge tray, and comprising: The control unit: Lifts the discharge guide toward a first set position according to the amount of the sheet loaded on the discharge tray, and stops the upward movement of the discharge guide when the discharge guide reaches a second set position spaced a predetermined distance downward from the lower surface of the feed tray. A sheet conveying device.

2. The control unit stops the discharge guide at the second set position when the first set position is above the second set position. The sheet conveying device according to Claim 1.

3. When the discharge guide is stopped at the second set position, the control unit raises the discharge guide from the second set position to the first set position on the condition that a sheet conveying operation for conveying the sheet from the feed tray to the discharge tray has been started. The sheet conveying device according to Claim 1 or 2.

4. A sheet conveying device according to Claim 1, and An image processing apparatus comprising an image processing unit for performing image processing on the sheet conveyed by the sheet conveying device.

Images