Document transport device and document transport reading device

Abstract

The present invention provides a document transport device that can reliably return the paper feed unit to its initial position, even if it does not have a sensor to detect the opening and closing of the transport cover. [Solution] The document transport device comprises a paper tray, a paper feeding unit 73, an actuator 91 driven by a document set in the paper tray, a sensor 93 that outputs a predetermined signal in response to the drive of the actuator 91, and a control unit that receives the signal output from the sensor 93 and controls the paper feeding unit 73 based on the signal. The control unit returns the paper feeding unit 73 to its initial position if a signal different from the signal output from the sensor 93 is input when a document is set in the paper tray and the actuator 91 is driven.

Description

Technical Field

[0001] The present invention relates to a document conveying apparatus including a paper feeding unit and a document conveying and reading apparatus including the document conveying apparatus.

Background Art

[0002] The document conveying apparatus includes a paper feeding tray on which a document is set, a conveying frame having a conveying path through which the document is conveyed, a paper feeding unit that sends out the document set on the paper feeding tray to the conveying path, and a conveying cover that is provided so as to be rotatable in the vertical direction with respect to the conveying frame and exposes the conveying path by rotating upward.

[0003] The paper feeding unit includes, for example, as described in Patent Document 1, a drive shaft rotatably supported by the conveying cover, a holder rotatably supported by the drive shaft, and a pickup roller rotatably supported by the holder. The upstream end of the holder in the conveying direction is rotatably supported by the drive shaft. The pickup roller is rotatably supported at the downstream end of the holder in the conveying direction.

[0004] In a state where the conveying cover is closed, a drive gear fixed to the drive shaft meshes with an output gear of a motor provided in the conveying frame. When the drive shaft is rotated by the motor, the holder rotates in the vertical direction so as to move up and down between a paper feeding position where the pickup roller abuts against the document set on the paper feeding tray and a retracted position where the holder is separated upward from the document. The paper feeding unit is configured to return to an initial posture in which the holder rotates upward and the pickup roller rises to the retracted position at the start of the paper feeding operation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] As described above, when the paper feed unit is supported by a transport cover, when the transport cover is opened, the drive gear fixed to the drive shaft separates from the output gear. This allows the drive shaft to rotate freely, making it impossible to maintain the paper feed unit in its initial position, and causing the holder to rotate downward. If the holder remains rotated downward, the document will interfere with the pickup roller, preventing the document from being properly placed in the paper tray. For this reason, the above document transport device is equipped with a transport cover open / close detection sensor that detects the opening and closing of the transport cover. When the transport cover open / close detection sensor detects that the transport cover is closed, the drive shaft rotates and the paper feed unit returns to its initial position.

[0007] However, in recent years, efforts have been made to reduce the number of parts to lower costs. As part of this effort, if a sensor to detect the opening and closing of the transport cover is not installed, the holder will remain rotated downwards even when the transport cover is closed. In this case, when setting a document in the paper tray, the pickup roller will interfere with the document, making it impossible to set the document properly.

[0008] In consideration of the above circumstances, the present invention aims to provide a document transport device that can reliably return the paper feed unit to its initial position even when it is not equipped with a sensor for detecting the opening and closing of the transport cover, and a document transport reading device equipped with this document transport device. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides a document transport device comprising: a paper tray on which documents are set; a paper feed unit that feeds the documents set in the paper tray in a predetermined transport direction; an actuator driven by the documents set in the paper tray; a sensor that outputs a predetermined signal in response to the drive of the actuator; and a control unit that receives the signal output from the sensor and controls the paper feed unit based on the signal. The paper feed unit comprises: a drive shaft rotatably supported above the paper feed tray; a holder whose upstream end in the transport direction is rotatably supported on the drive shaft and which is rotatably supported vertically in conjunction with the drive shaft; and a component rotatably supported on the downstream end of the holder in the transport direction, which feeds the documents onto the paper feed tray. The actuator comprises a pickup roller that rotates in contact with a set document, and the actuator comprises a rotating shaft rotatably supported above the paper feed tray, a sensing piece provided integrally with the rotating shaft and hanging down from the rotating shaft by its own weight, which rotates the rotating shaft when pressed by a document set in the paper feed tray, and a light-shielding piece provided integrally with the rotating shaft and hanging down from the rotating shaft by its own weight, which switches the output of the sensor by the rotation of the rotating shaft, and the control unit returns the paper feed unit to its initial position where the pickup roller is separated above the paper feed tray when a signal different from the signal output from the sensor is input when a document is set in the paper feed tray and the actuator is driven.

[0010] The present invention may further include a transport frame having a transport path through which a document set in the paper feed tray is transported, and a transport cover that is rotatable in the vertical direction and rotates upward to expose the transport path, wherein the paper feed unit and the actuator are supported by the transport cover.

[0011] The present invention provides a document transport and reading device comprising: an image reading device that reads an image of a document at a predetermined reading position; and a document transport device that is rotatably supported by the image reading device and transports the document from which the image is read by the image reading device to the reading position. [Effects of the Invention]

[0012] According to the present invention, even without providing a sensor to detect the opening and closing of the transport cover, the paper feeding unit can be automatically returned to its initial position when the transport cover is closed. Therefore, since this sensor is unnecessary, the number of parts and costs can be reduced, and the control and configuration of the document transport device can be simplified. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing a document transport and reading device according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a document transport and reading device according to one embodiment of the present invention. [Figure 3] This is a perspective view of the transport cover of a document transport device according to one embodiment of the present invention, viewed from below. [Figure 4] This is a view from the right side of the document detection mechanism and paper feeding unit in a document transport device according to one embodiment of the present invention. [Figure 5] This is a cross-sectional view of a document detection mechanism and a paper feeding unit in a document transport device according to one embodiment of the present invention, viewed from the front. [Figure 6] This is a perspective view showing the actuator of the document detection mechanism in a document transport device according to one embodiment of the present invention. [Figure 7] This is a perspective view of the paper feeding unit of a document transport device according to one embodiment of the present invention, viewed from below. [Figure 8] This is a block diagram showing the control unit of a document transport device according to one embodiment of the present invention. [Figure 9] This is a perspective view showing a light-shielding piece of an actuator according to a first modified example in a document transport device according to one embodiment of the present invention. [Figure 10] In the document conveying device according to an embodiment of the present invention, it is a perspective view showing a light shielding piece of an actuator according to a second modification.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a document conveying and reading device according to an embodiment of the present invention will be described with reference to the drawings.

[0015] First, referring to FIG. 1, the overall configuration of the document conveying and reading device 1 will be described. FIG. 1 is a perspective view showing the document conveying and reading device 1. Fr, Rr, L, R, Up, and Lo shown in each figure indicate the front, rear, left, right, top, and bottom of the document conveying and reading device 1, respectively.

[0016] The document conveying and reading device 1 includes an image reading device 3 and a document conveying device 5 disposed above the image reading device 3. The left and right rear corners of the lower surface of the document conveying device 5 are connected to the left and right rear corners of the upper surface of the image reading device 3 so as to be rotatable in the vertical direction.

[0017] First, the image reading device 3 will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view showing a part of the document conveying and reading device 1. The image reading device 3 includes a contact glass 11 on which a document is placed, a reading sensor 13 for reading an image of the document, and a sensor moving mechanism 15 for moving the reading sensor 13.

[0018] The contact glass 11 is fitted into the top surface of the housing of the image reading device 3. By rotating the document conveying device 5 upward with respect to the image reading device 3, the contact glass 11 is exposed.

[0019] The reading sensor 13 is, for example, a CIS (Contact Image Sensor). The reading sensor 13 is disposed along the width direction (front-rear direction) of the document below the contact glass 11.

[0020] The sensor movement mechanism 15 moves the reading sensor 13 to multiple positions, including a reading position where the image of the document being transported by the document transport device 5 can be read. The reading position is located below the left end of the contact glass 11. When the document is transported to the reading position by the document transport device 5, the reading sensor 13 reads the image of one side (the front side) of the document. Alternatively, when reading the image of a document placed on the contact glass 11, the sensor movement mechanism 15 moves the reading sensor 13 from the reading start position to the reading end position to read the image of the placed document.

[0021] Next, the document transport device 5 will be described with reference to Figures 1 and 2. The document transport device 5 comprises a base 21, a transport unit 23 provided on the upper left surface of the base 21, a paper feed tray 25 supported by the transport unit 23, and an output tray 27 provided on the upper right surface of the base 21. Documents set in the paper feed tray 25 are transported by the transport unit 23, and after the image is read by the transport unit 23, they are output to the output tray 27.

[0022] First, let's describe the base 21. The base 21 is a rectangular member that is long in the left-right direction, with a rear wall erected along the rear edge. As shown in Figure 2, an opening is formed at the left end of the base 21, along the width direction of the original document. The opening exposes the reading position of the image reading device 3.

[0023] Next, the transport unit 23 will be described with reference to Figures 2 and 3. Figure 3 is a perspective view of the transport cover 33 from below (partially omitted). As shown in Figure 2, the transport unit 23 comprises a transport frame 31 fixed to the upper left surface of the base 21 and a transport cover 33 rotatably supported on the base 21.

[0024] A transport path 35 is formed in the transport unit 23 through which the original document is transported. The transport path 35 is formed in a horizontal U-shape with a downward curved section, from a paper feed opening 37 formed between the transport cover 33, which rotates downward, and the transport frame 31, to an output opening 39 formed between the transport frame 31 and the base 21. The direction in which the original document is transported along the transport path 35 is called the transport direction X. In the following description, the upstream side and the downstream side refer to the upstream and downstream sides of the transport direction X. Specifically, the upstream transport path from the paper feed opening 37 to approximately the center of the curved section is formed along the upper surface of the transport frame 31, and the downstream transport path from approximately the center of the curved section to the output opening 39 is formed along the upper surface of the base 21. The upstream transport path is opened by rotating (opening) the transport cover 33 upward.

[0025] The transport frame 31 will now be described. The transport frame 31 is equipped with a transparent glass plate 41 facing an opening formed in the base 21. Above the glass plate 41, a reading sensor 43 is provided along the width direction of the original document. The reading sensor 43 is, for example, a CIS (contact image sensor). When the original document is transported below the glass plate 41 through the downstream transport path, the reading sensor 43 reads the image of one side (back side) of the original document. Alternatively, the reading sensor 43 and the reading sensor 13 of the image reading device 3 read images of both sides of the original document.

[0026] The transport cover 33 will now be described. The transport cover 33 is supported on the left end of the upper surface of the base 21 so as to be rotatable in the vertical direction about a rotation axis parallel to the front-rear direction. As shown in Figure 3, a plurality of ribs 51 are formed in the document transport area on the inner surface of the transport cover 33 along the transport direction X. Furthermore, a recess 53 is formed on the inner surface of the transport cover 33 in the central part in the front-rear direction, partitioned by front and rear ribs 51F and 51R. A downstream opening 55 is formed in the front rib 51F, and an upstream opening 57 is formed in the rear rib 51R upstream of the downstream opening 55. The plurality of ribs 51 on the rear side of the recess 53 have a downstream notch 59 aligned with the downstream opening 55 in the front-rear direction, and an upstream notch 61 aligned with the upstream opening 57 in the front-rear direction.

[0027] As shown in Figure 2, the transport path 35 is equipped with, in order from the upstream side, a document detection mechanism 71 (not shown in Figure 2, see Figures 4 and 5), a paper feeding unit 73, a separation pad 75, a first transport roller pair 77, a second transport roller pair 79, and an discharge roller pair 81.

[0028] First, the document detection mechanism 71 will be described with reference to Figures 4 and 5. Figure 4 is a view of the document detection mechanism 71 and the paper feed unit 73 from the upstream side (right side), and Figure 5 is a cross-sectional view of the document detection mechanism 71 and the paper feed unit 73 from the front side. The document detection mechanism 71 detects when a document is placed in the paper feed tray 25. The document detection mechanism 71 includes an actuator 91 that is driven by the document placed in the paper feed tray 25, and a sensor 93 that outputs a predetermined signal in response to the drive of the actuator 91.

[0029] First, the actuator 91 will be described with reference to Figure 6. Figure 6 is a perspective view showing the actuator 91. The actuator 91 comprises a rotating shaft 101 and detection pieces 103 and light-shielding pieces 105 provided at both ends of the rotating shaft 101. The rotating shaft 101 has a length of about half the document transport area and has a large-diameter shaft portion 101a and a small-diameter shaft portion 101b. The axes of the large-diameter shaft portion 101a and the axes of the small-diameter shaft portion 101b are parallel to each other and offset in a direction intersecting the axial direction.

[0030] The detection piece 103 protrudes from the end of the large-diameter shaft portion 101a in a direction perpendicular to the axial direction of the large-diameter shaft portion 101a. The detection piece 103 is substantially L-shaped when viewed from the axial direction of the large-diameter shaft portion 101a and has a connecting portion 103a and a detection portion 103b. The connecting portion 103a is formed to extend downstream along the normal direction of the large-diameter shaft portion 101a. The detection portion 103b is provided at the tip of the connecting portion 103a and has a fan shape when viewed from the radial direction of the large-diameter shaft portion 101a. A rib 103c is formed on the outer surface of the detection portion 103b along the outer peripheral edge (the edge along the upstream side). The light-shielding piece 105 protrudes from the end of the small-diameter shaft portion 101b in a direction perpendicular to the axial direction of the small-diameter shaft portion 101b. The light-shielding piece 105 has a fan shape when viewed from the axial direction of the small-diameter shaft portion 101b. The light-shielding piece 105 and the detection piece 103 are slightly separated in the circumferential direction of the rotation axis 101.

[0031] The actuator 91 is supported on the inner surface of the transport cover 33. More specifically, as shown in Figure 3, the rotation axis 101 of the actuator 91 is housed in the upstream notch 61 of the rib 51, and the tip of the rotation axis 101 is inserted into the upstream opening 57 of the rib 51R. The detection piece 103 is located on the rear side of the recess 53, and the light-shielding piece 105 is located on the rear side of the document transport area. It is preferable that the actuator 91 is not subjected to any load by springs or the like. If a load is applied, it is preferable that the magnitude of the load be as small as possible.

[0032] When the transport cover 33 is closed, the detection piece 103 and the light-shielding piece 105 hang down from the rotation axis 101 due to their own weight. As mentioned above, the light-shielding piece 105 and the detection piece 103 are slightly separated in the circumferential direction of the rotation axis 101, so as shown in Figure 5, due to the balance of the weights of the detection piece 103 and the light-shielding piece 105, the detection piece 103 tilts downstream from the rotation axis 101 (not shown in Figure 5), and the light-shielding piece 105 tilts upstream from the rotation axis 101. As a result, the downstream side edge of the light-shielding piece 105 becomes almost vertical.

[0033] Next, the sensor 93 will be described. Sensor 93 is an optical sensor having a light-emitting part and a light-receiving part. Sensor 93 outputs an ON signal when the optical path formed between the light-emitting part and the light-receiving part is blocked, and emits an OFF signal when the optical path is formed.

[0034] The sensor 93 is supported on the rear wall of the base 21 in a position where its optical path is parallel to the rotation axis 101 of the actuator 91. Furthermore, as shown in Figure 4, the sensor 93 is positioned relative to the actuator 91 such that the light-shielding piece 105 of the actuator 91 crosses the optical path when the transport cover 33 is closed.

[0035] When the transport cover 33 is closed and the detection piece 103 and light-shielding piece 105 of the actuator 91 hang down from the rotation shaft 101 due to their own weight (see Figure 5), the light-shielding piece 105 is located on the upstream side of the optical path, and the sensor 93 outputs an OFF signal. When the detection piece 103 is pressed by the document, the rotation shaft 101 (not shown in Figure 5) rotates in the clockwise direction in Figure 5, and the light-shielding piece 105 rotates together with the rotation shaft 101 in the clockwise direction in Figure 5. As a result, the optical path is blocked by the light-shielding piece 105, and the sensor 93 outputs an ON signal. The signal output from the sensor 93 is input to the control unit 501 (see Figure 8).

[0036] Next, the paper feeding unit 73 will be described with reference to Figures 3 to 5 and Figure 7. Figure 7 is a perspective view of the paper feeding unit 73 from below. As shown in Figure 7, the paper feeding unit 73 includes a holder 111, a drive shaft 113 that supports the holder 111 and is rotatably supported by the transport cover 33, a paper feeding roller 115 supported by the drive shaft 113, and a pickup roller 117 supported by the holder 111.

[0037] First, the holder 111 will be described. As shown in Figure 5, the holder 111 has a top plate 121 and front and rear side plates 123 that face each other in the front-rear direction, and has a box-like shape with an open bottom. Downstream shaft holes are coaxially drilled at the downstream ends of the front and rear side plates 123. A pickup roller shaft 125 is fixed between the upstream ends of the front and rear side plates 123.

[0038] Next, the drive shaft 113 will be described. The drive shaft 113 has a length slightly longer than half the width of the document transport area. As shown in Figure 7, a drive gear 131 is fixed to the rear end of the drive shaft 113. The front end of the drive shaft 113 passes through the downstream shaft holes of the front and rear side plates 123 of the holder 111. This allows the holder 111 to rotate vertically around the drive shaft 113. A torque limiter 133 is interposed between the rear side plate 123 of the holder 111 and the drive shaft 113. When the rotation of the holder 111 is not restricted, the torque limiter 133 transmits the rotation of the drive shaft 113 to the holder 111, causing the holder 111 to rotate together with the drive shaft 113. On the other hand, when the rotation of the holder 111 is restricted, the drive shaft 113 rotates freely relative to the holder 111.

[0039] The torque limiter 133 consists of a collar (not shown) fitted onto the drive shaft 113 and rotating integrally with the drive shaft 113, and a coil spring (not shown) supported by the collar. The coil spring is wound around the collar by elastic force. The coil spring rotates integrally with the collar due to the winding force of the coil spring. On the other hand, when the winding force of the coil spring on the collar loosens, the collar rotates freely relative to the coil spring. One end of the coil spring is curved radially in the direction of the collar and protrudes outward from the large diameter portion of the collar. As the coil spring rotates in the forward and reverse directions, one end can engage with the forward and reverse engagement portions (not shown) of the holder 111.

[0040] When the drive shaft 113 rotates in the positive direction R1 (clockwise in Figure 5 and Figure 7), the coil spring rotates together with the collar due to the winding force. When one end of the coil spring engages with the positive engagement portion of the holder 111, the rotational force of the collar, i.e., the drive shaft 113, is transmitted to the holder 111, causing the holder 111 to rotate downward around the drive shaft 113. When the downward rotation of the holder 111 is restricted, the winding force of the coil spring loosens, and the collar rotates freely relative to the coil spring. On the other hand, when the drive shaft 113 rotates in the opposite direction R2 (counterclockwise in Figure 5 and Figure 7), the coil spring also rotates together with the collar due to the winding force. When one end of the coil spring engages with the reverse engagement portion of the holder 111, the rotational force of the collar, i.e., the drive shaft 113, is transmitted to the holder 111, causing the holder 111 to rotate upward around the drive shaft 113. When the upward rotation of the holder 111 is restricted, the coil spring rotates freely relative to the collar. At this time, the winding force of the coil spring increases, causing the collar to slide relative to the coil spring. As a result, the drive shaft 113, which rotates integrally with the collar, is subjected to a load due to friction between the coil spring and the collar.

[0041] Next, the paper feed roller 115 will be described. As shown in Figure 7, the paper feed roller 115 is supported by the drive shaft 113 via a one-way clutch 141. The one-way clutch 141 transmits the rotation of the drive shaft 113 to the paper feed roller 115 when the paper feed roller 115 rotates in the positive direction R1 (clockwise direction in Figure 7). An output gear 143 is fixed coaxially to the rear end face of the paper feed roller 115.

[0042] Next, the pickup roller 117 will be described. The pickup roller 117 is rotatably supported integrally with the pickup roller shaft 125 (see Figure 5), which is fixed to the holder 111. As shown in Figure 7, an input gear 151 is fixed coaxially to the rear end face of the pickup roller 117. The input gear 151 and the output gear 143 of the paper feed roller 115 mesh via three idler gears 153, which are rotatably supported on the inner surface of the rear side plate 123 of the holder 111. As a result, the rotation of the paper feed roller 115 is transmitted to the pickup roller 117, and the paper feed roller 115 and the pickup roller 117 rotate in the same direction.

[0043] As shown in Figure 3, the holder 111 of the paper feed unit 73 is housed in a recess 53 of the transport cover 33. The drive shaft 113 is housed in a downstream notch 59 of the rib 51, and the tip of the drive shaft 113 is inserted into the downstream opening 55 of the rib 51F via a bearing member. The drive gear 131, fixed to the rear end of the drive shaft 113, is located at the rear of the document transport area. When the transport cover 33 is closed, the drive gear 131 meshes with the output gear of the motor 135 (see Figure 8), which is supported by the rear wall of the base 21. When the motor 135 is driven, the drive shaft 113 rotates in the forward direction R1 or the reverse direction R2 via the output gear and the drive gear 131. The motor 135 is electrically connected to the control unit 501 (see Figure 8).

[0044] Next, the separation pad 75 will be described with reference to Figure 2. The separation pad 75 is supported by the transport frame 31 and contacts the paper feed roller 115 from below with elastic force. A separation nip is formed between the separation pad 75 and the paper feed roller 115.

[0045] Next, the first conveyor roller pair 77, the second conveyor roller pair 79, and the discharge roller pair 81 will be described with reference to Figure 2. The first conveyor roller pair 77 is located downstream of the separation nip and comprises a conveyor roller and a driven roller positioned on either side of the conveyor path 35. The second conveyor roller pair 79 is located in the curved portion of the conveyor path 35 and comprises a drive roller and a driven roller positioned on either side of the conveyor path 35. The discharge roller pair 81 is located inside the discharge port 39 and comprises a conveyor roller and a driven roller positioned on either side of the conveyor path 35. The drive roller of the discharge roller pair 81 also serves as the drive roller of the first conveyor roller pair 77.

[0046] Next, the paper feed tray 25 will be described with reference to Figures 1 and 2. The paper feed tray 25 is formed in the shape of a rectangular plate, having a fixed end that is fixed to the transport unit 23 and a free end opposite to the fixed end. The paper feed tray 25 is supported by the transport frame 31 below the paper feed opening 37 in a position that is inclined downward from the free end to the fixed end.

[0047] Next, the discharge tray 27 will be described with reference to Figures 1 and 2. The discharge tray 27 is formed on the upper right surface of the base 21 below the discharge port 39.

[0048] Next, the control unit 501 will be described with reference to Figure 8. Figure 8 is a block diagram showing the control unit 501. The control unit 501 receives an ON signal or an OFF signal from the sensor 93 of the document detection mechanism 71. Furthermore, the control unit 501 is electrically connected to the motor 135 that drives the drive shaft 113 of the paper feed unit 73, and rotates the drive shaft 113 in the forward or reverse direction.

[0049] The paper feeding operation in the document transport device 5 having the above configuration will be explained mainly with reference to Figures 5 and 7. In the standby state, the actuator 91 of the document detection mechanism 71 is maintained in an initial position in which the detection piece 103 and the light-shielding piece 105 hang down from the rotation axis 101 by their own weight. Since the optical path of the sensor 93 is not blocked by the light-shielding piece 105, the sensor 93 outputs an off signal to the control unit 501. The paper feeding unit 73 is also maintained in an initial position in which the holder 111 rotates upward and the pickup roller 117 rises to a retracted position above the paper tray 25. As shown in Figure 5, the detection piece 103 of the actuator 91 of the document detection mechanism 71 is located downstream of the pickup roller 117.

[0050] When a document is placed in the paper tray 25 after passing between the pickup roller 117 and the paper tray 25, the leading edge of the document pushes the detection piece 103 of the actuator 91, causing the rotation shaft 101 to rotate clockwise. As a result, the light-shielding piece 105 rotates clockwise along with the rotation shaft 101. Consequently, the light-shielding piece 105 blocks the light path, and the sensor 93 outputs an ON signal.

[0051] When the control unit 501 receives an ON signal from the sensor 93, it drives the motor 135 to rotate the drive shaft 113 of the paper feed unit 73 in the positive direction R1 (clockwise direction in Figure 5). The rotational force of the drive shaft 113 in the positive direction R1 is transmitted to the holder 111 via the torque limiter 133, and the holder 111 rotates integrally with the drive shaft 113 due to the action of the torque limiter 133. As a result, the holder 111 rotates downward around the drive shaft 113, and descends to a paper feed position where the pickup roller 117 contacts the top surface of the uppermost document set in the paper feed tray 25. After the pickup roller 117 contacts the document, the winding force of the coil spring of the torque limiter 133 on the drive shaft 113 loosens, so the drive shaft 113 rotates freely relative to the coil spring.

[0052] Furthermore, the rotation of the drive shaft 113 is transmitted to the paper feed roller 115 via the one-way clutch 141, causing the paper feed roller 115 to rotate in the forward direction. The rotation of the paper feed roller 115 is transmitted to the pickup roller 117 via the output gear 143, three idler gears 153, and input gear 151. This causes the pickup roller 117 to rotate in the forward direction, and the best document is fed out in the transport direction. The fed-out documents are separated one by one by the separation nip.

[0053] Subsequently, the document is transported along the transport path 35 by the first transport roller pair 77 and the second transport roller pair 79, and at the reading position, the image of one side is read by the reading sensor 43. Alternatively, the images of both sides of the document are read by the reading sensor 43 and the reading sensor 13 of the image reading device 3. After that, the document is discharged from the discharge port 39 by the discharge roller pair 81 via the transport path 35. The document discharged from the discharge port 39 is loaded onto the discharge tray 27.

[0054] When the last document in the paper tray 25 is ejected, the detection piece 103 of the actuator 91 moves away from the document, causing the rotation axis 101 to rotate under its own weight and the actuator 91 to return to its initial position. Then, the light-shielding piece 105 moves away from the optical path, and the sensor 93 outputs an OFF signal to the control unit 501. In this way, the sensor 93 continues to output an ON signal from the time the document is set until the last document is ejected. For example, if the document transport speed is 210 mm / s, the ON signal output time from the time a single A4 landscape document is set until it is ejected is 1 s.

[0055] When the control unit 501 receives an off signal from the sensor 93, it controls the motor 135 to rotate the drive shaft 113 of the paper feed unit 73 in the reverse direction R2 (counterclockwise direction in Figure 5). The rotational force of the drive shaft 113 in the reverse direction R2 is transmitted to the holder 111 via the torque limiter 133, and the torque limiter 133 causes the holder 111 to rotate upward around the drive shaft 113, raising the pickup roller 117. Eventually, the holder 111 comes into contact with the transport cover 33 and its rotation is restricted. When the rotation of the holder 111 is restricted, the collar of the torque limiter 133 rotates freely against the coil spring. At this time, the winding force of the coil spring increases, causing the collar to slide against the coil spring. As a result, the drive shaft 113, which rotates together with the collar, is subjected to a load due to friction between the coil spring and the collar, and the load applied to the drive shaft 113 from the motor 135 fluctuates. In other words, the load increases and the motor current increases. When the control unit 501 detects the increase in motor current, it stops the rotation of the motor 135.

[0056] Thus, after the paper feeding operation is completed, the paper feeding unit 73 returns to its initial position. Furthermore, the paper feeding unit 73 is maintained in its initial position because the rotation of the drive shaft 113 is restricted by the drive gear 131 meshing with the output gear of the motor 135.

[0057] However, when the transport cover 33 is opened while the paper feed unit 73 has returned to its initial position, the drive gear 131 separates from the output gear of the motor 135. As a result, the drive shaft 113 becomes free to rotate, making it impossible to maintain the paper feed unit 73 in its initial position, and the holder 111 rotates downward. If the transport cover 33 is closed in this state, the pickup roller 117 will interfere with the document being set.

[0058] On the other hand, when the open transport cover 33 is closed, the impact applied to the transport cover 33 is transmitted to the actuator 91 supported on the inner surface of the transport cover 33, causing the rotation axis 101 of the actuator 91 to reciprocate and rotate within a predetermined rotation angle. Even after the transport cover 33 is closed, the rotation axis 101 continues to reciprocate and rotate due to inertia. As a result, the light-shielding piece 105, which is integrally provided with the rotation axis 101, also reciprocates across the optical path of the sensor 93. This causes the optical path to be formed and blocked in a short time, and the ON signal and OFF signal output from the sensor 93 are switched in a short time. The output time of the ON signal when the transport cover 33 is closed is considerably shorter than the output time of the ON signal during the period from when the document is set until the last document is fed out, that is, during the paper feeding operation. Based on the output time of the ON signal, the control unit 501 can determine whether the paper feeding operation is being performed, in other words, whether the transport cover 33 has been closed. In other words, if the output time of the ON signal is longer than a predetermined time (for example, 200ms or more), it can be determined that the paper feeding operation is being performed. On the other hand, if the output time of the ON signal is shorter than a predetermined time (for example, 100ms or less), or if the ON signal and OFF signal switch in a short time, it can be determined that the transport cover 33 has been closed.

[0059] When the control unit 501 determines that the transport cover 33 is closed, it controls the motor 135 to rotate the drive shaft 113 in the reverse direction R2, allowing the holder 111 to rotate upward. Once the holder 111 rotates and the pickup roller 117 rises, and the rotation of the holder 111 is restricted by the transport cover 33, the control unit 501 stops the rotation of the motor 135. As a result, the paper feeding unit 73 returns to its initial position.

[0060] As is clear from the above explanation, the paper feed unit 73 can be returned to its initial position by opening and then closing the transport cover 33 during paper jam removal, etc. Specifically, the impact generated when closing the transport cover 33 causes the actuator 91 of the document detection mechanism 71 to reciprocate and rotate. By detecting this rotation of the actuator 91, it is determined that the transport cover 33 has been closed, and the paper feed unit 73 is returned to its initial position. Therefore, the pickup roller 117 does not interfere with the document to which it is set, and the paper feeding operation can be performed normally.

[0061] In particular, the actuator 91 is supported by the transport cover 33. Also, the rotation axis 101 of the actuator 91 and the rotation axis of the transport cover 33 are parallel. Therefore, when the transport cover 33 is closed, the actuator 91 itself also moves, causing the actuator 91 to rotate significantly. Thus, the rotation of the actuator 91 can be reliably detected.

[0062] Generally, the document transport device 5 is equipped with an open / close detection sensor that detects the opening and closing of the transport cover 33. When the open / close detection sensor detects that the transport cover 33 is closed, the paper feed unit 73 is returned to its initial position. In this embodiment, even without such an open / close detection sensor, the paper feed unit 73 can be automatically returned to its initial position when the transport cover 33 is closed. Therefore, since an open / close detection sensor is unnecessary, the number of parts and costs can be reduced, and the control and configuration of the document transport device 5 can be simplified.

[0063] Furthermore, when scanning an image of a document using the document-fixing method, the document transport device 5 is rotated upward to expose the contact glass 11 of the image reading device 3, the document is placed on the contact glass 11, and then the document transport device 5 is rotated downward to hold the document in place. When the document transport device 5 is rotated downward, an impact is applied to the document transport device 5.

[0064] In this case as well, when the control unit 501 detects the rotation of the actuator 91, it controls the motor 135 to return the paper feed unit 73 to its initial position. Therefore, even if the paper feed unit 73 is subjected to an impact when the document transport device 5 is closed, causing the torque limiter 133 to slip relative to the drive shaft 113 and move downward, it is still possible to return the paper feed unit 73 to its initial position. It is also possible to return the paper feed unit 73 to its initial position by detecting that the document transport device 5 has been closed (rotated downward) using an opening / closing detection sensor that detects the opening and closing of the document transport device 5. In this embodiment, there is no need to provide such an opening / closing detection sensor, so the number of parts and costs can be reduced, and the control and configuration of the document transport reading device 1 can be simplified.

[0065] Furthermore, even when the document is aligned by bringing its edge to the transport cover 33 of the document transport device 5, the control unit 501 detects the rotation of the actuator 91 and controls the motor 135 to return the paper feed unit 73 to its initial position.

[0066] Next, with reference to Figures 9 and 10B, a modified example of the light-shielding piece 105 of the actuator 91 will be described. Figures 9 and 10 are perspective views showing the light-shielding piece 105 of the actuator 91.

[0067] In the first modified example shown in Figure 9, a slit 201 is formed in the light-shielding piece 105 through which the optical path passes. The slit 201 is formed in a direction perpendicular to the rotation axis 101. The width of the slit 201 is slightly wider than the width of the optical path. The shape and dimensions of the portion upstream of the slit 201 and the portion downstream of the slit are approximately equal.

[0068] In the initial position, the optical path is formed through the slit 201, so the sensor 93 outputs an off signal. When the paper feeding operation is performed, the optical path is blocked by the downstream portion of the light-shielding piece 105, and the sensor 93 outputs an on signal. When the rotating shaft 101 rotates back and forth due to an impact applied to the transport cover 33, the downstream and upstream portions alternately block the optical path. Since the width of the slit 201 is relatively narrow, the time for the optical path to be formed is shortened, and the output time of the on signal is shortened. Therefore, the difference in the output time of the on signal between the paper feeding operation and when an impact is applied becomes large, so it is easy to infer that an impact has been applied.

[0069] In the second modified example shown in Figure 10, the light-shielding piece 105 has a fan shape centered on the axis of rotation and has a light-shielding portion 105a upstream of a line perpendicular to the axis of rotation 101 and a transparent portion 105b downstream of that line. The light-shielding portion 105a is made of a material that can block the light path, and the transparent portion 105b is made of a material that can transmit light through the light path.

[0070] In the second modification, the light-shielding piece 105 hangs almost vertically from the rotation axis 101, and the downstream side edge of the light-shielding portion 105a can be brought close to the optical path. Therefore, even when the rotation angle of the rotation axis 101 is small, the optical path is quickly blocked by the light-shielding portion 105a. Thus, the presence of an impact can be detected quickly and reliably.

[0071] In the above embodiment, in order to bring the downstream side edge of the light-shielding piece 105 close to the optical path, the two pieces were spaced apart in the circumferential direction of the rotation axis 101, taking into consideration the weight balance between the light-shielding piece 105 and the detection piece 103. However, in the second modification, both pieces 103 and 105 are formed at approximately the same position in the circumferential direction of the rotation axis 101, and both pieces 103 and 105 can be suspended in an approximately vertical direction. This allows the actuator 91 to be stably supported.

[0072] The above-described embodiments of the present invention describe preferred embodiments of the document transport apparatus and image forming apparatus according to the present invention, and may include various technically preferred limitations. However, the technical scope of the present invention is not limited to these embodiments unless otherwise specified. [Explanation of Symbols]

[0073] 1. Document transport and reading device 3. Image reading device 5. Document transport device 25 Paper feed tray 31. Transport Frame 33. Transport cover 73 Paper feed unit 91 Actuator 93 Sensors 101 Rotation axis 103 detection piece 105 Light shielding piece 111 Holder 113 Drive shaft 117 Pickup Roller 501 Control Unit

Claims

1. The paper tray into which the document is placed, A paper feeding unit that feeds the document set in the paper feed tray in a predetermined transport direction, An actuator driven by a document placed in the aforementioned paper feed tray, A sensor that outputs a predetermined signal in response to the operation of the actuator, The system includes a control unit which receives a signal output from the aforementioned sensor and controls the paper feeding unit based on the signal, The aforementioned paper feeding unit is A drive shaft rotatably supported above the aforementioned paper feed tray, The upstream end in the aforementioned transport direction is rotatably supported on the drive shaft, and the holder is rotatable vertically in conjunction with the drive shaft, The holder comprises a pickup roller rotatably supported at the downstream end in the transport direction, which rotates in contact with the document set in the paper feed tray, The actuator is A rotating shaft rotatably supported above the aforementioned paper feed tray, A detection piece is provided integrally with the rotating shaft and hangs down from the rotating shaft by its own weight, and rotates the rotating shaft when pressed by a document set in the paper feed tray, The system includes a light-shielding piece that is integrally provided with the rotating shaft and hangs down from the rotating shaft by its own weight, and switches the output of the sensor by the rotation of the rotating shaft, The document transport device is characterized in that, when the control unit receives a signal different from the signal output from the sensor when a document is placed in the paper tray and the actuator is driven, it returns the paper feeding unit to its initial position in which the pickup roller is separated upward from the paper tray.

2. A transport frame having a transport path through which documents set in the paper feed tray are transported, The system further includes a transport cover that is rotatable in the vertical direction and rotates upward to expose the transport path, The document transport device according to claim 1, characterized in that the paper feeding unit and the actuator are supported by the transport cover.

3. An image reading device that reads the image of a document at a predetermined reading position, A document transport and reading device characterized by comprising: a document transport device according to claim 1 or 2, which is rotatably supported by the image reading device and transports a document whose image is read by the image reading device to the reading position.

Images