Manuscript conveying device

Abstract

To provide a manuscript conveying device that can efficiently read both sides of manuscripts that are continuously conveyed.SOLUTION: A manuscript conveying device 1 includes an inlet path 31 that is formed between a paper feeding port 15 and a first passing point M1 right before a reading position P, a reading path 33 that is formed between the first passing point M1 and a second passing point M2 beyond the reading position P and passes through the reading position P, an evacuation path 35 that is formed between the first passing point M1 and the second passing point M2 and does not pass through the reading position P, a loop path 37 that starts from the second passing point M2 and returns to the second passing point M2, and a discharge path 39 that is formed between the first passing point M1 and a discharge port 17. When reading a single-sided image, the manuscript is conveyed sequentially through the inlet path 31, the reading path 33, the loop path 37, the evacuation path 35, and the discharge path 39, and when reading a double-sided image, the manuscript is conveyed sequentially through the inlet path 31, the reading path 33, the loop path 37, the reading path 33, and the discharge path 39.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a document transport device that transports a document so that both sides of the document can be read. [Background technology]

[0002] In a document transport device, a document is transported from the entrance of a transport path to the exit via a reading position. When reading images on both sides of a document, the document needs to be transported upside down to the reading position, so a reversing path is provided to turn the document over.

[0003] The image forming apparatus described in Patent Document 1 has a document inversion path that branches off from the conveyance path at a branching point after passing the reading position and merges with the conveyance path at a merging point upstream of the reading position. When double-sided reading is performed, the document is conveyed to the document inversion path at the branching point, where it is switched back and reversed. The document is then conveyed to the conveyance path at the merging point, and the image on the back side is read as it passes the reading position, after which it is discharged from the discharge port.

[0004] The automatic document feeder described in Patent Document 2 includes a reversing document transport path that passes through a reading position and then returns to the reading position. The reversing document transport path branches off into a discharge path that leads to a discharge outlet. The document is turned over as it passes through the reversing document transport path, and the image on the back side is read as it passes through the reading position. The document is then transported along a separate discharge path that leads to a different discharge outlet, and is discharged from the discharge outlet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-17178 [Patent Document 2] Japanese Patent Application Publication No. 8-286436 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the configuration described in Patent Document 1 requires a complicated mechanism and control for switching back the document when scanning both sides. Furthermore, there is also the problem of a long waiting time when scanning both sides of continuously transported documents, resulting in reduced productivity. Furthermore, the automatic document feeder described in Patent Document 2 requires the reversing document transport path and multiple discharge paths to be located in a narrow space, which may prevent smooth document transport.

[0007] SUMMARY OF THE INVENTION In consideration of the above circumstances, an object of the present invention is to provide a document transport device that has a simple configuration and is capable of efficiently reading both sides of documents that are continuously transported. [Means for solving the problem]

[0008] In order to achieve the above object, the document transport device of the present invention is a document transport device that transports a document through a reading position on a transport path, and the transport path includes an inlet path formed between the document feed port and a first passing point just before the reading position, a reading path formed between the first passing point and a second passing point beyond the reading position and passing through the reading position, an evacuation path formed between the first passing point and the second passing point and not passing through the reading position, a loop path that leaves the second passing point and returns to the second passing point, and a discharge path formed between the first passing point and the document discharge port, and is characterized in that when reading a single-sided image, the document is transported through the inlet path, the reading path, the loop path, the evacuation path, and the discharge path in that order, and when reading a double-sided image, the document is transported through the inlet path, the reading path, the loop path, the reading path, and the discharge path in that order.

[0009] In the present invention, the device may further include a first branching member at the first passing point that is rotatably supported above the entrance path and rotates downward under its own weight to guide the document from the reading path to the discharge path, and when the document is transported from the entrance path to the reading path, the first branching member is pushed up by the document, causing it to rotate upward and allow the document to pass.

[0010] In the present invention, the document feeder may further include a second branching member that is arranged at the second passing point and is switchable between a first position that guides the document from the reading path to the loop path and from the loop path to the evacuation path, and a second position that guides the document from the loop path to the reading path, a first actuator that is actuated by the document transported through the feed path, and a second actuator that is actuated by the document transported through the loop path, and when reading a double-sided image, the second branching member is switched from the first position to the second position by the actuation of the second actuator, and the document is transported to the reading path, and after the document has passed through the reading path, the second branching member is switched from the second position to the first position by the actuation of the first actuator, and the next document is transported from the reading path to the loop path.

[0011] The present invention may be characterized in that the document feeder further comprises a discharge tray on which documents discharged from the discharge port are stacked, and the loop path is disposed below the discharge tray.

[0012] In the present invention, the length of the loop path may be equal to the length of an A4 size paper in portrait or landscape format.

[0013] In the present invention, the document feeder further includes a pair of feed rollers including a drive roller and a driven roller that transport the document along the feed path, and a pair of discharge rollers including a drive roller and a driven roller that transport the document along the discharge path, and the drive roller of the pair of feed rollers is also used as the drive roller of the pair of discharge rollers.

[0014] The present invention may further comprise a pair of forward transport rollers including a drive roller and a driven roller that transports the document along the forward path of the loop path, and a pair of return transport rollers including a drive roller and a driven roller that transports the document along the return path of the loop path, wherein the drive roller of the pair of forward transport rollers is also used as the drive roller of the pair of return transport rollers. [Effects of the Invention]

[0015] According to the present invention, the interval between the end of scanning the front side of a document and the start of scanning the back side of the document can be shortened, thereby improving the productivity of double-sided scanning work. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a front view schematically illustrating an internal configuration of a document transport device according to an embodiment of the present invention. [Figure 2] 1 is a front view schematically illustrating a part of the internal configuration of a document transport device according to an embodiment of the present invention. [Figure 3] 1A to 1C are diagrams illustrating a document transport process during single-side reading in a document transport device according to an embodiment of the present invention. [Figure 4] 1A to 1C are diagrams illustrating a document transport process during double-sided reading in a document transport device according to an embodiment of the present invention. [Figure 5] FIG. 10 is a front view schematically illustrating the internal configuration of a conventional document transport device. [Figure 6] 10 is an example of a timing chart showing the transport of an original during single-side reading by an original transport device according to an embodiment of the present invention and a conventional example. [Figure 7] 10 is an example of a timing chart showing the transport of an original during double-sided reading by an original transport device according to an embodiment of the present invention and a conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A document transport device according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0018] First, the configuration of the document transport device 1 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 and Fig. 2 are front views that schematically show the internal configuration of the document transport device 1. In each figure, L and R indicate the left and right sides of the document transport device 1, respectively.

[0019] The document transport device 1 is placed on the top surface of an image reading device (not shown), for example. The document transport device 1 automatically transports the document, and the image reading device reads the image on one side of the transported document. Explanation of the image reading device will be omitted.

[0020] The document transport device 1 includes a transport section 3 for transporting documents, a paper feed tray 5 on which documents whose images are to be read by the transport section 3 are placed, and a discharge tray 7 on which documents whose images have been read by the transport section 3 are stacked.

[0021] First, the conveying section 3 will be described. When viewed from the front, the conveying section 3 is roughly L-shaped, and has a main conveying section 11 on the left side and a loop conveying section 13 on the right side. The height of the main conveying section 11 is higher than the height of the loop conveying section 13. A paper feed opening 15 and a paper discharge opening 17 are formed on the right side of the main conveying section 11. The paper discharge opening 17 is located lower than the paper feed opening 15.

[0022] The transport section 3 has a transport path for the document that passes through a reading position P of the document by the image reading device. The reading position P is a position that faces the reading sensor of the image reading device from above. An opening that faces the reading sensor is formed at the right end of the lower surface of the main transport section 11. The opening is covered with a transparent glass plate 19. A reading guide 21 is arranged above the glass plate 19 with a predetermined distance therebetween. When the document is transported between the reading guide 21 and the glass plate 19, the image of the document is read by the image reading device. A predetermined position between the reading guide 21 and the glass plate 19 is set as the reading position P.

[0023] The conveying path includes an inlet path 31, a reading path 33, an evacuation path 35, a loop path 37, and a discharge path 39. The inlet path 31, the reading path 33, the evacuation path 35, and the discharge path 39 are formed in the main conveying section 11, and the loop path 37 is formed in the loop conveying section 13.

[0024] First, the carry-in path 31 will be described. The carry-in path 31 is formed between the paper feed opening 15 and a first passing point M1 in front of the reading position P, curving downward from the paper feed opening 15 toward the reading position P. The carry-in path 31 is provided with, in this order from the upstream side in the transport direction, a pickup roller 41, a separation roller unit 43, and a carry-in roller pair 45. The carry-in roller pair 45 includes a drive roller and a driven roller that rotates following the drive roller. The carry-in path 31 may be provided with rollers to guide the transport of the document, if necessary.

[0025] The carry-in path 31 is provided, just before the first passing point M1, with a first actuator 47 and a first optical sensor (not shown), whose optical path is formed or blocked by the first actuator 47. The first actuator 47 is rotatably supported so as to cross the carry-in path 31. The first actuator 47 rotates when pressed by a document passing through the carry-in path 31 (see the two-dot chain line in FIG. 2). When the first actuator 47 rotates, the optical path of the optical sensor is blocked by the first actuator 47, and the optical sensor switches from an off state to an on state. When the first actuator 47 returns to its original position and moves away from the optical path, the optical sensor switches from an on state to an off state. The first optical sensor outputs an on signal indicating the on state and an off signal indicating the off state to a control unit (not shown).

[0026] Next, we will explain the reading path 33. The reading path 33 is formed in a substantially straight line between a first passing point M1 and a second passing point M2 via a reading position P. When a document is transported along the reading path 33 and passes through the reading position P, an image on one side (front side) of the document is read by a reading sensor of the image reading device.

[0027] Next, we will explain the evacuation path 35. The evacuation path 35 is formed between the first passing point M1 and the second passing point M2 so as not to pass through the reading position P. In this example, the evacuation path 35 is formed above the reading guide 21 in a substantially straight line.

[0028] Next, the loop path 37 will be described. The loop path 37 is formed so as to exit from the second passing point M2 and return to the second passing point M2. In this example, the loop path 37 includes a substantially horizontal forward path 37a extending from the second passing point M2 to the right, a curved path 37b curving upward from the forward path 37a, and a return path 37c sloping downward from the curved path 37b toward the second passing point M2. The forward path 37a, the curved path 37b, and the return path 37c are provided with first, second, and third conveyance roller pairs 51, 53, and 55, respectively. Each of the first, second, and third conveyance roller pairs 51, 53, and 55 includes a drive roller and a driven roller that rotates in response to the drive roller. The drive roller of the first conveyance roller pair 51 also serves as the drive roller of the third conveyance roller pair 55. The first transport roller pair 51 is an example of a forward transport roller pair of the present invention, and the third transport roller pair 55 is an example of a return transport roller pair of the present invention.

[0029] Near the exit of the return path 37c (at a position close to the second passing point M2), there are provided a second actuator 57 and a second optical sensor (not shown), whose optical path is formed or blocked by the second actuator 57. The second actuator 57 is rotatably supported so as to cross the return path 37c. The second actuator 57 rotates when pressed by a document passing through the return path 37c (see the two-dot chain line in FIG. 2). When the second actuator 57 rotates, the optical path of the optical sensor is blocked by the second actuator 57, and the optical sensor switches from an off state to an on state. When the second actuator 57 returns to its original position and moves away from the optical path, the optical sensor switches from an on state to an off state. The second optical sensor outputs an on signal indicating the on state and an off signal indicating the off state to a control unit (not shown).

[0030] Next, the discharge path 39 will be described. The discharge path 39 is formed between the first passing point M1 and the discharge outlet 17, curving upward from the first passing point M1 toward the discharge outlet 17. In the discharge path 39, a first discharge roller pair 59 and a second discharge roller pair 61 are provided, in this order from the upstream side in the conveyance direction. The first and second discharge roller pairs 59 and 61 each include a drive roller and a driven roller that rotates following the drive roller. The drive roller of the first discharge roller pair 59 also serves as the drive roller for the feed roller pair 45.

[0031] Furthermore, a first branch guide 65 and a second branch guide 67 are provided at the first passing point M1 and the second passing point M2.

[0032] First, the first branch guide 65 will be described. The first branch guide 65 is a relatively lightweight sheet-like member. As shown in FIG. 2, the first branch guide 65 is rotatably supported at the branch point between the carry-in path 31 and the discharge path 39. The first branch guide 65 rotates by its own weight into a position inclined downward toward the downstream side in the conveyance direction and crosses the carry-in path 31. The tip of the first branch guide 65 contacts the lower guide surface of the carry-in path 31. This guides the document from the reading path 33 to the discharge path 39. On the other hand, when a document is conveyed along the carry-in path 31, the first branch guide 65 is pushed by the document and rotates upward (see the two-dot chain line in FIG. 2), so that the document can be conveyed unimpeded from the carry-in path 31 to the reading path 33.

[0033] Next, the second branch guide 67 will be described. The second branch guide 67 is provided so as to be rotatable in the vertical direction around a rotation axis provided on the side of the reading guide 21. The second branch guide 67 rotates between a first position (see solid line in FIG. 2) and a second position (see two-dot chain line in FIG. 2). In the first position, the reading path 33 communicates with the forward path 37a of the loop path 37, and the return path 37c of the loop path 37 communicates with the evacuation path 35. In the second position, the return path 37c of the loop path 37 communicates with the reading path 33. The second branch guide 67 is controlled by the control unit in response to signals output from the first optical sensor and the second optical sensor, and rotates to either the first position or the second position.

[0034] Next, a description will be given of the paper feed tray 5. As shown in Fig. 1, the paper feed tray 5 is supported below the paper feed opening 15 of the transport section 3 in a position inclined downward toward the paper feed opening 15.

[0035] Next, a description will be given of the discharge tray 7. As shown in Fig. 1, the discharge tray 7 is formed on the upper surface of the loop conveying section 13 below the discharge opening 17 of the conveying section 3.

[0036] The document transport operation in the document transport device 1 having the above configuration will be described with reference to Figures 1, 2, 3, and 4. Figure 3 is a diagram illustrating the document transport process during single-sided reading, and Figure 4 is a diagram illustrating the document transport process during double-sided reading. In the initial state, the first actuator 47 is rotated to a position crossing the carry-in path 31, and the second actuator 57 is rotated to a position crossing the return path 37c. Also, in the initial state, the first branch guide 65 is rotated by its own weight to a position inclined downward toward the downstream side in the transport direction, and crosses the carry-in path 31. The second branch guide 67 is rotated to the first position.

[0037] The user selects either a single-sided reading mode for reading an image on one side of the document or a double-sided reading mode for reading images on both sides of the document, and inputs the selection to the control unit.

[0038] First, the single-sided scanning mode will be described. When the single-sided scanning mode is input to the control unit, the control unit ignores signals input from the first optical sensor and the second optical sensor. In other words, the control unit maintains the second branch guide 67 in the first position regardless of signals input from both sensors. The originals S placed on the paper feed tray are fed by the pickup roller 41, separated one by one by the separation roller unit 43, sent to the feed path 31, and then transported by the feed roller pair 45. When the originals S pass through the feed path 31, the first actuator 47 is pushed by the originals S and rotates, but as described above, the switching of the signal from the first optical sensor due to the rotation of the first actuator 47 is ignored.

[0039] When the leading edge of the document S reaches the first passing point M1, the document pushes up the first branch guide 65. Then, as shown in FIG. 3(a), the document S passes under the first branch guide 65 and is transported to the reading path 33. After the document S passes through the first branch guide 65, the first branch guide 65 returns to its original position. When the document S passes through the reading position P on the reading path 33, an image on one side of the document S is read by the image reading device.

[0040] 3(b), the document S is guided by the second branch guide 67 to the forward path 37a of the loop path 37 at the second passing point M2. The document is transported along the loop path 37 by three transport roller pairs 51, 53, and 55. When the document is transported along the return path 37c of the loop path 37, the second actuator 57 is pushed by the document and rotates, but as described above, the switching of the signal of the second optical sensor due to the rotation of the second actuator 57 is ignored.

[0041] The document S returns to the second passing point M2 and is guided by the second branch guide 67 from the loop path 37 to the evacuation path 35, as shown in FIG. 3(c). The document S is then transported from the evacuation path 35 through the first passing point M1 to the discharge path 39, as shown in FIG. 3(d). The document S is transported to the discharge opening 17 by the first discharge roller pair 59, and then discharged from the discharge opening 17 to the discharge tray 7 by the second discharge roller pair 61.

[0042] Next, the double-sided reading mode will be described. When the double-sided reading mode is input to the control unit, the control unit switches the second branch guide 67 based on signals input from the first optical sensor and the second optical sensor. The originals S placed on the paper feed tray 5 are fed by the pickup roller 41, separated one by one by the separation roller unit 43, sent to the feed path 31, and then transported by the feed roller pair 45. When the originals S pass through the feed path 31, the first actuator 47 is pushed by the originals S and rotates. When the originals S are the first sheet, the control unit ignores the switching of the signal from the first optical sensor due to the rotation of the first actuator 47.

[0043] When the leading edge of the document S reaches the first passing point M1, the document S pushes up the first branch guide 65. As shown in FIG. 4(a), the document S passes below the first branch guide 65 and is transported to the reading path 33. After the document S passes through the first branch guide 65, the first branch guide 65 returns to its original position. When the document S passes through the reading position P on the reading path 33, an image on one side of the document S is read by the image reading unit.

[0044] Thereafter, as shown in FIG. 4(b), the document S is guided by the second branch guide 67 to the forward path 37a of the loop path 37 at the second passing point M2. The document S is transported along the loop path 37 by three transport roller pairs 51, 53, and 55. When the document S is transported along the return path 37c of the loop path 37, the second actuator 57 is pushed by the document S and rotates. This switches the second optical sensor from an off state to an on state, and outputs an on signal to the control unit. When the on signal is input from the second optical sensor, the control unit switches the second branch guide 67 from the first position to the second position (see the two-dot chain line in FIG. 2).

[0045] 4(c), the second branch guide 67 guides the original S from the return path 37c to the reading path 33. The original S is transported to the reading path 33 from the opposite direction to the initial direction, with the front side facing upward. When the original S passes through the reading position P on the reading path 33, the image on the back side of the original S is read by the reading sensor of the image reading device.

[0046] 4(d), the original S is then guided by the first branch guide 65 from the retreat path 35 to the discharge path 39 at the first passing point M1. The original S is transported along the discharge path 39 by the first discharge roller pair 59 to the discharge outlet 17, and is discharged from the discharge outlet 17 to the discharge tray 7 by the second discharge roller pair 61.

[0047] When there are two or more sheets of original S, the second sheet of original S is transported to the feed-in path 31 at a predetermined timing. When the second sheet of original S passes through the feed-in path 31, the first actuator 47 is pushed by the original S and rotates. This causes the second optical sensor to switch from an off state to an on state and output an on signal to the control unit. When the on signal is input to the control unit, the control unit rotates the second branch guide 67 from the second position to the first position (see the solid line in Figure 2). Thereafter, the original S is transported in the same manner as the first sheet of original S, and the images on both sides are read.

[0048] Next, an example of the document transport time by the document transport device 1 of the present invention and the conventional document transport device 101 will be described with reference to the timing charts of Figures 6 and 7. Each figure is a timing chart for the case where three documents (A4 landscape size, document length in the transport direction: approximately 210 mm) are transported consecutively.

[0049] First, an example of a conventional document transport device 101 will be briefly described with reference to Fig. 5. Fig. 5 is a front view that schematically shows the conventional document transport device 101. The conventional document transport device 101 includes an input path 131 that leads from a document feed port 115 to a reading position P, a discharge path 133 that leads from the reading position P to a discharge port 117, and a reversal path 135 that leads from the reading position P through a switchback port 119 and merges with the input path 131.

[0050] In the case of single-sided scanning, the document is transported to the scanning position P through the infeed path 131, where the image on the front side is scanned. The document is then transported to the scanning outlet 117 through the discharge path 133 and scanned from the discharge outlet 117. In the case of double-sided scanning, the document is transported to the scanning position P through the infeed path 131, where the image on the front side is scanned from the front side. The document is then switched back through the reversal path 135 and returned to the infeed path 131. By switching back the document, the document is reversed. The document is then transported to the scanning position P through the infeed path 131, where the image on the back side is scanned from the front side. The document is then transported to the scanning position P through the discharge path 133 and scanned from the discharge outlet 117. When a stack of multiple documents is to be scanned consecutively on both sides, the documents whose back side images have been scanned at the scanning position P are reversed and transported by switching back through the reversing path 135 and returning to the feed path 131. The documents are then transported through the discharge path 133 to the discharge outlet 117 and discharged from the discharge outlet 117. As a result, the documents are discharged in the same arrangement (orientation and order) as the documents in the document stack before being scanned.

[0051] The parameters of the document transport devices 1 and 101 are set as follows: Distance from the paper feed slot to the reading position (length of the feed path) (common) L1: 90 mm, Distance from reading position to discharge outlet (length of discharge path) (common) L2: 60 mm, Reversal path distance (conventional model) L3:L2 <L3<L1、 Transport time for original (length 210 mm) (common): 7T, Document spacing (common): 30 mm (1T), Time required for reverse transport (including the pause time when reversing the transport direction, assuming the document is sent out 180 mm from the switchback opening and then reversed) (conventional model): 3T, Distance of the loop path (the distance at which the rear end of the document (length 210 mm) reaches the reading position at the standard interval (1T, 30 mm) after passing the reading position) (present invention): approximately 240 mm.

[0052] First, single-sided scanning will be described with reference to FIG. 6. First, conventional document transport device 101 will be described. At transport start time t0, the leading edge of the first document is transported from paper feed port 115. The document passes through paper feed port 115 and is transported along carry-in path 131 over time 7T. The leading edge of the document reaches reading position P at time t1, after time 3T has elapsed since transport start time t0 (the time it takes to transport 90 mm along the carry-in path). The document passes through reading position P over time 7T and is transported along discharge path 133. The leading edge of the document reaches discharge port 117 at time t2, after time 2T has elapsed since time t1 (the time it takes to transport 60 mm along the discharge path). The document is discharged from discharge port 117 over time 7T.

[0053] The second document is transported from the paper feed port 115 at time t3, an interval of 1T between documents, after the first document has passed through the paper feed port 115 in time 7T. Thereafter, it is transported in the same manner as the first document. The third document is also transported in the same manner as the first document.

[0054] Next, the document transport device 1 of the present invention will be described. At transport start time t0, the leading edge of the first document is transported from the paper feed slot 15. The document passes through the paper feed slot 15 and is transported along the carry-in path 31 over a period of 7T. The leading edge of the document reaches the reading position P at time t1, a period of 3T (the time required for the document to be transported along the carry-in path 90 mm) after transport start time t0. The document passes through the reading position P and is transported along the loop path 37 over a period of 7T. The leading edge of the document reaches the discharge port 17 at time t2', a period of 10T (the time required for the document to be transported along the loop path 240 mm + the discharge path 60 mm) after time t1. The document is discharged from the discharge port 17 over a period of 7T.

[0055] The second document is transported from the paper feed slot 15 at time t3, after the first document has passed through the paper feed slot 15 in time T7, leaving a document interval of 1T. Thereafter, it is transported in the same manner as the first document. The third document is also transported in the same manner as the first document.

[0056] Thus, in the case of single-sided reading, the reading completion time for each document is 8T earlier in the conventional document feeding device 101 than in the document feeding device 1 of the present invention. However, the difference in the reading completion time for the final document remains the same regardless of the number of documents.

[0057] Next, double-sided scanning will be described with reference to FIG. 7. First, a conventional machine will be described. At transport start time t0, the leading edge of the first sheet of document is transported from paper feed slot 115. The document passes through paper feed slot 115 over time 7T and is transported along carry-in path 131. The leading edge of the document reaches reading position P at time t1, which is 3T (the time it takes to transport 90 mm along the carry-in path) from transport start time t0. The document passes reading position P over time 7T, and the image on the front side of the document is read. The document is then transported along reversal path 135. The leading edge of the document reaches the reading position at time t2, which is 4T after the time when the trailing edge of the document passes reading position P. The document passes reading position P over time 7T, and the image on the back side of the document is read. Thereafter, for reverse transport, the document is switched back again on the reversing path 135, and reaches the reading position P at time t3, which is 4T after the time when the trailing edge of the document passes through the reading position P, and takes 7T to pass through the reading position P (see the dotted line in FIG. 7). During the switchback, the leading edge and trailing edge of the document temporarily overlap on the reversing path 135 and slide against each other while moving in opposite directions. The document is then transported along the discharge path 133. The leading edge of the document reaches the discharge outlet 117 at time t4, which is 2T after time t3 (the time it takes to transport 60 mm along the discharge path). The document is discharged from the discharge outlet 117 over time 7T.

[0058] The second document is transported so that its leading edge reaches reading position P at time t7, which is time T1 after time t6 when the inverted and transported first document (see dotted line in FIG. 7) passes through reading position P. In order to transport the document so that its leading edge reaches the reading position at time t7, the document is transported from paper feed port 115 at time t5, which is time 3T (the time it takes to transport through the feed path) before time t7. Thereafter, it is transported in the same way as the first document. The third document is transported in the same way.

[0059] Next, the present invention will be described. At transport start time t0, the leading edge of the first document is transported from paper feed slot 15. The document passes through paper feed slot 15 and is transported along the feed path over a period of 7T. The leading edge of the document reaches reading position P at time t1, a period of 3T (the time it takes to transport 90 mm of the feed path) from transport start time t0. The document passes the reading position over a period of 7T, and the image on the front side of the document is read. The document is then transported along loop path 37. The leading edge of the document reaches reading position P at time t2', a period of 8T (the time it takes to transport 240 mm of the loop path) from time t1. The document passes through reading position P over a period of 7T, and the image on the back side of the document is read. The document is then transported along discharge path 39. The leading edge of the document reaches discharge slot 17 at time t3', a period of 2T (the time it takes to transport 60 mm of the discharge path) from time t2'. The document is discharged from the discharge port 17 over a time period of 7T.

[0060] The second document is transported so that its leading edge reaches reading position P at time t6', which is time T1 after time t5' when the first document passed through loop path 37 and passed reading position P. In order to transport the document so that its leading edge reaches reading position P at time t6', the document is transported from paper feed slot 15 at time t4', which is time 3T (the time it takes to transport through the feed path) before time t6'. Thereafter, it is transported in the same way as the first document. The third document is transported in the same way.

[0061] As described above, in double-sided scanning, the start time of the next document is determined according to the reverse conveyance end time (t6) in conventional machines, but is set according to the back-side scanning end time (t5') in the present invention. The difference between the reverse conveyance end time (t6) and the back-side scanning end time (t5') is 14T in this example. This difference increases as the number of documents increases. That is, it accumulates for the number of documents. For example, if there are three documents, the difference is 3 x 14T. In conventional machines, when multiple documents are transported, reverse conveyance is required to discharge the documents in the same order (orientation) as the documents before transport. In the present disclosure, documents can be discharged in the same order (orientation) as the documents before transport without reverse conveyance, thereby reducing the transport time. In this way, productivity of double-sided scanning operations can be improved.

[0062] On the other hand, in the case of single-sided scanning, the time when scanning of the first document is completed is earlier in the conventional machine than in the document transport device of the present invention. However, since the difference between the two is not related to the number of documents, productivity of single-sided scanning work remains the same except for the difference in the time when scanning of the first document is completed.

[0063] Furthermore, in the document transport device of the present invention, the document is transported in one direction whether reading one side or both sides, so there is no need to switch back. Therefore, there is no need to reverse the drive roller, making it easy to control the drive roller.

[0064] Furthermore, the drive roller of the pair of carry-in rollers 45 of the carry-in path 31 can also be used as the drive roller of the first pair of discharge rollers 59 of the discharge path 39. Furthermore, the drive roller of the first pair of transport rollers 51 of the loop path 37 can also be used as the drive roller of the third pair of transport rollers 55. Therefore, the number of parts of the rollers that transport the document can be reduced.

[0065] Furthermore, the first branch guide 65 is pushed up by the document passing through, thereby allowing the document to pass through, so there is no need for a mechanism to rotate the first branch guide 65 when switching paths, which simplifies control of the first branch guide 65.

[0066] Furthermore, the upper surface of the loop transport section 13 can be used as the discharge tray 7; in other words, the space below the discharge tray 7 can be used effectively.

[0067] To increase productivity in double-sided scanning of frequently used A4-sized documents, the length of loop path 37 is preferably the same as that of A4 portrait or landscape. In this case, documents longer than these lengths (e.g., A3-sized documents) are ejected after the image on one side has been scanned. For example, the size of the document is detected by first actuator 47, and when the document length exceeds the above-mentioned length, second branch guide 67 is switched to the first position. As a result, the document is transported in the same manner as in the single-sided scanning described above, and the image on one side is scanned.

[0068] Although the present invention has been described with reference to specific embodiments, the present invention is not limited to the above embodiments, and those skilled in the art may modify the above embodiments without departing from the scope and spirit of the present invention. [Explanation of symbols]

[0069] 1 Document transport device 15 Paper feed slot 17 Outlet 31 Loading route (transport route) 33 Reading path (transport path) 35 Evacuation route (transport route) 37 Loop route (transport route) 39 Discharge path (transport path) 45 Loading roller pair 47 First Actuator 51 First conveying roller pair (forward conveying roller pair) 55 Third conveying roller pair (returning conveying roller pair) 57 Second Actuator 59 First discharge roller pair 65 First branch member 67 Second branch member

Claims

1. A document transport device that transports a document through a reading position on a transport path, The conveying path is a carry-in path formed between a document feed port and a first pass point in front of the reading position; a reading path formed between the first passing point and a second passing point beyond the reading position, the reading path passing through the reading position; an escape path formed between the first passing point and the second passing point, the escape path not passing through the reading position; a loop path that leaves the second waypoint and returns to the second waypoint; a discharge path formed between the first passing point and an outlet for the document; When reading an image on one side of the document, the document is transported through the carry-in path, the reading path, the loop path, the evacuation path, and the discharge path in this order; In a double-sided image reading operation, the document is conveyed through the entrance path, the reading path, the loop path, the reading path, and the discharge path in this order.

2. a first branching member that is rotatably supported above the carry-in path at the first passing point and rotates downward by its own weight to guide the document from the reading path to the discharge path; 2. The document transport device according to claim 1, wherein when a document is transported from the carry-in path to the reading path, the first branch member is pushed up by the document and rotates upward to allow the document to pass through.

3. a second branching member that is disposed at the second passing point and is switchable between a first position that guides the document from the reading path to the loop path and also guides the document from the loop path to the evacuation path, and a second position that guides the document from the loop path to the reading path; a first actuator that is actuated by a document transported through the transport path; a second actuator that is actuated by the document transported along the loop path, When double-sided images are read, the second branch member is switched from the first position to the second position by the operation of the second actuator, and the document is transported to the reading path; 2. The document transport device according to claim 1, wherein after a document has passed through the reading path, the second branching member is switched from the second position to the first position by the operation of the first actuator, and the next document is transported from the reading path to the loop path.

4. further comprising a discharge tray on which the originals discharged from the discharge port are stacked; 2. The document transport device according to claim 1, wherein the loop path is disposed below the discharge tray.

5. 2. The document transport device according to claim 1, wherein the length of the loop path is equal to the length of an A4 size document in portrait or landscape orientation.

6. a pair of carry-in rollers including a drive roller and a driven roller that transport the document along the carry-in path; a pair of discharge rollers including a drive roller and a driven roller that transport the document along the discharge path; 2. The document transport device according to claim 1, wherein the drive roller of the pair of feed rollers also serves as the drive roller of the pair of discharge rollers.

7. a pair of forward transport rollers including a drive roller and a driven roller that transport the document along a forward path of the loop path; a return-side transport roller pair including a drive roller and a driven roller that transports the document along a return path of the loop path, 2. The document transport device according to claim 1, wherein the drive roller of the forward transport roller pair also serves as the drive roller of the return transport roller pair.

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