Media conveying device, image reading device

Abstract

To solve a problem in which: if a medium has low rigidity, when the medium skews, a leading end of a preceding side abutting against a stopper for skew correction is crushed, which causes damage to the medium.SOLUTION: A medium conveying device comprises: a feeding roller that feeds a medium to a downstream side; at least one stopper that is located downstream of the feeding roller on a conveyance path for conveying the medium and can be switched between a blocking state in which the same blocks the conveyance path and an opening state in which the same opens the conveyance path; and a control unit that can execute skew correction control of causing a leading end of the medium to abut against the stopper in the blocking state to correct the skew of the medium. The control unit can acquire information related to rigidity of the medium, and when conveying a second medium with lower rigidity than that of a first medium, makes timing to switch the stopper from the blocking state to the opening state to end the skew correction control earlier than that for the first medium.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a medium transport device that transports a medium, and an image reading device including the medium transport device. [Background technology]

[0002] One example of an image reading device is a sheet-fed type that reads an image while transporting a medium. Some image reading devices of this type are equipped with a mechanism for correcting skew of the medium, as shown in Patent Document 1. The medium conveying device of the image reading device described in Patent Document 1 has a skew correction mechanism, and this skew correction mechanism has a left stopper, a right stopper, a left lever, and a right lever. Each of these members is provided so that it can be switched between a state in which the document conveying path is blocked and a state in which it is opened. The left lever and the right lever are located slightly upstream of the left stopper and the right stopper. The left lever has a function of locking the left stopper in a blocked state, and when the leading edge of the medium pushes up the left lever, the lock of the left stopper by the left lever is released, and the left stopper can open the document conveying path. Similarly, the right lever has a function of locking the right stopper in a blocked state, and when the leading edge of the medium pushes up the right lever, the lock of the right stopper by the right lever is released, and the right stopper can open the document conveying path.

[0003] The skew correction mechanism described in Patent Document 1 is configured as described above, so that when the medium is skewed, the leading edge of the medium strikes the left or right stopper, causing the medium to rotate and correct the skew. During the skew correction process, the leading edge of the medium pushes up the left and right levers, unlocking the left and right stoppers and allowing the leading edge of the medium to move downstream. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-037478 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the skew correction mechanism described in Patent Document 1, if the media has a certain level of rigidity, when the media skews, the leading side of the leading edge of the media hits the left or right stopper as described above, rotates, and the skew is corrected. However, if the medium has low rigidity, when the medium is skewed and the leading side hits the left or right stopper, the part that hits will be crushed before the medium rotates, resulting in damage. [Means for solving the problem]

[0006] In order to solve the above problem, the media transport device of the present invention comprises a feed roller that transports the media downstream, at least one stopper that is located downstream of the feed roller in a transport path that transports the media and is switchable between a blocked state that blocks the transport path and an open state that opens the transport path, and a control unit that controls the rotation of the feed roller and the switching of the state of the stopper, and is capable of performing skew correction control that corrects skew of the media by abutting the leading edge of the media against the stopper that is in the blocked state, and is characterized in that the control unit is capable of acquiring information related to the rigidity of the media, and when transporting a second medium having a lower rigidity than a first medium, the control unit switches the stopper from the blocked state to the open state and ends the skew correction control earlier than for the first medium. An image reading device according to the present invention includes the above-mentioned medium transport device for transporting a medium, and reading means for reading a surface of the medium transported by the medium transport device. [Brief description of the drawings]

[0007] [Figure 1] FIG. 4 is a side view of the document feed path of the scanner when the stopper is in the blocking state. [Diagram 2] FIG. 4 is a side view of the document feed path of the scanner when the stopper is in the open state. [Diagram 3] FIG. 4 is a block diagram showing the control system of the scanner. [Figure 4] FIG. 4 is a plan view of the transport path showing the relationship between the stopper and the medium. [Diagram 5] FIG. 4 is a plan view of the transport path showing the relationship between the stopper and the medium. [Figure 6] FIG. 4 is a plan view of the transport path showing the relationship between the stopper and the medium. [Figure 7] 11 is a flowchart showing the flow of a skew correction process. [Figure 8] 10 is a flowchart showing the flow of a skew correction process according to another embodiment. [Figure 9] FIG. 4 is a front view of the stiffness imparting portion when it is advanced into the conveying path. [Figure 10] FIG. 13 is a front view of the stiffness imparting unit in a state where it is retracted from the transport path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will now be briefly described. The media transport device of the first aspect comprises a feed roller that transports the media downstream, at least one stopper located downstream of the feed roller in a transport path that transports the media and that is switchable between a blocked state that blocks the transport path and an open state that opens the transport path, and a control unit that controls the rotation of the feed roller and the switching of the state of the stopper, and is capable of performing skew correction control that corrects skew of the media by abutting the leading edge of the media against the stopper that is in the blocked state, and is characterized in that the control unit is capable of acquiring information related to the rigidity of the media, and when transporting a second medium having a lower rigidity than a first medium, the control unit switches the stopper from the blocked state to the open state and ends the skew correction control earlier than for the first medium.

[0009] According to this aspect, the control unit capable of executing the skew correction control is capable of acquiring information related to the rigidity of the medium, and when transporting a second medium having a lower rigidity than a first medium, the timing for switching the stopper from the blocked state to the open state and terminating the skew correction control is made earlier than for the first medium, thereby suppressing crushing caused by the leading edge of the medium hitting the stopper when transporting the second medium having a lower rigidity than the first medium.

[0010] A second aspect is the first aspect, wherein the control unit determines the stiffness of the medium based on a thickness of the medium. According to this aspect, the control unit determines the stiffness of the medium based on the thickness of the medium, and therefore the stiffness of the medium can be easily determined.

[0011] A third aspect is characterized in that in the second aspect, a thickness detection unit for detecting a thickness of a medium is provided at a position on the transport path downstream of the feed roller and upstream of the stopper.

[0012] According to the present aspect, a thickness detection unit for detecting the thickness of the medium is provided at a position on the transport path downstream of the feed roller and upstream of the stopper, so that the user does not need to input information related to the thickness of the medium, improving the usability of the device.

[0013] The fourth aspect is characterized in that, in the first aspect, an information input unit is provided that accepts input of information related to the type of medium, and the control unit determines the rigidity of the medium based on the type of medium input to the information input unit. According to this aspect, the control unit determines the stiffness of the medium based on the type of medium input to the information input unit, so that the stiffness of the medium can be accurately grasped.

[0014] A fifth aspect is the fourth aspect, further comprising a media loading section for loading the medium to be fed by the feed roller, and a loading detection section for detecting the presence or absence of medium on the media loading section, wherein the information input section is composed of a display device that displays various information, the control section is capable of displaying a user interface on the display device that accepts input of information related to the type of medium, and when the control section determines that there is medium on the media loading section based on information received from the loading detection section during a transport standby state, it causes the display device to display the user interface.

[0015] According to this aspect, when the control unit determines that there is a medium on the media loading section based on information received from the loading detection unit while in a transport standby state, it causes the display device to display a user interface that accepts input of information related to the type of medium, thereby eliminating the need for the user to perform operations to display the user interface, improving usability for the user.

[0016] A sixth aspect is characterized in that, in the fifth aspect, the control unit is capable of executing standby control in which it waits for a medium to be placed on the media loading section when there is no medium on the media loading section, and when it determines that a medium has been placed on the media loading section based on information received from the placement detection unit, it rotates the feed roller in the forward direction to feed the medium from the media loading section, and after the control unit acquires information related to the rigidity of the medium in the standby control, it feeds the medium from the media loading section without displaying the user interface on the display device.

[0017] According to this aspect, after the control unit obtains information related to the stiffness of the medium during the standby control, it sends out the medium from the medium loading unit without displaying the user interface on the display device, so that the user does not need to input information related to the stiffness of the medium each time the user loads the medium on the medium loading unit, improving the usability of the device.

[0018] The seventh aspect is characterized in that, in any of the first to fourth aspects, a skew detection unit for detecting skew of the leading edge of the medium is provided at a position on the transport path downstream of the feed roller and upstream of the stopper, and the control unit performs error processing if the skew of the medium exceeds a predetermined degree at the time when the skew correction control is executed for a predetermined time based on information received from the skew detection unit.

[0019] According to this aspect, the control unit performs error processing if the skew of the medium exceeds a predetermined degree at the time when the skew correction control is executed for a specified period of time based on the information received from the skew detection unit, so that an appropriate processing result can be obtained when the skew correction of the medium is not good.

[0020] An eighth aspect of the present invention is characterized in that in the seventh aspect, the error processing is processing for continuing the skew correction control by decelerating the rotation speed of the feed roller. According to this embodiment, the error processing is a process in which the rotational speed of the feed roller is slowed down to continue the skew correction control, so that it is expected that skew correction will proceed through the rotation of the medium while suppressing crushing caused by the leading edge of the medium hitting the stopper.

[0021] A ninth aspect is the seventh aspect, wherein the error processing is processing for reversing the feed roller to return the medium upstream and retrying the skew correction control. According to this aspect, the error processing is a process of reversing the feed roller to return the medium upstream and retrying the skew correction control, so that it is expected that skew correction will be performed satisfactorily.

[0022] The tenth aspect is characterized in that the seventh aspect is provided with a display device that displays various information and a media loading section for loading the medium fed by the feed roller, and the error processing is a process of stopping the feed roller and instructing the display device to reset the medium on the media loading section.

[0023] According to this aspect, the error processing is a process of stopping the feed roller and guiding the display device to re-set the medium on the medium loading section, so that by having the user re-set the medium on the medium loading section, it is possible to expect the medium to be transported with less skewing the next time it is transported.

[0024] The image reading device of the 11th aspect is characterized in that it comprises a medium conveying device of any of the 1st to 10th aspects for conveying a medium, and a reading means for reading the surface of the medium conveyed by the medium conveying device. According to this aspect, in the image reading device, the operational effects of any one of the first to tenth aspects described above can be obtained.

[0025] The present invention will be specifically described below. In the following, a scanner 1 capable of reading at least one of the front and back sides of a document, which is an example of a medium, will be described as an example of an image reading device. The scanner 1 is a so-called sheet-fed type scanner that reads a document while conveying it to a reading means.

[0026] In the XYZ coordinate system shown in each figure, the X-axis direction is the device width direction and the document width direction, the Y-axis direction is the device depth direction and the horizontal direction, and the Z-axis direction is the vertical direction. Hereinafter, the direction in which the document is transported (+Y direction) may be referred to as "downstream," and the opposite direction (-Y direction) may be referred to as "upstream."

[0027] 1, the scanner 1 includes an upper unit 2b on top of a lower unit 2a. The upper unit 2b can rotate about a rotation axis (not shown) located at the end in the +Y direction relative to the lower unit 2a, and can be opened relative to the lower unit 2a by rotating. By opening the upper unit 2b relative to the lower unit 2a, a transport path 6, which will be described later, can be exposed.

[0028] The upper unit 2b has an operation panel 51 on the top surface for performing various operations. In this embodiment, the operation panel 51 is a so-called touch panel that can perform both display and input, and serves both as an information input unit that accepts input of various information and as a display device that displays various information.

[0029] The following describes the document feed path inside the scanner 1. An original placement unit 5, which is an example of a medium placement unit, is provided at the most upstream of the document feed path, and the original is supported in an inclined position by the original placement unit 5, as indicated by the symbol Pa. A feed roller 10 driven by a feed motor 52 (see FIG. 3) is provided downstream of the document placement unit 5. The feed roller 10 is an example of a feed roller that feeds documents downstream. The feed roller 10 feeds the bottommost document downstream out of multiple documents placed on the document placement unit 5. In FIGS. 1 and 2, the symbol P indicates an example of a document sent out from the document placement unit 5.

[0030] A separation pad 11 is provided at a position facing the feed roller 10. The separation pad 11 prevents a document from proceeding downstream following the bottom document fed by the feed roller 10, i.e., prevents double feeding. Downstream of the feed roller 10 and the separation pad 11, a transport path 6 for transporting the document is formed by an upper path forming member 12 and a lower path forming member 13. In this embodiment, the transport path 6 is a section from the feed roller 10 to a first transport roller pair 16. The feed roller 10 and the separation pad 11 are provided at the center position CL (see FIG. 9, etc.) of the transport path 6 in the X-axis direction, and are configured so that the feeding force of the feed roller 10 does not cause the original to skew.

[0031] The transport path 6 is provided with a first document detection section 26, a rigidity detection section 29, a skew detection section 31, and a stopper 21, which will be described later. A first transport roller pair 16 is provided downstream of the stopper 21, and a reading unit 20 serving as a reading means for reading an original image is provided further downstream thereof, and a second transport roller pair 17 is provided further downstream thereof.

[0032] The first transport roller pair 16 includes a drive roller 16a driven by a transport motor 53 (see FIG. 3) and a driven roller 16b that rotates in response to the drive roller 16a. The driven roller 16b is displaceable in a direction toward and away from the drive roller 16a, and is pressed toward the drive roller 16a by a pressing member (not shown).

[0033] The document sent downstream by the feed roller 10 is nipped by the first transport roller pair 16 and transported to a position facing the lower sensor unit 20A and the upper sensor unit 20B located downstream of the first transport roller pair 16.

[0034] The reading unit 20 includes a lower sensor unit 20A located below the document feed path, and an upper sensor unit 20B located above the document feed path. The lower sensor unit 20A and the upper sensor unit 20B are contact image sensor modules (CISMs). The lower surface of the document is read by lower sensor unit 20A located below the document feed path, and the upper surface of the document is read by upper sensor unit 20B located above the document feed path.

[0035] The document from which at least one of the upper and lower surfaces has been read by the reading unit 20 is nipped by a second transport roller pair 17 located downstream of the reading unit 20 and discharged from a discharge opening 18. The second transport roller pair 17 includes a drive roller 17a that is driven to rotate by a transport motor 53 (see FIG. 3), and a driven roller 17b that rotates in response to the drive roller 17a. The driven roller 17b is displaceable in the direction toward and away from the drive roller 17a, and is pressed toward the drive roller 17a by a pressing member (not shown).

[0036] Next, a control system in the scanner 1 will be described with reference to FIG. 3 and, if necessary, FIG. The control unit 50 as a control means performs various controls of the scanner 1, including document feeding, transport, discharge control, and reading control. In particular, the control unit 50 can execute skew correction control, which will be described later. A signal is input to the control unit 50 from an operation panel 51, and a signal for displaying the display of the operation panel 51, particularly a user interface (hereinafter referred to as "UI"), is sent from the control unit 50 to the operation panel 51.

[0037] The control unit 50 controls the feed motor 52 and the transport motor 53. In this embodiment, each motor is a DC motor. In addition, detection values ​​of rotary encoders (not shown) provided for the feed motor 52 and the transport motor 53 are input to the control unit 50, which enables the control unit 50 to grasp the amount of rotation of each motor, and thus the amount of document feed by each roller.

[0038] The control unit 50 controls the left outer solenoid 61A, the left inner solenoid 61B, the right inner solenoid 61C, and the right outer solenoid 61D. When there is no particular need to distinguish between these solenoids, they are collectively referred to as solenoids 61. The solenoid 61 is a solenoid actuator, and has a movable iron core that performs a piston action by switching between energized and de-energized states, and a stopper 21, which will be described later, is attached to the tip of this movable iron core. The solenoid 61 may be of either a pull type or a push type.

[0039] The control unit 50 receives read data from the reading unit 20 , and also transmits a signal for controlling the reading unit 20 from the control unit 50 to the reading unit 20 . The control unit 50 includes a CPU 55, a flash ROM 56, and a RAM 57. The CPU 55 performs various arithmetic processing according to the programs stored in the flash ROM 56, and controls the operation of the scanner 1 as a whole. The flash ROM 56, which is an example of a storage means, is a non-volatile memory that can be read and written, and stores various control programs, parameters, etc. required for document feed control and reading. Various programs, parameters, etc. required for skew correction control, which will be described later, are also stored in the flash ROM 56. Various setting information input by the user via the operation panel 51 is also stored in the flash ROM 56. Various information is temporarily stored in the RAM 57, which is a volatile memory. The control unit 50 is provided with an interface 58, and is capable of communicating with an external computer 90 via this interface 58.

[0040] To the control unit 50, signals from the detection units, namely, the placement detection unit 28, the first document detection unit 26, the second document detection unit 27, the rigidity detection unit 29, and the skew detection unit 31, are also input. The placement detection unit 28 is provided on the original placement unit 5 as shown in Fig. 1. The placement detection unit 28 is, for example, an optical sensor, and includes a light emitting unit (not shown) that emits detection light, and a light receiving unit (not shown) that receives the detection light reflected by the original. When an original is placed on the original placement unit 5, the intensity of the detection light received by the placement detection unit 28 becomes equal to or greater than a predetermined value. The control unit 50 can detect the presence or absence of an original on the original placement unit 5 based on the detection signal from the placement detection unit 28. The placement detector 28 is configured as a non-contact sensor in this embodiment, but may be configured as a contact sensor.

[0041] The first document detection unit 26 is provided downstream of the feed roller 10. The first document detection unit 26 is, for example, an optical sensor, and includes a light emitting unit (not shown) that emits detection light, and a light receiving unit (not shown) that receives the detection light reflected by the document. When the document reaches the first document detection unit 26, the intensity of the detection light received by the first document detection unit 26 becomes equal to or greater than a predetermined value. The control unit 50 can detect the passage of the leading or trailing end of the document based on the detection signal from the first document detection unit 26. The first document detection unit 26 may be a transmission type sensor instead of a reflective sensor, and may be a contact type sensor, although it is configured as a non-contact type sensor in this embodiment.

[0042] The rigidity detection unit 29 is provided downstream of the first document detection unit 26. In this embodiment, the rigidity detection unit 29 is configured with an ultrasonic sensor including an ultrasonic transmitter 29a and an ultrasonic receiver 29b that are arranged opposite each other across the transport path 6 as shown in Fig. 1. The control unit 50, which will be described later, can detect the rigidity of the document based on the intensity of the signal transmitted from the rigidity detection unit 29. In other words, the detection signal from the rigidity detection unit 29 becomes information related to the rigidity of the document.

[0043] For example, in the case of a first document and a second document that is thinner and less rigid than the first document, the ultrasonic waves that pass through the second document and are received by the ultrasonic receiver 29b will have a stronger intensity than the ultrasonic waves that pass through the first document and are received by the ultrasonic receiver 29b. This allows the control unit 50 to grasp the rigidity of the documents. Furthermore, if the documents are made of the same or similar material, the intensity of the ultrasonic waves received by the ultrasonic receiver 29b will vary depending on the thickness of the documents, so the rigidity detection unit 29 according to this embodiment can be said to be a thickness detection unit that detects the thickness of the documents. In this case, the intensity of the ultrasonic waves received by the ultrasonic receiver 29b is information related to the thickness of the documents.

[0044] In this embodiment, the rigidity detection unit 29 is configured with an ultrasonic sensor, but this is not limiting and other known paper thickness sensors may be used to determine the rigidity of the document based on the paper thickness. However, when the rigidity detection unit 29 is configured with an ultrasonic sensor, the intensity of the ultrasonic waves received by the ultrasonic receiving unit 29b will be different for documents with the same thickness but different rigidity, more specifically, documents with different densities, and this makes it possible to more appropriately grasp the rigidity of the document. Furthermore, in this embodiment, the document sent from the feed roller 10 is pressed against the lower path forming member 13 and curves so as to be convex downward. The degree of this curvature increases as the rigidity of the document decreases. Therefore, for example, if the first document detection unit 26 in FIG. 1 is configured with a known distance measuring sensor, the rigidity of the document can also be detected. In other words, the lower the rigidity of the document, the shorter the distance between the first document detection unit 26 and the document. Note that when no document is present, the distance detected by the first document detection unit 26 is the longest. In any case, a configuration in which a sensor is used to determine the stiffness of the document or, instead of stiffness, its thickness, eliminates the need for the user to input information relating to the stiffness of the document, improving ease of use of the device for users.

[0045] The skew detection unit 31 is an optical sensor located near the upstream side of the stopper 21 described later, and includes a light emitting unit (not shown) that emits detection light, and a light receiving unit (not shown) that receives the detection light reflected by the document. When the document reaches the skew detection unit 31, the intensity of the detection light received by the skew detection unit 31 becomes equal to or higher than a predetermined value. However, the skew detection unit 31 may employ a transmission type sensor instead of a reflection type sensor. The skew detection unit 31 is composed of a plurality of detection units as shown in Figures 4 to 6, and specifically includes a left outer detection unit 31A, a left inner detection unit 31B, a right inner detection unit 31C, and a right outer detection unit 31D. In Figures 4 to 6, a straight line CL indicates the center position of the transport path 6 in the X-axis direction, and each detection unit is disposed symmetrically with respect to the center position CL and at a position corresponding to a stopper 21 described later. If the leading edge Ps of the document is skewed, then, for example, only the left outer detector 31A detects the document, and the other detectors do not detect the document, as shown in Figure 4. That is, the control unit 50 can determine whether the document is skewed based on the detection signals of the detectors constituting the skew detector 31.

[0046] Next, the second original detection unit 27 is an optical sensor located between the first transport roller pair 16 and the reading unit 20 in the original feed direction, and is composed of a light emitting unit (not shown) that emits detection light and a light receiving unit (not shown) that receives the detection light reflected by the original. When the original reaches the second original detection unit 27, the intensity of the detection light received by the second original detection unit 27 becomes equal to or greater than a predetermined value. The control unit 50 can detect the passage of the leading or trailing end of the original at the arrangement position of the second original detection unit 27 based on the signal received from the second original detection unit 27. The second original detection unit 27 may adopt a transmission type sensor instead of a reflective sensor, or may be composed of a contact type sensor, although it is composed of a non-contact type sensor in this embodiment.

[0047] The above-described feed roller 10 and control unit 50, together with a stopper 21 described later, constitute a document transport device 3 (see FIGS. 1 and 2) which is an example of a medium transport device. From another perspective, the document transport device 3 can be regarded as a device in which the function related to document reading, i.e., the reading unit 20, has been removed from the scanner 1. Alternatively, even if the function related to document reading, i.e., the reading unit 20, is provided, from the viewpoint of document transport, the scanner 1 itself can be regarded as a document transport device. The rigidity detection unit 29 and the skew detection unit 31 are optional components of the document transport device 3.

[0048] Next, the skew correction control using the stopper 21 will be described. 1 and 2, a stopper 21 is provided downstream of the feed roller 10 in the conveying path 6. The stopper 21 is provided so as to be switchable between a blocking state in which the conveying path 6 is blocked as shown in FIG 1 and an opening state in which the conveying path 6 is opened as shown in FIG 2. The state of the stopper 21 is switched by the power of a solenoid 61 controlled by the control unit 50.

[0049] 4 to 6, the stopper 21 is made up of a plurality of stoppers, specifically including a left outer stopper 21A, a left inner stopper 21B, a right inner stopper 21C, and a right outer stopper 21D. The stoppers are arranged symmetrically with respect to a center position CL. In this embodiment, the stoppers are provided at approximately equal intervals along the X-axis direction, but this is not limited as long as they are arranged symmetrically with respect to the center position CL. In this embodiment, two stoppers are provided on each side of the center position CL, but three or more stoppers may be provided, or only one stopper may be provided on each side of the center position CL. Alternatively, the stopper 21 may be composed of a single member formed to be symmetrical with respect to the center position CL.

[0050] In this embodiment, the left outer stopper 21A is driven by a left outer solenoid 61A (see FIG. 3). The left inner stopper 21B is driven by a left inner solenoid 61B (see FIG. 3). The right inner stopper 21C is driven by a right inner solenoid 61C (see FIG. 3). The right outer stopper 21D is driven by a right outer solenoid 61D (see FIG. 3). That is, in this embodiment, each stopper can be driven independently. However, it is also possible to configure all the stoppers to be driven by one solenoid.

[0051] When feeding of the document starts, the stopper 21 is in the blocking state. Fig. 4 shows a state in which the document P1 is fed in a skewed state, and the leading left side of the leading edge Ps hits the left outer stopper 21A in the blocking state. Of course, if the skew direction is opposite to that in Fig. 4, the leading right side of the leading edge Ps hits the right outer stopper 21D. Also, if the document size is small, the leading side of the leading edge Ps hits the left inner stopper 21B or the right inner stopper 21C.

[0052] In the example shown in Fig. 4, when the leading left side of the leading edge Ps of the document P1 hits the left outer stopper 21A, the document P1 continues to receive a feeding force from the feed roller 10 and rotates as shown by the change from Fig. 4 to Fig. 5, with the part where the document P1 hits the left outer stopper 21A as a fulcrum. In Fig. 5, the arrow Ra indicates the rotation direction of the document P1 at this time. By rotating the document P1 in this manner, the skew of the document P1 is corrected. As described above, the skew correction control is performed by abutting the leading edge of the document against the stopper 21 in the blocked state and continuing the rotation of the feed roller 10 to promote the rotation of the document. This skew correction control ends when the stopper 21 is switched from the blocked state to the open state.

[0053] However, in the case of the document P2, which has a lower rigidity than the document P1 described above, when the leading left side of the leading edge Ps hits the left outer stopper 21A in the blocked state as shown in Fig. 6, the hit portion may be crushed as shown by the symbol Pm. In this case, the document P2 does not rotate, and the skew cannot be properly corrected. In consideration of such a problem, the control unit 50 performs a predetermined control according to the rigidity of the document.

[0054] The skew correction control will be further described below with reference to Fig. 7. Fig. 7 shows an example of control that does not use the skew detection unit 31 described above. When the control unit 50 receives a command to start reading the document, it starts rotating the feed roller 10 (step S101). Then, when the first document detection unit 26 detects the leading edge of the document (Yes in step S102), it acquires a detection value by the rigidity detection unit 29 (step S103) and determines whether the acquired detection value is less than a predetermined threshold value Ka (step S104).

[0055] That is, it is determined whether the document being conveyed is a first document (No in step S104) or a second document having lower rigidity than the first document (Yes in step S104). A first document means a document for which the detection value in rigidity detection unit 29 is equal to or greater than threshold value Ka, and a second document means a document for which the detection value in rigidity detection unit 29 is less than threshold value Ka. Document P1 described with reference to Figs. 4 and 5 is an example of a first document, and document P2 described with reference to Fig. 6 is an example of a second document.

[0056] If the detection value by the stiffness detection unit 29 is equal to or greater than the threshold value Ka (No in step S104), i.e., in the case of the first original, the control unit 50 selects time t1 as the skew correction time. If the detection value by the stiffness detection unit 29 is less than the threshold value Ka (Yes in step S104), i.e., in the case of the second original, the control unit 50 selects time t2 as the skew correction time. As will be described in detail later, time t2 is set to be shorter than time t1.

[0057] Next, the control unit 50 corrects the skew of the document (step S107), and after the skew correction, the process proceeds to reading the document (step S108). Here, as for the skew correction time in step S107, either time t1 or time t2 is selected according to the detection value by the rigidity detection unit 29, as described above. The skew correction time is, for example, the time from when the leading edge of the original is detected by the first original detection unit 26 to when the solenoid 61 is controlled to switch the stopper 21 from the closed state to the open state. In particular, time t1 is set to a suitable time for the first original, which has a relatively higher rigidity than the second original, to be skew corrected as shown by the change from Fig. 4 to Fig. 5, and is determined experimentally.

[0058] Here, time t2 is set shorter than time t1, for example, time t2 is set to about 70% to 90% of time t1. As a result, when the second original is transported, the timing at which stopper 21 switches from the closed state to the open state, that is, the timing at which skew correction control ends, is earlier in the case of the second original than in the case of the first original. As described above, the control unit 50 capable of executing skew correction control can obtain information related to the rigidity of the document, and when a second document having a lower rigidity than the first document is transported, the control unit 50 switches the stopper 21 from the closed state to the open state and ends the skew correction control earlier than when the first document is transported. This makes it possible to suppress crushing caused by the leading edge of the document hitting the stopper 21 when the second document having a lower rigidity than the first document is transported. In the above example, the rigidity of the original is classified into two types and two types of skew correction time are set accordingly, but the present invention is not limited to this, and the rigidity of the original may be classified into three or more types and three or more types of skew correction time may be set accordingly. In other words, the first original and the second original having a lower rigidity merely represent the relative rigidity, and the rigidity of the original is not limited to being classified into two types.

[0059] In the example of Figure 7, the rigidity of the document is grasped using the rigidity detection unit 29, but it is also possible to use the operation panel 51 as an information input unit that accepts input of information related to the type of document, and have the operation panel 51 display a UI that accepts input of information related to the type of document, and have the control unit 50 grasp the rigidity of the document based on the information obtained via this UI. As the UI, for example, a pull-down menu from which the type of document can be selected is displayed along with a message saying "Please set the type of document." The types of documents include, for example, "thin paper," "plain paper," and "photo paper." The stiffness of the document increases in the order of "thin paper," "plain paper," and "photo paper," with "thin paper" classified as the second document, and "plain paper" and "photo paper" classified as the first document. In this manner, the control unit 50 is configured to determine the stiffness of the document based on the type of document inputted to the information input unit, so that the stiffness of the document can be accurately grasped. As another embodiment, a UI that accepts the selection of a document reading mode may be displayed as the UI, and the control unit 50 may grasp the rigidity of the document based on information obtained via this UI. The document reading modes include "thin paper mode", "plain paper mode", and "thick paper mode". The rigidity of the document increases in the order of "thin paper mode", "plain paper mode", and "thick paper mode", with "thin paper mode" classified as the second document, and "plain paper mode" and "thick paper mode" classified as the first document.

[0060] Incidentally, in the case where the control unit 50 can obtain information related to the stiffness of the document via the UI as described above, the stiffness detection unit 29 can be omitted, but it is also preferable to provide the stiffness detection unit 29 and make it possible to display the above-mentioned UI, and to allow the user to select whether or not to display the above-mentioned UI.

[0061] When the control unit 50 determines that a document is present on the document placement unit 5 based on information received from the placement detection unit 28 during the transport standby state, the control unit 50 may display the above-mentioned UI on the operation panel 51. This eliminates the need for the user to perform an operation to display the above-mentioned UI, improving usability for the user.

[0062] The control unit 50 may be configured to execute standby control, waiting for a document to be placed on the document placement unit 5 when there is no document on the document placement unit 5, and, when it determines that a document has been placed on the document placement unit 5 based on information received from the placement detection unit 28, rotating the feed roller 10 in the forward direction to feed the document from the document placement unit 5. In this case, after acquiring information related to the stiffness of the document in the standby control, the control unit 50 may be configured to feed the document from the document placement unit 5 without displaying the UI on the operation panel 51. This eliminates the need for the user to input information related to the stiffness of the document every time the document is placed on the document placement unit 5, improving the usability of the device. The standby control is, for example, a control for placing documents one by one on the document placement unit 5 and sending out the documents. In this case, for example, the UI may be displayed when the first document is placed on the document placement unit 5, and the UI may not be displayed when the second or subsequent documents are placed.

[0063] Next, another embodiment of the skew correction control will be described with reference to Fig. 8. Fig. 8 shows an example of the control using the skew detection unit 31. Steps S201 to S207 in FIG. 8 are similar to steps S101 to S107 in FIG. 7, and therefore will not be described below. In step S208, the skew detection unit 31 is used to determine whether the skew of the leading edge of the document is within the allowable range, in other words, whether the degree of skew exceeds a predetermined level. For example, as shown in Fig. 5, if at least the left inner detection unit 31B and the right inner detection unit 31C in the center in the X-axis direction detect the document, the skew of the document is deemed to be within the allowable range. Therefore, it is preferable to set the distance between the stopper 21 and the skew detection unit 31 in the Y-axis direction based on the allowable degree of skew. Furthermore, when the size of the original document is small, the left outer detection unit 31A and the right outer detection unit 31D do not detect the original document regardless of whether or not it is skewed, so the left outer detection unit 31A and the right outer detection unit 31D do not need to be used to determine whether or not the skew is within the acceptable range.

[0064] If the condition for skew is that the left inner detection unit 31B and the right inner detection unit 31C at the center in the X-axis direction detect the original, then it can be determined that the skew of the original exceeds a predetermined level in the example shown in Fig. 6. Note that in the example of Fig. 6, if the feeding of the original is continued, there is a risk that the left inner detection unit 31B and the right inner detection unit 31C may detect the original with the leading edge of the original being crushed, but as described above, the time for skew correction control is suppressed for the second original with low rigidity, so such a problem can be avoided.

[0065] However, if the amount of document feed exceeds the expected range, for example, if the document feed advances further in the example of Fig. 6, the document may be crushed at the leading edge, causing the left inner detection unit 31B and the right inner detection unit 31C to detect the document, and only the right outer detection unit 31D to not detect the document. In such a case, there is a risk of erroneously determining that the document is skewed within the allowable range. Therefore, even if the left inner detection unit 31B and the right inner detection unit 31C in the center in the X-axis direction detect the document, if only one of the left outer detection unit 31A and the right outer detection unit 31D detects the document, an error may occur and the process may branch to step S209 described later.

[0066] Next, if the skew of the document is within the allowable range (Yes in step S208), the process proceeds to reading the document (step S210). If the skew of the document exceeds the allowable range (No in step S208), the process proceeds to error processing (step S209). In this way, by proceeding to error processing when the skew correction of the document is not satisfactory, an appropriate processing result can be obtained.

[0067] As the error processing in step S209, for example, a process of continuing the skew correction control by decelerating the rotation speed of the feed roller 10 can be performed. This is expected to progress the skew correction by the rotation of the document while suppressing the crushing caused by the leading edge of the document hitting the stopper 21.

[0068] Alternatively, as the error processing in step S209, for example, the feed roller 10 may be rotated in the reverse direction to return the document upstream and perform the skew correction control again. This allows the skew correction control to be retried, and it is expected that the skew correction will be performed satisfactorily.

[0069] Alternatively, the error processing in step S209 can be a process of stopping the feed roller 10 and instructing the operation panel 51 to reset the document on the document placement unit 5. By having the user reset the document on the document placement unit 5, it is possible to expect that the document will be transported with less skew the next time it is transported. In this example, skew of the document is detected after feeding of the document is started, and the user is prompted to reset the document on the document placement unit 5, but skew of the document may be detected before feeding of the document is started, and the user may be prompted to reset the document on the document placement unit 5 in the same manner. This is because the leading edge of the document may get downstream of the feed roller 10 before feeding starts.

[0070] Next, a configuration for making it easier to rotate the document during skew correction control will be described with reference to Figures 9 and 10. Note that the stiffness imparting unit described below with reference to Figures 9 and 10 is not an essential component of the document transport device 3. 9 and 10, reference numeral 23A denotes a first stiffness imparting portion, and reference numeral 23B denotes a second stiffness imparting portion. Although not shown, the first stiffness imparting portion 23A and the second stiffness imparting portion 23B are provided at a position downstream of the feed roller 10 and upstream of the stopper 21 in the conveying path 6 shown in FIG.

[0071] The first stiffness imparting section 23A and the second stiffness imparting section 23B are provided so as to be switchable between a state in which they advance into the conveying path 6 as shown in Fig. 9 and a state in which they retreat from the conveying path 6 as shown in Fig. 10. The state of the first stiffness imparting section 23A is switched by a first solenoid 63A controlled by the control section 50, and the state of the second stiffness imparting section 23B is switched by a second solenoid 63B controlled by the control section 50. In this embodiment, an independent solenoid is provided for each of the first stiffness imparting section 23A and the second stiffness imparting section 23B, but the first stiffness imparting section 23A and the second stiffness imparting section 23B may be driven by a single solenoid.

[0072] The first stiffness imparting section 23A and the second stiffness imparting section 23B are in a state of advancing into the conveying path 6 as shown in FIG. 9, at least during execution of the skew correction control, according to the stiffness of the document. In FIG. 9, the symbol P2 indicates the above-mentioned second document, and the second document P2 is formed with a nip portion formed by the feed roller 10 and the separation pad 11, and a wavy shape along the X-axis direction by the first stiffness imparting section 23A and the second stiffness imparting section 23B. This improves the stiffness of the second document P2 in the document feed direction. When the stiffness in the document feed direction is improved, the entire document becomes easier to rotate when the leading edge of the document hits the stopper 21, and thus the skew can be corrected better. In the case of the first original P1, which has higher rigidity and is easier to rotate than the second original P2, the first rigidity imparting section 23A and the second rigidity imparting section 23B are maintained in a retracted state from the conveying path 6 throughout the entire process of feeding, reading, and discharging the original, including during execution of the skew correction control, as shown in Fig. 10. This makes it possible to avoid excessive conveying load being applied to the first original P1. In the example of Figs. 9 and 10, one stiffness imparting portion is provided on each side so as to be symmetrical with respect to the center position CL in the X-axis direction, but it goes without saying that two or more stiffness imparting portions may be provided.

[0073] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these modifications are also included in the scope of the present invention. Furthermore, in the above embodiment, the medium transport device is applied to the scanner 1, which is an example of an image reading device, but it can also be applied to a recording device that records on a medium, in particular an inkjet printer. [Explanation of symbols]

[0074] 1...scanner, 2a...lower unit, 2b...upper unit, 3...original transport device, 5...original placement section, 6...transport path, 10...feed roller, 11...separation pad, 12...upper path forming member, 13...lower path forming member, 16...first transport roller pair, 16a...driving roller, 16b...driven roller, 17...second transport roller pair, 17a...driving roller, 17b...driven roller, 18...discharge port, 20...reading section, 20A...lower sensor unit, 20B...upper sensor unit, 21...stopper, 21A...left outer stopper, 21B...left inner stopper, 21C...right inner stopper, 2 1D...right outer stopper, 23A...first stiffness imparting section, 23B...second stiffness imparting section, 26...first original detection section, 27...second original detection section, 28...placement detection section, 29...stiffness detection section, 29a...ultrasonic transmission section, 29b...ultrasonic reception section, 31...skew detection section, 31A...left outer detection section, 31B...left inner detection section, 31C...right inner detection section, 31D...right outer detection section, 50...control section, 51...operation panel, 52...feed motor, 53...transport motor, 55...CPU, 56...flash ROM, 57...RAM, 58...interface, 61...solenoid, 61A...left outer solenoid, 61B...left inner solenoid, 61C...right inner solenoid, 61D...right outer solenoid, 63A...first solenoid, 63B...second solenoid, 90...external computer

Claims

1. a feed roller for feeding the medium downstream; at least one stopper located downstream of the feed roller in a transport path along which a medium is transported, the stopper being switchable between a blocking state for blocking the transport path and an open state for opening the transport path; a control unit that controls the rotation of the feed roller and the state switching of the stopper, the control unit being capable of executing skew correction control that corrects skew of the medium by abutting a leading edge of the medium against the stopper that is in the blocked state; a skew detection unit that is provided in the conveying path at a position downstream of the feed roller and upstream of the stopper, and detects skew of a leading edge of the medium; Equipped with the control unit is capable of acquiring information related to the rigidity of the medium, and when a second medium having a lower rigidity than a first medium is transported, the control unit switches the stopper from the closed state to the open state and ends the skew correction control earlier than the timing for the first medium; Furthermore, the control unit performs error processing when the skew of the medium exceeds a predetermined degree at the time when the skew correction control is executed for a predetermined time based on the information received from the skew detection unit. A medium transport device comprising:

2. 2. The medium transport device according to claim 1, wherein the error process is a process of continuing the skew correction control by decelerating the rotation speed of the feed roller. A medium transport device comprising:

3. 2. The medium transport device according to claim 1, wherein the error process is a process of reversing the rotation of the feed roller to return the medium upstream and retrying the skew correction control. A medium transport device comprising:

4. 2. The medium conveying device according to claim 1, further comprising: a display device for displaying various information; a medium placement section for placing a medium to be fed by the feed roller; the error processing is processing for stopping the feed roller and instructing the display device to reset the medium on the medium placement unit; A medium transport device comprising:

5. 5. The medium transport device according to claim 1, wherein the control unit determines the stiffness of the medium based on a thickness of the medium. A medium transport device comprising:

6. 6. The medium transport device according to claim 5, further comprising a thickness detector for detecting a thickness of the medium, the thickness detector being disposed downstream of the feed roller and upstream of the stopper in the transport path. A medium transport device comprising:

7. 5. The medium conveying device according to claim 1, further comprising an information input unit that receives input of information related to a type of medium, The control unit determines the stiffness of the medium based on the type of the medium inputted to the information input unit. A medium transport device comprising:

8. a feed roller for feeding the medium downstream; a medium placement section for placing a medium to be fed by the feed roller; at least one stopper located downstream of the feed roller in a transport path along which a medium is transported, the stopper being switchable between a blocking state for blocking the transport path and an open state for opening the transport path; a control unit that controls the rotation of the feed roller and the state switching of the stopper, the control unit being capable of executing skew correction control that corrects skew of the medium by abutting a leading edge of the medium against the stopper that is in the blocked state; a placement detection unit for detecting the presence or absence of a medium on the medium placement unit; an information input unit that receives input of information related to the type of medium, the information input unit being configured with a display device that displays various information; Equipped with the control unit is capable of acquiring information related to the rigidity of the medium based on the type of medium input to the information input unit, and when a second medium having a lower rigidity than a first medium is transported, the control unit switches the stopper from the blocked state to the open state and ends the skew correction control earlier than the timing for the first medium; Furthermore, the control unit is capable of displaying, on the display device, a user interface that accepts input of information related to the type of medium, Furthermore, when the control unit determines that a medium is present on the medium placement unit based on information received from the placement detection unit in a transport standby state, the control unit causes the display device to display the user interface; Furthermore, the control unit is capable of executing standby control for waiting for a medium to be placed on the medium placement unit when there is no medium on the medium placement unit, and when it determines that a medium has been placed on the medium placement unit based on information received from the placement detection unit, rotating the feed roller in the forward direction to feed the medium from the medium placement unit, Furthermore, after the control unit acquires information related to the stiffness of the medium during the standby control, the control unit feeds the medium from the medium placement unit without displaying the user interface on the display device. A medium transport device comprising:

9. A medium transport device according to any one of claims 1 to 8, which transports a medium; a reading means for reading a surface of the medium conveyed by the medium conveying device; An image reading device comprising:

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