Document transport device and image reading device

Abstract

It is a relatively low-cost system that detects additional sheets added to the paper tray after the original sheets have been loaded. [Solution] The flip-up detection sensor 23 detects when a stapled document flips up when the document sheet is fed by the transport device 21. The controller 51 then (a) when a stack of document sheets is placed on the paper feed tray 11, controls the lifting device 22 to raise the paper feed tray 11 so that the stack of document sheets is positioned at the paper feed position, (b) after the stack of document sheets is positioned at the paper feed position, but before the feeding of the document sheets begins, if the flip-up detection sensor 23 detects an object, the controller 51 determines that an additional stack of sheets has been detected, (c) when the flip-up detection sensor 23 determines that an additional stack of sheets has been detected, (d) controls the lifting device 22 to lower the paper feed tray 11.

Description

Technical Field

[0001] The present invention relates to a document conveying apparatus and an image reading apparatus.

Background Art

[0002] A certain document conveying apparatus includes an additional sheet detection sensor that detects an additional sheet added after a sheet is set on a paper feed tray. When the additional sheet detection sensor detects an additional sheet, the paper feed tray is returned to the standby position (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in order to detect an additional sheet added after a sheet is set on the paper feed tray, adding a dedicated sensor as the above-described additional sheet detection sensor increases the cost of the apparatus.

[0005] The present invention has been made in view of the above problems, and an object thereof is to obtain a document conveying apparatus and an image reading apparatus that can detect an additional sheet added after a sheet is set on a paper feed tray at a relatively low cost.

Means for Solving the Problems

[0006] The document transport device according to the present invention comprises a paper feed tray on which a stack of document sheets is placed, a transport device that feeds one document sheet at a time from the stack of document sheets and transports them along a transport path to an output tray, a lifting device that raises and lowers the paper feed tray, a bounce detection sensor that detects the bounce of the stack of document sheets when the transport device feeds the document sheets in the case that the stack of document sheets on the paper feed tray is stapled, and a controller that controls the lifting device to change the height position of the paper feed tray. Here, the bounce detection sensor is a sensor that detects an object at a predetermined position higher than the paper feeding position. The controller then (a) when a stack of document sheets is placed on the paper feed tray, controls the lifting device to raise the paper feed tray so that the stack of document sheets is positioned at the paper feed position; (b) after the stack of document sheets is positioned at the paper feed position, but before the feeding of the document sheets begins, if the flip-up detection sensor detects an object, the flip-up detection sensor determines that an additional stack of sheets has been detected; (c) when the flip-up detection sensor determines that an additional stack of sheets has been detected, (d) controls the lifting device to lower the paper feed tray.

[0007] The image reading device according to the present invention comprises the above-described document transport device and an image sensor that reads an image of the document sheet at a predetermined position in the transport path. [Effects of the Invention]

[0008] According to the present invention, a document transport device and an image reading device can be obtained that can detect additional sheets added after a sheet has been set on the paper feed tray, at a relatively low cost.

[0009] The above or other objects, features, and advantages of the present invention will become even more apparent from the following detailed description in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a side view showing the internal configuration of an image reading device according to an embodiment of the present invention. [Figure 2] Figure 2 is a perspective view showing an example of the placement of the flip-up detection sensor 23 in the image reading device shown in Figure 1. [Figure 3] Figure 3 is a block diagram showing the electrical configuration of the automatic document feeder 4 in Figure 1. [Figure 4] Figure 4 is a flowchart illustrating the operation of the image reading device shown in Figures 1 to 3. [Figure 5] Figure 5 illustrates the upward movement of the paper feed tray 11 on which the stack of document sheets is placed. [Figure 6] Figure 6 illustrates the detection of additional sheet bundles. [Figure 7] Figure 7 illustrates the lowering of the paper feed tray 11 when an additional sheet bundle is detected. [Figure 8] Figure 8 illustrates the re-raising of the paper feed tray 11. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the figures.

[0012] Figure 1 is a side view showing the internal configuration of an image reading device according to an embodiment of the present invention. The image reading device shown in Figure 1 is a device such as a scanner, copier, facsimile machine, or multifunction device, and is equipped with an automatic document feeder as a document transport device.

[0013] The image reading device shown in Figure 1 comprises a main unit 1, contact glasses 1a and 1b positioned on the top surface of the main unit 1, an image sensor 2, and a document cover 3. The document cover 3 includes an automatic document feeder 4.

[0014] Contact glass 1a is a transparent component on which the document is placed when image scanning is performed without using the automatic document feeder 4. Contact glass 1b is a transparent component over which the document passes when the document is automatically transported by the automatic document feeder 4 while the document image is scanned.

[0015] The image sensor 2 reads the document image from the document sheet. Specifically, when the image sensor 2 reads the document image while automatically conveying the document with the automatic document feeder 4, it is a sensor that optically reads the document image of the document passing through a predetermined image reading position in the document conveyance path. The image sensor 2 reads the document image one line at a time. The image sensor 2 includes a light source (such as a light-emitting diode) and a light-receiving element (such as a line sensor), emits light with the light source, detects the reflected light reflected from the document or the like through the contact glasses 1a and 1b with the light-receiving element, and outputs an electrical signal corresponding to the amount of the reflected light. The controller 23 described later receives this electrical signal and generates a document image (that is, the image data of the document image) based on this electrical signal.

[0016] The document cover 3 is a member that can be in surface contact with the contact glass 1a and is rotatably installed, which presses the document against the contact glass 1a and prevents ambient light from entering the inside of the apparatus from the contact glasses 1a and 1b during image reading.

[0017] Also, the automatic document feeder 4 includes a paper feed tray 11 on which the document sheet is placed and a conveyance device 21. The conveyance device 21 conveys the document sheets one by one along the conveyance path from the stack of document sheets on the paper feed tray 11 to the discharge tray 14. The automatic document feeder 4 controls the conveyance device 21 to pass the document sheets one by one through the reading position of the image sensor 2 (the position on the contact glass 1b) by the conveyance device 21 and discharges them to the discharge tray 14.

[0018] Specifically, the conveyance device 21 includes a paper feed unit 12 and conveyance rollers 13 along the conveyance path, and the paper feed unit 12 feeds the document sheet (the uppermost document sheet in the stack of document sheets) and conveys it by the conveyance rollers 13. The paper feed unit 12 includes a paper feed roller 12a, a drive roller 12b, a driven roller 12c, a conveyance belt 12d, and an auxiliary roller 12e, and the paper feed roller 12a feeds the document sheets on the paper feed tray 11 one by one along the conveyance belt 12d into the conveyance path.

[0019] Also, the image sensor 2 can change its image reading position by a driving device (not shown). When performing image reading using the automatic document feeder 4, the image reading position of the image sensor 2 is set to the passing position of the document on the contact glass 1b. The image sensor 2 optically reads the image of the document conveyed by the automatic document feeder 4 when passing over the contact glass 1b. Here, the image sensor 2 is a color image sensor and reads document images of multiple colors such as RGB at different image reading positions in the conveyance direction. In this embodiment, a CIS (Contact Image Sensor) is used as the image sensor 2, and when performing image reading using the automatic document feeder 4, the image sensor 2 is disposed directly below the contact glass 1b.

[0020] Note that the paper feed roller 12a, the drive roller 12b, and the conveyance roller 13 are driven by a driving device (not shown) such as a motor.

[0021] The discharge tray 14 is located below the paper feed tray 11 and is a tray on which the document sheets discharged from the discharge port 15 at the end of the conveyance path are stacked. The discharge port 15 discharges the document sheets to the discharge tray 14 at the end of the conveyance path.

[0022] Furthermore, the image reading device shown in FIG. 1 includes a lifting device 22, a bounce detection sensor 23, and an image sensor 31.

[0023] The lifting device 22 raises and lowers the paper feed tray 11 by an existing lifting method. Specifically, the lifting device 22 includes an electrically operating driving power source (such as a motor, an actuator, etc.), and mechanically raises and lowers the paper feed tray 11 with the driving force generated by the driving power source.

[0024] The bounce detection sensor 23 detects when the document sheet stack on the paper feed tray 11 bounces up when the document sheet is fed by the transport device 21, in cases where the document sheet stack on the paper feed tray 11 is stapled in place.

[0025] Specifically, the flip-up detection sensor 23 is a sensor that detects an object at a predetermined position higher than the paper feed position in the height direction (i.e., the contact position between the paper feed roller 12a and the top surface of the document sheet stack), and in this case, it is an optical sensor.

[0026] Figure 2 is a perspective view showing an example of the arrangement of the flip-up detection sensor 23 in the image reading device shown in Figure 1. For example, the flip-up detection sensor 23 is a reflective optical sensor comprising a light-emitting element and a light-receiving element, and is arranged such that its optical path passes through the predetermined position described above, as shown in Figure 2, for example.

[0027] Furthermore, the image sensor 31 generates a scanned image by optically reading the image of the document sheet at a predetermined position in the transport path. The image sensor 31 is similar to the image sensor 2, for example, a CIS. Here, the image of one side of the document sheet is read by the image sensor 31, and the image of the other side is read by the image sensor 2.

[0028] Figure 3 is a block diagram showing the electrical configuration of the automatic document feeder 4 in Figure 1. As shown in Figure 3, the image reading device further includes a paper feed tray sheet sensor 41, a paper feed tray upper limit sensor 42, a paper feed tray underside sensor 43, an output tray sheet sensor 44, an output tray sheet amount sensor 45, and a controller 51.

[0029] The paper feed tray sheet sensor 41 detects the stack of original sheets on the paper feed tray 11 and outputs a sensor signal indicating the presence or absence of the stack of original sheets.

[0030] The paper tray upper limit sensor 42 is a sensor that detects when the paper tray 11 has reached its upper limit height. Specifically, the paper tray upper limit sensor 42 detects when the paper tray 11 or the top surface of the stack of document sheets placed on the paper tray 11 comes into contact with the paper feed roller 12a.

[0031] The paper feed tray underside sensor 43 is located on the underside of the paper feed tray 11 and detects contact with objects (such as the output tray 14 or the document sheet on the output tray 14).

[0032] The output tray sheet sensor 44 detects the document sheet on the output tray 14 and outputs a sensor signal indicating the presence or absence of the document sheet.

[0033] The output tray sheet quantity sensor 45 detects the amount of original sheets (thickness of the sheet stack) on the output tray 14.

[0034] The controller 51 is equipped with a processor and an ASIC (Application Specific Integrated Circuit) for executing programs, and controls the automatic document feeder 4 (transport device 21, lifting device 22, etc.) to transport the document sheet, and also performs image reading with image sensors 2 and 31 to acquire image data of the document sheet (document image).

[0035] Furthermore, the controller 51 controls the lifting device 22 to change the height position of the paper feed tray 11.

[0036] Specifically, when a stack of document sheets is placed on the paper feed tray 11, the controller 51 controls the lifting device 22 to raise the paper feed tray 11 so that the stack of document sheets is positioned in the paper feed position. The presence of a stack of document sheets on the paper feed tray 11 is detected by the paper feed tray sheet sensor 41. The position of the stack of document sheets in the paper feed position is detected by the paper feed tray upper limit sensor 42.

[0037] Furthermore, after the stack of original sheets is placed in the paper feed position, but before the feeding of the original sheets begins, the controller 51 determines that the flip-up detection sensor 23 has detected an additional stack of sheets if it detects an object. When the controller 51 determines that the flip-up detection sensor 23 has detected an additional stack of sheets, it controls the lifting device 22 to lower the paper feed tray 11.

[0038] Here, when the controller 51 lowers the paper feed tray 11, it lowers the paper feed tray 11 until it contacts the output tray 14 or the upper surface of the document sheet stacked on the output tray 14. Specifically, when the paper feed tray underside sensor 43 detects contact of an object with the underside of the paper feed tray 11, the controller 51 stops lowering the paper feed tray 11.

[0039] Furthermore, after the controller 51 lowers the paper feed tray 11, it automatically controls the lifting device 22 after a predetermined time has elapsed to raise the paper feed tray 11 back up to the paper feed position. In other words, during this predetermined time, the user adds an additional stack of sheets on top of or below the original stack of sheets, so that the original stack of sheets and the additional stack of sheets are placed on the paper feed tray 11 as a single stack of sheets. Therefore, when the paper feed tray 11 is raised again, the original stack of sheets and the additional stack of sheets are placed on the paper feed tray 11.

[0040] Furthermore, the controller 51 may, after lowering the paper feed tray 11, automatically raise the paper feed tray 11 back up to the paper feed position when the paper feed tray sheet sensor 41 detects that the stack of original sheets on the paper feed tray 11 has been removed and a new stack of original sheets (for example, the original stack of original sheets and an additional stack of sheets) has been placed on it.

[0041] Next, the operation of the image reading device described above will be explained. Figure 4 is a flowchart illustrating the operation of the image reading device shown in Figures 1 to 3. Figure 5 illustrates the raising of the paper feed tray 11 on which the stack of original sheets is placed. Figure 6 illustrates the detection of an additional stack of sheets. Figure 7 illustrates the lowering of the paper feed tray 11 when an additional stack of sheets is detected. Figure 8 illustrates the raising of the paper feed tray 11 again.

[0042] In standby mode, the controller 51 controls the lifting device 22 to position the paper feed tray 11 at a predetermined height so that the stack of document sheets can be placed on it. When the stack of document sheets is placed on the paper feed tray 11, the paper feed tray sheet sensor 41 detects the placement of the stack of document sheets 101 (step S1), as shown in Figure 5, for example, and controls the lifting device 22 to raise the paper feed tray 11 to the paper feeding position (step S2). This puts the automatic document feeder 4 into a ready state. Note that, as shown in Figure 5, for example, the flip-up detection sensor 23 is positioned higher than the top surface of the stack of document sheets 101 at the paper feeding position, so the flip-up detection sensor 23 does not turn on at this time.

[0043] In the ready state, the controller 51 monitors whether or not a user operation to start scanning (e.g., pressing the start key) has been detected (step S3), and whether or not the bounce detection sensor 23 has been turned on (i.e., whether or not the bounce detection sensor 23 has detected an object) (step S4).

[0044] If the flip-up detection sensor 23 is detected to be ON (i.e., if the flip-up detection sensor 23 is detected to be ON before paper feeding begins), the controller 51 determines, for example as shown in Figure 6, that the user has placed the additional sheet stack 102 on top of the original sheet stack 101, and controls the lifting device 22 to lower and stop the paper feed tray 11, for example as shown in Figure 7 (step S5).

[0045] Subsequently, the controller 51 waits in that state for a predetermined time (step S6), and after the predetermined time has elapsed, it automatically controls the lifting device 22 to raise the paper feed tray 11 back up to the paper feed position, for example as shown in Figure 8 (step S7). During this predetermined time, the user places the additional sheet stack 102 on top of the original sheet stack 101, aligning it with the original sheet stack 101. When the paper feed tray 11 is raised again, the paper feed position is when the top surface of the additional sheet stack 102 contacts the paper feed roller 12a, for example as shown in Figure 8.

[0046] After the paper tray 11 rises again, the controller 51 returns to steps S3 and S4 and resumes the monitoring described above.

[0047] In the monitoring described above, if the controller 51 detects a user operation to start scanning (for example, pressing the start key), it controls the transport device 21 to start feeding the document sheet (step S8). At that time, the controller 51 determines whether or not the flip-up detection sensor 23 has turned on (i.e., whether or not the flip-up detection sensor 23 has detected an object) (step S9).

[0048] If the flip-up detection sensor 23 is detected to be ON (i.e., if the flip-up detection sensor 23 is detected to be ON after paper feeding has started), the controller 51 determines that the stack of document sheets 101 is a stapled document and stops the scanning operation (step S10). On the other hand, if the flip-up detection sensor 23 remains OFF, the controller 51 performs the scanning operation (transporting the document sheets one by one and reading the images) (step S11).

[0049] As described above, according to the above embodiment, the bounce detection sensor 23 detects the bounce of the document sheet stack when the document sheets are fed by the transport device 21 when the document sheet stack on the paper feed tray 11 is stapled in place. Here, the bounce detection sensor 23 is a sensor that detects an object at a predetermined position higher than the paper feed position. The controller 51 then (a) when the document sheet stack is placed on the paper feed tray 11, controls the lifting device 22 to raise the paper feed tray 11 so that the document sheet stack is positioned at the paper feed position, (b) after the document sheet stack is positioned at the paper feed position but before the feeding of the document sheets begins, if the bounce detection sensor 23 detects an object, the controller 51 determines that the bounce detection sensor 23 has detected an additional sheet stack, and (c) when the bounce detection sensor 23 determines that an additional sheet stack has been detected, (d) controls the lifting device 22 to lower the paper feed tray 11.

[0050] As a result, the additional sheet stack is detected by the flip-up detection sensor 23 for staple document detection, eliminating the need to provide a separate sensor for additional sheet stack detection, and allowing for relatively low-cost detection of the additional sheet stack.

[0051] Furthermore, various changes and modifications to the embodiments described above will be obvious to those skilled in the art. Such changes and modifications may be made without deviating from the spirit and scope of the subject matter and without diminishing the intended advantages. In other words, such changes and modifications are intended to be included in the claims. [Industrial applicability]

[0052] The present invention can be applied, for example, to an image reading device. [Explanation of symbols]

[0053] 4. Automatic document feeder (an example of a document transport device) 11 Paper feed tray 21 Conveying device 22 Lifting device 23. Jump detection sensor 51 Controllers

Claims

1. A paper tray on which stacks of original sheets are placed, A conveying device that feeds one document sheet at a time from the aforementioned stack of document sheets and transports them along a transport path to the output tray, A lifting device for raising and lowering the paper feed tray, A bounce detection sensor for detecting when the stack of original sheets on the paper feed tray is stapled and the original sheets are fed by the transport device, The system includes a controller that controls the lifting device to change the height position of the paper feed tray, The aforementioned paper-flipping detection sensor is a sensor that detects an object at a predetermined position higher than the paper feed position. The controller (a) when a stack of document sheets is placed on the paper feed tray, controls the lifting device to raise the paper feed tray so that the stack of document sheets is positioned at the paper feed position; (b) after the stack of document sheets is positioned at the paper feed position, but before the feeding of the document sheets begins, if the flip-up detection sensor detects an object, the flip-up detection sensor determines that an additional stack of sheets has been detected; (c) when the flip-up detection sensor determines that an additional stack of sheets has been detected, (d) controls the lifting device to lower the paper feed tray. A document transport device characterized by the following.

2. The document transport device according to claim 1, characterized in that the controller automatically controls the lifting device to raise the paper feed tray again after a predetermined time has elapsed since the paper feed tray was lowered.

3. The document transport device according to claim 1, characterized in that, after the controller lowers the paper feed tray, when it detects that the stack of document sheets on the paper feed tray has been removed and a new stack of document sheets has been placed on it, it automatically raises the paper feed tray again.

4. The system further comprises an output tray located below the paper feed tray for stacking the ejected document sheets, When the controller lowers the paper feed tray, it lowers the paper feed tray until it contacts the output tray or the upper surface of the document sheet stacked on the output tray. The document transport device according to claim 1, characterized in that

5. A document transport device according to any one of claims 1 to 4, An image sensor that reads the image of the original sheet at a predetermined position in the transport path, An image reading device characterized by comprising the following:

Images