Document transport device and image reading device

Abstract

To obtain a document transport device and image reading device that have relatively low equipment costs and good convenience. [Solution] The controller (a) when the discharge lift upper limit sensor 41 detects that the discharge port 15 has reached its upper limit height, temporarily stops the transport operation of the transport device 21 to the document sheet until the document sheet on the discharge tray 14 is removed. (b) Also, when attempting to raise the discharge port with the lifting device to a height position corresponding to the amount of sheets on the discharge tray 14, if the height position of the discharge port 15 does not reach the height position corresponding to the amount of sheets even after operating the lifting device for a predetermined time, and the discharge lift upper limit sensor 41 does not detect that the discharge port 15 has reached its upper limit height, the transport operation of the transport device to the document sheet until the document sheet on the discharge tray 14 is removed.

Description

Technical Field

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

Background Art

[0002] A certain document conveying device includes a paper feed tray that can be raised and lowered and a paper discharge tray, and conveys a document sheet along a conveyance path from the paper feed tray to the paper discharge tray through a discharge port (see, for example, Patent Document 1). In that document conveying device, the discharge port as the end of the conveyance path moves up and down according to the thickness of the stack of document sheets on the paper discharge tray.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the document conveying device as described above, since the paper feed tray moves up and down and the discharge port moves up and down, a contact sensor for detecting that the discharge port has contacted the paper feed tray is provided. And in order to suppress the malfunction that occurs when the discharge port contacts the paper feed tray, when the contact sensor detects that the discharge port has contacted the paper feed tray, the document conveying device stops with an error and outputs a service call or the like.

[0005] However, when a contact sensor is provided and an error stop occurs when contact is detected, the device cost increases due to the contact sensor, and the error stop makes it impossible to continue the conveyance operation, which is inconvenient.

[0006] The present invention has been made in view of the above problems, and an object thereof is to obtain a document conveying device and an image reading device with a relatively low device cost and good convenience. [Means for solving the problem]

[0007] The document transport device according to the present invention comprises: a paper feed tray on which a document sheet is placed; an output tray for the document sheet; a transport device for transporting the document sheet from the paper feed tray to the output tray along a transport path; an output port at the end of the transport path for discharging the document sheet to the output tray; a first lifting device for raising and lowering the paper feed tray; a second lifting device for raising and lowering the output port; an output lift upper limit sensor for detecting when the output port has reached a fixed upper limit height; an output tray sheet amount sensor for detecting the amount of the document sheet on the output tray; and a controller for controlling the first lifting device to change the height position of the paper feed tray and controlling the second lifting device to change the height position of the output port according to the amount of the sheet detected by the output tray sheet amount sensor. Furthermore, the controller (a) when the discharge lift upper limit sensor detects that the discharge port has reached the upper limit height, temporarily stops the transport operation of the transport device for the document sheet until the document sheet on the discharge tray is removed; and (b) when attempting to raise the discharge port with the second lifting device to a height position corresponding to the amount of sheet, if the height position of the discharge port does not reach the height position corresponding to the amount of sheet even after operating the second lifting device for a predetermined time, and the discharge lift upper limit sensor does not detect that the discharge port has reached the upper limit height, temporarily stops the transport operation of the transport device for the document sheet until the document sheet on the discharge tray is removed.

[0008] The image reading device according to the present invention comprises the above-mentioned 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]

[0009] According to the present invention, a document transport device and an image reading device can be obtained that have relatively low equipment costs and good convenience.

[0010] 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]

[0011] [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 diagram illustrating the sensors provided in the automatic document feeder 4 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 illustrates the rise of the output port 15 when there is a small amount of original paper sheets on the paper feed tray 11. [Figure 5] Figure 5 illustrates the rise of the output port 15 when there are many original sheets on the paper feed tray 11. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the figures.

[0013] 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.

[0014] The image reading device shown in Figure 1 comprises a main unit 1, contact glass 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 comprises [details omitted].

[0015] 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.

[0016] Image sensor 2 reads the document image from the document sheet. Specifically, when the document is automatically transported by the automatic document feeder 4 and image reading of the document image is performed, image sensor 2 is a sensor that optically reads the document image of the document as it passes through a predetermined image reading position in the document transport path. Image sensor 2 reads the document image line by line. Image sensor 2 is equipped with a light source (such as a light-emitting diode) and a light-receiving element (such as a line sensor). The light source emits light, and the light-receiving element detects the reflected light reflected from the document or other object via the contact glasses 1a and 1b, and outputs an electrical signal corresponding to the amount of reflected light. The controller 51, described later, receives this electrical signal and generates the document image (i.e., image data of the document image) based on this electrical signal.

[0017] The document cover 3 is a component that is rotatably mounted and can make surface contact with the contact glass 1a, ensuring that the document is in close contact with the contact glass 1a and preventing ambient light from entering the device from the contact glass 1a and 1b during image reading. The automatic document feeder 4 includes a paper feed tray 11 on which the document sheet is placed, and a transport device 21 that transports the document sheet from the paper feed tray 11 to the output tray 14 via the reading position of the image sensor 2. The transport device 21 passes each document sheet placed on the paper feed tray 11 over the contact glass 1b and discharges them to the output tray 14. Specifically, the transport device 21 includes a paper feed section 12 and transport rollers 13 along the transport path. The paper feed section 12 feeds the document sheet, which is then transported by the transport rollers 13. The paper feeding unit 12 includes a paper feeding roller 12a, a drive roller 12b, a driven roller 12c, a transport belt 12d, and an auxiliary roller 12e. The paper feeding roller 12a pulls the original sheets on the paper tray 11 one by one along the transport belt 12d into the transport path.

[0018] Further, 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 the document passes over the contact glass 1b. Here, the image sensor 2 is a color image sensor and reads document images of a plurality of 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.

[0019] 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.

[0020] The discharge tray 14 is a tray on which the document sheets discharged and dropped 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.

[0021] Furthermore, the image reading device shown in FIG. 1 includes a lifting device 22 that lifts and lowers the paper feed tray 11 by an existing lifting method, and a lifting device 23 that lifts and lowers the discharge port 15. Specifically, the lifting device 23 rotates the end conveyance path 16 together with the conveyance roller 13 at the end of the conveyance path about a predetermined fulcrum to lift and lower the discharge port 15.

[0022] FIG. 2 is a diagram for explaining the sensors provided in the automatic document feeder 4 in FIG. 1. The automatic document feeder 4 includes a discharge lift upper limit sensor 41, a discharge lift lower limit sensor 42, a discharge tray sheet amount sensor 43, and a paper feed tray upper limit sensor 44.

[0023] The discharge lift upper limit sensor 41 detects when the discharge port 15 has reached a fixed upper limit height. In this case, the discharge lift upper limit sensor 41 is a contact sensor that detects when the transport path 16, which is linked to the discharge port 15, makes contact with it.

[0024] The discharge lift lower limit sensor 42 detects when the discharge port 15 has reached a fixed lower limit height.

[0025] The output tray sheet quantity sensor 43 detects the amount of original sheets (thickness of the sheet stack) on the output tray 14. The output tray sheet quantity sensor 43 is fixed to the output port 15 and moves up and down in conjunction with the raising and lowering of the output port 15.

[0026] The paper tray upper limit sensor 44 is a sensor that detects when the paper tray 11 has reached its upper limit height. Specifically, the paper tray upper limit sensor 44 detects when the paper tray 11 or the document sheet placed on the paper tray 11 comes into contact with the paper feed roller 12a.

[0027] Furthermore, the back of the paper feed tray 11 does not have a contact sensor to detect contact between the paper feed tray 11 and objects (such as the output port 15 or the original document sheet on the output tray 14).

[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 automatic document feeder 4 further includes a controller 51.

[0029] 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 the image sensor 2 to acquire image data of the document sheet (document image).

[0030] Furthermore, the controller 51 controls the lifting device 22 to change the height position of the paper feed tray 11, and controls the lifting device 23 to change the height position of the discharge port 15 according to the amount of sheets detected by the discharge tray sheet amount sensor 43.

[0031] Specifically, the controller 51 adjusts the height of the paper feed tray 11 so that the top surface of the stack of original sheets on the paper feed tray 11 contacts the paper feed roller 12a. The controller 51 also adjusts the height of the output port 15 so that it is positioned a predetermined height higher than the top surface of the stack of original sheets on the output tray 14.

[0032] Figure 4 illustrates the rise of the output port 15 when there are few original sheets on the paper feed tray 11. Figure 5 illustrates the rise of the output port 15 when there are many original sheets on the paper feed tray 11.

[0033] Furthermore, as shown in Figure 4, for example, when the discharge lift upper limit sensor 41 detects that the discharge port 15 has reached the upper limit height, the controller 51 temporarily stops the transport operation of the document sheet 101 by the transport device 21 until the document sheet 101 on the discharge tray 14 is removed.

[0034] Furthermore, as shown in Figure 5, for example, when the controller 51 attempts to raise the output port 15 with the lifting device 23 to a height position corresponding to the amount of original sheet 101 on the output tray 14, if the output port 15 does not reach the height position corresponding to the amount of sheet even after operating the lifting device 23 for a predetermined time, and the output lift upper limit sensor 41 does not detect that the output port 15 has reached the upper limit height (i.e., the output port 15 is in contact with the paper feed tray 11), the controller 51 temporarily stops the transport operation of the original sheet 101 by the transport device 21 until the original sheet 101 on the output tray 14 is removed.

[0035] Subsequently, once the document sheet 101 on the output tray 14 is removed, the controller 51 automatically resumes the transport operation of the transport device 21.

[0036] The removal of the document sheet 101 from the output tray 14 may be detected by the output tray sheet amount sensor 43, or by a sensor (not shown) that detects the document sheet 101 on the output tray 14.

[0037] Furthermore, in this embodiment, if the current height position of the paper feed tray 11 is higher than a predetermined height position, the controller 51 attempts to raise the discharge port 15 with the lifting device 23 to a height position corresponding to the amount of sheets on the discharge tray 14. However, even after operating the lifting device 23 for a predetermined time, if the height position of the discharge port 15 does not reach the height position corresponding to the amount of sheets, and the discharge lift upper limit sensor 41 does not detect that the discharge port 15 has reached the upper limit height, the controller 51 determines that a malfunction has occurred in the lifting device 23 or the discharge lift upper limit sensor 41, issues an error notification (such as a service call) or displays an error, and terminates the transport operation with an error.

[0038] Furthermore, in this embodiment, if the current height position of the paper feed tray 11 is at or below the predetermined height position described above, the controller 51 attempts to raise the output port 15 with the lifting device 23 to a height position corresponding to the amount of sheets on the output tray 14. However, if the height position of the output port 15 does not reach the height position corresponding to the amount of sheets even after operating the lifting device 23 for a predetermined time, and the output lift upper limit sensor 41 does not detect that the output port 15 has reached the upper limit height, the controller 51 temporarily stops the transport operation of the document sheet by the transport device 21 until the document sheet on the output tray 14 is removed.

[0039] Here, the predetermined height position mentioned above is the height position at which the paper feed tray 11 contacts the discharge port 15 when the discharge port 15 reaches its upper limit height.

[0040] Next, the operation of the image reading device described above will be explained.

[0041] When a document sheet 101 is placed on the paper feed tray 11, the controller 51 raises the paper feed tray 11 until the document sheet 101 contacts the paper feed roller 12a (i.e., until the paper feed tray upper limit sensor 44 detects that the paper feed tray 11 has reached its upper limit height). Then, when transporting the document sheets begins, the controller 51 transports the document sheets on the paper feed tray 11 one by one to the output tray 14. At this time, the controller 51 changes the height position of the paper feed tray 11 so that the document sheets on the paper feed tray 11 contact the paper feed roller 12a as the number of document sheets on the paper feed tray 11 decreases, and changes the height position of the output port 15 as the number of document sheets 101 on the output tray 14 increases.

[0042] Then, as shown in Figure 4, for example, when the discharge lift upper limit sensor 41 detects that the discharge port 15 has reached the upper limit height, the controller 51 temporarily stops the transport operation of the transport device 21 to the document sheet 101 until the document sheet 101 on the discharge tray 14 is removed. After that, once the document sheet 101 on the discharge tray 14 is removed, the controller 51 automatically resumes the transport operation of the transport device 21.

[0043] Furthermore, as shown in Figure 5, for example, when attempting to raise the discharge port 15 with the lifting device 23 to a height position corresponding to the amount of document sheets 101 on the discharge tray 14, if the height position of the discharge port 15 does not reach the height position corresponding to the amount of sheets even after operating the lifting device 23 for a predetermined time, and the discharge lift upper limit sensor 41 does not detect that the discharge port 15 has reached the upper limit height, the controller 51 temporarily stops the transport operation of the document sheets 101 by the transport device 21 until the document sheets 101 on the discharge tray 14 are removed. After that, once the document sheets 101 on the discharge tray 14 are removed, the controller 51 automatically resumes the transport operation of the transport device 21.

[0044] As described above, according to the above embodiment, the controller 51 (a) when the discharge lift upper limit sensor 41 detects that the discharge port 15 has reached its upper limit height, temporarily stops the transport operation of the transport device 21 to the document sheet until the document sheet on the discharge tray 14 is removed, and (b) when attempting to raise the discharge port with the lifting device 23 to a height position corresponding to the amount of sheets on the discharge tray 14, if the height position of the discharge port 15 does not reach the height position corresponding to the amount of sheets even after operating the lifting device 23 for a predetermined time, and the discharge lift upper limit sensor 41 does not detect that the discharge port 15 has reached its upper limit height, the transport operation of the transport device 21 to the document sheet until the document sheet on the discharge tray 14 is removed.

[0045] This eliminates the need for a contact sensor to detect contact between the output port 15 and the paper feed tray 11. Furthermore, even if the output port 15 does come into contact with the paper feed tray 11, the document sheet transport operation is only temporarily stopped and automatically resumed, resulting in relatively low device costs and good convenience.

[0046] 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]

[0047] The present invention can be applied, for example, to an image reading device. [Explanation of symbols]

[0048] 4. Automatic document feeder (an example of a document transport device) 11 Paper feed tray 14. Discharge tray 15 Outlet 21 Conveying device 22. Lifting device (an example of a first lifting device) 23. Lifting device (an example of a second lifting device) 41. Discharge lift upper limit sensor 43. Discharge tray sheet volume sensor 51 Controllers

Claims

1. The paper tray on which the original document sheet is placed, An output tray for the aforementioned document sheet, A transport device that transports the original document sheet along a transport path from the paper feed tray to the output tray, At the end of the transport path, there is an outlet for discharging the document sheet to the discharge tray, A first lifting device for raising and lowering the paper feed tray, A second lifting device for raising and lowering the aforementioned discharge port, A discharge lift upper limit sensor that detects when the discharge port has reached a fixed upper limit height, A discharge tray sheet quantity sensor for detecting the amount of the original sheet on the discharge tray, The system includes a controller that controls the first lifting device to change the height position of the paper feed tray, and controls the second lifting device to change the height position of the discharge port according to the amount of sheets detected by the discharge tray sheet amount sensor, The controller (a) when the discharge lift upper limit sensor detects that the discharge port has reached the upper limit height, temporarily stops the transport operation of the transport device for the document sheet until the document sheet on the discharge tray is removed; and (b) when attempting to raise the discharge port with the second lifting device to a height position corresponding to the amount of sheet, if the height position of the discharge port does not reach the height position corresponding to the amount of sheet even after operating the second lifting device for a predetermined time, and the discharge lift upper limit sensor does not detect that the discharge port has reached the upper limit height, temporarily stops the transport operation of the transport device for the document sheet until the document sheet on the discharge tray is removed. A document transport device characterized by the following.

2. The document transport device according to claim 1, characterized in that the controller automatically resumes the transport operation when the document sheet on the output tray is removed.

3. The controller is characterized in that (a) when the current height position of the paper feed tray is higher than a predetermined height position, and when the second lifting device attempts to raise the discharge port to a height position corresponding to the amount of sheets, even after operating the second lifting device for a predetermined time, the height position of the discharge port does not reach the height position corresponding to the amount of sheets, and the discharge lift upper limit sensor does not detect that the discharge port has reached the upper limit height, the controller determines that a malfunction has occurred in the second lifting device or the discharge lift upper limit sensor; and (b) when the current height position of the paper feed tray is at or below the predetermined height position, and when the second lifting device attempts to raise the discharge port to a height position corresponding to the amount of sheets, even after operating the second lifting device for a predetermined time, the height position of the discharge port does not reach the height position corresponding to the amount of sheets, and the discharge lift upper limit sensor does not detect that the discharge port has reached the upper limit height, the controller temporarily stops the transport operation of the document sheet by the transport device until the document sheet on the discharge tray is removed.

4. The document transport device according to claim 3, characterized in that the predetermined height position is the height position at which the paper feed tray contacts the discharge port when the discharge port reaches the upper limit height.

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