JP2020055681A - Image reader - Google Patents

Abstract

To provide an image reader capable of accurately detecting a bound document.SOLUTION: An image reader includes: a document tray on which documents are stacked; a document feeding roller for feeding the documents stacked on the document tray; a separation unit that separates the documents fed by the document feeding roller one by one; a separation drive motor for driving the separation unit; a load torque measuring unit for measuring a load torque of the separated drive motor; skew detection means for detecting skew of the documents using a plurality of skew detection sensors arranged in a direction orthogonal to a transport direction downstream of the separating unit; and control means for stopping feeding of the documents, when the skew detection means detects the skew of the documents exceeding a predetermined amount, and the load torque of the separation drive motor measured by the load torque measuring unit exceeds a threshold value.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image reading apparatus that feeds a document placed on a document tray and reads an image of the fed document by an image reading unit.

  2. Description of the Related Art Generally, there is known an image reading apparatus which is arranged at an upper portion of a printer main body and reads an image of a document. The image reading apparatus has an ADF (Auto Document Feeder) that separates and feeds documents placed on a document tray one by one. The ADF cannot separate and feed a so-called "stitched document" such as a stapled document or a pasted document, and the mechanism within the ADF that separates the document may cause the document to become wrinkled or torn. May be. Further, if the bound document is fed without being separated in the ADF, a jam may occur on the transport path.

  Conventionally, there has been proposed an image reading apparatus in which a plurality of detection sensors are arranged in a width direction of a document conveyance path, and the detection sensors detect skew of the document when the bound document is fed, thereby detecting the bound document. (See Patent Document 1).

JP 2008-247540 A

  The image reading device described in Patent Literature 1 detects a bound document by obliquely moving the document. However, when a folded original is fed instead of a bound original, or when originals are stacked on the original tray without being neatly arranged, the originals may be erroneously detected as bound originals.

  The present invention has been made in view of such a problem, and an object of the present invention is to accurately bind a folded original or a stacked original without being erroneously detected as a bound original. The purpose is to detect a document.

  In order to achieve the above object, an image reading apparatus according to the present invention includes a document tray on which documents are stacked, a feeding roller for feeding the documents stacked on the document tray, and a feeding roller for feeding the documents. A separating unit for separating the separated originals one by one, an image reading unit for reading an image of the original conveyed through the separating unit, a motor for driving the separating unit, and measuring a load torque of the motor. A load torque measuring unit, a skew detection unit that detects skew of the document using a plurality of skew detection sensors disposed downstream of the separation unit, and a skew detection unit that detects a skew of the document exceeding a predetermined amount. When the skew is detected and the load torque of the motor measured by the load torque measurement unit exceeds a threshold value, the control unit stops feeding the document.

  According to the present invention, by measuring the skew of the fed original and the load torque of the motor, the folded original can be detected with high accuracy without erroneously detecting a folded original or an original stacked without being sorted. Can do things.

Overall schematic diagram of image reading device Explanatory diagram of skew detection means Control block diagram of image reading device Flowchart for explaining bound document detection processing Top view of the skew that occurs when a bound document is fed Explanatory diagram showing the occurrence of wrinkles when a bound document is fed Diagram showing changes in sensor output value and load torque when a bound document is fed

  An embodiment of the present invention will be described. The image forming apparatus 100 having the image reading apparatus according to the present embodiment is an electrophotographic laser beam printer. FIG. 1A is an overall schematic diagram of an image forming apparatus 100, and FIG. 1B is a schematic diagram of an image forming engine. As shown in FIG. 1A, the image forming apparatus 100 includes a printer main body 70 and an image reading device 10 mounted on an upper part of the printer main body 70.

  In the following, a sheet includes, in addition to plain paper, special paper such as coated paper, recording material having a special shape such as an envelope or index paper, and a plastic film or cloth for an overhead projector. Is also an example of a sheet.

  The printer body 70 has an image forming engine 60 therein. As shown in FIG. 1B, the image forming engine 60 includes an image forming unit PU as an electrophotographic image forming unit and a fixing device 7. When the start of the image forming operation is instructed, the photosensitive drum 1 as the photosensitive member rotates, and the drum surface is uniformly charged by the charging device 2. Then, the exposure device 3 modulates and outputs the laser beam based on the image data transmitted from the image reading device 10 or an external computer, and scans the surface of the photosensitive drum 1 to form an electrostatic latent image. The electrostatic latent image is visualized (developed) by the toner supplied from the developing device 4 to become a toner image.

  In parallel with such an image forming operation, a feeding operation of feeding sheets stacked on a cassette (not shown) or a manual feed tray toward the image forming engine 60 is executed. The fed sheet is conveyed in accordance with the progress of the image forming operation by the image forming unit PU. Then, the toner image carried on the photosensitive drum 1 is transferred to a sheet by the transfer roller 5. The toner remaining on the photosensitive drum 1 after the transfer of the toner image is collected by the cleaning device 6. The sheet on which the unfixed toner image has been transferred is transferred to the fixing device 7 and is heated and pressed by being nipped by a pair of rollers. The sheet on which the toner is fused and fixed to the sheet to fix the image is discharged by discharge means such as a discharge roller pair.

[Image reading device]
Next, the image reading device 10 will be described in detail. As shown in FIG. 1A, the image reading apparatus 10 has an ADF (Auto Document Feeder) 20 that feeds documents stacked on a document tray 21 and discharges the documents to a discharge tray 32. Further, the image reading device 10 includes a reading unit 40 which is an image reading unit that reads a document conveyed by the ADF 20. The ADF 20 is rotatably supported by the reading unit 40 by a hinge so that the original table glass 41 can be opened. The document D, which is an example of a sheet, may be blank, or may have an image formed on one or both sides.

  The ADF 20 includes a pickup roller 22 as a feeding roller, a separation driving roller 23 and a separation driven roller 24 as a separation unit, a conveyance roller pair 25, read roller pairs 26 and 30, and a discharge roller pair 31. . The ADF 20 has a document presence sensor S21 for detecting the document D on the document tray 21, and a post-separation sensor S22 disposed downstream of the separation driving roller 23 in the sheet feeding direction and detecting the document D. The ADF 20 includes skew detection sensors S1 and S2 that are arranged downstream of the separation driving roller 23 and detect skew of the document D in the document width direction (a direction orthogonal to the feeding direction).

  The reading unit 40 includes a platen glass 28, a jump table 29, a reference white plate 42, a document table glass 41, a first mirror table 43, a second mirror table 44, a lens 45, a CCD line sensor 46, have. A lamp 47 and a mirror 48 are arranged inside the first mirror stand 43, and mirrors 49 and 50 are arranged inside the second mirror stand 44. The first mirror base 43 and the second mirror base 44 are configured to be movable in the sub-scanning direction, which is the horizontal direction in the figure, by a wire and a drive motor (not shown).

  The image reading device 10 scans a document image while feeding the document D stacked on the document tray 21 by the ADF 20, a fixed reading mode for scanning a document placed on the platen glass 41, To read the image on the document D. The drift reading mode is selected when the document D loaded on the document tray 21 is detected by the document presence / absence sensor S21 or when the user explicitly gives an instruction using the operation panel of the printer body 70.

  When the flow reading mode is executed, the pickup roller 22 supported by an arm (not shown) moves down and comes into contact with the uppermost document D on the document tray 21. The document D is fed by the pickup roller 22 and separated one by one in a separation nip N formed by the separation driving roller 23 and the separation driven roller 24. The separation driving roller 23 is formed of a rubber material or the like having a slightly lower friction than the separation driven roller 24. A torque limiter is disposed in a drive transmission path to the separation driven roller 24. The separation driven roller 24 rotates with the separation driving roller 23 when the fed document is one, and the fed document is It does not rotate when there are two or more cards. Therefore, the originals can be separated one by one. In addition, a drive in a direction opposite to the sheet feeding direction may be input to the separation driven roller 24.

  The leading and trailing ends of the document that has passed through the separation nip N are detected by the post-separation sensor S22, and are used as references for raising / lowering timing, driving start and drive stop timing of the pickup roller 22, and driving start and drive stop timing of the transport roller pair 25. Becomes

  The document D to be transported is transported by a transport roller pair 25 and is transported toward a platen glass 28 by a lead roller pair 26. A platen guide roller 27 is arranged to face the platen glass 28, and the platen guide roller 27 guides the document D passing through the platen glass 28 so as not to float off the platen glass 28.

  Then, the image on the surface of the document D is read by the reading unit 40 via the platen glass 28. Specifically, the light of the lamp 47 is applied to the document D being conveyed, and the reflected light from the document D is guided to the lens 45 via the mirrors 48, 49, and 50. Then, the light passing through the lens 45 is imaged on the light receiving portion of the CCD line sensor 46, photoelectrically converted, and the image information is transmitted to the CPU 81. The reference white plate 42 serves as a reference for the reading luminance of the document D. The document D that has passed through the platen glass 28 is guided to a pair of read rollers 30 by a jump table 29, and is discharged to a discharge tray 32 by a pair of discharge rollers 31.

  On the other hand, the fixed reading mode is selected when the apparatus detects the original D placed on the original platen glass 41 or when the user explicitly gives an instruction using the operation panel or the like of the printer body 70. In this case, the document D on the document table glass 41 does not move, and the first mirror table 43 and the second mirror table 44 move along the document table glass 41. Then, the original D is scanned by the light emitted from the lamp 47. The image information photoelectrically converted by the light receiving element of the CCD line sensor 46 is transferred to the CPU 81.

[Skew detection means]
FIG. 2 shows the skew detecting means in the present embodiment. The skew detection means includes a skew detection sensor S1 and a skew detection sensor S2. The skew detection sensors S1 and S2 are arranged downstream of the separation drive roller 23 in the sheet feeding direction in the document width direction. ing. Documents D are stacked on a document tray 21, and the uppermost document D is sent to a position of a separation drive roller 23 by a pickup roller 22 and fed.

[Control block]
FIG. 3 is a control block diagram of the image reading device 10. The input side of the CPU 81 is connected to the skew detection sensor S1, the skew detection sensor S2, the document presence sensor S21, and the post-separation sensor S22. A pickup motor 84 and a separation drive motor 85 are connected to an output side of the CPU 81 via a motor control unit 83. The pickup motor 84 drives the pickup roller 22, and the separation drive motor 85 drives the separation drive roller 23. A load torque measuring unit 86 is connected to the motor control unit 83, and calculates a motor load torque from a load current or the like of the separation drive motor 85. In the present embodiment, the load torque measuring unit 86 is connected to the motor control unit 83, but is not limited to this configuration as long as the load torque of the separation drive motor 85 is measured.

  The operation unit 506 and the storage unit 507 are connected to the CPU 81. The operation unit 506 has, for example, an operation panel, and can start a copy job and perform various settings. The storage unit 507 is fed with a bound document based on a threshold Tth [ms] for detecting skew of the document by the skew detection sensors S1 and S2 and the load torque measured by the load torque measurement unit. The threshold value Nth [N · m] for determining whether or not the current time is stored.

[Binding Document Detection]
Next, a copy operation when a bound document is fed will be described with reference to a flowchart. FIG. 4 is a flowchart showing a copy operation when a document according to the present embodiment is fed. FIG. 5 is a top view of a skew occurring when a bound document is fed. FIG. 5A shows a state in which the bound documents are stacked, and FIG. 5B shows a state in which the bound documents are fed and skew occurs. FIG. 6 shows the occurrence of wrinkles when a bound document is fed. FIG. 6A shows a state immediately after the bound document has entered the separation driving roller, and FIG. 6B shows a state after a predetermined time has elapsed after the bound document has entered the separation driving roller. FIG. 7 shows changes in the output of the sensor and the load torque value when the bound document is fed.

  First, the CPU 81 determines whether a document is loaded on the document tray 21 by the document presence sensor S21 (step S101). If no originals are loaded on the original tray 21 (step S101: No), the CPU 81 does not proceed to the next process and waits until originals are loaded on the original tray 21.

  When it is determined that the originals are loaded on the original tray 21 (step S101: Yes), the CPU 81 determines whether or not the start of the copy job is instructed (step S102). If the start of the copy job has not been instructed from the operation unit 506 (step S102: No), the CPU 81 does not proceed to the next process and waits until the start of the copy job is instructed. When it is determined that the start of the copy job has been instructed (step S102: Yes), the sheet feeding is started in step S103. Here, when the sheet feeding is started, it is detected in steps S104 to S107 whether the document is skewed. Hereinafter, a detection method based on skew when a bound document is fed will be described.

[Skew detection]
First, as shown in FIG. 5A, a document in which the first document D1 and the second document D2 are stapled ST is stacked on the document tray 21. Then, the paper feeding is started (step S103), and when the bound originals D1 and D2 are advanced to the position of the separation driving roller 23 by the pickup roller 22, the separation of the first original D1 and the second original by the separation driving roller 23 is performed. D2 is fed so as to be separated one by one. Here, the first document D1 is advanced by the pickup roller 22 and the separation driving roller 23, whereas the second document D2 is stopped by the separation driving roller 23. Therefore, the first document D1 starts rotating around the staple ST. At this time, since the end of the document opposite to the staple ST advances, the skew detection sensor S1 is turned on (step S104: Yes), and the process proceeds to step S105. In step S105, one of the skew detection sensors S1 is turned on. However, since the end of the original on the side stapled by the staple ST is stopped, the other skew detection sensor S2 is turned on even after a certain time has elapsed. It does not turn on (step S105: No), and the process proceeds to step S106. In step S106, the CPU 81 determines whether the threshold value Tth [ms] stored in the storage unit 507 has elapsed. In step S106, when the threshold value Tth [ms] has elapsed (step S106: Yes), it is determined that the skew is more than the predetermined amount, and the process proceeds to step S110, where the load torque measurement unit 86 loads the separation drive motor 85. Measure the torque.

  If S2 is turned on before the threshold value Tth [ms] elapses in step S105 (step S105: Yes), the process proceeds to step S107. The case where the switch is turned ON before the threshold value Tth [ms] has elapsed is a case where only the skew detection sensor S1 is ON for a short time, that is, the skew is determined to be small. In this case, since the skew is less than the predetermined amount (normal skew original), the currently fed original is passed. After the process proceeds to step S107, the CPU 81 waits until the fed document passes the separated sensor S22 (step S107: No), and when the fed document passes the separated sensor S22 (step S107: Yes), step S108. Move to. In step S108, it is determined whether the document is the last document based on the detection result of the document presence sensor S21. If it is determined that the document is the last document (step S108: Yes), the process proceeds to step S109, and the CPU 81 stops the pickup motor 84 and the separation drive motor 85. If it is determined that the document is not the last document (step S108: No), the process returns to step S103, and the next document is fed.

  Next, the determination of the load torque when it is determined that skew has occurred in step S106 and the process proceeds to step S110 will be described.

[Judgment of load torque]
In step S110, the CPU 81 determines whether or not the load torque measured by the load torque measurement unit 86 exceeds the threshold Nth [N · m]. As shown in FIG. 6A, when the first sheet D1 and the second sheet D2 of the original bound by the staple ST enter the separation driving roller, separation starts. When the paper feed further proceeds, as shown in FIG. 6B, the separation drive roller 23 tries to advance the first document D1. However, since the second document D2 is stopped by the staples St, the force to stop the first document D1 around the staples ST increases. Therefore, as shown in FIG. 7, the load torque of the separation drive motor 85 increases. When the increased load torque exceeds the threshold value Nth [N · m] stored in the storage unit 507 (Step S110: Yes), the process proceeds to Step S109, where the pickup motor 84 and the separation drive motor 85 are stopped and the process ends. . As the threshold value Nth [N · m] stored in the storage unit 507, a threshold value that can be determined to be highly likely to be a bound document is set. When the load torque measured by the load torque measuring unit 86 is less than the threshold value Nth [N · m] (Step S110: No), the process proceeds to Step S111. If it is determined in steps S104 to S106 that there is skew, and if the load torque does not exceed the threshold value Nth [N · m] in step S110, the leading edge of the document as if cut by the user himself is fed. There may be a case where it is desired to feed a document that is not perpendicular to the direction. In step S111, it is determined whether the document D has passed the sensor after separation. If it has not passed through the sensor S22 after separation (Step S111: No), the process returns to Step S110, and the determination of the load torque is continued. If the document has passed the sensor S22 after separation (step S111: Yes), the process proceeds to step S108, and it is determined whether the document is the final document. In the case of the last document (step S108: Yes), the process proceeds to step S109, where the pickup motor 84 and the separation drive motor 85 are stopped, and the process ends. If it is not the last document (step S108: No), the process returns to step S103 to feed the next document. Next, steps S112 to S114 are performed because the skew detection sensors S1 and S2 are reversed in steps S104 to S106, and a description thereof will be omitted. In this way, even if there is a certain amount of skew, it is possible to detect the bound original with high accuracy by matching the load torque of the separation drive motor 85.

  As described above, according to the present embodiment, not only the skew amount of the original when the bound original is fed, but also the load torque of the motor is measured, so that a folded original or a stacked original is erroneously detected. Thus, the bound document can be detected with high accuracy without performing the operation.

10 Image reading device 21 Document tray 20 ADF
REFERENCE SIGNS LIST 22 Pickup roller 23 Separation drive roller 24 Separation driven roller 25 Transport roller pair 26 Lead roller pair 27 Platen guide roller 28 Platen glass 29 Jump table 40 Reading unit 41 Document table glass 46 CCD line sensor 47 Lamp 48, 49, 50 Mirror 81 CPU
83 Motor control unit 84 Pickup motor 85 Separation drive motor 86 Load torque measurement unit 506 Operation unit 507 Storage unit S1 Skew detection sensor S2 Skew detection sensor S21 Document presence sensor S22 Post-separation sensor

Claims (7)

A document tray on which documents are stacked;
A feeding roller for feeding the originals stacked on the original tray,
A separating unit that separates the originals fed by the feeding roller one by one;
An image reading unit that reads an image of a document conveyed through the separation unit,
A motor for driving the separation unit;
A load torque measuring unit that measures the load torque of the motor,
Skew detection means for detecting skew of the document using a plurality of skew detection sensors arranged downstream from the separation unit,
Control means for stopping the feeding of the document when the skew detection means detects a skew of the document exceeding a predetermined amount and the load torque of the motor measured by the load torque measurement unit exceeds a threshold value; When,
An image reading apparatus comprising: The separation unit has a separation drive roller and a separation driven roller,
2. The image reading apparatus according to claim 1, wherein documents are separated one by one in a nip formed by the separation driving roller and the separation driven roller.   The image reading apparatus according to claim 2, wherein the motor is a motor that drives the separation driving roller.   4. The image reading device according to claim 1, wherein the load torque measuring unit measures a load torque of the motor from a load current of the motor. 5.   The skew detecting means detects that the document is skewed when one of the plurality of skew detection sensors is turned on and the other sensor is not turned on for a predetermined time or more. The image reading device according to any one of claims 1 to 4, wherein   The image reading apparatus according to claim 1, wherein the plurality of skew detection sensors are arranged in a direction orthogonal to a document feeding direction. Provided downstream of the separation unit, has a transport roller pair for transporting the document toward the image reading unit,
The image reading apparatus according to claim 1, wherein the plurality of skew detection sensors are disposed between the separation unit and the pair of conveyance rollers.

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