JP2020117329A - Image reading device - Google Patents

Abstract

To provide an image reading device capable of preventing an occurrence of a paper feeding failure.SOLUTION: In the vicinity of separating and feeding means above a document tray, detection means is provided with its detection direction directed upstream of a document conveying direction. If an output of the detection means detects that there is a document before a start of document feeding, document feeding operation is not started.SELECTED DRAWING: Figure 11

Description

The present invention relates to an image reading device that reads an image on a document.

Generally, there is known an image reading device which is arranged on the upper part of the printer body and reads an image of a document. The image reading device conveys a document set on a document tray to a reading unit and reads the image of the document. After that, a sheet feeding device (ADF) for discharging the document to a discharge tray below the document placing table is provided. The ADF includes an original tray on which originals are set, a separate feeding unit that separates the originals set on the original tray one by one, and feeds the originals toward a reading position where image information of the originals is read. The paper tray is provided below the table, and includes a paper discharge table for discharging a document whose image information has been read at the reading position, and a support member for rotatably supporting the document table.

In the configuration disclosed in Patent Document 1, the manuscript tray is rotated so that the reference position at which the manuscript is set and the opening angle formed by the manuscript mounting table and the discharge table is larger than the reference position. In the automatic document feeder that rotates between the position and the position, the document tray is configured to be held at the turning position to improve the jam handling property of the document jammed in the document transport path.

JP, 2008-195511, A

Patent Document 1 discloses a configuration for improving the jam handling property of the document jammed in the document transport path, but does not explicitly disclose the configuration for preventing the document jam. For example, when reading images of a plurality of types of originals, the user of the sheet feeding apparatus may place an original document that is about to be read or an original document that has been read on the cover (Fig. 13a). ). At this time, if the original is dripping into the paper feed port and is in contact with the original on the paper feed tray, the dripping original will be drawn into the paper feed port when the original on the paper feed tray is fed. A defect (jam) may occur.

In order to solve the above problems, the image reading device according to the present invention is
Detects the relative distance between the document tray on which the documents are stacked, the separation and feeding unit that picks up and stacks the documents stacked on the document tray one by one, and the documents that are separated and fed on the document tray It has a detection means and a control means for controlling the drive of the separation feeding means, and determines whether or not the separation feeding means can start feeding the document based on the detection result of the detection means. It is characterized by doing.

According to the image reading apparatus of the present invention, it is possible to prevent the document placed on the open/close cover from being mistakenly fed, and thus to prevent the document from being damaged.

The conceptual diagram which concerns on 1st Embodiment. (A) An overall schematic view showing a printer, (b) A schematic view of an image forming engine. FIG. 3 is a side view of a main paper feeding unit according to the first embodiment. The conceptual diagram of a document surface detection sensor. (A) Schematic diagram when the distance between the document surface and the sensor is short, (b) Schematic diagram when the distance between the document surface and the sensor is long, (c) Relationship between the distance between the document surface and the sensor and the sensor output Graph. FIG. 6 is a schematic diagram illustrating that floating occurs in a bound document in which two positions on the trailing edge of the document are bound. The control block diagram which concerns on embodiment. 6 is a flowchart showing a copy operation when a bound document is fed according to the embodiment. 5 is a flowchart of S1 detection processing according to the embodiment. The figure which looked at paper feed from the width direction. (A) During normal document feeding, (b) During binding document feeding at two rear edge sides. The graph which shows the output of the sensor at the time of paper feeding. (A) During normal document feeding, (b) During binding document feeding at two rear end sides. 6 is a flowchart of S1 detection processing T according to the embodiment. The figure which looked at paper feed from the width direction. (A) When there is no original hanging in the paper feed port, (b) When there is original hanging in the paper feed port. 6 is a graph showing the output of the sensor when a paper feed start instruction is issued. (A) When there is no original hanging in the paper feed port, (b) When there is original hanging in the paper feed port. The figure which looked at the paper feeding of a prior art from the width direction. (A) A state in which a document is placed on the open/close cover and the document is drooping into the paper feed port, and (b) A diagram in which the document hanging from the paper feed port is drawn into the paper feed port and a paper feed failure occurs ..

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings.

First, the first embodiment will be described. The printer 100 as the image forming apparatus according to the first embodiment is an electrophotographic laser beam printer.

1A and 1B are diagrams according to the first embodiment. FIG. 1A is a conceptual diagram of the entire printer, and FIG. 1B is a schematic diagram of an image forming engine.

As shown in FIG. 1A, the printer 100 includes a printer body 70 and an image reading device 10 mounted on the printer body 70. In the following, the term sheet includes, in addition to plain paper, special paper such as coated paper, recording material having a special shape such as envelope and index paper, and plastic film or cloth for overhead projector, The manuscript is also an example of a sheet.

The printer body 70 has an image forming engine 60 inside. 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, which is a photoconductor, rotates, and the drum surface is uniformly charged by the charging device 2. Then, the exposure device 3 modulates and outputs laser light based on 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. This electrostatic latent image is visualized (developed) by the toner supplied from the developing device 4 and becomes a toner image.

In parallel with such an image forming operation, a feeding operation for feeding the sheets stacked in a cassette or a manual feed tray (not shown) 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 onto the 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 onto which the unfixed toner image is transferred is delivered to the fixing device 7, and is nipped by the roller pair and heated and pressed. The sheet on which the toner is melted and fixed on the sheet and the image is fixed is discharged by a discharge unit such as a pair of discharge rollers.

[Image reader]
Next, the image reading device 10 will be described in detail.

As shown in FIG. 1A, the image reading apparatus 10 includes an ADF 20 that feeds a document stacked on a document tray 21 and discharges the document to a discharge tray 32, and a reading unit 40 that reads a document conveyed by the ADF 20. Equipped with. An ADF 20 (Auto Document Feeder) as a sheet feeding device is rotatably supported by a hinge with respect to the reading unit 40 so that the document table glass 41 can be opened. The document D, which is an example of a sheet, may be a blank sheet, or an image may be formed on one side or both sides.

The ADF 20 includes a pickup roller 22 as a feeding unit, a separation driving roller 23 and a separation driven roller 24, a registration roller pair 25, conveyance roller pairs 26 and 30, and a discharge roller pair 31. .. Further, the ADF 20 includes a document presence/absence sensor S21 for detecting the document D on the document tray 21, a post-separation sensor S22 arranged downstream of the separation driving roller 23 in the sheet feeding direction for detecting the document D, and a document surface detection sensor. S1 and

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, and 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 left-right direction in the drawing, by a wire and a drive motor (not shown).

The image reading apparatus 10 has a flow-reading mode in which a document image stacked while being fed on the document tray 21 is fed by the ADF 20, and a fixed reading mode in which a document placed on the platen glass 41 is scanned. Thus, the image information is read from the document D. The flow-reading mode is selected when the document presence/absence sensor S21 detects the document D stacked on the document tray 21 or when the user explicitly instructs the operation panel of the printer body 70 or the like.

When the flow-reading mode is executed, the pickup roller 22 supported by an arm (not shown) descends and comes into contact with the uppermost document D on the document tray 21. Then, the document D is fed by the pickup roller 22 and separated one by one in the separation nip N formed by the separation drive roller 23 and the separation driven roller 24 as a separation unit. The separation drive roller 23 is formed of a rubber material or the like that has slightly less friction than the separation driven roller 24. A torque limiter is arranged in the drive transmission path to the separation driven roller 24. The separation driven roller 24 is rotated by the separation driving roller 23 when the number of fed originals is one, and the fed original is It does not rotate when there are two or more. Therefore, the originals can be separated one by one. The separation driven roller 24 may be input with a drive in the direction opposite to the sheet feeding direction.

The leading edge and the trailing edge of the document that has passed through the separation nip N are detected by the post-separation sensor S22, and the timing of raising and lowering the pickup roller 22, the drive start and drive stop timing, and the drive start and drive stop timing of the registration roller pair 25 are detected. It becomes a standard.

The leading edge of the conveyed document D strikes the registration roller pair 25 in the stopped state, and the skew of the document D is corrected. The original D whose skew has been corrected is conveyed by the registration roller pair 25, and is conveyed by the conveying roller pair 26 toward the platen glass 28. A platen guide roller 27 is arranged so as 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 from 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 document 47 being conveyed is irradiated with the light of the lamp 47, 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 brightness of the document D. The document D that has passed through the platen glass 28 is guided to the conveyance roller pair 30 by the jump table 29, and is ejected to the ejection tray 32 by the ejection roller pair 31.

On the other hand, the fixed reading mode is selected when the apparatus detects the document D placed on the platen glass 41 or when the user explicitly instructs the operation panel of the printer body 100 or the like. 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 document 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.

[Document surface detection sensor]
FIG. 2 shows a side view of the paper feeding unit in this embodiment. The document surface detection sensor S1 as a detection unit is provided on the frame 33 of the ADF 20, as shown in FIG. More specifically, the document surface detection sensor S1 is installed near the pickup roller 22 above the document tray 21 with its detection direction facing upstream in the document conveyance direction. Although only one document surface detection sensor S1 is arranged in the present embodiment, a plurality of document surface detection sensors S1 may be arranged.

Here, the document surface detection sensor S1 will be described. FIG. 3 shows a conceptual diagram of the document surface detection sensor S1. 3A is a schematic diagram when the document surface and the sensor are close, FIG. 3B is a schematic diagram when the document surface and the sensor are far, and FIG. 3C is the document surface and the sensor. Is the relationship between the distance and the sensor output.

As shown in FIGS. 3A and 3B, a light emitting unit S11 that emits light toward the rear end of the uppermost document D stacked on the document tray 21 and a reflected light from the document D are received. And a light receiving portion S12.

As shown in FIG. 3A, when the distance H1 between the document surface DS of the document D and the document surface detection sensor S1 is relatively small, the light receiving section S12 produces a large amount of the light flux reflected by the document surface DS. Since it can be captured, the amount of light received by the light receiving unit S12 is large. As shown in FIG. 3B, when the distance H2 (H2>H1) between the document surface DS of the document D and the document surface detection sensor S1 is relatively large, the light receiving section S12 is the document surface DS. A large amount of the reflected light flux cannot be captured, and the amount of light received by the light receiving section S12 becomes small. Then, the output of the document surface detection sensor S1 is determined according to the amount of light received by the light receiving section S12. That is, the document surface detection sensor S1 transmits a signal based on the magnitude of the amount of light received by the light receiving section S12 to the CPU 81 (see FIG. 5) to detect the distance between the document surface DS and the document surface detection sensor S1. The relationship with the sensor output is as shown in the graph of FIG.

The CPU 81 can detect the distance between the document surface DS and the document surface detection sensor S1 at the detection position according to the signal according to the sensor output transmitted from the document surface detection sensor S1.

Here, the principle that the original floats when a so-called "binding original" such as a stapled original or a pasted original is fed will be described. The "binding document" in the present embodiment is not limited to a stapled or glued document, and may be a stapleless bound document or a bound document. Further, the original is not limited to a bundle of originals having a plurality of pages, and a single original may be folded so as to overlap in the height direction.

FIG. 4 is an explanatory diagram for explaining that the binding document is lifted. In FIG. 4, a document D is fed as a sheet bundle in which the rear edges of the first sheet D1 as the first sheet and the second sheet D2 as the second sheet are connected by staples ST1 and ST2. It is a schematic diagram in a case.

When the document D is fed by the pickup roller 22, the document D strikes the separation nip N.

The pickup roller 22 is in contact with the upper surface of the first sheet D1 of the document D, and applies the feeding force to the first sheet D1 even when the document D strikes the separation nip N. However, the second sheet D2 is stopped at the separation nip N by the separation driven roller 24. Since the document D is connected by the staples ST1 and ST2, as the pickup roller 22 feeds the first sheet D1, the first sheet D1 pulls the second sheet D2 and rises from the staples ST1 and ST2. ..

As described above, when the bound original is fed by the pickup roller 22, the original D has a characteristic floating or bending.

[Control block]
FIG. 5 is a control block diagram of the CPU 81 as the control means.

As shown in FIG. 5, a document surface detection sensor S1, a document presence sensor S21, and a post-separation sensor S22 are connected to the input side of the CPU 81. A pickup motor 84 and a separation drive motor 85 are connected to the 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.

An operation unit 506 and a memory 82 are connected to the CPU 81. The operation unit 506 has an operation panel, for example, and can start a copy job and perform various settings. The memory 82 serving as a storage unit stores thresholds TH1 and TH2 of the output OP2 of the document surface detection sensor S1 for determining that the document is a bound document.

[Document feeding operation]
Next, a copy operation when a document is fed will be described with reference to a flowchart.

FIG. 6 is a flowchart showing a copy operation when the document according to the embodiment is fed.

First, as shown in FIG. 6, the CPU 81 determines whether or not a document is stacked on the document tray 21 by the document presence/absence sensor S21 (step S101). When no document is stacked on the document tray 21 (step S101: No), the CPU 81 does not proceed to the next process and waits until a document is stacked on the document tray 21.

When it is determined that the originals are stacked 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). When the start of the copy job is not 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 is instructed (step S102: Yes), the CPU 81 performs the S1 detection process T (step S103) of the document surface detection sensor S1 to detect the document hanging in the paper feed port. It is determined (step S104). When the document hung in the paper feed port is detected (step S104: Yes), the CPU 81 does not proceed to the next process and waits until the document hung in the paper feed port is removed. At this time, the user may be warned that there is a document hanging in the paper feed port by the operation panel.

When the original drooping to the paper feed port is not detected (step 104: No), the CPU 81 feeds the original D by the pickup roller 22 (step S105). Then, the CPU 81 performs S1 detection processing (step S106) of the document surface detection sensor S1 and determines whether or not a bound document is detected (step S107).

When the bound document is not detected, that is, when the normal document is fed (step S107: No), it is determined whether the document currently fed has passed the sensor after separation (step S108). When the sensor has not passed through after separation (step S108: No), steps S106-S108 are repeated. If the post-separation sensor has been passed in step S108 (step S108: Yes), it is determined whether the fed document D is the final document of the copy job (step S109).

When the document presence/absence sensor S21 detects that documents are stacked on the document tray 21 (step S109: No), steps S105 to S109 are repeated.

When the document presence/absence sensor S21 detects that no document is stacked on the document tray 21 (step S109: Yes), the CPU 81 determines that the document is the final document. Then, the CPU 81 stops the pickup motor 84 and the separation drive motor 85 in step S110, and the feeding of the document ends.

When the bound document is fed (step S107: Yes), the process proceeds to step S110. Then, the CPU 81 stops the pickup motor 84 and the separation drive motor 85 in step S110, and the feeding of the document ends.

[S1 detection process]
The S1 detection process (step S106) in the flowchart shown in FIG. 6 will be described with reference to the flowchart.

FIG. 7 shows a flowchart of the S1 detection process according to the embodiment. Further, for detailed description, a view of the document feeding portion viewed from the width direction (FIG. 8) and a graph showing the output of the sensor during sheet feeding (FIG. 9) are used. 8A shows a normal document feeding, and FIG. 8B shows a trailing edge bound document feeding. 9A shows a normal document feeding, and FIG. 9B shows a trailing edge bound document feeding.

First, the CPU 81 reads the output OP2 of the document surface detection sensor S1 during document feeding (sheet feeding) (step S201), and the output OP2 is a threshold TH1 as a predetermined height stored in the memory 82 in advance. It is determined whether or not (step S202).

As shown in FIG. 8A, when a normal document that is not a bound document is fed, the characteristic floating of the document does not occur unlike the case of a bound document. When a normal document is fed, as shown in FIG. 9A, the output OP2 of the document surface detection sensor S1 during document feeding is maintained in a low state. Therefore, when a normal document is fed, the output OP2 does not exceed the threshold TH1 (step S202: No), the CPU 81 determines that a document that is not a bound document is fed, and executes the S1 detection process. finish.

Next, as shown in FIG. 8B, when a bound original is fed, the first original D1, which is the uppermost original of the original D, floats as the original D is fed. Then, the height position of the first sheet D1 rises. Therefore, as shown in FIG. 9B, the output OP2 of the document surface detection sensor S1 increases as the bound document is fed. Then, in step S202, the CPU 81 determines whether or not the output OP2 of the document surface detection sensor S1 during document feeding exceeds the threshold value TH1 of the document surface detection S1 sensor. When the output OP2 of the document surface detection sensor S1 exceeds the threshold value TH1 (step S202: Yes), the CPU 81 determines in step S203 that the bound document is being fed, and ends the S1 detection process. ..

[S1 detection process T]
The S1 detection process T (step S103) in the flowchart shown in FIG. 6 will be described with reference to the flowchart. FIG. 10 shows a flowchart of the S1 detection process T according to the embodiment. Further, for detailed description, a view of the document feeding unit viewed from the width direction (FIG. 11) and a graph showing the output of the sensor at the time of feeding (FIG. 12) are used. FIG. 11 is a schematic diagram showing a state in which a document is placed on the open/close cover and is hanging down from the paper feed port. FIG. 12A shows an output graph of the sensor S1 in the state where there is nothing hanging at the sheet feeding port, and FIG. 12B shows a state where the document is placed on the opening/closing cover and hanging at the sheet feeding port. 3 is an output graph of the sensor S1 of FIG.

When it is determined that the start of the copy job is instructed (step S102: Yes), the CPU 81 reads the output OP2 of the document surface detection sensor S1 (step S301), and the output OP2 is stored in the memory 82 in advance. It is determined whether the threshold value TH2 is exceeded (step S302).

If there is no original hanging in the paper feed port, as shown in FIG. 12A, the output OP2 of the original surface detection sensor S1 remains low at the timing of the paper feed start instruction. There is. Therefore, when there is no original hanging in the paper feed port, the output OP2 does not exceed the threshold value TH2 (step S302: No), the CPU 81 determines that there is no original hanging in the paper feed port, and the S1 detection process is performed. End T.

Next, when there is a document hanging in the paper feed port, as shown in FIG. 12B, the output OP2 of the document paper surface detection sensor S1 becomes high at the timing of the paper feed start instruction. ing. Therefore, when there is a document hanging in the paper feed port, the output OP2 exceeds the threshold value TH2 (step S302: Yes), the CPU 81 determines that there is a document hanging in the paper feed port, and the S1 detection processing T To finish.

Here, since the distance and the direction to the document surface detection sensor S1 and the document surface DS are different at the time of detecting the binding document and at the time of detecting the document hanging in the sheet feeding port, the output and the sheet feeding at the time of feeding the binding document are performed. In most cases, the output is different when there is a document hanging in the mouth. Therefore, the thresholds TH1 and TH2 of the document surface detection sensor S1 do not have to be the same.

Moreover, the material that may cause a paper feed failure (jam) due to the paper being dripped into the paper feed port is not limited to plain paper, but may be a plastic film, cloth, or other low-rigidity material for an overhead projector. Rigidity here means the force to return to its original shape when it is bent, and the material with a weak force to return to its original shape has low stiffness.

20 sheet feeding device (ADF), 21a stacking surface, 22 feeding means (pickup roller),
81 control means (CPU), 82 storage means (memory),
93,94 lifting mechanism (lifting motor, lifting arm), 96 moving part (lever),
99 encoder (rotary volume),
D1 first sheet (first sheet), D2 second sheet (second sheet),
N separation means (separation nip), PU image forming means (image forming unit),
S1 detection means (original surface detection sensor), S11 light emitting section, S12 light receiving section,
S22 Separation sensor, S23 Original length detection sensor,
TH1・TH2 Threshold of document surface detection sensor

Claims (5)

A document tray having a document stacking surface for stacking documents,
A feeding roller that feeds the original in contact with the uppermost surface of the original on the original surface,
A detection means for detecting the orientation of the fed original,
Control means for stopping the feeding of the original when an abnormal posture change of the original is detected by the signal from the detecting means,
The image reading apparatus, wherein the control means does not start the feeding operation when the signal of the detection means exceeds a predetermined value before the start of the document feeding operation. 2. The image reading apparatus according to claim 1, wherein the detection unit is disposed above the document tray, in the vicinity of the feeding roller, with the detection direction facing upstream in the transport direction of the document. The image reading apparatus according to claim 1 or 2, wherein the detection unit detects a posture of the trailing edge of the document. The information for prompting the user to check the state of the original document is displayed on the operation unit when the signal of the detection unit exceeds a predetermined value and the feeding operation is not started. The image reading device according to any one of claims 1 to 3. The control means has at least one predetermined threshold value for making a determination with respect to the detection result of the detection means, and depending on whether or not the detection result of the detection means exceeds the threshold value, the feeding roller feeds the document. The image reading apparatus according to claim 1, wherein the image reading apparatus is started.