JP2022019338A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus equipped with an image reading device that is capable of stopping a feeding operation quickly when a stapled document is fed.SOLUTION: An image reading device 80 installed in the upper part of a printer 100 includes a tracking sensor 111 for detecting the speed of a document. On the basis of the speed of the document detected using the tracking sensor 111, whether to stop the feeding operation of the document is controlled.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus that forms an image on a sheet.

Conventionally, an image reading device provided in an image forming apparatus such as a copier is a reader in which an automatic document transporting device (Auto Document Feeder, hereinafter referred to as ADF) that transports documents one by one reads an image of a document. The one provided at the top is known. This type of ADF separates the top-level original from a plurality of originals placed on the original tray, and conveys the separated originals to the reading position of the reader along a U-shaped curved transport path. The structure is such that the document from which the image has been read is ejected to the output tray provided at the bottom of the original tray. This is because the area of the upper surface of the copying machine is limited, and the ADF is made compact by curving the document transport path into a U shape.

Further, since the transfer speed of the original is not stable in the separation portion, reading the original immediately after the separation portion may lead to reading failure. Therefore, it is desirable that the separation portion and the reading position are sufficiently separated from each other. It has a structure to convey to the reading position in. This enables the image reader to read the image of the original while transporting the original at a stable speed.

As described above, the image reading device provided on the copying machine is required to be compact and have high reading accuracy.

In such an image reading device, a bundle of originals in which a plurality of originals are bound by staples (hereinafter referred to as staple originals) may be mistakenly placed on the original tray by the user. When a stapled original is fed, the binding portion becomes the center of rotation of the original at the separation portion and the original is skewed, and if the feeding operation is continued as it is, the original may be damaged. Therefore, when the staple document is fed, it is desirable to stop the document feeding operation as soon as possible in order to prevent the document from being damaged.

Therefore, Patent Document 1 discloses a configuration in which it is determined whether or not the manuscript being fed is a staple manuscript by detecting the skew of the manuscript. In the configuration described in Patent Document 1, a plurality of optical sensors are arranged at intervals in the width direction perpendicular to the transport direction, and the document is skewed due to the difference in the detection timing of the tip of the document by the plurality of optical sensors. Is detected. Then, when the difference in the detection timing of the tip of the document by the optical sensor is larger than the predetermined time and the skew of the document is detected, the feeding operation of the document is stopped.

Japanese Unexamined Patent Publication No. 2009-51585

By the way, when a user sets a document in a document tray, the document may be set in a state of being tilted with respect to the transport direction, and the document may be transported in a tilted state. In the configuration of Patent Document 1, even when a document not bound by such staples is conveyed while being tilted with respect to the conveying direction, it is erroneously detected that the document being fed is a staple document. Therefore, the document feeding operation is stopped.

Further, when reducing such false detection by using the configuration of Patent Document 1, by increasing the predetermined time of the detection timing difference when determining the staple document, the transport is continued until the staple document is greatly skewed. After that, it is necessary to judge it as a staple manuscript. In this case, jam detection is delayed, so there is a high possibility that the original will be damaged. Therefore, there is room for improvement in the configuration for controlling whether or not to stop the document feeding operation.

Therefore, an object of the present invention is to provide an image forming apparatus provided with an image reading device capable of quickly stopping the feeding operation when the staple document is fed.

One aspect of the present invention includes an image forming unit having an image forming means for forming an image on a sheet, a reading unit provided above the image forming unit and reading an image of a document at a reading position, and an upper portion of the reading unit. It is an image forming apparatus provided in the image forming apparatus including a document transporting unit for transporting a document to the reading position, and the document transporting unit is mounted on a document tray on which a document is placed and a document tray. The feeding means for feeding the original, the separating means for separating the highest-level original from the original fed by the feeding means into one sheet, and the separating means for separating the original by the separating means are curved in a U shape. It has a transport means for transporting to the reading position via a curved portion of the transport path, and a paper ejection tray provided at the bottom of the document tray and ejecting an image from which an image has been read by the scanning section. , A detection means for detecting the speed of the document conveyed by the document transfer unit, and a control means for controlling whether or not to stop the feeding operation of the document based on the speed of the document detected by the detection means. , Is an image forming apparatus.

According to the present invention, it is possible to provide an image forming apparatus including an image reading device capable of quickly stopping the feeding operation when a stapled original is fed.

FIG. 6 is a schematic cross-sectional view showing a printer provided with an ADF according to the present embodiment. The schematic diagram which shows the image engine of a printer. Schematic cross-sectional view showing an image reader in a state where the opening / closing cover of the ADF is opened. The block diagram which shows the control part of the image reading apparatus which concerns on this embodiment. (A) is a diagram showing the positional relationship between the document and the tracking sensor immediately after separation. (B) is a diagram showing the positional relationship between the document and the tracking sensor after a certain period of time has passed after passing through the separation portion. (A) is a top view showing the position of the original immediately after separation. (B) is a top view showing the position of the original document after a certain period of time has passed after passing through the separation portion. (A) is a diagram showing image data of a document immediately after separation captured by a tracking sensor. (B) is a diagram showing image data of a document to be captured next to the image data of FIG. 7 (a) by the tracking sensor. The figure which shows the transition of the tracking sensor output value. The figure which shows the staple manuscript. (A) is a diagram showing the positional relationship between the staple document and the tracking sensor immediately after passing through the separation portion. (B) is a diagram showing the positional relationship between the staple document and the tracking sensor after a certain period of time has passed after passing through the separation portion. Top view showing the position of the staple document after passing through the separation part. The figure which shows the image data of the staple document after passing through the separation part which the tracking sensor takes an image. The figure which shows the transition of the tracking sensor output value at the time of feeding a staple document. (A) is a top view showing the position of the staple document immediately after separation. (B) is a top view showing the position of the staple document after a certain period of time has passed after passing through the separation portion. The flowchart which shows the process of the staple document detection which concerns on this embodiment. (A) is a top view showing the position of a document tilted with respect to the transport direction immediately after separation. (B) is a top view showing the position of the original tilted with respect to the transport direction after a certain period of time has passed after passing through the separation portion.

Hereinafter, an image reading device according to the present embodiment and an image forming device including the image reading device will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments are intended to limit the scope of application of this technology to those, unless otherwise specified. is not it.

<Approximate configuration of printer 100>
First, a schematic configuration of the printer 100 as an image forming apparatus according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view of the printer 100, and FIG. 2 is a schematic diagram showing an image engine of the printer 100. The printer 100 is an electrophotographic laser beam printer. As shown in FIG. 1, the printer 100 includes a printer main body 70 and an image reading device 80. The printer main body 70, which is an image forming unit, includes an image forming engine 60 and a control unit 400 that controls the printer 100. As shown in FIG. 2, the image forming engine 60 as an image forming means includes an electrophotographic image forming unit PU and a fixing device 7. When the start of the image forming operation is commanded, the photosensitive drum 1 which is a photoconductor is rotated, and the drum surface is uniformly charged by the charging device 2. Then, the exposure apparatus 3 modulates and outputs the laser beam based on the image data transmitted from the image reader 80 or an external computer, scans the surface of the photosensitive drum 1, and forms an electrostatic latent image. This electrostatic latent image is 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 a sheet loaded on a cassette (not shown) or a manual feed tray (not shown) to 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 supported on the photosensitive drum 1 is transferred to the sheet by the transfer roller 5. The toner remaining on the photosensitive drum 1 after the toner image transfer is recovered by the cleaning device 6. The sheet on which the unfixed toner image is transferred is transferred to the fixing device 7, sandwiched between roller pairs, and heated and pressurized. The sheet in which the toner is melted and fixed to the sheet and the image is fixed is discharged by a discharge means equivalent to a paper discharge roller.

<Structure of image reader 80>
Next, the schematic configuration of the image reader 80 will be described with reference to FIGS. 1 and 3. As shown in FIG. 1, the image reading device 80 installed on the upper part of the printer main body 70 includes a reader 40 as a reading unit and an ADF 20 as a document transporting unit, and optically scans the document 104 to form an image. Read the information. The ADF 20 is fixed so as to be rotatable with respect to the reader 40 by a hinge portion (not shown).

The ADF 20 has a document tray 105 as a document placing section on which the document 104 is placed, and continuously feeds the document 104 placed on the document tray 105 by a pickup roller 107 as a feeding means. At this time, the pickup roller 107 comes into contact with the document 104 from above. Further, the ADF 20 has a paper ejection tray 124 at the lower part of the original tray 105 from which the original document 104 after reading the image is discharged.

The document tray 105 is provided with a document set detection sensor 106 for detecting the presence or absence of a document on the document placing surface of the document tray 105. The ADF 20 has a separation roller 109 and a retard roller 110 as separation means for separating the uppermost original 104 into one sheet from the original bundle set in the original tray 105. Further, the ADF 20 includes a first transport roller 112, a second transport roller 113, a first resist roller 114, a third transport roller 115, and a second resist roller in order from upstream to downstream in the transport direction as transport means. 116, 4th transfer roller 117, 5th transfer roller 118, 6th transfer roller 119, 7th transfer roller 120, 8th transfer roller 121, original paper ejection roller 122, and 9th transfer roller 123. And have.

The ADF 20 has a pre-separation sensor 108 used to detect that the document 104 has reached the separation unit, and a tracking sensor 111 which is an image pickup unit used to detect the amount of movement of the document per predetermined time. .. The tracking sensor 111 receives the reflected light obtained by irradiating the surface of the document 104 with the laser beam to the image pickup device at a predetermined sampling cycle to image the document 104. In the present embodiment, the interval of the predetermined sampling cycle is 1 ms, and the tracking sensor 111 continuously images the document 104 every 1 ms. Then, the tracking sensor 111 outputs the movement amount of the document 104 per predetermined time (sampling cycle interval) based on the movement amount of the feature points included in the image data obtained by imaging the document 104 being conveyed. do. The CPU 202 as a detection unit, which will be described later, can detect the amount of movement of the document 104 per predetermined time from the output of the tracking sensor 111.

Here, in the present embodiment, "velocity" is the amount of movement of the object with respect to time, and "the amount of movement per predetermined time" is "velocity".

In this embodiment, the tracking sensor 111 is a detection means for detecting the amount of movement of the document 104 per predetermined time. However, the detection means is not limited to the configuration of the present embodiment, and for example, even if the tracking sensor 111 outputs only the captured image data and the CPU 202 detects the movement amount of the document per predetermined time based on the image data. good.

The exterior of the ADF 20 is a separate body from the housing portion 103 provided with the transfer motor 203 (see FIG. 4 described later) for driving the various rollers described above, and can be opened and closed with respect to the housing portion 103. It is composed of an opening / closing cover 102 (opening / closing portion). FIG. 1 shows a state in which the open / close cover 102 is closed, and FIG. 3 shows a state in which the open / close cover 102 is open.

As shown in FIGS. 1 and 3, the opening / closing cover 102 forms a part of the transport path 200 in the closed state, and exposes a part of the transport path 200 in the open state. Further, among the various rollers and sensors of the ADF 20 described above, the pickup roller 107, the separation roller 109, the first transport roller 112, the first resist roller 114, and the tracking sensor 111 are attached to the opening / closing cover 102. Have been placed. When the open / close cover 102 is opened, the transparent portion 309 of the tracking sensor 111, which will be described later, is exposed to the outside of the device. By opening the open / close cover 102, the user can remove the jammed document or clean the tracking sensor 111.

In the present embodiment, the opening / closing cover 102, which is an opening / closing portion, has a frame portion 102a forming a part of the exterior of the ADF 20 and a transport guide forming a part of the transport path 200 when the opening / closing cover 102 is closed. A part 102b and the like.

On the other hand, the reader 40 has a reading unit 50, a scanning glass 133, and a platen glass 134. The reading unit 50, which is a reading means, includes light sources 125 and 126, a first mirror 127, a second mirror 128, a third mirror 129, an imaging lens 130, a line sensor 131, and a signal processing substrate 132. It is prepared. In the line sensor 131, image pickup elements such as a CCD are arranged in the main scanning direction. Further, the reading unit 50 is configured to be movable in the sub-scanning direction (left-right direction in FIG. 1) by an optical system motor (not shown). Here, the sub-scanning direction is a direction perpendicular to the main scanning direction in which the image pickup elements of the line sensor 131 are arranged.

Subsequently, the document reading operation will be described with reference to FIG. The image reading device 80 has a scanning mode in which the original placed on the original tray 105 is conveyed to the reading position P by the ADF 20 to scan the original image, and the original placed on the original base glass 134, which is the original base. The image information of the original is read by the fixed reading mode for scanning.

First, the scanning mode will be described. In the scanning mode, the ADF 20 conveys the document to the scanning position P of the reader 40. Further, the original is scanned in a state where the scanning unit 50 is fixed below the scanning glass 133 (position shown in FIG. 1). The document 104 placed on the document tray 105 is fed by the pickup roller 107 to the separation section composed of the separation roller 109 and the retard roller 110. In the separation section, the separation roller 109 and the retard roller 110 are arranged at opposite positions so as to nip the documents, and separate the top-level documents in the document bundle one by one. In this way, the pickup roller 107 feeds the document placed on the document tray 105 to the separation unit, and the separation roller 109 and the retard roller 110 separate the top-level document into one sheet. Operation. "

The document 104 separated into one sheet at the separation unit is imaged by the tracking sensor 111 in order to detect the movement amount. After that, the document 104 is conveyed by the first transfer roller 112 and the second transfer roller 113, and the inclination (oblique) with respect to the transfer direction is corrected by the first resist roller 114 and the third transfer roller 115. The first resist roller 114 and the third transfer roller 115 receive the downstream end (tip) of the document 104 to be transported in the transport direction in a state where the rotation is stopped, and bend the document 104 to correct the skew. Then, the document 104 is sequentially conveyed to the second resist roller 116, the fourth transfer roller 117, and the fifth transfer roller 118 along the curved portion 200a of the transfer path 200 curved in a U shape. Here, the curved portion 200a is a path in which the upper surface and the lower surface of the document 104 are exchanged by passing the document 104, and in the present embodiment, the curved portion 200a is a path from the first resist roller 114 to the fifth transport roller of the transport path 200. It is a route to 118.

The document 104 transported by the fifth transport roller 118 is irradiated with light by the light sources 125 and 126 of the reading unit 50, and the reflected light is connected via the first mirror 127, the second mirror 128, and the third mirror 129. It is guided to the image lens 130. The light guided by these mirrors is converged by the imaging lens 130, and an image pickup element such as a CCD is imaged on the line sensor 131 arranged in the main scanning direction. The imaged optical signal is converted into an electric signal by the line sensor 131, and is converted into a digital signal by the signal processing substrate 132. As a result, the image reading device 80 reads the image data of the document 104. At this time, since the document 104 placed on the document tray 105 is read by the reader 40 after passing through the curved portion 200a described above, the image on the upper surface of the document 104 placed on the document tray 105 is read. Be done.

After that, the original 104 whose image has been read is conveyed from the 6th transfer roller 119 to the 7th transfer roller 120 and the 8th transfer roller 121, and is transferred to the paper output tray 124 by the original paper discharge roller 122 and the 9th transfer roller 123. The paper is ejected.

Next, the fixed reading mode will be described. The user opens the ADF 20 with respect to the reader 40 to expose the platen glass 134, and places the document 104 on the platen glass 134. After the user places the document 104 on the table glass 134, the document 104 is fixed on the table glass 134 by closing the ADF 20 with respect to the reader 40. Then, the reading unit 50 is moved in the sub-scanning direction along the platen glass 134 by an optical system motor (not shown) to scan the document 104 on the platen glass 134.

In the present embodiment, the pickup roller 107 is an example of the feeding means, and the document 104 may be fed by using the feeding belt. Further, the ADF 20 separates the originals by the separation roller 109 and the retard roller 110, but the separation means is not limited to this, and for example, even if the ADF 20 is configured to separate the originals by using a separation pad instead of the retard roller 110. good. Further, each of the above-mentioned transport rollers is an example of a transport means, and a transport belt may be used instead of the transport rollers to transport the original.

Further, in the present embodiment, the ADF 20 has a U-shaped curved transport path 200 as shown in FIG. 1 as a transport path for documents from the document tray 105 to the output tray 124. As described above, the ADF 20 separates the top-level original 104 from the original bundle placed on the original tray 105. In this configuration, by transporting the originals through the transport path 200 curved in a U shape, the order of the original bundles in the original tray 105 and the order of the original bundles in the output tray 124 match. Here, the “U-shaped curved transport path” is not limited to the gently curved transport path 200 shown in FIG. 1, and may be any transport path that folds back from top to bottom.

In this embodiment, the configuration in which only the reader 40 has the reading unit 50 is illustrated. However, the ADF 20 may be provided with an inversion path for inverting the document 104 or a reading unit 50 similar to the scanner unit 40 to read images on both sides of the conveyed document 104. Further, in the present embodiment, the reading unit 50 is illustrated as an example of the reading means, but the image of the original is read by fixing the line sensor 131 to the reader 40 and moving the light source and the mirror in the sub-scanning direction. It may be configured.

Subsequently, the configuration of the control unit of the image reading device 80 will be described with reference to FIG. FIG. 4 is a block diagram showing a control unit of the image reading device 80. The operation unit 201 is a display means for displaying information on the printer 100, and is a touch panel for a user to give an instruction to the printer 100. The CPU 202 detects that the user places the document 104 on the document tray 105 and presses the copy button of the operation unit 201. When the CPU 202 detects that the document 104 is placed on the document tray 105 by the document set detection sensor 106, the CPU 202 drives the transport motor 203 arranged in the housing 103 to start feeding the document 104. When the document 104 reaches the pre-separation sensor 108, the tracking sensor 111 continuously starts acquiring image data of the document at a predetermined sampling cycle in order to detect the amount of movement of the document 104 per predetermined time.

Since the document is conveyed at a constant transfer speed, it is possible to predict the time from when the document 104 reaches the pre-separation sensor 108 until the tip of the document 104 passes through the tracking sensor 111. Therefore, the output value of the tracking sensor 111 after a certain predetermined time has elapsed from the on of the pre-separation sensor 108 is enabled, and the acquisition of the image data of the original by the tracking sensor 111 is stopped after another predetermined time has elapsed. It is controlled by the CPU 202.

Further, the CPU 202 determines the jam caused by the staple document based on the amount of movement of the document 104 detected by the tracking sensor 111 per predetermined time. The jam determination process performed by the CPU 202 will be described later.

The CPU 202 shown in the present embodiment is an example of the determination means, and the control unit 400 of the printer main body 70 may be configured to perform jam determination in the ADF 20.

<Speed detection of originals during normal original transfer>
Next, the relationship between the document transport control and the output signal of the tracking sensor 111 when the non-stapled document is fed will be described with reference to FIGS. 5 to 8. FIG. 5A is a diagram showing the positional relationship between the document 104 and the tracking sensor 111 at time t1 immediately after the document 104 passes through the separation portion. FIG. 5B is a diagram showing the positional relationship between the document 104 and the tracking sensor 111 at time t2 (t1 <t2) when the document 104 reaches the first transfer roller 112 and the second transfer roller 113. FIG. 6A is a top view showing the position of the document 104 at time t1 shown in FIG. 5A. FIG. 6B is a top view showing the position of the document 104 at time t2 shown in FIG. 5B. The document 104 is transported in the transport direction from right to left in FIGS. 5 and 6.

In FIG. 5A, the arrow 306 indicates the rotation direction of the separation roller 109, and the arrow 307 indicates the rotation direction of the retard roller 110. In order to separate the original 104, which is the highest document in the original bundle, from the second original 308, the separation roller 109 rotates so as to feed the original 104 in the transport direction, and the retard roller 110 rotates the original 308 upstream in the transport direction. Rotate in the direction of pushing back. The retard roller 110 is input with a rotational driving force from the conveyor motor 203 via a torque limiter (not shown). As a result, the separation roller 109 and the retard roller 110 separate the uppermost original 104 from the original bundle into one sheet.

The tracking sensor 111 includes a laser issuing unit 301, a collimator lens 302, an imaging lens 303, a light receiving sensor 304, and a transparent unit 309. The coherent light 305 emitted from the laser light emitting unit 301, which is the irradiation unit, passes through the transparent unit 309 via the collimator lens 302 and is irradiated to the document 104. The irradiated coherent light 305 is reflected by the document 104, passes through the transparent portion 309 again, and enters the light receiving sensor 304, which is a sensor portion, via the imaging lens 303. The light receiving sensor 304 has pixels arranged in two dimensions, and the coherent light 305 input to the light receiving sensor 304 is photoelectrically converted into an electric signal according to the amount of incident light of each pixel. As a result, the tracking sensor 111 acquires image data of the speckle pattern when the document 104 is irradiated with the coherent light 305.

At time t1, the document 104 separated from the document bundle by the separation roller 109 and the retard roller 110 is conveyed toward the first transfer roller 112 and the second transfer roller 113, as shown in FIG. 5A. .. Then, at time t2, the document 104 reaches the first transport roller 112 and the second transport roller 113, as shown in FIG. 5 (b). At this time, as shown in FIG. 6, the second document 308 remains in the document tray 105 by the retard roller 110.

FIG. 7A is a diagram showing an example of image data of a speckle pattern acquired by the tracking sensor 111 at time t1. FIG. 7B is a diagram showing an example of image data of a speckle pattern acquired by the tracking sensor 111 next to the image data shown in FIG. 7A. That is, the image data shown in FIGS. 7 (a) and 7 (b) are image data continuously acquired by the tracking sensor 111 at intervals of predetermined sampling cycles (1 ms in the present embodiment). In the present embodiment, as an example, the tracking sensor 111, which is an imaging unit, can acquire image data of 8 pixels × 8 pixels, but it is possible to acquire image data of a larger number of pixels. An image pickup unit may be used. Further, the image data shown in the present embodiment is obtained by binarizing the light receiving amount of the light receiving sensor 304 in which the pixels are two-dimensionally arranged, and the black-painted pixels are pixels whose light receiving amount is less than the binarization threshold, white. The filled pixels indicate pixels whose light receiving amount is larger than the binarization threshold.

Comparing FIGS. 7 (a) and 7 (b), the image data acquired by the tracking sensor 111 is shifted to the left by 5 pixels. That is, the document 104 moves in the transport direction by 5 pixels in the tracking sensor 111 between the time when the tracking sensor 111 acquires the image data and the time when the tracking sensor 111 acquires the next image data.

In this way, the tracking sensor 111 acquires image data of the speckle pattern at predetermined time intervals. Then, by comparing the acquired image data by pattern matching or the like, it is possible to detect the amount of movement of the document 104 in the transport direction per predetermined time.

In the present embodiment, for the sake of simplification of the description, the image data assuming that the document 104 moves parallel to the transport direction is shown as an example, but in reality, not only the transport direction but also the transport direction is shown. It is also assumed that the direction is orthogonal to the direction. In this case, the tracking sensor 111 previously matches an image pattern or the like when it rotates with respect to the image data of FIG. 7A or simultaneously moves in the transport direction and the direction orthogonal to the transport direction. Prepare as data for use and compare with each image data. Thereby, the tracking sensor 111 can detect how the document 104 is conveyed.

In the present embodiment, the tracking sensor 111 outputs the number of moving pixels (5 pixels in the example shown in FIG. 7) of the document 104 in the transport direction per predetermined time (for each sampling cycle) as output data. FIG. 8 is a graph showing a part of the transition of the output value of the tracking sensor 111 between the time t1 and the time t2. In FIG. 8, the horizontal axis indicates time, and the tracking sensor 111 outputs the detected movement amount of the document 104 every 1 ms. Further, in FIG. 8, the vertical axis shows the output of the tracking sensor 111 for each sampling cycle.

If the document 104 is conveyed at a constant speed, the amount of movement of the document 104 per predetermined time is always constant. Therefore, when the document 104 moves in the transport direction by an amount corresponding to 5 pixels in the sampling cycle of the tracking sensor 111, the tracking sensor 111 outputs the movement amount of 5 pixels in each sampling cycle as shown in FIG.

<Speed detection of originals when transporting staples>
Next, the relationship between the document transport control when the staple document is fed and the output signal of the tracking sensor 111 will be described with reference to FIGS. 9 to 13.

FIG. 9 is a diagram showing a staple manuscript 700 (manuscript 104, 308) bound with staples 701 and 702 at the upper two places. In the following, as an example of the staple manuscript, the case where the staple manuscript 700 shown in FIG. 9 is fed will be illustrated.

FIG. 10A is a diagram showing the positional relationship between the staple document 700 and the tracking sensor 111 at time t3 after the staple document 700 has passed the separation roller 109 and the retard roller 110. FIG. 10B is a diagram showing the positional relationship between the staple document 700 and the tracking sensor 111 at time t4 (t3 <t4) after a certain time has elapsed from the state of FIG. 10A. FIG. 11 is a top view showing the position of the staple document 700 at time t3 shown in FIG. 10 (a).

As shown in FIG. 10A, since the staple manuscript 700 is bound by the staples 701 and 702, the uppermost manuscript 104 cannot be separated by the separation roller 109 and the retard roller 110. Therefore, at time t3, the document 104 is attracted to the document 308 pushed back upstream in the transport direction by the retard roller 110 and cannot move in the transport direction.

After that, when the separation roller 109 and the retard roller 110 are further rotated, the document 104 floats so as to form a loop at a position immediately after the separation roller 109, as shown in FIG. 10 (b). As a result, the document 104 cannot move in the transport direction even at time t4, and continues to stay at the position shown in FIG.

FIG. 12 is a diagram showing an example of image data of a speckle pattern acquired by the tracking sensor 111 at times t3 and t4. As described above, from time t3 to time t4, the document 104 floats up and stays at a position immediately after the separation roller 109 so as to form a loop. Therefore, the positions of the surfaces of the document 104 irradiated with the coherent light 305 by the tracking sensor 111 shown in FIGS. 10 (a) and 10 (b) are almost the same. As a result, both the image data of the speckle pattern acquired by the tracking sensor 111 at the time t3 and the time t4 are shown in FIG.

FIG. 13 is a graph showing the transition of the output value of the tracking sensor 111 when the staple document 700 stays at the position shown in FIG. In FIG. 13, as in FIG. 8, the horizontal axis indicates time, and the vertical axis indicates the output of the tracking sensor 111 for each sampling cycle.

As described above, since the document 104 stays at the position shown in FIG. 11, the amount of movement in the transport direction is 0 pixels. As a result, as shown in FIG. 13, the value output by the tracking sensor 111 is always 0 pixels.

Comparing FIGS. 8 and 13, the output of the tracking sensor 111 is always 5 pixels in the case of a non-staple document, and 0 pixel in the case of a staple document 700. From this, in the case of the present embodiment, the CPU 202 determines that the stapled document has been conveyed when the movement amount per predetermined time is 2 pixels or less, so that the stapled document and the stapled document can be discriminated from each other. Is possible. As described above, the CPU 202 as the control means is used when the movement amount of the document detected by the tracking sensor 111 per predetermined time is equal to or less than a predetermined threshold value (2 pixels in the present embodiment) or less. Control to stop the feeding operation. On the other hand, when the movement amount of the document detected by the tracking sensor 111 per predetermined time is larger than the predetermined threshold value, the CPU 202 controls to continue the feeding operation of the document.

FIG. 14 is a diagram showing a case where a staple manuscript 703, which is another example of a staple manuscript, is fed. FIG. 14 (a) is a diagram showing a state at time t5 after the staple document 703 has passed the separation roller 109 and the retard roller 110, and FIG. 14 (b) is a diagram further showing the state of the separation roller 109 and the retard roller 110 from the time t5. It is a figure which shows the state of the time t6 (t5 <t6) which was rotated.

The staple manuscript 703 has one tip bound by the staple 701. When such a staple manuscript 703 is fed, as shown in FIG. 14 (b), the manuscript 104, which is the highest-level manuscript, rotates around the staple 701. When the document 104 rotates, the moving direction of the document 104 deviates from the transport direction, and the amount of movement of the document 104 in the transport direction decreases. Then, when the amount of movement of the document 104 in the transport direction per predetermined time is 2 pixels or less, the CPU 202 stops the feeding operation. As a result, even when the staple document 703 is fed, it is possible to determine that the document being fed is a staple document by using the tracking sensor 111.

In the present embodiment, as an example, the predetermined threshold value used by the CPU 202 when determining a staple document is set to 2 pixels, but this threshold value may be appropriately set according to the transport speed of the document.

<Control of staple document detection>
Next, the control of staple document detection according to the present embodiment will be described with reference to FIG. FIG. 15 is a flowchart showing the control of staple document detection executed by the CPU 202.

Upon receiving a scan job start instruction from the user from the operation unit 201 (S001), the CPU 202 detects whether or not the document 104 is set in the document tray 105 from the output of the document set detection sensor 106 in the document tray 105 (S001). S002). When the CPU 202 determines that the document 104 is not in the document tray 105 (N in S002), the CPU 202 executes the fixed reading mode (S003).

When the CPU 202 determines that the document 104 is in the document tray 105 (Y in S002), the CPU 202 effectively sets the tracking sensor 111 (S004). After that, the CPU 202 starts driving the transport motor 203 in order to transport the document 104 (S005).

After that, the CPU 202 monitors for a predetermined time whether or not the document 104 has reached the pre-separation sensor 108 in the transport path (S006, S007). If the document 104 does not reach the pre-separation sensor 108 even after a lapse of a predetermined time (Y in S007), the CPU 202 determines that the document 104 has not been conveyed as a document feeding jam (S008).

On the other hand, when the document 104 reaches the pre-separation sensor within a predetermined time (Y in S006), the CPU 202 starts sampling of the tracking sensor 111 (S009). After the start of sampling, the tracking sensor 111 performs sampling at predetermined sampling cycles, and the CPU 202 determines whether or not the output value of the tracking sensor 111 is equal to or less than a predetermined threshold value (S010).

When the output value of the tracking sensor 111 is equal to or less than a predetermined threshold value (Y of S010), the CPU 202 determines that the jam is due to the staple document and stops the feeding operation (S012). Then, the CPU 202 causes the operation unit 201 to display information indicating that the conveyed document 104 is a staple document (S013), and ends the job.

On the other hand, when the output value of the tracking sensor 111 always exceeds a predetermined threshold value for a predetermined time (Y in S011), the CPU 202 continues the feeding operation until the document 104 passes through the pre-separation sensor 108 (S014, S015). When the document 104 is present on the sensor 108 before separation even after the lapse of a predetermined time (Y in S015), the CPU 202 determines that the document 104 is a document retention jam in the transport path (S016). When the CPU 202 determines that the original jam is jammed, the CPU 202 stops the transfer motor 203 and ends the job (S018).

When the CPU 202 detects that the pre-separation sensor 108 is turned off within a predetermined time (Y in S014), the CPU 202 determines whether or not the next document is in the document tray 105 by the document set detection sensor 106 (Y of S014). S017). When the document to be conveyed next exists in the document tray 105 (Y in S017), the process repeatedly returns to S006, and the CPU 202 continues to detect whether or not the next document is a staple document. When there is no document in the document tray 105 (N in S017), the CPU 202 determines that all the documents loaded in the document tray 105 have been conveyed, and the CPU 202 stops driving the transfer motor 203 to end the job.

In the present embodiment, the CPU 202, which is a control means, controls whether or not to stop the document feeding operation based on the movement amount per ms. In this way, when the CPU 202 controls based on the "movement amount per predetermined time" of the document, it is assumed that the CPU 202 of the document controls based on the "speed".

FIG. 16 is a diagram showing a state in which a document 104 that is not bound by staples is fed in a state of being tilted with respect to a transport direction. Here, FIG. 16A is a diagram showing the manuscript 104 immediately after passing through the separation portion, and FIG. 16B is a diagram showing the manuscript 104 when a certain period of time has elapsed after passing through the separation portion.

As described above, whether or not the image reading device 80 according to the present embodiment stops the document feeding operation based on the movement amount (speed) of the document detected by using the tracking sensor 111 per predetermined time. To control. Specifically, when the speed of the document to be fed is higher than a predetermined speed (movement amount corresponding to 2 pixels for 1 ms in the present embodiment), the CPU 202 continues the document feeding operation. .. Then, when the speed of the document to be fed is smaller than the predetermined speed, the CPU 202 stops the document feeding operation.

As a result, when the staple document as shown in FIGS. 11 and 14 is detected by the tracking sensor 111, the CPU 202 can stop the document feeding operation and prevent the document from being damaged. On the other hand, as shown in FIG. 16, when the document 104 not bound by staples is fed in an inclined state, the amount of movement of the document 104 per predetermined time is not inclined (shown in FIG. 6). State) is the same. Therefore, when the document 104 not bound by the staple is fed in an inclined state, the CPU 202 does not determine that the document being fed is a staple document, and the feeding operation of the document 104 is continued.

In the conventional configuration, when there is a difference in the timing at which the tip of the document is detected by the plurality of optical sensors, the document feeding operation is stopped. Therefore, in the conventional configuration, as shown in FIG. 16, when the original document 104 not bound by staples is fed in an inclined state, the feeding operation is stopped.

Here, when the feeding operation is continued even when the document 104 in the state shown in FIG. 16 is fed using the conventional configuration, the predetermined time of the detection timing difference of the optical sensor when determining the staple document is increased. There is a need to. At this time, specifically, the predetermined time of the detection timing of the optical sensor when determining the staple document is about 18 ms. In this case, the jam detection is delayed, and the possibility that the original is damaged increases.

On the other hand, in the present embodiment, the staple document can be determined in 1 ms at the shortest. As described above, since the image reading device 80 according to the present embodiment can improve the discrimination accuracy of the staple document without delaying the detection of jam, whether or not to stop the document feeding operation. Can be improved in the configuration that controls.

Further, in the present embodiment, the ADF 20 has a configuration in which the highest-ranked original among the bundles of originals placed on the original tray 105 is separated and conveyed. In this ADF 20, when the staple document 703 shown in FIG. 14 is conveyed, only the uppermost document 104 may rotate and the lower document 308 may be in a stopped state. In the image reading device 80 according to the present embodiment, since the tracking sensor 111 is arranged in the transport guide portion 102b on the upper side of the transport path 200, it is possible to always detect the movement amount of the uppermost document 104. .. Therefore, it is possible to detect the movement of the top-level document 104 and determine whether or not the conveyed document is a staple document. If the tracking sensor 111 is arranged in the transport guide on the lower side of the transport path 200, when the staple document is transported, the tracking sensor 111 is hidden by the lower document 308, and the movement of the uppermost document 104. May not be detected. In this case, since the tracking sensor 111 can only detect that the document is stagnant, it cannot determine whether or not the jam is caused by the staple document. Therefore, it is desirable that the tracking sensor 111 is arranged on the opening / closing cover 102 on the upper side of the transport path 200 as in the present embodiment.

Further, while the original is repeatedly conveyed, dust such as paper dust of the original and glue attached to the original may adhere to the transparent portion 309 on the surface of the tracking sensor 111. If such dust adheres to the transparent portion 309, the tracking sensor 111 may not be able to normally acquire image data, and may not be able to detect the amount of movement of the document. However, in the present embodiment, the transparent portion 309 of the tracking sensor 111 can be exposed to the outside of the device by opening the open / close cover 102. As a result, even if dust adheres to the surface of the transparent portion 309, the dust adhered by the user can be easily removed. Here, a plurality of transparent portions 309 may be provided, in which case the transparent portions 309 facing the transport path 200 may be exposed.

In the ADF 20 shown in the present embodiment, the output tray 124 is arranged below the document tray 105, and the document 104 separated by the separation roller 109 is conveyed along the curved portion 200a of the transfer path 200 and then by the reader 40. It is a configuration that reads an image. If the original tray 105 is arranged below the output tray 124 and conveyed from the bottom to the top, the image of the original 104 is read in the vicinity of the downstream side of the separation portion. However, since the retard roller 110 applies a force to the document 104 in the direction opposite to the transport direction in the separation section, it is difficult to keep the transport speed of the document 104 constant, and the image is read when the image is read in the vicinity of the separation section. It leads to defects. Further, when the document 104 is read at a place away from the separation roller 109, it is necessary to lengthen the transport path 200 to the reading position P, which leads to an increase in the size of the device. Therefore, in the configuration in which the ADF 20 is provided on the upper portion of the reader 40, as shown in the present embodiment, the documents are separated before passing through the curved portion 200a of the U-shaped curved transport path 200, and after passing through the curved portion 200a. A configuration that reads an image is desirable. By using such a configuration, the distance from the separation portion to the reading position P can be lengthened, and reading defects can be reduced.

In the present embodiment, the tracking sensor 111 is arranged at the center of the transport path on the downstream side in the transport direction of the separation roller 109. However, the position of the tracking sensor 111 is not limited to this, and for example, the tracking sensor 111 may be arranged so as to be adjacent to the separation roller 109 in the main scanning direction. Further, the tracking sensor 111 may be arranged upstream of the separation roller in the transport direction.

<Modification example of detection means>
In the above embodiment, the configuration using the tracking sensor 111 to detect the speed of the document has been described. However, instead of the tracking sensor, a driven roller that comes into contact with the document and is driven may be newly provided, and the speed of the document may be detected by the rotation amount of the driven roller.

In the configuration in which the speed of the document is detected by using the driven roller, the driven roller is rotated by the movement of the document, so that the transfer resistance by the driven roller is generated. On the other hand, in the configuration using the tracking sensor 111, such transport resistance does not occur, so it is desirable to detect the speed of the document by using an image pickup unit such as the tracking sensor 111.

20 ADF
40 Reader 60 Image forming engine 70 Printer body 80 Image reader 101 Image reader 102 Open / close cover 111 Tracking sensor

Claims (7)

An image forming unit having an image forming means for forming an image on a sheet,
A reading unit provided above the image forming unit and reading an image of a document at a reading position,
A document transporting unit provided above the scanning unit to transport the document to the scanning position, and a document transporting unit.
It is an image forming device equipped with
The document transfer unit is
The manuscript tray on which the manuscript is placed and the manuscript tray
A feeding means for feeding the manuscript placed on the manuscript tray, and
A separation means for separating the highest-level original from the original fed by the feeding means into one sheet, and
A transport means for transporting a document separated by the separation means to the reading position via a curved portion of a transport path curved in a U shape, and a transport means.
A paper ejection tray provided at the bottom of the original tray and from which the originals whose images have been read by the reading unit are ejected.
Have,
A detection means for detecting the speed of the document conveyed by the document transfer unit, and
A control means for controlling whether or not to stop the document feeding operation based on the speed of the document detected by the detection means, and
An image forming apparatus comprising. The control means continues the document feeding operation when the speed of the document detected by the detection means is higher than the predetermined speed, and the speed of the document detected by the detection means is smaller than the predetermined speed. Is the image forming apparatus according to claim 1, wherein the feeding operation of a document is stopped. The detection means
An image pickup unit that captures an image of a document fed by the feeding means,
A detector that detects the speed of the document based on the output of the image pickup unit,
The image forming apparatus according to claim 1 or 2, wherein the image forming apparatus has. It is provided so as to be openable and closable, and has an opening / closing portion that forms a part of the transport path in a closed state and exposes a part of the transport path in an open state.
The image pickup unit is
An irradiation unit that irradiates the document fed by the feeding means with light,
A transparent part through which the light irradiated by the irradiation part and reflected by the document passes.
A sensor unit that receives light that has passed through the transparent unit and converts it into photoelectric light.
Have,
The image forming apparatus according to claim 3, wherein the transparent portion is exposed by opening the opening / closing portion. The image forming apparatus according to claim 4, wherein the image pickup unit is arranged in the opening / closing unit. The image forming apparatus according to any one of claims 1 to 5, further comprising a display means for displaying information indicating that the original whose speed is detected by the detection means is bound by staples. The reading unit has a document stand on which a document is placed.
The image forming apparatus according to any one of claims 1 to 6, wherein an image of a document fixed on the platen can be read.

Images