JP2013229709A - Image reading device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading device and an image forming device, capable of preventing paper jamming and manuscript damage caused by contact between a carried manuscript and a left manuscript with relatively low cost.SOLUTION: A reference image retention unit 501 stores image data read out by an image reading unit 120 at a specific position in a state that a manuscript carried by a manuscript carriage device 110 is not in a reading area of the image reading unit 120. A comparison unit 502 compares the image data, read out by the image reading device 120 at the specific position when the manuscript carriage device 110 starts carrying the manuscript, with the image data stored in the reference image retention unit 501. Based on the comparison result by the comparison unit 502, a determination unit 503 determines whether or not the carriage of the manuscript is to be started by the manuscript carriage device 110. A carriage control unit 504 controls the manuscript carriage device 110 to start carrying the manuscript, when the determination result of the determination unit 503 indicates that the manuscript carriage can be started.

Description

  The present invention relates to an image reading apparatus and an image forming apparatus including a document transport mechanism that transports a document from a document tray to an image reading position.

  2. Description of the Related Art As an image reading apparatus such as a copying machine, a facsimile machine, a scanner, or a multifunction machine, a configuration in which a movable carriage is provided below a document table is known. In such an image reading apparatus, an image of a document placed on the document table with the image reading target surface facing the document table can be read by moving the carriage. Further, in the image reading apparatus, a document conveying device is used to read images of a plurality of documents at high speed. The document conveying device automatically conveys documents stacked on the document tray one by one to the image reading position. As a result, the image reading apparatus can continuously read each original.

  In an image reading apparatus including such a document conveying device, a configuration in which an image reading position of a document conveyed by the document conveying device is set within a document placement range of a document table (see, for example, Patent Documents 1 and 2). And a configuration set outside the document placement range of the document table.

  For example, in the image reading apparatus disclosed in Patent Document 1, a reading unit that exposes a document surface of a passing document to the carriage side is formed at an image reading position set in a document transport path of the document transport device. . The reading unit is arranged above the document table with a slight gap, and even if the document is left on the document table, the document that is transported by the left document and the document transport device (hereinafter, appropriately transported). The document is not in contact with the original. In this image reading apparatus, when the document conveying apparatus is used, the carriage is temporarily fixed at a position corresponding to the image reading position.

  In such a configuration, when an undocumented document is on the document table, the undocumented document is interposed between the conveyed document and the carriage, so that the image of the conveyed document cannot be read. For this reason, in Japanese Patent Application Laid-Open No. 2004-133620, image data at both the time point when the transported document does not exist in the reading unit and the time point when the transported document exists in the reading unit are acquired. Judged to be left alone.

  In the image reading apparatus disclosed in Patent Document 2, the document conveying device conveys documents one by one on a document table. In this configuration, when a document is left on the document table, the transported document and the left document may interfere with each other, and a paper jam or document damage may occur. Therefore, in Patent Document 2, a black pattern is provided on a part of the white reference plate, and the black pattern is read before reading the conveyed document. If no black pattern is detected at this time, it is determined that the document is left on the document table.

  On the other hand, in the image reading apparatus in which the image reading position of the document conveyed by the document conveying apparatus is set outside the document placement range of the document table, a slit glass (reading glass) corresponding to the image reading position of the document conveying apparatus. Is provided. The slit glass is provided so as to be separated from the document table, and even if the document is left on the document table, the left document and the conveyed document are not in contact with each other.

JP 2010-109520 A JP 2006-165993 A

  As described above, in the image reading apparatus in which the image reading position of the document conveyed by the document conveying apparatus is set outside the document placement range of the document table, if the document is properly arranged on the document table, the image reading apparatus is left as it is. Even if there is a document, the document can be read using the document transport device without any problem. However, even when an original is placed on the platen and an image is read, for example, in order to read an image of a specific part in the original, the original may be placed with a part protruding from the platen. When such an original is left unattended, when the image reading is performed using the original conveying device, the conveyed original and the left original may interfere with each other, which may cause a paper jam or damage to the original.

  Even if it is going to apply the technique which the above-mentioned patent documents 1 disclose as a countermeasure against this, since patent documents 1 need to acquire image data at the time when a conveyance original exists in a reading part, this image data is acquired. At that time, there is a possibility that a paper jam or document breakage may occur.

  Further, in the technique disclosed in Patent Document 2, there is a possibility that a black pattern for detecting the presence or absence of a document may deteriorate due to a change with time and erroneous detection may occur. Therefore, additional care is required to avoid this erroneous detection. become.

  The above-described problem may be solved by installing a sensor for detecting the presence or absence of a document on the document table, or performing image reading and scanning on the document table before conveying the document. However, in the former case, there is a problem that parts cost and installation cost are required. In the latter case, it takes time to scan the carriage from when the user gives an instruction to execute image reading to when the conveyance of the document starts, so that there is a problem that the image reading processing time significantly increases.

  The present invention has been made in view of the above-described problems of the prior art, and an image reading apparatus and an image that can prevent paper jam and document damage due to contact between a transported document and a left document at a relatively low cost. An object is to provide a forming apparatus.

  In order to achieve the above object, the image reading apparatus according to the present invention employs the following technical means. That is, the image reading apparatus according to the present invention includes a document transport mechanism, an image reading unit, a reference image holding unit, a comparison unit, a determination unit, and a transport control unit. The document transport mechanism transports the documents placed on the document tray one by one to the image reading position. The image reading unit reads an image of the document transported by the document transport mechanism. The reference image holding unit stores image data read by the image reading unit at a specific position in a state where the document conveyed by the document conveying mechanism is not in the reading area of the image reading unit. The comparison unit compares the image data read by the image reading unit at a specific position when document conveyance by the document conveyance mechanism is started with the image data stored in the reference image holding unit. The determination unit determines whether or not to start document conveyance by the document conveyance mechanism based on the comparison result by the comparison unit. Then, the conveyance control unit causes the document conveyance mechanism to start document conveyance when the determination result of the determination unit indicates that document conveyance can be started.

  In this image reading apparatus, it is possible to detect the presence or absence of a document left on the document table when document conveyance by the document conveyance mechanism is started without installing a dedicated detector such as a sensor. As a result, it is possible to reliably prevent the occurrence of problems such as paper jams and document damage due to contact between the conveyed document and the undocumented document. In addition, in a configuration in which a document transported by the document transport mechanism does not exist in the reading area of the image reading unit, the left document is detected based on the image data read by the image reading unit and stored in the reference image holding unit. For this reason, it is possible to reliably prevent erroneous detection due to changes over time by appropriately updating the image data. For example, the reference image holding unit can store image data read by the image reading unit when the trailing edge of the document conveyed by the document conveying mechanism passes the image reading position. The passing document can be, for example, the last page of the document bundle conveyed by the document conveying mechanism or an arbitrary page.

  When the image reading apparatus includes a reading window provided corresponding to the image reading position and a document table provided adjacent to the reading window, the specific position is the reading window. The document platen side end can be used. Here, the reading window is used for reading an image of a document transported by a document transport mechanism. The document is placed on the document table for reading an image of the document without being transported by the document transport mechanism.

  For example, when a left document exists from the document table to the reading window, the document is always present at the end of the reading window on the document table side. Therefore, according to this configuration, it is possible to more reliably detect the presence or absence of a left document on the document table. Note that the document table side end of the reading window includes an end of the reading window on the document table side and the vicinity thereof.

  Further, in the image reading apparatus, when the determination result of the determination unit indicates that the document conveyance cannot be started, the position where the image reading unit of the image reading unit is temporarily fixed for reading the document image corresponds to the image reading position. You may further provide the reading position adjustment part which changes the image of the original conveyed from the position to the image reading position to the other position in the range which can be read. In this configuration, for example, if the cause of the inability to start document conveyance is a foreign object such as dust or a piece of paper present at the image reading position, the document is read automatically using the document conveyance mechanism after the foreign object is automatically avoided. Can be executed.

  On the other hand, in another aspect, the present invention can also provide an image forming apparatus including the above-described image reading apparatus and an image forming unit that prints a document image read by the image reading apparatus on a transfer target. .

  According to the present invention, it is possible to prevent the occurrence of problems such as paper jams and document breakage due to contact between the conveyed document and the undocumented document at a relatively low cost.

1 is a schematic configuration diagram showing the overall configuration of a multifunction machine according to an embodiment of the present invention. Sectional drawing which shows the structure of the document conveying apparatus in one Embodiment of this invention. The perspective view which shows the upper external appearance of the multifunctional device in one Embodiment of this invention. The figure which shows the hardware constitutions of the multifunctional device in one Embodiment of this invention. 1 is a functional block diagram showing a multifunction machine according to an embodiment of the present invention. 1 is a flowchart showing an image reading procedure of a multifunction machine according to an embodiment of the present invention. Functional block diagram showing another multifunction machine according to an embodiment of the present invention. The flowchart which shows the image reading procedure of the other multifunctional machine in one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. Hereinafter, the present invention is embodied as a digital multi-function peripheral having a document conveying device (document conveying mechanism).

  FIG. 1 is a schematic configuration diagram illustrating an example of the overall configuration of a digital multifunction peripheral according to the present embodiment. As shown in FIG. 1, the multifunction peripheral 100 includes a main body 101 including an image reading unit 120 and an image forming unit 140, and a platen cover 102 attached above the main body 101. An original table 103 made of a transparent plate such as contact glass is provided on the upper surface of the main body 101, and the original table 103 is opened and closed by a platen cover 102.

  An image reading unit 120 is provided below the document table 103. The image reading unit 120 reads an image of a document and generates digital data (image data) of the image. The document can be placed on the document table 103. A scanning optical system 121 is disposed below the document table 103. The scanning optical system 121 includes a first carriage 122 and a second carriage 123 that are image reading units. The first carriage 122 is provided with a linear light source 131 and a mirror 132, and the second carriage 123 is provided with mirrors 133 and 134. The light source 131 illuminates the document. The mirrors 132, 133, and 134 guide reflected light from the document to the condenser lens 124, and the condenser lens 124 forms an optical image on the light receiving surface of the line image sensor 125. In the scanning optical system 121, the first carriage 122 and the second carriage 123 are provided so as to be able to reciprocate in the sub-scanning direction 135. By moving the first carriage 122 and the second carriage 123 in the sub-scanning direction 135, the image of the document placed on the document table 103 can be read by the image sensor 125. The image sensor 125 generates document image data from the light image incident on the light receiving surface. Here, the image sensor 125 generates, for example, R (red), G (green), and B (blue) electrical signals based on the received light.

  In the image forming apparatus 100, the image data generated by the image reading unit 120 can be printed on a sheet by the image forming unit 140. Further, it can be transmitted to other devices (not shown) through the network 162 by the network interface 161.

  The image forming unit 140 prints image data generated by the image reading unit 120 or image data received from another device (not shown) connected to the network 162 via the network adapter 161 on a sheet. The image forming unit 140 includes a photosensitive drum 141. The photosensitive drum 141 rotates in one direction at a constant speed. Around the photosensitive drum 141, a charger 142, an exposure unit 143, a developing unit 144, and an intermediate transfer belt 145 are arranged in this order from the upstream side in the rotation direction. The charger 142 uniformly charges the surface of the photosensitive drum 141. The exposure device 143 irradiates the surface of the uniformly charged photoconductor drum 141 with light according to the image data, and forms an electrostatic latent image on the photoconductor drum 141. The developing device 144 attaches toner to the electrostatic latent image and forms a toner image on the photosensitive drum 141. The intermediate transfer belt 145 transfers the toner image on the photosensitive drum 141 onto a sheet. When the image data is a color image, the intermediate transfer belt 145 transfers each color toner image onto the same sheet. The RGB color image is converted into C (cyan), M (magenta), Y (yellow), and K (black) format image data, and the image data of each color is input to the exposure unit 643.

  The image forming unit 140 feeds paper from the manual feed tray 151, the paper feed cassettes 152, 153, and 154 to the transfer unit between the intermediate transfer belt 145 and the transfer roller 146. Various sizes of paper can be placed or stored in the manual feed tray 151 and the paper feed cassettes 152, 153, and 154. The image forming unit 140 selects a sheet specified by the user or a sheet corresponding to the automatically detected document size, and feeds the selected sheet from the manual feed tray 151 or the cassettes 152, 153, and 154 by the feeding roller 155. . The fed paper is transported to the transfer section by transport rollers 156 and registration rollers 157. The sheet on which the toner image is transferred is conveyed to the fixing device 148 by the conveyance belt 147. The fixing device 148 has a fixing roller 158 and a pressure roller 159 with a built-in heater, and fixes the toner image on the sheet by heat and pressing force. The image forming unit 140 discharges the sheet that has passed through the fixing device 148 to the discharge tray 149.

  In such a multifunction peripheral 100, the platen cover 102 includes a document conveying device 110 that is a document conveying mechanism. The document transport device 110 includes a document tray 111, a transport path 113, and a paper discharge tray 112. The user places a document on the document table 103 or sets the document on the document transport device 110. The document conveyance device 110 sends out the documents set on the document tray 111 to the conveyance path 113 one by one. An image reading position 114 is on the conveyance path 113. On the upper surface of the image reading unit 102, not only the document table 103 but also a slit glass (reading window) 104 for reading a document with respect to the image reading position 114 is provided. When reading an image of a document set on the document tray 111, the image reading unit 120 temporarily fixes the first carriage 122 and the second carriage 123 to the image reading position 114. When the document passes through the image reading position 114, the light source 131 illuminates the document. The light from the light source 131 is reflected by the original that passes through the slit glass 104 and passes through the image reading position 114, and is guided to the image sensor 125 by the mirrors 132, 133, and 134 and the condenser lens 124. The document that has passed the image reading position 114 is discharged to the paper discharge tray 112.

  FIG. 2 is a cross-sectional view showing an example of the mechanical configuration of the document conveying device in more detail. The document transport device 110 includes a pickup roller 201, a feeding belt 202, and a separation roller 203 in order to separate the documents one by one from the document bundle P placed on the document tray 111. The pickup roller 201 is pressed against the top end of the uppermost surface of the document bundle P. When the pickup roller 201 is driven in this state, the document is pulled out from the document bundle P. Even if there are two or more drawn documents, the first document is separated from the documents by the feeding belt 202 and the separation roller 203 and conveyed to the downstream side of the conveying path 113. A registration roller 204 and a conveyance roller 205 are provided downstream thereof. The timing at which the registration roller 204 conveys the image to the image reading position 114 is adjusted, and the conveying roller 205 conveys the document to the image reading position 114. The document that has passed the image reading position 114 where the image of the document is read is discharged to the discharge tray 112 by the discharge roller 206.

  The document tray 111 is provided with a document set sensor 207. Document set sensor 207 detects the presence or absence of documents on document tray 111. When the document set sensor 207 detects the document, the document transport device 110 raises the elevating plate 208 constituting a part of the document placement surface and presses the uppermost surface of the document bundle P against the pickup roller 201. The detection result of the document setting sensor 207 is also used for detecting the completion of conveyance of the document set on the document tray 111.

  FIG. 3 is a perspective view showing an upper appearance of the multifunction machine. As described above, the slit glass 104 is disposed adjacent to the document table 103, and the image reading position 114 of the document conveying device 110 is disposed to face the slit glass 104. Although not particularly limited, in the present embodiment, the image reading position 114 is set at the center of the slit glass 104 in the sub-scanning direction 135. That is, the image reading position 114 is set at a position where the conveyance roller 205 and the slit glass 104 are closest to each other and the positional relationship between the document and the slit glass 104 is most stable. An area where the positional relationship between the document and the slit glass 104 is stable has a certain width in the sub-scanning direction 135. Therefore, as described later, the positions of the first carriage 122 and the second carriage 123 are temporarily set not only in the image reading position 114 but also in the vicinity of the image reading position 114 (position shifted along the sub-scanning direction 135). It is possible to acquire the image data of the transported original even when it is fixed to.

  On the front side of the multifunction device 100, an operation panel 301 is provided for a user to input instructions and various settings for the multifunction device. In the present embodiment, the operation panel 301 includes a touch panel display 302 used for inputting instructions and displaying various information, and a start button 303 for instructing the start of processing.

  FIG. 4 is a hardware configuration diagram of a control system in the multifunction machine. The MFP 100 according to the present embodiment includes a CPU (Central Processing Unit) 401, a RAM (Random Access Memory) 402, a ROM (Read Only Memory) 403, an HDD (Hard Disk Drive) 404, an original transport device 110, and an image reading unit 120. A driver 405 corresponding to each drive unit in the image forming unit 140 is connected via an internal bus 406. The ROM 403, the HDD 404, and the like store programs, and the CPU 401 controls the multifunction peripheral 100 in accordance with instructions of the control program. For example, the CPU 401 uses the RAM 402 as a work area, and controls the operation of each driving unit by exchanging data and commands with the driver 405. The HDD 404 is also used to store image data obtained by the image reading unit 120 and image data received from other devices via the network adapter 161.

  An operation panel 301 and various sensors 407 are also connected to the internal bus 406. The operation panel 301 receives a user operation and supplies a signal based on the operation to the CPU 401. The operation panel 301 displays an operation screen on the display 302 in accordance with a control signal from the CPU 401. In addition to the document set sensor 207, the sensor 407 includes various sensors such as an open / close detection sensor for the platen cover 102, a detection sensor for the conveyed paper or document, and a temperature sensor for the fixing device 148. The CPU 401 executes, for example, a program stored in the ROM 403 to realize the following means (functional blocks) and controls the operation of each means according to signals from these sensors.

  FIG. 5 is a functional block diagram of the MFP according to the present embodiment. As illustrated in FIG. 5, the multifunction peripheral 100 of the present embodiment includes a reference image holding unit 501, a comparison unit 502, a determination unit 503, and a conveyance control unit 504.

  The reference image holding unit 501 stores image data read by the image reading unit 120 at a specific position in a state where the document conveyed by the document conveying device 110 is not in the reading area of the image reading unit 120. In the present embodiment, this specific position is set at the end of the slit glass 104 on the side of the document table 103. That is, in the present embodiment, the image data stored in the reference image holding unit 501 is obtained by temporarily fixing the first carriage 122 and the second carriage 123 according to the end of the slit glass 104 on the side of the document table 103. Acquired by the image reading unit 120 in a state. Although not particularly limited, in the present embodiment, the HDD 404 functions as the reference image holding unit 501.

  In the present embodiment, as will be described later, the image data stored in the reference image holding unit 501 includes the trailing edge of the document transported last in the document bundle P mounted on the document tray 111 of the document transport device 110. Acquired immediately after passing the image reading position 114. That is, the first carriage 122 and the second carriage 123 that are temporarily fixed to the image reading position 114 during the reading of the image data of the conveyed document are immediately after the trailing edge of the final document has passed the image reading position 114. Are temporarily fixed in accordance with the above-mentioned specific position. In this state, image data stored in the reference image holding unit 501 is acquired. Although not particularly limited, the image data includes image data for one line in the main scanning direction (scanning direction of the image sensor 125). In the present embodiment, the user can store the image data at the specific position in the reference image holding unit 501 at an arbitrary timing according to the user's instruction. With this configuration, appropriate image data is stored in the reference image holding unit 501 when an apparatus in which a document has never been conveyed is installed, or when wrong image data is stored in the reference image holding unit 501 due to some malfunction. It becomes possible to do.

  The comparison unit 502 compares the image data read by the image reading unit 120 at the specific position described above when the document conveyance by the document conveyance device 110 is started with the image data stored in the reference image holding unit 501. Here, “when the document conveyance is started” relates to the start of document reading, for example, the document bundle P is placed on the document tray 111, or a document reading start instruction is input by the user. This refers to the period from when the event occurs until the leading edge of the document that has been transported in response to a reading start instruction from the user reaches the image reading position 114. In the present embodiment, the image data read by the image reading unit 120 at the above-described specific position when the document conveyance by the document conveyance device 110 is started is the main scan, similarly to the image data stored in the reference image holding unit 501. This is image data for one line in the direction. The comparison unit 502 calculates a difference in each pixel corresponding to the image data and the image data stored in the reference image holding unit 501. Here, the difference is calculated for each of the R, G, and B color data.

  The determination unit 503 determines whether or not to start document conveyance by the document conveyance device 110 based on the comparison result by the comparison unit 502. In the present embodiment, the determination unit 503 performs the determination by comparing the absolute value of the difference between the color data calculated for each pixel by the comparison unit 502 with a predetermined threshold value. Here, if all of the absolute values of the differences between the color data calculated by the comparison unit 502 for each pixel are equal to or less than a predetermined value, it can be said that both image data to be compared are the same, and the determination unit 503 starts document conveyance. Judge that it is possible. Further, if part of the absolute value of the difference between the color data calculated by the comparison unit 502 for each pixel exceeds a predetermined value, the image data to be compared cannot be said to be the same. That is, since there is a possibility that a document left unattended on the slit glass 104, the determination unit 503 determines that the document conveyance cannot be started.

  For example, when the image reading unit 120 generates 256 tone image data for each of the R, G, and B colors, “20” can be specified as the above-described predetermined value. Further, the determination unit 503 may determine that the document conveyance cannot be started if the threshold is exceeded in at least one pixel. Alternatively, it may be determined that the document conveyance cannot be started when the threshold value is exceeded in at least the pixels exceeding the predesignated number of pixels.

  The conveyance control unit 504 causes the document conveyance device 110 to start document conveyance when the determination result of the determination unit 503 indicates that document conveyance can be started.

  In addition, the MFP 100 according to the present embodiment also includes a notification unit 505. When the determination unit 503 determines that the document conveyance cannot be started, the notification unit 505 notifies the user to that effect. As the notification method, any method that can be recognized by the user, such as display and voice, can be adopted. Here, the notification unit 505 displays a warning display on the display 302 of the operation panel 301 indicating that it is necessary to exclude the document or the like existing on the slit glass 104.

  FIG. 6 is a diagram illustrating an example of an image data reading procedure executed by the multifunction peripheral according to the present embodiment. In the present embodiment, for example, this procedure starts with a trigger that the user inputs an image reading instruction to the multi-function peripheral 100 by pressing the start button 303 or the like.

  The multifunction peripheral 100 (here, the conveyance control unit 504) to which the image reading instruction is input first checks whether or not the document bundle P is placed on the document conveying device 110. The confirmation can be easily determined based on the state of the document set sensor 207 described above. For example, if the document set sensor 207 has not detected a document, this procedure ends because the image is not read using the document conveying device 110 (No in step S601). On the other hand, when the document set sensor 207 detects the document, the conveyance control unit 504 inquires of the determination unit 503 whether the document conveyance can be started (Yes in step S601).

  At this time, the determination unit 503 instructs the comparison unit 502 to compare the image data at the end of the slit glass 104 on the side of the document table 103 and the image data stored in the reference image holding unit 501 at that time. In the following, the former image data is referred to as pre-conveyance image data, and the latter image data is referred to as reference image data.

  Upon receiving an instruction from the determination unit 503, the comparison unit 502 instructs the image reading unit 120 to acquire pre-conveyance image data. At this time, the image reading unit 120 acquires the image data by moving the first carriage 122 and the second carriage 123 to a position corresponding to the end of the slit glass 104 on the side of the document table 103 (step S602). Although not particularly limited, the pre-conveyance image data is held in the RAM 402. The comparison unit 502 reads the reference image data from the reference image holding unit 501 and calculates the above-described difference with the pre-conveyance image data held in the RAM 402. The comparison unit 502 inputs the calculated absolute value of the difference for each color in each pixel to the determination unit 503.

  The determination unit 503, to which the comparison result is input from the comparison unit 502, determines whether the document conveyance can be started or the document conveyance cannot be started as described above based on the comparison result (step S603). If the determination result indicates that document conveyance can be started, the determination unit 503 notifies the conveyance control unit 504 to that effect. Receiving the notification, the conveyance control unit 504 causes the document conveyance device 110 to start document conveyance (Yes in steps S603 and S604).

  When the conveyance of the document bundle P proceeds and the trailing edge of the final document has passed the image reading position 114, the document conveying device 110 notifies the image reading unit 120 to that effect (No in steps S605 and S605). Upon receiving the notification, the image reading unit 120 moves the first carriage 122 and the second carriage 123 immediately after the trailing edge of the final document has passed the image reading position 114, so that the edge of the slit glass 104 on the document table 103 side. Is acquired, and the image data is stored in the reference image holding unit 501 as reference image data (step S606). Note that the final document of the document bundle P can be easily detected by the state change of the document set sensor 207. Whether or not the trailing edge of the document has passed is determined by calculation based on the distance between the registration roller 204 and the image reading position 114, the document transport speed and the paper size, or the document placed on the transport path 113. It can be detected by a sensor that detects clogging. As the detection method, any method according to the structure of the document conveying device 110 can be adopted.

  On the other hand, in the determination in step S603, if the determination result indicates that the document conveyance cannot be started, the procedure ends. At this time, the determination unit 503 displays on the display 302 of the operation panel 301 a warning display that requests the notification unit 505 to remove a document left on the slit glass 104 and the like.

  As described above, since the MFP 100 is configured to detect an undocumented document on the slit glass 104 using the image sensor 125 provided in the image reading unit 120, a dedicated detector such as a sensor is installed. There is no need. Therefore, it is possible to reliably prevent the occurrence of problems such as paper jams and document breakage due to the contact between the conveyed document and the undocumented document at low cost. In addition, it is configured to detect an undocumented document based on the reference image data stored in the reference image holding unit 501, and the reference image data is updated every time the document conveying device 110 completes document conveyance. It is possible to reliably prevent the erroneous detection caused by it.

  Further, the multifunction peripheral 100 is based on image data at the end of the slit glass 104 on the side of the document table 103 where it is considered that the document is always present when the undocumented document exists from the document table to the reading window. Judgment is performed. Therefore, according to this configuration, it is possible to more reliably detect the presence or absence of a left document on the document table.

  In the above description, the acquisition position of the reference image data is the end of the slit glass 104 on the side of the document table 103. However, the position is not limited to this position. For example, the reference image data is acquired at the central portion of the slit glass 104 corresponding to the image reading position 114 for acquiring the image data of the transported original or the position between the central portion and the end of the slit glass 104 on the side of the original plate 103. May be. The acquisition timing of the reference image data may be any timing at which no document exists in the reading area of the image reading unit 120. Therefore, the reference image data may be acquired when any one page such as the first page of the document bundle conveyed by the document conveying device 110 passes, and the reference image data is acquired every time each page passes. May be. This configuration is particularly suitable when the acquisition position of the reference image data is set to the image reading position 114. In addition, it is not essential to acquire the reference image data for each document conveyance. For example, a configuration in which the reference image data is acquired and updated every plurality of document conveyances or every predetermined period can be employed.

  In the above description, the determination unit 503 is configured to calculate a difference for the image data of each color in each pixel. For example, an image of any one color of red (R), green (G), and blue (B) is used. The difference may be calculated using data.

  By the way, when the acquisition position of the reference image data is set to the center portion of the slit glass 104 such as the image reading position 114, the dust or dirt present on the slit glass 104 is compared with the case of the end portion of the slit glass 104 on the side of the platen 103. It is considered that there is a high possibility that it is determined that document conveyance cannot be started due to a foreign matter such as a piece of paper. Therefore, hereinafter, another configuration that can be applied when the acquisition position of the reference image data is the central portion of the slit glass 104 like the image reading position 114 will be described.

  FIG. 7 is a schematic configuration diagram illustrating an example of the overall configuration of another digital multi-function peripheral according to the present embodiment. In FIG. 7, components having the same operational effects as the components of the multifunction machine 100 are denoted by the same reference numerals, and detailed description thereof will be omitted. As illustrated in FIG. 7, the multifunction peripheral 700 according to the present embodiment includes a reading position adjustment unit 701 in addition to the components of the multifunction peripheral 100. In the multi-function device 700, the specific position from which the reference image data is acquired is the image reading position 114, other than the range in which the image of the document conveyed to the image reading position 114 can be read (for example, the range of the slit glass 104). Of the slit glass 104 (hereinafter referred to as a preliminary reading position) and an end portion of the slit glass 104 on the side of the original platen 103 (hereinafter referred to as a left document checking position). That is, in the multi-function device 700, the image data stored in the reference image holding unit 501 is acquired by the image reading unit 120 at a plurality of positions.

  When the determination result of the determination unit 503 at the image reading position 114 indicates that the document conveyance cannot be started, the reading position adjustment unit 701 moves the first carriage 122 and the second carriage 123 to the left document confirmation position. If the determination result of the determination unit 503 at the undocumented document confirmation position is that the document conveyance can be started, a range in which the image of the document conveyed by the first carriage 122 and the second carriage 123 to the image reading position 114 can be read (for example, , It is moved to the preliminary reading position, which is another position within the range of the slit glass 104).

  FIG. 8 is a diagram illustrating an example of an image data reading procedure executed by the multi-function device 700. In this embodiment, for example, this procedure starts with a trigger that the user inputs an image reading instruction to the multi-function device 700 by pressing the start button 303 or the like.

  The multifunction peripheral 700 (here, the conveyance control unit 504) to which the image reading instruction is input confirms whether or not the document bundle P is placed on the document conveying device 110, similarly to the multifunction peripheral 100. If the document bundle P is not placed, this procedure ends (No in step S801). On the other hand, when the document set sensor 207 detects the document, the conveyance control unit 504 inquires of the determination unit 503 whether the document conveyance can be started (Yes in step S801). At this time, the determination unit 503 instructs the comparison unit 502 to compare the image data at the image reading position 114 at that time with the reference image data stored in the reference image holding unit 501.

  Upon receiving an instruction from the determination unit 503, the comparison unit 502 instructs the image reading unit 120 to acquire pre-conveyance image data. At this time, the image reading unit 120 moves the first carriage 122 and the second carriage 123 to a position corresponding to the image reading position 114 and acquires image data (step S802). Similar to the multifunction machine 100, the pre-conveyance image data is held in the RAM 402. The comparison unit 502 reads the reference image data corresponding to the image reading position 114 from the reference image holding unit 501, and calculates the above difference with the pre-conveyance image data held in the RAM 402. The comparison unit 502 inputs the calculated absolute value of the difference for each color in each pixel to the determination unit 503.

  The determination unit 503, to which the comparison result is input from the comparison unit 502, determines whether the document conveyance can be started or not based on the comparison result (step S803). If the determination result indicates that document conveyance can be started, the determination unit 503 notifies the conveyance control unit 504 to that effect. Upon receiving the notification, the conveyance control unit 504 causes the document conveyance device 110 to start document conveyance (Yes in steps S803 and S808).

  When the conveyance of the document bundle P proceeds and the trailing edge of the final document passes the image reading position 114, the document conveying device 110 notifies the image reading unit 120 to that effect (No in steps S809 and S809). Receiving the notification, the image reading unit 120 receives the image data at the image reading position 114, the image data at the preliminary reading position, and the image data at the left document confirmation position immediately after the trailing edge of the final document has passed the image reading position 114. The acquired image data is stored in the reference image holding unit 501 as reference image data (step S810).

  On the other hand, in the determination in step S803, if the determination result indicates that the document conveyance cannot be started, the determination unit 503 notifies the reading position adjustment unit 701 accordingly. Upon receiving the notification, the reading position adjustment unit 701 causes the image reading unit 120 to move the first carriage 122 and the second carriage 123 to a position corresponding to the left document confirmation position (step S804). When the movement of the first carriage 122 and the second carriage 123 is completed, the reading position adjustment unit 701 notifies the determination unit 503 to that effect. Upon receiving the notification, the determination unit 503 instructs the comparison unit 502 to compare the pre-conveyance image data and the reference image data in the state, and whether or not the document conveyance can be started based on the comparison result. It is determined whether it is impossible (step S805). Upon receiving the comparison instruction from the determination unit 503, the comparison unit 502 instructs the image reading unit 120 to acquire the pre-conveyance image data again, and the reference image data corresponding to the left document confirmation position and the pre-conveyance image data. The above difference is calculated. The comparison unit 502 inputs the calculated absolute difference for each color in each pixel to the determination unit 503.

  If the determination result of the determination unit 503 indicates that the document conveyance cannot be started, the procedure ends (No in step 805). In this case, since there is a high possibility that a left document exists at the end of the slit glass 104 on the side of the document table 103, the determination unit 503 removes the left document on the slit glass 104 from the notification unit 505. A warning display requesting the user to be displayed is displayed on the display 302 of the operation panel 301.

  If the determination result indicates that document conveyance can be started, the determination unit 503 notifies the reading position adjustment unit 701 to that effect. Upon receiving the notification, the reading position adjustment unit 701 causes the image reading unit 120 to move the first carriage 122 and the second carriage 123 to the preliminary reading position (steps S805 Yes and S806). When the movement of the first carriage 122 and the second carriage 123 is completed, the reading position adjustment unit 701 notifies the determination unit 503 to that effect. Upon receiving the notification, the determination unit 503 instructs the comparison unit 502 to compare the pre-conveyance image data and the reference image data in the state, and whether or not the document conveyance can be started based on the comparison result. It is determined whether it is impossible (step S807). By adopting such a configuration for changing the document reading position, for example, when the absolute value of the difference calculated by the comparison unit 502 exceeds a threshold value due to foreign matter such as dust or a piece of paper on the slit glass 104 The document can be read at a position different from the position where the foreign object exists. The comparison unit 502 that has received the comparison instruction from the determination unit 503 instructs the image reading unit 120 to acquire the pre-conveyance image data again, and between the reference image data corresponding to the preliminary reading position and the pre-conveyance image data. The above difference is calculated. The comparison unit 502 inputs the calculated absolute difference for each color in each pixel to the determination unit 503.

  If the determination result of the determination unit 503 is that document conveyance can be started, the above-described procedure is executed (steps S807 Yes, S808, S809 Yes, S810). On the other hand, if the determination result indicates that the document conveyance cannot be started, the procedure ends (No in step S807). In this case, since there is no abnormality confirmed at the end of the slit glass 104 on the side of the document table 103, the possibility that an undocumented document exists is extremely low. Therefore, the determination unit 503 causes the notification unit 505 to display a warning display requesting the user to remove dust on the slit glass 104 on the display 302 of the operation panel 301.

  As described above, in the multi-function device 700, first, it is determined whether or not the determination result of the determination unit 503 at the image reading position 114 cannot start the document transport, and only when the document transport cannot be started. Re-determination is performed at the end of the glass 104 on the side of the document table 103. Therefore, when there is no abnormality at the image reading position 114, the document reading can be started without moving the carriage, so that time can be saved. Further, when it is possible to start document conveyance in the re-determination at the edge of the document glass 103 side of the slit glass 104, it is determined that there is no left document and dust is attached, and the carriage is moved to another position within the range of the slit glass 104. Move. Therefore, after automatically avoiding foreign matters such as dust and paper pieces on the slit glass 104, it is possible to execute document reading using the document conveying device 110.

  In the above description, when the determination result of the determination unit 503 at the undocumented document confirmation position indicates that document conveyance can be started, the document reading position is moved only once. However, the preliminary reading positions are set at a plurality of positions. The document reading position may be moved a plurality of times. Further, in the above description, as a particularly preferable mode, a configuration in which re-determination is performed at the end portion of the slit glass 104 on the side of the original table 103 when the determination result at the image reading position 114 cannot start the original conveyance is illustrated. However, the determination may be performed by the determination unit at the preliminary reading position by moving the carriage to the preliminary reading position without performing the determination again. As described above, since the image reading position and the preliminary reading position are very close to each other in the sub-scanning direction 135, if there is no abnormality in the preliminary reading position, the abnormality in the image reading position is caused by foreign matters such as dust. This is because the possibility is extremely high. The preliminary reading position is more preferably set between the image reading position 114 and the end of the slit glass 104 on the side of the document table 103.

  As described above, according to the present invention, it is possible to prevent the occurrence of problems such as a paper jam or document breakage due to contact between a transported document and a left document at a relatively low cost.

  The above-described embodiments do not limit the technical scope of the present invention, and various modifications and applications other than those already described are possible within the scope of the present invention. For example, in the above-described embodiment, the description has been made based on the multifunction peripheral including the reduction optical system that forms an image of the document on the image sensor fixed outside the carriage by the movement of the first and second carriages. However, the present invention can also be applied to a multi-function machine including a contact optical system in which a light source and an image sensor are mounted on one carriage. In the above embodiment, the structure in which the document table and the slit glass are physically separated has been described. However, in the present invention, the document table also serves as the slit glass, and the specific position of the document table is set as the image reading position. It is applicable to.

  Further, in the flowcharts shown in FIGS. 6 and 8, the order of the steps can be appropriately changed within a range where the equivalent action is achieved. For example, in the above-described embodiment, the procedure is started in response to the user's document reading start instruction. However, the same effect can be obtained even if the procedure is started with the document bundle P placed on the document tray 111 as a trigger. be able to.

  Further, in the above-described embodiment, the pre-conveyance image data is acquired for all of the main scanning directions. However, in the configuration in which the size of the original document mounted on the original document conveying device can be recognized, the pre-conveyance image data is within the original document size range. The structure which acquires data may be sufficient.

  In addition, in the above-described embodiment, the present invention is embodied as a digital multifunction peripheral. However, the present invention is not limited to these apparatuses, and an arbitrary image reading apparatus including a document transport mechanism such as a printer, a facsimile, a copying machine, or a multifunction peripheral. It is also possible to apply the present invention to image forming apparatuses.

  According to the present invention, it is possible to prevent paper jamming and document damage due to contact between a transported document and a left document at low cost, which is useful as an image reading apparatus and an image forming apparatus.

100, 700 MFP 103 Document table 104 Slit glass (reading window)
122 First carriage (image reading unit)
123 Second carriage (image reading unit)
120 Image Reading Unit 110 Document Conveying Device (Document Conveying Mechanism)
501 Reference image holding unit 502 Comparison unit 503 Determination unit 504 Transport control unit 701 Reading position adjustment unit

Claims (5)

A document transport mechanism for transporting documents placed on the document tray one by one to the image reading position;
An image reading unit that reads an image of a document conveyed by the document conveyance mechanism;
A reference image holding unit for storing image data read by the image reading unit at a specific position in a state where a document conveyed by the document conveying mechanism is not in a reading area of the image reading unit;
A comparison unit that compares image data read by the image reading unit at the specific position when document conveyance by the document conveyance mechanism is started with image data stored in the reference image holding unit;
A determination unit that determines whether or not to start document conveyance by the document conveyance mechanism based on a comparison result by the comparison unit;
A conveyance control unit that causes the document conveyance mechanism to start document conveyance when the determination result of the determination unit is that document conveyance can be started;
An image reading apparatus comprising: A reading window provided corresponding to the image reading position for reading an image of the document conveyed by the document conveying mechanism;
A document table provided adjacent to the reading window on which the document is placed for image reading of the document without conveyance by the document conveyance mechanism;
Further comprising
The image reading apparatus according to claim 1, wherein the specific position is an end portion on the original platen side of the reading window.   When the determination result of the determination unit indicates that the document conveyance cannot be started, the position where the image reading unit of the image reading unit is temporarily fixed for reading the document image is read from the position corresponding to the image reading position. The image reading apparatus according to claim 1, further comprising a reading position adjusting unit that changes the image of the document conveyed to the position to another position within a readable range.   The reference image holding unit stores image data read by the image reading unit when a rear end of the document conveyed by the document conveying mechanism passes the image reading position. The image reading apparatus according to item. An image reading apparatus according to any one of claims 1 to 4,
An image forming unit that prints a document image read by the image reading device on a transfer medium;
An image forming apparatus comprising:

Images