JP2011010182A - Image reading apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a cleaning operation, with such a timing as to prevent adversely affecting a read image of a document.SOLUTION: An image reading apparatus 100 includes read glass 215 provided at a read position 211 on a feeding path of a document 103, and an exposure unit 206 which irradiates the document 103, passing on a surface of the read glass 215 with light via a rear side of the read glass 215 and optically reads the image in accordance with a designated read size, and controls a cleaning operation having a cleaning section 202 slide on a front side of the read glass 215. Under such a control, the actual size of the document 103 passing through the read position 211 is detected. The time for starting the cleaning operation is then determined to be the time, at which the document 103 completely passes through the read position 211 in the case of read size ≤ real size, or to be the time at which the document 103 is completely read, in accordance with the actual read size for the case of: read size > real size.

Description

  The present invention relates to an image reading apparatus and method, and more particularly to a sheet-through type image reading apparatus used as an image input apparatus such as a copying machine or a scanner.

  Conventionally, as an image reading apparatus for optically reading an image of a document, a platen set method for reading an image of a document placed on a platen glass, and a document are conveyed one by one, and an image of the document is read during conveyance. The sheet-through method was used alone or in combination. The sheet-through method has advantages in downsizing, low cost, low noise, high-speed image reading, and high print productivity, and has become the mainstream of image reading devices in monochrome copiers and color copiers. .

  In the case of the sheet-through method, the image reading position is fixed, that is, fixed on a transparent member (elongated reading glass), and the reading optical system is focused on the image surface of the conveyed document through the reading glass. Due to the configuration, it is easily affected by foreign matter such as dust attached to the reading glass and residual dust, and the portion shielded by the foreign matter becomes streak-like image noise in the read image. If the document is paper, a problem that fine foreign matters such as fillers and fibers contained in the paper such as calcium carbonate adhere to the reading glass is unavoidable.

  In order to solve such problems, conventionally, in the process of processing a read image, measures such as detecting dust on the image and issuing a warning to the user, or eliminating streak noise as image processing, etc. have been taken. It was.

  Conventionally, as another method for avoiding such a dust problem, as shown in, for example, Japanese Patent Application Laid-Open No. 6-164863, a felt-like cleaner is used in a reading portion of a document image supplied by automatic conveyance. The structure which cleans by rotating is proposed.

  Further, the device of Patent Document 2 (Japanese Patent Laid-Open No. 2000-270152) provides an elastic member on the outer peripheral surface of the white roller and rotates the white roller to remove dust adhering to the contact glass surface at the reading position. To do.

  The apparatus disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2007-306330) moves a foreign substance attached to a reading position by moving the reading glass, and removes the foreign substance from the reading position.

JP-A-6-164863 JP 2000-270152 A JP 2007-306330 A

  Here, as a timing for starting the cleaning member, Patent Document 3 merely moves the reading glass when the read original passes through the reading position, and pays attention to the size of the original to be read. Absent. This is because the reading glass itself is a transparent member, and even if it moves during reading, there is no effect on the read image. The reading glass has moved even if the reading of the original has not been completed.

  On the other hand, the method of rotating the cleaning member on the reading glass surface as in Patent Document 2 requires less cleaning time than the method in which the reading glass moves, and image reading productivity (reading per unit time). This is advantageous for the number of documents. In order to increase the reading productivity, it is necessary to minimize the interval between the documents conveyed to the reading position. However, if the distance between the originals is reduced, the glass exposure time that allows cleaning by the cleaning member is shortened. In order to efficiently perform cleaning, it is conceivable to start the cleaning member earlier. However, if the cleaning member is started too early, the original and the cleaning member may compete on the reading glass surface, which may adversely affect the read image. In order to avoid this, the reading productivity is lowered when the document conveyance interval is increased and the glass exposure time is increased.

  Therefore, it is important to consider the size of the document to be read in order to activate the cleaning member at a timing that does not adversely affect the read image without reducing the reading productivity of the document. However, none of the above-mentioned patent documents proposes a configuration in which the cleaning member is activated in consideration of the size of the document.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image reading apparatus and method for starting a cleaning member at a timing that does not adversely affect a read image of a document.

  An image reading apparatus according to an aspect of the present invention includes a plate-like transparent member provided at a predetermined reading position in a document transport path, and a document that is passing through a reading position on one surface of the transparent member. A cleaning unit that rubs one surface of the transparent member with a scanning member prepared in advance and a reading unit that optically reads the document according to a predetermined reading size by irradiating light through the transparent member from the other surface side And a control unit for controlling.

  The above-described control unit includes an actual size detection unit that detects the actual size of the document that passes on one side of the transparent member, and a time for starting the cleaning operation. Is determined to be a time for completing the passage of the document, and when the reading size> the actual size, the reading unit determines the time for completing the reading of the document according to the reading size.

  Preferably, the control unit completes passing through the reading position based on the conveyance speed and the distance between the first position and the reading position when the document has passed through the first position upstream of the reading position in the conveyance path. Detect time.

  Preferably, the control unit detects the completion time of reading by adding the time calculated based on the difference between the read size and the actual size and the conveyance speed to the completion time of passage.

  Preferably, the apparatus further includes a document transport unit that transports the document one by one along the transport path so that the document passes through a predetermined position, and the document transport unit has a time for the document transported to the next position to reach the reading position. The original is conveyed so as to be delayed by an amount corresponding to the added time.

  Preferably, the control unit further includes a reading size detection unit that detects a predetermined reading size in accordance with a mode input from the outside.

  Preferably, when the mode indicates a mixed loading mode in which the sizes differ for each conveyed document, the reading size detection unit detects the reading size based on the actual size.

  Preferably, the apparatus further includes a document size detection unit that detects a size of a document placed in advance so as to be fed to the transport path, and the mode is a non-mixing mode in which the sizes of the documents to be transported are the same. When instructing, the reading size detection unit detects the reading size based on the size detected by the document size detection unit.

  Preferably, when the mode indicates the user designation mode, the reading size detection unit detects the reading size based on the size input from the outside.

Preferably, the read size refers to a prescribed size of a sheet on which the read document is to be printed.
According to another aspect of the present invention, an image reading method includes a transparent member from a second surface side of a document passing over one surface of a plate-like transparent member provided at a predetermined reading position for reading a document. Irradiating light through the step of optically reading the document according to a predetermined reading size;
Controlling a cleaning operation by a cleaning member that rubs and cleans the one surface of the transparent member. In the controlling step, the step of detecting the actual size of the document passing through the reading position and the time for starting the cleaning operation are determined as the time when the document completes passing through the reading position when the reading size ≦ the actual size. And, when the read size> the actual size, the step of determining the time to complete the reading of the document according to the read size.

  According to the present invention, the document reading operation is continuously performed according to a predetermined reading size. However, regardless of the actual size of the document, the cleaning operation is started while reading the document, and the shadow of the cleaning member is shadowed. It can be prevented from being read together with the document.

1 is a schematic configuration diagram of an image reading apparatus according to an embodiment. It is a schematic hardware block diagram including the drive system of the motor of the reading part and ADF part of this Embodiment. It is a block diagram of the image processing part which concerns on this Embodiment. It is explanatory drawing which shows the cleaning operation | movement of the reading glass by the cleaning part which concerns on this Embodiment. (A)-(C) are figures which show the brush of the cleaning part which concerns on this Embodiment. It is a perspective view explaining the structure for driving the cleaning part which concerns on this Embodiment. It is a block diagram which shows the control part of the image reading apparatus which concerns on this Embodiment. It is a figure explaining the size of the manuscript concerning this embodiment, and its detection method. (A) to (C) are diagrams showing detection and comparison of the actual document size and the read document size according to the present embodiment. (A) and (B) are diagrams illustrating the start of a cleaning operation based on a comparison of document sizes according to the present embodiment. It is a flowchart which shows the detection procedure of the starting timing of the cleaning part which concerns on this Embodiment. (A)-(C) are timing charts showing the relationship between the document reading time and the cleaning time according to the present embodiment.

  Hereinafter, an image reading apparatus according to an embodiment of the present invention will be described with reference to the drawings. The same reference numerals indicate the same or corresponding members.

[Outline of device]
Referring to FIG. 1, an image reading apparatus 100 includes an ADF (Auto Document Feeder) unit 101 that automatically conveys a document and a reading unit 102 that reads a document.

  In the ADF unit 101, the originals 103 stacked on the original tray 200 are sent out one by one by the paper supply unit 201 to the conveyance path. The sent document 103 is conveyed from the conveyance path (1) to the reading position 211 through (2).

  The reading unit 102 exposes the original 103 passing through the reading position 211 with the exposure unit 206. Light reflected from the original 103 by exposure is received by a CCD (Charged Coupled Device) 209 through a reading glass 215, which is an example of a plate-like transparent member, a mirror group 207, and a lens 208. The CCD 209 converts the received light signal into RGB data by photoelectric conversion and outputs it to the image processing unit 210. The image processing unit 210 generates image data based on the RGB data. The generated image data is printed on output paper or the like.

  The document 103 that has passed the reading position 211 is conveyed by the post-reading roller 212 and is positioned in the switching units 203 and 204. Switching units 203 and 204 act to switch the transport path of the original 103 when the original 103 is detected. As a result, the document 103 is conveyed in the direction of the conveyance path (7), and the document 103 that has been read and is sent to the outside from the conveyance path is accommodated, but is discharged to the discharge tray 214. When reading the other side (back side) of the document 103, the transport path of the document 103 is switched when the one side (front side) is read at the reading position 211 and transported and positioned at the switching units 203 and 204. When the reversing unit 205 reverses the front and back of the original 103, the original 103 is transported from the transport path (3) through (4) and sent to the reading position 211. Alternatively, the document 103 is reversed and discharged by the switching unit 203 through the conveyance paths (5) to (6).

  The document tray 200 of the ADF unit 101 includes a guide member (not shown) for preventing the document 103 from being inclined when being fed from the document tray 200 to the conveyance path. Furthermore, a combination of a position detection sensor (not shown) connected to the guide member and a plurality of document detection members provided at a predetermined interval on a straight line extending in the conveyance direction of the document tray 200 provides a document. A size detection unit 104 that detects the size of the document 103 on the tray 200 is included.

  In the image reading apparatus 100, if there is a foreign substance such as paper dust or adhesive on the reading glass 215 at the reading position 211, the image data read from the original 103 has color streaks caused by the foreign substance according to the direction in which the original 103 is conveyed. Noise appears. Therefore, the ADF unit 101 includes a cleaning unit 202 so as to face the exposure unit 206 with the reading glass 215 sandwiched at the reading position 211 in order to remove foreign matters such as paper dust and adhesive. The cleaning unit 202 sweeps the surface of the reading glass 215 through which the document 103 passes in synchronization with the conveyance interval of the document 103. Details of the configuration and function of the cleaning unit 202 will be described later.

  With reference to FIG. 2, control blocks of the ADF unit 101 and the reading unit 102 will be described. A CPU (Central Processing Unit) 300 that controls the ADF unit 101 is connected to be able to communicate with a CPU 313 that controls the reading unit 102. Through this communication, various control information such as the size information of the original 103, the operation mode of the image reading apparatus 100, and information related to the timing for reading the original 103 are exchanged.

  Connected to the CPU 300 are pulse motors 231, 232, and 233 for driving each section such as a roller for document conveyance in the ADF unit 101 and motor drive ICs (Integrated Circuits) 301, 302, and 303 for controlling the motors. ing. The CPU 300 generates excitation signals φ0 to φ3 according to the magnification and mode and outputs them to these pulse motors. As a result, the pulse motor rotates based on the excitation signals φ0 to φ3, so that the conveyance speed of the original 103 is variably controlled according to the magnification and the mode. As a result, the conveyance interval of the original 103 and the synchronization of the reading operation and the conveying operation of the reading unit 102 are controlled. For this reason, in this example, the drive system divides and drives the paper feed unit for feeding the original 103 from the original tray 200 to the transport path, the reading unit, the discharge unit for the original 103, and the like. The rotation speed and rotation direction of the motor are switched according to the conveyance timing of the document 103.

  Further, here, the CPU 300 is connected to a pulse motor 234 coupled to the cleaning unit 202 and a motor drive IC 304 that controls the pulse motor 234. The position relating to the cleaning unit 202 is controlled by a pulse motor 234. In addition, a home position sensor 236 is connected to detect a position reference related to the cleaning unit 202.

  On the other hand, the reading unit 102 is controlled by the CPU 313. The CPU 313 is connected to a motor 235 and a motor drive IC 305 that controls the motor 235. In the reading unit 102, the exposure unit 206 and the mirror group 207 constitute a unit that can slide integrally. The unit is connected to the motor 235 and slides in the direction indicated by the arrow Y in FIG. 1 in conjunction with the rotation of the motor 235. By this sliding movement, the unit moves along an axis extending in the arrow Y direction. Reading a document image by a sheet through (ADF) method is performed in a state where the exposure unit 206 is stationary at a reading position 211 shown in FIG.

  The CPU 313 connects the image processing unit 210 that inputs RGB data output from the image input unit 318 corresponding to the CCD 209, inputs the image data output from the image processing unit 210, and outputs the image data to an image data output unit (not shown). Send it out.

  Referring to FIG. 3, the image processing unit 210 receives red (R), green (G), and blue (B) image data from an image input unit 209 corresponding to the CCD 209. An A / D (Analog / Digital) converter 12 converts analog image data input from the image input unit 209 into digital image data. The SH correction unit 13 performs shading correction on the image data input from the A / D conversion unit 12 and outputs the image data after the shading correction to the brightness / color difference separation unit 14. The brightness / color difference separation unit 14 separates the image data into a brightness component and a color difference component, and outputs each to the image adjustment unit. The image adjustment unit includes a sharpness adjustment unit 15, an HVC adjustment unit 16, and a density correction unit 18. The sharpness adjustment unit 15 executes a process for sharpening the image, and the HVC adjustment unit 16 adjusts the hue (H), lightness (V), and saturation (C) of the image. The density correction unit 18 corrects the density of the image. The image adjustment unit outputs the processed RGB image data to the color space conversion unit 17. The color space conversion unit 17 converts the color space of the image data from the RGB color space to the L * A * B * color space, and outputs it to the compression / decompression unit 19. The compression / decompression unit 19 compresses the image data. The compression / decompression unit 19 stores the compressed image data in a memory 30 such as an HDD (hard disk). Or output to an external device. For the sharpness adjustment unit 15, HVC adjustment unit 16, and density correction unit 18, the read image is optimized by the image parameter setting 32 for adjusting the image density and the like.

(Configuration and function of the cleaning unit)
With reference to FIG. 4, the structure of the cleaning part 202 and its peripheral part is demonstrated. A guide sheet 41 that guides the document 103 directly above the surface of the reading glass 215 through which the document 103 passes is disposed upstream of the reading glass 215 in the conveyance direction B so that the image surface of the document 103 does not contact the glass surface. Has been. Here, the side that supplies (sends) the document 103 to the reading position 211 while passing the paper passing sensor 217 by the rotation of the pre-reading roller 213 with the reading position 211 as a reference is referred to as “upstream side in the conveyance direction B”. The side on which the read original 103 is sent from the reading position 211 by the rotation of the post-reading roller 212 is referred to as “downstream side in the transport direction B”.

  The original 103 conveyed on the glass surface of the reading glass 215 is guided by sliding on the guide sheet 41, so that the original 103 is conveyed in a state where the image surface is not in contact with the surface of the reading glass 215. The

  By conveying the document 103 to the reading glass 215 in a non-contact manner, such transfer and adhesion of foreign matter can be prevented in advance. Of course, in the present embodiment, even if adhesive foreign matter adheres to the reading glass 215, it can be eliminated by the cleaning unit 202 described below.

  In the present embodiment, it is also possible to invert the front and back of the original 103 on which images are formed on both sides, and pass the reading position 211 again to continuously read the front and back images. Such a double-sided reading mechanism of the document 103 is well known, and the description thereof is omitted.

  As shown in FIG. 4, in the cleaning unit 202, a brush-like cleaning member 45 is rotatably disposed so as to face the reading position 211 of the reading glass 215. Further, a striking member 46 is disposed downstream of the cleaning member 45 in the document conveyance direction B. The cleaning member 45 is provided with a cleaning brush 45b that can be elastically deformed on a flat surface of the shaft member 45a. Assuming an axis extending along the conveyance direction B, the cleaning brush 45b extends in a line shape orthogonal to the axis.

  The shaft member 45a rotates forward or reverse in accordance with a predetermined timing and speed in conjunction with the rotation of the motor 234 (see FIG. 2). A white reference discriminating member (white film) 45c may be attached to the outer peripheral surface of the shaft member 45a opposite to the surface on which the cleaning brush 45b is fixed for shading correction.

  The cleaning brush 45b is obtained by implanting conductive polyimide resin, for example. When the cleaning unit 202 starts the cleaning operation, the shaft member 45a rotates forward from the upstream side in the document transport direction B to the downstream side, and the cleaning brush 45b rubs the reading glass 215 in conjunction with the rotation.

  The position of the knocking member 46 is fixed, and the foreign matter captured by the cleaning brush 45b is scraped off after the cleaning brush 45b rubs on the reading glass 215.

  As shown in FIG. 5A, the cleaning member 45 stands by with the cleaning brush 45b facing upward (in the direction opposite to the surface of the reading glass 215 through which the document 103 passes) as the home position. The home position is detected by the home position sensor 236. When the cleaning operation by the cleaning unit 202 is started, the cleaning member 45 starts normal rotation in the arrow c direction from the home position to the downstream side in the document transport direction B. Thereafter, the tip of the brush 45b rubs the surface of the reading glass 215 (see FIGS. 5B and 5C), captures foreign matter on the reading glass 215, and removes the foreign matter from the reading position 211. Thereafter, the cleaning brush 45b comes into contact with the hammering member 46, and the cleaning member 45 rotates once, and as a result, the position of the cleaning member 45 returns to the home position.

  The captured foreign matter is knocked out of the cleaning brush 45 b by the hammering member 46, is caught in the original 103 conveyed on the reading glass 215, and is discharged to the outside of the image reading apparatus 100. As a result, the surface of the reading glass 215 (particularly the reading position 211) and the brush 45b are always kept clean, and foreign matter collected from the reading glass 215 by the cleaning brush 45b is reattached to the reading glass 40. However, it is possible to prevent streak noise from occurring in the read image.

  Cleaning of the reading glass 215 by the cleaning member 45, that is, normal rotation of the cleaning member 45 at the reading position 211 is performed at a timing at which the cleaning brush 45 b does not interfere (compete) with the document 103 conveyed at the reading position 211. In the present embodiment, as will be described below, basically, after the document 103 transported in advance passes through the reading position 211, the document 103 transported to the next position is supplied to the reading position 211. Until the cleaning member 45 is rotated forward once.

  When the cleaning member 45 is always driven to rotate forward in one direction to clean the reading glass 211, the tip of the cleaning brush 45b may be deformed in a rotational direction due to long-term use, and the cleaning function may be deteriorated. is there. In order to correct this deformation, the cleaning member 45 may be reversed at an arbitrary timing. As a result of this reverse rotation, the cleaning brush 45b rubs the striking member 46 and the reading glass 215 in the reverse direction, receives a force in the reverse direction to the normal rotation, and corrects the deformation. As a result, a good cleaning function is maintained for a long period of time for the cleaning brush 45b.

  Next, driving of the cleaning member 45 will be described with reference to FIG. The sprocket 31 fixed to one end of the shaft member 45 a is connected to the output sprocket 32 of the cleaning motor 234 via the timing belt 33. The cleaning motor 234 is a stepping motor that can rotate forward and backward.

  Further, an arc-shaped protruding piece 35 is attached to the sprocket 31 and a home position sensor 236 for detecting the protruding piece 35 is disposed. When the home position sensor 236 detects the end 35a of the protruding piece 35, it is detected that the cleaning member 45, that is, the cleaning brush 45b is located at the home position (see FIG. 6).

(Control unit of image reading apparatus)
The configuration of the control unit of the image reading apparatus 100 will be described with reference to FIG. The control unit 59 corresponds to a CPU, and this CPU corresponds to the CPUs 300 and 313 shown in FIG. The control unit 59 has a timer 60 for measuring time, a ROM (Read Only Memory) 61 storing program data, a RAM (Random Access Memory) 62, a memory 63, and a key switch, which are operated by the user. An operation unit 64 for inputting information is connected.

  Information input to the control unit 59 includes a reading mode RM selected by the user by operating the operation unit 64 (details will be described later), and a sheet passing sensor 217 arranged on the upstream side in the transport direction with respect to the reading position 211 (FIG. 1). For example, a detection signal from the home position sensor 236 of the cleaning member 45, a detection signal from the size detection unit 104, and time data counted by the timer 60.

  Further, the control unit 59 performs control via a corresponding motor driving IC such as a document conveying system 101 such as various rollers and a cleaning motor 234.

  The control unit 59 detects the size of the document 103 being conveyed (hereinafter referred to as an actual document size SZ1) based on the detection of the timing detection unit 70 that detects the cleaning timing of the reading glass 215 by the cleaning unit 202 and the paper passing sensor 217. An actual document size detection unit 73 that performs scanning, a reading document size detection unit 74 that detects a size to be read when the document 103 passing through the reading position 211 is read by the exposure unit 206 and the CCD 209 (hereinafter referred to as a reading document size SZ2), and cleaning. A cleaning motor control unit 76 for controlling the motor 234, a reading timing detection unit 79 for detecting the timing at which the reading unit 102 starts reading the document 103, and a conveyance system control unit 80 for controlling the document conveyance system 101 are included. . Some of these units are realized by program data. These program data are stored in advance in the ROM 61, and the functions of these units are realized when the CPU reads the program data from the ROM 61 and executes it.

(Original size)
Referring to FIG. 8, document 103 has a rectangular shape, and the long side length corresponds to actual document size SZ1. In the present embodiment, the direction in which the long side extends coincides with the conveyance direction B when the document 103 passes through the surface of the reading glass 215. During document conveyance, the downstream side of the short side in the conveyance direction B is the leading end 1031, and the upstream side is the trailing end 1032. When the original 103 is conveyed and supplied to the reading glass 215, the paper passing sensor 217 detects a period during which the long side of the original 103 passes. The length of the long side of the document 103 is calculated based on the detected period (time) and the predetermined conveyance speed of the document 103. As a result, the actual document size SZ1 is detected for each of the conveyed documents 103.

  The read original size SZ2 indicates the length of the long side of a prescribed size paper (A5, B5, A4, B4, A3, etc.) according to JIS (Japanese Industrial Standard) dimensions. An image read from a document is printed on a sheet of the specified size by an output unit (not shown).

  In the present embodiment, the read document size SZ2 is detected by the read document size detection unit 74. The read document size detection unit 74 is based on the read mode RM by the mode detection unit, the size of the document 103 detected by the size detection unit 104, the size obtained by rounding the detected actual document size SZ1, and the operation unit 64 by the user. One of the sizes designated by operating is detected as the read document size SZ2. The detected read document size SZ2 is stored in the RAM 62.

  In the present embodiment, the value of the actual document size SZ1 is rounded, in the present embodiment, a value that is equal to or larger than the actual document size SZ1 and that is closest to the actual document size SZ1 among the prescribed sizes according to the JIS dimensions. It is detected as size SZ2.

  Therefore, in this embodiment, when the original 103 is conveyed and the image of the original 103 is read by the reading unit 102, the original reading size SZ2 is smaller than the actual original size SZ1 or larger than the actual original size SZ1. There is.

(Detection of timing to start reading the document)
The timing at which the reading unit 102 starts to read the image of the original 103 passing at the reading position 211 is detected by the reading timing detection unit 79 and output to the reading unit 102.

  Specifically, when the reading timing detection unit 79 detects that the leading edge 1031 of the document 103 has passed the position of the sheet passing sensor 217 based on the detection signal of the sheet passing sensor 217, the reading timing detection unit 79 reads the position of the sheet passing sensor 217 and the reading position. Based on a predetermined distance from the position 211 and a predetermined conveyance speed of the original 103, the time required for the leading edge 1031 of the original 103 to reach the reading position 211 is detected. Based on the detected required time and the current time indicated by the timer 60, a time (time) T1 for starting reading of the original 103 is detected and stored in the RAM 62. The predetermined distance and the conveyance speed are stored in the ROM 61 in advance.

  The control unit 59 compares the time of the timer 60 with the time T1 of the RAM 62. Based on the comparison result, when the timer 60 counts the time T1, the reading unit 102 is instructed to start reading the document 103. In the reading unit 102, based on the instruction, the image of the original 103 is optically read at the reading position 211 by the exposure unit 206 and the CCD 209. Reading is continued for a predetermined time from the start of reading, and the reading is terminated after the predetermined time has elapsed. Thereafter, when the next reading start instruction is input, the reading operation is similarly performed on the original 103 conveyed to the next order.

  Here, the predetermined time during which the reading operation is continued after the reading is started is determined in advance based on the read document size SZ2.

(Detection of timing for starting cleaning unit 202)
With reference to FIG. 9A, the conveyance of the original 103 is started, and the provisional time detection unit 71 causes the trailing end 1032 of the original 103 to pass the paper passage sensor 217 based on the detection signal of the paper passage sensor 217. When the completion is detected, the trailing edge 1032 of the original 103 has passed through the position of the paper passing sensor 217 based on a predetermined distance from the position of the paper passing sensor 217 to the reading position 211 and a predetermined conveying speed of the original 103. After that, the time required to pass the reading position 211 (corresponding to the broken line arrow in the figure) is calculated. Then, based on the calculated required time and the current time of the timer 60, a time T2 for the trailing end 1032 to pass the reading position 211 is calculated. This is stored in the RAM 62 as the provisional time T2.

  Referring to FIG. 9B, the actual document size detection unit 73 indicates that the document 103 has passed through the sheet passing sensor 217 based on the detection signal of the sheet passing sensor 217 after the conveyance of the document 103 is started. When detected, the actual document size SZ1 is calculated from the time required for the document 103 to pass through the position of the sheet passing sensor 217 and a predetermined conveyance speed. The calculated actual document size SZ1 is stored in the RAM 62.

  As described above, when the actual document size SZ1 is detected, the read document size detection unit 74 detects the read document size SZ2 according to the reading mode RM detected by the mode detection unit 75. Details of the detection of the read document size SZ2 will be described later.

  Next, referring to FIG. 9C, the timing detection unit 70 compares the detected actual document size SZ1 with the read document size SZ2. Based on the comparison result, a time (time) for starting the cleaning unit 202 is detected. During the detected start-up time, the cleaning motor control unit 76 outputs a signal to the cleaning motor 234, so that the cleaning motor 234 rotates in response to the signal, and the roller 45 rotates forward from the home position in conjunction with the rotation. To start.

  When the comparison result indicates (read document size SZ2 ≦ actual document size SZ1), referring to FIG. 10A, the provisional time T2 read from the RAM 62 is used as the time for starting the cleaning unit 202 as it is. decide. When instructing (reading document size SZ2> actual document size SZ1), the provisional time read from the RAM 62 is corrected with reference to FIG. That is, the time (time) when the cleaning unit 202 should be activated is calculated by calculating the time to be added from the difference between the read original size SZ2 and the actual original size SZ1 and the conveyance speed and adding the calculated time to the provisional time T2. To decide.

  As described above, the time T1 for starting the reading of the image of the document 103 at the reading position 211 by the reading unit 102 and the time for starting the cleaning unit 202 are detected for each conveyed document 103 one by one.

(Processing flowchart)
The timing for starting the cleaning unit 202 when the document 103 is conveyed will be described with reference to the flow of FIG. This flow is stored in advance in the ROM 61 as a program, and the processing is realized by being read and executed by the CPU of the control unit 59. This process is executed each time the paper passing sensor 217 detects that the document 103 has passed, that is, every time the trailing edge 1032 is detected. Here, it is assumed that the reading start time T1 is detected and stored in the RAM 62 in advance.

  First, in step S <b> 101, the provisional time T <b> 2 is detected by the provisional time detection unit 71 as described above and stored in the RAM 62. Subsequently, in step S102, the actual document size detection unit 73 detects the actual document size SZ1 in accordance with the above-described procedure, and stores it in the RAM 62.

  Next, in steps S103 to S106, the read original size detection unit 74 detects the read original size SZ2 and stores it in the RAM 62. Specifically, the mode detection unit 75 is a mode for instructing the read document size SZ2 based on the reading mode RM input via the operation unit 64, that is, the “non-mixed mode”, the “mixed mode”, and the “user specified mode”. Which of 'is designated is detected (S103).

  The “non-mixed mode” is a mode for instructing that the originals 103 to be conveyed are the same size. When the mode is designated, the read document size detection unit 74 detects the read document size SZ2 of the document 103 based on the detection signal of the size detection unit 104 (S104).

  'Mixed loading mode' is a mode for instructing that the sizes of the conveyed originals 103 are not the same but different. When this mode is designated, the read document size detection unit 74 detects the read document size SZ2 by rounding the actual document size SZ1 read from the RAM 62 as described above (S105).

  'User designation mode' is a mode in which the user designates the read document size SZ2. When this mode is designated, the read document size detection unit 74 detects the size input by the user via the operation unit 64 as the read document size SZ2 (S106).

  Next, in step S107, the time determination unit 72 compares the actual document size SZ1 read from the RAM 62 with the read document size SZ2. If it is determined that the comparison result indicates (read document size SZ2> actual document size SZ1), the provisional time T2 read from the RAM 62 in steps S108 and S109 is determined from the difference between the read document size SZ2 and the actual document size SZ1 and the conveyance speed. Correction (change) is made by adding the calculated time. In step S111, the corrected time T2 is stored in the RAM 62, so that the corrected time (time) T2 is determined as the time for starting the cleaning unit 202.

  On the other hand, if it is determined that the comparison result indicates (read document size SZ2 ≦ actual document size SZ1), the time determination unit 72 determines the provisional time T2 as the time (time) for starting the cleaning unit 202 in step S110, In step S <b> 111, the determined time T <b> 2 is stored in the RAM 62, whereby the provisional time T <b> 2 is determined as the time for starting the cleaning unit 202.

  The cleaning motor control unit 76 compares the time of the timer 60 with the time T2 read from the RAM 62, and outputs a start signal to the cleaning motor 234 when detecting that the timer 60 indicates the time T2 based on the comparison result. To do. As a result, the cleaning motor 234 rotates and the roller 45 located at the home position rotates forward in conjunction with the rotation, and the surface of the reading glass 215 is rubbed.

  As described above, the reading unit 102 continuously performs the reading operation from the reading start time T1 to the time according to the read original size SZ2. However, the reading unit 102 cleans the original 103 while reading it regardless of the actual original size SZ1. It is possible to prevent the shadow of the cleaning brush 45b from being read as an image by being cleaned by the unit 202.

  That is, when the actual document size SZ1 of the document 103 to be read is smaller than the read document size SZ2, the timing for cleaning the reading glass 215 for the time according to the difference between the actual document size SZ1 and the read document size SZ2 (provisional time T2). Therefore, it is possible to avoid the shadow of the cleaning brush 45b being read as an image of the document 103 by the cleaning unit 202 cleaning the document 103 while the reading unit 102 is reading the document 103. When the actual document size SZ1 is equal to or larger than the read document size SZ2, the cleaning unit 202 performs cleaning when the reading unit 102 completes reading the document 103 (provisional time T2), and the cleaning brush It is not read as a 45b image.

(Timing chart)
The effect of the present embodiment will be described with reference to the timing chart of FIG. The horizontal axis of the timing chart indicates the elapsed time, and the vertical axis indicates the signal level.

  First, it is assumed that even when the read document size SZ2 is larger than the actual document size SZ1, the above-described provisional time T2 is not corrected. In that case, as shown in FIG. 12A, the reading operation of the original 103 by the reading unit 102 continues during the period from the time when the original 103 has passed through the reading position 211 (time ST2) to the time T3. Accordingly, the cleaning operation is started from the time ST3 when the document 103 has passed through the reading position 211, so that the shadow of the cleaning brush 45b is read together with the image of the document 103.

  In order to avoid this, the operation start of the cleaning unit 202 is delayed by a period Ta (time according to the difference between the actual document size SZ1 and the read document size SZ2) until the time when the reading operation is completed according to the flowchart of FIG. Good (see FIG. 12B).

  On the other hand, when the read original size SZ2 is equal to or larger than the actual original size SZ1, as shown in FIG. 12C, after the original 103 has passed through the reading position 211, in other words, the reading unit 102 has the original 103. The cleaning operation by the cleaning unit 202 is started after the completion of the reading, and the shadow of the cleaning brush 45b is not read.

  Here, the conveyance system control unit 80 delays the time for the original 103 conveyed to the next position to reach the reading position 211 by an amount corresponding to the corrected (added) time (period Ta). Transport. Specifically, a signal for lowering the conveyance speed by a speed corresponding to the period Ta is output to each motor in the document conveyance system 101. The corresponding speed data is stored in the ROM 61 in advance. A signal for controlling the rotation of the motor is generated and output in accordance with the read speed data.

  As a result, the number of rotations of the motor that has received the control signal is decreased, and the number of rotations of the pre-reading roller 213 of the transport system is decreased, and the time for the next original 103 to reach the reading position 211 is not corrected. This is delayed compared to the case (see the period Tb in FIGS. 12A and 12B). Therefore, even if the start of the cleaning operation of the cleaning unit 202 is delayed, it is possible to avoid reading the shadow of the brush 45b by the cleaning operation during the image reading period of the next original 103.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  59 control unit, 70 timing detection unit, 71 provisional time detection unit, 72 time determination unit, 73 actual document size detection unit, 74 reading document size detection unit, 75 mode detection unit, 76 cleaning motor control unit, 79 transport system control unit , 80 Conveyance system control unit, 100 image reading device, 101 ADF unit, 102 reading unit, 202 cleaning unit, 209 image input unit (CCD), 210 image processing unit, 211 reading position, 217 sheet passing sensor, SZ1 actual document size , SZ2 Scanned document size.

Claims (10)

A plate-like transparent member provided at a predetermined reading position in the document conveyance path;
By irradiating light from the other surface side of the transparent member through the transparent member to the document passing through the reading position on the one surface of the transparent member, the document is optically optically according to a predetermined reading size. A reading unit for reading;
A control unit that controls a cleaning operation of rubbing the one surface of the transparent member with a cleaning member prepared in advance,
The controller is
An actual size detector for detecting the actual size of the document passing on one side of the transparent member;
The time for starting the cleaning operation is determined as the time when the document passes through the reading position when the reading size ≦ the actual size, and when the reading size> the actual size, the reading unit. An image reading apparatus including a cleaning time determination unit that determines a time for completing the reading of the document according to the reading size. The controller is
When the document has passed through the first position on the upstream side of the reading position in the transport path, a time for completing the passage through the reading position is determined based on the transport speed and the distance between the first position and the reading position. The image reading apparatus according to claim 1, wherein the image reading apparatus is detected. The controller is
The time for completing the reading is detected by adding the time calculated based on the difference between the reading size and the actual size and the conveyance speed to the time for completing the passage through the reading position. Image reading apparatus. A document transport unit that transports the documents one by one along the transport path so as to pass the document through the reading position;
The image reading unit according to claim 3, wherein the document transport unit transports the document so as to delay a time for the document transported to the next position to reach the reading position by an amount corresponding to the added time. apparatus. The controller is
The image reading apparatus according to claim 1, further comprising a reading size detection unit that detects the reading size in accordance with a mode input from the outside.   The image reading apparatus according to claim 5, wherein when the mode indicates a mixed loading mode in which a size differs for each conveyed document, the reading size detection unit detects the reading size based on the actual size. A document size detection unit that detects the size of a document placed in advance so as to be fed to the conveyance path;
The reading size detection unit detects the reading size based on a size detected by the document size detection unit when the mode indicates a non-mixed mode in which the sizes of documents to be conveyed are the same. The image reading apparatus according to 5 or 6.   The image reading apparatus according to claim 5, wherein when the mode indicates a user designation mode, the reading size detection unit detects the reading size based on a size input from the outside.   The image reading apparatus according to claim 1, wherein the reading size indicates a specified size of a sheet on which a read document is to be printed. By irradiating light from the other side of the original passing through one side of the plate-like transparent member provided at a predetermined reading position for reading the original through the transparent member, the original is predetermined. Optically reading according to the reading size of
A step of controlling a cleaning operation by a cleaning member that rubs and cleans the one surface of the transparent member, and
In the controlling step,
Detecting the actual size of the document passing through the reading position;
The time for starting the cleaning operation is determined to be a time when the document passes through the reading position when the reading size ≦ the actual size, and when the reading size> the actual size, the reading size is determined. And determining the time to complete the reading of the original according to the method.

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