JP6341241B2 - Image processing device - Google Patents

Description

  The technology disclosed in this specification relates to a technology used in an image reading apparatus that switches a conveyance path and conveys and reads a document.

  2. Description of the Related Art Conventionally, there has been known an image reading apparatus that has a plurality of conveyance paths and conveys and reads a document by switching the conveyance path for each document (for example, Patent Document 1). In this apparatus, a technique is disclosed in which the thickness of a document is determined during transport, and the transport path for transporting the document is switched according to the determined thickness of the document.

Japanese Patent Laid-Open No. 11-127301

  In an image reading apparatus having a plurality of conveyance paths, it may be necessary to perform different correction processes on the reading results obtained by reading a document conveyed on each conveyance path. For example, when the type of document conveyed by each conveyance path is determined, due to the difference in document type, the document conveyed by one conveyance path is more accurate than the document conveyed by the other conveyance path. It may be necessary to correct the reading result. In addition, due to the difference in the shape of each conveyance path, there is a slight difference in the conveyance speed of the document conveyed on each conveyance path, and it is necessary to correct the document conveyed on at least one of the conveyance paths. There are cases. However, in the prior art, sufficient consideration has not been given to the correction processing for the reading results read using different conveyance paths.

  The invention disclosed in this specification relates to a technique for correcting a reading result in accordance with a conveyance path in an image reading apparatus that conveys and reads a document by switching the conveyance path.

An image reading apparatus disclosed in this specification includes a placement unit on which a document is placed, and transports the document placed on the placement unit in one of a first transport path and a second transport path. A conveyance unit that conveys along the path, and a reading unit that is provided on a common conveyance path of the first conveyance path and the second conveyance path, and reads an image of the document conveyed by the conveyance unit in the main scanning direction. And a control unit, wherein the control unit sets a conveyance path of a document conveyed by the conveyance unit to one of the first conveyance path and the second conveyance path; When the reading unit reads the document image of the conveyed document by the reading unit and the setting process sets the first conveyance path, the document image read by the reading process is main in the main scanning direction. How to scan Based on the document width, to estimate the sub-scanning direction length in the sub scanning direction of the document, the first sub-scan magnification sub-scanning direction document width in the sub-scanning direction of the document image becomes equal to the sub-scanning direction length A determination process for determining, a first correction process for correcting the document image at the first sub-scanning magnification determined by the determination process when the first conveyance path is set by the setting process, and the setting When the second conveyance path is set by the processing, the number of unit reading images acquired is increased or decreased based on a predetermined correction constant, thereby enlarging / reducing in the sub-scanning direction when reading a document. And performing a second correction process.

  In this image reading apparatus, a first transport path and a second transport path for transporting a document are provided, and the document is transported along one of the transport paths. Then, the reading result obtained by reading the document conveyed along the conveyance path is corrected by switching the sub-scanning magnification according to the conveyance path. According to this image reading apparatus, an individual sub-scanning magnification can be set for each conveyance path according to individual differences in the conveyance path such as the shape of each conveyance path and the type of document conveyed to each conveyance path. Different correction processes can be executed on the reading results obtained by reading the document conveyed by each conveyance path.

Further , according to this image reading apparatus, it is possible to determine the sub-scanning magnification for a document transported along the first transport path in accordance with a reading result actually read using the document .

Further , according to this image reading apparatus, with respect to the document conveyed along the first conveyance path, the document width in the sub-scanning direction in the sub-scanning direction is highly accurate so as to be equal to the length of the document in the sub-scanning direction. The corrected reading result can be acquired.

Further , according to this image reading apparatus, with respect to the document conveyed along the first conveyance path, the document width in the sub-scanning direction in the sub-scanning direction is highly accurate so as to be equal to the length of the document in the sub-scanning direction. The corrected reading result can be acquired.

  In the image reading apparatus disclosed in this specification, the reading result can be corrected in accordance with the conveyance path in the image reading apparatus that conveys and reads the document by switching the conveyance path.

Schematic sectional view of an image reading device Block diagram schematically showing the electrical configuration of the image reading apparatus 6 is a flowchart illustrating a reading process according to the first embodiment. Flow chart showing pre-correction reading processing Flow chart showing enlargement / reduction processing Flow chart showing reading correction processing Diagram showing original and scanned image 7 is a flowchart illustrating reading processing according to the second embodiment.

<Embodiment 1>
The first embodiment will be described with reference to FIGS.

1. As shown in FIG. 1, the image reading apparatus 1 transports a plurality of documents G placed on a paper feed tray 2 by a user to paper discharge trays 4A and 4B, This is a sheet feed scanner that reads the original G using the CIS 30 included in the main body 3. The paper feed tray 2 is an example of a placement unit.

  The main body 3 of the image reading apparatus 1 is provided with a conveyance path 22 that connects the paper feed tray 2 and the paper discharge tray 4. A paper feed roller 40, a separation pad 42, and the periphery of the conveyance path 22 are provided. , A transport roller 44, a CIS 30, a front sensor (hereinafter referred to as F sensor) 13, a rear sensor (hereinafter referred to as R sensor) 14, a paper discharge roller 46, a turning plate 48, and a tray plate 50. The CIS 30 is an example of a reading unit, and the tray plate 50 is an example of a switching unit.

  The paper feed roller 40 abuts on the original G placed on the paper feed tray 2 and draws the original G placed on the paper feed tray 2 into the main body 3 by a frictional force. At this time, the document G is separated for each document G by the frictional force of the separation pad 42 and sent out to the conveyance path 22.

  The conveyance roller 44 is driven by a motor M (see FIG. 2) and conveys the original G drawn into the main body 3 along the conveyance path 22. The CIS 30 is arranged at the reading position L1 on the conveyance path 22 with the main scanning direction D1 orthogonal to the conveyance direction D2 along the conveyance path 22, and reads the document G passing through the reading position L1 in the main scanning direction D1. .

  The paper discharge roller 46 is driven by the motor M in the same manner as the transport roller 44, and sends the document G transported on the transport path 22 to the paper discharge tray 4. A direction change plate 48 is arranged at a position facing the paper discharge roller 46 across the conveyance path 22. The diverting plate 48 is controlled by the diverting unit 19 (see FIG. 2), and the first posture F1 along the first transport path 22A continuing to the paper discharge tray 4A and the second post continuing to the paper discharge tray 4B. The second posture F2 along the second transport path 22B is controlled to be one of the postures.

  A tray plate 50 is disposed on the first transport path 22A at a position where the first transport path 22A intersects the main body 3. The state of the tray plate 50 is detected by the state sensor 10 (see FIG. 2), and the tray plate 50 is switched between the open state F3 and the closed state F4. The tray plate 50 constitutes the paper discharge tray 4A by being in the open state F3, and forms a state in which the original G is transported along the first transport path 22A. Further, the closed state F4 blocks the first transport path 22A, and forms a state in which the document G is transported along the second transport path 22B instead of the first transport path 22A. The open state F3 is an example of a conveyance state, and the closed state F4 is an example of a blocking state.

  The first transport path 22A and the second transport path 22B are common in the range from the paper feed tray 2 to the paper discharge roller 46. That is, the first transport path 22A and the second transport path 22B have a common reading position L1 and a common detection position L2, which will be described later.

  On the other hand, the first transport path 22A and the second transport path 22B are different in the range from the discharge roller 46 to the discharge trays 4A and 4B. In this range, the first transport path 22 </ b> A is provided in a substantially linear shape, and a part of the second transport path 22 </ b> B is provided in a curved shape along the paper discharge roller 46. That is, in the second transport path 22B, the curvature radius is smaller in the curved portion X along the paper discharge roller 46 than in the first transport path 22A. The curved portion X is an example of a curved portion.

  For this reason, when the first conveying path 22A passes through the curved portion X such as the original G thicker than the reference thickness or the original G smaller than the reference original size, a jam or a decrease in the conveyance speed occurs. It is used for conveying the original G that is not suitable for conveyance in the curved portion X. On the other hand, the second transport path 22B does not cause a jam or a decrease in transport speed even when the curved portion X such as the document G thinner than the reference thickness or the document G larger than the reference document size is passed. It is used for transporting a document G that can be transported in the curved portion X.

  Here, the reference thickness and the reference document size are determined based on the shapes of the first transport path 22A and the second transport path 22B. In the present embodiment, business cards and postcards are classified as a document G that is thicker than the reference thickness and smaller than the reference document size, and A4 plain paper and B5 plain paper are thinner than the reference thickness and larger than the reference document size. Is classified as an original document G.

  When the tray plate 50 is in the open state F3 indicated by the solid line in FIG. 1, the direction change plate 48 is controlled to the first posture F1 indicated by the solid line in FIG. 1, and the document G is conveyed along the first conveyance path 22A. . Then, the document G is placed on the paper discharge tray 4A constituted by the tray plate 50 in the opened state.

  On the other hand, when the tray plate 50 is in the closed state F4 indicated by the dotted line in FIG. 1, the direction changing plate 48 is controlled to the second posture F2 indicated by the dotted line in FIG. 1, and the document G is conveyed along the second conveyance path 22B. Then, the paper is discharged to the paper discharge tray 4B. That is, a plurality of originals G placed on the paper feed tray 2 are fed by one of the first transport path 22A and the second transport path 22B by the paper feed roller 40, the transport roller 44, and the paper discharge roller 46. The conveyance part 15 conveyed along is formed.

  The F sensor 13 is disposed in the paper feed tray 2 and is turned on when the original G is placed on the paper feed tray 2, and is turned off when the original G is not placed on the paper feed tray 2. That is, the F sensor 13 detects whether or not the document G is present in the paper feed tray 2. The R sensor 14 is disposed at a detection position L2 upstream of the reading position L1 in the conveyance path 22, and is turned on when the document G passes the detection position L2 on the conveyance path 22, and the document G passes the detection position L2. Turn off when not passing.

  Furthermore, the image reading apparatus 1 includes an input unit 11 that includes various buttons and receives an operation input from a user, and a display unit 12 that includes a liquid crystal display that displays the state of the image reading apparatus 1 (FIG. 2). reference).

2. As shown in FIG. 2, the image reading apparatus 1 includes a central processing unit (hereinafter referred to as “CPU”) 20, a ROM 26, a RAM 27, an image processing unit 28, a device control unit 16, an analog front end (hereinafter referred to as “CPU”). AFE) 17, a drive circuit 18, and a turning unit 19, to which a state sensor 10, an input unit 11, a display unit 12, an F sensor 13, an R sensor 14, and the like are connected via a bus 29. . As indicated by a dotted line 21 in FIG. 3, the CPU 20, the ROM 26, the RAM 27, and the image processing unit 28 are examples of a control unit, and the ROM 26 and the RAM 27 are examples of a storage unit.

  The ROM 26 stores various programs for controlling the operation of the image reading apparatus 1, and the CPU 20 controls each unit according to the program read from the ROM 26. In addition, the ROM 26 stores a reference reading number NK and a correction constant TH. The reference reading number NK is a reference reading number in the main scanning direction D1 of the CIS 30 determined for each size of the document G. The correction constant TH is a correction constant determined based on the configuration of the transport unit 15 and the shape of the transport path 22.

  The device control unit 16 is connected to the CIS 30 and transmits a read control signal to the CIS 30 based on a command from the CPU 20. The CIS 30 reads the document G based on the reading control signal from the device control unit 16. The correction constant TH is an example of a second sub-scanning magnification.

  The CIS 30 repeats reading a plurality of times in the main scanning direction D1 with respect to the document G conveyed on the reading position L1 of the conveyance path 22. As shown in FIG. 7, the CIS 30 acquires the unit read image TG by one reading in the main scanning direction D1. The unit read image TG corresponds to a read image obtained by reading the specified range KH of the document G having the specified width KW in the transport direction D2. The CIS 30 repeats reading in the main scanning direction D1, thereby reading a reading image YG in which a plurality of unit reading images TG are gathered in the sub-scanning direction D3 orthogonal to the main scanning direction D1, and reading the reading image YG to the AFE 17 Output. The read image YG is an example of a read result.

  The AFE 17 is connected to the CIS 30 and converts an analog signal read image YG output from the CIS 30 into a digital signal, that is, a gray scale data read image YG, based on a command from the CPU 20. The AFE 17 stores the converted gradation data in the RAM 27 via the bus 29.

  The image processing unit 28 performs edge extraction processing such as binarization processing and enhancement processing on the read image YG stored in the RAM 27. Further, the image processing unit 28 performs correction processing for correcting the magnification in the sub-scanning direction D3 of the read image YG stored in the RAM 27 (see an arrow 54 in FIG. 7). When enlarging the magnification in the sub-scanning direction D3, the image processing unit 28 creates a new unit read image between the unit read images TG by linear interpolation or the like from the unit read image TG read by the CIS 30 and the unit read image TG. TG is generated. Further, when reducing the magnification in the sub-scanning direction D3, a part of the unit read image TG read by the CIS 30 is deleted. The read image YG processed by the image processing unit 28 is stored in the RAM 27 again.

The drive circuit 18 is connected to the motor M. The motor M is well-known and includes a rotor (not shown) fixed to a rotating shaft and a stator (not shown) attached to the outside thereof. The drive circuit 18 for driving the motor M can rotate the rotor accurately in a certain angle unit by sequentially applying current corresponding to the excitation phase to the coils wound around the stator. The excitation phase is a phase indicating how the drive circuit 18 supplies current to the coil of the motor M. The rotational position (rotor position) of the stepping motor is determined according to the excitation phase.
A clock signal is input to the drive circuit 18 in accordance with an instruction from the CPU 20. Then, the drive circuit 18 updates the signal indicating the excitation phase for each pulse of the clock signal, and supplies the current to the coil based on the signal, thereby rotating the motor M step by step. The motor M is driven to rotate by one rotation angle with one pulse of the pulse signal. When the motor M is driven by one step, the transport roller 44 and the paper discharge roller 46 are driven, and the original G is transported on the transport path 22 by a predetermined distance. When the CPU 20 transports the document G, the CPU 20 transmits a pulse signal to the drive circuit 18, and the transport unit 15 transports the document G by a distance obtained by multiplying the number of pulses of the pulse signal by a specified distance. Hereinafter, the number of pulses of the pulse signal that the CPU 20 transmits to the drive circuit 18 is referred to as a step number.

3. Reading Process Next, the reading process of the original G in the image reading apparatus 1 will be described with reference to FIGS. FIG. 3 shows a flowchart of a reading process executed by the CPU 11 according to a predetermined program. The CPU 11 starts processing when it is confirmed that the document G is placed on the paper feed tray 2 using the F sensor 13, and when an instruction to read the document G is input from the user via the input unit 11. .

  When the reading process is started, the CPU 20 executes a setting process for setting the conveyance path 22 prior to conveyance of the original G (S2 to S6). In the setting process, the CPU 20 checks the state of the tray plate 50 using the state sensor 10 (S2). When the tray plate 50 is in the open state (S2: YES), the CPU 20 uses the turning portion 19 to move the turning plate 48 in the first posture F1 in order to transport the document G along the first transport path 22A. Switch to. Further, the CPU 20 turns on a first flag indicating that the document G is transported along the first transport path 22A (S4).

On the other hand, when the tray plate 50 is in the closed state (S2: NO), the direction change plate 48 is switched to the second posture F2 in order to convey the document G along the second conveyance path 22B. Further, the CPU 20 turns on a second flag indicating that the document G is transported along the second transport path 22B (S6).

  When the setting process is completed, the CPU 20 starts conveying the document G along the conveyance path 22 set by using the drive circuit 18 and the motor M (S8) and counts the number of steps. Further, the CPU 20 sets the reading number N indicating the number of readings in the main scanning direction D1 to zero (S10). The CPU 20 detects the position of the document G being conveyed using the R sensor 14 (S12: NO), and when the R sensor 14 is turned on (S12: YES), the CPU 20 detects the position of the document G at the detection position L2 on the conveyance path 22. It is detected that the front end in the transport direction D2 has arrived, and reading processing and correction processing are started (S16 to S20).

  When starting the reading process and the correction process, the CPU 20 checks whether either the first flag or the second flag is on (S14). When the first flag is on (S14: YES), the CPU 20 executes the pre-correction reading process (S16) and the enlargement / reduction process (S18). If the second flag is on (S14: NO), a reading correction process (S20) is executed. That is, the CPU 20 switches and executes the correction process depending on which flag is turned on. The enlargement / reduction process is an example of a first correction process, and the reading correction process is an example of a second correction process.

(Reading process before correction)
When the first flag is on and the document G is transported along the first transport path 22A, the CPU 20 executes a pre-correction reading process (S16). FIG. 4 shows a flowchart of the pre-correction reading process. In the pre-correction reading process, after the R sensor 14 is turned on, the CPU 20 waits until the first step number ST1 corresponding to the distance from the detection position L2 of the conveyance path 22 to the reading position L1 is counted (S32: NO). . Then, the CPU 20 counts the first step number ST1 (S32: YES), and executes reading once in the main scanning direction D1 when the leading end of the document G in the transport direction D2 reaches the reading position L1 (S34). ), 1 is added to the reading number N (S36).

  Next, the CPU 20 checks the reading number N (S38), and when the reading number N is 1 (S38: YES), that is, when the first unit reading image TG is read in the pre-correction reading process, the image Edge extraction processing is executed on the first unit read image TG using the processing unit 28 (S40). The CPU 20 estimates the main scanning direction length LS (see FIG. 7), which is the length of the document G in the main scanning direction D1, using the first unit read image TG subjected to the edge extraction processing (S42). The CPU 20 estimates the main scanning direction data length DS that is the length in the main scanning direction D1 of the unit read image TG using the first unit read image TG subjected to the edge extraction processing, and this main scanning direction data length. DS is estimated as the main scanning direction length LS. The CPU 20 stores the main scanning direction length LS in the RAM 27 and repeats the processing from S34.

  On the other hand, when the reading number N is 2 or more (S38: NO), the CPU 20 uses the R sensor 14 to detect the position of the document G being conveyed (S44). When the R sensor 14 is on and the trailing end of the document G in the transport direction D2 has not reached the detection position L2 on the transport path 22 (S44: NO), the CPU 20 repeats the processing from S34.

  Further, the CPU 20 has not counted the first step number ST1 after the R sensor 14 is turned on even though the R sensor 14 is turned off and the trailing end of the conveyance direction D2 of the document G has reached the detection position L2. Even when the trailing end of the document G in the conveyance direction D2 has not reached the reading position L1 (S44: NO), the processing from S34 is repeated.

  On the other hand, the CPU 20 counts the first step number ST1 after the R sensor 14 is turned on, and when the rear end of the document G in the conveyance direction D2 reaches the reading position L1 on the conveyance path 22 (S44: YES). Then, the reading of the document G is completed, the reading number N when the first step number ST1 is counted is stored in the RAM 27 as the reading line number NL (S46), and the pre-correction reading process is ended.

(Enlargement / reduction processing)
The CPU 20 ends the pre-correction reading process, and executes the enlargement / reduction process after the reading of the read image YG is completed. In the enlargement / reduction process, a correction process for enlarging or reducing the read image YG acquired in the pre-correction read process in the sub-scanning direction D3 is executed. FIG. 5 shows a flowchart of the enlargement / reduction process. In the enlargement / reduction process, the CPU 20 first estimates the sub-scanning direction length LH (see FIG. 7), which is the length of the original G in the sub-scanning direction D3 (S52).

  In the estimation of the sub-scanning direction length LH, the CPU 20 estimates the size of the original G from the main scanning direction length LS calculated in the pre-correction reading process, and uses the reference reading number NK stored in the ROM 26 in association with the size. elect. The CPU 20 estimates the reference reading number NK, thereby estimating the sub-scanning direction length LH as a value obtained by multiplying the reference reading number NK by the specified width KW.

Next, the CPU 20 determines a sub-scanning magnification BH that is a magnification for enlarging or reducing the read image YG in the sub-scanning direction D3 (S54). In determining the sub-scanning magnification BH, the CPU 20 reads the number of reading lines NL stored in the RAM 27 and divides the estimated reference reading number NK by the number of reading lines NL to determine the sub-scanning magnification BH. The sub scanning magnification BH is an example of a first sub scanning magnification.
BH = NK / NL

  The CPU 20 corrects the read image YG using the determined sub-scanning magnification BH (S56). When the sub-scan magnification BH is smaller than 1, the CPU 20 generates a new unit reading image TG from the unit reading image TG included in the reading image YG, and the number of unit reading images TG included in the reading image YG is the reference reading. Correction is made to be equal to the number NK. At this time, the CPU 20 generates a new unit read image TG for each predetermined number of unit read images TG based on the sub-scanning magnification BH.

  When the sub-scan magnification BH is larger than 1, the CPU 20 deletes a part of the unit read image TG included in the read image YG, and the number of unit read images TG included in the read image YG is the reference read number NK. (See arrow 54 in FIG. 7). At this time, the CPU 20 deletes the unit read image TG for each predetermined number of unit read images TG based on the sub-scanning magnification BH.

  The CPU 20 corrects the read image YG using the sub-scanning magnification BH. Accordingly, the error indicated by the arrow 56 in FIG. 7 is corrected, and the sub-scanning direction data length DH as the value obtained by multiplying the number of unit read images TG included in the read image YG by the specified width KW is set to the sub-scanning direction length LH. Correct to be equal.

(Reading correction process)
On the other hand, when the second flag is on and the document G is transported along the second transport path 22B, the CPU 20 executes the pre-correction reading process. FIG. 6 shows a flowchart of the reading correction process. In the present embodiment, a description will be given of a case where the magnification in the sub-scanning direction D3 of the read image YG is reduced as the read correction process. In the reading correction process, the CPU 20 reads a correction constant TH stored in advance in the ROM 26 (S62). Further, the CPU 20 sets the scheduled number Y indicating the scheduled number of readings in the main scanning direction D1 to zero (S64).

  After the R sensor 14 is turned on, the CPU 20 stands by until the first step number ST1 is counted (S66: NO). Then, the CPU 20 counts the first step number ST1 (S66: YES), and adds 1 to the expected number Y when the leading end of the document G in the transport direction D2 reaches the reading position L1 on the transport path 22 ( In S68, it is confirmed whether the planned number Y is a multiple of the correction constant TH (S70). When the planned number Y is not a multiple of the correction constant TH (S70: NO), the CPU 20 executes reading once in the main scanning direction D1 (S72).

  On the other hand, when the planned number Y is a multiple of the correction constant TH (S70: YES), the CPU 20 does not perform reading in the main scanning direction D1. The CPU 20 does not perform reading in a predetermined case, thereby reducing the acquired unit read image TG and reducing the magnification of the read image YG in the sub-scanning direction D3. The CPU 20 does not execute the reading in the main scanning direction D1 when the planned number Y is a multiple of the correction constant TH, so that the magnification of the read image YG in the sub-scanning direction D3 based on the correction constant TH stored in the ROM 26 in advance. Reduce.

  The CPU 20 detects the position of the document G being conveyed using the R sensor 14, and after the R sensor 14 is turned off and the R sensor 14 is turned off, the first step number ST1 is counted (S74: NO). That is, the processing from S68 is repeated until the trailing end of the document G in the conveyance direction D2 reaches the reading position L1. Then, the CPU 20 counts the first step number ST1 after the R sensor 14 is turned off (S74: YES), and when the trailing end of the document G in the transport direction D2 reaches the reading position L1 on the transport path 22. Then, the reading of the original G is completed, and the reading correction process is ended.

  When the CPU 20 finishes the enlargement / reduction process or the reading correction process, the CPU 20 returns to the reading process shown in FIG. When the CPU 20 counts the second step number ST corresponding to the distance from the reading position L1 of the transport path 22 to each of the paper discharge trays 4, the CPU 20 stops the transport of the original G (S22) and ends the reading process.

4). Advantages of the present embodiment (1) In the image reading apparatus 1 of the present embodiment, the document G is transported along the transport path 22, and the scanned image YG read from the transported document G is scanned in the sub-scanning direction D3. A process for correcting the magnification is executed. At that time, when the document G is transported along the first transport path 22A, the magnification in the sub-scanning direction D3 is corrected based on the sub-scan magnification BH, and the document G is transported along the second transport path 22B. If so, the magnification in the sub-scanning direction D3 is corrected based on the correction constant TH. In other words, in the image reading apparatus 1, correction processing can be executed by switching the reference value of the magnification in the sub-scanning direction D <b> 3 according to the conveyance path 22 through which the document G is conveyed. Different correction processes can be performed on the read image YG obtained by reading the original G.

(2) In the image reading apparatus 1 of the present embodiment, for the read image YG of the original G conveyed along the first conveyance path 22A, the sub-scan magnification BH is set based on the read image YG that has been read. decide. Specifically, the sub-scanning direction data length DH of the read image YG is equal to the sub-scanning direction length LH of the original G, that is, the number of unit read images TG included in the read image YG is equal to the reference read number NK. Thus, the sub-scanning magnification BH is determined, and the read image YG is corrected based on the sub-scanning magnification BH. Therefore, it is possible to obtain a read image YG in which the magnification in the sub-scanning direction D3 is corrected with high accuracy with respect to the document G transported along the first transport path 22A.

(3) In the image reading apparatus 1 of the present embodiment, the read image YG of the original G conveyed along the second conveyance path 22B is based on the correction constant TH stored in the ROM 26 in advance. While the original G is being read, the read image YG is corrected. Therefore, when the reading of the read image YG is completed, the correction of the read image YG can be completed, and the time from the start of reading the original G to the completion of correction of the read image YG can be shortened.

(4) In the image reading apparatus 1 of the present embodiment, when the document G is transported along the first transport path 22A, the unit reading acquired by the first scanning of the document G in the main scanning direction D1. Since the main scanning direction length LS of the document G is estimated from the image TG, the reference reading number NK can be selected at an early stage, whereby the sub scanning direction length LH can be estimated at an early stage.

(5) In the image reading apparatus 1 of the present embodiment, a relatively thick original G such as a business card or a postcard is conveyed by the first conveyance path 22A, and the magnification in the sub-scanning direction D3 of the read image YG using the sub-scan magnification BH. Correct. A relatively thick document G has a larger torque of the transport roller 44 and the like necessary for transport than a relatively thin document G, and the transport speed tends to be slower than a relatively thin document G. Therefore, when the magnification in the sub-scanning direction D3 is corrected using the correction constant TH determined based on the reference transport speed, the read image YG may not be corrected with high accuracy. In the image reading apparatus 1, a relatively thick original G is conveyed by the first conveyance path 22A, and the magnification in the sub-scanning direction D3 of the read image YG is corrected using the sub-scan magnification BH determined from the read image YG. The read image YG of the relatively thick original G can be corrected with high accuracy.

(6) In the image reading apparatus 1 of the present embodiment, a relatively small document G such as a business card or a postcard is conveyed by the first conveyance path 22A, and the sub-scanning magnification BH is used in the sub-scanning direction D3 of the read image YG. Correct the magnification. A relatively small document G is less likely to transmit torque from the transport roller 44 to the document G than a relatively large document G, and the transport speed is likely to be slower than a relatively large document G. Therefore, when the magnification in the sub-scanning direction D3 is corrected using the correction constant TH determined based on the reference transport speed, the read image YG may not be corrected with high accuracy. In this image reading apparatus 1, a relatively small document G is conveyed by the first conveyance path 22A, and the magnification in the sub-scanning direction D3 of the read image YG is corrected using the sub-scan magnification BH determined from the read image YG. Therefore, the read image YG of the relatively small original G can be corrected with high accuracy.

(7) The relatively small document G has a smaller number of read lines NL than the relatively large document G. Therefore, even when all the read images YG before correction are stored in the RAM 27 when determining the sub-scanning magnification BH, it is possible to suppress an increase in the capacity required for the RAM 27.

(8) In the image reading apparatus 1 of the present embodiment, the reference radius is different for each conveyance path 22 with respect to two conveyance paths 22 having different radii of curvature and possibly causing a difference in conveyance speed when conveying the original G. Is switched to correct the magnification of the read image YG in the sub-scanning direction D3. Therefore, it is possible to determine a reference value for correcting the read image YG in the sub-scanning direction D3 so as to suppress the influence on the read image YG caused by the shape of the transport path 22.

(9) Since the image reading apparatus 1 according to the present embodiment determines the conveyance path 22 through which the document G is conveyed based on the state of the tray plate 50, the user manually changes the state of the tray plate 50. Thus, it is possible to determine which conveyance path 22 the document G is conveyed through.

<Embodiment 2>
A second embodiment will be described with reference to FIG. In the present embodiment, the first correction constant TH1 corresponding to the first transport path 22A and the second correction constant TH2 corresponding to the second transport path 22B are determined in advance and stored in the RAM 26. The difference from the image reading apparatus 1 of the first embodiment is that the magnification in the sub-scanning direction D3 is also corrected based on the correction constant TH for the read image YG of the original G conveyed along. Each correction constant TH is determined based on the shape of the corresponding conveyance path 22, in particular, the radius of curvature of the curved portion of the conveyance path 22, the conveyance roller 44 used for conveyance in the conveyance path 22, and the like. In the following description, the same description as that of the first embodiment will not be repeated.

1. Reading Process When the reading process is started, the CPU 20 executes a setting process for setting the conveyance path 22 prior to the conveyance of the original G (S82 to S86). In the setting process, the CPU 20 checks the state of the tray plate 50 using the state sensor 10 (S82). When the tray plate 50 is in the open state (S82: YES), the CPU 20 switches the direction changing plate 48 to the first posture F1, reads the first correction constant TH1 stored in the ROM 26, and sets the representative correction constant TH0 to the first correction constant TH0. 1 correction constant TH1 is substituted (S84).

  On the other hand, when the tray plate 50 is in the closed state (S82: NO), the direction change plate 48 is switched to the second posture F2, and the second correction constant TH2 stored in the ROM 26 is read and the second correction constant TH0 is set to the second correction constant TH0. The correction constant TH2 is substituted (S84). When completing the setting process, the CPU 20 starts conveying the document G along the set conveyance path 22 (S88) and counts the number of steps. Further, the CPU 20 sets the planned number Y to zero (S90).

  Next, the CPU 20 detects the position of the document G being conveyed using the R sensor 14, and waits until the first step number ST1 is counted after the R sensor 14 is turned on and the R sensor 14 is turned on. (S92: NO). When the CPU 20 counts the first step number ST1 after the R sensor 14 is turned on (S92: YES), the CPU 20 adds 1 to the planned number Y (S94), and the planned number Y is a multiple of the representative correction constant TH0. (S96).

  When the planned number Y is not a multiple of the representative correction constant TH0 (S96: NO), the CPU 20 executes reading once in the main scanning direction D1 (S98). On the other hand, when the planned number Y is a multiple of the representative correction constant TH0 (S96: YES), the CPU 20 does not perform reading in the main scanning direction D1.

  The CPU 20 detects the position of the document G being conveyed using the R sensor 14, and after the R sensor 14 is turned off and the R sensor 14 is turned off, the first step number ST1 is counted (S100: NO). , The process from S94 is repeated. When the CPU 20 counts the first step number ST1 after the R sensor 14 is turned off (S100: YES), the reading of the document G is completed. When the CPU 20 further counts the second step number ST, the conveyance of the original G is stopped (S102), and the reading process is terminated.

2. Advantages of the present embodiment (1) In the image reading apparatus 1 of the present embodiment, correction processing is executed by switching the correction constant TH according to the transport path 22 along which the original G is transported. Therefore, the correction constant TH can be set for each conveyance path 22 according to the conveyance path 22 in which the shape and the document G to be conveyed are different, and the read image YG obtained by reading the document G conveyed on each conveyance path 22 is set. On the other hand, different correction processes can be executed.

(2) In the image reading apparatus 1 of the present embodiment, the original G is read based on the correction constant TH stored in advance in the ROM 26 for the read image YG of the original G conveyed along any conveyance path 22. The read image YG is corrected during reading. Therefore, even when the document G is transported along any transport path 22, the time from the start of scanning of the document G to the completion of correction of the read image YG can be shortened.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.
(1) In the above embodiment, the image reading apparatus 1 having the scanner function has been described. However, the present invention is not limited to this, and the present invention is a multifunction device having a printer function, a copy function, a facsimile function, and the like. May be.

(2) In the above-described embodiment, the image reading apparatus 1 has one CPU 20 and an example in which various processes such as a reading process are executed by the one CPU 20 has been described. Not limited. For example, if each unit may be configured by a plurality of CPUs, each unit may be configured only by a hardware circuit such as an ASIC (Application Specific Integrated Circuit). Furthermore, each part may be comprised by one or several CPU and ASIC.

(3) Further, the program executed by the CPU 20 does not necessarily have to be stored in the ROM 26, and may be stored in the CPU 20 itself or in another storage device.

(4) In the above-described embodiment, the example in which the transport path 22 to which the document G is transported is determined based on the posture of the tray plate 50. However, the transport path 22 through which the document G is transported is described. The determination method is not limited to the above, and may be determined according to an instruction from the user via the input unit 11, for example, depending on the state of the deflection plate 48.

(5) In the above embodiment, the description has been given using an example in which the main scanning direction length LS of the original G is estimated from the unit read image TG acquired by reading the original G in the first main scanning direction D1. The unit read image TG used to estimate the main scanning direction length LS of the document G may be the second and subsequent unit read images TG. Further, the main scanning direction length LS of the document G does not necessarily have to be estimated from the read image YG of the document G, and may be determined by an instruction from the user via the input unit 5, for example.

(6) In the above embodiment, it has been described that the magnification in the sub-scanning direction D3 of the read image YG is corrected based on the sub-scan magnification BH or the correction constant TH. However, when the sub-scan magnification BH is 1, When the correction constant TH is equal to the reference reading number NK, the read image YG is not corrected. That is, “correcting the magnification in the sub-scanning direction D3” includes “correcting the magnification in the sub-scanning direction D3 to the same magnification”.

(7) In the above embodiment, the example of reducing the magnification of the read image YG in the sub-scanning direction D3 has been described as the read correction process. However, in the read correction process, the read image YG in the sub-scanning direction D3 is described. The magnification may be increased.

22A, 22B: transport path, 44: transport roller, 46: discharge roller, 50: tray plate, BH: sub-scan magnification, D1: main scan direction, D3: sub-scan direction, DH: sub-scan direction data length, DS : Main scanning direction data length, LH: Sub scanning direction length, LS: Main scanning direction length, NK: Reference reading number, NL: Reading line number, TG: Unit reading image, TH: Correction constant, YG: Reading image

Claims (6)

A placement section on which a document is placed;
A transport unit that transports the document placed on the placement unit along one of the first transport path and the second transport path;
A reading unit that is provided on a common conveyance path of the first conveyance path and the second conveyance path, and that reads an image of the document conveyed by the conveyance unit in a main scanning direction;
A control unit;
With
The controller is
A setting process for setting a transport path of the document transported by the transport unit to one of the first transport path and the second transport path;
A reading process for reading an image of the conveyed document by the reading unit;
If set to the first conveying path by the pre-Symbol setting process, based on the main scanning direction document width in the main scanning direction of the document image read by the reading process, the sub-scanning direction in the sub-scanning direction of the document A determination process for estimating a length and determining a first sub-scanning magnification at which a sub-scanning direction document width in the sub-scanning direction of the document image is equal to the sub-scanning direction length;
A first correction process for correcting the document image at the first sub-scanning magnification determined by the determination process when the first conveyance path is set by the setting process;
When the second conveyance path is set by the setting process, the number of unit reading images acquired is increased or decreased based on a predetermined correction constant, so that enlargement in the sub-scanning direction is performed when reading a document. An image reading apparatus that executes a second correction process for performing reduction . The image reading apparatus according to claim 1,
The controller is
In the reading process, reading in the main scanning direction by the reading unit is repeated a plurality of times in the sub-scanning direction to read the document image,
An image reading device that estimates the sub-scanning direction length based on the main-scanning-direction document width of a unit-read image read by the first reading in the main-scanning direction in the document image in the determination process. The image reading apparatus according to claim 2,
A storage unit that stores a reference reading number indicating a reference reading number in the main scanning direction corresponding to the sub-scanning direction length;
The controller is
In the determination process, the image reading apparatus determines the first sub-scanning magnification at which the number of readings when the document image is read is equal to the reference reading number corresponding to the length in the sub-scanning direction. An image reading apparatus according to any one of claims 1 to 3,
The image reading apparatus, wherein the first conveyance path is a conveyance path for conveying a document thicker than a reference thickness. An image reading apparatus according to any one of claims 1 to 4,
A storage unit for storing the document image;
The image reading apparatus, wherein the first transport path is a transport path for transporting a document smaller than a reference document size. An image reading apparatus according to any one of claims 1 to 5,
A switching unit that is provided on the first transport path and switches between a blocking state that blocks the first transport path and a transport state that transports the document along the first transport path;
The controller is
In the setting process, when the state of the switching unit is the conveyance state, the document is set to be conveyed along the first conveyance path, and when the state of the switching unit is the blocking state, An image reading device configured to set the original so as to be conveyed along the second conveyance path.

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