JP5744705B2 - Document reader - Google Patents

Description

  The present invention relates to a document reading apparatus having a function of executing a network scan, for example.

  As a document reading device that reads a document line by line with an image sensor such as a linear image sensor while moving the document relatively in the sub-scanning direction, a flatbed type document reading device and an ADF (Auto Document Feeder) type document There is a reader. In the flat bed type, the original is read by moving the carriage in the sub-scanning direction. In the ADF method, the document is read in the sub-scanning direction.

  In a network scan in which image data of a document read by a document reading device is transferred to a destination such as a server via a network, the transfer speed of the image data on the network depends on network traffic. For this reason, if there is a large amount of network traffic, a phenomenon occurs in which the transfer rate of image data on the network is slower than the speed at which the document reader reads the document.

  The document reading apparatus includes a buffer memory for temporarily storing image data. However, when the above phenomenon occurs, there is a possibility that the amount of image data to be stored in the buffer memory exceeds the capacity of the buffer. If the amount of image data to be stored in the buffer memory exceeds the capacity of the buffer memory during reading of the original, the reading of the original fails.

  Therefore, the following two types of document reading apparatuses have been proposed. The first type includes a buffer memory that can store image data of a document for one page. In this type, since the capacity of the buffer memory is increased, the cost of the document reading apparatus increases.

  In the second type, when the image data to be stored in the buffer memory exceeds the capacity of the buffer memory during reading of the original, the reading of the original is paused, and the image data stored in the buffer memory is sent to the network. When the buffer memory becomes empty, scanning of the original resumes.

  According to the second type, since the capacity of the buffer memory can be reduced, the cost of the document reading apparatus can be reduced. However, since the reading of the original is temporarily stopped during the reading of the original and the reading is resumed, a joint between images is generated. Since the line at the reading stop position is not read, reading is resumed from the stop position. It is necessary to improve the accuracy of matching the reading restart position to the reading stop position so that the joints of the images do not shift.

  For example, the following three document reading devices have been proposed as document reading devices that prevent the joint between images from being shifted by improving the accuracy of matching the reading restart position to the reading stop position.

  The first is a distance measuring unit that measures the image reading position of the document in the sub-scanning direction, a unit that generates a horizontal synchronization signal from the divided signal of the reference clock signal, and a unit that resynchronizes the horizontal synchronization signal. (See, for example, Patent Document 1). In this document reading device, when the reading operation is interrupted due to the occurrence of buffer overrun or the like, the sub-scan reading position at the time of interruption is stored in the buffer memory, and the horizontal synchronization is performed at the timing when the carriage passes the re-reading start position during the re-reading operation By resynchronizing the signals, the misalignment of the joints is eliminated.

  Second, the free space detection unit that detects the free space of the buffer memory that temporarily stores the scanned image, and when the free space detection unit detects a shortage of free space, reading of the image is stopped, and the free space is detected. When detecting that the free space has been secured, the reading control unit that resumes reading the image, and when the free space detection unit detects that the free space is insufficient, the motor is stopped and when the free space is secured And a motor control unit that sets the motor at a preset settling time for each reading mode, and accelerates, accelerates, and decelerates the motor to drive at the reading speed (for example, a patent reading device). Reference 2).

  Third, an imaging unit that reads an image in the main scanning direction based on the main scanning synchronization signal, and a driving unit that moves the imaging unit in the sub scanning direction based on a drive control signal that is asynchronous with the main scanning synchronization signal. And an intermittent instruction means for generating a stop instruction and a restart instruction for intermittently reading an image by the imaging means, and if a stop instruction is generated, a phase difference between the main scanning synchronization signal and the drive control signal is recognized. And a phase control unit that corrects the phase difference between the main scanning synchronization signal and the drive control signal based on the phase difference that is recognized and held when a restart instruction is generated (for example, (See Patent Document 3).

JP-A-8-228267 JP 2001-217996 A JP 2000-270162 A

  In the flat bed system, control for temporarily stopping reading and restarting reading while reading an original is performed as follows. If the amount of image data to be stored in the buffer memory exceeds a specified amount while reading a document (for example, when the buffer memory is full), the movement of the carriage in the sub-scanning direction is temporarily stopped and the document reading is temporarily stopped. Stop. When the image data stored in the buffer memory is sent to the network and the buffer memory becomes empty, the carriage is moved backward from the stop position in the sub-scanning direction and then moved forward, and the carriage moving speed is set to the target speed at the reading stop position. The document reading is resumed from the reading stop position.

  When the power for moving the carriage in the sub-scanning direction is generated by the stepping motor, the reading restart position is adjusted to the reading stop position in consideration of the slowing up and slowing down of the stepping motor. In a stepping motor, the number of pulse signals that control the rotation angle of the motor and the amount of movement of the carriage in the sub-scanning direction correspond one-to-one, so the reading restart position can be set to the reading stop position with relatively high accuracy. Can be matched.

  However, if the original clock that generates the pulse signal that controls the rotation angle of the motor is different from the original clock that generates the horizontal synchronization signal when reading the document, the accuracy of matching the read restart position to the read stop position decreases. Cause. As a result, the joint of the image may be shifted in the sub-scanning direction.

  According to the present invention, in a method of reading an original by relatively moving the original in the sub-scanning direction, the original reading that can improve the accuracy of matching the reading restart position to the reading stop position when the reading is temporarily stopped. An object is to provide an apparatus.

  The present invention relates to a document reading apparatus capable of shortening the time from the pause of reading to the restart of reading when reading is paused in a method of reading the document by relatively moving the document in the sub-scanning direction. The purpose is to provide.

  An original reading apparatus according to one aspect of the present invention that achieves the above object includes an imaging element that reads an original in line units along the main scanning direction, and a motor that generates power for moving the original relatively in the sub-scanning direction. Using a pulse signal for controlling the rotation angle of the motor, and a movement control unit for controlling the relative movement of the document in the sub-scanning direction, and generating a horizontal synchronization signal in synchronization with the pulse signal. An image sensor control unit that controls the operation of the image sensor, and a storage unit that temporarily stores image data output from the image sensor when the image sensor reads the document. The image sensor is caused to read the document using the horizontal synchronization signal generated by the first horizontal synchronization signal generation unit while relatively moving the document in the sub-scanning direction. Operation, when the image data temporarily accumulated in the storage unit during reading of the document exceeds a predetermined amount, reading of the document is temporarily stopped and the document is moved relatively in the sub-scanning direction. When the operation of stopping and reading of the original is resumed, the original is read back from the reading stop position of the original by moving the original relatively backward in the sub-scanning direction and then moving forward. A reading control unit that executes an operation by controlling the movement control unit and the image sensor control unit.

  In the document reading apparatus according to one aspect of the present invention, a horizontal synchronization signal used for reading a document is generated in synchronization with a pulse signal. The pulse signal is a signal that controls the rotation angle of a motor that generates power for moving the document relatively in the sub-scanning direction. Thus, according to one aspect of the present invention, the horizontal synchronization signal is generated in synchronization with the pulse signal that controls the rotation angle of the motor. Accordingly, the accuracy of matching the reading restart position with the reading stop position can be improved, so that the joints of the images can be prevented from shifting.

  In the case of a stepping motor, the pulse signal for controlling the rotation angle of the motor is a pulse signal used for driving the stepping motor. In the DC motor, the rotation of the DC motor is detected by an encoder, and the rotation of the DC motor is feedback-controlled. For this reason, in the case of a DC motor, the pulse signal output from the encoder is a pulse signal for controlling the rotation angle of the motor.

  If the horizontal synchronization signal is not synchronized with the pulse signal for controlling the rotation angle of the motor, the width of one line read by the image sensor varies when the rotation speed of the motor varies. If the horizontal synchronization signal is synchronized with the pulse signal that controls the rotation angle of the motor as in the document reading apparatus according to one aspect of the present invention, the position for reading each line even if the rotation speed of the motor fluctuates. Does not vary, the width of one line can be made constant. Therefore, the document can be read without the width of one line extending or contracting from the leading edge to the trailing edge of the document.

  In the above configuration, a light source that irradiates the original with light, and a light source control unit that controls lighting of the light source, wherein the light source control unit defines a lighting possible period of the light source, and the lighting possible period is An enable signal generation unit configured to generate an enable signal shorter than a period of the horizontal synchronization signal in synchronization with the pulse signal;

  According to this configuration, since the enable signal that defines the lighting-enabled period of the light source is generated in synchronization with the pulse signal, the enable signal can be generated in synchronization with the horizontal synchronization signal. For this reason, it is possible to prevent the light source from being turned on before the generation of the horizontal synchronization signal.

  In the above configuration, the motor is a DC motor.

  In the DC motor, the rotation speed is controlled by feedback control using a pulse signal (pulse signal for controlling the rotation angle of the motor) output from the encoder. Since the frequency of the pulse signal output from the encoder changes, when the DC motor is applied in one aspect of the present invention, a slight shift occurs in the interval of the horizontal synchronization signal. According to this configuration, the lighting-enabled period specified by the enable signal is shorter than the period of the horizontal synchronization signal, and the enable signal is generated in synchronization with the horizontal synchronization signal. For this reason, even if a slight shift occurs in the interval of the horizontal synchronization signals, it is possible to prevent the enable signal generated in synchronization with a certain horizontal synchronization signal from extending over the period of the next horizontal synchronization signal. Accordingly, the lighting time of the light source can be made constant in reading each line. Therefore, the amount of light accumulated in the image sensor by reading each line can be kept constant, so that the image quality of the read original image can be improved.

  In the above configuration, the imaging element control unit includes a clock generation unit that generates a clock signal, and a second horizontal synchronization signal generation unit that generates the horizontal synchronization signal in synchronization with the clock signal, and the imaging When the element control unit causes the image sensor to acquire reference data used for correcting image data without relatively moving the document in the sub-scanning direction, the element control unit generates the second horizontal synchronization signal generation unit. The reference data is acquired by the image sensor using a horizontal synchronization signal.

  Reference data such as white reference data and black reference data is acquired by the image sensor without relatively moving the document in the sub-scanning direction. According to this configuration, the horizontal synchronization signal used for obtaining the reference data is generated in synchronization with the clock signal generated by the clock generation unit included in the image sensor control unit. Accordingly, the horizontal synchronization signal can be generated even if the document is not moved relatively in the sub-scanning direction (even if the pulse signal is not generated).

  In the above configuration, an interface is provided that can be connected to a network that transfers image data of the document read by the image sensor to a destination.

  A document reading apparatus according to another aspect of the present invention includes a light source that irradiates light on a document, an image sensor that reads the document irradiated with light from the light source in units of lines along a main scanning direction, and the document. An image sensor control unit that controls the operation of the image sensor, and a horizontal sync signal that includes a movement control unit that controls the relative movement in the sub-scanning direction, a horizontal sync signal generator that generates a horizontal sync signal, A part of the period from the occurrence of the horizontal synchronization signal to the next generation of the horizontal sync signal is the lighting time of the light source, and the original moves relatively at a constant speed in the sub-scanning direction, when moving at a reduced speed, and when moving at an acceleration A light source control unit that controls the lighting time to be the same, a storage unit that temporarily stores image data output from the image sensor when the image sensor reads the document, and (a) the document (B) When the image data temporarily accumulated in the storage unit during reading of the document exceeds a predetermined amount, the image sensor reads the document while moving at a relatively constant speed in the sub-scanning direction. An operation of causing the image sensor to read the original while moving the original relatively decelerated in the sub-scanning direction; and (c) stopping the original from relatively moving in the sub-scanning direction after the decelerating movement. And (d) when resuming the reading of the original, the relative movement of the original is stopped without moving the original relatively backward in the sub-scanning direction. An operation of resuming the reading of the original from a position where the relative movement of the original is stopped while relatively accelerating the original in the sub-scanning direction from the position, the movement control unit, the image sensor control unit, Previous And a reading control unit that is executed by controlling the light source control unit.

  In the document reading apparatus according to another aspect of the present invention, when the reading of the document is temporarily stopped when the image data temporarily stored in the storage unit during reading of the document exceeds a predetermined amount, the following operation is performed. . First, an operation of causing the image sensor to read the original while moving the original relatively slow in the sub-scanning direction is executed to stop the relative movement of the original in the sub-scanning direction. When the reading of the original is resumed, the original is not moved backward in the sub-scanning direction, and the original is moved relatively accelerated in the sub-scanning direction from the position where the relative movement of the original is stopped. The reading of the original is resumed from the position where the relative movement is stopped.

  Even when the original is moved relatively decelerating and accelerating in the sub-scanning direction, an operation of causing the image sensor to read the original is executed. In another aspect of the present invention, when a part of a period from the generation of a horizontal synchronization signal to the generation of the next horizontal synchronization signal is a light source lighting time, and the document moves relatively at a constant speed in the sub-scanning direction, the deceleration is performed In the case of moving and the case of accelerating movement, the lighting time is controlled to be the same. Thereby, in reading each line, the amount of light accumulated in the image sensor can be kept constant (the same amount of light). Accordingly, the image quality of the line read when the document is relatively decelerated and accelerated in the sub-scanning direction can be made the same as the image quality of the line read when the document is moving at a constant speed. .

As described above, according to another aspect of the present invention, when reading of a document is resumed, the document is not moved backward in the sub-scanning direction, and the document is moved from the position where the relative movement of the document is stopped. Resume reading. Therefore, when resuming the reading of an original, the original is moved backward relative to the sub-scanning direction and then moved forward, so that the reading of the original is resumed from the position where the original reading is resumed from the reading stop position. The time from the pause to the resumption of reading can be shortened.
An original reading apparatus according to still another aspect of the present invention includes an image sensor that reads an original in line units along the main scanning direction, a stepping motor that generates power for moving the original relatively in the sub-scanning direction, A pulse signal generator for generating a pulse signal used for driving the stepping motor, and a step-up signal indicating that the original has moved by one pixel in the sub-scanning direction are generated in synchronization with the pulse signal. A step-up signal generation unit that controls the movement of the document relative to the sub-scanning direction, and a first horizontal synchronization signal generation that generates a horizontal synchronization signal in synchronization with the step-up signal. An image sensor control unit for controlling the operation of the image sensor, and when the image sensor reads the document, the image sensor outputs the document. A storage unit that temporarily stores the image data and the horizontal synchronization signal generated by the first horizontal synchronization signal generation unit while relatively moving the document in the sub-scanning direction. An operation for reading an original, and when the image data temporarily accumulated in the storage unit during reading of the original exceeds a predetermined amount, the reading of the original is temporarily stopped and the original is relatively moved in the sub-scanning direction. When stopping the movement and restarting the reading of the original, the original is moved backward relative to the sub-scanning direction and then moved forward to move the original from the reading stop position of the original. A reading control unit that executes an operation of resuming reading by controlling the movement control unit and the image sensor control unit, and the step-up signal generation unit includes: If the pulse signal for reverse rotation of the stepping motor does not generate the step-up signal.

  According to one aspect of the present invention, in a method of reading a document by relatively moving the document in the sub-scanning direction, when reading is temporarily stopped, the accuracy of matching the reading restart position with the reading stop position is improved. be able to.

  According to another aspect of the present invention, in a method of reading a document by relatively moving the document in the sub-scanning direction, when reading is paused, the time from the pause of reading to the restart of reading is shortened. be able to.

1 is a diagram showing an outline of an internal structure of an image forming apparatus to which a document reading apparatus according to a first embodiment and a second embodiment of the present invention can be applied. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus illustrated in FIG. 1. 1 is a block diagram illustrating a main part of a document reading apparatus according to a first embodiment of the present invention. 6 is a time chart illustrating a reading operation in a monochrome reading mode in the first embodiment. 6 is a time chart showing the first half of a reading operation in a color reading mode in the first embodiment. 6 is a time chart showing the latter half of the reading operation in the color reading mode in the first embodiment. 6 is a flowchart for explaining the operation of the document reading apparatus according to the first embodiment. 9 is a time chart showing the first half of a reading operation in a monochrome reading mode in the second embodiment. 9 is a time chart showing the latter half of the reading operation in the monochrome reading mode in the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the internal structure of an image forming apparatus 1 to which the document reading apparatus according to the first and second embodiments of the present invention can be applied. The image forming apparatus 1 can be applied to, for example, a digital multifunction machine having functions of a copy, a printer, a scanner, and a facsimile. The image forming apparatus 1 includes an apparatus main body 100, a document reading unit 200 disposed on the apparatus main body 100, a document feeding unit 300 disposed on the document reading unit 200, and an operation disposed on the upper front surface of the apparatus main body 100. Part 400 is provided.

  The document feeder 300 functions as an automatic document feeder, and can continuously send a plurality of documents placed on the document placement unit 301 to the document reading unit 200.

  The document reading unit 200 includes a carriage 201 on which a light source and an image sensor are mounted, a document table 203 formed of a transparent member such as glass, and a document reading slit 205. When reading a document placed on the document table 203, the document is read by the image sensor while moving the carriage 201 in the longitudinal direction of the document table 203. On the other hand, when reading a document fed from the document feeding unit 300, the carriage 201 is moved to a position facing the document reading slit 205, and the document fed from the document feeding unit 300 is scanned. Reading is performed by the image sensor through the reading slit 205. The image sensor outputs the read original as image data.

  The apparatus main body 100 includes a sheet storage unit 101, an image forming unit 103, and a fixing unit 105. The sheet storage unit 101 is disposed at the lowermost part of the apparatus main body 100 and includes a sheet tray 107 that can store a bundle of sheets. In the bundle of sheets stored in the sheet tray 107, the uppermost sheet is sent out toward the sheet conveyance path 111 by driving the pickup roller 109. The sheet is conveyed to the image forming unit 103 through the sheet conveyance path 111.

  The image forming unit 103 forms a toner image on the conveyed paper. The image forming unit 103 includes a photosensitive drum 113, an exposure unit 115, a developing unit 117, and a transfer unit 119. The exposure unit 115 generates modulated light corresponding to image data (image data output from the document reading unit 200, image data transmitted from a personal computer, image data received by facsimile, etc.), and is uniformly charged. Irradiate to the peripheral surface of the photosensitive drum 113. As a result, an electrostatic latent image corresponding to the image data is formed on the peripheral surface of the photosensitive drum 113. In this state, a toner image corresponding to image data is formed on the peripheral surface by supplying toner from the developing unit 117 to the peripheral surface of the photosensitive drum 113. This toner image is transferred by the transfer unit 119 to the sheet conveyed from the sheet storage unit 101 described above.

  The sheet on which the toner image is transferred is sent to the fixing unit 105. In the fixing unit 105, heat and pressure are applied to the toner image and the paper, and the toner image is fixed on the paper. The paper is discharged to the stack tray 121 or the paper discharge tray 123.

  The operation unit 400 includes an operation key unit 401 and a display unit 403. The display unit 403 has a touch panel function, and displays a screen including soft keys. The user operates the soft keys while viewing the screen to make settings necessary for executing functions such as copying.

  The operation key unit 401 is provided with operation keys including hard keys. Specifically, a start key 405, a numeric key 407, a stop key 409, a reset key 411, a function switching key 413 for switching between a copy, a printer, a scanner, and a facsimile are provided.

  A start key 405 is a key for starting operations such as copying and facsimile transmission. A numeric keypad 407 is a key for inputting numbers such as the number of copies and a facsimile number. A stop key 409 is a key for stopping a copying operation or the like halfway. A reset key 411 is a key for returning the set contents to the initial setting state.

  The function switching key 413 includes a copy key, a transmission key, and the like, and is a key for switching between a copy function and a transmission function. When the copy key is operated, an initial copy screen is displayed on the display unit 403. When the transmission key is operated, an initial screen for facsimile transmission and mail transmission is displayed on the display unit 403.

  FIG. 2 is a block diagram showing a configuration of the image forming apparatus 1 shown in FIG. The image forming apparatus 1 has a configuration in which an apparatus main body 100, a document reading unit 200, a document feeding unit 300, an operation unit 400, a control unit 500, and a communication unit 600 are connected to each other by a bus. Since the apparatus main body 100, the document reading unit 200, the document feeding unit 300, and the operation unit 400 have already been described, description thereof is omitted.

  The control unit 500 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an image memory, and the like. The CPU executes control necessary for operating the image forming apparatus 1 on the hardware constituting the image forming apparatus 1. The ROM stores software necessary for controlling the operation of the image forming apparatus 1. The RAM is used for temporary storage of data generated during execution of software, storage of application software, and the like. The image memory temporarily stores image data (image data output from the document reading unit 200, image data transmitted from a personal computer, image data received by facsimile, etc.).

  The communication unit 600 includes a facsimile communication unit 601 and a network I / F unit 603. The facsimile communication unit 601 includes an NCU (Network Control Unit) that controls connection of a telephone line with a destination facsimile, and a modulation / demodulation circuit that modulates / demodulates a signal for facsimile communication. The facsimile communication unit 601 is connected to the telephone line 605.

  A network I / F unit 603 is connected to a LAN (Local Area Network) 607. A network I / F unit 603 is a communication interface circuit for executing communication with a terminal device such as a personal computer connected to the LAN 607.

  FIG. 3 is a block diagram showing a main part of the document reading apparatus 2 according to the first embodiment of the present invention. The document reading unit 200 and the network I / F unit 603 illustrated in FIG. 2 function as the document reading device 2. The document reading apparatus 2 includes a carriage 201, a motor 10, a movement control unit 30, an image sensor control unit 40, a light source control unit 50, a reading control unit 60, an image processing unit 70, a buffer memory 80 as an example of a storage unit, and a network I / O. An F unit 603 is provided.

  The carriage 201 accommodates the image sensor 21 and the light source 23. The image sensor 21 is a linear image sensor that reads an original in line units along the main scanning direction (for example, a CCD linear image sensor, CIS (Contact Image Sensor)). In the present embodiment, CIS will be described as an example. The light source 23 irradiates the document placed on the document table 203 (FIG. 1) with light. The light source 23 includes a red light source 23R, a green light source 23G, and a blue light source 23B. The red light source 23R is, for example, a red LED, the green light source 23G is, for example, a green LED, and the blue light source 23B is, for example, a blue LED.

  The motor 10 generates power for moving the carriage 201 in the sub-scanning direction (in other words, moving the document relatively in the sub-scanning direction). Hereinafter, the movement of the carriage 201 in the sub-scanning direction means a relative movement of the document in the sub-scanning direction. In this embodiment, the case of reading a document by the flat bed method will be described, but the present invention can be applied to a case of reading a document by the ADF method. When reading an original by the ADF method, the carriage 201 is fixed and the original is moved in the sub-scanning direction.

  In the present embodiment, a stepping motor will be described as an example of the motor 10, but other motors such as a DC motor may be used.

  The movement control unit 30 controls to move the carriage 201 in the sub-scanning direction using a pulse signal PuS that controls the rotation angle of the motor 10. The movement control unit 30 includes a power supply 31, a pulse signal generation unit 33, and a step-up signal generation unit 35.

  The power supply 31 supplies power to the motor 10. The pulse signal generation unit 33 generates a pulse signal PuS that controls the rotation angle of the motor 10. In the case of a stepping motor, the pulse signal used to drive the stepping motor is a pulse signal PuS that controls the rotation angle of the motor 10. In the DC motor, the rotation of the DC motor is detected by an encoder, and the rotation speed and amount of the DC motor are feedback-controlled. For this reason, in the case of a DC motor, the pulse signal output from the encoder is a pulse signal PuS that controls the rotation angle of the motor 10.

  The step-up signal generator 35 generates a step-up (STEPUP) signal StS. The step-up signal StS is a signal indicating that the carriage 201 has moved by one pixel in the sub-scanning direction (in other words, a signal indicating that the carriage 201 has moved onto a line to be read next). In the present embodiment, it is indicated that one cycle of the step-up signal StS has moved by one pixel in the sub-scanning direction. However, the present invention is not limited to this. For example, four cycles of the step-up signal StS may indicate that one pixel has moved in the sub-scanning direction.

  The step-up signal StS is generated in synchronization with the pulse signal PuS that controls the rotation angle of the motor 10. The amount of movement of one pixel in the sub-scanning direction of the carriage 201 varies depending on the document reading resolution (for example, 600 dpi, 300 dpi). Further, in the case of a stepping motor, the movement amount of one pixel in the sub-scanning direction of the carriage 201 differs depending on the excitation method (for example, 1-2 phase excitation, 2 phase excitation). Therefore, the step-up signal StS is set in consideration of the resolution of document reading (in the case of a stepping motor, further an excitation method).

  The image sensor control unit 40 is a driver that controls the operation of the image sensor 21. The image sensor control unit 40 includes an ASIC (Application Specific Integrated Circuit) including a clock generation unit 41, a first horizontal synchronization signal generation unit 43, a second horizontal synchronization signal generation unit 45, a power supply 47, and an AD converter 49. . The image sensor control unit 40 further includes a vertical synchronization signal generation unit and the like, which are not particularly related to the description of the present embodiment, and thus the description thereof is omitted.

  The clock generation unit 41 generates a clock signal that serves as a reference for the vertical synchronization signal and the horizontal synchronization signal HoS generated by the second horizontal synchronization signal generation unit 45. The power supply 47 supplies power to the image sensor 21.

  The first horizontal synchronization signal generation unit 43 generates the horizontal synchronization signal HoS in synchronization with the step-up signal StS. The horizontal synchronization signal HoS is sent to the image sensor 21 and used for reading a document. Since the step-up signal StS is generated in synchronization with the pulse signal PuS, the horizontal synchronization signal HoS generated by the first horizontal synchronization signal generation unit 43 is generated in synchronization with the pulse signal PuS.

  The second horizontal synchronization signal generation unit 45 generates a horizontal synchronization signal HoS in synchronization with the clock signal generated by the clock generation unit 41. The horizontal synchronization signal HoS is sent to the image sensor 21 and used for reading the white reference and the black reference.

  The AD converter 49 converts the analog image data ImD output by reading the document by the image sensor 21 into digital image data. The digital image data is subjected to predetermined processing (for example, shading correction) by the image processing unit 70. The digital image data subjected to the predetermined processing is temporarily stored in the buffer memory 80, and then transferred to a destination such as a server via the network by the network I / F unit 603.

  The buffer memory 80 is an example of a storage unit that temporarily stores image data ImD output from the image sensor 21 when the image sensor 21 reads a document. A network I / F unit 603 is an example of an interface that can be connected to a network that transfers image data ImD of a document read by the image sensor 21 to a destination.

  The light source control unit 50 includes a power source 51 and an enable signal generation unit 53 and controls lighting of the light source 23. The power source 51 supplies power to the red light source 23R, the green light source 23G, and the blue light source 23B. The enable signal generation unit 53 synchronizes the enable signals EnS (R), EnS (G), and EnS (B) that define the lighting possible periods of the red light source 23R, the green light source 23G, and the blue light source 23B with the step-up signal StS. Generated and sent to each of the red light source 23R, the green light source 23G, and the blue light source 23B. The period of the enable signal (that is, the lighting-enabled period) is shorter than the period of the horizontal synchronization signal HoS. In the present embodiment, the case where a part of the period from the generation of the horizontal synchronization signal HoS to the generation of the next horizontal synchronization signal HoS is set to the lighting time of the light source 23 is described. However, the present invention can also be applied to a method in which the light source 23 is turned on over the entire period of document reading.

  The reading control unit 60 controls the movement control unit 30, the image sensor control unit 40, and the light source control unit 50, and is realized by a CPU, a RAM, a ROM, and the like. The pulse signal generation unit 33 generates a pulse signal PuS using the CPU clock of the reading control unit 60 as an original clock. The step-up signal StS is generated in synchronization with the pulse signal PuS. The first horizontal synchronization signal generation unit 43 generates the horizontal synchronization signal HoS in synchronization with the step-up signal StS. Therefore, the horizontal synchronization signal HoS generated by the first horizontal synchronization signal HoS and the pulse signal PuS generated by the pulse signal generation unit 33 are synchronized.

  The reading control unit 60 executes the following operations (1) to (3) by controlling the movement control unit 30, the image sensor control unit 40, and the light source control unit 50.

  The operation (1) is an operation for causing the image sensor 21 to read a document using the horizontal synchronization signal HoS generated by the first horizontal synchronization signal generation unit 43 while moving the carriage 201 in the sub-scanning direction.

  In the operation (2), when the image data temporarily stored in the buffer memory 80 becomes full during reading of the original, the reading of the original is temporarily stopped and the carriage 201 is stopped from moving in the sub-scanning direction. Is the action. The case where the image data temporarily stored in the buffer memory 80 is full is an example of a case where the image data temporarily stored in the buffer memory 80 exceeds a predetermined amount. The image data temporarily stored in the buffer memory 80 may be near full.

  In the operation (3), when the reading of the document is resumed, the carriage 201 is moved back in the sub-scanning direction (in other words, the document is moved back relatively in the sub-scanning direction) and then moved forward, thereby reading the document. This is an operation for resuming the reading of the document from the stop position.

  Next, a reading operation when the image data stored in the buffer memory 80 becomes full during reading of the document will be described. FIG. 4 is a time chart showing the reading operation in the monochrome reading mode. 5 and 6 are time charts showing the reading operation in the color reading mode. First, the case of the monochrome reading mode will be described with reference to FIGS.

  In the monochrome reading mode, the green light source 23G is used, and the red light source 23R and the blue light source 23B are not used. The step-up signal generator 35 generates the step-up signal StS based on the pulse signal PuS generated by the pulse signal generator 33 and controlling the rotation angle of the motor 10. The first horizontal synchronization signal generation unit 43 generates a horizontal synchronization signal HoS in synchronization with the rising edge of the step-up signal StS. The enable signal generation unit 53 generates the enable signal EnS (G) for the green light source 23G in synchronization with the rising edge of the step-up signal StS. The image sensor 21 reads a document in units of one line in synchronization with the horizontal synchronization signal HoS, and outputs image data ImD of the read lines.

  The image data ImD of the immediately preceding line is output from the line where the image sensor 21 is located. That is, when the image sensor 21 is positioned on the nth line, the image data ImD of the (n−1) th line is output. Therefore, the image data ImD output when the image sensor 21 is positioned on the first line is discarded.

  When the reading control unit 60 determines that the image data temporarily stored in the buffer memory 80 is full, reading of the document is temporarily stopped. FIG. 4 shows that reading is temporarily stopped after reading the nth line. When reading is temporarily stopped, the motor 10 is stopped, so that the pulse signal PuS is not generated. For this reason, the step-up signal StS is not generated. However, one horizontal synchronization signal HoS and one enable signal EnS (G) are generated to output the image data ImD of the nth line. Thereafter, the horizontal synchronization signal HoS and the enable signal EnS (G) are not generated.

  When the reading control unit 60 determines that the image data temporarily stored in the buffer memory 80 is empty, the reading control unit 60 controls the movement control unit 30, the image sensor control unit 40, and the light source control unit 50 to resume reading. Execute control. Hereinafter, this control will be described in detail.

  The movement control unit 30 causes the pulse signal generation unit 33 to generate a pulse signal PuS that reversely rotates the motor 10, and reversely rotates the motor 10, thereby moving the carriage 201 backward in the sub-scanning direction. The step-up signal generator 35 does not generate the step-up signal StS in the case of the pulse signal PuS that reversely rotates the motor 10. For this reason, the horizontal synchronization signal HoS and the enable signal EnS (G) are not generated during the period in which the carriage 201 is retracted in the sub-scanning direction.

  When the movement controller 30 moves the carriage 201 backward by a predetermined distance, the movement controller 30 stops the motor 10 and stops the carriage 201 from moving backward in the sub-scanning direction. Then, the movement control unit 30 causes the pulse signal generation unit 33 to generate a pulse signal PuS that rotates the motor 10 in the forward direction and rotates the motor 10 in the forward direction, thereby moving the carriage 201 forward in the sub-scanning direction. Since the step-up signal generation unit 35 generates the step-up signal StS, the first horizontal synchronization signal generation unit 43 generates the horizontal synchronization signal HoS and generates the enable signal in synchronization with the rise of the step-up signal StS. The unit 53 generates an enable signal EnS (G).

  The reading control unit 60 resumes reading of the document from the document reading stop position by performing a process of validating the image data from the image data of the line at the document reading stop position. FIG. 4 shows that reading of a document is resumed from the (n + 1) th line. When the image sensor 21 is positioned on the (n + 2) th line, the image data ImD of the (n + 1) th line is output. Accordingly, the image data ImD output when the image sensor 21 is positioned on the (n + 1) th line is discarded.

  Next, the case of the color reading mode will be described with reference to FIG. 3, FIG. 5, and FIG. Since CIS is used as the image sensor 21, in the color reading mode, the red light source 23R, the green light source 23G, and the blue light source 23B are turned on in order in reading one line. Accordingly, in the reading of one line, three signals are generated: a horizontal synchronizing signal HoS (R) for reading red, a horizontal synchronizing signal HoS (G) for reading green, and a horizontal synchronizing signal HoS (B) for reading blue. Is done.

  The first horizontal synchronization signal generation unit 43 generates a horizontal synchronization signal HoS (here, horizontal synchronization signal HoS (R)) corresponding to the color to be read first in synchronization with the rise of the step-up signal StS. The horizontal synchronization signal HoS corresponding to the color to be read is provided with a predetermined interval, the horizontal synchronization signal HoS corresponding to the color to be read next (here, the horizontal synchronization signal HoS (G)), and the color to be read last. A corresponding horizontal synchronization signal HoS (here, horizontal synchronization signal HoS (B)) is generated.

  The enable signal generation unit 53 generates the enable signal EnS (R) of the red light source 23R in synchronization with the horizontal synchronization signal HoS (R) (in other words, in synchronization with the rise of the step-up signal StS), and generates the horizontal synchronization signal HoS ( The enable signal EnS (G) of the green light source 23G is generated in synchronization with G), and the enable signal EnS (B) of the blue light source 23B is generated in synchronization with the horizontal synchronization signal HoS (B).

  The image sensor 21 reads image data ImD (R) read in synchronization with the horizontal synchronization signal HoS (R) and image data ImD (G) read in synchronization with the horizontal synchronization signal HoS (G) in reading one line. ) And image data ImD (B) read in synchronization with the horizontal synchronization signal HoS (B).

  The image data of the previous line is output from the line where the image sensor 21 is located. That is, when the image sensor 21 is positioned on the nth line, image data ImD (R), ImD (G), and ImD (B) of the (n−1) th line are output. Therefore, the image data output when the image sensor 21 is positioned on the first line is discarded.

  When the reading control unit 60 determines that the image data temporarily stored in the buffer memory 80 is full, the reading of the document is temporarily stopped as in the monochrome reading mode. FIG. 5 shows that reading is temporarily stopped after reading the nth line. When the reading of the document is temporarily stopped, the step-up signal StS is not generated. However, in order to output the image data ImD (R), ImD (G), ImD (B) of the nth line, the horizontal synchronization signals HoS (R), HoS (G), HoS (B) and the enable signal EnS are output. (R), EnS (G), and EnS (B) are generated one each. Thereafter, the horizontal synchronization signal and the enable signal are not generated.

  When the image data temporarily stored in the buffer memory 80 is emptied and the reading is resumed, the reading control unit 60 moves the carriage 201 backward in the sub-scanning direction as in the monochrome reading mode. Thus, the reading of the original is resumed from the position where the original reading is stopped. FIG. 6 shows that reading of a document is resumed from the (n + 1) th line. When the image sensor 21 is positioned on the (n + 2) th line, the image data ImD (R), ImD (G), and ImD (B) of the (n + 1) th line are output. Accordingly, the image data output when the image sensor 21 is positioned on the (n + 1) th line is discarded.

  The operation of the document reading apparatus 2a according to the first embodiment will be described with reference to FIGS. FIG. 7 is a flowchart for explaining this operation.

  When the operator sets a document on the document table 203 shown in FIG. 1 and operates the start key 405, the reading control unit 60 starts reading the document in the flat bed mode (step S1). The image sensor 21 reads a document line by line and outputs analog image data ImD. The analog image data ImD is converted into digital image data ImD by the AD converter 49, and the digital image data ImD is subjected to predetermined processing by the image processing unit 70 and then temporarily stored in the buffer memory 80.

  The reading control unit 60 determines whether or not the image data ImD temporarily stored in the buffer memory 80 is full (step S2). If the reading control unit 60 does not determine that the image data ImD temporarily stored in the buffer memory 80 is full (No in step S2), the image sensor 21 continues to read the original (step S3). Then, the process returns to step S2.

  When the reading control unit 60 determines that the image data ImD temporarily stored in the buffer memory 80 is full (Yes in step S2), reading of the document is temporarily stopped (step S4).

  The reading control unit 60 determines whether or not the image data ImD temporarily stored in the buffer memory 80 is empty (step S5). If the reading control unit 60 does not determine that the image data ImD temporarily stored in the buffer memory 80 has become empty (No in step S5), the process returns to step S4.

  When the reading control unit 60 determines that the image data ImD temporarily stored in the buffer memory 80 has become empty (Yes in step S5), it resumes reading the document (step S6).

  The reading control unit 60 determines whether or not the reading of the document has been completed (step S7). If the reading control unit 60 does not determine that the reading of the document has been completed (No in step S7), the process returns to step S3. If the reading control unit 60 determines that the reading of the document has ended (Yes in step S7), the reading of the document ends.

  The main effects of the first embodiment will be described. In the first embodiment, the step-up signal StS is generated in synchronization with the pulse signal PuS, and the horizontal synchronization signal HoS is generated in synchronization with the step-up signal StS. Accordingly, the horizontal synchronization signal HoS used for reading the document is generated in synchronization with the pulse signal PuS. The pulse signal PuS is a signal for controlling the rotation angle of the motor 10 that generates power for moving the carriage 201 in the sub-scanning direction. Thus, according to the first embodiment, the horizontal synchronization signal HoS used for reading the document is generated in synchronization with the pulse signal PuS for controlling the rotation angle of the motor 10. Accordingly, the accuracy of matching the reading restart position with the reading stop position can be improved, so that the joints of the images can be prevented from shifting.

  If the horizontal synchronization signal HoS is not synchronized with the pulse signal PuS that controls the rotation angle of the motor 10, the width of one line read by the image sensor 21 varies when the rotation speed of the motor 10 varies. If the horizontal synchronization signal HoS is synchronized with the pulse signal PuS that controls the rotation angle of the motor 10 as in the first embodiment, the position at which each line is read varies even if the rotation speed of the motor 10 varies. Therefore, the width of one line can be constant. Therefore, the document can be read without the width of one line extending or contracting from the leading edge to the trailing edge of the document.

  In the first embodiment, the step-up signal StS is generated in synchronization with the pulse signal PuS. In monochrome reading, as shown in FIG. 4, an enable signal EnS (G) that defines a lighting-enabled period of the green light source 23G is generated in synchronization with the step-up signal StS. In color reading, as shown in FIG. 5 and FIG. 6, an enable signal EnS (R) that defines the lighting possible period of the red light source 23R is generated in synchronization with the step-up signal StS. Since the enable signals EnS (G) and EnS (R) are generated in synchronization with the pulse signal PuS in this way, the enable signals EnS (G) and EnS (R) are generated in synchronization with the horizontal synchronization signal HoS. Can do. In color reading, the enable signal EnS (G) of the green light source 23G is generated in synchronization with the horizontal synchronization signal HoS (G), and the enable signal EnS (B) of the blue light source 23B is generated by the horizontal synchronization signal HoS (B ) Is generated in synchronization with Therefore, in monochrome reading and color reading, it is possible to prevent the light source 23 from being turned on before the horizontal synchronization signal HoS is generated.

  When a DC motor is used as the motor 10, the following effects are produced. In the DC motor, the rotation speed is controlled by feedback control using a pulse signal (pulse signal PuS for controlling the rotation angle of the motor 10) output from the encoder. For this reason, since the frequency of the pulse signal output from the encoder changes, when the DC motor is applied in the first embodiment, a slight deviation occurs in the interval of the horizontal synchronization signal HoS. According to the first embodiment, the lighting possible period defined by the enable signals EnS (R), EnS (G), EnS (B) is shorter than the cycle of the horizontal synchronization signal HoS, and the enable signals EnS (R), EnS (G) and EnS (B) are generated in synchronization with the horizontal synchronization signal HoS. For this reason, even if a slight deviation occurs in the interval of the horizontal synchronization signal HoS, the enable signals EnS (R), EnS (G), EnS (B) generated in synchronization with a certain horizontal synchronization signal HoS are the next horizontal signals. It is possible to prevent the period of the synchronization signal HoS from being straddled. Therefore, in reading each line, the lighting time of the light source 23 can be made constant. Therefore, the amount of light accumulated in the image sensor 21 by reading each line can be kept constant, so that the image quality of the read original image can be improved.

  In the first embodiment, when reference data (for example, white reference or black reference data) used to correct image data is acquired by the image sensor 21, the carriage 201 is fixed without being moved in the sub-scanning direction. For this reason, since the motor 10 is not driven, the pulse signal generator 33 does not generate the pulse signal PuS. Therefore, the first horizontal synchronization signal generation unit 43 cannot generate the horizontal synchronization signal HoS.

  Therefore, when the image sensor control unit 40 does not move the carriage 201 in the sub-scanning direction and causes the image sensor 21 to acquire reference data used for image data correction, the second horizontal synchronization signal generation unit 45 shown in FIG. The image sensor 21 is caused to acquire reference data using the generated horizontal synchronization signal HoS. The second horizontal synchronization signal generation unit 45 generates a horizontal synchronization signal HoS using the clock generated by the clock generation unit 41 as an original clock. The enable signal generation unit 53 generates an enable signal in synchronization with the horizontal synchronization signal HoS generated by the second horizontal synchronization signal generation unit 45. As described above, acquisition of white reference and black reference data is realized.

  A second embodiment of the present invention will be described with a focus on differences from the first embodiment. The document reading apparatus according to the second embodiment differs from the document reading apparatus 2 according to the first embodiment shown in FIG. 3 in the functions of the light source control unit 50 and the reading control unit 60.

  In the second embodiment, the light source controller 50 enables the enable signals EnS (R), EnS (G), EnS (B) when the carriage 201 moves at a constant speed in the sub-scanning direction, when moving at a reduced speed, and when moving at an accelerated speed. ) Is controlled to have the same occurrence period. In other words, the light source control unit 50 uses a part of the period from the generation of the horizontal synchronization signal HoS to the generation of the next horizontal synchronization signal HoS as the lighting time of the light source 23, and the carriage 201 moves at a constant speed in the sub-scanning direction. In the case of decelerating movement and acceleration movement, the lighting time is controlled to be the same.

  In the second embodiment, the reading control unit 60 performs the following operations (a) to (d) by controlling the movement control unit 30, the image sensor control unit 40, and the light source control unit 50.

  The operation (a) is an operation for causing the image sensor 21 to read a document while moving the carriage 201 at a constant speed in the sub-scanning direction.

  The operation (b) is an operation of causing the image sensor 21 to read the original while moving the carriage 201 at a reduced speed in the sub-scanning direction when the image data temporarily stored in the buffer memory 80 becomes full during reading of the original. is there.

  The operation (c) is an operation for stopping the reading of the document by stopping the movement of the carriage 201 in the sub-scanning direction after the decelerating movement.

  In the operation (d), when the reading of the document is resumed, the carriage 201 is not moved backward in the sub-scanning direction, and the carriage 201 is accelerated in the sub-scanning direction from the position where the movement of the carriage 201 is stopped. This is an operation for resuming the reading of the document from the position where the movement is stopped.

  In the second embodiment, a reading operation when the image data temporarily stored in the buffer memory 80 becomes full during reading of a document will be described. FIG. 8 is a time chart showing the first half of the reading operation in the monochrome reading mode. FIG. 9 is a time chart showing the latter half of the reading operation in the monochrome reading mode.

  If the image data temporarily stored in the buffer memory 80 shown in FIG. 3 becomes full during reading of the original, and the reading is temporarily stopped, the motor 10 is slowed down to move the carriage 201 from a constant speed to a reduced speed. And the carriage 201 is stopped. When resuming reading, the motor 10 is slowed up to accelerate the carriage 201. When the carriage 201 reaches the target speed, the carriage 201 is switched from the acceleration movement to the constant speed movement. Control of deceleration movement and acceleration movement of the carriage 201 is an important control in order to prevent step-out when the motor 10 is a stepping motor.

  If the frequency of the step-up signal StS at the constant speed movement of the carriage 201 is, for example, 5.0 kHz, the cycle T1 for reading one line is 200 μs. When the motor 10 is slowed down and the carriage 201 is decelerated and stopped in two steps, for example, if the frequency of the step-up signal StS in the deceleration movement of the carriage 201 is set to 2.5 kHz and 1.0 kHz, for example, one line Read periods T2 and T3 are 400 μs and 1000 μs, respectively. When the motor 10 is slowed up from the stopped state of the carriage 201 and the carriage 201 is accelerated, for example, in two stages and switched to a constant speed, the frequency of the step-up signal StS in the acceleration movement of the carriage 201 is set to 2.5 kHz, for example. Assuming 1.0 kHz, the reading cycles T2 and T3 for one line are 400 μs and 1000 μs, respectively.

  The period T0 of the enable signal EnS (G) is constant (for example, 100 μs) when the carriage 201 is moved at constant speed, deceleration, and acceleration. This is because a part of the period from the generation of the horizontal synchronization signal HoS to the generation of the next horizontal synchronization signal HoS is set as the lighting time of the light source 23, and the carriage 201 moves at a constant speed in the sub-scanning direction or moves at a reduced speed. In the case of acceleration movement, it means that the lighting time is the same. Thereby, in reading each line, the amount of light accumulated in the image sensor 21 can be kept constant (the same amount of light), so that the image quality of the line read during the slowing movement and the accelerating movement can be reduced. The image quality of the line read when moving at a constant speed can be made the same.

  When the cycle for reading one line is 200 μs (in the case of cycle T1), the duty of the enable signal EnS (G) is 50%. When the period for reading one line is 400 μs (when the period is T2), the duty of the enable signal EnS (G) is 25%. When the cycle for reading one line is 1000 μs (in the case of cycle T3), the duty of the enable signal EnS (G) is 10%. Therefore, the duty of the enable signal EnS (G) becomes lower as the period for reading one line becomes longer.

  The document is read by the image sensor 21 by moving the carriage 201 at a constant speed in the sub-scanning direction. In the second embodiment, a document is further read by the image sensor 21 during the deceleration movement and the acceleration movement. As a result, when the reading of the document is resumed, the movement of the carriage 201 is stopped while the carriage 201 is accelerated in the sub-scanning direction from the position where the movement of the carriage 201 is stopped without retreating the carriage 201 in the sub-scanning direction. The reading of the document can be resumed from the position where it was placed.

  As described above, according to the second embodiment, when the reading of the document is resumed, the document reading is resumed from the position where the movement of the carriage 201 is stopped without moving the carriage 201 back in the sub-scanning direction. Therefore, when resuming the reading of the document, the reading of the document is temporarily stopped compared to the method of resuming the reading of the document from the document reading stop position by moving the carriage 201 backward after moving in the sub-scanning direction. The time from reading to restart of reading can be shortened.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Document reading apparatus 10 Motor 21 Image pick-up element 23 Light source 30 Movement control part 40 Image pick-up element control part 41 Clock generation part 43 1st horizontal synchronizing signal generation part 45 2nd horizontal synchronizing signal generation part 50 Light source control part 53 Enable Signal Generating Unit 60 Reading Control Unit 80 Buffer Memory

Claims (4)

An image sensor that reads a document line by line along the main scanning direction;
A stepping motor that generates power to move the document relatively in the sub-scanning direction;
A pulse signal generator for generating a pulse signal used for driving the stepping motor, and a step-up signal indicating that the original has moved by one pixel in the sub-scanning direction are generated in synchronization with the pulse signal. A movement control unit for controlling the movement of the document in the sub-scanning direction,
An image sensor control unit that controls the operation of the image sensor, including a first horizontal sync signal generator that generates a horizontal sync signal in synchronization with the step-up signal;
A storage unit that temporarily stores image data output from the image sensor by the image sensor reading the original;
An operation of causing the image sensor to read the document using the horizontal synchronization signal generated by the first horizontal synchronization signal generation unit while relatively moving the document in the sub-scanning direction, while reading the document When the image data temporarily stored in the storage unit exceeds a predetermined amount, the operation of temporarily stopping reading of the document and stopping the document from relatively moving in the sub-scanning direction; and When resuming the reading of the original, the movement control unit performs an operation of restarting the reading of the original from the reading stop position of the original by moving the original relatively backward in the sub-scanning direction and then moving forward. And a reading control unit executed by controlling the imaging element control unit ,
The step-up signal generation unit is an original reading apparatus that does not generate the step-up signal in the case of the pulse signal that reversely rotates the stepping motor . A light source for irradiating the document with light;
A light source control unit for controlling lighting of the light source,
The light source control unit includes an enable signal generation unit that defines a lighting possible period of the light source and generates an enable signal whose lighting possible period is shorter than a period of the horizontal synchronization signal in synchronization with the pulse signal. The document reading apparatus according to 1. The imaging element control unit includes a clock generation unit that generates a clock signal, and a second horizontal synchronization signal generation unit that generates the horizontal synchronization signal in synchronization with the clock signal,
The image sensor control unit is generated by the second horizontal synchronization signal generation unit when the image sensor acquires reference data used for correcting image data without relatively moving the document in the sub-scanning direction. document reading apparatus according to claim 1 or 2 to obtain the reference data on the imaging device by using the horizontal synchronizing signal. Document reading apparatus according to any one of claims 1 to 3 having an interface capable of connecting the image data of the document to a network for transferring to a destination that has been read by the image sensor.

Images