JP2021153274A - Image reading device - Google Patents

Abstract

To read a background area at a high speed in document reading to improve throughput of reading.SOLUTION: An image reading device irradiates with light a line at the current position of a document with a first light source, receives reflected light thereof with an image sensor, irradiates with light a line located in front of the line of the current position of the document with a second light source, and receives reflected light thereof with the image sensor, and the image reading device has: light source control means that turns on, in a line sequential manner, first LED owned by the first light source and a second LED owned by the second light source for each of the colors; and image determination means that determines whether the line is a background or other than the background from data obtained through reception of the light from the second light source. The image reading device changes the moving speed of a carriage from a result of the determination, and changes the line determined to be other than the background to first carriage movement control and the line determined to be the background to second carriage movement control.SELECTED DRAWING: Figure 3

Description

The present invention relates to a technique for reading an image of a document.

Currently, a multifunction printer (MFP) having a scanner unit, a printer unit, and the like is widely used as an image processing device. The scanner unit of the MFP is provided with an image sensor such as a CCD or CIS (contact image sensor) on the scanner head. The printer section of the MFP is composed of an inkjet printer and a laser printer.

The CPU of the MFP, the image processing circuit, etc. perform image processing on the digital image data generated by the scanner unit of the MFP reading the image, and the printer unit prints the image using the processed digital image data. As a result, the MFP realizes the copy function.
The MFP generally includes a memory allocated to three areas: an input buffer for storing digital image data, an image processing memory for image processing, and an output buffer for storing output data for printing.

However, according to the demands of users and the like, MFPs that perform higher image quality and higher speed reading and scanning are required.

The image processing apparatus of Patent Document 1 refers to a document when the detection amount of the background area detected continuously with the background area detecting means for detecting the background area of the scanned document exceeds a predetermined background document determination reference amount. It is an image reading device provided with a reading control means for performing skip-reading processing.

Further, the document scanning means is provided for scanning the document placed on the platen on the scanner carriage to scan the document, and the document scanning means usually determines the scanning speed of the scanner carriage at the time of detecting the base area. When the scanning speed is set to be higher than the scanning speed at the time of reading and the non-ground region is detected during the detection of the ground region by the ground region detecting means, the scanner carriage is returned and the normal position is started from the detection start position of the non-ground region. The document is scanned at the scanning speed at the time of scanning.

Japanese Unexamined Patent Publication No. 2012-222791

However, in Patent Document 1, even if the background is scanned at high speed, if characters are detected, the switchback must be performed. Therefore, depending on the type of the original, the number of switchbacks increases and the throughput effect becomes small. ..

An object of the present invention is to provide an image reader capable of suppressing switchback that occurs when a non-underground region is detected and reducing a decrease in throughput.

In order to achieve the above object, the image reading device of the present invention reads the image of the document line by line by moving the carriage equipped with the image sensor and the light source relative to the sub-scanning direction of the document by a motor. An image reading device, wherein the image reading device includes a first light source that illuminates the current position line of the document, a first image sensor that receives reflected light from the current position line, and more than the current position line. A second light source arranged so that the reflected light can be received by the first image sensor with respect to a line located forward in the moving direction of the carriage, and the first light source and the second light source are sometimes used. Depending on the results of the light source control means that lights up in division, the image determination means that determines whether or not the line is the background by the image sensor output obtained by the irradiation light from the second light source, and the result of the image determination means. The movement speed of the carriage is switched, and the line determined to be other than the base is switched to the first carriage movement control, and the line determined to be the base is switched to the second carriage movement control. The control is characterized in that the movement speed of the carriage is faster than that of the first carriage movement control.

According to the present invention, it is possible to suppress switchback that occurs when a non-underground region is detected, that is, to reduce a decrease in throughput.

It is a schematic block diagram of the MFP. It is a block diagram of a scanner unit. It is an electric block diagram of the image reading apparatus of Embodiment 1. FIG. It is a figure which shows the light source irradiation to the current line M and the reflection in a document in the normal mode of Embodiment 1. FIG. It is operation timing chart of CIS in the normal mode of Embodiment 1. FIG. It is a figure which shows the light source irradiation to the current line M and the look-ahead line N in the normal drive of the look-ahead mode of Embodiment 1, and the reflection in a document. FIG. 5 is an operation timing chart of the CIS in the normal drive of the look-ahead mode of the first embodiment. It is a figure which shows the light source irradiation to the look-ahead line N and the document in the high-speed drive of the look-ahead mode of Embodiment 1. FIG. It is an operation timing chart of CIS in the high-speed drive of the look-ahead mode of Embodiment 1. It is an overall flowchart of a scanning operation. It is a flowchart of a document reading process. It is a flowchart of the groundwork determination process at the time of normal drive. It is a flowchart of the groundwork determination process at the time of high-speed driving. It is a flowchart of the background / image determination process. It is a figure which shows an example of a manuscript. It is a figure which shows the operation example when the document of FIG. 15 is read in the look-ahead mode. It is a figure which shows an example of a document (when the base area is narrower than the distance dL between the current line M and the look-ahead line N). It is a figure which shows the operation example when the document of FIG. 15 is read in the look-ahead mode. It is a figure which shows an example of a document (when the document area is narrower than the distance dL between the current line M and the look-ahead line N). It is a figure which shows the operation example when the document of FIG. 19 is read in the look-ahead mode. It is an electric block diagram of the image reading apparatus of Embodiment 2. It is a figure which shows the light source irradiation to the current line M and the reflection in a document in the normal mode of Embodiment 2. FIG. It is an operation timing chart of CIS in the normal mode of Embodiment 2. It is a figure which shows the light source irradiation to the current line M and the look-ahead line N in the normal drive of the look-ahead mode of Embodiment 2, and the reflection in a document. It is an operation timing chart of CIS in the normal drive of the look-ahead mode of Embodiment 2. It is a figure which shows the light source irradiation to the look-ahead line N and the document in the high-speed drive of the look-ahead mode of Embodiment 2. It is an operation timing chart of CIS in the high-speed drive of the look-ahead mode of Embodiment 2. It is an overall flowchart of the scanning operation of Embodiment 2.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The relative arrangement of each component of the device used in this embodiment, the shape of the device, and the like are merely examples, and the present invention is not limited to these.

<< Embodiment 1 >>
<Overall MFP configuration>
FIG. 1 is a schematic configuration diagram of an MFP 100 which is an example of an image reading device according to the present embodiment. In FIG. 1, an MFP having a reading function and a printing function will be described as an example, but the image reading device is not limited to this. It may be an image reading device having only an image reading function, or an MFP having a FAX function or the like.

As shown in FIG. 1, the MFP 100 includes a mechanism control circuit 109, an ASIC (Application Specific Integrated Circuit) 110, and a ROM (Read Only Memory) 112. It also has a RAM (Random Access Memory) 113 and an EEPROM (Electrically Erasable Programmable Read-Only Memory) 114. It also has a memory card 115, an operation unit 116, an I / F (InterFace) 117, and an I / F 119. These are each connected by a system bus.

Further, the MFP 100 has a recording head control circuit 102 and a scanner unit 103 connected to the ASIC 110. Further, the MFP 100 has a recording head 101 connected to the recording head control circuit 102. Further, the MFP 100 has a head carriage motor 105, a transfer motor 106, and sensors 108 connected to the mechanism control circuit 109.

The ASIC 110 includes a CPU (Central Processing Unit) 111 and a read control unit 121, and controls the operation of each unit of the MFP 100 as a whole. The CPU 111 is a central processing unit in the form of a microprocessor (microcomputer), and controls the operation of the entire MFP 100 by executing a program or starting hardware. The reading control unit 121 controls the LED of the CIS (Contact Image Sensor) module, the image sensor, the AFE (Analog Front End) described later, and the motor drive.

The ROM 112 stores a program corresponding to the processing procedure executed by the ASIC 110. The RAM 113 is used as a work area of the CPU 111, and temporarily stores parameters and image data for the ASIC 110 to execute a processing procedure. The EEPROM 114 stores the state of the recording head 101 even when the power of the MFP 100 is turned off. The memory card 115 stores image data and the like taken by a digital camera or the like.

The operation unit 116 is for the user to perform various operations, and includes, for example, a hard key and a display unit for presenting (notifying) various information to the user. Examples of the display unit include a display unit including a touch panel. Further, a sound generator or the like may be provided so that various information can be presented to the user by outputting sound (buzzer, sound, etc.) based on acoustic information.

Further, the I / F 117 and the I / F 119 are interfaces with an external device. For example, a PC (Personal Computer) 118 is connected via the I / F 117. Further, an external device 120 such as a digital camera or an optical disk is connected via the I / F 119. Image data can be input and output between the MFP 100 and the external device via the I / F 117 and I / F 119.

The recording head control circuit 102 electrically controls the recording head 101 and generates a drive pulse for ejecting ink based on the image data. The scanner unit 103 is a so-called scanning unit that reads an image. The details of the configuration of the scanner unit 103 will be described later.

The mechanism control circuit 109 is a circuit that controls and manages various motors and sensors. The head carriage motor 105 is a motor for moving the head carriage. The head carriage is equipped with a recording head 101 and ink tanks of each color, and ejects ink droplets onto recording paper while moving along a shaft supporting the head carriage in a direction orthogonal to the transport direction for recording. I do. In the present embodiment, the recording unit for transporting the head carriage in the direction intersecting the transport direction has been described as an example, but the recording unit is not limited to this, and the recording unit is not limited to this, for example, along the transport direction. It may have a line head having a nozzle row of each color. The transport motor 106 is a motor for transporting the recording medium. The sensors 108 are sensors for monitoring the operating state of the recording unit and the scanner unit.

<Explanation of scanner unit>
FIG. 2 is a diagram illustrating the configuration of the scanner unit 103. The CIS205 is a module equipped with a contact image sensor and an LED (Light Emitting Diode) light source for illuminating a document. The white reference plate 200 is a white reference plate for performing shading correction, dimming treatment, and the like. The DC motor 206 is a motor that is a drive source for the CIS 205. The shaft 204 is a shaft for moving the CIS 205. The pressure plate 203 is a pressure plate for blocking light other than the LED light source when reading the image data of the document placed on the platen glass 202. The white reference plate 200 is attached to the platen glass 202.

The CIS 205 and the DC motor 206 are connected to a circuit board (not shown) on which the ASIC 110, ROM 112, RAM 113, etc. are mounted by a cable (not shown) such as a flat cable. The CIS 205 is moved and controlled in the first direction (secondary scanning direction) along the shaft 204 by driving the DC motor 206. Further, the CIS 205 is arranged so as to extend in a second direction (main scanning direction) intersecting with the first direction. The CIS 205 moves in the first direction (secondary scanning direction) while reading the area from one end to the other end of the document reading area in the second direction (main scanning direction). In this way, the CIS 205 reads the original image in the original reading area for each line in the first direction.

<Explanation of the configuration of the image reader>
FIG. 3 is a diagram illustrating an electrical configuration related to a configuration that functions as an image reader 300 of the MFP 100. The scanner unit 103 includes a CIS 205, an AFE 330, a drive unit 350, and a motor driver 352. The reading control unit 121 of the ASIC 110 includes a reading signal processing unit 360, a light source control unit 361, an encoder processing unit 362, a motor control unit 363, a horizontal synchronization signal (SH) generation unit 404, a sensor control unit 365, and an image determination unit 366. Have.

The CIS 205 includes a first light source 301 and a second light source 302 for irradiating a document with light, a first lens array 303 arranged on a line, a first image sensor 304 arranged in a line, and the like. .. The first light source 301 is composed of the first LED 305 and the first light guide body 306, and the first LED 305 corresponds to the three primary colors of light, R color (Red) LED, G color (Green) LED, and B color. It is configured to include a (Blue) LED. The first LED 305 is turned on during the document reading operation, and the light emitted from the first LED 305 irradiates the M line, which is the current reading line (defined as the current line) in the document, via the first light guide 306. do.

The second light source 302 is composed of a second LED 307 and a second light guide body 308, and the second LED 307 corresponds to the three primary colors of light: R color (Red) LED, G color (Green) LED, and B color. It is configured to include a (Blue) LED. The second LED 307 is turned on during the document reading operation, and the light emitted from the second LED 308 is a line (defined as a look-ahead line) that advances dL line ahead of the current line via the second light guide. Irradiate the N line. In the first image sensor 304, a plurality of light receiving pixels including a photodiode (light receiving element) are arranged side by side in a line. The light reflected from the document surface enters the photodiode of the first image sensor 304 via the first lens array 303, and the first image sensor 304 stores the charge obtained by photoelectrically converting the incoming light with the photodiode for a predetermined time. Then, after voltage conversion, it is output as an image signal.

The image signal output from CIS205 is input to AFE (Analog Front End) 330. The AFE330 samples the input image signal, adjusts the gain and offset, performs analog-to-digital conversion (A / D conversion), and outputs the signal to the reading signal processing unit 360 of the ASIC 110. The reading signal processing unit 360 performs image processing such as packing of the input image signal, shading correction of the image signal, and color correction. Then, the image data is stored in the image memory 368 or the line memory 369 arranged in the RAM 113.

The image memory 368 can store image data of all lines of R (Red) color, G (Green) color, and B color (Blue), and the image data of each color of the current line M is the current image memory 368 of each color. It is stored in the address corresponding to the line M. The line memory 369 can store one line of image data, and is stored in the line memory 369 in the look-ahead line N. The image data stored in the line memory 369 is read from the image determination means 366, and the image determination means 366 determines from the image data of the look-ahead line N whether the look-ahead line N is a base or an image. The details of the determination will be described later.

The drive unit 350 includes a DC motor 206, an encoder 351 and the like. The DC motor 206 is a drive source that scans the CIS 205 in the first direction (secondary scanning direction) in the document reading region. The encoder 351 is, for example, an optical rotary encoder. When the DC motor 206 rotates a predetermined number of times (that is, the CIS 205 is scanned for a certain distance in the sub-scanning direction), an encoder pulse is output from the encoder 351. The encoder pulse is output according to the rotation speed of the DC motor 206, and is for detecting the driving amount of the DC motor 206, that is, the moving amount of the CIS 205 moving. The encoder pulse is input to the encoder processing unit 362. The encoder processing unit 362 counts the encoder pulses, generates a line synchronization signal when the count number corresponding to one line is reached, and outputs the line synchronization signal to the SH generation unit 364. The interval of this line synchronization signal corresponds to the reading time (line time) of one line. The line counter 367 in the SH generation unit 364 counts the number of read lines by counting the input line synchronization signal. Further, the CPU 111 applies feedback control to the motor control unit 363 so that it can scan at the target speed by using the position information (count number of encoder pulses) and the speed information (pulse interval) obtained by the encoder processing unit 362. The motor control unit 363 performs PWM (Pulse Width Modulation) control of the current supplied from the motor driver 352 to the DC motor 206.

<CIS configuration and operation>
The image reading device 300 of the present embodiment has a "normal mode" in which the current line M is read using only the first light source 301, and a look-ahead line in which the current line M is read using the first light source 301 and the second light source 302 is used. It has a "look-ahead mode" mode for reading N. Further, in the look-ahead mode, the moving speed of the CIS 205 in the sub-scanning direction and the method of reading one line of the CIS 205 are switched between two driving methods, "normal drive" and "high-speed drive", according to the state of the document described later. .. The switching conditions between normal drive and high-speed drive will be described later.

FIG. 4 is a diagram showing light source irradiation on the current line M and reflection on the document in the normal mode. The central axis of the first lens 500 is located in the normal direction of the current line M of the document, and when reading the current line, the first lens 500 reflects the most light in the normal direction of the current line M of the document. The light guide body 306 is arranged. The details will be described later, but the current line M is read in a time-division manner in the order of G color (Green) → B color (Blue) → R color (Red). The second light guide 308 is not used in the normal mode. The arrangement of the second light guide 308 will be described later. Further, the light that has passed through the first lens 500 enters the first image sensor 304. FIG. 5 shows an operation timing chart of CIS205 in the normal mode.

The encoder processing unit 362 outputs a line synchronization signal when the encoder pulse reaches a count number corresponding to one line set in advance by a register or the like. The line synchronization signal is input from the encoder processing unit 362 to the SH generation unit 364, and the number of lines is incremented by the line counter 367. The line synchronization signal input to the SH generation unit 364 is multiplied by a predetermined number as a horizontal synchronization signal (SH) in the SH generation unit 364. This horizontal synchronization signal (SH) is a reading synchronization signal used for reading control. The generated horizontal synchronization signal (SH) is input to the reading signal processing unit 360, the light source control means 361, and the sensor control unit 365. FIG. 5 shows an example of multiplying by three. In the present embodiment, a monochrome line sensor is used as the first image sensor 304. Therefore, at the time of color reading, the first LED 305 is turned on in the order of G color (Green) → B color (Blue) → R color (Red) to accumulate the charge of the first image sensor 304. There is. The multiplication factor is not limited to this. The multiplication number can be set by a register or the like.

The SH generation unit 364 first generates a horizontal synchronization signal (SH) at the timing when the line synchronization signal is input (corresponding to the signal in the portion “a” in FIG. 5). Next, the SH generation unit 364 generates a horizontal synchronization signal (SH) after the period Tsp (reading cycle) of the horizontal synchronization signal (SH) has elapsed (corresponding to the signal in the “b” portion of FIG. 4). Next, the SH generation unit 364 generates a horizontal synchronization signal (SH) after the period Tsp of the horizontal synchronization signal (SH) has elapsed (corresponding to the signal in the portion “c” in FIG. 5).

Further, the SH generation unit 364 generates a horizontal synchronization signal (SH) at the timing when the next line synchronization signal is input (corresponding to the signal in the portion “d” in FIG. 5). The period Tsp of the horizontal synchronization signal (SH) can be set by a register or the like, and is usually set according to the drive speed of the carriage or the multiplication factor from the line synchronization signal. However, the period Tsp of the horizontal synchronization signal (SH) needs to secure a period that can secure the minimum time required for charge accumulation and output of the first image sensor 304.

Hereinafter, the period from the time when the horizontal synchronization signal of the “a” part in FIG. 5 is generated to the time when the horizontal synchronization signal of the “b” part is generated is referred to as an ab section. Similarly, the period from the time when the horizontal synchronization signal of the “b” part in FIG. 5 is generated to the time when the horizontal synchronization signal of the “c” part is generated is referred to as a bc section. Further, the period from the time when the horizontal synchronization signal of the "c" part in FIG. 5 is generated to the time when the horizontal synchronization signal of the "d" part is generated is referred to as a cd section.

The ab section of FIG. 5 is a G color accumulation section in the M line and an R color output section accumulated in the previous cycle (M-1 line). In the section ab of FIG. 5, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) output from the SH generation unit 364, and lights the first G-color LED 305 for a certain period of time. The bc section in FIG. 5 is the B color accumulation section in the M line, and the G color output in the M line accumulated in the previous cycle (the cycle corresponding to the ab section in FIG. 5). It is a section. In the section bc of FIG. 5, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) and lights the first LED 305 of color B for a certain period of time.

The cd section of FIG. 5 is the R color accumulation section in the M line, and the B color output in the M line accumulated in the previous cycle (the cycle corresponding to the bc section of FIG. 5). It is a section. In the cd section of FIG. 5, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) and lights the first LED 305 of the R color for a certain period of time. The R color of the Mth line accumulated in the cd section is output in the next cycle. The lighting time of each color of the first LED 305 is determined by the dimming control. Since the dimming control is a general control, the description thereof will be omitted. The second LED 307 is not used in the normal mode.

FIG. 6 is a diagram showing light source irradiation and reflection on the document to the current line M and the look-ahead line N in the normal drive of the look-ahead mode. The arrangement of the first lens 500, the first light guide body 306, and the first image sensor 304 is the same as that in FIG. In the present embodiment, in the look-ahead line reading, the second light guide body is irradiated within the viewing angle of the first lens 500 by irradiating the look-ahead line N located at a position advanced by the dL line from the current line M. Place 308. The details will be described later, but the reading of the current line M and the look-ahead line N is time-divisioned as G color (Green) of the current line M → B color (Blue) of the current line M → R color (Red) of the current line M → look-ahead. The GY color (Gray) line of line N is read in sequence.

FIG. 7 shows an operation timing chart of the CIS 205 in the normal drive in the look-ahead mode. The line synchronization signal generation and line counting are the same as in FIG. The line synchronization signal input to the SH generation unit 364 is multiplied by a predetermined number as a horizontal synchronization signal (SH) in the SH generation unit 364. At the time of color reading, in addition to the R color (Red) → G color (Green) → B color (Blue) of the current line M, the GY color (Gray) of the look-ahead line N is read sequentially in the first LED 305 and the second LED 307. Is turned on to accumulate the charge of the first image sensor 304. Therefore, in FIG. 7, it is multiplied by 4. The multiplication number can be set by a register or the like.

The SH generation unit 364 first generates a horizontal synchronization signal (SH) at the timing when the line synchronization signal is input (corresponding to the signal in the portion “a” in FIG. 7). Next, the SH generation unit 364 generates a horizontal synchronization signal (SH) after the period Tsp (reading cycle) of the horizontal synchronization signal (SH) has elapsed (corresponding to the signal in the “b” portion of FIG. 4). Next, the SH generation unit 364 generates a horizontal synchronization signal (SH) after the period Tsp of the horizontal synchronization signal (SH) has elapsed (corresponding to the signal in the portion “c” in FIG. 7).

Next, the SH generation unit 364 generates a horizontal synchronization signal (SH) after the period Tsp of the horizontal synchronization signal (SH) has elapsed (corresponding to the signal in the “d” portion of FIG. 7). Next, the SH generation unit 364 generates a horizontal synchronization signal (SH) at the timing when the next line synchronization signal is input (corresponding to the signal in the “d” part of FIG. 7). Further, the SH generation unit 364 generates a horizontal synchronization signal (SH) at the timing when the next line synchronization signal is input (corresponding to the signal in the “e” portion of FIG. 7). The method and operation of setting the period Tsp of the horizontal synchronization signal (SH) are the same as those described in FIG.

Hereinafter, the period from the time when the horizontal synchronization signal of the “a” part in FIG. 7 is generated to the time when the horizontal synchronization signal of the “b” part is generated is referred to as an ab section. Similarly, the period from the time when the horizontal synchronization signal of the “b” part in FIG. 7 is generated to the time when the horizontal synchronization signal of the “c” part is generated is referred to as a bc section. Further, the period from the time when the horizontal synchronization signal of the "c" part in FIG. 7 is generated to the time when the horizontal synchronization signal of the "d" part is generated is referred to as a cd section. Further, the period from the time when the horizontal synchronization signal of the "d" part in FIG. 7 is generated to the time when the horizontal synchronization signal of the "e" part is generated is referred to as a de-e section.

The ab section of FIG. 7 is an R color accumulation section in the M line and a GY color output section accumulated in the previous cycle (N-1 line). In the section ab of FIG. 7, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) output from the SH generation unit 364, and lights the first LED 305 of the R color for a certain period of time. The bc section in FIG. 7 is the G color accumulation section in the M line, and the R color output in the M line accumulated in the previous cycle (the cycle corresponding to the ab section in FIG. 7). It is a section. In the section bc of FIG. 7, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) and lights the first LED 305 of the G color for a certain period of time. The cd section of FIG. 7 is the B color accumulation section in the M line, and the G color output in the M line accumulated in the previous cycle (the cycle corresponding to the bc section of FIG. 7). It is a section.

In the cd section of FIG. 7, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) and lights the first LED 305 of the B color for a certain period of time. The de section in FIG. 7 is a GY color accumulation section in the Nth line, which is a look-ahead line, and is in the M line accumulated in the previous cycle (the cycle corresponding to the bc section in FIG. 7). This is the B color output section. In the cd section of FIG. 7, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) and lights the second LED 307 in the order of R color → G color → B color for a certain period of time to read GY color. conduct. Since the method of processing as GY color is very general, the description thereof will be omitted. The GY color of the Nth line accumulated in the d-e section is output in the next cycle. The lighting time of each color of the first LED 305 and the second LED 307 is determined by the dimming control. Since the dimming control is a general control, the description thereof will be omitted. In this embodiment, the feed resolution in the movement direction of the CIS 205 in the sub-scanning direction is set to 600 dpi in the normal drive in the look-ahead mode.

FIG. 8 is a diagram showing light source irradiation to the look-ahead line N and reflection on the document in the high-speed drive in the look-ahead mode. The arrangement of the first lens 500, the first light guide body 306, and the second light guide body 308 is the same as in FIG. Although the details will be described later, when reading the look-ahead line N, only the GY color (Gray) of the look-ahead line N is read.

FIG. 9 shows an operation timing chart of the CIS 205 in high-speed drive in the look-ahead mode. The line synchronization signal generation and line counting are the same as in FIG. The line synchronization signal input to the SH generation unit 364 is multiplied by a predetermined number as a horizontal synchronization signal (SH) in the SH generation unit 364. FIG. 9 shows an example in which multiplication is not performed. In the high-speed drive of the look-ahead mode, during color reading, only the gray color (defined as GY color) of the look-ahead line N is read, so only the second LED 307 is turned on and the charge of the first image sensor 304 is accumulated, so that the multiplication is not performed. The multiplication factor is not limited to this. The multiplication number can be set by a register or the like.

The SH generation unit 364 first generates a horizontal synchronization signal (SH) at the timing when the line synchronization signal is input (corresponding to the signal in the portion “a” in FIG. 9). Further, the SH generation unit 364 generates a horizontal synchronization signal (SH) at the timing when the next line synchronization signal is input (corresponding to the signal in the portion “b” in FIG. 9). The period Tsp of the horizontal synchronization signal (SH) can be set by a register or the like, and is set to a period that can secure the minimum time required for charge accumulation and output of the first image sensor 304. The period Tsp setting and operation of the horizontal synchronization signal (SH) are the same as those described in FIG.

Hereinafter, the period from the time when the horizontal synchronization signal of the “a” part in FIG. 9 is generated to the time when the horizontal synchronization signal of the “b” part is generated is referred to as an ab section.

The ab section of FIG. 9 is a GY color accumulation section in the Nth line and is a GY color output section accumulated in the previous cycle (N-1 line). In the section ab of FIG. 9, the light source control means 361 synchronizes with the horizontal synchronization signal (SH) output from the SH generation unit 364, and lights the second LED 307 for a certain period of time in the order of R color → G color → B color. By letting it read the GY color. Since the method of processing as GY color is very general, the description thereof will be omitted. The GY color of the Nth line accumulated in the ab section is output in the next cycle. In this embodiment, in the high-speed drive in the look-ahead mode, the feed resolution in the moving direction of the CIS 205 in the sub-scanning direction is set to 75 dpi. When the moving speed of CIS205 in the sub-scanning direction is increased by 8 times, the encoder processing unit 362 counts the number of counts corresponding to one line during normal driving so that the line time line is equivalent between normal driving and high-speed driving. Set with 8 times the count number.

<Flowchart>
FIG. 10 shows the overall flow of the scanning operation of the present embodiment. When a job such as scanning is issued, first, the first image sensor 304 is calibrated in S1000, and the first light source 301 is calibrated in step S1001. Calibration refers to dimming and shading correction, and since it is a general technique, its description is omitted. The job is sent by a method such as the user operating the PC 118 or the operation unit 116. When the look-ahead mode is selected (yes in S1002), the second light source 302 is calibrated in step S1003, and the process proceeds to the document reading process in step S1004. When the normal mode is selected (no in S1001), the process proceeds to the document scanning process in step S1004. The normal mode / look-ahead mode is selected by the user operating the PC 118 or the operation unit 116.

FIG. 11 shows a flowchart of the document scanning process S1004. In step S1100, the variables are set as follows. For variable setting, a scan of 600 dpi is taken as an example.

Normal drive sub-scan resolution reso_a = 600 [dpi]
High-speed drive sub-scan resolution reso_b = 75 [dpi]
Total number of lines L = 7016 lines (A4 manuscript 600 dpi)
Distance between the current line and the look-ahead line dL [line] = 13 lines (600 dpi)
Deceleration section kL [line] = 11 lines (600 dpi)
Current line count M = 0
Look-ahead line count N = M + dL-1
Speed flag = 0 (0: normal drive / 1: high speed drive)
Speed switching reservation flag = 0
Current sub-scan resolution reso = reso_a
In the normal mode (no in S1101), the process proceeds to step S1102. In step S1102, servo control is performed so that the movement of the CIS 205 in the sub-scanning direction becomes the target speed. At that time, the motor control unit 363 performs PWM control of the DC motor 206. The target speed during normal driving is set to be equivalent to 600 dpi, and reso = reso_a (600 dpi) is set. Then, the CIS 205 controls the light source control means 361 and the reading control unit 405 in synchronization with the signal of the encoder 351 so as to perform the control shown in FIG. 5 described above, and reads the current line M. The read image data of the current line M is stored in the address corresponding to the Mth line of the image memory 368, and the process proceeds to step S1109.

In the read-ahead mode (yes in S1101), transition to step S1103, if N <L-1 (yes in S1103), transition to step S1104, and if the speed flag = 0 (yes in S1104). The transition to step S1105. In step S1101, the user may be able to specify the normal mode / look-ahead mode on the operation unit 116, or the scan mode (high resolution setting or low resolution setting) may be automatically switched. In step S1105, servo control is performed so that the movement of the CIS 205 in the sub-scanning direction becomes the target speed. At that time, the motor control unit 363 performs PWM control of the DC motor 206. The target speed during normal driving is set to be equivalent to 600 dpi, and reso = reso_a (600 dpi) is set.

Then, the CIS 205 controls the light source control means 361 and the read control unit 405 in synchronization with the signal of the encoder 351 so as to perform the control shown in FIG. 7, and reads the current line M and the look-ahead line N. The read image data of the current line M is stored in the address corresponding to the Mth line of the image memory 368, and the image data of the look-ahead line N is stored in the address corresponding to the line memory 369. Then, after performing the groundwork determination process at the time of normal driving in step S1106, the process proceeds to step S1109. If the speed flag = 1 (no in S1104), the process proceeds to step S1107. In step S1107, in step S1107, servo control is performed so that the movement of the CIS 205 in the sub-scanning direction becomes the target speed. At that time, the motor control unit 363 performs PWM control of the DC motor 206. The target speed at the time of high-speed driving is set to correspond to 75 dpi, and reso = reso_b (75 dpi) is set.

Then, the CIS 205 controls the light source control means 361 and the read control unit 405 in synchronization with the signal of the encoder 351 so as to perform the control shown in FIG. 9, and reads the look-ahead line N. The image data of the look-ahead line N is stored in the address corresponding to the line memory 369. Then, after performing the groundwork determination process at the time of high-speed driving in step S1108, the transition to S1109 occurs. The look-ahead line N is represented by N = M + dL-1. If M ≠ L-1 (yes in S1109), the line count M is incremented according to M = M + reso_a / reso in step S1110 (1 line for normal drive, 8 lines for high speed drive). ), Transition to step S1104. When M = L-1 is reached (no in S1109), the scanning of the total number of lines L is completed, so the document scanning process is terminated.

If N <L-1 is not satisfied in step S1103 (no in S1103), the look-ahead line N has reached the total number of lines L, so no look-ahead is performed. If the speed flag = 0 and the speed switching reservation flag = 0 (yes in S1111), the process proceeds to step S1102 described above. If the speed flag = 0 (no of S1111), the remaining dL lines are not read, and the image data is used as the background data in step S1112 to the addresses corresponding to the tmp1 line to the L-1 line of the image memory 368. Interpolate in a stored form. When the image data is 16 bits for each color, the background data = 65535.

FIG. 12 shows a flowchart of the groundwork determination process during normal driving. In step S1200, a process of determining whether the look-ahead line N is a background or an image is performed, and if the background is determined in step S1201 (yes of S1201), the process proceeds to step S1202. If the speed switching reservation flag = 0 (yes in S1202), the line of the look-ahead line N used for the determination in step S1203 is stored in the temporary tmp1, and the speed switching reservation flag = 1 is set in step S1204. If the speed switching reservation flag = 1 in step S1202 (no in S1202), the process proceeds to step S1205.

If M = tp1 is not set in step S1205 (no in S1205), that is, if the current line M has not reached the look-ahead line N held in S1203, the groundwork determination process during normal driving is terminated. When M = tp1 (yes of S1205), that is, when the current line M reaches the look-ahead line N held in S1203, the speed switching reservation flag = 0 is reset in step S1206, and the speed flag = 1 is set in step S1207. Switching and ending the groundwork determination process during normal driving. When the look-ahead line N is image-determined in step S1201 (no in S1201), the process proceeds to step S1208. When the speed switching reservation flag = 0 in step S1208 (no in S1208), the groundwork determination process during normal driving is terminated. On the other hand, when the speed switching reservation flag = 1 in step S1208 (yes in S1208), the speed switching reservation flag = 0 is reset in step S1209, and the groundwork determination process during normal driving ends.

FIG. 13 shows a flowchart of the groundwork determination process during high-speed driving. In step S1300, the same pre-reading line N as in step S1200 is subjected to the determination process of whether the pre-reading line N is the background or the image, and when the pre-reading line N is image-determined in step S1301 (yes of S1301), the process proceeds to step S1302. When the speed switching reservation flag = 0 in step S1302 (yes in S1302), the line of the look-ahead line N used for the determination in step S1303 is stored in the temporary tmp2, and the speed switching reservation flag = 1 is set in step S1304. Then, the transition to S1305 occurs. When the look-ahead line N is ground-determined in step S1301 (no in S1301), the ground-based determination process during high-speed driving is terminated.

In step S1305, the background data is assigned to the address corresponding to the tmp1 line (start of the background) to the tp2-kL-1 line (the deceleration section of the movement of the CIS 205 in the sub-scanning direction is subtracted from the end of the background) of the image memory 368. To store. If the speed switching reservation flag = 1 in step S1302 (no in S1302), the process proceeds to step S1306. If M = tp2-kL-1 (no in S1306), that is, if the current line M has not reached the look-ahead line N held in S1303, the groundwork determination process at the time of high-speed driving is terminated. When M = tp2-kL-1 (yes of S1306), that is, when the current line M reaches the read-ahead line N held in S1303, the speed switching reservation flag = 0 is switched in step S1307, and the speed flag is flagged in step S1308. It is reset to = 0, reset to tp1 = 0 and tp2 = 0 in step S1309, and the groundwork determination process at the time of high-speed driving is completed.

FIG. 14 shows a flowchart of the background / image determination process. In step S1401, the background / image determination flag is reset, and in step S1402, the image determination means 366 counts the number of background pixels (HKS_ct) of the look-ahead line N. If the number of background pixels (HKS_ct) in step S1403 is larger than the number of background pixels (HKS_num) required for determining as a background line (yes in S1403), the background is determined in step S1404. If the number of background pixels (HKS_ct) is equal to or less than the number of background pixels (HKS_num) required for determining the background line (no in S1403), the image is determined in step S1405, and the background / image determination process is terminated.

<Operation example>
FIG. 15 is an example of a document, and is a diagram showing characteristic timings in document reading by (a) to (h). The shaded area is the image area and the white area is the background area. The broken line is the current line M, and the alternate long and short dash line is the look-ahead line N. FIG. 16 is a diagram showing the moving speed of the CIS 205 in the sub-scanning direction and the type of data (image data or background data) stored in the image memory when the document of FIG. 15 is read in the look-ahead mode.

In (a), it is the first line of the document, and the image reading device 300 is normally driven. In the look-ahead line N (= 12 lines), the background is determined, the background region start line tp1 = 12 lines is held, and the speed switching reservation flag = 1 is set. The carriage is driven at a normal drive speed, and the CIS 205 reads the current line M and the look-ahead line N in synchronization with the line synchronization signal generated from the encoder signal, and sequentially reads the image data of the current line M in units of one line in the image memory. It is stored in the address corresponding to the line M, and the groundwork determination process of the look-ahead line N is performed.

When the current line M = tp1 (= 12 lines) is reached in (b), the speed switching reservation flag = 0 is reset and the speed flag = 1 (high-speed drive) is switched. Then, the carriage is driven at a high-speed drive speed, and the CIS 205 reads the image of the look-ahead line N in synchronization with the line synchronization signal generated from the encoder signal, and performs the groundwork determination process in units of one line. The image data of the current line M is stored in the image memory up to 12 lines.

When the look-ahead line N = 2000 line (image area start line) is reached in (c), the tp2 = 2000 line is held and the speed switching reservation flag = 1 is set. Then, the background data is stored in the addresses corresponding to tp1 (= 12 lines) to tp2-kL-1 (= 1990 lines) in the image memory.

In (d), when the current line M = tp2-kL-1 (= 1990 line) is reached, the speed switching reservation flag = 0 is reset, and the speed flag = 0 (normal drive) is switched. The carriage decelerates at the deceleration acceleration for reaching the normal driving speed at the current line M = tp2 (= 2000 lines), and is driven at the normal driving speed after the 2000 lines in (e). The CIS 205 reads the current line M and the look-ahead line N in synchronization with the line synchronization signal generated from the encoder signal, reads the image data of the current line M in units of one line, and sequentially stores the image data in the address corresponding to the line M of the image memory. , Performs the groundwork determination process of the look-ahead line N.

In (f), when the look-ahead line N = 5000 line (base area start line) is reached, the line tp1 = 5000 line used for the determination is held and the speed switching reservation flag = 1 is set. The image data of the current line M is stored up to 5000 lines.

In (g), when the current line M = tp1 (= 5000 line) is reached, the speed switching reservation flag = 0 is reset and the speed flag = 1 (high-speed drive) is switched. The carriage is driven at a high speed, and the CIS 205 reads the image of the look-ahead line N in synchronization with the line synchronization signal generated from the encoder signal, and performs the groundwork determination process in units of one line.

In (h), when the look-ahead line N = the final line L-1 (= 7015 line) is reached, if the movement of the CIS 205 in the sub-scanning direction is a high-speed drive, the address corresponding to tp1 to L of the image memory is reached. The background data is stored and the document scanning process is completed.

FIG. 17 shows an example of a document when the background area is narrower than the distance dL line between the current line M and the look-ahead line N, and is a diagram showing characteristic timings in document reading in (a) to (c). .. The symbols and the like in the figure are the same as those in FIG. FIG. 18 is a diagram showing the moving speed of the CIS 205 in the sub-scanning direction and the type of data (image data or background data) stored in the image memory when the document of FIG. 17 is read in the look-ahead mode.

In (a), the state when the look-ahead line N = 3045 line (base area start line) is reached is shown, and the previous operation is the same as in FIG. The movement of the CIS 205 in the sub-scanning direction is a normal drive, and when the read-ahead line N = 3045 line (base area start line) is reached, the line tp1 = 3045 line used for the determination is held, and the speed switching reservation flag = 1 Set to.

In (b), when the look-ahead line N = 3050 line (image area start line) is reached, the 3050 line is determined as an image and reset to the speed switching reservation flag = 0. That is, even when the current line M = 3045 line (base area start line) in (c) is reached, the moving speed of the CIS 205 in the sub-scanning direction remains the normal drive. The movement of the CIS 205 in the sub-scanning direction and the reading of the CIS 205 are the same as those after (e) in FIG.

FIG. 19 shows an example of a document in which the document area is narrower than the distance dL line between the current line M and the look-ahead line N, and is a diagram showing characteristic timings in document scanning in (a) to (c). .. The symbols and the like in the figure are the same as those in FIG. FIG. 20 is a diagram showing the moving speed of the CIS 205 in the sub-scanning direction and the type of data (image data or background data) stored in the image memory when the document of FIG. 19 is read in the look-ahead mode.

In (a), the state when the look-ahead line N = 2000 line (image area start line) is reached is shown, and the previous operation is the same as in FIG. The movement of the CIS 205 in the sub-scanning direction is a high-speed drive, and when the read-ahead line N = 2000 line (image area start line) is reached, the tp2 = 2000 line is held and the speed switching reservation flag = 1 is set.

In (b), when the look-ahead line N = 2001 line (base area start line) is reached, even if the movement of the CIS 205 in the sub-scanning direction is image-determined in high-speed drive, nothing is done and the background is determined during high-speed drive. End the process.

In (c), when the current line M = 1990 line (base area start line) is reached, when the current line M = tp2-kL-1 (= 1990 line) is reached, the speed switching reservation flag is reset to 0. , Switch to speed flag = 0 (normal drive). The carriage decelerates at the deceleration acceleration for reaching the normal drive speed at the current line M = tp2 (= 2000 line), and is driven at the normal drive speed after the 2000 line. The CIS 205 reads the current line M and the look-ahead line N in synchronization with the line synchronization signal generated from the encoder signal, reads the image data of the current line M in units of one line, and sequentially stores the image data in the address corresponding to the line M of the image memory. , Performs the groundwork determination process of the look-ahead line N. When the current line M = 1990 line, the groundwork is determined by the look-ahead line N = 2002 line, tp1 = 2002 is held, and the speed switching reservation flag = 1 is set. The image data of the current line M is stored in the image memory up to the 2001 line.

In (d), when the current line M = tp1 (= 2002 line) is reached, the speed switching reservation flag = 0 is reset and the speed flag = 1 (high-speed drive) is switched. That is, the base 2001 line is stored in the memory as an image. Subsequent processing is the same as in FIG.

<< Embodiment 2 >>
In the first embodiment described above, the CIS 205 irradiates the current line with the first light source 301, irradiates the look-ahead line with the second light source 302, and transmits the reflected light with the first image sensor 304 via the first lens array 303. The form of receiving light is described as an example. However, it is not limited to this form. The look-ahead line may be configured such that the current line is irradiated by the second light source 302 and the reflected light is received by the second image sensor 2101 via the second lens array 2100. In the second embodiment, the configuration, control, and the like that are different from those in the first embodiment will be described below.

<Explanation of the configuration of the image reader>
FIG. 21 is a diagram illustrating an electrical configuration related to a configuration that functions as an image reading device 300 of the MFP 100 in the second embodiment.

The CIS 205 includes a first light source 301 and a second light source 302 for irradiating a document with light, a first lens array 303 and a second lens array 2100 arranged on a line, and a first image sensor 304 arranged in a line. , Second image sensor 2101, and the like. The configurations of the first light source 301 and the second light source 302 are the same as those in the first embodiment. The second LED 307 is turned on during the document reading operation, and the light emitted from the second LED 308 irradiates the Nth line, which is a line ahead of the current line by the dL line, via the second light guide. The light reflected from the document surface enters the photodiode of the second image sensor 2101 via the second lens array 2100, and the second image sensor 2101 stores the charge obtained by photoelectrically converting the incoming light with the photodiode for a predetermined time. Then, after voltage conversion, it is output to AFE330 as an image signal. Although the second image sensor 2101 is controlled by the sensor control unit 365, it may be shared with the control signal of the first image sensor 304 or may be provided separately. The method of reading the current line M by the first light source 301 is the same as that of the first embodiment.

<CIS configuration and operation>
FIG. 22 is a diagram showing light source irradiation to the current line M and reflection on the document in the normal mode in the second embodiment. In the normal mode, the second light guide 308, the second lens array 2200, and the second image sensor 2101 are not used. The second light guide 308, the second lens 2200, and the second image sensor 2101 will be described later. The light source irradiation on the current line M and the reflection on the document are the same as those in FIG. 4 described in the first embodiment. FIG. 23 shows an operation timing chart of CIS205 in the normal mode in the second embodiment. Since the second image sensor 2101 is not used in the normal mode, as an example, the signal of the second image sensor 2101 is not stored and the signal is not output. The timings of the encoder pulse, the line synchronization signal, the horizontal synchronization signal (SH), the first LED 305, the first image sensor 304, and the like are the same as those in FIG. 5 described in the first embodiment.

FIG. 24 is a diagram showing light source irradiation and reflection on the document to the current line M and the look-ahead line N in the normal drive of the look-ahead mode in the second embodiment. The arrangement of the first lens 500, the first light guide body 306, and the first image sensor 304 is the same as that in FIG. In the second embodiment, the central axis of the second lens 2200 is located in the normal direction of the look-ahead line N of the document, and in reading the current line, the most light is reflected in the normal direction of the look-ahead line N of the document. The second light guide body 308 is arranged so as to do so. The look-ahead line N is located on the dL line ahead of the current line M, as in the first embodiment. FIG. 25 shows an operation timing chart of the CIS 205 in the normal drive of the look-ahead mode in the second embodiment. The timings of the encoder pulse, the line synchronization signal, the horizontal synchronization signal (SH), the first LED 305, the first image sensor 304, the second LED 307, and the like are the same as those in the first embodiment. In the second image sensor 2101, the number of lines for signal storage and signal output and the timing of the color channel are the same as the timing of the first image sensor 304 of FIG. 7 described in the first embodiment.

FIG. 26 is a diagram showing light source irradiation to the look-ahead line N and reflection on the document in the high-speed drive of the look-ahead mode in the second embodiment. The arrangement of the first lens 500, the first light guide 306, the first image sensor 304, the second lens 2200, the second light guide 308, and the second image sensor 2101 is the same as in FIG. 24. FIG. 27 shows an operation timing chart of the CIS 205 in high-speed drive in the look-ahead mode in the second embodiment. The timings of the encoder pulse, the line synchronization signal, the horizontal synchronization signal (SH), the first LED 305, the first image sensor 304, the second LED 307, and the like are the same as those in the first embodiment. In the second image sensor 2101, the number of lines for signal storage and signal output and the timing of the color channel are the same as the timing of the first image sensor 304 of FIG. 9 described in the first embodiment.

<Flowchart>
FIG. 28 shows an overall flowchart of the scanning operation of the second embodiment. Calibration of the second image sensor 2101 is performed in S2800 of FIG. 28. Other flows are the same as those in FIGS. 10 to 14 shown in the first embodiment.

<< Embodiment 3 >>
In the first or second embodiment described above, a mode in which the CIS 205 reads a document while moving in the first direction by being driven by a DC motor 206 has been described as an example. However, it is not limited to this form. An image reading device 300 that reads an image of a document line by line by controlling the relative position of a carriage equipped with an image sensor and a light source and a document in the first direction by a motor may be used. For example, the present invention may be applied to a form in which a document is read by an auto document feeder (ADF). In the ADF, the CIS 205 is fixed at a predetermined position, and the CIS 205 scans a document conveyed in the first direction by a transfer mechanism using a DC motor as a drive source.

The configuration of the present embodiment is the same as that described in the first embodiment or the second embodiment. For example, the drive unit 350 of FIG. 3 may be used as a drive unit for ADF. Alternatively, a drive unit equivalent to the drive unit 350 in FIG. 3 may be provided separately. For example, when the drive unit 350 of FIG. 3 is used as the first drive unit, the image reading device 300 may further include a second drive unit for ADF separate from the first drive unit. Then, the signal input to the encoder processing unit 362 may be switched between the first drive unit and the second drive unit according to the reading mode to be used by a selector (not shown). Even when the ADF is used in this way, the underlying region can be read at high speed by performing the same processing as in the first or second embodiment.

206 DC motor 300 Image reader 301 First light source 302 Second light source 304 First image sensor 361 Light source control means 366 Image determination means

Claims (13)

An image reading device that reads an image of the document line by line by moving a carriage equipped with an image sensor and a light source relative to the sub-scanning direction of the document by a motor.
The image reading device includes a first light source that illuminates the current position line of the document, and
The first image sensor that receives the reflected light from the current position line and
A second light source arranged so that the reflected light can be received by the first image sensor with respect to the line located in front of the current position line in the moving direction of the carriage.
A light source control means for lighting the first light source and the second light source in a time-division manner, and
An image determination means for determining whether or not the line is a base based on the image sensor output obtained by the irradiation light from the second light source.
The moving speed of the carriage is switched according to the result of the image determination means.
The line determined to be other than the base is switched to the first carriage movement control, and the line determined to be the base is switched to the second carriage movement control.
The second carriage movement control is an image reading device, characterized in that the movement speed of the carriage is faster than that of the first carriage movement control. The first light source is arranged so as to receive the most reflected light in the normal direction with respect to the image sensor in the line at the current position of the document.
The second light source is characterized in that it is arranged so that the image sensor receives reflected light from a direction other than the normal direction with respect to the image sensor in a line located ahead of the line at the current position of the document. The image reading device according to claim 1. An image reading device that reads an image of the document line by line by moving a carriage equipped with an image sensor and a light source relative to the sub-scanning direction of the document by a motor.
The image reading device includes a first light source that illuminates the current position line of the document, and
The first image sensor that receives the reflected light from the current position line and
A second light source that illuminates a line located in front of the current position line in the moving direction of the carriage, and
The second image sensor that receives the reflected light from the current position line and
A light source control means for lighting the first light source and the second light source in a time-division manner, and
An image determination means for determining whether or not the line is a base based on the image sensor output obtained by the irradiation light from the second light source.
The moving speed of the carriage is switched according to the result of the image determination means.
The line determined to be other than the base is switched to the first carriage movement control, and the line determined to be the base is switched to the second carriage movement control.
The second carriage movement control is an image reading device, characterized in that the movement speed of the carriage is faster than that of the first carriage movement control. The image reading device according to any one of claims 1 to 3, wherein the light source controlling means reads a line located ahead of the line at the current position of the document in gray. Any one of claims 1 to 4, wherein the reading resolution in the sub-scanning direction in the second carriage movement control is smaller than the reading resolution in the sub-scanning direction in the first carriage movement control. The image reader according to the section. In the switching from the second carriage movement control to the first carriage movement control, a switching section margin for switching several lines before is provided for the line determined to be other than the base, and the switching section margin is set according to the scan mode. The image reading device according to any one of claims 1 to 5, wherein the image reading device is determined. In the first carriage movement control, image data is stored in the image memory for each color for each line, and in the second carriage movement control, the image determination is performed from the line determined as the base by the image determination means. Any of claims 1 to 6, wherein the background data is stored in the image memory for each color up to the line before the number of lines corresponding to the switching margin section with respect to the line determined to be an image by the means. The image reading device according to item 1. When the background area of the document is shorter than the distance d between the line at the current position of the document and the line located before the line at the current position of the document, the area is read with the first carriage movement control. The image reading device according to any one of claims 1 to 7, wherein the image reading device is characterized. When the area other than the background of the document is shorter than the distance between the line at the current position of the document and the line located before the line at the current position of the document, the distance d ahead of the background determination line from other than the background. The image reader according to any one of claims 1 to 8, wherein the line switches to a second carriage speed. When the line located before the current position line of the document reaches the end of the document, if there is no area other than the background during the distance d, the scanning operation is terminated and the distance d before the end of the document. The image reading device according to any one of claims 1 to 9, wherein the background data is stored in the memory in the line from the line to the end of the document. The image reading device according to any one of claims 1 to 10, wherein the reading resolution in the sub-scanning direction in the second carriage movement control is determined according to the scan mode or the input device. In each pixel of one line, if the number of background pixels is larger than the number of background pixels required for determining as a background line, the image determination means determines that the line is a background, and if other conditions, the background is determined. The image reading device according to any one of claims 1 to 11, wherein the image reading device is characterized by determining that the image is other than. The normal reading mode and the look-ahead mode in which the light source control means does not read the line located ahead of the current position line of the document by the second light source, and the image determination means does not perform a determination other than the background / background. The image reading device according to any one of claims 1 to 12, wherein the mode is determined according to a condition specified by the user.

Images