JP2013026657A - Image reading apparatus, image reading method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce glaring caused by light emitted from a light source and to reduce variation in illumination of the light source on a document surface.SOLUTION: An image reading apparatus comprises: an LED 1 for irradiating a document with light; a CCD 2 which comprises a monochrome line sensor for reading the document monochromatically and plural color line sensors for reading the document chromatically and reads the document by converting the light reflected by the document to an electric signal; and a mode switch part 91 which, when detecting the document size along a main scanning direction, switches a reading mode indicating which of the monochrome line sensor and the color line sensor to use to read the document, to a monochrome mode to use the monochrome line sensor to read the document.

Description

  The present invention relates to an image reading apparatus, an image reading method, and a program for reading a document placed on a document table.

  2. Description of the Related Art Conventionally, in an image reading apparatus, when a document placed on a document table is read by a flat bed scanner, a document size is detected by a dedicated sensor provided in each of the main scanning direction and the sub-scanning direction. There were many. However, in recent years, a dedicated sensor is not provided for detecting the document size in the main scanning direction, and the document size is detected by a CCD (Charge Coupled Device) used as a reading device. Specifically, for example, when the pressure plate changes from an open state to a closed state, a light source such as an LED (Light Emitting Diode) is turned on to irradiate the original, and the original size is detected by reflected light incident on the CCD.

  However, when the document size is detected using a light source such as an LED, there is a problem that the light generated by the light source is dazzling for the user. Therefore, a document image reading apparatus that reduces glare caused by light emission from a light source has been disclosed (for example, see Patent Document 1). In the document image reading apparatus of Patent Document 1, when the document size is detected, every other LED is turned on when the opening angle of the pressure plate of the flatbed scanner becomes a predetermined value or less, and the amount of light at the time of document reading is determined. Also, the document size is read using a low light quantity.

  Here, in an image reading apparatus using a light source such as an LED, the light amount of the light source is generally adjusted for each apparatus when the power is turned on. The light amount adjustment of the light source is adjusted based on image data output from the CCD when the light source is turned on. For this reason, in each apparatus, when the light amount is adjusted from image data read including factors such as variations in the light source and the CCD itself, that is, variations in the light emission intensity of the light source and variations in sensitivity for each pixel of the CCD. There is a problem in that the illuminance on the document surface varies from device to device.

  The present invention has been made in view of the above, and an image reading apparatus and an image which reduce glare caused by light emission from a light source and reduce variations in illuminance on a document surface of the light source when detecting a document size. It is an object to provide a reading method and a program.

  In order to solve the above-described problems and achieve the object, the present invention provides an image reading apparatus having a light source for irradiating light on a document, a monochrome line sensor for reading the document as achromatic, and the document. A plurality of color line sensors for reading as a color, converting reflected light of the light from the document into an electrical signal, and reading the document, and detecting the document size in the main scanning direction, And a switching unit for switching a reading mode indicating whether the original is read by the monochrome line sensor or the color line sensor to a monochrome mode in which the original is read by the monochrome line sensor.

  Further, the present invention is an image reading method executed by an image reading device, wherein the image reading device includes a light source that irradiates light on a document, a monochrome line sensor that reads the document as achromatic, and A plurality of color line sensors for reading the original as chromatic, and a reading means for converting the reflected light of the light from the original into an electrical signal and reading the original, and for adjusting the original size in the main scanning direction. In the case of detection, it includes a switching step of switching a reading mode indicating whether the original is read by the monochrome line sensor or the color line sensor to a monochrome mode in which the original is read by the monochrome line sensor. And

  The present invention also includes a light source that irradiates light to the original, a monochrome line sensor that reads the original as achromatic, and a plurality of color line sensors that read the original as chromatic, When detecting an original size in the main scanning direction, an image reading apparatus including a reading unit that converts the reflected light of the light into an electrical signal and reads the original, and either of the monochrome line sensor and the color line sensor This is a program for functioning as a switching means for switching a reading mode indicating whether or not the original is read by a line sensor to a monochrome mode for reading the original by the monochrome line sensor.

  According to the present invention, when detecting the document size, it is possible to reduce glare due to light emission from the light source and to reduce variation in illuminance on the document surface of the light source.

FIG. 1 is a block diagram illustrating the configuration of the image reading apparatus according to the embodiment. FIG. 2 is a schematic diagram of the CCD according to the embodiment. FIG. 3 is an explanatory diagram when light emitted from the LED enters the CCD. FIG. 4 is an explanatory diagram of the operation by the first carriage when the document size is detected. FIG. 5 is an explanatory diagram of the operation by the first carriage when the document size is detected. FIG. 6 is an explanatory diagram of LED light amount adjustment. FIG. 7 is a flowchart showing the flow of LED light amount adjustment. FIG. 8 is a flowchart showing the flow of the document size detection operation. FIG. 9 is a block diagram of a hardware configuration of the image reading apparatus according to the embodiment.

  Exemplary embodiments of an image reading apparatus, an image reading method, and a program according to the present invention will be explained below in detail with reference to the accompanying drawings. Note that the image reading apparatus described in the following embodiments is a multifunction machine, a copier, a printer, a scanner apparatus, a facsimile apparatus, or the like having at least two functions among a copy function, a printer function, a scanner function, and a facsimile function. The present invention can be applied to any device that reads the image.

  In an image reading apparatus using an LED as a light source, the light amount of the light source is usually adjusted when the power is turned on in order to optimize the light amount of the light source when reading an original. The light amount adjustment of the light source is performed based on image data read by the CCD. Therefore, if there is a variation in light emission intensity of an LED mounted on a PCB (printed circuit board) or a variation in CCD sensitivity, the illuminance on the document surface also varies. For example, when the sensitivity of the CCD is extremely low, light amount adjustment for increasing the light emission intensity of the LED is performed so as to achieve a target image level. Accordingly, the amount of light emitted from the LED changes due to variations in the components such as the LED and the CCD, so that variations in the illuminance on the document surface vary from device to device.

  In this embodiment, as will be described later, a 4-line CCD having one monochrome line and three color lines is used. However, in order to reduce variations in illuminance with respect to the document surface for each apparatus, monochrome lines are used. To detect the document size. If only monochrome lines are used, there is no need to consider variations due to color filters because a color filter that causes variations in CCD sensitivity is not used. As a result, variations in illuminance with respect to the original surface after the light amount adjustment of the light source can be reduced.

  FIG. 1 is a block diagram illustrating the configuration of the image reading apparatus according to the embodiment. As shown in FIG. 1, the image reading apparatus mainly includes a scanner 100, an image processing unit 200, and a main control unit 300.

  The scanner 100 further includes an LED 1, a CCD 2, a motor 3, a pressure plate opening / closing sensor 4, and a document size detection sensor 5.

  The LED 1 is a semiconductor element that emits light when an electric current is passed, and is a light source that irradiates light on a document placed on a document table. A plurality of LEDs 1 are mounted on the PCB such that a plurality of LEDs 1 are arranged in the main scanning direction so as to obtain a uniform light amount on the document surface. In this embodiment, an LED is used as a light source, but the present invention is not limited to this, and a configuration using another light source may be used.

  The CCD 2 is for reading the original by irradiating the original with light from the LED 1 and converting the reflected light of the light from the original into an electric signal. Specifically, the CCD 2 acquires information held by the document as light brightness and darkness, generates an image signal according to the light brightness and darkness, and sends the generated image signal to the AFE 6. In the present embodiment, the document size is detected based on the image data read by the CCD 2. In the present embodiment, a CCD is used as a reading device. However, the present invention is not limited to this, and a configuration using an equal magnification sensor such as a contact sensor may be used.

  The CCD 2 is a 4-ch CCD (4-line sensor) having a monochrome line sensor that reads an original as achromatic (monochrome) and three color line sensors that read the original as chromatic. FIG. 2 is a schematic diagram of the CCD according to the embodiment. As shown in FIG. 2, the CCD 2 includes a monochrome line sensor L1 composed of Bk (black or monochrome) line sensors, and a color line sensor L2 composed of R (red), G (green) and B (blue) line sensors. Are arranged in the order of Bk, R, G, and B. The color line sensor L2 uses a color filter to determine the color, and generates a color image. However, since the monochrome line sensor L1 does not need to determine the color, the color filter is not used.

  The CCD 2 is switched between reading modes indicating whether the original is read by the monochrome line sensor L1 or the color line sensor L2. Specifically, the CCD 2 has a terminal for switching between a monochrome mode read by the monochrome line sensor L1 and a color mode read by the color line sensor L2, and the reading mode can be switched. The input clock is also changed according to each reading mode.

  When detecting the document size, the CCD 2 detects the monochrome line when the pressure plate opening / closing sensor 4 described later detects that the pressure plate pressing the document placed on the document table is closed (closed state). The original is read by the sensor L1.

  Here, how the light emitted from the LED 1 enters the CCD 2 will be described. FIG. 3 is an explanatory diagram when light emitted from the LED enters the CCD. As shown in FIG. 3, the scanner 100 includes an LED 1, a first mirror 21, a second mirror 22, a third mirror 23, a lens 24, an SBU (sensor boat unit) 25, and a contact glass on the mounting table P. A CCD 2 is provided.

  When light is emitted from the LED 1 to the document placed on the placement table P, the reflected light from the document passes through the first mirror 21, the second mirror 22, and the third mirror 23 and is reflected on the reflected light. After entering the condensing lens 24, the light enters the CCD 2 mounted on the SBU 25. Here, a module on which the LED 1 and the first mirror 21 are mounted is referred to as a first carriage C1, and a module on which the second mirror 22 and the third mirror 23 are mounted is referred to as a second carriage C2.

  The motor 3 drives the first carriage C1 and the second carriage C2 on which the LED 1 is mounted when reading a document for printing or detecting the document size by the CCD 2. Here, the operation of the first carriage C1 when the document size is detected by the CCD 1 will be described. 4 and 5 are explanatory diagrams of the operation by the first carriage when the document size is detected.

  The motor 3 moves the first carriage C1 below the reference white plate, that is, below the reading glass 30 when the power is turned on. Here, the reference white plate is a white plate-like member provided at a position facing the reading glass 30 of the pressure plate, and is used for shading correction or the like when the light amount of the LED 1 is adjusted. Shading correction refers to read data even though a document having a uniform density is read due to variations in individual light emission intensities of the LEDs 1, variations in the main scanning direction, sensitivity variations for each pixel of the CCD 2, and the like. This is to correct the phenomenon of variation.

  In addition, when the pressure plate opening / closing sensor 4 described later detects that the pressure plate is in an open state (open state), the motor 3 is moved to a document size detection position B, which is a position where document size detection is started. 1 Carriage C1 is moved.

  Further, the motor 3 moves the first carriage C1 from the document size detection position B to the normal standby position A when a closed state of the pressure plate is detected by a pressure plate opening / closing sensor 4 described later. At this time, the document size in the main scanning direction is detected by turning on the LED 1 and reading the document. The document size in the sub-scanning direction is detected by a document size detection sensor 5 described later. Note that the standby position A varies depending on the model because there is a portion that is shielded by a mold near the reading glass 30.

  The pressure plate opening / closing sensor 4 is a sensor that detects a state where the pressure plate is open (open state) and a state where the pressure plate is closed (closed state). Specifically, for example, the pressure plate open / close sensor 4 detects a case where the pressure plate is opened at a predetermined angle or more as an open state, and detects a case where the pressure plate is closed at a predetermined angle or less as a closed state. The document size detection operation by the CCD 2 is performed using the detection by the pressure plate opening / closing sensor 4 as a trigger.

  The document size detection sensor 5 is a sensor for detecting the size of the document placed on the document table P in the sub-scanning direction, and is mounted inside the scanner as shown in FIGS.

  The image processing unit 200 mainly includes an AFE (Analogue Front End) 6, an image processing unit 7, and a document size determination unit 8.

  The AFE 6 is a device that performs A / D conversion, and converts each analog image signal output from the monochrome line sensor L1 and the color line sensor L2 of the CCD 2 into a digital image signal. The AFE 6 also has a dark offset level adjustment and a bright output adjustment function for the output digital image signal. The AFE 6 may be mounted on the SBU 25 in the scanner 100 or may be mounted on the main control unit 300.

  The image processing unit 7 performs various processes on the digital image signal output from the AFE 6.

  The document size determination unit 8 uses an electrical signal output from the CCD 2 to detect the document size in the main scanning direction and a signal output from the document size detection sensor 5 to detect the document size in the sub-scanning direction. The document size in the main scanning direction and the sub scanning direction is determined.

  The main control unit 300 mainly includes a scanner control unit 9, a CPU (Central Processing Unit) 10, an operation unit 11, and a memory 12.

  The scanner control unit 9 has a function of outputting a control signal for driving the CCD 2 and the AFE 6, a control signal for driving the LED 1 and the motor 3, a function of driving the document size detection sensor 5 and the pressure plate opening / closing sensor 4. The scanner control unit 9 includes a mode switching unit 91, a light source control unit 92, and a count unit 93.

  The mode switching unit 91 switches a reading mode when reading an original with the CCD 2 to a monochrome mode or a color mode. Specifically, the mode switching unit 91 switches the reading mode to the monochrome mode when an open state is detected by the pressure plate opening / closing sensor 4 when detecting the document size in the main scanning direction. The mode switching unit 91 switches to the reading mode designated by the user after the document size is determined by the document size determination unit 8.

  The light source control unit 92 performs light amount adjustment for adjusting the LED 1 to a light amount corresponding to each reading mode when the power is turned on. The light source control unit 92 sets the light amount of the LED 1 to a value adjusted by adjusting the light amount when the power is turned on after the document size is determined by the document size determination unit 8. Further, when the closed state is detected by the pressure plate opening / closing sensor 4, the light source control unit 92 sets the light amount of the LED 1 to a value that is uniformly reduced from the value adjusted by the light amount adjustment at the time of turning on the power.

  The counting unit 93 counts the number of times the pressure plate is opened and closed when the pressure plate opening / closing sensor 4 detects an open state and a closed state, and the number of times the document size is detected by the CCD 2. The number of detections is stored in a storage unit (not shown). This is for use as information at the time of substrate reuse.

  The CPU 10 performs overall control of the image reading apparatus configured by the scanner 100, the image processing unit 200, the scanner control unit 9, and the like.

  The operation unit 11 displays an input screen and a warning to the user, and inputs the user from the displayed input screen and operation keys.

  The memory 12 is a storage medium that temporarily stores various data.

  Next, the light source control unit 92 will be described with respect to the light amount adjustment of the LED 1. The light amount adjustment of the LED in the present embodiment is the same as the light amount adjustment that is generally performed. FIG. 6 is an explanatory diagram of LED light amount adjustment. As shown in FIG. 6, the lighting clock synchronized with the line synchronizing signal when the original is read by the CCD 2 is repeatedly turned on / off several times within one line. The light source control unit 92 changes the High / Low duty (ratio of pulse width H to L) of the lighting clock (PWM (Pulse Width Modulation) adjustment) or the CCD 2 in accordance with the set gain (amplification factor). The light quantity of the LED 1 is adjusted by amplifying the electric signal photoelectrically converted (gain setting).

  Next, the flow of adjusting the light amount of the LED 1 when the image reading apparatus is turned on will be described. FIG. 7 is a flowchart showing the flow of LED light amount adjustment.

  First, the light source control unit 92 determines whether or not the power of the image forming apparatus is turned on (step S10). If the power is off, the light source control unit 92 waits as it is (step S10: No).

  When the power is turned on (step S10: Yes), the light source control unit 92 performs gain setting (step S11) and sets PWM to an initial value (step S12). Next, the scanner control unit 9 moves the first carriage C1 below the reference white plate by the motor 3 (step S13).

  Next, the LED 1 irradiates the reference white plate, and the CCD 2 reads the reference white plate (step S14). The light source controller 92 detects the peak value of the image signal from the image data of the reference white plate read by the CCD 2 (step S15). Based on the peak value, the light source control unit 92 performs PWM adjustment so that the peak value of the reference white plate becomes a target value (step S16), and performs PWM setting based on the adjustment value (step S17). .

  The light source control unit 92 determines whether or not there is another reading mode (step S18). If there is another reading mode (step S18: Yes), the reading mode is switched and the processing of steps S14 to S17 is performed. repeat.

  On the other hand, when there is no other reading mode (step S18: No), the scanner control unit 9 moves the first carriage C1 to the standby position by the motor 3 (step S19).

  Next, the flow of the original size detection operation of the image reading apparatus will be described. FIG. 8 is a flowchart showing the flow of the document size detection operation.

  First, the scanner control unit 9 determines the open / close state of the pressure plate by the pressure plate open / close sensor 4 (step S30), and if it is in the closed state, it waits until the open state (step S30: No). On the other hand, when the pressure plate is in the open state (step S30: Yes), the mode switching unit 91 switches the reading mode of the CCD 2 to the monochrome mode (step S31). The scanner control unit 9 moves the first carriage C1 to the document size detection position by the motor 3 (step S32).

  Then, the scanner controller 9 determines the open / close state of the pressure plate by the pressure plate open / close sensor 4 (step S33), and if it remains in the open state, it waits until it is closed (step S33: No).

  On the other hand, when the pressure plate is in the closed state (step S33: Yes), the PWM setting is performed with a value that is uniformly reduced from the value adjusted by the light amount adjustment at the time of power-on (step S34). The light source controller 92 turns on the LED 1 (step S35), and the document size detection sensor 5 detects the document size in the sub-scanning direction (step S36).

  Next, the light source control unit 92 moves the first carriage C1 from the document size detection position to the standby position by the motor 3, and detects the document size in the main scanning direction by the CCD 2 (step S37).

  Then, the document size determination unit 8 determines the document size based on the output from the document size detection sensor 5 and the output from the CCD 2 (step S38). If the document size cannot be determined (step S38: No), the CPU 10 displays on the operation unit 11 that the document size cannot be determined and displays a pressure plate opening / closing instruction (alert display) (step S39), and returns to step S30. .

  On the other hand, when the document size can be determined (step S38: Yes), the count unit 93 increments the document size detection count (step S40). The mode switching unit 91 switches the reading mode of the CCD 2 to the reading mode designated by the user (step S41). Then, the scanner 100 executes a scan for reading an image (step S42).

  As described above, in the image forming apparatus according to the present embodiment, when the document size in the main scanning direction is detected, the LED 1 and the CCD 2 are used. However, the light amount of the LED 1 when the document size is detected is turned on. Since the value is uniformly reduced from the value adjusted by adjusting the amount of light at the time, glare caused by light emission from the light source can be reduced when detecting the document size.

  Further, when detecting the document size, the monochrome mode of the CCD 2 is used for detection by switching the reading mode to the monochrome mode. This is because if only a monochrome line is used, it is not necessary to use a color filter that causes the sensitivity of the CCD 2 to vary, and thus there is no need to consider variations due to the color filter. As a result, variation in illuminance with respect to the original surface of the LED 1 can be reduced.

  FIG. 9 is a block diagram of a hardware configuration of the image reading apparatus according to the embodiment. As shown in the figure, this image reading apparatus has a configuration in which a controller 1000 and an engine unit (Engine) 6000 are connected by a PCI (Peripheral Component Interface) bus. The controller 1000 is a controller that controls the entire image reading apparatus and controls drawing, communication, and input from an operation unit (not shown). The engine unit 6000 is a printer engine that can be connected to a PCI bus, and is, for example, a monochrome plotter, a 1-drum color plotter, a 4-drum color plotter, a scanner, or a fax unit. The engine unit 6000 includes an image processing part such as error diffusion and gamma conversion in addition to a so-called engine part such as a plotter.

  The controller 1000 includes a CPU 1100, a north bridge (NB) 1300, a system memory (MEM-P) 1200, a south bridge (SB) 1400, a local memory (MEM-C) 1700, and an ASIC (Application Specific Integrated Circuit). 1600 and a hard disk drive (HDD) 1800, and the north bridge (NB) 1300 and the ASIC 1600 are connected by an AGP (Accelerated Graphics Port) bus 1500. The MEM-P 1200 further includes a ROM (Read Only Memory) 1200a and a RAM (Random Access Memory) 1200b.

  The CPU 1100 performs overall control of the image reading apparatus. The CPU 1100 includes a chip set including the NB 1300, the MEM-P 1200, and the SB 1400, and is connected to other devices via the chip set.

  The NB 1300 is a bridge for connecting the CPU 1100 to the MEM-P 1200, SB 1400, and AGP 1500, and includes a memory controller that controls reading and writing of the MEM-P 1200, a PCI master, and an AGP target.

  The MEM-P 1200 is a system memory used as a memory for storing programs and data, a memory for developing programs and data, a memory for drawing a printer, and the like, and includes a ROM 1200a and a RAM 1200b. The ROM 1200a is a read-only memory used as a program / data storage memory, and the RAM 1200b is a writable / readable memory used as a program / data development memory, a printer drawing memory, or the like.

  The SB 1400 is a bridge for connecting the NB 1300 to a PCI device and peripheral devices. The SB 1400 is connected to the NB 1300 via a PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

  The ASIC 1600 is an IC (Integrated Circuit) for image processing having hardware elements for image processing, and has a role of a bridge for connecting the AGP 1500, the PCI bus, the HDD 1800, and the MEM-C 1700. The ASIC 1600 includes a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 1600, a memory controller that controls the MEM-C 1700, and a plurality of DMACs (Direct Memory) that rotate image data using hardware logic. Access Controller) and a PCI unit that performs data transfer between the engine unit 6000 via the PCI bus. The ASIC 1600 is connected to an FCU (Facsimile Control Unit) 3000, a USB (Universal Serial Bus) 4000, and an IEEE 1394 (the Institute of Electrical and Electronics Engineers 1394) interface 5000 via a PCI bus. The operation display unit 2000 is directly connected to the ASIC 1600.

  A MEM-C 1700 is a local memory used as a copy image buffer and a code buffer, and an HDD (Hard Disk Drive) 1800 is a storage for storing image data, programs, font data, and forms. It is.

  The AGP 1500 is a bus interface for a graphics accelerator card proposed for speeding up graphics processing. The AGP 1500 speeds up the graphics accelerator card by directly accessing the MEM-P 1200 with high throughput. .

  The image reading program executed by the image reading apparatus according to the present embodiment is provided by being incorporated in advance in a ROM or the like. The image reading program executed by the image reading apparatus according to the present embodiment is an installable or executable file, such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk), or the like. It may be configured to be recorded on a computer-readable recording medium.

  Furthermore, the image reading program executed by the image reading apparatus according to the present embodiment may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. Further, the image reading program executed by the image reading apparatus of the present embodiment may be provided or distributed via a network such as the Internet.

  The image reading program executed by the image reading apparatus according to the present embodiment includes the above-described units (AFE 6, image processing unit 7, document size determination unit 8, mode switching unit 91, light source control unit 92, and count unit 93). The module has a module configuration, and as the actual hardware, a CPU (processor) reads out and executes an image reading program from the ROM, and the above-described units are loaded onto the main storage device. The AFE 6, the image processing unit 7, the document A size determination unit 8, a mode switching unit 91, a light source control unit 92, and a count unit 93 are generated on the main storage device.

1 LED
2 CCD
3 Motor 4 Pressure plate open / close sensor 5 Document size detection sensor 7 Image processing unit 8 Document size determination unit 9 Scanner control unit 91 Mode switching unit 92 Light source control unit 93 Count unit 11 Operation unit 12 Memory 21 First mirror 22 Second mirror 23 Second mirror 23 3 mirrors 24 lens 30 reading glass 100 scanner 200 image processing unit 300 main control unit L1 monochrome line sensor L2 color line sensor

JP 2002-290675 A

Claims (10)

A light source that emits light to the document;
A monochrome line sensor that reads the original as achromatic and a plurality of color line sensors that read the original as chromatic, and converts the reflected light of the light from the original into an electrical signal to read the original Reading means;
When detecting the document size in the main scanning direction, the reading mode indicating which of the monochrome line sensor and the color line sensor reads the document is switched to the monochrome mode in which the document is read by the monochrome line sensor. An image reading apparatus comprising: a switching unit. A pressure plate for pressing the document placed on the document table;
An open / close detecting means for detecting an open state where the pressure plate is open and a closed state where the pressure plate is closed; and
The image reading apparatus according to claim 1, wherein the switching unit switches the reading mode to the monochrome mode when the open state is detected by the open / close detection unit.   The image reading apparatus according to claim 2, wherein the reading unit reads the document by the monochrome line sensor when the closed state is detected by the open / close detection unit.   4. The apparatus according to claim 2, further comprising a driving unit that moves the light source to a document size detection position that is a position where the document size detection is started when the open / closed detection unit detects the open state. The image reading apparatus described in 1. Size determination means for determining the document size based on a signal output by the reading means;
5. The image reading according to claim 1, wherein the switching unit switches to the reading mode designated by a user after the document size is determined by the size determination unit. 6. apparatus.   When the power is turned on, a light amount adjustment is performed to adjust the light source to a light amount corresponding to each of the reading modes, and after the document size is determined by the size determination unit, the light amount of the light source is adjusted by the light amount adjustment at the time of turning on the power. The image reading apparatus according to claim 5, further comprising a light source control unit that sets the adjusted value.   When the closed state is detected by the open / close detection unit, the light source control unit sets the light amount of the light source to a value that is uniformly reduced from a value adjusted by the light amount adjustment at the time of power-on. The image reading apparatus according to claim 6.   The image reading apparatus according to claim 1, further comprising a counting unit that counts the number of times the document size is detected by the reading unit. An image reading method executed by an image reading apparatus,
The image reading apparatus includes a light source that irradiates light on a document, a monochrome line sensor that reads the document as achromatic color, and a plurality of color line sensors that read the document as chromatic color. Reading means for converting the reflected light of the light into an electrical signal and reading the document,
When detecting the document size in the main scanning direction, the reading mode indicating which of the monochrome line sensor and the color line sensor reads the document is switched to the monochrome mode in which the document is read by the monochrome line sensor. An image reading method comprising a switching step. A light source that emits light to the original; a monochrome line sensor that reads the original as achromatic; and a plurality of color line sensors that read the original as chromatic; and the reflected light of the light from the original An image reading apparatus comprising a reading unit that converts the electric signal into the original and reads the original.
When detecting the document size in the main scanning direction, the reading mode indicating which of the monochrome line sensor and the color line sensor reads the document is switched to the monochrome mode in which the document is read by the monochrome line sensor. Program to function as a switching means.

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