JP2019134351A - Image reading device and program - Google Patents

Abstract

To provide an image reading device scanning an image by means of an image sensor, and capable of improving the throughput speed while maintaining accurate shading compensation.SOLUTION: An image reading device for reading a script and generating image data has an image sensor for reading the script, a digital data processing part for compensating the data of the script read by the image sensor on the basis of the shading data containing black reference data and white reference data, and generating the image data, and a reading control section for generating the shading data from the data read by the image sensor. The reading control section generates the shading data at the time of power-up of the image reading device, generates black reference data at the time of reading the script, and compensates the shading data on the basis of the black reference data.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image reading apparatus that scans an image with an image sensor, and more particularly to an image reading apparatus that can improve processing speed while maintaining accurate shading correction.

  2. Description of the Related Art Conventionally, an image reading apparatus such as a scanner that reads an image of a document and generates image data has become widespread. Some of these image reading apparatuses have a plurality of reading modes having different resolutions and colors when reading an image.

  Also, the scanning process (reading process) in the image reading apparatus requires various setting information, specifically, shading data used for shading correction, information such as the lighting time of the light source, and these setting information include It depends on the resolution and color when reading the image.

  Therefore, in an image reading apparatus having a plurality of reading modes, the setting information is generated and set after the scanning mode is determined in response to a scanning request.

  Patent Document 1 below describes the invention of the image reading apparatus and describes that the shading data is read when the power is turned on.

Japanese Patent Laid-Open No. 11-205539

  However, generation of shading data in the image reading apparatus requires time by moving the image sensor to a predetermined position and reading data by the image sensor. For this reason, as described above, when the above-described setting information including shading data is prepared when a scanning request is received, it takes a long time to start reading a document after receiving a document reading instruction. In particular, when the image data read by the image reading apparatus is output for direct facsimile transmission, there is a possibility that a timeout error occurs until the facsimile data transmission starts.

  Further, Patent Document 1 does not describe how to prepare shading data when power is turned on, and at what timing other setting information is set in that case.

  In addition, there is a temperature difference between the apparatus when the power is turned on and when a scanning request is received, and there is a problem that accurate shading correction cannot be performed if the shading data read when the power is turned on.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus that scans an image with an image sensor, and that can improve processing speed while maintaining accurate shading correction. is there.

  In order to achieve the above object, according to one aspect of the present invention, an image reading apparatus that reads an original to generate image data includes an image sensor that reads the original, and shading data including black reference data and white reference data. A digital data processing unit that corrects the document data read by the image sensor and generates the image data; and a reading control unit that generates the shading data from the data read by the image sensor; The reading control unit generates the shading data when the image reading apparatus is turned on, generates the black reference data when reading the document, and converts the black reference data into the black reference data. Correcting the generated shading data on the basis of the generated shading data.

  According to this aspect, it is possible to shorten the processing time when receiving an instruction to read a document, and accurate shading correction is possible.

  Furthermore, in the above invention, a preferable aspect is that the reading control unit is based on a difference between the black reference data of the generated shading data and the black reference data generated when the original is read. The white reference data of the generated shading data is corrected.

  According to this aspect, it is possible to omit moving the image sensor to the position of the white reference plate in order to read the white reference data.

  Furthermore, in the above-mentioned invention, one preferable aspect further includes a light source that emits light to the original and an A / D conversion unit that digitally converts an analog signal output from the image sensor. The control unit generates a light source lighting time for the light source and a gain / offset value for the A / D conversion unit when the image reading apparatus is powered on.

  According to this aspect, it is possible to shorten the processing time when receiving an instruction to read a document.

  Furthermore, in the above-described invention, a preferable aspect thereof includes a plurality of reading modes having different resolutions and numbers of colors, and the reading control unit has the highest resolution and the largest number of colors when the image reading apparatus is turned on. The shading data is generated for the reading mode, and for the other reading modes, the shading data is generated by calculation from the shading data of the reading mode with the highest resolution and the largest number of colors.

  According to this aspect, it is possible to reduce the time required for generating shading data.

  Furthermore, in the above invention, a preferable aspect thereof is that the reading control unit is configured such that when the value of the black reference data generated when the original is read is equal to or greater than a predetermined threshold value, The black reference data is generated again from the data read by the image sensor by moving the sensor to a position not affected by external light.

  According to this aspect, it is possible to correct shading data accurately without the influence of external light.

  Furthermore, in the above-described invention, one preferable aspect thereof is that the document table further includes a document table placed when the document is read by the image sensor and a hinge extending in a direction crossing a longitudinal direction of the image sensor. A scanner cover attached to the platen so as to be openable and closable, and the reading control unit determines whether or not the value of the black reference data is equal to or greater than a predetermined threshold value. It is characterized by using black reference data based on data read at a position away from the hinge of the image sensor.

  According to this aspect, the black reference data can be determined more correctly.

  In order to achieve the above object, another aspect of the present invention is an image reading apparatus that reads an original to generate image data, and includes an image sensor that reads the original, black reference data, and white reference data A digital data processing unit that corrects the data of the original read by the image sensor based on shading data and generates the image data; And generating the shading data from the data read by the image sensor, generating the black reference data when reading the document, and generating the generated shading data based on the black reference data. It is a program characterized by correcting and executing processing.

  Further objects and features of the present invention will become apparent from the embodiments of the invention described below.

1 is a configuration diagram according to an embodiment of an image reading apparatus to which the present invention is applied. It is the flowchart which illustrated the process sequence at the time of power activation. It is a figure for demonstrating operation | movement of the carriage 3, etc. at the time of power activation. It is the flowchart which illustrated the processing procedure at the time of scanning instruction | indication reception. It is a figure for demonstrating the operation | movement of the carriage 3, etc. at the time of scanning instruction | indication reception.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.

  FIG. 1 is a configuration diagram according to an embodiment of an image reading apparatus to which the present invention is applied. An image reading apparatus 1 shown in FIG. 1 is an image reading apparatus to which the present invention is applied. The image reading apparatus 1 includes shading data necessary for scanning processing when the power is turned on (when the power is turned on). Setting information is prepared, and when a scanning request is received, the prepared various setting information is set to a predetermined location and shading data is corrected. This shortens the processing time when receiving a scanning request while maintaining accurate shading correction.

  The image reading apparatus 1 may be a single scanner, or a printer multifunction device including a printer unit (printing function).

  Although not shown, the image reading apparatus 1 includes a document supply unit that is an object to be processed, such as an ADF (Auto Document Feeder), a document table generated by glass or the like on which the supplied document is placed, and the document table. An openable and closable scanner cover, a paper discharge unit for discharging the processed document, and the like.

  The scanner cover is attached to the document table so as to be rotatable by a hinge on one side of the rectangular document table.

  Further, the document table is provided with a white reference plate (such as b in FIG. 3) for generating white reference data constituting shading data.

  As shown in FIG. 1, the image reading apparatus 1 includes a control unit 2, a carriage 3, a drive mechanism 4, an image sensor 5, and an LED light source 6.

  The carriage 3 includes an image sensor 5 and an LED light source 6, and is moved along the document table in the sub-scanning direction on the document table by the drive mechanism 4.

  The image sensor 5 is a sensor that receives light emitted from the LED light source 6 and reflected by the document, accumulates electric charges according to the amount of received light, and outputs the charges as an image read signal (analog data).

  The image sensor 5 includes a plurality of sensor chips arranged in a direction (main scanning direction) substantially orthogonal to the document supply direction, and each sensor chip is, for example, a CCD (Charge Coupled Device) image sensor.

  The direction in which the sensor chips are arranged, that is, the longitudinal direction of the image sensor 5, in the present image reading apparatus 1, is a direction that intersects with one side (the hinge) of the document table on which the scanner cover is attached. The direction is generally orthogonal.

  The LED light source 6 includes a red LED, a green LED, and a blue LED. The LED light source 6 is a portion that emits light to the document table and the document, and sequentially generates light of these three colors.

  The control unit 2 is a controller that controls the operation of each unit of the image reading apparatus 1. The control unit 2 includes a CPU, ROM, RAM, NVRAM, ASIC, and the like. As shown in FIG. 1, the functional configuration includes a reading control unit 21, a temporary storage memory 22, a light source register 23, an AFE register 24, A shading memory 25, an A / D converter 26, a digital data processor 27, and the like are provided.

  The reading control unit 21 controls the entire scanning process, and in particular, generates setting information including shading data and sets the information in a predetermined location (shading memory 25, light source register 23, AFE register 24). Execute.

  Note that the image reading apparatus 1 has a plurality of reading modes, specifically, four reading modes as an example. The four reading modes are, for example, (1) resolution: 300 dpi, color: monochrome, (2) resolution: 300 dpi, color: color, (3) resolution: 600 dpi, color: monochrome, (4) resolution: 600 dpi, color: Color.

  The reading control unit 21 includes a program that instructs processing contents, a CPU that executes processing according to the program, a RAM, and the like.

  The temporary storage memory 22 is a storage device that temporarily stores setting information including shading data, and includes a RAM or the like.

  The light source register 23 is a register for registering a setting value relating to the light source such as the lighting time of the LED light source 6, and the LED light source 6 operates based on the setting value of the light source register 23.

  The AFE register 24 is a register for an A / D conversion unit 26 described later, and a gain / offset setting value of AFE (Analog Front End) is registered as the setting information.

  The shading memory 25 is a storage unit in which shading data is set, and includes a RAM or the like. The digital data processing unit 27 described later executes a shading process based on the shading data set in the shading memory 25.

  The A / D converter 26 is a device that amplifies analog data (image reading signal) output from the image sensor 5 and converts it into digital data, and is specifically an AFE.

  The digital data processing unit 27 is a part that performs shading correction on the digital data of the image output from the A / D conversion unit 26 and outputs the resulting image data. Specifically, the arithmetic circuit included in the digital data processing unit 27 performs shading correction based on the shading data set in the shading memory 25. The output image data is transmitted to a PC (personal computer) or a printer unit (printing mechanism).

  The image reading apparatus 1 according to the present embodiment having the above-described configuration is characterized by a process for generating various setting information necessary for a scanning process such as shading data. explain. As described above, the image reading apparatus 1 prepares (generates) setting information such as shading data when the apparatus is turned on (when the power is turned on), and receives the setting information when receiving an instruction for scanning processing. Set to a predetermined location.

  First, processing at power-on will be described. FIG. 2 is a flowchart illustrating a processing procedure when power is turned on. FIG. 3 is a diagram for explaining the operation of the carriage 3 when the power is turned on.

When the power of the image reading apparatus 1 is turned on, the reading control unit 21 sequentially selects all reading modes included in the image reading apparatus 1 and, in the present embodiment, four reading modes (1) to (4). The setting information to be set in the light source register 23 and the AFE register 24, specifically, the light source lighting time and the AFE gain / offset value are generated and held in the temporary storage memory 22.

  More specifically, the reading control unit 21 first executes processing for the reading mode (1), and sets the color setting to monochrome and the resolution setting to 300 dpi (steps S1 and S2 in FIG. 2).

  Thereafter, the reading control unit 21 executes an adjustment process for determining the light source lighting time and an adjustment process for determining the AFE gain / offset value (steps S3 and S4 in FIG. 2). The light source lighting time and the AFE gain / offset value to be stored are stored in the memory A1 and the memory B1 of the temporary storage memory 22, respectively (step S5 in FIG. 2). The adjustment process can be executed by a conventional method.

  Next, the reading control unit 21 performs the same processing for the reading modes (2) to (4). That is, the reading control unit 21 sets the color and resolution to the contents of the reading mode (steps S6 and S7, S11 and S12, S16 and S17 in FIG. 2), and adjusts the light source lighting time and the AFE gain / offset value. (Steps S8 and S9, S13 and S14, S18 and S19 in FIG. 2), and the generated light source lighting time and AFE gain / offset value are respectively stored in predetermined locations (memory A2 and B2, A3 and B3, A4 and B4) (steps S10, S15 and S20 in FIG. 2).

  Next, the reading control unit 21 performs a shading data reading process (generation process). The shading data includes black reference data and white reference data, and each data is composed of pixel data in the main scanning direction (density gradation value data of each color for each pixel).

  The shading data is data generated for each reading mode. At this timing, the reading control unit 21 uses the reading mode in the present embodiment for the reading mode having the highest resolution and the largest number of colors. Shading data is generated for (4).

  First, the reading control unit 21 sets the light source lighting time stored in the memory A4 in step S20 in the light source register 23, and sets the AFE gain / offset value stored in the memory B4 in step A20 in the AFE register 24 (step S20). Steps S21 and S22 in FIG.

  Next, the reading control unit 21 performs black reference reading processing (step S24 in FIG. 2) with the LED light source 6 turned off (step S23 in FIG. 2). Specifically, in the state of FIG. 3A, that is, when the carriage 3 is at the position c (home position) in the sub-scanning direction, the reading control unit 21 causes the image sensor 5 to read the black reference data.

  Subsequently, the reading control unit 21 turns on the LED light source 6 (step S25 in FIG. 2) and executes a white reference reading process (step S26 in FIG. 2). Specifically, as shown in FIG. 3B, the reading control unit 21 operates so that the carriage 3 scans on the white reference plate (b in FIG. 3) in the sub-scanning direction. The sensor 5 is caused to read white reference data.

The reading control unit 21 stores the read shading data (black reference data and white reference data) in the memory C of the temporary storage memory 22 (step S27 in FIG. 2). (As shown in FIG. 3, at this point, the shading data is not set in the shading memory 25.)
When the setting information is acquired in this way, the reading control unit 21 places the image reading apparatus 1 in an idle state. At this time, as shown in FIG. 3C, the reading control unit 21 moves the carriage 3 to the idle position (c2 in FIG. 3) in the sub-scanning direction.

  As described above, the process at power-on is completed.

  Next, processing when a document reading instruction is received (when a scanning instruction is received) will be described. FIG. 4 is a flowchart illustrating a processing procedure when a scanning instruction is received. FIG. 5 is a diagram for explaining the operation of the carriage 3 at the time of receiving a scanning instruction.

  When a user operation or the like is performed on the image reading apparatus 1 and a document reading instruction is issued, the reading control unit 21 receives the instruction and first determines the reading mode of the instructed process (FIG. 4). Step S31).

  Next, based on the determination result, the reading control unit 21 sets setting information including shading data suitable for the determined reading mode to a predetermined location using data stored in the temporary storage memory 22. .

  Specifically, as a result of the determination, if the reading mode is the reading mode (1) (color: monochrome, resolution 300 dpi), the reading control unit 21 acquires the reading mode (generated) when the power is turned on (generated). 4) The shading data for the reading mode (1) is generated from the shading data for the (highest resolution, most color mode).

  Specifically, the reading control unit 21 copies the shading data stored in the memory C of the temporary storage memory 22 to the memory D (processing memory) of the temporary storage memory 22 (step S32 in FIG. 4).

  Next, the reading control unit 21 executes a process of adding data (gradation value) by two pixels for the shading data in the memory D, and converts the resolution of the shading data (step S33 in FIG. 4). Here, 600 dpi data is converted into 300 dpi data.

  Thereafter, the reading control unit 21 executes processing for converting color data into monochrome data for the shading data subjected to resolution conversion. That is, since the shading data subjected to resolution conversion is color data, the data is converted into monochrome data in accordance with the reading mode (1). The color shading data is assumed to be composed of density gradation values of each color of R (red), G (green), and B (blue).

  Specifically, the reading control unit 21 adds the RGB gradation values for each pixel of the shading data, for example, at a ratio of R: G: B = 3: 6: 1 to obtain a monochrome gradation value. Data is set (step S34 in FIG. 4).

  In this way, since the shading data for the reading mode (1) is generated in the memory D, the reading control unit 21 sets the shading data in the shading memory 25 (step S35 in FIG. 4).

  Subsequently, the reading control unit 21 sets the light source lighting time stored in the memory A1 in step S5 in the light source register 23, and sets the AFE gain / offset value stored in the memory B1 in step A5 in the AFE register 24. (Steps S36 and S37 in FIG. 4). Thereafter, the process proceeds to step S51.

  Returning to step S31, if the reading mode is the reading mode (2) (color: color, resolution 300 dpi) as a result of the determination, the reading control unit 21 similarly obtains (generates) when the power is turned on. The shading data for the reading mode (2) is generated from the shading data for the reading mode (4) (the mode with the highest resolution and the largest number of colors).

  In this case, the reading control unit 21 executes only resolution conversion among the resolution conversion and monochrome conversion performed in the reading mode (1).

  Specifically, the reading control unit 21 copies the shading data stored in the memory C of the temporary storage memory 22 to the memory D (processing memory) of the temporary storage memory 22 (step S38 in FIG. 4). As in the reading mode (1), the 600 dpi shading data is converted to 300 dpi data (step S39 in FIG. 4).

  In this way, since the shading data for the reading mode (2) is generated in the memory D, the reading control unit 21 sets the shading data in the shading memory 25 (step S40 in FIG. 4).

  Subsequently, the reading control unit 21 sets the light source lighting time stored in the memory A2 in step S10 in the light source register 23, and sets the AFE gain / offset value stored in the memory B2 in the AFE register 24 in step S10. (Steps S41 and S42 in FIG. 4). Thereafter, the process proceeds to step S51.

  Returning to step S31, if the reading mode is the reading mode (3) (color: monochrome, resolution 600 dpi) as a result of the determination, the reading control unit 21 similarly obtains (generates) when the power is turned on. The shading data for the reading mode (3) is generated from the shading data for the reading mode (4) (the mode with the highest resolution and the largest number of colors).

  In this case, the reading control unit 21 executes only monochrome conversion among resolution conversion and monochrome conversion performed in the reading mode (1).

  Specifically, the reading control unit 21 copies the shading data stored in the memory C of the temporary storage memory 22 to the memory D (processing memory) of the temporary storage memory 22 (step S43 in FIG. 4). As in the reading mode (1), the color shading data is converted into monochrome data (step S4 in FIG. 4).

  In this way, since the shading data for the reading mode (3) is generated in the memory D, the reading control unit 21 sets the shading data in the shading memory 25 (step S45 in FIG. 4).

  Subsequently, the reading control unit 21 sets the light source lighting time stored in the memory A3 in step S15 in the light source register 23, and sets the AFE gain / offset value stored in the memory B3 in step A15 in the AFE register 24. (Steps S46 and S47 in FIG. 4). Thereafter, the process proceeds to step S51.

  Returning to step S31, if the reading mode is the reading mode (4) (color: color, resolution 600 dpi) as a result of the determination, the reading control unit 21 reads the shading data of the reading mode (4). Is stored when the power is turned on, and settings are made using that data. That is, since the shading data for the reading mode (4) is stored in the memory C, the reading control unit 21 sets the shading data in the shading memory 25 (step S48 in FIG. 4).

  Subsequently, the reading control unit 21 sets the light source lighting time stored in the memory A4 in step S20 in the light source register 23, and sets the AFE gain / offset value stored in the memory B4 in step A20 in the AFE register 24. (Steps S49 and S50 in FIG. 4). Thereafter, the process proceeds to step S51.

  When the process proceeds to step S51, the reading control unit 21 performs a shading data correction process. This correction is because the output value of the image sensor 5 depends on the temperature, and the temperature of the image sensor 5 changes when the power is turned on and when the scanning instruction is received.

  Specifically, the reading control unit 21 first turns off the LED light source 6 (step S51 in FIG. 4), and performs black reference reading at that position (idling position) without moving the carriage 3 (see FIG. 4). 4 step S52). When the power is turned off, the black reference data can be read at any position in the sub-scanning direction of the document table.

  Next, the reading control unit 21 checks whether or not the read black reference data is obtained in a correct state. This is because when the scanner cover is open, the black reference data read due to the influence of external light has an abnormal value.

  Specifically, the reading control unit 21 determines whether or not the value of the read black reference data is equal to or greater than a predetermined threshold (step S53 in FIG. 4). The determination may be made using all (pixel) data read by the image sensor 5, but the influence of external light also changes depending on the opening degree of the scanner cover. It is preferable to judge using the data.

  Specifically, the direction in which the sensor chips of the image sensor 5 are arranged (main scanning direction) is a direction that is substantially perpendicular to the hinge portion where the scanner cover is attached to the document table, so that it is far from the hinge portion where external light is likely to enter. It is preferable to use data acquired by the image sensor 5, in other words, pixel data within a predetermined range located on the opposite side of the hinge portion in the main scanning direction.

  As a result of the determination, if the value of the read black reference data is equal to or greater than a predetermined threshold (Yes in step S53 in FIG. 4), the reading control unit 21 moves the carriage 3 to the position of the white reference plate. The black reference data is read again (step S52). The white reference plate is provided at a position that is not affected by external light.

  On the other hand, as a result of the determination, if the value of the read black reference data is not equal to or greater than the predetermined threshold (No in step S53 in FIG. 4), the reading control unit 21 obtains the black reference value variation ΔBK ( Step S55 in FIG. Specifically, the reading control unit 21 determines the gradation value of each pixel of the black reference data read when the power is turned on or the black reference data (black reference data stored in the shading memory 25) obtained based on the black reference data. BK0, and the gradation value of each pixel of the black reference data read this time is BK1, the black reference value variation ΔBK is calculated from ΔBK = BK1−BK0. Note that this calculation is performed on pixels at the same position.

  Next, the reading control unit 21 changes the black reference data set in the shading memory 25 to the black reference data read this time (read in step S52), and is set in the shading memory 25. The white reference data is changed to data obtained by adding the black reference value variation ΔBK to each pixel data of the white reference data (step 56 in FIG. 4).

  The change of the white reference data is not limited to the method of adding the black reference value variation ΔBK, and may be performed using a predetermined calculation based on the black reference value variation ΔBK according to the characteristics of the image sensor 5. .

  When the correction of shading data is executed in this way, the preparation of each setting information for the scanning process (original reading process) is completed, so that the reading control unit 21 reads the original (FIG. 4). Step 57).

  Specifically, the reading control unit 21 activates the ADF, supplies the document to the document table, turns on the LED light source 6 based on the light source lighting time set in the light source register 23, and the supplied document Is read by the image sensor 5 in the sub-scanning direction.

  An analog signal output from the image sensor 5 is amplified and converted into digital data by an A / D converter (AFE) 26. The digital data is input to the digital data processing unit 27, and shading correction is performed based on the shading data set in the shading memory 25 by the arithmetic circuit of the digital data processing unit 27.

  The digital data (image data) after the shading correction is output from the image reading apparatus 1 to a PC or the like.

  In this way, when the instructed scanning process is completed, the image reading apparatus 1 enters an idle state.

  As described above, when receiving a scanning instruction, as shown in FIG. 5, the shading data stored in the temporary storage memory 22 or the shading data calculated from the data is set in the shading memory 25. Therefore, as shown in FIGS. 5A and 5B, there is no need to move the carriage 3 to the position of the white reference plate, and a position for reading a document fed from the ADF (ADF reading position). Just move to. Further, since the black reference data for correcting the shading data can be read at any position on the document table, it is not necessary to move the carriage 3 for that purpose.

  In the above description based on FIG. 4, the processing procedure for checking the black reference data read in order to correct the shading data is described. However, on the assumption that the scanner cover is securely closed, the checking step is performed. It is good also as a processing procedure which omits (S53, S54).

  As described above, in the image reading apparatus 1 according to the present embodiment, shading data for shading correction performed at the time of document reading is generated when the power is turned on, and the black reference data is re-read at the time of document reading. The shading data is corrected and the shading data after correction is set. Accordingly, the operation such as movement of the carriage 3 to the white reference plate can be omitted, and the processing time at the time of receiving the document reading instruction can be shortened. Further, since the reading error due to the temperature difference of the image sensor 5 can be eliminated by correcting the shading data, the accuracy of the shading correction can be maintained.

  Further, when correcting the shading data, the white reference data is corrected based on the reread black reference data, and therefore it is not necessary to read the white reference data again.

  Further, when the power is turned on, the light source lighting time, AFE gain / offset value, and the like necessary for the document reading process are also generated. Therefore, it is only necessary to set such information at the time of document reading. The processing time at the time can be shortened.

  Of the multiple scanning modes, the shading data is generated when the power is turned on for the scanning mode with the highest resolution and the maximum number of colors, and the other scanning modes are calculated from the generated shading data at the time of document scanning. Generated. Therefore, it is possible to shorten the processing time when the power is turned on and to suppress the amount of data to be saved.

  Further, the black reference data re-read when correcting the shading data is evaluated, and if it is determined to be an abnormal value, the black reference data is re-read at a position that is not affected by external light. Therefore, even when the scanner cover is opened and external light enters the document table, accurate correction that eliminates the influence of external light is possible.

  Furthermore, since the evaluation of the black reference data is performed based on data at a position that is easily affected by external light, a correct evaluation can be performed.

  In this embodiment, the shading data for the reading modes (1) to (3) is generated when the document reading instruction is received. However, the shading data is generated when the power is turned on, and when the document reading instruction is received. In any reading mode, the generated shading data may be set in the shading memory 25 without calculation.

  In this specification, the CPU may be composed of one or a plurality of CPUs, or may be composed of one or a plurality of integrated circuits (for example, ASIC). The CPU may be configured by a combination of one or more CPUs and one or more integrated circuits.

  The protection scope of the present invention is not limited to the above-described embodiment, but covers the invention described in the claims and equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Image reading apparatus, 2 ... Control part, 3 ... Carriage, 4 ... Drive mechanism, 5 ... Image sensor, 6 ... LED light source, 21 ... Reading control part, 22 ... Temporary storage memory, 23 ... Light source register, 24 ... AFE Register, 25 ... shading memory, 26 ... A / D converter, 27 ... digital data processor.

Claims (7)

An image reading apparatus that reads a document and generates image data,
An image sensor for reading the document;
A digital data processing unit that corrects the data of the document read by the image sensor based on shading data including black reference data and white reference data, and generates the image data;
A reading control unit that generates the shading data from the data read by the image sensor,
The reading control unit generates the shading data when the image reading apparatus is turned on, generates the black reference data when reading the document, and generates the black reference data based on the black reference data. An image reading apparatus for correcting shading data. In claim 1,
The reading control unit corrects the white reference data of the generated shading data based on a difference between the black reference data of the generated shading data and the black reference data generated when the original is read. An image reading apparatus. In claim 1 or 2,
Furthermore,
A light source that emits light to the document;
An A / D converter that digitally converts an analog signal output from the image sensor, and the reading control unit, when the image reading device is turned on, a light source lighting time for the light source, A gain / offset value for the A / D conversion unit is generated. In any one of Claims 1 thru | or 3,
It has multiple reading modes with different resolution and number of colors,
The reading control unit generates the shading data for the reading mode having the highest resolution and the largest number of colors when the image reading apparatus is turned on, and for the other reading modes, the reading resolution unit has the highest resolution and the largest number of colors. An image reading apparatus, wherein the shading data is generated by calculation from shading data in a reading mode. In any one of Claims 1 thru | or 4,
The reading control unit moves the image sensor to a position not affected by external light when the value of the black reference data generated when reading the document is equal to or greater than a predetermined threshold. The black reference data is generated again from the data read by the image sensor. In claim 5,
Furthermore,
A document table placed when the document is read by the image sensor;
A scanner cover attached to the document table so that the surface of the document table can be opened and closed by a hinge extending in a direction crossing the longitudinal direction of the image sensor;
The reading control unit uses black reference data based on data read at a position away from the hinge of the image sensor to determine whether the value of the black reference data is equal to or greater than a predetermined threshold. An image reading apparatus. An image reading apparatus that reads an original and generates image data, the image sensor reading the original, and data of the original read by the image sensor based on shading data including black reference data and white reference data And a digital data processing unit for generating the image data, and a control unit of the image reading apparatus,
When the image reading device is turned on, the shading data is generated from the data read by the image sensor, the black reference data is generated when the original is read, and based on the black reference data A program for correcting the generated shading data and executing a process.