JP2019161561A - Image reading device and image forming apparatus - Google Patents

Abstract

To appropriately update reference data while reducing a waiting time before the start of reading of a document.SOLUTION: In an image reading device 11 of the present invention, upon completion of reading of an image of a document performed by a CCD 37, a control unit 51 causes the CCD 37 to read a white reference member 33, generates white reference data and black reference data on the basis of an output from the CCD 37, and stores the white reference data and black reference data in a memory. In reading of an image of the next document performed by the CCD 37, an image processing unit 47 reads the white reference data and black reference data from the memory and performs shading correction on the output from the CCD 37 by using the white reference data and black reference data.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image reading apparatus and an image forming apparatus including an image sensor that reads an image of a document, and more particularly to a technique for performing shading correction on an output of an image sensor.

  The image reading apparatus is used alone or mounted on an image forming apparatus. For example, while an original is pulled out from a tray and conveyed, the original is illuminated by a light source and an image of the original is read by an image sensor. In addition, the white reference member is read by the image sensor before reading the image of the original, and reference data is generated based on the output of the image sensor. Using the reference data, the output of the image sensor that has read the image of the original is used. So-called shading correction is performed to control the gain.

  For example, in Patent Document 1, when the original reading apparatus is shipped from the factory or during maintenance, the white reference chart is read to generate first reference data, and the white reference plate is read to generate second reference data. Data and second reference data are stored. Then, during the period from when the power is turned on to before reading the document image, the white reference plate is read to generate third reference data, and the third reference data is multiplied by the first reference data and divided by the second reference data. The correction value for shading correction is determined. Thus, accurate shading correction can be performed on the image data of the document at any timing from when the power is turned on to before reading the document image without using the white reference chart.

  In Patent Document 2, during warm-up of a copying machine after power-on, the white plate is read to acquire reference data, and the temperature detected by the temperature sensor is held. When the temperature newly detected by the temperature sensor changes by a predetermined value or more with respect to the held temperature, the reference data is acquired again by reading the white plate at the standby timing. As a result, the shading correction is performed at an appropriate timing without increasing the copy sequence time.

JP 2011-151478 A JP 2000-50064 A

  However, in Patent Document 1, since the third reference data is generated by reading the white reference plate before reading the image of the document, the standby time until the reading of the document is started becomes long. Further, in Patent Document 2, since the reference data is updated only when the temperature change becomes large, the reference data is not updated at all in a room where the temperature change is small, and shading correction is not performed accurately. Sometimes.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to appropriately update shading correction by appropriately updating reference data while shortening the waiting time before starting reading of a document.

  An image reading apparatus according to an aspect of the present invention includes a light source that illuminates a document, an image sensor that receives reflected light from the document and reads an image of the document, and is illuminated by the light source, and the image sensor When the reading of the original image by the image sensor is completed, the white reference member is read by the image sensor, and the image is read out. A control unit that generates the reference data based on the output of the sensor and stores the reference data in the storage unit, and when the image of the next document is read by the image sensor, the reference data is read from the storage unit, An image processing unit that performs shading correction on the output of the image sensor using the reference data; It is as it has.

  An image forming apparatus according to an aspect of the present invention is an image forming apparatus including the image reading apparatus according to the present invention, and an image forming unit that forms an image of a document read by the image reading apparatus on a recording sheet. .

  According to the present invention, it is possible to appropriately perform the shading correction by appropriately updating the reference data while shortening the waiting time before starting the reading of the document.

1 is a cross-sectional view illustrating an image forming apparatus including an image reading apparatus according to an embodiment of the present invention. It is sectional drawing which shows an image reading apparatus. FIG. 2 is a perspective view showing an appearance of the image reading apparatus, and shows a state in which a document feeding unit is opened. 2 is a functional block diagram illustrating a main internal configuration of the image forming apparatus. FIG. It is a figure which shows notionally the data table in which white reference data and black reference data were written according to several reading linear velocity of an image reading apparatus. It is a flowchart which shows the procedure of writing the white reference data and the black reference data to the data table at the time of factory shipment or maintenance. It is a flowchart which shows the process sequence for performing a shading correction | amendment to image data using white reference data and black reference data. It is a figure which shows notionally another example of the data table in which white reference data and black reference data were written.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating an image forming apparatus including an image reading apparatus according to an embodiment of the present invention. The image forming apparatus 10 according to the present embodiment is an MFP (multifunction machine) having a plurality of functions such as a copy function, a printer function, and a scanner function. The image forming apparatus 10 includes an image reading device 11 and an image forming unit 12.

  The image reading device 11 has an image pickup device (CCD) that optically reads an image of a document, and the analog output of the CCD is converted into a digital signal to generate image data indicating the image of the document.

  The image forming unit 12 prints an image indicated by the image data on a recording sheet. The image forming unit 3M for magenta, the image forming unit 3C for cyan, the image forming unit 3Y for yellow, and the image for black Image forming unit 3Bk. In each of the image forming units 3M, 3C, 3Y, and 3Bk, the surface of the photosensitive drum 4 is uniformly charged, the surface of the photosensitive drum 4 is exposed, and an electrostatic latent image is formed on the surface of the photosensitive drum 4. The electrostatic latent image on the surface of the photosensitive drum 4 is developed into a toner image, and the toner image on the surface of the photosensitive drum 4 is primarily transferred to the intermediate transfer belt 5. As a result, a color toner image is formed on the intermediate transfer belt 5. This color toner image is secondarily transferred to the recording paper P conveyed through the conveyance path 8 from the paper supply unit 14 in the nip region N between the intermediate transfer belt 5 and the secondary transfer roller 6.

  Thereafter, the recording paper P is heated and pressurized by the fixing device 15, the toner image on the recording paper P is fixed by thermocompression bonding, and the recording paper P is discharged to the discharge tray 17 through the discharge roller 16.

  FIG. 2 is a cross-sectional view showing the image reading apparatus 11 of the present embodiment. FIG. 3 is a perspective view showing the appearance of the image reading apparatus 11 and shows a state in which the document feeder 20 is opened.

  As shown in FIGS. 2 and 3, the image reading apparatus 11 includes a document feeding unit 20 and a reading unit 30. The document feeding unit 20 is provided on the upper surface of the reading unit 30 so as to be openable and closable by a hinge or the like. When the document feeding unit 20 is opened, the first platen glass 31 and the second platen glass 32 of the reading unit 30 are provided. Is opened and a document can be placed on the second platen glass 32, and when the document feeding unit 20 is closed, the document cover 21 of the document feeding unit 20 is placed on the second platen glass 32. Press the original document MS.

  The document feeder 20 includes a document cover 21, a document feed tray 22, a pickup roller 25, a transport roller 26, a discharge roller 27, a document discharge tray 28, and the like. A reading opening 38 that is long in the main scanning direction X and is located between the transport roller 26 and the paper discharge roller 27 is formed at the bottom of the document feeder 20.

  The reading unit 30 includes a first platen glass 31, a second platen glass 32, a white reference plate 33, a carriage 34, an optical system unit 35, a condenser lens 36, a CCD (Charge Coup Device) 37, and the like.

  The carriage 34 includes an LED 34 </ b> A that irradiates light to the original MS and a mirror 34 </ b> C that reflects light reflected by the original MS. The optical system unit 35 includes a mirror 35A and a mirror 35B. The carriage 34 and the optical system unit 35 are provided so as to reciprocate in the sub-scanning direction Y perpendicular to the main scanning direction along the rail.

  The white reference plate 33 is a white plate for shading correction provided between the first platen glass 31 and the second platen glass 32.

  Here, when the document MS is set on the document feed tray 22 of the document feeder 20, the carriage 34 and the optical system unit 35 are positioned as shown in FIG. In this state, the pickup roller 25, the transport roller 26, and the paper discharge roller 27 pull out the document MS from the document feed tray 22 and transport it to the first platen glass 31 through the reading opening 38, and further the document MS. Is conveyed from the first platen glass 31 to the document discharge tray 28 and discharged.

  In the reading unit 30, the light of the LED 34 </ b> A of the carriage 34 is applied to the original MS that passes over the first platen glass 31, and the light reflected by the original MS is reflected by the mirror 34 </ b> C of the carriage 34. Further, this light is reflected by the mirror 35 A and the mirror 35 B of the optical system unit 35, and enters the CCD 37 through the condenser lens 36. The condenser lens 36 forms an image of the original on the light receiving surface of the CCD 37, and the CCD 37 reads the image of the original MS.

  Further, when the document MS is placed on the second platen glass 32, the carriage 34 and the optical system unit 35 of the reading unit 30 are moved in the sub-scanning direction Y while maintaining a predetermined speed relationship.

  In the reading unit 30, the light of the LED 34 </ b> A is applied to the original MS on the second platen glass 32, and the light reflected by the original MS is sequentially reflected by the mirror 34 </ b> C, the mirror 35 </ b> A, and the mirror 35 </ b> B. The light is incident on the CCD 37 and the image of the document MS is read by the CCD 37.

  The operation of reading the image of the document MS by the reading unit 30 while conveying the document MS by the document feeding unit 20 is referred to as a DP mode, and the document MS placed on the second platen glass 32 by the reading unit 30. The operation of reading the image is referred to as a table mode.

  Next, a configuration related to the control of the image reading apparatus 11 and the image forming apparatus 10 will be described. FIG. 4 is a functional block diagram showing the main internal configuration of the image forming apparatus 10. As shown in FIG. 4, the image forming apparatus 10 includes a control unit 41, a display unit 42, an operation unit 44, a touch panel 45, an image memory 46, an image processing unit 47, a storage unit 48, the image reading device 11, and the image forming unit 12. Etc. These components can transmit / receive data or signals to / from each other through a bus.

  The display unit 42 includes a liquid crystal display (LCD), an organic EL (Organic Light-Emitting Diode) display, and the like.

  The operation unit 44 includes hard keys such as a numeric keypad, a determination key, and a start key.

  A touch panel 45 is superimposed on the screen of the display unit 42. The touch panel 45 is a so-called resistive film type or capacitive type touch panel, and detects the touch (touch) of the user's finger or the like to the touch panel 45 together with the contact position, and the GUI on the screen of the display unit 42 or the like. Enter user instructions. Accordingly, the touch panel 45 serves as an operation unit to which a user operation on the screen of the display unit 42 is input.

  The image memory 46 temporarily stores image data indicating an image of a document read by the image reading device 11.

  The image processing unit 47 performs various image processing such as shading correction on the image data in the image memory 46.

  The storage unit 48 includes a RAM, a large capacity HDD (Hard Disk Drive), and the like, and stores various data and programs.

  The control unit 41 includes a processor, a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The processor is a CPU (Central Processing Unit), MPU, ASIC, or the like. The control unit 41 functions as the control unit 51 when the control program stored in the ROM or the storage unit 48 is executed by the processor. In addition, each said structure of the control unit 41 may be comprised with a hardware circuit, respectively, not based on the operation | movement based on a control program.

  The control unit 51 serves as a processing unit that executes various processes. The control unit 51 controls the display unit 42 to display various setting screens and information.

  Next, white reference data and black reference data used for shading correction of image data will be described.

  The control unit 51 controls the image reading device 11 to turn on the LED 34A of the carriage 34 in a state where the carriage 34 and the optical system unit 35 are appropriately positioned (positioned below the white reference plate 33). The white reference plate 33 is illuminated by the LED 34 </ b> A, and the white reference plate 33 is read by the CCD 37. Then, the control unit 51 generates white reference data for shading correction based on the output of the CCD 37 when the white reference plate 33 is illuminated, and this white reference data is stored in the memory (for example, EPROM) of the control unit 41. Remember. Further, the control unit 51 turns off the LED 34A, generates black reference data for shading correction based on the output of the CCD 37 at this time, and stores this black reference data in the memory of the control unit 41.

  The control unit 51 generates the white reference data and the black reference data for each of a plurality of preset reading linear velocities of the CCD 37, and associates the white reference data and the black reference data with the reading linear velocities to control unit 41. Store in the memory.

  FIG. 5 is a diagram conceptually showing a data table in the memory of the control unit 41 in which white reference data and black reference data are written for each of a plurality of reading linear velocities. In the data table DT shown in FIG. 5, six reading linear velocities A, B, C, D, E, and F are set in advance, and these reading linear velocities A, B, C, D, E, and F White reference data and black reference data are stored.

  Further, in the data table DT, the reading linear velocities A, B, C, D, E, and F are set to a color mode, a monochrome mode, a reading line density, a DP mode for reading an image of the original while conveying the original, This is associated with a combination of table modes for reading a document image on the two-platen glass 32. For example, the reading line speed A corresponds to a combination of a color mode, a reading line density of 600 dpi, and a DP mode. The reading line speed B corresponds to a combination of the monochrome mode, the reading line density of 600 dpi, and the DP mode. Further, the reading linear velocity C corresponds to the combination of the color mode, the reading linear density 300 dpi, and the DP mode, and the reading linear velocity D corresponds to the combination of the monochrome mode, the reading linear density 300 dpi, and the DP mode. The reading linear velocity E corresponds to a combination of the color mode, the reading linear density 600 dpi, and the table mode, and the reading linear velocity F corresponds to the combination of the monochrome mode, the reading linear density 600 dpi, and the table mode.

  Next, the procedure for writing the white reference data and the black reference data to the data table DT at the time of factory shipment or maintenance will be described with reference to the flowchart shown in FIG.

  At the time of factory shipment or maintenance, the control unit 51 controls the image reading device 11, sets the reading linear velocity of the CCD 37 to the reading linear velocity A, and appropriately positions the carriage 34 and the optical system unit 35. The white reference data and the black reference data are generated as described above (S101), and the white reference data and the black reference data are written and stored in the data table DT (S102).

  Subsequently, the control unit 51 determines whether or not white reference data and black reference data have been acquired for all the reading linear velocities (S103), and the reading linear velocities for which white reference data and black reference data have not been acquired are determined. If it is determined that there is (S103 “No”), S101 and S102 are repeated. As a result, the white reference data and the black reference data are also generated and written in the data table DT for the other reading linear velocities B to F.

  When determining that the white reference data and the black reference data have been acquired for all the reading linear velocities (S103 “Yes”), the control unit 51 ends the processing of FIG.

  Next, referring to the flowchart shown in FIG. 7, a processing procedure for performing shading correction on image data representing an image of a document using such a plurality of white reference data and black reference data for each reading linear velocity. I will explain.

  First, the user operates the operation unit 44 or the touch panel 45 to input a color mode or monochrome mode designation and a reading line density designation before starting the reading of a document by the image reading apparatus 11.

  In addition, the user sets the document on the document feed tray 22 or the second platen glass 32. The document feed tray 22 is provided with a DP sensor (not shown) for detecting a document set on the document feed tray 22, and the second platen glass 32 is set on the second platen glass 32. A table sensor (not shown) for detecting the original document is provided.

  On the other hand, the control unit 51 waits for the color mode or the monochrome mode and the reading line density to be designated by the operation of the operation unit 44 or the touch panel 45, and for the document to be detected by the DP sensor or the table sensor ( S201 “No”). Then, when the color mode or the monochrome mode and the reading line density are designated and the original is detected by the DP sensor (S201 “Yes”), the control unit 51 controls the image reading device 11 to control the carriage 34. Then, the optical system unit 35 is moved to the first reading position for reading the document conveyed on the first platen glass 31, and the DP mode is set (S202). Alternatively, when the color mode or the monochrome mode and the reading line density are designated, and the document is detected by the table sensor (S201 “Yes”), the control unit 51 controls the image reading device 11 to control the carriage 34. Then, the optical system unit 35 is moved to the second reading position where the reading of the document placed on the second platen glass 32 is started, and the table mode is set (S202).

  Further, the control unit 51 obtains a combination of the color mode or monochrome mode, the reading line density, the DP mode, or the table mode designated by the operation of the operation unit 44 or the touch panel 45, and sets the reading line speed corresponding to this combination as data. The data is read from the table DT, and this read linear velocity is instructed to the image processor 47 (S203).

  Thereafter, the control unit 51 waits for a copy start instruction based on the operation of the operation unit 44 or the touch panel 45 by the user (S204 “No”). When the copy start is instructed (S204 “Yes”), the image reading is performed. The document is read by the apparatus 11, and image data indicating the image of the document is stored in the image memory 46 (S205).

  When the reading linear velocity is instructed from the control unit 51 in S203, the image processing unit 47 reads white reference data and black reference data corresponding to the reading linear velocity from the data table DT, and reads the read white reference data and Using the black reference data, the image data in the image memory 46 is subjected to shading correction (S206). At this time, the image processing unit 47 performs various other image processing such as gamma correction and chromatic aberration correction on the image data in the image memory 46 in addition to the shading correction.

  The image forming unit 12 inputs image data from the image memory 46 and prints an image indicated by the image data on a recording sheet (S207).

  Subsequently, the control unit 51 detects whether or not the next document set on the document feeding tray 22 is detected by the DP sensor, or detects the next document placed on the second platen glass 32 by the table sensor. If it is determined whether or not the next document has been detected (S208 “Yes”), the processing from S205 is repeated.

  If the control unit 51 determines that the next document has not been detected (“No” in S208), the control unit 51 controls the image reading device 11 in the same procedure as at the time of factory shipment or maintenance, and reads each reading line of the CCD 37. For each speed A to F, white reference data and black reference data are generated, written and stored in the data table DT, and the data table DT is updated (step S209). Thereafter, the processing returns to S201.

  As described above, in the present embodiment, when the original is read by the image reading apparatus 11, a combination of the color mode or the monochrome mode, the reading linear density, the DP mode, or the table mode is obtained, and the reading linear velocity corresponding to this combination is obtained from the data table. The white reference data and black reference data corresponding to the selected reading linear velocity are read from the data table DT, and the image data in the image memory 46 is read using the read white reference data and black reference data. The shading correction is applied to. By using the white reference data and the black reference data corresponding to the reading linear velocity, the shading correction can be accurately performed.

  When all the originals have been read, white reference data and black reference data are generated and written to the data table DT for each of the reading linear velocities A, B, C, D, E, and F. Since it is updated, there is no need to perform a reading operation for acquiring white reference data and black reference data before the image reading device 11 starts reading the document, and the waiting time before the document reading starts is shortened. be able to. Further, at the same time when the document set on the document feed tray 22 is detected by the DP sensor, the carriage 34 and the optical system unit 35 are moved to the first reading position for reading the document conveyed on the first platen glass 31. Therefore, the DP mode can be started quickly. Similarly, the document set on the second platen glass 32 is detected by the table sensor, and at the same time, the carriage 34 and the optical system unit 35 start reading the document placed on the second platen glass 32. 2 Since it is moved to the reading position, the table mode can be started promptly.

  On the other hand, conventionally, before the reading of the original by the image reading device 11, the carriage 34 and the optical system unit 35 are temporarily stopped at the position of the white reference plate 33, and an operation of reading the white reference plate 33 is performed. Since the reference data is generated and the black reference data is generated by performing the reading operation in the non-illuminated state, the carriage 34 and the optical system unit 35 are moved to the first reading position or the second reading position. The waiting time before starting to read a document has become longer.

  In the present embodiment, since the data table DT is updated every time the reading operation of all originals is completed, the accuracy of shading correction of image data can be continuously maintained.

  In the above embodiment, the influence of the temperature change of the CCD 37 is not taken into consideration, but the white reference data and the black reference data may be corrected according to this temperature change. In this case, a temperature sensor for detecting the temperature of the CCD 37 is provided. When generating the white reference data and the black reference data, the control unit 51 writes the first temperature detected by the temperature sensor in the data table DT in association with the white reference data and the black reference data as shown in FIG. Remember. Then, when the image of the next original is read by the image reading device 11 and the image data indicating the image of the next original is stored in the image memory 46, the control unit 51 is detected by the temperature sensor at this time. The second temperature is acquired, and the first temperature is read from the data table DT. Based on the difference between the first temperature and the second temperature, for example, using a coefficient set in advance according to the value of the temperature difference, Each value of the white reference data and the black reference data stored in the data table DT in association with the first temperature is corrected. The image processing unit 47 performs shading correction on the image data in the image memory 46 using the corrected white reference data and black reference data. This makes it possible to perform more accurate shading correction.

  Further, the white reference data and the black reference data may be corrected in accordance with the light amount change in consideration of the influence of the light amount change of the LED 34A. In this case, when generating the white reference data and the black reference data, the control unit 51 acquires the first output level (the amount of received light) of the CCD 37 when the white reference plate 33 is illuminated by the LED 34A. The output level is written in the data table DT in association with the white reference data and black reference data. Then, the controller 51 temporarily stops the carriage 34 and the optical system unit 35 at the position of the white reference plate 33 before reading the image of the next document, and the white reference plate 33 is illuminated by the LED 34A. The second output level (the amount of received light) of the CCD 37 is obtained, and thereafter the image of the next document is read by the image reading device 11 and the image data indicating the image of the next document is stored in the image memory 46. Further, the control unit 51 reads the first output level from the data table DT, and based on the difference between the first output level and the second output level, for example, according to the value of the difference between the first output level and the second output level. Using the coefficient set in advance, each value of the white reference data and the black reference data stored in the data table DT in association with the first output level is corrected. The image processing unit 47 performs shading correction on the image data in the image memory 46 using the corrected white reference data and black reference data. This also makes it possible to perform more accurate shading correction. However, although it is shorter than the time for generating the white reference data and the black reference data for each reading linear velocity, a time for obtaining the second output level of the CCD 37 occurs.

  Further, the control unit 51 measures the elapsed time from the generation of the white reference data and the black reference data, and when the elapsed time reaches a predetermined time set in advance, the carriage 34 and the optical system unit 35 are moved to the white reference plate. It is also possible to move to position 33, generate white reference data and black reference data for each reading linear velocity, and store and update the white reference data and black reference data in the memory of the control unit 41.

  Further, as described in the above embodiment, after the document reading operation is completed, white reference data and black reference data are generated and written to the data table DT for each reading linear velocity, and the white reference data and black reference data are used. The shading correction is set to the first shading correction mode, and the white reference data and the black reference data are generated and written to the data table DT for each reading linear velocity before the reading of the document is started. The white reference data and the black reference data are stored in the data table DT. The control unit 51 may switch between the first shading correction mode and the second shading correction mode with the shading correction to be used as the second shading correction mode.

  In this case, the user operates the operation unit 44 or the touch panel 45 to select and specify either the first shading correction mode or the second shading correction mode.

  When the first shading correction mode is instructed, the control unit 51 generates white reference data and black reference data based on the first shading correction mode and stores them in the data table DT, and the second shading correction mode is instructed. If so, white reference data and black reference data are generated based on the second shading correction mode and stored in the data table DT. Then, when the image of the document is read by the image reading device 11 and image data indicating the image of the document is stored in the image memory 46, the image processing unit 47 performs white reference data and black reference data of the data table DT. Is used to perform shading correction on the image data in the image memory 46.

  As a result, when the first shading correction mode is selected, the waiting time before the reading of the document is shortened, and when the second shading correction mode is selected, immediately after the white reference data and the black reference data are obtained. Therefore, more accurate shading correction can be performed.

  In the above-described embodiment, the image reading apparatus of the present invention is applied to the image forming apparatus. However, this is only an example, and other image forming apparatuses such as other electronic devices such as a copying machine and a facsimile machine are used. You may apply to.

  The configuration and processing described with reference to FIGS. 1 to 8 are only one embodiment of the present invention, and the present invention is not limited to the configuration and processing.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Image reader 12 Image forming part 20 Document feeding part 21 Document cover 30 Reading part 31 1st platen glass 32 2nd platen glass 33 White reference board 34A LED
37 CCD
41 control unit 42 display unit 44 operation unit 45 touch panel 46 image memory 47 image processing unit 48 storage unit 51 control unit

Claims (7)

A light source that illuminates the document;
An image sensor that receives reflected light from the document and reads an image of the document;
A white reference member illuminated by the light source and read by the image sensor;
A storage unit for storing reference data used for shading correction;
When reading of the image of the document by the image sensor is completed, the image sensor reads the white reference member, generates the reference data based on the output of the image sensor, and stores the reference data in the storage unit A control unit,
An image reading apparatus comprising: an image processing unit that reads the reference data from the storage unit when the image sensor reads an image of the next document and uses the reference data to perform shading correction on the output of the image sensor. . The control unit generates the reference data by reading the white reference member by the image sensor for each of a plurality of preset reading linear velocities, and stores the reference data in the storage unit. ,
The image processing unit reads reference data corresponding to the reading linear velocity of the document image from the storage unit when the image sensor reads the document image, and uses the reference data to output the image sensor. The image reading apparatus according to claim 1, wherein shading correction is performed. A temperature sensor for detecting the temperature of the image sensor;
The control unit stores the first temperature detected by the temperature sensor when the reference data is generated in the storage unit, and the first temperature detected by the temperature sensor when the image image is read by the image sensor. The image reading apparatus according to claim 1, wherein two image temperatures are acquired. The image reading apparatus according to claim 1, wherein the first temperature is read from the storage unit, and the reference data is corrected based on a difference between the first temperature and the second temperature.   The control unit stores a first output level of the image sensor at the time of generation of the reference data in the storage unit, and sets a second output level of the image sensor when the image image is read by the image sensor. The image reading apparatus according to claim 1, wherein the image reading apparatus acquires the first output level from the storage unit and corrects the reference data based on a difference between the first output level and the second output level. .   The control unit counts an elapsed time from the generation of the reference data, and when the elapsed time reaches a predetermined time set in advance, the image sensor further reads the white reference member, and the image sensor 3. The image reading apparatus according to claim 1, wherein the reference data is generated based on the output of the image data, and the reference data is stored and updated in the storage unit. After the past reading of the document image by the image sensor is finished, the shading correction using the reference data generated based on the output of the image sensor is set to the first shading correction mode, and reading of the document image by the image sensor is started. If the shading correction using the reference data generated based on the output of the image sensor before the second shading correction mode is set to the second shading correction mode, either one of the first shading correction mode and the second shading correction mode is instructed. It has an operation unit operated by the user,
The control unit obtains reference data used in the first shading correction mode when the first shading correction mode is instructed by the operation of the operation unit, stores the reference data in the storage unit, and operates the operation unit. When the second shading correction mode is instructed, reference data used in the second shading correction mode is obtained and stored in the storage unit,
2. The image processing unit according to claim 1, wherein when the image sensor reads an image of a document, the image processing unit reads the reference data from the storage unit, and performs shading correction on the output of the image sensor using the reference data. Image reading device. An image reading apparatus according to any one of claims 1 to 6,
An image forming apparatus comprising: an image forming unit that forms an image of a document read by the image reading apparatus on a recording sheet.