Image forming apparatus, method of controlling the same, and storage medium

Abstract

To provide an image forming apparatus capable of executing two reading methods, selecting a reading method according to a purpose, and executing calibration in a flow suitable for the reading method.SOLUTION: A scanner unit 112 includes a printer unit 113 that forms an image on a sheet, a CIS210 that reads a document placed on a document table 213, and a DF unit 200, and an operation unit 114, and when the scanner unit 112 receives a reading start instruction from the operation unit 114 in a state where a document on which a chart is formed is placed on a document tray 201 of the DF unit 200, the scanner unit reads the document on which the chart is formed on the document tray 201 by conveying the document to a pickup roller 205 regardless of whether or not the document is placed on the document table 213.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to calibration control in an image forming apparatus. [Background technology]

[0002] When an electrophotographic image forming device is used continuously, the density of the image printed on paper fluctuates due to various factors, such as the degree of deterioration of the parts that make up the image forming device, the environment (temperature and humidity) in which the image forming device is installed, and consumables such as toner and paper used when the image forming device prints.

[0003] Therefore, calibration is performed so that the density of the image printed by the image forming device is the target density. Specifically, correction data is generated using the color difference between the result of reading a test pattern in which a patch image is printed on a medium such as paper and the target density.

[0004] Patent Document 1 discloses an image forming apparatus that efficiently generates correction data by reading, with a scanner, a test pattern on a document conveyed by an auto document feeder (hereinafter referred to as an ADF).

[0005] Patent Document 2 discloses that an image forming apparatus equipped with an ADF generates correction data using the results of reading a test pattern on a document conveyed by the ADF, and that an image forming apparatus not equipped with an ADF generates correction data using the results of reading a test pattern on a document placed on a document table. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-329929 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-59626 Summary of the Invention [Problem to be solved by the invention]

[0007] However, compared to scanning a document placed on a document table, scanning a document transported by an ADF eliminates the need to open and close the document pressing plate. This reduces the user's workload when scanning multiple documents consecutively at once. On the other hand, scanning a document placed on a document table can sometimes provide higher reading accuracy than scanning a document transported by an ADF.

[0008] Therefore, it is desirable to have one image forming apparatus equipped with these two reading methods, so that the user can use the appropriate reading method depending on the purpose. [Means for solving the problem]

[0009] In order to solve the above problem, the image forming apparatus of the present invention comprises a reading means having an image forming means for forming an image on paper, a document table on which a document is placed, a reading unit for reading the document placed on the document table, a loading unit on which the document is placed, a transport unit for transporting the document loaded on the loading unit so that the document loaded on the loading unit can be read by the reading unit, and a paper output tray to which the document transported by the transport unit is discharged, and a receiving means for receiving user instruction information that instructs the reading means to read a chart used for calibrating the image forming means, wherein when the reading means receives the user instruction information with a document on which the chart is formed loaded on the loading unit, the reading means transports the document on which the chart is formed that is loaded on the loading unit to the transport unit, regardless of whether a document is placed on the document table. [Effects of the Invention]

[0010] According to the present invention, when a user places a chart, which is an original with a printed test pattern, in a desired original placement position, a correction mode for performing calibration is automatically determined based on the placement position, thereby enabling calibration to be performed in accordance with a flow in accordance with the mode automatically determined based on the original placement position. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a system block diagram of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a scanner unit in the present embodiment. [Figure 3] FIG. 2 is a block diagram of a control unit that controls a scanner unit in the present embodiment. [Figure 4] 3 is a flowchart showing the operation in the first embodiment. [Figure 5] 5A and 5B are diagrams showing a method of determining an operation mode in the present embodiment. [Figure 6] 3A to 3C are diagrams illustrating an example of a screen display in the first embodiment. [Figure 7] 10 is a flowchart showing the operation in the second embodiment. [Figure 8] 10A to 10C are diagrams illustrating an example of a screen display in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Best modes for carrying out the present invention will be described in detail below with reference to the drawings.

[0013] It should be noted that the following embodiments do not limit the scope of the present invention as defined in the claims, and not all of the combinations of features described in the present embodiments are necessarily essential to the solution of the present invention. [Example]

[0014] FIG. 1 is a block diagram of a control unit 115 included in the image forming apparatus of this embodiment. Each component of the control unit 115 is connected to a system bus 101 and an image bus 110. ROM 102 stores a system boot program. System software implementing each means of this embodiment is stored in ROM 102 or storage memory 105 and executed by CPU 103. RAM 104 is a system work memory area for CPU 103 to execute the software and also serves as image memory for temporary storage when processing image data. Storage memory 105 is used as internal storage. It stores data scanned by scanner unit 112, image data, system software, and the like. Storage memory 105 is composed of an HDD (hard disk) and an SSD (solid state drive). LAN (local area network) I / F unit 106 is an I / F unit for connecting to a LAN and inputs and outputs information to and from each device connected to the LAN. Line I / F unit 107 is an I / F unit for connecting to a WAN and inputs and outputs information to and from each device connected to the WAN. The above components are mounted on the system bus 101. The IO control unit A 109 is a bus bridge that connects the system bus 101 to an image bus 110, which transfers image data at high speed, and converts the data structure of the system bus 101. The image bus 110 is composed of general-purpose buses such as a PCI bus, IEEE1394, and PCIEx. The following components are mounted on the image bus 110: It connects the image input / output devices, such as a scanner unit 112 and a printer unit 113, to an image processing unit 111, and performs synchronous / asynchronous conversion of image data. The image processing unit 111 is composed of multiple ASICs that perform image processing such as resolution conversion, compression / expansion, and binary / multi-value conversion on input and output image data. The image data operation unit control unit B 108 is an interface unit with the operation unit (User Interface, hereinafter referred to as UI) 114, and outputs image data to be displayed on the operation unit. It also serves to transmit information entered by the system user from the operation unit to the CPU 103. This is an I / F section for software control of the operation section 114 equipped with a display device and a keypad device.In this embodiment, the operation unit 114 is configured with an LCD touch panel or the like, and interprets and displays a VGA signal output from the operation unit control unit B108.

[0015] FIG. 2 is a side cross-sectional view showing the internal structure of a DF (Document Feeder) unit 200 of the scanner unit 112. The DF unit 200 has a document tray 201 on which documents to be read are loaded. On the document tray 201, a document sensor 203 for detecting the presence or absence of a document, two document guides 202, and a document size detection sensor 204 are provided. When the document sensor 203 in the paper transport path detects the presence of a document, the detected document is transported. Two document guides 202 are provided side by side in the document length direction (perpendicular to the document transport direction), and documents loaded on the document tray 201 are transported by three rollers: a pickup roller 205, a transport roller 207, and a paper discharge roller 209. The pickup roller 205 is a roller for transporting documents loaded on the document tray 201 into the document transport path inside the DF unit. The transport roller 207 transports the document transported into the document transport path by the pickup roller 205. Discharge rollers 209 transport the document conveyed by transport rollers 207 to a discharge tray 211. Furthermore, the document conveyed by pickup rollers 205 is detected by document passage detection sensor 206, and based on this detection time, it is determined whether the first document has passed through. Although not shown, the transport rollers 207, pickup roller 205, and discharge rollers 209 are all driven by a stepping motor. Sub-scanning thinning processing in the DF unit is achieved by frequency-doubling the drive pulses of the transport, pickup, and discharge rollers. The document conveyed by the DF unit is read through a DF reading window 208 by a CIS 210, which is a sensor provided in a sensor unit 212 located below the DF reading window. The sensor unit 212 is movable freely in the sub-scanning direction and can also move in the same direction as the document conveyed from transport rollers 207 to discharge rollers 209. The DF reading window 208 has a certain length in the sub-scanning direction, and within this length, the CIS 210 sensor can be moved to any position and the document can be read at that position. The CIS 210 is composed of photoelectric conversion elements such as CCDs, and simultaneously generates a FIFO for storing images from each element and control signals for controlling the FIFO and CCD.The CIS 210 is generally realized by arranging a plurality of photoelectric conversion elements in a line.

[0016] The scanner unit 112 also includes a document table 213. When reading an original via this document table 213, it is possible to open a document pressing plate 214, place the original on the document table 213, close the document pressing plate 214, and then read the original while moving a sensor unit 212 having a CIS 210 in the sub-scanning direction.

[0017] The CIS 210 also has the role of detecting whether or not an original is placed on the platen 213. Since this is a known technique, the details will be omitted, but when the original pressing plate 214 is closed, the CIS 210 reads a portion of the original at the bottom of the platen 213. It is possible to determine whether or not an original is placed on the platen 213 by analyzing the read image.

[0018] In this embodiment, a method of reading a document placed on the tray 201 while conveying it with the sensor unit 212 having the CIS 210 fixed is called an ADF reading mode (first reading mode). On the other hand, a method of reading a document placed on the document table 213 by moving the sensor unit 212 is called a pressure plate reading mode (second reading mode).

[0019] 3 shows a block diagram of hardware for controlling the scanner unit 112 by a scanner unit control application program, and is a block included in the scanner unit 112. The following description will be given assuming that the scanner unit 112 is controlled by a scanner unit control application program executed on a CPU 301 of a scanner control unit 300. The application program for controlling the scanner unit 112 may be executed by a CPU 103 included in the control unit 115. The scanner control unit 300 is composed of a CPU 301, a RAM 302, a CLK control unit 303, a ROM 304, a motor controller unit 305, and a CCD control unit 307. The scanner unit control application program is stored in the ROM 304 and executed by the CPU 301. A clock is distributed from the CLK control unit 303 to each block. The CLK control unit 303 is composed of a crystal oscillator for clock generation and a PLL element that multiplies and divides the clock generated by the crystal oscillator. The scanner control application that controls the scanner control unit 300 outputs a control clock from the CLK control unit 303 to the motor controller unit 305, CCD control unit 307, and RAM 302 based on instructions for scanning. Each block further multiplies and divides the clock input from the CLK control unit 303 to generate control clocks for the motors that rotate the CCD elements and various rollers. The instructions for scanning include information such as color / monochrome distinction and resolution, and the scanner control application changes the PLL settings of the CLK control unit 303 based on the instructions. Changing the PLL settings changes the frequencies of various clocks, thereby changing the reading speed. RAM 304 stores image data read by the CIS 210.

[0020] The operation of the calibration function will be described in detail below. In this embodiment, the generation of correction data used for adjusting the density of an image will be described as an example. However, this embodiment is not limited to this, and can be applied to calibration such as image position adjustment and density unevenness adjustment, in which a patch image is printed on paper, the patch image is read by a scanner unit, and correction data is generated using the read results.

[0021] Next, the flow of the correction data generation process used for density adjustment in this embodiment will be described with reference to Fig. 4. In this embodiment, a case will be described in which three documents (charts) on which predetermined test patterns are printed are printed, the printed test documents are read, and the reading results are used to generate correction data.

[0022] The number of test documents required is generally determined according to the type of dither pattern used by the image forming apparatus when forming an image. This is because correction data must be generated for each dither pattern used when performing image processing. Therefore, in an image forming apparatus capable of using multiple dither patterns, correction data must be generated for each dither pattern. This correction data is generated using the results of scanning a single test document printed using a single dither pattern. Therefore, when generating correction data corresponding to three types of dither patterns (e.g., low screen frequency, high screen frequency, and error diffusion), three test documents are required. In another embodiment, multiple dither patterns may be printed on a single test document. In this case, the number of test documents required will be reduced. The number of test documents may be determined according to the number of dither patterns, or the number of test documents required to generate correction data corresponding to the selected dither pattern may be determined.

[0023] The program of the control unit 115 relating to this flow is stored in the ROM 102 of the control unit 115 , read into the RAM 104 , and executed by the CPU 103 .

[0024] In response to a user's instruction to execute calibration, in step S401, the operation unit 114 selects a paper feed cassette of the printer unit 113 that stores paper on which a test document is to be printed.

[0025] Next, in step S402, an instruction to execute printing is received via operation unit 114. In accordance with this instruction, in step S403, three test documents are printed. Although details are omitted because this is a known technique, when generating correction data, each test document is output using a different dither pattern generated by image processing unit 111. Also, a patch pattern of a color or shape that can distinguish each test document may be printed in the margin so that it can be determined which dither pattern was used to output the scanned test document. Also, numbers indicating the document number may be printed in the margin so that the user can easily distinguish each test document.

[0026] In step S404, an area for variable N is secured in RAM 104 and initialized to 0. Also, an area for a used flag for each test document to identify test documents that have already been used for generating correction data is secured and initialized to a value indicating an unused state.

[0027] In step S405, a display is displayed on the operation unit 114 to prompt the user to place the test document output in S403 at a desired document placement position on the document table 213 or the ADF document tray 201. Upon seeing this, the user places the printed test document at the desired document placement position.

[0028] In step S406, an instruction to start reading the test document is received via the operation unit 114.

[0029] In step S407, CPU 103 inquires of CPU 301 via IO control unit A109 about document detection information indicating whether a document has been detected on each of document tray 201 of the ADF and document platen 213. The document detection information does not have to be queried at this timing. For example, document detection information on document platen 213 may be acquired when a test document is set on document platen 213 after S405 and document pressing plate 214 of document platen 213 is closed. Also, the order of S406 and S407 may be reversed, so that if a document is not detected on either document platen 213 or document tray 201 of the ADF, the document reading start instruction is not accepted.

[0030] In step S408, the subsequent operation mode is determined based on the document detection information acquired in step S407. Details of the determination will be described with reference to FIG. 5. If a document placed on document tray 201 of the ADF is detected, correction data is generated in the first correction mode. In this first correction mode, test documents are read in the first reading mode (ADF reading mode). That is, multiple test documents placed on the document tray of the ADF are read in accordance with a single reading command. Then, multiple correction data corresponding to each test document are generated using density information obtained by reading each test document. That is, correction data generation starts after all test documents have been read. On the other hand, if a document placed on platen 213 is detected, correction data is generated in the second correction mode. In this second correction mode, test documents are read in the second reading mode (pressure plate reading mode). Correction data corresponding to this test document is generated using density information obtained by reading one test document placed on the platen. This series of processes is executed each time a test document is read, that is, the processes of reading the test document and generating correction data are executed multiple times.

[0031] If an error is determined, the process proceeds to S409. If it is determined that the ADF reading mode (first reading mode) is to be performed, the process proceeds to S410. If it is determined that the pressure plate reading mode (second reading mode) is to be performed, the process proceeds to S415.

[0032] In step S409, a screen is displayed on the operation unit 114 to prompt the user to properly reposition the test document.

[0033] In step S410, the test documents placed on document tray 201 of the ADF are conveyed in order, the test documents are read by the scanner controller, and the images obtained by reading the test documents are transferred to control unit 115. Then, CPU 103 analyzes whether the transferred images are suitable for generating correction data. For example, if a luminance pattern cannot be detected from the images obtained by reading the test documents, if an appropriate test document is not used, or if the test document was printed in an inappropriate state, the images are deemed unsuitable for use in generating correction data.

[0034] In step S411, if it is determined in S410 that all three images obtained by scanning the three test documents can be used to generate correction data, the process proceeds to S412. If it is determined that one or more of the three images obtained by scanning the three test documents cannot be used to generate correction data, the process proceeds to S413.

[0035] In step S412, each image obtained by reading the three test documents in step S410 is analyzed, and a correction table to be used for density correction of the image to be printed is generated. Details are omitted as this is a known technique, but based on the difference between the value obtained by converting the luminance value of the read image into a density value and the target value stored in RAM 104, a density correction table to be used in image processing performed on the print image and stored in RAM 104 is generated (updated).

[0036] In step S413, a screen is displayed on the operation unit 114 to prompt the user to properly reposition the test document.

[0037] In step S414, a screen indicating that the generation of correction data has been completed is displayed on the operation unit 114, and the process of generating correction data used for density adjustment is terminated.

[0038] In step S415, one test document placed on document table 213 is read by the scanner controller, and the image obtained by reading the test document is transferred to control unit 115. Then, CPU 103 analyzes the transferred image. The image analysis is the same as in S410.

[0039] However, the patch for determining the test document described in S403 is analyzed, compared with a used flag prepared for each test document in RAM 104, and if it is determined that a test document that has already been used to generate correction data has been reread, it is determined that the test document cannot be used to generate correction data. Alternatively, as another configuration, the patch for determining the test document described in S403 may be analyzed, and if it is not an appropriate test document, it may be determined that an error has occurred. For example, when N=0, the test document is used to generate correction data for dither pattern 1. When N=1, the test document is used to generate correction data for dither pattern 2. When N=2, the test document is used to generate correction data for dither pattern 3.

[0040] In step S416, if it is determined in S415 that the read image can be used to generate correction data, the process proceeds to S417, whereas if it is determined that the read image cannot be used for correction, the process proceeds to S422.

[0041] In step S417, the image obtained in S415 is analyzed, and a correction table to be used for density correction of the image to be printed is generated. Details are omitted as this is a known technique, but a density correction table to be used in image processing performed on the print image and stored in RAM 104 is generated (updated) based on the value obtained by converting the luminance value of the scanned image into a density value and the target value stored in RAM 104. Furthermore, of the used flags prepared for each test document in RAM 104, the flag for the test document used to generate the correction data is set to a used state.

[0042] In step S418, 1 is added to the variable N stored in the RAM 104.

[0043] In step S419, if the variable N is 3 or greater, it is determined that the generation of correction data using each of the three test documents has been completed, and the process proceeds to S414, otherwise the process proceeds to S420.

[0044] In step S420, a screen instructing the user to place the Nth document on document table 213 is displayed on operation unit 114.

[0045] In step S421, an instruction to start reading a test document is received via the operation unit 114.

[0046] In step S422, a screen is displayed on the operation unit 114 to prompt the user to properly reposition the test document.

[0047] In step S423, if the variable N is 1, the process proceeds to S405, whereby the test document may be repositioned from the platen to the ADF. If the variable N is 2 or greater, the process proceeds to S420 to continue generating correction data by reading from the platen. The determination in S423 may also be omitted. In that case, the process proceeds from S422 to S420.

[0048] In addition, in steps S405 and S420, the correction data generation process used for density adjustment, which is executed in this flow, may be made cancelable by issuing an instruction to the operation unit 114.

[0049] Next, the method for determining the operation mode in S408 will be described with reference to FIG.

[0050] 5 is a table showing the process of determining the operation of S408 based on information indicating whether a document has been placed on the document platen 213 and the document tray 201 of the ADF. If it is detected that a document has been placed on the document platen 213 but not in the document tray 201 of the ADF, the process proceeds from S408 to S410. That is, the test document is read in the pressure platen reading mode, and correction data is generated in the second correction mode. On the other hand, if it is detected that a document has not been placed on the document platen 213 but has been placed in the document tray 201 of the ADF, the process proceeds from S408 to S411. That is, the test document is read in the ADF reading mode, and correction data is generated in the first correction mode.

[0051] If it is detected that documents are placed on both the document table 213 and the document tray 201 of the ADF, or if it is detected that documents are not placed on either, it is determined to be an error and the process proceeds from S408 to S409.

[0052] In another configuration, when it is detected that documents are placed on both the document platen 213 and the document tray 201 of the ADF, a screen is displayed on the operation unit 114 that allows the user to select whether to read the test document on the document platen or the ADF (first reading mode or second reading mode). The test document may then be read in the mode selected by the user. In yet another embodiment, when test documents are placed on both the document platen 213 and the document tray 201 of the ADF, reading may be performed from one of the two that is predetermined. For example, a configuration may be adopted in which reading from the ADF is given priority, as with the copy function, or reading is performed from the other that is set in advance on the operation unit 114.

[0053] Next, an example of a screen displayed on the operation unit 114 will be shown with reference to FIG.

[0054] FIG. 6(a) is an example of the screen displayed in S405 and S406. The user is prompted to place three test documents in the document tray of the ADF, or to place the first test document on the document table. Although not shown in the figure, the screen may also display instructions on how to place the test documents (orientation and front and back) and the number of sheets. S406 is executed by pressing the Start Reading button.

[0055] FIG. 6(b) is an example of the screen displayed in S420 and S421. Next, an instruction is given to place the test document to be scanned on the document tray. In this example, N=2 is used, but the wording changes depending on the value of N and the number of test documents to be scanned. S421 is executed by pressing the Start Scan button. Note that if the Cancel button is pressed on this screen, the process of generating correction data used for density adjustment is terminated.

[0056] Figure 6(c) is an example of the screen displayed in S409. It prompts the user to check how the test document is placed in order to resolve the error caused by the detection state of the test document shown in Figure 5. Pressing the back button will proceed to S405.

[0057] 6(d) is an example of the screen displayed in S413 and S422. Because the scanned image is inappropriate for generating correction data, confirmation items are displayed to prompt the user to check whether the scanned document is a test document and whether there are any problems with the printing state of the test document. Pressing the back button proceeds to S405 or S423.

[0058] As described above, it is possible to determine the method for reading the test document and the flow for generating density correction data based on the document detection results obtained from the document table 213 and the ADF document tray 201. This makes it possible to perform calibration in an appropriate flow using a test document placed at a user's desired position.

[0059] Furthermore, when the user places a test document in the desired placement position on the document table 213 or the document tray 201 of the ADF, the appropriate flow for generating correction data is automatically determined, eliminating the need for the user to input settings in advance. [Example]

[0060] In the first embodiment, an example has been shown in which the processing flow for generating density correction data is determined depending on the location where placement of the test document is detected, that is, depending on the reading mode for reading the test document.

[0061] In this embodiment, a configuration will be described in which the reading mode can be changed during the generation of correction data. This allows test documents to be read more freely and flexibly, and it is possible to provide an image forming apparatus with a calibration function that can be used in a way that suits the user's needs.

[0062] The contents explained in FIGS. 1, 2, and 3 in the first embodiment are the same in the second embodiment, and therefore will be omitted.

[0063] The flow of generating correction data used for density adjustment in this embodiment will be described using Figure 7. In this example, three test documents are printed and scanned for correction. However, the number of test documents is not limited to three, and any number of documents necessary to generate the desired correction data may be used. Explanations of points overlapping with Figure 4 will be omitted.

[0064] In step S701, a display is displayed on the operation unit 114 prompting the user to place the test document output in S403 on the desired reading unit. Details are shown in FIG. 8, and the correction data generation flag is referenced. Then, if correction data has not been successfully generated using the read results for any of the test documents, if the first correction mode using the ADF reading mode is being executed, the user is prompted to place three test documents on the ADF document tray 201. On the other hand, if the second correction mode using the pressure plate reading mode is being executed, the user is prompted to place the first test document on the document table 213.

[0065] Furthermore, if the process returns to S701 after successfully generating correction data for even one image in any mode, the instructions are switched as follows:

[0066] If the first correction data mode using the ADF reading mode is being executed, an instruction is given to place test documents (multiple or one document) not used for generating correction data on the document tray 201 of the ADF.

[0067] On the other hand, if the second correction data mode using the pressure plate reading mode is being executed, an instruction is given to place another test document on the document table 213 that has not yet been read for generating correction data.

[0068] In step S702, the test documents placed on the document tray 201 of the ADF are transported in order, the transported test documents are read by the scanner controller, and the image obtained by reading the test documents is transferred to the control unit 115. The CPU 103 then analyzes whether the transferred image is suitable for generating correction data. For example, if a luminance pattern cannot be detected from the image obtained by reading the test documents, if an appropriate test document is not used, or if the test document was printed in an inappropriate state, the image is deemed unsuitable for use in generating correction data. Furthermore, the document detection flag is referenced to determine that a test document that has already been used to generate correction data is unsuitable as an image for generating correction data.

[0069] In step S703, if it is determined that one or more of the test documents read in S702 can be used to generate correction data, the process proceeds to S704. Otherwise, the process proceeds to S413. As another example, the process may proceed to S703 if it is determined that all of the test documents read in S702 can be used to generate correction data, and proceed to S413 if not.

[0070] In step S704, each image of the test document read in step S702 that is determined to be usable for generating correction data is analyzed, and correction data generation processing is executed. The details of the correction data generation processing are the same as in step S412, and therefore will not be described here.

[0071] In step S705, the number of test documents on which correction has been performed is added to the variable N stored in the RAM 104.

[0072] Next, an example of a screen displayed on the operation unit 114 will be shown using Fig. 8. The screen displayed when an error occurs is the same as that explained in Fig. 6, so it will be omitted.

[0073] FIG. 8(a) is an example of the screen displayed in S406 and S407 when correction data generation has not yet been successful. A screen is displayed prompting the user to place three test documents in the document tray of the ADF or to place the first test document on the document table. Although not shown in the figure, a screen may also be displayed instructing the method of placing the test documents and the number of test documents. S407 is executed by pressing the start reading button.

[0074] FIG. 8(b) shows an example of a screen displayed in S406 and S407 when the first page of a test document is first read on the document platen and the generation of correction data is successful. The correction data generation flag is referenced, and since the first page of the test document for which the corresponding correction data has been generated is no longer necessary, the user is prompted to place the second and third test documents in the document tray of the ADF. This differs from (a). Alternatively, the user may be prompted to always place three test documents in the document tray 201 of the ADF. In this case, as explained in S702, the test document for which correction data has been generated is not subject to correction, so this does not pose a problem.

[0075] 8(c) shows an example of the screen displayed in S406 and S407 when the second and third test documents are first read by the ADF and correction data generation is successful. The correction data generation flag is referenced, and the user is prompted to place the first test document, for which correction data has not yet been generated, in the ADF document tray 201 or document table 213.

[0076] In the second embodiment, as in the first embodiment, the screen prompts the user to place three test documents in the document tray 201 of the ADF. However, for example, if the user intended to place all three test documents in the document tray 201 of the ADF but actually placed only two, in this embodiment, two of the test documents are read in the ADF reading mode and correction data is generated in the first correction mode. Then, the remaining test document can be read separately in the pressure plate reading mode and correction data can be generated in the second correction mode. (It is also possible to read it again in the ADF reading mode and generate correction data in the first correction mode.)

[0077] Furthermore, a user who needs highly accurate correction data only for a specific dither pattern and wants to efficiently generate correction data for the remaining dither patterns can generate correction data by using two correction modes. Specifically, to obtain correction data corresponding to a specific dither pattern, a corresponding test document is placed on the document table 213 and read in pressure platen reading mode. This enables highly accurate reading, and therefore highly accurate correction data can be generated.

[0078] For correction data corresponding to the remaining dither patterns, the corresponding test document is placed on document tray 201 of the ADF and read in ADF reading mode. This allows for efficient reading, thereby reducing the burden on the user required to generate correction data.

[0079] (Other Examples) The present invention can also be realized by executing the following process: software (programs) that realize the functions of the above-described embodiments are supplied to a system or device via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or device reads and executes the programs.

Claims

1. an image forming means for forming an image on a sheet; a reading means having a document table on which a document is placed, a reading unit that reads the document placed on the document table, a loading unit on which the document is stacked, a transport unit that transports the document loaded on the loading unit so that the document loaded on the loading unit can be read by the reading unit, and a paper discharge tray onto which the document transported by the transport unit is discharged; a receiving unit that receives user instruction information that instructs the reading unit to read a chart used for calibration of the image forming unit, When the reading means receives the user instruction information while a document on which the chart is formed is loaded in the loading section, the reading means transports the document on which the chart is formed, which is loaded in the loading section, to the transport section, regardless of whether a document is placed on the document table, and reads the document on which the chart is formed.

2. 2. The image forming apparatus according to claim 1, wherein the reading unit further reads the document on which the chart is formed that is placed on the document table when the user instruction information is received in a state where no document on which the chart is formed is loaded on the loading section and a document on which the chart is formed is placed on the document table.

3. 3. The image forming apparatus according to claim 2, wherein the reading means detects a state in which the document on which the chart is formed is placed on the document table by using the reading unit.

4. 3. The image forming apparatus according to claim 2, wherein the reading means detects, by using the reading unit, whether or not a document on which the chart is formed is placed on the document table in response to receiving the user instruction information.

5. 2. The image forming apparatus according to claim 1, further comprising a detection unit used to detect the document on which the chart is formed and which is loaded on the loading unit.

6. a detection unit used to detect the document on which the chart is formed and which is loaded on the loading unit; 2. The image forming apparatus according to claim 1, further comprising: a determination unit that, in response to receiving the user instruction information, determines using the detection unit whether a document on which the chart is formed is loaded on the loading unit.

7. 2. The image forming apparatus according to claim 1, wherein the calibration is image density adjustment for adjusting the density of the image formed by the image forming means.

8. 2. The image forming apparatus according to claim 1, wherein the calibration is a position adjustment of the image formed by the image forming means.

9. 2. The image forming apparatus according to claim 1, wherein the calibration is an adjustment of uneven density of the image formed by the image forming means.

10. 2. An image forming apparatus according to claim 1, wherein said image forming means forms said chart.

11. an image forming means for forming an image on a sheet; a reading means having a document table on which a document is placed, a reading unit that reads the document placed on the document table, a loading unit on which the document is stacked, a transport unit that transports the document loaded on the loading unit so that the document loaded on the loading unit can be read by the reading unit, and a paper discharge tray onto which the document transported by the transport unit is discharged; A control method for an image forming apparatus having a receiving step of receiving user instruction information instructing the reading unit to read a chart used for calibration of the image forming unit; a reading step in which, when the user instruction information is received in a state in which the document on which the chart is formed is loaded in the loading section, the document on which the chart is formed and which is loaded in the loading section is transported to the transport section regardless of whether the document is placed on the document table or not, and the document on which the chart is formed is read; 1. A method for controlling an image forming apparatus, comprising:

12. an image forming means for forming an image on a sheet; a reading means having a document table on which a document is placed, a reading unit that reads the document placed on the document table, a loading unit on which the document is stacked, a transport unit that transports the document loaded on the loading unit so that the document loaded on the loading unit can be read by the reading unit, and a paper discharge tray onto which the document transported by the transport unit is discharged; A program for causing a computer to execute each step of a control method for an image forming apparatus, the control method comprising: a receiving step of receiving user instruction information instructing the reading unit to read a chart used for calibration of the image forming unit; a reading step of, when the user instruction information is received in a state in which the document on which the chart is formed is loaded in the loading section, transporting the document on which the chart is formed and which is loaded in the loading section to the transport section regardless of whether the document is placed on the document table or not, and reading the document on which the chart is formed; A program comprising:

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