Image reading device, image forming apparatus, and image reading method

Abstract

To provide an image reading device, an image forming apparatus, and an image reading method that can more easily generate clean white reference data.SOLUTION: An image reading device of an embodiment comprises: an image reading unit that reads an image; a density reference member that is provided opposite to the image reading unit; a moving mechanism that moves the density reference member; a lock mechanism that switches the density reference member to a fixed state or a movable state; a generation unit that generates reference data of shading correction from an image read from the density reference member in the fixed state moved by the moving mechanism to a reading portion different from a reading portion used in reading of the document; and a shading correction unit that executes shading correction of the image by using the reference data.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image reading apparatus, an image forming apparatus, and an image reading method. [Background technology]

[0002] Conventionally, images read by a scanner have periodic unevenness caused by the lens that focuses light on the sensor. Therefore, shading correction of images read by a scanner is performed using data read from a white member located opposite the sensor as white reference data.

[0003] Patent Document 1 discloses a technique for storing shading data generated in advance from a white reference board in order to perform accurate shading correction using a white reference board placed at a position different from the reading position of the document. In Patent Document 1, this shading data is used to determine whether or not to adjust the shading data of the white reference board that was read immediately before, an adjustment value is calculated according to the determination result, and shading correction is performed according to the adjustment value. Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the components used to generate the reference data are located on the paper transport path, they are in an environment where dust such as paper powder is likely to adhere to them, and if dust-like noise is included in the reference data, vertical streaks will appear in the corrected image data.When the board mounting the memory that stores the reference data or the reading module itself is replaced, it is necessary to regenerate the reference data in an environment outside the manufacturing process, but there is a problem in that it is difficult to remove the effects of dust.

[0005] The present invention has been made in view of the above, and has an object to make it possible to more easily generate clean reference data. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention is characterized by comprising an image reading unit that reads an image, a density reference member provided opposite the image reading unit, a movable mechanism that moves the density reference member, a locking mechanism that switches the density reference member between a fixed state and a movable state, a generation unit that generates reference data for shading correction from an image read from the fixed-state density reference member that has been moved by the movable mechanism to a reading position different from the reading position used when reading a document, and a shading correction unit that uses the reference data to perform shading correction of the image. Effect of the Invention

[0007] Advantageous Effects of Invention According to the present invention, an effect is achieved in that clean reference data can be more easily generated. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an example of a hardware configuration of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a functional configuration related to read signal processing according to the first embodiment. [Diagram 3] FIG. 3 is a conceptual diagram illustrating an example of a concentration reference member and a locking mechanism according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a component configuration related to image reading processing according to the first embodiment. [Figure 5A] FIG. 5A is a conceptual diagram for explaining an example of a mechanism (fixed state) for moving the density reference member in the sub-scanning direction according to the first embodiment. [Figure 5B] FIG. 5B is a conceptual diagram for explaining an example of a mechanism (movable state) for moving the density reference member in the sub-scanning direction according to the first embodiment. [Figure 6] FIG. 6 is a conceptual diagram for explaining an example of a mechanism for moving the density reference member in the main scanning direction according to the first embodiment. [Figure 7]FIG. 7 is a flowchart illustrating an example of an image reading method according to the first embodiment. [Figure 8] FIG. 8 illustrates an example of a functional configuration related to read signal processing according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image reading apparatus, an image forming apparatus, and an image reading method will be described in detail with reference to the accompanying drawings.

[0010] (First embodiment) In the first embodiment, an example will be described in which the image forming apparatus of the present invention is applied to a multifunction peripheral having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function. However, the image forming apparatus of the present invention can be applied to any apparatus consisting of an image reading device having a scanner function, such as a copier, printer, scanner device, or facsimile device.

[0011] [Example of hardware configuration] Fig. 1 is a diagram showing an example of a hardware configuration of an image forming apparatus 1 according to a first embodiment. The hardware configuration of the image forming apparatus 1 according to this embodiment will be described with reference to Fig. 1. Note that in Fig. 1, the image forming apparatus 1 will be described as an MFP (Multifunction Peripheral).

[0012] As shown in FIG. 1, the image forming apparatus 1 includes a controller 910, a short-range communication circuit 920, an engine control unit 930, an operation panel 940, and a network I / F 950.

[0013] The controller 910 includes a CPU (Central Processing Unit) 901, which is the main part of the computer, a MEM-P (system memory) 902, an NB (north bridge) 903, an SB (south bridge) 904, an ASIC (Application Specific Integrated Circuit) 906, a MEM-C (local memory) 907, an HDD (Hard Disk Drive) controller 908, and an HD 909. Of these, the NB 903 and the ASIC 906 are connected by an AGP (Accelerated Graphics Port) bus 921.

[0014] The CPU 901 is a calculation device that performs overall control of the image forming apparatus 1. The NB 903 is a bridge for connecting the CPU 901 with the MEM-P 902, the SB 904, and the AGP bus 921, and includes a memory controller that controls reading and writing to the MEM-P 902, a PCI (Peripheral Component Interconnect) master, and an AGP target.

[0015] The MEM-P902 includes a ROM902a which is a memory for storing programs and data for implementing the various functions of the controller 910, and a RAM902b which is used for developing the programs and data and as a drawing memory during memory printing, etc. The programs stored in the RAM902b may be configured to be provided by being recorded in an installable or executable format on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a CD-R (Compact Disc Recordable), or a DVD.

[0016] The SB904 is a bridge for connecting the NB903 with a PCI device, a peripheral device, and the like. The ASIC906 is an IC (Integrated Circuit) for image processing purposes having hardware elements for image processing, and serves as a bridge for connecting the AGP bus 921, the PCI bus 922, the HDD controller 908, and the MEM-C907. The ASIC906 includes a PCI target and an AGP master, an arbiter (ARB) that is the core of the ASIC906, a memory controller that controls the MEM-C907, a plurality of DMACs (Direct Memory Access Controllers) that rotate image data using hardware logic, and a PCI unit that transfers data between the image reading unit 10 and the image forming unit 931 via the PCI bus 922. A Universal Serial Bus (USB) interface or an Institute of Electrical and Electronics Engineers 1394 (IEEE1394) interface may be connected to the ASIC906.

[0017] The MEM-C 907 is a local memory used as a copy image buffer and a code buffer. The HDD controller 908 is a controller that controls reading and writing of data from and to the HD 909 under the control of the CPU 901. The HD 909 is a storage for storing image data, font data used during printing, and forms. The HDD controller 908 and the HD 909 may be SSDs (Solid State Drives).

[0018] The AGP bus 921 is a bus interface for a graphics accelerator card proposed to speed up graphics processing, and by directly accessing the MEM-P 902 at high throughput, the graphics accelerator card can be made faster.

[0019] The short-range communication circuit 920 is a communication circuit such as NFC (Near Field Communication) or Bluetooth (registered trademark). The short-range communication circuit 920 is electrically connected to the ASIC 906 via a PCI bus 922. An antenna 920a for wireless communication is connected to the short-range communication circuit 920.

[0020] The engine control unit 930 includes the image reading unit 10 and an image forming unit 931. The image reading unit 10 and the image forming unit 931 include an image processing function such as error diffusion or gamma conversion.

[0021] The operation panel 940 is equipped with a panel display unit 940a (display device) such as a touch panel that displays current setting values ​​or a selection screen, etc. and accepts input from the user, and hard keys 940b consisting of a numeric keypad that accepts setting values ​​for image formation conditions such as density setting conditions, and a start key that accepts a copy start instruction.

[0022] The image forming apparatus 1 can successively switch among the document box function, copy function, printer function, and fax function using the application switching key on the operation panel 940. When the document box function is selected, the document box mode is selected, when the copy function is selected, the copy mode is selected, when the printer function is selected, the printer mode is selected, and when the fax function is selected, the fax mode is selected.

[0023] The network I / F 950 is an interface for data communication via a network, and is an interface capable of communication conforming to, for example, Ethernet (registered trademark), TCP (Transmission Control Protocol) / IP (Internet Protocol), etc. The network I / F 950 is electrically connected to the ASIC 906 via the PCI bus 922.

[0024] It should be noted that the hardware configuration of the image forming apparatus 1 shown in FIG. 1 is merely an example, and it is not necessary for the image forming apparatus 1 to include all of the components shown in FIG. 1, or it may include other components.

[0025] Next, a function for processing an image read signal read by the image reading unit 10 in FIG. 1 will be described in detail.

[0026] [Example of functional configuration related to image reading signal processing] 2 is a diagram showing an example of a functional configuration related to read signal processing according to the first embodiment. An image reading unit 10 according to the first embodiment includes a light source 11, a sensor 12, and an A / D conversion unit 13.

[0027] A light source 11 irradiates a document with light, and a sensor 12 receives the collected light reflected from the document to read the image. Specifically, the sensor 12 may be configured as a CIS (Contact Image Sensor) using a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, or may be configured using a CCD (Charge-Coupled Device) sensor.

[0028] The A / D conversion unit 13 converts the electrical signal input from the sensor 12 into a digital signal. That is, the A / D conversion unit 13 converts the analog data acquired by the sensor 12 into digital data and sends the digital data to the signal processing unit 20.

[0029] The data sent to the signal processing unit 20 includes white shading data obtained by reading a density reference member provided opposite the image reading unit 10, and image data obtained by reading a document. The white shading data is data used for shading correction processing. The image data is data used for image formation processing of the document.

[0030] The signal processing unit 20 includes a generating unit 21, an auxiliary storage unit 22, a selector 23, a main storage unit 24, and a shading correction unit 25. The selector 23 selects either the data from the generating unit 21 or the auxiliary storage unit 22, and inputs it to the main storage unit 24.

[0031] Each function of the signal processing unit 20 is realized by an engine control unit 930 or a controller 910 of the image forming apparatus functioning as the image reading apparatus in FIG.

[0032] First, a process flow will be described, in which the white shading data read from the density reference member is stored as clean white reference data (an example of reference data) in the auxiliary storage unit 22. Note that a color other than white may be used as the density reference member, and a color other than white may be used as the reference data.

[0033] First, the generating unit 21 receives white shading data from the image reading unit 10. The generating unit 21 extracts the white shading data by a sub-scanning gate signal, and generates white data for one line.

[0034] When this white data is to be used as white reference data in the future, it passes through the selector 23 as is and is stored in the main memory unit 24. Thereafter, this white reference data is saved in the non-volatile auxiliary memory unit 22.

[0035] The main memory unit 24 is volatile, so the white reference data disappears when power is cut off, but the auxiliary memory unit 2 is nonvolatile, so the white reference data is retained even when power is turned off. The white reference data in the auxiliary memory unit 22 is stored in the main memory unit 24 from the auxiliary memory unit 22 through the selector 23 immediately when power is supplied so that it can be used for shading correction immediately the next time it is used.

[0036] When an image is read, image data is input to the shading correction unit 25, and the white reference data stored in the main memory unit 24 is also input to the shading correction unit 25. The shading correction unit 25 performs shading correction using the image data and the white reference data.

[0037] The scanned image data is affected by the inherent characteristics of the sensor, the surrounding environment, etc., so even if an image with uniform density is scanned, the image data will not be uniform when viewed in the main scanning direction. Therefore, this shading correction is used to output an image with uniform density as uniform data.

[0038] By using the functional configuration shown in Figure 2, the white reference data read from the density reference member can be stored in the auxiliary memory unit 22 (non-volatile memory), and shading correction can be performed on the image data read from the original document using the previously stored white reference data.

[0039] 3 is a conceptual diagram showing an example of the density reference member 30 and the lock mechanism 40 according to the first embodiment. In the example of FIG. 3, the density reference member 30 is a density reference plate located opposite the image reading unit 10.

[0040] The image reading unit 10 includes the above-mentioned light source 11 and sensor 12 , and reads the light reflected from the density reference member 30 .

[0041] The lock mechanism 40 is a mechanism that allows the concentration reference member 30 to be arbitrarily selected between a movable state in which the concentration reference member 30 is movable and a fixed state in which the concentration reference member 30 is fixed.

[0042] When the document is read, the density reference member 30 is used in a fixed state. The density reference member 30 serves as a guide for document transport and as a background when the document is read.

[0043] When white reference data is acquired during a shipping process at a factory or when it becomes necessary to acquire the white reference data again due to parts replacement in the market, the locking mechanism 40 is released and the density reference member 30 is made movable.

[0044] Thereafter, the movable density reference member 30 is moved to a position that is not used when reading a normal document, and is read as white shading data by the image reading unit 10. Then, the white reference data generated from the white shading data by the generating unit 21 is stored in the auxiliary storage unit 22.

[0045] At this time, the white reference data may be generated from data of only one line, or may be generated from data of multiple lines including data before and after the movement of the density reference member 30.

[0046] 3, by moving the density reference member 30 to a reading position different from the reading position during normal use, it is possible to remove the influence of dust and scratches on the surface of the density reference member 30 and generate clean white reference data. That is, the generation unit 21 generates reference data for shading correction from an image read from the density reference member 30 that has been moved to a reading position different from the reading position used when reading a document.

[0047] The different reading locations are different positions that are shifted at least further than the width of one line of the irradiation diameter of one light emitter of the light source 11 having multiple light emitters that are irradiated onto the density reference member 30, and are preferably different positions that are shifted further than the irradiation range including the range equivalent to the irradiation diameter in front and behind the light emitters. The density reference member 30 of the reading location used when reading the document is released from the fixed state and becomes movable, and the density reference member 30 moves arbitrarily. It can be fixed by the lock mechanism 40 at multiple fixed positions that are different from the reading location used when reading the document. The density reference member 30 can generate reference data in this fixed state.

[0048] The density reference member 30 moves in a sub-scanning direction 101 and a main scanning direction 102. A moving mechanism for moving the density reference member 30 in the sub-scanning direction 101 will be described later with reference to Figures 5A and 5B. A moving mechanism for moving the density reference member 30 in the main scanning direction 102 will be described later with reference to Figure 6.

[0049] Fig. 4 is a diagram showing an example of a component configuration related to the image reading process of the first embodiment. As shown in Fig. 4, the image reading unit 10 (first component), the density reference member 30 (second component), and the electric circuit board 50 (third component) are each composed of independent components. The electric circuit board 50 is connected to the image reading unit 10 via a data transmission path.

[0050] When any of the image reading unit 10, the density reference member 30, and the electric circuit board 50 is damaged or malfunctions, the damaged or malfunctioning part can be replaced in the market.

[0051] The white reference data stored in the auxiliary memory unit 22 has a different distribution depending on the combination of the light source 11 and the sensor 12 of the image reading unit 10 and the density reference member 30. Therefore, when either the image reading unit 10 or the density reference member 30 is replaced, consistency with the white reference data in the auxiliary memory unit 22 cannot be achieved.

[0052] Therefore, the image reading unit 10, the density reference member 30, and the electric circuit board 50 must be replaced as a set, which increases the cost of replacing parts in the market. Even if the electric circuit board 50 is replaced, the white reference data stored in the auxiliary storage unit 22 is lost, so it becomes necessary to incur costs such as making the memory that realizes the auxiliary storage unit 22 removable.

[0053] However, if the device has a lock mechanism 40 that allows the movable state and the fixed state shown in Fig. 3 to be selected arbitrarily, clean white reference data can be generated in the market even if any of the parts are replaced in the market. This makes it possible to reduce the cost of replacing parts in the market.

[0054] That is, when at least one of the above-mentioned first to third parts is replaced, the generating unit 21 can regenerate the reference data for shading correction from the image read from the density reference member 30 that has been moved to a reading position different from the reading position used when reading the document. Then, the auxiliary storage unit 22 can store the reference data regenerated by the generating unit 21.

[0055] The auxiliary memory unit 22 and the main memory unit 24 may be located inside or outside the image processing IC 51. In the example of Fig. 4, the main memory unit 24 is located inside the image processing IC 51, and the auxiliary memory unit 22 is located outside the image processing IC 51.

[0056] Furthermore, if necessary, the unit of replacement in the market may be a set of the image reading unit 10, the density reference member 30, and the electrical circuit board 50, rather than each of the image reading unit 10, the density reference member 30, and the electrical circuit board 50 being replaced individually.

[0057] Fig. 5A is a conceptual diagram for explaining an example of a movable mechanism (fixed state) that moves the density reference member 30 in the sub-scanning direction 101 according to the first embodiment. Fig. 5A is a diagram of the image reading unit 10 and the density reference member 30 as viewed from the short side direction.

[0058] The density reference member 30 is located opposite the image reading unit 10, and has a shaft 60 and a bearing 61 disposed in a position accessible to the user. The density reference member 30 is designed to operate in conjunction with the rotation of the shaft 60 and the bearing 61 that is integral with the shaft 60. In the example of Fig. 5A, the density reference member 30 is configured to rotate and move, but it may be configured to slide laterally, and the mechanism for moving it in the sub-scanning direction 101 is not limited to the example of Fig. 5A.

[0059] During normal use when an original is read, the shaft 60 is fixed, and the density reference member 30 does not move. When an original is read, the original is read at a reading point 202 of reflected light 201 on the reading surface.

[0060] The locking mechanism for fixing the concentration reference member 30 in Fig. 5A has a handle 62, which is an operating member, attached to a bearing 61. The handle 62 moves and hooks onto the exterior surrounding the concentration reference member 30 to fix the concentration reference member 30. Alternatively, the concentration reference member 30 may be fixed from rotation by moving the handle 62 and utilizing the tension of a spring. The mechanism for fixing the concentration reference member 30 is not limited to the example in Fig. 5A.

[0061] FIG. 5B is a conceptual diagram for explaining an example of a mechanism (movable state) for moving the density reference member 30 in the sub-scanning direction 101 according to the first embodiment.

[0062] By releasing the fixed state, the density reference member 30 becomes capable of moving in the sub-scanning direction 101 relative to the reading direction. Since it becomes possible to use a reading location different from the reading location 202 of the reflected light 201, this is effective in removing the effects of dirt and scratches when generating the white reference data, and is particularly effective in removing dirt and scratches that extend in the main scanning direction 102.

[0063] The rotation of the shaft 60 and the release of the fixed state are performed by the user. When the shaft 60 is operated by the user, the user holds the handle 62 with his / her fingers and rotates it in the direction of removal from the exterior.

[0064] In addition, an electric drive circuit may be used as the power source. In the case of using an electric drive circuit, a gear is added to the bearing 61 to transmit the motor power, thereby enabling operation.

[0065] If the device is configured to operate through user operation, the number of drive mechanisms such as gears for transmitting motor power and shafts for supporting the gears, as well as other electrical drive circuits, can be reduced, thereby reducing costs.

[0066] Fig. 6 is a conceptual diagram for explaining an example of a mechanism for moving the density reference member 30 in the first embodiment in the main scanning direction 102. Fig. 6 is a diagram showing the image reading unit 10 and the density reference member 30 as viewed from the longitudinal direction.

[0067] The density reference member 30 is located opposite the image reading unit 10, and has a shaft 60 and a bearing 61 disposed in a position accessible to the user. The density reference member 30 is designed to operate in conjunction with the rotation of the shaft 60 and the bearing 61. In the example of Fig. 6, a cylindrical groove cam 63 is shown as being connected to the density reference member 30, but a different mechanism may be used to slide the density reference member 30, and the mechanism for moving the density reference member 30 in the main scanning direction 102 is not limited to the example of Fig. 6.

[0068] During normal use when a document is being read, the shaft 60 is fixed by a locking mechanism, so the shaft 60 does not rotate and the concentration reference member 30 does not move. The locking mechanism for fixing the shaft 60 may be configured such that a handle 62 is provided on a bearing 61 that rotates integrally with the shaft 60 and that the handle 62 is hooked onto the exterior, or the tension of a spring may be used to fix the rotation.

[0069] By releasing the fixed state, the shaft 60 rotates, the cylindrical groove cam 63 becomes able to rotate, and the density reference member 30 becomes able to move in the main scanning direction 102 relative to the reading direction. This makes it possible to use a reading location on the reading surface 201 that is different from the reading location used to read the document. This is therefore effective in removing the effects of dust and scratches when generating white reference data, and has particularly high removal performance for dust and scratches that extend in the sub-scanning direction 101.

[0070] Rotation of the shaft 60 and release of the fixed state may be performed using an electrical drive circuit or by user operation. When an electrical drive circuit is used, a gear can be added to the bearing 61 and the motor power can be transmitted to operate the device. When the device is operated by user operation, the user can rotate the device by pinching the handle 62 with their fingers. When the device is configured to operate by user operation, the number of gears for transmitting the motor power, shafts for supporting the gears, and other electrical drive circuits can be reduced, thereby reducing costs.

[0071] [Example of image reading method] 7 is a flowchart showing an example of the image reading method according to the first embodiment. First, the locking mechanism 40 switches the density reference member 30, which is provided opposite the image reading unit 10, from a fixed state to a movable state (step S1).

[0072] Next, the movable mechanism moves the density reference member 30 to a reading position different from the reading position used when reading the document (step S2). For example, in the example of Fig. 5A and 5B in which the density reference member 30 is moved in the sub-scanning direction 101, the movable mechanism is the shaft 60, the bearing 61, and the handle 62. Also, for example, in the example of Fig. 6 in which the density reference member 30 is moved in the main scanning direction 102, the movable mechanism is the shaft 60, the bearing 61, the handle 62, and the cylindrical groove cam 63.

[0073] 5B and 6 so as to be movable in both the sub-scanning direction 101 and the main scanning direction 102. Also, the movable mechanism may be provided with either the configuration shown in FIG. 5B or the configuration shown in FIG. 6 so as to be movable in either the sub-scanning direction 101 or the main scanning direction 102.

[0074] Next, the image reading unit 10 reads an image from the fixed density reference member 30 that has been moved to a different reading position by the process of step S2 (step S3).

[0075] Next, the generating unit 21 generates reference data for shading correction from the image read from the density reference member 30 (step S4).

[0076] The shading correction unit 25 performs shading correction on the image read from the document using the reference data generated in step S4 (step S5).

[0077] As described above, according to the first embodiment, clean reference data can be generated more easily. Specifically, in the first embodiment, a lock mechanism 40 is provided that allows the density reference member 30 (e.g., a white board) used as a density reference to be selected as either movable or fixed. This allows clean white reference data to be easily generated even when parts are replaced in the market, while maintaining the effect of reducing the influence of dust by moving the density reference member 30 and the effect of reducing costs by fixing the density reference member 30.

[0078] Conventionally, when it is necessary to regenerate reference data in an environment outside the manufacturing process, it has been very difficult to remove the effects of dust in an uncontrolled environment. According to the first embodiment, when parts are replaced in the field, reference data from which the effects of dust, scratches, etc. have been removed can be more easily recreated. This makes it possible to reduce replacement costs in the field.

[0079] (Second embodiment) Next, a second embodiment will be described. In the description of the second embodiment, the description of the same parts as in the first embodiment will be omitted, and only the parts different from the first embodiment will be described.

[0080] 8 is a diagram showing an example of a functional configuration related to read signal processing in the second embodiment. In the second embodiment, a reference data correction unit 26 is added to the signal processing unit 20. The reference data correction unit 26 uses the reference data stored in the auxiliary storage unit 22 to detect an abnormal portion of the reference data recorded in the main storage unit 24, and corrects the reference data recorded in the main storage unit 24.

[0081] The process flow for storing the clean white reference data in the non-volatile auxiliary storage unit 22 is the same as that in the first embodiment. The process flow in the second embodiment will be described below.

[0082] In the second embodiment, the image reading unit 10 sends white shading data obtained by reading the density reference member 30 to the generating unit 21 immediately before reading the image of the document. The generating unit 21 generates white data for, for example, one line from the white shading data. The white data generated by the generating unit 21 is stored as white reference data in the main memory unit 24 through the selector 23.

[0083] This white data is obtained by reading the density reference member 30 in a fixed state, and since there is a possibility that the data may be affected by dust, this white data is input to the reference data correction section 26 .

[0084] Furthermore, clean white reference data is input from the non-volatile auxiliary storage unit 22 to the reference data correction unit 26 .

[0085] The reference data correction unit 26 compares the two white reference data input from the main memory unit 24 and the auxiliary memory unit 22, and detects the position of dust adhering to the white data acquired immediately before reading the document. The reference data correction unit 26 also performs a process of correcting the white reference data input from the main memory unit 24 by partially replacing the detected portion with clean white reference data.

[0086] The shading correction section 25 uses the white reference data corrected by the reference data correction section 26 to perform shading correction on the image read from the document.

[0087] The light source of the image reading unit 10 may have a deteriorated light quantity due to use over time. In addition, the sensitivity of the sensor 12 may decrease and the main scanning distribution may vary due to heat generation during operation. Therefore, if the white reference data stored in the auxiliary storage unit 22 is old data with respect to the time of reading the document, it may be affected by the above-mentioned variation and appear as unevenness in the data after shading correction.

[0088] However, as in the second embodiment, if white data obtained immediately before scanning a document is used, it is possible to absorb the effects of fluctuations due to aging. However, since the white data obtained immediately before scanning a document may be affected by dust as described above, in the second embodiment, only that portion is replaced with clean white reference data.

[0089] In the first embodiment, the white reference data saved in the auxiliary storage unit 22 is stored in the main storage unit 24, and the white reference data is used as is for shading correction. In the second embodiment, by adding a reference data correction unit 26, it becomes possible to generate most of the white reference data from white shading data acquired immediately before acquiring the document.

[0090] As a result, according to the second embodiment, the influence of fluctuations over time in white shading data, such as short-term fluctuations in the light source 11 and temperature fluctuations, can be absorbed, and improvement in image quality after shading correction can be expected.

[0091] For example, aspects of the present invention are as follows. <1> an image reading unit that reads an image; a density reference member provided opposite the image reading unit; a movable mechanism for moving the concentration reference member; a lock mechanism for switching the concentration reference member between a fixed state and a movable state; a generating unit that generates reference data for shading correction from an image read from a fixed density reference member that is moved by the movable mechanism to a reading position different from a reading position used when reading a document; a shading correction unit that performs shading correction on the image using the reference data; The image reading device includes: <2> an auxiliary storage unit that stores the reference data; a selector that selects the reference data generated by the generation unit or the reference data stored in the auxiliary storage unit; a main memory unit that stores the reference data selected by the selector, the shading correction unit performs shading correction on the image using the reference data stored in the main storage unit. The above <1> The image reading apparatus according to the present invention is <3> a data correction unit that detects an abnormality in the reference data recorded in the main storage unit by using the reference data stored in the auxiliary storage unit and corrects the reference data recorded in the main storage unit; The above further comprises <2> The image reading apparatus according to the present invention is <4> The image reading unit is configured as a first component, The concentration reference member is configured as a second part, the main memory unit and the auxiliary memory unit are configured as a third component; When at least one of the first to third parts is replaced, the generating unit regenerates reference data for shading correction from an image read from a fixed density reference member that has been moved by the movable mechanism to a reading position different from a reading position used when reading an original; The auxiliary storage unit stores the reference data regenerated by the generation unit. The above <2> The image reading apparatus according to the present invention is <5> The movable mechanism has an operating member, the lock mechanism switches the concentration reference member between the fixed state and the movable state in response to movement of the operating member. The above <1> ~ <4> The image reading device according to any one of claims 1 to 5, <6> the movable mechanism is a mechanism for moving the density reference member in a main scanning direction; The above <1> ~ <5> The image reading device according to any one of claims 1 to 5 is provided. <7> the movable mechanism is a mechanism for moving the density reference member in a sub-scanning direction; The above <1> ~ <6> The image reading device according to any one of claims 1 to 5 is provided. <8> The above <1> ~ <7> 13. An image reading device according to claim 12, an image forming unit that forms an image read by the image reading device; The image forming apparatus includes: <9> a locking mechanism switching a density reference member provided opposite the image reading unit from a fixed state to a movable state; a step of moving the density reference member to a reading position different from a reading position used when reading an original by a movable mechanism; An image reading unit reads an image from the density reference member moved to the different reading position; A generating unit generates reference data for shading correction from an image read from the density reference member; a shading correction unit performing shading correction of an image read from an original by using the reference data; The image reading method includes the steps of: [Explanation of symbols]

[0092] 1. Image forming device 10 Image reading unit 11 Light source 12 Sensors 13 A / D conversion section 21 Generation part 22 Auxiliary storage 23 Selector 24 Main memory 25 Shading correction section 26 Reference data correction section 30 Concentration standard material 40 Locking mechanism 50 Electrical Circuit Board 51 Image processing IC 60 Axis 61 Bearings 62 Toride 63 Cylindrical groove cam 901 CPU 902 MEM-P 902a ROM 902b RAM 903 NB 904SB 906 ASIC 907 MEM-C 908 HDD Controller 909 HD 910 Controller 920 Near field communication circuit 920a Antenna 921 AGP Bus 922 PCI bus 930 Engine control unit 931 Image forming section 940 Operation Panel 940a Panel display 940b Hard Key 950 Network Interface [Prior art documents] [Patent documents]

[0093] [Patent Document 1] JP 2019-068380 A

Claims

1. an image reading unit that reads an image; a density reference member provided opposite the image reading unit; a movable mechanism for moving the concentration reference member; a lock mechanism for switching the concentration reference member between a fixed state and a movable state; a generating unit that generates reference data for shading correction from an image read from a fixed density reference member that is moved by the movable mechanism to a reading position different from a reading position used when reading a document; a shading correction unit that performs shading correction on the image using the reference data; An image reading device comprising:

2. an auxiliary storage unit that stores the reference data; a selector that selects the reference data generated by the generation unit or the reference data stored in the auxiliary storage unit; a main memory unit that stores the reference data selected by the selector, the shading correction unit performs shading correction on the image using the reference data stored in the main storage unit.

2. The image reading device according to claim 1.

3. a data correction unit that detects an abnormality in the reference data recorded in the main storage unit by using the reference data stored in the auxiliary storage unit and corrects the reference data recorded in the main storage unit; The image reading device according to claim 2 , further comprising:

4. The image reading unit is configured as a first component, The concentration reference member is configured as a second part, the main memory unit and the auxiliary memory unit are configured as a third component; When at least one of the first to third parts is replaced, the generating unit regenerates reference data for shading correction from an image read from a fixed density reference member that has been moved by the movable mechanism to a reading position different from a reading position used when reading an original; The auxiliary storage unit stores the reference data regenerated by the generation unit.

3. The image reading device according to claim 2.

5. The movable mechanism has an operating member, the lock mechanism switches the concentration reference member between the fixed state and the movable state in response to movement of the operating member.

5. The image reading device according to claim 1.

6. the movable mechanism is a mechanism for moving the density reference member in a main scanning direction; 5. The image reading device according to claim 1.

7. the movable mechanism is a mechanism for moving the density reference member in a sub-scanning direction; 5. The image reading device according to claim 1.

8. An image reading device according to any one of claims 1 to 4, an image forming unit that forms an image read by the image reading device; An image forming apparatus comprising:

9. a locking mechanism switching a density reference member provided opposite the image reading unit from a fixed state to a movable state; a step of moving the density reference member to a reading position different from a reading position used when reading an original by a movable mechanism; An image reading unit reads an image from the density reference member moved to the different reading position; A generating unit generates reference data for shading correction from an image read from the density reference member; a shading correction unit performing shading correction of an image read from an original by using the reference data; An image reading method comprising the steps of:

Images