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 prevent a reduction in the image quality of a formed image while reducing an image reading time of an original document.SOLUTION: An image forming apparatus 100 comprises: an ADF 1; a rear face CIS sensor 43 that reads an image of a rear face of a document; a front face CIS sensor 42 that is arranged below a contact glass to be capable of reciprocating in a scanning direction, and reads an image of a front face of the document; a white reference board 43B that is arranged opposite to the rear face CIS sensor 43; a white reference board 42B that is arranged at a reference position; and a control unit 7 that turns on a first light source of the rear face CIS sensor 43 and generates first white reference data for the rear face by using reflected light reflected on the white reference board 43B, and turns on a second light source of the front face CIS sensor 42 and generates second white reference data for the front face by using reflected light reflected on the white reference board 42B. The control unit 7 controls the first light source and the second light source so that a lighting time of the first light source and a lighting time of the second light source do not overlap with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image reading apparatus, an image forming apparatus, and an image reading method for reading images on both sides of a conveyed document. [Background technology]

[0002] There are known image processing devices equipped with a sheet transport device that transports a document to be read. There are also known image reading devices equipped with multiple reading units that read images on both sides (front and back sides) of a document. For example, the image reading device includes a CIS sensor for reading images on the back side (back CIS sensor) and a CIS sensor for reading images on the front side (front CIS sensor) in the transport path of the ADF, and reads both sides of the document in a single pass (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-082033 Summary of the Invention [Problem to be solved by the invention]

[0004] To reduce the size of the image reading device, a structure in which the back CIS sensor and the front CIS sensor are placed close to each other is conceivable. In this structure, for example, in order to shorten the image reading time of the first document (First Scan Operating Time; FSOT), it is conceivable to perform the setting process of the front CIS sensor, such as generating white reference data, and the setting process of the back CIS sensor at approximately the same time. In this case, however, the irradiation time of the light source (LED) of each CIS sensor overlaps, making it impossible to generate appropriate white reference data, resulting in a problem of degraded image quality.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus, an image forming apparatus, and an image reading method that can prevent a deterioration in the quality of the formed image while shortening the time required to read the image of the first document. [Means for solving the problem]

[0006] According to one aspect of the present invention, an image reading device includes: a conveying unit that conveys a sheet; a first reading unit that is disposed within the conveying unit and that reads an image on the sheet conveyed by the conveying unit; a second reading unit that is disposed below a contact glass and that is capable of reciprocating in a scanning direction; a first white reference plate that is disposed within the conveying unit facing the first reading unit; a second white reference plate that is disposed within the conveying unit at a reference position that can face the second reading unit; and a control unit that turns on a first light source included in the first reading unit to generate first white reference data using light reflected by the first white reference plate, and turns on a second light source included in the second reading unit to generate second white reference data using light reflected by the second white reference plate. The control unit controls the first light source and the second light source so that the turn-on times of the first light source and the second light source do not overlap.

[0007] An image forming apparatus according to another aspect of the present invention includes the image reading device described above and an image forming section that forms an image on the sheet.

[0008] According to another aspect of the present invention, there is provided an image reading method for reading an image in an image reading device including: a conveying unit that conveys a sheet; a first reading unit that is disposed within the conveying unit and that reads an image on a first side of the sheet conveyed by the conveying unit; a second reading unit that is disposed below a contact glass and is movable back and forth in a scanning direction and that reads an image on a second side of the sheet; a first white reference plate that is disposed within the conveying unit and faces the first reading unit; and a second white reference plate that is disposed within the conveying unit at a reference position that can face the second reading unit, the image reading method including a control step of turning on a first light source included in the first reading unit to generate first white reference data using light reflected by the first white reference plate, and turning on a second light source included in the second reading unit to generate second white reference data using light reflected by the second white reference plate, and controlling the first light source and the second light source in the control step so that the lighting time of the first light source and the lighting time of the second light source do not overlap. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an image reading apparatus, an image forming apparatus, and an image reading method that can prevent a deterioration in the quality of the formed image while shortening the time required to read the image of the first document. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the system configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of the ADF and image reading unit of the image forming apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing a schematic diagram of the relationship between the positional relationship between the CIS sensor and the white reference plate and the control time of the light source in the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing an example of an image reading process executed by the image forming apparatus according to the first embodiment of the present invention. [Figure 5]FIG. 5 is a flowchart showing an example of an image reading process executed by the image forming apparatus according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of a specific embodiment of the present invention and does not limit the technical scope of the present invention.

[0012] [Configuration of image forming apparatus 100] First, with reference to FIG. 1, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described.

[0013] The image forming apparatus 100 is a multifunction peripheral having multiple functions, such as a scanning function for reading an image from a document, a printing function for forming an image based on image data, a facsimile function, and a copy function. The image forming apparatus 100 is an example of the image forming apparatus of the present invention. The image forming apparatus of the present invention may also be a scanner, a facsimile machine, a copy machine, or the like.

[0014] As shown in FIG. 1, the image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, an operation display unit 5, a storage unit 6, and a control unit .

[0015] The ADF 1 is a sheet conveying device that conveys a document to be read (an example of a sheet of the present invention). The ADF 1 executes document conveyance processing in accordance with a control instruction from the control unit 7.

[0016] The image reading unit 2 reads an image from a document conveyed by the ADF 1. The image reading unit 2 also reads an image from a document placed on a document table 41 (see FIG. 2).

[0017] The image forming unit 3 forms an image by electrophotography on a sheet supplied from the paper feed unit 4. For example, the image forming unit 3 includes a photosensitive drum, a charging roller, an optical scanning device, a developing device, a transfer roller, a cleaning device, a fixing device, and a paper output tray.

[0018] The paper feed unit 4 supplies sheets to the image forming unit 3. For example, the paper feed unit 4 includes a paper feed cassette, a manual feed tray, a sheet transport path, and a plurality of transport rollers.

[0019] The operation display unit 5 is a user interface of the image forming apparatus 100. For example, the operation display unit 5 has a display unit such as a liquid crystal display that displays various information in response to control instructions from the control unit 7, and an operation unit such as operation keys or a touch panel that inputs various information to the control unit 7 in response to user operations.

[0020] The storage unit 6 is a nonvolatile storage device, such as a nonvolatile memory such as a flash memory or an EEPROM (registered trademark), a solid state drive (SSD), or a hard disk drive (HDD).

[0021] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 1, the control unit 7 includes a CPU 11, a ROM 12, and a RAM 13. The CPU 11 is a processor that executes various types of arithmetic processing. The ROM 12 is a non-volatile storage device that stores in advance information such as control programs for causing the CPU 11 to execute various types of processing. The RAM 13 is a volatile or non-volatile storage device that is used as a temporary storage memory (work area) for the various types of processing executed by the CPU 11. In the control unit 7, the CPU 11 executes the various control programs that are pre-stored in the ROM 12. In this way, the control unit 7 performs overall control of the image forming apparatus 100.

[0022] [Configuration of ADF 1 and image reading unit 2] Next, the configuration of the ADF 1 and the image reading unit 2 will be described with reference to Figures 1 and 2. Here, Figure 2 is a cross-sectional view showing the configuration of the ADF 1 and the image reading unit 2. The ADF 1 and the image reading unit 2 are an example of the image reading device of the present invention.

[0023] As shown in FIG. 2, the ADF 1 includes a document placement unit 21, a housing 22, a pickup roller 23, a separation roller 25, a first transport roller 30, a second transport roller 31, a discharge roller 32, and a discharge unit 33.

[0024] A document to be transported is placed on the document placement unit 21. In the ADF 1, the document placed on the document placement unit 21 is transported in a transport direction D1 shown in FIG.

[0025] A detection unit (not shown) is provided in the document placement unit 21. The detection unit detects whether or not a document is present on the document placement unit 21. For example, the detection unit is a reflective optical sensor provided on the document placement surface of the document placement unit 21.

[0026] Further, a lift plate (not shown) is provided on the document placement section 21. The lift plate lifts the document stack placed on the document placement section 21 up to a contact position with the pickup roller 23.

[0027] The housing 22 houses rollers and the like used to transport the document. As shown in Fig. 2, a first transport path 22A and a second transport path 22C for guiding the document are formed inside the housing 22. The second transport path 22C includes a curved portion 22B that curves from the first transport path 22A and leads to the discharge portion 33. The curved portion 22B is curved at a curvature that allows the document to make a U-turn inside the housing 22.

[0028] In the ADF 1, a document placed on the document placement unit 21 is transported along a transport path that leads to the discharge unit 33 via the first transport path 22A, the curved portion 22B, and the second transport path 22C.

[0029] Pickup roller 23 is provided above document placement unit 21. Pickup roller 23 comes into contact with the surface (top surface) of the uppermost document in the document stack lifted by the lift plate, and transports the document in transport direction D1. A paper feed belt (not shown) is provided in first transport path 22A, and comes into contact with the surface of the document transported in transport direction D1 by pickup roller 23, and transports the document downstream in transport direction D1.

[0030] The first transport roller 30 is provided on the curved portion 22B. The first transport roller 30 comes into contact with the document and transports the document downstream in the transport direction D1.

[0031] An opening 22D is formed in the second transport path 22C downstream in the transport direction D1 from the first transport roller 30. In the opening 22D, the image on the front surface of the document passing through the opening 22D is read by the surface CIS sensor 42 (see FIGS. 1 and 2) of the image reading unit 2.

[0032] The second transport roller 31 is provided on the second transport path 22C downstream of the opening 22D in the transport direction D1. The second transport roller 31 comes into contact with the document transported by the first transport roller 30, and transports the document downstream in the transport direction D1.

[0033] The discharge roller 32 is provided on the second transport path 22C downstream of the second transport roller 31 in the transport direction D1. The discharge roller 32 comes into contact with the document transported by the second transport roller 31 and discharges the document to the discharge section 33. The discharge section 33 is loaded with the document discharged by the discharge roller 32.

[0034] As shown in FIGS. 1 and 2, the image reading unit 2 includes a platen 41, a front CIS sensor 42, and a rear CIS sensor 43.

[0035] The front CIS sensor 42 is a CIS sensor-type reading unit, and is equipped internally with a light source (LED), a condenser lens composed of multiple lenses, and a CMOS sensor. In the front CIS sensor 42, light emitted from the light source passes through the reading glass and is reflected by the document, and the reflected light (image light) passes through the reading glass again and is condensed by the condenser lens, forming an image on the CMOS sensor. The formed image light is resolved into pixels in the CMOS sensor and converted into electrical signals corresponding to the density of each pixel, thereby reading the image. The back CIS sensor 43 has the same configuration as the front CIS sensor, and is equipped with a light source (LED), a condenser lens, and a CMOS sensor.

[0036] A document to be read is placed on document table 41. Document table 41 is provided on the upper part of the housing of image forming apparatus 100. ADF 1 is provided so as to be openable and closable relative to document table 41, and also serves as a document cover that supports one side of a document placed on first contact glass 411 of document table 41.

[0037] 2, the platen 41 includes a first contact glass 411, a second contact glass 412, and a guide member 413. A document, whose image is to be read by the front surface CIS sensor 42, is placed on the first contact glass 411. The second contact glass 412 and the guide member 413 face the opening 22D of the housing 22 and form part of the second transport path 22C when the ADF 1 is closed relative to the platen 41. The second contact glass 412 transmits light emitted from the front surface CIS sensor 42 toward the opening 22D and light reflected by the document. The guide member 413 guides the document to the discharge rollers 32 downstream of the second contact glass 412 in the transport direction D1.

[0038] The front CIS sensor 42 is provided below the first contact glass 411 and the second contact glass 412. The front CIS sensor 42 is elongated in the depth direction of the paper in FIG. 2 and is provided so as to be able to move back and forth along the left-right direction of the paper in FIG. 2. The front CIS sensor 42 reads an image on the front side of a document conveyed by the ADF 1 while being disposed at a position (reading position DP) below the second contact glass 412. Specifically, the front CIS sensor 42 outputs an analog signal corresponding to the image read from the front side of the document. The analog signal output from the front CIS sensor 42 is converted into a digital signal (image data) by an analog front-end circuit (not shown) and input to the control unit 7.

[0039] Further, a white reference plate 42B (front surface shading plate) for shading correction of the front surface CIS sensor 42 is disposed below the guide member 413 (at the reference position HP). That is, the white reference plate 42B is disposed at the reference position HP within the ADF 1 so as to be able to face the front surface CIS sensor 42. When the front surface CIS sensor 42 is disposed at the reference position HP, the light source is turned on and white reference data is generated from light reflected by the white reference plate 42B.

[0040] The back CIS sensor 43 is disposed within the ADF 1 and reads an image on the back side of a document conveyed by the ADF 1. The back CIS sensor 43 is disposed in a position facing the front CIS sensor 42 across the opening 22D. Specifically, as shown in FIG. 2, the back CIS sensor 43 is disposed downstream of the curved portion 22B and the first conveyance roller 30 in the conveyance direction D1 and upstream of the second conveyance roller 31. The back CIS sensor 43 is also disposed downstream of the reading position DP and upstream of the reference position HP. The back CIS sensor 43 outputs an analog signal corresponding to the image read from the back side of the document. The analog signal output from the back CIS sensor 43 is converted into a digital signal (image data) by an analog front-end circuit (not shown) and input to the control unit 7.

[0041] Furthermore, a white reference plate 43B (rear shading plate) for shading correction of the rear CIS sensor 43 is disposed at a position facing the rear CIS sensor 43. The white reference plate 43B is disposed between the first contact glass 411 and the rear CIS sensor 43. The rear CIS sensor 43 generates white reference data by turning on a light source and receiving light reflected by the white reference plate 43B.

[0042] In this way, the back CIS sensor 43 and the white reference plate 43B are positioned downstream in the document transport direction from the reading position DP where the front CIS sensor 42 reads the document image, and the white reference plate 42B is positioned downstream in the transport direction from the back CIS sensor 43 and the white reference plate 43B.

[0043] As described above, by adopting a structure in which the front CIS sensor 42 and the back CIS sensor 43 are arranged opposite each other, the image reading device (ADF 1 and image reading unit 2) can be made smaller and costs reduced. In this structure, for example, to shorten the image reading time (FSOT) of the first document, it is possible to set the front CIS sensor and the back CIS sensor, such as generating white reference data, at approximately the same time. However, in this case, the illumination times of the light sources (LEDs) of the CIS sensors overlap, making it impossible to generate appropriate white reference data, resulting in a problem of reduced image quality. In contrast, the image forming apparatus 100 according to an embodiment of the present invention can prevent a reduction in the image quality of the formed image while shortening the image reading time of the first document, as described below.

[0044] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described in more detail with reference to Fig. 1. As shown in Fig. 1, the control unit 7 includes a lighting processing unit 51, a movement processing unit 52, and a setting processing unit 53.

[0045] Specifically, the ROM 12 pre-stores an image reading program for causing the CPU 11 to execute the image reading process (see FIGS. 4 and 5) described below. The control unit 7 executes the image reading program stored in the ROM 12, thereby functioning as a lighting processing unit 51, a movement processing unit 52, and a setting processing unit 53. Here, an apparatus including the ADF 1, the image reading unit 2, and the control unit 7 is an example of the image reading device of the present invention. Note that the present invention may also be realized by an apparatus including the image reading unit 2 and the control unit 7.

[0046] The image reading program may be recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and may be read from the recording medium and stored in a storage device such as the memory unit 6. The lighting processing unit 51, the movement processing unit 52, and the setting processing unit 53 may be configured by electronic circuits such as an integrated circuit (ASIC).

[0047] Here, the control unit 7 performs processing (setting processing) required for initial setting and adjustment of the front CIS sensor 42 and the back CIS sensor 43 at various times, such as when the image forming apparatus 100 is powered on, when returning from a power saving state (sleep mode), when there is a predetermined change in temperature and humidity, and when starting an image reading process. In addition, in the setting processing, the control unit 7 turns on the light sources of the front CIS sensor 42 and the back CIS sensor 43, and generates white reference data from the light reflected from the white reference plates 42B and 43B.

[0048] Specifically, the control unit 7 turns on the light source included in the front CIS sensor 42 to generate white reference data for the front CIS sensor 42 (for the front-surface read image) from the light reflected by the white reference plate 42B, and turns on the light source included in the back CIS sensor 43 to generate white reference data for the back CIS sensor 43 (for the back-surface read image) from the light reflected by the white reference plate 43B. Furthermore, the control unit 7 controls each light source so that the lighting time of the light source of the front CIS sensor 42 and the lighting time of the light source of the back CIS sensor 43 do not overlap.

[0049] The lighting processing unit 51, the movement processing unit 52, and the setting processing unit 53 included in the control unit 7 each execute a process for generating the white reference data.

[0050] The lighting processing unit 51 controls the lighting (ON) and extinguishing (OFF) of the light sources of the front CIS sensor 42 and the back CIS sensor 43.

[0051] The movement processing unit 52 controls the movement of the front surface CIS sensor 42. Specifically, in the setting process, the movement processing unit 52 moves the front surface CIS sensor 42 in the scanning direction (the left-right direction in FIG. 2) between the reference position HP and the reading position DP shown in FIG.

[0052] The setting processing unit 53 performs initial setting and adjustment of each of the front CIS sensor 42 and the back CIS sensor 43. The setting processing unit 53 also generates reference data (white reference data, black reference data).

[0053] When the control unit 7 generates the white reference data, the control unit 7 performs shading correction using the white reference data when reading an image. That is, the control unit 7 generates the white reference data before reading an image of a conveyed document, and performs shading correction on the read image using the generated white reference data.

[0054] The control unit 7 generates the white reference data and executes the image reading process, for example, by using the configurations of the following Examples 1 and 2. The control unit 7 may have either the configuration of Example 1 or Example 2, or may have both the configurations and be able to switch between them as appropriate.

[0055] [Image reading process according to the first embodiment] 3 and 4 show an example of the procedure of the image reading process executed by the control unit 7 of the image forming apparatus 100 according to the first embodiment.

[0056] The present invention can be understood as an image reading method (image reading method of the present invention) that executes one or more steps included in the image reading process. One or more steps included in the image reading process described here may be omitted as appropriate. The steps in the image reading process may be executed in a different order as long as the same operational effect is achieved. While the example described here is one in which the control unit 7 executes each step in the image reading process, in other embodiments, one or more processors may execute each step in the image reading process in a distributed manner. The image reading process is executed at the start of the image reading process.

[0057] Fig. 3 shows a schematic diagram of the positional relationship between the front CIS sensor 42, rear CIS sensor 43, and white reference plate 42B, and the relationship with the light source control time. Note that Fig. 3 shows the state shown in Fig. 2 reversed from left to right, with the direction of movement of the front CIS sensor 42 from the reference position HP toward the reading position DP indicated as the rightward direction.

[0058] 3, the white reference plate 42B is positioned so that its front end (the front end of the SHD plate) is 2 mm from the reference position HP and its rear end (the rear end of the SHD plate) is 7.6 mm from the reference position HP. The rear CIS sensor 43 is positioned 17.9 mm from the rear end of the white reference plate 42B and 10 mm from the reading position DP.

[0059] <Step S11> First, in step S11, the control unit 7 acquires a request (reading request) to read images on both sides of a document. For example, when a user performs an operation to start image formation on both sides of the document, the control unit 7 acquires the reading request. At this point, the front CIS sensor 42 is located at the reference position HP, and the light source is turned off.

[0060] <Step S12> In step S12, the control unit 7 (setting processing unit 53) performs setting processing for the front surface CIS sensor 42. Specifically, the setting processing unit 53 performs initial setting, adjustment, mode setting, etc. for the front surface CIS sensor 42. The setting processing unit 53 also generates black reference data for the front surface CIS sensor 42 by controlling the light source to turn off while the front surface CIS sensor 42 is positioned at the reference position HP. In step S12, the control unit 7 performs the setting processing using a well-known method.

[0061] <Step S13> In step S13, the control unit 7 (lighting processing unit 51) turns on the light source of the front surface CIS sensor 42 (ON).

[0062] <Step S14> In step S14, the control unit 7 (movement processing unit 52) ​​moves the front surface CIS sensor 42 from the reference position HP to the rear end position of the white reference plate 42B (the rear end of the SHD plate). While the front surface CIS sensor 42 is moving, the light source remains lit, and white reference data for the front surface CIS sensor 42 is generated.

[0063] <Step S15> In step S15, the control unit 7 (lighting processing unit 51) turns off the light source of the front surface CIS sensor 42. The lighting processing unit 51 turns off the light source when the front surface CIS sensor 42 reaches the end of the white reference plate 42B. In this way, the control unit 7 turns on the light source while moving the front surface CIS sensor 42 from the reference position HP to the rear end position of the white reference plate 42B, and generates white reference data.

[0064] <Step S16> In step S16, the control unit 7 (movement processing unit 52) ​​moves the front surface CIS sensor 42 from the rear end position of the white reference plate 42B (rear end of the SHD plate) to the reading position DP. That is, the movement processing unit 52 places the front surface CIS sensor 42 at the reference position HP and generates white reference data, and then turns off the light source and moves the front surface CIS sensor 42 from the reference position HP to the reading position DP. While the front surface CIS sensor 42 is moving, the light source remains off (see FIG. 3).

[0065] <Step S17> In step S17, the control unit 7 (lighting processing unit 51) turns on the light source of the front surface CIS sensor 42. In this way, the control unit 7 turns off the light source during the section in which the front surface CIS sensor 42 moves from the white reference plate 42B to the reading position DP, and turns on the light source at the timing when the front surface CIS sensor 42 reaches the reading position DP. After step S17, the control unit 7 transitions the process to step S18.

[0066] Here, the control unit 7 executes the setting process for the front CIS sensor 42 and the setting process for the back CIS sensor 43 at the same time (step S21).

[0067] <Step S21> In step S21, the control unit 7 (setting processing unit 53) performs setting processing for the back CIS sensor 43. Specifically, the setting processing unit 53 performs initial setting, adjustment, mode setting, etc. for the back CIS sensor 43. The setting processing unit 53 also controls the lighting of the light source of the back CIS sensor 43 to generate black reference data and white reference data for the back CIS sensor 43. In step S21, the control unit 7 performs the setting processing by a well-known method.

[0068] In step S21, the control unit 7 may turn off the light source of the back CIS sensor while turning on the light source of the front CIS sensor 42 to generate white reference data. That is, the control unit 7 may generate white reference data for the back CIS sensor after generating white reference data for the front CIS sensor 42.

[0069] Furthermore, the control unit 7 may generate white reference data for the back CIS sensor 43 while the front CIS sensor 42 is being moved from the reference position HP to the reading position DP.

[0070] <Step S22> In step S22, the control unit 7 executes a document transport process. Specifically, the control unit 7 outputs an instruction to transport the document to be read to the ADF 1. After step S22, the control unit 7 shifts the process to step S18.

[0071] <Step S18> In step S18, the control unit 7 starts a reading process for reading images on both sides of the conveyed document. Specifically, the control unit 7 performs shading correction on the read image on the front side using the white reference data for the front side generated by the front CIS sensor 42, and performs shading correction on the read image on the back side using the white reference data for the back side generated by the back CIS sensor 43.

[0072] As described above, in the image reading method according to the first embodiment, the control unit 7 generates white reference data for the front CIS sensor 42 and white reference data for the back CIS sensor 43 by adjusting the ON / OFF times of the light source of the front CIS sensor 42 (see FIG. 3). Specifically, the control unit 7 sets the light source to the OFF state during the section in which the front CIS sensor 42 moves from the white reference plate 42B to the reading position DP. As a result, even when the setting process for the back CIS sensor 43 is performed while the front CIS sensor 42 is moving, the irradiation time of the light source of the back CIS sensor 43 and the irradiation time of the light source of the front CIS sensor 42 do not overlap, and therefore the white reference data for the back CIS sensor 43 can be appropriately generated.

[0073] Furthermore, according to the above configuration, the setting process of the front CIS sensor 42 (the process of generating white reference data) and the setting process of the back CIS sensor 43 (the process of generating white reference data) can be performed at the same time, thereby shortening the time required to read the image of the first document.

[0074] [Image reading process according to the second embodiment] 5 shows an example of the procedure of the image reading process executed by the control unit 7 of the image forming apparatus 100 according to the second embodiment. The positional relationship between the front CIS sensor 42, the back CIS sensor 43, and the white reference plate 42B is the same as the configuration shown in FIG.

[0075] <Step S31> First, in step S31, the control unit 7 acquires a request to read images on both sides of a document (a reading request). For example, when a user performs an operation to start image formation on both sides of an image, the control unit 7 acquires the reading request. At this point, the front CIS sensor 42 is located at the reference position HP, and the light source is turned off. When the control unit 7 acquires the reading request, it executes the following setting process (S32 to S37) for the front CIS sensor 42 and the setting process (S51 to S56) for the back CIS sensor 43.

[0076] <Step S32> In step S32, the control unit 7 (setting processing unit 53) performs initial setting of the front surface CIS sensor .

[0077] <Step S33> In step S33, the control unit 7 (setting processing unit 53) adjusts the front surface CIS sensor .

[0078] <Step S34> In step S34, the control unit 7 (setting processing unit 53) sets the mode of the front surface CIS sensor 42.

[0079] <Step S35> In step S35, the control unit 7 (setting processing unit 53) generates black reference data for the front surface CIS sensor 42. After generating the black reference data for the front surface CIS sensor 42, the control unit 7 interrupts the setting process for the front surface CIS sensor 42.

[0080] The control unit 7 executes the setting process for the rear CIS sensor 43 at the same timing as the processes in steps S32 to S35.

[0081] <Step S51> In step S51, the control unit 7 (setting processing unit 53) performs initial setting of the rear CIS sensor 43.

[0082] <Step S52> In step S52, the control unit 7 (setting processing unit 53) adjusts the rear CIS sensor 43.

[0083] <Step S53> In step S53, the control unit 7 (setting processing unit 53) sets the mode of the rear CIS sensor 43.

[0084] <Step S54> In step S54, the control unit 7 (setting processing unit 53) generates black reference data for the rear CIS sensor 43.

[0085] <Step S55> In step S55, the control unit 7 (lighting processing unit 51) turns on the light source of the rear CIS sensor 43 (ON).

[0086] <Step S56> In step S56, the control unit 7 (setting processing unit 53) generates white reference data for the back CIS sensor 43. After generating the white reference data for the back CIS sensor 43, the control unit 7 shifts the process to step S36 and resumes the setting process for the front CIS sensor 42.

[0087] <Step S57> In step S57, the control unit 7 executes a document transport process. Specifically, the control unit 7 outputs an instruction to transport the document to be read to the ADF 1. After step S57, the control unit 7 shifts the process to step S40.

[0088] <Step S36> In step S36, the control unit 7 (lighting processing unit 51) turns on (ON) the light source of the surface CIS sensor 42. After turning on the light source of the surface CIS sensor 42, the control unit 7 executes the processes of steps S37 and S38.

[0089] <Step S37> In step S37, the control unit 7 (setting processing unit 53) generates white reference data for the front CIS sensor 42. After generating the white reference data for the front CIS sensor 42, the control unit 7 shifts the process to step S39. In this way, with the front CIS sensor 42 placed at the reference position HP, the setting processing unit 53 generates the white reference data for the back CIS sensor 43, and then generates the white reference data for the front CIS sensor 42.

[0090] <Step S38> In step S38, the control unit 7 (movement processing unit 52) ​​moves the front CIS sensor 42 from the reference position HP to the reading position DP. While the front CIS sensor 42 is moving, the light source remains on. In this way, after generating white reference data for the back CIS sensor 43, the control unit 7 turns on the light source of the front CIS sensor 42 and moves the front CIS sensor 42 from the reference position HP to the reading position DP.

[0091] <Step S39> In step S39, the control unit 7 (lighting processing unit 51) turns off the light source of the front CIS sensor 42. In this way, in the second embodiment, the front CIS sensor 42 is moved to the reading position DP after generating the white reference data of the back CIS sensor 43, so there is no need to turn off the light source of the front CIS sensor 42 while the front CIS sensor 42 is moving.

[0092] <Step S40> In step S40, the control unit 7 starts a reading process for reading images on both sides of the conveyed document. Specifically, the control unit 7 performs shading correction on the read image on the front side using the white reference data for the front side generated by the front CIS sensor 42, and performs shading correction on the read image on the back side using the white reference data for the back side generated by the back CIS sensor 43.

[0093] As described above, in the image reading method according to the second embodiment, the control unit 7 generates white reference data for the front CIS sensor 42 after completing the process of generating white reference data for the back CIS sensor, thereby generating white reference data for the front CIS sensor 42 and white reference data for the back CIS sensor 43. Specifically, when generating the white reference data for the back CIS sensor, the control unit 7 positions the front CIS sensor 42 at the reference position HP without moving it, and after generating the white reference data for the back CIS sensor, generates the white reference data for the front CIS sensor 42 and moves it from the reference position HP to the reading position DP. This prevents the irradiation time of the light source for the back CIS sensor 43 from overlapping with the irradiation time of the light source for the front CIS sensor 42, making it possible to appropriately generate white reference data for the back CIS sensor 43.

[0094] Furthermore, with the above configuration, the setting process for the front CIS sensor 42 (initial settings, adjustment, mode setting, black reference data generation process) and the setting process for the back CIS sensor 43 (initial settings, adjustment, mode setting, black reference data generation process) can be performed at the same time, thereby shortening the time required to read the image of the first document.

[0095] In this way, the control unit 7 repeatedly executes the operation mode switching process each time the image forming apparatus 100 is turned on or returns from the sleep mode. Note that the image reading process in the above-described first and second embodiments is merely an example, and the content and order of the process can be changed as appropriate.

[0096] As described above, the image forming apparatus 100 comprises an ADF1 that transports an original, a back CIS sensor 43 (first reading unit) that is arranged within the ADF1 and reads the image of the original transported by the ADF1, a front CIS sensor 42 (second reading unit) that is arranged below the first contact glass 411 so as to be movable back and forth in the scanning direction, a white reference plate 43B (first white reference plate) that is arranged within the ADF1 to face the back CIS sensor 43, a white reference plate 42B (second white reference plate) that is arranged within the ADF1 at a reference position HP that can face the front CIS sensor 42, and a control unit 7 that turns on a first light source included in the back CIS sensor 43 to generate first white reference data for the back side using light reflected by the white reference plate 43B, and turns on a second light source included in the front CIS sensor 42 to generate second white reference data for the front side using light reflected by the white reference plate 42B. Furthermore, the control unit 7 controls the first light source and the second light source so that the lighting time of the first light source and the lighting time of the second light source do not overlap.

[0097] According to the above configuration, the light source illumination time when generating the white reference data for the front CIS sensor 42 and the light source illumination time when generating the white reference data for the back CIS sensor 43 do not overlap, so each piece of white reference data can be generated appropriately. This prevents a decrease in the quality of the formed image. Furthermore, according to the above configuration, the setting process for the front CIS sensor 42 and the setting process for the back CIS sensor 43 can be performed at the same time, so the time required to read the image of the first document can be shortened.

[0098] [Disclosure Note] The following will provide an outline of the disclosure extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0099] <Appendix 1> a conveying unit that conveys a sheet; a first reading unit disposed within the conveying unit and configured to read an image on a first surface of the sheet conveyed by the conveying unit; a second reading unit that is disposed below the contact glass so as to be reciprocable in a scanning direction and that reads an image on a second surface of the sheet; a first white reference plate disposed in the transport unit opposite the first reading unit; a second white reference plate disposed in a reference position within the transport unit so as to be able to face the second reading unit; a control unit that turns on a first light source included in the first reading unit to generate first white reference data using light reflected by the first white reference plate, and turns on a second light source included in the second reading unit to generate second white reference data using light reflected by the second white reference plate; Equipped with the control unit controls the first light source and the second light source so that a lighting time of the first light source and a lighting time of the second light source do not overlap. Image reading device.

[0100] <Appendix 2> the first reading unit and the first white reference plate are disposed downstream in a conveyance direction of the sheet from a reading position where the second reading unit reads an image on the sheet, the second white reference plate is disposed downstream of the first reading unit and the first white reference plate in a conveying direction of the sheet; 2. An image reading device according to claim 1.

[0101] <Appendix 3> the first white reference plate is disposed between the first reading unit and the contact glass; 3. An image reading device according to claim 1 or 2.

[0102] <Appendix 4> the control unit places the second reading unit at the reference position and generates the second white reference data, and then turns off the second light source and moves the second reading unit from the reference position to the reading position. 4. The image reading device according to any one of claims 1 to 3.

[0103] <Appendix 5> the control unit turns off the second light source at a timing when the second reading unit reaches an end of the second white reference plate. 5. The image reading device according to claim 4.

[0104] <Appendix 6> The control unit further generates the first white reference data while the second reading unit is being moved from the reference position to the reading position. 6. An image reading device according to claim 4 or 5.

[0105] <Appendix 7> the control unit generates the first white reference data in a state where the second reading unit is disposed at the reference position, and then generates the second white reference data. 4. The image reading device according to any one of claims 1 to 3.

[0106] <Appendix 8> the control unit further turns on the second light source and moves the second reading unit from the reference position to the reading position after generating the first white reference data. 8. The image reading device according to claim 7. [Explanation of symbols]

[0107] 100: Image forming device 2: Image reading unit 3: Image forming unit 7: Control section 22D: Opening 42: Surface CIS sensor 42B: White reference plate 43: Rear CIS sensor 43B: White reference plate 51: Lighting processing unit 52: Movement processing unit 53: Setting processing section 411: First contact glass 412: Second contact glass DP: Reading position HP: Reference position

Claims

1. a conveying unit that conveys a sheet; a first reading unit disposed within the conveying unit and configured to read an image on a first surface of the sheet conveyed by the conveying unit; a second reading unit that is disposed below the contact glass so as to be reciprocable in a scanning direction and that reads an image on a second surface of the sheet; a first white reference plate disposed in the transport unit opposite the first reading unit; a second white reference plate disposed in the transport unit at a reference position capable of facing the second reading unit; a control unit that turns on a first light source included in the first reading unit to generate first white reference data using light reflected by the first white reference plate, and turns on a second light source included in the second reading unit to generate second white reference data using light reflected by the second white reference plate; Equipped with the control unit controls the first light source and the second light source so that a lighting time of the first light source and a lighting time of the second light source do not overlap. Image reading device.

2. the first reading unit and the first white reference plate are disposed downstream in a conveyance direction of the sheet from a reading position where the second reading unit reads an image on the sheet, the second white reference plate is disposed downstream of the first reading unit and the first white reference plate in a conveying direction of the sheet; 2. The image reading device according to claim 1.

3. the first white reference plate is disposed between the first reading unit and the contact glass; 3. The image reading device according to claim 2.

4. the control unit places the second reading unit at the reference position and generates the second white reference data, and then turns off the second light source and moves the second reading unit from the reference position to the reading position.

3. The image reading device according to claim 2.

5. the control unit turns off the second light source at a timing when the second reading unit reaches an end of the second white reference plate.

5. The image reading device according to claim 4.

6. The control unit further generates the first white reference data while the second reading unit is being moved from the reference position to the reading position.

5. The image reading device according to claim 4.

7. the control unit generates the first white reference data in a state where the second reading unit is disposed at the reference position, and then generates the second white reference data.

3. The image reading device according to claim 2.

8. the control unit further turns on the second light source and moves the second reading unit from the reference position to the reading position after generating the first white reference data.

8. The image reading device according to claim 7.

9. 9. An image forming apparatus comprising: the image reading device according to claim 1; and an image forming section that forms an image on the sheet.

10. an image reading method for reading an image in an image reading device including: a conveying unit that conveys a sheet; a first reading unit that is disposed within the conveying unit and that reads an image on a first side of the sheet conveyed by the conveying unit; a second reading unit that is disposed below a contact glass so as to be able to move back and forth in a scanning direction and that reads an image on a second side of the sheet; a first white reference plate that is disposed within the conveying unit and faces the first reading unit; and a second white reference plate that is disposed within the conveying unit at a reference position that can face the second reading unit, a control step of turning on a first light source included in the first reading unit to generate first white reference data by light reflected by the first white reference plate, and turning on a second light source included in the second reading unit to generate second white reference data by light reflected by the second white reference plate, In the control step, the first light source and the second light source are controlled so that a lighting time of the first light source and a lighting time of the second light source do not overlap. Image reading method.

Images