Information processing system and program

Abstract

To achieve a technique to correct a black level having less restrictions required on an image sensor, compared with a technique to correct a black level requiring the presence of a position hardly affected by external light and a position easily affected by external light on the image sensor.SOLUTION: An information processing system is provided, which has an image sensor that reads an image of a document, and one or more processors. When incident of external light is detected from output data of the image sensor, the one or more processors move the image sensor in a direction opposite to a reading direction from a first position for starting reading of the document in a stationary state, and correct a black level of the image sensor at a second position where the entirety of a light receiving surface of the image sensor is hidden by a housing.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an information processing system and a program. [Background technology]

[0002] A so-called scanner reads an image of a document using an image sensor that is moved relatively to the document. Before the image is read by the scanner, black level correction is performed to remove the influence of external light on the image to be read. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7117866 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a black level correction technique that corrects the black level at a position where the influence of external light is easily seen based on the amount of light received at a position where the influence of external light is less noticeable. However, this type of technique cannot deal with cases where the influence of external light extends over the entire area of ​​the image sensor.

[0005] The present invention aims to make it possible to realize a black level correction technique that places fewer constraints on the image sensor compared to a black level correction technique that requires that there be positions on the image sensor where the effects of external light are unlikely to appear and positions where the effects of external light are likely to appear. [Means for solving the problem]

[0006] The invention described in claim 1 is an information processing system comprising a light source that illuminates an original document, an image sensor that reads an image of the original document, and one or more processors, wherein when incidence of external light is detected from the output data of the image sensor, the one or more processors move the image sensor from a first position for starting reading of a stationary original document in a direction opposite to the reading direction, and correct the black level of the image sensor at a second position where the entire light receiving surface of the image sensor is hidden by a housing. An invention described in claim 2 is the information processing system described in claim 1, wherein the second position is located farther away than a reading position for reading an image from a transported document. The invention described in claim 3 is an information processing system described in claim 1 or 2, wherein the one or more processors detect the presence or absence of external light from the output of the image sensor when turning on the main power or when returning from a power saving state is detected. The invention described in claim 4 is the information processing system described in claim 1, wherein, when the presence of external light is detected at the second position, the one or more processors correct the black level using output data detected and stored by the image sensor in the absence of external light. The invention described in claim 5 is an information processing system described in claim 4, wherein the output data detected and stored by the image sensor in the absence of external light is data at the time of shipment, at the time of setup, or at an execution time in which the presence of external light is not detected. The invention described in claim 6 is the information processing system described in claim 1, wherein when a human presence sensor detects the presence of a person in front of the operation panel, even if external light is detected at the second position, the one or more processors correct the black level using the output data of the image sensor at the first position. The invention described in claim 7 is an information processing system described in claim 6, wherein the one or more processors do not perform black level correction when the human presence sensor does not detect the presence of a person in front of the operation panel if the presence of external light is detected even at the second position. The invention described in claim 8 is a program for enabling a computer to realize the following functions: when the presence of external light is detected from the output data of an image sensor reading an image of a document, move the image sensor from a first position for starting reading the image of the document in a stationary state in a direction opposite to the reading direction of the document, and correct the black level of the image sensor at a second position where the entire light receiving surface of the image sensor is hidden by the housing. Effect of the Invention

[0007] According to the invention described in claim 1, it is possible to realize a black level correction technique that places fewer constraints on the image sensor, compared to a black level correction technique that requires that there be positions on the image sensor that are less susceptible to the effects of external light and positions that are more susceptible to the effects of external light. According to the invention described in claim 2, the black level can be corrected at a position where the incident direction of external light is restricted. According to the invention as set forth in claim 3, it is possible to increase the opportunities for correcting the black level. According to the invention as set forth in claim 4, it is possible to use the black level in normal times that is actually detected by the image sensor at the position where external light is incident. According to the invention as set forth in claim 5, it is possible to use the black level in normal times that is actually detected by the image sensor at the position where external light is incident. According to the invention described in claim 6, the black level can be corrected without being affected by external light. According to the seventh aspect of the invention, the correction of the black level can be stopped until the outside light has no effect. According to the invention described in claim 8, it is possible to realize a black level correction technique that places fewer constraints on the image sensor, compared to a black level correction technique that requires that there be positions on the image sensor that are less susceptible to the effects of external light and positions that are more susceptible to the effects of external light. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of an external configuration of an image forming apparatus according to a first embodiment. [Diagram 2]FIG. 2 is a diagram illustrating an example of an internal configuration of an image forming apparatus. [Diagram 3] FIG. 2 is a cutaway view showing the vicinity of a document table of the device main body used in the first embodiment. [Figure 4] FIG. 2 is a diagram illustrating an incident path of external light. [Diagram 5] 11A and 11B are diagrams illustrating the relationship between pixel positions and black data when external light is incident on the housing. [Figure 6] 4 is a flowchart illustrating a processing operation employed in the first embodiment. [Figure 7] FIG. 13 is a diagram illustrating prediction correction. [Figure 8] FIG. 1 is a diagram illustrating blocking of external light by a person. [Figure 9] 11 is a cutaway view showing the vicinity of the document table of the device main body used in the second embodiment. FIG. [Figure 10] 11 is a flowchart illustrating a processing operation employed in the second embodiment. [Figure 11] 13A and 13B are diagrams illustrating movement of the image reading unit to the left end in the housing. [Figure 12] 13 is a flowchart illustrating a processing operation employed in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. <Embodiment 1> <Appearance> Fig. 1 is a diagram showing an example of the external configuration of an image forming apparatus 1 assumed in the first embodiment. The image forming apparatus 1 shown in Fig. 1 represents one form of an apparatus (a so-called multifunction machine) used in an office. Therefore, the image forming apparatus 1 has a printing function, a copy printing function, a facsimile function, a scanner function, and other functions. The image forming apparatus 1 described in the first embodiment is an example of an information processing system.

[0010] The image forming apparatus 1 has a structure in which a document transport unit 20 is attached to the upper surface of a device body 10. The device body 10 is provided with a document table 11, an operation panel 12, a center tray 13, a power switch 14, a front cover 15, a paper tray 16, a manual feed tray 17, a side tray 18, and a human sensor 19. In Fig. 1, the sub-scanning direction is the X-axis, the main scanning direction is the Y-axis, and the vertical upward direction is the Z-axis.

[0011] The document table 11 is provided with a document glass 11A for reading an image (hereinafter referred to as "image") from a document placed on the glass surface, and a document reading glass 11B for reading an image from a document transported at a constant speed by a document transport unit 20. The document glass 11A and the document reading glass 11B are separated in the X-axis direction by a strip-shaped member 11C1 that constitutes part of the document table 11. The long side of this strip-shaped member 11C1 on the document glass 11A side defines the reading start position of the effective reading range on the document glass 11A. The long side of the strip-shaped member 11C1 is parallel to the Y-axis. The strip-shaped member 11C1, like the rest of the housing, is made of a material that does not transmit light.

[0012] On the opposite side of the belt-shaped member 11C1 with respect to the document reading glass 11B, a belt-shaped member 11C2 is disposed, which forms one outer edge of the document table 11. The long side of the belt-shaped member 11C2 is also parallel to the Y-axis. The belt-shaped member 11C2 is made of a material that does not transmit light, just like the other parts of the housing. The operation panel 12 is provided with operation-related buttons, lamps, a capacitance-type touch panel, and the like. Furthermore, a human sensor 19 is attached to a part of the operation panel 12.

[0013] Paper on which an image is printed is discharged, print side down, to the center tray 13. The images here include images received from an external terminal as a print job, images read from an original, and the like. A power switch 14 is used to turn the power of the device main body on and off. The front cover 15 is a cover that is opened when replacing consumables or when turning the main power on and off. In this embodiment, the side on which the operation panel 12 and the front cover 15 are attached is called the front, and the side on which the hinge for opening and closing the document transport unit 20 is attached is called the back.

[0014] The paper tray 16 is a tray that stores paper used for printing. The paper tray 16 is also called a paper feed tray. The manual feed tray 17 is a tray that is used when printing an image on a type of paper that is not stored in the paper tray 16 . The paper on which the image is printed is discharged onto the side tray 18 with the printed side facing up. The human presence sensor 19 is a sensor, for example an infrared sensor, that detects a person operating the operation panel 12. In the case of this embodiment, the human presence sensor 19 is provided near the front of the document reading glass 11B.

[0015] <Internal structure> FIG. 2 is a diagram illustrating an example of the internal configuration of the image forming apparatus 1. As shown in FIG. The image forming apparatus 1 has a control unit 100, a main memory device 104, an operation panel unit 105, an image reading unit 106, an image processing unit 107, an image forming unit 108, a communication unit 109, and a signal line 110 such as a bus that connects these units. The control unit 100 is composed of a processor 101, a ROM (=Read Only Memory) 102, and a RAM (=Random Access Memory) 103.

[0016] The processor 101 is a processing device that uses a RAM 103 as a working area, executes a program read from a ROM 102, and realizes various functions. The ROM 102 stores, for example, a BIOS (Basic Input Output System) and firmware. The main storage device 104 is, for example, a hard disk device or a semiconductor memory, and is used to store image data received as a print job and image data read by the image reading unit 106 .

[0017] The operation panel unit 105 is a device that includes the operation panel 12 (see FIG. 1) and a human presence sensor 19 (see FIG. 1). The operation panel unit 105 is used for displaying an operation screen, accepting operations by a person, detecting the presence of a person operating the operation panel 12, and the like. Image reading unit 106 is a device that reads an image of a document placed on document table 11 or a document transported by document transport unit 20, and is provided in the space below document table 11 (see FIG. 1). In this embodiment, a CIS (=Contact Image Sensor) type sensor is used as image reading unit 106.

[0018] Fig. 3 is a cutaway view showing the vicinity of the document table 11 of the device body 10 used in the embodiment 1. In Fig. 3, parts corresponding to those in Figs. 1 and 2 are denoted by the same reference numerals. In this embodiment, a white reference plate 11D1 is attached to the lower surface side of the belt-shaped member 11C1.

[0019] The image reading unit 106 is movable in the X-axis direction inside the device body 10. For example, when reading the image of a document placed on the document glass 11A, the image reading unit 106 is moved in the sub-scanning direction from near the bottom of the white reference plate 11D1. On the other hand, when reading the image of a document transported by the document transport unit 20, the image reading unit 106 is positioned below the document reading glass 11B.

[0020] The image reading unit 106 is composed of a light source 106A, an imaging lens 106B, an image sensor 106C, and a stage 106D. The light source 106A is, for example, an LED (Light Emission Diode) light source. Although omitted in Fig. 3, light sources 106A corresponding to the colors R (red), G (green), and B (blue) are arranged for color reading. The illumination light output from the light source 106A is guided to the glass surface through a transparent light guide plate.

[0021] The imaging lens 106B is a lens array in which cylindrical, equal-magnification lenses are arranged in the Y-axis direction. For example, a gradient index lens (SLA: Selfoc (registered trademark) lens array) is used for the imaging lens 106B. In the present embodiment, the width in the X-axis direction of the image reading unit 106 that houses the imaging lens 106B is 2.5 mm. The opening width of the imaging lens 106B is a fraction of the width in the X-axis direction of the image reading unit 106, as shown in FIG. 3. The image sensor 106C is a device that reads a linearly formed optical image. The stage 106D is a base for the image sensor 106C.

[0022] Returning to the explanation of Figure 2. The image processing unit 107 is configured as, for example, a dedicated processor or processing board, and is a device that executes image processing such as color correction and gradation correction on image data. The image forming unit 108 is a so-called print engine. The image forming unit 108 includes an electrophotographic engine and an inkjet engine. In the case of the image forming unit 108 that supports color printing, for example, four colors, yellow (Y), magenta (M), cyan (C), and black (K), are used as color materials. The communication unit 109 is composed of, for example, a modem and a LAN interface, and is used for fax communication and communication with external devices.

[0023] <Path of external light incidence> Fig. 4 is a diagram for explaining the incidence paths of external light L1 and L2. Although document transport unit 20 is not depicted in Fig. 4, document transport unit 20 is actually closed. That is, document transport unit 20 actually covers the entire upper surface of document table 11. In the case of FIG. 4, the image reading unit 106 is located below the belt-shaped member 11C1. Even when the document transport unit 20 is closed, a gap is generated between the document table 11 and the document transport unit 20. For this reason, in an environment in which external light is incident on the image forming apparatus 1 from a substantially horizontal direction, two types of incident paths are possible.

[0024] One of the incident paths is an incident path for external light L1. In the case of external light L1, the entire long side of the document reading glass 11B serves as an entrance for the external light L1. The other incident path is an incident path of external light L2. In the case of external light L2, the front end of document reading glass 11B or the front end of document glass 11A serves as an entrance for external light L2.

[0025] 5 is a diagram for explaining the relationship between pixel positions and black data OUT when external light is incident on the housing. The black data OUT here refers to a data value (hereinafter also referred to as an "output value") output from the image sensor 106C in a state where the light source 106A is turned off. The horizontal axis corresponds to the pixel position of the image sensor 106C, and the vertical axis represents the minimum bit. When external light L1 is incident, the entire document reading glass 11B becomes the light entrance, as explained in Fig. 4. Therefore, the black data OUT1 shown by the thick line becomes uniformly high from the back side to the front side of the image sensor 106C (see Fig. 3). Note that the black data OUT1 shown by the dashed line represents the output value when there is no effect of external light.

[0026] On the other hand, when external light L2 is incident, only the front end of document glass 11A or document reading glass 11B becomes the incident port, as explained in Fig. 4. Therefore, black data OUT1 indicated by a thick line becomes high near the front side of image sensor 106C (see Fig. 3). Note that external light L2 does not reach the rear side, so black data OUT1 near the rear side becomes approximately the same as the output value when there is no effect of external light. Hereinafter, the output value indicated by the dashed line will be referred to as the reference value of the black data OUT. The reference value is data at the time of shipment from the factory, at the time of installation of the image forming apparatus 1, or at a time of execution when the presence of external light is not detected, and is written in, for example, the ROM 102 (see FIG. 2) or the RAM 103 (see FIG. 2), etc.

[0027] <Black correction> The image forming apparatus 1 is provided with a function (hereinafter, referred to as "black correction") for correcting the black level of the image sensor 106C so that it falls within a normal range. The black correction is called AOC (=Auto Offset Control), and is executed, for example, when the power is turned on or when returning from a power saving state. However, there is an upper limit to the amount of adjustment of the output value OUT by the AOC. For this reason, the output value after correction by the AOC may not fall within the normal range. In this case, the image reading unit 106 may be determined to be broken even though it is normal.

[0028] <Processing Operation> 6 is a flow chart for explaining the processing operation employed in embodiment 1. Note that the symbol S in the figure means a step. The processing operation shown in FIG. 6 is started when the processor 101 (see FIG. 2) detects that the power switch 14 (see FIG. 1) has been turned on, or when the processor 101 (see FIG. 2) detects a return from a power saving state.

[0029] <Processing when power is turned on> First, the processor 101 adjusts the offset amount of the black data OUT of the image sensor 106C (see FIG. 3) (step 101). That is, AOC is executed. The AOC here is executed at the position of the strip-shaped member 11C1 (see FIG. 3). Next, the processor 101 detects the presence or absence of external light entering the housing from the black data OUT acquired during execution of step 101 (step 102). For example, when the processor 101 finds a pixel where the difference between the black data OUT and a reference value exceeds a threshold, it determines that external light entering the housing has been detected.

[0030] However, in order to avoid false detection due to individual differences or abnormal values ​​in the image reading unit 106 (see FIG. 2), the image sensor 106C may be divided into multiple sections in the Y-axis direction, and the presence or absence of external light entering the housing may be determined based on the difference between the average value of the black data OUT for each section and a reference value. If no external light is detected, a negative result is obtained in step 102. In this case, the processor 101 obtains data for black shading (step 103). Specifically, the black data after AOC is obtained as data for black shading. On the other hand, if external light is detected, a positive result is obtained in step 102. In this case, processor 101 performs predictive correction on the stored data (step 104).

[0031] Fig. 7 is a diagram for explaining predictive correction, in which parts corresponding to those in Fig. 5 are denoted by the same reference numerals. In Fig. 7, it is assumed that external light L2 is incident. In Fig. 7, black data OUT2 before and after predictive correction is shown by a thick line. The upper diagram in Fig. 7 shows black data OUT2 before predictive correction, and the lower diagram shows black data OUT2 after predictive correction.

[0032] In the upper diagram of FIG. 7, the black data OUT2 on the front side is larger than the reference value. Therefore, it is determined that external light L2 (see FIG. 4) is incident on the housing from the front side. In this case, the processor 101 replaces the black data OUT2 that is larger than the reference value with the reference value. In FIG. 7, the target portion of the predictive correction is indicated by a dashed line. When external light L1 (see FIG. 4) enters the housing from the side, the processor 101 replaces all of the black data OUT1 with a reference value during predictive correction.

[0033] Returning to the explanation of Figure 6. After executing step 103 or step 104, the processor 101 automatically adjusts the white gain (step 105). That is, AGC (=Auto Gain Control) is executed. Specifically, the gain is adjusted based on the output value output from the image sensor 106C (see FIG. 3) with the light source 106A (see FIG. 3) turned on. Next, the processor 101 acquires data for white shading (step 106). Specifically, the output value after the gain adjustment is acquired as the data for white shading. This completes the initial processing associated with turning on the power, etc.

[0034] <Processing when scanning a document> The processing operations executed each time a document is read will be described below. First, the processor 101 determines whether or not a person has been detected in front of the operation panel 12 (see FIG. 1) (step 107). For this determination, an output signal of the human presence sensor 19 (see FIG. 1) is used. If no person is detected, a negative result is obtained in step 107. In this case, there is no possibility that a person will be reading the document. Therefore, the processor 101 repeats the determination in step 107.

[0035] On the other hand, if a person is detected, a positive result is obtained in step 107. In this case, the processor 101 goes into an operation waiting (standby) state (step 108). At this time, the image reading unit 106 is located below the belt-shaped member 11C1. Next, the processor 101 determines whether or not the incidence of external light from the left side surface was detected in the determination of step 102 (step 109). In this determination, for example, the black data OUT after AOC in step 101 is referenced.

[0036] For example, if the incidence of external light L1 (see FIG. 4) is detected, a positive result is obtained in step 109. In this case, the processor 101 performs predictive correction using the stored data (step 110). The predictive correction performed in step 110 is the same as the predictive correction performed in step 104. In the predictive correction in step 110, the black data OUT1 corresponding to all pixels of the image sensor 106C (see FIG. 3) is replaced with a reference value.

[0037] On the other hand, if external light from the side is not detected, a negative result is obtained in step 109. For example, if a negative result is obtained in step 102, a negative result is also obtained in step 109. Even if the incidence of external light L2 (see FIG. 4) is detected in step 102, a negative result is obtained in step 109. The reason is that at the time of this determination (i.e., in the standby state), a person is present in front of operation panel 12, blocking the incidence of external light L2 into the housing.

[0038] Fig. 8 is a diagram for explaining the blocking of external light L2 by a person. In Fig. 8, parts corresponding to those in Fig. 4 are denoted by the same reference numerals. 8, the external light L2 is blocked by a person operating the operation panel 12. For this reason, it can be considered that no external light L2 is entering the housing.

[0039] Returning to the explanation of Figure 6. After a negative result is obtained in step 109, or after execution of step 110, when a request to start reading the document is received (step 111), processor 101 executes black shading (step 112) and white shading (step 113) to read the document image (step 114). When reading of the document image is completed, the processor 101 returns to step 108 to prepare for the next reading.

[0040] <Summary> The image forming apparatus 1 (see FIG. 1) described above has an apparatus main body 10 (see FIG. 1), an original conveying unit 20 (see FIG. 1) that is opened and closed by a hinge provided on the rear side of the apparatus main body 10, a light source 106A (see FIG. 3) that illuminates an original, an image sensor 106C (see FIG. 3) that reads the image of the original, and a processor 101 (see FIG. 2). For this reason, there are two paths through which external light can enter that affect the correction of the black data OUT. Specifically, there are two paths: one on the left side when facing the front of the device, and one on the front side of the device.

[0041] In this embodiment, if the incidence of external light is detected in the determination of step 102, the processor 101 corrects the black level of the image sensor 106C using a normal value (i.e., an output value not affected by external light) stored at the time of shipment from the factory, regardless of the direction of incidence of the external light. If it is determined in step 102 that incidence of external light is not detected, the processor 101 uses the result of the black level correction executed in step 101 as is.

[0042] In addition, after the power is turned on, if the judgment in step 102 detects that external light L1 is incident from the left side, the black level of the image sensor 106C is corrected using a normal value (i.e., an output value not affected by external light) stored at the time of shipment from the factory, etc. After the power is turned on, even if it is determined in step 102 that external light L2 is incident from the front side, the correction result of the black level of the image sensor 106C performed in step 101 is used as is. Incidentally, if no person is detected in step 107, the processor 101 does not execute the black level correction process according to the direction of incidence of external light. In this manner, in the case of the image forming apparatus 1 described in the present embodiment, a black level correction technique that places fewer restrictions on the image sensor 106C is realized.

[0043] <Embodiment 2> <Exterior and internal structure> In this embodiment, an image forming apparatus 1 having the external configuration shown in Fig. 1 is used. The internal configuration of the image forming apparatus 1 is also basically the same as the internal configuration described with reference to Fig. 2. Fig. 9 is a cutaway view showing the vicinity of the document table 11 of the device body 10 used in the embodiment 2. In Fig. 9, parts corresponding to those in Fig. 3 are denoted by the same reference numerals. In the case of the document table 11 shown in FIG. 9, in addition to being attached below the belt-shaped member 11C1, a white reference plate 11D2 is also attached below the belt-shaped member 11C2. Therefore, in this embodiment, black correction is possible at either position on belt-shaped member 11C1 or belt-shaped member 11C2.

[0044] <Processing Operation> Fig. 10 is a flow chart for explaining the processing operation employed in the embodiment 2. In Fig. 10, parts corresponding to those in Fig. 6 are denoted by the same reference numerals. The processing operation shown in FIG. 10 is started when the processor 101 (see FIG. 2) detects that the power switch 14 (see FIG. 1) has been turned on, or when the processor 101 (see FIG. 2) detects a return from a power saving state.

[0045] <Processing when power is turned on> First, the processor 101 adjusts the offset amount of the black data, which is the output value of the image sensor 106C (step 101). That is, the AOC is executed. The AOC here is executed at the position of the strip-shaped member 11C1 (see FIG. 3). Next, the processor 101 detects the presence or absence of external light entering the housing from the black data OUT acquired during execution of step 101 (step 102). For example, when the processor 101 finds a pixel where the difference between the black data OUT and a reference value exceeds a threshold, it determines that external light entering the housing has been detected.

[0046] If no external light is detected, a negative result is obtained in step 102. In this case, the processor 101 obtains data for black shading (step 103). On the other hand, if external light is detected, a positive result is obtained in step 102. In this case, processor 101 determines whether external light L2 is from the front (step 121). If only the output value from the pixel position on the front side of image sensor 106C is greater than the reference value, it is found that the external light entering the housing is external light L2 from the front side. On the other hand, if the output values ​​from all pixel positions of image sensor 106C are greater than the reference value, it is found that the external light entering the housing is external light L1 from the side.

[0047] If it is determined that the external light L2 is incident from the front side, a positive result is obtained in step 121. In this case, the processor 101 sets the external light flag to ON (step 122). Next, the processor 101 performs predictive correction using the stored data (step 104). As described above, data that is greater than the reference value among the output values ​​of the image sensor 106C is replaced with the stored data.

[0048] On the other hand, if it is determined that the external light L1 is incident from the side, a negative result is obtained in step 121. In this case, the processor 101 moves the image reading unit 106 to the left end inside the housing (step 123). Fig. 11 is a diagram for explaining the movement of the image reading unit 106 to the left end within the housing. In Fig. 11, the same reference numerals are used to denote parts corresponding to those in Figs. 3 and 9. 11 shows the state of platen 11 when incidence of external light is detected in step 102. For this reason, image reading unit 106 is located below belt-shaped member 11C1.

[0049] 11 shows a state in which the external light entering the housing is determined to be external light L1 in step 121, and image reading unit 106 is moved to the left end of the housing. As shown in the lower diagram, image reading unit 106 is positioned further to the left of document reading glass 11B, which is the entrance for external light L1. That is, the opening of imaging lens 106B constituting image reading unit 106 is located further left than the left end of document reading glass 11B. Therefore, even if external light L1 enters the housing, the external light L1 does not affect image sensor 106C.

[0050] Returning to the explanation of Figure 10. When the image reading unit 106 moves to the left end inside the housing, the processor 101 executes the AOC (step 124). Next, the processor 101 obtains data for black shading (step 103). After executing step 103 or after executing step 104, the processor 101 automatically adjusts the white gain (step 105). That is, AGC (=Auto Gain Control) is executed. Next, the processor 101 obtains data for white shading (step 106). This completes the initial processing associated with turning on the power.

[0051] <Processing when scanning a document> The processing operations executed each time a document is read will be described below. First, processor 101 determines whether or not a person operating operation panel 12 (see FIG. 1) has been detected (step 107). If no person is detected, a negative result is obtained in step 107. In this case, the document is not read by a person. Therefore, the processor 101 repeats the determination in step 107.

[0052] On the other hand, if a person is detected, a positive result is obtained in step 107. In this case, the processor 101 goes into an operation waiting (standby) state (step 108). At this time, the image reading unit 106 is positioned below the belt-shaped member 11C1. Next, the processor 101 determines whether the external light flag is on (step 125). If the external light detected in step 102 is external light L2 from the front side, a positive result is obtained in step 125. In this case, the processor 101 executes AOC again (step 126), obtains data for black shading (step 127), executes AGC (step 128), and obtains data for white shading (step 129).

[0053] On the other hand, if external light has not been detected in step 102, or if the external light detected in step 102 is external light L2 from the side, a negative result is obtained in step 125. In this case, or after execution of step 129, when processor 101 receives a command to start reading the document (step 111), processor 101 performs black shading (step 112) and white shading (step 113) to read the document image (step 114). When reading of the document image is completed, the processor 101 returns to step 108 to prepare for the next reading.

[0054] <Summary> The image forming apparatus 1 (see FIG. 1) used in this embodiment is also the same as that in the first embodiment. For this reason, there are two paths through which external light can enter that affect the correction of the black data OUT. Specifically, there are two paths: one on the left side when facing the front of the device, and one on the front side of the device. However, in the case of the image forming apparatus 1 used in this embodiment, a white reference plate 11D2 is attached to the left end inside the housing when viewed from the front side.

[0055] In this embodiment, when the incidence of external light L1 is detected in the determination of step 121, the processor 101 moves the image reading unit 106 from a first position (i.e., the position of the strip-shaped member 11C1) for starting reading of a document in a stationary state in a direction opposite to the reading direction (i.e., toward the left end inside the housing). Then, when the image reading unit 106 moves to a second position (i.e., the position of the strip-shaped member 11C2) where the entire light receiving surface of the image sensor 106C is hidden by the housing, the processor 101 corrects the black level of the image sensor 106C again.

[0056] On the other hand, if the incidence of external light L2 is detected in the determination of step 121, the processor 101 corrects the black level of the image sensor 106C using a normal value (i.e., an output value not affected by external light) stored at the time of shipment from the factory or the like. If it is determined in step 102 that incidence of external light is not detected, the processor 101 uses the result of the black level correction executed in step 101 as is. As a result, a black level correction technique that places fewer restrictions on the image sensor 106C is realized.

[0057] <Embodiment 3> <Exterior and internal structure> In this embodiment, an image forming apparatus 1 having the external configuration shown in Fig. 1 is used. The internal configuration of the image forming apparatus 1 is also basically the same as the internal configuration described with reference to Fig. 2. In the present embodiment, as in the second embodiment, a white reference plate 11D2 is also attached below the belt-shaped member 11C2.

[0058] <Processing Operation> Fig. 12 is a flow chart for explaining the processing operation employed in the embodiment 3. In Fig. 12, parts corresponding to those in Fig. 10 are denoted by the same reference numerals. The processing operation shown in FIG. 12 is started when the processor 101 (see FIG. 2) detects that the power switch 14 (see FIG. 1) has been turned on, or when the processor 101 (see FIG. 2) detects a return from a power saving state.

[0059] First, the processor 101 adjusts the offset amount of the black data, which is the output value of the image sensor 106C (step 101). That is, the AOC is executed. The AOC here is executed at the position of the strip-shaped member 11C1 (see FIG. 3). Next, the processor 101 detects the presence or absence of external light entering the housing from the black data OUT acquired during execution of step 101 (step 102). For example, when the processor 101 finds a pixel where the difference between the black data OUT and a reference value exceeds a threshold, it determines that external light entering the housing has been detected.

[0060] If no external light is detected, a negative result is obtained in step 102. In this case, the processor 101 obtains data for black shading (step 103). On the other hand, if external light is detected, a positive result is obtained in step 102. In this case, the processor 101 moves the image reading unit 106 to the left end in the housing (step 123). In this embodiment, regardless of whether the external light is incident from the front side or the side side, the image reading unit 106 is uniformly moved to the left end in the housing.

[0061] Next, the processor 101 executes the AOC (step 131). The AOC here is executed at the position of the strip-shaped member 11C2 (see FIG. 9). After executing the AOC, the processor 101 determines whether or not external light has been detected again (step 132). If the external light detected in step 102 is external light L1 from the side, a negative result is obtained in step 132. In this case, the processor 101 proceeds to step 103 and obtains data for black shading. However, the data is the data obtained in step 131.

[0062] On the other hand, if the external light detected in step 102 is the external light L2 from the front side, a positive result is obtained in step 132 . Although external light L1 does not directly enter the leftmost position inside the housing, since the presence of a person in front of the operation panel 12 has not been confirmed at this stage, external light L2 entering through the document reading glass 11B may affect the black level. In this case, the processor 101 sets the external light flag to ON (step 122). The processor 101 also executes predictive correction using the stored output data (step 104).

[0063] When step 103 or step 104 is executed, the processor 101 automatically adjusts the white gain (step 105). That is, AGC (=Auto Gain Control) is executed. Next, the processor 101 obtains data for white shading (step 106). This completes the initial processing associated with turning on the power.

[0064] <Processing when scanning a document> The processing operations executed each time a document is read will be described below. First, processor 101 determines whether or not a person operating operation panel 12 (see FIG. 1) has been detected (step 107). If no person is detected, a negative result is obtained in step 107. In this case, the document is not read by a person. Therefore, the processor 101 repeats the determination in step 107.

[0065] On the other hand, if a person is detected, a positive result is obtained in step 107. In this case, the processor 101 goes into an operation waiting (standby) state (step 108). At this time, the image reading unit 106 is positioned below the belt-shaped member 11C1. Next, the processor 101 determines whether the external light flag is on (step 125). If the external light detected in step 102 is the external light L2 from the front side, a positive result is obtained in step 125. The subsequent processing operations are the same as those in the second embodiment, and therefore will not be described.

[0066] <Summary> The image forming apparatus 1 (see FIG. 1) used in this embodiment is also the same as that in the second embodiment. For this reason, there are two paths through which external light can enter that affect the correction of the black data OUT. Specifically, there are two paths: one on the left side when facing the front of the device, and one on the front side of the device. Moreover, the image forming apparatus 1 used in this embodiment also has a white reference plate 11D2 attached to the left end inside the housing when viewed from the front side.

[0067] In this embodiment, when the incidence of external light is detected in the determination of step 102, processor 101 moves image reading unit 106 from a first position (i.e., the position of strip-shaped member 11C1) for starting reading of a stationary document in a direction opposite to the reading direction (i.e., toward the left end inside the housing). Then, when image reading unit 106 moves to a second position (i.e., the position of strip-shaped member 11C2) where the entire light receiving surface of image sensor 106C is hidden by the housing, processor 101 corrects the black level of image sensor 106C again.

[0068] If incidence of external light is also detected at the second position, the processor 101 corrects the black level of the image sensor 106C using a normal value (i.e., an output value not affected by external light) stored at the time of shipment from the factory or the like. It should be noted that if the incidence of external light is not detected, the processor 101 uses the result of the black level correction executed in step 101 as is. In this manner, in the present embodiment, a black level correction technique that places fewer restrictions on image sensor 106C than in the second embodiment is realized.

[0069] <Other embodiments> (1) Although the embodiment of the present invention has been described above, the technical scope of the present invention is not limited to the scope of the above-mentioned embodiment. It is clear from the claims that the technical scope of the present invention also includes various modifications and improvements to the above-mentioned embodiment.

[0070] (2) In the above embodiment, the image forming device 1 is described as being used in an office, but the image forming device may be a home image forming device capable of reading an image of a stationary document and an image of a document transported by a document transport mechanism, or a scanner capable of reading an image of a stationary document and an image of a document transported by a document transport mechanism.

[0071] (3) In the above embodiment, a CIS type sensor is used as the image reading unit 106, but a CCD (=Charge Coupled Device) type sensor may also be used.

[0072] (4) The processor in the above-described embodiments refers to a processor in a broad sense, and includes general-purpose processors (e.g., CPU (=Central Processing Unit)) as well as dedicated processors (e.g., GPU (=Graphical Processing Unit), ASIC (=Application Specific Integrated Circuit), FPGA (=Field Programmable Gate Array), programmable logic devices, etc.). In addition, the operations of the processor in each of the above-mentioned embodiments may be executed by one processor alone, or may be executed by multiple processors located at physically separate locations in cooperation with each other. Furthermore, the order of execution of each operation in the processor is not limited to the order described in each of the above-mentioned embodiments, and may be changed individually.

[0073] (5) In the above-described embodiment, the processor 101 constituting the image forming apparatus 1 executes the black correction by itself, but the black correction may be executed in cooperation with a processor of another terminal with which the image forming apparatus 1 can communicate via a network, etc. In other words, the above-described processing operation may be realized by cooperation between a plurality of processors.

[0074] <Additional Notes> (((1))) An information processing system comprising a light source that illuminates an original document, an image sensor that reads an image of the original document, and one or more processors, wherein when incidence of external light is detected from output data of the image sensor, the one or more processors move the image sensor from a first position for starting reading of a stationary original document in a direction opposite to the reading direction, and correct the black level of the image sensor at a second position where the entire light receiving surface of the image sensor is hidden by a housing. (((2))) The information processing system according to (((1))), wherein the second position is located farther away than a reading position for reading an image from a transported document. (((3))) The information processing system according to (((1))) or (((2))), wherein the one or more processors detect the presence or absence of external light from the output of the image sensor when a main power supply is turned on or when a return from a power saving state is detected. (((4))) The information processing system of any one of (((1))) to (((3))), wherein, when the presence of external light is detected at the second position, the one or more processors correct the black level using output data detected and stored by the image sensor in the absence of external light. (((5))) The information processing system described in (((4))), wherein the output data detected and stored by the image sensor in the absence of external light is data at the time of shipment, at the time of setup, or at an execution time when the presence of external light is not detected. (((6))) The information processing system of any one of (((1))) to (((5))), wherein the one or more processors correct the black level using the output data of the image sensor at the first position when a human presence sensor detects the presence of a person in front of the operation panel, even if external light is detected at the second position. (((7))) The information processing system described in (((6))), wherein the one or more processors do not perform black level correction when the presence of external light is detected even at the second position and the human presence sensor does not detect the presence of a person in front of the operation panel. (((8))) A program for enabling a computer to implement the following functions: when the presence of external light is detected from the output data of an image sensor that reads an image of a document, the computer moves the image sensor from a first position for starting to read the image of the document in a stationary state in a direction opposite to the reading direction of the document; and when the computer detects the presence of external light from the output data of the image sensor that reads an image of the document, the computer corrects the black level of the image sensor at a second position where the entire light receiving surface of the image sensor is hidden by the housing.

[0075] According to the information processing system of (((1))), it is possible to realize a black level correction technique that places fewer constraints on the image sensor, compared to a black level correction technique that requires that there be positions on the image sensor where the effects of external light are unlikely to appear and positions where the effects of external light are likely to appear. According to the information processing system of (((2))), it is possible to correct the black level at a position where the incident direction of external light is restricted. According to the information processing system of (((3))), it is possible to increase the opportunities for correcting the black level. According to the information processing system of (((4))), it is possible to use the normal black level that is actually detected by the image sensor at the position where the external light is incident. According to the information processing system of (((5))), it is possible to use the normal black level that is actually detected by the image sensor at the position where the external light is incident. According to the information processing system of (((6))), the black level can be corrected without being affected by external light. According to the information processing system of (((7))), the black level correction can be stopped until the influence of external light is eliminated. According to the program of (((8))), it is possible to realize a black level correction technique that places fewer constraints on the image sensor, compared to a black level correction technique that requires that there be positions on the image sensor where the effects of external light are unlikely to appear and positions where the effects of external light are likely to appear. [Explanation of symbols]

[0076] 1...image forming apparatus, 10...apparatus main body, 11...original table, 11A...original glass, original reading 11B...glass, 12...operation panel, 19...human sensor, 20...original transport unit, 100...control unit, 101...processor, 102...ROM, 103...RAM, 104...main memory device, 105...operation panel section, 106...image reading section, 106A...light source, 106B...imaging lens, 106C...image sensor, 106D...stage, 107...image processing section, 108...image forming section, 109...communication section, 110...signal line, 11D1, 11D2...white reference plate

Claims

1. A light source for illuminating a document, an image sensor for reading an image of the document, and one or more processors; The one or more processors: When the incidence of external light is detected from the output data of the image sensor, moving the image sensor in a direction opposite to a reading direction from a first position for starting reading of a stationary document; correcting a black level of the image sensor at a second position where the entire light receiving surface of the image sensor is hidden by a housing; Information processing system.

2. the second position is located farther away than a reading position for reading an image from a transported document; The information processing system according to claim 1 .

3. The one or more processors: when it is detected that a main power source is turned on, or when it is detected that the device has returned from a power saving state, the presence or absence of external light is detected from the output of the image sensor.

3. The information processing system according to claim 1 or 2.

4. The one or more processors: If the presence of external light is also detected at the second location, correcting the black level based on the output data detected and stored by the image sensor in the absence of external light; The information processing system according to claim 1 .

5. The output data detected and stored by the image sensor in the absence of external light is data at the time of shipment, at the time of setup, or at a time of execution in which the presence of external light is not detected.

5. The information processing system according to claim 4.

6. The one or more processors: Even if the presence of external light is detected at the second position, when the human presence sensor detects the presence of a person in front of the operation panel, the black level is corrected using the output data of the image sensor at the first position. The information processing system according to claim 1 .

7. The one or more processors: when the presence of external light is detected even at the second position, if the human presence sensor does not detect the presence of a person in front of the operation panel, correction of the black level is not executed.

7. The information processing system according to claim 6.

8. On the computer, a function of moving the image sensor in a direction opposite to a reading direction of the document from a first position for starting reading the image of the document in a stationary state when the presence of external light is detected from output data of the image sensor that reads the image of the document; a function of correcting a black level of the image sensor at a second position where the entire light receiving surface of the image sensor is hidden by a housing; A program to achieve this.

Images