Reading device and image forming device

Abstract

To accurately correct a read image even if a background is black.SOLUTION: A reading device reading a recording medium comprises: a background unit that is to be a background when reading the recording medium; a reading unit that generates a reading value through the reading with the background unit as the background; and a correction unit that corrects the reading value. The background unit has a first area that is black and a second area that is an area different from the first area. The correction unit corrects the reading value based on a reference value generated by the reading unit reading the second area.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reading device and an image forming device. [Background technology]

[0002] When reading an image, a light source such as a lamp may be used. In such a case, fluctuations in the amount of light from the lamp may cause so-called uneven density.

[0003] Therefore, in order to prevent uneven density, the image reading device first reads the color of the reference roller using an image sensor and generates correction (shading) data. The image reading device then corrects the read image signal using the correction data. In this way, a technology is known that corrects the read data in real time to prevent uneven density caused by fluctuations in the amount of light (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, the background is made white with a roller or the like to perform correction (shading). Then, the conventional technology reads the white roller to generate correction data. In this case, for example, if the purpose is to detect the outline of a sheet of paper, if the background is made black, there is a problem that the correction cannot be performed with high accuracy.

[0005] An object of the present invention is to provide a reading device and the like that can correct a read image with high accuracy even when an image is read with a black background. [Means for solving the problem]

[0006] In order to solve the above problem, one aspect of the present invention is a reading device for reading a recording medium, comprising: a background portion that serves as a background when the recording medium is read; a reading unit that generates a read value by reading the background portion; a correction unit that corrects the read value, The background portion is a first region that is black; a second region that is different from the first region, The correction unit is The reading unit reads the second area and generates a reference value, and corrects the second area based on the reference value. It is characterized by: Effect of the Invention

[0007] According to the present invention, even if the background is black, the read image can be corrected with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating an example of the configuration of a reading device 10. [Diagram 2] 2 is a diagram showing an example of an image read by a line sensor 12. FIG. [Diagram 3] FIG. 13 is a diagram illustrating an example of a case where a thermal effect occurs in lighting. [Figure 4] FIG. 13 is a diagram showing an example of the distribution of thermal effects with respect to positions. [Diagram 5] FIG. 11 is a diagram illustrating a first example of correlation and correction (edge ​​correction). [Figure 6] FIG. 13 is a diagram illustrating a second example of correlation and correction (edge ​​correction). [Figure 7] FIG. 13 is a diagram showing an example of periodic correction (edge ​​correction). [Figure 8] FIG. 11 is a diagram illustrating a first example of the overall processing. [Figure 9] FIG. 11 is a diagram illustrating a second example of the overall processing. [Figure 10] FIG. 13 is a diagram showing a first example of correction performed on a divided region. [Figure 11] FIG. 13 is a diagram showing a second example of correction performed on a divided region. [Figure 12] FIG. 1 illustrates an example of the configuration of an image forming apparatus. [Figure 13] FIG. 2 illustrates an example of a functional configuration of an image forming apparatus. [Figure 14] FIG. 13 is a diagram showing a first modified example. [Figure 15] FIG. 1 is a diagram showing a reading device 10 to which a first modified example is applied. [Figure 16] FIG. 13 is a diagram showing a second modified example. [Figure 17] FIG. 13 is a diagram showing a third modified example. [Figure 18] FIG. 1 illustrates a first example of a hardware configuration. [Figure 19] FIG. 2 is a diagram showing a second example of a hardware configuration. [Figure 20] FIG. 3 is a diagram showing a hardware configuration example (part 3). [Figure 21] FIG. 15 is a diagram showing a configuration example in which a white board is added to the configuration shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, specific examples will be described with reference to the accompanying drawings. Note that the embodiment is not limited to the examples shown in the drawings and the specific examples described below.

[0010] [First embodiment] For example, the reading device 10 is a device having the following hardware configuration.

[0011] [Example of a reading device] FIG. 1 is a diagram showing an example of the configuration of a reading device 10. The following description will be given using an example in which the recording medium is paper 100. The paper 100 is transported from right to left in the figure. Specifically, the direction in which the paper 100 is transported (hereinafter simply referred to as the "transport direction") is the direction indicated by the arrow. In the following description, the transport direction may also be referred to as the "Y direction". On the other hand, the transport direction, i.e., the direction perpendicular to the surface of the paper 100 (the up-down direction in the figure), may also be referred to as the "Z direction".

[0012] The reading device 10 is a device having a hardware configuration including, for example, a roller 11, a line sensor 12, and a control device 13. The hardware configuration is not limited to the example described above. For example, it is preferable that the reading device has a hardware configuration further including an illumination device serving as a light source such as a lamp or an LED (light emitting diode).

[0013] Furthermore, the reading device 10 is connected to, for example, a transport sensor 20 or the like. Specifically, the transport sensor 20 is installed upstream of the reading device 10 on the transport path (on the right side in the figure). The transport sensor 20 detects the presence or absence of the paper 100. Next, the transport sensor 20 transmits the detection result to the reading device 10. Therefore, based on the detection result by the transport sensor 20, the reading device 10 can determine the presence or absence of the paper 100 and that the paper 100 is being transported. In this way, the reading device 10 may be configured to be connected to peripheral devices such as the transport sensor 20.

[0014] The line sensor 12 is an optical sensor, etc. Therefore, when the line sensor 12 performs reading, the reading device 10 obtains a reading result, such as a read value.

[0015] The control device 13 is, for example, a calculation device, a storage device, an input / output device, etc. The control device 13 may be an external device of the reading device 10, etc. Therefore, the control device 13 processes or stores the reading result by the line sensor 12. The control device 13 may also control and drive the switching of the rollers 11. The rollers 11 may be switched by control of a device other than the control device 13 or by operation by a user, etc.

[0016] The roller 11 is formed, for example, by combining a white member (hereinafter referred to as "white member 11W") and a black member (hereinafter referred to as "black member 11B"). For example, the control device 13 controls the roller 11 so that the black member 11B is positioned directly under the line sensor 12 as shown in the figure. With this control, the background becomes black when the paper 100 is read. Therefore, reading is performed in this state, and image data showing a read image with a black background can be generated.

[0017] On the other hand, the control device 13 switches the white member 11W so that it is located directly under the line sensor 12. When the paper 100 is read, the background becomes white. and generate image data showing the scanned image with a white background.

[0018] The background portion has, for example, the following configuration.

[0019] FIG. 2 is a diagram showing an example of an image read by the line sensor 12. Hereinafter, an example will be described in which the paper 100 is white. When the paper 100 is white, the reading device 10 reads the black background (black member 11B) and the white background. On the other hand, as shown in FIG. 18 and other figures, the white background is disposed at both ends of the black member 11B in the X direction. Therefore, the outside of the paper 100 (the area shown as "first area 101" in the figure) is black, and the area other than the first area 101 (for example, the area shown as "second area 102" in the figure) is white. Therefore, the line sensor 12 reads both the white area at the end and the black area in the center. In this way, with the hardware configuration shown in FIG. 18, an image as shown in FIG. 2 can be read.

[0020] The first region 101 is, for example, a range through which the paper 100 passes. The range in which the line sensor 12 senses the reading target (hereinafter referred to as the "reading range") is set, for example, in advance. Then, when the image generated based on the reading result is read with the black member 11B as the background, the background of the image is black.

[0021] The second area 102 is, for example, both ends of the roller 11 (in the illustrated example, it is an area outside the first area 101 in the X direction). In other words, the second area 102 is an area through which the paper 100 does not pass. For example, as shown in FIG. 18, which is a configuration diagram seen from the Y direction in FIG. 1, the black member 11B (first area 101) is within the area FW through which the paper passes, and the second area 102 is outside the area FW through which the paper passes. In addition, the reading area RW includes the first area 101 and the second area 102.

[0022] It should be noted that second region 102 may be any region located away from first region 101, and may be, for example, either one of both ends.

[0023] Also, since the second region 102 is an area through which the paper 100 does not pass, it may be a member disposed outside the roller 11. For example, as shown in Fig. 19, the second region 102 may be provided in an area through which the paper 100 does not pass on both ends of a conveyance guide 300 that guides the paper 100. Also, as shown in Fig. 20, the second region 102 may be formed of a member separate from the conveyance guide 300.

[0024] As described above, the line sensor 12 may simultaneously read an area including both the first area 101 and the second area 102, or the line sensor 12 may read the area in a plurality of separate readings.

[0025] For example, if the paper 100 is white and it is desired to grasp the outer shape of the paper 100, the control device 13 switches the roller 11 so that the background becomes black, and the black member 11B is positioned as shown in Fig. 1. In this way, with the objective of grasping the outer shape with high accuracy and with a configuration in which the background can be switched according to the type of recording medium, the reading device 10 can grasp the outer shape of the recording medium with high accuracy.

[0026] The reading device 10 may adjust the height (position in the Z direction) of the second region 102. For example, the reading device 10 adjusts the height of the second region 102 so that it is the same height as the height of the recording medium.

[0027] Depending on the height, the reading result by the reading device 10 may change due to the influence of brightness. Therefore, if correction (edge ​​correction) is performed by adjusting the height of the second region 102 to the same height as the recording medium to be read, the correction can be performed with high accuracy.

[0028] In addition, when the paper 100 is white and it is desired to reduce so-called "offset," the control device 13 switches the rollers 11 so that the background becomes black. In this way, with the objective of preventing "offset" and a configuration in which the background can be switched depending on the type of recording medium, "offset" can be reduced and high-quality images can be easily read.

[0029] The reading device 10 performs reading and generates read values ​​indicating the amount of light, brightness, color, etc. Specifically, the read values ​​are in the format of RGB, YUV, etc. Therefore, the amount of light is converted from each RGB value, or is specified from the value indicated by the read value, such as "Y" in YUV (so-called brightness value). Image data, etc. are generated by collecting such read values ​​generated for each pixel.

[0030] When performing correction (edge ​​correction), the reader 10 reads a part of the second region 102 in advance to generate a reference value. Note that the reference value is preferably a value obtained by reading a plurality of positions in the second region 102 and performing statistical processing such as averaging the plurality of read values.

[0031] For example, the line sensor 12 is a mechanism that moves in the X direction when reading the paper 100 and when generating a reference value. For example, the line sensor 12 is a mechanism that moves in the X direction according to the purpose by an actuator such as a motor.

[0032] On the other hand, the line sensor 12 may be installed at a position where it can read both the first area 101 and the second area 102, or may have a sensing range where it can read both areas. In such a case, the line sensor 12 does not physically move in the X direction, and it is possible to determine where the line sensor 12 senses when reading the paper 100 and when generating the reference value. The settings are made in advance so that the following functions are used appropriately.

[0033] [Example of heat effect correction (edge ​​correction)] The reader 10 compensates for the following thermal effects, for example.

[0034] 3 is a diagram showing an example of a case where the influence of heat in lighting occurs. For example, the reading device 10 uses a lighting device or the like to ensure brightness for the paper 100 that is the subject of reading, thereby stabilizing the environment in which reading is performed. In such a case, the following influences may occur due to heat.

[0035] In the figure, the horizontal axis represents "time" (for example, in units of seconds (s)) and the vertical axis represents "level" (the amount of light measured as a reading, for example, in units of dimensionless). Therefore, the further to the right the figure shows, the more time has passed.

[0036] First, the read value ("level" in the figure) is ideally not affected by heat. Therefore, even over time, the read value remains almost constant, as shown by the dashed line in the figure (hereinafter referred to as "ideal state 201"). Note that ideal state 201 is premised on no change in lighting conditions, subject, etc. In other words, the amount of light ideally maintains a constant value regardless of the passage of time, as in ideal state 201.

[0037] On the other hand, when there is an influence of heat or the like, the amount of light may tend to be as shown in, for example, actual state 202 (shown by a solid line in the figure). Specifically, in actual state 202, the amount of light gradually decreases over time. In such actual state 202, even if the reading device 10 reads the same color in the same environment, it generates a reading value that is lower than the previous value due to the influence of heat.

[0038] When there is a variation in the amount of light due to such thermal effects, it is desirable to correct the readings, for example by "shading" or edge correction.

[0039] The line sensor 12 has reading values ​​for three colors, R, G, and B, and changes in the amount of light due to heat, etc., may differ for each color. Therefore, the following correction calculates a correction value for each of R, G, and B, and performs correction for each color.

[0040] First, the reading device 10 stores a reference value in advance. That is, the reading device 10 reads the second region 102 and stores the read value before the influence of heat occurs. Then, the reading device 10 reads the white member 11W and performs shading, thereby correcting unevenness in the main scanning direction (X direction). Since there is no influence of heat, the reference value is generated at this timing.

[0041] Here, to perform shading, it is necessary to switch the white member 11W. Therefore, if shading is performed between the previous and next sheets of paper for each sheet of paper, the interval between the previous and next sheets of paper will become longer due to the switching time of the white member 11W, and productivity will decrease. Therefore, the processing of the present invention is performed to reduce the frequency of performing shading while suppressing the invention of the reduction in light quantity due to heat.

[0042] Therefore, the correction (edge ​​correction) is performed when the amount of light is reduced due to the effect of heat after the reference value is generated. Alternatively, the correction (edge ​​correction) is performed when a certain amount of time has passed after the reference value is generated and the amount of light is reduced due to various effects. In this way, the read value that is the subject of the correction (edge ​​correction) is the read value that is generated after the effect of heat, etc. is generated.

[0043] Even if time passes, the second region 102 maintains the same color, so ideally, the read value is the same regardless of the passage of time. Therefore, for example, the reading device 10 performs correction (end correction) so that the read value stored as the reference value (i.e., the read value generated by reading the second region 102 before the passage of time) matches the current read value (i.e., the read value generated by reading the second region 102 after the passage of time).

[0044] Specifically, the correction (edge ​​correction) is performed using parameters (hereinafter referred to as "correction parameters") calculated as follows: First, the reading device 10 performs a calculation such as the following formula (1), for example. WB = (WBL + WBR) / 2 (1) In the above formula (1), "WB" is a reference value. As shown in the above formula (1), the reference value "WB" is obtained by, for example, adding two read values, "WBL" (hereinafter referred to as the "first preliminary read value") and "WBR" (hereinafter referred to as the "second preliminary read value"), and then dividing the result by "2", that is, calculating the average of the first preliminary read value "WBL" and the second preliminary read value "WBR". Therefore, when reading three or more points, the reference value "WB" is a value calculated by averaging the read values ​​of the three or more points.

[0045] In the above formula (1), the first preliminary read value "WBL" and the second preliminary read value "WBR" are read values ​​generated by reading the second region 102. Specifically, the first preliminary read value "WBL" is a read value read from the left end of the second region 102 shown in FIG. 2. On the other hand, the second preliminary read value "WBR" is a read value read from the right end of the second region 102 shown in FIG. 2. In this way, the reference value is calculated by statistically processing the read values ​​at both ends, such as by averaging them. Such reference values ​​are stored in advance.

[0046] On the other hand, after the effect of heat occurs in the actual state 202, i.e., after the amount of light has decreased, the read value is corrected (edge ​​correction) by a correction parameter calculated as in the following equation (2). P=WB / WA (2) In the above formula (2), "P" is a correction parameter. Specifically, when an area including both the first area 101 and the second area 102 is read simultaneously, the correction parameter "P" is used for correction (edge ​​correction) for the first area 101.

[0047] For example, in the second region 102, the read value before the decrease is "200", and after the light amount decreases, the read value is "190". In this case, "P=200 / 190" is calculated. The correction parameter "P" calculated in this way is used for correction (edge ​​correction) for the first region 101.

[0048] Moreover, "WA" (hereinafter referred to as "current average value") in the above formula (2) is calculated as follows. WA = (WAL + WAR) / 2 (3) As shown in the above formula (3), the current average value "WA" is a read value generated by reading the same color as in the above formula (1) after the thermal effect has occurred, i.e., at the time of correction (end correction), and is a value calculated by performing the same statistical processing.

[0049] Specifically, the current first read value "WAL" and the current second read value "WAR" are read values ​​generated by reading the second region 102 similar to the preliminary first read value "WBL" and the preliminary second read value "WBR" after the thermal effect occurs.

[0050] When the effect of heat occurs, there is a fluctuation as shown in Figure 3 before and after the effect occurs, so the current first read value "WAL" is lower than the preliminary first read value "WBL" even if the reading results are the same color. Similarly, the current second read value "WAR" is lower than the preliminary second read value "WBR".

[0051] Next, the reader 10 corrects the read value (edge ​​correction) by calculation such as the following equation (4) using the correction parameter "P" calculated by the above equation (2). R = RA × P (4) In the above formula (4), "R" is the value after the read value is corrected (end correction) (hereinafter referred to as "corrected value"). Meanwhile, "RA" is the read value to be corrected (end correction) (i.e., the read value generated under a condition where the value is low due to the influence of heat, and is the value before correction (end correction). Hereinafter referred to as "target read value").

[0052] The reference value "WB" calculated by the above formula (2) is the state before the light amount decreases, and is therefore greater than the current average value "WA" after the light amount decreases. Therefore, the correction parameter "P" becomes a value of "1" or more by the calculation of the above formula (2). Then, in the above formula (4), the reading device 10 calculates to multiply the target reading value "RA" by the correction parameter "P", which is a value of "1" or more. In this way, the correction parameter "P" is a value that becomes the gain in correction (edge ​​correction).

[0053] Therefore, in the above formula (4), the correction value "R" is calculated so as to increase the target read value "RA" whose value has decreased. By performing such a correction (end correction), the reading device 10 can correct (end correction) the thermal fluctuation as shown in FIG. 3 based on the correction parameters. Therefore, the reading device 10 can accurately correct (end correction) the read values, etc. In this way, when the read values ​​are accurately corrected (end correction), the read image can be accurately corrected (end correction).

[0054] The correction (edge ​​correction) may be performed at the stage when the reading device 10 reads, or may be performed in a process such as generating image data after reading. In addition, if dirt or the like occurs due to foreign matter such as paper powder or toner, it may be determined not to perform the correction (edge ​​correction).

[0055] For example, the occurrence of dirt is determined based on a preset setting such that a read value generated by reading the second region 102 is below a reference threshold value. The threshold value is stored in advance in a storage device.

[0056] Furthermore, when generating a correction value based on the read results from both sides, if one of the read values ​​is lower than the threshold value, the reading device 10 may determine that one side is dirty. In this case, the reading device 10 may perform correction (edge ​​correction) using only the read result from the side where no dirt has occurred.

[0057] [Example of correcting positional variations (edge ​​correction)] For example, the read value may have the following tendencies depending on the position where the reader 10 reads.

[0058] FIG. 4 is a diagram showing an example of the distribution of the thermal effect with respect to position. For example, the thermal effect is distributed as shown in the figure according to the position (horizontal axis in the figure). Hereinafter, the horizontal axis is "position" and the vertical axis is "level" (the vertical axis is the same as in FIG. 3). In the following example, "position" refers to, for example, a position in the main scanning direction (X direction in this example). For example, the position is indicated by the number of pixels (units are "dots" or the like) counted from one end of the first region 101 (hereinafter, the left end of the first region 101 in FIG. 2) as the origin. Therefore, the first end PS1 is the position that is the left end of the first region 101. On the other hand, the second end PS2 is the position that is the right end of the first region 101.

[0059] First, in an ideal state 201, there is no thermal effect, and the read value is therefore almost constant regardless of position or time, as shown by the dashed line in the figure (referred to as "ideal state 201" as in FIG. 3).

[0060] On the other hand, in reality, depending on the position, an effect such as position effect 302 in the figure may occur. Specifically, position effect 302 is an example of a case where the thermal effect occurs more significantly in center portion PS3 than in first end portion PS1 and second end portion PS2, which are the ends.

[0061] In particular, as time passes, the effects may not be uniform depending on the position, and variations may occur. For example, a lighting device is a hardware configuration in which multiple LEDs are arranged. In such lighting devices, the effects of heat may be uneven depending on the position due to the physical spacing at which the LEDs are mounted, the conditions for dissipating heat, etc.

[0062] For example, since the central portion PS3 is the central portion where reading is performed, it may be better for it to be brighter than the first end portion PS1 and the second end portion PS2, etc. In such a case, more LEDs may be arranged in the central portion PS3 than in the first end portion PS1 and the second end portion PS2. In such an arrangement, the central portion PS3 is more likely to be affected by heat over time. Therefore, the positional effect 302 may tend to occur disproportionately in certain parts depending on the position.

[0063] An example of the position effect 302 is a case where the amount of light at the center portion PS3 decreases with time compared to the first end portion PS1 and the second end portion PS2.

[0064] A tendency such as the position effect 302 depends on, for example, the layout of the LEDs in the lighting device, etc. Therefore, once the layout of the LEDs is determined, the correlation between the position of the reading and the fluctuation of the reading value with respect to the position can be estimated.

[0065] Based on the correlation estimated in this way, correction (edge ​​correction) is performed, for example, as shown in the following formula (5). Below, an example will be explained in which the reading of the Nth sheet ("N" is an arbitrary number) is corrected (edge ​​correction) using the first sheet (i.e., a state close to the initial state) as a reference. Note that this example is an example in which one sheet is targeted each time, and the "Nth" time is an example of the "Nth" sheet. R = RA × P2 (5) As in the above formula (4), in the above formula (5), "R" is a correction value. In this example, "R" indicates the value after correcting (edge ​​correction) the read value on the "N"th sheet.

[0066] In the above formula (5), "RA" is the target read value. In this example, "RA" is the read value on the "N"th sheet, and indicates the value before correction (edge ​​correction).

[0067] In the above formula (5), the correction parameter is "P2." As shown in the above formula (5), the correction (end correction) is realized by multiplying the target read value "RA" by the correction parameter "P2" according to the correlation.

[0068] The correction parameter "P2" is a value calculated, for example, according to the following formula (6). P2 = (R1 / RN) × PP (6) In the above formula (6), "R1" is, for example, the first sheet and is the read value of the ends such as the first end PS1 and the second end PS2 (hereinafter referred to as the "reference read value"). In other words, the reference read value "R1" is the value before the influence of heat occurs.

[0069] Furthermore, it is desirable for the reference reading value "R1" to be a value at a position that is less susceptible to the effects of heat, such as an end portion.

[0070] The following describes an example of performing correction (edge ​​correction) taking into account the position based on the reference read value "R1", but the correction (edge ​​correction) may be a value based on a read value at another position. For example, the reference read value "R1" is read and stored at a preset position, and is referred to when performing correction (edge ​​correction), etc.

[0071] Furthermore, the reference reading value "R1" may be an average value obtained by reading a number of positions.

[0072] In the above formula (6), "RN" is, for example, the "N"th sheet and is the read value of the ends such as the first end PS1 and the second end PS2 (hereinafter referred to as "affected read value").

[0073] The affected reading value "RN" is a reading value at the same position as the reference reading value "R1". On the other hand, the affected reading value "RN" is different from the reference reading value "R1" in that it targets the "N"th sheet.

[0074] 4, at the first end PS1, the reference read value "R1" is, for example, a value indicated by the ideal state 201. On the other hand, the affected read value "RN" is a value indicated by the positional effect 302. In this way, when there is a thermal effect, the light quantity is a lower value for the "Nth" sheet than for the first sheet, even at the same position.

[0075] In the above formula (6), "PP" indicates a coefficient (hereinafter referred to as "position correction coefficient") that corrects the influence of the reading position (edge ​​correction). For example, like the center part PS3 in Fig. 4, for a position that has a large thermal fluctuation compared to the edge (a reference position, which is a position read with the reference reading value "R1"), the position correction coefficient "PP" is set to a value larger than "1", such as "1.1".

[0076] In this way, the position correction coefficient "PP" is set according to the correlation between the position shown in Fig. 4 and the fluctuation of the read value relative to the position. Therefore, correction (end correction) using the position correction coefficient "PP" can be performed differently for each position. Therefore, the read value can be corrected (end correction) with high accuracy.

[0077] As shown in the above formula (6), the correction parameter "P2" is a value calculated by multiplying the position correction coefficient "PP". Therefore, the correction parameter "P2" is a value that reflects the correlation between the reading position and the fluctuation of the read value relative to the position.

[0078] Specifically, when the read value of the central PS3 (i.e., the target read value “RA” in the above equation (5)) is corrected (end correction) by multiplying it by the correction parameter “P2”, the value is corrected (end correction) to be larger because the position correction coefficient “PP” is a value such as “1.1”.

[0079] In this way, the correction parameter is preferably a value that reflects the correlation between the reading position and the fluctuation of the read value relative to the position. By using such a correction parameter that takes the position into consideration for correction (edge ​​correction), the reader 10 can perform correction (edge ​​correction) that takes into consideration the characteristics of the position for each position.

[0080] For example, the correlation is estimated as follows:

[0081] 5 is a diagram showing a first example of correlation and correction (end correction). Hereinafter, it is assumed that the correlation shows that the light amount tends to decrease more rapidly from the first end PS1 (e.g., the left end) to the second end PS2 (e.g., the right end).

[0082] In this example, correlation 401 is estimated, for example, assuming that it is linear. Specifically, correlation 401 shows a tendency to decrease with position (from left to right in this example). Thus, correlation 401 is an equation or the like that shows a tendency for the amount of light to decrease with position.

[0083] In the following description, a continuous case is taken as an example, but the numerical values ​​and calculations may be discrete.

[0084] For example, the light amount at the first end portion PS1 decreases by 0.5%. In contrast, the light amount at the second end portion PS2 decreases by 1.5%. In this way, it is considered that the light amount tends to decrease the farther away from the first end portion PS1 the light amount is.

[0085] In this case, for example, the correlation 401 is estimated by calculating a straight line connecting the read values ​​of the first end PS1 and the second end PS2. Specifically, the correlation 401 can be calculated by a method such as the least squares method.

[0086] When the correlation 401 is estimated, for example, the position correction coefficient "PP" is calculated as in the correction formula 402. For example, the correction formula 402 is calculated so as to have an opposite tendency to the correlation 401 in order to correct the influence of the position estimated by the correlation 401 (end correction).

[0087] Specifically, the correction formula 402 is calculated so that the value becomes higher as the position becomes farther from the first end portion PS1. Then, the position correction coefficient "PP" is set, for example, based on the correction formula 402. When such a position correction coefficient "PP" is used, when correction (end portion correction) is performed by the calculation of the above formula (5), the influence of position such as the correlation 401 can be corrected (end portion correction).

[0088] The reading device 10 is, for example, a CIS (Contact Image Sensor), etc. The CIS is, for example, a device in which optical elements such as a lens and an optical sensor are integrated with an illumination device serving as a light source such as an LED.

[0089] In some CISs, the LEDs that act as both heat and light sources are located at the left and right ends. In this configuration, the amount of light in the center is the sum of the light emitted by the left and right LEDs.

[0090] And different LEDs are placed separately on the left and right ends. In many cases, there is a difference in characteristics between the two. Such a difference in characteristics occurs in the main scanning direction, i.e., in the left-right direction. occurs.

[0091] For example, if there is a characteristic difference such that the light quantity of the LED arranged at the right end is more likely to drop than that of the LED arranged at the left end, the tendency will be as shown in correlation 401 in Fig. 5. In order to counteract such a tendency, it is desirable to perform correction (edge ​​correction) taking into account the positional relationship as shown in correction formula 402.

[0092] The estimation of the correlation and the correction (edge ​​correction) may be performed for each section, for example, as follows.

[0093] Fig. 6 is a diagram showing a second example of correlation and correction (end correction). The example shown below is a case where the effect of heat occurs as shown in Fig. 5. That is, in the example shown below, it is assumed that there is a correlation in which the light quantity tends to decrease more rapidly from the first end PS1 (e.g., the left end) to the second end PS2 (e.g., the right end), similarly to Fig. 5.

[0094] Hereinafter, an example will be described in which the X direction is divided into three sections. The number of sections, the range of each section, and whether or not each section has an equal range are set in advance by the user, for example.

[0095] The first section 511 is mainly the left portion in the X direction (an example of a section including the first end portion PS1).

[0096] The second section 512 is mainly the central portion in the X direction (an example of a section including a central portion PS3).

[0097] The third section 513 is mainly the right portion in the X direction (an example of a section that includes the second end portion PS2).

[0098] The section correlation 501 is estimated to be different for the first section 511, the second section 512, and the third section 513, for example.

[0099] A correction value 502 is set for each section based on the section correlation 501. That is, the correction value 502 is a value calculated so as to cancel the tendency estimated by the section correlation 501, similar to FIG.

[0100] In this manner, estimation and correction (edge ​​correction) may be performed in segments. For example, when estimation and correction (edge ​​correction) are performed in pixel units, the processing is performed in smaller units than when performed in segments. This makes the calculations more complex and the amount of data more likely to increase. Therefore, segments are set in units of, for example, a group of multiple pixels. By performing processing such as estimation and correction (edge ​​correction) in segments in this manner, the calculation load can be reduced.

[0101] The divisions are not limited to the above-described examples of the first division 511, the second division 512, and the third division 513. For example, each division may be divided equally. Alternatively, the divisions may be set by measuring the tendency of the light amount or the like in advance and allocating a division to each range that groups together ranges with similar tendencies.

[0102] In addition, it is desirable that the correction (edge ​​correction) is performed periodically, for example. For example, it is desirable that the correction (edge ​​correction) described with reference to FIG. 4 or FIG. 5 is performed periodically at preset times.

[0103] Fig. 7(a) is a diagram showing an example of periodic correction (edge ​​correction). For example, as shown in Fig. 3, a case where the amount of light decreases over time due to the effect of heat will be described. Also, the ideal state 201 is the same as that in Fig. 3.

[0104] First, the interval (indicated as "correction interval 601" in the figure) for performing correction (end correction) is set in advance. Once the correction interval 601 is set in this manner, correction (end correction) is performed every time the time of the correction interval 601 has elapsed. Note that the correction interval 601 is not limited to time, and may be the number of recording media to be processed or the amount of processed data, etc. For example, if the correction interval 601 is set in units of time, the time is measured by a timer or the like, and when the time of the correction interval 601 is counted, the reading device 10 performs correction (end correction).

[0105] When the correction (end correction) is performed, the read value will show approximately the value of the ideal state 201. Then, after the correction (end correction), the value will tend to decrease again due to the influence of heat. Therefore, the correction interval 601 is set based on the time when it is estimated that a certain degree of decrease will occur. In this way, by performing the correction (end correction) at every correction interval 601, the reading device 10 can periodically correct the read value (end correction) and perform reading with high accuracy.

[0106] In addition, it is desirable that the correction (edge ​​correction) is performed periodically, for example. For example, it is desirable that the correction (edge ​​correction) described with reference to FIG. 4 or FIG. 5 is performed periodically at preset times.

[0107] Fig. 7(b) is a diagram showing another example of periodic correction (edge ​​correction). In this example, the case where the amount of light decreases over time due to the influence of heat will also be described. Also, the ideal state 201 differs from Fig. 7(a) in that it is an ideal state 201a due to edge correction and an ideal state 201b due to shading.

[0108] First, the interval at which edge correction is performed (indicated as "correction interval 601" in the figure) and the interval at which shading is performed are set in advance. The interval at which shading is performed may be set, for example, as an integer multiple of the correction interval 601, or may be set as the number of edge corrections. In this way, when the correction interval 601 is set, correction (edge ​​correction) is performed every time the time of the correction interval 601 has elapsed.

[0109] When the edge correction is performed, the read value shows the value of the ideal edge correction state 201a. After the correction (edge ​​correction), the value tends to decrease again due to the influence of heat. Therefore, the correction interval 601 is set based on the time when it is estimated that a certain degree of decrease will occur. Here, the correction (edge ​​correction) mainly uses the edge, so in the long term, the read value corrected (edge ​​correction) over the entire main scanning area by shading is not completely ideal because the read value other than the edge shifts. Therefore, if the white member 11W is read and shading is performed after the edge correction is performed a predetermined number of times, the read value can be set to the ideal state 201b as shown in FIG. 7(b). In this way, by performing shading after each edge correction performed a predetermined number of times, the reading device 10 can periodically correct the read value (edge ​​correction) and perform reading with high accuracy.

[0110] The correction (edge ​​correction) is not limited to correction for the effect of heat and fluctuations in position, and may be a process for correcting, for example, deterioration over time.

[0111] [Second embodiment] For example, the reading device 10 may perform the overall process as follows.

[0112] FIG. 8 is a diagram illustrating a first example of the overall process.

[0113] In step S0801, the reading device 10 reads a reference value. For example, the reading device 10 reads both the left end and the right end in FIG. 2 to set the reference value. Specifically, when both the first area and the second area are set as the reading range, the reading device 10 extracts the reading results of the parts corresponding to the left end and the right end from the reading range to generate the reference value. In this way, the reference value and the reading value may be generated either from the reading results of only the target position, or by extracting the reading results of the target position.

[0114] In step S0802, the reader 10 judges whether the reference value is within the allowable range. For example, when the reader 10 performs multiple readings in reading the reference value as in step S0801, if any one of the multiple readings is outside the allowable range, the reader 10 judges that the value is not within the allowable range (NO in step S0802).

[0115] The allowable range is set in advance. For example, the allowable range is set by setting upper and lower limits of the read value, or by setting the ratio of the allowable range to the set value (set in a relative value format, etc.).

[0116] For example, the position where the reference value is read may be contaminated with dust, etc. In such a case, the dust may cause the reference value to show an abnormal value, and therefore, if such a reference value is used, the accuracy of reading the recording medium, etc. may worsen due to correction (edge ​​correction).

[0117] Therefore, an allowable range for the reference value is set in advance. In this way, if the reference value is within the allowable range, it is determined that the reference value is a normal value and is preferably used for correction (edge ​​correction).

[0118] Next, if the reference value is within the allowable range (YES in step S0802), the reading device 10 proceeds to step S0803. On the other hand, if the reference value is not within the allowable range (NO in step S0802), the reading device 10 proceeds to step S0804.

[0119] In step S0803, the reading device 10 performs correction (edge ​​correction). That is, the reading device 10 performs correction (edge ​​correction) based on the reference value generated in step S0801.

[0120] In step S0804, the reading device 10 does not perform correction (edge ​​correction). That is, the reading device 10 disables correction (edge ​​correction) by not performing correction in response to the determination result that the reference value generated in step S0801 is an abnormal value. Note that in such a case, an abnormality has occurred due to dust or the like. Therefore, the determination result that an abnormality has occurred may be notified to a user, a service person, or the like.

[0121] In this way, it is desirable to use overall processing that determines whether or not to correct the read value (edge ​​correction) depending on whether the read value is within the allowable range. With such overall processing, correction (edge ​​correction) based on an inappropriate reference value due to the influence of dust, etc. can be invalidated, and excessive correction (edge ​​correction) can be prevented.

[0122] Furthermore, when reading at a plurality of positions to generate reference values, the overall process may be as follows.

[0123] Fig. 9 is a diagram showing a second example of the overall processing. Below, an example will be described in which reading is performed to generate reference values ​​at two locations (the left end and the right end will be taken as an example). The overall processing may be, for example, a process in which the first sheet is subjected to the processing shown in Fig. 8, and the subsequent "N" sheets are subjected to the processing shown in Fig. 9. Below, an example will be described in which the second sheet onwards are the target.

[0124] In step S0901, the reading device 10 reads a reference value. For example, the reading device 10 performs the same process as in step S0801.

[0125] In step S0902, the reading device 10 judges whether or not the reference values ​​at both positions are within the allowable range. For example, the reading device 10 performs the same process as in step S0802.

[0126] Next, if the reference values ​​at both locations are within the allowable range (YES in step S0902), the reading device 10 proceeds to step S0903. On the other hand, if any one of the reference values ​​at both locations is not within the allowable range (NO in step S0902), the reading device 10 proceeds to step S0905.

[0127] In step S0903, the reader 10 performs correction (edge ​​correction) based on the reference values ​​at two locations. That is, since the two read values ​​are both normal values ​​within the allowable range in step S0902, both are used to determine the reference value. For example, the reference value is determined by averaging the read values ​​at the two locations.

[0128] In step S0904, the reading device 10 judges whether or not to continue reading.

[0129] Next, if reading is to be continued (YES in step S0904), the reading device 10 proceeds to step S0902. On the other hand, if reading is not to be continued (NO in step S0904), the reading device 10 ends the entire process.

[0130] In step S0905, the reader 10 judges whether the reference value of the first end portion PS1 is within the allowable range. That is, the reader 10 judges whether the reference value of the left end portion, which is an example of the first end portion PS1, among the read values ​​generated in step S0901 is within the allowable range.

[0131] Next, if the reference value of the first end portion PS1 is within the allowable range (YES in step S0905), the reading device 10 proceeds to step S0906. On the other hand, if the reference value of the first end portion PS1 is not within the allowable range (NO in step S0905), the reading device 10 proceeds to step S0907.

[0132] In step S0906, the reader 10 performs correction (end correction) based on the reference value of the first end PS1. That is, based on the determination result in step S0905 that the reference value of the first end PS1 is within the allowable range and is a normal value, the reader 10 uses the read value of the first end PS1 to determine the reference value.

[0133] In step S0907, the reader 10 judges whether the reference value of the second end portion PS2 is within the allowable range. That is, the reader 10 judges whether the reference value of the right end portion, which is an example of the second end portion PS2, among the read values ​​generated in step S0901 is within the allowable range.

[0134] Next, if the reference value of the second end portion PS2 is within the allowable range (YES in step S0907), the reading device 10 proceeds to step S0908. On the other hand, if the reference value of the second end portion PS2 is not within the allowable range (NO in step S0907), the reading device 10 proceeds to step S0909.

[0135] In step S0908, the reader 10 performs correction (end correction) based on the reference value of the second end PS2. That is, based on the determination result in step S0907 that the reference value of the second end PS2 of the two read values ​​is within the allowable range and is a normal value, the reader 10 uses the read value of the second end PS2 to determine the reference value.

[0136] In step S0909, the reading device 10 maintains the reference value and performs correction (edge ​​correction). That is, since the read value generated in step S0901 is not within the allowable range, the reading device 10 determines that the reference value for the first sheet, etc., should be the reference value. Note that the reading device 10 may also determine not to perform correction (edge ​​correction) in step S0909. In this way, the reading device 10 invalidates the abnormal value.

[0137] In addition, the process of determining whether the reference value is within the allowable range and the process of determining the reference value according to the result of the determination are not limited to the order of performing the first end and then the second end. In other words, the overall process does not have to be in the order shown in the figure.

[0138] As described above, when reading at multiple locations, it is desirable for the reading device 10 to extract a reference value that is within the allowable range from among multiple reference values ​​and use it as the reference value. In other words, the reading device 10 does not use a read value that is not within the allowable range and that is abnormally large or small when determining the reference value. In this way, when the reference value is determined only from read values ​​that are normal values ​​within the allowable range, the reading device 10 can perform correction (edge ​​correction) with high accuracy.

[0139] [Variations] For example, the process of correction (edge ​​correction) etc. may be performed for each divided unit as follows.

[0140] 10 is a diagram showing a first example of correction (edge ​​correction) performed on a divided area. For example, an example in which the paper is a cut sheet 110 will be described.

[0141] The recording medium is a cut sheet 110, and may have a particularly long dimension, which is called a long length. Specifically, the cut sheet 110 may have a dimension such as 700 mm or 1260 mm. In such long recording media having a dimension of 700 mm or more, a decrease in the amount of light is more likely to occur, particularly near the rear end, compared to processing near the front end. Therefore, it is preferable to set divided regions and perform correction (edge ​​correction) even for one recording medium. That is, correction (edge ​​correction) may be performed multiple times for one recording medium.

[0142] The divided regions are determined, for example, by setting the length of one divided region in advance. There may be three or more divided regions. That is, the divided regions may be generated with one region smaller than the example shown in the figure, and there may be a third or more divided regions.

[0143] For example, the divided areas are set in advance as a first divided area 1101 and a second divided area 1102, and the reading device 10 performs correction (edge ​​correction) and generation of reference values ​​separately for the first divided area 1101 and the second divided area 1102. With such a configuration using divided areas, accurate correction (edge ​​correction) can be performed even for a long recording medium.

[0144] Similarly, when the recording medium is a continuous form (sometimes called a "continuous form," "continuous paper," "LP paper," "form paper," or "fanfold paper," etc.; it may also be called "Z paper," etc.), corrections (edge ​​corrections) and other processes may be performed for each divided unit as follows:

[0145] 11 is a diagram showing a second example of performing correction (edge ​​correction) on a divided area. For example, an example in which the paper is a continuous form 111 will be described.

[0146] In many cases, the continuous form 111 has longer intervals between cut lines than the cut sheets 110, or has no cut lines at all. Therefore, the continuous form 111 is set in advance so that it can be divided into predetermined units.

[0147] The predetermined unit is determined, for example, as the time it takes to transport the recording medium, the length of the recording medium, or for each image.

[0148] Specifically, in the figure, the divided regions are set as a fourth divided region 1114, a fifth divided region 1115, a sixth divided region 1116, .... Therefore, in the fourth divided region 1114, the fifth divided region 1115, and the sixth divided region 1116, correction (edge ​​correction) is performed for each divided region. In this way, the divided region is a unit for generating a reference value and a unit for performing correction (edge ​​correction). With a configuration using such divided regions, correction (edge ​​correction) can be performed with high accuracy even for recording media such as continuous forms.

[0149] [Examples of image forming devices] FIG. 12 is a diagram illustrating an example of the configuration of an image forming apparatus.

[0150] The image forming apparatus is, for example, an electrophotographic color multifunction device 500 . The following description will be given taking a multifunction peripheral as an example.

[0151] The multifunction device 500 is a device that includes a reading device, a conveying device, etc. The multifunction device 500 also includes an image forming unit, a conveying unit, the reading device 10, etc.

[0152] Specifically, the image forming means forms an image on a sheet-like recording medium P. After fixing, the conveying means conveys the recording medium P. The reading device 10 is an example of an image reading means that reads an image from an object conveyed by the conveying means.

[0153] The multifunction machine 500 is composed of, for example, a device main body 5001, a scanner 5002, and a display operation device 503. Specifically, the scanner 5002 is attached to the upper part of the device main body 5001 and reads an original. The display operation device 503 is attached so as to protrude upward and rearward from the scanner 5002.

[0154] The scanner 5002 reciprocates a first moving body and a second moving body to read and scan an original placed on the contact glass.

[0155] The first moving body is equipped with a light source for illuminating the document, a mirror, etc., and also with multiple reflecting mirrors. The scanning light emitted from the second moving body is focused by an imaging lens on the imaging surface of a reading sensor installed behind it, and then read by the reading sensor as an image signal.

[0156] The display operation device 503 includes a liquid crystal panel having a pressure-sensitive touch panel and a speaker. The display operation device 503 is controlled by the main body control unit. Based on this control, the display operation device 503 displays an operation screen, a setting screen, or the like.

[0157] The display operation device 503 transmits selected or input information to the main body control unit when each screen is displayed, etc. Also, under the control of the main body control unit, the display operation device 503 displays each message such as the operating status of each unit, paper supply to the user, toner supply, and warnings on the liquid crystal panel, and outputs the messages as sound from the speaker.

[0158] The apparatus main body 5001 has an image forming unit, which is an example of an image forming means. The image forming unit is a tandem type image forming section that is configured by arranging four process units (in the figure, these are "1Y", "1C", "1M" and "1Bk". Hereinafter, they may be collectively referred to as "process unit 1") side by side.

[0159] The process unit 1 is configured to be detachable from the apparatus main body 5001. Each process unit 1 has the same configuration, except that each process unit 1 contains toner of a different color, yellow (Y), cyan (C), magenta (M), and black (Bk), which correspond to the color separation components of a color image.

[0160] The process unit 1 includes a photoconductor 2, a charging roller 3, a developing device 4, and a cleaning blade 5. The photoconductor 2 is a latent image carrier. The charging roller 3 is an example of a charging means for charging the surface of the photoconductor 2. The developing device 4 is an example of a developing means for forming a toner image on the surface of the photoconductor 2. The cleaning blade 5 is an example of a cleaning means for cleaning the surface of the photoconductor 2. In the figure, reference numerals are given only to the photoconductor 2, the charging roller 3, the developing device 4, and the cleaning blade 5 of the yellow process unit "1Y", and reference numerals are omitted for the other process units.

[0161] For example, an exposure device 6 is installed above the process unit 1. The exposure device 6 is an example of an exposure means that exposes the surface of the photoconductor 2. For example, the exposure device 6 has a light source, a polygon mirror, an f-θ lens, and a reflecting mirror. The exposure device 6 irradiates the surface of the photoconductor 2 with laser light based on image data input from an external device such as a personal computer or a scanner 5002.

[0162] Further, for example, a transfer device 7 is installed below the process unit 1. The transfer device 7 has an intermediate transfer belt 504 and the like. The intermediate transfer belt 504 is a transfer body and is composed of an endless belt or the like. The intermediate transfer belt 504 is stretched around a plurality of tension rollers, for example, tension rollers 21, 22, 23, and 24. When one of these tension rollers rotates as a drive roller, the intermediate transfer belt 504 runs (rotates) in a circle in the direction indicated by the arrow in the figure.

[0163] The primary transfer rollers 505 are installed as primary transfer means at positions facing the four photoconductors 2. The primary transfer rollers 505 are installed for each color. The primary transfer rollers 505 press the inner circumferential surface of the intermediate transfer belt 504 at each position. In this way, primary transfer nips are formed at the points where the pressed parts of the intermediate transfer belt 504 come into contact with the respective photoconductors 2.

[0164] Further, the primary transfer roller 505 is connected to a power source, and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the primary transfer roller 505.

[0165] For example, a secondary transfer roller 506 is installed at a position facing the tension roller 24. The secondary transfer roller 506 presses the outer peripheral surface of the intermediate transfer belt 504. In this manner, a secondary transfer nip is formed at a location where the secondary transfer roller 506 and the intermediate transfer belt 504 come into contact with each other. The secondary transfer roller 506, like the primary transfer roller 505, is connected to a power source. A predetermined direct current (DC) voltage and / or alternating current (AC) voltage is applied to the secondary transfer roller 506 .

[0166] The medium containing cassette 507 is installed, for example, in the lower part of the apparatus main body 5001. The medium containing cassette 507 contains a recording medium P, such as paper or an OHP sheet. The recording medium P is then fed out by a feed roller 508.

[0167] In the illustrated configuration, a discharge tray 509 is provided on the left side of the apparatus main body 5001 .

[0168] Conveyance path R is an example of a conveyance path that conveys a recording medium from a medium containing cassette 507 through a secondary transfer nip to an output tray 509. In the conveyance path R, a registration roller 510 is provided upstream of the position of the secondary transfer roller 506 in the recording medium conveyance direction. Meanwhile, a fixing device 8, a reading device 10, a pair of output rollers 16, and the like are provided downstream of the position of the secondary transfer roller 506 in the recording medium conveyance direction.

[0169] The fixing device 8 includes, for example, a fixing roller 17 and a pressure roller 18. The fixing roller 17 is an example of a fixing member having a heater therein. The pressure roller 18 is an example of a pressure member that presses the fixing roller 17. A fixing nip is formed at a location where the fixing roller 17 and the pressure roller 18 come into contact with each other.

[0170] The multifunction device 500 also includes a processor such as a central processing unit (CPU) and a main storage device and an auxiliary storage device such as a random access memory (RAM) and a read only memory (ROM).

[0171] For example, the multifunction device 500 starts image formation when a user issues a command to start using the display operation device 503. Specifically, image data is generated by reading using the scanner 5002. Based on this image data, the multifunction device 500 performs image formation using an image forming unit.

[0172] Based on image information of the original read by the scanner 5002, the exposure device 6 irradiates the charged surface of each photoconductor 2 with laser light, forming an electrostatic latent image on the surface of the photoconductor 2. At this time, the image information exposed to the photoconductor 2 is monochromatic image information obtained by decomposing a desired full-color image into color information of yellow, cyan, magenta, and black. When toner is supplied by the developing device 4 to the electrostatic latent image thus formed on the photoconductor 2, the electrostatic latent image is visualized as a toner image.

[0173] The toner images of each color formed on the photoreceptor 2 are then transferred in sequence, superimposed on the intermediate transfer belt 504, by the transfer electric field formed in the primary transfer nip. In this way, the intermediate transfer belt 504 carries a full-color toner image on its surface. Any toner on each photoreceptor 2 that has not been transferred to the intermediate transfer belt 504 is removed by the cleaning blade 5.

[0174] An image forming apparatus including the reading device 10 has, for example, the following functional configuration.

[0175] 13 is a diagram showing an example of the functional configuration of an image forming apparatus, for example, a multifunction peripheral 500, which is an example of an image forming apparatus, is configured to include a reading device 10 and the like.

[0176] The reading device 10 has a functional configuration including a background unit 10F1, a reading unit 10F2, and a correction unit 10F3. The reading device 10 preferably has a functional configuration further including a switching unit 10F4, a determination unit 10F5, a setting unit 10F6, a storage unit 10F7, and a calculation unit 10F8. The following describes the functional configuration as shown in the figure.

[0177] The background portion 10F1 serves as the background when the recording medium is read. For example, the background portion 10F1 is realized by a roller 11.

[0178] The reading unit 10F2 performs a reading procedure to generate a read value by reading the background portion 10F1 as a background. For example, the reading unit 10F2 is realized by a line sensor 12.

[0179] The reading unit 10F2 also includes a shading unit 10F21, etc. The shading unit 10F21 performs processing such as shading on the image read by the reading unit 10F2.

[0180] The correction unit 10F3 performs a correction procedure to correct the read value (edge ​​correction). For example, the correction unit 10F3 is realized by the control device 13 or the like.

[0181] The switching unit 10F4 performs a switching procedure for switching the colors of the first area and the second area in the background portion 10F1 according to the type of recording medium. For example, the switching unit 10F4 is realized by a driving device such as a motor.

[0182] The determination unit 10F5 performs a determination procedure to determine whether the read value is within an allowable range or not. For example, the determination unit 10F5 is realized by the control device 13 or the like.

[0183] The setting unit 10F6 performs a setting procedure for setting an allowable range of the reference value. For example, the setting unit 10F6 is realized by the control device 13 or the like.

[0184] The storage unit 10F7 performs a storage procedure for storing the reference value. For example, the storage unit 10F7 is realized by the control device 13 or the like.

[0185] The calculation unit 10F8 performs a calculation procedure to calculate a correction parameter for correcting the read value (edge ​​correction) based on the reference value. For example, the calculation unit 10F8 is realized by the control device 13 or the like.

[0186] The driving unit 10F10 transports the recording medium and is realized by, for example, a motor or the like.

[0187] The transport control unit 10F11 controls the drive unit 10F10. For example, the transport control unit 10F11 is realized by a calculation device, a sensor, and the like.

[0188] The transport detection unit 10F12 detects the transport of the recording medium, etc. For example, the transport detection unit 10F12 is realized by a transport sensor 20 or the like.

[0189] In addition, in a configuration in which the image forming apparatus has a reading device as shown in the figure, the function of the reading device may be realized by hardware that the image forming apparatus has. For example, the correction unit 10F3 may be realized by a calculation device or the like that the image forming apparatus has. In this way, the hardware and functional configuration are not limited to the configuration as shown in the figure. Therefore, the switching unit 10F4 and the conveyance control unit 10F11, etc. may have integrated functions.

[0190] The type of recording medium is determined to be a different type if, for example, the color, thickness, material, size, or shape is different. The type of recording medium is input by the user or detected by a sensor or the like, and the reading device or the like determines what type of recording medium is currently being targeted. In this manner, with a configuration capable of determining the type of recording medium, the reading device or the like can switch the colors of the first area and the second area according to the type of recording medium (i.e., when it is detected that the recording medium has changed to a different type).

[0191] [Modifications of rollers, etc.] For example, the background portion 10F1 etc. may be realized by a roller etc. as described below.

[0192] Fig. 14 is a diagram showing a first modified example, an explanatory side view of the reading device, and an enlarged view of a portion of the reading device, focusing on an opposing member 93 provided therein.

[0193] For example, the reading device is disposed downstream of the fixing device 8 in the transport direction. This reading device optically reads an image formed on the recording medium. Then, the reading device generates image data indicating the image to be inspected. Based on this generated image data, the multifunction device 500 performs a correction process for the image to be formed. For this reason, it is desirable to change the color of the facing member 93 or the gap (gap) between the facing member 93 and the contact glass 94 in accordance with the correction process.

[0194] FIG. 15 is a diagram showing a reading device 10 to which the first modified example is applied.

[0195] The reading device 10 includes an illumination light source 91, an image reading device 92, an opposing member 93, a contact glass 94, a support member 95, a first transport guide 98, and a second transport guide 99. Note that the reading device 10 is not limited to the configuration shown in the figure, and may have a configuration without the first transport guide 98, for example.

[0196] The illumination light source 91 is disposed on the side that faces the surface of the recording medium on which an image is formed (that is, the image forming surface) when the recording medium is conveyed.

[0197] The illumination light source 91 is a portion of the transport path R where the recording medium passes through the reading device 10 (for example, the partial transport path R1 shown in FIG. 14), and illuminates a predetermined reading position for reading an image from the recording medium. The reading position corresponds to a part of the partial transport path R1.

[0198] The image reading device 92 includes three reflecting mirrors 921 , an imaging lens 922 , and an image sensor 923 .

[0199] The three reflecting mirrors 921 guide the reflected light from the image forming surface of the recording medium passing the reading position from the reading position to the imaging lens 922 .

[0200] The imaging lens 922 forms an image on the position of the image sensor 923 using the light reflected from the image forming surface of the recording medium P and guided by the three reflecting mirrors 921 .

[0201] The image sensor 923 has an image pickup element and reads the image formed on the image forming surface of the recording medium P.

[0202] In addition, even when no recording medium is present on the partial conveying path R1, the image sensor 923 reads the roller outer surfaces of the roller 931 that function as the curved opposing portion of the opposing member 93 (for example, the first roller outer surface 931a, the second roller outer surface 931b, the third roller outer surface 931c, and the fourth roller outer surface 931d in the figure).

[0203] The image sensor 923 receives the light focused by the imaging lens 922 and generates image data according to the amount of light received.

[0204] The facing member 93 is disposed on the rear side of the image forming surface when the recording medium is conveyed. The facing member 93 has four rollers 931, which are also rotating bodies serving as a plurality of facing portions, rotatably held by a roller bracket 935 serving as a rotation holding member.

[0205] The four rollers 931 are rotatable rotating bodies having a first roller outer peripheral surface 931a, a second roller outer peripheral surface 931b, a third roller outer peripheral surface 931c, and a fourth roller outer peripheral surface 931d, each of which functions as a plurality of curved surface opposing parts having a convexly curved reference surface. In addition, the rotating bodies rotate independently of the roller bracket 935.

[0206] Further, the roller bracket 935 is fastened to a roller bracket shaft 936. When the roller bracket shaft 936 rotates, it rotates while holding the four rollers 931. This allows the outer circumferential surfaces of the four rollers 931 to be selectively switched. This causes the partial conveying path R1 to form a predetermined reading position facing the contact glass 94 with a gap through which the recording medium P can pass.

[0207] The reading position is set, for example, at a position closest to the contact glass 94 with respect to the outer surface of the roller 931 (in the figure, the first roller outer surface 931a) that is arranged opposite the contact glass 94 among the outer surfaces of the multiple rollers 931.

[0208] In addition, the reading position may be set, for example, at a position closer to the contact glass 94 than the position closest to the contact glass 94 on the outer surface of the roller 931 arranged opposite the contact glass 94 by the thickness of the recording medium P.

[0209] The contact glass 94 as a first light-transmitting member is a light-transmitting member that is arranged at a position that faces the image-forming surface of the recording medium when the recording medium is transported to a predetermined reading position.

[0210] That is, the contact glass 94 is disposed between the reading device 10 and the facing member 93. The contact glass 94 is disposed at a position facing one surface of the recording medium P.

[0211] The support member 95 is a member to which both the illumination light source 91 and the image reader 92 are fixed. Of the transport path R, the partial transport path R1 is separated from both the upstream portion and the downstream portion of the partial transport path R1 and is supported by the support member 95.

[0212] For example, a first conveyor roller 96 is disposed upstream of the partial conveyor path R1, and a second conveyor roller 97 is disposed downstream of the partial conveyor path R1.

[0213] The first transport guide 98 as the second light-transmitting member is a light-transmitting member that is arranged on the reading position side of each of the outer circumferential surfaces of the rollers 931 that the opposing member 93 includes.

[0214] The first transport guide 98 constitutes a part of the partial transport path R1, and has a smooth surface that is smooth enough not to impose a transport load when the recording medium passes above the facing member 93 as a background member.

[0215] The first transport guide 98 is included in the optical system of the reading device 10, and is therefore made of a material (such as glass or acrylic) that has little effect on the optical characteristics.

[0216] That is, the first transport guide 98 is disposed between the reading device 10 and the facing member 93. The first transport guide 98 is disposed at a position facing the other surface of the recording medium P.

[0217] The first conveying guide 98 prevents friction (or collision) between the opposing member 93 and the outer circumferential surface of the roller 931 and the object, and prevents contamination of the opposing member 93 (or roller 931) that may occur due to the passage of a recording medium.

[0218] The first transport guide 98 also serves as a transport path component that narrows the partial transport path R1 to an extent that allows the recording medium to pass through. This makes the partial transport path R1 a smooth transport path with a narrow gap, and the passage of the recording medium is expected to improve the self-cleaning effect of the reading position.

[0219] The second transport guide 99, which serves as a transport guide member, is a slope-shaped member arranged upstream of the partial transport path R1, and has a rotating shaft 991 that rotatably holds one end (i.e., the end on the partial transport path R1 side) as a free end.

[0220] The free end of the second transport guide 99 comes into contact with the upstream end of the first transport guide 98 or the opposing member 93 when the opposing member 93 rotates to change the outer circumferential surface of the roller 931 opposing the reading position.

[0221] At this time, by rotating about the rotation shaft 991 as a fulcrum, it is possible to escape so as not to impede the rotation of the opposing member 93 .

[0222] The second transport guide 99 can prevent the leading end in the transport direction of the recording medium, which passes through the transport path R and is transported to the reading position, from contacting (or colliding with) the opposing member 93 (i.e., the outer peripheral surface of the roller 931).

[0223] If the second transport guide 99 were not present, the leading edge in the transport direction of the recording medium P that enters the narrow partial transport path R1 from the transport path R upstream of the opposing member 93 would come into contact (or collide with) the opposing member 93 (i.e., the outer peripheral surface of the roller 931).

[0224] At this time, the conveyance is temporarily impeded due to frictional resistance with the opposing member 93. Furthermore, the recording medium is pushed from the upstream side.

[0225] The leading edge of the recording medium slides on the circumferential surface of the opposing member 93. The recording medium then moves downstream from the collision position. The impact at this time causes the recording medium to fluctuate at the reading position. Therefore, when the image-forming surface of the fluctuating recording medium is read, the reading is performed in an out-of-focus state rather than in-focus state. This makes it easy for the reading accuracy to decrease.

[0226] In contrast, if the second transport guide 99 is disposed upstream of the opposing member 93, the smoothness of the transport state of the recording medium P can be improved, and as a result, the reading accuracy can be improved.

[0227] The process of reading an image formed on the image forming surface of the recording medium will be described in detail. When the recording medium is passed through the reading position, the image reading device 92 passes through the reading position between the first conveying guides 98, which is below the contact glass 94.

[0228] In this case, the image forming surface is read from the side of the arrow 940. The first roller outer peripheral surface 931a of the facing member 93 is disposed at a position facing the contact glass 94.

[0229] The outer peripheral surface 931a of the first roller constitutes a reference surface, thereby obtaining high image reading accuracy. At this time, the recording medium moves while sliding on the smooth surface of the first conveying guide 98.

[0230] Therefore, the first transport guide 98 has a function of transporting the recording medium, and forms a narrow gap that prevents the recording medium from flapping, forming a part of the medium transport device that prevents medium paper jams and the like.

[0231] The four rollers 931 arranged on the opposing member 93 are rollers that differ from each other in at least one of color and diameter.

[0232] Therefore, among the rollers having an outer circumferential surface, for example, roller 931 corresponding to first roller outer circumferential surface 931a is black and has a normal diameter, and corresponds to the above-mentioned black member 11B.

[0233] The roller 931 corresponding to the second roller outer circumferential surface 931b is white and has a small diameter, and corresponds to the above-mentioned white member 11W.

[0234] The roller 931 corresponding to the third roller outer circumferential surface 931c is white and has a normal diameter, and corresponds to the above-mentioned white member 11W.

[0235] The roller 931 corresponding to the fourth roller outer circumferential surface 931d is black in color and has a small diameter, and corresponds to the above-mentioned black member 11B.

[0236] The color of the roller 931 is changed depending on the paper passing mode of the recording medium. The notification mode is set and changed by a display operation device provided in the main body control unit.

[0237] The diameter of each roller 931 may be determined based on the thickness of the recording medium or whether it is used for shading. Since the roller 931 rotates so that the outer circumferential surface changes depending on the thickness of the recording medium, the size of the gap in the partial conveying path R1 can be set according to the thickness of the recording medium.

[0238] The rollers etc. may have the following configuration.

[0239] FIG. 16 is a diagram showing a second modified example.

[0240] For example, the first transport guide 98a may be configured to move relative to the opposing member 93. In this case, the first transport guide 98a is disposed at a position facing the contact glass 94 across the partial transport path R1.

[0241] Further, the first transport guide 98a changes the gap that forms with the partial transport path R1 according to the positions of the outer circumferential surfaces of the rollers 93a, 93b, 93c, and 93d of the opposing member 93. The rollers 93a and 93c correspond to the above-mentioned white member 11W, and the rollers 93b and 93d correspond to the above-mentioned black member 11B.

[0242] That is, the first transport guide 98a is a member that changes the facing distance to the contact glass serving as the first light-transmitting member.

[0243] The first transport guide 98a is also a transparent member that transmits light from the illumination light source 91 and transmits light reflected from the recording medium.

[0244] The first conveying guide 98a includes a cam 981 serving as a driving source.

[0245] The rotation of the cam 981 is controlled by the main body control unit depending on the notification mode of the recording medium P. The rotation of the cam 981 causes the position of the first conveying guide 98a to vary.

[0246] FIG. 17 is a diagram showing a third modified example.

[0247] The cross section of the opposing member is not limited to a circular one, and may be, for example, a polygonal member having a polygonal cross section (in this example, a hexagonal cross section).

[0248] In this case, the facing member 932 is configured to rotate along the transport direction of the recording medium. The position of the facing member 932 is changed by the rotation.

[0249] In the facing member, background surfaces (930a, 930b, 930c, 930d, 930e, and 930f in the figure) corresponding to the rollers described above are arranged as separate facing parts having different thicknesses or colors for each (i.e., six places) of the outer circumferential surface. Note that the background surfaces 930a, 930c, and 930d correspond to the white member 11W described above, and the background surfaces 930b and 930e correspond to the black member 11B described above.

[0250] Further, the first transport guides 98b that protect the respective background surfaces and face the partial transport path R1 are also disposed corresponding to the respective background surfaces.

[0251] The rollers may be modified as described above.

[0252] In the above-described embodiment, the reading device 10 reads the white member 11W and performs shading to correct main-scanning unevenness in the reading level, but the present invention is not limited to this embodiment.

[0253] Fig. 21 is a diagram showing a configuration example in which a white board is added to Fig. 14. Note that this embodiment is also applicable to other forms such as Fig. 1.

[0254] The first roller outer peripheral surface 931a and the fourth roller outer peripheral surface 931d correspond to the above-mentioned black member 11B, while the second roller outer peripheral surface 931b and the third roller outer peripheral surface 931c correspond to the above-mentioned white member 11W.

[0255] The white plates 800a, 800b, 800c, and 800d each have a width in the main scanning direction (X direction), which is the same width as the white member 11W and the black member 11B.

[0256] The white plate is disposed between each of the rollers (931a, 931b, 931c, 931d). By disposing the white plate 800 between each of the rollers, the time required to switch the position from the rollers 931 to the white plate can be shortened, improving the productivity of the device.

[0257] [Other embodiments] The recording medium is, for example, paper (also called "plain paper"). However, the recording medium may be coated paper, label paper, or an overhead projector sheet, film, or a flexible thin plate. That is, the material of the recording medium may be a material to which ink droplets can adhere, to which ink droplets can adhere temporarily, to which ink droplets can adhere and stick, or to which ink droplets can penetrate. Specifically, the recording medium may be a recording medium such as paper, film, or cloth, an electronic board, an electronic component such as a piezoelectric element (also called "piezoelectric member"), a powder layer (also called "powder layer"), an organ model, or a test cell. In this way, the material of the recording medium may be a material to which liquid can adhere, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, or a combination of these.

[0258] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist of the present invention. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0259] 10: Reading device 10F1: Background part 10F10: Drive unit 10F11: Transport control section 10F12: Transport detection unit 10F2: Reading section 10F3: Correction section 10F4: Switching section 10F5: Judgment section 10F6: Setting section 10F7: Storage section 10F8: Calculation section 11: Laura 11B: Black material 11W: White component 12: Line sensor 13: Control device 100: Paper 101: 1st area 102:Second area 201: Ideal state 202: Actual state 302 :Position influence 401: Correlation 402:Correction formula 500: Multifunction device 501:Category correlation 502: Correction value 1101: 1st divided area 1102 :Second divided area 1114: 4th divided area 1115: 5th division area 1116: 6th division area 5001: Device body 5002: Scanner P: Recording medium PS1: 1st end PS2: Second end PS3: central part R: Transport path R1: Partial transport path [Prior art documents] [Patent documents]

[0260] [Patent Document 1] JP 2007-208878 A

Claims

1. A reading device for reading a recording medium, a background portion that serves as a background when the recording medium is read; a reading unit that generates a read value by reading the background portion; a correction unit that corrects the read value, The background portion is A rotating member, a first region that is black; a second region that is white; After performing the correction a predetermined number of times, the first region and the second region are switched by rotation, The correction unit is The reading unit reads the second region and generates a reference value, and corrects the second region based on the reference value. A reading device comprising:

2. The recording medium further includes a switching unit that switches the color of the first area according to the type of the recording medium.

2. The reading device according to claim 1.

3. The recording medium is white.

3. A reading device according to claim 1 or 2.

4. A setting unit that sets an allowable range of the reference value; a determination unit that determines whether the read value is within the allowable range, The correction unit is A value to be the reference value is determined according to a result of the determination by the determining unit, or a determination is made as to whether or not to correct the read value. A reading device according to any one of claims 1 to 3.

5. A storage unit that stores the reference value; a calculation unit that calculates a correction parameter for correcting the read value based on the reference value, The correction unit is Correcting the reading based on the correction parameters A reading device according to any one of claims 1 to 4.

6. The correction unit is The read value is corrected based on the correction parameter after the reference value is generated and after heat is applied or after time has elapsed since the reference value is generated.

6. A reading device according to claim 5.

7. The calculation unit is Estimating a correlation between a position read by the reader and a variation in the read value relative to the position; calculating the correction parameters responsive to the correlation; The correction unit is The read value is corrected for each of the positions based on the correction parameters.

7. A reading device according to claim 6.

8. The first region is a region through which the recording medium passes; The second region is A region located outside the first region A reading device according to any one of the preceding claims.

9. The correction unit performs correction based on the reference value generated by the reading unit reading the second area at predetermined time intervals. A reading device according to any one of claims 1 to 4.

10. The correction unit is When the reading unit reads the second region and generates the reference value, the reading unit performs correction a predetermined number of times based on the reference value. The reading unit reads the first area switched to white by the switching unit and generates the reference value, and performs correction based on the reference value.

3. The reading device according to claim 2.

11. The first region is A region that is black and through which the recording medium passes; The second region is A region that is white and through which the recording medium does not pass; 2. The reading device according to claim 1.

12. A first reading is generated for one end of the second region; generating a second read value for an end of the second region different from the one end; generating the reference value based on an average of the first reading and the second reading; 2. The reading device according to claim 1.

13. an image forming unit that forms an image on a recording medium; a background portion that serves as a background when reading the recording medium on which an image is formed by the image forming portion; a reading unit that generates a read value by reading the background portion; a correction unit that corrects the read value, The background portion is A rotating member, a first region that is black; a second region that is white; After performing the correction a predetermined number of times, the first region and the second region are switched by rotation, The correction unit is The reading unit reads the second region and generates a reference value, and corrects the second region based on the reference value.

1. An image forming apparatus comprising:

Images