Patent Description:
An image forming apparatus may fail to form an intended image on a recording medium such as a sheet of paper due to an unexpected factor. Some techniques have been proposed that read an image formed and inspects the quality of the formed image.

For example, an image inspecting apparatus firstly sets an end portion of, e.g., a sheet as an image inspection exclusion area to be excluded from an inspection target. According to the setting, the image inspecting apparatus performs inspection excluding the end portion of the sheet. The image inspecting apparatus thus performs inspection excluding an area that is susceptible to erroneous detection, to prevent erroneous detection due to, e.g., the deformation of the sheet in the image inspection. An example of the deformation of the sheet is bending, which is so-called "twisting" at the end portion of the sheet. Such a technique has been proposed that prevents erroneous detection in image inspection (see <CIT>, for example).

In the related art, a user sets the image inspection exclusion area in advance. When sheets conveyed to the image inspecting apparatus vary in posture with respect to the direction in which the sheets are conveyed or when the sheets have deformed end portions as described above, the image inspection exclusion area set in advance is not appropriate for the sheets conveyed. As a result, an area to be set as the image inspection exclusion area may not be excluded as appropriate. In other words, the image inspecting apparatus in the related art may fail to sufficiently prevent erroneous detection in image inspection.

<CIT> and <CIT> discloses background art to the invention.

According to an embodiment of the present invention, an image reading device including an image reading unit, an output unit, and a setting unit is provided as described in the annexed claims.

There is also provided an image forming apparatus incorporating the image reading device.

For the sake of simplicity, like reference numerals are given to identical or corresponding constituent elements such as parts and materials having the same functions, and redundant descriptions thereof are omitted unless otherwise required.

As used herein, the term "connected/coupled" includes both direct connections and connections in which there are one or more intermediate connecting elements.

Now, a description is given of a first embodiment of the present disclosure.

Initially with reference to <FIG>, a description is given of an overall configuration of an image forming apparatus according to the first embodiment.

<FIG> is a diagram illustrating an overall configuration of an image forming apparatus.

In the following description, a "Y direction" refers to a recording medium conveyance direction in which a recording medium is conveyed. The recording medium conveyance direction may be referred to simply as the conveyance direction. An "X direction" refers to a direction perpendicular to the conveyance direction. A "Z direction" refers to a direction perpendicular to an X-Y plane.

For example, as illustrated in <FIG>, an image forming apparatus <NUM> includes an image forming device <NUM>, a sheet feeding device <NUM>, an image reading device <NUM>, and a post-processing device <NUM>.

The image forming device <NUM> forms an image on a sheet S as a recording medium according to input image data.

The sheet feeding device <NUM> supplies the sheet S to the image forming device <NUM>.

The image reading device <NUM> reads the sheet S output from the image forming device <NUM>. Specifically, the image reading device <NUM> reads the image formed on the sheet S.

The post-processing device <NUM> includes, e.g., a plurality of output trays. In the present embodiment, the post-processing device <NUM> includes a first output tray <NUM> and a second output tray <NUM>.

In the image forming apparatus <NUM>, the sheet feeding device <NUM>, the image forming device <NUM>, the image reading device <NUM>, and the post-processing device <NUM> are physically coupled in this order in the conveyance direction (i.e., leftward in <FIG>). The plurality of devices, namely, the sheet feeding device <NUM>, the image forming device <NUM>, the image reading device <NUM>, and the post-processing device <NUM> thus coupled construct the image forming apparatus <NUM>. Accordingly, in the image forming apparatus <NUM>, a conveyance passage P through which the sheet S is conveyed is defined by the internal components of the plurality of devices of the image forming apparatus <NUM>. The conveyance passage P is branched by a sorter <NUM> of the post-processing device <NUM> into a first path P1 to the first output tray <NUM> located below and a second path P2 to the second output tray <NUM> located above.

Although the conveyance passage P is indicated by a single line in <FIG>, the image forming apparatus <NUM> may include a conveyance passage for duplex printing, for example. The passage for outputting the sheet S may be branched into three or more passages, depending on the number of output trays, for example.

The sheet feeding device <NUM> accommodates the sheets S in various sizes or types. The sheet feeding device <NUM> includes, e.g., a sheet feeding roller that feeds the accommodated sheets S one by one and a motor that drives the sheet feeding roller.

The image forming device <NUM> includes, e.g., a forming device <NUM> that forms an image by an intermediate transfer method with an electrophotographic process technique.

Specifically, first, the forming device <NUM> primarily transfers, onto an intermediate transfer belt, toner images in different colors such as yellow (Y), magenta (M), cyan (C), and black (K) formed on drum-shaped photoconductors so that the toner images in the four colors are superimposed one atop another as a composite image on the intermediate transfer belt. Thereafter, the forming device <NUM> secondarily transfers the composite toner image onto the sheet S. Thus, the forming device <NUM> forms the toner image on the sheet S.

The image forming device <NUM> further includes a fixing device <NUM> downstream from the forming device <NUM> in the conveyance direction. The fixing device <NUM> applies heat and pressure to the sheet S to fix the toner image onto the sheet S.

The image forming method and the configuration of the image forming device <NUM> may be other than those described above.

The image forming device <NUM> further includes an operation display <NUM>. The operation display <NUM> is, e.g., a liquid crystal display (LCD) with a touch panel. Specifically, the operation display <NUM> includes, e.g., a display <NUM> and an operation device <NUM>.

The display <NUM> displays, e.g., an operation screen, the state of an image, and the operation state of each function according to a display control signal.

The operation device <NUM> includes, e.g., a numeric keypad and a start key. The operation device <NUM> receives an input operation from a user and outputs an operation signal to, e.g., a control device.

The display <NUM> may display an icon with, e.g., a cursor or a pointer on a screen and output an operation signal to, e.g., the control device in res pose to an input operation from the user.

The image forming device <NUM> may further include an image processing device that performs correction such as gradation correction on input image data. The image forming device <NUM> may further include a sheet conveying device that drives a conveying roller or a communication device that communicates with an external device through a communication network.

The image forming device <NUM> may further have a configuration as a copier that copies a document on the sheet S. For example, the image forming device <NUM> may include an automatic document feeder (ADF) and a scanner that scans the document.

The image reading device <NUM> includes an output image reading device <NUM> that optically reads an image formed on the sheet S. Specifically, the output image reading device <NUM> reads one side or both sides of the sheet S with a sensor such as a charge coupled device (CCD). Based on the reading result provided by the sensor, the output image reading device <NUM> generates read image data.

The image reading device <NUM> further includes, e.g., a calculation device, a control device, a storage device or memory, an input device, an output device, and a communication device to process, e.g., an image acquired with the sensor. The image reading device <NUM> includes, e.g., a central processing unit (CPU) <NUM>, a read only memory (ROM) <NUM>, and a random access memory (RAM) <NUM>.

The CPU <NUM> serves as the arithmetic device and the control device.

The ROM <NUM> and the RAM <NUM> serve as the storage devices or memories.

The sorter <NUM> includes, e.g., a switching gate that switches the output destination of the sheet S, a drive source such as a solenoid that drives the switching gate, and an interface that performs data transmission.

The post-processing device <NUM> may include, e.g., a cutter that cuts the sheet S, a stapler that performs stapling, and a sheet folder that folds the sheet S.

Referring now to <FIG>, a description is given of an example of inspection.

<FIG> is a diagram illustrating an outline of image inspection.

Now, a description is given of a case in which an image is formed on the sheet S according to input image data <NUM>, which is image data input to the image forming apparatus <NUM>.

As illustrated in <FIG>, after an image is formed on the sheet S according to the input image data <NUM>, a sensor <NUM> that is disposed downstream in the conveyance direction (i.e., on the left side in <FIG>) reads the image formed on the sheet S. The image reading device <NUM> generates, as read image data <NUM>, image data based on the reading result provided by the sensor <NUM>.

The read image data <NUM> is compared with the input image data <NUM> for an image inspection, which may be referred to simply as an inspection in the following description. Specifically, the image reading device <NUM> inspects whether the read image data <NUM> includes an image that is not included in the input image data <NUM> serving as reference data.

More specifically, the image reading device <NUM> inspects whether the read image data <NUM> includes contamination due to, e.g., toner or ink, scratches generated during conveyance, unevenness in printing, misalignment such as so-called "out of registration" or "off-registration," or a combination thereof. In short, the image reading device <NUM> inspects whether the read image data <NUM> includes, e.g., contamination. The image reading device <NUM> may determine whether the contamination is greater than an allowable value set in advance as a criterion for the inspection.

For example, the image inspection is implemented by image recognition. In other words, the image inspection is performed based on whether the read image data <NUM> matches the input image data <NUM>. For example, the image inspection may be implemented by image recognition of dust.

Note that the input image data <NUM> may be generated before the inspection is performed. For example, after the input image data <NUM> is generated once, the input image data <NUM> may be used for another inspection. This reduces the processing for generating the input image data <NUM>, resulting in reduction of the processing load.

When the read image data <NUM> includes, e.g., contamination, the image reading device <NUM> outputs an inspection result indicating the read image data <NUM> is abnormal. By contrast, when the read image data <NUM> does not include, e.g., contamination, the image reading device <NUM> outputs an inspection result indicating that the read image data <NUM> is normal.

Referring now to <FIG>, a description is given of some examples of area setting.

<FIG> is a diagram illustrating an example of area setting. <FIG> is a diagram illustrating how the conveyance state of the sheet S changes.

The image reading device <NUM> includes a first roller pair <NUM> serving as a first sandwiching conveyor and a second roller pair <NUM> serving as a second sandwiching conveyor. As illustrated in <FIG>, the first roller pair <NUM> is located upstream from the sensor <NUM> in the conveyance direction (i.e., below the sensor <NUM> in <FIG>); whereas the second roller pair <NUM> is located downstream from the sensor <NUM> in the conveyance direction (i.e., above the sensor <NUM> in <FIG>).

Now, a description is given of a case in which the state of the sheet S changes from part (a) to part (d) of <FIG> while the sheet S is conveyed. In other words, parts (a) to (d) of <FIG> illustrate different states of the sheet S gripped by the first sandwiching conveyor and the second sandwiching conveyor.

Specifically, parts (a) and (d) of <FIG> illustrate the sheet S sandwiched by either the first roller pair <NUM> (i.e., the first sandwiching conveyor) or the second roller pair <NUM> (i.e., the second sandwiching conveyor). When the sheet S is not gripped by the roller pairs that define the conveyance passage P as illustrated in parts (a) and (d) of <FIG>, the conveyance state of the sheet S is likely to be unstable and may often flap.

Specifically, in part (a) of <FIG>, the first roller pair <NUM> grips the sheet S; whereas the second roller pair <NUM> does not grip the sheet S. In this state, for example, a leading end area <NUM> of the sheet S is likely to flap. Note that the leading end area <NUM> of the sheet S is an area at a leading end of the sheet S.

By contrast, in part (d) of <FIG>, the second roller pair <NUM> grips the sheet S; whereas the first roller pair <NUM> does not grip the sheet S. In this state, for example, a trailing end area <NUM> of the sheet S is likely to flap. Note that the trailing end area <NUM> of the sheet S is an area at a trailing end of the sheet S.

On the other hand, parts (b) and (c) of <FIG> illustrate the sheet S sandwiched by both the first roller pair <NUM> and the second roller pair <NUM> and being stable.

When the image inspection is performed on the flapping sheet S, the reading accuracy of the sensor <NUM> may decrease. To address such a situation, the image reading device <NUM> performs a process of excluding an area that is likely to flap from the read image data <NUM> generated from the reading result provided by the sensor <NUM>, depending on the position of the sheet S being conveyed. The "process of excluding" is a process of "excluding from inspection" with respect to a specific area in the read data provided by the sensor <NUM>, more specifically, a process of "excluding a specific area in the read data provided by the sensor <NUM> from inspection. " In other words, the image reading device <NUM> performs setting for masking part of the read image data <NUM>. Note that the "process of excluding" may be referred to as "excluding from inspection" or "masking.

In the following description, a given area excluded from an area to be inspected may be referred to as a "first area. " An area obtained by excluding the first area from the area to be inspected may be referred to as a "second area" as an area to be inspected or an inspection target area.

The first area and the second area are preferably set depending on, e.g., the state of the sheet S being conveyed. For example, in part (a) of <FIG>, the first area is the leading end area <NUM>. In part (d) of <FIG>, the first area is the trailing end area <NUM>.

As described above, preferably, the area that is likely to flap in the sheet S is excluded depending on the state of the sheet S being conveyed and the second area, which is an area other than the area excluded, is inspected. Setting the first area depending on the state of the sheet S being conveyed as described above further enhances the inspection accuracy.

Alternatively, the first area may be set depending on the existence of an image, for example. Depending on the input image data <NUM>, an image such as a character is not formed in an area of the sheet S. In other words, such an area includes no image. In such a case, the area without an image such as a character may be set as the first area.

Alternatively, an area such as a margin may be set as the first area. In other words, the first area may include an area in which no image is formed.

The image reading device <NUM> may thus reduce the area to be inspected to perform inspection at high speed.

The image reading device <NUM> may use the area without an image such as a character to inspect whether the contamination with, e.g., toner or ink occurs.

The sizes of the leading end area <NUM> and the trailing end area <NUM> may change depending on, e.g., the type of the sheet S. For example, the degree of flapping varies depending on the hardness of the sheet S. For this reason, in a case where the sheet S is likely to flap because of the sheet type, the leading end area <NUM> and the trailing end area <NUM> may be relatively large.

In a case where the reading position is apart from the position at which the sheet S is gripped, the reading accuracy is likely to be worse due to the influence of flapping.

For this reason, the range set as the first area may be changed based on, e.g., the position of the sheet S with respect to the reading position or the type of the sheet S. Such a change enhances an accurate exclusion of an area that is difficult to read.

Note that the image reading device <NUM> stably conveys the sheet S with the sandwiching conveyors. Accordingly, the image reading device <NUM> including the sandwiching conveyors performs the inspection with high accuracy. As the image reading device <NUM> includes the multiple sandwiching conveyors that hold the sheet S at multiple positions, the image reading device <NUM> conveys the sheet S more stably than an image reading device that includes a single sandwiching conveyor. The position, number, and shape of the sandwiching conveyors are not limited to those exemplified.

Referring now to <FIG>, a description is given of some comparative examples.

<FIG> is a diagram illustrating a first comparative example.

For example, in the first comparative example, a specific image <NUM> indicated by the input image data <NUM> is set in advance as an area to be excluded from the inspection.

<FIG> is a diagram illustrating a second comparative example.

For example, in the second comparative example, an end portion <NUM> indicated by the input image data <NUM> is set in advance as an area to be excluded from the inspection.

In the first comparative example and the second comparative example, the flapping or twisting of a recording medium may hamper an accurate inspection.

Referring now to <FIG>, a description is given of a second embodiment of the present disclosure.

<FIG> is a diagram illustrating a third sandwiching conveyor.

A description is now given, as an example, of the image reading device <NUM> and the post-processing device <NUM> illustrated in <FIG>. For example, the image reading device <NUM> preferably changes, e.g., area setting or the determination criterion in the inspection in consideration of peripheral devices such as the post-processing device <NUM>.

Specifically, in the present example, the post-processing device <NUM> includes a third roller pair <NUM> serving as the third sandwiching conveyor.

The sheet S is susceptible to a shock when the leading end of the sheet S enters the third roller pair <NUM>. In other words, for example, the sheet S is likely to be deformed during the reading performed by the sensor <NUM> when the leading end of the sheet S is conveyed to the third roller pair <NUM>.

In particular, when the force for conveying the sheet S changes between the image reading device <NUM> and the post-processing device <NUM>, the sheet S is susceptible to a greater shock. For example, when the roller pairs included in the image reading device <NUM> and the post-processing device <NUM> have different rotational speeds, the sheet S is susceptible to a greater shock. In other words, in a case where the conveyance speed of the sheet S is different from the conveyance speed at which the leading end of the sheet S is sandwiched and conveyed by the third roller pair <NUM> when the leading end of the sheet S enters the third roller pair <NUM>, the conveyance speed varies between the leading end portion of the sheet S and the other portion of the sheet S. As a result, the entire sheet S may be affected by a shock when the sheet S enters the third roller pair <NUM>. This shock tends to deform the sheet S, for example.

The post-processing device <NUM> is changeable to various models. For this reason, the distance between a reading position <NUM> and a downstream gripping position <NUM>, which is a position at which the sheet S is gripped by the third roller pair <NUM>, may change depending on, e.g., the model of a peripheral device.

For example, Table <NUM> below presents some combinations of a first distance <NUM> and a second distance <NUM>. The first distance <NUM> is a distance between the entrance of the post-processing device <NUM> in the conveyance direction and the downstream gripping position <NUM>. The second distance <NUM> is a distance between the reading position <NUM> and the exit of the image reading device <NUM> in the conveyance direction.

In the example presented in Table <NUM> above, the post-processing device <NUM> is classified into three types: "first peripheral device," "second peripheral device," and "third peripheral device.

Now, a description is given of a case in which the timing when the sheet S is conveyed to the third sandwiching conveyor is set by distance.

Alternatively, for example, the timing when the sheet S is conveyed to the third sandwiching conveyor may be set by time.

In Table <NUM> above, the "invalid area" indicates examples of set areas for which the inspection is invalidated. The "invalid area" is, e.g., a value obtained by adding the first distance and the second distance, in other words, a value obtained by calculating the distance between the reading position <NUM> and the downstream gripping position <NUM>. Specifically, the "invalid area" is calculated as "<NUM> + <NUM> = <NUM>" for the "first peripheral device.

The "invalid area" also includes certain areas before and after a center distance. In the example of Table <NUM> above, "±<NUM>" is included in the "invalid area. " Accordingly, the "invalid area" is "<NUM> ± <NUM>" for the "first peripheral device.

The "invalid area" is set for an area that is inspected when the sheet S is susceptible to a shock by a peripheral device. Since the sheet S is susceptible to some failures when the sheet S is susceptible to a shock, the inspection is invalidated. In other words, the image reading device <NUM> stops the inspection of the "invalid area" or ignores an abnormality detected in the inspection of the "invalid area.

Note that the criterion for determining the abnormality may be changed for the invalidation of the inspection. For example, the inspection for the "invalid area" may be performed based on a criterion different from a criterion for other areas. Specifically, when the tint is inspected, the tint may be determined normal in the inspection for the "invalid area" though the difference between an ideal color and a color inspected is larger than that in the other areas.

When the shape of the sheet S is inspected, a sub-scanning magnification of an image to be inspected may change because the sheet S is conveyed slowly or quickly. As a result, the image may be determined abnormal in the inspection. For this reason, the criterion for the image reading device <NUM> to determine the abnormality in the "invalid area" is preferably looser than that in the other areas.

Thus, invalidating the inspection in consideration of the third sandwiching conveyor reduces erroneous detection.

In the example of Table <NUM> above, the "invalid area" is set based on the position of the third roller pair <NUM>. Alternatively, for example, the "invalid area" may be set based on the entrance of the post-processing device <NUM> in the conveyance direction.

The determination criterion for the inspection is set by, e.g., a graphical user interface (GUI) described below.

<FIG> is a diagram illustrating a setup screen.

For example, the determination criterion for the inspection is set by a user operation on a setup screen <NUM>. The setup screen <NUM> includes, e.g., an inspection setting button <NUM>, a reference image setting button <NUM>, and a determination criterion setting button <NUM>.

The inspection setting button <NUM> is a GUI that receives an operation of determining whether to perform an inspection.

The reference image setting button <NUM> is a GUI with which an image as a reference for the inspection, which is the input image data <NUM>, is set.

The determination criterion setting button <NUM> is a GUI with which a determination criterion for the inspection is set. In the example illustrated in <FIG>, the determination criterion for the inspection is selected from three levels of "loose," "normal," and "strict.

Note that the number of levels from which the determination criterion for the inspection is selected is not limited to three. The determination criterion for the inspection thus set prevents erroneous detection of, e.g., fiber of the sheet S.

To enhance the user-friendliness, a variable area in which different images such as different addresses are formed for multiple sheets S may be excluded from the inspection.

For the items set as described above, the abnormality such as contamination or image missing is inspected. The inspected sheet S is discharged to, e.g., a given tray. When the image on the sheet S is determined as abnormal in the inspection, the image forming device <NUM> may form an image on a sheet S other than the sheet S bearing the abnormal image. In short, the image forming device <NUM> may perform so-called recovery printing.

Note that the screen for setting is not limited to the configuration of the setup screen <NUM>. In other words, the determination criterion for the inspection may be set by another setting way other than the way of setting through the setup screen <NUM>.

Now, a description is given of a third embodiment of the present disclosure.

<FIG> is a diagram illustrating a fourth sandwiching conveyor.

A description is now given, as an example, of the image reading device <NUM> and the image forming device <NUM> illustrated in <FIG>. For example, the image reading device <NUM> preferably changes, e.g., area setting or the determination criterion in the inspection in consideration of peripheral devices such as the image forming device <NUM>.

The image reading device <NUM> may inspect the sheet S bearing an image formed by a device other than the image forming device <NUM>. The device located upstream from the image reading device <NUM> in the conveyance direction may be another type of device other than the image forming device <NUM>.

Specifically, in the present example, the image forming device <NUM> includes a fourth roller pair <NUM> serving as a fourth sandwiching conveyor.

Like the second embodiment, the sheet S is susceptible to a shock when the trailing end of the sheet S passes through the fourth roller pair <NUM>. In other words, for example, the sheet S is likely to be deformed during the reading performed by the sensor <NUM> when the trailing end of the sheet S is conveyed from the fourth roller pair <NUM>.

In particular, when the force for conveying the sheet S changes between the image reading device <NUM> and the image forming device <NUM>, the sheet S is susceptible to a greater shock. For example, when the roller pairs included in the image reading device <NUM> and the image forming device <NUM> have different rotational speeds, the sheet S is susceptible to a greater shock.

The image forming device <NUM> is changeable to various models. For this reason, the distance between an upstream gripping position <NUM>, which is a position at which the sheet S is gripped by the fourth roller pair <NUM>, and the exit of the image forming device <NUM> in the conveyance direction may change depending on, e.g., the model of a peripheral device.

For example, Table <NUM> below presents some combinations of a third distance <NUM> and a fourth distance <NUM>. The third distance <NUM> is a distance between the upstream gripping position <NUM> and the exit of the image forming device <NUM> in the conveyance direction. The fourth distance <NUM> is a distance between the entrance of the image reading device <NUM> in the conveyance direction and the reading position <NUM>.

In the example presented in Table <NUM> above, the image forming device <NUM> or another type of device is classified into three types: "fourth peripheral device," "fifth peripheral device," and "sixth peripheral device.

Now, a description is given of a case in which the timing when the sheet S is conveyed from the fourth sandwiching conveyor is set by distance. Alternatively, for example, the timing when the sheet S is conveyed from the fourth sandwiching conveyor may be set by time.

In Table <NUM> above, the "invalid area" indicates examples of set areas for which the inspection is invalidated. The "invalid area" is, e.g., a value obtained by adding the third distance and the fourth distance, in other words, a value obtained by calculating the distance between the upstream gripping position <NUM> and the reading position <NUM>. Specifically, the "invalid area" is calculated as "<NUM> + <NUM> = <NUM>" for the "fourth peripheral device.

The "invalid area" also includes certain areas before and after a center distance. In the example of Table <NUM> above, "±<NUM>" is included in the "invalid area. " Accordingly, the "invalid area" is "<NUM> ± <NUM>" for the "fourth peripheral device.

The "invalid area" is an area that is inspected when the sheet S is susceptible to a shock by a peripheral device.

Since the sheet S is susceptible to some failures when the sheet S is susceptible to a shock, the inspection is invalidated. In other words, the image reading device <NUM> stops the inspection of the "invalid area," ignores an abnormality detected in the inspection of the "invalid area," or changes the criterion for determining the abnormality for the "invalid area.

Thus, invalidating the inspection in consideration of the fourth sandwiching conveyor reduces erroneous detection.

Now, a description is given of a fourth embodiment of the present disclosure.

<FIG> is a diagram illustrating a configuration for duplex printing.

In a case where an image is formed on each side of the sheet S, after an image is formed on one side, as a front side, of the sheet S, e.g., the sensor <NUM> inspects the front side bearing the image as illustrated in <FIG>. When the inspection is finished, the sheet S is reversed so that another image is formed on a back side of the sheet S, which is another side different from the front side of the sheet S, and that the sensor <NUM> inspects the back side of the sheet S. In the following description, a "reversing passage" refers to a conveyance passage for reversing the front and back sides of the sheet S.

When the duplex printing is performed, in other words, when the front and back sides of the sheet S are reversed, the conveyance direction includes a first direction S1, a second direction S2, a third direction S3, and a fourth direction S4.

Specifically, the first direction S1 is a direction in which the sheet S is conveyed at a position upstream from the first sandwiching conveyor in the conveyance direction. On the other hand, the second direction S2 is a direction in which the first sandwiching conveyor conveys the sheet S from the first sandwiching conveyor.

When the duplex printing is performed, the first direction S1 is different from the second direction S2. Specifically, in the example illustrated in <FIG>, the first direction S1 is a direction in which the sheet S is conveyed from right to left in <FIG>. On the other hand, the second direction S2 is a direction in which the sheet S is conveyed from top to bottom in <FIG>. Thus, when the duplex printing is performed, the first direction S1 is different from the second direction S2.

The third direction S3 is a direction in which the sheet S is conveyed at a position downstream from the second sandwiching conveyor in the conveyance direction. On the other hand, the fourth direction S4 is a direction in which the second sandwiching conveyor conveys the sheet S from the second sandwiching conveyor.

When the duplex printing is performed, the third direction S3 is different from the fourth direction S4. Specifically, in the example illustrated in <FIG>, the third direction S3 is a direction in which the sheet S is conveyed from left to right in <FIG>. In other words, the third direction S3 is a direction toward a device that performs processing such as image formation to form an image on the back side of the sheet S. On the other hand, the fourth direction S4 is a direction in which the sheet S is conveyed from top to bottom in <FIG>. Thus, when the duplex printing is performed, the third direction S3 is different from the fourth direction S4.

The image forming apparatus <NUM> conveys the sheet S through, e.g., a conveyance passage having a curvature as illustrated in <FIG> to turn over the sheet S from the front side to the back side. The conveyance passage having a curvature is, e.g., a conveyance passage for reversing the sheet S. Note that the curvature and shape of the conveyance passage are not limited to those illustrated in <FIG>. For example, the conveyance passage having a curvature may be a conveyance passage that is used in a case where the height of conveyance position is different between the image forming device <NUM> and a peripheral device.

The sheet S is conveyed in the third direction S3 through the reversing passage. At this time, part of the sheet S tends to jump up or be lifted up in <FIG> near the sensor <NUM>. As a result, the distance between the sheet S and the sensor <NUM> decreases. In particular, after passing through the first roller pair <NUM>, the sheet S is likely to jump up.

When the distance between the sheet S and the sensor <NUM> changes as described above, e.g., the brightness changes and the appearance on the image may change. Such a change in color may cause the image reading device <NUM> to erroneously detect an abnormality.

When the first direction S1 is different from the second direction S2 or when the third direction S3 is different from the fourth direction S4, for example, the image reading device <NUM> stops the inspection, ignores an abnormality detected in the inspection, or changes the criterion for determining the abnormality, to prevent erroneous detection.

When the reversing passage is thus taken into consideration, the image reading device <NUM> reduces erroneous detection.

The jumping of the sheet S varies depending on the type of the sheet S.

Specifically, when the sheet S is hard or thick, the sheet S is likely to jump up. In other words, the influence tends to be large. By contrast, when the sheet S is soft or thin, the sheet S is likely to be deformed along the reversing passage.

For this reason, the image reading device <NUM> preferably changes the criterion for determining the abnormality in consideration of the thickness, weight, or type of the sheet S. For example, the image reading device <NUM> changes the criterion for determining the abnormality depending on whether the sheet S is a film medium such as an overhead projector (OHP) sheet or a metallic sheet.

Now, a description is given of an example of setting a determination criterion based on a learning result.

The following setting is performed in advance to set a criterion for the image reading device <NUM> to determine whether the inspection result is normal or abnormal.

<FIG> is a graph illustrating an example of acquiring a sheet level.

Now, a description is given of a case in which the image reading device <NUM> obtains a first reading result <NUM> and a second reading result <NUM> when reading two types of sheets S. The image reading device <NUM> reads the sheets S conveyed before image formation.

The image reading device <NUM> averages the first reading result <NUM> in a main scanning direction to obtain a first average value <NUM>.

The image reading device <NUM> averages the second reading result <NUM> in the main scanning direction to obtain a second average value <NUM>.

As indicated by the first reading result <NUM> and the second reading result <NUM>, the brightness is different between the types of the sheets S. For this reason, preferably, the normal sheet level is separately set for each type of the sheets S such as the first average value <NUM> or the second average value <NUM>.

For example, the image reading device <NUM> calculates an average value such as the first average value <NUM> or the second average value <NUM> to obtain a reference value. As described above, since the value of, e.g., the brightness is different between the types of the sheets S, the brightness of, e.g., characters formed is also different between the types of the sheets S. For this reason, the criterion for determining whether the inspection result is normal or abnormal is preferably set based on the value acquired in advance for each type of the sheets S.

<FIG> is a diagram illustrating an example of change in brightness.

Now, a description is given of a case in which the image reading device <NUM> reads the brightness of the sheet S and obtains a reading result as illustrated in <FIG>. Specifically, the result of reading the sheet S includes a dark area <NUM> and a bright area <NUM>, which are a relatively dark area and a relatively bright area, respectively.

The dark area <NUM> and the bright area <NUM> occur due to, e.g., a change in the distance between the sheet S and the sensor <NUM>. Specifically, the dark area <NUM> is an area where the brightness is lower than an average. By contrast, the bright area <NUM> is an area where the brightness is higher than the average.

<FIG> is a graph illustrating a reading result.

When the brightness changes as illustrated in <FIG>, the read values are averaged in the main scanning direction. The reading result exhibits a distribution described below, for example.

The image reading device <NUM> reads the dark area <NUM> and obtains a first read value <NUM> that is lower than the average.

The image reading device <NUM> reads the bright area <NUM> and obtains a second read value <NUM> that is higher than the average.

Now, a description is given of a case in which a range to be determined as normal is set to a normal range <NUM> in advance with respect to the reading result described above. For example, the normal range <NUM> is determined by, e.g., an allowable value set in advance with respect to the average.

Since the normal range <NUM> is determined by, e.g., the average, the influence of changes in brightness between different types of the sheets S is reduced. On the other hand, the read value may be outside the normal range <NUM> due to rapid changes such as the first read value <NUM> and the second read value <NUM>. Such a read value may cause the image reading device <NUM> to erroneously detect the abnormality despite of no contamination.

To prevent such a situation, the criterion for determining whether the inspection result is normal or abnormal is desirably set based on a result of learning the reading result in advance. The learning may be performed separately according to, e.g., the type, size, and thickness of the sheet S. For example, the learning is implemented by artificial intelligence (AI).

<FIG> is a diagram illustrating a normal range set based on a learning result.

The normal range <NUM> illustrating <FIG> is different from the normal range <NUM> illustrated in <FIG> around the first read value <NUM> and the second read value <NUM>.

In the present example, the background is black. The brightness as illustrated in <FIG> is acquired by, e.g., a line sensor. The boundary between the sheet S and the background is determined by, e.g., the difference in brightness of reflected light. The area of the sheet S is thus specified.

The learning is performed so as not to determine a rapidly changing read value such as the first read value <NUM> or the second read value <NUM> as an abnormality. Specifically, the image reading device <NUM> scans the sheet S to acquire the profile in advance. With such a profile acquired, the image reading device <NUM> learns a change in brightness, for example. The image reading device <NUM> performs setting to widen the normal range based on the learning result as illustrated in <FIG>. Accordingly, the image reading device <NUM> reduces erroneous detection.

The image reading device <NUM> may change the determination criterion as described below, based on the learning result.

<FIG> is a graph illustrating an example of changing the determination criterion based on a learning result.

Now, a description is given of a case in which the same result as the result illustrated in <FIG> is obtained.

A first read area <NUM> refers to an area in the vicinity where the first read value <NUM> is obtained. A second read area <NUM> refers to an area in the vicinity where the second read value <NUM> is obtained. A third read area <NUM> refers to an area that is neither the first read area <NUM> nor the second read area <NUM>.

Based on the learning result, the image reading device <NUM> performs determination for the first read area <NUM> and the second read area <NUM> based on a criterion different from a criterion for the third read area <NUM>. Specifically, the image reading device <NUM> inspects the first read area <NUM> and the second read area <NUM> at an inspection level different from an inspection level for the third read area <NUM>.

A specific area may be often subjected to erroneous detection compared to the overall average. In the following description, an area that is often subjected to erroneous detection may be referred to as a "specific area. " In other words, the inspection result of the specific area tends to be poor compared with the inspection result of an area other than the specific area.

For example, the specific area may be determined or presumed by a mechanical layout. In other words, the specific area may be often specified at, e.g., a designing stage. For this reason, the image reading device <NUM> stores, in advance, the specific area specified in, e.g., design, in the memory. For example, the image reading device <NUM> stores the specific area in the form of table data.

The image reading device <NUM> may change the criterion according to the specific area. Specifically, the image reading device <NUM> sets the inspection level to "<NUM>%" for an area of <NUM> from the leading end of the sheet S. On the other hand, the image reading device <NUM> sets the inspection level to "<NUM>%" for the other areas. The image reading device <NUM> thus sets the criterion for the specific area to be lower than the criterion for an area other than the specific area.

When calculating the average, for example, the image reading device <NUM> may exclude the specific area.

The image reading device <NUM> performs such an inspection based on the specific area to reduce erroneous detection.

Now, a description is given of an example of disposing a guide.

The image reading device <NUM> preferably includes a guide <NUM>. For example, the guide <NUM> is disposed at a position illustrated in <FIG>, <FIG>, or <FIG>. The guide <NUM> thus disposed restrains flapping of the sheet S. Since the sheet S is conveyed stably with the guide <NUM>, the image reading device <NUM> performs an accurate inspection.

Now, a description is given of some modifications.

<FIG> is a diagram illustrating an image reading device according to a first modification. Specifically, <FIG> is a side view of the image reading device according to the first modification. The image reading device <NUM> may have a configuration described below.

The image reading device <NUM> includes a plurality of imaging elements 11a, an irradiator 11b, and a platen <NUM>. The image reading device <NUM> further includes a revolver <NUM>, a first conveyance roller pair <NUM>, and a second conveyance roller pair <NUM>.

The irradiator 11b irradiates a sheet material passing through a reading position with light.

The imaging elements 11a performs photoelectric conversion for each pixel to generate image data. The imaging elements 11a are one-dimensionally aligned in a direction perpendicular to the conveyance direction to form a line image sensor.

The revolver <NUM> is positioned to face the imaging elements 11a across the conveyance passage. The revolver <NUM> reflects irradiation light with which the sheet material is irradiated at the time of image reading.

The platen <NUM> is positioned to face the revolver <NUM>. The platen <NUM> is a transparency. The platen <NUM> transmits emitted light, light reflected by the revolver <NUM>, and light reflected by the sheet material.

The first conveyance roller pair <NUM> and the second conveyance roller pair <NUM> are rotated by a drive motor. In the cleaning, for example, the first conveyance roller pair <NUM> and the second conveyance roller pair <NUM> may have different conveyance speeds.

<FIG> is a diagram illustrating an image forming apparatus according to a second modification. The image forming apparatus <NUM> including the image reading device <NUM> may have a configuration described below.

The image forming apparatus <NUM> includes a control device <NUM> that controls an overall operation of the image forming apparatus <NUM> to control a process of forming an image on the sheet S. The control device <NUM> may include, e.g., a cleaning control device.

The image forming apparatus <NUM> further includes drum-shaped photoconductors <NUM> to form images with image forming material such as toner in different colors of yellow (Y), magenta (M), cyan (C), and black (K). For example, the photoconductors <NUM> are disposed along an intermediate transfer belt <NUM>.

The intermediate transfer belt <NUM> is entrained around a driving roller and a plurality of driven rollers. Images developed as toner images on the photoconductors <NUM> are transferred onto the intermediate transfer belt <NUM> to form a composite toner image. The intermediate transfer belt <NUM> moves between a primary transfer position and a secondary transfer position at which the composite toner image is transferred onto the sheet S.

The image forming apparatus <NUM> further includes a transfer roller 113a and an opposed roller 113b at the secondary transfer position. At the secondary transfer position, the composite toner image is transferred from the intermediate transfer belt <NUM> onto the sheet S. A gap is formed between the transfer roller 113a and the opposed roller 113b, allowing the intermediate transfer belt <NUM> and the sheet S to be sandwiched between the transfer roller 113a and the opposed roller 113b and the sheet S to pass through the gap. The image is transferred onto the sheet S conveyed through the gap in the conveyance direction, which is a sub-scanning direction, while being sandwiched between the transfer roller 113a and the opposed roller 113b.

The sheet S is fed from a first feed tray 121A or a second feed tray 121B.

The sheet S bearing the image on the front side is conveyed to a fixing roller pair <NUM>, which fixes the image onto the front side of the sheet S. After the fixing, the sheet S is conveyed to a conveyance passage switching device <NUM>, which reverses the traveling direction of the sheet S. Thereafter, the sheet S is conveyed to a reversing path <NUM>. After the sheet S is conveyed along the reversing path <NUM>, another image is formed on the back side of the sheet S. Like the front side of the sheet S, the back side of the sheet S is subjected to the fixing and the inspection.

<FIG> is a diagram illustrating an image forming apparatus according to a third modification. The image forming apparatus <NUM> illustrated in <FIG> is different from the image forming apparatus <NUM> illustrated in <FIG> in the configuration of the image reading device <NUM>.

<FIG> is a diagram illustrating a first-side reader and a second-side reader included in the image reading device <NUM> of <FIG>. Specifically, a first-side reader 130a is a downstream reader in the conveyance direction; whereas a second-side reader 130b is an upstream reader in the conveyance direction.

Now, a description is given of a case in which the first-side reader 130a and the second-side reader 130b have substantially the same hardware configuration.

The first-side reader 130a includes the imaging elements 11a, the irradiator 11b, the revolver <NUM>, the first conveyance roller pair <NUM>, and the second conveyance roller pair <NUM>.

The first-side reader 130a reads an image in synchronization with the movement of the sheet S passing through the reading position. In the example illustrated in <FIG>, the first-side reader 130a reads an image formed on the front side of the sheet S; whereas the second-side reader 130b reads an image formed on the back side of the sheet S.

The revolver <NUM> reflects irradiation light with which the sheet S is irradiated at the time of image reading.

The first conveyance roller pair <NUM> includes a first driving roller 14a that rotates to convey the sheet S.

The second conveyance roller pair <NUM> includes a second driving roller 15a that rotates to convey the sheet S.

The first-side reader 130a preferably includes the guide <NUM>.

The image reading device <NUM> includes the first-side reader 130a and the second-side reader 130b. The first-side reader 130a and the second-side reader 130b allows the image reading device <NUM> to read the front and back sides of the sheet S almost simultaneously.

In another example, the first-side reader 130a may be disposed upstream in the conveyance direction; whereas the second-side reader 130b may be disposed downstream in the conveyance direction.

Now, a description is given of a functional configuration.

<FIG> is a diagram illustrating a functional configuration of the image reading device <NUM>.

For example, the image reading device <NUM> includes, e.g., an image reading unit 30F1, an output unit 30F2, and a setting unit 30F3. The image reading device <NUM> may further include, e.g., a transmission unit 30F4, an operation unit 30F5, and a learning unit 30F6.

The image reading unit 30F1 performs an image reading procedure to read an image on a recording medium. For example, the image reading unit 30F1 is implemented by the sensor <NUM>.

The output unit 30F2 performs an output procedure to inspect the image and output an inspection result, based on the second area. For example, the output unit 30F2 is implemented by the CPU <NUM>.

The setting unit 30F3 performs a setting procedure to exclude the first area from an area to be inspected, based on the type of the recording medium or the position of the recording medium with respect to the reading position, to set or determine the second area. For example, the setting unit 30F3 is implemented by the CPU <NUM>.

The transmission unit 30F4 performs a transmission procedure to transmit the inspection result to, e.g., the operation unit 30F5 or a display terminal <NUM>. For example, the transmission unit 30F4 is implemented by a communication device.

The operation unit 30F5 performs an operation procedure to receive an operation from a user or output a screen for the user. For example, the operation unit 30F5 is implemented by the operation display <NUM>.

The learning unit 30F6 performs a learning procedure to learn a reading result. For example, the learning unit 30F6 is implemented by the CPU <NUM>.

The display terminal <NUM> is an information processor such as a tablet or a personal computer (PC) that is connected via a network or a cable.

The image reading device <NUM> excludes the first area from the area to be inspected to determine the second area. The image reading device <NUM> performs an inspection based on the second area thus determined, to prevent erroneous detection in the image inspection.

Now, a description is given of an overall process.

<FIG> is a flowchart of an overall process.

In step S2001, the image reading device <NUM> excludes the first area from an area to be inspected and determines the second area to be inspected.

In step S2002, the image reading device <NUM> reads an image formed on a recording medium.

In step S2003, the image reading device <NUM> inspects the image and outputs an inspection result, based on the second area.

Now, a description is given of some other embodiments of the present disclosure.

The image forming apparatus is not limited to the configurations described above. For example, the image forming apparatus may include devices other than the devices described above. In addition, the arrangement of the devices may be other than the arrangements illustrated in the drawings.

The recording medium may be other than the sheet S, which is a sheet of plain paper. Alternatively, for example, the recording medium may be a sheet of coated paper, a sheet of label paper, an overhead projector sheet, a film, or a flexible thin plate. In other words, the recording medium is made of, e.g., a material to which ink droplets are at least temporarily adherable, a material to which ink droplets adheres and are fixed, or a material to which ink droplets adheres and permeate. Specific examples of a recording material or formation made of such a material include, but are not limited to, a recording medium such as a sheet, a film, or cloth, an electronic component such as an electronic substrate or a piezoelectric element, which may be referred to as a piezoelectric component, layered powder, an organ model, and a testing cell. In short, the recording medium is made of any material to which liquid is adherable, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramic, or a combination thereof.

The device may be a plurality of devices. In other words, each device may have a configuration in which a plurality of devices perform processing in a distributed manner, in a redundant manner, or in parallel. On the other hand, each device may be integrated. In other words, the plurality of devices described above may be implemented by one device.

The image reading method as described above may be implemented by an image reading program. In other words, the image reading program causes devices such as an arithmetic device, a control device, and a storage device included in a computer to operate in cooperation with each other to implement the image reading method. The image reading program may be distributed via, e.g., a computer-readable recording medium or an electric communication line.

Claim 1:
An image reading device (<NUM>) comprising:
an image reading unit (30F1) configured to read an image on a recording medium;
an output unit (30F2) configured to inspect the image and output an inspection result; and
a setting unit (30F3) configured to exclude an area of the recording medium as a first area from an area to be inspected by the output unit (30F2), based on a type of the recording medium or a position of the recording medium with respect to a reading position at which the image reading unit (30F1) reads the image, to determine a second area to be inspected,
the output unit (30F2) being configured to output the inspection result based on the second area;
characterized in that the image reading device (<NUM>) further comprises:
a first sandwiching conveyor (<NUM>) configured to sandwich and convey the recording medium at a position upstream from the image reading unit (30F1) in a recording medium conveyance direction; and
a second sandwiching conveyor (<NUM>) configured to sandwich and convey the recording medium at a position downstream from the image reading unit (30F1) in the recording medium conveyance direction,
wherein the output unit (30F2) is configured to output the inspection result based on the second area in response to one of the first sandwiching conveyor (<NUM>) and the second sandwiching conveyor (<NUM>) sandwiching the recording medium.