Patent Description:
The present disclosure relates to a recording apparatus, a recording/reading system and a recording method.

By optically reading the recorded material output by a printer with a reading apparatus, the color, density, etc. of the recorded material can be obtained and evaluated. At this time, if foreign matter such as dust adheres to the reading apparatus, the reading result of the foreign matter is incorporated into the data as the reading result of the recorded material, and the recorded material cannot be accurately read.

<CIT> discloses an imaging apparatus that reads the same side of the same sheet after image formation inline with a colorimeter capable of reading only a part of the area in the main scanning direction and a line sensor capable of reading over the width of the image formation in the main scanning direction, and the imaging apparatus has a configuration that detects the presence or absence of abnormal values based on the read information read by the line sensor, and displays a message urging the user to clean the line sensor and colorimeter when abnormal values are detected at the same location in the main scanning direction where the abnormal values were detected for a predetermined number of times or more (see <CIT>).

<CIT> requires a line sensor to clean foreign matter adhering to the colorimeter, and increases cost due to the provision of two sensors for image reading. In view of this situation, there is a need for a technique that can help detect foreign matter adhering to the sensor for image reading while controlling costs.

<CIT> discloses droplet ejection control apparatus. Droplet ejection amounts are adjusted during a process of generating raster data, and this process is realized by a control circuit. The sum total of droplet ejection amounts exceeds <NUM>% as for three nozzles while the sum total of droplet ejection amount is below <NUM>% as for one nozzle, which is repeated at some nozzle numbers. The sum total of droplet ejection amounts is <NUM>% in a normal portion. As such, in the case where this sum total is taken as a reference amount, the sum total of droplet ejection amounts for each raster in a region where overlap printing is performed is sequentially changed to be equal to or greater than the reference amount in the normal region where the overlap printing is not performed, and to be equal to or smaller than the above reference amount.

<CIT> discloses a method of judging whether or not darkness of a foreign matter on a test pattern printed on a medium with predetermined darkness has been read at the time of reading the darkness of the test pattern using a reading section, which includes: detecting a section in the test pattern for which an amount of deviation, from a predetermined reference value, of a readout value on the darkness of that section exceeds a predetermined darkness-deviation threshold which is a threshold adopted for the deviation in darkness; and judging whether or not the darkness of the foreign matter has been read based on a size of the above-mentioned section that has been detected.

According to a first aspect of the present invention, there is provided a recording/reading system according to claim <NUM>.

According to a second aspect of the present invention, there is provided a recording/reading system according to claim <NUM>.

According to a third aspect of the present invention, there is provided a control method of a recording/reading system according to claim <NUM>.

According to a fourth aspect of the present invention, there is provided a control method of a recording/reading system according to claim <NUM>.

An embodiment of the present disclosure is described below with reference to the drawings. Note that the drawings are merely examples for describing the embodiment. Since the drawings are examples, they may be provided with incorrect proportions and shapes, may mismatch each other, and may be partially omitted.

<FIG> is a diagram schematically illustrating a configuration of a recording/reading system <NUM> of the embodiment. The recording/reading system <NUM> may be referred to as foreign matter detection system <NUM>, data correction system <NUM> or the like. The recording/reading system <NUM> includes a recording apparatus <NUM> and a reading apparatus <NUM>. The recording apparatus <NUM> executes a recording method of the embodiment.

The recording apparatus <NUM> includes a control unit <NUM>, a display unit <NUM>, an operation reception unit <NUM>, a communication IF <NUM>, a conveyance unit <NUM>, a recording unit <NUM>, a storage unit <NUM> and the like. IF is an abbreviation of interface. The control unit <NUM> includes one or a plurality of ICs including a CPU 11a serving as a processor, a ROM 11b, a RAM 11c and the like, other nonvolatile memories and the like. At the control unit <NUM>, the processor, i.e., the CPU 11a, executes arithmetic processing in accordance with a program <NUM> stored in the ROM 11b, other memories and the like, with the RAM 11c and the like used as a working area.

In accordance with the program <NUM>, the control unit <NUM> implements a plurality of functions such as a record control unit 12a and a data correction unit 12b. These functions are only some of the functions that the program <NUM> causes the control unit <NUM> to implement. Note that the processor is not limited to one CPU, and may have a configuration of performing processing with a plurality of CPUs or a hardware circuit such as an ASIC, or a configuration of performing processing with a CPU and a hardware circuit in conjunction with each other.

The display unit <NUM> is a means for displaying visual information, and is composed of a liquid crystal display, an organic EL display or the like, for example. The display unit <NUM> may have a configuration including a display and a driving circuit for driving the display. The operation reception unit <NUM> is a means for receiving the user operation, and is implemented with physical buttons, touch panel, mouse, keyboard and the like, for example. Naturally, the touch panel may be implemented as one function of the display unit <NUM>. A configuration including the display unit <NUM> and the operation reception unit <NUM> may be referred to as the operation panel of the recording apparatus <NUM>. The display unit <NUM> and/or the operation reception unit <NUM> may be a part of the configuration of the recording apparatus <NUM>, or may be a peripheral device externally attached to the recording apparatus <NUM>.

The communication IF <NUM> is a collective term of one or a plurality of IFs for the recording apparatus <NUM> to communicate with other apparatuses in a wired or wireless manner in compliance with a predetermined communication protocol including publicly known communication standards. In the example illustrated in <FIG>, the recording apparatus <NUM> is connected to the reading apparatus <NUM> through the communication IF <NUM>. The recording apparatus <NUM> may be connected to and communicate with various external apparatuses not illustrated in <FIG> through the communication IF <NUM> as well as the reading apparatus <NUM>.

The conveyance unit <NUM> is a means for conveying a recording medium along a predetermined conveyance direction under the control of the control unit <NUM>, and includes, for example, a roller that conveys a medium through rotation and a motor for driving the roller and the like not illustrated in the drawing. The medium is typically a sheet, but may be materials other than paper as long as recording on the medium with liquid can be performed.

The recording unit <NUM> is a mechanism that performs recording on a medium by ejecting liquid such as ink by an ink-jet system. The recording unit <NUM> includes a recording head <NUM> as described later. The recording head <NUM> includes a plurality of nozzles <NUM> for ejecting liquid, and ejects the liquid from each nozzle <NUM> to a medium <NUM> being conveyed by the conveyance unit <NUM> under the control of the control unit <NUM>. The droplet ejected by the nozzle <NUM> is also referred to as dot. The recording head <NUM> may be referred to as liquid ejection head, printing head, print head, ink-jet head and the like.

The storage unit <NUM> is a storage means composed of a hard disk drive, a solid-state drive, and/or other memories, for example. A part of the memory provided in the control unit <NUM> may be regarded as the storage unit <NUM>. The storage unit <NUM> may be regarded as a part of the control unit <NUM>.

The reading apparatus <NUM> includes a control unit <NUM>, a communication IF <NUM>, a conveyance unit <NUM>, a reading unit <NUM>, a display unit <NUM> and the like. As with the control unit <NUM>, the control unit <NUM> includes a processor, a memory, a program and the like mounted therein, which control the reading apparatus <NUM> in conjunction with each other. The communication IF <NUM> is a collective term of one or a plurality of IFs for the reading apparatus <NUM> to communicate with other apparatuses in a wired or wireless manner in compliance with a predetermined communication protocol including publicly known communication standards. In the example illustrated in <FIG>, the communication IF <NUM> is connected to the communication IF <NUM> of the recording apparatus <NUM>.

As with the display unit <NUM>, the display unit <NUM> is a means for displaying visual information. Naturally, the reading apparatus <NUM> may include an operation reception unit. The conveyance unit <NUM> is a means for conveying the document to be read along a predetermined conveyance direction under the control of the control unit <NUM>, and includes a roller that conveys documents through rotation, a motor for driving the roller and the like not illustrated in the drawing, for example. The medium <NUM> after the recording of the recording apparatus <NUM> becomes a kind of document for the reading apparatus <NUM>. In the following description, a document read by the reading apparatus <NUM> may be referred to as the medium <NUM>.

The reading unit <NUM> is a mechanism for optically reading a document conveyed by the conveyance unit <NUM>. Although details are omitted, the reading unit <NUM> includes a light source for irradiating document, an image sensor that receives reflection light and transmitted light from the document through a predetermined reading surface and generates an electric signal through optoelectronic conversion, an image processing circuit that generates read image data as a reading result of a document by performing predetermined conversion and correction on the electric signal output from the image sensor, and the like. The image processing circuit may be a part of the control unit <NUM>. When foreign matter adheres to the reading surface of the reading unit <NUM> for reading documents and the like, the document cannot be properly read. The image sensor is a line sensor that is long in the width direction of the document, which intersects the document conveyance direction of the conveyance unit <NUM>. The line sensor is composed of a plurality of photoelectric conversion elements aligned along the width direction of the document. The reading apparatus <NUM> described above is a scanner of a sheet feed type.

The control unit <NUM>, the display unit <NUM>, the communication IF <NUM> and the conveyance unit <NUM> of the recording apparatus <NUM>, and the control unit <NUM>, the display unit <NUM>, the communication IF <NUM> and the conveyance unit <NUM> of the reading apparatus <NUM> may be referred to as the first control unit <NUM>, the first display unit <NUM>, the first communication IF <NUM>, the first conveyance unit <NUM>, the second control unit <NUM>, the second display unit <NUM>, the second communication IF <NUM>, and the second conveyance unit <NUM>, respectively, for the sake of distinguishing them.

The recording apparatus <NUM> and the reading apparatus <NUM> may be interpreted as independent apparatuses. In this case, when the user sets the medium <NUM> after the recording at the recording apparatus <NUM> to the conveyance unit <NUM> of the reading apparatus <NUM>, the medium <NUM> after the recording is read by the reading unit <NUM>.

Alternatively, the recording apparatus <NUM> and the reading apparatus <NUM> may be integrally configured. Specifically, the recording/reading system <NUM> may be a single apparatus including the recording apparatus <NUM> and the reading apparatus <NUM>. In this case, the medium <NUM> after the recording at the recording unit <NUM> is continuously conveyed to the reading unit <NUM> and read by the reading unit <NUM>. That is, the reading unit <NUM> may be disposed downstream of the recording unit <NUM> in the conveyance direction in an inline manner.

In the case where the recording apparatus <NUM> and the reading apparatus <NUM> are an integrally configured apparatus, the conveyance unit <NUM> and the conveyance unit <NUM> are substantially an integrated conveyance means, and they are not necessarily required to be distinguished for understanding the embodiment. Likewise, the control unit <NUM> may be interpreted as a part of the control unit <NUM>, and the display unit <NUM> and the display unit <NUM> may be interpreted as the same component.

The following description will be continued without making any particular distinction as to whether the recording apparatus <NUM> and the reading apparatus <NUM> are apparatuses independent of each other, or are an integrated apparatus.

Next, features of the recording head <NUM> and recording of an overlapping region using the recording head <NUM> in the embodiment are described as first to fourth examples.

<FIG> is a diagram schematically illustrating a relationship between the recording head <NUM> and the medium <NUM> and the like according to the first example as viewed from above. In <FIG>, the recording head <NUM> is mounted in a carriage omitted in the illustration. That is, the recording unit <NUM> includes the recording head <NUM> and the carriage. Alternatively, the recording head <NUM> may be interpreted as a configuration including the function of the carriage. The carriage is a mechanism that can move back and forth along a main scanning direction D2 intersecting the conveyance direction D1 of the medium <NUM> of the conveyance unit <NUM> by receiving the power of the motor. Thus, with the carriage, the recording head <NUM> performs a forward movement and a backward movement along the main scanning direction D2. The intersection of the conveyance direction D1 and the main scanning direction D2 may be interpreted as orthogonal. Note that orthogonality is not limited to strict orthogonality, but may be an intersection including errors that may occur in the product.

<FIG> illustrates an arrangement of the nozzle <NUM> in the surface of the recording head <NUM> facing the medium <NUM>. In <FIG>, the circle represents each nozzle <NUM>. In a configuration in which ink of each color is supplied from a liquid holding means called ink cartridge, ink tank and the like not illustrated in the drawing and ejected from the nozzle <NUM>, the recording head <NUM> includes nozzle rows for respective ink colors. <FIG> illustrates a nozzle row <NUM> for ejecting black (K) ink and a nozzle row 23C for ejecting cyan (C) ink. The nozzle row composed of the plurality of nozzles <NUM> that eject the K ink is the nozzle row <NUM>, and the nozzle row composed of the plurality of nozzles <NUM> that eject the C ink is the nozzle row 23C.

Each nozzle row is composed of the plurality of nozzles <NUM> arranged at a constant or substantially constant interval (nozzle pitch) between the nozzles <NUM> in the conveyance direction D1. The direction in which the plurality of nozzles <NUM> making up the nozzle row are arranged is referred to as a nozzle arrangement direction D3. While an example in which the nozzle arrangement direction D3 obliquely intersects the conveyance direction D1 is known as a configuration of the recording head <NUM>, <FIG> illustrates an example in which the nozzle arrangement direction D3 and the conveyance direction D1 are parallel to each other. In <FIG>, a plurality of nozzle rows are arranged along the main scanning direction D2 at the same position in the conveyance direction D1. Here, the nozzle row <NUM> is "first nozzle row", and the nozzle row 23C is "second nozzle row". The recording head <NUM> may naturally include nozzle rows other than the nozzle rows <NUM> and 23C although they are omitted for reasons of space limitation in the drawing. The recording head <NUM> may include a nozzle row for ejecting magenta (M) ink, a nozzle row for ejecting yellow (Y) ink, nozzle rows for ejecting other ink and/or liquid other than ink, and the like, for example.

In <FIG>, the nozzle number is provided to each nozzle <NUM> making up the nozzle row for the sake of description. More specifically, the N nozzles making up one nozzle row are sequentially provided with nozzle numbers, #<NUM>, #<NUM>, #<NUM>. #N, from the downstream side to the upstream side in the conveyance direction D1. In the first example, the positions of the plurality of nozzle rows in the conveyance direction D1 are the same, and therefore the nozzle number is information common to each nozzle row.

In the first example, the control unit <NUM> two-dimensionally records an image on the medium <NUM> based on image data representing an image through a combination of so-called "sheet advancing", which is conveyance of the medium <NUM> from the upstream side to the downstream side in the conveyance direction D1 using the conveyance unit <NUM>, and "scan", which is ink ejection from the recording head <NUM> in conjunction with the forward movement and the backward movement of the recording head <NUM>. In this manner, the recording apparatus <NUM> functions as so-called serial printer. The scan is also referred to as "path". During execution of the scan, the medium <NUM> is stationary. In <FIG>, two recording heads <NUM> are illustrated at two locations. Specifically, the recording head <NUM> executing a certain one path P1 and the recording head <NUM> executing the next path P2 after the path P1 are illustrated. A distance L1 between the recording head <NUM> executing the path P1 and the recording head <NUM> executing the path P2 in the conveyance direction D1 corresponds to the distance of one sheet advancing.

In <FIG>, the recording head <NUM> appears to move upstream in the conveyance direction D1 as the number of paths increases, but in practice, the medium <NUM> moves downstream in the conveyance direction D1 for each sheet advancing and the relative position of the recording head <NUM> and the medium <NUM> changes in the conveyance direction D1. When a certain path is referred to as preceding path, the next path after that certain path is referred to as succeeding path. The path P1 and the path P2 are in the preceding path-succeeding path relationship. Naturally, for the next path after the path P2, the path P2 is a preceding path. In this manner, the path and the sheet advancing are repeated.

In the first example, the line recorded on the medium <NUM> with the main scanning direction D2 as the longitudinal direction is referred to as "raster line". In the state of image data, the raster line is a pixel line of a plurality of pixels aligned in the main scanning direction D2. In addition, on the medium <NUM>, the raster line is a dot line directed in the main scanning direction D2. It should be noted that the length of the raster line is not limited.

When attention is focused on recording with ink of one color, one raster line can be recorded through ink ejection from one nozzle <NUM>, i.e., a single scan, but the control unit <NUM> records some raster lines through a plurality of nozzles <NUM>, i.e., multiple scans. The method of recording the raster line with the plurality of nozzles <NUM> for the ink of one color is referred to as overlapping (hereinafter referred to as OL) recording.

As can be seen from <FIG>, in the first example, the control unit <NUM> performs the OL recording in an overlapping manner on a part of the region recorded in the preceding path in the succeeding path by adjusting the distance L1. More specifically, in <FIG>, the sheet advancing is performed such that recording can be performed in the common regions <NUM> and <NUM> of the medium <NUM> with the nozzle range of the nozzle numbers #N-<NUM> to #N of the recording head <NUM> in the preceding path and the nozzle range of the nozzle numbers #<NUM> to #<NUM> of the recording head <NUM> in the succeeding path. The nozzle range of the nozzle numbers #<NUM> to #<NUM> on the downstream side and the nozzle range of the nozzle numbers #N-<NUM> to #N on the upstream side in the conveyance direction D1 used for the OL recording are referred to as downstream nozzle range and upstream nozzle range, respectively. Naturally, the number of nozzles in the downstream nozzle range and the upstream nozzle range are not limited.

In addition, in the first example, some nozzles <NUM> in the upstream nozzle range of the nozzle row <NUM>, or more specifically the nozzles <NUM> of the nozzle numbers #N-<NUM> to #N are unused nozzles, and some nozzles <NUM> in the downstream nozzle range of the nozzle row 23C, or more specifically the nozzles <NUM> of the nozzle numbers #<NUM> to #<NUM> are unused nozzles. The unused nozzle is the nozzle <NUM> that is not used for the recording, and <FIG> illustrates the unused nozzle with × in the circle representing the nozzle <NUM>. The nozzle <NUM> that is not the unused nozzle ejects ink under the control of the control unit <NUM>.

In such a configuration, attention is focused on ejection of the K ink from the nozzle row <NUM>. A region <NUM> corresponds to "first overlapping region" where each raster line is formed through two scans of the nozzle row <NUM>. For example, a certain one raster line making up the first overlapping region <NUM> is OL-recorded by a first nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row <NUM> in the path P1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row <NUM> in the path P2. The region other than the region <NUM> in the medium <NUM> corresponds to "first normal region" where each raster line is formed through a single scan of the nozzle row <NUM>.

Likewise, attention is focused on ejection of the C ink of the nozzle row 23C. A region <NUM> corresponds to "second overlapping region" where each raster line is formed through two scans of the nozzle row 23C. For example, a certain one raster line making up the second overlapping region <NUM> is OL-recorded by the nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row 23C in the path P1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23C in the path P2. The region other than the region <NUM> in the medium <NUM> corresponds to "second normal region" where each raster line is formed through a single scan of the nozzle row 23C.

That is, the first overlapping region <NUM> overlaps a part of the second normal region and the second overlapping region <NUM> overlaps a part of the first normal region.

In this manner, in the first example, by setting some nozzles <NUM> in the first nozzle row to the unused nozzles in one of the upstream nozzle range and the downstream nozzle range and setting some nozzles <NUM> of the second nozzle row to unused nozzles in the other of the upstream nozzle range and the downstream nozzle range, the first overlapping region <NUM> OL-recorded by the first nozzle row and the second overlapping region <NUM> OL-recorded by the second nozzle row are shifted in the conveyance direction D1. In other words, the first overlapping region <NUM> is formed at a position overlapping the second normal region as viewed in the longitudinal direction of the raster line. In addition, in other words, the second overlapping region <NUM> is formed at a position overlapping the first normal region as viewed in the longitudinal direction.

<FIG> is a diagram schematically illustrating a relationship between the recording head <NUM> and the medium <NUM> and the like according to a second example as viewed from above. The view of <FIG> is the same as <FIG>. As in the first example, in the second example, the recording apparatus <NUM> is a serial printer. In the second example, description common to the first example is omitted. In the second example, the positions of a plurality of nozzle rows <NUM> and 23C provided in the recording head <NUM> are shifted from each other in the conveyance direction D1. In <FIG>, the position of the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row <NUM> and the position of the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23C coincide with each other in the conveyance direction D1. That is, in the second example, the nozzle row <NUM> and the nozzle row 23C are attached by being shifted by three nozzles in the conveyance direction D1.

It can be said that the nozzle rows <NUM> and 23C illustrated in <FIG> have a configuration obtained by only removing the unused nozzles from the nozzle rows <NUM> and 23C illustrated in <FIG>. As such, the number N of nozzles per nozzle row of the nozzle rows <NUM> and 23C illustrated in <FIG> is smaller than the number N of nozzles of <FIG> by three. Thus, by using the recording head <NUM> of <FIG> instead of the recording head <NUM> of <FIG>, the first overlapping region <NUM> and the first normal region can be recorded on the medium <NUM> by the nozzle row <NUM>, and the second overlapping region <NUM> and the second normal region can be recorded on the medium <NUM> by the nozzle row 23C as in first example. That is, the first overlapping region <NUM> OL-recorded by the first nozzle row and the second overlapping region <NUM> OL-recorded by the second nozzle row are recorded in a shifted manner in the conveyance direction D1.

More specifically, in <FIG>, the nozzle range of the nozzle numbers #<NUM> to #<NUM> on the downstream side and the nozzle range of the nozzle numbers #N-<NUM> to #N on the upstream side in the conveyance direction D1 used for the OL recording are set to the downstream nozzle range and the upstream nozzle range, respectively. Then, when attention is focused on ejection of the K ink of the nozzle row <NUM>, a certain one raster line making up the first overlapping region <NUM> is OL-recorded by the nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row <NUM> in the path P1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row <NUM> in the path P2. In addition, when attention is focused on ejection of the C ink of the nozzle row 23C, a certain one raster line making up the second overlapping region <NUM> is OL-recorded by the nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row 23C in the path P1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23C in the path P2.

<FIG> is a diagram schematically illustrating a relationship between the recording head <NUM> and the medium <NUM> and the like according to a third example as viewed from above. While the recording apparatus <NUM> is assumed to be a serial printer in the first example and the second example, the recording apparatus <NUM> is assumed to be a so-called line printer in the third example and the fourth example described later. In the third example, description common to the first example with reference to with reference to <FIG> is appropriately omitted.

In the third example, the recording unit <NUM> does not include a carriage, and the recording head <NUM> does not move. The recording head <NUM> is composed of a plurality of head chips 22a, 22b and 22c coupled along the nozzle arrangement direction D3. In addition, in the third example, the conveyance direction D1 of the medium <NUM> of the conveyance unit <NUM> intersects the nozzle arrangement direction D3. Here, the intersection may also be interpreted as orthogonal or substantially orthogonal. Specifically, the recording head <NUM> is configured such that the length of the recording head <NUM> in the nozzle arrangement direction D3 can cover the width of the medium <NUM> in the nozzle arrangement direction D3.

Naturally, the number of head chips making up the recording head <NUM> may be greater than three illustrated in <FIG>. Each of the head chips 22a, 22b and 22c includes a plurality of nozzle rows as with the recording head <NUM> illustrated in <FIG>. The nozzle rows <NUM> and 23C provided in the head chip 22a are referred to as nozzle rows 23K1 and 23C1. Likewise, the nozzle rows <NUM> and 23C provided in the head chip 22b are referred to as nozzle rows 23K2 and 23C2, and the nozzle rows <NUM> and 23C provided in head chip 22c are referred to as nozzle rows 23K3 and 23C3. In <FIG>, the plurality of nozzle rows in the head chip are arranged along the conveyance direction D1, and their positions in the nozzle arrangement direction D3 are the same.

In <FIG>, nozzle numbers are provided to the nozzles <NUM> making up the nozzle row in the head chip. N nozzles making up one nozzle row in the head chip are sequentially provided with nozzle numbers #<NUM>, #<NUM>, #<NUM>. #N from one end to the other end in the nozzle arrangement direction D3. In the third example, the positions of the plurality of nozzle rows in the head chip in the nozzle arrangement direction D3 coincide with each other, and therefore the nozzle number in the head chip is information common to each nozzle row.

In the third example, the control unit <NUM> two-dimensionally records an image on the medium <NUM> based on image data representing an image by executing in parallel the conveyance of the medium <NUM> by the conveyance unit <NUM> at a constant speed from the upstream side to the downstream side in the conveyance direction D1, and the ink ejection from the recording head <NUM>. In addition, in the third example, the line recorded on the medium <NUM> with the conveyance direction D1 as the longitudinal direction is referred to as "raster line". Specifically, in the state of image data, the raster line is a pixel line of a plurality of pixels aligned in the conveyance direction D1, while it is a dot line directed in the conveyance direction D1 on the medium <NUM>. The length of the raster line is not limited.

In the third example, the control unit <NUM> also performs the OL recording for some raster lines by using the plurality of nozzles <NUM>. While a part of the region recorded in the preceding path is OL-recorded in the succeeding path in an overlapping manner by adjusting the distance L1 in the first example and the second example, the head chips partially overlap in the nozzle arrangement direction D3 in the configuration of the recording head <NUM> in the third example. More specifically, in <FIG>, the nozzle range of the nozzle numbers #N-<NUM> to #N of the head chip 22a and the nozzle range of the nozzle numbers #<NUM> to #<NUM> of the head chip 22b overlap each other. Likewise, the nozzle ranges overlap each other also in the relationship between the head chip 22b and the head chip 22c.

Regarding such a head chip, the nozzle range of the nozzle numbers #<NUM> to #<NUM> on one end side in the nozzle arrangement direction D3 and the nozzle range of the nozzle numbers #N-<NUM> to #N on the other end side in the nozzle arrangement direction D3 may be regarded as with the downstream nozzle range and the upstream nozzle range of the first example, including the presence of the unused nozzle in respective ranges.

In such a configuration, attention is focused on ejection of the K ink by the group of the nozzle rows 23K1, 23K2 and 23K3 of the head chips 22a, 22b and 22c. A region <NUM> corresponds to "first overlapping region" where each raster line is formed through the ink ejection by the nozzle row 23K1 and the nozzle row 23K2 or the ink ejection by the nozzle row 23K2 and the nozzle row 23K3. For example, a certain one raster line making up the first overlapping region <NUM> is OL-recorded by the nozzles <NUM> of the nozzle number #N-<NUM> of the nozzle row 23K1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23K2. The region other than the region <NUM> in the medium <NUM> corresponds to "first normal region" where the raster line is formed by the nozzle <NUM> of any one of the nozzle row 23K1, the nozzle row 23K2 and the nozzle row 23K3.

Attention is focused on ejection of the C ink by the group of the nozzle rows 23C1, 23C2 and 23C3 of the head chips 22a, 22b and 22c. A region <NUM> corresponds to "second overlapping region" where each raster line is formed through the ink ejection by the nozzle row 23C1 and the nozzle row 23C2 or the ink ejection by the nozzle row 23C2 and the nozzle row 23C3. For example, a certain one raster line making up second overlapping region <NUM> is OL-recorded by the nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row 23C1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23C2. The region other than the region <NUM> in the medium <NUM> corresponds to "second normal region" where the raster line is formed by the nozzle <NUM> of any one of the nozzle row 23C1, the nozzle row 23C2 and the nozzle row 23C3. That is, the first overlapping region <NUM> overlaps a part of the second normal region, and the second overlapping region <NUM> overlaps a part of the first normal region.

In the third example, attention is focused on a pair of head chips whose ranges partially overlap each other, and the nozzle row 23K1 is referred to as "first nozzle row", the nozzle row 23K2 is referred to as "second nozzle row", the nozzle row 23C1 is referred to as "third nozzle row", and the nozzle row 23C2 is referred to as "fourth nozzle row", for example Naturally, the nozzle row 23K2 may be regarded as "first nozzle row", the nozzle row 23K3 may be regarded as "second nozzle row", the nozzle row 23C2 may be regarded as "third nozzle row", and the nozzle row 23C3 may be regarded as "fourth nozzle row". In such a third example, the first normal region where the raster line is formed by using the first nozzle row or the second nozzle row, the first overlapping region <NUM> where the raster line is formed by using the first nozzle row and the second nozzle row, the second normal region where the raster line is formed by using the third nozzle row or the fourth nozzle row, and the second overlapping region <NUM> where the raster line is formed by using the third nozzle row and the fourth nozzle row, are recorded. Further, the first overlapping region <NUM> and the second overlapping region <NUM> are shifted in the nozzle arrangement direction D3. In other words, the first overlapping region <NUM> is formed at a position overlapping the second normal region as viewed in the longitudinal direction of the raster line. In addition, in other words, the second overlapping region <NUM> is formed at a position overlapping the first normal region as viewed in the longitudinal direction.

<FIG> is a diagram schematically illustrating a relationship between the recording head <NUM> and the medium <NUM> and the like according to a fourth example as viewed from above. The view of <FIG> is the same as <FIG>. In the fourth example, as in the third example, the recording apparatus <NUM> is a line printer. In the fourth example, description common to the third example is omitted. The relationship between the third example and the fourth example may be interpreted as being the same as the relationship between the first example and the second example.

That is, in the fourth example, in each of the plurality of the head chips 22a, 22b and 22c provided in the recording head <NUM>, at the positions of the plurality of nozzle rows are shifted from each other in the nozzle arrangement direction D3. The shift amount of the nozzle row 23K1 and the nozzle row 23C1, the shift amount of the nozzle row 23K2 and the nozzle row 23C2, and the shift amount of the nozzle row 23K3 and the nozzle row 23C3 are the same as the shift amount of the nozzle row <NUM> and the nozzle row 23C of <FIG>.

It can be said that each of the nozzle rows 23K1, 23C1, 23K2, 23C2, 23K3 and 23C3 illustrated in <FIG> has a configuration obtained by only removing the unused nozzles from each of the nozzle rows 23K1 and 23C1, 23K2, 23C2, 23K3 and 23C3 illustrated in <FIG>. As such, in <FIG>, the number N of nozzles per nozzle row in the head chip is smaller than the number N of nozzles of <FIG> by three. Thus, by using the recording head <NUM> of <FIG> instead of the recording head <NUM> of <FIG>, the first overlapping region <NUM> can be OL-recorded by the first nozzle row and the second nozzle row, the first normal region can be recorded by the first nozzle row or the second nozzle row, the second overlapping region <NUM> can be OL-recorded by the third nozzle row and the fourth nozzle row, and the second normal region can be recorded by the third nozzle row or the fourth nozzle row, as in the third example. That is, the first overlapping region <NUM> and the second overlapping region <NUM> are recorded in a shifted manner in the nozzle arrangement direction D3.

Specifically, in <FIG>, when attention is focused on ejection of the K ink by the nozzle row 23K1 and the nozzle row 23K2, a certain one raster line making up the first overlapping region <NUM> is OL-recorded by the nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row 23K1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23K2. In addition, when attention is focused on ejection of the C ink by the nozzle row 23C1 and the nozzle row 23C2, a certain one raster line making up the second overlapping region <NUM> is OL-recorded by the nozzle <NUM> of the nozzle number #N-<NUM> of the nozzle row 23C1 and the nozzle <NUM> of the nozzle number #<NUM> of the nozzle row 23C2.

<FIG> is a flow flowchart illustrating recording of a pattern and detection of foreign matter executed by the recording/reading system <NUM>. Note that even in the case where the recording apparatus <NUM> and the reading apparatus <NUM> making up the recording/reading system <NUM> are separate apparatuses, <FIG> simply collectively illustrates the processes executed by the apparatuses <NUM> and <NUM> in one flowchart.

At step S100, the record control unit 12a of the control unit <NUM> controls the recording unit <NUM> and the conveyance unit <NUM> on the basis of pattern recording image data stored in advance in the storage unit <NUM> and the like, and records "density correcting pattern" and "comparative pattern" on the medium <NUM>. The the pattern recording image data is image data representing a density correcting pattern and a comparative pattern. The density correcting pattern corresponds to "first pattern" including the first overlapping region and the first normal region, and the comparative pattern corresponds to "second pattern" including the second overlapping region and the second normal region. Step S100 is "pattern recording step" of recording a pattern on the medium <NUM>. The comparative pattern is used for detecting foreign matter in the reading unit <NUM> as described later.

In the embodiment, any of the above-described first to fourth examples may be employed as the specific example of the recording head <NUM>, the conveyance and the like. Specifically, in a configuration in which the recording apparatus <NUM> employs the first example or the second example, at step S100, the record control unit 12a records the density correcting pattern on the medium <NUM> by controlling the first nozzle row, and records a comparative pattern on the medium <NUM> by controlling the second nozzle row. The density correcting pattern includes the first overlapping region, which is the overlapping region where the raster line having a longitudinal direction corresponding to the main scanning direction D2 is formed through m scans, and the first normal region, which is a normal region where the raster line is formed through n scans, and n is smaller than m. The comparative pattern includes the second overlapping region, which is the overlapping region, and the second normal region, which is the normal region. According to the description made above, m=<NUM> and n=<NUM> hold.

Alternatively, in a configuration in which the recording apparatus <NUM> employs the third example or the fourth example, at step S100, the record control unit 12a records the density correcting pattern on the medium <NUM> by controlling the first nozzle row and the second nozzle row, and records the comparative pattern on the medium <NUM> by controlling the third nozzle row and the fourth nozzle row. The density correcting pattern includes the first normal region where the raster line whose longitudinal direction is the conveyance direction D1 intersecting the nozzle arrangement direction D3 is formed by using the first nozzle row or the second nozzle row, and the first overlapping region where the raster line is formed by using the first nozzle row and the second nozzle row. The comparative pattern includes the second normal region where the raster line is formed by using the third nozzle row or the fourth nozzle row and the second overlapping region where the raster line is formed by using the third nozzle row and the fourth nozzle row.

At step S100, in the medium <NUM>, the first overlapping region in the density correcting pattern is formed at a position overlapping the second normal region in the comparative pattern as viewed in the longitudinal direction of the raster line.

At step <NUM>, the control unit <NUM> controls the conveyance unit <NUM> and the reading unit <NUM> to cause the reading unit <NUM> to read the density correcting pattern and the comparative pattern recorded on the medium <NUM> at step S100.

<FIG> is a diagram schematically illustrating the medium <NUM> and the reading unit <NUM> after pattern recording at step S100 as viewed from above. In <FIG>, a plurality of density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and a comparative pattern <NUM> are recorded on the medium <NUM> along a direction D4. The patterns <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> do not overlap each other in the direction D4. As can be seen from the example described above, the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are recorded with the K ink and the comparative pattern <NUM> is recorded with the C ink. The direction D4 is the longitudinal direction of the raster line, and, in the situation of <FIG>, the direction D4 is also a conveyance direction for conveying the medium <NUM> toward the reading unit <NUM>. Note that in a configuration in which the third example or the fourth example is employed as the configuration of the recording head <NUM> and the reading unit <NUM> is assembled downstream of the recording head <NUM> in the conveyance direction D1, the conveyance direction D1=D4 can be interpreted to hold. On the other hand, in a configuration in which the first example or the second example is employed as the configuration of the recording head <NUM>, it is necessary to automatically or manually convert the orientation of the medium <NUM> after the recording such that the longitudinal direction of the raster line in the medium <NUM> after the recording is directed to the direction D4.

The density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are recorded with respective different K densities, and the comparative pattern <NUM> is recorded with a predetermined C density. The density may be interpreted as the cover rate of dots, the dot generation rate per unit area, and the like. In addition, each of the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and the comparative pattern <NUM> is a belt-shaped pattern whose longitudinal direction is a direction D5 intersecting the direction D4, and each pattern has a constant density. Here, the constant density means that the density represented by the pattern recording image data has a constant value in each pattern, and density variation, i.e., unevenness in density, is generated in each pattern actually recorded on the medium <NUM> due to the non-uniformity of the ejection characteristics and the like of the nozzles <NUM>.

In a situation where the recording head <NUM> performs recording on the medium <NUM>, the direction D5 for the medium <NUM> corresponds to the nozzle arrangement direction D3. In <FIG>, the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are darker in sequence. Each pattern is recorded at the density (constant value) set in the image data such that the density correcting pattern <NUM> is at <NUM>%, the density correcting pattern <NUM> is at <NUM>%, the density correcting pattern <NUM> is at <NUM>%, the density correcting pattern <NUM> is at <NUM>%, and the density correcting pattern <NUM> is at <NUM>%, for example. When one raster line RL with the maximum length in the direction D4 as indicated with the broken line in <FIG> is assumed to be provided in the medium <NUM> after the pattern recording described above, the raster line RL includes a part of each of the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and the comparative pattern <NUM>.

As illustrated in <FIG>, the longitudinal direction of the reading unit <NUM> is the direction D5. That is, the line sensor provided in the reading unit <NUM> is arranged with the direction D5 as the longitudinal direction. Thus, when the medium <NUM> after pattern recording is conveyed in the direction D4 and the reading unit <NUM> reads the medium <NUM>, the density of each of the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> and the comparative pattern <NUM> is obtained for each position of the raster line. Note that here, while the information acquired by the reading unit <NUM> as the reading result of the medium <NUM> is the luminance of each pixel and the like, the information acquired by the reading unit <NUM> as the reading result is also referred to as "density", for example. The density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM> are patterns for calculating "density correction value" for correcting the non-uniformity of the density at each position of the raster line. Calculation of the density correction value will be described later.

In <FIG>, a part of the density correcting pattern <NUM> and the comparative pattern <NUM> surrounded by the two-dotted line in the medium <NUM> is illustrated in an enlarged diagram of FIG. The enlarged diagram of FIG. 7A also illustrates reading results of a part of the density correcting pattern <NUM> and a part of the comparative pattern <NUM> at the reading unit <NUM> in the form of graphs. In the graph, the abscissa indicates the density as the reading result, and the ordinate indicates the position of each raster line. In other words, the position of each raster line is the position of the nozzle <NUM> in the nozzle arrangement direction D3.

As illustrated in the enlarged diagram of FIG. 7A, the density correcting pattern <NUM> includes a first overlapping region 50a and a first normal region 50b. In addition, the comparative pattern <NUM> includes a second overlapping region 60a and a second normal region 60b. How the first overlapping region, the first normal region, the second overlapping region, and the second normal region have been recorded is as described above. While the density correcting pattern <NUM> is an image recorded at a density of <NUM>% with the K ink and the comparative pattern <NUM> is an image recorded at a predetermined density with the C ink as described above, the enlarged diagram of FIG. 7A represents the density variation in each of the density correcting pattern <NUM> and the comparative pattern <NUM> for the sake of description, and does not necessarily correspond to the colors and densities of the original patterns <NUM> and <NUM> of the enlarged source of <FIG>.

Ideally, the density in the density correcting pattern <NUM> is constant, but there is a difference in density between the first overlapping region 50a and the first normal region 50b. That is, between the first normal region 50b in which each raster line is recorded by one nozzle <NUM> and the first overlapping region 50a in which each raster line is OL-recorded by two nozzles <NUM>, the density difference easily occurs at the medium <NUM> due to the difference in overlapping amount of the dots, the difference in impinging time difference of dots, and the like. In the example illustrated in the enlarged diagram of FIG. 7A, the first overlapping region 50a has a higher density, i.e., higher darkness than the first normal region 50b. Likewise, ideally, the density in the comparative pattern <NUM> is constant, but there is a density difference between the second overlapping region 60a and the second normal region 60b. In the example illustrated in the enlarged diagram of FIG. 7A, the second overlapping region 60a has a density higher than that of the second normal region 60b.

As is clear from the enlarged diagram of FIG. 7A, the first overlapping region 50a in the density correcting pattern <NUM> overlaps the second normal region 60b in the comparative pattern <NUM> as viewed in the longitudinal direction of the raster line, and the position is shifted from the second overlapping region 60a. Note that in each of the overlapping regions 50a and 60a and normal regions 50b and 60b, there is a slight difference in density at each position of the raster line due to the non-uniformity of the ejection characteristics of the nozzle <NUM> used for the recording of each raster line. It should be noted that, in enlarged in FIG. 7A, expression of such a slight density difference at each position of the raster line is omitted, and the density difference between the first overlapping region 50a and the first normal region 50b and the density difference between the second overlapping region 60a and the second normal region 60b are clearly illustrated.

At step S120, the control unit <NUM> performs foreign matter detection at the reading unit <NUM> on the basis of the reading result of the density correcting pattern and the comparative pattern from the reading unit <NUM>. The control unit <NUM> that executes step S120 corresponds to "detection unit" that executes foreign matter detection. In this case, it suffices that the control unit <NUM> compares the reading result of the density correcting pattern and the reading result of the comparative pattern, and determines that there is foreign matter when there is a range where the density variation is large at the same position in the results.

As in the enlarged diagram of FIG. 7A in <FIG>, <FIG> illustrates a part of the density correcting pattern <NUM>, a part of the comparative pattern <NUM>, and their reading results at the reading unit <NUM>. <FIG> is different from the enlarged diagram of FIG. 7A in that the density of foreign matter F adhered to the reading unit <NUM> is indicated in the graph of the reading result. Note that while the foreign matter F adheres to the reading unit <NUM>, a pseudo foreign matter F is illustrated in the density correcting pattern <NUM> and in the comparative pattern <NUM> for the reason that the patterns <NUM> and <NUM> appear as in <FIG> from the reading unit <NUM>.

As described above, there is a density difference between the overlapping region and the normal region in a single pattern. On the other hand, there is also a density difference between the density of the read foreign matter F and the density of the normal region. Therefore, in the case where the reading result of a single pattern, e.g., the density correcting pattern <NUM> is analyzed and there is a density different from the normal region, it is difficult to determine whether that is the density corresponding to the overlapping region or the density corresponding to the foreign matter F. In particular, in the case where the foreign matter F adheres at the position corresponding to the overlapping region in the reading unit <NUM>, it is difficult to detect the foreign matter F from the reading result of the density correcting pattern <NUM>. In the embodiment, the first overlapping region in the density correcting pattern and the second overlapping region in the comparative pattern are recorded in a shifted manner in the nozzle arrangement direction D3. Thus, when the reading result of the density correcting pattern and the reading result of the comparative pattern are compared with each other and there is a large density variation only in one of the reading result of the density correcting pattern and the reading result of the comparative pattern at a certain position, then it can be determined to be the density variation corresponding to the overlapping region. Conversely, when there is a large density variation in both the reading result of the density correcting pattern and the reading result of the comparative pattern at a certain position, then it can be determined to be the density variation corresponding to the foreign matter F, not the overlapping region.

In <FIG>, the reference numbers <NUM> and <NUM> in the graph as the reading result of the density correcting pattern <NUM> represent a range where the density is largely changed (hereinafter referred to as density changing range) in comparison with the density of the normal region. The "density is largely changed in comparison with the density of the normal region" means that the absolute value of the difference from the average density of the normal region in the pattern is equal to or greater than a predetermined threshold value, for example. Likewise, in <FIG>, reference numbers <NUM>, <NUM> and <NUM> in the graph as the reading result of the comparative pattern <NUM> also indicate density changing ranges. One density changing range is shown also in each of the two graphs of the enlarged diagram of FIG.

The results show that, of the density changing ranges <NUM> to <NUM>, the density changing ranges <NUM>, <NUM>, <NUM> and <NUM> are densities corresponding to the foreign matter F. That is, the density changing ranges <NUM> and <NUM> are the results of the density of a certain foreign matter F indicated in both the density of the density correcting pattern <NUM> and the density of the comparative pattern <NUM>. Likewise, the density changing ranges <NUM> and <NUM> are the results of the density of another certain foreign matter F indicated in both the density of the density correcting pattern <NUM> and the density of the comparative pattern <NUM>. While the foreign matter F includes various matters such as paper dust and ink smudge, and the color and the density differ depending on what exactly it is, <FIG> illustrates an example case where the density of the foreign matter F is also high in comparison with the normal region. A density changing range <NUM> has a density of the foreign matter F overlapping a part of the first overlapping region 50a.

According to <FIG>, it can be said that the density changing range <NUM> in the graph as the reading result of the density correcting pattern <NUM> and the density changing range <NUM> in the graph as the reading result of the comparative pattern <NUM> are generated at the same position in the ordinate of the graph. In addition, the density changing range <NUM> and the density changing range <NUM> are also generated at the same position. The "same position" may be defined not only as being exact same and completely overlapping, but also as including some errors and margins. In this manner, when the reading result as illustrated in <FIG> is obtained, the control unit <NUM> determines that detection of foreign matter is successful, i.e., there is foreign matter. On the other hand, when the reading result as illustrated in the enlarged diagram of FIG. 7A is obtained, it cannot be said that the positions of the density changing range in the graph as the reading result of the density correcting pattern <NUM> and the density changing range in the graph as the reading result of the comparative pattern <NUM> are the same, and accordingly the control unit <NUM> determines that detection of foreign matter is not successful, i.e., there is no foreign matter.

At step S130, the control unit <NUM> divides the process in accordance with the result of the detection of the foreign matter at step S120. When determining that there is foreign matter, the control unit <NUM> advances the process from "Yes" of step S130 to step S140, whereas when determining that there is no foreign matter, the control unit <NUM> advances the process from "No" of step S130 to step S150.

While the reading result of the density correcting pattern <NUM> and the reading result of the comparative pattern <NUM> are compared with each other in <FIG> and <FIG>, the control unit <NUM> may execute the detection of the foreign matter by comparing the reading result of any of the other density correcting patterns <NUM>, <NUM>, <NUM> and <NUM> and the reading result of the comparative pattern <NUM>. Of the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, the control unit <NUM> may use the reading result of the pattern with the density that tends to indicate the difference from the density of the foreign matter, for the comparison with the reading result of the comparative pattern <NUM>, for example.

At step S140, the control unit <NUM> replaces the density at the position corresponding to the detected foreign matter in the reading result of the density correcting pattern with the reading result of the nearby position in the density correcting pattern. As illustrated in <FIG> for example, when determining that there is foreign matter in the density changing range <NUM> in the reading result of the density correcting pattern <NUM>, the control unit <NUM> replaces the density of the density changing range <NUM> with the density of the first normal region at a position adjacent to or near the density changing range <NUM> at step S140. In addition, when determining that there is foreign matter in the density changing range <NUM> corresponding to the first overlapping region 50a in the reading result of the density correcting pattern <NUM>, the control unit <NUM> replaces the density of the density changing range <NUM> with the density of another first overlapping region that does not include the density of the foreign matter at a position near the density changing range <NUM> at step S140.

The position of the foreign matter detected at step S120 is common to the reading result of the density correcting pattern other than the density correcting pattern that is compared with the comparative pattern <NUM>. Therefore, when the foreign matter has been detected by comparing the density correcting pattern <NUM> with the comparative pattern <NUM> as described above, the control unit <NUM> replaces the density of the position corresponding to the foreign matter with the density of the nearby position in the pattern in the same manner for the reading results of the density correcting patterns <NUM>, <NUM>, <NUM> and <NUM> at step S140. Through this step S140, the influence of the foreign matter can be removed from the reading results of the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM>.

Through "No" of step S130 or step S140, at step S150, the data correction unit 12b of the control unit <NUM> calculates the density correction value at each position of the raster line. Note that the control unit <NUM> transfers, to the control unit <NUM>, read image data as the reading results of the density correcting patterns <NUM>, <NUM>, <NUM> and <NUM> at the reading unit <NUM>. In the case where step S140 is executed, the read image data transferred to the control unit <NUM> is naturally data after the process of step S140.

Step S150 is briefly described below. The data correction unit 12b calculates the density correction value for each position of the raster line on the basis of the read image data of the density correcting patterns <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. Briefly speaking, for a position of a certain one raster line, the data correction unit 12b compares the density as the reading result of certain one density correcting pattern, e.g., the density correcting pattern <NUM> corresponding to <NUM>% of K with a predetermined reference value (luminance) expected to be obtained as the reading result of the density correcting pattern <NUM>, and calculates the density correction value in accordance with the comparison result. That is, when the density of the density correcting pattern <NUM> is higher than the reference value, the density correction value for reducing the density (brightening) is calculated. Conversely, when the density of the density correcting pattern <NUM> is lower than the reference value, the density correction value for increasing the density (darkening) is calculated. The correction value for reducing the density is a correction value that acts to reduce the ink amount, and the correction value for increasing the density is a correction value that acts to increase the ink amount.

The density correction value calculated in this manner is the correction value for correcting the density (<NUM>% of K) of the image data of recording source of the density correcting pattern <NUM> corresponding to the position of the one raster line. The calculation of the density correction value of the above-described procedure is performed for the position of each raster line and for each of the densities (<NUM>%, <NUM>%, <NUM>%, <NUM>% and <NUM>% of K) of the recording source of the density correcting patterns <NUM> to <NUM>. Further, the data correction unit 12b executes interpolation computation of the density correction value as necessary, and as a result, obtains the density correction value for each of the positions of all raster lines and for each of all densities (<NUM> to <NUM>% of K). The data correction unit 12b records the density correction values calculated in this manner in the storage unit <NUM> and the like, and terminates the flowchart of <FIG>.

Thereafter, when the control unit <NUM> executes recording of an image based on image data arbitrarily selected by the user, the data correction unit 12b corrects the density of K of each pixel of the image data with the density correction value corresponding to the density and the position of the raster line. Then, on the basis of the image data corrected in this manner, the record control unit 12a records the image on the medium <NUM> by controlling the conveyance unit <NUM> and the recording unit <NUM>. As a result, recording results with favorable image quality in which the non-uniformity of the density of each raster line and the density difference between the overlapping region and the normal region are corrected are obtained.

Through the procedure of the above-described steps S140 and S150 and the subsequent image recording including the correction using the density correction value, the amount of the ink to be thereafter ejected from the nozzle <NUM> used for the recording of the raster line corresponding to the position where the foreign matter is detected at step S120 is corrected with the density correction value calculated through the calculation of the correction value at step S150 based on the density after the replacement step S140. Thus, it can be said that when foreign matter is detected by the detection unit, the control unit <NUM> controls the ejection of the liquid at a foreign matter position nozzle, which is the nozzle <NUM> used for the recording of the region where the foreign matter is detected, on the basis of the reading result of the reading unit <NUM> corresponding to the nozzle <NUM> near the foreign matter position nozzle.

Note that the density correction value is required for all colors of the ink ejected by the recording head <NUM>. Therefore, in the case where the recording head <NUM> includes nozzle rows of CMYK inks, the density correcting patterns of the C, M and Y inks are recorded on the medium <NUM> as with the density correcting patterns <NUM> to <NUM> of the K ink illustrated in <FIG> in the embodiment, for example. The method of calculating the density correction value, including the density replacement at step S140, is the same for all ink colors. Therefore, the density correcting pattern of ink other than K may be used for the comparison of the reading result with the reading result of the comparative pattern <NUM> for the foreign matter detection. In addition, it suffices to record the comparative pattern <NUM> with the ink of any one color, and therefore the comparative pattern <NUM> may be recorded with the ink other than the C ink.

When determining that "Yes" at step S130, the control unit <NUM> may proceed to step S160 as indicated with the broken line in <FIG>. In this case, steps S140 and S150 are not executed. At step S160, the control unit <NUM> causes the display unit <NUM> to display an alert indicating that there is a region where reading by the reading unit <NUM> has failed, and then terminates the flowchart of <FIG>. The region where reading by the reading unit <NUM> has failed is naturally a position where foreign matter has been detected. The display unit <NUM> displays an alert message, such as "Some parts of the document could not be read due to foreign matter adhering to the image sensor". In addition, the display unit <NUM> may use an alert display of a message urging the user to remove foreign matter such as "Clean the image sensor as there may be foreign matter adhering to the image sensor" at step S160.

In addition, together with the alert display of step S160, the control unit <NUM> may inquire the user whether step S140 and S150 can be executed or not, and proceed to step S140 and S150 when the user's instruction is accepted for this execution or not.

In this manner, according to the embodiment, the recording apparatus <NUM> includes a first nozzle row and a second nozzle row including the plurality of nozzles <NUM> configured to eject liquid to the medium <NUM>, and a control unit <NUM> configured to control ejection of the liquid by the first nozzle row and the second nozzle row, and the control unit <NUM> is configured to cause the first nozzle row and the second nozzle row to perform scan of ejecting the liquid while moving forward or backward along the predetermined main scanning direction D2. When the control unit <NUM> records a first pattern including a first overlapping region and a first normal region on the medium <NUM> by controlling the first nozzle row and records a second pattern including a second overlapping region and a second normal region on the medium <NUM> by controlling the second nozzle row, the control unit <NUM> forms the first overlapping region at a position overlapping the second normal region as viewed in a longitudinal direction, the first overlapping region being an overlapping region where a raster line having a longitudinal direction corresponding to the main scanning direction D2 is formed by performing the scan m times, the first normal region being a normal region where the raster line is formed by performing the scan n times, n being smaller than m, the second overlapping region being the overlapping region, the second normal region being the normal region.

In addition, according to the embodiment, the recording apparatus <NUM> includes a first nozzle row, a second nozzle row, a third nozzle row and a fourth nozzle row in which the plurality of nozzles <NUM> configured to eject liquid to the medium <NUM> are arranged in the arrangement direction D3 of the nozzles, and a control unit <NUM> configured to control ejection of the liquid by the first nozzle row, the second nozzle row, the third nozzle row and the fourth nozzle row. Further, the control unit <NUM> records a first pattern including a first normal region and a first overlapping region on the medium <NUM> by controlling the first nozzle row and the second nozzle row and records a second pattern including a second normal region and a second overlapping region on the medium <NUM> by controlling the third nozzle row and the fourth nozzle row, the control unit <NUM> forms the first overlapping region at a position overlapping the second normal region as viewed in a longitudinal direction, the first normal region being a region where a raster line having a longitudinal direction corresponding to a direction intersecting the arrangement direction D3 of the nozzles is formed using the first nozzle row or the second nozzle row, the first overlapping region being a region where the raster line is formed using the first nozzle row and the second nozzle row, the second normal region being a region where the raster line is formed using the third nozzle row or the fourth nozzle row, the second overlapping region being a region where the raster line is formed using the third nozzle row and the fourth nozzle row.

In each configuration, when the first pattern and the second pattern are recorded on the medium <NUM>, the first overlapping region is formed at a position overlapping the second normal region as viewed in the longitudinal direction of the raster line. Thus, a pattern with which it is easy to determine whether the reason for the part with a large density variation in the reading result is the influence of the overlapping region or the influence of foreign matter at the time of reading is recorded, which is useful for the detection of foreign matter. In addition, since the foreign matter detection is facilitated with the above-mentioned pattern design, it is not necessary to have two image reading sensors for detecting and cleaning foreign matter unlike in known technology, which leads to product cost reduction.

In addition, according to the embodiment, the control unit <NUM> records a plurality of the first patterns with densities different from each other, along the longitudinal direction.

By recording the plurality of first patterns with densities different from each other, an appropriate density correction value with increased density correction accuracy can be obtained on the basis of the reading result of each first pattern.

It should be noted that, a configuration of recording only one pattern for the first pattern may be employed. For example, in <FIG>, only the density correcting pattern <NUM> is recorded on the medium <NUM> as the first pattern. The control unit may execute the foreign matter detection by comparing the reading result of the density correcting pattern <NUM> with the reading result of the comparative pattern <NUM>, and may determine the density correction value of each position of the raster line by determining the tendency of the density variation of the record density in each raster line on the basis of the reading result of the density correcting pattern <NUM>.

In addition, according to the embodiment, the first pattern and the second pattern are recorded with liquids of different colors.

With this configuration, the first pattern and the second pattern have different colors on the medium <NUM>, and thus it is easy to determine the density of the first pattern and the density of the second pattern from the reading result of the medium <NUM>, and to detect foreign matter on the basis of the comparison between the first pattern and the second pattern.

It should be noted that, in the case where the recording head <NUM> includes multiple rows or multiple nozzle row groups that eject the ink of the same color, the first pattern and the second pattern may be recorded with ink of the same color.

In addition, according to the embodiment, the recording/reading system <NUM> includes the recording apparatus <NUM>, the reading unit <NUM> configured to read the first pattern and the second pattern recorded on the medium <NUM> by the recording apparatus <NUM>, and the detection unit (control unit <NUM>) configured to detect foreign matter at the reading unit <NUM>, based on a reading result of the first pattern and the second pattern from the reading unit <NUM>.

With this configuration, the recording/reading system <NUM> can perform the foreign matter detection at the reading unit <NUM> on the basis of the reading result of the first pattern and the second pattern from the reading unit <NUM>.

In addition, according to the embodiment, the recording/reading system <NUM> may include the display unit <NUM> configured to display information, and when the foreign matter is detected by the detection unit, the display unit <NUM> may indicate that there is a region where reading by the reading unit <NUM> failed.

With this configuration, when foreign matter is detected by the detection unit, the user can recognize that there is a region where reading by the reading unit <NUM> has failed.

In addition, according to the embodiment, when the foreign matter is detected by the detection unit, the control unit <NUM> may control ejection of the liquid by a foreign matter position nozzle, based on a reading result of the reading unit <NUM> corresponding to the nozzle <NUM> located near the foreign matter position nozzle, the foreign matter position nozzle being the nozzle <NUM> used for recording a region where the foreign matter is detected.

With this configuration, when foreign matter is detected by the detection unit, the subsequent liquid ejection of the nozzle <NUM> can be appropriately controlled on the basis of the reading result of the reading unit <NUM> in which the influence of the foreign matter is eliminated.

The embodiment is not limited to apparatuses and systems, and encompasses disclosures of various categories such as a method executed by apparatuses and systems and the program <NUM> for causing a processor to execute the method.

For example, in a recording method of the recording apparatus <NUM> configured to perform recording by controlling ejection of liquid by a first nozzle row and a second nozzle row including the plurality of nozzles <NUM> configured to eject the liquid to the medium <NUM>, the recording method includes a pattern recording step of recording a pattern on the medium <NUM> by causing the first nozzle row and the second nozzle row to perform scan of ejecting the liquid while moving forward or backward along the predetermined main scanning direction D2. In the pattern recording step, when recording a first pattern including a first overlapping region and a first normal region on the medium <NUM> by controlling the first nozzle row and recording a second pattern including a second overlapping region and a second normal region on the medium <NUM> by controlling the second nozzle row, the first overlapping region is formed at a position overlapping the second normal region as viewed in a longitudinal direction, the first overlapping region being an overlapping region where a raster line having a longitudinal direction corresponding to the main scanning direction D2 is formed by performing the scan m times, the first normal region being a normal region where the raster line is formed by performing the scan n times, n being smaller than m, the second overlapping region being the overlapping region, the second normal region being the normal region.

While m=<NUM> and n=<NUM> hold in the description made above, the values of m and n are not limited to these. For example, for the first pattern, the recording apparatus <NUM> may OL-record each raster line of the first overlapping region through four scans of the first nozzle row and OL-record each raster line of the first normal region through two scans of the first nozzle row. Further, for the second pattern, the recording apparatus <NUM> may OL-record each raster line of the second overlapping region through four scans of the second nozzle row and OL-record each raster line of the second normal region through two scans of the second nozzle row. That is, it is only necessary that the relationship of m>n holds.

Claim 1:
A recording/reading system (<NUM>) comprising:
a recording apparatus (<NUM>) ; and
a reading unit (<NUM>);
the recording apparatus (<NUM>) comprising:
a first nozzle row and a second nozzle row including a plurality of nozzles (<NUM>) configured to eject liquid to a medium (<NUM>); and
a control unit (<NUM>) configured to control ejection of the liquid by the first nozzle row and the second nozzle row, wherein
the control unit is configured to cause the first nozzle row and the second nozzle row to perform scan of ejecting the liquid while moving forward or backward along a predetermined main scanning direction (D2);
when the control unit records a first pattern including a first overlapping region (<NUM>) and a first normal region on the medium by controlling the first nozzle row and records a second pattern including a second overlapping region (<NUM>) and a second normal region on the medium by controlling the second nozzle row, the control unit forms the first overlapping region at a position overlapping the second normal region as viewed in a longitudinal direction (D1), the first overlapping region being an overlapping region where a raster line having a longitudinal direction corresponding to the main scanning direction is formed by performing the scan m times, the first normal region being a normal region where the raster line is formed by performing the scan n times, n being smaller than m, the second overlapping region being an overlapping region where a raster line having a longitudinal direction corresponding to the main scanning direction is formed by performing the scan m times, the second normal region being a normal region where the raster line is formed by performing the scan n times, n being smaller than m; and
a reading unit (<NUM>) configured to read the first pattern and the second pattern recorded on the medium (<NUM>) by the recording apparatus; and
a detection unit (<NUM>) configured to detect foreign matter at the reading unit, based on a reading result of the first pattern and the second pattern from the reading unit;
wherein the detection unit compares the reading result of the first pattern and the reading result of the second pattern, and determines that there is foreign matter when there is a range where the density variation at the same position in the results is larger than a predetermined threshold.