JP6977254B2 - Liquid discharge device, liquid discharge system and liquid discharge method - Google Patents

Description

The present invention relates to a device for discharging a liquid, a system for discharging a liquid, and a method for discharging the liquid.

Conventionally, a method of forming an image or the like by a so-called inkjet method of ejecting ink from a print head is known. A method of improving the print quality of an image printed on a print medium by this image formation is known.

For example, a method of adjusting the position of a print head is known in order to improve print quality. Specifically, first, the position fluctuation in the lateral direction of the web (web), which is a printing medium passing through the continuous paper printing system, is detected by the sensor. A method of adjusting the position of the print head in the lateral direction so as to compensate for the position variation detected by this sensor is known (see, for example, Patent Document 1).

However, in order to further improve the image quality of the image formed, the liquid to be ejected lands in a direction orthogonal to the direction in which the object to be conveyed is conveyed (hereinafter, simply referred to as "orthogonal direction"). You may be asked to make the position more accurate. On the other hand, in the conventional technique, there is a problem that the accuracy of the landing position of the discharged liquid may not be improved in the orthogonal direction.

One aspect of the present invention is to provide a device that ejects a liquid that can further improve the accuracy of the landing position of the ejected liquid in the orthogonal direction.

To solve the problems described above, which is an embodiment of the present invention, an apparatus for discharging a liquid,
A first liquid discharge head unit that discharges liquid to the transported object, and
The first liquid ejection head unit liquid discharged is provided on the upstream side of the landing position landing on the transported object, a first support member for supporting the object to be conveyed,
Provided on the downstream side of the landing position, and a second support member for supporting the object to be conveyed,
A second that is arranged between the first support member and the second support member and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. 1 detector and
A second liquid discharge head unit provided downstream of the second support member and discharging liquid to the transported object, and a second liquid discharge head unit.
A third support member provided on the upstream side of the second liquid discharge head unit and on the downstream side of the second support member to support the transported object, and a third support member.
A fourth support member provided on the downstream side of the second liquid discharge head unit and supporting the object to be transported, and a fourth support member.
It is arranged between the third support member and the fourth support member , and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The second detector and
It is characterized by including a movement control unit for moving the second liquid discharge head unit based on the detection result of the first detection unit and the detection result of the second detection unit.

The accuracy of the landing position of the discharged liquid can be further improved in the direction orthogonal to the direction in which the object to be conveyed is conveyed.

It is a schematic diagram which shows an example of the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a schematic diagram which shows the whole structure example of the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the external shape of the liquid discharge head unit which concerns on one Embodiment of this invention. It is an external view which shows an example of the detection apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the correlation calculation method which concerns on one Embodiment of this invention. It is a figure which shows an example of the search method of the peak position in the correlation calculation which concerns on one Embodiment of this invention. It is a figure which shows the calculation result example of the correlation calculation which concerns on one Embodiment of this invention. It is a functional block diagram which shows an example of the functional structure of the detection part which concerns on one Embodiment of this invention. It is a figure which shows the example which the position of a recording medium fluctuates in an orthogonal direction. It is a figure which shows an example of the cause which a color shift occurs. It is a block diagram which shows an example of the hardware composition of the control part which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the hardware composition of the data management apparatus which the control part which concerns on one Embodiment of this invention has. It is a block diagram which shows an example of the hardware composition of the image output apparatus which the control part which concerns on one Embodiment of this invention has. It is a flowchart which shows an example of the whole processing by the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the hardware structure for calculating the fluctuation amount of the conveyed object which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the moving mechanism for moving the liquid discharge head which the apparatus which discharges liquid which concerns on one Embodiment of this invention has. It is a timing chart which shows an example of the method of calculating the fluctuation amount of the conveyed object by the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the test pattern used by the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the position where the 1st sensor is installed in the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the hardware configuration in the 1st comparative example. It is a figure which shows the processing result example of the whole processing by the apparatus which discharges a liquid which concerns on 1st comparative example. It is a figure which shows the processing result example of the whole processing by the apparatus which discharges the liquid which concerns on the 2nd comparative example. It is a figure which shows an example of the position where the sensor is installed in the apparatus which discharges a liquid which concerns on a comparative example. It is a functional block diagram which shows an example of the functional structure of the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a schematic diagram which shows the modification of the apparatus which discharges a liquid which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present specification and the drawings, the components having substantially the same functional configuration are designated by the same reference numerals, and duplicate description will be omitted.

<Overall configuration example>
FIG. 1 is a schematic view showing an example of a device for discharging a liquid according to an embodiment of the present invention. For example, the device that discharges the liquid is an image forming device as shown in the figure. In such an image forming apparatus, the discharged liquid is a recording liquid such as water-based or oil-based ink. Hereinafter, an example in which the device for discharging the liquid is the image forming apparatus 110 will be described.

The object to be transported is, for example, a recording medium or the like. In the illustrated example, the image forming apparatus 110 ejects a liquid to the web 120, which is an example of a recording medium conveyed by a roller 130 or the like, to form an image. Further, the web 120 is a so-called continuous paper printing medium or the like. That is, the web 120 is a roll-shaped sheet or the like that can be wound up. As described above, the image forming apparatus 110 is a so-called production printer. In the following description, an example will be described in which the roller 130 adjusts the tension of the web 120 and the web 120 is conveyed in the direction shown in the drawing (hereinafter referred to as “transport direction 10”). Further, in the figure, the direction orthogonal to the transport direction 10 is an example in which the orthogonal direction 20 is used. Further, in this example, the image forming apparatus 110 ejects inks of four colors of black (K), cyan (C), magenta (M), and yellow (Y) to an image at a predetermined position on the web 120. Is an inkjet printer that forms.

FIG. 2 is a schematic view showing an overall configuration example of a device for discharging a liquid according to an embodiment of the present invention. As shown in the figure, the image forming apparatus 110 has four liquid ejection head units for ejecting inks of four colors.

Each liquid discharge head unit discharges each liquid of each color to the web 120 transported in the transport direction 10. Further, it is assumed that the web 120 is conveyed by two pairs of nip rollers, rollers 230 and the like. Hereinafter, of the two pairs of nip rollers, the nip roller installed on the upstream side of each liquid discharge head unit is referred to as "first nip roller NR1". On the other hand, the nip roller installed on the downstream side of the first nip roller NR1 and each liquid discharge head unit is referred to as "second nip roller NR2". As shown in the figure, each nip roller rotates with an object to be transported such as a web 120 sandwiched between them. As described above, each nip roller and roller 230 is a mechanism or the like that conveys the web 120 or the like in a predetermined direction.

Further, it is desirable that the recording medium of the web 120 is long. Specifically, it is desirable that the length of the recording medium is longer than the distance between the first nip roller NR1 and the second nip roller NR2. Furthermore, the recording medium is not limited to the web. That is, the recording medium may be a sheet that is folded and stored, so-called "Z paper" or the like.

In the overall configuration example shown below, each liquid discharge head unit is installed in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side to the downstream side. do. That is, the liquid discharge head unit (hereinafter referred to as "black liquid discharge head unit 210K") installed on the most upstream side is used for black (K). The liquid discharge head unit (hereinafter referred to as "cyan liquid discharge head unit 210C") installed next to the black liquid discharge head unit 210K is used for cyan (C). Further, the liquid discharge head unit (hereinafter referred to as "magenta liquid discharge head unit 210M") installed next to the cyan liquid discharge head unit 210C is used for the magenta (M). Subsequently, the liquid discharge head unit (hereinafter referred to as "yellow liquid discharge head unit 210Y") installed on the most downstream side is used for yellow (Y).

Each liquid ejection head unit ejects ink of each color to a predetermined portion of the web 120 based on image data or the like. The position where the ink is ejected (hereinafter referred to as “landing position”) is substantially equal to the position where the liquid ejected from the liquid ejection head lands on the recording medium, that is, directly under the liquid ejection head or the like. In this example, the black ink is ejected to the landing position of the black liquid ejection head unit 210K (hereinafter referred to as “black landing position PK”). Similarly, the cyan ink is ejected to the landing position of the cyan liquid ejection head unit 210C (hereinafter referred to as “cyan landing position PC”). Further, the magenta ink is ejected to the landing position of the magenta liquid ejection head unit 210M (hereinafter referred to as “magenta landing position PM”). Further, the yellow ink is ejected to the landing position of the yellow liquid ejection head unit 210Y (hereinafter referred to as “yellow landing position PY”). The timing at which each liquid ejection head unit ejects ink is controlled by the controller 520 connected to each liquid ejection head unit.

Further, a plurality of rollers are installed for each liquid discharge head unit. As shown in the figure, for example, the plurality of rollers are installed on the upstream side and the downstream side, respectively, with each liquid discharge head unit interposed therebetween. In the illustrated example, for each liquid discharge head unit, a roller used to convey the web 120 to each landing position (hereinafter referred to as “first roller”) is installed on the upstream side of each liquid discharge head unit. To. Further, a roller (hereinafter referred to as "second roller") used to convey the web 120 downstream from each landing position is installed on the downstream side of each liquid discharge head unit. When the first roller and the second roller are installed in this way, so-called "fluttering" can be reduced at each landing position. The first roller and the second roller are used to convey a recording medium, and are, for example, driven rollers. Further, the first roller and the second roller may be rollers that are rotationally driven by a motor or the like.

The first roller, which is an example of the first support member, and the second roller, which is an example of the second support member, do not have to be a rotating body such as a driven roller. That is, the first roller and the second roller may be support members that support the object to be transported. For example, the first support member and the second support member may be a pipe or a shaft having a circular cross section. In addition, the first support member and the second support member may be a curved plate or the like whose portion in contact with the transported object has an arc shape. Hereinafter, an example will be described in which the first support member is a first roller and the second support member is a second roller.

Specifically, in order to eject black ink at a predetermined position on the web 120, a black first roller CR1K used for transporting the web 120 to the black landing position PK is installed. On the other hand, a second roller CR2K for black used for transporting the web 120 from the black landing position PK to the downstream side is installed. Similarly, the first roller CR1C for cyan and the second roller CR2C for cyan are installed on the cyan liquid discharge head unit 210C, respectively. Further, a first roller CR1M for magenta and a second roller CR2M for magenta are installed on the magenta liquid discharge head unit 210M, respectively. Further, a first roller CR1Y for yellow and a second roller CR2Y for yellow are installed on the yellow liquid discharge head unit 210Y, respectively.

An example of the outer shape of the liquid discharge head unit will be described with reference to FIG. Here, FIG. 3A is a schematic plan view showing an example of the four liquid discharge head units 210K to 210Y of the image forming apparatus 110 according to the embodiment of the present invention.

As shown in FIG. 3A, the liquid discharge head unit is a line type head unit in this embodiment. That is, the image forming apparatus 110 has four liquid ejection head units 210K, 210C corresponding to black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the transport direction 10 of the recording medium. 210M and 210Y are arranged.

Here, in the present embodiment, the black (K) liquid discharge head unit 210K has four heads 210K-1, 210K-2, 210K-3, and 210K-4 in a direction orthogonal to the transport direction 10 of the web 120. They are arranged in a staggered pattern. As a result, the image forming apparatus 110 can form an image in the entire width direction (direction orthogonal to the conveying direction) of the image forming area (printing area) of the web 120. Since the configurations of the other liquid discharge head units 210C, 210M and 210Y are the same as the configurations of the black (K) liquid discharge head unit 210K, the description thereof will be omitted.

Although the example in which the liquid discharge head unit is configured by four heads has been described here, the liquid discharge head unit may be configured by a single head.

<Example of detector>
In addition to the sensor installed for each liquid discharge head unit, a sensor for detecting the position of the recording medium in the orthogonal direction is installed. The example shown in FIG. 2 is an example in which a total of five sensors are installed, including four sensors installed for each liquid discharge head unit and one sensor installed on the upstream side of the four sensors. .. Hereinafter, in this example, one sensor is installed for each liquid discharge head unit, and each sensor, which is an example of the first detection unit, is generally referred to as a “first sensor”. On the other hand, a sensor installed upstream of the first sensor and which is an example of the second detection unit is called a "second sensor". Further, in the following description, each of the first sensor and the second sensor may be collectively referred to as a “sensor”.

The following description will be given with a total of five examples of sensors. The number of sensors is not limited to five. That is, the number of sensors may be larger than the number of liquid discharge head units by totaling the numbers of the first sensor and the second sensor. For example, two or more sensors may be installed for each liquid discharge head unit. Similarly, two or more second sensors may be installed.

As this sensor, an optical sensor or the like using light such as a laser, pneumatic, photoelectric, ultrasonic or infrared rays is used. The optical sensor may be, for example, a CCD (Charge Coupled Device) camera or the like. That is, the sensor constituting the first detection unit and the second detection unit is, for example, a sensor capable of detecting the edge of the recording medium. It should be noted that each sensor may be of the same type or may be of a different type. In the following description, all sensors are of the same type. Further, the sensor may have the configuration described below, for example.

FIG. 4 is an external view showing an example of an apparatus that realizes a detection unit according to an embodiment of the present invention. Further, the detection unit may be realized with a configuration as shown in the figure.

The illustrated sensor has a configuration in which an object such as a web is illuminated to form a speckle pattern. Specifically, the sensor has a semiconductor laser light source (LD) and a collimating optical system (CL). Further, the sensor has a CMOS image sensor for capturing an image of the speckle pattern and a telecentric imaging optical system (OL) for condensing and imaging the speckle pattern on the CMOS image sensor.

In the illustrated configuration example, the CMOS image sensor captures an image of the speckle pattern at each of the time T1 and the time T2 separated. Further, the cross-correlation calculation is performed by the FPGA circuit using the image of the speckle pattern captured at time T1 and the image of the speckle pattern captured at time T2. Based on the movement of the correlation peak position calculated by this cross-correlation calculation, the CMOS image sensor outputs the amount of movement of the object from time T1 to time T2 in the range in which the image is being captured. In the illustrated example, the size of the sensor is width W × depth D × height H is 15 × 60 × 32 [mm].

The CMOS image sensor is an example of an imaging unit, and the FPGA circuit is an example of an arithmetic unit.

Further, the correlation calculation is performed as follows, for example.

<Correlation calculation example>
FIG. 5 is a block diagram showing an example of a correlation calculation method according to an embodiment of the present invention. For example, the detection unit can calculate the relative position of the web at the position of the sensor, the movement amount, the movement speed, or a combination thereof, etc. by performing the correlation calculation according to the configuration as shown in the figure.

Specifically, as shown in the figure, the detection unit includes a first two-dimensional Fourier transform unit FT1, a second two-dimensional Fourier transform unit FT2, a correlation image data generation unit DMK, a peak position search unit SR, and a calculation unit CAL. And a configuration having a conversion result storage unit MEM.

The first two-dimensional Fourier transform unit FT1 converts the first image data D1. Specifically, the first two-dimensional Fourier transform unit FT1 has a configuration including a Fourier transform unit FT1a for the orthogonal direction and a Fourier transform unit FT1b for the transport direction.

The Fourier transform unit FT1a for the orthogonal direction performs a one-dimensional Fourier transform on the first image data D1 in the orthogonal direction. Then, the Fourier transform unit FT1b for the transport direction performs one-dimensional Fourier transform of the first image data D1 in the transport direction based on the conversion result by the Fourier transform unit FT1a for the orthogonal direction. In this way, the Fourier transform unit FT1a for the orthogonal direction and the Fourier transform unit FT1b for the transport direction perform one-dimensional Fourier transform in the orthogonal direction and the transport direction, respectively. The first two-dimensional Fourier transform unit FT1 outputs the conversion result converted in this way to the correlation image data generation unit DMK.

Similarly, the second two-dimensional Fourier transform unit FT2 transforms the second image data D2. Specifically, the second two-dimensional Fourier transform unit FT2 has a configuration including a Fourier transform unit FT2a for the orthogonal direction, a Fourier transform unit FT2b for the transport direction, and a complex conjugate unit FT2c.

The Fourier transform unit FT2a for the orthogonal direction performs a one-dimensional Fourier transform on the second image data D2 in the orthogonal direction. Then, the Fourier transform unit FT2b for the transport direction performs one-dimensional Fourier transform of the second image data D2 in the transport direction based on the conversion result by the Fourier transform unit FT2a for the orthogonal direction. In this way, the Fourier transform unit FT2a for the orthogonal direction and the Fourier transform unit FT2b for the transport direction perform one-dimensional Fourier transform in the orthogonal direction and the transport direction, respectively.

Next, the complex conjugate unit FT2c calculates the complex conjugate of the conversion result by the Fourier transform unit FT2a for the orthogonal direction and the Fourier transform unit FT2b for the transport direction. Then, the second two-dimensional Fourier transform unit FT2 outputs the complex conjugate calculated by the complex conjugate unit FT2c to the correlation image data generation unit DMK.

Subsequently, the correlated image data generation unit DMK has the conversion result of the first image data D1 output from the first two-dimensional Fourier transform unit FT1 and the second image output from the second two-dimensional Fourier transform unit FT2. Correlated image data is generated based on the conversion result of the data D2.

The correlation image data generation unit DMK has a configuration including an integration unit DMKa and a two-dimensional inverse Fourier transform unit DMKb.

The integration unit DMKa integrates the conversion result of the first image data D1 and the conversion result of the second image data D2. Then, the integration unit DMKa outputs the integration result to the two-dimensional inverse Fourier transform unit DMKb.

The two-dimensional inverse Fourier transform unit DMKb performs a two-dimensional inverse Fourier transform on the integration result by the integration unit DMKa. When the two-dimensional inverse Fourier transform is performed in this way, the correlated image data is generated. Then, the two-dimensional inverse Fourier transform unit DMKb outputs the correlation image data to the peak position search unit SR.

The peak position search unit SR searches for a peak position having a peak brightness (peak value) that has the steepest (that is, a steep rise) in the generated correlated image data. First, a value indicating the intensity of light, that is, the magnitude of brightness is input to the correlated image data. The brightness is input in a matrix.

In the correlated image data, the luminance is arranged at the pixel pitch interval of the area sensor, that is, the pixel size interval. Therefore, it is desirable that the search for the peak position is performed after performing so-called subpixel processing. In this way, when the sub-pixel processing is performed, the peak position can be searched with high accuracy. Therefore, the detection unit can accurately output the position, the movement amount, the movement speed, and the like.

For example, the search by the peak position search unit SR is performed as follows.

FIG. 6 is a diagram showing an example of a method for searching for a peak position in a correlation calculation according to an embodiment of the present invention. In the figure, the horizontal axis indicates the position in the transport direction in the image indicated by the correlation image data. On the other hand, the vertical axis indicates the brightness of the image indicated by the correlation image data.

Hereinafter, among the brightnesses indicated by the correlated image data, three data of the first data value q1, the second data value q2, and the third data value q3 will be described as an example. That is, in this example, the peak position search unit SR (FIG. 5) searches for the peak position P on the curve k connecting the first data value q1, the second data value q2, and the third data value q3.

First, the peak position search unit SR calculates each difference in the brightness of the image indicated by the correlation image data. Then, the peak position search unit SR extracts a combination of data values having the largest difference value among the calculated differences. Next, the peak position search unit SR extracts a combination adjacent to the combination of data values having the largest difference value. In this way, the peak position search unit SR can extract three data as shown in the illustrated first data value q1, second data value q2, and third data value q3. Then, when the curve k is calculated by connecting the three extracted data, the peak position search unit SR can search for the peak position P. By doing so, the peak position search unit SR can search for the peak position P at a higher speed by reducing the amount of calculation such as sub-pixel processing. The position of the combination of data values having the largest difference value is the steepest position. Further, the sub-pixel processing may be processing other than the above processing.

As described above, when the peak position search unit SR searches for the peak position, for example, the following calculation result can be obtained.

FIG. 7 is a diagram showing an example of a calculation result of a correlation calculation according to an embodiment of the present invention. The figure shows the correlation intensity distribution of the cross-correlation function. In the figure, the X-axis and the Y-axis indicate the serial numbers of the pixels. A peak position such as the illustrated "correlation peak" is searched by the peak position search unit SR (FIG. 5).

Returning to FIG. 5, the calculation unit CAL calculates the relative position, movement amount, movement speed, etc. of the web. For example, the calculation unit CAL can calculate the relative position and the amount of movement by calculating the difference between the center position of the correlation image data and the peak position searched by the peak position search unit SR.

Further, based on the relative position, the calculation unit CAL calculates the movement speed, for example, as in the following equation (1).

V = [{(K + J) × L} / √i] / T (1)

In the above equation (1), V is the moving speed. Further, T is an imaging cycle in which an image is captured. Further, K is a relative number of pixels. Furthermore, L is the pitch interval of the pixels. And J is a relative position. Further, i is the image pickup magnification of the area sensor.

As described above, the detection unit can detect the relative position, the movement amount, the movement speed, and the like by the correlation calculation. The detection method of relative position, movement amount, movement speed, etc. is not limited to this. For example, the detection unit may detect a relative position, a movement amount, a movement speed, or the like as follows.

First, the detection unit binarizes the brightness of each of the first image data and the second image data. That is, the detection unit sets "0" if the luminance is equal to or less than the preset threshold, and "1" if the luminance is larger than the threshold. The detection unit may detect the relative position by comparing the first image data and the second image data binarized in this way.

Further, the detection unit may detect a relative position, a movement amount, a movement speed, or the like by another detection method. For example, the detection unit may detect a relative position from each pattern reflected in each image data by so-called pattern matching processing or the like.

FIG. 8 is a functional block diagram showing an example of the functional configuration of the detection unit according to the embodiment of the present invention. As shown in the figure, the detection unit is composed of, for example, an image pickup unit 110F1, an image pickup control unit 110F2, a storage unit 110F3, a speed calculation unit 110F4, and the like. Each part shown in the figure is realized by, for example, the FPGA and the storage device shown in FIG.

Hereinafter, a case where imaging is performed twice by the imaging unit 110F1, that is, a case where two images are generated will be described as an example. Further, in the following description, the position where the first web 120 imaging is performed is referred to as "A position". Then, it is assumed that the second web 120 imaging is performed at the timing when the web 120 is conveyed and the pattern captured at the "A position" is moved to the "B position".

As shown in the figure, the image pickup unit 110F1 takes an image of the web 120 transported in the transport direction 10.

The image pickup control unit 110F2 has an image acquisition unit 110F21 and a shutter control unit 110F22.

The image acquisition unit 110F21 acquires an image captured by the image pickup unit 110F1.

The shutter control unit 110F22 controls the timing at which the image pickup unit 110F1 takes an image.

The storage unit 110F3 has a first storage area 110F31 and a second storage area 110F32.

The image when the pattern is in the "A position" and the image when the pattern is in the "B position" are stored in the first storage area 110F31 and the second storage area 110F32, respectively.

The speed calculation unit 110F4 has a pattern position of the web 120, a movement speed of the web 120, and a movement of the web 120 based on the respective images stored in the first storage area 110F31 and the second storage area 110F32. The amount etc. can be calculated. Further, the speed calculation unit 110F4 outputs data of a time difference Δt indicating the timing of releasing the shutter to the shutter control unit 110F22. That is, the speed calculation unit 110F4 outputs a trigger signal to the shutter control unit 110F22 so that the image indicating the “A position” and the image indicating the “B position” are imaged with a time difference Δt, respectively. Further, the speed calculation unit 110F4 may control a motor or the like that conveys the web 120 so as to have a calculated moving speed.

The web 120 is a member having a scattering property on the surface or inside. Therefore, when the web 120 is irradiated with the laser beam, the reflected light is diffusely reflected. Due to this diffuse reflection, a pattern is formed on the web 120. That is, the pattern is a spot called "speckle", a so-called speckle pattern. Therefore, when the web 120 is imaged, an image showing a speckle pattern is obtained. Since the position of the speckle pattern can be known from this image, it is possible to detect where the predetermined position of the web 120 is. It should be noted that this speckle pattern is generated because the irradiated laser beam interferes with the uneven shape formed on the surface or the inside of the web 120.

Further, the light source is not limited to the device using the laser beam. For example, the light source may be an LED (Light Emitting Diode), an organic EL (Electro-Luminescence), or the like. The pattern does not have to be a speckle pattern depending on the type of light source. Hereinafter, an example in which the pattern is a speckle pattern will be described.

Therefore, when the web 120 is conveyed, the speckle pattern of the web 120 is also conveyed. Therefore, if the same speckle pattern is detected at different times, the amount of movement can be obtained. That is, when the same speckle pattern is detected and the movement amount of the pattern is obtained, the speed calculation unit 110F4 can obtain the movement amount of the web 120. When the obtained movement amount is converted per unit time, the speed calculation unit 110F4 can obtain the movement speed at which the web 120 has moved.

As described above, based on the speckle pattern, the image forming apparatus can accurately obtain the detection result indicating the position of the web 120 in the orthogonal direction.

The sensor may detect the position in the transport direction and the like. That is, the sensor may also be used to detect the positions in the transport direction and the positions orthogonal to the transport direction. When used in this way, the cost can be reduced in each direction. In addition, since the number of sensors can be reduced, space can be saved.

Returning to FIG. 2, in the following description, the sensor installed for the black liquid discharge head unit 210K is referred to as “black sensor SENK”. Similarly, the sensor installed for the cyan liquid discharge head unit 210C is referred to as "cyan sensor SENC". Further, the sensor installed for the magenta liquid discharge head unit 210M is referred to as "magenta sensor SENM". Furthermore, the sensor installed for the yellow liquid discharge head unit 210Y is referred to as "yellow sensor SENY".

In the example shown in FIG. 2, the first sensor is, for example, a black sensor SENK, a cyan sensor SENC, a magenta sensor SENM, and a yellow sensor SENY. On the other hand, in the example shown in FIG. 2, the second sensor SEN2 is, for example, a sensor installed upstream of the first sensor, that is, the most upstream.

Further, in the following description, the "position where the sensor is installed" refers to a position where detection or the like is performed. Therefore, it is not necessary to install all the devices used for detection or the like at the "position where the sensor is installed", and the devices other than the sensor may be installed at other positions by being connected by a cable or the like. The black sensor SENK, the cyan sensor SENC, the magenta sensor SENM, the yellow sensor SENY, and the second sensor SEN2 shown in FIG. 2 show examples of positions where the sensors are installed.

As described above, it is desirable that the position where the first sensor is installed is close to each landing position. If the first sensor is installed at a position close to each landing position, the distance between each landing position and the first sensor becomes short. When the distance between each landing position and the first sensor becomes short, the error in detection can be reduced. Therefore, the image forming apparatus can accurately detect the position of the recording medium in the orthogonal direction by the first sensor.

The position close to each landing position is specifically between each first roller and each second roller. That is, in the illustrated example, it is desirable that the position where the black sensor SENK is installed is INTK1 between the black rollers as shown in the figure. Similarly, the position where the cyan sensor SENC is installed is preferably the cyan roller-to-roller INTC1 as shown in the figure. Further, it is desirable that the position where the magenta sensor SENM is installed is the magenta roller-to-roller INTM1 as shown in the figure. Furthermore, it is desirable that the position where the yellow sensor SENY is installed is INTY1 between the yellow rollers, as shown in the figure. In this way, when the first sensor is installed between the rollers, the first sensor can detect the position of the recording medium or the like at a position close to each landing position. In addition, the moving speed between the rollers is often relatively stable. Therefore, the image forming apparatus can accurately detect the position of the recording medium in the orthogonal direction.

It is desirable that the position where the first sensor is installed is closer to the first roller than the landing position between the rollers. That is, as shown in FIG. 2, it is desirable that the position where the first sensor is installed is on the upstream side of each landing position.

Specifically, the position where the black sensor SENK is installed is from the black landing position PK to the position where the black first roller CR1K is installed toward the upstream side (hereinafter referred to as "black upstream section INTK2"). .) Is desirable. Similarly, the position where the cyan sensor SENC is installed is from the cyan landing position PC to the position where the cyan first roller CR1C is installed toward the upstream side (hereinafter referred to as "cyan upstream section INTC2"). Is desirable. Further, the position where the magenta sensor SENM is installed is from the magenta landing position PM to the position where the magenta first roller CR1M is installed toward the upstream side (hereinafter referred to as "magenta upstream section INTM2"). It is desirable to have it. Furthermore, the position where the yellow sensor SENY is installed is from the yellow landing position PY to the position where the first yellow roller CR1Y is installed toward the upstream side (hereinafter referred to as "yellow upstream section INTY2"). Is desirable.

When the first sensor is installed in the upstream section INTK2 for black, the upstream section INTC2 for cyan, the upstream section INTM2 for magenta, and the upstream section INTY2 for yellow, the image forming apparatus accurately detects the position of the recording medium in the orthogonal direction. can. Further, when the first sensor is installed at such a position, the first sensor is installed on the upstream side of each landing position. Therefore, the image forming apparatus can first accurately detect the position of the recording medium in the orthogonal direction by the first sensor on the upstream side, and can calculate the timing at which each liquid discharge head unit discharges. That is, if the web 120 is conveyed to the downstream side while this calculation is being performed, each liquid ejection head unit can eject ink at the calculated timing.

If the position where the first sensor is installed is located directly under each liquid discharge head unit, color shift may occur due to a delay in the control operation or the like. Therefore, when the position where the first sensor is installed is on the upstream side of each landing position, the image forming apparatus can reduce the color shift and improve the image quality. Further, it may be restricted to set the vicinity of each landing position or the like as the position where the first sensor or the like is installed. Therefore, it is desirable that the position where the first sensor is installed is closer to each first roller than each landing position.

The position of the sensor may be, for example, directly below each of the liquid discharge head units. In this way, when the sensor is directly underneath, the accurate amount of movement underneath can be detected by the sensor. Therefore, if the control operation or the like can be performed quickly, it is desirable that the sensor is located closer to the position directly under each liquid discharge head unit. On the other hand, the sensor does not have to be directly under each liquid discharge head unit, and even if it is not directly under it, the same calculation is performed.

Further, if the error is acceptable, the position of the sensor may be directly under each of the liquid discharge head units or between each first roller and each second roller, and may be a position downstream from directly below.

On the other hand, it is desirable that the position where the second sensor SEN2 is installed is a position where the intervals of the first sensors are substantially equal to each other when the intervals are substantially equal to each other. Hereinafter, an example shown in FIG. 2 will be described. Specifically, the distance between the black sensor SENK and the cyan sensor SENC, the distance between the cyan sensor SENC and the magenta sensor SENM, and the distance between the magenta sensor SENM and the yellow sensor SENY are approximately equal. In some cases, the first sensor is installed. On the other hand, the position where the second sensor is installed is a position where the distance between the second sensor SEN2 and the black sensor SENK and the distance between the black sensor SENK and the cyan sensor SENK are approximately equal. Is desirable. The detection accuracy of each sensor is often calculated based on the spacing of each sensor. Therefore, if the intervals between the sensors are substantially equal, the detection accuracy by each sensor can be made uniform.

In addition, it is desirable that the position where the second sensor is installed is on the downstream side of the roller where there is wrapping or the like. For example, when the web wraps around a roller or the like, the web often fluctuates. Therefore, it is desirable that the second sensor detects after the wrapping occurs, that is, on the downstream side. By doing so, the influence of fluctuation due to wrapping or the like can be reduced by the detection result by the second sensor. The roller in which winding is likely to occur is the roller 230 in the example shown in FIG. As shown in the figure, the web 120 is liable to fluctuate when there is a roller or the like where the web 120 has a tight winding angle. Therefore, in the example shown in FIG. 2, it is desirable that the position where the second sensor is installed is a position downstream of the roller 230, as shown in the figure.

Further, the image forming apparatus may further include a measuring unit such as an encoder. Hereinafter, an example in which the measuring unit is realized by the encoder will be described. Specifically, the encoder is installed, for example, with respect to the rotation axis of the roller 230. In this way, the amount of movement in the transport direction can be measured based on the amount of rotation of the roller 230. When this measurement result is used together with the detection result by the sensor, the image forming apparatus can discharge the liquid to the web 120 with higher accuracy.

FIG. 9 is a diagram showing an example in which the position of the recording medium fluctuates in the orthogonal direction. Hereinafter, an example in which the web 120 is conveyed in the conveying direction 10 as shown in FIG. 9A will be described. As shown in this example, the web 120 is conveyed by a roller or the like. In this way, when the web 120 is conveyed, the position of the web 120 may change in the orthogonal direction, for example, as shown in FIG. 9B. That is, the web 120 may "meander" as shown in FIG. 9B.

The example shown in the figure is a case where the rollers are arranged diagonally. In the figure, the state of being “oblique” is described in an easy-to-understand manner, and the inclination of the rollers and the like may be less than in the illustrated example.

Changes in the position of the web 120 in the orthogonal direction, that is, "meandering", are caused by, for example, eccentricity of the rollers involved in transport, misalignment, cutting of the web 120 by a blade, or the like. Further, when the width of the web 120 is narrow with respect to the orthogonal direction, thermal expansion of the rollers and the like may affect the fluctuation of the position of the web 120 in the orthogonal direction.

For example, when vibration is generated due to eccentricity of a roller, cutting of a blade, or the like, the web 120 may "meander" as shown in the figure. In addition, the cutting by the blade is not uniform, and the web 120 may "meander" as shown in the figure due to the physical characteristics of the web 120, that is, the shape after the web 120 is cut, and the like. be.

FIG. 10 is a diagram showing an example of the cause of color shift. As described with reference to FIG. 9, when the position of the recording medium fluctuates in the orthogonal direction, that is, when "meandering" occurs, color shift is likely to occur due to the cause shown in FIG.

Specifically, when an image is formed on a recording medium using a plurality of colors, that is, when a color image is formed, the image forming apparatus discharges each liquid discharge head unit as shown in the figure. Inks of each color are layered to form a so-called color plane color image on the web 120.

On the other hand, there is a change in position as described in FIG. For example, "meandering" may occur with reference to the reference line 320. In this case, when each liquid ejection head unit ejects ink to the same position, the position of the web 120 changes in the orthogonal direction due to "meandering" between the liquid ejection head units, so that the color shift 330 May occur. That is, the color shift 330 occurs because the lines and the like formed by the ink ejected by each liquid ejection head unit are displaced in the orthogonal direction. As described above, when the color shift 330 occurs, the image quality of the image formed on the web 120 may deteriorate.

<Example of control unit>
The controller 520 (FIG. 2), which is an example of the control unit, has, for example, the configuration described below.

FIG. 11 is a block diagram showing an example of the hardware configuration of the control unit according to the embodiment of the present invention. For example, the controller 520 has a host device 71 such as an information processing device and a printer device 72. In the illustrated example, the controller 520 causes the printer device 72 to form an image on the recording medium based on the image data and the control data input from the host device 71.

The host device 71 is, for example, a PC (Personal Computer) or the like. Further, the printer device 72 has a printer controller 72C and a printer engine 72E.

The printer controller 72C controls the operation of the printer engine 72E. First, the printer controller 72C transmits / receives control data to / from the host device 71 via the control line 70LC. Further, the printer controller 72C transmits / receives control data to / from the printer engine 72E via the control line 72LC. By transmitting and receiving the control data, various printing conditions and the like indicated by the control data are input to the printer controller 72C, and the printer controller 72C stores the printing conditions and the like by the registers and the like. Next, the printer controller 72C controls the printer engine 72E based on the control data, and performs image formation according to the print job data, that is, the control data.

The printer controller 72C has a CPU 72Cp, a print control device 72Cc, and a storage device 72Cm. The CPU 72Cp and the print control device 72Cc are connected by a bus 72Cb and communicate with each other. Further, the bus 72Cb is connected to the control line 70LC via a communication I / F (interface) or the like.

The CPU 72Cp controls the operation of the entire printer device 72 by a control program or the like. That is, the CPU 72Cp is an arithmetic unit and a control unit.

The print control device 72Cc transmits / receives data indicating a command, status, or the like to / from the printer engine 72E based on the control data transmitted from the host device 71. As a result, the print control device 72Cc controls the printer engine 72E. Further, the storage unit 110F3 shown in FIG. 8 is realized by, for example, a storage device 72 Cm or the like. Further, the speed calculation unit 110F4 shown in FIG. 8 is realized by, for example, a CPU 72Cp or the like. The storage unit 110F3 and the speed calculation unit 110F4 may be realized by other arithmetic units and storage devices.

Data lines 70LD-C, 70LD-M, 70LD-Y and 70LD-K, that is, a plurality of data lines are connected to the printer engine 72E. Then, the printer engine 72E receives the image data from the host device 71 via the plurality of data lines. Next, the printer engine 72E forms an image of each color based on the control by the printer controller 72C.

The printer engine 72E has data management devices 72EC, 72EM, 72EY and 72EK, that is, a plurality of data management devices. Further, the printer engine 72E has an image output device 72Ei and a transfer control device 72Ec.

FIG. 12 is a block diagram showing an example of the hardware configuration of the data management device included in the control unit according to the embodiment of the present invention. For example, a plurality of data management devices have the same configuration. Hereinafter, an example in which each data management device has the same configuration will be described, and the data management device 72EC will be described as an example. Therefore, duplicate description will be omitted.

The data management device 72EC has a logic circuit 72ECl and a storage device 72ECm. As shown in the figure, the logic circuit 72ECl is connected to the host device 71 via the data line 70LD-C. Further, the logic circuit 72ECl is connected to the print control device 72Cc via the control line 72LC. The logic circuit 72ECl is realized by an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or the like.

The logic circuit 72ECl stores the image data input from the host device 71 in the storage device 72ECm based on the control signal input from the printer controller 72C (FIG. 11).

Further, the logic circuit 72ECl reads out the image data Ic for cyan from the storage device 72ECm based on the control signal input from the printer controller 72C. Next, the logic circuit 72ECl sends the read image data Ic for cyan to the image output device 72Ei.

It is desirable that the storage device 72ECm has a capacity of storing about 3 pages of image data. When the image data of about 3 pages can be stored, the storage device 72ECm can store the image data input from the host device 71, the image data during image formation, and the image data for next image formation.

FIG. 13 is a block diagram showing an example of the hardware configuration of the image output device included in the control unit according to the embodiment of the present invention. As shown in the figure, the image output device 72Ei includes an output control device 72Eic, a black liquid discharge head unit 210K, a cyan liquid discharge head unit 210C, a magenta liquid discharge head unit 210M, and a yellow liquid discharge head, which are liquid discharge head units of each color. It has a unit 210Y.

The output control device 72Eic outputs image data of each color to the liquid discharge head unit of each color. That is, the output control device 72Eic controls the liquid discharge head unit of each color based on the input image data.

The output control device 72Eic controls a plurality of liquid discharge head units simultaneously or individually. That is, the output control device 72Eic receives the input of the timing and controls to change the timing of discharging the liquid to each liquid discharge head unit. The output control device 72Eic may control any of the liquid discharge head units based on the control signal input from the printer controller 72C (FIG. 11). Further, the output control device 72Eic may control any of the liquid discharge head units based on an operation by the user or the like.

The printer device 72 shown in FIG. 11 has different routes for inputting image data from the higher-level device 71 and for transmission / reception between the higher-level device 71 and the printer device 72 based on the control data. This is an example.

Further, the printer device 72 may be configured to form an image with, for example, one black color. In the case of performing image formation with one black color, in order to increase the speed of image formation, for example, a configuration having one data management device and four black liquid discharge head units may be used. In this way, the black ink is ejected by each of the plurality of black liquid ejection head units. Therefore, faster image formation can be performed as compared with the configuration in which one black liquid discharge head unit is used.

The transport control device 72Ec (FIG. 11) is a motor or the like that transports the web 120. For example, the transport control device 72Ec controls a motor or the like connected to each roller or the like to transport the web 120.

<Overall processing example>
FIG. 14 is a flowchart showing an example of overall processing by the device for discharging the liquid according to the embodiment of the present invention. For example, it is assumed that image data indicating an image formed on the web 120 (FIG. 1) is input to the image forming apparatus 110 in advance. Next, the image forming apparatus 110 performs the whole processing shown in FIG. 14 based on the image data, and forms the image shown by the image data on the web 120.

Note that FIG. 14 shows the processing for one liquid discharge head unit. That is, FIG. 14 is, for example, in the example shown in FIG. 2, the process relating to the black liquid discharge head unit 210K. Further, for the liquid discharge head units of other colors, for example, the processes shown in FIG. 14 are performed separately in parallel or before and after.

In step S01, the image forming apparatus calculates the amount of fluctuation of the transported object based on the plurality of sensor data. That is, in step S01, the image forming apparatus first detects the position of the web 120 in the orthogonal direction by each sensor. Next, the image forming apparatus acquires sensor data indicating each detection result output from each sensor. Subsequently, the amount of fluctuation of the recording medium or the like is calculated based on the plurality of sensor data, that is, the plurality of detection results. The details of the calculation method will be described later.

In step S02, the image forming apparatus moves the liquid discharge head unit in the direction orthogonal to the transport direction of the web. Further, step S02 is performed based on the detection result in step S01. Further, in step S02, the liquid discharge head unit is moved so as to compensate for the change in the position of the web 120 in the direction orthogonal to the transport direction indicated by the detection result in step S01. For example, in step S02, the image forming apparatus moves the liquid discharge head unit to compensate for the change in the position of the web 120 by the amount of the change in the position of the web 120 detected in step S01.

FIG. 15 is a block diagram showing an example of a hardware configuration for moving a liquid discharge head unit included in the liquid discharge device according to the embodiment of the present invention. The configuration shown in the figure is an example in which the image forming apparatus 110 has a plurality of actuators and a plurality of sensors. Further, the configuration shown in the figure is an example in which the control device CTRL is connected to the image forming device 110. Further, the control device CTRL has a CPU 221, a ROM (Read-Only Memory) 222, and a RAM (Random Access Memory) 223. Further, as shown in the figure, each device may have an interface that becomes an I / O (Input / Output) in order to send and receive data and the like to and from other devices.

The configuration is not limited to the illustrated example. That is, each of the illustrated devices may be included in the image forming device or may be an external device.

Further, each device may be shared. For example, the CPU 221 and the like may be shared with the CPU and the like for realizing the detection unit, or may be separate.

The CPU 221 is an example of an arithmetic unit and a control unit. Specifically, the CPU 221 acquires the detection results of each sensor and performs calculations and the like for calculating the amount of fluctuation of the transported object. Further, the CPU 221 controls each actuator and controls to move each head unit and the like.

ROM 222 and RAM 223 are examples of storage devices. For example, the ROM 222 stores programs, data, and the like used by the CPU 221. Further, the RAM 223 stores a program or the like used by the CPU 222 to perform an operation, and serves as a storage area for realizing each operation.

The speed detection circuit SCR is an electronic circuit that detects the moving speed at which the object to be conveyed is conveyed. For example, a "6 ppi" signal or the like is input to the speed detection circuit SCR. Next, the speed detection circuit SCR calculates the speed at which the object to be transported is conveyed based on the detection result from each sensor, the detection result from the encoder, and the like, and transmits the speed to the CPU 221 and the like. The speed detection circuit SCR may be the same as or different from the FPGA shown in FIG.

Each actuator is connected to a respective liquid discharge head unit to be moved. Specifically, the first actuator AC1 is connected to the black liquid discharge head unit 210K. That is, the first actuator AC1 moves the black liquid discharge head unit 210K. Similarly, the second actuator AC2 is connected to the cyan liquid discharge head unit 210C. That is, the second actuator AC2 moves the cyan liquid discharge head unit 210C in the direction orthogonal to the transport direction of the web. Further, the third actuator AC3 is connected to the magenta liquid discharge head unit 210M. That is, the third actuator AC3 moves the magenta liquid discharge head unit 210M. Further, the fourth actuator AC4 is connected to the yellow liquid discharge head unit 210Y. That is, the fourth actuator AC4 moves the yellow liquid discharge head unit 210Y.

That is, each actuator moves each liquid discharge head unit by, for example, the following moving mechanism.

FIG. 16 is a block diagram showing an example of a moving mechanism for moving the liquid discharging head included in the device for discharging the liquid according to the embodiment of the present invention. For example, the moving mechanism is realized by hardware or the like as shown in the figure. The illustrated example is an example of a moving mechanism for moving the cyan liquid discharge head unit 210C.

First, in the illustrated example, an actuator ACT such as a linear actuator that moves the cyan liquid discharge head unit 210C is installed in the cyan liquid discharge head unit 210C. A control device CTRL that controls the actuator ACT is connected to the actuator ACT.

The actuator ACT is, for example, a linear actuator or a motor. Further, the actuator ACT may include a control circuit, a power supply circuit, a mechanical component, and the like.

The detection result in step S01 shown in FIG. 14 is input to the control device CTRL. Then, the control device CTRL moves the cyan liquid discharge head unit 210C by the actuator ACT so as to compensate for the change in the position of the web 120 indicated by the detection result (step S02 shown in FIG. 14).

In the illustrated example, the detection result is, for example, variation Δ. Therefore, in this example, the control device CTRL moves the cyan liquid discharge head unit 210C in the orthogonal direction 20 so as to compensate for the fluctuation Δ.

Returning to FIG. 15, the detection result by each sensor is transmitted to the control device CTRL. Specifically, the second sensor SEN2 is connected to the control device CTRL. Further, the first sensor SEN1 is connected to the control device CTRL. In this example, the first sensor SEN1 is a black sensor SENK, a cyan sensor SENC, a magenta sensor SENM, and a yellow sensor SENY.

FIG. 17 is a timing chart showing an example of a method of calculating the amount of fluctuation of the transported object by the device for discharging the liquid according to the embodiment of the present invention. As shown in the figure, the control device CTRL (FIG. 15) calculates the fluctuation amount based on a plurality of detection results. Specifically, the control device CTRL outputs a calculation result indicating the fluctuation amount based on the first detection result S1 and the second detection result S2. First, the first detection result S1 and the second detection result S2 are the detection results indicated by the sensor data output from any two of the first sensor SEN1 and the second sensor SEN2 shown in FIG. .. Next, each sensor data is transmitted to the control device CTRL, and the detection result is stored in the RAM 223. Subsequently, the control device CTRL calculates the fluctuation amount from the plurality of detection results indicated by each sensor data.

The amount of fluctuation is calculated for each liquid discharge head unit. Hereinafter, an example of calculating the fluctuation amount for the cyan liquid discharge head unit 210C (FIG. 2) will be described. In this example, the fluctuation amount is based on, for example, the detection result by the cyan sensor SENC (FIG. 2) and the detection result by the black sensor SENK (FIG. 2) installed one upstream side from the cyan sensor SENC. Is calculated. In FIG. 17, the first detection result S1 is a detection result by the black sensor SENK. On the other hand, the second detection result S2 is a detection result by the cyan sensor SENC.

It is assumed that the distance between the black sensor SENK and the cyan sensor SENC, that is, the distance between the sensors is "L2". Further, it is assumed that the moving speed detected by the speed detection circuit SCR is "V". Further, it is assumed that the moving time required for the transported object to be transported from the position of the black sensor SENK to the position of the cyan sensor SENC is "T2". In this case, the travel time is calculated as "T2 = L2 / V".

Further, the sampling interval by the sensor is set to "A". Further, the number of samplings between the black sensor SENK and the cyan sensor SENC is set to "n". In this case, the number of samplings is calculated as "n = T2 / A".

The illustrated calculation result, that is, the fluctuation amount is defined as “ΔX”. For example, as shown in the figure, when the detection cycle is “0”, the fluctuation amount is the first detection result S1 before the travel time “T2” and the second detection result S2 of the detection cycle “0”. Calculated by comparison. Specifically, the fluctuation amount is calculated as "ΔX = X2 (0) −X1 (n)". Then, when the position of the sensor is closer to the first roller than the landing position, the image forming apparatus calculates the change in the position of the recording medium when the paper moves to the position of the sensor and drives the actuator. Let me.

Next, the image forming apparatus controls the second actuator AC2 (FIG. 15) so as to compensate for the fluctuation amount “ΔX”, and moves the cyan liquid discharge head unit 210C (FIG. 16) in the orthogonal direction. By doing so, even if the position of the transported object fluctuates, the image forming apparatus can accurately form an image on the transported object. Further, as shown in the figure, when the fluctuation amount is calculated based on the two detection results, that is, the detection results by the two sensors, the fluctuation amount can be calculated without integrating the position information of each sensor. Therefore, by doing so, the accumulation of detection errors by each sensor can be reduced.

The fluctuation amount may be calculated in the same manner in another liquid discharge head unit. For example, the fluctuation amount for the black liquid discharge head unit 210K (FIG. 2) is calculated by the first detection result S1 by the second sensor SEN2 (FIG. 15) and the second detection result S2 by the black sensor SENK. Similarly, the fluctuation amount for the magenta liquid discharge head unit 210M (FIG. 2) is calculated by the first detection result S1 by the cyan sensor SENC and the second detection result S2 by the magenta sensor SENM. Further, the fluctuation amount for the yellow liquid discharge head unit 210Y (FIG. 2) is calculated by the first detection result S1 by the magenta sensor SENM and the second detection result S2 by the yellow sensor SENY.

Further, the detection result used for the first detection result S1 is not limited to the detection result detected by the sensor installed one upstream side from the moving liquid discharge head unit. That is, the first detection result S1 may be a detection result detected by a sensor installed on the upstream side of the liquid discharge head unit to be moved. For example, the fluctuation amount for the yellow liquid discharge head unit 210Y may be calculated by using the detection result of the second sensor SEN2, the black sensor SENK, or the cyan sensor SENC for the first detection result S1. ..

On the other hand, it is desirable that the second detection result S2 is a detection result by a sensor installed at a position closest to the liquid discharge head unit to be moved.

Further, the fluctuation amount may be calculated based on three or more detection results.

In this way, the liquid ejection head unit is moved based on the fluctuation amount calculated from the plurality of detection results, and when the liquid is ejected to the web, an image or the like is formed on the recording medium.

<Processing result example>
FIG. 18 is a diagram showing an example of a test pattern used by the device for discharging the liquid according to the embodiment of the present invention. First, as shown in the figure, the image forming apparatus performs test printing in black, which is an example of the first color, so that a straight line is formed in the transport direction 10. From the result of this test print, the distance Lk from the edge can be obtained. In this way, when the distance Lk from the edge is adjusted manually or manually in the orthogonal direction, the position where the first color, that is, the reference black ink is ejected is determined.

Further, it is desirable that the position where the first sensor is installed is closer to the first roller than the landing position.

FIG. 19 is a diagram showing an example of a position where a first sensor is installed in a device for discharging a liquid according to an embodiment of the present invention. Hereinafter, black will be described as an example. In this example, it is desirable that the black sensor SENK is installed between the black first roller CR1K and the black second roller CR2K at a position closer to the black first roller CR1K than the black landing position PK. .. The distance close to the first roller CR1K for black is determined based on the time required for the control operation and the like. For example, the distance close to the first roller CR1K for black is set to "20 mm". In this case, the position where the black sensor SENK is installed is an example in which the position is "20 mm" upstream from the black landing position PK.

In this example, the black sensor SENK detects the position POS of the web 120 in the orthogonal direction. For example, the position POS is the position of the edge portion on the web 120 and the like. The position POS is not limited to the position of the edge portion, but may be the position of another portion. As shown in the figure, the position where the black sensor SENK is installed is upstream from the black landing position PK and is at a different position. In such a case, a detection error E1 occurs between the position POS at the black landing position PK and the position POS at the position where the black sensor SENK is installed. The closer the distance between the position where the black sensor SENK is installed and the black landing position PK is, the smaller the detection error E1 becomes.

As described above, when the position where the first sensor is installed is close to the landing position, the detection error E1 becomes small. Further, when the detection error E1 is small, the image forming apparatus can accurately land the liquid of each color. Therefore, when image formation is performed, the image forming apparatus can accurately land the liquids of each color, so that color shift can be reduced and the image quality of the formed image can be improved.

Further, with such a configuration, for example, there is no restriction that the distance between the liquid discharge head units must be an integral multiple of the peripheral length of the roller 230 (FIG. 2), so that the liquid discharge head unit is installed. You can freely position it. That is, the image forming apparatus can accurately land the liquids of each color even if the distance between the liquid discharge head units is a non-integer multiple of the peripheral length of the roller 230.

<Comparison example>
FIG. 20 is a diagram showing an example of the hardware configuration in the first comparative example. In the illustrated first comparative example, the position of the web 120 is detected before each liquid discharge head unit reaches the position where the liquid is discharged. For example, in this comparative example, the position where the sensor is installed is a position that is "200 mm" from directly below the liquid discharge head unit to the upstream. Based on the detection result in this case, the image forming apparatus according to the first comparative example moves the liquid ejection head unit to compensate for the position fluctuation of the recording medium.

FIG. 21 is a diagram showing an example of processing results of the entire processing by the apparatus for discharging the liquid according to the first comparative example. In this comparative example, the liquid discharge head unit is installed so that the distance between the liquid discharge head units is an integral multiple of the circumference of the roller. In this case, the difference between the position of the web detected by each sensor and the position of the web directly under the liquid discharge head unit is “0”. Therefore, in this comparative example, assuming that the landing position of the liquid with respect to the web of each color ink is the distances "Lk1", "Lc1", "Lm1" and "Ly1" from the web end, "Lk1 = Lc1 = Lm1 = Ly1". ". In this way, the misalignment is corrected.

FIG. 22 is a diagram showing an example of processing results of the entire processing by the apparatus for discharging the liquid according to the second comparative example. The second comparative example has the same hardware configuration as the first comparative example. Compared with the first comparative example, the second comparative example is different in that the distance between the black and cyan liquid discharge head units and the distance between the magenta and yellow liquid discharge head units are "1.75d", respectively. That is, the second comparative example is an example in which the distance between the black and cyan liquid discharge head units and the distance between the magenta and yellow liquid discharge head units are non-integer multiples of the peripheral length d of the rollers, respectively.

In this second comparative example, the difference between the position of the web detected by the black sensor SENK and the position of the web under the black liquid discharge head unit 210K is defined as "Pk". Similarly, the difference between the position of the web detected by the cyan sensor SENC and the position of the web under the cyan liquid discharge head unit 210C is defined as "Pc". Further, the difference between the position of the web detected by the magenta sensor SENM and the position of the web 120 under the magenta liquid discharge head unit 210M is defined as "Pm". Furthermore, the difference between the position of the web detected by the yellow sensor SENY and the position of the web 120 under the yellow liquid discharge head unit 210Y is defined as "Py". Further, in the second comparative example, assuming that the landing position of the liquid of each color ink on the web is the distances "Lk2", "Lc2", "Lm2" and "Ly2" from the web end, the following equation (2) is obtained. Can show a good relationship.

Lc2 = Lk2-Pc
Lm2 = Lk2
Ly2 = Lk2-Py (2)
Therefore, "Lk2 = Lm2 ≠ Lc2 = Ly2". As described above, when the distance between the liquid discharge head units is a non-integer multiple of the peripheral length d of the roller, in this comparative example, the position of the web directly under the cyan liquid discharge head unit 210C and the magenta liquid discharge head unit 210M. Is different because it deviates by "Pc" and "Py". Therefore, the position fluctuation of the web is not compensated, and color shift or the like is likely to occur.

FIG. 23 is a diagram showing an example of a position where a sensor is installed in a device for discharging a liquid according to a comparative example. As shown in the figure, in the comparative example, the sensor is installed at a position farther than the landing position. Therefore, the detection error E2 in the comparative example often becomes large.

<Function configuration example>
FIG. 24 is a functional block diagram showing an example of the functional configuration of the device for discharging the liquid according to the embodiment of the present invention. As shown in the figure, the image forming apparatus 110 includes a plurality of liquid discharge head units and a plurality of detection units 110F10. Further, the image forming apparatus 110 includes a movement control unit 110F20. Further, the configuration shown in the figure is an example in which the calculation unit 110F30 is provided for each liquid discharge head unit.

For the transported object, each liquid discharge head unit is installed at a different position on the transport path, for example, as shown in FIG. Hereinafter, among the plurality of liquid discharge head units, a portion such as the liquid discharge head unit for black shown in FIG. 2 will be described as an example.

Further, as shown in the figure, the image forming apparatus 110 is preferably configured to include the measuring unit 110F40.

As shown in the figure, the detection unit 110F10 is provided for each liquid discharge head unit. Specifically, in the example shown in FIG. 2, the number of detection units 110F10 is four as shown in the figure. These detection units are the first detection unit 110F101. On the other hand, the detection unit installed on the upstream side of the first detection unit 110F101 is the second detection unit 110F102. Further, each detection unit 110F10 detects the position of the recording medium in the orthogonal direction of the web 120. Each detection unit 110F10 is realized by, for example, the hardware configuration shown in FIG. 4 or the like. Further, the first detection unit 110F101 and the second detection unit 110F102 are each one or more detection units 110F10.

As shown in the figure, the first roller is provided for each liquid discharge head unit. Specifically, in the example shown in FIG. 2, the number of first rollers is four, which is the same as the number of liquid discharge head units. Further, the first roller is a roller used to convey the recording medium to a landing position where the liquid discharge head unit can discharge the liquid to a predetermined position of the recording medium. That is, the first roller is a roller installed on the upstream side of each landing position. The first roller is, for example, the first roller CR1K for black (FIG. 2) in the case of black.

As shown in the figure, the second roller is provided for each liquid discharge head unit. Specifically, in the example shown in FIG. 2, the number of the second rollers is four, which is the same as the number of the liquid discharge head units. The second roller is a roller used to convey the recording medium from the landing position to another position. That is, the second roller is a roller installed on the downstream side of each landing position. The second roller is, for example, a black second roller CR2K (FIG. 2) in the case of black.

The calculation unit 110F30 compares a plurality of detection results and calculates the fluctuation amount. For example, the calculation unit 110F30 calculates the fluctuation amount as shown in FIG. The calculation unit 110F30 is realized by, for example, CPU 221 (FIG. 15).

The movement control unit 110F20 moves the liquid discharge head unit based on the detection results of the plurality of detection units 110F10. For example, the movement control unit 110F20 moves the liquid discharge head unit so as to compensate for the fluctuation amount calculated by the calculation unit 110F30. The movement control unit 110F20 is realized by, for example, the hardware and the movement mechanism shown in FIGS. 15 and 16. Further, the movement control unit 110F20 may be configured to control a plurality of liquid discharge head units as shown in the figure, while the movement control unit 110F20 may be configured to be separately provided for each liquid discharge head unit.

As described above, when the movement control unit 110F20 moves each liquid discharge head unit based on the plurality of detection results by each detection unit 110F10, the image forming apparatus 110 moves the landing position of the discharged liquid in the orthogonal direction. The accuracy of can be further improved.

Further, preferably, the position where the detection unit of the first detection unit 110F101 performs detection, that is, the position where the sensor is installed, is close to the landing position of the black landing position PK or the like, such as the black roller-to-roller INTK1 or the like. The position is good. That is, when the detection is performed by the black roller-to-roller INTK1 or the like, the image forming apparatus 110 can accurately detect the position of the recording medium or the like in the orthogonal direction.

Further, preferably, the position where the detection unit of the first detection unit 110F101 performs detection, that is, the position where the sensor is installed, is located upstream of the landing position among the rollers, such as the black upstream section INTK2. The position on the side is better. That is, when the detection is performed in the black upstream section INTK2 or the like, the image forming apparatus 110 can accurately detect the position of the recording medium or the like in the orthogonal direction.

<Summary>
The device for discharging a liquid according to an embodiment of the present invention detects the position of an object to be transported such as a recording medium in a orthogonal direction at a position close to the liquid discharge head unit for each liquid discharge head unit. Further, the device for discharging the liquid detects the position of the object to be transported on the upstream side of the moving liquid discharge head unit. The combination of the detection results used depends on the liquid discharge head unit to be moved. For example, an example of calculating the fluctuation amount based on the combination of the detection result by the detection unit 110F10 provided on the upstream side and the detection result by the detection unit 110F10 closest to the liquid discharge head unit to be moved will be described. In this example, the combination of detection results used to calculate the fluctuation amount is the first combination RES1, the second combination RES2, the third combination RES3, and the fourth combination RES4, as shown in the figure. In this way, the fluctuation amount is calculated for each liquid discharge head unit based on the first combination RES1, the second combination RES2, the third combination RES3, and the fourth combination RES4. When the fluctuation amount is calculated based on these combinations, the accuracy of each calculated fluctuation amount tends to be uniform.

When the position of the object to be transported is detected by one detection unit, the range in which the detection is performed may be narrow. Therefore, the accuracy may be insufficient with the fluctuation amount calculated based on the detection result by one detection unit. On the other hand, when a plurality of detection results are combined as in one embodiment of the present invention, the fluctuation amount can be calculated more accurately than the fluctuation amount calculated based on the detection result by one detection unit. Further, by combining a plurality of detection results in this way, it is possible to calculate the amount of fluctuation due to the fluctuation of the transported object generated between the sensors and the variation of the transported object generated between the sensor and the liquid discharge head unit. .. That is, when a plurality of detection results are combined, the device that discharges the liquid can accurately compensate for these fluctuations.

Next, the device for discharging the liquid according to the embodiment of the present invention moves the liquid discharge head unit based on the fluctuation amount calculated from the combination of the detection results. Therefore, the device for discharging the liquid according to the embodiment of the present invention discharges the liquid according to the embodiment of the present invention as compared with the first comparative example and the second comparative example shown in FIGS. 21 and 22. The device can accurately compensate for the deviation generated at the landing position of the liquid in the orthogonal direction.

Further, in the device for discharging the liquid according to the embodiment of the present invention, it is not necessary to arrange each liquid discharge head unit at a position obtained by multiplying the peripheral length of the roller by an integer, as in the first comparative example, so that each liquid is not required. The restrictions on installing the discharge head unit can be reduced. Further, in the first comparative example and the second comparative example, the adjustment cannot be performed in the first color, that is, in the black in this example, without the actuator. On the other hand, the device for discharging the liquid according to the embodiment of the present invention can further improve the accuracy of the landing position of the discharged liquid in the orthogonal direction even for the first color.

Further, in the case of ejecting a liquid to form an image on a recording medium, the device for ejecting the liquid according to the embodiment of the present invention causes color shift when the landing position of the discharged liquid of each color becomes accurate. The number is reduced, and the image quality of the formed image can be improved.

Further, if the measurement unit 110F40 is provided, the position of the recording medium and the like can be detected more accurately. For example, it is assumed that a measuring device such as an encoder is installed on the rotating shaft of the roller 230. Then, the measuring unit 110F40 measures the movement amount of the recording medium by an encoder or the like. As described above, when the measurement result measured by the measurement unit 110F40 is further input, the image forming apparatus 110 can more reliably detect the position of the recording medium in the transport direction and the like.

<Modification example>

The device for discharging the liquid according to the present invention may be realized by a system for discharging the liquid having one or more devices. For example, the black liquid discharge head unit 210K and the cyan liquid discharge head unit 210C are devices having the same housing, and the magenta liquid discharge head unit 210M and the yellow liquid discharge head unit 210Y are devices having the same housing, both of which are included. It may be realized by a system that discharges a liquid.

Further, in the liquid ejection device and the liquid ejection system according to the present invention, the liquid is not limited to ink, but may be another type of recording liquid, fixing treatment liquid, or the like. That is, the liquid ejection device and the liquid ejection system according to the present invention may be applied to a liquid ejection device other than ink.

Therefore, the device for discharging the liquid and the system for discharging the liquid according to the present invention are not limited to forming an image. For example, the formed object may be a three-dimensional model or the like.

The first support member and the second support member may also be used. For example, the first support member and the second support member may have the following configurations.

FIG. 25 is a schematic view showing a modified example of the device for discharging the liquid according to the embodiment of the present invention. As compared with FIG. 2, in the illustrated configuration, the arrangement of the first support member and the second support member is different. As shown in the figure, the first support member and the second support member may be realized by, for example, the first member RL1, the second member RL2, the third member RL3, the fourth member RL4, and the fifth member RL5. .. That is, the second support member provided on the upstream side of each liquid discharge head unit and the first support member provided on the downstream side of each liquid discharge head unit may be shared. The first support member and the second support member may be combined with a roller or a curved plate.

Further, the object to be transported is not limited to a recording medium such as paper. The material to be transported may be any material to which liquid can adhere. For example, the material to which the liquid can be attached may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, or a combination thereof, as long as the liquid can be attached even temporarily.

Further, in the embodiment of the present invention, it may be realized by a program for executing a part or all of the methods of discharging the liquid to a computer such as an image forming apparatus, an information processing apparatus, or a combination thereof.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiment, and various modifications are made within the scope of the gist of the present invention described in the claims. Or it can be changed.

110 Image Forming Device 120 Web 210K Black Liquid Discharge Head Unit 210C Cyan Liquid Discharge Head Unit 210M Magenta Liquid Discharge Head Unit 210Y Yellow Liquid Discharge Head Unit SENK Black Sensor SENC Cyan Sensor SENM Magenta Sensor 520 Controller S1 1 Detection result S2 Second detection result

Japanese Unexamined Patent Publication No. 2015-13476

Claims (14)

A first liquid discharge head unit that discharges liquid to the transported object, and
A first support member provided on the upstream side of the landing position where the liquid discharged by the first liquid discharge head unit lands on the transported object, and supports the transported object.
A second support member provided on the downstream side of the landing position and supporting the object to be transported, and a second support member.
It is arranged between the first support member and the second support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The first detector and
A second liquid discharge head unit provided downstream of the second support member and discharging liquid to the transported object, and a second liquid discharge head unit.
A third support member provided on the upstream side of the second liquid discharge head unit and on the downstream side of the second support member to support the transported object, and a third support member.
A fourth support member provided on the downstream side of the second liquid discharge head unit and supporting the object to be transported, and a fourth support member.
It is arranged between the third support member and the fourth support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The second detector and
A device for discharging a liquid, comprising: a movement control unit for moving the second liquid discharge head unit based on the detection result of the first detection unit and the detection result of the second detection unit. A first liquid discharge head unit that discharges liquid to the transported object, and
A first support member provided on the upstream side of the landing position where the liquid discharged by the first liquid discharge head unit lands on the transported object, and supports the transported object.
A second support member provided on the downstream side of the landing position and supporting the object to be transported, and a second support member.
It is arranged between the first support member and the second support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The first detector and
A second liquid discharge head unit provided downstream of the second support member and discharging liquid to the transported object, and a second liquid discharge head unit.
A fourth support member provided on the downstream side of the second liquid discharge head unit and supporting the object to be transported, and a fourth support member.
It is arranged between the second support member and the fourth support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The second detector and
A device for discharging a liquid, comprising: a movement control unit for moving the second liquid discharge head unit based on the detection result of the first detection unit and the detection result of the second detection unit. The device for discharging a liquid according to claim 1 or 2, wherein the position of the first detection unit is a position between the landing position and the first support member. The liquid according to any one of claims 1 to 3, wherein the movement control unit moves the liquid discharge head unit in a direction orthogonal to the direction in which the object to be transported is conveyed. Equipment to do. The device for discharging a liquid according to any one of claims 1 to 4, wherein the first detection unit and the second detection unit use an optical sensor. The device for discharging the liquid according to claim 5, wherein the first detection unit and the second detection unit each obtain the detection result based on the pattern of the transported object. The pattern is generated by the interference of light applied to the uneven shape formed on the object to be transported.
The device for discharging the liquid according to claim 6, wherein the first detection unit and the second detection unit each obtain the detection result based on an image obtained by capturing the pattern. Further, a measuring unit for measuring the amount of movement in the transport direction in which the object to be transported is transported is provided.
The device for discharging the liquid according to any one of claims 1 to 7, wherein the liquid is discharged based on the movement amount measured by the measuring unit and the detection result. The device for discharging a liquid according to any one of claims 1 to 8, wherein the transported object is a sheet that is long and continuous along the transport direction. At least, it is arranged at a position different from the first detection unit and the second detection unit, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. With one other detector,
Among the first detection unit, the second detection unit, and at least one other detection unit, the detection unit closest to the second liquid discharge head unit is the second detection unit. The device for discharging the liquid according to any one of claims 1 to 9. At least, it is arranged at a position different from the first detection unit and the second detection unit, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. With one other detector,
Any of claims 1 to 9, wherein the first detection unit, the second detection unit, and at least one other detection unit are installed at positions where the intervals between the detection units are equal. The device for discharging the liquid according to item 1. The device for discharging a liquid according to any one of claims 1 to 11, wherein the light source of the first detection unit and the second detection unit is an LED or an organic EL. A system that has one or more devices and discharges liquid.
A first liquid discharge head unit that discharges liquid to the transported object, and
A first support member provided on the upstream side of the landing position where the liquid discharged by the first liquid discharge head unit lands on the transported object, and supports the transported object.
A second support member provided on the downstream side of the landing position and supporting the object to be transported, and a second support member.
It is arranged between the first support member and the second support member , and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The first detector and
A second liquid discharge head unit provided downstream of the second support member and discharging liquid to the transported object, and a second liquid discharge head unit.
A third support member provided on the upstream side of the second liquid discharge head unit and on the downstream side of the second support member to support the transported object, and a third support member.
A fourth support member provided on the downstream side of the second liquid discharge head unit and supporting the object to be transported, and a fourth support member.
It is arranged between the third support member and the fourth support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The second detector and
A system for discharging a liquid, comprising: a movement control unit for moving the second liquid discharge head unit based on the detection result of the first detection unit and the detection result of the second detection unit. A first liquid discharge head unit that discharges liquid to the transported object, and
A first support member provided on the upstream side of the landing position where the liquid discharged by the first liquid discharge head unit lands on the transported object, and supports the transported object.
A second support member provided on the downstream side of the landing position and supporting the object to be transported, and a second support member.
It is arranged between the first support member and the second support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. The first detector and
A second liquid discharge head unit provided downstream of the second support member and discharging liquid to the transported object, and a second liquid discharge head unit.
A third support member provided on the upstream side of the second liquid discharge head unit and on the downstream side of the second support member to support the transported object, and a third support member.
A fourth support member provided on the downstream side of the second liquid discharge head unit and supporting the object to be transported, and a fourth support member.
It is arranged between the third support member and the fourth support member, and outputs a detection result indicating the position of the transported object in a direction orthogonal to the direction in which the transported object is transported. It is a method of discharging a liquid performed by a device for discharging a liquid provided with a second detection unit.
The device for discharging the liquid includes a movement control procedure for moving the second liquid discharge head unit based on the detection result of the first detection unit and the detection result of the second detection unit. A method of discharging a liquid.

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