JP6801479B2 - 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, 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 discharged 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 for discharging a liquid that can further improve the accuracy of the landing position of the discharged liquid in the orthogonal direction.

In order to solve the above-mentioned problems, one aspect of the present invention is to have a plurality of liquid discharge head units, and each liquid discharge head unit is different on the transfer path with respect to the object to be transported. The device that discharges the liquid at the position is an integer of the peripheral length of the transport roller from the transport roller that transports the object to be transported and the landing position where the liquid discharged by the liquid discharge head unit lands on the object to be transported. A detection unit that is installed at a double distance 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, and the detection unit based on the detection result. It is characterized by including a moving unit for moving each of the liquid discharge head units.

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 transported is conveyed.

It is the schematic which shows an example of the apparatus which discharges the liquid which concerns on one Embodiment of this invention. It is the schematic which shows the whole structure example of the apparatus which discharges the 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 a block diagram which shows the hardware configuration example which realizes the detection part 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 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 the liquid which concerns on one Embodiment of this invention. It is a block diagram which shows an example of the hardware composition for moving the liquid discharge head unit which the apparatus which discharges the liquid which concerns on one Embodiment of this invention has. It is a block diagram which shows an example of the moving mechanism for moving the liquid discharge head unit which the apparatus which discharges a 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 change of the position of a recording medium 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 the liquid which concerns on one Embodiment of this invention. It is a figure which shows the processing result example of the whole processing by the apparatus which discharges the liquid which concerns on one Embodiment of this invention. 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 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 the 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 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 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 apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is the schematic which shows the 1st modification of the hardware structure which realizes the detection part which concerns on one Embodiment of this invention. It is the schematic which shows the 2nd modification of the hardware structure which realizes the detection part which concerns on one Embodiment of this invention. It is a schematic diagram which shows the 3rd modification of the hardware structure which realizes the detection part which concerns on one Embodiment of this invention. It is the schematic which shows an example of the plurality of image pickup lenses used for the detection part which concerns on one Embodiment of this invention. It is the schematic which shows the modification of the apparatus which discharges a liquid which concerns on one Embodiment of this invention. It is a timing chart which shows the modification 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.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present specification and drawings, 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 will be described in which the device for discharging the liquid is the image forming device 110.

The object to be transported is, for example, a recording medium or the like. In the illustrated example, the image forming apparatus 110 discharges 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 “transportation direction 10”). Further, in the figure, the direction orthogonal to the transport direction 10 is an example in which the orthogonal direction 20 is set. 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. It 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 first nip roller NR1 and the nip roller installed on the downstream side of each liquid discharge head unit are 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. To 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, a 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 unit lands on the recording medium, that is, directly under the liquid ejection head unit 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 discharge 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 discharge 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 discharge 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, in the image forming apparatus 110, it is desirable that a plurality of rollers are installed for each liquid discharge head unit. Specifically, as shown in the figure, it is desirable that the plurality of rollers are installed on the upstream side and the downstream side, respectively, with each liquid discharge head unit sandwiched between them. In the illustrated example, for each liquid discharge head unit, rollers (hereinafter referred to as “first rollers”) used to convey the web 120 to each landing position are installed on the upstream side of each liquid discharge head unit. To. Further, rollers (hereinafter referred to as "second rollers") used to convey the web 120 downstream from each landing position are 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 the 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 object to be transported has an arc shape. Hereinafter, an example in which the first support member and the second support member are installed will be described. Further, the following description will be described with an example in which the first support member is the first roller and the second support member is the 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.

FIG. 3 is a diagram showing an example of the outer shape of the liquid discharge head unit according to the embodiment of the present invention. Hereinafter, 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 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 discharge head units corresponding to black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the transport direction 10 in which the recording medium is conveyed. 210K, 210C, 210M and 210Y are arranged.

For example, in the black liquid discharge head unit 210K, four heads 210K-1, 210K-2, 210K-3 and 210K-4 are arranged in a staggered manner in the orthogonal direction. 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>
For each liquid discharge head unit, a sensor for detecting the position of the recording medium in the orthogonal direction, which is an example of the detection unit, is installed. As this sensor, an optical sensor or the like that uses light such as laser, pneumatic, photoelectric, ultrasonic wave, or infrared ray is used. The optical sensor may be, for example, a CCD (Charge Coupled Device) camera, a CMOS (CMOS (Complementary Metal Oxide Semiconductor) camera, or the like. That is, the sensor constituting the detection unit is, for example, a sensor capable of detecting the edge of a recording medium. Therefore, the detection unit is realized by, for example, the following hardware configuration.

FIG. 4 is a block diagram showing an example of a hardware configuration that realizes a detection unit according to an embodiment of the present invention. For example, the detection unit is realized by hardware such as a detection device 50, a control device 52, a storage device 53, and an arithmetic unit 54 as shown in the figure.

First, the detection device 50 is, for example, the following device.

FIG. 5 is an external view showing an example of a detection device according to an embodiment of the present invention.

When detection is performed by the detection device shown in the figure, the speckle pattern formed by shining light from a light source on an object to be transported such as a web is imaged. Specifically, the detection device first has an optical system such as a semiconductor laser light source (LD) and a collimating optical system (CL). Further, the detection device has, for example, a CMOS image sensor for capturing an image in which a speckle pattern or the like is captured, and a telecentric imaging optical system (OL) for condensing and imaging the speckle pattern on the CMOS image sensor. It is a composition.

In the illustrated configuration example, the CMOS image sensor captures an image in which the speckle pattern is captured a plurality of times at each of the time T1 and the time T2, for example. Then, based on the image captured at time T1 and the image captured at time T2, an arithmetic unit such as an FPGA (Field-Programmable Gate Array) circuit performs processing such as cross-correlation calculation. Next, based on the movement of the correlation peak position calculated by the correlation calculation or the like, the detection device or the like outputs the movement amount or the like in which the transported object has moved from the time T1 to the time T2. In the illustrated example, the size of the detection device is width W × depth D × height H is 15 × 60 × 32 [mm]. The details of the correlation calculation will be described later.

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

Returning to FIG. 4, the control device 52 controls the detection device 50 and the like. Specifically, the control device 52 outputs, for example, a trigger signal to the detection device 50 to control the timing at which the CMOS image sensor releases the shutter. Further, the control device 52 controls so that a two-dimensional image can be acquired from the detection device 50. Then, the control device 52 sends the two-dimensional image imaged by the detection device 50 and generated to the storage device 53 or the like.

The storage device 53 is a so-called memory or the like. It is desirable that the two-dimensional image sent from the control device 52 or the like can be divided and stored in different storage areas.

The arithmetic unit 54 is a microcomputer or the like. That is, the arithmetic unit 54 performs an arithmetic operation for realizing various processes using the image data and the like stored in the storage device 53.

The control device 52 and the arithmetic unit 54 are, for example, a CPU (Central Processing Unit), an electronic circuit, or the like. The control device 52, the storage device 53, and the arithmetic unit 54 do not have to be different devices. For example, the control device 52 and the arithmetic unit 54 may be one CPU or the like.

<Example of function configuration of detection unit>
FIG. 6 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 imaging unit 110F1, an imaging control unit 110F2, a storage unit 110F3, a speed calculation unit 110F4, and the like.

Hereinafter, a case where imaging is performed twice by the imaging unit 110F1, that is, 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 imaged at the "A position" is moved to the "B position".

As shown in the figure, the image pickup unit 110F1 takes an image of an object to be conveyed such as a web 120 to be conveyed in the transfer direction 10. The imaging unit 110F1 is realized by, for example, a detection device 50 or the like (FIG. 4).

The image pickup control unit 110F2 includes an image acquisition unit 110F21 and a shutter control unit 110F22. The image pickup control unit 110F2 is realized by, for example, a control device 52 or the like (FIG. 4).

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, a second storage area 110F32, and an image division unit 110F33. The storage unit 110F3 is realized by, for example, a storage device 53 or the like (FIG. 4).

The image dividing unit 110F33 divides the image captured by the imaging unit 110F1 into an image indicating the "A position" and an image indicating the "B position". Next, each of the divided images is stored in the first storage area 110F31 and the second storage area 110F32.

The speed calculation unit 110F4 conveys the position of the pattern of the web 120, the moving speed at which the web 120 is conveyed, and the web 120 based on the respective images stored in the first storage area 110F31 and the second storage area 110F32. The amount of movement, etc. can be obtained. For example, the speed calculation unit 110F4 outputs data such as 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 at the timing when the time difference is Δt. Then, the speed calculation unit 110F4 may control a motor or the like that conveys the web 120 so that the moving speed is calculated. The speed calculation unit 110F4 is realized by, for example, a calculation device 54 or the like (FIG. 4).

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. A pattern is formed on the web 120 by this diffuse reflection. That is, the pattern is, for example, spots called "speckles", so-called speckle patterns. Therefore, when the web 120 is imaged, an image showing a speckle pattern can be obtained. Since the position of the speckle pattern can be known from this image, the detection unit can detect where the predetermined position of the web 120 is. It should be noted that this speckle pattern is generated because the laser beam to be irradiated interferes with the uneven shape formed on the surface or inside of the web 120.

Further, the light source is not limited to a device that uses laser light. 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 transported, the speckle pattern of the web 120 is also transported together with the web 120. 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. Further, when the movement amount obtained in this way is converted per unit time, the speed calculation unit 110F4 can obtain the movement speed at which the web 120 is conveyed.

As described above, for example, as shown in the illustrated "A position" and "B position", the web 120 is imaged a plurality of times at each position. Then, the same speckle pattern appears in each image captured. The position, movement amount, movement speed, etc. of the web are calculated using the speckle pattern shown in each image. In this way, based on the speckle pattern, the image forming apparatus can accurately obtain a detection result indicating the position of the web 120 or the like in the orthogonal direction.

The detection unit may detect the position in the transport direction and the like. That is, the detection unit may also be used to detect the respective positions in the transport direction and the orthogonal direction. When used in this way, the cost of installing a device that performs a detection device in each direction can be reduced. In addition, since the number of devices can be reduced, space can be saved.

Returning to FIG. 2, in the following description, a device such as a detection device installed on the black liquid discharge head unit 210K is referred to as a “black sensor SENK”. Similarly, a device such as a detection device installed on the cyan liquid discharge head unit 210C is referred to as a "cyan sensor SENC". Further, a device such as a detection device installed on the magenta liquid discharge head unit 210M is referred to as a "magenta sensor SENM". Furthermore, a device such as a detection device installed on the yellow liquid discharge head unit 210Y is referred to as a "yellow sensor SENY". Further, in the following description, the black sensor SENK, the cyan sensor SENC, the magenta sensor SENM, and the yellow sensor SENY may be collectively referred to as “sensors”.

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 such as the detection device at the "position where the sensor is installed", and the devices other than the sensor may be installed at other positions because they are connected by a cable or the like. The black sensor SENK, the cyan sensor SENC, the magenta sensor SENM, and the yellow sensor SENY shown in FIG. 2 show examples of positions where the sensors are installed.

As described above, it is desirable that the position where the sensor is installed is a position close to each landing position. If the sensor is installed at a position close to each landing position, the distance between each landing position and the sensor becomes short. Then, when the distance between each landing position and the 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 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, it is desirable that the position where the cyan sensor SENC is installed is INTC1 between the cyan rollers, as shown in the figure. Further, it is desirable that the magenta sensor SENM is installed at 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 sensor is installed between the rollers, the sensor can detect the position of the recording medium or the like at a position close to each landing position. In many cases, the moving speed is relatively stable between the rollers. Therefore, the image forming apparatus can accurately detect the position of the recording medium in the orthogonal direction.

Further, it is desirable that the position where the sensor is installed is a position closer to the first roller than the landing position between the rollers. That is, it is desirable that the position where the 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 between the magenta landing position PM and 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 sensors are 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 can accurately detect the position of the recording medium in the orthogonal direction.

When the sensor is installed at such a position, the 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 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 sensor is installed is located directly below 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 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. In addition, it may be restricted to set the position near each landing position or the like as the position where the sensor or the like is installed. Therefore, it is desirable that the position where the sensor is installed is closer to each first roller than each landing position.

Further, the position of the sensor may be, for example, directly below each of the liquid discharge head units. In the following description, an example in which the sensor is directly under each liquid discharge head unit will be illustrated and described. As in this example, when the sensor is directly underneath, the exact 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 the same calculation is performed even when the sensor is not directly under the liquid discharge head unit.

If the error is acceptable, the position of the sensor is directly below each liquid discharge head unit or between each first roller and each second roller, and downstream from directly below each liquid discharge head unit. It may be the position where

FIG. 7 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. 7A will be described. As shown in this example, the web 120 is conveyed by a roller or the like. When the web 120 is conveyed in this way, the position of the web 120 may change in the orthogonal direction, for example, as shown in FIG. 7 (B). That is, the web 120 may "meander" as shown in FIG. 7 (B).

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.

Fluctuations in the position of the web 120 in the orthogonal direction, or "meandering," occur, for example, due to roller eccentricity, misalignment, or cutting of the web 120 by a blade. Further, when the width of the web 120 is narrow with respect to the orthogonal direction, the thermal expansion of the rollers 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, depending on the physical characteristics of the web 120, that is, the shape after the web 120 is cut, and the like. is there.

FIG. 8 is a diagram showing an example of the cause of color shift. As described with reference to FIG. 7, when the position of the recording medium fluctuates in the orthogonal direction, that is, “meandering” occurs, color shift is likely to occur due to the causes 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 superposed 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 discharged by each liquid discharge 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. 9 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 and receives control data to and from the printer engine 72E via the control line 72LC. When various print conditions and the like indicated by the control data are input to the printer controller 72C by transmitting and receiving such control data, the printer controller 72C stores the print conditions and the like by means of a register and the like. Next, the printer controller 72C controls the printer engine 72E based on the control data, and forms an image 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 is realized by, for example, a storage device 72 Cm or the like. Further, the speed calculation unit 110F4 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 calculation devices 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. 10 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. 9).

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. 11 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. 9). 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. 9 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 of one black liquid discharge head unit.

The transport control device 72Ec (FIG. 9) is a motor, a mechanism, a driver device, and the like for transporting 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. 12 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 entire processing shown in FIG. 12 based on the image data, and forms the image indicated by the image data on the web 120.

Note that FIG. 12 shows a process for one liquid discharge head unit. That is, FIG. 12 shows, for example, the process related to the black liquid discharge head unit 210K in the example shown in FIG. Further, for the liquid discharge head units of other colors, for example, the processes shown in FIG. 12 are separately performed in parallel or before and after.

In step S01, the image forming apparatus detects the position of the recording medium in the orthogonal direction. That is, in step S01, the image forming apparatus detects the position of the web 120 in the orthogonal direction by the sensor.

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 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 detected in step S01.

FIG. 13 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. For example, the image forming apparatus includes a time shifting device 81, an arithmetic unit 82, an LPF (low pass filter) 83, and an actuator controller 84 in addition to the sensor.

The time shift device 81 stores the detection result of the sensor and stores the data indicating the position of the recording medium one cycle before. That is, the time shift device 81 is a storage device.

The arithmetic unit 82 subtracts the current position of the recording medium detected by the sensor and the position of the recording medium one cycle before the time shift device 81 stores, and calculates the fluctuation of the position of the recording medium. That is, the arithmetic unit 82 calculates the so-called meandering amount. That is, the arithmetic unit 82 is a CPU, an electronic circuit, or the like.

The LPF 83 filters the meandering amount calculated by the arithmetic unit 82. Thereby, the LPF83 reduces the abrupt change in the amount of meandering. The range of the "meandering" frequency is determined to some extent by the speed of the recording medium or the like. Therefore, the LPF 83 attenuates a high frequency value, that is, a value indicating a sudden change, from a predetermined "meandering" frequency. Sudden changes are often noise or false positives. Therefore, if the LPF83 reduces the sudden decrease in the meandering amount, the image forming apparatus can reduce the malfunction of the actuator.

The actuator controller 84 controls an actuator that moves the liquid discharge head unit. For example, the target controlled by the actuator controller 84 is the following moving mechanism.

FIG. 14 is a block diagram showing an example of a moving mechanism for moving the liquid discharge head unit included in the device for discharging the liquid according to the embodiment of the present invention. For example, the actuator controller 84 (FIG. 13) is an actuator controller CTL in the configuration shown and controls a moving mechanism as shown. Hereinafter, a configuration for moving the cyan liquid discharge head unit 210C will be described as an example.

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. Then, the actuator controller CTL 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 actuator controller CTL is, for example, a driver circuit or the like. Then, the actuator controller CTL position-controls the cyan liquid discharge head unit 210C.

The detection result in step S01 shown in FIG. 12 is input to the actuator controller CTL. Then, the actuator controller CTL moves the cyan liquid discharge head unit 210C by the actuator ACT so as to compensate for the fluctuation of the position of the web 120 indicated by the detection result (step S02 shown in FIG. 12).

In the illustrated example, the detection result shows, for example, variation Δ. Therefore, in this example, the actuator controller CTL moves the cyan liquid discharge head unit 210C in the orthogonal direction 20 so as to compensate for the fluctuation Δ.

The hardware of the controller 520 shown in FIG. 2 and the devices shown in FIGS. 13 and 14 may be integrated or separate.

FIG. 15 is a timing chart showing an example of a method of calculating the change in the position of the recording medium by the device for discharging the liquid according to the embodiment of the present invention. As shown in the figure, the image forming apparatus subtracts the position of the recording medium one cycle before and the position of the current recording medium to calculate the fluctuation of the position of the recording medium.

Hereinafter, a case where the detection cycle is “0” times will be described as an example. In this example, as shown in the figure, the image forming apparatus has "X (-1)" which is a value indicating the position of the recording medium one cycle before and "X (1)" which is a value indicating the position of the current recording medium. By subtracting "0)", the variation in the position of the recording medium is calculated by "X (0) -X (-1)".

In this example, the position of the recording medium one cycle before is detected by the sensor at the time of "-1" times, and the data is stored in the time shift device 81 (FIG. 13). Next, the image forming apparatus subtracts "X (0)" detected by the sensor and "X (-1)" indicated by the data stored in the time shifting apparatus 81 to calculate the fluctuation of the position of the recording medium. To do.

When the liquid discharge head unit is moved and the liquid is discharged to the web in this way, an image or the like is formed on the recording medium.

FIG. 16 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 conveying 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. The method for determining the position where the black ink is ejected is not limited to this method.

FIG. 17 is a diagram showing an example of processing results of the entire processing by the device for discharging the liquid according to the embodiment of the present invention. For example, as shown in FIG. 17A, it is assumed that image formation is performed in the order of black, cyan, magenta, and yellow. Further, FIG. 17 (B) is a view of FIG. 17 (A) viewed from above, a so-called plan view.

Hereinafter, an example in which the roller 230 has an eccentricity will be described. Specifically, as shown in FIG. 17C, it is assumed that there is eccentric EC. As described above, if there is an eccentric EC, a shaking OS is generated in the roller 230 when the web 120 is conveyed. Then, when the shaking OS occurs, the position POS of the web 120 fluctuates. That is, "meandering" or the like occurs depending on the shaking OS.

In order to reduce the color shift with respect to black, the image forming apparatus subtracts the position of the current recording medium detected by the sensor and the position of the recording medium one cycle before, for example, as shown in FIG. Then, the fluctuation of the position of the recording medium is calculated. Specifically, in the following description, first, the difference between the position of the web 120 detected by the black sensor SENK and the position of the web 120 under the black liquid discharge head unit 210K is defined as "Pk". Similarly, the difference between the position of the web 120 detected by the cyan sensor SENC and the position of the web 120 under the cyan liquid discharge head unit 210C is defined as "Pc". Further, the difference between the position of the web 120 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 120 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".

Subsequently, the position where the liquid lands by each liquid discharge head unit and the distance from the end of the web 120, that is, the edge of the web 120 are set for each color as "Lk3", "Lc3", "Lm3", and "Ly3". ". In such a case, since the position of the web 120 is detected by the sensor, “Pk = 0”, “Pc = 0”, “Pm = 0”, and “Py = 0”. From this relationship, the relationship as shown in the following equation (1) can be shown.

Lc3 = Lk3-Pc = Lk3
Lm3 = Lk3
Ly3 = Lk3-Py = Lk3 (1)
Therefore, from the above equation (1), “Lk3 = Lm3 = Lc3 = Ly3”. In this way, the image forming apparatus can further improve the accuracy of the landing position of the discharged liquid in the orthogonal direction by moving each liquid discharge head unit to change the position of the web 120. Further, when the image is formed, the liquids of each color land with high accuracy, so that the color shift can be reduced and the image quality of the formed image can be improved.

The position where the sensor is installed is the position where the circumference d of the transport roller is multiplied by an integer from the landing position. Hereinafter, the position where the sensor is installed will be described by taking the black sensor SENK as an example. For example, if the black sensor SENK is set to "d × 0", it is installed at a position close to the landing position. Further, if it is set to "d × 1", the black sensor SENK is installed at a distance obtained by multiplying the circumference d of the transport roller by 1 from the landing position (hereinafter referred to as "first distance d1"). As shown in the figure, in the case of "d × 1", the black sensor SENK is installed at a position one distance d1 away from the landing position.

Similarly, assuming that "d × 2", the black sensor SENK is installed at a distance (hereinafter referred to as "second distance d2") obtained by doubling the peripheral length d of the transport roller from the landing position. As shown in the figure, in the case of "d × 2", the black sensor SENK is installed at a position separated from the landing position by a second distance d2. The integer multiple may be 3 times or more.

In addition, the sensor mounting error, the landing position error, or both of them may be further added to the distances such as the first distance d1 and the second distance d2. In addition, sensors may be installed for other colors in the same manner.

FIG. 18 is a diagram showing an example of a position where a 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 black first roller CR1K 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.

As described above, when the position where the 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 liquids 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 each liquid discharge head unit must be an integral multiple of the peripheral length d (FIG. 17) of the roller, 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 d of the rollers.

<Comparison example>
FIG. 19 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 of "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 discharge head unit to compensate for the position fluctuation of the recording medium.

FIG. 20 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 units are installed so that the distance between the liquid discharge head units is an integral multiple of the peripheral length d of the rollers. 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. 21 is a diagram showing a processing result example 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 times the peripheral length d of the rollers, respectively.

In this second comparative example, as in FIG. 17, 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 with respect to the web of each color ink 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. 22 is a diagram showing an example of a position where a sensor is installed in the device for discharging the liquid according to the 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.

<Example of correlation calculation>
FIG. 23 is a configuration 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, the amount of movement, the movement speed, or a combination thereof at the position of the sensor 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. It is configured to have a conversion result storage unit MEM.

The first two-dimensional Fourier transform unit FT1 transforms 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 correlation image data generation unit DMK receives 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) having 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 brightness 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. When the sub-pixel processing is performed in this way, the peak position can be searched with high accuracy. Therefore, the detection unit can accurately output the position, the moving amount, the moving speed, and the like.

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

FIG. 24 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 correlated 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. 23) 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. In this way, 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 subpixel 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.

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

FIG. 25 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. 23).

Returning to FIG. 23, the calculation unit CAL calculates the relative position, movement amount, movement speed, and the like 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 correlated image data and the peak position searched by the peak position search unit SR.

Further, the calculation unit CAL can calculate the movement speed by dividing the movement amount by the time, for example.

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 moving amount, a moving 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 brightness is equal to or less than a preset threshold, and sets "1" if the brightness 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.

In addition, the detection unit may detect a relative position, a moving amount, a moving 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.

<Function configuration example>
FIG. 26 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 detection unit 110F10 for each liquid discharge head unit. Further, the image forming apparatus 110 includes a moving unit 110F20.

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, there are four detection units 110F10 as shown in the figure. Further, the detection unit 110F10 detects the position of the recording medium in the orthogonal direction of the web 120. The detection unit 110F10 is realized by, for example, the hardware configuration shown in FIG. 4 or the like.

It is desirable that the embodiment includes a first roller and a second roller as shown in the figure. In a preferred embodiment, a first roller is provided for each liquid discharge head unit, as shown. Specifically, in the example shown in FIG. 2, the number of the first rollers is four, which is the same number as the liquid discharge head units. 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 on 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.

In a preferred embodiment, similarly, a second roller is provided for each liquid discharge head unit, as shown. Specifically, in the example shown in FIG. 2, the number of the second rollers is four, which is the same number as the liquid discharge head unit. 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 moving unit 110F20 moves the liquid discharge head unit based on the detection result by the detection unit 110F10. The moving unit 110F20 is realized by, for example, the hardware configuration shown in FIG.

Further, the image forming apparatus 110 includes a transport roller. For example, the transfer roller is a roller 230 or the like as shown in the figure. As shown in the figure, the transport roller is a roller that transports the recording medium in the transport direction.

As shown in the figure, for example, the black detection unit 110F10 sets an integer of the circumference d of the transport roller (hereinafter, the integer is "N = 0, 1, 2, 3 ..." From the black landing position PK. .) Installed at twice the distance. That is, the black detection unit 110F10 detects at a position "perimeter d × N" away from the black landing position PK.

The detection unit 110F10 may be installed downstream from each landing position as long as it is located at a position "perimeter d × N" away from each landing position.

For example, color shift may easily occur because the distance between the print heads is a non-integer multiple of the circumference d. On the other hand, if there is no constraint that the distance between the printheads is a non-integer multiple, that is, the distance between the printheads is an integral multiple, the design for installing the printheads has more freedom and design. Can be easily done. Then, as in the embodiment of the present invention, when the position where the sensor is installed is an integral multiple of the circumference d, such a deviation can be corrected, and the accuracy of the landing position of the discharged liquid can be corrected. Can be improved. Therefore, the image forming apparatus 110 can correct the color shift.

In this way, when the moving unit 110F20 moves each liquid discharge head unit based on the detection result by each detection unit 110F10, the image forming apparatus 110 determines the accuracy of the landing position of the discharged liquid in the orthogonal direction. Can be improved further.

Further, preferably, the position where the detection unit 110F10 detects, that is, the position where the sensor is installed, is preferably a position close to the landing position such as the black landing position PK such as INTK1 between the black rollers. 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 110F10 detects, that is, the position where the sensor is installed, is the position on the upstream side of the landing position among the rollers, such as the black upstream section INTK2 and the like. good. 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.

Further, as shown in the figure, the image forming apparatus 110 is preferably configured to include the measuring unit 110F30.

As shown in the figure, when the measurement unit 110F30 is provided, the image forming apparatus 110 can more reliably detect the position of the recording medium and the like. For example, it is assumed that a measuring device such as an encoder is installed on the rotating shaft of the roller 230 or the like. Then, the measuring unit 110F30 measures the moving amount of the recording medium by an encoder or the like. In this way, when the measurement result measured by the measurement unit 110F30 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.

<Summary>
The device that discharges the liquid according to the embodiment of the present invention detects the position of the object to be transported such as a recording medium in the orthogonal direction at a position close to the liquid discharge head unit for each liquid discharge head unit. Next, the device for discharging the liquid according to the embodiment of the present invention moves the liquid discharge head unit based on the detection result. 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. 20 and 21. The device can accurately compensate for the deviation generated at the landing position of the liquid in the orthogonal direction.

Further, the position where the sensor included in the device for discharging the liquid according to the embodiment of the present invention is installed is a position that is an integral multiple of the peripheral length d. Therefore, the device that discharges the liquid according to the embodiment of the present invention can correct the deviation.

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 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, when the liquid is discharged to form an image on the recording medium, the device for discharging 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.

<Modification example>
The detection device 50 shown in FIG. 4 may be realized by the following hardware, for example.

FIG. 27 is a schematic view showing a first modification of a hardware configuration that realizes a detection unit according to an embodiment of the present invention. In the following description, the same devices as those described above will be designated by the same reference numerals, and the description thereof will be omitted.

Compared with the hardware configuration described above, the detection device is different in that it has a plurality of optical systems. That is, the hardware configuration described above is a so-called "monocular", whereas the hardware configuration of the first modification is a "compound eye".

The web 120, which is an example of the detection target, is irradiated with laser light or the like from the first light source 51A and the second light source 51B, respectively. The position where the first light source 51A irradiates the light is defined as the "A position", and similarly, the position where the second light source 51B irradiates the light is defined as the "B position".

The first light source 51A and the second light source 51B have a light emitting element that emits laser light and a collimated lens that makes the laser light emitted from the light emitting element substantially parallel light. Further, the first light source 51A and the second light source 51B are installed at positions where the laser beam is irradiated from an oblique direction with respect to the surface of the web 120.

The detection device 50 has an area sensor 11, a first image pickup lens 12A at a position facing the "A position", and a second image pickup lens 12B at a position facing the "B position".

The area sensor 11 is, for example, a sensor having a configuration in which an image pickup device 112 is formed on a silicon substrate 111. It is assumed that the image sensor 112 has an "A region 11A" and a "B region 11B" that can acquire a two-dimensional image, respectively. The area sensor 11 is, for example, a CCD sensor, a CMOS sensor, a photodiode array, or the like. Then, the area sensor 11 is housed in the housing 13. Further, the first imaging lens 12A and the second imaging lens 12B are held by the first lens barrel 13A and the second lens barrel 13B, respectively.

In this example, as shown, the optical axis of the first imaging lens 12A coincides with the center of the "A region 11A". Similarly, the optical axis of the second imaging lens 12B coincides with the center of the "B region 11B". Then, the first imaging lens 12A and the second imaging lens 12B form an image of light in the "A region 11A" and the "B region 11B", respectively, to generate a two-dimensional image.

In addition, the detection device 50 may have a configuration or the like described below.

FIG. 28 is a schematic view showing a second modification of the hardware configuration that realizes the detection unit according to the embodiment of the present invention. Hereinafter, the points different from FIG. 27, that is, the hardware configuration of the detection device 50 will be extracted and illustrated. Compared with the configuration shown in FIG. 27, the configuration of the detection device 50 is different in that the first imaging lens 12A and the second imaging lens 12B are integrated into the lens 12C. On the other hand, the area sensor 11 and the like have the same configuration as shown in FIG. 27, for example.

Further, in this example, it is desirable that the aperture 121 or the like is used so that the images of the first imaging lens 12A and the second imaging lens 12B do not interfere with each other to form an image. As described above, when the aperture 121 or the like is used, the regions for forming the images of the first imaging lens 12A and the second imaging lens 12B can be limited respectively. Therefore, it is possible to reduce the interference between the respective images, and the detection device 50 can generate images at the respective positions at the “A position” and the “B position”.

FIG. 29 is a schematic view showing a third modification of the hardware configuration that realizes the detection unit according to the embodiment of the present invention. Compared with the configuration shown in FIG. 28, the configuration of the detection device 50 shown in FIG. 29A is different in that the area sensor 11 is the second area sensor 11'. On the other hand, the configurations of the first imaging lens 12A, the second imaging lens 12B, and the like are the same as those in FIG. 28, for example.

The second area sensor 11'has, for example, the configuration shown in FIG. 29 (B). Specifically, as shown in FIG. 29 (B), a plurality of image pickup devices b are formed on the wafer a. Next, the image sensor as shown in FIG. 29 (B) is cut out from the wafer a. The first image sensor 112A and the second image sensor 112B, which are the plurality of image pickup elements to be cut out, are formed on the silicon substrate 111, respectively. On the other hand, the positions of the first image pickup lens 12A and the second image pickup lens 12B are determined according to the distance between the first image pickup element 112A and the second image pickup element 112B.

The image pickup device is often manufactured for imaging. Therefore, the ratio of the image sensor in the X direction and the Y direction, that is, the aspect ratio is often a ratio that matches the image format, such as square, "4: 3" or "16: 9". In the present embodiment, images are taken at two or more points separated by a certain interval. Specifically, an image is taken at each point separated by a certain interval in the X direction, which is one direction in two dimensions, that is, in the transport direction 10 (FIG. 2). On the other hand, the image sensor has an aspect ratio that matches the image format. Therefore, when imaging two points separated by a certain interval in the X direction, the image sensor in the Y direction may not be used. Further, when the pixel density is increased, the cost may be increased because the image sensor having a high pixel density is used in either the X direction or the Y direction.

Therefore, with the configuration shown in FIG. 29, the first image sensor 112A and the second image sensor 112B that are separated from each other at regular intervals can be formed on the silicon substrate 111. Therefore, the number of image sensors in which the image sensor in the Y direction is not used can be reduced. Therefore, the waste of the image sensor can be reduced. Further, since the first image sensor 112A and the second image sensor 112B are formed by a semiconductor process with high accuracy, the distance between the first image sensor 112A and the second image sensor 112B can be made accurate.

FIG. 30 is a schematic view showing an example of a plurality of imaging lenses used in the detection unit according to the embodiment of the present invention. A lens array as shown may be used to implement the detector.

The illustrated lens array has a configuration in which two or more lenses are integrated. Specifically, the illustrated lens array is an example in which there are 3 rows and 3 columns in the vertical and horizontal directions, and a total of nine imaging lenses A1 to C3 are provided. When such a lens array is used, an image showing nine points can be captured. In this case, an area sensor having nine imaging regions is used.

In this way, for example, the operations on the two imaging regions are likely to be executed simultaneously, that is, executed in parallel. Next, when each calculation result is averaged or error elimination is performed, the detection device can calculate accurately and improve the stability of the calculation as compared with the case where one calculation result is used. can do. In addition, the calculation may be executed based on the application software whose speed fluctuates. Even in this case, since the area where the correlation calculation can be performed is expanded, it becomes easy to obtain a highly accurate speed calculation result.

FIG. 31 is a schematic view showing a modified example of the device for discharging the liquid according to the embodiment of the present invention. Compared with FIG. 2, in the illustrated configuration, the arrangement of the first support member and the second support member is different. As shown, 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.

FIG. 32 is a timing chart showing a modified example of the method of calculating the fluctuation amount of the transported object by the device for discharging the liquid according to the embodiment of the present invention. The amount of fluctuation may be calculated by a method as shown in the figure. As shown in the figure, the image forming apparatus calculates the amount of fluctuation based on a plurality of detection results. Specifically, based on the first detection result S1 and the second detection result S2, the control device CTRL outputs a calculation result indicating the amount of fluctuation. First, the first detection result S1 and the second detection result S2 are detection results indicated by sensor data output from any two of the plurality of sensors.

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 amount of fluctuation 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".

Let the illustrated calculation result, that is, the amount of fluctuation be "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 amount of fluctuation 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 actuator so as to compensate for the fluctuation amount “ΔX”, and moves the cyan liquid discharge head unit 210C (FIG. 14) in the orthogonal direction. In this way, even if the position of the object to be transported fluctuates, the image forming apparatus can accurately form an image on the object to be transported. 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, in this way, the accumulation of detection errors by each sensor can be reduced.

The amount of fluctuation may be calculated in the same manner in other liquid discharge head units. For example, the amount of fluctuation for the cyan liquid discharge head unit 210C (FIG. 2) depends on the first detection result S1 by the black sensor SENK (FIG. 2) and the second detection result S2 by the cyan sensor SENC (FIG. 2). Calculated. 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 amount of fluctuation 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, a sensor for black may be further provided, and the fluctuation amount for the black liquid discharge head unit 210K (FIG. 2) may be calculated from the second detection result S2 by the black sensor SENK (FIG. 2).

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 moving liquid discharge head unit. 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 the detection result by the sensor installed at the position closest to the liquid discharge head unit to be moved.

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

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

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, and have both of them. It may be realized by a system that discharges a liquid.

Further, in the device for ejecting a liquid and the system for ejecting a liquid according to the present invention, the liquid is not limited to ink, and 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.

Further, the object to be transported is not limited to a recording medium such as paper. The transported object may be made of a material to which a liquid can adhere. For example, the material to which the liquid can adhere may be any material such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, or a combination thereof, which 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 a method of discharging a 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 SENY Yellow Sensor 520 Controller

Japanese Unexamined Patent Publication No. 2015-13476

Claims (14)

A device having a plurality of liquid discharge head units, each of which discharges liquid to a transported object at a different position on the transport path.
A transport roller that transports the object to be transported and
The liquid discharged by the liquid discharge head unit is installed at a position that is an integral multiple of the peripheral length of the transport roller from the landing position where the liquid is landed on the object to be transported, and is in the direction in which the object to be transported is transported. On the other hand, a detection unit that outputs a detection result indicating the position of the object to be transported in the orthogonal direction,
A device for discharging a liquid, which comprises a moving unit for moving each of the liquid discharge head units based on the detection result. A first support member provided for the liquid discharge head unit, provided on the upstream side of the landing position, and supporting the object to be transported, and
A second support member provided for the liquid discharge head unit, provided on the downstream side of the landing position, and supporting the object to be transported is further provided.
The device for discharging the liquid according to claim 1, wherein the position of the detection unit is between the first support member and the second support member. The device for discharging a liquid according to claim 2, wherein the position of the detection unit is a position between the landing position and the first support member. The device for discharging the liquid according to any one of claims 1 to 3, wherein the moving unit moves the liquid discharge head unit in a direction orthogonal to the direction in which the object to be transported is conveyed. .. The device for discharging a liquid according to any one of claims 1 to 4, wherein the detection unit uses an optical sensor. The device for discharging the liquid according to claim 5, wherein the detection unit obtains the detection result based on the pattern of the object to be transported. Each of the detection units detects the position of the object to be transported for each liquid discharge head unit based on the result of detecting the pattern of the object to be transported at two or more different timings. Item 6. The device for discharging the liquid according to item 6. 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 or 7, wherein the detection unit obtains the detection result based on an image obtained by capturing the pattern. A measuring unit for measuring the amount of movement in the transport direction in which the object to be transported is transported is further provided.
The device for discharging a liquid according to any one of claims 1 to 8, 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 9, wherein the transported object is a sheet that is long and continuous along the transport direction. The device for discharging a liquid according to any one of claims 1 to 10, wherein an image is formed on the object to be transported when the liquid is discharged. The device for discharging a liquid according to any one of claims 1 to 11, wherein the distance between the liquid discharge head units is a non-integer multiple of the peripheral length of the transport roller. A system that has a plurality of liquid discharge head units, and each liquid discharge head unit discharges liquid to a transported object at different positions on the transport path.
A transport roller that transports the object to be transported and
The liquid discharged by the liquid discharge head unit is installed at an integral multiple of the circumference of the transport roller from the landing position where the liquid is landed on the object to be transported, and is orthogonal to the direction in which the object to be transported is transported. A detection unit that outputs a detection result indicating the position of the object to be transported in the direction,
A system for discharging a liquid, which comprises a moving unit for moving each of the liquid discharge head units based on the detection result. A liquid operated by a device having a plurality of liquid discharge head units and a transport roller for transporting an object to be transported, and each liquid discharge head unit discharges liquid to the object to be transported at different positions on the transfer path. Is a method of discharging
The device for discharging the liquid conveys the object to be transported at a position separated by an integral multiple of the peripheral length of the transport roller from the landing position where the liquid discharged by the liquid discharge head unit lands on the object to be transported. A detection procedure that outputs a detection result indicating the position of the object to be transported in a direction orthogonal to the direction of the object.
A method in which a device for discharging a liquid discharges a liquid including a moving procedure for moving each of the liquid discharge head units based on the detection result.

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