JP6705282B2 - Device for ejecting liquid - Google Patents

Description

The present invention relates to a device for ejecting a liquid .

Conventionally, there is known a method of forming an image by a so-called inkjet method, in which ink is discharged from a print head. There is known a method of improving print quality of an image printed on a print medium by forming the image.

For example, a method of adjusting the position of the print head to improve print quality is known. Specifically, first, a sensor detects a lateral position variation of a web, which is a print medium passing through the continuous paper printing system. There is known 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 (see, for example, Japanese Patent Laid-Open No. 2004-242242).

However, in order to further improve the image quality of an image formed, for example, the direction in which an object is conveyed (hereinafter referred to as “conveyance direction”) or a direction orthogonal to the conveyance direction (hereinafter simply referred to as “orthogonal direction”). In order to improve the accuracy of the landing position of the ejected liquid, it may be required to detect the position of the transported object with high accuracy. On the other hand, in the conventional technique, there is a problem that the position or the like of the transported object may not be accurately detected in the transportation direction or the orthogonal direction.

It is an object of one aspect of the present invention to provide a transported object detection device that accurately detects the position of the transported object in the transport direction or the orthogonal direction.

In order to solve the above-described problems, an apparatus for ejecting a liquid, which is one embodiment of the present invention, includes an optical sensor having a plurality of optical elements that receive light reflected by a transported object, and the transported object. Among the optical elements, a setting unit that sets outputs of at least two of the optical elements based on a speed at which the object is conveyed, and a conveyance direction in which the object to be conveyed is conveyed using the output, or the setting unit. A transported object detection device including a detection unit that outputs a detection result indicating the position or speed of the transported object in at least one of the directions orthogonal to the transport direction ; and a plurality of liquid ejection head units, A device for ejecting a liquid to each of the liquid-ejecting head units at different positions on the conveyance path with respect to an object to be conveyed, and a control unit for ejecting the liquid to the liquid-ejecting head unit based on the detection result. The detection unit is provided in each of the liquid ejection head units, is provided upstream of a position at which the liquid ejected by the liquid ejection head unit lands on the transported object, The first roller used for conveyance and the liquid ejection head unit are provided respectively, and are provided on the downstream side of a position where the liquid ejected by the liquid ejection head unit lands on the conveyed object. It is characterized in that it is installed between the second roller used for transporting the sheet .

The position or the like of the transported object can be accurately detected in the transport direction or the orthogonal direction.

It is a schematic diagram showing an example of a device which discharges a liquid concerning one embodiment of the present invention. It is a schematic diagram showing an example of whole composition of a device which discharges a liquid concerning one embodiment of the present 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 schematic diagram showing an example of hardware constitutions of a detection part concerning one embodiment of the present invention. It is a schematic diagram showing an example of the 2nd hardware composition of the detecting device used for the detecting part concerning one embodiment of the present invention. It is a schematic diagram showing an example of the 3rd hardware constitutions of the detecting device used for the detecting part concerning one embodiment of the present invention. It is a schematic diagram showing an example of a plurality of imaging lenses used for a primary detecting element concerning one embodiment of the present invention. It is a functional block diagram which shows an example of a functional structure of the detection part which concerns on one Embodiment of this invention. It is an external view showing an example of an apparatus which realizes a primary detecting element concerning one embodiment of the present invention. It is a figure which shows the example which the position of a recording medium changes in an orthogonal direction. It is a figure which shows an example of the cause which a color shift arises. It is a block diagram which shows an example of the hardware constitutions of the control part which concerns on one Embodiment of this invention. It is a block diagram showing an example of hardware constitutions of a data management device which a control part concerning one embodiment of the present invention has. It is a block diagram which shows an example of the hardware constitutions of the image output device which the control part which concerns on one Embodiment of this invention has. 6 is a flowchart showing an example of overall processing by a device for ejecting a liquid according to an embodiment of the present invention. It is a figure which shows an example of the binning process which concerns on one Embodiment of this invention. It is a figure which shows an example of the test pattern which the apparatus which discharges the liquid which concerns on one Embodiment of this invention uses. It is a figure which shows the process result example of the whole process 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 the liquid which concerns on one Embodiment of this invention. It is a figure which shows an example of the hardware constitutions in a 1st comparative example. It is a figure which shows the process result example of the whole process by the apparatus which discharges the liquid which concerns on a 1st comparative example. It is a figure which shows the process result example of the whole process by the apparatus which discharges the liquid which concerns on a 2nd comparative example. It is a figure which shows an example of the position where the sensor in the apparatus which discharges the liquid which concerns on a comparative example is installed. It is a functional block diagram showing an example of functional composition of a device which discharges a liquid concerning one embodiment of the present invention.

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

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

The transported object is, for example, a recording medium or the like. In the illustrated example, the image forming apparatus 110 forms an image by ejecting a liquid onto a web 120, which is an example of a recording medium conveyed by rollers 130 and the like. The web 120 is a so-called continuous paper printing medium or the like. That is, the web 120 is a roll-shaped paper 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 (hereinafter referred to as “conveyance direction 10”). Further, in the drawing, a direction orthogonal to the transport direction 10 is an example of an orthogonal direction 20. Further, in this example, the image forming apparatus 110 ejects ink of four colors of black (K), cyan (C), magenta (M), and yellow (Y) to form an image on a predetermined portion of the web 120. It is an inkjet printer for forming a.

FIG. 2 is a schematic diagram showing an example of the overall configuration of an apparatus for ejecting 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 in order to eject each of the four colors of ink.

Each liquid ejection head unit ejects each liquid of each color onto the web 120 conveyed in the conveyance direction 10. In addition, the web 120 is assumed to be conveyed by two nip rollers and a roller 230. Hereinafter, of these two nip rollers, the nip roller installed on the upstream side of each liquid ejection head unit is referred to as a “first nip roller NR1”. On the other hand, a nip roller installed downstream of the first nip roller NR1 and each liquid ejection head unit is referred to as a "second nip roller NR2". As shown in the drawing, each nip roller rotates while sandwiching an object to be conveyed such as the web 120. As described above, the nip rollers and the rollers 230 are actuators or mechanisms that convey the web 120 or the like in a predetermined direction.

In addition, the recording medium of the web 120 is preferably long. Specifically, the length of the recording medium is preferably longer than the distance between the first nip roller NR1 and the second nip roller NR2. Further, the recording medium is not limited to the web. That is, the recording medium may be paper that is folded and stored, so-called “Z paper” or the like.

Hereinafter, in the illustrated overall configuration example, each liquid ejection 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 ejection head unit (hereinafter referred to as “black liquid ejection head unit 210K”) installed on the most upstream side is for black (K). A liquid ejection head unit (hereinafter referred to as “cyan liquid ejection head unit 210C”) installed next to the black liquid ejection head unit 210K is for cyan (C). Further, a liquid ejection head unit (hereinafter referred to as “magenta liquid ejection head 210M”) installed next to the cyan liquid ejection head unit 210C is for magenta (M). Then, the liquid ejection head unit (hereinafter referred to as “yellow liquid ejection head unit 210Y”) installed on the most downstream side is for yellow (Y).

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

In addition, a plurality of rollers are installed for each liquid ejection head unit. As shown in the figure, the plurality of rollers are respectively installed on the upstream side and the downstream side with the liquid ejection head units sandwiched therebetween. In the illustrated example, a roller (hereinafter, referred to as “first roller”) used to convey the web 120 to each ejection position is installed upstream of each liquid ejection head unit for each liquid ejection head unit. It Further, rollers (hereinafter, referred to as “second rollers”) used to convey the web 120 downstream from the respective ejection positions are installed on the downstream sides of the respective liquid ejection head units. In this way, when the first roller and the second roller are respectively installed, so-called “fluttering” can be reduced at each ejection 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 driving rollers.

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

An example of the outer shape of the liquid ejection head unit will be described with reference to FIG. Here, FIG. 3A is a schematic plan view showing an example of the four liquid ejection 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 ejection head unit is a full line type head unit in this embodiment. That is, the image forming apparatus 110 includes four liquid ejection head units 210K and 210C corresponding to black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side in the recording medium conveyance direction 10. 210M and 210Y are arranged.

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

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

<Example of detector>
A sensor that detects the position of the recording medium in the transport direction or the orthogonal direction, which is an example of a detection unit, is installed for each liquid ejection head unit. As this sensor, an optical sensor using light such as laser, air pressure, photoelectric, ultrasonic wave or infrared ray is used. The optical sensor may be, for example, a CCD (Charge Coupled Device) camera or the like. That is, the sensor that constitutes the detection unit is, for example, a sensor that can detect the edge of the recording medium. Further, the sensor may have a configuration described below, for example.

As shown in FIG. 2, the setting device 521 is connected to the sensor. The setting device 521 outputs each pixel value from a plurality of optical elements included in the sensor based on the result calculated by each sensor or the controller 520. Then, the setting device 521 sets the outputs to be combined. The setting device 521 may set the aperture value, the exposure time, or the like. Details of the setting will be described later.

FIG. 4 is a schematic diagram showing an example of the hardware configuration of the detection unit according to the embodiment of the present invention. For example, the sensor is realized by the detection device 50, the first light source 51A, the second light source 51B, the control device 52, the storage device 53, the calculation device 54, the setting device 521, and the like as illustrated.

The web 120, which is an example of a detection target, is irradiated with laser light and the like from the first light source 51A and the second light source 51B, respectively. The position where the first light source 51A emits light is referred to as “A position”, and similarly, the position where the second light source 51B emits light is referred to as “B position”.

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

The detection device 50 has an area sensor 11, a first imaging lens 12A at a position facing the “A position”, and a second imaging lens 12B at a position facing the “B position”.

The area sensor 11 is, for example, a sensor in which an optical element 112 is formed on a silicon substrate 111. In addition, it is assumed that there are an “A area 11A” and a “B area 11B” on the optical element 112, each of which can acquire a two-dimensional image. The area sensor 11 is, for example, a CCD sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, a photodiode array, or the like. 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 illustrated, the optical axis of the first imaging lens 12A coincides with the center of the “A area 11A”. Similarly, the optical axis of the second imaging lens 12B coincides with the center of the “B area 11B”. Then, the first image pickup lens 12A and the second image pickup lens 12B respectively form light in the “A area 11A” and the “B area 11B” to generate a two-dimensional image.

The detection device 50 is not limited to the configuration shown in FIG. For example, the detection device 50 may have the configuration described below.

FIG. 5 is a schematic diagram showing an example of the second hardware configuration of the detection device used in the detection unit according to the embodiment of the present invention. Compared with the configuration shown in FIG. 4, the configuration of the detection device 50 shown in FIG. 5 is different in that the first imaging lens 12A and the second imaging lens 12B are integrated and become a lens 12C. On the other hand, the area sensor 11 and the like have, for example, the same configuration as that shown in FIG.

Further, in this example, it is desirable to use the aperture 121 or the like so that the respective images of the first imaging lens 12A and the second imaging lens 12B interfere with each other and are not formed. As described above, when the aperture 121 or the like is used, the regions where the respective images of the first imaging lens 12A and the second imaging lens 12B are formed can be limited. 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” shown in FIG. 4.

FIG. 6 is a schematic diagram showing an example of a third hardware configuration of the detection device used in the detection unit according to the embodiment of the present invention. Compared with the configuration shown in FIG. 5, the configuration of the detection device 50 shown in FIG. 6A is different in that the area sensor 11 is a 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 in FIG. 5, for example.

The second area sensor 11′ has, for example, the configuration shown in FIG. Specifically, as shown in FIG. 6B, a plurality of optical elements b are formed on the wafer a. Next, the optical elements as shown in FIG. 6B are cut out from the wafer a. The first optical element 112A and the second optical element 112B, which are the plurality of optical elements cut out, are formed on the silicon substrate 111, respectively. On the other hand, the positions of the first imaging lens 12A and the second imaging lens 12B are determined in accordance with the distance between the first optical element 112A and the second optical element 112B.

Optical elements are often manufactured for imaging. Therefore, the ratio between the X direction and the Y direction of the optical element, that is, the aspect ratio is often a ratio matching the image format, such as square, “4:3”, or “16:9”. In the present embodiment, images at two or more points separated by a constant interval are captured. Specifically, an image is captured in each of the X-directions, which are one direction in two dimensions, that is, at points separated by a constant distance in the transport direction 10 (FIG. 4 ). In contrast, the optical element has an aspect ratio that matches the image format. Therefore, in the case of capturing images at two points separated by a constant distance in the X direction, the optical element in the Y direction may not be used. In addition, when the pixel density is increased, an optical element having a high pixel density is used in either the X direction or the Y direction, which may increase the cost.

Therefore, with the configuration shown in FIG. 6, the first optical element 112A and the second optical element 112B can be formed on the silicon substrate 111 at regular intervals. Therefore, it is possible to reduce the number of optical elements in which the optical elements in the Y direction are not used. Therefore, the waste of the optical element can be reduced. In addition, since the first optical element 112A and the second optical element 112B are formed by a highly accurate semiconductor process, the distance between the first optical element 112A and the second optical element 112B can be accurately set.

FIG. 7 is a schematic diagram 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 has a total of nine imaging lenses A1 to C3 arranged in three rows and three columns in the vertical and horizontal directions, for example. When such a lens array is used, an image showing 9 points can be captured. In this case, an area sensor having 9 imaging areas is used.

By doing so, for example, the operations for the two imaging regions are likely to be executed simultaneously, that is, in parallel. Next, when the respective calculation results are averaged or error removal is performed, the detection device calculates with high accuracy or improves the stability of calculation, as compared with the case where one calculation result is used. can do. In addition, the calculation may be executed based on application software whose speed changes. Even in this case, since the area in which the correlation calculation can be performed is expanded, it is easy to obtain a highly accurate speed calculation result.

Returning to FIG. 4, the control device 52 controls the detection device 50 and the like. For example, the control device 52 controls the shutter timing of the area sensor 11 and adjusts the diaphragm by outputting a signal to the detection device 50. Further, the control device 52 controls so that a two-dimensional image can be acquired from the detection device 50. Next, the control device 52 sends the acquired two-dimensional image to the storage device 53.

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 be divided and stored in different storage areas.

The arithmetic device 54 and the setting device 521 are a microcomputer or the like. That is, the arithmetic unit 54 performs arithmetic operations for implementing various processes using image data stored in the storage unit 53.

The control device 52 is, for example, a CPU (Central Processing Unit), an electronic circuit, or the like. The control device 52, the storage device 53, the arithmetic device 54, and the setting device 521 do not have to be different devices. For example, the control device 52, the arithmetic device 54, and the setting device 521 may be one CPU or the like.

An example in which there are two optical systems shown in FIG. 4 will be described below. In the embodiment according to the present invention, the number of optical systems may be three or more or one.

Moreover, as shown in FIG. 4, actuators ACA and ACB for changing the diaphragm, the optical zoom magnification, or a combination thereof may be installed in the optical system such as the first imaging lens 12A and the second imaging lens 12B, respectively. .. For example, when the optical zoom magnification is changed, the position of each of the first image pickup lens 12A and the second image pickup lens 12B is changed by the zoom mechanism based on the set optical zoom magnification to become the optical zoom magnification. To be controlled.

When each optical system has a diaphragm such as an electric iris diaphragm, the diaphragm is controlled by actuators ACA and ACB based on the diaphragm value. Then, when the diaphragm is controlled, the amount of received light is adjusted.

Alternatively, the exposure speed may be adjusted by controlling the shutter speed and the like. Further, the control may be performed by the control device 52, and the setting device 521 or the like may set the optical zoom magnification, the aperture value, the exposure time, or a combination thereof.

FIG. 8 is a functional block diagram showing an example of the functional configuration of the detection unit according to the embodiment of the present invention. Hereinafter, as illustrated, a combination of the black liquid ejection head unit 210K and the cyan liquid ejection head unit 210C among the detection units installed for each head unit will be described as an example. Further, as shown in the figure, the detection unit 52A for the black liquid ejection head unit 210K outputs the detection result relating to the "A position", and the detection unit 52B for the cyan liquid ejection head unit 210C detects the "B position". An example of outputting the result will be described. First, the detection unit 52A for the black liquid ejection head unit 210K includes, for example, the image pickup unit 16A, the image pickup control unit 14A, the image storage unit 15A, and the like. In this example, the detection unit 52B for the cyan liquid ejection head unit 210C has, for example, the same configuration as the detection unit 52A, and includes the image pickup unit 16B, the image pickup control unit 14B, the image storage unit 15B, and the like. Hereinafter, the detection unit 52A will be described as an example.

The image capturing unit 16A captures an image of the web 120 transported in the transport direction 10 as illustrated. The imaging unit 16A is realized by, for example, the detection device 50 or the like (FIG. 4 or the like).

The image capturing control unit 14A includes an image capturing unit 142A and a binning control unit 143A. The imaging control unit 14A is realized by, for example, the control device 52 or the like (FIG. 4). Further, the imaging control unit 14A may further include a shutter control unit 141A and the like as illustrated. In addition, the imaging control unit 14A may further include an aperture control unit and an optical zoom control unit. The configuration shown in the figure will be described below as an example.

The image capturing unit 142A acquires an image captured by the image capturing unit 16A.

The shutter control unit 141A controls the timing at which the image capturing unit 16A captures an image.

The image storage unit 15A stores the image captured by the imaging control unit 14A. The image storage unit 15A is realized by, for example, the storage device 53 or the like (FIG. 4).

The calculation unit 53F obtains the position of the pattern of the web 120, the transport speed at which the web 120 is transported, the transport amount at which the web 120 is transported, and the like, based on the images stored in the image storage units 15A and 15B. be able to. Further, the calculation unit 53F outputs the data of the time difference Δt indicating the shutter timing to the shutter control units 141A and 141B. That is, the calculation unit 53F indicates the shutter timing to the shutter control units 141A and 141B so that the image indicating the “A position” and the image indicating the “B position” are imaged with the time difference Δt. Further, the calculation unit 53F may control a motor or the like that conveys the web 120 so that the calculated conveyance speed is obtained. The calculation unit 53F is realized by, for example, the arithmetic device 54 or the like (FIG. 4).

Further, the binning control unit 143A controls the imaging unit 16A to perform the binning process or controls to cancel the binning process. Specifically, when the transport speed is high, the binning control unit 143A causes the image pickup unit 16A to add the respective charges indicated by the plurality of pixels to combine the respective outputs of the respective optical elements. The details of the binning process will be described later. Further, the binning control unit 143A is realized by, for example, the detection device 50 or the like (FIG. 4 or the like).

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 light, the reflected light is diffusely reflected. A pattern is formed on the web 120 by this diffuse reflection. That is, the pattern is a so-called speckle pattern, which is a spot called “speckle”. Therefore, when the web 120 is imaged, an image showing the speckle pattern is obtained. Since the position of the speckle pattern is known from this image, it is possible to detect where the predetermined position of the web 120 is. The speckle pattern is generated because the irradiated laser light interferes with the uneven shape formed on the surface or inside of the web 120.

Therefore, when the web 120 is transported, the speckle pattern of the web 120 is also transported. Therefore, if the same speckle pattern is detected at different times, the carry amount is obtained. That is, when the same speckle pattern is detected and the carry amount of the pattern is obtained, the calculation unit 53F can find the carry amount of the web 120. By converting the calculated transport amount per unit time, the calculation unit 53F can determine the transport speed at which the web 120 is transported.

Specifically, assuming that the transport speed V [mm/s] and the relative distance L [mm] that is the interval at which the first imaging lens 12A and the second imaging lens 12B are installed in the transport direction 10, the following formula (1) is used. Can be shown as.

Δt=L/V (1)
In the above formula (1), the relative distance L [mm] is the distance between the first imaging lens 12A and the second imaging lens 12B, and thus can be calculated in advance. Therefore, when the time difference Δt is determined, the calculation unit 53F can calculate the transport speed V [mm/s] based on the above equation (1). In this way, the image forming apparatus can accurately determine the position in the carrying direction, the carrying amount, the carrying speed, or a combination thereof based on the speckle pattern. The image forming apparatus may output a combination of any one of a plurality of positions in the transport direction, a transport amount, and a transport speed.

As shown in FIG. 4, the first imaging lens 12</b>A and the second imaging lens 12</b>B are installed at constant intervals in the transport direction 10. Then, the web 120 is imaged at each position via the first imaging lens 12A and the second imaging lens 12B. In this way, the image forming apparatus can accurately obtain the detection result indicating the position of the web 120 in the transport direction or the orthogonal direction based on the speckle pattern.

Moreover, the detection result may indicate a relative position. Specifically, the relative position indicates the difference between the position detected by any sensor and the position detected by a different sensor. Alternatively, the relative position may be the difference between the positions of a plurality of images captured by any of the sensors a plurality of times. That is, for example, the relative position may be the difference between the position detected in the previous frame and the position detected in the next frame. In this way, the relative position indicates the amount of deviation from the position detected by the previous frame or another sensor.

The sensor may detect a position in the transport direction and the like. That is, the sensor may also be used to detect the position in each of the transport direction and the direction orthogonal to the transport direction. When used in this way, the cost can be reduced in each direction. Further, since the number of sensors can be reduced, it is possible to save space.

Further, the calculation unit 53F performs a cross-correlation calculation on the image data D1(n) and D2(n) indicating the images captured by the detection units 52A and 52B. Hereinafter, the image generated by the cross-correlation calculation is referred to as "correlation image". For example, the calculation unit 53F calculates the deviation amount ΔD(n) based on the correlation image.

For example, the cross-correlation calculation is a calculation represented by the following formula (2).

D1*D2*=F-1[F[D1].F[D2]*] (2)
In the equation (2), the image data D1(n), that is, the image data indicating the image captured at the "A position" is referred to as "D1". Similarly, in the equation (2), the image data D2(n), that is, the image data indicating the image captured at the "B position" is referred to as "D2". Further, in the above formula (2), the Fourier transform is indicated by "F[]" and the inverse Fourier transform is indicated by "F-1[]". Furthermore, in the above formula (2), the complex conjugate is indicated by "*" and the cross-correlation calculation is indicated by "*".

As shown in the equation (2), when the cross-correlation calculation “D1*D2” is performed on the image data D1 and D2, the image data indicating the correlated image is obtained. If the image data D1 and D2 are two-dimensional image data, the image data indicating the correlation image will be two-dimensional image data. If the image data D1 and D2 are one-dimensional image data, the image data indicating the correlation image will be one-dimensional image data.

Note that, in the correlation image, for example, when a broad luminance distribution is a problem, the phase-only correlation method may be used. The phase-only correlation method is, for example, a calculation represented by the following formula (3).

D1*D2*=F-1[P[F[D1]]·P[F[D2]*]] (3)
In the above equation (3), “P[]” indicates that only the phase is extracted in the complex amplitude. Note that all the amplitudes are “1”.

In this way, the calculation unit 53F can calculate the deviation amount ΔD(n) based on the correlation image even if the brightness distribution is broad.

The correlation image shows the correlation between the image data D1 and D2. Specifically, the higher the degree of coincidence between the image data D1 and D2, the steeper the peak, the so-called correlation peak, is output at a position closer to the center of the correlation image. Then, when the image data D1 and D2 match, the center and peak positions of the correlation images overlap.

Based on the timing calculated by such calculation, the black liquid ejection head unit 210K and the cyan liquid ejection head unit 210C respectively eject liquid. The timing of ejecting the liquid is controlled by the first signal SIG1 for the black liquid ejection head unit 210K, the second signal SIG2 for the cyan liquid ejection head unit 210C, and the like output from the controller 520. As illustrated, the control unit 54F outputs a signal to control the timing based on the result of the calculation by the calculation unit 53F. The controller 54F is realized by, for example, the controller 520 or the like.

The calculation unit 53F also outputs the transport speed V calculated based on the detection result to the setting unit 55F. Note that the setting unit 55F may calculate and set the optical zoom magnification, the aperture value, the exposure time, or a combination thereof based on the transport speed V received from the outside such as the calculation unit 53F. Further, the conveyance speed V may be input to the setting unit 55F based on the operation mode such as the resolution of the output image of the image forming apparatus. The setting unit 55F is realized by, for example, a setting device (FIG. 4) such as a microcomputer.

The setting unit 55F, for example, sets the outputs from the optical elements to be combined when the transport speed V is high. Whether or not the transport speed V is high is determined by, for example, whether or not the transport speed V is faster than a preset reference speed.

When the shutter speed and the like are further set, the shutter control unit 141A may control the shutter speed and the like so that the shutter speed is set by the setting unit 55F. The shutter control unit 141A is realized by, for example, the control device 52 (FIG. 4) and the like.

Similarly, when the setting unit 55F sets the aperture value or the optical zoom magnification, the aperture value or the optical zoom magnification may be further controlled.

With this configuration, the detection unit can perform the binning process on the captured image according to the transport speed V. The controller 520 and the like may perform the calculation and the setting.

The aperture value is calculated so that the amount of received light is inversely proportional to the exposure time determined by the transport speed V. For example, the aperture value is calculated by the following equation (4).

I=Io×(NA×Mo) ²
Depth of focus=±k×wavelength/{2×(numerical aperture) ² } (4)
In the above formula (4), “I” indicates the brightness of the image. Further, “Io” indicates the brightness of the sample surface. Further, in the above formula (4), “NA” indicates the numerical aperture which is an example of the aperture value. Further, in the above formula (4), “Mo” indicates the magnification of the objective lens. That is, the numerical aperture of the diaphragm is set. In the case of the above formula (4), the amount of received light is proportional to the square of the numerical aperture. Therefore, when the exposure time is “½” times, the numerical aperture is “√2” times. It

Note that the image forming apparatus may store the optical zoom magnification, the exposure time, and the aperture value corresponding to the transport speed in a look-up table or the like by an experiment or evaluation performed in advance. Then, the setting unit 55F specifies the exposure time and the aperture value according to the transport speed from the look-up table and the like, and sets the exposure time and the aperture value.

FIG. 9 is an external view showing an example of an apparatus that realizes the detection unit according to the embodiment of the present invention. Further, the detection unit may be realized by the configuration shown in the figure.

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

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

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

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

Further, in the following description, the “position where the sensor is installed” refers to the position where detection or the like is performed. Therefore, it is not necessary to install all the devices used for detection and the like at the "position where the sensor is installed", and devices other than the sensor connected by cables or the like may be installed at other positions. Note that the black sensor SENK, the cyan sensor SENC, the magenta sensor SENM, and the yellow sensor SENY illustrated in FIG. 2 are 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 ejection position. When the sensor is installed at a position close to each ejection position, the distance between each ejection position and the sensor becomes short. When the distance between each ejection 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 transport direction or the orthogonal direction by the sensor.

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

More preferably, the position where the sensor is installed is more preferably a position closer to the first roller than the ejection position between the rollers. That is, it is more preferable that the position where the sensor is installed is upstream of each ejection position.

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

When the sensors are installed in the black upstream section INTK2, the cyan upstream section INTC2, the magenta upstream section INTM2, and the yellow upstream section INTY2, the image forming apparatus accurately positions the recording medium in the transport direction or the orthogonal direction. Can be detected. Further, when the sensor is installed at such a position, the sensor is installed upstream of each discharge position. Therefore, in the image forming apparatus, first, the position of the recording medium can be accurately detected by the sensor on the upstream side in the transport direction or the orthogonal direction, and the timing at which each liquid ejection head unit ejects can be calculated. That is, when the web 12 is transported to the downstream side while this calculation is performed, each liquid ejection head unit can eject ink at the calculated timing.

Note that if the position where the sensor is installed is directly below each liquid ejection head unit, color misregistration may occur due to delay in control operation or the like. Therefore, if the position where the sensor is installed is upstream of each ejection position, the image forming apparatus can reduce color misregistration and improve image quality. In addition, setting the vicinity of each discharge position or the like as a position where a sensor or the like is installed may be restricted. Therefore, it is more desirable that the position where the sensor is installed is closer to each first roller than each ejection position.

The image forming apparatus may further include a measuring unit such as an encoder. Hereinafter, an example in which the measuring unit is realized by an encoder will be described. Specifically, the encoder is installed, for example, with respect to the rotation shaft of the roller 230. By doing so, the carry amount in the carrying direction can be measured based on the rotation amount of the roller 230. By using this measurement result together with the detection result by the sensor, the image forming apparatus can discharge the liquid onto the web 120 with higher accuracy.

FIG. 10 is a diagram showing an example in which the position of the recording medium changes in the orthogonal direction. Hereinafter, an example in which the web 120 is conveyed in the conveyance direction 10 as shown in FIG. As shown in this example, the web 120 is conveyed by rollers or the like. In this way, when the web 120 is conveyed, the position of the web 120 may fluctuate in the orthogonal direction, for example, as shown in FIG. That is, the web 120 may “meander” as shown in FIG.

The fluctuation of the position of the web 120 in the orthogonal direction, that is, "meandering" occurs, for example, due to eccentricity of rollers involved in conveyance, misalignment, cutting of the web 120 by a blade, or the like. Further, when the width of the web 120 is narrow in the orthogonal direction, the thermal expansion of the rollers may affect the change in the position of the web 120 in the orthogonal direction.

FIG. 11 is a diagram showing an example of the cause of color misregistration. As described with reference to FIG. 10, when the position of the recording medium fluctuates in the orthogonal direction, that is, “meandering” occurs, color misregistration is likely to occur due to the cause shown in FIG.

Specifically, when an image is formed on a recording medium using a plurality of colors, that is, when a color image is formed, the image forming apparatus ejects each liquid ejection head unit as shown in the drawing. Ink of each color is overlaid 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 with reference to 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. May occur. That is, the color misregistration 330 occurs because the line formed by the ink ejected by each liquid ejection head unit is displaced in the orthogonal direction. As described above, when the color misregistration 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 a configuration described below, for example.

FIG. 12 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 a recording medium based on the image data and control data input from the higher-level device 71.

The host device 71 is, for example, a PC (Personal Computer) or the like. The printer device 72 also 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 higher-level device 71 via the control line 70LC. Further, the printer controller 72C transmits/receives control data to/from the printer engine 72E via the control line 72LC. By transmitting and receiving this control data, various printing conditions and the like indicated by the control data are input to the printer controller 72C, and the printer controller 72C stores the printing conditions and the like by 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 overall operation of the 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 or status to/from the printer engine 72E based on the control data transmitted from the higher-level device 71. As a result, the print control device 72Cc controls the printer engine 72E. The storage unit 110F3 illustrated in FIG. 8 is realized by, for example, the storage device 72Cm. Further, the speed calculation unit 110F4 shown in FIG. 8 is realized by, for example, the CPU 72Cp or the like. The storage unit 110F3 and the speed calculation unit 110F4 may be realized by another calculation device and storage device.

The 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 higher-level device 71 via the plurality of data lines. Next, the printer engine 72E forms an image of each color under the control of 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 conveyance control device 72Ec.

FIG. 13 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, the 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, redundant description will be omitted.

The data management device 72EC has a logic circuit 72ECl and a storage device 72ECm. As illustrated, 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. 12).

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

The storage device 72ECm preferably has a capacity capable 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 the image formation, and the image data for the next image formation.

FIG. 14 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 illustrated, the image output device 72Ei includes an output control device 72Eic, a black liquid ejection head unit 210K, which is a liquid ejection head unit for each color, a cyan liquid ejection head unit 210C, a magenta liquid ejection head unit 210M, and a yellow liquid ejection head. Unit 210Y.

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

The output control device 72Eic controls a plurality of liquid ejection head units simultaneously or individually. That is, the output control device 72Eic receives the timing input and performs control such as changing the timing of ejecting the liquid to each liquid ejection head unit. The output control device 72Eic may control any of the liquid ejection head units based on a control signal input from the printer controller 72C (FIG. 12). Furthermore, the output control device 72Eic may control any of the liquid ejection head units based on an operation by the user or the like.

In the printer device 72 shown in FIG. 12, a route for inputting image data from the higher-level device 71 and a route used for transmission/reception between the higher-level device 71 and the printer device 72 based on control data are different routes. Here is an example.

Further, the printer device 72 may be configured to perform image formation with one black color, for example. 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 ejection head units may be used. By doing so, the black ink is ejected by each of the plurality of black liquid ejection head units. Therefore, it is possible to perform faster image formation as compared with the configuration in which one black liquid ejection head unit is used.

The transport control device 72Ec (FIG. 12) is an actuator, a mechanism, a driver device, or the like that transports the web 120. For example, the conveyance control device 72Ec controls a motor or the like connected to each roller or the like to convey the web 120.

<Overall processing example>
FIG. 15 is a flowchart showing an example of overall processing by the device for ejecting liquid according to the embodiment of the present invention. For example, assume that image data indicating an image formed on the web 120 (FIG. 1) in advance is input to the image forming apparatus 110. Next, the image forming apparatus 110 performs the entire process shown in FIG. 15 based on the image data to form the image indicated by the image data on the web 120.

In step S01, the image forming apparatus detects the transport speed in the transport direction or the orthogonal direction. That is, in step S01, the image forming apparatus detects the transport speed at which the web 120 is transported in at least one of the transport direction and the orthogonal direction by the sensor.

In step S02, the image forming apparatus determines whether or not the transport speed is changed based on the transport speed detected in step S01. Next, when it is determined that the transport speed has been changed (YES in step S02), the image forming apparatus proceeds to step S03. On the other hand, when it is determined that the transport speed is not changed (NO in step S02), the image forming apparatus ends the process.

In step S03, the image forming apparatus sets an exposure time and the like. Specifically, when the optical zoom magnification, the aperture value, the exposure time, etc. are set, the image forming apparatus performs the calculation based on the above equation (4) and the like, and based on the calculation result, the optical zoom magnification. , Aperture value, exposure time, etc. are set.

In step S04, the image forming apparatus determines whether the transport speed detected in step S01 is high. Next, when it is determined that the transport speed is high (YES in step S04), the image forming apparatus proceeds to step S05. On the other hand, if it is determined that the transport speed is not high (NO in step S04), the image forming apparatus proceeds to step S06.

In step S05, the image forming apparatus controls the optical sensor to perform the binning process.

In step S06, the image forming apparatus controls so that the binning process by the optical sensor is canceled.

FIG. 16 is a diagram showing an example of the binning process according to the embodiment of the present invention. In the process shown in FIG. 15, the binning process of step S05 and the cancellation of the binning process of step S06 are, for example, the processes shown in the drawing. In the figure, one square represents one pixel of the optical element included in the area sensor.

First, before the binning process is performed or when the binning process is canceled, the optical sensor treats the optical element 112 as the minimum unit. On the other hand, when the binning process is set, the optical sensor combines, for example, four adjacent optical elements 112 into one group GRP. Specifically, the optical sensor adds the respective charges of the four optical elements 112 included in the group GRP into one data. That is, one group GRP is the 2×2 optical element 112, and when the illustrated binning process is performed, the minimum unit is the group GRP.

As described above, when the group GRP is used, the optical sensor can virtually increase the light receiving area per pixel. Therefore, the optical sensor can increase the sensitivity by increasing the light receiving area. Further, since the four charges are one data, the number of data is one quarter. Therefore, when the binning process is performed, the image forming apparatus can reduce the number of data and the calculation process.

If the brightness can be ensured, the binning process may be performed by an arithmetic device included in the image forming apparatus instead of performing the binning process in the optical device.

Alternatively, the binning process may be a line binning process of adding pixel signals in the line direction, a pixel binning process of adding pixel signals in the pixel direction, or the like. The binning process is not limited to the process of collecting four pixels. For example, the binning process may be a process of grouping more than four pixels into one group.

Further, the image forming apparatus is not limited to the case in which there are two modes, that is, a mode for canceling the binning process, that is, a high definition mode, and a mode for performing the binning process, that is, a high speed mode. For example, the image forming apparatus may change the number of pixels to be combined according to the transport speed. Specifically, in the binning process, in addition to setting four charges as one data, in the case of a higher speed, the 3×3 optical element 112, that is, nine charges may be set as one data.

With this configuration, the image forming apparatus can secure the control frequency by performing the binning process. In addition, when the binning process is performed, since the respective charges are added, a bright image is easily generated. Therefore, the image forming apparatus can accurately detect the position based on the generated image.

<Example of processing results>
FIG. 17 is a diagram showing an example of a test pattern used by the device for ejecting a liquid according to an embodiment of the present invention. First, as shown in the figure, the image forming apparatus performs test printing so that a straight line is formed in the transport direction 10 with black, which is an example of the first color. The distance Lk from the edge is obtained from the result of this test printing. In this way, when the distance Lk from the edge is adjusted manually or by the device in the orthogonal direction, the position where the first color, that is, the reference black ink is ejected is determined.

FIG. 18 is a diagram showing an example of the processing result of the overall processing by the device for ejecting the liquid according to the embodiment of the present invention. For example, assume that image formation is performed in the order of black, cyan, magenta, and yellow as shown in FIG. Further, FIG. 18B is a view of FIG. 18A viewed from the top, that is, a so-called plan view. Hereinafter, an example in which the roller 230 has an eccentricity will be described. Specifically, as shown in FIG. 18C, it is assumed that there is an eccentricity EC. In this way, if the eccentricity EC is present, a swaying OS occurs on the roller 230 when the web 120 is conveyed. As described above, when the wobbling OS occurs, the position POS of the web 120 changes. That is, the wobbling OS causes "meandering".

In order to reduce the color misregistration with respect to black, the image forming apparatus subtracts the current position of the recording medium detected by the sensor from the position of the recording medium one cycle before to detect the change in the position of the recording medium. calculate. Specifically, 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 ejection head unit 210K is set to “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 ejection 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 below the magenta liquid ejection head unit 210M is set to “Pm”. Furthermore, the difference between the position of the web 120 detected by the yellow sensor SENY and the position of the web 120 below the yellow liquid ejection head unit 210Y is “Py”.

Subsequently, the position where the liquid is landed by each liquid ejection head unit and the distance from the edge of the web 120, that is, the edge of the web 120, are “Lk3”, “Lc3”, “Lm3”, and “Ly3” for each color. ". 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 shown in the following expression (5) can be shown.

Lc3=Lk3-Pc=Lk3
Lm3=Lk3
Ly3=Lk3-Py=Lk3 (5)
Therefore, from the above formula (5), “Lk3=Lm3=Lc3=Ly3”. In this way, the image forming apparatus moves each liquid ejection head unit according to the positional fluctuation of the web 120, thereby further improving the accuracy of the landing position of the ejected liquid in the orthogonal direction. Further, in the case of forming an image, since the liquids of the respective colors land accurately, it is possible to reduce the color misregistration and improve the image quality of the formed image.

Further, it is desirable that the sensor is installed at a position closer to the first roller than the ejection position.

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

Thus, when the position where the sensor is installed is close to the ejection position, the detection error E1 becomes small. Further, when the detection error E1 is small, the image forming apparatus can accurately land the liquid of each color. Therefore, when performing image formation, since the liquid of each color lands on the image forming apparatus with high precision, color misregistration can be reduced and the image quality of the formed image can be improved.

Further, with such a configuration, there is no restriction such that the distance between the liquid ejection head units must be an integral multiple of the roller circular length d (FIG. 18), so that the liquid ejection head units are installed. The position can be freely set. That is, the image forming apparatus can accurately land the liquid of each color even if the distance between the liquid ejection head units is a non-integer multiple of the roller circular length d.

<Comparative example>
FIG. 20 is a diagram illustrating an example of the hardware configuration of the first comparative example. In the illustrated first comparative example, the position of the web 120 is detected before each liquid ejection head unit reaches the position where the liquid is ejected. For example, in this comparative example, the position where the sensor is installed is “200 mm” upstream from immediately below the liquid ejection head unit. Based on the detection result in this case, the image forming apparatus according to the first comparative example moves the liquid ejection head unit to compensate the positional fluctuation of the recording medium.

FIG. 21 is a diagram showing a processing result example of the overall processing by the device for ejecting 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 roller circle length d. In this case, the difference between the position of the web detected by each sensor and the position of the web immediately below the liquid ejection head unit is “0”. Therefore, in this comparative example, if the landing position of the liquid on the web of each color ink is the distances “Lk1”, “Lc1”, “Lm1” and “Ly1” from the edge of the web, “Lk1=Lc1=Lm1=Ly1”. Will be In this way, the positional deviation is corrected.

FIG. 22 is a diagram showing an example of the processing result of the overall processing by the device for ejecting 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 liquid ejection head units for black and cyan and the distance between the liquid ejection head units for magenta and yellow are “1.75d”, respectively. That is, the second comparative example is an example in which the distance between the black and cyan liquid ejection head units and the distance between the magenta and yellow liquid ejection head units are each a non-integer multiple of the roller circle length d.

In the second comparative example, the difference between the position of the web detected by the black sensor SENK and the position of the web under the black liquid ejection head unit 210K is “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 ejection head unit 210C is “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 ejection head unit 210M is “Pm”. Furthermore, the difference between the position of the web detected by the yellow sensor SENY and the position of the web 120 below the yellow liquid ejection head unit 210Y is set to "Py". Further, in the second comparative example, when the liquid landing position on the web of each color ink is the distances “Lk2”, “Lc2”, “Lm2” and “Ly2” from the web end, the following formula (6) is obtained. I can show a good relationship.

Lc2=Lk2-Pc
Lm2=Lk2
Ly2=Lk2-Py (6)
Therefore, “Lk2=Lm2≠Lc2=Ly2”. Thus, if the distance between the liquid ejection head units is a non-integer multiple of the roller circle length d, in this comparative example, the position of the web immediately below the cyan liquid ejection head unit 210C and the magenta liquid ejection head unit 210M. Are different by "Pc" and "Py". Therefore, the positional fluctuation of the web is not compensated, and the color shift or the like is likely to occur.

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

<Functional configuration example>
FIG. 24 is a functional block diagram showing an example of the functional configuration of a device for ejecting a liquid according to an embodiment of the present invention. As illustrated, the image forming apparatus 110 includes a plurality of liquid ejection head units, and a detection unit 110F10 for each liquid ejection head unit. The image forming apparatus 110 also includes a control unit 54F and a setting unit 55F.

The detector 110F10 is provided for each liquid ejection head unit, as shown in the figure. 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 conveyance direction of the web 120 or the orthogonal direction. The detection unit 110F10 is realized by, for example, the hardware configuration shown in FIG. 4 or FIG. Then, the detection unit 110F10 outputs the detection result indicating the transport speed of the transported object in at least one of the transport direction in which the transported object is transported or the direction orthogonal to the transport direction using the optical sensor. The detection unit 110F10 is, for example, the detection units 52A and 52B in FIG.

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

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

The setting unit 55F sets the output OUT of the optical element included in the optical sensor used by the detection unit 110F10 to be coupled based on the transport speed.

The image forming apparatus 110 may further include a moving unit that moves the liquid ejection head unit based on the detection result.

Further, desirably, the position where the detection unit 110F10 performs detection, that is, the position where the sensor is installed, is preferably a position close to the ejection position such as the black ejection position PK, such as the black inter-roller INTK1. That is, when the detection is performed with the black roller INTK1 or the like, the image forming apparatus 110 can accurately detect the position of the recording medium in the transport direction or the orthogonal direction.

Furthermore, more desirably, the position where the detection unit 110F10 performs detection, that is, the position where the sensor is installed, is the position upstream of the ejection position among the rollers, such as the black upstream section INTK2. Better. That is, when the detection is performed in the black upstream section INTK2 and the like, the image forming apparatus 110 can accurately detect the position of the recording medium in the transport direction or the orthogonal direction.

<Summary>
A device for ejecting a liquid according to an embodiment of the present invention includes a transported object detection device having an optical sensor and the like. Then, the transported object detection device 60 includes the detection unit 110F10 and the setting unit 55F, and sets the outputs of the optical elements included in the optical sensor to be combined based on the transportation speed. Then, the detection unit 110F10 is controlled by the binning control unit or the like based on the setting by the setting unit 55F, and performs the binning process or cancels the binning process. Thereby, the transported object detection device 60 can accurately detect the position of the transported object in the transport direction or the orthogonal direction.

An apparatus for ejecting liquid according to an embodiment of the present invention detects the position of an object to be conveyed such as a recording medium in the conveyance direction or the orthogonal direction at a position close to the liquid ejection head unit for each liquid ejection head unit. Next, the apparatus for ejecting the liquid according to the embodiment of the present invention moves the liquid ejection head unit based on the detection result. Therefore, the device for ejecting the liquid according to the embodiment of the present invention ejects the liquid according to the embodiment of the present invention as compared with the first comparative example and the second comparative example shown in FIGS. 21 and 22. The device can accurately compensate for the deviation occurring at the landing position of the liquid in the orthogonal direction.

Further, in the device for ejecting the liquid according to the embodiment of the present invention, unlike the first comparative example, it is less necessary to dispose each liquid ejection head unit at a position where the circumferential length of the roller is multiplied by an integer, so that each liquid is ejected. It is possible to reduce restrictions on installing the ejection head unit. Further, in the first comparative example and the second comparative example, adjustment cannot be performed without the actuator for the first color, that is, black in this example. On the other hand, the apparatus for ejecting the liquid according to the embodiment of the present invention can further improve the accuracy of the landing position of the ejected liquid in the orthogonal direction even for the first color.

Further, when the liquid is ejected to form an image on the recording medium, the apparatus for ejecting the liquid according to the embodiment of the present invention causes a color misregistration when the landing position of the ejected liquid of each color becomes accurate. It is possible to improve the quality of the formed image.

The liquid ejecting apparatus according to the present invention may be realized by a liquid ejecting system having one or more devices. For example, the black liquid ejection head unit 210K and the cyan liquid ejection head unit 210C are devices with the same housing, and the magenta liquid ejection head unit 210M and the yellow liquid ejection head unit 210Y are devices with the same housing, and both of them are provided. It may be realized by a system for ejecting a liquid.

Further, in the apparatus 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 kind of recording liquid or fixing treatment liquid. That is, the apparatus for ejecting the liquid and the system for ejecting the liquid according to the present invention may be applied to an apparatus for ejecting a liquid of a type other than ink.

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

Furthermore, the transported object is not limited to a recording medium such as paper. The material to be transported may be any material to which liquid can be attached. 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 that can adhere to the liquid even temporarily.

Further, the embodiment according to the present invention may be realized by a program for executing a part or all of the methods of causing a computer to eject a liquid, 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 above in detail, the present invention is not limited to the specific embodiments, and various modifications are possible within the scope of the gist of the present invention described in the claims. Alternatively, it can be changed.

60 Transported Object Detection Device 110 Image Forming Device 120 Web 210K Black Liquid Ejection Head Unit 210C Cyan Liquid Ejection Head Unit 210M Magenta Liquid Ejection Head Unit 210Y Yellow Liquid Ejection Head Unit SENK Black Sensor SENC Cyan Sensor SENM Magenta Sensor SENY Yellow Sensor 520 controller

JP, 2005-13476, A

Claims (11)

An optical sensor having a plurality of optical elements for receiving the light reflected by the transported object,
A setting unit configured to set outputs of at least two optical elements among the optical elements based on a speed at which the transported object is transported;
Using the output, a detection unit that outputs a detection result indicating the position or speed of the transported object in at least one of a transport direction in which the transported object is transported or a direction orthogonal to the transport direction,
Conveying object detecting equipment comprising, and has a plurality of liquid ejection head unit, the in device, each of the liquid jet head unit for discharging liquid at different locations on the path of the conveyor with respect to the conveyed object There
A control unit that causes the liquid ejection head unit to eject liquid based on the detection result,
The detection unit is provided in each of the liquid ejection head units, is provided on an upstream side of a position where the liquid ejected by the liquid ejection head unit lands on the transported object, and is used for transporting the transported object. A first roller,
A second roller that is provided in each of the liquid ejection head units, is provided on the downstream side of a position where the liquid ejected by the liquid ejection head unit lands on the transported object, and is used for transporting the transported object; Installed between
A device that ejects liquid. The apparatus for ejecting a liquid according to claim 1, wherein the setting unit receives the speed at which the transported object is transported from the outside. The device for ejecting a liquid according to claim 1 or 2, wherein the setting unit sets the optical sensor to perform a binning process of adding and combining the outputs. The device for ejecting liquid according to claim 1, wherein the detection unit obtains the detection result based on a pattern of the transported object. The pattern is generated by the interference of light emitted to the uneven shape formed on the transported object,
The apparatus for ejecting liquid according to claim 4, wherein the detection unit obtains the detection result based on an image obtained by capturing the pattern. The device for ejecting liquid according to claim 4 or 5, wherein the detection unit detects the position of the transported object based on a result of detecting the pattern at two or more different timings. The device for ejecting liquid according to any one of claims 1 to 6 , wherein the position of the detection unit is a position between the landing position and the first roller. Apparatus for discharging liquid according to any one of claims 1 to 7 wherein the carried object is characterized further comprising a moving unit for moving the liquid discharge head unit in a direction perpendicular to the direction to be conveyed .. The liquid ejecting apparatus according to any one of claims 1 to 8 , wherein the liquid is ejected based on the detection result in the conveying direction in which the conveyed object is conveyed. The objects to be conveyed to a device for discharging liquid according to any one of claims 1 to 9, characterized in that it is a long. When the liquid is discharged, an apparatus for discharging a liquid, wherein in any one of claims 1 to 10, characterized in that an image is formed on the object to be conveyed.

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