JP2022041174A - Pulse generation apparatus, image formation apparatus, and pulse generation program - Google Patents

Abstract

To prevent occurrence of printing misalignment.SOLUTION: When generating a pulse for driving a print head, an acquisition unit acquires a captured image obtained by imaging a conveyed article at predetermined time intervals. A position detection unit detects the same position on each of the consecutive captured images acquired by the acquisition unit, and a moving distance detection unit detects moving distance of the conveyed object based on the distance between the same positions on each of captured images detected by the position detection unit. Then, a pulse generation unit generates a pulse when the moving distance of the conveyed object detected by the moving distance detection unit becomes fixed distance. Thus, it is possible to generate a pulse synchronized with the moving distance of the conveyed object and to prevent printing misalignment to the conveyed object.SELECTED DRAWING: Figure 5

Description

The present invention relates to a pulse generator, an image forming apparatus and a pulse generation program.

Conventionally, in an image forming apparatus having a plurality of line heads, the ink ejection timing (printing timing) of each color is based on the detection value of an encoder provided on a roller driven by a medium (web) for detecting a web transport amount. ) Has been decided. Further, there is known a technique of reducing the influence of deformation due to a temperature change of an encoder roller that detects the amount of web transport, suppressing the occurrence of print misalignment, and preventing deterioration of print quality.

Further, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2020-70163), when the transport of the medium is stopped, the looseness of the straddled medium is suppressed and printing defects such as printing misalignment can be prevented. The system is disclosed. This printing system includes a first guide roller for transporting a long medium, a second guide roller for sandwiching the medium together with the first guide roller, and an electromagnetic brake connected to the second guide roller. Then, when the transport of the medium is stopped, the rotation of the second guide roller is stopped by the braking of the electromagnetic brake. As a result, when the transport of the medium is stopped, it is possible to suppress the loosening of the stretched medium and prevent printing defects.

However, the conventional printing apparatus has a problem that printing misalignment also occurs due to the eccentricity of the encoder roller itself and the slippage of the medium with respect to the roller.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a pulse generation device, an image forming device, and a pulse generation program capable of suppressing the occurrence of print misalignment.

In order to solve the above-mentioned problems and achieve the object, the present invention has an acquisition unit that acquires captured images obtained by capturing images of the conveyed object at regular intervals, and each continuous captured image acquired by the acquisition unit. A position detection unit that detects the same position above, a movement distance detection unit that detects the movement distance of the transported object based on the distance between the same positions on each captured image detected by the position detection unit, and a movement distance detection. It has a pulse generating unit that generates a pulse when the moving distance of the transported object detected by the unit becomes a constant distance.

According to the present invention, there is an effect that the occurrence of print misalignment can be suppressed.

FIG. 1 is a diagram showing a system configuration of the image forming system of the embodiment. FIG. 2 is a diagram for explaining an image sensor provided in the image forming system of the embodiment. FIG. 3 is a diagram showing a hardware configuration and a functional configuration of a first inkjet printer device provided in the image forming system of the embodiment. FIG. 4 is a flowchart showing the flow of the ejection timing signal generation operation for controlling the ink ejection timing in the image forming system of the embodiment. FIG. 5 is a diagram for explaining a discharge timing signal generation operation in the image forming system of the embodiment.

Hereinafter, the image forming system according to the embodiment will be described with reference to the attached drawings.

(System configuration)
FIG. 1 is a diagram showing a system configuration of the image forming system of the embodiment. As shown in FIG. 1, the image forming system of the embodiment includes a paper feeding device 1, a processing agent liquid applying device 2, a first inkjet printer device 3a, a reversing device 4, and a second inkjet printer device 3b. ing.

The paper feeding device 1 feeds the web W, which is, for example, a long (continuous paper) recording medium. The web W fed from the paper feed device 1 is conveyed to the treatment agent liquid application device 2, and the treatment agent liquid is applied to the front and back surfaces as a pretreatment. The web W coated with the treatment agent liquid is conveyed to the first inkjet printer device 3a. In the first inkjet printer device 3a, ink droplets are ejected onto the surface of the web W by a plurality of line head units to form a desired image.

The front and back of the web W on which the image is formed are inverted by the inversion device 4, and the web W is conveyed to the second inkjet printer device 3b. The second inkjet printer device 3b forms a desired image by ejecting ink droplets on the back surface of the web W by a plurality of line head units provided. The web W on which the desired image is formed on both sides in this way is conveyed to a post-processing device (not shown) and subjected to predetermined post-processing.

(Structure of main parts)
FIG. 2 is a diagram showing a configuration of a main part of the image forming system of the embodiment. FIG. 2 shows the treatment agent liquid application device 2 for applying the treatment agent liquid to the web W, and the print heads 10C and 10M of each color of cyan (C), magenta (M), yellow (Y) and black (K). The configuration in which the image sensor 15 is provided between the first inkjet printer device 3a provided with 10Y and 10K is shown.

In the image sensor 15, which is an example of the image pickup unit, a predetermined tension is applied by a tension roller, and a pair of transfer rollers 11a and 11b (an example of the transfer unit) is used to transfer the treatment agent liquid application device 2 to the first inkjet printer device 3a. The conveyed web W is imaged at regular intervals. The fixed cycle is shorter than the cycle in which the encoder makes a round, assuming that an encoder that rotates at a fixed cycle is provided to detect the moving distance of the web W. In other words, the period is shorter than the period in which one encoder pulse is generated.

In this example, the image sensor 15 is provided between the processing agent liquid application device 2 and the first inkjet printer device 3a, but any position can capture the image of the conveyed web W. It may be provided at a position. For example, it may be provided in the first inkjet printer device 3a, in the reversing device 4, or in the second inkjet printer device 3b, or the like. Alternatively, it may be provided between any of the devices, for example, between the first inkjet printer device 3a and the reversing device 4.

(Hardware configuration and functional configuration of the first inkjet printer device)
FIG. 3 is a diagram showing a hardware configuration and a functional configuration of the first inkjet printer device 3. As shown in FIG. 3, the first inkjet printer device 3a acquires an image captured by the image sensor 15 and ejects ink from the print heads 10C, 10M, 10Y, and 10K, which are examples of the printing unit. It has a control unit 16 that generates a pulse to generate a pulse. Further, the first inkjet printer device 3a has a memory 23 in which a pulse generation program is stored. The control unit 16 reads and executes the pulse generation program stored in the memory 23 to generate pulses for controlling the ejection of ink in the print heads 10C, 10M, 10Y, and 10K.

Further, the first inkjet printer device 3a has a transport motor drive unit 17 that rotationally drives a transport motor that transports the web W, and a print head drive unit 18 that drives the print heads 10C, 10M, 10Y, and 10K. ing. The transfer motor drive unit 17 and the print head drive unit 18 rotate and drive the transfer motor based on the pulse generated by the control unit 16, and also discharge control the print heads 10C, 10M, 10Y, and 10K.

The control unit 16 realizes the image acquisition unit 19, the image processing unit 20, the web travel distance calculation unit 21, and the pulse signal generation unit 22 by executing the pulse generation program stored in the memory 23. Then, the control unit 16 performs the pulse generation operation shown in the flowchart of FIG.

(Pulse generation operation)
In the flowchart of FIG. 4, first, when printing is started in step S1, the image acquisition unit 19 which is an example of the acquisition unit determines in step S2 whether or not a certain cycle has been reached. As described above, this fixed cycle is shorter than the cycle in which the encoder makes a round, assuming that an encoder that rotates at a fixed cycle is provided in order to detect the moving distance of the web W. .. In other words, the period is shorter than the period in which one encoder pulse is generated. If the image acquisition unit 19 does not reach a certain cycle (step S2: No), the process proceeds to step S9, and if printing is completed (step S9: Yes), the process of the flowchart of FIG. 4 is terminated as it is. do. Alternatively, if it is determined in step S9 that printing is being continued (step S9: No), the process returns to step S2.

When it is determined in step S2 that the fixed cycle has been reached (step S2: Yes), the image capturing unit 19 captures the captured image of the web W captured by the image sensor 15 in step S3. FIG. 5A shows a first captured image, a second captured image, and the like captured at regular intervals in this way. Each captured image is sequentially stored in the memory 23. The “x” mark in each captured image is, for example, the unevenness of the web W or a printed predetermined mark, and indicates the position of a pixel corresponding to the peak position of the image correlation described later. In order to image the web W to be transported, the "x" in each captured image moves according to the transport direction of the web W.

Next, the image processing unit 20, which is an example of the position detection unit, stores two consecutive captured images (two captured images before and after) in the memory 23 like the first captured image and the second captured image. It is determined whether or not the image has been processed (step S4). When two front and rear captured images are stored (step S4: Yes), the image processing unit 20 performs, for example, fast Fourier transform processing (FFT: Fast Fourier Transform) for each of the front and rear captured images in step S5. ) Is applied to detect the intensity for each pixel of each captured image. Then, the image processing unit 20 detects pixels having a peak intensity from each captured image.

In this example, the peak position of each captured image is detected by the fast Fourier transform process, but another frequency analysis method may be used, or the same point of a plurality of captured images can be extracted. If so, any method may be used.

Next, of the pixels of the two captured images before and after, the pixel having the peak intensity is the pixel at the same position. Further, since the two captured images before and after are captured images obtained by capturing the transported web W (an example of the transported object), the positions of the pixels having the peak intensity on each captured image are shown in FIG. 5 (b). As shown, the positions are separated by the transport distance of each web W. In other words, as shown in FIG. 5B, the separation distance of each peak intensity on each captured image indicates the moving distance of the web W. Therefore, in step S6, the web movement distance calculation unit 21, which is an example of the movement distance detection unit, calculates the movement distance of the web W from the separation distance of each peak intensity on each captured image.

Further, in step S7, the web moving distance calculation unit 21 determines whether or not the moving distance of the web W has reached a predetermined constant distance. Then, when the web movement distance calculation unit 21 determines that the movement distance of the web W has reached a predetermined constant distance (step S7: Yes), the web movement distance calculation unit 21 reaches a certain distance with respect to the pulse signal generation unit 22. Supply a signal.

The pulse signal generation unit 22, which is an example of the pulse generation unit, generates a pulse having a predetermined pulse width as shown in FIG. 5C at the timing when a constant distance arrival signal is supplied. As described above, the web travel distance calculation unit 21 supplies a constant distance arrival signal to the pulse signal generation unit 22 at the timing when the travel distance of the web W reaches a predetermined constant distance. This is because the amount of web W transported is reduced due to slippage in the transport roller, and the constant distance arrival signal is not supplied to the pulse signal generation unit 22 until the travel distance of the web W reaches a certain distance. It means that no pulse is generated.

In FIG. 5 (c), there is a gap between one pulse and the next pulse. This corresponds to the fact that the amount of the web W transported is reduced due to the slip of the transport roller and the like, and it takes time for the moving distance of the web W to reach a certain distance. Since a pulse is generated when the moving distance of the web W reaches a certain distance, when the amount of the web W transported is reduced due to slippage of the transport roller or the like, the previous pulse is generated and then the next pulse is generated. It will take time like this to do so.

That is, in the case of the image forming system of the embodiment, the pulse is not generated at a fixed timing, but is generated at the timing when the web W moves by a fixed distance. Therefore, the transfer motor drive unit 17 and the print head drive unit 18 drive the transfer motor exactly in synchronization with the moving distance of the web W, and also drive the print head to print on the web W. be able to.

Such a pulse generation operation is repeatedly executed until it is determined in step S9 that printing is completed (step S9: Yes) (step S9 is No and processing returns to step S2).

(Effect of embodiment)
As is clear from the above description, the image forming system of the embodiment detects the moving distance of the web W from the captured images before and after the image of the web W, and each time the moving distance becomes constant, the print head is set. Generate a pulse to drive. As a result, the print head or the like can be driven in synchronization with a certain moving distance of the web W.

Therefore, it is possible to eliminate the deviation between the pulse generation timing due to the eccentricity of the encoder roller itself, the slip of the web W with respect to the transport roller, and the actual moving distance of the web W, and it is possible to prevent the printing deviation. Therefore, the print quality can be maintained.

Further, since the moving distance of the web W is detected and the pulse is generated based on the correlation between the captured images before and after the image captured by the image sensor 15, the encoder can be eliminated.

Further, since the transport amount of the web W can be calculated from the captured image of the web W captured by the image sensor 15, it is possible to eliminate the need for advance preparation such as printing a slit on the web W, and printing with a simple configuration. It is possible to prevent misalignment.

Finally, the embodiments described above are presented as an example and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Further, the embodiment and the modification of the embodiment are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

1 Paper feed device 2 Processing agent liquid application device 3a First inkjet printer device 3b Second inkjet printer device 4 Inversion device 10C Cyan print head 10M Magenta print head 10Y Yellow print head 10K Black print head 11a Conveyor roller 11b Conveyor roller 12 Tension roller 15 Image sensor 17 Conveyor motor drive unit 18 Print head drive unit 19 Image capture unit 20 Image processing unit 21 Web travel distance calculation unit 22 Pulse signal generation unit 23 Memory

Japanese Unexamined Patent Publication No. 2020-70163

Claims (6)

An acquisition unit that acquires an image taken by capturing an image of the transported object at regular intervals, and
A position detection unit that detects the same position on each continuous captured image acquired by the acquisition unit, and a position detection unit.
A moving distance detecting unit that detects the moving distance of the transported object based on the distance between the same positions on each captured image detected by the position detecting unit, and a moving distance detecting unit.
A pulse generation unit that generates a pulse when the movement distance of the transported object detected by the movement distance detection unit reaches a certain distance, and a pulse generation unit.
A pulse generator with. The pulse generation device according to claim 1, wherein the position detection unit detects pixels at the same position on each captured image by performing frequency analysis. The position detection unit is characterized in that it detects pixels at the same position on each captured image by performing frequency analysis by a high-speed Fourier transform process and detecting pixels having a peak value on each captured image. Item 2. The pulse generator according to Item 2. The pulse generation according to any one of claims 1 to 3, wherein the conveyed object is a long storage medium that is conveyed by being wound from one end to the other end. Device. The pulse generator according to any one of claims 1 to 4.
A transport unit that transports the transported material and
An imaging unit that supplies an image taken by capturing an image of the conveyed object conveyed by the conveying unit to the pulse generator at regular intervals.
A printing unit that prints on the conveyed object in synchronization with the pulse generated by the pulse generator.
Image forming apparatus having. Computer,
An acquisition unit that acquires an image taken by capturing an image of the transported object at regular intervals, and
A position detection unit that detects the same position on each continuous captured image acquired by the acquisition unit, and a position detection unit.
A moving distance detecting unit that detects the moving distance of the transported object based on the distance between the same positions on each captured image detected by the position detecting unit, and a moving distance detecting unit.
A pulse generation program characterized by functioning as a pulse generation unit that generates a pulse when the movement distance of the transported object detected by the movement distance detection unit reaches a certain distance.

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