Conveying device and image forming apparatus

Abstract

To provide a conveying device and an image forming apparatus that can prevent an erroneous detection of an edge of a recording medium and continuously and accurately detect the edge.SOLUTION: There is provided a recording medium conveying device including conveying means for conveying a recording medium to an image formation unit, control means for controlling the conveying means, and detection means provided on a conveying path of the recording medium of the conveying means and for detecting the amount of skew and shift of the recording medium fed into the conveying means, in which the control means shifts a conveying center position of the recording medium in a direction perpendicular to a conveying direction of the recording medium based on the amount of skew and shift, and moves a conveying paper edge of the recording medium to outside of a foreign object.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conveying device and an image forming apparatus. [Background technology]

[0002] For the purpose of estimating the cause of errors occurring in recording media such as paper in an image forming apparatus, there is already known technology for detecting errors related to the width, center position, and side position of the recording media according to the output signal of a reading unit such as a contact image sensor (CIS). Also, there is already known technology for the purpose of nonstop correction of skew and shift during conveyance of the recording media, in which the amount of skew and shift of the recording media is detected on one side parallel to the conveyance direction, and meandering correction is performed while the recording media is conveyed by a conveyance roller.

[0003] Patent document 1 discloses a technology that enables accurate detection of the position of the edge of a sheet of paper even if there is a partial abnormality in the reading unit.The technology detects in advance whether the reading unit at a position that is likely to be used to detect the position of the edge of the sheet of paper is abnormal due to paper dust or dirt, and if an abnormality is detected, moves the sheet in a direction perpendicular to the transport direction (outside the paper dust) before detecting the position of the edge of the sheet of paper so as to avoid detecting the position of the edge of the sheet of paper at this position.This technology enables accurate detection of the position of the edge of a sheet of paper even if there is a partial abnormality in the reading unit. Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above technology, if paper dust accumulates on the contact image sensor, the edge of the recording medium may be erroneously detected, and the skew and shift of the recording medium may not be accurately corrected.

[0005] The present invention has been made in consideration of the above, and aims to provide a conveying device and an image forming device that can prevent erroneous detection of the edge of a recording medium and continuously detect the edge accurately. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention comprises a conveying means for conveying a recording medium to an image forming section, a control means for controlling the conveying means, and a detection means arranged on the conveying path of the recording medium of the conveying means and for detecting the amount of skew and shift of the recording medium fed into the conveying means, and the control means shifts the conveying center position of the recording medium in a direction perpendicular to the conveying direction of the recording medium based on the amount of skew and the amount of shift, and moves the conveying paper edge of the recording medium outside of any foreign matter. [Effects of the Invention]

[0007] According to the present invention, it is possible to prevent erroneous detection of the edge of the recording medium and to continuously and accurately detect the edge. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a line head type printing machine according to this embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of a registration / imaging unit of a line head type printing machine according to this embodiment. [Figure 3] FIG. 3 is an enlarged view of an example of the periphery of a shift roller of a line head type printing machine according to this embodiment. [Figure 4] FIG. 4 is a diagram for explaining the problems of a printing machine of the prior art. [Figure 5] FIG. 5 is a block diagram showing an example of the functional configuration of a line head type printing machine according to this embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of the flow of a process for correcting main scanning positional deviation and skew amount in a line head type printing machine according to this embodiment. [Figure 7]FIG. 7 is a diagram for explaining an example of a correction process for main scanning positional deviation and skew amount in a line head type printing machine according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a conveying device and an image forming device will be described in detail with reference to the accompanying drawings.

[0010] Fig. 1 is a diagram showing an example of the configuration of a line head type printing press according to this embodiment. As shown in Fig. 1, the printing press according to this embodiment has a registration / imaging unit 1, a pre-coating unit 2, a paper feed unit 3, a drying / cooling unit 4, a reversing unit 5, and a paper discharge unit 6. As shown in Fig. 1, the printing press according to this embodiment conveys a recording medium such as paper in the direction of arrow D to perform printing.

[0011] The paper feed unit 3 feeds and transports paper one sheet at a time. In other words, the paper feed unit 3 is an example of a transport means that transports paper (an example of a recording medium) to the registration and imaging unit 1 (an example of an image forming section). The pre-coating unit 2 applies an undercoat liquid to the paper beforehand, since ink does not adhere well to some types of paper. The registration and imaging unit 1 detects and corrects the registration and skew of the paper. The registration and imaging unit 1 then transfers the paper from the cylinder (upstream) to the drum using a gripper (paper transport claw). The registration and imaging unit 1 is also an example of an image forming section that prints with a line head while adsorbing the paper to the drum.

[0012] The drying and cooling unit 4 dries the moisture in the ink. Depending on the paper, the temperature can become high, so the drying and cooling unit 4 cools the paper. The reversing unit 5 switches back and reverses the paper when printing on the back side, and transports the paper in the direction of the registration and imaging unit 1. The paper discharge unit 6 stacks the paper after printing has been completed.

[0013] FIG. 2 is a diagram showing an example of the configuration of a registration / imaging unit of a line-head printing press according to this embodiment. In this embodiment, registration / imaging unit 1 detects the main scanning misalignment (an example of the shift amount) and skew amount, which are misalignments in the main scanning direction, using edge sensors 12a and 12b before the paper enters shift roller 11. That is, edge sensors 12a and 12b are arranged on the paper transport path of paper feed unit 3 and are an example of a detection means for detecting the skew amount and main scanning misalignment of the paper being fed into paper feed unit 3. Next, control unit S11 of registration / imaging unit 1 moves shift roller 11 to a position directly facing the paper based on the detection results of the main scanning misalignment and skew amount, thereby correcting the main scanning misalignment and skew of the paper that has entered shift roller 11.

[0014] That is, the control unit S11 functions as an example of a control unit that shifts the center position of the paper in a direction (hereinafter referred to as the main scanning direction or X-axis direction) perpendicular to the paper transport direction (hereinafter referred to as the sub-scanning direction or Y-axis direction) based on the skew amount and the main scanning position deviation, thereby moving the edge of the paper (the paper edge) outside of foreign matter such as paper dust. The control unit S11 also shifts the paper edge in the main scanning direction outside of foreign matter other than paper dust. This allows the paper edge to be continuously detected even if foreign matter other than paper dust is present. The control unit S11 may also repeatedly shift the center position of the paper transport. This can extend the operating time of the product. Furthermore, the control unit S11 may prompt the user to perform cleaning if the center position of the paper transport is shifted to a position where the CIS of the edge sensors 12a and 12b cannot detect the paper edge. This can avoid error stops due to false edge detection and improve the operating rate of the product. Paper dust and dirt are examples of foreign matter.

[0015] Thereafter, the registration / imaging unit 1 again detects the misalignment in the main scanning direction and the amount of skew of the paper using edge sensors 12b and 12c (edge ​​sensor 12d for small size paper), corrects the misalignment in the main scanning direction and the skew using control unit S11, and causes the leading edge of the paper to be gripped by gripper 13, which opens and closes mechanically and is attached to entrance cylinder 14. Entrance cylinder 14, imaging drum 15, and exit cylinder 18 are connected by gears, and the paper is transported while being gripped alternately by the attached grippers.

[0016] The print heads 17 (17a, 17b, 17c, 17d) of the registration / imaging unit 1 are inkjet heads (for example, inkjet heads for K, C, M, and Y colors) that are line heads connected in the X-axis direction (main scanning direction), and eject ink to form an image when the paper 10 passes under the print heads 17. At that time, the print timing is determined based on the timing when the paper passes over the print timing sensor 16.

[0017] 3 is an enlarged view of an example of the area around a shift roller of a line head printing press according to this embodiment. The shift roller 11 (shift / skew correction roller) is a roller that can rotate around a rotation center and move in the X-axis direction. The printing press has a function to correct the amount of skew and main scanning position deviation calculated based on the edges of the conveyed paper detected by multiple edge sensors 12a to 12d.

[0018] In the printing press, in the first paper state shown in FIG. 3, the edge sensors 12a and 12b detect the main scanning positional deviation and the amount of skew before the paper enters the shift rollers 11.

[0019] In addition, in the second paper state shown in Figure 3, the control unit S11 of the printing press moves the shift roller 11 to a position directly facing the paper in accordance with the detection results of the main scanning position shift and the amount of skew, and corrects the main scanning position shift and the amount of skew of the paper that has entered the shift roller 11.

[0020] 3, the printing press again detects the main scanning misalignment and skew amount of the paper 10 using edge sensors 12b and 12c, and the control unit S11 corrects the main scanning misalignment and skew amount. In the case of small-sized paper, it is difficult to detect the main scanning misalignment and skew amount of the paper 10 due to the distance restriction from edge sensor 12b to edge sensor 12c, so the control unit S11 switches from edge sensor 12b to edge sensor 12d and controls the correction of the main scanning misalignment and skew amount.

[0021] FIG. 4 is a diagram illustrating the problems with a conventional printing press. Conventional printing presses transport paper with high precision using the method shown in FIG. 3. However, as the number of sheets of paper passing through increases, paper dust accumulates outside the paper edge definition position 400. When a certain amount of paper dust accumulates, the CIS is no longer able to distinguish between the edge of the paper and the accumulated paper dust. As a result, the paper edge position is incorrectly detected, resulting in poor correction accuracy for misalignment of the paper in the main scanning direction and skew amount, or an error stating that the paper is misaligned causes the printer to stop.

[0022] Fig. 5 is a block diagram showing an example of the functional configuration of a line head printing press according to this embodiment. In this embodiment, the printing press has a paper transport unit S6, a control unit S11, a cleaning notification unit S10, etc. As shown in Fig. 5, the control unit S11 has a transported sheet count storage unit S7, a count comparison unit S8, a control determination unit S9, etc.

[0023] The transported sheet count storage unit S7 receives a transport notification from the paper transport unit S6, which has shift rollers 11 and the like, counts the number of transported sheets, and stores the count value. After the transported sheet count storage unit S7 counts the number of transported sheets, the count comparison unit S8 compares the count value (number of transported sheets) to determine whether it is equal to or greater than a certain number. Depending on the comparison result between the number of transported sheets and the certain number, the control decision unit S9 notifies the paper transport unit S6 whether or not to shift the center position of the paper transport. The control decision unit S9 also determines whether or not to notify the user to clean, and notifies the cleaning notification unit S10 of the decision result (cleaning notification). The cleaning notification unit S10 notifies the user to clean.

[0024] 6 is a flowchart showing an example of the flow of the process for correcting main scanning misalignment and skew amount in a line head printer according to this embodiment. First, the conveyed sheet count storage unit S7 clears the count value of the number of conveyed sheets (step S1). Next, when a sheet conveyance notification is input from the sheet conveyance unit S6 (step S2), the conveyed sheet count storage unit S7 increments the count of the number of conveyed sheets (step S3).

[0025] Next, the count comparison unit S8 determines whether the number of conveyed sheets counted by the conveyed sheet count storage unit S7 exceeds a certain number (step S4). If the number of conveyed sheets is equal to or less than the certain number (step S4: No), the conveyed sheet count storage unit S7 returns to step S3 and continues counting the number of conveyed sheets. On the other hand, if the number of conveyed sheets exceeds the certain number (step S4: Yes), the control determination unit S9 shifts the center position of the paper conveyance (step S5).

[0026] 7 is a diagram illustrating an example of a process for correcting main scanning misalignment and skew in a linehead printer according to this embodiment. In this embodiment, the control determination unit S9 shifts the center position of the paper transport so that the edge of the transported paper is outside the paper dust every time a certain number of sheets are transported. By always positioning the edge of the transported paper outside the paper dust, the CIS can accurately detect the edge of the transported paper, preventing problems seen in conventional technology.

[0027] In this way, with the printing machine of this embodiment, by shifting the center position of the paper transport so that the edge of the transported paper is outside the paper dust, the edge of the transported paper is always outside the paper dust, thereby preventing erroneous detection of the edge of the transported paper and enabling continuous accurate detection of the edge of the transported paper.

[0028] In the above embodiment, the image forming apparatus of the present invention is described as being applied to a multifunction peripheral having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function, but the present invention can be applied to any image forming apparatus such as a copier, printer, scanner device, or facsimile device.

[0029] For example, aspects of the present invention are as follows.

[0030] <1> a conveying means for conveying the recording medium to the image forming unit; a control means for controlling the conveying means; a detection means disposed on a transport path of the recording medium of the transport means, for detecting a skew amount and a shift amount of the recording medium fed into the transport means; The control means shifts the center position of the recording medium in a direction perpendicular to the recording medium conveying direction based on the skew amount and the shift amount, and moves the conveying paper edge of the recording medium outside the foreign object. <2> the foreign matter is paper dust, and the control unit moves the edge of the conveyed paper to an outer side of the foreign matter other than paper dust in a direction perpendicular to the conveyance direction. <1> The conveying device according to claim 1. <3> the control means extends the operating time by repeatedly moving the transport center position; <1> or <2> The conveying device according to claim 1. <4> the detecting means has a CIS (Contact Image Sensor), the control unit prompts a user to perform cleaning when the center position of conveyance is shifted to a position where the CIS cannot detect the edge of the conveyed paper. <1> from <3> 10. The conveying device according to claim 9, wherein <5> an image forming unit; a conveying means for conveying a recording medium to the image forming unit; a control means for controlling the conveying means; a detection means disposed on a transport path of the recording medium of the transport means, for detecting a skew amount and a shift amount of the recording medium fed into the transport means; The control means shifts the center position of the transport of the recording medium in a direction perpendicular to the transport direction of the recording medium based on the skew amount and the shift amount, and moves the transport paper edge of the recording medium outside the foreign object. [Explanation of symbols]

[0031] 1. Resist / imaging unit 2. First coating unit 3 Paper feed unit 4 Drying and cooling units 5 Reversing unit 6 Paper output unit 11 Shift Roller 12a, 12b, 12c, 12d Edge sensors S6 Paper transport section S7 Conveyed sheet count storage unit S8 Count comparison section S9 Control decision unit S10 Cleaning notification section S11 Control unit [Prior art documents] [Patent documents]

[0032] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-137710

Claims

1. a conveying means for conveying the recording medium to the image forming unit; a control means for controlling the conveying means; a detection means disposed on a transport path of the recording medium of the transport means, for detecting a skew amount and a shift amount of the recording medium fed into the transport means; The control means shifts the center position of the recording medium in a direction perpendicular to the recording medium conveying direction based on the skew amount and the shift amount, and moves the conveying paper edge of the recording medium outside the foreign object.

2. The foreign matter is paper powder, 2. The conveying device according to claim 1, wherein the control means moves the edge of the conveyed paper to the outside of foreign matter other than paper dust in a direction perpendicular to the conveying direction.

3. 3. The transport device according to claim 1, wherein the control means extends the operating time by repeatedly moving the transport center position.

4. the detecting means has a CIS (Contact Image Sensor), 3. The conveying device according to claim 1, wherein the control unit prompts a user to perform cleaning when the conveying center position is shifted to a position where the CIS cannot detect the edge of the conveyed paper.

5. an image forming unit; a conveying means for conveying a recording medium to the image forming unit; a control means for controlling the conveying means; a detection means disposed on a transport path of the recording medium of the transport means, for detecting a skew amount and a shift amount of the recording medium fed into the transport means; The control means shifts the center position of the transport of the recording medium in a direction perpendicular to the transport direction of the recording medium based on the skew amount and the shift amount, and moves the transport paper edge of the recording medium outside the foreign object.

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