JP2006213419A - Recording paper conveying device and recording paper conveyance adjustment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high speed processing and highly accurate stop position control in conveying recording paper. <P>SOLUTION: A conveyance amount by a conveying belt for conveying the recording paper is measured by using a conveyance amount measurement means and a conveyance error of the recording paper P in a sub-scanning direction is corrected by using a check chart 30 having a plurality of lines partitioned at the minimum pitch determined based on resolution of the conveyance amount measurement means. Check lines 32-35 are previously printed on the check chart 30. Deposition positions 36-39 of an ink in an actual printer are obtained by performing printing by passing the check chart 30, deviation of the chart and the actual deposition positions 36-37 of the ink at this time is confirmed and an actual slide amount is measured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording paper conveyance device and a recording paper conveyance adjustment method provided in a printer, a facsimile machine, a copier, etc., and more particularly to a technique for correcting a recording paper conveyance error.

  In recent years, in the ink jet recording system, ink has been changed from a dye system to a pigment system due to improvement in light resistance and deterioration with time of ink, and ink viscosity has been increased. Although the blurring on the recording paper has been drastically reduced due to the increase in viscosity, conversely, the poor positional deviation accuracy (white stripes, black stripes, banding) of the recording paper landing position of ink droplets can be clearly seen. In particular, since the contribution rate of stop position accuracy during conveyance of sub-scanning recording paper is large, increasing accuracy has become an indispensable technical issue.

  In the sub-scanning recording paper transport mechanism of the ink jet recording method, conventionally, a transport method using a transport roller or a transport belt has been generally used, and a code wheel is generally installed on the transport roller shaft for controlling the feed amount. A method is adopted in which this value is read by an encoder sensor for control.

  However, in this control, accuracy is increased by accumulating the effects of parts accuracy such as eccentricity, vibration, temperature change of driving roller, eccentricity, vibration of driving pulley, code wheel, thickness deviation of conveyor belt, and assembly accuracy. There was a problem that it was difficult to perform good stop position control.

Patent Document 1 proposes a technique for correcting a position of a motor by paying attention to a slip amount existing between a conveyor belt and a conveyed object in a motor position control device.
JP 2004-29870 A

  However, in the technique described in Patent Document 1, since the object to be transported is directly sensed, sensing can be performed only at the front end or the rear end of the object to be measured. As a result, when the size of the object to be conveyed relative to the conveyance belt length is relatively small and continuous conveyance is performed, a certain degree of effect can be expected. However, in a serial printer such as an inkjet recording method, the conveyance belt Since the length of the recording paper is longer than the length of the recording paper and the conveyance is intermittent drive and minute movement, almost no effect can be expected.

  It is an object of the present invention to provide a recording paper transport apparatus and a recording paper transport adjustment method that solve the above-described conventional problems and enable high-speed processing and high-accuracy stop position control.

  In order to achieve the above object, the invention according to claim 1 is a recording paper transporting apparatus that intermittently transports recording paper, a transporting unit for transporting the recording paper, and a transporting amount measuring unit for measuring the transporting amount of the recording paper. And a means for correcting the conveyance error of the recording paper in the sub-scanning direction using an adjustment chart having a plurality of lines separated by a minimum pitch determined based on the resolution of the conveyance amount measuring unit. As a feature, this configuration makes it possible to perform high-precision positioning even when high-speed processing is performed by correcting the conveyance error of the recording paper using the conveyance amount measuring means and the adjustment chart.

  According to a second aspect of the present invention, in the recording paper conveyance device according to the first aspect, the slip amount during the acceleration driving of the intermittent driving is adjusted using the adjustment chart that is conveyed in the same manner as the recording paper. And

  The invention according to claim 3 is characterized in that, in the recording paper transport apparatus according to claim 1, at least two transport amount measuring means are installed, and by this configuration, by using a measuring means with high resolution as appropriate, More accurate control can be performed.

  The invention according to claim 4 is a recording paper transport adjustment method used in a recording paper transport device that transports recording paper intermittently, measuring the transport amount of the recording paper and the means for transporting the recording paper, An adjustment chart having a plurality of lines separated by a minimum pitch determined based on the resolution of the conveyance amount measuring means for performing measurement is created, and the adjustment chart is conveyed in the same manner as the recording paper to perform intermittent drive acceleration. Pre-adjustment of the slip amount at the time of the target drive, measure the slip amount of the recording paper transport measured in the adjustment step, write the slip amount information into the memory, and based on the information, Even if high-speed processing is performed by this method, the conveyance error of the recording paper is corrected by using the conveyance amount measuring means and the adjustment chart, and slippage during conveyance is suppressed by this method. High precision It decided it is possible.

  According to a fifth aspect of the present invention, in the recording paper conveyance adjustment method according to the fourth aspect, the recording paper conveyance adjustment method includes means for measuring the number of jobs related to the recording paper conveyance, and recalculates information in the memory according to the measurement result. According to this method, the amount of slip can be changed over time by changing the correction value step by step according to the measured value of the number of sheets that has the greatest influence, corresponding to the change in the state depending on the usage state. Stable positioning is possible.

  According to the present invention, by using the conveyance amount measuring means and the adjustment chart, it is possible to perform highly accurate positioning and stop position control when performing high-speed processing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing a cross-sectional side view of an ink jet printer for explaining an embodiment of the present invention.

  In FIG. 1, when a print command is input to a control unit 2 including a CPU (Central Processing Unit) provided in the printer main body 1, first, the paper feed roller 3 is driven to rotate and the friction with the friction pad 4. The recording paper P is separated one by one from the paper feed tray 5 by force and fed to the registration rollers 6. The registration roller 6 supplies the recording paper P to the inkjet head 7 that ejects ink droplets for image formation in synchronism with an image forming operation described later in accordance with information from the registration sensor 6S (one-dot chain line shown in the figure). Is the recording paper transport path).

  The recording paper P is transported by the transport belt 8. The conveyor belt 8 is moved in the circumferential direction by a driving roller 10 that is directly driven by a belt driving motor 9 and a driven roller 11 that is driven by the driving roller 10 via the conveyor belt 8. When the recording paper P is conveyed between the driven roller 11 and the presser plate 12 provided to face the driven roller 11, the recording paper P is conveyed by the nip between the driven roller 11 and the leading end roller 13, and the inkjet head 7. Enter the part.

  In the present embodiment, the conveyance belt 8 employs an electrostatic attraction belt conveyance method for conveyance of the recording paper P, but is not limited to this conveyance method. In this example, the conveyance belt 8 is an electrostatic attraction belt, and is made of a polymer material that is charged by the charging roller 14 and remains at a certain value or more. The recording paper P is transported while being electrostatically attracted by the transport belt 8, and when the carriage 15 is driven in the main scanning direction perpendicular to the moving direction of the recording paper P, the transport belt 8 is driven. Is temporarily stopped.

  An ink jet head 7 is mounted on the carriage 15, and when the driving of the conveyor belt 8 stops, the carriage 15 slides from the front of FIG. When the ejection of ink droplets for one line is completed, the transport belt 8 is driven again, and the recording paper P is transported to the next line image forming position and stopped. By repeating the above operation, image formation for one page is completed.

  A linear scale (not shown) is formed on the back side of the conveyor belt 8. This linear scale is formed by aluminum vapor deposition or the like, and is provided in a place where there is no problem with the platen 16 facing the inkjet head 7. An encoder sensor 17 for reading the linear scale is arranged in the loop of the conveyor belt 8, and the position of the conveyor belt 8 is controlled by the linear scale and the encoder sensor 17.

  However, when the resolution of the linear scale and the encoder sensor 17 is insufficient to obtain the intended positioning accuracy, the linear scale and the encoder sensor 17 are used by using the code wheel 18 and the rotary encoder sensor 19 having higher resolution. Complement the range that cannot be detected.

  By controlling the conveyance belt 8 closest to the recording paper P by the linear scale and the encoder sensor 17, the eccentricity, blurring, temperature change of the rollers 10, 11, the eccentricity, deflection of the code wheel 18, and the thickness deviation of the conveyance belt. It is possible to perform positioning in a state that includes all the effects of parts accuracy and assembly accuracy.

  However, even if the control by the conveyance state detection is performed, the conveyance belt 8 and the recording paper P are only held by the finite adsorption force and friction force, and the state transition from the static friction to the dynamic friction, and from the dynamic friction to the static friction, in particular. Friction slip occurs at the rise and fall of the conveyor belt drive, which is likely to occur, resulting in an error in position accuracy.

  FIG. 2 is a diagram showing the speed control profile 20 of the belt drive motor 9 and the movement distance of an arbitrary point on the recording paper P on the conveying belt 8 with time taken on the horizontal axis.

  As shown in FIG. 2, an ideal state in which frictional slip does not occur between the recording paper P and the conveyance belt 8 is a waveform 21. At the stage of the first acceleration motion 24 at the start of movement, the conveyor belt 8 gradually starts to move, and when it reaches a constant speed, the moving distance increases in a relationship substantially proportional to time. When approaching the target position, the movement proceeds to the second acceleration motion 25, decelerating for positioning, and stopping. While the belt drive motor 9 is stopped, the carriage 15 moves and prints on the recording paper P as described above.

  When frictional slip occurs due to the first acceleration motion 24, the actual behavior of the recording paper is a waveform 22. At this time, since the moving distance of the recording paper P becomes shorter than the moving distance of the conveying belt 8, the image formation is light and dark in the vertical direction with respect to the paper feeding direction. In extreme cases, black stripes are generated. . On the contrary, when frictional slip is generated by the second acceleration motion 25, the waveform 23 is obtained, and on the contrary, white stripes may be generated.

  FIGS. 3A and 3B are diagrams illustrating an example of a check chart that is an adjustment chart in the present embodiment.

  This check chart is assumed to be printed for each resolution (600 dpi in this example) in the inspection process in the printer manufacturing process and used for adjustment / correction. It may be used for adjustment.

  In this example, the high-resolution code wheel 18 is 300 lpi, and the minimum resolution of the printer is 300 lpi × 4 = 1200 lpi as sensing by quadruple multiplication. Further, if the outer diameter ratio between the driven roller 11 and the code wheel 18 is 1: 2, the minimum resolution is 1200 lpi × 2 = 2400 dpi≈10.58 μm. Therefore, the minimum pitch 31 of the check chart 30 is also determined according to this value so that 2400 dpi can be sensed.

  If the head nozzle interval of the inkjet head 7 is, for example, 600 dpi, printing can be performed only up to 600 dpi in one scan. Therefore, if dot droplets are landed at 2400 dpi, at least three belt feeds are performed. Is required. Therefore, check lines 32 to 35 are printed on the check chart 30 in advance. When the check chart 30 is passed through and printing is performed, the actual landing positions 36 to 39 of the printer are obtained. The deviation between the chart at this time and the actual ink landing positions 36 to 37 is confirmed, and the actual slip amount is measured.

  In the actual inspection process, since the accuracy of the leading edge position (registration positioning) of the recording paper is generally larger than the dot pitch, a resist adjustment layer (ST) 40 is provided at the leading edge portion of the chart to set the reference position of the head nozzle. Determine.

  After that, a plurality of lines (+5 to -5 in this example) are prepared by intentionally shifting the landing positioning on one recording sheet surface, and the line matched with the resist adjustment layer 40 is used as a reference position on the same line. Check the amount of deviation and confirm the slip amount.

  The operations are summarized in the flowcharts of FIGS. These are performed for each speed control profile, printing mode, and assumed recording paper, the amount of slip is measured in each operation mode, and the data is stored in a non-volatile memory such as the ROM 50 provided in the control unit 2.

  As an inspection method, visual confirmation is possible up to about several tens of μm, but when the resolution is further improved, for example, by reading the print output with a high resolution scanner and measuring the amount of deviation by image processing It is also possible to write to the ROM 50 or the memory of the CPU.

  As described above, the amount of slip for each actual machine is stocked in the memory, and correction at the time of driving as shown in FIG. 7 is performed, so that positioning control with higher accuracy becomes possible.

  In the above embodiment, it is particularly effective to carry out the inspection process before leaving the factory. However, according to the configuration of the embodiment that executes the flow shown in FIG. Can respond. That is, when continuously operated in the market, the physical conditions change due to wear of the belt, and the amount of slip increases, so it is possible to cope with this change.

  In the embodiment shown in FIG. 8, the relationship between the data and information (for example, the number of sheets to be passed) and the slip amount corresponding to the use state is previously stored in the memory as a data table, and the control unit 2 always passes the sheet. The number of sheets is determined, compared with the stored data in the memory, and the CPU or the like makes an adjustment based on the virtual slip amount, and writes the current data in the memory.

  The present invention is a recording paper conveyance device and a recording paper conveyance adjustment method applicable to office printers, facsimile machines, and copiers, and is particularly effective when applied to an inkjet engine capable of high-speed processing and high-precision stop position control. .

The block diagram which shows the ink jet printer for describing embodiment of this invention in a cross section, and shows it The speed control profile of the belt drive motor in the present embodiment and the movement distance of any one point on the recording paper on the transport belt, taking time on the horizontal axis (A), (b) is a figure which shows an example of the chart in this embodiment. Flowchart relating to check chart printing in this embodiment Flow chart relating to slip amount determination in the present embodiment Flowchart for correction amount determination in this embodiment Flow chart relating to conveyance device adjustment in the present embodiment Flowchart relating to adjustment operation in another embodiment

Explanation of symbols

2 Control Unit 7 Inkjet Head 8 Conveyor Belt 9 Belt Drive Motor 17 Encoder Sensor 18 Code Wheel 19 Rotary Encoder 30 Check Chart 50 Memory (ROM)

Claims (5)

  In a recording paper conveying apparatus that intermittently conveys recording paper, a means for conveying the recording paper, a conveying amount measuring means for measuring the conveying amount of the recording paper, and a minimum pitch determined based on the resolution of the conveying amount measuring means A recording paper transport apparatus comprising means for correcting a transport error of the recording paper in the sub-scanning direction using an adjustment chart having a plurality of lines separated by.   2. The recording paper conveying apparatus according to claim 1, wherein a slip amount at the time of intermittent driving acceleration is adjusted using the adjustment chart that is conveyed in the same manner as the recording paper.   2. A recording paper transport apparatus according to claim 1, wherein at least two transport amount measuring means are provided.   A recording paper transport adjustment method used in a recording paper transport device that intermittently transports recording paper, and measures the recording paper transporting means and the recording paper transporting amount, and the resolution of the transporting amount measuring unit that performs the measurement An adjustment chart having a plurality of lines separated by a minimum pitch determined based on the above is created, and the adjustment chart is conveyed in the same manner as the recording paper, and the slip amount at the time of the intermittent drive is adjusted in advance. And measuring the slip amount of the recording paper transport measured in the adjustment step, writing information on the slip amount into a memory, and correcting an error during transport of the recording paper based on the information. Recording paper conveyance adjustment method. 5. The recording paper transport adjustment method according to claim 4, further comprising means for measuring the number of jobs related to recording paper transport, and recalculating the information in the memory in accordance with the measurement result.

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