JP2007260991A - Printing method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure correctly the thickness over the whole width of a paper even when there exists a level difference on the paper, and to obtain a good quality of printing. <P>SOLUTION: A printing apparatus is equipped with a printing head 2 for performing printing on a medium 10, a medium thickness detecting means 8 for detecting the thickness of the medium 10, a carrier 3 fitted with the printing head 2 and the medium thickness detecting means 8 and performing the printing on the medium 10 by moving back and forth, a gap adjusting means 9 for adjusting a gap between the printing head 2 and the medium 10, a storing means 22 for storing information, and a controlling means 1 for controlling the printing. By the controlling means 1, the thickness is detected by the medium thickness detecting means 8 over the whole width of the medium 10 on the outward path of the carrier 3 to store it in the storing means 22, and on the return path of the carrier 3, while the gap is controlled by the gap adjusting means 9 in accordance with the thickness of the medium 10 stored, the printing is performed on the medium 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a medium margin of a dot impact printer or the like, and more particularly to a printing method and apparatus for paper (medium) having a step in one sheet. The dot impact printer is required to have an appropriate gap (head gap) between the paper and the print head. If this gap is not appropriate, the printing position on the paper may shift (especially during high-speed printing).

  Conventionally, there has been a method in which a laser beam is applied to a paper surface while printing (according to head movement), a gap between sheets is measured by reflected light, and the head gap is adjusted according to the measured gap (see Patent Document 1). ). In the case of copy sheets with overlapping sheets, there is a gap between the sheets, so measuring the gap with the uppermost sheet in a non-contact manner has a low accuracy and the printing quality is lowered.

Conventionally, there is a point of contamination as an adverse effect of running on the upper surface of the sheet by the sheet thickness detection roller. That is, there is a method of detecting unevenness of the paper with the paper thickness detection roller at the same time as the printing operation (simultaneously with the movement of the print head) and reflecting it in the gap of the head (see Patent Document 2).
Japanese Patent Laid-Open No. 8-25751 JP-A-4-265777

  The conventional device has the following problems.

  (1): The method of measuring the gap between sheets with a laser beam and adjusting the head gap according to the measured gap is non-contact, so there is a gap between the sheets of copy paper. Measuring only the gaps of these results in low accuracy and poor print quality.

  (2): The method of running on the upper surface of the paper with a roller, detecting the unevenness of the paper at the same time as the printing operation, and reflecting it in the gap of the head cannot be followed unless the roller pressing pressure is increased in high-speed printing. There was a problem that the paper was soiled by the roller pressure.

  The present invention solves such a conventional problem, and even if there is a step in the paper, the thickness can be measured correctly over the entire width of the paper, and good print quality can be obtained. The object is to set the detection roller pressing pressure regardless of the printing speed so that the roller pressure does not stain the paper.

  FIG. 1 is an explanatory diagram of a printing apparatus according to the present invention. In FIG. 1, 1 is a control unit (control means), 2 is a print head, 3 is a carrier, 4 is a guide plate, 5 is a guide shaft, 6 is a sheet pressing roller (roller), 7 is a pressure spring, and 8 is a gap. A sensor (medium thickness detection means), 9 is a print head height adjustment motor (gap adjustment means), 10 is paper (medium), 21 is a paper thickness detection / controller, and 22 is a storage unit (storage means).

  In order to solve the above-described conventional problems, the present invention is configured as follows.

  (1): The print head 2 for printing on the medium 10, the medium thickness detecting means 8 for detecting the thickness of the medium 10, and the print head 2 and the medium thickness detecting means 8 are attached and reciprocally move. A carrier 3 for printing on the medium 10, a gap adjusting means 9 for adjusting a gap between the print head 2 and the medium 10, a storage means 22 for storing information, and a control means 1 for controlling printing. And the control means 1 detects the thickness of the medium 10 over the entire width of the medium 10 in the forward path of the carrier 3 and stores it in the storage means 22, and the return path of the carrier 3. Then, the gap adjusting means 9 performs printing on the medium 10 while controlling the gap according to the stored thickness of the medium 10. For this reason, even if there is a step in the paper, it is possible to accurately measure the thickness over the entire width of the paper and obtain good print quality.

  (2): In the printing apparatus of (1), the medium thickness detecting means 8 presses the roller 6 against the medium 10 and detects the thickness of the medium 10 above and below the roller 6. For this reason, the roller pressing pressure for detecting the thickness of the medium can be set regardless of the printing speed so that the paper is not soiled by the roller pressure.

  (3): In the printing apparatus according to (1) or (2), the medium 10 includes a step setting unit without a step, and the control unit 1 includes the carrier when the medium 10 has no step. Printing is performed for both the forward and backward passes. For this reason, in normal printing without a step of the medium, printing can be performed at high speed.

  The present invention has the following effects.

  (1): The control means detects the thickness of the medium over the entire width of the medium in the forward path of the carrier and stores it in the storage means, and according to the thickness of the stored medium by the gap adjusting means in the return path of the carrier. Since the printing is performed on the medium while controlling the gap, even if there is a step in the paper, the thickness is measured correctly over the entire width of the paper, and good print quality can be obtained.

  (2): The medium thickness detecting means presses the roller against the medium to detect the thickness of the medium above and below the roller, so the roller pressing pressure for detecting the thickness of the medium is set regardless of the printing speed. However, it is possible to prevent the paper from being soiled by the roller pressure.

  (3): It is provided with setting means for whether or not there is a step in the medium, and when the control means does not have a step in the medium, printing is performed on both the forward and return paths of the carrier. Can be printed.

  In the present invention, a roller is lightly pressed against a sheet, the thickness of the sheet (medium) is measured on the forward path of the carrier (carriage), and printing is performed while appropriately controlling the gap on the return path of the carrier.

  The printer (printing apparatus) is provided with a setting for whether there is a level difference in the medium. In this setting, when there is a step, the thickness is detected over the entire width of the paper in the forward path of the carrier reciprocation (printing is not performed). In the detection method, a vertically movable roller is provided on the carrier, and the roller moves up and down by lightly pressing the roller against the paper surface and moving the carrier. The left and right positions and the vertical position are stored. Next, printing is performed on the return path of the carrier while controlling the head gap to an appropriate value according to the sheet thickness stored in the forward path. This operation is repeated for printing.

(1): Description of Printing Device FIG. 1 is an explanatory diagram of a printing device. 1, the printing apparatus includes a control unit 1, a print head 2, a carrier 3, a guide plate 4, a guide shaft 5, a paper pressing roller 6, a pressure spring 7, a gap sensor 8, a print head height adjusting motor 9, A paper 10, a paper thickness detection / controller 21, and a storage unit 22 are provided. The control unit 1 is a control unit that controls printing, and includes a sheet thickness detection / controller 21 and a storage unit (storage unit) 22 that stores the position and thickness of the sheet. The print head 2 is a print head such as a dot impact printer that performs printing on paper. In the carrier 3, the print head 2 and the gap sensor 8 are integrated and move in the width direction of the paper. The guide plate 4 is a plate (guide means) for guiding the carrier 3 in the paper width direction. The guide shaft 5 is a shaft (guide means) for guiding the carrier 3 in the paper width direction. The paper pressing roller 6 contacts the paper with an appropriate pressure and moves up and down depending on the thickness of the paper. The pressure spring 7 is an elasticity applying unit that presses the paper pressing roller 6 with an appropriate contact pressure in the paper direction. The gap sensor 8 is a sheet thickness detecting unit that converts the vertical movement of the sheet pressing roller 6 into an electric signal. The print head height adjusting motor 9 is a motor (head gap adjusting means) for adjusting the height (head gap) of the print head 2. The rotation of the motor moves the print head 2 up and down via a transmission gear, a transmission shaft, and the like. The paper 10 is a print medium on which printing is performed by the print head 2. The sheet thickness detection / controller 21 is a controller that stores the sheet thickness detected by the gap sensor 8 and controls the print head height adjusting motor 9 according to the stored sheet thickness during printing. The storage unit 22 is storage means for storing information such as sheet thickness.

  FIG. 2 is an explanatory side view of the printing apparatus. FIG. 2 is an explanatory view of the printing apparatus of FIG. 1 as viewed from the side, and shows only the main part. In FIG. 2, the printing apparatus includes a print head 2, a carrier 3, a guide plate 4, a guide shaft 5, a sheet 10, and a platen 11. Here, the platen 11 is in contact with the paper 10 and receives pressure from the print head 2.

(2): Explanation of operation of printing apparatus When “medium with steps” is selected before printing, the paper thickness is measured after the paper is sucked. In this method, the thickness measuring roller is lightly pressed against the paper, and the carrier is moved in the paper width direction in this state. Along with this movement, the roller moves up and down in accordance with the thickness of the paper, and this vertical movement is converted into a gap value (the paper position and gap value are stored). Printing is performed while controlling the gap according to the paper thickness on the return path of the carrier.

  FIG. 3 is an explanatory diagram of the step measuring operation direction and the printing direction. In FIG. 3, the carrier moves left and right (reciprocates) for printing on the paper 10. For paper with no level difference, both the leftward movement and rightward movement (reciprocal movement) of the carrier 3 perform printing operations (printing on different lines when moving leftward and rightward). For the stepped paper 10, the gap measuring roller is lightly pressed against the paper 10 when the carrier 3 moves in the right direction (outward), and the thickness is detected over the entire width of the paper for each line. At that time, the roller pressing pressure and the carrier moving speed are optimized (the pressing force is changed according to the speed to prevent the copy paper and the like from being soiled) (step measurement operation of the paper 10). Next, printing is performed while the head gap is controlled to an appropriate value according to the thickness of the sheet by the leftward movement (return path) of the carrier (printing operation). In FIG. 3, the arrows for the paper level measurement operation direction and the printing operation direction are shifted up and down, but actually the paper level measurement and the printing operation are performed at the same place. Further, the reciprocating movement of the carrier may be reversed in the left-right direction (measuring the paper step by moving leftward and printing by moving right).

  FIG. 4 is a flowchart of the printing operation. Hereinafter, the printing operation will be described according to the processes S1 to S7 in FIG.

  S1: When the printer is turned on, the control unit 1 determines whether or not the step medium (paper) is printed. If it is determined that the step medium is printed, the process proceeds to step S2. If the step medium is not printed, the process proceeds to step S6.

  S2: When the step medium is selected on the operation panel (operation panel not shown), the control unit 1 proceeds to processing S3.

  S3: The control unit 1 activates printing of the step medium, and proceeds to processing S4.

  S4: The control unit 1 measures the level difference of the medium when the carrier 3 moves in the right direction (outward path), stores the measured position and level difference of the medium (storage unit 22), and proceeds to processing S5.

  S5: The control unit 1 performs printing of the medium while controlling the head gap to an appropriate value according to the level difference of the medium (storage unit 22) stored when the carrier 3 moves leftward (return), and performs one line (line) ) When finished, the process returns to step S4, and when all lines have been printed, this process is finished.

  S6: The control unit 1 performs normal printing activation, and proceeds to processing S7.

  S7: The control unit 1 executes the printing operation (to different lines) for both the rightward movement and the leftward movement (reciprocal movement) of the carrier 3, and ends this process.

  As described above, when the above method is employed, even if there is a step in the paper, the thickness can be measured correctly over the entire width of the paper, so that good print quality can be obtained. Also, since the roller pressing pressure can be set regardless of the printing speed, the paper is not soiled by the roller pressure.

It is explanatory drawing of the printing apparatus of this invention. It is side surface explanatory drawing of the printing apparatus of this invention. It is explanatory drawing of the level | step difference measurement operation direction and printing direction of this invention. 3 is a flowchart of a printing operation according to the present invention.

Explanation of symbols

1 Control unit (control means)
2 Print Head 3 Carrier 4 Guide Plate 5 Guide Shaft 6 Paper Pressing Roller (Roller)
7 Pressure spring 8 Gap sensor (medium thickness detection means)
9 Printhead height adjustment motor (gap adjustment means)
10 Paper (medium)
21 Paper Thickness Detection / Controller 22 Storage Unit (Storage Unit)

Claims (4)

A print head for printing on a medium;
Medium thickness detecting means for detecting the thickness of the medium;
A carrier that is mounted with the print head and the medium thickness detection means and reciprocates to print on the medium;
A gap adjusting means for adjusting a gap between the print head and the medium;
Storage means for storing information;
In a printing apparatus comprising a control means for controlling printing,
The control means detects the thickness by the medium thickness detection means over the entire width of the medium in the forward path of the carrier and stores it in the storage means, and stores the thickness by the gap adjustment means in the return path of the carrier. A printing method comprising printing on the medium while controlling the gap according to the thickness of the medium. A print head for printing on a medium;
Medium thickness detecting means for detecting the thickness of the medium;
A carrier that is mounted with the print head and the medium thickness detection means and reciprocates to print on the medium;
A gap adjusting means for adjusting a gap between the print head and the medium;
Storage means for storing information;
Control means for controlling printing,
The control means detects the thickness by the medium thickness detection means over the entire width of the medium in the forward path of the carrier and stores it in the storage means, and stores the thickness by the gap adjustment means in the return path of the carrier. A printing apparatus that performs printing on the medium while controlling the gap according to the thickness of the medium. The printing apparatus according to claim 2, wherein the medium thickness detecting unit detects a thickness of the medium by pressing a roller against the medium and above and below the roller. A setting means with or without a step of the medium is provided,
4. The printing apparatus according to claim 2, wherein the control unit performs printing on both the forward path and the return path of the carrier when there is no step in the medium.

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