JP2010162695A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of uneven gradation caused by ruggedness of a printing medium. <P>SOLUTION: The inkjet printer includes: a printer head equipped with a plurality of piezo-elements; a roller for conveying a first printing medium that is an object to be printed actually; a detection part for detecting the ruggedness of the first printing medium; a non-volatile memory for storing correspondence relation between the ruggedness of a second printing medium which has been experimentally printed in advance and gradation when ejecting droplets ejected from the plurality of piezo-elements necessary to make the gradation after striking the droplets to the second printing medium having the ruggedness substantially equal to the original gradation; and a decision part for deciding the gradation when ejecting the droplets to the first printing medium by referring to the correspondence relation stored in the non-volatile memory based on the ruggedness of the first printing medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printing apparatus, and more particularly to an ink jet printer having a printer head including a plurality of piezo elements.

  In a “printing apparatus including a roller for transporting a printing medium (printing paper)” as described in Patent Document 1 below, as shown in FIG. 5, a plurality of piezo elements P10 constituting a print head H10. , P20,. . . . To droplets E10, E20,... Of the same size toward the printing paper PA10 conveyed by the rollers R10, R20. . . Printing is performed by discharging the ink.

JP 2005-178225 A

  However, in the conventional ink jet printer described above, as shown in FIG. 5, the printing paper PA10 is uneven due to the conveyance of the rollers R10 and R20, so that the droplets E10, E20,. . . Are the same size, droplets e10, e20,... After landing on the printing paper PA10. . . Have different sizes (areas viewed from the direction perpendicular to the printing surface of the printing paper PA10), and this causes a problem that the quality of printed characters and images is deteriorated, such as uneven gradation. .

  The present invention is realized by the following application examples in order to solve the above-described problems.

[Application Example 1]
The inkjet printer of Application Example 1
A printer head comprising a plurality of piezo elements;
A roller for conveying the first print medium that is actually the object to be printed;
A detector for detecting irregularities of the first print medium;
The original gradation of the unevenness of the second print medium experimentally printed in advance and the droplets ejected from the plurality of piezo elements after landing on the second print medium having the unevenness. A non-volatile memory for storing a correspondence relationship with the gradation at the time of ejection of the droplet, which is necessary to make the tone substantially equal to the tone;
A determining unit that determines a gradation at the time of ejection of a droplet ejected to the first print medium by referring to the correspondence stored in the nonvolatile memory based on the unevenness of the first print medium. And including.

  According to the ink jet printer of Application Example 1, the determination unit includes the unevenness of the second print medium experimentally printed in advance stored in the nonvolatile memory based on the unevenness of the first print medium. The liquid necessary for making the gradation of the droplets ejected from the plurality of piezoelectric elements after landing on the second print medium having the unevenness substantially equal to the original gradation Since the gradation of the droplet discharged onto the first print medium is determined by referring to the correspondence relationship with the gradation at the time of droplet ejection, after landing on the first print medium having the unevenness Can be made substantially equal to the original gradation.

[Application Example 2]
The inkjet printer of application example 2 is the inkjet printer of application example 1,
The nonvolatile memory is FeRAM.

  An ink jet printer according to an embodiment will be described with reference to the drawings.

<Constitution>
FIG. 1 shows a configuration of an inkjet printer according to an embodiment. As shown in FIG. 1, the inkjet printer IJP of the embodiment performs printing on a printing paper PA1 (shown in FIG. 2), as shown in FIG. Part D and nonvolatile memory F are included.

  As illustrated in FIG. 4, the print head H includes a plurality of (for example, five) piezoelectric elements P1 to P5 and nozzles NZ1 to NZ5.

  As shown in FIG. 4, the piezo element P1 ejects a droplet E1 from the nozzle NZ1 toward the printing paper PA1. Similarly, the other piezoelectric elements P2 to P5 discharge droplets E2 to E5 from the nozzles NZ2 to NZ5 toward the printing paper PA1.

  Returning to FIG. 1, the control unit C monitors and controls the overall operation of the inkjet printer IJP. In addition, the control unit C refers to the gradation data DT stored in the nonvolatile memory F based on the unevenness of the printing paper PA1, and determines the gradations of the droplets E1 to E5 at the time of ejection.

  As shown in FIG. 2, the paper feeding mechanism M includes a first roller R1 (feeding side) and a second roller R2 (feeding side) that cooperate to transport the printing paper PA1 in the paper feeding direction. Have. The printing paper PA1 is accurately conveyed due to a slight difference in paper feeding force between the first and second rollers R1 and R2 due to the conveying operation of the first roller R1 and the second roller R2. Depending on the material of the paper PA1 itself and the environment (temperature, humidity, etc.) in which the transported printing paper PA1 is placed, undulations (unevenness) occur as shown in FIG.

  As shown in FIG. 2, the position detection unit D is provided above the printing paper PA1 and includes a light emitting element LE and a light receiving element LR. The light emitting element LE is, for example, an LED, and emits light toward the printing paper PA1, and the light receiving element LR is, for example, a photodiode, and receives the light reflected by the printing paper PA1. Thereby, the position detection part D detects the unevenness | corrugation (height) of printing paper PA1.

  The nonvolatile memory F is, for example, EEROM or FeRAM, and stores the gradation data DT. As shown in FIG. 3, the gradation data DT is obtained by changing the height (unevenness) of the printing paper PA1 and the gradations of the droplets e1 to e5 after landing to an original gradation (an original gradation). In order to approach, the gradation at the time of ejection of the droplets E1 to E5 ejected toward the area (area A1 to A5 described later) of the printing paper PA1 at the height is defined.

  The gradation data DT stipulates that, for example, when the height of a certain area in the printing paper PA1 is “H1”, the gradation at the time of discharging a droplet discharged to the area should be “T1”. Further, it is defined that when the height of a certain area in the printing paper PA1 is “H2”, the gradation at the time of discharging the droplet discharged to the area should be “T2”.

<Operation>
The operation of the ink jet printer of the embodiment will be described. In the inkjet printer IJP, when the first roller R1 and the second roller R2 are transporting the printing paper PA1, the position detection unit D detects the height of the printing paper PA1. For example, as shown in FIG. 2, the heights (positions) of the areas A1, A2, A3, A4, and A5 of the printing paper PA1 are “H0”, “H2”, “H4”, “H3”, It is detected that it is “H1”.

  When the heights of the areas A1 to A5 of the printing paper PA1 are detected, the control unit C refers to the gradation data DT stored in the nonvolatile memory F and ejects droplets to the areas A1 to A5. The gradation at the time of discharging the power droplet is determined.

  More specifically, for example, since the height of the region A1 is “H0”, the control unit C sets the gradation at the time of ejection of the droplet ejected by the piezo element P1 corresponding to the region A to “T0”. Similarly, since the height of the region A2 is “H2”, the gradation at the time of discharging the droplets to be discharged by the piezo element P2 corresponding to the region A2 is set to “T2”. Decide what to do. In this way, as shown in FIG. 4, the control unit C generates gradations “T0”, “T2”, “T4”, “T3”, “T3” from each of the piezo elements P1 to P5. The droplets E1 to E5 which are “T1” are discharged. As a result, the gradation of the droplets e1 to e5 after landing on the printing paper PA1 is substantially equal to the original gradation.

<effect>
As described above, in the inkjet printer IJP of the embodiment, the control unit C uses the nonvolatile memory based on the heights of the areas A1 to A5 of the printing paper PA1 conveyed by the first roller R1 and the second roller R2. By referring to the gradation data DT stored in F, the gradation at the time of ejection of the droplets E1 to E5 to be ejected by the piezo elements P1 to P5 corresponding to the regions A1 to A5 is determined. As a result, the gradations of the droplets e1 to e5 after landing on the printing paper PA1 are substantially equal to the original gradations, and as a result, it is possible to avoid deterioration in image quality such as gradation unevenness. It becomes possible.

The structure of the inkjet printer of an Example is shown. FIG. 3 is a diagram illustrating a configuration of a print head according to an embodiment. The figure which shows the content of the gradation data of an Example. FIG. 4 is a diagram illustrating a printing operation by the piezo element according to the embodiment. The figure which shows the operation | movement of the printing by the conventional piezoelectric element.

  IJP ... Inkjet printer, H ... Print head, F ... Non-volatile memory, DT ... Gradation data, D ... Position detector, M ... Paper feed mechanism.

Claims (2)

A printer head comprising a plurality of piezo elements;
A roller for conveying the first print medium that is actually the object to be printed;
A detector for detecting irregularities of the first print medium;
The original gradation of the unevenness of the second print medium experimentally printed in advance and the droplets ejected from the plurality of piezo elements after landing on the second print medium having the unevenness. A non-volatile memory for storing a correspondence relationship with the gradation at the time of ejection of the droplet, which is necessary to make the tone substantially equal to the tone;
A determining unit that determines a gradation at the time of ejection of a droplet ejected to the first print medium by referring to the correspondence stored in the nonvolatile memory based on the unevenness of the first print medium. And an ink jet printer.   The inkjet printer according to claim 1, wherein the nonvolatile memory is FeRAM.

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