JP2006305894A - Method for correcting inclination of recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To grasp how large the installation position of a recording head is inclined to the installation position of another recording head adjoining it. <P>SOLUTION: A method for correcting the inclination of the first recording head 11 is applied when the image is recorded, in the case that an image is recorded by a line printer in which a plurality of recording heads 11-16 each being shorter than the recording width of the image are arranged by shifting them so that they do not overlap each other, and the installation position of the first recording head 11 is inclined to the installation position of the second recording head 12, is provided. In this method, first line groups L1, L1, ... with (N+1) pixel intervals are formed by the first recording head 11 around a reference line as a center, and second line groups L2, L2, ... with N pixel intervals are formed by the second recording head 12, and the number n of the pixels of inclination of the first recording head 11 is calculated in accordance with the number of lines to the line where the line L1 of the first line groups coincides with the line L2 of the second line groups from the reference line. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, when an image is recorded by a line printer in which a plurality of recording heads shorter than the recording width of the image are arranged so as not to overlap each other, the installation position of the first recording head is the first recording head. The recording head tilt correction method corrects the tilt of the first recording head when the image is recorded when the second recording head is tilted with respect to the installation position of the second recording head.

  A so-called “line printer” is a recording apparatus that records an image line by line (line), and can record at a higher speed than a “serial printer” that records an image dot by dot. Conventionally, it has been suitably used as a business recording apparatus. Specifically, the line printer has a configuration in which a long recording head (line head) along the width of the recording medium is fixedly arranged, and the recording medium passes directly below the recording head. A line head discharges ink toward the medium, and records an image on the recording medium line by line (see, for example, Patent Documents 1 and 2).

In the above line printer, since the quality of the image is deteriorated unless a large number of ink ejection sections (nozzles) are arranged accurately in the direction perpendicular to the conveyance direction of the recording medium over the entire width of the recording medium, the line head is manufactured. Is required to be accurate, and itself is very expensive and difficult to manufacture. For this reason, in recent years, line printers have been developed that have a structure in which a plurality of short recording heads are arranged in parallel along the width of the recording medium so as to be connected to each other, and correspond to one long line head ( For example, see Patent Document 3).
Japanese Patent Laid-Open No. 10-44474 JP-A-8-90837 JP 2002-103597 A

  However, in a line printer that corresponds to one line head with a plurality of short recording heads, although it is possible to eliminate the inconveniences related to the price of the line head and its production, as described in Patent Document 3, Depending on the installation state of the recording heads, the dot formation position may be shifted between the recording heads, and the image quality is degraded.

  This will be described in detail with reference to the installation example of the recording head shown in FIG. 8. As shown in FIG. 8, the recording head 100 has one end portion 100a fixed to an inverted U-shaped fixture 101 and the other end. The portion 100b is fixed to the second fixture 102 in a state where the spring (not shown) is pressed downward (not shown) (see the dotted line arrow in FIG. 8). There is some play between 100b and the second fixture 102, and by inserting an adjusting screw 103 between them, the installation position of the recording head 100 can be adjusted against the biasing force of the spring. ing.

In this case, one end 100a of the recording head 100 is completely fixed by the fixing device 101, but the other end 100b has some play between the second fixing device 102, and therefore the adjustment screw. Depending on the insertion degree (tightness) of 103, the installation position may be deviated from other recording heads 100. That is, when the adjustment screw 103 is tightened excessively, the recording head 100 has the other end portion 100b slightly inclined upward against the urging force of the spring, and conversely when the adjustment screw 103 is loosened too much. The recording head 100 is inclined slightly downward at the other end 100b due to the biasing force of the spring.

  Therefore, even if the installation position of the recording head 100 is set to a predetermined position, the recording head 100 is installed in a state where the one end portion 100a is a fulcrum and the other end portion 100b is slightly inclined on the order of several μm from the desired position. In many cases (see the solid line arrow in FIG. 8), if it is inclined, the amount of inclination is very small, and it is very difficult to accurately calculate the amount of inclination.

  When an image is recorded in a state where the installation position of the recording head 100 is inclined with respect to that of the other recording head 100, the dots formed by the recording head 100 are in a direction orthogonal to the conveyance direction of the recording medium. In contrast, an oblique line is formed, and an oblique line is also formed with respect to dots by other recording heads 100. In particular, when there is a shift of one pixel or more between other adjacent recording heads 100, the shift is reflected in the image to the extent that it can be visually recognized, leading to a reduction in image quality.

  An object of the present invention is to grasp how much an installation position of a recording head is inclined when an installation position of a certain recording head is inclined with respect to an installation position of another adjacent recording head. Another object of the present invention is to prevent the inclination of the installation position of the recording head from being reflected in the image quality in that case.

In order to solve the above problem, the invention according to claim 1
When an image is recorded by a line printer using a line head configured by shifting a plurality of recording heads shorter than the recording width of the image so as not to overlap each other, the installation position of the first recording head is An inclination correction method for a recording head that corrects the inclination of the first recording head when the image is recorded when it is inclined with respect to an installation position of a second recording head adjacent to the first recording head. ,
A first line group having an interval of (N + 1) pixels is formed by the first recording head around a reference line, and a second line group having an interval of N pixels is formed by the second recording head. The tilt number n of pixels of the first recording head is calculated according to the number of lines from the line to the line where the line of the first line group and the line of the second line group coincide. Yes.

The invention described in claim 2
In the recording head inclination correction method according to claim 1,
The ink ejection portion of the first recording head is divided into (n + 1) blocks with a value obtained by adding 1 to the number of inclined pixels n, and image data corresponding to each block is shifted at each block. The data is transferred to a block, and the tilt of the first recording head is corrected.

The invention according to claim 3
In the recording head inclination correction method according to claim 1,
Each of the plurality of recording heads is detachable from the line printer.

  According to the first aspect of the present invention, it is possible to grasp how much the installation position of the first recording head is inclined with respect to the installation position of the second recording head by the number of inclination pixels n.

According to the second aspect of the present invention, the inclination of the installation position of the first recording head relative to the installation position of the second recording head can be less than one pixel, and the inclination is reflected in the image quality. Can be suppressed.

  According to the third aspect of the present invention, it is possible to replace each recording head, and when there is a recording head that does not function normally among a plurality of recording heads, the recording head is appropriately used as another recording head. Can be exchanged.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for carrying out the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

  As shown in FIG. 1, the line printer 1 has a long line head unit 3 that extends along the width of the recording medium 2, and the recording medium 2 passes downward from the line head unit 3 so as to pass through the line head unit 3. It has the structure conveyed toward upper direction from. The line head unit 3 is configured on the assumption of recording on A4 paper having a width of about 210 mm, and six first to sixth recording heads 11 to 16 are installed on the object 4 to be installed. It has a configuration.

  The mounted body 4 is a member that allows the first to sixth recording heads 11 to 16 to be installed and supports the first to sixth recording heads 11 to 16, and is detachable from the main body of the line printer 1. It has become.

  Each of the first to sixth recording heads 11 to 16 is a member that ejects ink toward the recording medium 2 and is shorter than the recording width of the image. The first to sixth recording heads 11 to 16 are alternately arranged with respect to the imaginary line that crosses the central portion of the mounted body 4 in the left-right direction in FIG. 1, and zigzag in the direction along the width of the recording medium 2. Is arranged.

  The first to sixth recording heads 11 to 16 are detachably attached to the body 4 to be installed, and the other recording heads 11 to 16 of the same type are provided for each of the first to sixth recording heads 11 to 16. Can be exchanged for. Therefore, when there is a recording head (for example, the first recording head 11) that does not function normally among the first to sixth recording heads 11 to 16, the first recording head 11 is replaced with another one. One recording head 11 can be appropriately replaced.

  As shown in FIG. 2A, the first recording head 11 has 512 ink ejection portions 11a, 11a,... (Elements, nozzles). Each discharge unit 11a is configured on the assumption that an image having a resolution of 360 dpi (dot per inch) is recorded. Specifically, each discharge part 11a is arranged in a straight line with an equal interval of 70.6 μm, and the distance from the discharge part 11a at one end to the discharge part 11a at the other end is It is about 36 mm. Each ejection unit 11a is provided with one drive element (piezo element or the like), and when the drive element is driven, the ejection unit 11a corresponding to the drive element ejects ink as droplets. It has become.

The first recording head 11 having the above-described configuration is fixed to the installation body 4 with the same configuration as the recording head 100 described with reference to FIG. That is, in the first recording head 100, one end 11b is fixed to a fixture (not shown) corresponding to the fixture 101 in FIG. 8, and the other end 11c is biased by a spring in FIG. It is fixed to a second fixing tool (not shown) corresponding to the second fixing tool 102. As shown in FIG. 2B, there is play between the other end portion 11c and the second fixture so that the other end portion 11c can move within a range of about ± 300 μm at the maximum. While being received by an adjustment screw (not shown) corresponding to the adjustment screw 103 in FIG. 8, the position of the other end portion 11c is adjusted by the tightening degree.

  Although only the configuration of the first recording head 11 has been described in detail here, the other second to sixth recording heads 12 to 16 also differ from the first recording head 11 only in the reference numerals in FIG. It has the same configuration.

  As shown in FIG. 3, the line printer 1 is connected to a host computer 20 capable of controlling the line printer 1 through an interface 30. The interface 30 receives a control command for instructing execution of various processes from the host computer 20, image data of an image to be recorded on the recording medium 2, and the like.

  A CPU (Central Processing Unit) 31 and a memory controller 32 are connected to the interface 30, and the interface 30 distributes the control command and image data received from the host computer 20 to the CPU 31 and the memory controller 32, respectively. It has become.

  The CPU 31 receives the control command input via the interface 30 and controls the operation of each part of the line printer 1 based on the control command. In particular, the CPU 31 is connected to the memory controller 32 and causes the memory controller 32 to execute processes such as reading, rearranging, and transferring image data.

  The memory controller 32 is connected to an image memory 33 capable of storing the image data, and writes the image data input via the interface 30 into the image memory 33. The memory controller 32 is connected to the six first to sixth head drivers 41 to 46, receives an instruction signal (clock signal) from the CPU 31, reads out the image data from the image memory 33, and rearranges the arrangement. The changed image data is transferred to the first to sixth head drivers 41 to 46.

  The first to sixth head drivers 41 to 46 are for driving the drive elements of the first to sixth recording heads 11 to 16, and the first to sixth head drivers 41 to 46 include The first to sixth recording heads 11 to 16 are connected one by one.

  Specifically, the first head driver 41 is connected to each drive element of the first recording head 11, converts the image data transferred from the memory controller 32 into a signal for driving each drive element, and A signal is output to each driving element to drive each driving element.

  The second to sixth head drivers 42 to 46 also operate in the same manner as the first head driver 41 performs on each drive element of the first recording head 11, and the second to sixth recording heads. Each of the drive elements 12 to 16 is driven. In FIG. 3, the third, fourth, and fifth head drivers 43, 44, and 45 and the third, fourth, and fifth recording heads 13, 14 are simplified to simplify the description in the drawing. 15 are omitted.

  Next, the “recording head tilt correction method” according to the present invention will be described.

As described above, the first recording head 11 is configured such that the position of the other end portion 11c is adjusted by the tightening degree while receiving the biasing force of the spring with the adjusting screw. The other end portion 11c may be displaced forward and backward in the direction along the conveyance direction of the recording medium 2 with respect to the one end portion 12b of the second recording head 12 (see FIGS. 2B and 4). When the image is recorded, the deviation may be reflected to the extent that the image can be visually recognized.

  Therefore, prior to image recording, first, a test chart as shown in FIG. 4 is created, and how much the installation position of the first recording head 11 is inclined with respect to that of the second recording head 12 is calculated. (Inclination amount calculation step). That is, a predetermined line of the recording medium 2 is set as a reference line (see a two-dot chain line in FIG. 4), and a plurality of lines L1, L1,. Are recorded to form a first line group, and a plurality of lines L2, L2,... Are recorded at intervals of N pixels by the second recording head 12 to form a second line group.

  In this case, as shown in FIG. 4, when the line L1 of the first line group and the line L2 of the second line group match at the reference line (position "0"), the first recording head 11 can be determined not to be inclined with respect to that of the second recording head 12.

  On the other hand, as shown in FIG. 5A, when the line L1 of the first line group and the line L2 of the second line group coincide with each other at a position away from the reference line, the first recording head. 11 can be determined to be inclined with respect to that of the second recording head 12.

  For example, as shown in FIG. 5A, the line L1 of the first line group and the line L2 of the second line group match at a position away from the reference line, and the matched lines L1, L2 from the reference line. When the number of lines up to “2” is reached, as shown in FIG. 5B, the end of the line L1 is shifted by 2 pixels from the end of the line L2, and the first recording head 11 can be determined to be inclined by two pixels with respect to that of the second recording head 12.

  Through the above processing of the tilt amount calculation step, the tilt amount of the installation position of the first recording head 11 with respect to the second recording head 12 can be calculated as “the number of tilt pixels n”. To what extent the installation position is inclined with respect to that of the second recording head 12 can be grasped by “inclination pixel number n”.

  When recording an image, 512 ejection units 11a, 11a,... Are divided into (n + 1) blocks with a value obtained by adding 1 to the number of tilt pixels n calculated in the tilt amount calculation step, and each block The timing of reading, rearranging, and transferring image data corresponding to is shifted by one pixel for each block (accelerated by one pixel for each block along the direction from one end 11b to the other end 11c). The inclination of the installation position of the first recording head 11 is corrected (inclination correction step).

  For example, when the installation position of the first recording head 11 is inclined by “2 pixels” as shown in FIG. 6A with respect to that of the second recording head 12, first, FIG. As shown, these 512 ejection sections 11a, 11a,... Are divided into 3 (= 2 + 1) blocks. Here, 512 discharge units 11a, 11a,... Are divided into a first block B1 including 170 discharge units 11a, 11a,... And a second block including 171 discharge units 11a, 11a,. It divides | segments into B2 and 3rd block B3 which consists of 171 discharge parts 11a, 11a, ....

  After that, among the image data of the image to be recorded by the first recording head 11, the image data corresponding to the second block B2 is one pixel more than the image data corresponding to the first block B1. The image data corresponding to the third block B3 is read one pixel earlier than the image data corresponding to the second block B2.

  In the circuit configuration of the line printer 1, the memory controller 32 usually reads out the image data corresponding to the first recording head 11 from the image memory 33 and rearranges them in synchronization with the instruction signal (clock signal) of the CPU 31. The data is transferred to the first head driver 41. Here, the CPU 31 controls the memory controller 32, and the memory controller 32 corresponds to the second block B2 as shown in FIG. The image data is read one pixel earlier than the image data corresponding to the first block B1, and the image data corresponding to the third block B3 is read out as much as the image corresponding to the first block B1. Read out two pixels earlier than the data, and keep the read timing in phase with the first through third blocks B1 through B3. It adapted to forward to the first head driver 41 rearranges the image data to be.

  By the above tilt correction process, the installation positions of the first to third blocks B1 to B3 are tilted by 2/3 pixels with respect to that of the second recording head 12, as shown in FIG. 6C. Thus, the inclination amount of the installation position of the first recording head 11 can be corrected so as to be suppressed from 2 pixels to 2/3 pixels less than 1 pixel. Therefore, the inclination of the installation position of the first recording head 11 with respect to the installation position of the second recording head 12 can be prevented from being reflected in the image quality, and the image quality can be improved.

  In the tilt amount calculating step and the tilt correcting step, a method of calculating the tilt amount of the installation position of the first recording head 11 with respect to the second recording head 12 and the tilt with respect to the second recording head 12 are used. Although the correction method has been described, the calculation of the inclination amount of the installation positions of the other second to fifth recording heads 12 to 15 and the correction thereof are also arranged on the right side of the recording heads 12 to 15 in FIG. The recording heads 13 to 16 can be used in the same manner as described above.

The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
For example, in the above embodiment, assuming standard image recording, A4 paper is applied as the recording medium 2, and the first to sixth recording heads 11 to 6 are used as recording heads corresponding to known line heads. 16 is applied, but the size and type of the recording medium 2 may be changed as appropriate, the number of the first to sixth recording heads 11 to 16 and the ejection portions 11a, 11a,. The number of ..., the interval (pitch), etc. may be changed as appropriate.

1 is a plan view showing a schematic configuration of a line printer 1. FIG. 2 is a plan view showing a schematic configuration of a first recording head 11. FIG. 2 is a block diagram illustrating a circuit configuration of the line printer 1. FIG. 4 is a diagram illustrating an example of a state where the installation position of the first recording head 11 is not inclined with respect to that of the second recording head 12. 4 is a diagram illustrating an example of a state in which the installation position of the first recording head 11 is inclined with respect to that of the second recording head 12. 4 is a diagram illustrating a method for correcting the inclination of the installation position of the first recording head 11. 4 is a timing chart showing timings of reading image data corresponding to first to third blocks B to B3 with respect to a clock signal of a CPU 31. FIG. 6 is a plan view illustrating an installation example of a conventional recording head 100.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Line printer 2 Recording medium 3 Line head unit 4 Installation object 11 1st recording head 11a Discharge part 12 2nd recording heads 13-16 The 3rd-6th recording head 20 Host computer 30 Interface 31 CPU
32 memory controller 33 image memory 41 first head drivers 42 to 46 second to sixth head drivers

Claims (3)

In the case where an image is recorded by a line printer using a line head configured by shifting a plurality of recording heads shorter than the image recording width so as not to overlap each other, the installation position of the first recording head is An inclination correction method for a recording head that corrects the inclination of the first recording head when the image is recorded when it is inclined with respect to an installation position of a second recording head adjacent to the first recording head. ,
A first line group having an interval of (N + 1) pixels is formed by the first recording head around a reference line, and a second line group having an interval of N pixels is formed by the second recording head. The number n of inclined pixels of the first recording head is calculated according to the number of lines from the line to the line where the line of the first line group and the line of the second line group coincide with each other. To correct the tilt of the recording head. In the recording head inclination correction method according to claim 1,
The ink ejection portion of the first recording head is divided into (n + 1) blocks with a value obtained by adding 1 to the number of inclined pixels n, and image data corresponding to each block is shifted at each block. A method of correcting the tilt of the recording head, wherein the tilt of the first recording head is corrected by transferring to a block. In the recording head inclination correction method according to claim 1,
A method of correcting a tilt of a recording head, wherein each of the plurality of recording heads is detachable from the line printer.

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