JPH07148976A - Dot printing method and device - Google Patents

Abstract

PURPOSE: To provide a printer producing print results where no blank line is present between stripes printed with multiple dots. CONSTITUTION: A printer is fixed with a print head 1 combined with a moving member such that a relative movement takes place at least in one direction between the print head 1 and a document to be printed. The print head 1 includes a series of print members arranged at an interval of actual separation distance longer than a reference separation distance in the moving direction 10. Movement takes place at a pitch corresponding to the reference separation distance so that an overlap is ensured between continuous print stripes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus suitable for dot printing and especially for facsimile applications.

[0002]

2. Description of the Prior Art Dot printing devices are already known and are mounted on a dot print head, for example a carriage (movement table) associated with a drive member, in two substantially perpendicular directions of movement between the carriage and the document. And an ink jet print head for causing relative movement between the two. This type of head includes a series of printing nozzles arranged along a straight line or along rows and columns. The print nozzles are spaced from each other, and the print nozzles are
The movement of the print head in the first direction is arranged to print one swath made up of individual dots fired by the nozzles of the head when the nozzles of the head are made to print. There is. In this regard, it is recalled that the resolution of an ink jet printhead is defined by the number of dots printed per unit length in the direction of the printhead. The strip of consecutive points is moved by moving the printhead and the document in a second direction relative to each other, for example by advancing the document in a direction perpendicular to the carriage movement direction,
The number of strips required to scan the desired document type are determined sequentially.

Theoretically, the amount by which the document is advanced in the second direction is the size of the document in which successive strips make contact, ie the document is multiplied in that direction by the number of nozzles contained in the printhead. It is adapted to be advanced by an amount equal to the product of the distance between the nozzles in the direction of advance.

Unfortunately, due to varying amounts of mechanical play resulting from manufacturing tolerances of the parts that make up the carriage assembly, two adjacent printed strips do not always contact each other exactly. As a result, blank lines are formed between the strips, and it is said to be fictitious that the printed information does not include such blank lines at all. The higher the density of printing, the more visible this white line becomes, which greatly reduces the quality of the printed image, especially when the printed image is a realistic image.

In order to eliminate such "imaginary" blank lines from the document, for example, the strip is printed at a standard resolution (ie a resolution that theoretically guarantees that the strip will come into contact for a corresponding advance). To ensure that there is a small amount of overlap between successive print swaths by creating a relative movement between the document and the printhead at a pitch smaller than the pitch corresponding to the reference resolution. It is possible to However, since the number of swaths printed is determined regardless of how much the document advances, advancing at a pitch less than the pitch corresponding to the reference resolution will increase all successive swaths in the same direction and even more. It acts to bias in size, thus reducing the type of printed document.

[0006]

SUMMARY OF THE INVENTION According to the present invention, dot printing is performed at a resolution smaller than the reference resolution, and at a pitch that matches the reference pitch between the document and the print head. A printing method is provided that includes the step of maintaining relative movement.

The reduction in resolution associated with the corresponding enlargement of the size of the individual points thus enlarges each swath, which enlargement is evenly distributed throughout the document, which also causes the swath itself to be biased. It ensures a small amount of overlap between the strips without and without noticeably changing the model.

The invention further comprises a printhead associated with a moving member for providing relative movement in at least one direction of movement between the printhead and the document to be printed, the printhead having a reference spacing. A series of printing members spaced from each other in the direction of movement by an actual separation distance greater than the distance, the printing members being provided with print dots having an actual size greater than the reference size, the movement of which is relative to the reference size. (EN) Provided is a dot printing apparatus which is performed at a pitch corresponding to a separation distance.

[0009]

The features and advantages of the present invention will become apparent from the following description of specific non-limiting embodiments of the invention described with reference to the accompanying drawings.

Referring to FIG. 1, an ink jet print head 1 is carried by a carriage 2 that moves along a first direction, hereinafter referred to as the "horizontal direction". The carriage 2 slides along a guide 3 extending parallel to the horizontal direction. The movement of the carriage 2 along the guide 3 is under the control of the drive members 5 and 6. In the illustrated embodiment, the drive member comprises a belt 6 fixed to the carriage 2 and a motor 5 for driving the belt.

A document 8 to be printed, for example a sheet of paper, is supported by a support 7 against the printhead 1 by a drive from a drive means 9 in a second direction, which will be referred to below as the "vertical" direction. Moving. The drive member 9 comprises two rollers 11 between which the document is sandwiched. A drive motor 12 is provided on the roller located behind the document.

FIG. 2 is a magnified view of the face of the print head facing the document to be printed. Head 1
Is a nozzle 1 on a straight line that is inclined at an angle A with respect to the vertical direction so that a desired resolution can be obtained in the horizontal and vertical directions.
Have three. The vertical spacing d is the reciprocal of the resolution measured in said direction. This resolution corresponds to the large number of nozzles required to print individual dots that contact each other when adjacent nozzles are activated simultaneously for printing purposes.

Given reference resolution, eg vertical 1
At 0, 7.7 dots per millimeter corresponds to the given reference spacing, namely 0.1299 mm in this example. For a printhead with 64 nozzles, the corresponding fiducial advance for the document would have a fiducial pitch of 8.31 mm.

According to the present invention, the motor 12 is sequentially limited to advance the document by an amount equal to the reference pitch.
The vertical resolution of the print head is, for example, 7.6 per millimeter.
Changed to be smaller than the standard pitch of 5 dots,
As a result, the actual vertical separation distance d, which is larger than the reference separation distance, is 0.1307 mm in this embodiment.

Therefore, in the conventional device, the width of the strip is 8.31 mm, but in the case of the present invention a strip having a width of 8.36 mm is obtained, so that between two adjacent strips. You will be able to play 0.05mm.

FIG. 3 shows the dots (dots) that are theoretically in contact with each other.
Figure 4 is a cross-sectional view showing the result of printing four continuous strips of the figure, the left part of the figure shows the result obtained with a known ink jet print head, while the right part is according to the application of the invention. The results obtained are shown. In both cases the printing was done by an ink jet print head with 3 print nozzles.

In the left part of FIG. 3, the continuous strip is given the reference numeral 14 and the individual reference numerals 14.1, 14.2.
14.3 and 14.4 are attached. The individual dots are given the reference numeral 15, and these dots are shaded at different angles depending on the strip to which they belong. The individual dots 15 are printed by the print head at a reference resolution, and the advance of the document from one swath to another takes place at a pitch corresponding to said reference resolution. However, due to mechanical play in the carriage, the successive printed strips 14 do not always touch each other exactly at all times, so that for example between the strips 14.2 and 14.3 a "fictional" one is present. A white line 16 will appear.

In the right part of FIG. 3, the results of printing four consecutive document strips are shown in the same manner, but obtained using the method and apparatus of the present invention, The continuous strips are generally given the reference numeral 18 and the individual strips have the reference numerals 18.1, 18.2, 18.3, and 18.
4 is attached. The individual dots are numbered 17. The individual dots 17 are printed using a print head having a resolution smaller than the reference resolution and have actual dimensions larger than the reference dimensions of the dots 15. The pitch of the relative movement between the document and the print head is kept the same as the pitch of the relative movement corresponding to the reference resolution. This means that in the drawing, the center line of the strip 14 and the center line of the strip 18 coincide with each other as indicated by the chain line.

The printed strip 18 is wider than the strip 14 because the resolution is smaller than the reference resolution and the size of the individual dots is correspondingly increased, so that the strip 18.1.
A small amount of overlap 19 between strips 18.2 and 18.2 and between strips 18.3 and 18.4, while strip 1 again
The "imaginary" line 16 between 8.2 and 18.3 will not appear without causing a total transition of the strip. This increase in strip size means that the end strips are very slightly overextended. However, the increase brought to the size of the model is negligible in its very small size.

Naturally, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention defined in the claims.

In particular, while the printheads described above have nozzles in only a single column, printheads can include a set of nozzles arranged in rows and columns. It also provides a printhead with a large enough number of nozzles to simultaneously print an entire strip of individual dots so that the relative movement between the printhead and the document occurs in only one direction. It is also possible to do so.

Although the invention has been described above with reference to a resolution determined in the vertical direction, it can also be implemented with reference to a resolution in the horizontal direction.

Although the present invention has been described with reference to an ink jet printhead, it can also be implemented with any other dot printing device, and especially with a thermal printhead.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a printer having a carriage (moving table).

FIG. 2 is an enlarged view showing the side of the print head facing the document to be printed.

FIG. 3 compares the results of a document printed using known means with the results of the same document printed using the method and apparatus of the present invention.

[Explanation of symbols]

 1 ... Ink jet print head 2 ... Carriage 3 ... Guide 5 ... Motor 6 ... Belt 7 ... Support 8 ... Document 9 ... Driving member 10 ... Direction 11 ... Roller 12 ... Motor 13 ... Nozzle 14 ... Strip 15 ... Dot 16 ... White line 17 ... Dot 18 ... Band

Claims (2)

[Claims] 1. A method for printing a document (8) by means of a dot print head (1) comprising a series of printing members (13), wherein dots are printed sequentially, the document (8) and the print head (1). A method for printing with a dot print head, characterized in that dots are printed at a resolution smaller than the reference resolution, including the step of performing a relative movement between the reference resolution and the reference resolution. 2. A print head (1) in combination with a moving member (9) is mounted to effect relative movement in at least one movement direction (10) between the printing hand and the document to be printed (8). The dot printing device
The print head (1) comprises a series of printing members (13) spaced from each other by an actual separation distance in a movement direction (10) for printing dots having actual dimensions, the movement of which is Done at a pitch that corresponds to a reference separation distance associated with the reference size for the dots, and the dot printing apparatus is configured such that the actual separation distance and the actual dot size are greater than the reference separation distance and the reference size, respectively. Dot printing device characterized by