JPS6124370A - Area gradation recording method - Google Patents

Abstract

PURPOSE:To increase the number of gradation levels without decreasing the resolution by shifting a thermal head by nearly 1/2 of horizontal elements of a matrix to form a coloring section. CONSTITUTION:In applying gradation recording to picture elements of 4X4 matrix constitution with a 4 column X 4 row serial thermal head, the heat resistive element of the 1st row and the 1st column is energized to obtain a density pattern of the gradation level 1 as shown in figure (a). After the forming of the pattern, the thermal head is moved horizontally by 1/2 pitch and the heat resistive element of the 1st row and the 1st column is energized to obtain the density pattern of the gradation level 2 as shown in figure (b). In obtaining a level larger than the gradation level 2 by a minimum level width, the gradation level 3 as shown in figure (c) is obtained by energizing each heat resistive element of the 1st row and 1st column and the 3rd row and 3rd column. Thus, the area of the ink dot in the density pattern shown in figure (b) is 1.5S, where S is the area of one dot, and a middle value between 1S in the figure (a) and 2S in figure (c) is obtained.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an area gradation recording method that can improve image quality by increasing the number of gradation levels without reducing resolution. Ru.

[Technical background of the invention and its problems] In recent years, the information-related industry has made remarkable progress, and along with this, there has been a need for blinkers for recording characters, figures, etc. on recording paper. As the printer in this case, a thermofusion type thermal recording type printer is widely used.

The heat-melting type thermal recording method described above overlaps recording paper with ink sheet 1-, which is made by applying heat-melting solid ink on the surface of paper or non-nos book film, etc., and presses it using a thermal head. The solid inks of ink sheets 1 to 10 are melted by heating and transferred to recording paper. This recording method is a non-inbound one-way system, so it does not generate noise, has a fast recording speed, and has the advantages of
It is possible to obtain high resolution horns, there is no need to worry about problems caused by clogging of the recording head as with the inkjet recording type 1 type, and there is almost no need for maintenance. Because it can be used, it has good light fastness and storage stability, and it is easy to record in color by using a color ink sheet with three colors of yellow, magenta, and cyan, and by overcoating each color. It has many advantages as a printer, including the ability to However, on the other hand, there is a drawback that the recording density cannot be controlled by changing the amount of heat generated by changing the power applied to the thermal head and by changing the amount of ink transferred to the recording paper. (For example, it is not possible to reduce the amount of ink transferred by half and record at half the recording density of the recording density at the time of transfer.) In other words, thermal melting RR thermal transfer recording 1/j The formula can only perform either no ink transfer or ink ω transfer2 (
It is an ICi recording type. Therefore, it is not possible to record halftone image quality with great shading as it is.

Therefore, a gradation recording method called the density pattern method, which is a type of area gradation method, is used for recording halftone images using a heat-fusion type thermal transfer recording method. Density pattern expansion is done by associating one pixel with a matrix consisting of several elements, and changing the number of matrix elements to be filled by transferring ink according to the density of the pixel. The ink inside is transferred to l [by changing the area of the colored part, δ
This is a way to express 13th tan.

This gradation recording method is convenient because it allows conventional binary recording type ink sheets to be used as is and can be applied to color gradation recording as well as monochrome recording.

FIG. 8 shows a density pattern in which one pixel is divided into 71 pixels (4×4) and the density of each pixel is expressed in gradation levels from 0 to 16 levels. In the same figure, there are various types of arrangement of 71~lix elements which are colored by C1 transfer.

However, in this method, the number of gradations is limited to one by the number of elements from 71 to The disadvantage is that the resolution decreases.

Incidentally, as a conventional example related to the present invention, a print head driving system is disclosed in Japanese Patent Application Laid-Open No. 50-99746. This uses n×m recording elements vertically and horizontally.
It records information such as characters, and its resolution is limited by the number of elements (n x m), so by moving the print head by 1/2 the pitch and printing again, the actual information can be recorded. Although this method achieves closer resolution, it does not improve the number of gradations and does not solve the problem of recording halftone images with shading.

[Objective of the Invention 1] The present invention has been made in view of the above-mentioned points, and it is possible to significantly increase the number of gradation levels without reducing resolution by using a matrix of the same size as the conventional density pattern method. to reproduce the shading more faithfully.
! 1] Our aim is to provide an i-key recording method.

[Requirements of the Invention] The present invention is a heat-melting type thermal transfer recording method that uses a matrix consisting of one element and changes the number of colored elements depending on the density of each pixel. In the area gradation recording method such as 4-Jlf C recording, which is 1/2 of the pitch of the matrix elements in the horizontal direction, the area of 1/2 of the colored element to be transferred is transferred and colored before being shifted. In this way, the number of gradations can be significantly increased without increasing the number of 71-lix elements.

[Embodiments of the invention] Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIGS. 1 to 5 relate to the first embodiment of the present invention.
The figure shows a density pattern of 0 to 31 gradations that can be realized with a 4 x 4 matrix according to the first embodiment, Fig. 2 shows a recording system using a serial type thermal head, and Fig. 3 shows a density pattern of 1 column x 4 rows. Showing a serial type thermal head, the fourth
The figure shows a printing example (a) when the "S"-Mul head shown in Fig. 3 is fed at a pitch of 1 dot, and an example printing (b) when it is fed at a pitch of 1/2 dot. The figure shows a pattern in which the gradation of one pixel is expressed using a 4×4 matrix according to the method of the present invention.

In the first embodiment, one pixel is divided into nodes 1 and 1 in a 4×4 matrix.
It turns out that J, C1 is O as shown in Figure 1.633
Regarding the method for realizing halftone recording up to the first floor density J (
state

First, the gradation recording method according to the present invention is carried out using a 1) -maru head and a full type b, and the construction of the recording system in that case is shown in Fig. 2.

In the same figure, there is A3, serial type Nermal Hetsu 1': 1 cry,
For example, in order to simplify the explanation, it will be assumed for a moment that the heating resistor cables 2 are arranged in one column by four rows as shown in FIG. Each heating resistor cord 2- is regularly arranged at a predetermined pitch d so close that it almost overlaps with the adjacent one.

The horizontal scanning direction of this thermal head 1 is along the arrow A, and the line feeding direction (paper feeding) is along the arrow B.

The four normal heads 1 are pressed onto a platen roller (not shown) on which a recording paper 3 and an ink sheet 4 are stacked, and in this case, the heating resistive elements 2. . . , 2 generate heat by being selectively energized in a pulsed manner depending on the density of pixels of recorded information. Due to this heat generation, the ink of the ink sheet 1-4 in the part where the heating resistor cable 2 is pressed is melted.
The molten ink will be transferred to the recording paper 3. Therefore, the thermal head 1 is 1 pitch d in the horizontal direction.
4, and is similarly selectively energized to transfer the ink on the ink sheet 4. When one normal head 1 of 1 column x 4 rows is used, a melon pattern for 1 pixel is formed with 4 x 4 71 ~ ricks. When covering, in the conventional example, the thermal head 1 is moved horizontally four times. It will be scanned.

For example, heating resistor element 2 of thermal head 1 in 1 column x 4 rows
．． 2. When all of 2.2 are energized, the ink is thermally transferred by scanning roughly 1 pip d in the horizontal direction and energizing only the uppermost heating resistor element 2, the ink is thermally transferred, as shown in Fig. 4 (a). Insid dots 1 to 5 (colored dots) are placed on the recording paper 3 in the area corresponding to the area where heat is generated. ..., 5 are formed.

By the way, in the present invention, in order to further increase the number of gradations, in addition to scanning in the horizontal direction by 1 pip d and covering C thermal transfer according to the density of the pixel, the scanning is performed by scanning 1/2 of 1 pip d in the horizontal direction.
The thermal transfer is carried out by shifting the multi-head 1. For example, Fig. 4(a) corresponds to an rAi degree pattern with a gradation level of 5, but if the gradation level is increased by the minimum level width T, (in the conventional example) 1 dot 1 Although the gradation level is 4, which is less than the area of
Since the water is shifted in the horizontal direction and thermal transfer is performed by applying electricity in the same way, as shown in FIG. Now you can get it.

When the heating resistor element 2 at the top is energized by shifting the above 1/2 pitch d/2 in the horizontal direction, the left half of the heating resistor cable 2 becomes east of the ink sheet part before shifting by 1/2 pitch (this The ink on the left half (because it has been transferred at the end and there is no more transferable ink) is not transferred, and the ink on the right half of the ink sheet that has not been transferred is melted, as shown in Figure 4. As shown in (b), it is possible to realize a gradation level that is 1/2 of the minimum gradation level width (color area area corresponding to one dot) of the conventional example.

The above description has been simplified using a 1-column x 4-row thermal head 1, and next, a case will be described in which gradation recording is performed using a 4-column x 4-row thermal head.

For example, if the heating resistor elements in the first row and first column of a 4×4 thermal head are energized and the ink is heated 7 times, the fifth
As shown in the figure <-a, >, a Fuchimaro pattern of gradation level 1 can be obtained. This gradation level has a slightly higher density than gradation level 1 (the gradation level is changed to 2)
To obtain the density pattern represented by
Move 2 bits/straddle horizontally and read the first line above.
By energizing the heating resistive elements in the first row, a density pattern of gradation level 2 as shown in FIG. 5(b) can be obtained. Next, in order to obtain a gradation level larger than the gradation level 2 by the minimum level width, the first row, the first column, the third row,
By energizing each heating resistor element in the third row,
, gradation level 3 b as shown in FIG. 5(C) can be performed.

The J'-Fee pattern shown in Figure 5(b) is 1/2 bit d/2 after the ink is thermally transferred by the heating resistor elements in the first row and first column. Ink is thermally transferred by energizing the heating resistive elements in the first row and first column of the four shifted normal heads. Since there is no ink to be transferred to the left half of the ink sheet portion heated and pressed by the first row of heating resistive elements, only the ink of the right half is thermally transferred. Therefore, the area of one portion of ink 1:T1 falling into the density pattern shown in FIG. 5 ([)) is the surface of one dot! (If - is written as S, it becomes 1.58, Figure 5 (a)
lS', 28 intermediate values in lri diagram (c) are obtained.

It is possible to form a Fuchimaro pattern with successively larger gradation levels by using ``,'', and ``) as described in ``,'' and ``,'', which is similar to the conventional 1 shown in Fig. 8.
By interpolating the 15 gradations in b of 6 gradations, we can create a density pattern with a large number of gradation levels of 31 gradations, as shown in Figure 1 (r). By recording one character figure using this 8-degree pattern, it is possible to reproduce one degree of each pixel of that figure much more faithfully than before.

In addition, it is 1/2 pitch d/2 [1/2 when tilted horizontally]
/ When forming a colored dot of 2 dots, its formation position is as follows:
The invention is not limited to what is shown in FIG. 1, but may be applied anywhere as long as it is applied to the boundary between a colored part of one dot and an uncolored part on the left or right side. In addition, 4 columns x 4
In the same way, (-1) can be obtained for a thermal head with 1 column x 4 rows instead of a row thermal head.

By the way, in the above description, a 4×4 matrix with one pixel is explained, but the present invention can generally be applied to a matrix of size n×.

As described above, the first embodiment has the advantage that the number of gradation levels can be approximately doubled compared to the conventional example without reducing the resolution, and the quality of gradation recording can be greatly improved.

Figure 116 shows the second embodiment of the present technology (chicken! 1-gradation recording/j method (51 used) edge threads.

° In this second embodiment (in 13, the predetermined pitch d
Then, (in the line feed direction [3 do white text Jru), heat generation 1 in a horizontal direction in the form of a line] (resistance line A 2..., 2 is arranged and formed -1 ta 1 nonru l\tsuF' Density .12 is arranged in two stages.

Therefore, the heat generating resistor elements 2, .
2 array pip d (or 1 pixel width in the line feed direction (for example, 4 pitches in a 4x4 matrix). (There is no limitation to this.) ) However, the recording paper 3 stacked on the platen roller 3
From the top of the ink sheet 4, the first line of pixels is first printed at the first thermal density according to the density of the pixels, and then the second, third, and fourth lines are printed in order. For example, as shown in FIG. 8, [
For example, the seventh
As shown in Figure (a), gradation levels 3, 4, etc. are printed in a line (from the conventional level display) (Print 1
−) to be done.

In this way, the first normal head density is printed one after another in a line. - On the other hand, each line-shaped pixel 71-lix printed in the above 16 gradations is processed by the second thermal head 12, and for those that require interpolation, The heating resistor element 2 is printed in half shape in the horizontal direction, and for example, as shown in FIG. 7(b), the gradation level 3 is 3.5 (the level display in FIG. 1 is 6), the gradation level of 4 is changed to 4.5 (8 in the level display of FIG. 1), and a more faithful gradation level is recorded.

In this way, according to the second embodiment, two thermal head densities 12 are provided, shifted by 1/2 pitch in the horizontal direction,
Print with the first thermal head density while performing normal line feed, and for the 71 to 6th density that requires interpolation, use the second thermal head 12 to perform interpolation without reducing the print speed. can.

In the second embodiment described above, each of the two normal head concentrations.
12, heating element elements 2. ....

However, if two sets of rows each having a row of one pixel are arranged in a line, the printing speed can be further improved.

Furthermore, if a printer in which more lines than one pixel are arranged in a line (for example, a line printer) is used, the printing speed can be further improved.

In addition, as the second thermal head for the gradation level supplementary device, one line is sufficient in any of the above cases, and when the second thermal head reaches the line where interpolation is required, All you have to do is make it work.

Furthermore, by doing the following, it is possible to function for 11 minutes by simply installing one thermal head for gradation level interpolation for one pixel.

The pudding pattern for printing with the first thermal head is different from the one shown in Figure 8 so that it does not splatter, and interpolation is required. (Of course, the printing is done by shifting 1/2 pitch and printing so that half overlaps.) If this shift is made in the J direction, the structure of the second thermal head for interpolation will be simple.

In the case of a single thermal head formed by arranging a single or Fi number of heating resistive elements in a line, first print as in the conventional example, and then print the thermal head horizontally by 1/2. You can use the printer to interpolate the gradation level by shifting it by 2 pips.

The present invention is widely applicable to area gradation recording methods in which one pixel is constituted by a matrix having n×m (n, m: natural numbers) elements in the vertical and horizontal directions.

Incidentally, when recording by shifting 1/2 pitch, the recording paper side may be shifted instead of the recording head side.

In addition, the present invention can be used in the case of color rather than monochrome.
Using an ink sheet with three types of ink (yellow, magenta, and cyan), two or three colors of ink are placed on the recording paper and transferred to record the desired color. You can print with . Incidentally, Inksey 1-whatever, 3
It's not limited to colored ones, it's also good to have four kinds of Shinode, including black ones.

Furthermore, the present invention can be applied to area gradation recording using six impact dots. In this case, 1 horizontally
By recording with a shift of /2 pitches, the result is a shift of 1 pitch in the uncolored area - (1 of the area of the formed shield colored part)
/2 and six color parts can be formed.

In addition, forming and covering the colored part by 1/2 pitch in the horizontal lj direction (including density, 3/'2 and 5./2 pitch tongue shift J) [Effects of the invention 1 hereafter J- According to the present invention, according to the density of each pixel, the area of the color part is changed to a matrix of ('n In this method, the pitch of the matrix elements formed in the horizontal direction is shifted by 1./2, and the transfer recording is performed, so the minimum gradation level width is set to 1/2 of the pitch of the conventional method.
The number of gradation levels can be reduced to approximately 2 to 8 without reducing resolution, and the density can be reproduced with J or more faithful gradations.

[Brief explanation of the drawing]

Figures 1 to 5 show a first embodiment of the present invention, and Figure 1 is a diagram showing a 31-gradation pattern that can be realized with 7 4 x 4 tricks according to the present invention. FIG. 2 is a perspective view showing the outline of the recording system used in the first embodiment, FIG.
The figure shows the dot pattern when recording with the 4 normal heads in Figure 3, Figure 5 shows the recording pattern when one pixel is displayed in a 4 x 4 matrix, Figures 6 and 7 The figure relates to the second embodiment of the present invention, and is shown in Fig. 6 (E'').
is an explanatory diagram showing how two thermal heads are arranged in a line (-density 5), and the same figure (b) is the same figure (
Fig. 7 (a) is a side view of Fig. 7 (a) showing the recording pattern transferred and recorded by the first thermal head in Fig. 6, and Fig. 7 (b) is a side view of the case where the recording pattern is further transferred and recorded by the second one normal head. Figure 8 shows the recording pattern of J[
) is a diagram showing a pattern for gradation recording. 1. concentration. 12...Remal head 2...Heating resistance element 3...Recording paper 4...
Ink sheet 13...Brain opening - Figure 1

Claims (1)

[Claims] In an area gradation recording method in which the number of colored elements in a matrix consisting of n×m elements is recorded in correspondence with the density of each pixel, gradation is recorded by the area of the colored part according to the density. . An area gradation recording method, characterized in that the number of gradation levels can be increased by forming colored portions shifted by approximately 1/2 of the pitch between elements in the horizontal direction of the matrix.