JPS59132280A - Picture recorder with gradation - Google Patents

Abstract

PURPOSE:To form nearly stepwise an average reflecting density per unit area by expressing the gradation taking the number of dots written in the unit area and an area where dots are overlapped into consideration. CONSTITUTION:As the method to express the gradation, the gradation pattern is formed by taking the number of dots written in the unit area and the degree of overlapping among dots depending on the arrangement of dots, i.e., the overlapped area into consideration. For example, two dots S0 are used so as to form the overlapped area to be S1 or S2. Further, three dots are used to form the overlapped area S3. The average reflecting density per unit area is formed nearly stepwise by expressing the gradation in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gradation image recording device, and in particular, the number of dots to be written in a pixel ζ constituted by a unit area constituted by a plurality of dot writing positions. The present invention relates to a gradation control method that changes the average reflection density of a pixel (this is referred to as pixel density) by changing the pixel density or arrangement.

(Prior art) In the conventional gradation control method, a certain area is allocated as the area of the recording part to each stage ζ of the gradation of a pixel, the number of dots that satisfy this area is found, and this number is calculated. The gradation was determined by recording the dots.

In this method, the unit of change in the recorded area in one pixel is the area of one dot.Due to the arrangement of the dots, the dots may overlap, and there is no known processing method for this case. Therefore, it is not possible to minutely control the area of the recorded area in response to changes in gradation, and the area of the recorded area for each pixel may result in an error due to overlapping dots. was there.

(Purpose and Features) In view of the above, the purpose of the present invention is to sequentially increase the number of written dots in order to express gradation density by taking into account the area of the overlap between the dots written in the unit area. To provide an apparatus that improves the gradation of a recorded image by controlling the area of a recording part within one pixel that forms multiple gradations by selecting the writing position of the next dot to be increased. In order to achieve the above object, the features of the present invention include means for generating recording dots, scanning means for positioning and recording the dots at specific positions, and scanning means for positioning and recording the dots at specific positions. In the gradation image recording apparatus, the gradation image recording apparatus has a selection control means for a recording pattern and gradation pattern to be selectively recorded, and one multi-gradation pixel is constituted by a unit area in which a plurality of the dots can be written. As a method of expressing gradation, a gradation pattern is formed by taking into account the number of dots written in the above unit area and the overlap between dots that differs depending on the placement position of the dots. This means that the average reflection density of the object is formed almost stepwise.

(Example) Fig. 1 is a conceptual diagram of the present invention, and Figs. 2 and 3 are explanatory diagrams of an embodiment of the present invention. This is to explain the overlapping combination of pixels and writing positions (dots).

In the figure, A is a main scanning means for main-scanning the inkjet particle generating head 1, B is a sub-scanning means for sub-scanning by moving the recording paper 6, which is a medium, and C is a selective control of the piezoelectric element 2. The recording pattern control means includes a gradation pattern selection means for generating ink particles 5 and recording dots on the recording paper 6. Although not particularly shown, these are under the control of the interlocking control section of the apparatus and select the gradation to be received. It is assumed that the controller is controlled so that a multi-gradation recording pattern is output even when the pixel pattern signal is busy.

In the figure, 3 is the ink chamber, 4 is the nozzle, 7 is the recorded dot, 8 is one of the pixels consisting of the writing position of the subnumber, and the subdivision in the pixel is for filling the dot 7. , and its center point is the dot 7 to be written for recording.
This is the center of allocation for allocating the area to the above-mentioned small area.

The present invention will be described in detail using a drop-on-demand pressure-controlled inkjet printer having such a configuration as an example.

In FIG. 1, a pressure wave is generated by applying an electric signal to a piezoelectric element 2 provided in a particle generation head 1. This pressure wave compresses the ink in the pressure chamber 3,
As a result, the ink particles 5 are ejected through the nozzle hole 4.

The ink particles 5 collide with the surface of the recording paper 6 and are fixed thereon.

Since the recording paper 6 moves in a direction perpendicular to the scanning direction of the particle generating head 1, an image made up of ink dots 71 is recorded on the surface of the recording paper 6. Further, when performing color recording, nozzle holes 4 are assigned to each primary color.

In the inkjet recording method, the amount of ink in one ink droplet 5 is constant. Therefore, the gradation is expressed by the number of dots 7 in the pixel 8.

In this embodiment, a pixel 8 as shown in FIG. 2 is used.

The ink droplet 5 collides with the center 9 of the recording device, forming a dot 7.
, and its size is larger than the distance between the center portions 9. (In this example, the diameter of the dots is approximately 1.6 times the center distance.) At this time, when recording two or more ink particles 5, it is possible to create areas where the dots overlap by arranging the dots 7. can. If the number of dots recorded in one pixel is defined as a gradation level, 17 gradations from 0 to 16 can be expressed in this embodiment.

For example, the recording pattern B in a pixel when the gradation level is 2 is shown by solid line dots 14° and 15 in FIG.

Stage 3, which is one gray scale step higher than 2, is obtained by recording one more dot in the stage 2 pixel. At this time, if this one dot is recorded at the recording position 10 or IN, the area occupied by the dot in one pixel will increase by 9,000,000 yen, so the pixel density will be higher than the desired pixel density representing gradation level 3. It's too expensive.

Therefore, it is necessary to record at recording position 12 or 13.
Create a dot area where the dot overlaps with Koyoshi dot 14 or 15. By changing the recording position of the dots, it is possible to change the area of the overlapped portion of the dots, so that it is possible to represent gradation stage 3, which is very close to the desired pixel density t.

As an example, FIG. 2 specifically shows the effects of the present invention when cyan ink is used in the pixel configuration shown in FIG.

In addition, the density Da of the dot part, one pixel l of the dot part
In contrast, the pixel density when the area occupation rate is a is defined as the pixel density.

D= -tOgio (1-a (1-i 0-DI+
))=(1) Note that FIGS. 4(A) and (B) are detailed explanatory diagrams of the present invention, and FIG. 4(A) shows where to place a dot in one pixel of multi-gradation according to the principle of the present invention. 1 to record the distribution of
For example, FIG. 4(B) shows an example in which dots are mechanically distributed continuously from the chopsticks as a counter-sho group.

In addition, in FIG. 4(A) and FIG. 4(B), regarding the area occupied by a dot in one pixel, the area shifted compared to the number of constituent dots installed is summarized for the embodiment and the conventional example. What is shown is Table 1.

Figure 5 (A) shows the details of the crushed area for each number of dots on the example side of Table 1.
The suffixes (1) to (16) in (B) indicate the number of constituent dots. Figure 6 is a supplementary figure to Table 1 or Figure 5 that shows the area of overlapping squares or dots used as the basic unit of display. It is easy to imagine that there are many equivalent transformation groups that satisfy at least the area of the example in Table 1, and the writing order and position in FIG. 4(A) corresponds to this area gradation. FIG. 7 shows the realization of the middle gradation configuration.

Note that FIG. 7 is an explanatory diagram of an embodiment of the present invention, and Table 1 illustrates the average density gradation of pixels when pixels are eliminated in the area configuration of the embodiment in comparison with the conventional example. It is.

As is clear from FIG. 7, the gradation of the distribution structure of this embodiment is more uniform than that of the conventional example when viewed in terms of average density, which is much closer to a straight line.

(Effects) As explained above, according to the present invention, not only the number of dots written in a pixel, but also the overlapping areas between dots are taken into consideration, and dots are added next to express the next gradation. By taking into account the dots that have already been written to express the current gradation, the
By sequentially filling in the remaining parts in the sections 16 to 16, and by freely writing and configuring the first section, it is possible to achieve a gradation depiction that is close to being vaguely spaced.

In addition, the density of the dot in the case of the present invention is 0.0.
The 9th part that overlaps with 6 is ignored.The gradation is based on the same idea when the O- and D parts of the cards, which are evaluated close to ζ, are originally low and the 9th part that overlaps cannot be ignored. Of course it is possible to think about it.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the concept of the present invention, FIGS. 2 and 3 are explanatory diagrams of one embodiment of the present invention, and FIGS. Figure 5 (A) (1-16) and 5th
Figure (B) (1 to 16) is a detailed calculation example of Figures 4 (A) and (B), respectively Figure 6 is a supplementary diagram of Figures 5 (A) and (B), and M7 Figure 1d is an example of the present invention In the explanatory diagram of the example, the results obtained in this way were evaluated using half-uniform density. In the diagram, f3o is the area of the dot, 8+
+82.8g is the area of the overlapping parts. CB) (q to s) Sb 250-5t (3
Sθ-2St)tSo-2Sr (4So-4S
r) tstr-5t4S3=4Sa-4St
=55o-5St-? 53(7I(1) "3So-231 C6noh(!yso-7Ssl"5D-5t-(Sr-52u
3>-5s+Otsu5o-7j'++s2-433

Claims (1)

[Claims] Means for generating recording dots, scanning means for positioning and recording the dots at specific positions, and recording for selectively recording the dots at specific positions. In a gradation image recording device having a pattern and gradation pattern selection control means, and in which one multi-gradation pixel is constituted by a unit area in which the dot can be written in decimal fixed tone, the gradation is expressed. The method is to form a gradation pattern by taking into account the overlap between dots, which varies depending on the number of dots written in the above unit area and the placement position of the dots. A gradation image recording device characterized by forming a target.