JPS62222773A - Multigradation recording system - Google Patents

Abstract

PURPOSE:To obtain an extremely smooth density characteristic without lowering a resolution apparently by combining plural fixed patterns of small matrix size having a prescribed density and forming the matrix constituting a picture element. CONSTITUTION:Fixed pattern information and forming energy information of the fixed pattern are stored in a multivalued pattern table 2. By the combination of the fixed patterns a1-a5 and injection energy information, 51 gradation is represented as a whole. A multigradation picture signal is processed to the signal of the type conformed to the specification or the characteristic of a printer and outputted by a multigradation signal processing circuit 1. The signal processed in the multigradation signal processing circuit 1 is inputted to the multivalued pattern table 2. The fixed pattern information and energizing energy information from the multivalued pattern table 2 are applied to a thermal recording circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention combines a plurality of fixed patterns each consisting of a plurality of dots to collect a single summer bean bag, and at the same time collects the first summer coquetts by combining a plurality of fixed patterns each consisting of a plurality of dots. 1 pseudo-gradation image 1 by fttll GA injection energy
This paper relates to a multi-gradation recording method for obtaining images.

[Technical background of the invention and its problems]

In the melt-type thermal transfer recording method, in which heat-melting ink is heated by a thermal head to melt or soften the ink and record in one transfer, the density expression by ink transfer is
1" and "0", gradation expression by area modulation, so-called so-called 2-square area gradation, is generally performed.

However, with this method, the number of gradations that can be expressed in a single pixel expressed by a matrix of nxntIT is
Even if you include the 11 degree level of the recording paper base, n! It's only eleven. Therefore, in the case of flI, only 17 gradations can be expressed with a matrix size of 4×4. However,
Generally, to obtain an image that looks natural to the eye, the resolution of the color dots should be 4 dots) or more than 7 mm.

It is said that the number of gradations is 64 or more. In order to satisfy this requirement with both the two-magnetic area variation method, it is necessary to use one thermal head having an 8.times.8 matrix size and a heating element density of 32 dots/mm or more. However, the limit of currently available thermal heads is 16 dots/mm, and 3
At present, it is difficult to realize thermal transfer recording with a resolution of 2 dots/mm. For this reason, it has been extremely difficult to obtain smooth a-degree gradation using binary area gradation.

Therefore, in order to solve this problem, we used two inks with different densities.
A method of obtaining multiple gradations by combining pixel dots with different densities and pixel arrangement using laminated ink ribbons (Japanese Unexamined Patent Publication No. 1987-57)
-193377), and a method of sequentially overlapping a recording dots from low-quality ink to high-density ink using an ink ribbon coated with ink of different # degrees sequentially in the longitudinal direction (Japanese Patent Application Laid-open No. 59-55768). etc. have been proposed. However, all of these methods have drawbacks such as unstable ink transfer and long printing time.

In contrast to these methods, by multi-leveling the pixel formation energy of a fixed pattern, it is possible to obtain a larger number of gradations than before even with a small matrix size, and it is also possible to obtain the same number of gradations as before. Since it can be expressed with a smaller matrix size than conventional methods, increasing the number of gradations can also increase the resolution when opening.
8th grade) was proposed.

However, when the matrix size is made smaller in an attempt to increase the resolution of a ring with a low @lff1 ff of the thermal head, the number of tones that can be expressed in one decreases.
f+ gradation cannot be obtained and image quality deteriorates.

[Purpose of the invention]

The present invention was made based on such circumstances, and M
It is an object of the present invention to provide a multi-gradation recording method capable of expressing extremely smooth gradations without causing image wave deterioration.

[Summary of the invention]

The present invention provides a multi-gradation method for obtaining pseudo gradations by using a plurality of types of fixed patterns with different density levels set in a dot matrix 511 and by multi-leveling the pixel formation energy of each mark dot constituting the fixed pattern. It is characterized by the fact that one pixel is formed as follows in the tone recording method.

That is, the present invention is characterized in that a plurality of the fixed patterns are combined to form a matrix that constitutes a pixel.

〔Effect of the invention〕

According to the present invention, a plurality of fixed patterns of a small matrix size with a predetermined ia degree are combined to create a matrix forming the image can be obtained.

Furthermore, according to the present invention, by symmetrically tossing the fixed patterns adjacent to each other in the matrix IC3, the frequency of use of a specific heating resistor of the thermal head can be reduced.
11 Yumata can suppress S fever, which causes quality deterioration. Depending on the density of the adjacent matrix 11, the arrangement of fixed patterns within the matrix is changed so that the density change from the # degree of the ¥X matrix to the adjacent matrix is smooth. Even smoother density characteristics can be obtained by changing the distribution of dot formation energy to the mark dots that make up the fixed pattern.

In addition, by changing the matrix size according to the concentration change between the adjacent Ifl elementary concentrations, the matrix size is changed to 1 by using a matrix having one fixed pattern arranged as a small size.
Extremely smooth density characteristics can be obtained while keeping the pixel size small.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on one drawing.

Figure 1 (al is 8 dots/mm as an example of the present invention)
This is an example of configuring a 4x4 matrix by assembling four 2x2 dots as a submatrix using a thermal head with a resolution of 1. Dot patterns, diagonal patterns, and L-shaped patterns that emphasize diagonal dots have gradation level 1.
We found that the image quality was good and combined them to form five fixed patterns (a, ) to (a,) in Figure 1(a), each pattern having a density area as shown in Figure 2. can be expressed. In each of the density regions (1) to (2), a continuous density scale can be obtained depending on the amount of formation energy of the mark dots of the corresponding fixed patterns (a,) to (a,). In addition, in the same figure (b), the same 4 as in the same figure (al) is shown.
Myobumato I in X4 Matokugusu! Fixed patterns (b,) to (b,) that do not use glue are shown.

Fixed pattern (+1.) to (a
), the spatial frequency of the pattern is doubled compared to fixed patterns (bl) to (b,) using the same size matrix, and the apparent resolution is 2 lines/m of (b).
m71z etc. is better at 4 pieces/m m. This value almost matches the resolution of the human eye, and provides an extremely fine quality. In addition, since the submatrices of different a degrees are combined, the number of gradations that can be expressed increases, and extremely smooth m
Wave characteristics can be obtained.

Third South 12 is a block diagram showing the configuration of an apparatus for realizing the thermal recording method according to the above embodiment.

That is, 9 scanners, A/D converters (not shown), 1
The multi-gradation image fJlei input in the form of a digital signal from the ifii image memory, demodulation of the transmission system, summer circuit, etc. is processed by the multi-gradation signal processing circuit 1 into a form that matches the specifications and characteristics of the printer. The signal is subjected to M-number processing and output. The signal processed by this multi-gradation signal processing circuit 1 is input to a multi-value Bakun table 2.

The multi-value pattern table 2 determines the fixed pattern and the amount of energy to be injected according to the concentration information held by the melt field, and is specifically composed of R and OM, and is the main part of this embodiment. It is.

This multi-value pattern table 2 includes R, which conventionally generates a tape-1 silk-up format binary dither pattern.
QM sometimes included calculations to compensate for heat accumulation in the thermal head.

However, in this embodiment, this portion stores fixed pattern information and formation energy information for each mark dot, as will be described later.

The matrix position designation circuit 3 is a circuit for instructing the position on the matrix of a pattern in a matrix consisting of a plurality of pixels required for digital recording or pseudo intermediate recording. It is linked with a dot counter in the main scanning direction and a line counter in the sub-scanning direction. It was.

In some cases, it may be linked to the image signal input clog used in the multi-gradation signal processing circuit 1.

Fixed pattern information and energization energy information from the multi-value pattern table 2 are given to the thermal recording circuit 4. In this thermal recording circuit 4, the width of the energizing pulse for each heating element of the thermal head is used as a subsidiary. The energizing pulse output from the thermal recording circuit 4 is output to the thermal head drive circuit 5.

The thermal head drive circuit 5 is an IC circuit consisting of a shift register, a latch, and a gate driver, and is mounted on the thermal head substrate.

The interlocking operation of the conothermal recording circuit 4 and the thermal head drive circuit 5 is the same as the operation performed in conventional fused thermal transfer recording to compensate for the heat accumulation phenomenon. As stated in No. 988878, etc.

It is conceivable to vary the energization pulse width, vary the voltage level of the energization pulse, or use these in combination.

By the way, the multivalued pattern table 2, which is the main part of the apparatus according to the above embodiment, stores the following primary information. In other words, 1. For example, the concentration region is
The fixed pattern 1° to a is assigned to these density regions 1 to 2. Each of these density regions I to ■ is further divided into the fixed pattern a1.
~a.

The injected energy tone is divided into 10 gradations. That is, fixed pattern information and fixed pattern formation energy information are stored inside the multivalued pattern table 2.

Therefore, the combination of these fixed patterns al to al and the implanted energy information makes it possible to express 51 gradations as a whole.

In this way, according to this embodiment, even if an inexpensive thermal head with a low resolution of 8 dots/mm is used, an apparent resolution of 4 dots/mm and an extremely high resolution of 51 gradations can be achieved.
High-quality recording with multiple gradations can be obtained.

FIG. 4 1a) shows another embodiment of the present invention. Same figure (
A for each matrix (2 x 2 submatrices x 4) of al
, B, C, , C, , C, , D density information (density: A<B<C<D, C,=c.

"Cs)" indicates the pattern that will be output when input. The numbers 1, 2, 3,
...The larger the value of 10, the greater the image point formation energy.In this example, the same density information (C1tc
The arrangement of sub-matrices within the matrix output for 1 rcs ) is changed in accordance with density information of pixels adjacent to the matrix in the main scanning direction. That is, with respect to the density of a plurality of pixels adjacent to each other in the main scanning direction, the arrangement of the Nisafmato+1 pixels is changed so that the difference in density between the pixels and the directly adjacent submatrix becomes smaller. Figure 1b) is an example of outputting completely the same pattern for the same density information as fa) in the same figure (for example, (+, / , (::, / , C
, I are all the same pattern) and the density changes of each submatrix are not smooth (for example, B', A', C
You can see the sub-matrix column of the first rule at the top that follows ''.

On the other hand, in Figure 1al, the density of each pixel is maintained while the density of each sub-mask changes smoothly and continuously even between each pixel, making it possible to record extremely high image quality. can.

Another embodiment that provides the same effect as above is shown in FIG.

This example also corresponds to the same density information as in Fig. 4, but without changing the dot arrangement of each fixed pattern (submatrix), the fixed pattern is adjusted according to the density information of pixels directly adjacent to these in the main scanning distortion direction. Change the dot formation and energy distribution of the marked dots (in the figure, the dots with increased energy are
The reduced pixel is indicated by a Δ mark, but the density of the submatrix itself does not change) 1. The a degree change with the adjacent pixel is made smoother. That is, the pixel formation energy on the high-density pixel side is increased, and the energy of the foreign pixel is decreased. Alternatively, the energy for forming a pixel on the low-density pixel side is reduced, and the energy for other pixel points is increased accordingly. Note that in one or more examples, attention is focused only on pixels adjacent to each other in the main scanning direction, but it is of course possible that the pixel of interest may be in a direction other than this direction.

Figure 6 shows another embodiment of the present invention. The submatrix is 2×2, and the fixed pattern is a one-dot pattern corresponding to the density region I-IItm shown in fbl of the same figure.
Diagonal pattern, L-shaped pattern. In the case of a one-dot pattern, in order to stably record that pixel, it is necessary to apply a certain amount of energy (6 or more on this side) to record a pixel of a certain size or more. Therefore, if the submatrix is small, the area ratio of the pixel will be large.

In particular, the recording paper base density and the next a degree bell (same figure + b)
(A and C) may become large and the image quality may deteriorate. Therefore, if the level jump is small and smooth recording is possible (above D in Figure 1b), the submatrix is used as it is as a pixel, and the same +
Like between A and C of 1lbl! If the jump in one degree is large, increase the matrix as shown in B in the same figure (al), record only one pixel with high energy (this one combination has 2 matrices), and record the jump in density. In this case, pixels and pixel points become large, but the human eye averages the density of this area and sees it, so the density shown by B in the same figure (b) does not feel very smooth. The size of such a matrix or the corresponding density area may be freely varied depending on the characteristics of the recorded image.

FIG. 7 shows the above embodiment (Fig. 4).

FIG. 6 is a block diagram showing the W efficiency of an apparatus for realizing the thermal recording method according to FIG. 6). This has the same basic I/C configuration as shown in FIG. 3 (b) multi-gradation signal processing circuit 1.
Multi-value pattern table 2. Matrix position designation circuit 3.
Thermal recording device 4. In addition to the "thermal head" consisting of the dynamic circuit 5, the signal output from the multi-gradation signal processing circuit 1, for example coded density information, is stored.When recording a certain pixel, the surrounding area of that pixel is stored. There is a pattern side circuit 6 which reads density information of a pixel and outputs a selection signal to the multi-value pattern table 2 for determining the pattern of the pixel. Pattern 1t111 The open circuit 6 consists of a RAM for storing pixel a[information and a comparison circuit for determining deafness based on density changes between adjacent pixels, and outputs the determination result to the multi-value pattern table 2. It's cool. According to this signal, from the multi-single shift pattern table 2,
(Subma) Data in which the position of the IJ, the distribution of dot formation energy, the size of the matrix, etc. are changed is output to the thermal recording device 4. Alternatively, depending on the case, the signal of the determination result from the pattern control circuit 6 is input to the matrix position specifying circuit 3, and the sub-matrix position i degree etc. can be changed by changing the signals of the dot counter or line counter.

FIG. 8 shows another embodiment according to the present invention. Figure 1a)
is a pattern of sub-matrix l-IJ boxes adjacent in the sub-scanning direction in a matrix that is a combination of four 2×2 sub-matrices (one dot pattern, stripe pattern with continuous pixel points in the sub-scanning direction, and L-shaped pattern) are each other 5?
! ′ is a nominal pattern. : Tsukasa(Also(bl) is that each submatrix is arranged in the same pattern.
In the case of a dark pattern, it is printed continuously twice in the 01 scanning direction at most. In other words, the same heating resistor can be used up to two times in a row, but in the case of FIG. 6(b), the same heating resistor may be used continuously. Generally, when the heating resistor of the thermal head is energized and printing is repeated,
There is a drawback that heat accumulation is greater than heat diffusion, and density reproducibility and image quality are significantly deteriorated due to rapid increase in ink transfer rate. In particular, if the same heating resistor is used continuously as shown in fb) in the same figure, the image quality will deteriorate quickly due to this effect.In contrast, i'1JI
If the sub-matrix pattern is made symmetrical, as in JIal, so that many pixels are not consecutive in the sub-scanning direction, the effect of heat accumulation can be significantly improved. For example, fc) shows a schematic diagram of the temperature characteristics of the heating resistor for printing the pixel array of row B in la). The horizontal axis is time, and the numbers 112 and 3.4 indicate the printing start time of each line, and the vertical axis indicates the temperature change of the heating resistor at that time. The actual heating resistors of A and B at 3t, the solid line after 3 shows the temperature change of B, and the broken line shows the temperature change of A. As can be seen from this figure, the temperature of the heating resistor of A is ΔT lower than that of B at 5, and it is understood that it has almost returned to the initial temperature.

In this way, by making the sub-matrix pattern symmetrical with respect to the sub-matrix adjacent to each other in the sub-scanning direction so that the pixel dots are not continuous in the sub-scanning direction, it is possible to significantly reduce the influence of heat accumulation and obtain high-quality recording. Color with

By creating a symmetrical pattern like an octopus, the spatial frequency of each pixel becomes large, so it appears as a very fine, high-quality recording. Note that not only the sub-matrices adjacent in the sub-scanning direction are symmetrical patterns as in this embodiment, but also the patterns of sub-matrices adjacent in the main-scanning direction or diagonal direction are symmetrical patterns with respect to each other within the scope of this spirit. Of course, the same applies to any pattern (such as symmetrical, symmetrical, 9-point symmetrical, etc.). However, this method is particularly effective when the pattern is a sub-matrix pattern that has continuous pixel rows in the main scanning direction or the sub-scanning direction; There may be parts where points are formed continuously, which may have the opposite effect.

Next, still other embodiments of the invention will be described in detail.

This embodiment is characterized in that for fixed patterns in which expression density areas are adjacent to each other, dot formation energy is preferentially distributed to mark dots at corresponding positions so that the recorded shapes of both fixed patterns maintain continuity. .

According to this embodiment, two regions of one expression are adjacent to each other.
In the fineness region near the switching density of the two fixed patterns, the image point formation energy of the mark dots is distributed so that the recorded shape of both fixed patterns maintains continuity. The occurrence of random bridges between mark dots and the deterioration of image quality and density reproducibility caused by rapid changes in mark dot arrangement are significantly reduced, and extremely smooth recording can be achieved.

FIG. 9 1a) is a diagram showing an example in which a 3×3 matrix is used as this embodiment. That is, fixed pattern P,
, P, , P, , P are fixed patterns that can express the concentration regions I, n, In, and IV, respectively, as shown in Figure 2, and the energy implanted into each mark dot as shown in Figure 9 fa). (This example uses a thermal head of 8/snm, and the injection energy is 1°2, 3 =
・10 is that way n O, 30, 0, 32, 0, 34・0
．． 48mj)), continuous m-degree gradations can be obtained. In this example a0~84
41 gradations can be expressed by a multivalued pattern of G (hereinafter referred to as mark dot arrangement, or referred to as a multivalued pattern if fixed pattern pixel formation energy is included). Among the fixed patterns with adjacent density regions, the fixed pattern on the high density region side 1 has a shape in which one mark dot is added to the fixed pattern on the low and fiff side.

Pixel formation energy is applied to the high-density pattern to maintain the shape of the low-density pattern. In other words, in the example of FIG. 9 (a3), the fixed pattern P is
Contains the multivalued pattern Sen0, which is the maximum density of l, as it is,
In addition to maintaining the shape of the low-density l111 pattern, the image point formation energy for the mark dot D0 added to this pattern is changed. Fixed patterns P, and P, ,P,
The relationship between and P4 is also similar.

By distributing the image point forming energy in this manner, a recorded image of extremely high quality can be obtained.

In addition, the same figure (bl is for comparison, the concentration characteristics are the same figure fa)
A multi-valued pattern b' is similar to 1 (characteristics shown in FIG. 10), but the dot-forming energy is distributed so that the recorded shape is not maintained between fixed patterns that are in contact with each other by 1 m.

~ b 40 is shown.

As shown in FIG. 11fa), in the multi-level patterns a1 to a40 according to the present embodiment, even when different fixed patterns are adjacent to each other, the amount of energy injected into the common mark dot portion is the same or almost the same. As a result, even when the fixed patterns are switched, the recorded patterns formed have similar shapes even in different fixed patterns, as shown in FIG.

Therefore, the uniqueness of each recording pattern is maintained, and the reduction in manufacturing reproducibility caused by irregular bridges that occur when changing fixed patterns and the noise caused by irregular shading are also reduced, resulting in high quality. A recorded image can be obtained.

On the other hand, in the multi-level pattern BL-B41 of the comparative example shown in FIG. 9 1b), when different fixed patterns are adjacent to each other as shown in FIG. 12 fa), the amount of energy injected into the common mark dot position is Since the distribution is greatly different, the mark dots in adjacent patterns may be too close together or too far apart. Therefore, with such a pattern, recorded portions and blank portions may be irregularly lined up, or random bridges may occur, as shown in FIG. 2(b). For this reason, when the image quality deteriorates significantly due to density unevenness, and when such random bridges occur, the ink transfer area specifically and rapidly increases at that portion depending on the image point formation energy. For this reason, as the energy for forming one pixel point increases, the linearity of pixel density is hindered. The multivalued pattern al”'-34 that stops at this point two-line implementation column
With a value of 0, such a problem does not occur.

FIG. 5 shows the configuration of an apparatus for realizing the thermal recording method according to the above embodiment, which is shown in the block diagram of FIG.

The configuration is almost the same.

In other words, a multi-gradation image signal input in the form of a digital signal from a scanner, an A/D converter, an image memory, a transmission system restoration circuit, a decoding circuit, etc. (not shown) is processed by a multi-gradation signal processing circuit 1. Signal processing is performed on the signal in a format that matches the specifications and characteristics of the printer, and the signal is output. The signal processed in this multi-tone signal processing circuit Ml is input into the multilevel pattern table 2. This is the main part of this embodiment, which determines the energy consumption and is specifically composed of RQM.

This multivalue pattern table 2 is a ROM that conventionally generates a table lookup format binary dither pattern.
In some cases, this included calculations to compensate for heat accumulation in the thermal head.

However, in this embodiment, this portion stores fixed pattern information and formation energy information for each mark dot, as will be described later.

The matrix position designation circuit 3 is a circuit for instructing the position on the matrix of a pattern in a matrix consisting of a plurality of pixel points required for digital recording or pseudo-intermediate recording. The dot counter and the line counter in the sub-scanning direction are linked. , f.

In some cases, the clock IC for image signal input used in the multi-gradation signal processing circuit 1 may be interlocked.

The fixed pattern information and energization energy information from the multivalued pattern table 2 are provided to the thermal storage circuit 41C. This thermal recording circuit 4 controls the energization pulse width for each heating element of the thermal head. The energizing pulse output from the thermal recording circuit 4 is output to the thermal head drive circuit 5.

The thermal head movement circuit 5 is integrated into an IC consisting of a shift register, seven latches, and a gate driver.The interlocking operation of the thermal recording circuit 4 and the thermal head drive circuit 5 compensates for the heat accumulation phenomenon in conventional fusion thermal transfer recording. This is the same as the action taken for example in JP-A-57-208.
As stated in No. 283 and Japanese Patent Application Laid-open No. 59-98878.

It is conceivable to vary the energization pulse widths, vary the voltage level of one energization pulse, or use these in combination.

By the way, the following information is stored in the multivalued pattern table 2, which is the main part of the apparatus according to the above embodiment. In other words, 1. For example, the concentration region is
The fixed pattern P is divided into four density regions.

~P4 is allocated. And each of these concentration area techniques~■
is further divided into 10 gradations by controlling the amount of implanted energy in the fixed patterns P, -P4. That is, fixed pattern information and fixed pattern formation energy information are stored inside the multivalued pattern table 2.

Therefore, the combination of these fixed patterns P1 to P4 and the injection energy information makes it possible to express 41 gradations as a whole.

In such a configuration, good image quality can be achieved by distributing the dot formation energy so as to maintain the continuity of the recorded shape of the fixed patterns P1 to P4! It is possible to obtain a recording artist with excellent reproducibility.

As described above, according to this embodiment, even with a 3×3 matrix, the number of gradations can be increased from the conventional 10 gradations to 41 gradations, and a decrease in resolution due to this can also be suppressed.

Note that the present invention is not limited to the embodiments described above. For example, the multivalued patterns shown in FIGS. 13 to 17 are all patterns included in the basic idea of the present invention.

The one in Fig. 13 is a fixed pattern similar to that in Fig. 9, but as a multivalued pattern, the pixel formation energy of the maximum all patterns of the adjacent low-grainness side pattern is not used as is; Middle at.

and 'ltt+ats and az number? ass and am? As you can see from the comparison, less energy is applied than that.

Also, all is a! from alG! The number is a sy from 'Itg.
has a higher concentration than aslI, but the total amount of energy injected into the matrix is lower. This number takes into consideration the unique increase in ink transfer area due to thermal interference of image points in thermal recording. However, even in this case, it can be seen that the difference in the amount of energy implanted into the common mark dots is small so as to maintain the continuity of shape with the pattern on the low concentration side, as in the previous example.

FIG. 14 is an example using a fixed pattern that is basically a pattern extending diagonally with respect to the main scanning direction. The diagonal pattern is particularly effective when using a low-resolution thermal head (for example, 8 pieces/mm or less) because the apparent spatial frequency of the pattern becomes large.

FIG. 15 is an example in which the fixed pattern on the high concentration region side does not necessarily include the pattern on the low S degree region side.

For example, the fixed pattern P, does not include the mark dot DI of P, but has mark dots D, ,D added thereto. However, the ink is transferred to the vacant dot device DK of P, due to thermal interference from the surrounding mark dots, and the dot device DK is crushed. Therefore, this fixed pattern P is the mark dot D in P.

Even without this, the continuity of both recorded shapes is maintained.

Country 16, Figure 17 is an example using a 2x2 matrix.

As described above, in this embodiment, the desired effect can be obtained by distributing the dot forming energy so as to maintain the continuity of the recorded shape in the adjacent fixed patterns of the expression a degree area.

Furthermore, the present invention is not limited to the 3X3t2X2 matrix, and can be applied to other matrix sizes, but in order to further enhance the effects of the present invention, nXn (
A matrix size of 2≦n≦6 is desirable.

As described above, the present invention can obtain extremely high-quality recording by using a submatrix. Although each of the embodiments described above may be used independently, the effect can be increased by combining several of them.

Furthermore, the present invention is not limited to 2×2 as the submatrix size and can be applied to cases where other sizes are used; however, in order to further enhance the effects of the present invention, the submatrix resolution should be 4 lines/mm or more ( For example, if the resolution of the thermal head is 8 lines/mm, it will be 2×2.If the resolution is 12 lines/mm, it will be 3×
3 or less, 16 lines/mm, 4×4 or less) is desirable.

As described above, the present invention can be practiced with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining a submatrix pattern according to an embodiment of the present invention, FIG. 1 [b] is a schematic diagram showing a pattern of a comparative example, and FIG. Figure 3 shows the relationship between energy and recording density;
Figures 17 to 17 are diagrams for explaining still other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1...Multi-gradation signal processing circuit, 2...Multi-value pattern table, 3...Matrix position specification circuit, 4...Thermal recording circuit, 5...-Multiple head drive circuit. f'l ~P4''・Fixed pattern, ao~aMO-b
O~b4o...Multiple patterns. Agent Patent Attorney Rules Near ′@ Direction
Is Kikuo Takehana the first figure of the eye and hair follicles? Actual input of the whisper (Page 1) and the 1st part of the phrase (Fig. 4) Support the 5th part of the figure 6 Fig. 1st part of the 5th part
Figure 11 (a)

Claims (5)

[Claims] (1) A fixed pattern is set in a matrix composed of a plurality of dots, and the pixel formation energy of the mark dots constituting the fixed pattern is expressed as multivalued, and by combining the fixed patterns of different types. A multi-gradation recording method that expresses the entire density range as an expression range, characterized in that a pseudo gradation is obtained by configuring a matrix in which a plurality of the fixed patterns are combined. (2) The scope of the present invention is characterized in that the arrangement of the fixed patterns in the matrix is varied depending on density information of adjacent matrices, or the distribution of dot formation energy to mark dots forming the fixed pattern is varied. A multi-gradation recording method described in a single term. (3) The multi-gradation recording method according to claims 1 and 2, wherein the size of the matrix differs depending on the density information. (4) The multi-gradation recording system according to claims 1, 2 and 3, wherein fixed patterns adjacent in at least one direction within the matrix are symmetrical patterns with respect to each other. (5) The image point forming energy of the mark dots is distributed so that the recording shapes of two fixed patterns whose expressive density areas are adjacent to each other maintain continuity. Multi-gradation recording method.