JPH09300677A - Device and method for color recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the printing quality by reducing the hue variation generated by the printing shear among respective colors in a color recording device and a recording method thereof. SOLUTION: The resolution in the sub-scanning direction is quadrupled by a resolution conversion section 7, and mask patterns in compliance with respective colors are overlapped on a mask processing section 6 to form a constitution in which the shear amoung difference for respective lines and respective colors is provided. When the printing shear is generated in a certain color or a certain area, hue stripes generated by the hue variation can be controlled by the arrangement to improve the color reproducibility and tone reproducibility and also improve the image quality. In other words, the color reproducibility and tone reproducibility are improved to realize the accurate tone demonstrated in compliance with the calorie to be applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a thermal head in which a plurality of heating resistors are arranged in the main scanning direction of a color image, and three or more color materials containing at least yellow, magenta, and cyan are sequentially added. The present invention relates to a color recording apparatus and a recording method for recording an image on a recording medium by sequentially applying heat according to an image to a coated sheet.

[0002]

2. Description of the Related Art Generally, in a color thermal transfer recording apparatus using a thermal head in which a plurality of heating resistors are arranged in a line, which is a kind of color recording apparatus, the main raw material of the coloring material is a hot-melt ink containing a pigment. It is roughly divided into two types, one used and one using a thermal sublimation ink whose main raw material is a dye. The former is generally called a melting type thermal transfer recording device and the latter is called a sublimation type thermal transfer recording device. In a sublimation type thermal transfer recording device, a base layer composed of a polyethylene terephthalate (PET) film or the like is an ink in which a coloring material containing a sublimation dye as a main material is applied in the order of yellow, magenta, cyan and black in the case of color printing. The sheet is overlaid with a thermal transfer recording paper having an image-receiving layer made of a substance such as polyester resin to which the dye is easily dyed, and the ink is applied by applying heat from the thermal head to the ink sheet in the order of yellow, magenta, cyan, and black. Sublimate and transfer to thermal transfer recording paper. Further, in the case of the sublimation type, the transfer amount to the thermal transfer recording paper continuously changes according to the amount of heat to which the density gradation is added, so that it is suitable for recording halftone images such as photographs, and so-called full color printing is possible. It is possible. However, the transfer temperature of the general melting type is 100 ° C. or less, whereas the transfer temperature of the sublimation type is as high as 100 to 200 ° C., and a large amount of energy is required. Therefore, the device cost becomes high and the thermal head is cooled. The time required for printing is longer than that of the fusion type, and printing time is longer.Because dyes are the main raw material, sublimable inks are less expensive and more expensive than pigments. Since plain paper cannot be used, running costs are high.

On the other hand, in the fusion type thermal transfer recording apparatus, P
In the case of color printing with a color material mainly composed of a fusible pigment on a base layer such as an ET film, thermal transfer with high smoothness is applied to the ink sheet applied in the order of yellow, magenta, cyan and black as shown in FIG. Transfer the recording paper by stacking the recording papers and applying heat from the thermal head to the ink sheet to melt the solid ink and adhere the recording papers in the order of yellow, magenta, cyan, and black. Since the pigment is the same type used in general printed matter such as offset printing, it can be transferred to plain paper and can be transferred with a small amount of energy, so compared to sublimation thermal transfer recording devices. It has the advantage of low equipment cost and running cost, but it is difficult to express multiple gradations with one dot because transfer is performed due to the difference in the adhesive force between the ink paper and the base layer. Value printing was common. When a halftone image is printed by a fusion type thermal transfer recording device, dither processing or error diffusion is used, but the printed halftone image has a disadvantage that the actual resolution is low and the image is rough. However, in recent years, the thermal control technology of the thermal head has been improved, the quality of the ink sheet has been stabilized, and the coating material of the recording paper has been improved.

[0004]

Generally, when the resolution of the thermal head is 300 dots per inch (dpi), if the gradation can be controlled in 256 steps for each color of yellow, magenta, cyan and black, it can be identified by human eyes. It is said that all colors can be expressed. However, for that purpose, when the resolution of the thermal head is, for example, 300 dpi, the diameter of the dots is continuously controlled within the range of about 4 to 100 μm, and the relative position of each dot and the dot of the other color is in any region on the paper. It will have to be the same. The first color,
Ideally, the centers of the dots of the second, third, and fourth colors should all be in the same position, but it is very difficult to control the position of the thermal transfer recording paper in the sub-scanning direction on the micron scale with respect to the thermal head resistor. A deviation of about 100 μm exists in a certain width in the sub-scanning direction. Since the transparency of the ink itself is not 100%, when the dots of each color are exactly overlapped with each other as shown in FIG. 3 and when there is a deviation, there is a difference in hue when viewed with the naked eye. Further, the fact that the transfer characteristics of the ink to the thermal transfer image receiving paper and the transfer characteristics when the ink is transferred onto the ink are generally different also promotes the difference in hue when viewed with the naked eye. Due to these factors, for example, when solid printing is performed by applying heat of 50% for each of yellow, magenta, and cyan, the hue of a certain area in the sub-scanning direction changes as shown in FIG. FIG. 3 shows an example in which two colors are overlapped, but if the third color is printed in this state, the frequency at which stripes occur becomes even higher and it looks more dirty. Therefore, for example, in the case of an image displayed with a uniform color gradation such as the sky or the face of a person, the image quality is significantly deteriorated.

Therefore, the conventional thermal transfer method has a problem that it is difficult to accurately reproduce a stable color tone in accordance with the amount of heat to which the gradation of density is applied in the case of fusion type thermal transfer recording. Therefore, the color recording apparatus and the recording method of the present invention can improve the quality of a printed image by providing stable and reproducible gradation expression and color reproduction that do not cause stripes even when a printing deviation occurs. An object is to obtain a fusion type color thermal transfer recording apparatus and method.

[0006]

In order to solve the above-mentioned problems, the color recording apparatus of the present invention is an integer multiple of the resolution of the color image data for printing in the sub-scanning direction, for example, 4
The number of pixels is doubled, that is, the number of pixels in the sub-scanning direction is quadrupled, and a mask processing unit for superimposing a predetermined mask pattern on the image data is provided. Then, this mask pattern is configured to be different in at least two colors, preferably three colors.

Then, the timing control means (that is, the sub-pixel of the color image data before the resolution conversion) can print from any of the sub-scanning direction feeds by dividing the resolution of the color image data before the resolution conversion into four in the sub-scanning direction. If the scanning direction resolution is 300 dpi, the paper feed in the sub-scanning direction is 1
200 dpi unit, and the print signal can be generated in the 1200 dpi unit).

Further, as a more detailed configuration of the color recording apparatus of the present invention, the resolution conversion means sets the gradation data of each line after conversion to the corresponding line when the number of pixels in the sub-scanning direction is multiplied by an integer. Is calculated by weighting the corresponding line before conversion, the previous line, and the next line.

The mask processing means superimposes a 4 × 4 or 8 × 4 mask pattern in which 3 is 0 and 1 is 1 in one column on the image data after resolution conversion, and the mask is 0. The gradation of the image data of the portion is set to 0, and the gradation of the portion where the mask is 1 is left unchanged. As a result, the number of pixels before the resolution conversion process becomes the same as the number of pixels that can actually generate a print signal.

Further, the timing control means is a gradation of the image data for every four times the resolution of the image data before the resolution conversion process for printing, that is, for every 1/4 of the feed amount in the sub-scanning direction before the resolution conversion process. The print signal can be generated according to the above. Further, in the color recording method of the present invention, at least three colors are used, and the second color with respect to the first color dot is 0 dot, 1/4 dot, 2/4 dot in the sub-scanning direction.
Printing is performed by shifting in the sub-scanning direction in units of four columns in the main scanning direction with a combination of one set of four rows that always includes either dots or 3/4 dots, and the third color is in the sub-scanning direction for the first and second colors. 0 dot, 1/4 dot, 2/4 dot, 3/4
Printing is performed by shifting in the sub-scanning direction in units of 8 columns in the main scanning direction with a combination of one set of 8 rows that always includes two dots each.

Furthermore, in a color recording method for printing an image or a character using at least three colors, an operation of printing only one dot of four dots continuous in the sub-scanning direction is executed every four dots for each color. And the dots to be printed are different in at least two colors.

Furthermore, in a color recording method for printing an image or a character by using at least three colors, the number of pixels in the sub-scanning direction of the image data input from the outside is quadrupled, and four consecutive dots in the sub-scanning direction. The operation of printing only one dot among the four dots is performed for each color, and the dots to be printed are different in at least two colors.

In the color recording apparatus and the color recording method configured as described above, the colors of yellow, magenta, and cyan have deviation amounts different from each other in advance, and any color is printed in printing. Even if there is a deviation, the total amount of deviation with respect to other colors does not change, and it is possible to suppress the occurrence of hue stripes. Therefore, since the hue reproducibility is improved, accurate gradation expression and color reproduction can be achieved according to the amount of heat applied to the gradation.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1, 4 and 5. FIG. 1 is an explanatory diagram showing the configuration of a thermal head drive unit in an embodiment of the color recording apparatus of the present invention. FIG. 4 is a schematic view of the color thermal transfer recording apparatus embodying the present invention when the thermal head is down. FIG. 5 is a schematic view of the color thermal transfer recording apparatus embodying the present invention when the thermal head is up.

In FIGS. 4 and 5, the thermal head 1
The heating resistor 1 is arranged at 8 so as to face the platen roller 10. The platen roller 10, the pair of paper feed rollers A12, and the paper feed roller B11 are a stepping motor A2 controlled by a controller (not shown).
3 allows forward and reverse rotation in the sub-scanning direction line by line and conveys the thermal transfer recording paper 25. In front of the platen roller 10, a pair of paper feed rollers A27 and B26 for feeding paper to the platen roller 10 and a paper feed guide (not shown) are arranged. Further, a pair of paper discharge rollers A14 is provided in front of the paper feed roller A12 and the paper feed roller B11.
A sheet discharge roller B13 and a sheet discharge guide (not shown) are arranged. Paper feed roller A27 and paper feed roller B26,
Both the discharge roller A14 and the discharge roller B13 can be rotated in the sub-scanning direction by a DC motor 24 controlled by a controller (not shown).
Is transported. Further, an ink sheet supply roller 15 and an ink sheet take-up roller 16 are arranged, and the ink sheet take-up roller 16 can be rotated by a stepping motor B22 controlled by a controller (not shown). Further, immediately after the thermal head 18, a peel plate 19 for stably peeling off the ink sheet 17 after thermal transfer and the thermal transfer recording paper 25 is arranged. In addition, an ink sheet guide roller 21 is provided between the peel plate 19 and the ink sheet take-up roller 16 in order to prevent the peel angle from changing due to the change in the diameter of the take-up side due to the ink sheet 17 being taken up. The peel angle is fixed by. Like above-mentioned,
4 shows a state in which the thermal head 18 contacts the thermal transfer recording paper 25 and the ink sheet 17 and presses them, and FIG. 5 shows the thermal head 18 in the thermal transfer recording paper 25.
Indicates that the ink sheet 17 is not pressed.

As shown in FIG. 1, the thermal head comprises 3520 heat generating resistors 1 arranged at 300 dpi intervals in the main scanning direction, and a switching element 3 such as a transistor for controlling energization of each heat generating resistor or other elements. A thermal head driving power supply 2 configured by a logic element or the like and supplying a current to the heating resistor 1 is connected to the thermal head. The output of the heat pulse generator 4 is connected to each terminal (base) that controls the energization of the switching element 3. The thermal head itself can be moved up and down. When the thermal head 1 is down, the heating resistor 1 applies pressure to the platen roller 10 as shown in FIG. 4, and when it is up, no pressure is applied as shown in FIG. And the platen roller 10 are separated.

The heat pulse generator 4 can read data from the line memory 5. The image signal sent via the mask processing unit 6 is stored in the line memory 5 for eight lines or more. Line memory 5 is S-RAM, D
-A semiconductor device such as a RAM is used, but another storage device such as a magnetic disk may be used. Mask processing unit 6
The image signal sent through the image signal interface unit 9 is input to the frame memory 8 and the resolution conversion unit 7. The image signal interface unit 9 is connected to a host computer (not shown) that supplies image data to the thermal transfer recording device, and enlarges, reduces, rotates, RGB, and the like of an image sent from the host computer.
It also has a CMYK conversion function. An image signal sent via the image signal interface unit is stored in the frame memory 8 for one screen or more. The frame memory 8 is S
A semiconductor device such as -RAM or D-RAM is used, but another storage device such as a magnetic disk may be used.

The stepping motor 23 shown in FIGS. 4 and 5 moves the thermal transfer recording paper 25 to 2.5 mS / 1 during printing.
It operates to convey at a line speed (1 line = 25.4 / 1200 mm). The transport speed other than during printing is not specified. Next, in the present invention, the time width of the applied pulse generated by the heat pulse generator 4 of FIG. 1 differs for each color and each gradation, and the higher the gradation, the longer the pulse width. However, since the voltage of the thermal head is set so that the maximum gradation can be realized by the applied pulse shorter than the line cycle, the applied pulse width does not exceed the line cycle at the maximum gradation. Further, the increment due to the applied pulse and the higher gradation is determined in consideration of the heat storage of the thermal head (TPH), the transfer characteristics of the ink, the ambient temperature, the humidity and the like. Since the specific conversion method from the gradation data to the time width of the applied pulse is not the essence of the present invention, the details of the specific circuit will be omitted. In this apparatus, the applied pulse for each gradation in one line is set not to exceed 2 mS, and the voltage that can generate the maximum gradation that ink can output within that range is set to 15 V as the TPH supply voltage. Further, it is possible to give an instruction for various settings such as starting and stopping the operation of the thermal transfer recording apparatus and changing the print mode from a host computer (not shown).

The ink sheet 17 is shown in FIGS. 2 (A) and 2 (B).
As shown in FIG. 3, heat-melting inks of yellow, magenta, cyan, and black are applied to a base layer made of a film such as PET for each screen in the order of yellow, magenta, cyan, and black. As shown in FIG. 4, the ink sheet has a structure in which colors are sequentially switched by rotation of the ink sheet take-up roller. Further, the color detection sensor 20 allows a controller (not shown) to determine the current color of the ink sheet 17.

Next, the operation of this device will be described. FIG.
In FIG. 3, the host computer (not shown) sends a signal for giving an instruction to start the printing operation to the thermal transfer recording apparatus, and the thermal transfer recording apparatus starts the printing operation and the image data signal sent from the host computer (not shown) is passed through the image signal interface section 9. And is stored in the frame memory 8. The image data sent from the host computer to the image signal interface section here is a digital signal, and generally has a width of 8 bits per color, but this is not the case when the present invention is applied. The color may consist of three colors of cyan, magenta, and yellow, or data of four colors obtained by adding black to these three colors (hereinafter referred to as CMYK data), or data of three colors of red, green, and blue. (Hereinafter referred to as RGB data) in some cases. For example, image data composed of CMYK data of 100 pixels has 100 × 4 × 8 = 3200 bits (400
(Byte) data capacity. The image signal sent from the host computer to the thermal transfer recording device may be an RGB image, a CMYK image, or a resolution of 30.
Since there are cases other than 0 dpi, if the image sent by the image signal interface unit 9 is an RGB image, C
The image is converted into an MYK image, and when the resolution is other than 300 dpi, the image is converted into an image of 300 dpi using the enlargement / reduction function, and then sent to the resolution conversion unit 7. That is, the image data signal sent from the image signal interface unit 9 to the resolution conversion unit 7 is CMYK data and is naturally a digital signal. In addition, one pixel (cyan,
A unit consisting of 4 bytes in total of magenta, yellow, and black corresponds to a pixel printed by any one heating resistor of the thermal head in a one-to-one correspondence. These enlargement, reduction, and RGB → CMYK conversion are configured by a digital logic integrated circuit, but since this is not the essence of the present invention, the details of the specific circuit will be omitted.

The resolution converter 7 sequentially reads the image data stored in the frame memory 8 from the first line of yellow. In the resolution conversion unit 7, the number of lines is quadrupled in order to quadruple the resolution in the sub-scanning direction. In order to make the explanation easy to understand, any line before resolution conversion is subjected to resolution conversion processing to be line A, line B, line C, line D.
In the case of conversion into four lines, the weight of the previous line gradation data before conversion is 50, the weight of the corresponding line before conversion is 50, the weight of the next line before conversion is 0 in line A, and the weight of the next line before conversion is 0 in line B. The weight of the previous line gradation data is 25, the weight of the line before conversion is 75, and the weight of the next line before conversion is 0.
In line C, the weight of the previous line gradation data before conversion is 0, the weight of the line before conversion is 100, the weight of the next line before conversion is 0, and in line D the previous line gradation data before conversion Is 0 and the weight of the line before conversion is 7
5. Gradation data of each line after resolution conversion is generated by setting the weight of the next line before conversion to 25. However, regarding the first line and the last line, the gradations of the previous line and the next line are calculated as 0, respectively.

As a concrete example, the case of 8-bit image data composed of 8 × 4 pixels as shown in FIG. 6 in the frame memory will be described. After resolution conversion, 8 × 1 as shown in FIG.
Converted to image data of 6 pixels. The converted image data shown in FIG. 7 is then sent to the mask processing unit 6. When the mask processing is for the first color, the mask pattern to be superimposed on the image data for the first color is composed of a 4 × 4 matrix as shown in FIG. When the mask pattern of FIG. 8 and the image data of FIG. 7 are superposed, the image data as shown in FIG. 11 is generated. Next, when the mask processing is for the second color, the mask pattern to be superimposed on the image data for the second color is composed of a 4 × 4 matrix as shown in FIG. When the mask pattern of FIG. 9 and the image data of FIG. 7 are superposed, the image data as shown in FIG. 12 is generated. Next, when the mask processing is for the third color, the mask pattern to be superimposed on the image data for the third color is composed of an 8 × 4 matrix as shown in FIG. When the mask pattern of FIG. 10 and the image data of FIG. 7 are superposed, the image data as shown in FIG. 13 is generated. Next, when the mask processing is for the fourth color, the mask pattern to be superimposed on the image data for the fourth color is composed of a 4 × 4 matrix as shown in FIG. When the mask pattern of FIG. 8 and the image data of FIG. 7 are superimposed, the same image data as the first color as shown in FIG. 11 is generated. The image data after the mask processing is sequentially written in the line memory. Here, in order to simplify the description, the same value as shown in FIG. 6 is used for each color for the gradation data, but of course, in actual printing, it should be different for each color, and this case can be processed in the same manner. Needless to say.

In FIG. 5, one sheet of thermal transfer recording paper 25 placed in a paper feed guide (not shown) is set in the apparatus by rotating the paper feed roller A27 and the paper feed roller B26 in parallel with the transfer of image data. Pull in. When the thermal transfer recording paper 25 is conveyed to the positions of the paper feed roller A12 and the paper feed roller B11, the subsequent conveyance is the paper feed roller A1.
2 and the paper feed roller B11 mainly. When the print start line portion of the thermal transfer recording paper 25 is conveyed to below the heat generating resistor 1 of the thermal head 18, the conveyance is temporarily stopped. Next, the ink sheet take-up roller 16 rotates to take up the ink sheet 17. When the color detection sensor 20 detects yellow, the winding of the ink sheet is once stopped, the thermal head 18 goes down, and the print start line portion of the thermal transfer recording paper 25 and the ink sheet 17 of the heat generating resistor 1 and the platen roller 10. It is sandwiched between them and waits for a print start instruction from the controller.

In FIG. 1, when the storage of the image data to be printed in the line memory is completed, the heat pulse generator 4 reads the data of the first line of yellow from the line memory 8 and the data of the length corresponding to each gradation is obtained. It becomes possible to generate an applied pulse. At this point, the print preparation is completed, so that the paper feed roller A12, the paper feed roller B11, and the platen roller 10 start to convey the thermal transfer recording paper 25, and the ink sheet take-up roller 16 starts to take up the ink sheet 17. The heat pulse generator 4 generates a heat pulse (applied pulse) to the switching element 3 of each heating resistor 1 in synchronization with the start of these. The applied pulse of each line has the same pulse generation start time regardless of the gradation, and the end time differs depending on the gradation. When the application of the first line is completed (2
After mS), the heat pulse generator 4 reads the image data of the second line from the line memory 5 and starts printing of the second line 2.5 mS after the start of printing the first line. The yellow printing is completed by sequentially performing these operations up to the final line. Further, as soon as the reading of one line from the heat pulse generator 4 is completed, the line memory 5 is written with the data after resolution conversion and mask processing of the next line.

Since the final line corresponds to the total number of lines in the sub-scanning direction of the printed image, it differs depending on the size of the image to be printed. By the above operation, the arrangement of yellow dots on the thermal transfer recording paper 25 is as shown in FIG. When the printing of the final line is completed and the final line portion of the thermal transfer recording paper 25 is peeled, the thermal head 18 is in the up state and the ink sheet take-up roller 16 stops rotating as shown in FIG. Next, the paper feed roller A12, the paper feed roller B11, and the platen roller 10 rotate in reverse, so that the portion of the thermal transfer recording paper 25 one line before the printing start line is the heating resistor 1 and the platen roller 10.
It is returned to the recording unit sandwiched between. At the same time, the ink sheet take-up roller 16 is rotated so that the ink sheet 17 is not detected until the color detection sensor 20 detects magenta.
Is sent.

When magenta is detected, the winding of the ink sheet is once stopped, the thermal head 18 goes down as shown in FIG. 4, and waits for a magenta printing start command from a controller (not shown). The heat pulse generator 4 is 1
Similarly to the color, the image data after the resolution conversion and the mask processing of the data of the first line of magenta is read from the line memory 5 and an applied pulse corresponding to the number of gradations is generated. At this point, the preparation for printing the magenta image is completed, so that the ink sheet take-up roller 16 starts to rotate, and the transfer of the thermal transfer recording paper 25 is started. Similar to, the last line is sequentially generated. By the above operation, the magenta dot arrangement on the thermal transfer recording paper 25 is as shown in FIG.

When the printing of the final line is completed and the final line portion of the thermal transfer recording paper 25 is peeled, the thermal head 18 is in the up state and the ink sheet take-up roller 16 is rotated as shown in FIG. Stop. Next, the paper feed roller A12, the paper feed roller B11, and the platen roller 10 are rotated in reverse, so that the thermal transfer recording paper 25
Is the heating resistor 1 in the part one line before the printing start line
Then, the sheet is returned to the recording section sandwiched by the platen roller 10.
At the same time, the ink sheet take-up roller 16 rotates to feed the ink sheet 17 until the color detection sensor 20 detects cyan.

At the time when cyan is detected, the winding of the ink sheet is once stopped, the thermal head 18 goes down as shown in FIG. 4, and waits for a cyan print start command from a controller (not shown). The heat pulse generator 4 reads the image data after the resolution conversion and the mask processing of the data of the first line of cyan similarly to the first color and the second color from the line memory 5 and generates an applied pulse according to the number of gradations. Becomes At this point, the preparation for cyan image printing is completed, so the ink sheet take-up roller 16 starts to rotate, starts to convey the thermal transfer recording paper 25, and at the same time as the conveyance starts, the heat pulse generation unit applies the yellow pulse to the applied pulse. Similar to magenta, it occurs sequentially up to the final line. By the above operation, the cyan dot arrangement on the thermal transfer recording paper 25 is as shown in FIG.

When the printing of the final line is completed and the final line portion of the thermal transfer recording paper 25 is peeled off, the thermal head 18 is in the up state and the ink sheet take-up roller 16 is rotated as shown in FIG. Stop. Next, the paper feed roller A12, the paper feed roller B11, and the platen roller 10 are rotated in reverse, so that the thermal transfer recording paper 25
Is the heating resistor 1 in the part one line before the printing start line
Then, the sheet is returned to the recording section sandwiched by the platen roller 10.
At the same time, the ink sheet take-up roller 16 rotates to feed the ink sheet 17 until the color detection sensor 20 detects black.

At the time when black is detected, the winding of the ink sheet is once stopped, the thermal head 18 goes down as shown in FIG. 4, and waits for a black print start command from a controller (not shown). The heat pulse generator 4 reads the image data after the resolution conversion and the mask processing of the data of the black first line as in the case of the first color, the second color, and the third color from the line memory 5, and applies an application pulse according to the number of gradations. Will occur. At this point in time, the preparation for black image printing is completed, so the ink sheet take-up roller 16 starts rotating, starts transporting the thermal transfer recording paper 25, and the heat pulse generation unit 4 applies an yellow application pulse in synchronization with the transport start. , Magenta, and cyan are sequentially generated until the final line. By the above operation, the black dot arrangement on the thermal transfer recording paper 25 is as shown in FIG.

When the printing of the final black line is completed and the final line portion is peeled off, the thermal head 18 goes up and the ink sheet take-up roller 16 stops rotating. Next, the discharge roller A14 and the discharge roller B13
When the paper feed roller A12 and the paper feed roller B11 rotate, the thermal transfer recording paper 25 is ejected out of the apparatus, and the printing is completed.

In the thermal transfer recording apparatus configured as described above, the resolution conversion unit 7 multiplies the number of pixels in the sub-scanning direction by an integer, and the mask processing unit 6 prints the first color, the second color and the third color. Since the pixel patterns are different, each row has a different amount of misalignment from other colors, and even if printing misalignment occurs in a certain area, the total amount of misalignment between colors does not change, preventing hue shift. It is possible to stabilize the color reproducibility.

The present invention is not limited to the configuration of the above embodiment. That is, 2 for the first color dot
The same procedure is performed in units of 4 columns in the main scanning direction with a combination of 4 rows and 1 set that always includes 0 dot, 1/4 dot, 2/4 dot, or 3/4 dot in the sub scanning direction. Printing is performed by shifting in the scanning direction, and 0 dots, 1/4 dots, 2 /
If a combination of any one set of 8 rows including 2 pieces each of 4 dots and 3/4 dots is performed in the same manner in units of 8 rows in the main scanning direction, and printing is performed by shifting this in the sub scanning direction. It's good. In addition, the operation of printing only one dot of the four continuous dots in the sub-scanning direction is performed for every four dots, and the dots to be printed may be different in at least two colors. Of.

However, the present invention is not limited to quadruple the number of pixels in the sub-scanning direction in the resolution converter. When the number of pixels in the sub-scanning direction is multiplied by n, for example, for the first color dot, the second color is 0 dots, 1 / n dot, 2 / n dot, ... (n−
1) / n dot is always included in a combination of any one set of n columns, and the same is performed in units of n columns in the main scanning direction, and printing is performed by shifting this in the sub-scanning direction.
0 dots, 1 / n dot, 2 in the sub-scanning direction for the color
, N dots, ..., (n-1) / n dots, each of which includes 2 pairs of 2n columns, and is similarly performed in the unit of 2n columns in the main scanning direction in the sub-scanning direction. It should be shifted and printed. Further, the operation of printing only one dot of the n dots continuous in the sub-scanning direction is performed for every n dots, and the dots to be printed may be different in at least two colors. Of.

Further, the mask pattern for each color of the mask processing section is not limited to the embodiment. In short,
It is only necessary to print one dot in one row and not to print the other dots, and to use a mask pattern in which the dots printed in at least two colors are different. When the number of pixels in the sub-scanning direction is multiplied by n in the resolution conversion unit, it is preferable that the mask pattern has n rows.

Of course, it goes without saying that the resolution conversion section and the mask processing section are made to be the same as those in the embodiment, so that a remarkable effect can be obtained. Furthermore, in the above embodiment, the present invention has been described by taking the fusion type thermal transfer recording device as an example.
It goes without saying that the present invention is also applicable to other types of color print recording devices, for example, inkjet recording devices.

[0037]

As described above, according to the present invention, each color has a different amount of deviation from each other in advance in each row, and even if an arbitrary color is misregistered in printing, the deviation from other colors is caused. It is possible to suppress the occurrence of hue fringes without changing the total amount of the colors and to improve the hue reproducibility, so that accurate gradation expression and color reproduction can be achieved according to the amount of heat applied to the gradation.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a thermal head driving section in an embodiment of a color recording apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an ink sheet.

FIG. 3 is an explanatory diagram showing a specific example of a change in hue due to a print shift in halftone solid printing.

FIG. 4 is a diagram schematically showing a color thermal transfer recording apparatus embodying the present invention when a thermal head is down.

FIG. 5 is a diagram schematically showing a color thermal transfer recording apparatus embodying the present invention when a thermal head is raised.

FIG. 6 is gradation data used for specific description of the color recording apparatus and the recording method of the present invention.

FIG. 7 is an example of gradation data after resolution conversion in the color recording apparatus and the recording method of the present invention.

FIG. 8 is an example of the mask patterns of the first and fourth colors in the color recording apparatus and the recording method of the present invention.

FIG. 9 is an example of a mask pattern of the second color in the color recording apparatus and the recording method of the present invention.

FIG. 10 is an example of a mask pattern of the third color in the color recording apparatus and the recording method of the present invention.

FIG. 11 is an example of gradation data after mask processing for the first color and the fourth color in the color recording apparatus and the recording method of the present invention.

FIG. 12 is an example of tone data after mask processing for the second color in the color recording apparatus and the recording method of the present invention.

FIG. 13 is an example of gradation data after mask processing for the third color in the color recording apparatus and the recording method of the present invention.

FIG. 14 is a diagram showing an example of a dot arrangement on a first-color and fourth-color thermal transfer recording paper in a color recording apparatus and a recording method of the present invention.

FIG. 15 is a diagram showing an example of a dot arrangement on a second color thermal transfer recording sheet in the color recording apparatus and recording method of the present invention.

FIG. 16 is a diagram showing an example of a dot arrangement on a third color thermal transfer recording sheet in the color recording apparatus and the recording method of the present invention.

[Explanation of symbols]

 1 Heating Resistor 2 Thermal Head Driving Power Supply 3 Switching Element 4 Heat Pulse Generation Section 5 Line Memory 6 Mask Processing Section 7 Resolution Conversion Section 8 Frame Memory 9 Image Signal Interface Section 10 Platen Roller 11 Paper Feed Roller B 12 Paper Feed Roller A 13 Paper ejection roller B 14 Paper ejection roller A 15 Ink sheet supply roller 16 Ink sheet take-up roller 17 Ink sheet 18 Thermal head 19 Peel plate 20 Color detection sensor 21 Ink sheet guide roller 22 Stepping motor B 23 Stepping motor A 24 DC motor 25 Thermal transfer recording paper 25 26 Paper feed roller B 27 Paper feed roller A

Claims (10)

[Claims] 1. A color recording apparatus for printing an image or a character using a plurality of colors, and a resolution conversion unit for multiplying the number of pixels in the sub-scanning direction of image data input from the outside by an integer, and the resolution conversion unit. And a mask processing means for performing a mask processing on the output data of each color with a predetermined mask pattern, the mask processing means having different mask patterns for at least two colors. 2. In a color recording apparatus for printing an image or characters using at least three colors, a resolution conversion unit for multiplying the number of pixels in the sub-scanning direction of image data input from the outside by an integer, and the resolution conversion unit. And a mask processing means for performing a mask processing on the output data of each color with a predetermined mask pattern, the mask processing means including at least 3
A color recording device having a mask pattern that is different for each color. 3. The color recording apparatus according to claim 1, wherein the resolution conversion unit doubles the number of pixels in the sub-scanning direction by four. 4. The resolution conversion unit, when converting the number of pixels in the sub-scanning direction, the first line after conversion has a weight of 50 for the previous line before conversion, a weight of 50 for that line, and two lines after conversion. For the eye, the weight of the previous line before conversion is 25, the weight of the line concerned is 75, the weight of the line before conversion is 100 for the third line after conversion, and the weight of the line before conversion is for the fourth line after conversion. And the weight of the next line is 25, so that the gradation data after resolution conversion is obtained.
The described color recording device. 5. The mask pattern of the first color of the mask processing section is a 4 × 4 matrix of (0101, 0000, 1010,000) and the mask pattern of the second color is (00).
01, 0010, 0100, 1000) 4 × 4 matrix, the mask pattern for the third color is (11000000)
00,001,000,000 01100,000
5. The color recording apparatus according to claim 1, wherein each of the color recording apparatuses is composed of an 8 × 4 matrix of (0011). 6. The color recording apparatus has a thermal head in which a plurality of heating resistors are arranged in the main scanning direction of a color image, and a thermal head sequentially applies color materials of a plurality of colors to a sheet. 6. The color recording apparatus according to claim 1, wherein the color recording apparatus is a fusion type thermal transfer recording apparatus that records an image or a character on a recording medium by sequentially applying heat according to the image. 7. The color recording apparatus according to claim 1, wherein the color recording apparatus is an inkjet color recording apparatus having nozzles that eject ink of a plurality of colors. 8. In a color recording method for printing an image or a character using at least three colors, for the first color dot, the second color is 0 dot, 1/4 dot, 2/4 dot, 3 dot in the sub-scanning direction. / 4 dots are always included in a combination of 4 columns, and printing is performed by shifting in the sub-scanning direction in units of 4 columns in the main scanning direction, and the third color is 0 dots in the sub-scanning direction for the first and second colors. , 1/4 dot, 2/4 dot, 3/4 dot must contain two 2 columns each 1
A color recording method characterized by printing by shifting in the sub-scanning direction in units of 8 columns in the main scanning direction by combining sets. 9. In a color recording method for printing an image or a character using at least three colors, an operation of printing only one dot of four dots continuous in the sub-scanning direction is executed every four dots. The color recording method is characterized in that the printed dots are different in at least two colors. 10. A color recording method for printing an image or a character using at least three colors, wherein the number of pixels in the sub-scanning direction of image data input from the outside is quadrupled and four consecutive dots in the sub-scanning direction are formed. The color recording method is characterized in that the operation of printing only one dot is performed every four dots for each color, and the dots to be printed are different in at least two colors.