JPH09123510A - Surface sequential recording method for color image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sensitivity malfunction of a second and following colors by applying energy of a level which does not record to a non-recording pixel of a first color in a method for surface sequentially recording a color image, thereby increasing the adhesive strength of the surface. SOLUTION: A plurality of line-like heaters are aligned in a main scanning direction in a thermal head 31 according to a method for surface sequentially recording a color image by using a variable dot size process, and a platen 33 is provided under the head 31. An ink ribbon 34 and an image receiving sheet 32 are intermittently conveyed by each unit feeding width in the sub scanning direction of an arrow A while superposing the ribbon 34 and the sheet 32 between both the head 32 and platen 33, and the image is recorded by controlling the energizations of respective heaters. In this case, if a second color is recorded on the part where the first color is not recorded under the control of printing, thermal energy of the degree for not recording is previously given to the part where the first color is not recorded. Thus, the adhesive strength of the part is enhanced to improve the sensitivities of the second and following colors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to color thermal recording such as thermal transfer, and in particular, area gradation by a staggered array pixel size using a variable dot size (VDS) method. The present invention relates to a modulation method color image field sequential recording method.

[0002]

2. Description of the Related Art The VDS method itself to which the present invention is applied has been publicly known, and the thermal energy applied to a recording material is changed by changing the application time of a voltage applied to a heater, thereby recording dots. This is a method that makes the size of variable. When the ink film is heated from behind by this heat energy, it is transferred to the ink image receiving sheet. In this case, one pixel is composed of a plurality of unit dots arranged in a staggered pattern in the vertical and horizontal directions, and the coloring area of the unit dot is changed by the VDS method, thereby changing the coloring area of one pixel. The thermal head for heating from the backside of the ink film is one in which a drive pulse is sent from the thermal head driver in accordance with the input drive data to heat each heater.

An example of this device is shown in FIG. In the figure, the thermal head 31 is provided with a heater having a length of, for example, 80 μm in the conveyance direction (sub-scanning direction: arrow A) of the image receiving sheet 32 and a width of about 70 μm in the direction perpendicular thereto (main scanning direction: arrow B). A plurality of lines are arranged in the main scanning direction. A platen 33 is provided below the thermal head 31, and an ink ribbon (recording material) is provided between them.
While the resin sheet 34 and the image receiving sheet (image receiving material) 32 are superposed on each other, the resin roller 35 and the rubber roller 36 intermittently convey each unit feed width in the sub-scanning direction of the arrow A. Each heater is driven by a drive pulse while the image receiving sheet 32 is transported by the unit feed width. After the recording is completed, the ink ribbon 34 is turned upward by the peeling bar 37 and discharged.

FIG. 4 is an enlarged schematic view of the recording portion of FIG. In the figure, the ink ribbon 34 is composed of a thin support 341 having a thickness of 3 to 6 μm and a thin peelable color material layer 342 thereon, while the image-receiving sheet 32 is the support 3
21 and a cushion layer 322 thereon and an image receiving layer 323 thereon. At the time of recording, the heater 311 is in contact with the support 341 side of the ink ribbon 34 while the ink ribbon 34 and the image receiving sheet 32 are overlapped,
Further, the thin peelable color material layer 342 supported on the support 341 of the ink ribbon 34 is the image receiving layer 323 of the image receiving sheet 32.
Ink ribbon 34
Is heated relative to the heater 311 so that the color material 342 'is peeled off in an image form. The heater 311 is linear and is divided into pixel units extending in a direction orthogonal to the paper surface.

In the case of color hard copy, the ink ribbon 34 is formed by dividing the ink layer into four colors of yellow (Y), magenta (M), cyan (C), and black (K) for each frame length. In addition to being used, the image signal processing circuit (not shown) performs color tone correction in addition to tone correction, and the table memory converts the densities of YMCK components of the image into YMCK transfer times. And first,
For example, after transferring Y for one frame, the rubber roller 36 is rotated in the reverse direction to return the image receiving sheet 32 to the initial position, and at the same time, the ink ribbon 34 is set below the thermal head 31 with the next M ink layer. To transfer.
Then, similarly to the transfer of Y, the transfer of M, C, and K is sequentially performed. In this manner, the image receiving sheet 32 is reciprocated four times to make one color hard copy with a mixed color of four YMCK colors.

A material for improving heat resistance and slipperiness may be provided on the back surface of the ink ribbon.
Further, a material for improving slipperiness and adhesion resistance may be provided on the back surface of the image receiving sheet.

[0007]

However, there are two problems with such a method. Problem 1: The first problem is to record the second and subsequent colors, and to record in the part where the first color is not recorded.
The sensitivity may be different when recording is performed on the part where the color is recorded. When this difference is large, the recording dot area ratio of the second color may deviate from the target recording dot area ratio. Therefore, the recording dot area ratio of the second and subsequent colors recorded on the portion where the first color is not recorded and the recording dot area ratio of the second and subsequent colors recorded on the portion where the first color is recorded are the same recording dot area ratio. There was a demand for such a solution.

Problem 2: Another problem is that, in the case of recording by the VDS method, when the dot pitch in the sub-scanning direction is longer than twice the heater size, even if high energy is applied, the gap between the dots is increased. Sometimes there are gaps and 100% solid printing is not possible. Therefore, in order to record 100%, it is necessary to raise the electric power applied to the heater to an extremely high level. In such a case, however, the temperature of the central portion of the recording dot rises too much due to overheating, and the color of the central portion changes. It happened. Therefore, in the case of recording by the VDS method, when the dot pitch in the sub-scanning direction is longer than twice the heater size, there is a demand for a 100% solid recording method with low power that does not cause overheating and has no gap. .

The details will be described below with reference to FIG. FIG. 1 is a diagram of zigzag arrangement-2 dots with an area ratio of 95% in the case of Y color in which the dot pitch is more than twice the heater size. In the figure, the up-down direction is the main scanning direction, the horizontal direction is the sub-scanning direction, the heater has a size of 80 μm in the sub-scanning direction, and in the case of Y recording, the dot pitch in the sub-scanning direction is 170.8 μm. Therefore, the dot pitch of Y is more than twice the heater size. This energizable time is 7 ms at a maximum of 1/2 dot pitch, but since 0.7 ms is actually taken during the data transfer period, the energization upper limit of Y is 6.3 ms.

In the figure, A is the position at the start of heating the heater, and B is the position at the end of heating. The area of the dot is wider than that of the heater position A at the start of heating because the temperature of the surrounding area is raised to the transferable temperature by the heating of the heater. The area of the dot is wider than that of the heater position B at the end of heating because the temperature of the surrounding area has risen to the transferable temperature by the heating of the heater. From this point on, the power supply is zero, so it is white. Then, heating is started again at the next dot pitch. The figure shows an area ratio of 9
Since it is an example of 5%, a white background is left, but in order to perform solid printing with an area ratio of 100% next time, it is desired to move B in the sub-scanning direction.
At 5%, the upper limit of the Y energizable time is 6.3 ms. Therefore, B cannot be moved further in the sub-scanning direction. So when you want 100% solid printing,
A higher power is applied to the thermal head to spread the heat around the thermal head and connect it to the next dot. However, if the dot pitch in the sub-scanning direction is longer than twice the heater size, a considerably high power must be applied in order to connect the next dot. The temperature of the central portion rises too much and the coloring material in the central portion changes.

Of course, if the dot pitch is less than twice the size of the heater in the sub-scanning direction, which is 80 μm (ie, K, C, M), the heater is placed on the material from the start to the end of heating. Since it moves relatively, the dot at the end of heating the heater and the dot at the start of the next heating are connected, and such a problem does not occur at the time of 100% solid printing.

[0012]

The present invention solves the above problems. In order to solve the problem 1, according to the present invention, the unrecorded level energy is applied only to the non-recorded pixels of the first color. Further, with respect to the problem 2, the non-printing level energy is applied to the non-printing pixels only for the color whose dot pitch in the sub-scanning direction is at least twice the heater size.

With this structure, the surface of the non-recorded pixel is heated by the energy of the level at which the first color is not recorded, and the adhesive force of the surface is increased, so that the abnormal sensitivity reduction of the second and subsequent colors is improved, and therefore The second and subsequent colors have the same hue regardless of whether or not the first color is recorded, and even when the dot pitch in the sub-scanning direction is longer than twice the heater size, there is no gap with low power.
It is possible to record solid images.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Table 1 shows an embodiment of the present invention.
And Table 2 will be described. The recording head, recording method, recording material, and image receiving material used in the embodiments of the present invention are as follows. Thermal head: 300 dpi (dots per inch) Rectangular heater with main scanning direction length 70 μm and sub scanning direction length 80 μm Applied power: 0.075 W / dot Sub scanning direction speed: 12.2 mm / s Color order: K → C → M → Y or Y → M → C → K Dot pitch: K = 85.4 μm, C = 102.5 μm, M = 128.1 μm, Y = 170.8 μm, Staggered array: K and M are one dot at a time, C And Y are recorded every 2 dots.

Thermal recording material: Color material content of all layers of the donor sheet is 40% by weight or more and color material layer thickness is 0.2 μm to 1.0 μm. Image receiving material: Softening temperature measured by Vicat method. Having a layer having a thickness of 80 to 80 ° C and a thickness of 3 to 100 µm between the support and the image receiving layer.

For Problem 1: Under such conditions, with respect to Problem 1, first, 100% solid recording is performed on the first color, and then the energy capable of recording the second color at an area ratio of 50% ( Hereinafter, with 50% solid energy), after applying the "strobe of the non-recording area" to the first color, 2
The results of measuring the area ratio by recording the color at 50% solid energy are shown in the results A of Tables 1 and 2.

Regarding Problem 2: For Problem 2, a color whose dot pitch exceeds twice the heater size (that is, Y) has an upper limit of 6.
Table 1 shows the area ratios obtained by recording by applying the "strobe of the non-recording portion" to the Y color under the recording condition of energizing for 3 ms.
The result B of 2 is shown.

[0018]

[Table 1]

In Table 1, in Conventional Example 1, first, 100% solid recording of K color or 0% solid recording is performed for the first color under the condition that the strobe ("0 heat") of the non-recording portion of all colors is 0 ms. Then, the second color, C color, is recorded at 50% solid energy, and the area ratio of C color is measured. further,
The M color of the third color is solidly recorded at 0%, and the Y color of the fourth color is recorded at an energization upper limit of 6.3 ms to measure the area ratio of the Y color.

In the prior art example 1, the area ratio of C color is 50% after 100% solid recording of K color, whereas 37% after 0% solid recording, a small dot. It was
This means that when the second color is recorded after the first color is recorded and when the second color is recorded without recording the first color, there is a large difference in area ratio between 50% and 37%. As a result, good quality print records cannot be obtained.
The area ratio of Y color is 9% after 100% solid recording of K color.
While it is 5%, it is 90% after 0% solid recording, and neither 100% solid density can be obtained.

The conventional example 2 is different from the conventional example 1 in that the non-recording portion is strobed by 0.4 ms for all of K, C, M and Y. In the conventional example 2, the area ratio of C color is 73% after 100% solid recording of K color, and 58% after 0% solid recording, which is a large dot. It is not possible to obtain a good print record. The area ratio of Y color is 10 for K color.
100% after both 0% solid recording and 0% solid recording
A solid density could be obtained.

This means that 100% solid density could be obtained by applying "strobe of non-recording portion" of 0.4 ms when recording the Y color. However, although the problem 2 was improved, the problem 1
Has not been able to obtain satisfactory printing performance. On the other hand, the example 1 is for the problem 1, and the area ratio of the C color was measured by applying the “strobe of the non-recording portion” of 0.4 ms only to the K color. The area ratio of C color is 100% for K color and 50% after solid recording, but it is 0%.
After solid recording, it was 45%, which was an acceptable difference in area ratio.

The second embodiment is directed to the second problem,
The Y-color area ratio was measured by applying a 0.4 ms “non-recording portion strobe” to only the Y-color. As with the results of Conventional Example 2, it can be seen that 100% solid density could be obtained.

In the third embodiment, both the first embodiment and the second embodiment are carried out, and the areas of the C color and the Y color are multiplied by applying 0.4 ms "non-recording part strobe" of the K color and the Y color. The rate was measured. The result of the area ratio of C color is 50% after 100% solid recording of K color, and 45% after 0% solid recording, which is an acceptable area ratio difference and Y color As a result of the area ratio of 100%, 100% solid density could be obtained for both K color after 100% solid recording and after 0% solid recording.

[0025]

[Table 2]

In Table 2, the recording color order of Table 1 is K → C → M → Y.
In contrast, the order of recording colors is Y → M → C → K. In Conventional Example 3, under the condition that the strobes of the non-recording portions of all colors are 0 ms, first, 100% solid recording of Y color is performed on the first color, or 0% solid recording is performed, and then M color is changed to 5 on the second color.
Recording is performed at 0% solid energy, and the area ratio of M color is measured. The Y-color energization condition is recorded at the energization upper limit of 6.3 ms.

In Conventional Example 3, as a result of the area ratio of Y color, 100% solid density cannot be obtained at 100% solid recording. The area ratio of M color was 45% after 100% solid recording of Y color, and 35% after 0% solid recording, which was a small dot.

The conventional example 4 is different from the conventional example 3 in that the non-recording portion is subjected to a "strobe of the non-recording portion" of 0.4 ms for each of Y, M, C and K. In Conventional Example 4, the result of the area ratio of Y color is 10 at the time of 100% solid recording.
A solid density of 0% could be obtained. The area ratio of M color is 71% after 100% solid recording of Y color and 55% after 0% solid recording, which is a large dot, and the area ratio after 100% solid recording of Y color is larger than expected value. It is impossible to obtain high quality print records.

On the other hand, the fourth embodiment has problems 1 and 2.
The area ratio of the Y color and the M color was measured by applying the 0.4 mm “strobe of the non-recording portion” to the Y color only. The result of the area ratio of Y color is 10 at the time of 100% solid recording.
A 0% solid density can be obtained, and the result of the area ratio of M color is 50% after 100% solid recording of Y color, while it is 43% after 0% solid recording. It was a difference in the area ratio that can be done.

As described above, when the second color is recorded in the portion where the first color is not recorded, the sensitivity is lower than when the second color is recorded in the portion where the first color is recorded.
Focusing on the phenomenon that if the heat energy to the extent that the first color is not recorded is given to the portion where the first color is not recorded in advance, the adhesive strength of that portion is increased and the same sensitivity as the portion where the first color is recorded can be obtained. Then, this is effectively applied at the time of recording the first color. Further, when the dot pitch in the sub-scanning direction is Y which is twice as long as the heater size or more, 10
Even in 0% solid recording, if low-level thermal energy is applied to the non-recording pixel in advance, the adhesive strength of that portion increases, so the non-recording pixel is also recorded by the heat received during the recording of the next adjacent pixel. Become.

The staggered arrangement handled by the present invention shows an example of one dot in FIG. In the figure, the originally recorded area (black portion of the checkered pattern) and the unrecorded area (white portion of the checkered pattern, portion indicated by A) are in a staggered arrangement, and all are recorded in the areas to be recorded. However, the white portion (A) that is not recorded remains. In the present invention, energy is applied to such unprinted white areas.

In addition to the above, there is a place where data is originally recorded in the zigzag arrangement but is not recorded because the record data at that place happens to be "zero" data (portion B in FIG. 2). In the present invention, energy is applied to such a portion that should be recorded originally but is not recorded. In this way, the color balance between this point and the other points to which energy is applied can be balanced.

In the above embodiments, the area gradation method is used, but the area gradation method is not limited to the density gradation method. Further, the present invention is not limited to the melt transfer, but can be applied to a sublimation transfer type color printer or a TA (Termo Auto Chrome) type color printer.

[0034]

As described above, according to the present invention, by applying a low heat energy to a proper place, the second and subsequent colors to be recorded and the first color to be recorded in the portion where the first color is not recorded are recorded. The second and subsequent colors recorded on the portion have the same hue. Further, even when the color dot pitch in the sub-scanning direction is longer than twice the heater size, solid printing of 100% is possible with low heat energy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between staggered dots and heater energization for Y color.

FIG. 2 is a staggered array diagram.

FIG. 3 is a partial perspective view of a heat melting type transfer recording device.

FIG. 4 is an enlarged view of a recording unit.

[Explanation of symbols]

 31 Thermal Head 34 Ink Ribbon (Thermal Recording Material) 311 Heater 341 Support 341 32 Image Receiving Sheet (Image Receiving Material) 342 Peeling Color Material Layer 321 Support 35 Resin Roller 322 Cushion Layer 36 Rubber Roller 323 Image Receiving Layer 37 Release Bar 33 Platen

Claims (5)

[Claims] 1. A method of recording a color image in a frame-sequential manner, wherein 1
A frame-sequential recording method of a color image in which energy of an unrecorded level is applied to non-recorded pixels only for colors. 2. A frame-sequential recording method for a color image in which a non-recording level of energy is applied to non-recording pixels only for a color having a dot pitch in the sub-scanning direction which is at least twice the heater size. Recording method. 3. A method of frame-sequential recording of color images, wherein 1
The color and dot pitch in the sub-scanning direction are heater size 2
A frame sequential recording method of a color image in which an unrecorded level of energy is applied to a non-recorded pixel of a color more than double the color. 4. The frame sequential recording method according to any one of claims 1 to 3, wherein in a staggered arrangement, a pixel that should be recorded originally is not recorded because the recording data of that pixel is non-recording data at the time of recording. A field-sequential recording method in which energy of a level that is not recorded is applied to such pixels. 5. The frame sequential recording method according to claim 1, wherein the first color is a color having a dot pitch in the sub-scanning direction which is at least twice the heater size.