JPH03221465A - Multigradation color printing method - Google Patents

Abstract

PURPOSE:To obtain an excellent image quality by coating a recording sheet with transparent or white heat meltable wax in response to an image signal or the quality of the sheet prior to transfer of ink onto the recording sheet. CONSTITUTION:Wax data at each time are sent to a dense/pale data comparator 12 according to first-n-times address signals from an address counter 11, compared with data from a data counter 13 by the comparator 12, and control data [0] or [1] is sent to a shift register 14. The register 14 sequentially inputs n-bit control data corresponding to first-n-times addresses to be supplied from the comparator 12, and sends them to a latch circuit 15. The coating amount of the transparent or white wax is reduced on a part having high gradation of the image to prevent an ink bridge, the coating amount of the wax is increased on a part having low gradation, and the control of a coloring dot size is reduced to a microsize.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multi-tone color printing method particularly suitable for reproducing halftone images among color printing methods using a thermal transfer printer.

(Prior art) The principle of a thermal transfer printer is as shown in FIG. The thermal head 102 is pressed against the surface opposite to the formed surface, and the thermal head 10
By energizing a predetermined resistor among the plurality of resistors constituting the resistor 2, it generates heat, and ink in the heated portion is transferred onto the recording paper 103.

Here, the ink layer 105 was formed by coating the transfer paper 104 with a heat-melting sublimation ink, which is a mixture of ink (coloring material) in heat-melting wax and forming an ink layer 105 together with a binder. There are heat dye sublimation type and a hybrid type between these types, and in color printing methods using these transfer papers, in order to print halftone images, there are two methods: changing the area of the ink dots transferred to the recording paper. There is a method of changing the number of dots, and the former provides better image quality than the latter, but consumes more power and cannot control the dot size at low gradations (low density).

Therefore, Japanese Patent Application Laid-Open No. 51389 describes a method for expressing colors including intermediate tones by controlling the dot size for high gradation (high density) areas and controlling the number of dots for low gradation (low density) areas. Proposed.

(Problems to be Solved by the Invention) When performing multi-gradation color printing using the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 51389, two different gradation expression methods are used, which makes control complicated and Since the low gradation portion is only a pseudo gradation expression, it is difficult to obtain good image quality.

(Means for Solving the Problem) The present inventor has developed the present invention based on the knowledge that the inability to control the color dot size in low gradation areas is mainly caused by unevenness on the surface of the recording paper. The gist is that before transferring heat-melting or sublimation ink to the surface of the recording paper, transparent or white heat-melting wax is applied to the surface of the recording paper depending on the image signal or the quality of the recording paper. .

(Function) For example, in low gradation areas, by increasing the amount of transparent or white heat-melting wax applied, the smoothness of the recording paper surface is increased and the size of colored dots can be controlled down to the minute size. Furthermore, by reducing the amount of wax applied in high gradation areas, the smoothness of the recording paper surface is suppressed to prevent ink bridging.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of a color printer device used to implement the method of the present invention, in which an analog video signal supplied from a TV signal generator 1 is converted into a digital signal by an A/D converter 2 and data is stored. Sent to device 3.

The data storage device 3 is provided with a yellow image data storage section 4, a magenta image data storage section 5, a cyan image data storage section 6, and a transparent or white wax data storage section 7,
Store each data.

Here, the transparent or white wax data is processed by the wax data creation device 8 into three colors: yellow, magenta, and cyan.
created based on two image data. To give an example, an address signal is sent from the Wa Sox data creation device 8 to the address bus 9, and according to this signal, data is sent from the yellow image data storage section 4, the magenta image data storage section 5, and the cyan image data storage section 6. Pass through bus 10 in Figure 2 (
The gradation data of each color as shown in A) is taken into the wax data creation device 8. Then, as shown in FIG. 2(B), among the gradation data of each color, data with the highest number of gradations is selected from among the three colors and sent to the wax data storage section 7 as wax data. Transparent or white wax is applied to the surface of the recording paper based on
Each color of magenta and cyan is transferred.

Specifically, according to the 1st to nth address signals from the address counter 11, each wax data is sent to the grayscale data comparison circuit 12, and the grayscale data comparison circuit 12 compares the data from the data counter 13 with the data from the data counter 13. The control data [0] or [1] is transferred to the shift register 14 by comparison.
send to In this shift register 14, the gray level comparison circuit 12
The n-bit control data corresponding to the 1st to nth addresses supplied by the controller are sequentially taken in and sent to the latch circuit 15. When a data transfer pulse is received from the address counter 11, the latch circuit 15 operates to shift register 1
The control data supplied from 4 is latched and the gate circuit 0
1 to Gn, respectively. This gate circuit G, ~G.

A heating pulse is applied from the correction circuit 16 to the other input terminal of the transistors, and each output signal thereof is applied to the corresponding NPN transistors T, -Tn to control switching thereof. Of the transistors T, -Tn, only the resistor 18 of the thermal head 17 connected to the collector side of the turned-on transistor is energized and generates heat.

In this way, you can apply less transparent or white hot-melt wax to areas with higher gradations in the image (to prevent ink bridging), and apply more wax to areas with lower gradations. It is possible to control the color dot size down to minute size.

Here, as a method of adjusting the amount of wax applied, there may be a method of controlling the fluidity of the wax by changing the energy applied to the resistor 18. That is, when the applied energy is low, as shown in FIG. 3(A), the recording paper 20
The amount of wax 21 applied to the surface is small and the smoothness of the recording paper surface is low, and if the applied energy is higher than this, the third
As shown in Figure CB), the wax 2 is applied to the surface of the recording paper 20.
The coating amount of No. 1 increases, and the smoothness of the surface of the recording paper increases, reaching a saturated state at a certain applied energy. At this time, the smoothness is the highest. As the applied energy is further increased, as shown in FIGS. 3(C) and 3(D), the wax 21 diffuses or permeates into the recording paper 20, and the surface smoothness decreases.

In the embodiment, the application energy of transparent or white heat-melting wax is changed in accordance with the image data, and the smoothness (wax distribution state) of the recording paper surface is controlled in accordance with the image. However, the application energy of the hot-melt wax may be set to a constant value for "-screen" and the smoothness of the surface of the recording paper may be constant, or the application energy of the hot-melt wax may be varied depending on the type of recording paper and surface roughness. It may be changed accordingly.

Further, the method of creating wax data is not limited to the above-described example, and wax data may be created by performing arithmetic processing based on image data of three colors.

Furthermore, it is also possible to use a transfer paper in which transparent or white hot-melt wax and ink of each color are applied sequentially at intervals in the length direction, or to transfer the hot-melt wax and each color of ink separately. You may also prepare paper.

〔effect〕

As explained above, according to the present invention, transparent or white hot-melt wax is applied to the surface of the recording paper before ink is transferred to the surface of the recording paper, and the smoothness of the surface of the recording paper is determined by the image signal or recording. Since it is adapted to the quality of the paper, a single gradation expression is required from low gradation areas to high gradation areas, making control easier. Therefore, good image quality can be obtained.

[Brief explanation of drawings]

Figure 2 is a circuit diagram of a color printer used to carry out the method of the present invention, Figures 2 (A) and (B) are graphs showing the relationship between each color, wax data, and gradation, and Figure 3 (A
), (B), (C), and (D) are cross-sectional views showing the relationship between the energy applied to the resistor of the thermal head and the smoothness, and FIG. 4 is a diagram showing the principle of a thermal transfer type printer. 3... Data storage device, 4... Yellow image data storage section, 5... Magenta image data storage section, 6... Cyan image data storage section, 7... Transparent or white wax data storage section, 8.・・Wax data creation device, 17・・
- Thermal head, 1st...Resistance element, 20...Recording paper, 21...Wax. Patent Applicant: Victor Company of Japan Co., Ltd. Figure 31 (B) Procedure: Xinbo Seisho (spontaneous) Indication of the case: Patent Application No. 18606/1999 Name of the invention: Multi-gradation color printing method relationship

Claims (1)

[Claims] With the thermal head placed on the opposite side of the transfer paper to the side on which the ink layer was formed and the ink layer in contact with the recording paper,
In a multi-gradation color printing method in which the dot size of the ink transferred to the recording paper is controlled by changing the amount of heat generated by energization of the resistor that constitutes the thermal head, the dot size of the ink transferred to the recording paper is controlled by A multi-gradation color printing method characterized in that a transparent or white heat-melting wax is applied to the surface depending on the image signal or the quality of the recording paper.