JPS60159072A - Color correction system of multi-color thermal transfer recorder - Google Patents

Abstract

PURPOSE:To permit exact realization of designated colors by correcting the amount of heat energy to be supplied to heating elements in such a way as to enable the same amount as ink amount to be transferred directly to a recording paper to be transferred on the information of designated density. CONSTITUTION:When Y-color of ink sheet is selected on a color switching signal S from the color switching circuit for ink sheets, ''1'' recorded in an image line buffer 16 and ''1'' recorded in a shift register 15 are put in a pulse width correction circuit 16. When the ink sheet is switched to M-region by a color switching signal S, the content of the shift register 15 is shifted by 1(one) bit, and the content of the shift register SR is also altered to ''100''. The AND GATE A1 is closed, AND GATE A3 is opened, a pulse width designation circuit 21 is operated to send out a signal corresponding to Tw+DELTATw, and M-color of dots are superposed on Y-color of dots to become dots of red color. The same amount as the ink amount when directly transferring it to the recording paper can thus be transferred to obtain a desired color.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a color correction method for a novel multicolor thermal transfer recording device that can faithfully express designated colors.

+b) Background of the Technology In recent years, multicolor thermal transfer recording devices have been widely used for image recording in facsimiles and the like due to their advantages such as the ability to use plain paper and low noise.

The configuration of such a conventional recording apparatus is shown in FIG. In the figure, 1 is an ink sheet having an ink layer in which each color region of yellow (Y), magenta (M), and cyan (C) is arranged as one set, and many of these sets are arranged in one row, and 2 is a large number of heating layers. A thermal head having elements arranged in a row in a direction perpendicular to the conveying direction of the ink sheet 1, 3 a recording paper, and 4 a platen that presses the ink sheet 1 and the recording paper 3 against the thermal head 2. To record in color with this recording device,
First, the Y area of the ink sheet 1 is transported to the position of the thermal head 2, and while the platen 3 is pressed, the multiple heating elements of the thermal head 2 are selectively heated according to the print information to record ink that is solid at room temperature. Transfer to paper 3. After recording the entire Y area as described above while conveying the ink sheet 1 and the recording paper 3 in the direction of the arrow, only the recording paper 3 is transported in the opposite direction (
The next M area is transferred in the same manner, and the C area is also transferred in the same manner. In this way, yellow, magenta, and cyan colors are recorded on the recording paper 3 where the ink is not superimposed, respectively.

By controlling the thermal energy applied to the thermal head 1, the amount of transfer is changed, that is, the transfer density is changed to obtain multiple gradations. This thermal energy control is generally performed by varying the pulse width of the applied voltage for ease of control.

When printing colors other than the three colors mentioned above, these three colors of ink may be selectively superimposed.

For example, to obtain a red color, the Y area is used as the undercolor to transfer, and the M area is overlaid and transferred on top of the Y area as the undercolor. For purple, the M area and C area are transferred, for green, the Y area and C area, and for black, the Y area, M area, and C area are sequentially overlapped and transferred.

Other intermediate colors are created by changing the transfer amount of each ink to be superimposed.

(C) Prior Art and Problems In such a conventional multicolor thermal transfer recording device, the pulse width of the applied voltage is adjusted according to the specified transfer density, regardless of the presence or absence of overlapping of inks or the amount of undercolor ink transferred. For example, if you specify a red color with a transfer density of 1 for each of yellow and magenta, it will be transferred first in the Y area and yellow with a transfer density of 1 will be obtained.
The transfer density of magenta that is then transferred in the M area is less than 1, which has the disadvantage that the desired color cannot be obtained.

This is because when ink is superimposed, the amount of undercolor ink that is transferred later depends on the amount of undercolor ink that is transferred, and when there is undercolor ink, the amount of undercolor ink that is transferred later depends on the amount of undercolor ink that is transferred, compared to when it is directly transferred to recording paper. This is because the amount of transfer decreases.

This will be explained in more detail below.

FIG. 2 is a diagram showing the relationship between pulse width and transfer density when transferring undercolor ink. In the figure, A is the density curve of the undercolor ink when it is directly transferred to the recording paper, and if there is already undercolor ink, the transfer density of the undercolor ink decreases as shown in the curves B and C. Here, curve C indicates that the transfer density of the undercolor ink is higher than curve B.

Figure 3 shows the transfer density D of the undercolor ink when the applied voltage and its pulse width are constant when transferring the undercolor ink.
1 and the transfer density D2 of the undercolor ink,
It can be seen that the transfer density of the undercolor ink decreases almost linearly as the transfer density of the undercolor ink increases.

In this way, there is a disadvantage that the transfer density is lower when superimposed transfer is performed compared to when it is transferred directly to recording paper.
Furthermore, since the amount of undercolor ink transferred varies depending on the transfer density of the undercolor ink, there is a drawback that a desired color cannot be obtained.

(dl Purpose of the Invention The purpose of the present invention is to solve the above-mentioned drawbacks of the conventional technology, and when color transfer is performed by overlapping inks, the transfer of the undercolor ink to be overlaid next is performed based on the color designation signal of the undercolor transferred first. To provide a color correction method for a multicolor thermal transfer recording device capable of faithfully expressing designated colors by correcting the amount.

(e) Structure and object of the invention According to the present invention, a recording paper, an ink sheet facing the recording paper and having ink areas of different colors, and a method for supplying thermal energy to the ink sheet are provided. In a thermal transfer recording device that consists of a thermal head with a heating element and records a color image by selectively and sequentially transferring ink of different colors onto a recording paper in accordance with a color designation signal, a predetermined color When transferring ink of a different color to the area where the ink was transferred,
A color correction method for a multicolor thermal transfer recording device, characterized in that thermal energy supplied to the heating element is corrected so that an amount of ink equal to that directly transferred to recording paper is transferred according to designated density information. This is achieved by providing

Embodiments of the Invention First, the principle of the color correction method of the multicolor thermal transfer recording apparatus of the present invention will be explained.

As explained earlier in Figure 3, when transferring over the under color ink, the amount of transfer is reduced compared to when transferring directly to the recording paper, so the transfer amount must be corrected by the amount of decrease. No. Further, the amount of correction is determined by the transfer density of the undercolor ink. As can be seen from FIG. 3, the transfer density D2 of the undercolor ink decreases approximately in proportion to the transfer density DI of the undercolor ink, so the amount of increase ΔD in the correction amount can be determined as shown in the following equation.

ΔD-ΔD2max-DI/D1may...11.
Also, D 1max is the saturated transfer density of the undercolor ink,
ΔD21Ilax is the correction amount when DI=D1max.

Furthermore, when three colors Y, M, and C are superimposed, there are two colors as undercolors, so it is necessary to refer to the transfer density of each color.

FIG. 4 is a diagram showing, as an example, the pulse width correction amount for determining the ink correction amount when M color ink is superimposed on Y color ink, and the horizontal axis is the pulse width;
The vertical axis is the transfer density of the undercolor ink. If there is no undercolor ink indicated by DO with respect to the designated transfer density DM of the undercolor ink, transfer is performed with the pulse width Tw. However, if the under color ink is transferred with the same pulse width Tw to an area where the transfer density of the under color ink is recorded with DYI and is superimposed, the transfer density will decrease to [1]. Therefore, by transferring with Tw + ΔTwl, which corrects the pulse width by ΔTwl, even if there is under-color ink, the transfer density of the under-color ink is D.
M will be obtained.

In addition, DY2 has a higher transfer density of the undercolor ink than DYI.
In this case, if the transfer is performed with the pulse width Tw, the transfer amount will be DM.
2, so Tw +Δ corrected by Δ1゛W2
It is necessary to transfer with Tw2.

FIG. 5 is a block diagram showing a first embodiment of the present invention, which is a correction method for performing overlapping transfer without considering the amount of undercolor ink transferred. In the figure, 10 is a code line buffer, 11 is a character generator, 12 is an image line buffer, 13 is a decoder, 14 is a ROM, 15 is a shift register, 16 is a pulse width correction circuit, 17 is a heating element 18 and a transistor 19 A thermal head consisting of
SR is a 3-bit shift register, 1 to 84 are ant game 1, ORI, OR2 is an OR gate, 20.2
1 indicates a pulse width designation circuit, respectively. However, only the pulse width correction circuit 16 and the thermal head 17 corresponding to the first dot of the image line buffer 12 are shown.

Table 1 Table 1 shows the contents of the ROM 14, in which 3-bit color separation signals corresponding to color designation signals are stored.

For example, if the color designation signal is yellow, the color separation signal of "100' is selected and transferred with the Y ink sheet, and if the color designation signal is red, the color separation signal of "110' is selected and Y and M
This indicates that the image will be transferred using an ink sheet of the same color.

The color correction method in the case of overlapping transfer will be explained using FIG. 5 and Table 1. Character code X and color designation signal Y, which are print information, are input to the code line buffer 10 line by line. One of the two pieces of information, the character code, is input to the character generator 11, decomposed into dot information, and input to the image line buffer 12. The other color designation signal is input to the decoder 13, which outputs an address signal corresponding to the color designation signal to the ROM 14. The ROM 14 outputs a color separation signal consisting of 3 bits specified by the selected address. This color separation signal is input to the shift register 15 for one line of three bits each.

Here, to simplify the explanation, this one line (n dot)
Consider the case where the first dot of the minute is designated as red.

When the Y color ink sheet is selected by a color switching signal S from an ink sheet color switching circuit (not shown), "1" is stored in the image line buffer 12 and "100" is stored in the shift register 15. Therefore, these signals are input to the pulse width correction circuit 16.The color separation signal from the shift register 15 is input to the AND gate 81 and the shift register SR, and the dot signal from the image line buffer 12 is also input to the AND gate. 81. Since both input signals of AND gate A1 are °1', “
1'' is output and input to AND gate A2. On the other hand, since "1" is input to the first bit of shift register SR and becomes "100", AND gate Δ2 is "1".
” is output, a signal corresponding to the specified pulse width Tu is output from the pulse width specifying circuit 20, a voltage is applied to the heating element, and a Y color dot is transferred.At this time, AND gates A3 and 84 are Since it is closed, the pulse width designation circuit 21
doesn't work. Such operations are performed simultaneously for one line to transfer the ink in the Y area.

Next, when the ink sheet is switched to the M area by the color switching signal S, the shift register 1
The contents of 5 are shifted by 1 bit and transferred to shift register SR.
Since the content of is also changed to °110', AND gate A1 is closed, AND gate 83 is opened, the pulse width designation circuit 21 is activated, and a signal corresponding to Tw + Δ1゛w is output, and the color of Y is The M color dot is superimposed and transferred on top of the dot to form a red dot. Note that when the ink sheet is switched to the M area, the shift register SR
Since the content is "011", it is not transcribed.

As can be seen from the above explanation, the pulse width is widened so that the same amount of ink is transferred as when directly transferred to the recording paper. As a result, in the conventional method, only a color different from red could be obtained because the amount of M color transferred was small, but in the method of the present invention, the desired red color can be obtained.

FIG. 6 is a block diagram showing a second embodiment of the present invention, in which the pulse width is corrected according to the amount of undercolor ink transferred. In the figure, 3o is an n-bit line buffer, 3L32 is a switch, 33 and 34 are multipliers, 35 is an adder, 36 is a converter that converts the density signal to be transferred into a pulse width, and 37 is a preset type down converter. counter, 17
indicates a thermal head, respectively.

In this embodiment, one line of image information is input to the line buffer 30, where one dot consists of Y, M, and C color designation signals and density designation signals. Color switching signal sy.

Sm and Sc are signals for switching the color area of the ink sheet, and are also input to the line buffer 3o, switch 3L32, and adder 35 as control signals.

When the color switching signal Sy is inputted to the line buffer 30, the line buffer 30 outputs density signals (Dy) and (Dll) of each bit.

Outputs only (Dy) of (Dc) and color switching signal S
When m is input, it outputs (Dy) and (Dm>, and when color switching signal Sc is input, it outputs (Dy).

It is controlled to output (Dm) and (Dc).

When the switch 31 receives the color switching signal Sy, the switch 31 switches the terminal A to the terminal A.
When the color switching signals Sm and Sc are input, it is connected to the terminal B side. Further, the switch 32 is controlled to be connected to the terminal A side when the color switching signal Sm is input, and to be connected to the terminal B side when the color switching signals Sy and Sc are input.

Multipliers 33 and 34 multiply the input concentration signal by a proportionality constant k. The value of k can be expressed as follows from equation (1).

k-ΔD2max/D1max...121 adder 35
has a function of selecting and adding the density signals inputted to terminals a to e according to the color switching signal and density signal type, and outputting the added value. That is, when the color switching signal Sy is input, only the density signal input from the terminal a is output. Also, when the color switching signal Sm is input, the density signal from terminal C and the density signal across the terminal are selected and added in principle, but the back density signal of the three density signals (
When Dm ) is 0, the concentration signal across the terminals is ignored. Furthermore, when the color switching signal Sc is input, the density signals of terminals S, d, and e are added as a general rule, but when the density signal (Dc) is 0 among the three density signals, the density signals of terminals S, d, and E are added.
The concentration signal from is controlled to be ignored.

The conversion circuit 36 has a function of converting the concentration signal from the addition circuit 35 into time width information and outputting the time width information to the counter 37. The counter 37 sets its output to "1" from the time when the time width information is preset, and subtracts its count value every time the clock signal CLK is input.When the count value reaches a specific value, for example 0, , its output is set to °0'.Therefore, the counter outputs a drive signal having a pulse width Tw according to the preset time width information, and this drive signal is applied to the transistor 19 of the thermal conductor 17. .

Next, the recording operation will be explained. To simplify the explanation, consider only the first dot of one line.
Assume that image information of a density signal (Dyl) whose transfer density corresponds to DYI and a density signal (Dm) whose transfer density corresponds to DM are input as shown in FIG.

First, only the density signal (Dyl) is read out by the color switching signal Sy and inputted to the switch 31. Since the switch 31 is connected to the terminal A side by the color switching signal sy, the density signal (Dyl) is input to the terminal a of the adder 35. Time width information corresponding to the concentration signal (Dyl) input to the converter 36 as described above is output. This information is presented to the counter 37 and counted until the counter value reaches O, and a drive signal having a pulse width corresponding to the density signal (Dyl>) is applied to the thermal head 17, directly applying the Y- color to the recording paper. is transcribed.

When one line of dots from the first dot to the nth dot are transferred at the same time in this way, the color switching signal Sn
+ allows the density signals (Dyl) and (Dm) to be read out simultaneously. One density signal (Dyl) is input to the switch 31, but since it is connected to the terminal B side by the color switching signal Sm, it is input to the multiplier 33, multiplied by the proportionality constant k, and input to the adder 35. be done. On the other hand, the concentration signal (D
m) is input to the switch 32, but this switch 32
is connected to the terminal A side by the color switching signal Sm, so it is inputted to the terminal C of the adder 35 through. Adder 35
is the concentration signal kx(Dyl
) and (Dm) are added and output to the converter 36. The converter 36 outputs information corresponding to this concentration signal kx(Dyl)→-(Dm), and the counter 37 outputs information corresponding to the concentration signal kx(Dyl)→−(Dm),
A pulse width of Tw+ΔTwl is output to the thermal head 17. This means that a corrected transfer density DM has been obtained.

Here, if the density signal (Dy2) corresponding to DY2, in which the transfer density of the undercolor ink is higher than the above-mentioned DYI, and the image information (Dm) similar to the above are input, the multiplier 33 calculates the proportionality constant k. Since it is multiplied, from the adder 35 kx
(Dy2) + (Dm) is output and counter 3
7 outputs a pulse width of Tw+ΔTw2.

Next, the operation when three colors of Y, M, and C are superimposed will be explained. The concentration signals of Y and M are the same as above (Dyl)
and (Dm), and assuming that a predetermined C density signal (Dc) is input, the process until recording Y and M colors is as described above. Next, in the case of transferring color C, density signals (Dyl), (Him), (Dc
) is read out.

Since the switch 31 is connected to the terminal B side, the adder 3
Since the switch 32 is also connected to the terminal B side, kx (Dn+) is output to the terminal d of the adder 35, and (Dc ) are input, so these concentration signals are added and input to the converter 36. The converter 36 outputs value information corresponding to this concentration signal, and the counter 37 outputs a signal with a predetermined pulse width.

In the above example, Y, M and Y, M, C are superimposed and transferred, but even when Y and C or M and C are superimposed, faithful colors corresponding to the image information can be obtained.

Furthermore, in this example, the pulse width was controlled as a means of correcting the thermal energy, but the same effect can be obtained by controlling the applied voltage, applied current, or the number of pulses corresponding to one dot alone or in combination. It goes without saying that you can get it.

(fl Effects of the Invention As explained in detail above, according to the color correction method of the multicolor thermal transfer recording device of the present invention, when the ink is superimposed on the already transferred ink, it is directly transferred to the recording paper. Since the thermal energy supplied to the heating element is corrected so that the amount of snow is transferred equal to the amount of ink transferred at the time of transfer, the specified color can be faithfully expressed.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the main parts of a multicolor thermal transfer recording device;
The figure shows the relationship between the pulse width when transferring the under-color ink and the transfer density of the under-color ink, using the transfer density of the under-color ink as a parameter. Figure 3 shows the applied voltage when transferring the under-color ink and its voltage. FIG. 4 is a diagram showing the relationship between the transfer density DI of the undercolor ink and the transfer density D2 of the undercolor ink when the pulse width is constant, and is used to explain the principle of the color correction method of the multicolor thermal transfer recording device of the present invention. FIG. 5 is a block diagram showing one embodiment of the present invention, and FIG. 6 is a block diagram showing another embodiment of the present invention. In the drawing, 1 is an ink sheet, 2 and 17 are thermal heads, 3 is recording paper, 13 is a decoder, 14 is a ROM,
15 is a shift register, 16 is a pulse width correction circuit, 18
is the heating element, 20.21 is the pulse width specification circuit, 33.3
4 is a multiplier, 35 is an adder, and DY-DM indicates the undercolor ink and the transfer density of the undercolor ink, respectively. Figure 1 Figure 2 Figure 3 Lower color/) Transfer density D1

Claims (2)

[Claims] (1) Consisting of a recording paper, an ink sheet facing the recording paper and having ink areas of different colors, and a thermal head having a heating element for supplying thermal energy to the ink sheet, and responding to a color designation signal. Accordingly, in a thermal transfer recording device that records a color image by selectively and sequentially transferring inks of different colors onto recording paper in a superimposed manner,
When transferring ink of a different color to a portion to which ink of a predetermined color has already been transferred, supply is supplied to the heating element so that an amount equal to the amount of ink directly transferred to the recording paper is transferred based on specified density information. A color correction method for a multicolor thermal transfer recording device characterized by correcting thermal energy. (2) The multicolor thermal transfer recording device according to claim (1), wherein the amount of correction of thermal energy during transfer is made variable according to the density of ink that has already been transferred. Color correction method.