JPH02172763A - Multiple gradation thermal transfer recording device - Google Patents

Abstract

PURPOSE:To reproduce an optimal image regardless of the number of gradations by controlling recording energy based on the recorded data in memory, when the number of gradations of entered image is less that of data which can be reproduced. CONSTITUTION:In case printing is performed using a Y color ink film, for instance, a control section 4 rewrites recorded data of a conversion table 1 to Y color data and stores it in a line buffer 2. A head control section 3 controls power supply to a recording head based on the recorded data, and the same process as described above takes place for printing in M and C colors. In this case, recorded data stored in the conversion table (RAM or ROM) is rewritten to recorded data corresponding to each color and the gradation of each color Y to C is independently compensated for, when data is printed in each color Y to C. In this way, an optimal image is formed regardless of the number of gradations of entered image data.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a multi-tone thermal transfer recording device capable of recording multi-tone images, and in particular, to a multi-tone thermal transfer recording device capable of recording multi-tone images, and in particular, to The present invention relates to a multi-tone thermal transfer recording device that can output optimal color images.

Conventional technology Generally, thermal transfer printers are equipped with a thermal head consisting of a plurality of heating elements arranged in a line, and the energization state (on/off) of each heating element of the thermal head is controlled. By doing so, a desired image is formed on a recording medium such as transfer paper. In addition, recently, there has been a desire to output high-quality images with reproduced halftones. As shown in Fig. 1, there is a system that reproduces a 166-gradation image by changing the energization time to each heating element of the thermal head according to the number of floors 2i of input image data.

Problems to be Solved by the Invention However, in such conventional multi-tone thermal transfer recording devices, the data of the energization time to the thermal head corresponding to the number of gradations of input image data is fixed. Therefore, there is a problem that an optimal image cannot be obtained unless the number of gradations of the input image data is equal to the number of gradations that can be reproduced by this multi-gradation thermal transfer recording apparatus. For example, when the number of gradations that can be reproduced by a multi-gradation thermal transfer recording device is 166 gradations, the number of gradations of input image data is 8 gradations or 256 gradations, etc. If the number of gradations does not match the number of gradations that can be reproduced by the recording device, it will not be possible to reproduce an optimal image.

The multi-gradation thermal transfer recording device of the present invention has been developed to eliminate these conventional drawbacks, and is capable of reproducing an optimal image regardless of the number of gradations of input image data. The purpose of the present invention is to provide a multi-tone thermal transfer recording device that can perform the following steps.

Means for Solving the Problems In order to achieve the above object, the present invention is a multi-tone thermal transfer recording device that inputs image data and forms a multi-tone color image based on the image data, an image forming means for forming a color image on a recording medium by means of the image forming means; a storage means for storing recording energy to be outputted to the image forming means as recording data for each color in correspondence with the number of gradations of input image data; control means for controlling the recording energy given to the image forming means based on the recording data stored in the storage means when the number of gradations in the input image data is smaller than the number of reproducible gradations; It is characterized by having.

The multi-tone thermal transfer recording apparatus inputs image data and forms a multi-tone color image based on the image data, the image forming means forming a color image on a recording medium by thermal transfer; storage means for storing recording energy to be output to the forming means as recording data for each color in correspondence with a predetermined gradation width of input image data;
control means for controlling the recording energy given to the image forming means based on the recording data stored in the storage means when the number of gradations in the input image data is larger than the number of reproducible gradations; It is characterized by having.

Operation The multi-gradation thermal transfer recording apparatus according to the present invention configured as described above operates as follows.

When the number of gradations of the input image data is smaller than the number of gradations that can be reproduced by the multi-gradation thermal transfer recording device, the control means controls the image forming means based on the recorded data stored in the storage means. The applied recording energy is controlled. That is, when the number of gradations of the input image data is 8 gradations, the recorded data corresponding to the number of gradations of the input image data is retrieved from the storage means in which the recorded data of 8 gradations is stored. The control means controls the recording energy given to the image forming means based on the read recording data. Specifically, this control is
This is done by varying the time during which the image forming means is energized. Therefore, if the input image data has 8 gradations, an optimal image with 8 gradations can be formed.

The control means also controls the number of gradations of the input image data to be
When the number of gradations is greater than the number of gradations that can be reproduced by this multi-gradation thermal transfer recording device, the image forming means is processed based on the recorded data stored in the storage means that has a data structure that can handle the input of such image data. The applied recording energy is controlled. That is, for example, if the number of gradations that can be reproduced by a multi-gradation thermal transfer recording device is 32 gradations,
Assuming that the number of gradations of the input image data is 256 gradations, the gradation data in which the 256 gradations have been compressed to 32 gradations is stored from the storage means that -H. Record data corresponding to the number of gradations is read out, and the control means controls recording energy given to the image forming means based on the read record data. This control is performed by changing the time period during which the image forming means is energized, similarly to the above. Therefore, even if the input image data has 256 gradations, an optimal image with 32 gradations can be formed.

Embodiments Below, embodiments of a multi-tone thermal transfer recording apparatus according to the present invention will be described in detail with reference to the drawings.

1 to 3 are schematic diagrams showing various aspects of the control section in the multi-gradation thermal transfer recording apparatus according to the present invention.

The multi-gradation thermal transfer recording device shown in FIG. 1 is for yellow (Y), which is used when performing color printing.

Record data corresponding to the characteristics of each magenta (M) and cyan (C) ink film is stored for each Y, M, and C recording. A conversion table 1 as a storage means made of silk, a line buffer 2 for temporarily storing recorded data output from the conversion table 1, and an image forming means based on the recorded data stored in the line buffer 2. It has a head control section 3 that controls power supply to a recording head such as a thermal head (not shown), and a control section 4 as a control means that controls rewriting of recording data in the conversion table 1 and the operation of the head control section 3. and are connected as shown.

According to the multi-tone thermal transfer recording device in which the control section is configured as described above, for example, when printing is performed using a yellow ink film, the control section 4 converts the recording data of the conversion table 1 into yellow color data. The head control unit 3 controls energization of the print head based on the print data. Next, printing is performed using a magenta ink film, but when printing in this color is performed, the recorded data stored in conversion table 1 is rewritten to that of magenta color, and printing is performed as described above. . Note that printing with a cyan ink film is also performed in the same manner as described above. In this way, the recorded data stored in the conversion table 1 is
When printing each color of Y, M, and C, recording data corresponding to each color is rewritten, and gradation correction is performed independently for each color of Y, M, and C.

Further, in the multi-gradation thermal transfer recording apparatus shown in FIG. 2, the conversion table 1 shown in FIG. 1 is 1? It is configured by OM, and when printing, the control unit 4
The recording data of the color to be printed is extracted from this conversion table IA, and the head control section 3 controls the energization of the recording head based on the extracted recording data. Color printing is performed by performing such control for each color. Furthermore, this conversion table is I? Since it is composed of OM, it has an independent conversion table for each color. That is, three 1's for each color of Y, M, and C.
I have OM.

Furthermore, the multi-gradation thermal transfer recording device shown in Fig. 3 is a multi-head type in which a recording head is provided for each color. An independent translation table, i.e.
Y conversion table IB.

M conversion tables IC, C conversion table ID, line buffers 2B to 2D and head control units 3B to 3D provided corresponding to these conversion tables IB to ID, and their respective conversion tables IB to ID and head control A control section 4 that controls the operations of sections 3B to 3D is shown, and these are connected as shown. In addition, in the same figure, the parts indicated by solid lines are each conversion table. This is the input route of input data when OM is used, and the dotted line indicates the input route of recorded data to the conversion table when RAM is used as each conversion table.

According to the multi-gradation thermal transfer recording device in which the control section is configured as described above, when printing yellow, the control section 4 extracts the recording data from the Y conversion table IB and performs the following based on this recording data. When printing yellow color using a recording head exclusively for yellow, and then printing magenta, M conversion table I is used.
If you want to extract print data from C and print magenta using a magenta-dedicated print head based on this print data, and then print cyan, take print data from C conversion table ID and print this print. Based on the data, cyan color printing is performed using a recording head dedicated to cyan. Furthermore, if these conversion tables IB to ID are configured by RAM, the print data for each color is sent from the control unit 4 to the respective conversion tables, even after each color is printed. become. This recording data is set to each of the conversion tables IB to ID at the same time as the power is turned on.

FIG. 4 is a diagram showing the relationship between the recording pulse width T output from the recording head and the density for each color in a general ink film used when performing color printing. As can be seen from this figure, in this type of ink film, even if the recording pulse width applied to the self-recording head is the same, the density for each valley color is different. For this reason, the recorded data of each conversion table described above is corrected so that if the number of gradations of the input image data is the same, the density of each color is also the same.

The multi-gradation thermal transfer recording device according to the present invention can be used independently for each color as shown in FIGS. The recorded data is stored in each of the conversion tables described above. That is, what is shown in FIGS. 5 to 7 is
This is recording data that is used when the number of gradations of input image data is smaller than the number of reproducible gradations, and the recording pulse width corresponding to each density is stored in each conversion table as recording data. What is shown in these figures assumes that the number of gradations in the input image data is 32 gradations, and divides the maximum density that can be reproduced by the ink film by this number to obtain equally spaced densities, and in order to reproduce each density. This is to find the pulse width necessary for In other words, the recording energy is set linearly with respect to the number of gradations of input image data. This relationship is shown as specific numerical values in Table 1 shown on the next page. In the data shown in this table, a pulse width of 0.1 s is assigned to one gradation of recording data, and the number of recording data is 100, so the maximum recording pulse width is 1001 s. That is, in this table, when the number of gradations of input image data is 32 gradations, the equally spaced density step is set to 0.05, and 32 gradations are assigned to the number of recording data 100. be.

For example, when the number of gradations of the input image data is 19, that is, when the density is 1.0, the recorded data of yellow color is 53. That is, the pulse width is 5. 3+
++s, the recording data for magenta color is 58. That is, the pulse width is 5. 8ms, and the recording data for cyan color is 66, that is, the pulse width is 6.6a+s, and when reproducing an image with a density of 1.0, the recording head needs a voltage with the above pulse width for each color. will be applied. In this way, when the number of gradations of the input image data (32 gradations in the above example) is smaller than the number of reproducible gradations, that is, the number of recorded data (100 in the above example), A predetermined gradation is expressed by recorded data as shown in Table 1. Incidentally, when the densities are set at equal intervals in this way, the setting is such that when the same density steps of Y, M, and C are superimposed, an achromatic color (white-gray-black) is obtained. In the above example, 32 gradations were illustrated, but in the case of 16 gradations, the above-mentioned equally spaced density step is set to 0.1, and the conversion table assigned to the total number of recorded data of 16 gradations is 100. Just create it.

Table 1 Table 2 Also, what is shown in FIGS. 8 to 10 is the number of gradations that can reproduce the number of gradations of input image data.

That is, it is a diagram showing the relationship between the recording pulse width used when the number of recording pulses is larger than the number of recording data and the density. In this way, when the number of gradations of the input image data is larger than the number of recorded data, the respective densities of Y, M, and C corresponding to a certain gradation cylinder of the input image data are calculated based on these figures. The calculated data is recorded as recorded data, and this recorded data is stored in each conversion table. In calculating this recording data, since the number of gradations of the input image data is larger than the number of reproducible gradations, each recording pulse is calculated for each color as shown in FIGS. 8 to 10. The density is determined according to the width, and the number of gradations of the input image data is assigned so that the density becomes the center. In other words, the number of gradations of image data is determined according to each recording pulse width. Specific numerical values showing the relationship between the number of gradations (input data) of the image data obtained in this way and the density are shown in Table 2 described below.

As shown in this table, for example, if the number of gradations in the input image data is 150, the density of yellow and magenta is 1.00. The density of the cyan color is 0°96, and each recorded data is 19.9° for yellow and magenta. Cyan becomes 20. The relationship between the recording data for each color thus determined and the recording pulse width of the voltage applied to the recording head is determined as follows. First, the recording pulse width when the density of each color becomes 1.6 is determined based on FIGS. 8 to 10. When this is actually determined, the recording pulse width when the yellow color density is 1.6 is 8°5 ms, and the recording pulse width when the magenta color density is 1.6 is 9.411.
1 s, the recording pulse width when the cyan color density is 1.6 is 10.0 ms, so this is divided by 31. That is, in this embodiment, since the number of gradations is 32, these four recording pulses are divided by 31.

The recording pulse width of one gradation for each color determined in this way is 274 μs for yellow and 303 μs for magenta.
s, and cyan is 323 μs. Therefore, in order to reproduce the desired density of each color described above, the recording data determined in Table 2 is multiplied by the recording pulse width for one gradation determined as above, and this pulse width is h. All that is required is to apply a voltage to the recording head.

For example, if the number of gradations of the input image data is 150 as illustrated above, the density of yellow and magenta is 1.00. The density of cyan color is 0.
96, and each recording data is 19.9 for yellow and magenta. Since cyan is 20, the pulse width of the voltage applied to the recording head when reproducing the color yellow is 19 x 274 μs = 5.206 m5, and the pulse width of the voltage applied to the recording head when reproducing the color magenta is 19 x 274 μs = 5.206 m5. The pulse width of the applied voltage is 19 x 303 μs = 5.757 m
5, and the pulse width of the voltage applied to the recording head when reproducing cyan color is 20×323 μs = 6.
It will be 46m5.

In this way, when the number of gradations of the input image data is larger than the number of gradations that can be reproduced, the number of gradations of the input image data is set at equal intervals relative to the recording pulse width, that is, the recording energy. is assigned to. In other words, the recording data stored in the conversion table is such that the number of gradations of the input image data is linear with respect to the density corresponding to the recording energy. However, the maximum value of the recording energy division range is set to the recording energy where the maximum density of each color of Y, M, and C is the same. In other words, the combined color is achromatic black (1.6 in this embodiment). Furthermore, since the number of gradations of the input image data is assigned to the density according to the recording pulse width, the image can be reproduced accurately within the limit of the number of gradations that can be reproduced.

As described above, when the number of gradations of input image data is smaller than the number of reproducible gradations, the recording data to be stored in the conversion table of the multi-gradation thermal transfer recording device according to the present invention is If the number is large, a device is used to convert the large number of gradations into a reproducible number of gradations. Therefore, in either case, the smaller number of gradations is set at equal intervals, making it possible to form an image using the smaller number of gradations.

FIG. 11 is a diagram showing details of the vicinity of the head control section shown in FIGS. 1 to 3.

In this figure, comparator 10. Line buffer address generation counter 11. The clock generation circuit 12 is connected to the line buffer 2 described above.

The data converted by the conversion table 1 output from the line buffer 2 is input to the comparator 10, and is compared with the data output from the comparison data counter 13. Reading of data from the line buffer 2 is performed using a read pulse outputted from a clock generation circuit 12 and an address specified by a line buffer address generation counter 11. As a result of the comparison by the comparator 10, if the data output from the comparison data counter 13 is smaller than the data output from the line buffer 2, the data output from the line buffer 2 is output to the recording head side and latched. Ru. As shown in FIG. 12, the data output from the comparison data counter 13 is initially reset by the input of the 1-line print signal, so every time the latch signal is input, the data is 0 to 3.
Up to 1 is output. Along with this, the comparator 1o outputs 31 or more data each time a latch signal is input, such as 1 or more data at first, 2 or more data when the first latch signal is input, and so on. Data is sequentially output to the recording head side. In this way, one line of data is output in synchronization with the clock signal output from the clock generation circuit 12. Here, FIG. 13 shows data transfer and recording for − times.

This latch belief is output from the control section 4, and this signal is also output to the strobe timing circuit 14. The strobe timing circuit 14 also receives a one-line print signal output from the control section 4. The strobe timing circuit 14 outputs a strobe signal from when both the 1-line print and the first latch signals are output until the 1-line print signal is output. When this strobe signal is output, a voltage latched for each heating element is applied to each of the heating elements 20A to 2ON as image forming means constituting the recording head.

In this way, a predetermined amount of thermal energy is output from each heating element that makes up the recording head for a time equal to the product of the latch period and the recording data that is the output data from the line buffer γ, resulting in a predetermined density. The image will be output regardless of the number of gradations in the input image data.

As described in 2 below, in this embodiment, if the number of gradations of the input image data is smaller than the number of reproducible gradations, the recorded data will have the same density for each color of Y, M, and C. Therefore, when three colors are superimposed at all gradations, an achromatic color is obtained, and this is independent of the number of gradations. Furthermore, if the number of gradations in the input image data is greater than the number of reproducible gradations, the recorded data will not have equal density.

In other words, even if the recorded data is the same, Y, M, C
Since the density of each color is different, some colors will not be achromatic, but as the number of gradations increases, the color will become achromatic, that is, closer to gray.

Note that the apparatus of the embodiment may selectively use a plurality of conversion tables created by the method described above, depending on the number of gradations of input image data.

As is clear from the explanation in 2. Effects of the Invention, in the multi-tone thermal transfer recording device of the present invention, when the number of gradations of input image data is smaller than the number of gradations that can be reproduced, Since the recording energy to be output to the image forming means is controlled in accordance with the number of gradations of the image data, each color has a linear density characteristic, and the balance when combining each color is good, so gray , good black reproducibility. Furthermore, it is possible to deal with changes in the ink film or changes in its characteristics by simply changing the recorded data to be stored in the storage means, without changing any hardware such as circuitry. That is, since the parts that depend on the ink film are separated, there is no need to consider the characteristics of the ink film when designing the device. Also, unlike color correction using a matrix, data for the required number of colors is not required at the same time, which is very advantageous for inexpensive printing apparatuses.

Furthermore, in the multi-tone thermal transfer recording device of the present invention, when the number of gradations of the input image data is larger than the number of gradations that can be reproduced, the multi-gradation thermal transfer recording device is configured to correspond to a predetermined gradation width of the image data. Since the recording energy to be output to the image forming means is controlled, even if the image data has a large number of gradations, it is possible to reproduce the image. Furthermore, changes in the ink film or changes in characteristics can be dealt with only by changing the recorded data to be stored in the storage means, without changing any hardware such as circuitry. That is, since the parts that depend on the ink film are separated, there is no need to consider the characteristics of the ink film when designing the device. Also, unlike color correction using a matrix, data for the required number of colors is not required at the same time, which is very advantageous for inexpensive printing apparatuses.

[Brief explanation of the drawing]

1 to 3 are schematic configuration diagrams showing various aspects of the control part in the multi-tone thermal transfer recording apparatus according to the present invention, and FIG. 4 shows the relationship between recording energy and density of the ink film in the shell. Figures 5 to 7 are diagrams used to calculate recording data for each color when the number of gradations of input image data is smaller than the number of reproducible gradations, and Figures 8 to 10 are diagrams used to calculate recording data for each color. The figure is a diagram used to calculate the recorded data for each color when the number of gradations of input image data is larger than the number of reproducible gradations. The configuration diagrams around the head control section, FIGS. 12 and 13, are timing charts showing the operation timings of the respective parts constituting the control section shown in FIG. 1. IA~ID...conversion table (storage means), 2.
...Line buffer, 3.Head control section, 4.Control section (control means) 20A~2ON...Heating element (image forming means)

Claims (2)

[Claims] (1) A multi-tone thermal transfer recording device that inputs image data and forms a multi-tone color image based on the image data, comprising an image forming means that forms a color image on a recording medium by thermal transfer; storage means for storing recording energy to be outputted to the image forming means as recording data for each color in correspondence with the number of gradations of input image data; and a number of gradations at which the number of gradations in the input image data can be reproduced. If it is smaller than
A multi-gradation thermal transfer recording apparatus comprising: a control means for controlling recording energy applied to the image forming means based on recording data stored in the storage means. (2) A multi-tone thermal transfer recording device that inputs image data and forms a multi-tone color image based on the image data, comprising an image forming means that forms a color image on a recording medium by thermal transfer; storage means for storing recording energy to be outputted to the image forming means as recording data for each color in correspondence with a predetermined gradation width of input image data; and a number of gradations that can reproduce the number of gradations in the input image data. 2. A multi-gradation thermal transfer recording apparatus comprising: control means for controlling the recording energy applied to the image forming means based on the recording data stored in the storage means when the recording energy is larger than the recording data stored in the storage means.