JPH0315565A - Thermal transfer recorder - Google Patents

Abstract

PURPOSE:To obtain a stable photographic printing result without depending upon variation in temperature by a method wherein an electrification data calculating means reads a representative electrification data of a specific temperature near a detected temperature from a memory by a temperature detection means, calculates an actual electrified time data conforming to temperature in photographic printing, and electrification to a thermal head is performed. CONSTITUTION:An electrification data calculating means 3 receives a temperature data from a temperature sensor 6 fitted onto a thermal head 5, further reads a necessary data from a gradation ROM 4 according to a gradation number and the temperature data, and calculates an electrified time data. In photographic printing, an image signal having gradation information in a light and shade direction per each pixel of the image from an image signal source 1 is inputted to a middle tone control means 2. The middle tone control means 2 receives the electrified time data of the thermal head 5 according to the gradation number to be outputted from the electrification data calculating means 3, and sends a strobe signal of a time width corresponding to this electrified time data to be thermal head 5. The thermal head 5 makes a current flow to a heating element 7 by a time width of the inputted strobe signal, and the heating element 7 is heated correspondingly thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording device for printing images with gradation, such as a video printer.

[Conventional technology]

In thermosensitive gradation recording, the relationship between the power supply time to the heating element and the color density is generally not linear, but as shown in Figure 15, there is a constant increase in density between low density areas and high density areas. The amount of increase in the energization time required for F becomes large. Therefore, in order to record an image signal representing an image with gradations so that the image appears faithfully, it is necessary to change the energization time non-linearly depending on the gradation.

In the conventional thermal transfer recording device, Japanese Patent Application Laid-Open No. 574886
As described in Publication No. 8, data representing the nonlinear relationship between gradation and energization time is stored in advance in a ROM (read-only memory) as a reference signal, and a reference signal corresponding to the gradation is stored in this ROM. A method is known in which the reference signal is read from the reference signal and the energization time of the heating element is controlled in accordance with this reference signal.

To explain this in more detail, when the number of heating elements is 7 and the gradations are 8 from O to 7, 8 different reference signals are stored in advance in the ROM. All of these reference signals have the same number of constituent bits, and in the case of 8 gradations, each reference signal consists of 9 bits, but the ratio of 3-4 ``1'' bits to ``O'' bits is different from each other. The two reference signals are composed of all "0" bits. In this way, these eight reference signals correspond one-to-one to each of the eight gradations, and assuming that the reference signal for the lowest density of the image corresponds to the reference signal with all bits "0", The maximum density of the image corresponds to the reference signal with the largest number of "l" bits, and the other reference signals correspond to I
It corresponds to an intermediate density depending on the number of NF\bits.

The gradation code signals for each heating element are sequentially supplied to the ROM, the first bit of the reference signal corresponding to each gradation code signal is read out from the ROM, and the first bit of the reference signal corresponding to each heating element is The bit of is stored in the cell corresponding to this heating element of the latch circuit. In this way, when the first bit of the reference signal corresponding to all the heating elements is stored in each cell of the latch circuit, the corresponding heating element is driven according to the bit stored in this latch circuit. Only the heating element driven by the "1" bit is energized for a predetermined period of time to perform printing.

When this energization is completed, the above operation is performed on the next bit of the reference signal in the ROM, and thereafter the above operation is performed on each bit in turn. In this way, in the case of 8 gradations, each reference signal consists of 9 bits, so
Reading from the ROM for each heating element is performed nine times, and among these nine readings, the heating element is energized only the number of "1" bits of the reference signal for the gradation code signal. Therefore, the density of a pixel of a printed image that is affected by the energization of the heating element varies depending on the number of energizations, and a multi-gradation image is printed.

[Problem to be solved by the invention]

By the way, in a thermal transfer recording device, as shown in FIG. 16, even if the current application time is the same, the color density differs depending on the temperature of the heating element. Therefore, when printing is started, heat accumulates around the heating element over time, and the temperature of the heating element rises.

For this reason, when printing begins, the temperature of the heating element is low so that it is thin (i.e., suitable)? ! The image is printed once, but the density increases over time.

In this way, it is not possible to always obtain prints with constant density.

Furthermore, in order to obtain color prints, for example, when printing is performed three times using three types of recording media: yellow for the first color, magenta for the second color, and cyan for the third color, as shown in Figure 17. Furthermore, it is known that the characteristics of color density with respect to current application time differ depending on the recording medium. Moreover, when printing a color image using a recording medium of a different color material, as shown in FIG. 18, the image is recorded at a density different from the original design, and a normal recording density cannot be maintained. Therefore, significant restrictions are placed on the recording medium.

In order to prevent these problems, it would be possible to provide data representing the characteristics of energization time versus concentration for each recording medium, but this would require a very large memory capacity to store this data, making it impractical. Not.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal transfer recording device that eliminates such problems, prevents the influence of temperature changes on print density, and can significantly reduce the amount of data used.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a memory storing reference energization time data representing the energization time for each of a plurality of specific gradations at each of one or more specific temperatures set in advance; Temperature detection means for detecting temperature and outputting temperature data representing the temperature, and reading reference energization time data corresponding to the temperature data from the memory and calculating the energization time for each gradation with respect to the temperature of the thermal head. and energization data calculation means for calculating the actual energization time data represented.

Further, the present invention provides means for storing reference energization data corresponding to the coloring material of the ink paper in the memory and detecting the type of the coloring material of the ink paper used for printing.

[For production]

Using the temperature detection means provided in the thermal head, the energization data calculation means reads representative energization data at a specific temperature 78 times closer to the detected temperature from the memory, and calculates actual energization time data according to the temperature of the thermal head at the time of printing. Based on this, the thermal head is energized. Therefore, stable printing results can be obtained regardless of temperature changes, and the amount of data stored in the memory can be reduced. Further, since the amount of data is reduced in this way, data for other ink color materials having different printing density characteristics can be stored in the memory.

In addition, since the ink selection means also obtains information on the ink coloring material, the energization data calculation means selects and reads representative energization time data suitable for the coloring material of the ink paper used from the memory, and calculates the actual energization time. Since we calculate the data,
Even if the ink color materials are different, uniform printing results can be obtained.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a thermal transfer recording apparatus according to the present invention, in which 1 is a video signal source, 2 is a halftone control means, 3 is an energization data calculation means 4 is a gradation ROM, and 5 is a thermal 6 is a temperature sensor, 7 is a heating element, 8 is a drum, and 9 is ink paper 10 is a recording paper.

In the same figure, the energization data calculation means 3 uses a temperature sensor attached to the thermal head 5 before the recording paper 10 and the ink holder 9 are conveyed to a predetermined recording position or before recording starts. Receive temperature data from 6,
Further, necessary data, which will be described later, is read out from the gradation ROM 4 according to the gradation number and temperature data, and energization time data is calculated.

During printing, an image signal having gradation information in the gradation direction for each pixel of the image is manually inputted from the image signal source 1 to the halftone control means 2. The halftone control means 2 receives the energization time data of the thermal head 5 corresponding to the gradation number output from the energization data calculation means 3, and sends a strobe signal to the thermal head 5 with a time width corresponding to this energization time data. .

The thermal head 5 passes a current through the heating element 7 for the time width of the manually inputted strobe signal, and the heating element 7 generates heat in response to this.

9 10 A recording paper 10 is wound around the circumferential surface of the drum 8 , and an ink paper 9 is stacked on top of the paper paper 9 and pressed by the thermal head 5 . The amount of heat generated by the heating element 7 changes according to the energization time specified by the halftone control means 2, and ink corresponding to the amount of heat generated is transferred from the ink paper 9 to the recording paper 10. Thereby, controlled halftone recording is performed.

FIG. 2 shows the 1 stored in the gradation ROM 4 in FIG.
An example of energization time data for colored ink is shown.

In Fig. 2, the curve vAA indicated by a circle, the curve B indicated by a Δ mark, and the curve C indicated by an x mark represent three different typical temperatures (for example, 50°C. 35°C. 20°C), respectively.
Typical gradations when the voltage applied to the thermal head 5 is constant (for example, 3, 7, 11, 15, 19,
31, 43, 55, and 63 floors m> and the relationship between current application time data, and each curve is designed in advance to have the same gradation vs. density characteristic at each temperature.

FIG. 3 is a flowchart showing an example of the energization time calculation operation of the energization data calculation means 3 in FIG. 1. Hereinafter, the detailed operation of this embodiment will be explained using FIG. 3.

1 to 3, when a printing command is issued, the temperature sensor 6 detects the temperature of the thermal head 5, and the detected temperature T. Temperature data representing the temperature is supplied to the energization data calculation stage 3 (step 301). Among the representative temperatures stored in the gradation ROM 4, T. <T, <T, the maximum representative temperature T. and the minimum representative temperature T, (where T n ) is specified (step 302). This means that the detected temperature TL is inscribed to identify two adjacent curves in FIG.゜C
, 20°C, and the detected temperature T is, for example, 40°C.
℃, T,=35℃〈40゜C〈Tn=50℃ The curves A and B are targeted for this detected temperature.

That is, step 302 is for specifying the target gradation versus energization time characteristic curve.

The gradation vs. energization time characteristic curve 11 12 with respect to the detected temperature T is the curve A. in FIG. It is between B. Next, energization time data for the representative gradation on this characteristic curve is determined.

That is, first, curve A. Representative energizing time data for B. D. , D (however, D7<D.) is specified (step 303). Then, the identified representative energization time data D,,D,, is divided into a predetermined number of temperature width steps (for example, 4 steps), and the energization time data is calculated for each increment of one temperature width step. Increment ΔD−
is calculated (step 304).

Next, the detected temperature T. Depending on the temperature range stage to which it belongs (for example, the third from the representative temperature T7),
Increment ΔD + from energization time data D at a certain representative gradation
Subtract 1 times 1111, or D.

3ΔD IThfi is added to the energization time data to calculate the energization time data at a representative gradation with a temperature range step including the temperature T detected by the temperature sensor 6 (step 305
).

Have you repeated the steps 303 to 305 in FIG. 3? By returning the data, energization time data at all representative gradations is calculated (step 306).

Next, among the energization time data at the representative gradation calculated in step 305, the energization time data S at the adjacent representative gradation
(2), S, l (where Sm <Sn) is specified (step 307). Then, the specified energization time data S.
.

After that, ΔS is added to the energization time data S1 at a certain representative gradation.
By adding an integer multiple of (1) (this integer is 1 to 3), the energization time data in the gradation between the energization time data S, , Sn is calculated. As described above, the processes of steps 307 to 309 are repeated until all the energization time data are calculated (step 310), and as a result, the temperature T. of the thermal head 5.
The energization time data (hereinafter referred to as actual energization time data) at all gradations corresponding to the current energization time data is calculated.

In the case of color printing, data 13 to 14 are similarly stored in the gradation ROMA as shown in FIG. Actual energization time data is calculated according to the detected temperature data.

As a result of the above, the optimum actual energization time data can be determined according to the temperature of the thermal unit 5, so that printing with constant gradation to density characteristics can be performed regardless of the environmental temperature or the number of continuous prints. . Furthermore, since the representative energization time data in the gradation ROMA is composed of representative values for each temperature and gradation, the amount of data stored in the gradation ROM 4 can be reduced, and the capacity of the gradation ROM 4 can be reduced. For example, if the temperature range is divided into 16 steps at 3°C intervals starting from 15°C, the data for 3 colors and 64 gradations would be 16x3.
X64 = 3072 pieces. On the other hand, in this embodiment, the temperature is in three stages, and among the 64 gradations as representative gradations,
0,7 3, 7, 11, 15, 23. 31
, 39, 47, 55. Therefore, the number of data stored in the gradation ROM 4 is 3 x 3 x 10 = 90, which reduces the amount of data to about 1/34 of the above case.

Note that in halftone recording, density changes in the low-density region and the high-density region are nonlinear, so fine control is required.

Furthermore, since changes in density in a low density area are visually sensitive to changes in density in a high density area, so-called false contours are likely to occur, requiring more precise control. In the data structure shown in Fig. 2, representative data is increased in the low density area, that is, at low gradations. By taking a representative gradation at every interval, density changes in the low density region can be controlled more precisely. In general, the representative gradations to be stored are every NllW tone (however, N>1, an integer) in the high density area, and every M gradations (an integer) in the low density area, then N>M. is desirable.

Further, when the energization data calculation means 3 is composed of a microcomputer, the calculation time can be shortened by setting both N and M to be a multiple of 2 or a power of 2.

FIG. 4 shows another specific example of the representative energization time data stored in the gradation ROM 4 in FIG.

In the same figure, Kl, K2, K3, K4, K5
．． K6, K7, K8, K9, KIO are representative gradations (for example, 3, 7, 11, 15.23, 31
, 39, 47, 55.63 gradations). width steps) are set in advance so that the gradation versus density characteristics of the printing results at each temperature are constant.

The operation according to this flowchart will be explained below.

In FIG. 5, when the temperature of the thermal head 5 is detected by the temperature sensor 6 in response to a printing command, the detected temperature T. Temperature data corresponding to the temperature data is supplied to the energization data calculation stage 3 (step 50l).

Then, from among the representative energization time data stored in the gradation ROM 4, a temperature range stage TD including the detected temperature Ti is specified (step 502).

For this specified temperature width stage To, among the energization time data at representative gradations set in advance, energization time data S. , SL (where Sk<SL) are specified (step 503). The identified representative energizing time data S, SL is divided into a preset number of gradations (for example, 4), and an increment Δ311 of energizing time data corresponding to a data increment of one gradation is calculated (step 50
5). Then, a value that is an integral multiple (for example, 1 to 3 times) of the increment ΔSkL is calculated for the energization time data S at a certain representative gradation, and actual energization time data at the gradation between SkrSkL is calculated.

As described above, by repeating the processing of steps 503 to 505 for each gradation, actual energization time data at all gradations is calculated according to the A degree Tt of the thermal head 5.

In the case of color printing, data for the second and third colors as shown in FIG. Prints with constant gradation and density characteristics are produced regardless of the environmental temperature or the number of consecutive prints. Furthermore, the amount of data stored in the gradation ROM 4 can be reduced compared to the case where data for all temperature range steps and all gradations is held in advance. For example, 3 colors, 64 gradations,
In the case of 16 temperature width stages, the number of data is 3×6 compared to the conventional
3 x 10 x 16 = 48 compared to 4 x 16 = 3072 pieces
This can be reduced to approximately 1/6 of 0.

In addition, in FIG. 4, as well as the data structure shown in FIG. 2, by taking a large amount of representative data at low gradations,
Concentration changes in the low concentration range are more precisely controlled.

FIG. 6 shows still another specific example of the representative energization time data for ink stored in the gradation ROM 4 in FIG. 1.

In FIG. 6, Tl. T2 and T3 are representative energization time data when the applied voltage is kept constant at representative temperatures (e.g., 50°C, 35°C, 20°C), and each data is for all gradations (e.g., 64°C). There are gradations.

FIG. 7 is a flowchart showing an example of an operation for calculating actual energization time data using the characteristics shown in FIG.

This operation will be explained in detail below.

In response to the print command, the temperature sensor 6 detects the temperature of the thermal head 5, and the detected temperature T. The temperature data corresponding to
). Then, from among the representative energizing time data stored in the gradation ROM 4, the representative temperatures Tk and TtD, including the detected temperature T8, are divided into preset temperature width steps (for example, 4). Then, an increment ΔDkL of the energization time data corresponding to an increment of one temperature width step is calculated (step 704). Next, the detected temperature T. of the thermal head 5. l of ΔDkl from D at a certain gradation depending on the temperature range stage to which it belongs (for example, 19 20 3rd from TL)
or ΔD0 to the representative energization time data D,
, and calculates actual energization time data at a certain gradation of the temperature range step (step 705).

By repeating the operations of steps 703 to 705, actual energization time data at all gradations is calculated.

In the case of color printing, data for the second and third colors as shown in FIG. Calculate the actual energization time data.

FIG. 8 shows still another specific example of the representative energization time data for color printing stored in the gradation ROM 4 in FIG.

In FIG. 9, Yl, Y2, and Y3 are representative energizing time data for yellow when the applied voltage is kept constant at typical temperatures (for example, 50°C, 35°C, and 20°C), respectively. , each data has all the floors tlM (for example, 6
4 gradations) are provided.

FIG. 9 is a flowchart showing an example of an operation for calculating actual energization time data at an arbitrary temperature from the representative energization time data shown in FIG. 8, and this operation will be described in detail below.

In response to the print command, the temperature sensor 6 detects the temperature of the thermal head 5, and temperature data corresponding to the detected temperature T is supplied to the energization data calculation stage 3 (step 1001).
, floor! From among the representative energizing time data stored in the ROM4, a preset representative temperature T,, T9 that defines a range including the detected temperature 'ri (however, Tr<'re)
(Step 1002). Then, representative energization time data t) r, D for a certain gradation set in advance
*(where D,>D,) is specified (step 1003)
, these identified representative energization time data D,,D, are divided into preset temperature width steps (for example, 4),
Increment ΔDf. of energization time data corresponding to an increment of one temperature width step. (Step 1004). After that, the temperature range 2 that includes the detected temperature T of the thermal head 5 is
l 22 Depending on the stage (for example, the third from T.), subtract 1 times ΔDfg from the representative energization time data D at a certain gradation,
Alternatively, three times ΔD, , is added to the representative energization time data D9 to calculate actual energization time data at a certain gradation in this temperature range step (step 1005).

By repeating the steps 1003 to 1005, the actual energization time data for all yellow gradations is calculated (step 1006).

Next, the coefficient k stored in advance in the floor 11 ROM 4 is added to the actual energization time data at a certain gradation of yellow calculated as described above. , and thereby calculates magenta actual energization time data (step 1007). here,
Coefficient k. is expressed by a ratio (magenta energization time data/yellow energization time data) having a gradation-density characteristic designed in advance.

By repeating the process of step 1007, actual energization time data for all magenta gradations is calculated (step 1008).

Once magenta energization time data is calculated in this way, cyan actual energization time data is calculated by multiplying the actual energization time data at a certain gradation of yellow by a coefficient kc (step 1009). .

Here, the coefficient kc is expressed as a ratio (cyan energization time data/yellow energization time data) having a gradation-density characteristic designed in advance. By repeating the operation of step 1009, cyan actual energization time data at all gradations is calculated (step 1010).

As a result of the above, the gradation ROM 4 contains representative energization time data Yl, Y2, Y3 at typical yellow temperatures and coefficient K. ，
Only Kc is stored, yellow magenta,
Compared to storing all the data for each cyan,
The number of data stored in the floor 31 ROM 4 can be significantly reduced.

In this example, the actual energizing time data of magenta and cyan were calculated from the actual energizing time data of yellow, but instead of yellow, the actual energizing time data of other colors was calculated from the actual energizing time data of magenta or cyan. It may be calculated.

23 24 FIG. 10 shows still another specific example of the representative energization time data for color printing stored in the gradation ROM 4 in FIG. The graph shows representative energization time data for each gray level of yellow when the applied voltage is kept constant at (for example, 35° C.).

FIG. 11 is a flowchart showing an example of an operation for calculating actual energization time data at an arbitrary temperature from the data structure shown in FIG. 10, and this operation will be described in detail below.

In response to the printing command, the temperature sensor 6 detects the temperature of the thermal head 5, and the detected temperature T! Temperature data corresponding to is supplied to the energization data calculation means 3 (step 1101
). Next, the coefficient ki that determines the temperature range step stored in the gradation ROM 4 is specified (step 1102). Here, the coefficient k, is a coefficient set in advance at constant temperature intervals (for example, every 3 degrees Celsius), and is composed of, for example, j = 1 to 16, and k, -k is a representative value indicated by a circle. If the temperature is lower than (k, > 1, j = 1~8.k, ~k8), k9~k
l6 is higher than the representative temperature (0<kj<1, j=
9 to 16, kq > k, b), and the coefficient k to which the temperature data belongs is specified. Next, the representative energizing time data at a certain gradation at the representative temperature is multiplied by a coefficient k to calculate actual energizing time data corresponding to the detected temperature data (step 1103). By repeating the above operations, actual energization time data for all gradations of yellow is calculated (step 1104). Next, actual energization time data for magenta is calculated by multiplying the calculated actual energization time data for a certain gradation of yellow by a coefficient k stored in advance in the floor 11 ROM 4 (step 1105). Here, the coefficient k. is expressed as a ratio (magenta energization time data/yellow energization time data) having a gradation-to-density characteristic designed in advance. This processing operation is repeated for each gradation to calculate actual magenta energization time data at all gradations (step 1106).
).

Also, in the same way as in step l105, the actual energizing time data for a certain gradation of yellow is multiplied by the coefficient kc to calculate the actual energizing time data for cyan 25 to 26 (step 1107).
). Here, the coefficient kc is expressed as a ratio (cyan energization time data/yellow energization time data) having a gradation-to-density characteristic designed in advance. By repeating this processing operation for each gradation, cyan actual energization time data for all gradations is calculated (step 110B).

As described above, in this specific example, the floor i111ROM4 has the representative energization time data Y at the yellow representative temperature and the coefficient kj
(j=1 to 16), it only has k,,kc,
The number of data stored in the gradation ROM 4 can be significantly reduced compared to the case where yellow, magenta, and cyan data are respectively stored.

In this specific example, the actual energizing time data of magenta and cyan were calculated from the actual energizing time data of yellow, but the actual energizing time data of other colors can also be calculated from the actual energizing time data of magenta or cyan instead of yellow. can be calculated in the same way.

FIG. 12 is a block diagram showing another embodiment of the thermal transfer recording apparatus according to the present invention, in which 11 is a RAM (random access memory), and parts corresponding to those in FIG. 1 are given the same reference numerals.

As shown in the figure, this embodiment is obtained by adding RAMII to the embodiment shown in FIG. In the embodiment shown in FIG. 1, the actual energization time data calculated as described above by the energization data calculation means 3 are all read by the halftone control means 2, but in FIG. Accordingly, the data is temporarily stored in RAMII, and the actual energization time data is read from RAMII by the halftone control means 2 at the time of printing.

The other parts are the same as the embodiment shown in FIG. 1, and the calculation methods shown in FIGS. 2 to 11 can be used.

FIG. 13 is a block diagram showing still another embodiment of the thermal transfer recording apparatus according to the present invention, in which reference numeral 12 denotes coloring material detection means;
13 is a switch, 14 is an ink type designation means,
Components corresponding to those in FIG. 1 are given the same reference numerals and redundant explanations will be omitted.

In FIG. 13, the coloring material detection means 12
7 28 Alternatively, from an ink cassette (not shown) that holds this ink paper 9, the type of coloring material of the ink paper 9 to be used is determined by optical or mechanical means, and the type information of this coloring material is output. . Further, the ink type designation means l4
It is possible to specify any type of ink, and information representing the color material of this ink is output. Either one of the color material type information from the color material detection means 12 or the ink type designation means 14 is selected by a switch 13 and supplied to the energization data calculation means 3.

Here, the gradation ROM 4 contains data as shown in FIG. FIG. 4 Multiple sets of representative energization time data at representative gradations shown in FIG. 6, FIG. 8, or FIG. 10 are stored for different color materials.
The energization data calculation means 3 selects representative energization time data from the gradation ROM 4 corresponding to the color material type information obtained from the color material detection stage 12 or the ink type designation means 14.

Hereinafter, the operation of calculating the actual energization time data by the energization data calculation means 3 is the same as that in the embodiment shown in FIG. 1, so the explanation thereof will be omitted here.

The recording paper IO used in thermal transfer recording devices includes plain paper, synthetic paper, OHP paper, etc.
For this purpose, ink paper 9 with a different coloring material is used. Also, depending on the type of image signal source 1, the halftone expression of the ink paper 9 used may change (for example, smooth halftone control is required for natural images, and CAD,
(For CG images, etc., sharp halftone control is required.)

Further, even when using the same ink paper 9, the halftone expression may change depending on the type of recording paper 10 used.

In order to satisfy the above conditions, data is required for each condition, and the amount of data becomes enormous. On the other hand, the typical energization time data of the configuration shown in FIG. 2, FIG. 4, FIG. 6, FIG. 8, or FIG.
This has the effect of reducing the number of data stored in OM4. Therefore, representative energization time data regarding multiple sets of different color materials can be stored in the gradation ROM 4 due to this reduction. can be used.

FIG. 14 is a block diagram showing still another embodiment of the thermal transfer recording apparatus according to the present invention, in which 15 is a microcomputer, 16 is an energization data calculation section, 17 is a data storage section, and 18 is an A/D (analog/ The parts corresponding to those in FIG. 1 are given the same reference numerals and redundant explanations will be omitted.

In this embodiment, a microcomputer is used in place of the energization data calculation means 3 and the gradation R OM 4 in FIG.

In FIG. 14, the microcomputer 15 is provided with an energization data calculation section 16 and a data storage section 17. The data storage unit 17 stores representative energization time data shown in FIG. 2, FIG. 4, FIG. 6, FIG. 8, or FIG. 10. The energization data calculation unit 16 takes in temperature data of the thermal head 5 from the temperature sensor 6 attached to the thermal head 5 via the A/D converter 18, and reads the temperature data from the data storage unit 17 according to the gradation number and this temperature data. Read the necessary data and calculate the actual energization time data.

At the time of printing, an image signal having gradation information in the gradation direction for each pixel of the image is supplied from the image signal source 1 to the halftone control means 2. The halftone control means 2 takes in data on the energization time for the thermal head 5 corresponding to the gradation number output from the microcomputer 15, and sends a strobe signal to the thermal head 5.

As described above, this embodiment also provides the same effects as the embodiment shown in FIG. 1.

〔Effect of the invention〕

As explained above, according to the present invention, one or more temperatures are used as representative temperatures, and the print density characteristics of the ink coloring material with respect to the representative temperatures are used, and the print density characteristics of the representative temperature corresponding to the detected temperature of the thermal head are calculated. Since the print density characteristics are obtained at the detected temperature, it is only necessary to store the data of the print density characteristics for these representative temperatures in the memory, and store the data of the print density characteristics for all temperatures of the thermal head. The amount of data stored in the memory is significantly reduced compared to the case where the image is stored in the memory, and moreover, stable halftone expression of the image is possible regardless of the temperature of the thermal head.

In addition, by reducing the amount of data stored in ROM for one ink color material, it is possible to store similar print density characteristic data for each different ink color material in memory, and for each type of ink color material. Data on printing density characteristics at any temperature with a thermal head can be obtained, making it possible to print images suitable for ink color materials.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a thermal transfer recording device according to the present invention, FIG. 2 is a diagram showing a specific example of data stored in the gradation ROM in FIG. 1, and FIG. Flowchart 1 showing the operation of the energization data calculation means in FIG. 1 for the data shown in FIG. is a flowchart showing the operation of the energization data calculation means in FIG. 1 with respect to the data shown in FIG. 7 is a flowchart showing the operation of the energization data calculation means in FIG. 1 for the data shown in FIG. 6, and FIG.
A diagram showing still another specific example of data stored in OM,
FIG. 9 is a flowchart showing the operation of the energization data calculation means in FIG. 1 for the data shown in FIG.
0 is a diagram showing still another specific example of the data stored in the gradation ROM in FIG. 1, and FIG. 11 is a flowchart showing the operation of the energization data calculation means in FIG. 1 for the data shown in FIG. 10. , FIGS. 12 to 14 are block diagrams showing other embodiments of the thermal transfer recording apparatus according to the present invention, and FIG. 15 is a characteristic diagram showing the relationship between the energization time of the heating element and the color density in thermal gradation recording. , FIG. 16 is a diagram showing changes in color density depending on the temperature of the heating element, FIG. 17 is a diagram showing color density for recording media of different colors, and FIG. 18 is a diagram showing changes in color density for recording media of different color materials. FIG. 3 is a diagram showing color density. 33 34 2... Halftone control means, 3... Energization data calculation means, 4... Floor 11 Jil R O M, 5... Thermal head, 6... Temperature sensor, 9... Ink paper ,1
0... Recording paper, l1... RAM, 12... Color material detection means, 14... Ink type designation means. 3 5- 2nd figure 4 figure 5 figure 7 figure 6 figure tone 8 figure P'lr key 10 figure 11 figure 387- figure 16 figure 17

Claims (1)

[Claims] 1. A thermal head is brought into contact with an ink paper stacked on a recording paper, a heating element of the thermal head is made to generate heat by applying electricity, and the heating element is transferred to the ink paper according to the duration of electricity application. In a thermal transfer recording device that performs gradation recording on the recording paper by changing the amount of heat applied to the recording paper, a representative value representing the energization time for each of a plurality of specific gradations at one or more preset specific temperatures. a memory storing energization time data, a temperature detection means for detecting the temperature of the thermal head and outputting temperature data representing the temperature, and reading from the memory representative energization time data in accordance with the temperature data of the thermal head. energization data calculation means for calculating actual energization time data without representing the energization time for each gradation for the temperature of the thermal head at each gradation based on the calculated actual energization time data; 1. A thermal transfer recording device, characterized in that it is configured to be capable of compensating for fluctuations in gradation recording characteristics due to temperature changes in the thermal head by setting the energization time. 2. In claim 1, the representative energization time data consists of data representing the energization time for every N (where N>1 is an integer) gradation in the high density region, and M (however, M
1. A thermal transfer recording device comprising data representing energization time for every other gradation (<N is an integer). 3. The thermal transfer recording apparatus according to claim 2, wherein both N and M are multiples of 2 or powers of 2. 4. In claim 1, 2 or 3, the representative energization time data for each of the ink papers of different colors is stored in the memory, and the energization data calculating means calculates the data from the representative energization time data corresponding to each of the ink papers. A thermal transfer recording device, characterized in that the actual energization time data is calculated. 5. In claim 4, representative energization time data corresponding to the color material of the ink paper is stored in the memory, and means for detecting the type of color material of the ink paper used for printing is provided, A thermal transfer recording apparatus, characterized in that actual energization time data for the ink paper is calculated from representative energization time data corresponding to the coloring material. 6. According to claim 1, 2 or 3, printing is performed using K (where K is an integer) types of ink paper of different colors, and the memory stores L of the K types (where L< The representative energizing time data for the ink paper of the color (K is an integer) is stored, and the actual energization time data for the ink paper other than the L color ink paper is stored. A thermal transfer recording device characterized in that the calculation is made from the representative energization data for a given period of time.