JPH04201268A - Heat-sensitive recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal recording device that prints an image f# having gradations, and particularly to a thermal recording device that prints an image f# having gradations, and in particular, The present invention relates to a thermal recording device suitable for obtaining prints with a constant halftone expression.

[Conventional technology]

In thermal recording devices, the relationship between the energization time to the heating element and the color density is generally not linear, and the amount of energization time increase required to obtain a constant increase in a degree is moderate in the low and high density areas. The concentration area is relatively large. Therefore, when trying to faithfully reproduce an image signal with gradation,
It is necessary to change the energization time depending on the gradation.

As described in Japanese Patent Application Laid-Open No. 57-48868, in the conventional device, a non-linear relationship between gradation and energization time is written in advance in a read-only memory (hereinafter abbreviated as ROM). During recording, the gradation is "1" during the power supply time.
, and others output "o" in parallel, and a grayscale image can be recorded according to the set contents of the ROM.

[Problem to be solved by the invention]

By the way, in a thermal recording device, it is known that heat is accumulated around the heating element of the thermal heater (1) along with the printing, and the color density for the same energization time increases. It is known that when three types of recording media are used, yellow as the first color, magenta as the second color, and cyan as the third color, and when printing is carried out three times, the characteristics of current application time and color density differ depending on the recording medium.

Furthermore, when printing color images, even if they are of the same color, if a medium with a different coloring material and composition is used for printing, the image will be recorded at a density different from the original design, making it impossible to maintain a normal recording density. Therefore, significant restrictions are placed on the recording medium.

In addition, the amount of heat stored in the thermal head varies depending on the repetition cycle when printing one pixel, so even if the same recording medium is used, if the repetition cycle is short, that is, the printing speed is fast, the recording density will be higher, and if the repetition If the cycle is long, that is, if the printing speed is slow, the recording density becomes thinner and normal recording density cannot be maintained.

However, the above-mentioned conventional technology does not take into consideration the change in recording density during print recording, and the ROM that was originally designed
However, there is a problem in that recording density changes due to changes in temperature and printing speed.

Further, when performing color printing, data for each recording medium for three or four colors is required for each gradation. Furthermore, if you want to be able to use multiple recording media with different color materials, you will need data for the number of color materials used, and if you make the printing speed variable, you will need data for the number of print speeds that are variable. data is required, which increases the required ROM capacity. This problem becomes particularly noticeable when recording multiple gradations such as 64 gradations, 128 gradations, or more.

The purpose of the present invention is to solve the above-mentioned problems of the prior art,
It is an object of the present invention to provide a thermal recording device capable of reducing the amount of data required while enabling stable gradation expression in response to multicolor, temperature fluctuation, and variable speed recording.

[Failure to solve the problem]

In order to achieve the above object, a thermal recording apparatus according to the present invention is a thermal recording apparatus that performs multi-gradation recording by controlling the energization time to the heating element of a thermal head.
storage means for storing data regarding the energization time of the heating element for a plurality of temperatures in accordance with one printing speed and each gradation; a temperature detection means for detecting the temperature of the thermal head; printing speed detection means for detecting the printing speed; storage means for storing data for correcting the energization time corresponding to the printing speed; reading both sets of data for the second temperature from the storage means, interpolating the read data for both sets, and reading correction data corresponding to the printing speed from the storage means to correspond to the corresponding temperature and speed. and a control means for controlling the energization time of the heating element for each gradation based on the calculation result of the calculation means. is.

Another thermal recording device according to the present invention is a thermal recording device that performs multi-gradation recording by controlling the energization time to the heating element of the thermal head. a storage means for storing data regarding the energization time of the heating element for a plurality of temperatures; a temperature detection means for detecting the temperature of the thermal head; a printing speed detection means for detecting the printing speed; In accordance with the detected temperature, both sets of first and second temperature data including the temperature are read out from the storage means, the read data sets are interpolated, and the printing speed is set as a reference. Let the current printing speed ratio be the correction data,
energization time data calculation means for calculating a new set of data regarding energization time corresponding to the relevant temperature and the relevant speed; and control for controlling the energization time of the heating element for each gradation based on the calculation result of the calculation means. We have prepared the means.

Another heat-sensitive recording device according to the present invention is a heat-sensitive recording device that performs multi-gradation recording by controlling the energization time to a heating element of 2-4-4-3. a storage means for storing data regarding the energization time of the heating element corresponding to a plurality of temperatures; a temperature detection means for detecting the temperature of the thermal head; and a printing speed control means for arbitrarily varying the printing speed; In accordance with the temperature detected by the temperature detection means, reading both sets of first and second temperature data including the temperature from the storage means, interpolating the read data sets of both sets,
There is also an energizing time data calculating means for obtaining correction data from a reference printing speed and an arbitrarily varied printing speed, and calculating a new set of data regarding the energizing time corresponding to the relevant temperature and the relevant speed, and the calculating means. and control means for controlling the energization time of the heating element for each gradation based on the calculation result.

Preferably, the plurality of sets of data are assembled in correspondence with different printing ink color materials (by a d2 calculation means,
Data corresponding to the ink coloring material to be used is selected and the energization time for each of the above gradations is calculated.

The selection of data corresponding to the ink color material by the calculation means is performed in response to an instruction from a detection means for detecting type information of the ink color material or a designation means for specifying type information. , is suitable for a thermal transfer type recording device, but can also be applied to one in which the recording paper itself develops heat-sensitive color.

[Function] According to the present invention, a plurality of sets of data regarding the energization time of the heating element of the thermal head are stored for a plurality of temperatures, and when printing, data corresponding to the temperature is stored in the memory according to the temperature of the thermal head. The data is interpolated and calculated, and the energization data is corrected based on the printing speed, and the thermal head is energized based on this data. As mentioned above, data is interpolated in the temperature direction and speed direction, so the data stored in the storage means such as RO\1 is based on the printing density characteristics of the ink color material, which continuously changes depending on the temperature of the thermal head. It is sufficient to hold corresponding data only for a plurality of representative temperatures at one printing speed. Therefore, printing results with constant gradation density characteristics that are unaffected by changes in temperature and printing speed can be obtained while reducing the capacity of the data to be stored in the storage means. Further, it is possible to store data of other ink color materials having different print density characteristics by the reduced data capacity.

In this case, the data calculation means reads data suitable for the coloring material of the ink paper used from the storage means, and if the correction data in the speed direction differs depending on the ink coloring material, it also reads that data from the storage means, and reads out the data for each gradation. Calculate the energization time data for each gradation. Therefore, printing results with constant gradation density characteristics can be obtained even when ink color materials are different.

〔Example〕

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

FIG. 1 shows a schematic configuration of a thermal transfer recording apparatus as a first embodiment of the present invention.

This thermal transfer recording device uses a thermal head 6 that prints an image on a recording paper 11 wound around a tram 10 via an ink paper 9, and a heating element 8 of the thermal head 6 to be energized by adjusting the printing time from an image signal source. A halftone control means 2 for controlling according to the image signal to be output, a temperature sensor 7 for detecting the temperature of the thermal head 6, and a printing speed detection means 5 for detecting the speed at the time of printing. A gradation ROM 4 that stores energization time difference data between gradations, and a temperature sensor 7
The energization data calculation means 3 reads the contents of the corresponding ROM 4 according to the detected temperature and calculates energization time data for controlling the energization time of the halftone control means 2. The energization data calculation means 3 includes a calculation section 3a and a lookup table (LUT) 3b.

Specifically, the energization data calculation means 3 calculates the temperature sensor 7 attached to the thermal head 6 by the time the recording paper 11 or the ink paper 9 is conveyed to a predetermined recording position or before recording is started. Receives temperature data from
Based on the temperature data, necessary data, which will be described later, is read from the gradation ROM 4, and energization time data is calculated. During recording, an image signal having gradation information in the gradation direction for each gradation of the image is input from the symbol source 1 to the halftone control means 2. The halftone control means 2 receives data on the energization time of the thermal head 6 corresponding to the gradation number output from the energization data calculation means 3, and outputs a strophe signal to the thermal head 6 in accordance with this energization time. do.

The thermal head 6 causes current to flow through the heating element 8 for the duration of the supplied strobe signal. The heating element 8 generates heat accordingly. ) - Recording paper 11 is wound around the circumference of ram 7, and ink paper 9 is stacked on top of it and pressed against it by thermal head 6. The amount of heat generated by the heating element 80 changes according to the energization time specified by the halftone control means 2, and ink corresponding to the amount of heat is transferred from the ink paper 9 to the recording paper 11.
Controlled halftone recording is performed by transferring the image to the image plane.

FIG. 2 shows an example of a data structure of typical energization time differences between adjacent gradations of the first color ink recorded in the gradation ROM in FIG. 1.

In FIG. 2, ■9■, . . . , ■, ■ are data reference numbers specifying different energization time differences; TI, T2. T3
．． T4. T5 is a typical temperature example (e.g. 5
℃, 20°C, 935°C, 950°C, 65°C). In this embodiment, the data DT for each temperature row is the typical difference in energization time between adjacent gradations (incremental value of energization time per gradation), in other words, the gradation-density curve of the ink paper 9. It consists of eight pieces of data selected as representative slopes (for example, eight types for 64 gradations). Note that each typical temperature series has a range of several degrees Celsius (for example, the reference temperature ±2 degrees Celsius).
). Further, each temperature series is selected in advance to have the same gradation-density characteristics.

Next, an example of a flowchart for interpolating and calculating energization time data for all gradations from the data configurations shown in FIGS. 3 and 2 will be shown.

First, in process (a), the temperature of the thermal head 6 is detected by the temperature sensor 7 according to a printing command, and the detected temperature TI
Temperature data representing the temperature is input to the energization data calculation means 3 in FIG.

In process (b), the printing speed detection means 5 detects the printing speed, and the detected speed Si is calculated by the energization data calculation means 3. Both of us are strong.

In process (c), representative temperature sequences Tm, Tn (
Identify and read Tm<Ti<Tn). Here, the representative temperature series is divided into four stages from Tm to Tn in the temperature direction, that is, Tm, Ta.

A case will be explained in which the data is divided into Tb, Tc, and Tn, and Ta, Tb, and Tc are calculated by interpolation.

In process (d), data D in the representative temperature series Tm and Tn
The difference ΔDTmn between Tm and DTn is determined, and this difference ΔDT is divided by 4 to determine the increment ΔDT for each temperature series. Depending on whether the detected temperature T1 belongs to the temperature series, ΔDTXI if it belongs to Ta, and ΔDT if it belongs to Tb.
X2. If it belongs to Tc, ΔDTX3 is performed, and data DTi in the temperature sequence Ti is obtained by adding it to DTm.

In process (e), the energization time calculation means 3 calculates the detected speed S.
The correction coefficient ks is calculated by dividing by the speed Sm based on 1.

In process (f), energization time data D is generated for each representative gradation number.
Ti is multiplied by ks to calculate energization time data DSi.

By repeating the processes (c) to (f) above for all data reference numbers, it is possible to calculate the data of the temperature sequence to which Ti belongs.

Next, in process (g), the energization data calculation means 3 allocates the data of the temperature column to which the detected temperature Ti belongs to each gradation via the reference number by the method described later.

In process (h), total energization time data for each gradation is calculated based on data representing the energization time difference assigned to each gradation.

As mentioned above, the thermal navel) can be reached by simple calculation process 6
Optimal data is calculated for the detected temperature T1 at , and gradation-current application time data is determined.

An example of data interpolation in which data is interpolated in the temperature direction will be described based on the data structure shown in FIG.

Here, the temperature T1 of the thermal head 6 detected by the temperature sensor 7 is Ta, Tb, T in the range from T2 to Ta.
A case that belongs to either of c will be explained. In addition,
T2. Ta as well as Ta.

Tb and Tc are each within a range of several degrees Celsius (for example, the reference temperature ±
2°C).

First, if Ti belongs to Ta, ΔDTXI.

If it belongs to Tb, ΔDTX2. If it belongs to Tc, ΔDTX3 is performed and the result is added to data DTm in temperature sequence Tm. That is, DTi is DT i =DTm+((DTn-DTm)XN)-4
[N is an integer from 0 to 3] It is determined as follows.

As described above, data of the temperature sequence to which Ti belongs is calculated according to the detected temperature Ti.

Next, calculation of energization time with respect to speed will be explained.

FIG. 4 is an explanatory diagram of calculation of energization time data with respect to printing speed. The operation of calculating the energization time data will be described below.

In FIG. 4, the printing speed is explained as three types, Sl, Sm, and S2, but the printing speed may be any number of two or more types.

The printing speed detection means 5 detects the current printing speed Si. The data stored in the gradation ROM 4 is energization time data at a reference speed Sm, and the energization time calculation means 3 calculates a correction coefficient ks by dividing the detected speed Si by the reference speed Sm.

In this example, when Si is Sl, k s = S 1/Sm,
When Si is Sm, ks=Sm/Sm=1, Si is 82
When ks=52/Sm.

The energization time calculation means 3 calculates energization time data DSi by multiplying the energization time data DTi by ks for each representative gradation number.

For example, when the printing speed is 5i-5l, the correction coefficient ks=S 1
When /Sm=ks 1, in the case of data reference number ■, the energization time data becomes DTIXksl. Hereinafter, the data reference number ■ will be DT2Xksl, and the data reference number ■ will be DT3Xksl, and by repeating this for all data reference numbers, the energization time data at the speed Si can be calculated.

Next, calculation of the energization time for each gradation will be explained.

FIG. 5 explains the operation of calculating the energization time data for each gradation of the image signal. The operation of calculating the energization time data will be described below.

The energization data calculation means 3 reads the necessary temperature sequence from the gradation ROM 4 according to the temperature Ti detected by the thermal head 6, calculates the data of the temperature sequence to which Ti belongs, and then calculates the data as explained in Fig. Then, correction coefficient data based on the speed to which Sl belongs is calculated. Here, the data at each reference number is indicated by an increment value per gradation as described above.

Next, the LUT in the energization data calculation means 3 is as shown in FIG.
As shown in a), there is a data reference number assigned to each gradation, and through this data reference number, the information in FIG.
) is assigned to each gradation. This LO
There are various possible methods for selecting the allocation contents by T, but 1.
As an example, in the energization time-density curve as shown in Fig. 21, when the density is divided into a fixed amount ΔF for each gradation, the corresponding energization time difference ΔT is taken as the energization time difference of the relevant gradation, and the corresponding energization time difference ΔT corresponds to this time difference. It is sufficient to select data, select the data reference number corresponding to the LUT, and associate the data reference number with the corresponding gradation number of the LUT. The energization data calculation means 3 further calculates initial gradation-energization time data based on the data assigned to each gradation by the LUT.

The energization data calculating means 3 detects the temperature of the thermal head 6 at that time before starting recording, calculates gradation-energization time data in real time according to the detected temperature, and outputs it to the halftone control means 2. do.

FIG. 6 shows another example of a flowchart for interpolating data in the temperature direction and velocity direction from the data structure shown in FIG. 2 to calculate energization time data for all gradations.

Processing from (a) to (d) and from (g) to (h) is performed in the same manner as in FIG.

Calculation of energization time with respect to speed in (e) and (f) will be explained.

FIG. 7 shows correction data stored in the gradation ROM 4 together with the energization time data. The operation of calculating the energization time data will be described below.

The printing speed detection means 5 detects the current printing speed Si. As shown in FIG. 7, the gradation ROM 4 stores correction coefficients ks corresponding to each of the printing speeds S1 along with current application time data at representative speeds. The energization time calculation means 3 reads out a correction coefficient ks corresponding to the printing speed S1 detected by the printing speed detection means 5. The energization time calculation means 3 is
The energizing time data DSi is calculated by multiplying the energizing time data DTi by ks for each representative gradation number.

By repeating the above process for all data reference numbers, the energization time data at the speed Sj can be calculated. In this example, this is effective when the gradation-current application time curve is not linear with respect to the printing speed.

FIG. 8 shows another example of a flowchart for interpolating data in the temperature direction and speed direction from the data structure shown in FIG. 2 to calculate energization time data for all gradations.

From (a) to (d) and from (g) to (h), the same processing as in FIG. 3 is performed.

Calculation of energization time with respect to speed in (e) and (f) will be explained.

FIG. 9 shows another example of correction data stored in the gradation ROM 4 together with the energization time data.

The operation of calculating the energization time data will be described below.

The printing speed detecting means 5 detects the current printing speed Si, and the six-gradation ROM 4 stores correction coefficients ks corresponding to the printing speed S1 and the data reference numbers, as well as energization time data at the representative speed. The energization time calculation means 3 reads out the printing speed S detected by the printing speed detection means 5 and the correction coefficient ks corresponding to the data reference number for calculation.

The energization time calculation means 3 calculates energization time data DSi by multiplying the energization time data DTi by ks for each representative gradation number.

By repeating the above process for all data reference numbers, the energization time data at the speed S1 can be calculated.

FIG. 10 is a diagram showing gradation-energization time data, which is an example of the energization time data calculated in FIG. 4. 1st
In Figure 0, the vertical axis represents cumulative energization time data, and the horizontal axis represents gradation.

As shown in FIG. 10, the graph of gradation-current application time data is a line graph for each gradation.

Since the data is composed of the typical slope of the tone-density curve of the ink paper 9, that is, the increment value per tone, the optimum energization time data is assigned to each tone. Furthermore, depending on the printing speed, it is possible to create three sets of gradation/current application time data.

With the simple data structure shown in Figure 2 and the calculation/processing shown in Figure 3, it is possible to calculate the gradation-density curve with good reproducibility. A gradation-dark I curve can be calculated.

In the case of color printing, similar data as shown in FIG. 2 is stored in the gradation ROMJ for the second and third colors, etc., and the energization time data is stored in accordance with the temperature data detected by the thermal head 6. calculate.

As described above, the optimum actual energization time data is obtained according to the temperature of the thermal head 6, so that printing with constant gradation to density characteristics is performed regardless of the environmental temperature and the number of continuous prints. In addition, since the representative energizing time data in the gradation ROM 4 is composed of representative values for each temperature gradation,
The capacity of the gradation ROM 4 can be reduced.

In addition, since the gradation ROM contains current application time data corresponding to one representative printing speed, it can correspond to a plurality of printing speeds, which further reduces the amount of data stored in the gradation ROM 4. (The amount of data can be reduced to 1/10 in the case of this embodiment C) FIG. By counting , a strophe signal is outputted to the terminal 6. For this reason, all of the energization time data output from the energization time calculation means 3 to the halftone control means 2 is the number of clocks. Here, since the number of clocks is an integer, the data outputted by the energization time calculation means 3 to the halftone control means 2 is also an integer. Therefore, when calculating the energization time data by interpolation from the two representative temperature sequences, the rounding error when converted into an integer becomes a non-negligible amount. In order to reduce rounding errors, it is possible to increase the frequency of the clock and increase the number of pixels of the corresponding data, but it is possible to
The amount of data stored in M4 increases.

FIG. 13 shows an example of a data structure of typical energization time differences between adjacent gradations of the first color ink recorded in the gradation ROM 4 in FIG. 11. The energization time data stored here is all integer data because it is used by the halftone control means 2.

FIG. 12 shows an example of a flowchart for interpolating the energization time data from the data structure shown in FIG. 13 and calculating the energization time data for all gradations.

First, in process (a), the temperature sensor 7 detects the temperature of the thermal head 6 according to a printing command, and the detected temperature T1
Temperature data representing the temperature is input to the energization data calculation means 3 in FIG.

In process (b), the printing speed detection means 5 detects the printing speed, and the detected speed S1 is input to the energization data calculation means 3.

In the process (c), representative temperature strings Tm, Tn, which sandwich the detected temperature TI from among the representative temperature strings stored in the gradation ROM 4 are created.
(Tm<T i <Tn) and award it. Here, the representative temperature sequence Tm to Tn is divided into four stages in the temperature direction, that is, Tm, Ta.

A case will be described in which the image is divided into Tb, Tc, and Tn, and Ta, Tb, and Tc are calculated by interpolation.

First, calculation is performed using the data corresponding to the first data reference number.

In process (ci), the difference ΔD T m n between the data DTm and DTn in the representative temperature series Tm and Tn is obtained, and this difference ΔDT is divided by 4 to obtain the increment ΔDT for each temperature series. Depending on whether the detected temperature Ti belongs to the temperature series,
If it belongs to Ta, ΔDTX1. If it belongs to Tb, ΔDTX2. If it belongs to Tc, ΔDTX3 is performed and further added to DTm to obtain data DTi in temperature sequence T1.

In process (e), the energization time calculation means 3 calculates the detected speed S.
The correction coefficient ks is calculated by dividing i by the speed Sm based on the reference, and the energization time data DTi is multiplied by ks to calculate the energization time data DSi.

In process (f), the decimal part d of the previously calculated energization time data
A process of adding ni is performed, but in the case of the first data calculation, the previous data is O, and the energization time data does not change.

In process (g), the calculated data is divided into an integer part DNi and a decimal part dni. The integer part DNi becomes data sent to the halftone control means 2 at the time of printing as current application time data. Further, the decimal part dni is stored inside the energization data calculation means 3.

Next, the process (d) of calculating the data corresponding to the second and subsequent data reference numbers is performed to calculate the data D in the representative temperature series Tm and Tn.
Find the difference ΔD T m n between Tm and DTn, and calculate this difference ΔD
Divide DT by 4 to find the increment ΔDT for each temperature series. Depending on which temperature series the detected temperature T1 belongs to, T
a, then ΔDTX2. If it belongs to Tc, ΔDTX3 is performed, and data DTj in the temperature sequence DTi is obtained by adding it to D T m.

In process (e), the energization time calculation means 3 calculates the detected speed S.
Calculate the correction coefficient ks by dividing by the speed Sm that is used as the i standard,
The energization time data DTi is multiplied by ks to obtain the energization time data D.
Calculate Si.

In process (f), the decimal part d of the previously calculated energization time data
In the case of the second data calculation in which the process of adding ni is performed, the decimal part dni of the first calculated data is added.

Through this process, the data that was previously rounded down to a decimal part is used to calculate the current energization time.

In process (g), the calculated data is divided into an integer part DNi and a decimal part dni. The integer part DNi becomes data sent to the halftone control means 2 at the time of printing as current application time data. Further, the decimal part dni is stored inside the energization data calculation means 3 and used for calculating the next energization time data.

By repeating the processes (d) to (g) above for all data reference numbers, the data of the temperature sequence to which T1 belongs can be calculated.

Next, in process (h), the energization data calculation means 3 allocates the data of the temperature column to which the detected temperature Ti belongs to each gradation via the data reference number by the method described later.

In process (i), total energization time data for each gradation is calculated based on data representing the energization time difference assigned to each gradation.

As described above, the optimum data is calculated for the detected temperature Ti in the thermal head 6 through a simple calculation process,
Gradation-current application time data is obtained.

FIG. 14 shows an example of data interpolation in which data is interpolated based on the data structure shown in FIG. 13.

Here, the temperature Ti of the thermal head 6 detected by the temperature sensor 7 is T2 to T3.
In the case where the printing speed belongs to either Tc, the case where the printing speed is standard Sm will be explained.

In addition, T2. Similar to T3, Ta, Tb, and Tc are each associated with a range of several degrees Celsius (for example, reference temperature ±2 degrees Celsius).

For example, when Ti belongs to the temperature range of Ta, the difference between the data DPI2°DPI3 in the representative temperature series T2 and T3 is found, and this difference is divided by 4 to find the increment for each temperature series. The integer part of this increment multiplied by 1 and added to DPI2 is set as data in Ta. That is, D
AI is DA1=DP12+((DPI 3-DPI
This is the integer part of the value obtained by 2)/4)×1. Next, DA2 is calculated by setting the decimal part of the value obtained above to dal. Data DP22. Find the difference in DP23,
Divide this difference by 4 to find the increment for each temperature series.

This increment multiplied by 1 is added to DP22, and dal is further added, and the integer part is set as data at Ta. That is, DA2 is DA2=DP22+((DP2
3-DP22)/4)X1+dal This is the integer part of the value obtained. Next, DA3 is calculated by setting the decimal part of the value obtained above to da2. Similarly, DA3. -DA8 is calculated.

For example, if T] belongs to the temperature range Tb, the difference between the data DPI2°DPI3 in the representative temperature rows T2 and T3 is determined, and this difference is divided by 4 to determine the increment for each temperature row. The integer part of this increment multiplied by 2 and added to DPI2 is the data at Tb. That is,
DBI is DB1=DPI 2+((DPI 3-DP
This is the integer part of the value obtained by I 2)/4)×2. Next, DB2 is calculated using the decimal part of the value obtained above as dbl. Data DP22. Find the difference in DP23 and divide this difference by 4 to find the increment for each temperature series. This increment multiplied by 1 is added to DP22, and dbl is further added, and the integer part is set as data at Tb. That is, D.B.
2 is DB2=DP22+((DP23-DP22)/
4) This is the integer part of the value obtained by x2+dbl. Next, DB3 is calculated by setting the decimal part of the value obtained above to db2. Similarly, DB3. - DBS is calculated.

For example, when T1 belongs to the temperature range of Tc, the difference between the data DP12°DPI3 in the representative temperature series T2 and T3 is found, and this difference is divided by 4 to find the increment for each temperature series. The integer part of this increment multiplied by 3 and added to DPI2 is the data at Tc. That is,
DCI is DC1=DPI 2+((DPI 3-DP
This is the integer part of the value obtained by I 2)/4)×3. Next, DC2 is calculated using the decimal part del of the value obtained above. Data DP22. Find the difference in DP23 and divide this difference by 4 to find the increment for each temperature series. This increment multiplied by 1 is added to DP22, and del is further added, and the integer part is set as data at Tc. That is, DC2
is DC2=DP22+((DP23-DP22)/4
)X3+del is the integer part of the value obtained. Next, DC3 is calculated by setting the decimal part of the value obtained above to dc2. Thereafter, DC3 and DC8 are calculated in the same manner.

As described above, interpolation calculation of data is performed and energization time data is calculated. Using this data calculation method, the gradation R
The data held in OM4 is often integer numbers, which can reduce the amount of data. In addition, since the gradation-current application time curve of the temperature series between the representative temperature series can be reproduced with good accuracy using accurate values, printing with constant gradation-to-density characteristics can be performed.

Also, such interpolation processing is applied to printing speed.

It is also possible to apply the present invention to calculation processing that includes division calculations, such as calculation of energization time.

〔Effect of the invention〕

11 that corresponds to the printing density characteristics of the ink color material that continuously changes depending on the temperature of the thermal head! ! By retaining data regarding power hours only for representative temperatures and using interpolated data for temperatures that do not apply, it is possible to reduce the amount of data to be stored in a data storage storage means such as a ROM, and This results in halftone expression with constant tone density characteristics regardless of temperature changes.

In addition, data related to the energization time according to the printing density characteristics of the ink color material that changes depending on the printing speed is stored only for typical speeds, and for speeds that do not correspond, data is stored in ROM etc. by correcting it using a correction coefficient. The amount of data to be stored in the storage means can be reduced, and halftone expression with constant tone density characteristics can be achieved regardless of the printing speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a thermal recording apparatus according to a first embodiment of the present invention, FIG. 2 is a configuration diagram of data stored in a gradation ROM, and FIG. 3 is an operation of the embodiment of FIG. 1. FIG. 4 is an explanatory diagram showing the speed correction in the embodiment of FIG. 1, and FIG. 5 is a flowchart showing the LO in the embodiment of FIG. 1.
8 is a flowchart showing the operation of the third embodiment, FIG. 9 is an explanatory diagram showing speed correction in the embodiment of FIG. 8, and FIG. 10 is a flowchart showing the operation of the third embodiment. FIG. 11 is a block diagram showing the configuration of a thermal recording apparatus according to the fourth embodiment of the present invention, and FIG. 12 shows the operation of the embodiment of FIG. 11. FIG. 13 is a configuration diagram of data stored in the gradation ROM, and FIG. 14 is an explanation of data interpolation in the embodiment of FIG. 11. 1. Image signal source, 2. Halftone control means, 3. Energization data calculation means, 4. Gradation ROM, 5. Printing speed detection means, 6.. Thermal head, 7. Temperature sensor, 8.. Heating resistor, 9. Ink paper, 10-1 to racket, 11. Recording paper, 12. Clock pulse generating means. Figure 1 Figure 2 Mouth 30th 40th 5th step (α) Strategy 60 Suji q Shoko 8 Maro strategy 9 Team strategy / θ evil Yang Choku 11 Ward■ Figure 72

Claims (1)

[Claims] 1. In a thermal recording device that performs multi-gradation recording by controlling the energization time to the heating element of the thermal head, a plurality of specific gradations are recorded at one or more preset specific temperatures. storage means for storing a plurality of representative energization time data representing the energization time for each tone; temperature detection means for detecting the temperature of the thermal head; detection means for detecting a printing speed during recording; and the temperature detection means. According to the detected temperature, both sets of data of the first and second temperatures including the temperature are read from the storage means, and the read data of both sets are interpolated and detected by the speed detection means. energization time calculation means for calculating correction data according to the calculated speed, correcting the interpolated data with the calculated data, and calculating a new set of data regarding the energization time corresponding to the temperature and speed. A thermal recording device characterized by: 2. The thermal recording apparatus according to claim 1, wherein a plurality of sets of current application time correction data corresponding to speeds are stored in a ROM in advance. 3. The thermal recording apparatus according to claim 1, wherein a plurality of sets of current application time correction data corresponding to the speed are stored in advance in the ROM for each corresponding gradation. 4. The thermal recording apparatus according to claim 1, wherein a microprocessor is used as the energization time calculation means. 5. The thermal storage device according to claim 1 or 4, wherein the energization time data is an integer. 6. Read both sets of data of the first and second temperatures including the temperature from the storage means, interpolate the read data of both sets, and create a new set of energization corresponding to the temperature. When calculating time data, an energizing time calculation means calculates a new set of data regarding energizing time by adding the decimal part of the energizing time data of the previous gradation to the energizing time data of the current gradation. 6. The heat-sensitive recording device according to claim 5, further comprising: a heat-sensitive recording device.