JPH0639440U - Thermal printer equipped with resistance correction function for thermal head heating element - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a thermal printer capable of continuous tone reproduction in a sublimation thermal printer. [Structure] A memory 8 for previously recording resistance value data relating to the resistance value of each unit heating element of a thermal head, and a correction data table for retrieving correction data from this resistance value data and density gradation data of input print data are provided. A correction data table memory 9 for recording is provided, and the amount of electricity to be applied to the heating element is corrected by the correction data retrieved from the base correction data table corresponding to the density gradation data of the input print data. In this case, it is desirable that the amount of electricity is adjusted by the total energization time of voltage or current of a predetermined value corresponding to the resistance value of the heating element.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal printer for printing predetermined image information and the like, and in particular, it is suitable for a sublimation type thermal printer which is a printing means suitable for continuous tone reproduction of print density, and is suitable for resistance value correction of a thermal head heating element. Regarding a thermal printer with functions.

[0002]

[Prior art]

 A conventional thermal printer is equipped with a thermal head in which unit heating elements are arranged in a predetermined shape, and each unit heating element is changed in accordance with the print density gradation according to the print data input. Each quantity of electricity is applied and energized. Generally, in a sublimation thermal printer, each pixel that constitutes the image information to be printed is composed of multiple dots so that the original image can be represented with the required accuracy, and each unit heating element in the thermal head is located in each dot. It corresponds.

The heating element of the thermal head is constructed, for example, as shown in FIG. Fig. 2 is a diagram showing the symbolic concept of the heating element H provided in the thermal head of a line printer in which dots to be printed are arranged in one horizontal row. The heating element H is designed in the thermal head. The number of printed dots n is divided by the dot arrangement pitch, and terminals P ₁ , P ₂ ··· P _i , P _{i +} are respectively provided at both ends of each divided unit H ₁ , ···, H _i , ···, H _{n. 1,} is connected _{··, P n, P n +} 1, a. To perform printing by the thermal head having the heating element having the above-described configuration, for example, a voltage of a predetermined value is applied between the terminals P ₁ and P _2, and the unit heating element H ₁ is connected to the unit heating element. A current corresponding to the print density of the dots corresponding to H ₁ is passed to generate heat. Similarly, a current of a predetermined value is applied to each of the unit heating elements H ₂ , ..., H _i , ..., H _n according to the print data to complete printing for one line, and the same operation is repeated thereafter. To energize the thermal head shown in FIG. 2 according to the input print data indicating the image information to be printed, that is, to apply a predetermined amount of electricity to each unit heating element, for example, the configuration shown in FIG. It is used.

In FIG. 4, print data I including digital data indicating a gradation of print density corresponding to each dot of an image created or processed in a higher-level information processing apparatus of this thermal printer (not shown) is input interface. Enter 41. The memory 42 in which the data conversion table is recorded is searched according to the data indicating the gradation of the print density for each dot to be printed, which is set in the print data input to the input interface 41, and corresponds to the characteristics of each thermal head. Then, the data value indicating the gradient of the print density is converted into an electric quantity signal to be applied to each unit heating element forming each thermal head. The converted electric quantity signal to be applied to each unit heating element is temporarily recorded in the strobe data recording memory 44 for each heating element via the gate 43. The data temporarily recorded in the strobe data recording memory 44 inputs a heating element number signal designating each corresponding unit heating element of the thermal head and an electric quantity signal to be applied to this unit heating element to the thermal head driver 46. The thermal head driver 46 applies a current according to the electric quantity signal to the target heating element of the thermal head to generate heat. In a sublimation thermal printer, when each unit heating element generates heat, the dye molecules contained in the binder resin (not shown) that adheres to the thermal head diffuses to the receiving paper, and the dot area corresponding to this unit heating element is printed. Is executed.

[0005]

[Problems to be solved by the device]

 By the way, the print density in the sublimation type thermal printer can reproduce 256 levels of continuous gradation. However, according to the printing means as described above, in reality, each unit heating element of the thermal head has a deviation in resistance value. Therefore, it is difficult to express uniform gradation. That is, the resistance deviation characteristic of the thermal head has such a characteristic as shown in FIG. In FIG. 3, the horizontal axis shows the heating element numbers from 1 to 2600, and the vertical axis shows the resistance value corresponding to each heating element number. Since the heating element has the resistance deviation characteristic as shown in FIG. 3, even if the resolution of the input print data is increased in order to execute the gradation reproduction of 256 levels, for example, each unit heat generation is caused by the resistance deviation. There is a risk that the heat generation characteristics of the body will be different and the print density will be reversed, so there is no point in increasing the resolution of print data. The present invention eliminates the above-mentioned conventional problems, and is a thermal head having a resistance correction function of a thermal head heating element capable of realizing 256 levels of gradation in order to enable continuous gradation reproduction by a sublimation type thermal printer. The purpose (problem) is to provide a printer.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, in a thermal printer having a resistance correction function for a thermal head heating element based on the present invention, a memory for recording resistance value data relating to the resistance value of each unit heating element in advance, It is equipped with a correction data table memory that records a correction data table that searches for correction data from resistance value data and print density gradation data written in the print data, and that corresponds to the print density gradation written in the print data. The amount of electricity to be applied to each unit heating element is corrected by the correction data retrieved from the correction data table. It is effective to adjust the amount of electricity according to the total energization time of voltage or current of a predetermined value corresponding to the resistance value of each unit heating element.

[0007]

[Action]

 In the present invention, as described above, the correction data is created from the resistance value data relating to the resistance value of each unit heating element and the print density gradation data described in the print data and applied to each unit heating element. Since the amount of electricity to be used is corrected, an appropriate amount of heat generation can be obtained from each unit heating element without being affected by the resistance value. Therefore, even if each unit heating element has a resistance deviation, the print density is not reversed. The above object can be easily achieved by adjusting the amount of electricity to be applied according to the total time for which a predetermined voltage or current is applied.

[0008]

【Example】

An embodiment in which a thermal printer having a resistance correction function for a thermal head heating element based on the present invention is applied to a sublimation type thermal printer will be described in detail with reference to FIG. In the sublimation thermal printer according to this embodiment, as described in the prior art, each pixel forming the image information to be printed is composed of a plurality of dots corresponding to the necessary resolution for image reproduction, and The dots correspond to each unit heating element. The structure of the heating element in the thermal head shown in this embodiment is the same as that of the thermal head described in FIG. Therefore, the gradation data of the print density included in the print data input to this thermal printer is a print for designating the heating element corresponding to one line of the thermal head as a unit heating element obtained by dividing the heating element corresponding to one line at a predetermined pitch. It is assumed that the data indicating the gradation of density is sequentially formed from the data for the _first unit heating element H ₁ to the data for the nth unit heating element H _n .

FIG. 1 is a schematic block diagram mainly illustrating an energization function for a thermal head, which illustrates a thermal printer having a resistance correction function for a thermal head heating element according to the present invention. In FIG. 1, input print data I having print information to be input to this thermal printer is input to an input interface 1, the input interface 1 is connected to a data conversion table memory 2, and the data conversion table memory 2 is connected to a gate 3. It is connected to the strobe data memory data section 4a of the strobe data memory 4 via the. The strobe data memory data section 4a is connected to the gradation counter 5 and the thermal head driver 6, and the gradation counter is also connected to the thermal head driver 6. The thermal head driver 6 is connected to the heating element H of the thermal head.

The above-mentioned input interface 1 is also connected to the thermal head dot position counter 7, and the thermal head dot position counter 7 is connected to the heating element resistance value data memory 8. The heating element resistance value data memory 8 is connected to the correction data table memory 9, and the correction data table memory 9 is connected to the strobe data memory correction data portion 4b of the strobe data memory 4 through the gate 3. The strobe data memory correction data unit 4b is connected to the gradation counter 5 and the thermal head driver 6. The constituent circuits described above are controlled and managed by a host information processing apparatus (not shown). In FIG. 1, illustration of control signal lines, power supply lines, etc. input from the higher-level control function of this thermal printer is omitted. Further, the connection of each memory described above is shown as being connected between the functional circuits of the front stage and the rear stage for convenience of explanation of the operation of the thermal printer described later, but the signal line is connected by a control signal (not shown). It is controlled so that the recorded data in the memory is read to the circuit in the subsequent stage by the signal from the previous stage, and the signal from the previous stage is recorded.

In advance, each resistance value of each unit heating element H ₁ , ..., H _i , ..., H _n of the heating element H constituting this thermal head is measured, and this thermal printer corresponding to this resistance value is measured. Are converted into numerical values suitable for data processing to be described later, or resistance values are expressed in predetermined units, and named in correspondence with each unit heating element H ₁ , ..., H _i , ..., H _n . The heating element resistance value data memory 8 shown in FIG. 1 is recorded corresponding to the resistance value numbers. In the data conversion table memory 2, all data levels corresponding to the characteristics of the heating element H forming the thermal head and showing the gradation of the print density in each dot included in the input print data, for example, 256. Create data for setting the amount of electricity to be supplied to each unit heating element according to the level and record it as a data conversion table. In the present embodiment, as the electric quantity, a unit current pulse (a pulse in which a current value to be energized and a pulse time width is set) is applied to each unit heating element in a number corresponding to the gradation indicating the print density. , The gradation data indicating the number of times of application is recorded as a data conversion table. Further, the correction data table memory 9 corresponds to the characteristics of the heating element H which constitutes the thermal head, and the unit heating elements H ₁ , ..., H _i ,. As the base pulse of the applied pulse based on the gradation data retrieved from the data conversion table described above, corresponding to each resistance value in _n and the data indicating the gradation of the print density in each dot included in the input print data. , Record a correction data table containing correction data indicating the number of times the unit current pulse should be supplied to each unit heating element.

Next, the energization operation for the thermal head (heating element H) of the thermal printer having the above-described configuration shown in FIG. 1 will be described. In FIG. 1, each print dot of print data corresponding to each pixel of image information created or processed by a higher-level information processing device of this thermal printer (not shown), that is, each unit heating element H ₁ , ... The print data I including the digital data indicating the gradation of the print density for each heating element number designated in correspondence with H _i , ..., H _n is the input interface for each line of the thermal head (heating element H). Enter 1. As described above, the print data I is printed in units of one line of the thermal head in the order of the heating element numbers corresponding to the unit heating elements H ₁ , ..., H _i , ..., H _n. Input sequentially according to the dot order of one column. The corresponding pulse is applied from the data conversion table memory 2 in which the data conversion table is recorded as described above according to the data indicating the gradation of the print density in each dot contained in the print data I input to the input interface 1. Data indicating the number of times is searched, and when the gate 3 is opened as gradation data, it is recorded in the strobe data memory data section 4a of the strobe data memory 4. The strobe data memory data section 4a has a print density corresponding to each heating element number indicating each heating element H ₁ , ..., H _i , ..., H _n of the thermal head (heating element H). showing a gradation is recorded i.e. print density gradation each unit heating elements corresponding to _{H 1, ··, H i,} ··, as the maximum number of applications to be applied to H _n pieces of binary numerical data . In this binary numerical data, for example, 1 indicates that a current pulse is applied and 0 indicates that no current pulse is applied. Further, in the strobe data memory data section 4a, gradation data corresponding to one line of the thermal head, that is, a plurality of times of printing corresponding to the performance of the printer, are sequentially recorded.

The print data I input to the input interface 1 is also input to the thermal head dot position counter 7 and counts the number of data for each unit heating element described above. That is, the content value of the thermal head dot position counter 7 indicates the heating element number described above. The heating element number counted by the thermal head dot position counter 7 is input to the heating element resistance value data memory 8 and corresponds to this heating element number recorded in the heating element resistance value data memory 8, as described above. Search for a pre-recorded numerical value indicating the resistance value of the unit heating element. The numerical value indicating the retrieved resistance value is input to the correction data table memory 9. Further, the data indicating the gradation of the print density corresponding to the heating element number counted by the thermal head dot position counter 7 is input in parallel to the correction data table memory 9 at the same timing. Correction data table From the correction data table recorded in advance in the memory 9, reference is made to the two input signals, that is, the numerical value indicating the resistance value corresponding to the predetermined heating element number and the data indicating the gradation of the print density. Then, the number of times the unit current pulse is applied is retrieved as correction data. The correction data indicating the number of times of application of the unit current pulse retrieved from the correction data table memory 9 is recorded in the strobe data memory correction data portion 4b of the strobe data memory 4 when the gate 3 is opened. In the strobe data memory correction data section 4b, heat is generated in each unit corresponding to each heating element number indicating each unit heating element H ₁ , ..., H _i , ..., H _n of the thermal head (heating element H). body _{H 1, ··, H i,} ··, is recorded as the maximum number of applications to be applied to each H _n pieces of binary numerical data. In this binary numerical data, for example, 1 indicates that a current pulse is applied and 0 indicates that no current pulse is applied. As a result of the operation as described above, the correction data indicating the number of times of application of the unit current pulse recorded in the strobe data memory correction data section 4b is the thermal head (heat generation) recorded in the strobe data memory data section 4a. It is recorded at the same timing as the data for one line of printing of the body H). Further, in the strobe data memory data section 4a, gradation data corresponding to the performance of this printer, at least for one line of the thermal head, that is, for printing once or more than once, is sequentially recorded. .

When the printing of the previous one line by the thermal head is completed, the gradation counter 5 has a pulse oscillation function, and outputs to the strobe data memory 4 and the thermal head driver 6 while counting the oscillation pulses. In the strobe data memory 4 to which the pulse is input from the gradation counter 5, the maximum number of application binary data corresponding to the line to be printed this time recorded in the strobe data memory correction data section 4b by this input pulse is stored. The data is sequentially read to the thermal head driver 6. The thermal head driver 6 has an AND gate in the input section, and the correction data sent from the strobe data memory correction data section 4b synchronized with the pulse input from the grayscale counter 5 is a binary numeral unit of 1 An applied current pulse is output to the heating elements H ₁ , ..., H _i , ..., H _n . Also, each of the unit heat generating element H ₁ 0 correction data in binary numbers sent from the strobe data memory correction data unit 4b to be synchronized to the pulse inputted from the gradation counter _{5, · ·, H i,} ··, No applied current pulse is output to H _n . Therefore, the thermal head driver 6 energizes the unit heating element indicated by the input heating element number with a pulse current of a predetermined value set in the thermal headed driver 6 in response to the above-mentioned input pulse. That is, the total energization time for each unit heating element is changed and adjusted by the number of pulses indicated by the correction data.

When the count content of the gray scale counter 5 matches the maximum number of times of application, the count content of the gray scale counter is reset, and again output to the strobe data memory 4 and the thermal head driver 6 while counting the oscillation pulse. In the strobe data memory 4 to which the pulse is input from the gradation counter 5, the maximum number of times of binary number data corresponding to the line to be printed this time recorded in the strobe data memory data section 4a by the input pulse is converted into thermal data. The data is sequentially read to the head driver 6. The thermal head driver 6 is a unit heating element H ₁ , ..., H _i , in which the gradation data sent from the strobe data memory data unit 4a synchronized with the pulse input from the gradation counter 5 is 1 in binary number. ..., the H _n outputs the applied current pulse. Further, each unit heating element H ₁ , ..., H _i , in which the grayscale data sent from the strobe data memory grayscale data section 4a synchronized with the pulse input from the grayscale counter 5 is a binary number 0, .., No applied current pulse is output to H _n . Therefore, the thermal head driver 6 energizes the unit heating element indicated by the input heating element number with a pulse current of a predetermined value set in the thermal headed driver 6 in response to the above-mentioned input pulse. That is, the total energization time for each unit heating element is adjusted by the number of pulses indicated by the gradation data.

By the above-described operation, the unit heating element is supplied with a pulse current having a predetermined energization time according to the correction data and the gradation data, and is energized. Therefore, the sublimation print function works and printing is performed with the correct gradation according to the input print data. When the count content of the gradation counter 5 matches the maximum number of times of application, that is, when printing of one line with the thermal head using the gradation data and the correction data is completed, the gate 3 is opened and the print data of the next line is opened. Is input to the strobe data memory 4 in the same manner as described above. Printing is executed according to the next gradation data and correction data recorded in the strobe data memory 4. When the printing of one line by the thermal head is completed, the gate 3 described above writes the correction data and the gradation data alternately to the strobe data memory 4 at a predetermined address where the printing of each recording data is completed. To be opened.

The above description shows one embodiment based on the present invention, and it is needless to say that various modifications can be made based on the technical idea based on the present invention. That is, in the embodiment described above, on a line-by-line basis with respect to the heating element H illustrated in FIG. 2, information indicating the gradation of printing density corresponding to each unit heat generator, data against the unit heating element H ₁ The example in which the print data sequentially formed from the data to the unit heating element H _{n is} sequentially input has been described, but for the thermal head of other structures, the data structure corresponding to the structure of the thermal head is input. , The data processing function should be configured to operate properly according to the data structure. For example, the unit heating elements may be collected in a predetermined unit in the input print data, and the heating element number may be attached as a reference, and the processing utilizing the indicator may be executed. When the image information to be printed is an analog value, a necessary functional circuit such as an AD converter having appropriate performance may be added to the input section. Also, in order to adjust the print density, the total energization time for each unit heating element was changed by changing the number of fixed current pulses applied to each divided unit heating element. The current value to be applied to the heating element may be changed, or the time for applying a constant current value may be changed. Also, the pulse applied to the unit heating element is described as a current pulse, but it is natural that the same function can be achieved even if it is a voltage pulse. In the above description of the embodiment of the present invention, the circuit configuration shown by the configuration of the block functional circuit shown in FIG. 1 is configured as a control circuit for operating a sublimation thermal printer or other corresponding hot printer. However, all or any of the data conversion table memory 2, the heating element resistance value data memory 8, the correction data table memory 9, etc. may be stored in one of the ROMs belonging to the host information processing device (not shown). Part, the strobe data memory 4 uses part of the RAM belonging to the host information processing device (not shown), and the appropriate function uses part of the host information processing device (not shown). Alternatively, the functions of the gate 3 and the gradation counter 5 may be soft-processed by a program. Further, the gradation counter 5 may count from zero, or a predetermined number of times of application may be set in advance to subtract to zero. The means for printing according to the data stored in the strobe data memory may be set appropriately according to the functions of the thermal head and the thermal head driver. It is needless to say that the function described in the thermal head driver may be provided in the energizing function as illustrated in the circuit configuration of FIG. 1 of the thermal printer, other than the function provided in the thermal head itself. As described above, the function of this invention may be executed by an appropriate processing means and structure corresponding to the functions and structures of this thermal printer and its upper information processing device (not shown) and the structure of the thermal head. Of course.

[0018]

[Effect of device]

 Since the thermal printer of the present invention is configured as described above, it has the following excellent effects. A print having a high gradation such as 256 levels can be realized without being affected by the resistance deviation of the heating element forming the print head. Since printing with high density gradations can be realized, the functions of sublimation thermal printers suitable for continuous gradation of print density can be effectively used.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a thermal printer showing an energization function corresponding to a command print density for a thermal head for explaining a thermal printer having a resistance correction function for a thermal head heating element according to the present invention.

FIG. 2 is a schematic structural example diagram illustrating a structure of a heating element of a thermal head applied to an embodiment of the present invention.

FIG. 3 is a graph showing an example of resistance value deviation characteristics of a heating element for a thermal head.

FIG. 4 is a schematic block diagram of a conventional thermal printer showing an energization function corresponding to a command print density for a thermal head.

[Explanation of symbols]

 1: Input interface 2: Data conversion table memory 3: Gate 4: Strobe data memory 4a: Strobe data memory data section 4b: Strobe data memory correction data section 5: Gradation counter 6: Thermal head driver 7: Thermal head dot position counter 8: Heating element resistance value data memory 9: Correction data table memory I: Input data H: Heating element

Claims (2)

[Scope of utility model registration request] 1. A print head having a print density written in print data on each unit heating element of a thermal head formed by aligning unit heating elements corresponding to respective dots of print data input for printing in a predetermined shape. In a thermal printer adapted to apply an electric quantity corresponding to a tone, a memory for recording resistance value data relating to the resistance value of each unit heating element in advance, and a print described in the resistance value data and the print data. A correction data table memory for recording a correction data table for searching the correction data from the density gradation data, and the correction data table memory corresponding to the gradation of the print density described in the print data. The resistance of the thermal head heating element is characterized in that the amount of electricity to be applied to each unit heating element is corrected. A thermal printer with a resistance correction function. 2. The resistance value correction function of the thermal head heating element, wherein the quantity of electricity according to claim 1 is adjusted by the total energization time of voltage or current of a predetermined value corresponding to the resistance value of the unit heating element. Thermal printer.