JP4320478B2 - Printer and printing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sublimation printer or the like that transfers ink by heat. Printer And a printing method.
[0002]
[Prior art]
A sublimation printer is known as one of apparatuses that print characters, images, and the like on predetermined paper. A sublimation printer performs printing by dot printing by thermally transferring ink applied to an ink ribbon onto a printing paper by a thermal head provided with minute heating elements. It has the feature that it can do. For this reason, the printing technology of a sublimation printer is widely used as a technology capable of printing an image including an intermediate gradation such as a photograph.
[0003]
Gradation control in this sublimation type printer is generally performed by controlling the amount of heat applied from the thermal head to the ink ribbon according to the density to be printed. For example, Japanese Patent Application Laid-Open No. 7-148963 discloses a technique for controlling gradation by changing the pulse width of a pulse current supplied to a thermal head to control the amount of heat to the ink ribbon.
[0004]
[Problems to be solved by the invention]
By the way, when it is intended to obtain a large number of print density gradations by the above-described sublimation type printer, it is common to improve the accuracy of the thermal amount control of the thermal head.
[0005]
However, in sublimation printers, printing due to the mechanical physical structure, such as the contact pressure of the ink ribbon with the transfer paper, the variation in the amount of heat applied from the thermal head, the uneven density of the ink applied to the ink ribbon, etc. There are several factors that change the concentration. For this reason, extremely high technology is required to accurately control the print density, and with conventional sublimation printers, there is a limit to the number of gradations that can be achieved even when the thermal control accuracy of the thermal head is increased. There is a problem that a desired number of gradations may not be obtained due to a variation factor. In sublimation printers currently in practical use, the number of gradations that can be controlled per dot is limited to a maximum of 256 gradations, and the realization of further multi-gradation printing is desired.
[0006]
The present invention has been made in view of such circumstances, and printing with a large number of gradations can be performed without requiring high-accuracy thermal head heat amount control and other advanced techniques. Printer And a printing method.
[0007]
[Means for Solving the Problems]
Invention of Claim 1 Printer Is A winding roller to which an ink ribbon having a plurality of sections with different concentrations of applied ink is attached, a motor for rotating the winding roller to wind the ink ribbon, and an amount of heat to the ink ribbon In addition, a thermal head capable of thermal transfer at a predetermined density in a plurality of stages, and print data in which each dot and gradation are associated with each other, the motor and the thermal head are controlled to control dot units. And a control unit that performs printing at a plurality of gradations, and the control unit drives the thermal head, and according to the density to be printed on each dot, a plurality of sections of the ink ribbon. For dots that should be printed at a density higher than the printable density in the zone with the lowest ink density, add heat to the zone with the lowest ink density. And transferring the heat to a higher density section than the section having the lowest ink density and transferring it in an overlapping manner, so that the density of the ink ribbon is higher than the density that can be expressed in the lowest ink density section. Printing is possible, and printing is possible with a plurality of density gradations that sequentially change at a constant rate for one gradation that can be expressed in the section where the ink density of the ink ribbon is the lowest. It is characterized by that.
[0008]
The invention described in claim 2 is described in claim 1. Printer In The thermal head is capable of thermal transfer at a plurality of n levels including the 0th stage in which thermal transfer is not performed under the control of the control means, and the winding roller has the ink ribbon as the ink ribbon. A first section, a second section, and a third section in which the density of the ink becomes higher in order of double and quadruple are attached, and the control means does not print each dot as the print data. Data associated with any of the N gradations including N = 4 · n including the 0th gradation is input, and the gradation associated with the print data for each dot. Is a first gradation section where 0 ≦ N ≦ n−1, a second gradation section where n ≦ N ≦ 2 · n−1, and 2 · n ≦ N ≦ 4 · n−1. To determine one of the third gradation divisions, and drive the motor The first section of the ink ribbon is arranged at a position where the ink can be transferred to the printing medium, and the thermal head is driven so that each of the dots in the first gradation section is the first. The ink is transferred by applying an N-th heat amount corresponding to the number of gradations of each dot to the section, and for each of the dots in the second gradation section, the level of each dot in the first section is transferred. Ink is transferred by applying a heat amount that is the 0th or 1st stage, which is the remainder when the logarithm N is divided by 2, and for each of the dots in the third gradation section, Ink is transferred by applying the 0th, 1st, 2nd, or 3rd stage heat quantity that is the remainder of dividing the number of gradations N of each dot by 4 in one section, and the motor is driven. Ink the print media The second section of the ink ribbon is arranged at a position where the image can be copied, and the thermal head is driven so that the number of gradations of each dot in the second section for each of the dots in the second gradation section. The amount of heat corresponding to an integer value when N is divided by 2 is added to transfer the ink in a superimposed manner, and the motor is driven to move the ink to a position where the ink can be transferred to the printing medium. An integer value obtained by arranging the third section of the ribbon and driving the thermal head to divide the number of gradations N of each dot in the third section by 4 for each of the third gradation sections. By transferring the heat amount that becomes the number of steps, the ink is transferred in layers It is characterized by that.
[0009]
The invention described in claim 3 Using a thermal head capable of thermal transfer at a predetermined density in a plurality of stages and an ink ribbon having a plurality of sections with different concentrations of applied ink, printing is performed in a plurality of gradations in dot units. Printing method, The control means has the lowest ink density among the plurality of sections of the ink ribbon according to the density to be printed on each dot. On the interval Above Thermal head Heat Add quantity T Transcribe The first printing step and the control means for the dot to be printed at a density higher than the density that can be printed in the section with the lowest ink density of the ink ribbon, the density higher than the section with the lowest ink density. of On the interval Above Add heat from the thermal head T The Repeatedly Transcribe A second printing step, enabling printing at a density higher than the density that can be expressed in a section where the ink density of the ink ribbon is the lowest, and expressing in a section where the ink density of the ink ribbon is the lowest Enables printing with multiple density gradations that change sequentially at a constant rate for a single gradation. It is characterized by that.
[0010]
The invention according to claim 4 is the claim of claim 3 Description Sign of Printing method In this embodiment, a thermal head that can be thermally transferred at n stages of density including the 0th stage where thermal transfer is not performed is used, and the ink density of the ink ribbon is doubled or quadrupled. The first printing step uses the first section, the second section, and the third section that increase in order, and the first printing step uses the 0th gradation that is not printed in each dot as the print data. Data in which any one of the N gradations including N = 4 · n is associated is input to the control unit, and the control unit associates each dot with the print data. The first gradation section where 0 ≦ N ≦ n−1, the second gradation section where n ≦ N ≦ 2 · n−1, and 2 · n ≦ N ≦ 4 · First to determine which of the third gradation divisions is n−1 And a step of driving a motor that rotates a take-up roller that winds up the ink ribbon to place the first section of the ink ribbon at a position where the ink can be transferred to a printing medium. And the control means causes the thermal head to add an N-th stage heat amount corresponding to the number of gradations of each dot to the first section for each of the dots of the first gradation classification. Thus, for each of the dots in the second gradation section, the 0th or first stage, which is the remainder when the number of gradations N of each dot is divided by 2 in the first section, Ink is transferred by applying a certain amount of heat, and for each of the dots in the third gradation section, the 0th is the remainder obtained by dividing the number N of gradations of each dot by 4 in the first section. , And a third step of transferring the ink by applying an amount of heat in the first, second or third stage. In the second printing step, the control means drives the motor to perform printing. A fourth step of disposing the second section of the ink ribbon at a position where ink can be transferred to a medium; and the control means uses the thermal head for each of the dots in the second gradation section. A fifth step of transferring the ink in a superimposed manner by adding a heat quantity that is an integer value when the gradation number N of each dot is divided by 2 in the second section; A sixth step of driving the motor to place the third section of the ink ribbon at a position where ink can be transferred to the print medium; and the control means uses the thermal head to perform the third gradation classification. of For each, a seventh step of transferring the ink in a superimposed manner by adding a heat quantity that is an integer value when the gradation number N of each dot is divided by 4 is added to the third section. It is characterized by that.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. First, a premise configuration to which the ink ribbon and the printing method according to the present invention are applied will be described. FIG. 1 is a diagram illustrating a mechanical configuration of a printer which is an example of the premise configuration.
[0012]
In FIG. 1, reference numeral 1 denotes a printing paper stored in a roll shape, and a core portion is attached to the rotating shaft 2. The rotary shaft 2 rotates in the direction of arrow A when the printing paper 1 is taken up and rotates in the direction of the arrow A in the figure. When the printing paper 1 is conveyed by a conveyance mechanism which will be described later, the rotation braking force acts. It rotates in the direction of the middle arrow B, and the printing paper 1 is sent out while maintaining a certain tension.
[0013]
Reference numerals 3 and 4 denote rollers for guiding the conveyance of the printing paper 1. One end of the printing paper 1 is guided to a gap formed between the platen roller 5 and the thermal head 6 through these rollers 3 and 4. Yes. An ink ribbon 7 is also guided in the gap, and the platen roller 5 is displaced by the operation of a solenoid (not shown), and the printing paper 1 and the ink ribbon 7 are in contact with each other during printing (dot printing). The head 6 is brought into contact with the head 6. The thermal head 6 is provided with a minute heating element that generates heat by a pulse current (described later) supplied at the time of printing, and the ink on the ink ribbon 7 is thermally transferred onto the printing paper 1 with an amount of heat corresponding to the pulse current. .
[0014]
As for the ink ribbon 7, the unused part is accommodated in the unwinding roller 8a, and the already used part is accommodated in the take-up roller 8b. The unwinding roller 8a is provided with a brake 9 for rotational braking, and the ink ribbon 7 is unwound while maintaining a certain tension. The ink ribbon 7 coming out from the take-out roller 8a is guided to the gap together with the printing paper 1 via the roller 10, peeled off from the printing paper 1 at the gap outlet, and taken up by the take-up roller 8b. . Reference numeral 11 denotes a DC motor. The rotational driving force of the DC motor 11 is supplied to the take-up roller 8b via a predetermined roller, whereby the take-up operation of the ink ribbon 7 is performed.
[0015]
Reference numeral 12 is a paper feed pulse motor, and 13 is a paper feed roller. The printing paper 1 is guided between them, is sent out by the driving force of the pulse motor 12, and is discharged through a roller 14.
[0016]
The above-mentioned transport mechanism is a portion constituted by the rotary shaft 2, rollers 3, 4, pulse motor 12, paper feed roller 13 and roller 14, and by these, the printing paper 1 is sent out to the paper discharge side. Returned to the rotating shaft 2 side. Such a printing paper return mechanism is a technique that has already been adopted in general color printers and the like.
[0017]
Next, the configuration of a control system that controls the mechanical configuration of FIG. 1 by exchanging electrical signals will be described. FIG. 2 shows an example of the configuration. In this figure, components corresponding to those in FIG. 1 are denoted by the same reference numerals.
[0018]
In FIG. 2, a data buffer 20 accumulates print data supplied from the outside and supplies the print data to the CPU 21. Here, the print data is data indicating the density gradation of the dot to be printed. If the number of gradations of the print density is N, “0” (lowest density) to “N−1” (highest density). One of the values is indicated. The data buffer 20 starts to supply the print data to the CPU 21 from the time when the print data or one page of the print image is accumulated, and the print data for each line in the main scanning direction on the page in response to a request from the CPU 21. Supply sequentially. The number of print data for one line is equal to the width of the printing paper. For example, when the scanning line in the longitudinal direction of the printing paper is 12 lines / mm, the number of print data for one line that the data buffer 20 supplies to the CPU 21 at a time. Is about 2560 dots.
[0019]
The CPU 21 instructs the pulse generator 22 to output a pulse current based on the print data received from the data buffer 20, and instructs the driver 23 to operate each motor and the like according to a predetermined print operation program. The specific contents of the CPU 21 and instruction operations will be described later.
[0020]
The pulse generator 22 generates a pulse current according to an instruction from the CPU 21 and supplies the pulse current to the thermal head 6. The pulse generator 22 and the thermal head 6 are capable of dot printing of 256 gradations that are generally used conventionally, and data in which any density of 256 gradations is “0” to “255”. The pulse generator 22 sends an energization pulse to the thermal head 6 only for a time corresponding to the indicated density data, whereby the heating element of the thermal head 6 generates heat and the thermal transfer to the printing paper 1 is performed. . For example, assuming that the energization time for printing the maximum density is 4 msec, when the density instruction data is “N”, an energization pulse is sent to the thermal head 6 for a time of “4 msec × N / 255”, and printing is performed. A dot having a density of N + 1 gradations is printed on the paper 1.
[0021]
The driver 23 supplies drive current to the pulse motor 12, the DC motor 11, and the solenoid 24 in accordance with operation instructions from the CPU 21, and executes the various operations in FIG. The solenoid 24 corresponds to a solenoid that displaces the platen roller 5 described above.
[0022]
Based on the above premise configuration, an ink ribbon and a printing method according to an embodiment of the present invention will be described below. FIG. 3 is a diagram showing a configuration of an ink ribbon according to an embodiment of the present invention. However, this figure shows only a part of the ink ribbon, and the overall configuration is such that a large number of three sections (1) to (3), which will be described later, are continuously arranged in the horizontal direction in the figure. ing.
[0023]
In FIG. 3, (1) is a section where 25% density ink is applied, (2) is a section where 50% density ink is applied, and (3) is 100% density ink applied. It is a section. The ink ribbon has a configuration in which these three types of ink density are repeatedly and continuously arranged as shown in the figure. According to this configuration, even if the number of gradations by the thermal amount control of the thermal head is limited, the density of dots to be printed changes depending on which density ribbon is used, and printing is performed once more. However, the dot density can be further changed by printing with ink ribbons in other density sections. Therefore, according to the present ink ribbon, printing with a larger number of gradations can be performed with a thermal head similar to the conventional one.
[0024]
Next, a printing method according to an embodiment of the present invention will be described. In this printing method, the ink ribbon shown in FIG. 3 is used as the ink ribbon 7 in FIG. 1, and the CPU 21 in the control system in FIG. Is.
[0025]
At the start of the operation of the following printing method, the head of the 25% density section (1) of the ink ribbon 7 is positioned at the heating element position of the thermal head 6, and the printing start position of the printing paper 1 is the same heat generation. It shall be in the body position. At the time of printing, control is performed so that the solenoid 24 operates and the platen roller 5 contacts the thermal head 6 with the ink ribbon 7 in contact with the printing paper 1 to perform thermal transfer.
[0026]
First, it is determined whether or not each of the first one line of print data supplied from the data buffer 20 is '255' or less. For print data of “255” or less, the value as it is is sent to the pulse generator 22 as the density instruction data, and a pulse current is generated to energize the thermal head 6. For example, if the print data value is “40”, an energization pulse is sent to the thermal head 6 for a time of “4 msec × 40/255”, and if it is “255”, an energization pulse for a time of “4 msec × 255/255”. (The latter energization time is the time for printing the maximum density with an ink ribbon having a density of 25%.) As a result, for the print data of “255” or less, a print operation is performed with an ink ribbon having a density of 25% at the gradation indicated by the print data.
[0027]
On the other hand, print data of “255” or more is handled as follows. First, for print data of “256” to “511” (hereinafter, the value of the print data is assumed to be “N”), the remainder of N / 2 is sent to the pulse generator 22 as density instruction data, and the remainder is the same. The thermal head 6 is energized for a time corresponding to the minute. For the print data of “512” to “1023”, the remainder of N / 4 is sent to the pulse generator 22 as density instruction data, and the thermal head 6 is energized for the time corresponding to the remainder.
[0028]
In this way, printing is performed in accordance with the print data corresponding to each dot, and when the printing operation for one line is finished, the pulse motor 12 is driven and the printing paper 1 is sub-scanned for one line together with the ink ribbon 7. Send out in the direction. Then, the next one line of print data is supplied from the data buffer 20, and the same print operation is repeated for each print data. Thereafter, similarly, the feeding of the printing paper 1 and the ink ribbon 7 and the printing operation for each line are sequentially performed up to the last line on the currently printed page. Thus, when the printing operation up to the final line is completed, the printing operation using the ink ribbon having a density of 25% is completed.
[0029]
Here, as for the print data of “0” to “255”, as described above, the printing operation is performed with the value as it is using the ink ribbon having the density of 25%. Therefore, in the present embodiment, it is assumed that the dots corresponding to the print data “0” to “255” printed thereby have a density of 256 gradations, and the density (25% density divided into 256 gradations ( Since “0” is included, the density (25% / 255) is set to the density for one gradation.
[0030]
Next, the DC motor 11 is driven to wind the ink ribbon 7 toward the take-up roller 8b, and the head of the 50% density section (2) is positioned at the heating element position of the thermal head 6. Further, the rotary shaft 2 is driven to rotate to wind up the printing paper 1 for one page, and the printing start position of the printing paper 1 is returned to the heating element position again.
[0031]
Then, the printing operation using the ink ribbon having a density of 50% is started again for the print data for the first line. In this printing operation, printing is not performed for print data “0” to “255” and “512” to “1023”, but only printing is performed for print data “256” to “511”.
[0032]
For this reason, first, only print data having a value of “256” to “511” is selected. Subsequently, for the selected print data, the value of the integer part of N / 2 is sent to the pulse generator 22 as density instruction data, and the thermal head 6 is energized for the time corresponding to the integer.
[0033]
In this way, the printing operation for only the print data of “256” to “511” is sequentially performed, and when this operation is completed for one line, the printing paper 1 and the ink ribbon 7 are sent out in the sub-scanning direction for one line. Thereafter, in the same manner, the printing operation for only the print data “256” to “511” is sequentially performed for each line, and when the printing operation up to the final line is finished, the printing operation with the ink ribbon of 50% density is finished. To do.
[0034]
Here, when the print data of “256” to “511” is divided by 2 and printing is performed with an ink ribbon having a density of 50% using the integer part as density instruction data, the density to be printed is converted into the above-described gradation. Since “(N / 2 integer part) × 2”,
256, 256, 258, 258, 260, 260, ..., 510, 510
It becomes.
[0035]
However, since dots corresponding to these print data have already been printed using an ink ribbon with a density of 25% using the remainder of N / 2 as density instruction data, the above gradation is superimposed on the print data. Will be printed. Therefore, the dots corresponding to the print data such as '257' and '259' have a gradation density added by 1 to the above gradation, and the gradation of the printed density eventually becomes
256, 257, 258, 259, 260, 261, ..., 510, 511
It becomes.
[0036]
Next, the DC motor 11 is driven to wind the ink ribbon 7 toward the take-up roller 8b, and the head of the 100% density section (3) is positioned at the heating element position of the thermal head 6. Further, the rotary shaft 2 is driven to rotate to wind up the printing paper 1 for one page, and the printing start position of the printing paper 1 is returned to the heating element position again.
[0037]
Then, the printing operation for the first one line of print data is started again with an ink ribbon having a density of 100%. In this printing operation, printing is not performed for print data “0” to “511”, but only printing is performed for print data “512” to “1023”.
[0038]
For this reason, first, only print data having a value of “512” to “1023” is selected. Subsequently, for the selected print data, the value of the integer portion of N / 4 is sent to the pulse generator 22 as density instruction data, and the thermal head 6 is energized for the time corresponding to the integer.
[0039]
In this way, the printing operation for only the print data of “512” to “1023” is sequentially performed, and when this operation is completed for one line, the printing paper 1 and the ink ribbon 7 are sent out in the sub-scanning direction for one line. Thereafter, in the same manner, the printing operation for only the print data of “512” to “1023” is sequentially performed for each line, and when the printing operation up to the final line is finished, the printing operation with the ink ribbon of 100% density is finished. To do.
[0040]
Here, when the print data of “512” to “1023” is divided by 4 and printing is performed with a 100% density ink ribbon using the integer portion as the density instruction data, the density to be printed is converted into the above-described gradation. Since '(N / 4 integer part) x 4',
512, 512, 512, 512, 516, 516, 516, 516,
520, ..., 1016, 1020, 1020, 1020, 1020
It becomes.
[0041]
However, for the dots corresponding to these print data, printing using an ink ribbon with a density of 25% using the remainder of N / 4 as density instruction data has already been performed. That is, a density corresponding to one gradation is already printed on a dot corresponding to print data having a remainder of N / 4 such as '513' or '517', and N / N such as '514' or '518'. Dots corresponding to print data with a remainder of 4 being 2 have already been printed with a density corresponding to 2 gradations, and dots corresponding to print data with a remainder of N / 4 such as '515' or '519' The three-tone density has already been printed. For this reason, for the print data of “512” to “1023”, the density of the above gradation is printed on top of the density already printed. ,
512, 513, 514, 515, 516, 517, 518, 519,
520, ..., 1019, 1020, 1021, 1022, 1023
It becomes.
[0042]
For example, when the print data supplied from the outside for a certain dot is “1023” indicating the highest density,
1023/3 = 255, remainder 3
Therefore, the density of the remainder 3 is printed with a density of “3” with an ink ribbon having a density of 25%, and the density of the remaining 1020 is printed with a density of “255” with an ink ribbon with a density of 100%. .
[0043]
Through the above printing operation, printing for one page is performed with the density corresponding to the print data of “0” to “1023”, that is, the density of 1024 gradations.
[0044]
When the printing operation with the 100% density ink ribbon is completed, the printing paper 1 is sent to the roller 14 side and discharged. Further, the DC motor 11 is driven to print the ink ribbon 7 to the take-up roller 8b side for printing the next page, and the head of the unused 25% density section (1) at the heating element position of the thermal head 6 is used. Position.
[0045]
Although the embodiments of the present invention have been described above, the ink ribbon and the printing method according to the present invention are not limited to the above-described embodiments. For example, the ink ribbon realizes printing of 1024 gradations by a configuration in which inks of three different densities are continuously applied. If a finer number of gradations is required, the density is 12.5. Printing with 2048 gradations can be realized by adding a section where% ink is applied. That is, if a fine gradation number is necessary, a lower density section may be added accordingly, or the number of sections may be increased by reducing the density difference for each section.
[0046]
Further, in the above-described embodiment, the ink ribbon in which the density is linearly arranged such as 100%, 50%, and 25% has been described. However, the present invention is not limited to this, and the ink ribbon having a non-linear density array is often used. Can be obtained. However, in the printing operation at each density in that case, it is necessary to obtain a print instruction value corresponding to the density instruction data by a calculation method according to the non-linear density array.
[0047]
【The invention's effect】
As described above, according to the present invention, since a plurality of sections in which inks having different densities are applied are provided on the ink ribbon, printing of different density gradations can be performed by using each section. it can. As a result, there is an effect that printing with a large number of gradations can be performed without requiring high-accuracy thermal head heat amount control and other advanced techniques.
[0048]
Also Since the plurality of sections are sections from the low density to the high density where the density sequentially changes for each section, many gradations that change sequentially from the low density to the high density without requiring any advanced technique as described above. Obtainable.
[0049]
And ,mark In addition to transferring the amount of heat corresponding to the print density from the thermal head to one of the plurality of sections, the ink is transferred to the printing portion, and the amount of heat corresponding to the print density is also applied to the other section from the thermal head. Since the ink is transferred, the density gradation is printed with the density of the other section in addition to the density gradation printing with the density of the one section. Therefore, even if the number of gradations that can be expressed by the thermal amount control of the thermal head is limited, different gradations can be expressed according to the density of each section, and a large number of gradations combining these density gradations can be expressed. Tones can be obtained.
[0050]
In particular, the low density printed portion is printed by the low density section, and the high density printed portion is printed by the low density section which is not represented by the printing by the high density section, and is printed by the high density section. Do And Also, printing with a large number of density gradations that sequentially change at a constant rate from a low density to a high density is possible without requiring any advanced technology.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a mechanical configuration of a printer as an example of a premise configuration for application of the present invention.
FIG. 2 is a diagram showing a configuration of a control system that controls the mechanical configuration of FIG. 1;
FIG. 3 is a diagram illustrating a configuration of an ink ribbon according to an embodiment of the present invention.
[Explanation of symbols]
1 Printing paper
6 Thermal head
7 Ink ribbon
21 CPU
22 Pulse generator

Claims (4)

A winding roller to which an ink ribbon having a plurality of sections having different concentrations of applied ink is attached;
A motor for rotating the winding roller to wind up the ink ribbon;
A thermal head capable of applying heat to the ink ribbon and thermally transferring it at a predetermined density in a plurality of stages;
Control means for controlling the motor and the thermal head based on the input of print data in which each dot and gradation are associated with each other, and performing printing at a plurality of gradations in dot units,
The control means drives the thermal head, and according to the density to be printed on each dot, the density is higher than the printable density in the lowest ink density section of the plurality of sections of the ink ribbon. For dots to be printed with density, the amount of heat is applied to the section with the lowest ink density and transferred, and the amount of heat is added to the section with the density higher than the section with the lowest ink density, and transferred.
Enabling printing at a density higher than the density that can be expressed in the section where the ink density of the ink ribbon is the lowest, and
A printer capable of printing with a plurality of density gradations that sequentially change at a constant rate for one gradation that can be expressed in a section where the ink density of the ink ribbon is the lowest. The printer according to claim 1.
The thermal head is capable of thermal transfer at a plurality of n levels including a 0th stage in which thermal transfer is not performed under the control of the control means.
The winding roller is attached with an ink ribbon having three sections, a first section, a second section, and a third section, in which the ink density increases in order of 2 times and 4 times,
The control means includes
As the print data, data in which any one of N gradations of N = 4 · n including the 0th gradation that is not printed is associated with each dot is input. A first gradation section in which gradations associated with the print data are 0 ≦ N ≦ n−1, a second gradation section in which n ≦ N ≦ 2 · n−1, and 2 Determine any of the third gradation divisions where n ≦ N ≦ 4 · n−1,
  Driving the motor to dispose the first section of the ink ribbon at a position where ink can be transferred to a print medium;
Ink is transferred by driving the thermal head and applying an N-th stage heat amount corresponding to the number of gradations of each dot to each of the dots in the first gradation section. Then, for each of the dots in the second gradation section, the first section is applied with the amount of heat in the 0th or first stage, which is the remainder when the gradation number N of each dot is divided by 2. The ink is transferred, and for each of the dots in the third gradation section, the 0th, 1st, 1st, and 2nd are the remainders obtained by dividing the gradation number N of each dot by 4 in the first section. In addition to transferring the ink by adding the amount of heat that becomes the second or third stage,
Driving the motor to place the second section of the ink ribbon at a position where the ink can be transferred to the print medium;
  When the thermal head is driven, for each of the dots in the second gradation section, the amount of heat at which the number of steps becomes an integer value when the number of gradations N of each dot is divided by 2 in the second section Is added to transfer the ink in layers,
Furthermore, by driving the motor, the third section of the ink ribbon is arranged at a position where the ink can be transferred to the printing medium,
  The thermal head is driven, and for each of the third gradation divisions, the amount of heat corresponding to the stage number that becomes an integer value when the gradation number N of each dot is divided by 4 is added to the third section. A printer characterized by transferring ink in a superimposed manner. Printing method for performing printing at a plurality of gradations in dot units using a thermal head capable of thermal transfer at a predetermined density in a plurality of stages and an ink ribbon having a plurality of sections in which the density of applied ink is different Because
Control means, depending on the concentration to be printed in each dot, the first to transfer the Lee ink by adding the thermal head or we heat quantity most ink density is lower sections of the plurality of sections of the ink ribbon Printing process,
Said control means, the most ink density to be printed at a higher density than the printable density at low period dots of the ink ribbon, the amount of heat from the thermal head section of the higher than most ink concentration is lower sections concentration and a second printing step of transferring overlapping the Lee ink by adding,
Enabling printing at a density higher than the density that can be expressed in the section where the ink density of the ink ribbon is the lowest, and
A printing method characterized by enabling printing with a plurality of density gradations that sequentially change at a constant rate for one gradation that can be expressed in a section where the ink density of the ink ribbon is the lowest . The printing method according to claim 3,
As the thermal head, a thermal head that can be thermally transferred at a density of n stages including a 0th stage where thermal transfer is not performed is used, and as the ink ribbon, the ink density is doubled and quadrupled in order. Use the first section, the second section, and the third section and the three sections that become higher,
The first printing step includes
As the print data, data in which any gradation of N gradations of N = 4 · n including the 0th gradation not printed is associated with each dot is input to the control means, The control means, for each of the dots, has a gradation associated with the print data in a first gradation division in which 0 ≦ N ≦ n−1, and n ≦ N ≦ 2 · n−1. A first step of determining any one of the two gradation divisions and the third gradation division satisfying 2 · n ≦ N ≦ 4 · n−1;
A second step in which the control means drives a motor that rotates a winding roller that winds up the ink ribbon to place the first section of the ink ribbon at a position where ink can be transferred to a print medium;
The control means causes the thermal head to add an amount of heat at the Nth stage corresponding to the number of gradations of each dot to each of the dots in the first gradation division, thereby causing the ink to flow. For each of the dots in the second gradation section, the amount of heat in the 0th or 1st stage that is the remainder when the number of gradations N of each dot is divided by 2 in the first interval is calculated. In addition, the ink is transferred, and for each of the dots in the third gradation section, the 0th and 1st are the remainders obtained by dividing the gradation number N of each dot by 4 in the first section. , And a third step of transferring the ink by applying a heat amount that becomes the second or third stage,
The second printing step includes
A fourth step in which the control means drives the motor to dispose the second section of the ink ribbon at a position where ink can be transferred to a print medium;
The control means uses the thermal head for each of the dots of the second gradation classification, and the number of steps that becomes an integer value when the gradation number N of each dot is divided by 2 in the second section. A fifth step in which the amount of heat is applied and the ink is superimposed and transferred;
A sixth step in which the control means drives the motor to dispose the third section of the ink ribbon at a position where ink can be transferred to a print medium;
The control means, by the thermal head, for each of the third gradation divisions, the amount of heat at which the number of steps becomes an integer value when the gradation number N of each dot is divided by 4 in the third section. And a seventh step of transferring the ink in a superimposed manner by adding the ink .

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