JPH11245437A - Thermal head for thermal transfer printer and heating drive method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermal head for thermal transfer printing and a heating drive method therefor in which multiple gray level is realized in low gray level region. SOLUTION: In the heating drive method for thermal head, a plurality of sets of heating elements R1-1, R1-2 arranged through slits D1-D7 (48 micron) are juxtaposed sequentially in line at a specified interval (116 micron) wherein the total width (48+48 micron) of a set of heating elements in the line direction is set shorter than the specified interval and the width (150 micron) in the direction orthogonal to the line direction is set longer than the specified interval. Every other set of heating elements is then heated in same line and and the set of unheated heating elements is heated in next line. The alternating heating method is repeated sequentially in subsequently lines thus driving heating of a thermal head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a thermal head used in a thermal transfer printing apparatus and a heating driving method thereof.

[0002]

2. Description of the Related Art FIG. 5A is a schematic plan view of a conventional thermal head used in a thermal transfer printing apparatus. This thermal head H1 has slits d1, d2, d3, d4,.
Through each of the heating resistors r1, r2, r3, r4,.
Are arranged side by side, and these heating resistors are connected to each of the applied electrode portions e1 to e1.
, and a common electrode portion e0, a current is supplied to heat the heater 1, heater 2, heater 3, heater 4, and so on. Heating resistors r1, r3, ...
As described above, every other heating is performed, and in the next line, the heating resistors r2, r4,
, And this heating method is alternately repeated between subsequent lines.

[0005] For example, if a heat generation pattern of print dots is represented by such a method, a heating pattern in a staggered lattice shape as shown in FIG. According to this heating method, the adjacent dots between the same lines and the adjacent dots between the lines are separately heated, so that the spread of the ink to the adjacent dots can be prevented, and the printing blur can be prevented. Things.

[0004]

However, when printing is performed using the thermal head H1 having the above configuration, as shown in FIG. 4, the time from heating to the start of printing is long.
Moreover, the printing starts from a place where the initial starting density is high, and the multi-tone expression in the low-tone area is unsatisfactory.

In this case, from the viewpoint of the structure of the thermal head, the length of the heating resistor is reduced, the area of the heat generating portion is reduced, and the initial density in the low gradation region is reduced to increase the number of gradations. It is conceivable that the heating resistor is formed in a short shape like a glass rod, and there is a problem that productivity is lacking in terms of yield.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a thermal head capable of reducing the initial density in a low gradation region as much as possible and capable of expressing multiple gradations, and a method of heating and driving the same.

[0007]

The present invention, in order to solve the above-mentioned problems, comprises the following means 1) to 3). That is,

1) A thermal head for a thermal transfer printing apparatus, wherein a plurality of heating resistors are arranged side by side at predetermined intervals sequentially in a line with a plurality of heating resistors adjacent to each other via a slit. The total width of the set of heating resistors in the line direction is shorter than the predetermined interval of the set of heating resistors, and the width in the direction orthogonal to the line direction is set to be smaller than the predetermined interval of the set of heating resistors. A thermal head for a thermal transfer printing apparatus, wherein the heating resistor is formed by a negative resistor while being made longer.

2) The method for heating and driving a thermal head for a thermal transfer printing apparatus according to claim 1, wherein:
One set of heating resistors in the same line is heated every other pair, the next line is heated with a set of heating resistors not heated in the previous line, and the subsequent lines are alternately repeated in the heating method. A method for heating and driving a thermal head for a thermal transfer printing apparatus, comprising:

[0010] 3) A plurality of heating resistors are arranged side by side with a predetermined gap in line with a plurality of heating resistors adjacent to each other through a slit as a set. Heating a thermal head for a thermal transfer printing apparatus, wherein the total width in the direction is shorter than the interval between the pair of heat generating resistors, and the width in the direction orthogonal to the line direction is longer than the interval between the pair of heat generating resistors. In the driving method, at the time of thermal transfer printing, every other set of heating resistors in the same line is heated, and in the next line, the set of heating resistors not heated in the previous line is heated, and in the subsequent lines, A heating driving method for a thermal head for a thermal transfer printing apparatus, wherein a heating method is sequentially repeated.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described with reference to preferred embodiments. FIG. 1A is a schematic plan view of a heating resistor of a thermal head used for realizing the head heating driving method of the present invention, and FIG. 1B is a diagram showing a heating pattern by the heating resistor. It is. FIG. 2 is a schematic configuration diagram of a thermal transfer printing apparatus for realizing the heating driving method of the present invention.

In FIG. 1A, a thermal head H2
Means that a plurality of heating resistors R made of, for example, NiCr (temperature gradient −60 ppm / ° C.) whose temperature change is almost zero
1-1, R1-2, R2-1, R2-2, R3-1, R
3-2, R4-1, R4-2,... Are used, each of which has a width of 150 μm × 48 μm and a slit D1, D2, D2, D3 of 10 μm.
Are arranged side by side through D4, D5, D6, D7,..., And the heating resistor R1-1 and the heating resistor R1-2 are a set of heating resistors, and the heating resistor R2-1 and the heating resistor R2-. 2 is a set of heating resistor, heating resistor R3-1 and heating resistor R
3-2 is a set of a heating resistor, and a heating resistor R4.
-1 and the heating resistor R4-2 are a set of heating resistors,...
As described above, each of the adjacent heating resistors is used as a set of heating resistors, and the intervals of each set are arranged in a row with a width of 116 μm.
., E4,... And the common electrode portion E0, a current is supplied to the heater 11, heater 12, heater 13, heater 14,.
Are controlled by heating.

The shape and size of each heating resistor in the thermal head H2 is approximately 11 dots for printing.
In the case where the size is assumed to be 6 μm, the sum of the dimension in the line direction of a set of heating resistors is made smaller than the dot bitch,
Aiming at increasing the resistance in the width direction in a direction perpendicular to the line direction of each heating resistor, making it longer than the dot pitch,
It has a rectangular shape with 150 microns.

Next, such a thermal head H2 is
A schematic configuration and a printing method used in a thermal transfer printing apparatus having a configuration as shown in FIG. 2 will be described with reference to FIG. An ink ribbon 1 wound around a supply roller 5 and a take-up roller 6 is stretched over a platen roller 7, and a thermal head H 2 is provided at a position behind the ink ribbon 1 and near the platen roller 7. ,
Further, a movable platen roller 4 is provided at a position opposed to the platen roller 7.
The recording paper 2 is supplied from a mounting portion (not shown) between the ink ribbon 1 and the ink ribbon 1 stretched around the platen roller 7.

During printing, the ink ribbon 1 and the recording paper 2 are brought into close contact with the thermal head H2 by the platen roller 4 and the platen roller 7, and the ink ribbon 1 and the recording paper 2 are brought into close contact with the thermal head H2. The supply of current to the heating resistor is controlled through a heater, and a predetermined heating resistor is heated to melt the ink applied to the ink ribbon 1 and perform printing on the recording paper 2.

The heating method of the heating resistor at this time is, for example, as shown in the heating pattern of FIG. 1B, in the same line direction, for example, the heating resistor R1-1.
The pair of the heating resistor R1-2 and the heating resistor R1-2 is heated, the pair of the heating resistor R2-1 and the heating resistor R2-2 adjacent thereto is not heated, and the heating resistor R3-1 and the adjacent heating resistor R3-1 are further heated. The set with the resistor R3-2 is heated, so that every other set is heated, for example.

Further, between each line, the set of the heating resistors which are not heated in the previous line in the next line are heated, and this heating pattern is repeated alternately and sequentially. As a result, a staggered heating pattern as shown in FIG. As a result, FIG.
It is possible to divide one dot as shown in the heat generation pattern of (b) and to narrow the dot width, and the effect described later can be obtained.

Next, the thermal head H3 shown in FIG. 3A is composed of the respective heating resistors r1-1, r1-2, r2-
The dimensions and shapes of 1, r2-2, r3-1, r3-2,... And the method of heating each heating resistor are described in FIG. 1 (a) and FIG.
As in the case of the thermal head shown in FIG. 7, the head used is different in the material used for each heating resistor. That is,
CrAlBZr having a large negative temperature change (a large change in resistance corresponding to the heat generation temperature) as a material of the heat generating resistor
(Temperature gradient-1260 PPm / ° C: negative resistor) The heat generation pattern by this head is shown in FIG.
This is as shown in FIG.

As is apparent from this pattern, when a material having a large negative temperature change, such as CrAlBZr, is used for the heating resistor, a heat concentration effect occurs at the temperature of the central portion of the heating resistor, and one dot of heat is generated. Figure 1 (b)
Is narrower than the pattern shown in FIG. That is, in the low gradation area, the ink is melted in a small area, the low gradation area has a low density, and an effect described later in the lower gradation area can be obtained as compared with the above-described thermal head H2.

FIG. 4 is a diagram for explaining the effect.
A characteristic example in which the above-described conventional thermal head H1 is printed by the heating driving method in the above-described conventional apparatus, and a case in which the above-described thermal heads H2 and H3 of the present embodiment are printed by the above-described heating driving method. 5 is a diagram comparing the characteristic example with the optical density (O.D.) on the vertical axis.
D) is shown, and the heating time (msec) is shown on the horizontal axis.

As is apparent from this comparative characteristic example, when the heating method using the thermal head H1 according to the conventional example is used, it is difficult to identify the gradation density in the low gradation region, and the gradation in the low gradation region is difficult. You can see the poor tone expression. On the other hand, in the case of using the heating method using the thermal head H2, the density characteristics in the low gradation region are improved. Further, in the case of the heating method using the thermal head H3, a very remarkable improvement is seen in the density characteristics in the low gradation region.

Next, the thermal heads H2, H
In order to verify the effect from the viewpoint of the material, structure and productivity of No. 3, a comparative study was conducted using other sample examples.
The specifications of the thermal head, ink ribbon and recording paper used at that time, and the characteristics of the printer are shown below.

[Specifications of Thermal Head] The thermal head uses an end face type in which a heating resistor is formed on a glass rod, and its main specifications are as follows. 1. Heating element One row array of metal thin film resistors 2. Element density 8.57 dots / mm 3. Dot pitch 0.1167mm 4. Average resistance value 1600Ω +/− 15% 5. Printing length 52.3mm +/− 0.2mm

[Specifications of Ink Ribbon] 1. Thin film PET 3.5 μm 2. Ink coating amount 1.1 g / m ² 3. Concentration at application 1.4 or more Ink melting temperature 85 ° C

[Specifications of Recording Paper] Substrate PET and synthetic paper 2. Recording surface treatment Porous layer (corresponding to a pore diameter of 1 to 10 μm)

[Basic Characteristics of Printer] Resolution 8.57 dots / mm However, staggered printing is used. 2. 2. Recording speed 13 msec / line Power consumption 0.087 Watt / dot (maximum)

As a result, the following measurement results were obtained. In the following evaluation items, [length in the line direction × length in the width direction] indicates the rectangular size of the heat generating resistor, and [number] indicates the heat generation juxtaposed through a 10 μm slit. Indicates the number of resistors, [Material] indicates the material used for the heating resistor, and [Productivity] indicates that the resistance of 1600Ω is difficult to be realized, and the resistance is too wide, and the range of the resistance value is too wide. The product cannot be trimmed (trimming is generally performed by applying a high voltage to the heating resistor, and the product that cannot be obtained because of the disconnection caused by the trimming is rejected).
It is described as.

Length in line direction Number Material Low gradation characteristics Productivity × Length in width direction (μm) 1) 88 × 58 1 NiCr good high resistance not possible 2) 88 × 106 1 NiCr poor high resistance not possible 3) 48 × 58 2 NiCr excellent high resistance impossible 4) 32 × 120 2 NiCr excellent trimming impossible 5) 32 × 120 2 CrAlBZr excellent trimming impossible 6) 40 × 120 2 CrAlBZr excellent trimming possible 7) 40 × 150 2 NiCr good trimming impossible 8) 48 × 150 2 NiCr Good Trimmable 9) 106 × 150 1 NiCr Poor Trimmable

As a result, it is understood that the heating resistors shown in 6) and 8) are practical. That is, assuming that a plurality of rectangular heating resistors are juxtaposed via slits and that the print dot pitch is approximately 116 μm, the width of a set of heating resistors in the line direction is made smaller than this, and the width of the heating resistors is reduced. If the dimension in the direction is longer than the dot pitch, a thermal head that is satisfactory in terms of low gradation characteristics and productivity can be obtained.

[0030]

According to the present invention, the print density in the low gradation area can be reduced, and multi-gradation printing can be realized. In particular, according to the thermal head of the first aspect, a head with good productivity can be obtained in addition to the above effects.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a thermal head according to an embodiment of the present invention and a diagram showing a heat generation pattern thereof.

FIG. 2 is a schematic configuration diagram of a thermal transfer printing apparatus for realizing the present invention.

FIG. 3 is a schematic plan view of a thermal head according to another embodiment of the present invention and a diagram showing a heat generation pattern thereof.

FIG. 4 is a diagram comparing gradation characteristics.

FIG. 5 is a schematic plan view of a thermal head according to a conventional example and a diagram showing a heat generation pattern thereof.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ink ribbon 2 Recording paper 4 Platen roller 5 Supply roller 6 Take-up roller D1-D7 Slit E0-E4 Electrode part H2, H3 Thermal head r1-1-r4-2, R1-1-R4-2 Heating resistor

Claims (3)

[Claims] 1. A thermal head for a thermal transfer printing apparatus, comprising: a plurality of heating resistors adjacent to each other via a slit as a set, and a plurality of heating resistors arranged in a line at predetermined intervals. The total width of the set of heating resistors in the line direction is shorter than the predetermined interval of the set of heating resistors, and the width in the direction orthogonal to the line direction is set to be smaller than the predetermined interval of the set of heating resistors. A thermal head for a thermal transfer printing apparatus, characterized in that the heating resistor is formed of a negative resistor while being made longer. 2. A method of driving a thermal head for a thermal transfer printing apparatus according to claim 1, wherein, during thermal transfer printing, every other set of heating resistors in the same line is heated, and the next line is heated in the preceding line. A method of heating and driving a thermal head for a thermal transfer printing apparatus, wherein a set of heating resistors that are not heated is heated, and the heating method is alternately repeated in subsequent lines. 3. A plurality of heating resistors, which are adjacent to each other via a slit, are set as a set, and a plurality of sets of heating resistors are sequentially arranged side by side with a predetermined gap in a line shape. Heating a thermal head for a thermal transfer printing apparatus, wherein the total width in the direction is shorter than the interval between the pair of heat generating resistors, and the width in the direction orthogonal to the line direction is longer than the interval between the pair of heat generating resistors. In the driving method, at the time of thermal transfer printing, one set of heating resistors in the same line is heated every other set, and in the next line, the set of heating resistors not heated in the previous line is heated, and in the subsequent lines, A heating driving method for a thermal head for a thermal transfer printing apparatus, wherein a heating method is sequentially repeated.