JPH10181061A - Thermal head and heat transfer printing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high density without lowering a resolution and, at the same time, facilitate a density control by a method wherein one heating resistor constituting one pixel is bisected so as to form two electric current passages arranged in a main scanning direction and forming in respective electric current passages, narrow parts, the positions of which are different from each other in a sub-scanning direction. SOLUTION: Between electrodes 1 and 1, either one of which is a common electrode and the other of which is an individual electrode, heating resistors 2 and 2 are formed so as to bisect one pixel. The heating resistor 2 consists of a narrow part 2a and a broad part 2b. By arranging a plurality of sets of the heating resistors 2 and 2 having a shape just mentioned above in the main scanning direction, a thermal head is formed. When electric current is run in this thermal head, two electric current passages are formed by means of bisected heating resistors 2 and 2. In addition, since the resistance value at the narrow part 2a is larger, the peak in heat generation is formed at the narrow part 2a, the vicinity of the narrow part 2a becomes a heat generation part 3. That is, two heat generation parts 3 are prevent in one pixel at positions, which are different from each other in the main scanning direction and in the sub-scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a thermal head for performing thermal transfer printing and a thermal transfer printing apparatus using the thermal head.

[0002]

2. Description of the Related Art Conventionally, various improvements have been made in the form of a thermal head, a printing method, and the like in order to obtain a higher quality printed image. As one example, a very general thermal head having a rectangular heating resistor 2 as shown in FIG. 15 is used, and as shown in FIG. 16, the heating resistor 2 (R1, R2,. ,... Rm) are alternately heated in the main scanning direction, and the heating resistors 2 to be heated are alternately changed in the lines L1, L2,. There is a method of printing in a shape. In FIG. 15, reference numeral 1 denotes an electrode, and reference numeral 3 denotes a heating unit. This is intended to improve the multi-gradation characteristics by preventing thermal interference due to heat generation of the adjacent heating resistor 2 of the thermal head, and is particularly effective for thermal transfer printing using molten ink. . In this printing method, since the resolution is deteriorated, the printing method is mainly used in a thermal transfer printing apparatus provided with a thermal head having a resolution of 200 dpi or more.

As another improvement, there is a device in which the shape of a heating resistor of a thermal head is devised. FIG.
This shows a thermal head having a configuration in which a heat-generating resistor is divided into two parts, which is an example of such a device. In FIG. 17, heating resistors 2 and 2 are formed between electrodes 1 and 1, one of which is a common electrode and the other is an individual electrode, and one pixel is divided into two. When a current is applied to the thermal head, the central portion of the heating resistors 2 and 2 becomes the heating portion 3.
The heating resistor interval (pixel interval) of this thermal head is
As an example, at 150 dpi, the length is 169 μm, and the length in the sub-scanning direction is about 110 μm. FIG.
(C) shows print dots for printing using the thermal head shown in FIG. 17, where FIG. 18 (A) is at low density, FIG. 18 (B) is at high density, and FIG. 16 shows the same staggered printing as in FIG.

[0004]

As described above, FIG.
In the staggered printing described in (1), there is a problem that the resolution is deteriorated, and there is a problem that it can be mainly used only for a thermal head having a resolution of 200 dpi or more. Further, in printing using a thermal head having a configuration in which the heating resistor is divided into two parts as shown in FIG. 17, particularly at high density, the printing is affected by the heat of adjacent pixels.
There is a problem that the density tends to change sharply and the density control becomes difficult. In the zigzag printing using the thermal head shown in FIG. 17, although the density change is gradual, there is still a problem that the resolution is deteriorated and it is difficult to obtain a high density. At the same time, in staggered printing,
Heat generation control is complicated, and there is also a disadvantage that the apparatus becomes expensive.

Further, in a thermal transfer printing apparatus having a conventional thermal head, it is difficult to obtain high image quality with both the molten ink and the sublimation ink, and the image quality of either ink has to be sacrificed. There was a problem. For example, if the main component is a molten ink, it is preferable to easily control the density by setting the interval between the heating resistors in the main scanning direction to 169 μm and the length in the sub scanning direction to 100 μm or less. However, if this is used as it is for the sublimation ink, the density of the sublimation ink is not a change of the area but a change of the density, so that a gap is generated in the sub-scanning direction, and high-density printing cannot be performed. Conversely, if the ink is mainly composed of sublimation ink, it is preferable that the length in the sub-scanning direction is longer than the interval in the main scanning direction, for example, 170 μm so that no gap is formed in the sub-scanning direction. However, if this is used for the molten ink as it is, the area change is main in the molten ink, so the ink is connected in the sub-scanning direction,
Concentration control becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a thermal head which can easily control the density without lowering the resolution and can obtain a high density. I do. It is a further object of the present invention to provide a thermal transfer printing apparatus that can easily control the density of both the molten ink and the sublimation ink without lowering the resolution and can obtain a high density.

[0007]

According to the present invention, in order to solve the above-mentioned problems of the prior art, (1) a heating resistor is formed between a pair of electrodes, and a plurality of the heating resistors are arranged in the main scanning direction. In a thermal head configured by arranging one pixel, one heating resistor constituting one pixel is divided into two to form first and second current paths arranged in the main scanning direction. By forming narrow portions at different positions in the sub-scanning direction in each of the second current paths,
Provided is a thermal head, wherein two heat generating portions are formed at different positions in a main scanning direction and a sub scanning direction,
(2) In a thermal transfer printing apparatus including an ink ribbon and a thermal head for transferring the ink of the ink ribbon to recording paper, the thermal head may be located at different positions in one pixel in the main scanning direction and the sub scanning direction. When a thermal head having a heating resistor formed with two heating portions is used, and when the ink of the ink ribbon is molten ink, a print line is formed at a sub-scanning interval substantially equal to a pixel interval of the thermal head in a main scanning direction. Wherein the thermal transfer printing is provided with switching means for switching so as to form a print line at a sub-scanning interval of approximately 1/2 of the pixel interval when the ink of the ink ribbon is sublimation ink. An apparatus is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a thermal head and a thermal transfer printing apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a plan view showing an embodiment of the thermal head of the present invention, FIG. 2 is a view showing dots printed by the thermal head of the present invention, and FIG. 3 is a characteristic diagram for comparing the present invention with a conventional example. 4 is a plan view showing another embodiment of the thermal head of the present invention, FIG. 5 is a plan view for explaining the thermal head of the present invention, and FIG. 6 is a plan view showing still another embodiment of the thermal head of the present invention. FIG. 7 is a view showing a heat generation state by the thermal head of the present invention shown in FIG. 6, FIG. 8 is a view for explaining a printing operation by the thermal transfer printing apparatus of the present invention, FIG.
10 is a plan view showing an example of the shape of a heating resistor of a thermal head used in the thermal transfer printing apparatus of the present invention, FIG. 10 is a block diagram showing one embodiment of the thermal transfer printing apparatus of the present invention, and FIG. 12 is a block diagram illustrating a specific configuration of the head 20, FIG. 12 is a block diagram illustrating a specific configuration of the signal conversion unit 13 in FIG. 10, and FIG. 13 is a configuration diagram illustrating an embodiment of the thermal transfer printing apparatus of the present invention. FIG. 14 is a view for explaining the thermal transfer printing apparatus of the present invention.

First, the configuration of the thermal head of the present invention will be described. In FIGS. 1A and 1B, a heating resistor 2, 2 is formed between electrodes 1, 1, one of which is a common electrode and the other is an individual electrode, and one pixel is divided into two. It has a shape. The heating resistor 2 has a narrow portion 2a.
And a wide portion 2b. The heating resistor 2 on the left side in the figure has a narrow portion 2a formed on the electrode 1 side on the upper side in the figure,
The heating resistor 2 on the right side in the drawing has a narrow portion 2a formed on the lower electrode 1 side in the drawing. A set of the heating resistors 2 and 2 having such a shape constitutes a thermal head in a plurality in a line in the main scanning direction.

In the thermal head shown in FIG. 1A, the heating resistor 2 has a shape in which a rectangular narrow portion 2a is connected to an intermediate portion of a rectangular wide portion 2b. FIG.
In the thermal head shown in FIG.
Has a shape in which a rectangular narrow portion 2a is connected to an end of a rectangular wide portion 2b, and both outer sides of the heating resistor 2 are straight lines. Therefore, the thermal head shown in FIG. 1B is more desirable in terms of ease of manufacturing the heating resistor 2. In the thermal head shown in FIG. 1B, a concave portion 1 a is formed in the electrode 1. When a current is applied to such a thermal head, the current path becomes two by the heating resistors 2 and 2 divided into two.
Since the resistance value of the narrow portion 2a is large, a heat generation peak is formed in the narrow portion 2a, and the narrow portions 2a of the heat generating resistors 2 are formed.
The vicinity of “a” is the heat generating portion 3. That is, the thermal head of the present invention has two heat generating portions 3 at different positions in one pixel in the main scanning direction and the sub-scanning direction. The interval between the heat generating portions 3 in the sub-scanning direction is approximately の of the pixel interval in the main scanning direction.
It is desirable that In the case of a 150 dpi thermal head, for example, the interval in the main scanning direction (pixel interval)
Is 169 μm, and the interval between the heat generating portions 3 in the sub-scanning direction is about 85 μm.

The printing dots for printing using the thermal head of the present invention are as shown in FIG. 2A at a low density and as shown in FIG. 2B at a high density. The change in density when the heating energy is changed using this thermal head has characteristics as shown in FIG. 3A and 3B show a case where printing is performed using a thermal head having a configuration in which a heating resistor is simply divided into two as shown in FIG.
FIG. 18C shows a case where staggered printing as shown in FIG. 18C is performed by using a thermal head having a configuration in which a heating resistor as shown in FIG. 7 is divided into two.

As is apparent from FIG. 3, high density can be easily obtained by printing using a thermal head having a configuration in which a heating resistor is simply divided into two, but it is difficult to perform stable density control because the density changes steeply. . Further, in staggered printing using a thermal head having a configuration in which a heating resistor is divided into two parts, a high density cannot be obtained although the density change is gradual. In contrast, in printing using the thermal head of the present invention,
As is clear from FIG. 3, the resolution does not decrease,
It can be seen that a high concentration can be obtained and the concentration control is easy because the concentration change is stable.

Japanese Patent Application Laid-Open No. 63-82763 discloses a conventional example of a thermal head having a heat generating portion at a different position in the main scanning direction and the sub-scanning direction within one pixel.
And Japanese Patent Application Laid-Open No. 3-76657. Japanese Patent Application Laid-Open No. 63-82763 describes a thermal head in which a heating resistor is divided into two and each of which is provided with a total of four heating portions of two heating portions. JP-A-3-
JP-A-76657 describes a thermal head in which a heating element is bent at a different position in a main scanning direction and a sub-scanning direction within one pixel by bending the heating resistor without dividing the heating resistor. Have been.

However, as described in Japanese Patent Application Laid-Open No. 63-82763, if four heating portions are provided for one pixel, the heating portions are liable to be affected by each other, and there is no adverse effect on gradation recording. It became clear that it became. Further, as described in Japanese Patent Application Laid-Open No. 3-76657, if two heating portions are provided in one pixel without dividing the heating resistor, the heating resistor has many bent portions,
It becomes difficult to manufacture the thermal head. On the other hand, in the thermal head according to the present invention in which the heating resistor is divided into two parts and two heating parts 3 are provided at different positions in one pixel in the main scanning direction and the sub-scanning direction, the above-described features are provided. In addition to the above, there is a feature that the manufacture is easy and the amount of current flowing therethrough can be easily controlled.

Another configuration of the thermal head according to the present invention will be described. In FIG. 4, one of the electrodes is a common electrode, and the other is an individual electrode.
Are formed, and one pixel is divided into two. The heating resistor 2 includes a narrow portion 2a and a wide portion 2b. The heating resistor 2 on the left side in the drawing has a narrow portion 2a formed on the lower electrode 1 side in the drawing, and the heating resistor 2 on the right side in the drawing has a narrow portion 2a formed on the upper electrode 1 side in the drawing. ing. The electrode 1 has a concave portion 1a.

The shape of the heating resistors 2 and 2 arranged on the left and right is such that when one heating resistor 2 is turned upside down and turned upside down, it becomes the other heating resistor 2. . The heat generating resistor 2 has a shape in which a rectangular narrow portion 2a is connected to an end portion of a rectangular wide portion 2b, and one side of the heat generating resistor 2, that is, a left side in FIG. ing. A set of the heating resistors 2 and 2 having such a shape constitutes a thermal head in a plurality in a line in the main scanning direction. When current is passed through such a thermal head,
Due to the two divided heating resistors 2, two current paths are formed, and the resistance value of the narrow portion 2 a is large, so that a peak of heat is formed in the narrow portion 2 a, and the width of the heating resistors 2, 2 The vicinity of the narrow part 2a becomes the heat generating part 3. That is, the thermal head of the present invention shown in FIG. 4 has two heat generating portions 3 at different positions in the main scanning direction and the sub-scanning direction within one pixel, as in FIG. The interval between the heat generating portions 3 in the sub-scanning direction is set to approximately １ ／ of the pixel interval in the main scanning direction.

Moreover, the thermal head of the present invention shown in FIG. 4 has the following advantages over the thermal head shown in FIG. 1B. That is, as an example, assuming that the interval in the main scanning direction (pixel interval) is 176 μm and the interval in the sub-scanning direction of the heating section is 88 μm, the narrow portion 2a of the heating resistor 2 is arranged as shown in FIG. Therefore, the heating part 3 of the heating resistor 2 on the left side in the figure is located at the left end in one pixel, and the heating part 3 of the heating resistor 2 on the right side in the figure is located at the approximate center in one pixel. . The length of the narrow portion 2a in the sub-scanning direction is, for example, 40 μm. Thereby, in the thermal head shown in FIG.
The interval between the narrow portions 2a (that is, the heat generating portions 3) is 88 μm, which is almost equal in the main scanning direction. Therefore, it is possible to obtain a higher density without lowering the resolution than the thermal head shown in FIG. 1B, and to improve the feature that the density change is stable and the density control is easy. Can be. The thermal head shown in FIG. 4 also has the advantage that it is easy to manufacture because one side of the heating resistor 2 in the main scanning direction is straight, like the thermal head shown in FIG. 1B.

When the thermal head shown in FIG. 4 is manufactured, as shown in FIG. 5A, the length of the narrow portion 2a in the sub-scanning direction is set to 40 μm for both the pair of heat generating resistors 2.
It is desirable to make them uniform like m. However,
Actually, as shown in FIG. 5B, the length of the narrow portion 2a of one heating resistor 2 is 20 μm, and the length of the narrow portion 2a of the other heating resistor 2 is 60 μm. Tends to be uneven. In this case, the production yield of the thermal head is low, which causes an increase in cost.

In order to solve this problem, the thermal head may be configured as shown in FIG. Here, still another configuration of the thermal head of the present invention will be described. In FIG. 6, heating resistors 2 and 2 are formed between electrodes 1 and 1, one of which is a common electrode and the other is an individual electrode, and one pixel is divided into two. The heating resistor 2 has a shape in which the wide portion 2b, the narrow portion 2a, and the wide portion 2b are connected in the sub-scanning direction. In the heating resistor 2 on the left side in the drawing, a wide portion 2b having a short length in the sub-scanning direction is formed on the lower electrode 1 side in the drawing, and a narrow portion 2a is formed continuously with the wide portion 2b. I have. In the heating resistor 2 on the right side in the drawing, a wide portion 2b having a short length in the sub-scanning direction is formed on the upper electrode 1 side in the drawing, and a narrow portion 2a is formed continuously with the wide portion 2b. . The electrode 1 has a concave portion 1a
Are formed.

The shape of the heating resistors 2 and 2 arranged on the left and right is the same as in the embodiment shown in FIG. 4, and when one heating resistor 2 is turned upside down and turned upside down, the other heating resistor 2 is turned over.
The relationship is as follows. Also, as in the embodiment shown in FIG. 4, one side of the heating resistor 2, in FIG. 6, the left side is a straight line. Heating resistors 2 and 2 having such a shape
Are arranged in the main scanning direction to constitute a thermal head.

In the thermal head shown in FIG.
As shown in (A) to (C), even if the connection between the heating resistor 2 and the electrode 1 is slightly shifted, the width of the narrow portion 2a is 40 μm.
Is maintained as it is. Therefore, in the thermal head shown in FIG. 6, it is possible to improve the production yield of the thermal head without causing the problem described with reference to FIG. The effect of the thermal head shown in FIG. 6 is the same as that of the thermal head shown in FIG. The heating section 3 of the thermal head shown in FIG. 6 has a state as shown in FIG. 7A when the density is low, and as shown in FIG. 7B when the density is high.

The printing dots for printing using the thermal head of the present invention shown in FIGS. 4 and 6 are the same as those in FIG. 2, and the density changes when the heating energy is changed are also different from those in FIG. It has substantially the same characteristics as shown in FIG.
Strictly speaking, in the thermal head of the present invention shown in FIGS. 4 and 6 in which the interval between the narrow portions 2a in the main scanning direction is set to approximately の of the pixel interval in the main scanning direction, as shown in FIG. It is possible to obtain more ideal characteristics than the thermal head shown in FIG.

Next, the configuration and operation of the thermal transfer printing apparatus of the present invention will be described. In the thermal transfer printing apparatus of the present invention, as shown in FIGS. 9A and 9B, a heating resistor 2 having two heating portions 3 at different positions in one pixel in the main scanning direction and the sub-scanning direction is used. Is used.
The thermal head shown in FIG. 9A is the same as the thermal head shown in FIG. Of course, the thermal head shown in FIGS. 4 and 6 may be used. In the thermal transfer printing apparatus of the present invention, printing is performed as follows using such a thermal head.

That is, when the molten ink is used, FIG.
As shown in (A), the interval between the printing lines in the sub-scanning direction is
As is generally done in the related art, printing is performed at substantially the same interval as the interval in the main scanning direction. Note that FIGS. 8A and 8B
L1 and L2 are print lines, and the print dot A is 2
Two divided dots are formed by one pixel, and the dot B is formed by two adjacent pixels.
On the other hand, when sublimation ink is used, as shown in FIG. 8B, printing is performed with the interval between sub-scanning directions of a print line being substantially half the interval between main scanning directions. This way,
The printing dots A 'and B' printed on the printing line L1 / 2 between the printing lines L1 and L2 are the printing lines L1 and L
2 is transferred so as to fill the space between the print dots.

As described above, a thermal head having two heat generating portions 3 at different positions in the main scanning direction and the sub-scanning direction within one pixel is used. In the case of the molten ink, the sub-scanning direction interval is substantially the same as the main scanning direction interval. If printing is performed at intervals, there is no possibility that the ink is unnecessarily connected in the main scanning direction or the sub-scanning direction and the density control becomes difficult, and the resolution does not decrease. In addition, in the sublimation ink, if the interval in the sub-scanning direction is printed at substantially half the interval in the main scanning direction, there is no gap in the sub-scanning direction, and high density can be obtained.
Also, the resolution does not decrease. Therefore, in the thermal transfer printing apparatus of the present invention, in both the molten ink and the sublimation ink, the resolution can be easily controlled without deteriorating the resolution, and a high density can be obtained, which impairs the image quality of any one. Therefore, high-quality printing can be performed using both the molten ink and the sublimation ink.

A configuration for performing the above operation will be described with reference to FIGS. In FIG.
An image signal output from an image input device 10 such as a camera or a scanner is input to an I / F unit 11 in the thermal transfer printing device. The I / F unit 11 separates an image signal used for printing and a control signal used for controlling the printing apparatus, and inputs them to the data storage unit 12 and the control unit 15, respectively. The data storage unit 12 temporarily stores the image signal, and then inputs the image signal to the signal conversion unit 13 in accordance with the operation of the printing device. The signal converter 13 converts the R, G, and B color signals into Y, M, and C signals for printing, and performs an operation corresponding to each of the molten ink and the sublimation ink, as described later. The output of the signal converter 13 is input to the parallel / serial converter 14, which converts the heating resistor control signal Ds into the thermal head 2.
Supply 0.

On the other hand, when a start signal is input to the control unit 15 at the same time as the start of driving of the printing apparatus, the control unit 15 sends a control signal for sending the image signal stored in the data storage unit 12 to the signal conversion unit 13. A control signal is input to a data storage unit 12 and a reference signal generation unit 16 that generates a reference signal required for printing. Further, a control signal is also input to the mechanism system control unit 17. The reference signal generation unit 16 receives the control signal input from the control device 15 and the ink selection signal input from the ink selection unit 18 via the mechanism control unit 17,
A reference signal such as a color and density signal corresponding to the recording position is input to the signal conversion unit 13 and the parallel / serial conversion unit 14. Further, a reference signal for controlling the heating time for each concentration is input to the heating time control unit 19. The heating time control unit 19 generates a gate signal Sg that defines a heating time for each concentration, and inputs the gate signal Sg to the thermal head 20.

As shown in FIG. 11, the thermal head 20 includes a shift register 201, a latch circuit 202, a gate circuit 203, a drive circuit 204, and a heating resistor 205. The reference clock signal Ck and the heating resistor control signal Ds are input to the shift register 201,
The heating resistor control signal Ds for one line is stored in the shift register 201 in accordance with the reference clock signal Ck. The heating resistor control signal Ds is simultaneously transferred to and stored in the latch circuit 202 for one line by the latch signal Sr.
When the transfer to the latch circuit 202 is completed, the heating resistor control signal Ds for the next one line is input to the shift register 201. The reference clock signal Ck and the latch signal Sr are generated by the reference signal generator 16.

The heating resistor control signal Ds transferred to and stored in the latch circuit 202 is transferred to the gate circuit 203 as it is. The gate circuit 203 opens the gate for the heating time of each heating resistor 205 corresponding to each density according to the gate signal Sg, and supplies power to the heating resistor 205 via the driving circuit 204. The selection of the heating resistor 205 to be heated is performed for each density represented by the gate signal Sg based on the heating resistor control signal Ds, and the selected heating resistor 205 is melted for the time during which power is supplied. The ink or the sublimation ink is heated, and the ink corresponding to the heating amount is transferred to recording paper (not shown). The heating resistor 205 has a shape as shown in FIG.

The operation of the signal conversion unit 13 for each of the molten ink and the sublimation ink will be described with reference to FIG. In FIG. 12, an image signal-print signal converter 131 in the signal converter 13 converts the R, G, B color signals into Y, M, C signals for printing. This image signal-
The output of the print signal converter 131 is a print signal for one line. As described above, when the molten ink is used, the printing is performed with the sub-scanning direction interval substantially equal to the main scanning direction interval.
The output of the print signal converter 131 may be used as it is.
On the other hand, when the sublimation ink is used, the printing is performed with the interval in the sub-scanning direction substantially equal to the half of the interval in the main scanning direction. -The output of the print signal converter 131 may be used as it is. Then, when forming dots corresponding to an intermediate line at a normal sub-scanning interval, signals obtained by the one-line print signal storage units 132 and 133 and the arithmetic unit 134 may be used.

When printing an intermediate line at a normal sub-scanning interval, the same signal as an adjacent signal is used as it is,
Alternatively, the preceding and succeeding signals may be divided by two by dividing by two lines. In any case, the sublimation ink has no practical problem because the pixel itself is blurred and has a filter effect. The one-line print signal storage unit 132 stores the image signal-print signal conversion unit 1
By storing and delaying the output of 31, a half-line print signal as an intermediate line signal is obtained. When the same signal is used as it is, the one-line print signal storage unit 13
2 may be used. 1-line print signal storage unit 13
3 stores and delays the output of the one-line print signal storage unit 132. The operation unit 134 is a one-line print signal storage unit 13
The output of 2,133 is calculated (for example, added to １ ／) to obtain a ラ イ ン -line operation print signal as an intermediate line signal. When a signal obtained by dividing the previous and next signals by two lines and dividing by two is used, the output of the arithmetic unit 134 may be used.

The output of the image signal-to-print signal conversion section 131 and the output of the one-line print signal storage section 132 or the operation section 134 are input to a switch 135, and the reference signal generation section 1
6 is switched by the switching signal from. As described above, it is possible to perform signal processing according to each of the molten ink and the sublimation ink.

Next, control of the mechanical system will be described. As shown in FIG. 13, the thermal transfer printing apparatus of the present invention has a configuration including a thermal head 20, an ink ribbon 21, a recording paper 22, and a platen roller 23. Further, the thermal head 20 includes a spring 24 and a plunger 25 for pressing and separating the thermal head 20 from and against the platen roller 23. Switching between printing with the molten ink and printing with the sublimation ink can be performed using the ink ribbon cassette 26 as an example.

As shown in FIGS. 13 and 14, the ink ribbon cassette 26 for the molten ink has cutouts 26 at the corners.
a, and the notch 26a is not provided in the ink ribbon cassette 26 of the sublimation ink. The presence or absence of the notch 26a may be detected by the microswitch 27, and this detection signal may be input to the mechanism control unit 17. This is merely an example, and a method of providing an identification mark on the ink ribbon cassette 26 is also available.

As described above, when the ink on the ink ribbon 21 is the molten ink, the thermal head 20
When the ink on the ink ribbon 21 is sublimation ink, the print line is formed at a sub-scanning interval that is approximately 1/2 of the pixel interval. Thus, a thermal transfer printing apparatus provided with a switching means for switching can be configured. According to the thermal head and the thermal transfer printing apparatus of the present invention, since the resolution is not reduced, even if the resolution of one pixel is set to 200 dpi or less, there is no problem in image quality, and thus a high-quality print image can be obtained at low cost. The present invention is also effective for a 150 dpi printer used in a video printer or the like.

[0036]

As described above in detail, in the thermal head of the present invention, one heating resistor constituting one pixel is divided into two and the first and second two heating resistors are arranged in the main scanning direction. By forming two current paths and forming narrow portions at different positions in the sub-scanning direction on each of the first and second current paths, different pixels in the main scanning direction and the sub-scanning direction are formed within one pixel. Since two heat generating portions are formed at the positions, a high density can be obtained without lowering the resolution, and the density change is stable, so that the density control is easy. In addition, it has features that it is easy to manufacture and the amount of current flowing through the heating resistor is easily controlled.

Further, a thermal head having a heating resistor having two heating portions formed at different positions in the main scanning direction and the sub-scanning direction in one pixel is used. A print line is formed at a sub-scanning interval substantially equal to the pixel interval in the main scanning direction of the head, and when the ink of the ink ribbon is sublimation ink, a print line is formed at a sub-scanning interval of approximately 1/2 of the pixel interval. As a result, the resolution can be easily controlled without deteriorating the resolution of both the molten ink and the sublimation ink, and a high density can be obtained. It has the feature that high quality printing can be performed with both the molten ink and the sublimation ink without loss.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a thermal head according to the present invention.

FIG. 2 is a diagram showing dots printed by the thermal head of the present invention.

FIG. 3 is a characteristic diagram for comparing the present invention with a conventional example.

FIG. 4 is a plan view showing another embodiment of the thermal head of the present invention.

FIG. 5 is a plan view for explaining the thermal head of the present invention.

FIG. 6 is a plan view showing still another embodiment of the thermal head of the present invention.

7 is a diagram showing a heat generation state by the thermal head of the present invention shown in FIG.

FIG. 8 is a diagram for explaining a printing operation by the thermal transfer printing apparatus of the present invention.

FIG. 9 is a plan view showing the shape of a heating resistor of a thermal head used in the thermal transfer printing apparatus of the present invention.

FIG. 10 is a block diagram showing one embodiment of the thermal transfer printing apparatus of the present invention.

11 is a block diagram showing a specific configuration of the thermal head 20 in FIG.

12 is a block diagram showing a specific configuration of a signal conversion unit 13 in FIG.

FIG. 13 is a configuration diagram showing one embodiment of the thermal transfer printing apparatus of the present invention.

FIG. 14 is a view for explaining the thermal transfer printing apparatus of the present invention.

FIG. 15 is a plan view showing a conventional thermal head.

FIG. 16 is a diagram showing conventional staggered printing.

FIG. 17 is a plan view showing another conventional thermal head.

FIG. 18 is a diagram showing print dots by the thermal head shown in FIG. 17;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode 2 Heating resistor 2a Narrow part 2b Wide part 3 Heating part 20 Thermal head 21 Ink ribbon 22 Recording paper 23 Platen roller

Claims (4)

[Claims] 1. A thermal head comprising a plurality of heating resistors formed between a pair of electrodes and a plurality of heating resistors arranged side by side in a main scanning direction, wherein one heating resistor constituting one pixel is reduced to two. First and second two current paths which are divided and arranged in the main scanning direction are formed, and narrow portions are formed in the first and second current paths at different positions in the sub-scanning direction. A thermal head, wherein two heat generating portions are formed in one pixel at different positions in the main scanning direction and the sub scanning direction. 2. An apparatus according to claim 1, wherein an interval between said narrow portions formed in said first and second current paths in the main scanning direction is substantially の of a pixel interval in said main scanning direction. 1. The thermal head according to 1. 3. The device according to claim 1, wherein the narrow portion is connected to both of the pair of electrodes via a wide portion.
Or the thermal head according to any of 2. 4. A thermal transfer printing apparatus comprising an ink ribbon and a thermal head for transferring ink of the ink ribbon to recording paper, wherein the thermal head has different main scanning directions and sub scanning directions within one pixel. When a thermal head having a heating resistor having two heating portions formed at positions is used, when the ink of the ink ribbon is molten ink, printing is performed at a sub-scanning interval substantially equal to a pixel interval of the thermal head in a main scanning direction. A line is formed, and when the ink of the ink ribbon is sublimation ink, switching means for switching so as to form a print line at a sub-scanning interval of approximately 1/2 of the pixel interval is provided. Thermal transfer printing equipment.