JPH0320121Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head used in a thermal printer.

Conventionally, in thermal printers that use plain paper, a thermal head equipped with a plurality of heating elements is selectively driven with electricity, and predetermined heating elements are pressed onto the paper through a wax-type transfer ribbon, thereby changing the paper surface. Predetermined printing was performed by melting and adsorbing dye from a transfer ribbon onto the paper. Although this transfer method using a thermal printer has advantages such as reducing printing noise because it is a non-impact method and lowering costs because it has a simple structure, it is easily affected by the quality of the paper to be printed on, and it is difficult to print on uneven paper. In this case, it is difficult to transfer to the concave part, and a clear impression cannot be made. In addition, because the thermal head is pressed onto the paper surface via a transfer ribbon, the heat emitted from the heating element of the thermal head diffuses through the paper beyond the printing range of characters, etc. to be printed, resulting in poor thermal efficiency. Therefore, extra heat is required to perform a predetermined printing, which has the drawback of slowing the printing speed.

In order to overcome the drawbacks of such a transfer method using a thermal printer, an inkjet printing method has recently been proposed in which printing is performed by scattering ink onto a paper surface without using a transfer ribbon. The inkjet method is broadly divided into the bubble inkjet method and the spark inkjet method.The bubble inkjet method embeds a heating element in the nozzle, and prints by ejecting ink onto the paper surface using the vapor pressure of the liquid ink generated by the heat generated. The spark ink jet method generates a spark between the tip of a rod-shaped carbon ink and a spark electrode, and the resulting explosion causes part of the tip of the carbon ink to move toward the paper surface. This is a method of printing by ejecting. Since both print by scattering ink onto the paper surface, the drawbacks of conventional thermal printers mentioned above can be overcome, but the former requires a heating resistor element to be embedded in the nozzle, resulting in a complicated print head structure and high cost. Then came the flaws. Furthermore, the latter required a spark electrode to be provided separately from the print head, making the printing mechanism more complicated. Furthermore, the latter requires a power source capable of generating a high voltage and also requires noise countermeasures, which has the disadvantage of increasing the size of the device.

Furthermore, when a recording medium with low absorbency is used, the ink jet method sometimes does not fix the ink well on the recording medium.

The purpose of this invention is to improve the above-mentioned conventional drawbacks, to be applicable to ordinary thermal printers, and to be able to print by directly scattering ink onto the paper surface without using a transfer ribbon, thereby improving print quality. The object of the present invention is to provide a small-sized thermal head at low cost.

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 1 to 5.

FIG. 1 is a perspective view of the main parts of a thermal printer to which a thermal head according to the present embodiment is applied, and a carriage 1 has a pulley 2 attached to the thermal printer main body and a pulley fixed to a drive motor 3 at the bottom of the carriage 1. 4, and a guide rail 7 is slidably inserted into a guide hole 6 provided at the bottom of the carriage 1. Further, a platen 9 on which printing paper 8 is mounted is disposed on the entire surface of the carriage 1.

The thermal head 10 is provided on the front surface of the carriage 1 facing the platen 9. As shown in FIGS. A heating element 13 is provided on the periphery of the tip so that the tip of the through hole 12 is tapered. Each heating element 1
3 are respectively connected to printing signal sources via lead wires 14. Further, a solid evaporative recording material 17 in which nitrocellulose 15 and sublimable dye 16 are uniformly mixed is inserted into each of the through holes 12, and each evaporative recording material 17 is inserted into the rear end of each through hole 12. It is always urged by a disposed spring body 18 to be pushed out to the tip of the through hole 12. At this time, since the tip of the through hole 12 is tapered, excess evaporation recording material 17 is not pushed out to the tip of the through hole 12.

An anthraquinone disperse dye is used as the sublimable dye 16 in the evaporation recording material 17, and a ketone solvent such as methyl isobutyl ketone (MIBK) or methyl ethyl ketone (MEK) is used as the mixed solvent of the sublimable dye 16 and nitrocellulose 15. ) and cellosolve, such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, etc., are used, and if desired, alcohols such as ethyl alcohol and isopropyl alcohol are added to increase the dissolving power of the mixed solvent. You can. A mixture of the sublimable dye 16, nitrocellulose 15, and ketone solvent is injected into a predetermined mold, and the solvent is evaporated to obtain an evaporation recording material 17 that is inserted into the through hole 12 of the thermal head 10. .

In order to print with a thermal printer to which the thermal head 10 according to the present embodiment is applied, first, the printing paper 8 is mounted on the platen 9, and then a plurality of heat generating units provided at the tips of the through holes 12 of the thermal head 10 are placed in accordance with the printing information. Predetermined heating elements 13 among the elements 13 are selectively energized and driven via lead wires 14 . As a result, a predetermined number of the heating elements 13 of the plurality of heating elements 13 of the thermal head 10 are selectively made to generate heat, and the heat is transmitted to the evaporation recording material 17 at the tip of the through hole 12. Along with this, the nitrocellulose 15 in the evaporation recording material 17 is heated by the heat transferred from the heating element 13, and when it reaches a certain temperature, it burns at a high speed. The sublimable dye 1 contained in the evaporation recording material 17 due to this combustion heat
6 is instantaneously evaporated and deposited by scattering onto the printing paper 8 mounted on the platen 9 facing the front of the thermal head 10, as shown in FIG. 5, and the desired printing is completed. Along with this printing operation, the carriage 1 equipped with the thermal head 10 is moved by the pulleys 2 and 4.
As the drive motor 3 rotates forward and backward, it is guided by the guide rail 7 inserted into the guide hole 6 and reciprocated through the wire 5 stretched between them, and these operations are performed continuously to achieve a predetermined position. The printing is repeated continuously.

As described in detail above, the thermal head 10 according to the present embodiment has a plurality of through holes 12 formed inside the thermal head main body 11, each of which has an evaporative recording material 1 made of nitrocellulose 15 and a sublimable dye 16.
7 and attach this evaporation recording material 17 to the spring body 18.
It is possible to perform printing by scattering and vapor-depositing the sublimable dye 16 onto the paper 8 by utilizing the high-speed combustibility of the nitrocellulose 15 based on the heat emitted from the heating element 13 while extruding it to the tip of the through hole 12 through the nitrocellulose. This is what I did. Therefore, by printing using this evaporable dye, the transfer ribbon required in conventional thermal printers becomes unnecessary.
Further, since printing is performed by scattering and vapor-depositing the sublimable dye 16 onto the paper 8, efficient and clear printing can be performed even on the paper 8 having uneven surfaces, regardless of the paper quality of the paper 8. Furthermore, the thermal head 10 according to this embodiment can be applied to a normal thermal printer, and by using an evaporative recording medium,
Since an expensive transfer ribbon is not required, a thermal printer can be provided at low cost.

Next, another embodiment of the present invention will be described based on FIGS. 6 and 7. Note that the same parts as those in the above embodiment will be described with the same reference numerals for convenience.

FIG. 6 shows a side sectional view of the thermal head 10. The feature of this thermal head 10 is that a liquid material made of a mixture of nitrocellulose 15, a sublimable dye 16, and a ketone solvent is used as the evaporative recording material 17. As shown in FIG. 7, the evaporation recording material 17 is stored in a cylindrical storage tank 22 having a plurality of injection ports 19 on the side and a replenishment port 21 opened and closed by a cap 20 on the top. The injection port 19 is connected to the thermal head main body 1.
It is inserted into each through hole 12 bored in 1.

To perform printing using this thermal head 10, as in the previous embodiment, the heating element 13 is selectively energized and driven via the lead wire 14.
The nitrocellulose 15 in the evaporative recording material 17 is combusted at high speed by the heat emitted from the recording material 3, and the sublimable dye 16 is scattered and vapor-deposited onto the surface of the paper 8 to perform predetermined printing. At this time, the evaporation recording material 17
is the inlet 19 of the storage tank 22 according to the printing operation.
The liquid is injected into the through hole 12 through the through hole 12, and thereafter, it is sequentially replenished to the tip of the through hole 12 due to the capillary phenomenon that occurs between the through hole 12 and the through hole 12.

Incidentally, when the amount of evaporated recording material 17 decreases, the cap 20 on the upper part of the storage tank 22 can be removed and the material can be replenished from the replenishment port 21.

In this way, the thermal head 1 according to this embodiment
Similarly to the thermal head 10 according to the previous embodiment, printing can be performed without using a transfer ribbon by using an evaporative recording material. Furthermore, the thermal head 10 according to this embodiment
is applicable to ordinary thermal printers.

As described in detail above, the thermal head of the present invention can provide an inexpensive thermal head that does not require a transfer ribbon by using an evaporative recording material. Furthermore, this thermal head can be applied to an ordinary thermal printer, and can also be used as an ordinary thermal printer by bringing the thermal head into contact with thermal paper. Therefore, the printer using the thermal head of the present invention has great effects, such as allowing the user to selectively select the printing method depending on the paper quality, usage, etc.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a perspective view of the main parts of a thermal printer, FIG. 2 is a side sectional view of the thermal head, and FIG. 3 is a thermal head. FIG. 4 is a partially omitted enlarged side sectional view of the thermal head before printing, and FIG. 5 is a partially omitted enlarged side sectional view of the thermal head after printing. 6 and 7 show other embodiments of the present invention, FIG. 6 being a side sectional view of the thermal head and FIG. 7 being a perspective view of the storage tank. In the figure, 10 is a thermal head, 12 is a through hole,
13 is a heating element, 15 is nitrocellulose, 16
17 is a sublimable dye, 17 is an evaporative recording material, and 18 is a spring body.

Claims (1)

[Claims for Utility Model Registration] A thermal head for printing a dot pattern on a recording medium, which is provided so that an evaporative recording material made of a mixture of an explosive substance and a sublimable dye can be inserted thereinto, and which is connected to the recording medium. a plurality of through holes having openings at one end on opposing surfaces; and heat generation for ejecting the sublimable dye by heating the evaporative recording material inserted into the through holes and exploding the explosive substance. the heating element is provided on a surface facing the recording medium, and is capable of heating the thermal paper as the recording medium when the evaporative recording material is not inserted into the through hole. A thermal head characterized by: