JPS62208958A - Thermal printer - Google Patents

Abstract

PURPOSE:To enable a pressing force of a thermal head to be lowered with obtaining a constant good contact at a heating portion and to prevent a damage on an ink ribbon, by a method wherein; a thermal head provided with a heating portion at an end of a substrate and a projecting strip portion at the other end thereof is allowed to abut on a platen at the heating portion and the projecting strip portion in printing and to travel so as to be led by the other end having the convex projecting portion thereon. CONSTITUTION:A heating portion 3 is formed at an end of a thermal head 1 and a convex strip portion 7 is formed at the other end thereof. The projecting strip portion 7 is made of a glaze layer or a dummy heating element and set slightly higher than the heating portion. Since the head presses a platen 6 only at the area of the heating portion 3 and the projecting strip portion 7, the contact pressure of nearly 200-500g is adequate for a printing and also can be set higher at the heating portion 3. The thermal head 1 is so installed as to have a slight slant by forming the projecting strip portion 7 higher than the heating portion 3, which enables the pressing force to be increased still more at the heating portion 3. The projecting strip portion 7 is so constructed s to have an approximately semicircular cross section to prevent a damage on an ink ribbon 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal printer, and particularly to a thermal printer that can improve print quality.

[Prior Art and its Problems] FIG. 3 shows a conventional thermal head 1, in which a heat generating part 3 serving as a printing part is provided at one end of a substrate 2. When printing is performed using this thermal head 1, printing is performed by moving the thermal head 1 while keeping it in close contact with the recording paper 5 via the ink ribbon 4, as shown in FIG. however,
The surface of recording paper has severe irregularities, and this tendency is particularly noticeable in recording paper called rough paper, which has a Bekk smoothness of 20 to 30 seconds or less. When printing on such recording paper, there is an inconvenience that the ink from the ink ribbon is not transferred sufficiently, resulting in blurred characters or uneven density. It was necessary to maintain sufficient pressure. In general, for a platen made of neoprene rubber with a thickness of 2# and a rubber hardness of 30'', the minimum contact pressure of the heat generating part is 100 to 150g, which requires a pressure of 500 to 150g for the entire head.
With what force should you press 500g? If you press with such pressure, the platen 6 and ink ribbon 4 will be deformed as shown in Figure 4, and when the thermal head 1 is moved, the thermal head The ink ribbon 4 may be damaged at the other end 1a, causing the ink ribbon 4 to break and become unable to print.Also, the resistance during movement increases, so the motor for movement must also be powerful and large. There were some problems, such as having to use other materials.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a heat generating part at one end of the substrate and a protruding strip corresponding to the heat generating part at the other end. During printing, the formed thermal head is characterized in that the heat generating part and the protruding stripes are brought into contact with the platen, and the thermal head is moved with the other end where the protruding stripes are formed first.

[Operation] The above means operates as follows. When the thermal head 1 is pressed against the platen 6 during printing, the thermal head 1 is pressed against the heat generating portion 3 and the protruding portion 7 at two places.

[Examples] Examples of the present invention will be described below. FIG. 1 shows the printing state of the thermal printer of the present invention, and FIGS. 2 and 3 do not show the schematic structure of the thermal head used in the present invention. As shown in the figure, a heat generating section 3 is formed at one end of the 1-Normal Head 1, and a protruding strip 7 is formed at the other end so as to correspond to the heat generating section 3. still,
The protruding portion 7 is formed by a glaze layer or a dummy heating element, and its height is set to be slightly higher than the heating portion. When such a thermal head 1 is used in a thermal printer, the area of the head pressing against the platen 6 as shown in FIG.
Therefore, a contact pressure of about 200 to 5009 is sufficient, and it is possible to increase the contact pressure by using the heat generating part 3. Further, by forming the protruding portion 7 higher than the heat generating portion 3, the thermal head 2 can be mounted at a slight inclination, and the pressure contact force on the heat generating portion 3 can be further increased. Further, since the protruding portion 7 is usually formed so that its cross section is approximately semicircular, damage to the ink ribbon 4 can also be prevented.

[Effects of the Invention] As described above, according to the present invention, the pressure contact force of the thermal head can be reduced and good contact between the heat generating parts can always be obtained.
This not only provides high printing quality but also provides remarkable effects such as being able to prevent damage to the ink ribbon.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the printing state of the thermal printer of the present invention, FIG. 2 is a schematic structural diagram of a thermal head used in the thermal printer of the present invention, and FIG. 2(a) is a plan view thereof, and FIG. FIG. 2(b) is a sectional view thereof, FIG. 3 is a schematic diagram of a conventional thermal head, and FIG. 4 is an explanatory diagram showing a printing state of a conventional thermal printer. 1... Thermal head 2... Substrate 3... Heat generating part 7... Convex part dormitory 1 Figure 2nd day

Claims (1)

[Claims] When printing a thermal head, which has a heat generating section on one end and a protruding strip on the other end, the heat generating section and the protruding strip are brought into contact with the platen, and the other end on which the protruding strip is formed is brought into contact with the platen. A thermal printer characterized in that the thermal head is moved while moving the thermal head forward.