JPH0330958A - Thermal head - Google Patents

Abstract

PURPOSE:To enable excellent printing without any white stripe to be obtained by a method wherein a length of a heating resistor line which is larger than a line feed pitch of a paper feed mechanism is provided. CONSTITUTION:A plurality of heating resistors 2A to 2J are linearly adjacently to each other arranged by providing specific intervals on a substrate 1. Further, in order to connect those heating resistors 2A to 2J to an outside, electrodes 3A to 3J are formed from edges of respective thermal resistors 2A to 2J to a peripheral side part of a bottom edge on the same substrate 1. Further, the other ends of respective thermal resistors are connected to a common electrode 4. A length of a line of those heating resistors is established in the width L+d which is larger by one dot content width than a line feedpitch L of a paper feed mechanism. In the case where dot like recording is performed by using a thermal head, though the more outer side it goes, the more easily the heat is discharged and a top and bottom parts of recording become thin in density, a problem of appearing a white stripe ds not generated since there is a one dot of overlapped part with one line feed between the top and bottom parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head used in a thermal printer or the like, and particularly to a differential type thermal head in which a row of heating resistors is arranged in the paper feeding direction.

[Conventional technology]

Conventionally, a thermal head passes a current through a plurality of minute heating resistors arranged in a straight line and adjacent to each other, and repeatedly performs dot-shaped recording in response to the heat generated thereby. In recent years, with the development of integrated circuit technology, heating resistors and electrodes for connecting them to the outside have been formed on substrates such as glazed ceramics.

FIG. 3 is a plan view of a conventional thermal head.

As shown in FIG. 3, the conventional thermal head has a plurality of heating resistors 2A on a substrate 1 having heat resistance and insulation properties.
2J are arranged in a straight line and adjacent to each other with a certain gap, and in order to connect these heat generating resistors 2A to 2J to the outside, the same substrate 1 is connected from the end of each heat generating resistor 2A to 2J. It has electrodes 3A-3J formed thereon. Further, the other end of each of the heating resistors 2A to 2J is coupled to a common electrode 4 connected to the upper and external parts of the common connection. Note that this common electrode 4 is also formed on the substrate l.

Next, a case where dot-shaped recording is performed using this thermal head will be explained.

FIG. 4 is a diagram showing a recording state using the thermal head shown in FIG. 3.

As shown in Fig. 4, when recording is performed with the row length LK of the heating resistors, the recording medium is line-broken by the same length L as the row length of the heating resistors, and a new line is added following the previous recording. A record will be made.

[Problem to be solved by the invention]

In the conventional thermal head described above, the resistance values of the heating resistors are all in the range -, so when the same voltage is applied, the power consumption and heat generation t are uniform. However,
Heat dissipation is poor at the center of the heat generating resistor array, and the recording temperature at the center becomes high in actual recording due to the circulation of heat from each heat generating resistor. On the other hand, the disadvantage is that heat easily escapes from the outside of the counter pressure heating resistor row, and the top and bottom of the record becomes thinner, so the connection between the top and bottom dots becomes poor between line breaks, and white lines are noticeable at line breaks. be.

Furthermore, in the case of a mechanism in which the thermal head is pressed against a round platen to record information, the pressure at the center of the heating resistor array becomes high, and conversely, the pressure at the outside becomes low. It appears.

One way to counter this is to increase the area of the heating resistors at the top and bottom of the row of heating resistors, but if you increase the area of the heating resistors, the resistance value will be lower than the others. There is a limit because the life of the element becomes extremely short.

Therefore, even with this method, the above-mentioned drawbacks cannot be completely corrected.

[Means to solve the problem]

The thermal head of the present invention has a plurality of heat generating resistors arranged adjacent to each other on an insulating substrate, and is configured such that the length of the heat generating resistor row is also larger than the line feed pitch of the paper feeding mechanism. be done.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

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

As shown in FIG. 1, in this embodiment, a plurality of heating resistors 28 to 2J are arranged in a straight line and adjacent to each other with a certain gap provided on a substrate 1 having heat resistance and insulating properties. .

Further, in this embodiment, in order to connect these heat generating resistors 2A to 2J with the outside, electrodes 3A to 3J are formed from the ends of the respective heat generating resistors 2A to 2J around the lower end of the same substrate 1. Further, the other end of each heating resistor is commonly coupled to a common electrode 4.

FIG. 2 is a diagram showing a recording state using the thermal head shown in FIG. 1.

As shown in Fig. 2, the length of this row of heating resistors is larger than the line feed pitch L of the paper feed mechanism by the width of one dot L+.
It is set to d. When dot-shaped recording is performed using such a thermal head, after recording is performed with a row length of 10 d of heating resistors, the recording medium is line-fed by the distance. Next, a new recording is made, overlapping the previous recording by one dot width d (the shaded area indicates overlap).

However, since the resistance values of the heating resistors in the thermal head are all the same, when the same voltage is applied, the power consumption and the amount of heat generated are uniform. However, heat easily escapes from the outside of the heating resistor array, making the top and bottom of the recording thinner, but as mentioned above, there is an overlap of one dot between line breaks, so the problem of white stripes is not solved. Does not occur.

Here, we have explained L0d in which the row length of the heating resistor is increased by one dot width, but this means that the pressure at the center of the heating resistor row is high, and on the contrary, the pressure at the outside is low. This is an example of a round platen.

In addition, in the case of a mechanism that records by pressing a thermal head against a flat platen, the pressure is uniform over the entire length of the heating resistor row, so the overlap is set to 1/2 dot.
By setting the heating resistor row length to L + d/2, good printing without white lines can be obtained.

In addition to the round platen and flat platen mentioned above, the selection parameters for the size of this overlap are also determined by changing the platen diameter of the round platen, the pressing pressure of the thermal head, etc., and the heat generation resistance of each mechanism. Optimization of body length is relatively easy.

〔Effect of the invention〕

As explained above, since the thermal head of the present invention has a heating resistor row length that is larger than the line feed pitch of the paper feed mechanism, the problem of white stripes between line feeds due to a decrease in recording density at the top and bottom of the recording can be solved. It has the effect of being solvable.

[Brief explanation of drawings]

Fig. 1 is a plan view of a thermal head showing an embodiment of the present invention, Fig. 2 is a recording state diagram using the thermal head shown in Fig. 1, and Fig. 3 is a plan view of a conventional thermal head showing an example. , FIG. 4 is a diagram showing a recording state using the thermal head shown in FIG. 3. 1...Substrate, 2A to 2J...Heating resistor, 3A to 3J...Electrode, 4...Common electrode.

Claims (1)

[Claims] 1. A thermal head having a plurality of heat generating resistors arranged adjacent to each other on an insulating substrate, wherein the length of the heat generating resistor row is made larger than a line feed pitch of a paper feeding mechanism.