JPS61224772A - Printing method for thermal printing head - Google Patents

Abstract

PURPOSE:To compensate the printing dot diameter, to prevent the occurrence of the no-printing part and to improve the printing quality by driving the heating resistance element of the edge parts of respective pairs again. CONSTITUTION:When a timing signal from an N bit counter 24 is applied to a strobing signal generating circuit 30, the counter 30 generates strobing signals STR1, STR2 ... STRn. Thus, an N number of the heating resistance elements 21, 22 ... 2n is divided into an N/m pair. In accordance with a signal STR1, respective heating resistance elements are successively driven and printed. In such a case, the printing data to drive heating resistance elements 21 and 2n at both edge parts of the pair from a printing data circuit 34 corresponding to the signal STR1 are applied from a shift register 16 through a latch circuit 14 to a gate circuit 81. As the result, the heating resistance elements 21 and 2n at both edge parts of the pair are driven again and printed in accordance with an auxiliary strobing signal STRs1. This is executed for other signals, and in case of the printing and dividing, the quality of the printing can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a printing method using a thermal print head, and particularly to prevention of print quality deterioration due to print division.

[Conventional technology]

Generally, in a thermal print head, a large number of heating resistors are divided into a plurality of groups and energized to generate Joule heat, thereby coloring the thermal recording paper and recording specific characters, figures, etc.

As shown in FIG. 3, the thermal print head is provided with a large number of heat-generating antibodies 26.2□...2N,
Each heating resistor 23.2t...2. A common electrode 4 is provided on each heating resistor 2. ．． 2.
. . . A driver circuit 6 is provided which selects one or two or more of 2H and causes a drive current to flow. Each of the heat generating resistors 2+, 2g, . ...21.
2□8.2. ．． n gate circuits 81.8f .

Each gate circuit 82.8□...87 is connected to m NAND circuits 10.8, corresponding to each set of m heating resistors 28.2□...2°. , Log...10.
Each gate circuit 81.8□...8,1 and each NAND circuit 100.10t...10. has a common strobe input terminal 128.12□ ,...127
is formed and the strobe signal 5TR11STR2...
5TRn are added sequentially, and the latch circuit 14
A print signal from is added.

The latch circuit 14 is installed to temporarily hold the print signal from the shift register 16.
A latch signal LA is applied to the latch signal terminal 18 formed in the shift register 16 for reading out the held print signal or taking in the print signal from the shift register 16.

The shift register 16 stores the print data D applied to the data input terminal 20 line by line based on the clock signal CP applied to the clock input terminal 22.

Conventionally, the printing method of a thermal print head is to use a heating resistor 29 divided into n groups for printing in one line scan.
2□ ...2. Strobe signal STR+5S every
TRz...This is performed by controlling the drive state using STR,1.

[Problem that the invention seeks to solve]

In the case where such printing division is used, when the contents of the shift register 16 are in a fully printed state, A and A in FIG.
Each strobe signal STR+, STRg shown in BSC
, each set of heating resistor 23.2□ by 5TR3...
・2. is controlled to generate heat.

F, G, and H in FIG. 4 indicate the printing situation in this case, and each strobe signal S T Rr , S T Rt, S T
Since there is a time delay δ between Rz and Rz, the heating resistors 2 and 2 at both end portions of each set. Printed dots dl, d @ , d
s*t, d! The dot diameter of m... is smaller than the normal printing dots d, . . . d, -1.

D in FIG. 4 indicates each strobe signal STR+, 5TRt.
, 5TR3, E in FIG. 4 is each strobe signal STR+
, STRg Each set of heating resistors 21.2□ corresponding to 1STRs...2. The heat distribution in FIG. 4 shows the continuous printing on one line.

Therefore, when the contents of the shift register 16 are fully printed, the printed dots at both ends of each divided set become smaller, so that no markings become a wide white line as shown in J in Fig. 4. There was a drawback that the character part appeared.

The occurrence of such non-printing areas cannot be prevented not only when special continuous black lines are printed, but also when characters or figures are drawn across divided printing areas, which deteriorates printing quality. It was the cause.

Conventionally, as a related technique that may be used to prevent deterioration of print quality, a large number of heating resistors are arranged in a matrix of m rows and n columns, and when recording scan is performed by selecting rows and columns, Printing methods have been proposed, such as partially overlapping n columns and sequentially selecting them and applying recording signals, or driving adjacent rows simultaneously, but each method has drawbacks such as complicating the circuit configuration. was there.

Therefore, it is an object of the present invention to provide a printing method for a thermal print head that prevents deterioration in print quality when printing is divided.

[Means for solving problems]

That is, the present invention provides a printing method for a thermal print head in which a large number of heat generating resistors is divided into a plurality of sets each having a plurality of heat generating resistors, and each set of heat generating resistors is sequentially controlled to be driven. This printing method is characterized in that when a resistor is driven, the heating resistor is driven again after the drive is completed.

[Function] Accordingly, in the present invention, when the heating resistors at both ends of each group divided by printing division are driven, the heating resistors are driven again to compensate for the dot diameter of the printed dots.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a thermal recording apparatus using the thermal print head printing method of the present invention, and the same parts as the thermal print head and its driving section shown in FIG. 3 are given the same reference numerals.

In FIG. 1, a clock signal CP applied to clock input terminal 22 is applied to an N-bit counter 24 that counts N bits. That is, N bit counter 24
is the line scanning signal S applied to the line input terminal 28
Based on the strobe signal generation circuit 30, a timing signal is generated by dividing the line scanning signal section into m pieces based on
and added to the auxiliary strobe signal generation circuit 32.

The strobe signal generation circuit 30 includes an N-bit counter 24
Based on the timing signal applied from the strobe signals STR+ -5TRz...STR,%, these strobe signals 5TRI, STRz...
STR, is the strobe input terminal 12+, 12g,...
12. and to the auxiliary strobe signal generation circuit 32.

The auxiliary strobe signal generation circuit 32 includes a shift register 1
6 is used to detect whether the heating resistor at the divided printing position is driven, and based on this detection, the strobe signal STR.

STR, . ．． 12
g...12. % and is also added to the print data circuit 34.

Then, the print data circuit 34 receives a strobe signal STR.
+, 5TRz...STR, and clock signal C
Print data for coloring the dot portions at both ends of each group divided into prints based on P is output and added to the shift register 16.

In the above configuration, the printing method of the thermal print head will be explained with reference to FIG. 2.

The N-bit counter 24 counts the clock signal and generates a timing signal obtained by dividing one line scanning signal into m pieces. When this timing signal is applied to the strobe signal generation circuit 30, the strobe signal generation circuit 30 generates the strobe signal STR+ shown in A and C1E in FIG.
, 5TRz...STR, is generated. Therefore, N heating resistors 2. ．． 2. ...2. ．． 2. or 1.2m*t...2N is this strobe signal S
TR,, 5TRffi ...m corresponding to STR,
Each set is divided into NZm & Il.

On the other hand, when the print data added to the shift register 16 indicates silkworm printing, the data is sent via the launch circuit 14 to the gate circuits 8I, 82 . . . 8 . each NAND of
It is added to the circuit 108.10g...10.

As a result, for example, the heating resistor L 12t...21.2 responds to the strobe signal STR shown in A of FIG.
□1 is sequentially driven, and printing is performed as shown at H in FIG. 2 in response to the strobe signal 5TRI.

In this case, the strobe signal STR is applied to the auxiliary strobe signal generating circuit 32, which is connected to the heating resistors 2 at both ends of the set.
．． ．． 2. An auxiliary strobe signal STR□ as shown in FIG. 2B is generated at a fixed time interval according to the print data of , and is applied to the strobe input terminal 12° after the strobe signal STR.

Then, in response to the strobe signal STR, the print data circuit 34 outputs the heating resistors L, 2 at both ends of the set.
- The print data for driving the shift register 16
from the gate circuit 8 through the latch circuit 14. will be added to. As a result, as shown in FIG. 2, the heating resistors 2. ．． 2. is re-driven and printing is obtained.

Such print scanning is performed using a strobe signal S T
R! . . .STR, the same process is performed, and each strobe signal 5TRt as shown in C and H in FIG.
. . . After being printed as JIL in FIG. 2 in response to STR, the auxiliary strobe signal 5 shown in DSF in FIG. 2 is printed.
TRst...5TR3ll, again, as shown in FIG. 2, heat generating resistors 2. .

1.2 □, . can get. As a result, as shown at 0 in FIG. 2, in the case of continuous printing, the occurrence of non-printed portions due to printing division can be prevented.

Although the embodiments have been explained by taking continuous black printing as an example, the present invention can similarly prevent the occurrence of non-printed parts even in characters and figures where the printing division part is continuously driven, and improve the printing quality. can be improved.

In addition, in the embodiment, the print data that drives the print division part is formed by the print data circuit, but it is also possible to temporarily store the print data that drives the part and read the stored data at a specific timing. good.

〔Effect of the invention〕

As explained above, according to the present invention, when printing is divided, the heating resistors at both ends of each set are driven again, so the diameter of the printing dots can be compensated, and the occurrence of non-printing areas can be prevented. It is possible to improve printing quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a thermal printing device used in the printing method of the thermal print head of the present invention, and FIG.
FIG. 3 is an explanatory diagram showing an embodiment of the printing method of the thermal print head of the present invention, FIG. 3 is a block diagram showing the configuration of a general thermal print head, and FIG. 4 is an explanatory diagram showing its operation. 2+, 2-...2N...heating resistor, 30
... Strobe signal generation circuit, 32 ... Auxiliary strobe signal generation circuit, 34 ... Print data circuit 32°

Claims (2)

[Claims] (1) In a thermal print head printing method in which a large number of heat generating resistors are divided into a plurality of sets of each set and each set of heat generating resistors is sequentially controlled to be in a driving state, the heat generating resistors at both ends of each set are A printing method for a thermal print head, characterized in that when the heating resistor is driven, the heating resistor is driven again after the driving is completed. (2) The re-driving of the heating resistors at both end portions shall be carried out after each set of heating resistors is sequentially controlled to the driving state, and within the drive time interval of each set of heating resistors or after driving one line. A printing method using a thermal print head according to claim 1.