JPS58131081A - Thermal printer - Google Patents

Abstract

PURPOSE:To prevent a thermal head from overheating, by a method wherein a printing range for one line is divided, and printing of said one line is performed by a plurality of scanning operations, when an electric current is continuously passed through at least one of heating printing elements for a period of time not shorter than a predetermined period. CONSTITUTION:When a printing-controlling part receives a printing-restricting signal, printing of a row of dots corresponding to the subsequent printing timing T4 and the following timings is conducted by printing at every other printing timing. Namely, printing is conducted at the timing T4, is not conducted at a timing T5, and is conducted at a timing T6, Fig. (1). When printing of the line is completed, a carrier is reset without feeding a heat-sensitive recording paper by one line space, and printing of part corresponding to the timings T5, T7... which have been skipped in the preceding printing is conducted, whereby printing of one line is completed, Fig. (2). Accordingly, a printed pattern with a high density, Fig. (3) can be obtained, and the thermal head can be prevented from overheating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printer, and more particularly to a thermal printer in which overheating of a thermal head is prevented.

The thermal head of a conventional general thermal printer is shown in FIG. 1. The thermal head 1 has, for example, 7 elements in a vertical row 4+a% on the front side of a ceramic electric board 1iJ with an aluminum heat plate 1 hidden behind it. It has a heat generating printing element section (hereinafter referred to as 1 heat generating element section) 41 consisting of I1g.

Figure 2 shows a cross section of the thermal head l.
Forming a vitreous heat insulating layer j on a ceramic substrate J,
A resistor layer 6 is formed on the heat insulating layer S, and the resistor layer 6
A lead portion 7 made of a conductive layer and a ground ill are formed on the top in a shape vA (pattern) as shown in the first figure, and the surface between these 7 is further covered with a protective layer! covered with

When printing, a current t' is caused to flow through the resistor layer 6, which serves as the first heating element part, from the lead s7 to the grounding part t, as shown by the arrow M, to cause the heating element part to generate heat. Printing is performed by coloring the heat-sensitive recording paper that has been pressed into close contact with the paper in a desired pattern. At this time, when continuous current is applied for a relatively long period of time, the generated heat is transmitted to the center of the heating element in a concentric circle i0*m10b, IOc, but the heat insulating layer 5 prevents this rapid heat dissipation during current application. It is prevented.

As shown in FIG. 3, which is an example of a thermal printer equipped with the above-mentioned thermal head 1, when print data is supplied from a print data supply section (not shown), the carrier (mobile table) 1 that supports the thermal head 1 is moved. A stepping motor (not shown) moves the horizontal bar at the right direction along the guide rail 13 via the wire 12 in the same direction as the arrow. When the thermal head 1 reaches the desired printing position indicated by the printing data, the head control lever 41 moves upwards in the direction of the straight arrow due to the biasing force of a lunoid (not shown), so as to face the thermal head. Rotate the carrier in the direction of rotation arrow E around the provided platen/1. At that time, platen/j is l1clI of thermal head l! lI recording paper 1
4 from the back side, the thermal head l is brought into close contact with and pressed against the thermal recording paper 11. At the same time, since the thermal head 1 is located at the printing position and the heating element part is energized, it is possible to generate color and print on the thermal recording paper 16. In addition, printing starts from the left end of the thermal recording paper 14, and when the carrier/I moves to the right end and printing of one line is completed, the carrier moves back to the straight arrow C to the left of the thermal recording paper 14. Recording paper / 4 upward rotating arrows F 1 to 1
Feed one line and move on to printing the next line.

Characters and figures (patterns) such as alphabets and numbers printed by the thermal head 1 are printed by a dot matrix of jX pixels. A typical example of printing with this thermal head l is shown in Figure 4 1c.
Shown in +. ! Figure 4 is an example of a device that prints characters such as a general Alphabella tld and numbers, and the same heating elements 111-
This is an example in which pg is not continuously energized for a long period of time. #
! Figure 4 (5) is an example of printing the wj line, and #! This is an example in which the honorable heating element +d is continuously energized for a long period of time. Fourth
FIG. 1c+ is an example of printing a relatively high-density bar graph.

Third. Da-th and S-th heating elements +c, ld
.

4(e) is an example in which electricity is continuously applied for a long period of time.

The fifth position shows the waveform of the energizing pulse ps supplied to, for example, the second heating element (heating printing element) +a when continuous energization is carried out for a long period of time as shown in Figures 4 and 4. Figure 5 (5) shows the state of change in the temperature TM of the heating element 1d during continuous printing corresponding to the output of the energization pulse PO. When the heating element Qd is heated, the temperature 'rM of one heating element Qd rises to a level higher than the coloring temperature level (coloring level) HL of the thermal recording paper t6, and a desired color printing pattern is generated on the thermal recording paper t6. The energization pulse Pji/ in the figure is a long-time energization pulse that is energized when the same heating element ud is not energized at the previous energization timing, and heats the heating element 1Idt, which has almost completely radiated heat. The following one energization pulse PS2 is a short-time energization pulse that is energized when the concave heating element d is energized at the immediately preceding energization timing.

The M element qd whose heat dissipation has not been completely completed is heated.

In other words, in order to prevent sudden heat radiation while energizing the 9 heating element + azI1g, the heating element section is provided on the insulation 1-5 (see Fig. 2 β). ~ Once energized, heat accumulation occurs as shown in TM/ in box S (8), so if continuous energization is performed as in No. If energization is carried out for a short period of time as shown in the figure, the thermal head will be overloaded, so one energization pulse P8 includes a pulse Pa/ with a long pulse width and a pulse P with a shell time pulse width as shown in the figure.
IJ is set. However, despite setting the long and short pulse widths Pig/ and PB in consideration of continuous energization, as shown in No. 4N- and (6), the heating elements 4!1~++gK are When continuous current is applied for a long period of time, the printing heat generated in the heating elements 4a to 1g is as follows.
As shown in FIG. 2, concentric circles/Oas/Ob are formed around the heating element II.

Insulation layer in lOc shape! If the current is continuously energized for a longer period of time, heat will accumulate in the ceramic substrate @J and the heat sink. Therefore, the amount of heat dissipated between the pulses of the energizing pulse P8 to the first heating elements 47a to 47g decreases, and as shown in TMJ in FIG.
As the amount of heat stored in g increases abnormally, element da a''-
The maximum temperature at 41g also begins to rise as shown at TMJ.

In this way, more heat is stored than the set value in the heating elements 41a~
If this happens, there is a possibility that the thermal head 1 will be destroyed by overheating the heating element part 1.If the excess heat storage amount TM2 approaches the coloring level HL, the printed product 'M' will also be affected. It will drop significantly.

As a flat film to prevent excessive heat accumulation in the heating elements 41m to 41m due to continuous energization for a long period of time, it is possible to use a hand plate that lengthens the interval between energizations and slows down the printing rate, thereby allowing sufficient heat dissipation time. . By that means, Fig. 4 IfLl and El
If continuous energization is not performed for a long period of time as shown in Figure 4, there is an inconvenience that the printing speed becomes slow even when printing general characters as shown in Prisoner No. 41.

In view of the above-mentioned drawbacks, the present invention allows ordinary printing of single characters, symbols, etc. to be performed at high speed, and conducts subsequent heat generation related to periods using one heating element of the thermal head for m-, underline, and bar graph types. Only if the printed part λ
(Durability that allows printing of continuous m+pattern 7 such as 0wl lines by dividing printing into multiple times of g1 or more, while printing normal character formats at high speed, @1Mi VB's objective is to provide a thermal printer with good performance.

FIG. 6 shows an example of the main part configuration of the thermal printer of the present invention, where -0 is print data! The print signal caf: is adjusted as described later from the print limit signal L8 and the print limit signal L8, and the print signal C8 is supplied to each heating element lI1%IIg of the printer via the thermal head driver co5. 31, which also performs electric control of the carrier//.
~37 is a flip-flop 3/~J prepared independently for each of the seven heating elements 1~Ig consisting of seven vertical elements.
7 and are individually connected to the seven output terminals of the print control section 20. 4I/~Gua is the flip-flop 31~
A /hex cow/re is prepared independently for each of the three, and a flip-flop J/-J? Connect to each of the output terminals of the Connect the positive output 11/ terminals of the 7 lip-flops 7/-j to the set input terminals a of the hexadecimal katanta 41/~tei, and connect the 8 negative output terminals of the 7 lip-flops J/~J7. The reset input terminals bK of the hexadecimal counters 41 and 41 are connected, respectively. 3
0 is 14j! This is an OR circuit (OR circuit M) connected between all of the output terminals of the counter &/-117 and the input terminal of the printing brake unit θ, and the output obtained as a result of the OR operation is used for 13-character control @ -III! Supplied to print restriction signal 〇 as IL8. The rest of the configuration is almost the same as the conventional example shown in Figures 1 to 3, so a description thereof will be omitted.

Next, the operation of the thermal printer of the present invention shown in No. 6 will be explained.

Not shown is from a higher-level device such as a single-character data supply unit.

Supply the print data ID4 to the semi-control unit 20, and print the mark 5F.
t) rllNils, 2 o < stepping motor (not shown) Ikll! When the carrier l/ is moved by one movement and the sumal head/ is moved to the desired printing position Pk.

From print control unit λQ to thermal head driver j #J
The character multiplication signal C8 is supplied. [eye] character signal C8 is simultaneous ni 7 rig 70 tsubu J/~J? also be supplied.

This corresponds to the case where the print signal CS is 1/' which instructs printing energization. 7. Set the lip flops 37 to J7 to output '/'It at the positive output 87. on the other hand.

10 The print signal cg instructs not to energize printing.
', the corresponding 7 lip-flops 31 to 3 are reset and III is outputted to the negative output 8J. Therefore, the printing that is supplied from the printing control section θ to the heating elements 1 to dag is The output of the signal CI is continuously i1. That is, when continuous energization printing signals are supplied to the same heating elements a to 41g.

16-way cow/tag l corresponding to the heating element daa-gk
- The print signal cg to the same heating element da-a-g is 101. That is, when there is a pause in the print signal C8, it is possible to reset the hexadecimal counter 7 and start the output 17 from the beginning again. The count number of hexadecimal counter lI/-417 is '/!
” When you step forward with !

The output signal C3 is set to % and l and is supplied to the OR circuit SOK. Therefore, when at least one of the seven heating elements 'I a -47g is energized 11 times in a row, the output of the logical sum circuit go, the immediate character @flash symbol Li, becomes %,, j
and is supplied to the print control unit -〇.

Print control unit - 〇 is printing' limit gN number L8 is %, g is printing - The print data ID supplied for each line is used as the print signal C8 as it is, and is sequentially sent to each heating element via the thermal head driver j. 11 to eg, and the printing limit signal LiI-b'-''/'i is supplied to the last dot of the printing line.
If c is not obtained, 1 by the same scanning of the thermal head l.
Complete the printing for the line and move on to the W main work for the first line. Therefore, in the case of printing general characters as shown in FIG. 4 1cl, high-speed printing is possible by scanning the thermal head 101 times. On the other hand, the print control unit 217 outputs "1 i ' if the print limit signal Lit becomes % or l in the middle, that is, if a continuous print signal +5C8 of the same heating element lIa to dagWc14 dot row is supplied. % of print data obtained by thinning the print data ID using the tFQ character timing device from the next dot row that received the print restriction signal L8.
By supplying cs and scanning the v-w head l, one line printing is performed using the l printing timing device, and only the carrier it is returned without feeding the paper in the first stage, and the thinned out part on the m side is printed. By supplying the appropriate print signal C8f and causing the thermal head l to perform the first scan t, printing is performed at the print timing portion that was paused in the previous scan, and printing for one line is completed. Note that the print control unit KO is the first one described above.
In IIl of the divided printing due to the first thinning, the printing portion performed in the first scanning is sequentially temporarily stored in the internal memory (not shown) of the printing control unit-0, so that the printing signal CS of the first printing scanning is supply

Furthermore, in order to facilitate understanding of the present invention, No. 41 Garden and I
Q [Ikko body figures when the shown ruled lines and bar graphs are printed by the printing means according to the present invention described above are shown in FIG. 7 IA.
I-1a and FIG. 84-iOK are shown.

In the case of the ruled line printing of the kite 7 ^ and @ corresponding to FIG. 4 (8), only the second heating element da d is continuously energized. That is, at the w-shaped timing T/ at the start of printing, all heating elements IIa-dag are energized, and all of the /quaternary digits 41/-da7 are quantized to become 'A t l, but at the primary printing timing. In 7.2, only the first heating element d is energized for printing.

Among the 417 to 4I7, only the 97 risantei is increased to 12', and the others are 9/S$3 and +kS-1? has been reset and is 10I
K Go back. In the dot row after the print timing lever, only the heating element d of sugar number q is continuously energized, so only the corresponding hexadecimal quanta 4IQ is powered up by 97 tones, and the other colors 411 to q3 and 4Ij to d7 is not affected by force 9 (Figure 7 prisoner, c + @ solution). Next, when the energization/current to the second heating element d is lj @ continuous w-shaped timing T, the output S3 of the 744 force + 7/tatei is l
', and the printing limit signal L of 'l' is output from the - common sum circuit Sθ.
8 is supplied to the print 1 control section KO.

Pressing system #Sko0 is +1. When the printing restriction signal L8 of j is damaged, printing of the dot row after the eighth printing timing Td is performed by dividing printing (thinning printing) at l timing. That is, printing is performed at printing timing Tda, and printing is stopped at printing timing Tj.

At printing timing T4, printing is performed.

Do the W shape of z*@Ill (see prisoner 71). In this way, printing continues after printing timing T4', and when printing of this line is finished, the carrier l/ is returned without feeding the thermal recording paper 16 by one unit, and thinning printing is performed as shown in Fig. 7 @. The printing of the parts j, T, etc., which stopped printing after the printing time/g Tel '□ that was performed, is performed in the a-th scan, and the printing for one machine is completed. The same control means as described above is also used to print the bar graph section of LBl in Figure 8, which corresponds to 1cl in Figure 4.

Print the bar graph section separately. Figure 8 shows the hexadecimal counter 4I/-4+ 7's Kawanta trough at that time. Only when continuous power is applied for a long period of time, print the - line by scanning the thermal head multiple times (twice for the above-mentioned edge), and at the printing timing after which there is a risk of overheating. Since printing is performed by dividing printing every few columns (thinning printing), when printing general characters as shown in the 4th column, high-speed printing is possible with one scan of the thermal head l. For printed pattern parts such as the ruled lines and bar graphs shown in Figure 4 @ and clK where the same heating element 4'a-4Igfc is required to be continuously energized for a long period of time, the heating time interval of the same heating element is lengthened. It is possible.

As a result, the heating element +a can be used without reducing the overall printing speed.
It is possible to prevent overheating and deterioration of printing quality due to heat accumulation of ~+g, and it is also possible to improve durability and reliability by -j.

According to the present invention, since continuous energization is detected for each heating unit, the present invention has an effect that can be applied even to the case of ruled lines as shown in FIG. 4 (8).

In the above-described embodiment of the present invention, hexadecimal quanta was used as the flat membrane for detecting the number of consecutive energizations.

Depending on the structure of the thermal head and the heat storage percentage Note, 32-decimal quanta or other counters may also be used.

If you use a counter that fits the thermal head you are using, 9.
y・Furthermore, in this embodiment, the heating element 1 of the thermal head
A heating element with 7 elements in a 11c wheel row was used.

The number of heat-generating elements is free, such as a matrix head with S x 7 elements.For example, the number of heat-generating elements is arbitrary, and the number of heat-generating elements is arbitrary. The recording paper may be scanned instead of using the thermal head. Of course, the present invention is also suitable for printers such as thermal transfer printers that print on plain paper using a thermal transfer ink ribbon.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a general thermal head, Fig. 2 is a cross-sectional view showing the cross-sectional structure of the heating element portion, and Fig. 3 is a general outline of a general thermal printer equipped with the thermal head shown in Fig. 1. Perspective view showing the structure of the part, #! Figure 4 is an enlarged view showing an example of the printing pattern printed by the prisoner's thermal printer. A characteristic diagram showing the temperature change of the heating element, FIG. 6 is a block diagram showing an example of the configuration of the main parts of the thermal printer of the present invention, FIG. 7 ^~IC1 and FIG. 8 ^~Ω are #!, respectively. 7 is an enlarged view showing an example of a print pattern printed by the thermal printer of FIG. 6, and an explanatory view showing the contents of a hexadecimal input at that time. FIG. l... Thermal head, Co... Release 11 [. 3... Ceramic substrate, Hiroshi... Heat-generating printing element section. 'I a -44g... Heat-generating printing element. j...Insulating layer, 6...Resistor layer. 7...Lead part, I...Ground part. ? -°・Hoichi layer, loa~loc...Concentric circles. / /−−°Carrier, lco...wire. /3... Kite rail. /Su...Head control lever. /S...platen, /4...thermal recording paper. Ko 0... Inkyo 匍 j obe. j2! I 0 = Thermal hend driver. 31-37...Flip 70 knobs. tl/-da7...hexadecimal kawantah. SO...-Konwa circuit (OA circuit). ID/°°print data, L8...Printing restriction signal. cs...Print signal. T/~T7...Print timing. ps... energizing pulse. PS/...Long time energizing pulse. Plico...Short-time energizing pulse. TM...heating element temperature, ML...color development level. 'i'M/, TMko, TMJ...Heat storage level. A to F...arrow direction. Patent applicant Canon Co., Ltd. Figure 2 J Ryo / 72
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Claims (1)

[Claims] In a thermal printer that performs print scanning by moving a thermal head having a heat-generating print element of ms relative to a recording paper, when the heat-generating print element is continuously energized for a long period of at least 1IIK predetermined period or more, - line Between printing! 4111 The thermal printer is equipped with a control means for performing printing scanning in a plurality of times (b) by dividing printing.