JPS606481A - Thermal head - Google Patents

Abstract

PURPOSE:To make it possible to obtain printing quality generating no broken character, by forming mutually connected short thermal heads in mutually shifted arrangement so as to shorten the intervals between heat generating resistors provided to the end parts of said thermal heads in the longitudinal direction of each head. CONSTITUTION:The end sides of short heads 201-20m are respectively inclined at an angle theta in a right upward state and heat generating resistor arrangements 211-21m are provided to the short heads so as to be inclined at an angle alpha from a main scanning direction in a right upward state while a step L is provided between opposed heat generating resistors in the connection part. In this case, heat-sensititve recording paper is fed to a Y-direction and the short heads are driven in the order of 20m, 20m-1...202, 201. Whereupon, the step L' of a printing pattern is reduced as compared with the step L and, when auxiliary scanning line density is set to Y and the number of time shearing is set to m, d=(mY)<-1> is formed while L'=L-d is formed. By this method, a thermal head generating no broken character and excellent in printing quality can be obtained.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a thermal head for thermal recording used in printers, facsimile machines, etc., particularly a long thermal head formed by connecting a plurality of short thermal heads (hereinafter referred to as short heads). Regarding the line type thermal head.

(Prior Art) When manufacturing a long line-type thermal head, the manufacturing yield will decrease if the thermal head formed on a long substrate is used as is. Therefore, only the non-defective parts of the thermal head formed on a long substrate are cut out to make short heads, or short heads are manufactured separately, and the short heads 1-1 to 1-1 are made as shown in FIG. A method has been adopted in which a plurality of thermal heads are connected in the longitudinal direction (main scanning direction) to form a long thermal head. In the figure, 2 is a heating resistor array, and 3 is an electrode.

However, there are technical achievements in the accuracy of cutting, polishing, or bonding of the connection surfaces of short heads, and therefore, at the connection between short heads, as shown in FIG.
The distance d0 between the end heating resistors 2-1.2-1 that undergo IJ is larger than the distance d2 between the heating resistors 2-2.2-2 in other parts. do is the splicing interval between the short heads. Therefore, in the printing pattern 12, there are times when a so-called "white spot" occurs in a portion where printing is not performed in a portion corresponding to the connection portion.

(Objective) An object of the present invention is to provide a long no-line thermal head configured by connecting short heads, which does not cause white spots.

(Structure) The present invention is a line-type thermal head formed by connecting a plurality of short heads in the longitudinal direction 2 of the head, and as shown in FIG. The opposing edges 11-a and 11-b of the short heads 10-a and 10-s to be connected are inclined with respect to the paper feeding direction (sub-scanning direction) y (the angle of the inclination is θ). ), and (b) The heating resistors 12-a and 12-b at each end of each of the short heads 10-a and 10-b are aligned in the direction in which the distance in the longitudinal direction of the heads becomes shorter. a.

11-b. That is, when θ is positive in the clockwise direction as shown in the figure, the heating resistor 12-a at the end of the short head on the left side of the connection section shifts upward, and the heating resistor 12-a at the end of the short head on the right side of the connection section shifts upward. -b is shifted downward. When θ is in the opposite direction, the heating resistor 12-a
, 12-b are shifted in the opposite direction to the above.

Now, in FIG. 3, the space 14 between the short heads of the connection part
d. If the height difference between the end heating resistors 12-a and 12-b is L, then if the design is made so that the following relationship is satisfied: The projections 13 in the directions are arranged at equal intervals as shown in the figure, and there is no "jump" due to the existence of the space 14 at the connection part, and the "jump" during printing is eliminated.
"White areas" will no longer occur. Reference numeral 15 denotes an electrode that supplies current to the heating resistor.

(Example) Examples will be described below.

In the embodiment of FIG. 4, each connected short head 20-
The edges of 1 to 20-m are each tilted upward to the right at an angle θ. Then, in each short head, heating resistor array 2
1-1 to 21-m are provided tilting upward to the right by an angle α from the main scanning direction, and a third
A step is provided as shown in the figure.

FIG. 5 shows another embodiment, each of which has short heads 30-1 to 30-1.
The edge of 30-m is tilted upward to the right as in Fig. 4.

However, each short head has a plurality of heating resistor arrays (
The divided heating resistor arrays 31-1 to 31-3 are parallel to the longitudinal direction of the head, but are offset from each other in the paper feeding direction, and at the connection part, the heating resistor arrays 31-1 to 31-3 are divided into The heating resistors are arranged so as to create a step difference between the heating resistors as shown.

Next, a preferred driving method of the above embodiment will be explained using an example of printing a horizontal line.

FIG. 6 shows each short head 20-1 to 20 of the embodiment shown in FIG.
This is an example of a case where time division is performed every -m to make the drive timing different. In Figure (5), which shows a schematic diagram of a line type head, if thermal recording paper is fed in the direction of arrow y, the short head 20-m → 2O- as shown in Figure (I)). (In-1)→・・・・・・→20-
When driven in the order of 2 → 20-1, the print pattern is as shown in the figure (
5. The difference in white thermal marks in the printing pattern becomes as shown in B). This is less than the step difference at the connection part of the board. In p) of the same figure, [ is the driving time of one time division section, and T is the period.

In the same figure (I3), if the sub-scanning line density is Y and the number of time divisions is m, it becomes d-(mY)-', and the relationship between the step difference and L due to this time-division driving method is L=L-ct. ...... (2) It becomes.

If the drive timing is changed from short head 21-1 to 21-2,
→・・・・・・→21-m If the settings are reversed to the above, the printing pattern in that case will be L'=L+d as shown in C) in the same figure. ...(3), and the steps in the printed pattern become wider, which is undesirable.

As specific data, for example, main scanning line density: 8 dots/rrvns Sub-scanning line density: 7.7 dots/rr
vn.

Given that the printing pulse width is 2.5 milJ seconds, the number of time divisions is 4, and the inclination angle of the short head end is 0810 degrees. According to the driving method of p), the level difference in the printing pattern is approximately 0 compared to the case of the opposite timing diagram driving method.
．． It can be shortened by 6 times.

FIG. 7 shows another preferable driving method when using the thermal head shown in FIG. 4, which is the same as that described above. In this figure, the heat generating resistor array is time-divided into four parts, and each of the divided heat generating resistor arrays is simultaneously driven.

In this case, if the thermal recording paper is fed in the direction of the arrow y in the schematic diagram (5) of the thermal head, the timing of the drive pulses will be set sequentially from the left time-division array section (21 -i)□-...→(21-i)4
and set.

In this case, the height difference I in the print pattern "2" in the figure ([3)] is reduced to 1/n of the height difference in the heat generating resistor of the short head connecting portion. However, in order to have an equal level difference between the connecting part and other parts on the printing pattern, L=y-t(y
It is necessary to set L so that it satisfies the sub-scanning line density).

FIG. 8 shows an example of a preferred method of driving the embodiment of FIG. In the same figure (A) showing a schematic diagram of a thermal head, each divided heating resistor array 31 corresponding to each short thermal head 30-1 to 30-m is shown, where y is the paper feeding direction of the thermal recording paper. -1 to 3l-n (n-4 in the figure), if driving pulses are applied in the order of fcl<3i-i → 31-4 in the same figure, a horizontal-straight line is obtained as shown in (B). In the printing pattern of , the level difference can be canceled out and L'-0 can be obtained.

(Effects) The line type thermal head of the present invention can shorten the distance in the longitudinal direction of the head between the corresponding end heating resistors between the short heads that are connected to each other, so printing can be performed without white spots. A thermal head of excellent quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing a conventional line-type thermal head, FIG. 2 is an enlarged plan view showing the connection between the short heads, and FIG. 3 is the connection between the short heads in an embodiment of the present invention. 4 and 5 are schematic plan views showing embodiments of the present invention, FIG. 6 is a diagram showing a driving method of the embodiment of FIG. 4, and (A) shows a thermal A schematic plan view of the head, (I3) is a horizontal-linear printing pattern according to a preferred driving method, (q is a horizontal-linear printing pattern according to another driving method, p) is a preferred driving timing diagram, and %7 is the horizontal-linear printing pattern of FIG. 4. (5) is a schematic plan view of the thermal head tβ) is a horizontal-linear printing pattern, (Q is a timing diagram, and FIG. 8 is a preferred driving method of the embodiment of FIG. 5. In the diagram showing the driving method, ^ is a schematic plan view of the thermal head, (B+ is a horizontal-linear printing pattern, and (q is a timing diagram.
, 30-1 to 30-m...short head, 11-a, 1
1-b... end side of short head, 12-a, 12-
b , , heating resistor, 2l-1-21-In, 31-
1 to 31-m... Heat generating resistor array. Patent applicant: Ricoh Co., Ltd. Representative Patent attorney: 2 people mentioned above

Claims (2)

[Claims] (1) In a line-type thermal head in which a plurality of short thermal heads are connected in the longitudinal direction of the head, the connecting portions are formed at an angle from the paper feeding direction, and the connecting portions are mutually connected. A thermal head characterized in that the heat generating resistor arrays are formed to be offset from each other along the connection portion in a direction in which a distance in the longitudinal direction of the head between the end heat generating resistors of the short thermal head becomes shorter. (2) In each of the short thermal heads, a heating resistor (3
) In each of the short thermal heads, the heat generating resistor array is divided into a plurality of pieces, and the divided heat generating resistor arrays are formed offset from each other in the paper feeding direction. thermal head.