JPS62170363A - Method and apparatus for interpolation for slant line in thermal printer - Google Patents

Abstract

PURPOSE:To achieve smooth interpolation for a slant line, by a system wherein the thermal output of each heat generating in printing an interpolating dot is set to be smaller than that in printing a basic dot. CONSTITUTION:In a printer, for example, a multiplicity of heat generating elements are provided in a vertical row on a substrate to form a thermal head, and desired ones of the elements are energized while moving the head at a predetermined pitch in the transverse direction relative to a printing paper, thereby printing the paper with dots corresponding to the energized heat generating elements. When printing a slant line by the printer, basic dots X, Y, Z arranged skewly and pairs of interpolating dots x1, x2 and y1, y2 so located as to partially overlap with the adjacent basic dots and being contiguous in a linear form are alternately printed. In addition, the energization time is so controlled that the thermal output of each of the heat generating elements in printing the interpolating dot is smaller than that in printing the basic dot. Accordingly, the basic dots can be smoothly interpolated with the roundish interpolating dots.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a thermal printer that prints characters, figures, etc. using a so-called dot matrix, and in particular to a thermal printer that improves the interpolation method between dots for printing smooth diagonal lines. The present invention relates to a diagonal line interpolation method for a printer and a diagonal line interpolation device for a thermal printer.

[Technical Background of the Invention] This type of printer has a thermal head configured by arranging a large number of heating elements, for example, vertically on a substrate, and moves this thermal head at a predetermined pitch in the horizontal direction with respect to the printing paper. The system is configured to energize a required heating element and print dots corresponding to the heating element on the printing paper. This results in
For example, it is formed by a dot matrix in which characters are arranged vertically and horizontally at a predetermined pitch. In this case, the diagonal line is formed by arranging dots diagonally, but as shown in FIG. The dots are shifted by a pitch, and since the heating element is formed in a rectangular shape and the printed dots are also rectangular, the shaded areas become stepwise, making it impossible to obtain smooth printing quality.

In order to cope with this problem and smooth the diagonal lines, the following diagonal line interpolation method has been conventionally provided. That is, after the basic dot a forming the diagonal line is printed (the basic dots c and d forming the straight line are also printed at the same time), the thermal head moves one pitch to the position where the next basic dot b is printed. In between, the same heating element as that used to print the basic dots a and b is energized. As a result, as shown in FIG. 8(B), interpolated dots a' and b' are positioned so as to partially overlap each basic dot a and b, and are linearly continuous vertically.
is printed, the step difference in the direction of movement of the thermal head is equal to half a pitch, and the diagonal lines appear smooth.

[Problems with the foreground technology] However, in the conventional diagonal line interpolation method described above, the amount of heat generated by the heating element when printing interpolated dots is set to be the same as that when printing basic dots, without making any particular distinction. For this reason, the interpolation dots a" and b- are also printed in a rectangular shape, so the periphery of the interpolation dots a" and b- becomes angular, making it impossible to print a sufficiently smooth diagonal line. Moreover, if we interpolate the long diagonal line as shown in Figure 9(A) using this method, it will become as shown in Figure 9(B), so in the end, the step difference in the direction of movement of the thermal head will be one pitch. There is a problem that the effect of interpolation is not fully demonstrated.

[Object of the Invention] Therefore, the first object of the invention is to provide a diagonal line interpolation method in a thermal printer that can sufficiently smooth the diagonal lines, regardless of the length of the diagonal lines. An object of the present invention is to provide a diagonal line interpolation device for a thermal printer that can implement the method with a simpler configuration.

[Summary of the Invention] The present invention was made based on the fact that when the amount of heat generated by the heating element of a thermal head is suppressed, the temperature rise at the peripheral portion of the heating element is delayed, resulting in printed dots becoming rounded. be. That is, the first invention alternately prints diagonally arranged basic dots and a pair of linearly continuous intervening dots that are positioned so as to partially overlap each adjacent basic dot when printing diagonal lines. It is characterized in that the amount of heat generated by the heating element when printing the interpolated dots is smaller than that when printing the basic dots, so that the rounded interpolated dots can smoothly print between the basic dots. This allows for accurate interpolation.

Further, the second invention includes a first energization time control means that controls the energization time of the heating element during basic dot printing, and a second energization time control means that controls the energization time of the heating element during interpolation dot printing.
energization time control means, and the energization time to the heating element controlled by the second energization time control means is controlled by the first energization time control means.
The present invention is characterized in that the time is shorter than that controlled by the energization time control means, thereby making it possible to smoothly interpolate diagonal lines and easily control the amount of heat generated.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. In FIG. 1, reference numeral 1 denotes a well-known thermal head, although not shown, in which, for example, 24 heating elements that generate heat when energized are provided in a line in the vertical direction on a substrate.
Each heating element has a rectangular shape. This thermal head is mounted on a carriage (not shown), and the carriage is moved at a predetermined pitch in a direction perpendicular to the direction in which the heating elements are arranged, that is, in the lateral direction, while energizing the required heating elements to generate heat. A dot corresponding to the body is printed on the printing paper. Reference numeral 2 designates a timing pulse generator that generates a timing pulse with a duty ratio of 1/2 (see FIG. 2(A)), and 3 designates a data memory in which print data is stored. The print data is read one pitch at a time by an address pointer 4 that advances each time it receives a timing pulse from the timing pulse generator 2, and is stored in a print data latch 5. 6 is an interpolation data calculation section,
This calculates interpolation data for printing interpolated dots based on the print data in the data memory 3. The calculated interpolation data is stored in the interpolation data clutch 7. still,
As in the past, interpolation dots are made from two dots that are arranged in a straight line in the vertical direction and are positioned so that a portion overlaps each adjacent basic dot among the basic dots that are arranged diagonally during diagonal line printing. configured. Reference numeral 8 denotes a first energization time control means, which includes an AND circuit 9 and a first energization/energization time storage section 10.
The print data from the print data latch 5 is applied to the multiplexer 11 when the output from the first energization time storage section 10 becomes high level. 1
2 is a second energization time control means, which is an AND circuit 13
and a second energization time storage section 14, and when the output of the second energization time storage section 13 becomes high level, interpolation data from the interpolation data clutch 7 is given to the multiplexer 11. Here, during the first energization, the 1ul storage unit 10 outputs a high-level pulse with a pulse width of tl (for example, 1m5ec) in approximately synchronization with the rising edge of the timing pulse, as shown in FIG. 2(B), As shown in FIG.
It is set to output a high-level pulse with a pulse width of . Then, the multiplexer 11 selectively outputs print data or interpolation data to the driver 15 in synchronization with the rising and falling edges of the timing pulse, so that each heating element of the thermal head 1 is energized according to the data. Ru.

Next, the operation of this embodiment will be explained. When a print start signal is received, one column of print data is read from the address designated by the address pointer 4 and stored in the print data latch 5 (step a in FIG. 3). Next, calculation of the interpolated data is executed (step b in the figure). A subroutine for calculating this interpolated data is shown in FIG.

The calculation contents shown here are as follows: When the column specified by address pointer 4 is column A, and the next column is column B,
Only in the following two cases, the Nth bit of the interpolated data is “1”.
” is set, and “0” is set in other cases. That is, the first case is the case where the Nth bit of column A is "0", the N+1 or N-1th bit is "1", and the Nth bit of column B is "1". The second case is when the Nth bit of column A is "1", the N+1 or N-1th bit of column B is "l", and the Nth bit of column B is "0". . This is repeated from N-0 to N-23 to complete the interpolation data calculation. As a result, if the print data is such that basic dots are arranged diagonally,
This means that interpolation data has been calculated for printing a pair of interpolation dots that are linearly continuous in the vertical direction and are positioned so as to partially overlap each basic dot. After the interpolated data is calculated in this way, the interpolated data is stored in the interpolated data clutch 7 (step C in FIG. 3).

Thereafter, while moving the carriage at a predetermined pitch, as shown in step group d in FIG. given the basic dots and interpolated dots are printed. Then, as shown in Figure 5, the basic dots x, y,
z is arranged at intervals of 1 pitch, and the basic dots
.

One pair of interpolation dots between y and z 1 + X
2, yl, and y2 are located. in this case,
Since the time width t2 of the high-level pulse outputted from the second energization time storage section 14 is shorter than the time width t1 of the high-level pulse outputted from the first energization time storage section 10, heat generation of the thermal head 1 occurs. The time for energizing the body is shorter when printing interpolated dots than when printing basic dots.
As a result, the amount of heat generated by the heating element when printing interpolated dots is smaller than that when printing basic dots. Therefore, when printing basic dots, the entire area of the heating element becomes high temperature, and a rectangular dot that matches the shape of the heating element is printed.
When printing interpolated dots, the temperature rise at the periphery of the heating element is delayed, and as a result, the high temperature area is limited to the center of the heating element, so the dot is printed as a rounded dot with a chipped periphery, and the dots are printed as basic dots x, y, x. Mutual relations are facilitated. Furthermore, if only a pair of interpolated dots were printed without printing a basic dot immediately before, each interpolated dot would not be completely However, in the present invention, the basic dots are printed immediately before the interpolation dots are printed, and residual heat from the heating element remains at that time, so the smeared portion (fifth The area (indicated by a large number of dots in the figure) expands toward the basic dots, and the basic dots x, y, . . . , z are captured more smoothly. Incidentally, the eighth example shown when explaining the conventional interpolation method
For example, when interpolating the same basic dot arrangement as in Figures (A) and 9(A), Figures 6(A) and (B)
), and it is clear that the stepped portion is smoother than those in FIGS. 8(B) and 9(B), and sufficiently smooth interpolation is possible. Also, the letter rW
An example of printing J is shown in FIG. It is clear from this that the straight line portion is displayed as a clear line by continuous rectangular dots, and the diagonal line portion is smoothly displayed by the rectangular dots and rounded interpolation dots.

As described above, according to this embodiment, the amount of heat generated by the heating element when printing interpolated dots is made smaller than that when printing basic dots, so that the interpolated dots are printed with a rounded shape, and the interpolated dots are printed with a rounded shape. Since residual heat during printing causes a bleed that spreads from the interpolated dots toward the basic dots, an excellent effect is achieved in that extremely smooth diagonal line interpolation is possible. Moreover, in making the heat generation amount of the heating element different in this way, the first and second energization time control means 8.1
Since each energization time in 2 is made shorter in the second energization time control means than in the first energization time control means, so to speak, it is a time control method. This can be particularly simplified if the software is used. In other words, in order to control the amount of heat generated, a configuration may be considered in which the voltage applied to the heating element is varied, but this inevitably tends to complicate the configuration, such as requiring a switching element to switch the applied voltage. This is because the time control method does not require it.

Note that the present invention is not limited to the embodiments described above and shown in the drawings; for example, the degree of reduction in the amount of heat generated for printing interpolated dots may be varied depending on the arrangement of basic dots. It can be implemented with various modifications within the scope.

[Effects of the Invention] As described above, the first invention is characterized in that the amount of heat generated by the heating element when printing interpolated dots is smaller than that when printing basic dots. As a result, interpolated dots are printed that are rounded and have a smear that spreads toward the basic dot side, making it possible to smooth the interpolation between diagonal lines. Further, the second invention is characterized in that, when embodying the first invention, the time of energization of the heating element controlled by the two energization time control means is made different, and as a result, This provides an excellent effect in that smooth diagonal line interpolation is possible with a simple (1t) configuration.

[Brief explanation of drawings]

1 to 7 show one embodiment of the present invention, FIG. 1 is a block diagram of the main parts, FIG. 2 is a voltage waveform diagram of each part showing the time and timing of energization to each heating element, FIG. 3 is a flowchart showing the printing process, FIG. 4 is a flowchart showing interpolation calculations, FIGS. 5 to 7 are plan views showing examples of diagonal line printing, and FIGS. 8 and 9 The figure is a plan view showing an example of printing by a conventional method. In the drawing, 1 is a thermal head, 3 is a data memory, and 6 is a thermal head.
8 is an interpolation data calculation unit, 8 is a first energization time control means, 1
2 is a second energization means control means.

Claims (1)

[Scope of Claims] 1. In a thermal printer that prints dots corresponding to the heating elements on printing paper by moving a thermal head in which a predetermined number of heating elements are arranged in a row and energizing the heating elements, when printing diagonal lines, , alternately printing diagonally arranged basic dots and a pair of linearly continuous interpolation dots positioned so as to partially overlap each adjacent basic dot, and printing the interpolation dots. A diagonal line interpolation method in a thermal printer, characterized in that the amount of heat generated by the heating element during printing is smaller than that when printing the basic dots. 2. A thermal printer that prints dots corresponding to the heating elements on printing paper by energizing the heating elements while moving a thermal head in which a predetermined number of heating elements are arranged in a row, and when printing diagonal lines, the thermal printer is arranged diagonally. in which basic dots are printed alternately and a pair of linearly continuous interpolation dots that are positioned so as to partially overlap each adjacent basic dot, the heat generation during printing of the basic dots; a first energization time control means for controlling the energization time of the heating element; and a second energization time control means for controlling the energization time of the heating element during the interpolation dot printing;
A diagonal line interpolation device for a thermal printer, characterized in that the energization time to the heating element controlled by the energization time control means is shorter than that controlled by the first energization time control means.