JPS5814785A - Boldface character printing system for thermal printer - Google Patents

Abstract

PURPOSE:To print a boldface character favorably without lowering the printing speed, by a method wherein a common electrode is provided on the center line of heating elements placed in one row on the outside peripheral surface of a cylindrical substrate, and the parts on both sides of the common electrode are individually supplied with an electric current to generate heat. CONSTITUTION:When the center line of a head 1 is maintained to be orthogonal to a thermal printing paper 3 anda platen 4, the maximum color density can be obtained by a method wherein the printing in the printing direction (+) is performed by the electrode provided at the position inclined by an angle of +theta0 and the printing in the printing direction (-) is performed by the electrode provided at the position inclined by an angle of -theta0. A common electrode 5 is provided on the center line of the heating elements 21-2n, and individual electrodes 611-61n, 621-62n are provided. When printing boldface characters, the characters can be printed favorably without lowering the printing speed, by passing an electric current through the individual electrodes 611-61n, 621-62n simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bold character printing method for a thermal printer, and particularly to a bold character printing method that does not reduce printing speed and is suitable for a serial thermal printer that performs bidirectional printing.

Conventional thermal printer heads are, for example,
As disclosed in Japanese Patent No. 65550, a large number of heating elements are arranged in one row on the outer peripheral surface of a cylindrical base made of an insulator such as glass or ceramic (hereinafter referred to as "one row"). (referred to as "mold head").

In thermal printing in which recording is performed on thermal paper using a single-row head configured as described above, there is a constant difference between the contact pressure between the heating element on the head and the thermal paper and the coloring density of the thermal paper. There is a relationship as follows, and if the driving conditions of the head and the ambient temperature are constant, the color density increases as the contact pressure increases. This point will be explained in detail below 2).

When using the first head having the heating element 2 arranged on the cylindrical substrate as described above, the heating element 2 and the surfaces of the thermal paper 3 and the platen 4 are usually parallel to each other as shown in FIG. The heating element 2 is placed on the center line of the curved surface of the head 1, and the center line is set perpendicular to the thermal paper 3 and the platen 4. Here, the platen hand is usually made of an elastic material such as rubber in order to improve the adhesion between the head 1 and the thermal paper 3. Further, when recording and printing is performed using a head having this vertical dot arrangement, it is customary to energize the heating element 2 while moving the head 1. However, as described above, the head 1 is connected to the thermal paper 3.
The thermal paper 3 and the platen 4 are deformed when they are pressed against the platen 4, so if the head 1 is moved in this state, the point where the contact pressure between the head 1 and the thermal paper 3 is highest will be at the center line. The position is slightly tilted in the direction of movement of the head 1 (the position tilted by θ shown in FIG. 1).

Figure 2 shows the relationship between the inclination angle and the color density when the center line of the head is tilted as described above, plotted in both directions ((G) direction and (H) direction shown in Figure 1). In the case of (G) direction printing, the song MA is the song l1liIB.
(c) shows the case of directional printing.

As is clear from Figure 2, (g) the printing direction (direction in which the head moves to the right) is 10. , (c) 10 for the printing direction (direction in which the head moves to the left). Take the position where the center line of the head is tilted, that is, the center line is θ in the direction of head movement. Maximum color development when tilted at 5 degrees Dnll
&E is obtained.

Therefore, assuming that the center line of the head 1 and the thermal paper 3° platen are kept perpendicular, the color density will be the same whether the printing direction is (G) or (F). Although there is no difference in color density depending on the printing direction,
A color density D0L lower than the maximum color density Dm&d cannot be obtained, resulting in poor thermal efficiency.

Also, the center line is 10. When tilted by
In the printing direction, the color density is Do, resulting in a difference in color density depending on the printing direction.

To solve this problem, the device □ proposed in the patent application ``Sarsal Head'' filed by the present applicant on the same date is effective. This device, as shown in the perspective view in Figure 3,
In a head in which heating elements are arranged in a row on the outer peripheral surface of a cylindrical base formed of an insulator such as glass or ceramic, a common electrode element is provided on the center line of the row of heating elements,
The head is configured such that portions on both sides of the heating element bordering the center line can be individually energized to generate heat.

FIG. 4 shows a sectional view of the head, and in FIGS. 3 and 4, 2□128.・・2n is a heating element, 5 is a common electrode, 6□l” 1!'・・6, □; 62□
.

6□, . . . 6In indicate individual electrodes, and 7 indicates a capture layer. Heat generating element 211u in the figure 2. □ The distance between them is the angle θ shown in Figure 2 above. The decision should be made accordingly. The angle θ. The size of the head is mainly determined by the hardness of the platen, the curved shape of the head, and the pressing force on the platen.The hardness of the platen is small, the curvature of the head is small, or the pressing force of the head is large. Degree θ. needs to be large.

Moreover, FIG. 5 (4), Q3) shows the side electrode 61□ straddling 6. connected to the heating element 2□. This shows the state where electricity is applied between one of the □ and the common electrode, and the heating element 2
The hatched area with □ represents the area in the energized 2 heat generating state, and the white area represents the non-energized and non-heat generating area.

Below, the operation when printing is performed using the head shown in FIG. 3 will be explained based on FIG.
When the center line of the head l and the thermal paper 3° platen are kept perpendicular, printing in the printing direction (g) is done by using the electrode (of the color density characteristics As shown by curve I, printing in the (to) printing direction is performed by an electrode at a position tilted by one θ (coloring density characteristics are shown by curve r), respectively. Both can obtain the color density (points P, Q) of D. Now, considering the case where there is a deviation of △θ in the (g) direction, when printing in the (g) printing direction, the color density (points P, Q) of point R1 (h ) Printing in the printing direction is at point S, that is, the color density is D2.D and R, respectively, but the difference is extremely small and is tolerable in practice.

On the other hand, when using a conventional head, as long as the pressure contact angle is correct, color density is achieved regardless of the printing direction as described above. However, if the pressure contact angle deviates, (g) point T for directional printing, and (c) point U1 for directional printing, that is, the color density becomes D'2°D and R', respectively, and the difference between them is was significantly larger.

As described above, by using the separately proposed head, it is possible to obtain good heat conduction efficiency (color development efficiency) during bidirectional printing, and stable color density against changes in the pressure contact angle of the head.

On the other hand, there is another point of view, that is, as a method of bold printing using the single-row type head, there are methods of overprinting with slightly shifted timing, methods of increasing the dazzling width, or methods of bidirectional printing. There is a method in which overprinting is performed during printing in the return direction.

However, among the above methods, the method that performs printing by shifting the timing has the problem that a position detection mechanism is required and the equipment becomes expensive, and the method of increasing the width of the drawing is not preferable in terms of head durability. There was a problem. Further, in a method in which bidirectional printing is performed and overprinting is performed during printing in the backward direction, there is a problem in that the printing speed is significantly reduced.

The present invention has been made in view of the above circumstances, and its purpose is to solve all the above-mentioned problems of the bold character printing method in conventional thermal printers and to improve the printing speed without reducing the printing speed. The purpose is to provide a bold character printing method.

The above object of the present invention is to provide a bold character printing method for a thermal printer using a head in which heating elements are arranged in a row on the outer peripheral surface of a cylindrical base formed of an insulator such as glass or ceramic. A common electrode element is provided on the center line of the heat generating element row, and the parts on both sides of the heat generating element with the center line as a border are individually energized to generate heat. When printing bold characters, the heat generating element is This is achieved by a bold character printing method that simultaneously generates heat in the area on the image side of the element bordering on the center line.

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

7], and FIG. 8 shows a head drive circuit and its timing circuit of a thermal printer showing an embodiment of the present invention.
In the figure, AND is an AND circuit, 0Ilj
:OR Kaiyu and D indicates the driver. Also, R1□f Rb, Rag in the head 1.

Bill 8. . . . Rant'fLbn respectively indicate the individual portions of the heating elements 21+2B+ . . . divided by the two center lines (see the chain diagram).

As shown in FIG. 7, the signal input corresponding to each dot and the print timing signal (a) l (b) are ANDed,
This output drives the driver D to apply a voltage to the heat generating elements (11, Rb0...Ran, Rbn) in the head 1. A series of pulses is created by a delay circuit that adjusts the timing and a pulse width control circuit that determines the energization time.For normal printing (not bold characters), the printing direction is determined by the AND of the signal indicating the printing direction and the timing pulse. (&) or (b) is generated in a reverse manner. When the bold character printing finger cools, the above (a
) and (b) occur at the same time, bold letters (bold letters)
is printed.

FIG. 9 shows an example of printing bold characters by the apparatus of this embodiment. In Fig. 9, the part indicated by () indicates the dot caused by Ra□ of the heat generating element, and the part indicated by ■ indicates the dot caused by the other side tag of the same heat generating element. A good bold print with a constant width is printed.

As described above, according to the present invention, a bold character printing method for a thermal printer having a thermal head in which heating elements are arranged in a row on the outer peripheral surface of a cylindrical base made of an insulator such as glass or ceramic is provided. The thermal head is configured such that a common electrode element is provided on the center line of the heat generating element array, and parts of the heat generating elements on both sides of the center line can be individually energized to generate heat. When printing characters, the parts on both sides of the center line of the heating element are made to generate heat at the same time, so reducing the printing speed is not a bad idea, and it is possible to print good bold characters. It has a remarkable effect. Moreover, this method has the advantage that it does not cause any particular increase in cost by being used in conjunction with bidirectional printing.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the state of pressure contact between a conventional head, thermal paper, and a platen, FIG. 2 is a diagram showing color density characteristics of the conventional head, and FIG. 3 is a perspective view of a head suitable for implementing the present invention. Fig. 4 is a cross-sectional view of the device, Figs. FIG. 9 is a diagram showing a circuit, and FIG. 9 is a diagram showing an example of printing bold characters by the apparatus of the embodiment. ■=Head, 2, 22...2.・・・2□ : Release 1
1 gl Thermal element, 3: Thermal vapor, 4 Nibraten, δ' Both fnwfIiz 611* 612+...a□, +
a,,l 6@B+...6,. : Individual box 1 pole, 7: Protective layer. 0υ Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 仝(→-Head inclination angle - (g)

Claims (1)

[Claims] In a bold character printing method of a thermal printer having a thermal head in which heating elements are arranged in a row on the outer peripheral surface of a cylindrical base formed of an insulator such as glass or ceramic, the thermal head is connected to the heating element row. A common electrode element is provided on the center line of the heat generating element, and the parts on both sides of the heat generating element bordering the center line are configured to be individually energized and generate heat. A bold character printing method for a thermal printer characterized by simultaneously generating heat on both sides of the center line.