JPH03258558A - Printing head - Google Patents

Abstract

PURPOSE:To permit a clear printing at a uniform printing density by a method wherein a heat resisting layer is given such a wavy form that it is high and low alternately according to the corresponding layer thickness of a common electrode and a signal electrode, respectively. CONSTITUTION:Since heat resisting layers 13 located in the corresponding positions of common electrodes 12 are made high and since said layers 13 located in the corresponding positions of signal electrodes 11 are made lower, at the time of heat-sensitive printing with a heat-sensitive paper 21 placed on the heat resisting layer 13, the heat- sensitive paper 21 comes in contact with only a high part 19 of each of said layers 13 located in the corresponding positions of the common electrodes 12, being out of contact with the other parts thereof. Because of this, the places at which said layers 13 make contact with the heat-sensitive paper 21 are reduced in number and the adhesiveness of the paper 21 thereto is improved. Also, since a space between their contacting places become large, a space between dots can be made narrower to some extent.m Since, in this way, the heat-sensitive paper 21 can be closely attached to the heat resisting layers 13, even if the dot space is narrow, an uneven printing is avoided at the time of printing, the printing density is uniform and a clear printing can be effected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in printing devices such as printers [Prior Art] Conventionally, as a print head used in printers etc., for example, a heat-sensitive printhead as shown in FIG. type of thermal print head is known. This type of print head has a large number of signal electrodes 2 and common electrodes 3 made of metal layers formed in parallel on an insulating substrate 1 alternately at predetermined intervals, and is arranged over the entire area of the signal electrodes 2 and common electrodes 3 in the arrangement direction. It has a structure in which a heating resistor M4 is formed by printing conductive ink in a band-like manner. In this print head, the portion of the heating resistor layer 4 located between one signal electrode 2 and two adjacent common electrodes 3.3 becomes a heating portion 5, and these two heating portions 5.5 are used for printing. Sometimes it generates heat and prints as a single dot. Note that this print head is made of inexpensive materials, does not require high precision in manufacturing, and has good productivity.

[Problems to be Solved by the Invention] In the print head described above, as shown in FIG. 4, the signal electrode 2 and the common electrode 3 formed on the insulating substrate l have the same layer thickness, and moreover, are printed with approximately the same layer thickness, so the heat generating resistor layer 4 located above each electrode 2.3 is formed on a high portion 6, and the heat generating resistor layer 4 located between each electrode 2.3 is formed at a high height 6. 4 is formed at a low bottom portion 7, and this bottom portion 7 serves as a heat generating portion 5.

Therefore, when performing thermal printing by disposing thermal paper 8 or the like on the heat generating resistor layer 4, the thermal paper 8 must be brought into contact with three high parts 6 of the heat generating resistor layer 4 for one dot. . For example, in one dot, even if the thermal paper 8 comes into contact with two places, the high part 6a corresponding to the signal electrode 2 and the high part 6b corresponding to the common electrode 3 on the right side, it will not correspond to the common electrode 3 on the left side. If the thermal paper 8 is not in contact with the high part 6c, the printing density will be different between the heat generating part 5 on the right side and the heat generating part 5 on the left side, and printing unevenness will occur within one dot.

Such a problem is caused by the high temperature of the heating resistance layer 4 @B6a, 6b,
This is caused by the adhesion of the thermal paper 8 to the paper 6c. Therefore, if the distance between the dots is wide, the height of the heating resistor layer 4 is
Since the spacing between the dots becomes wider, it can be absorbed to some extent by the printing pressure of the print head, but as the spacing between the dots becomes narrower, the spacing between the high parts 7 of the heating resistor layer 4 also becomes narrower.
There is a problem that printing unevenness tends to occur, and it becomes impossible to print clearly and with uniform print density.

An object of the present invention is to provide a print head that can maintain good adhesion of thermal paper, etc. to a heating resistor layer even if the dot spacing becomes narrow, prevent uneven printing, and provide clear printing with uniform print density. That's true.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention forms one side of the signal electrode and the common electrode provided on an insulating substrate thinner than the other side, and each electrode The height of the upper heating resistor layer is formed so that one side is lower than the other side depending on the layer thickness of each electrode.

[Function] According to the present invention, the height of the heating resistor layer is formed so that one side is lower than the other side depending on the layer thickness of the signal electrode and the common electrode. It is possible to reduce the number of contact points, such as, and increase the distance between the contact points. Therefore, even if the dot spacing becomes narrow, the adhesion of thermal paper, etc. to the heating resistor layer is improved, which prevents uneven printing and enables clear printing with uniform print density. becomes.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

1 and 2 show the print head. This print head is used, for example, in a printer such as a facsimile machine and is capable of line printing. As shown in FIG. 2, in this print head, signal electrodes 11 and common electrodes 12 are formed in parallel on an insulating substrate 10 in an alternating manner, and are formed on each signal electrode 11 and common electrode 12 along the direction in which they are arranged. The heat generating resistor layer 13 is formed in a band shape. Note that each electrode 11.12 is covered with an insulating protective film (not shown), and a driving IC chip (not shown) is connected to each electrode 11.12.

The insulating substrate 1O is made of a heat-resistant resin plate such as polyester, polyimide, bismaleimide triazine, etc., or a resin film, and is formed into an elongated rectangular shape. As shown in FIG. 1, the signal electrode 11 and the common electrode 12 have a two-layer structure in which a plating layer 16.17 is laminated on a metal thin film layer 14.15. It is formed thinner than the That is, a metal thin film layer 14.15 made of copper or the like is deposited to the same thickness on the upper surface of the insulating substrate 1O by vacuum evaporation or sputtering, and then this metal thin film layer 14.15 is patterned using photolithography technology. The metal thin film layer 14 of the signal electrode 11 is formed to be thinner than the metal thin film layer 15 of the common electrode 12. Thereafter, a plating layer 16.17 is applied to each metal thin film layer 14.15 by electrolytic plating. At this time, the metal thin film layers 14 and 15 of the signal electrode 11 and the common electrode 15 have different sizes, and electrolytic plating is performed with a difference in current density between the two.

Therefore, a plating layer 16 is thinly formed on the metal thin film layer 14 of the signal electrode 11, and a plating layer 16 is formed thinly on the metal thin film layer 14 of the common electrode 12.
A thick plating layer 17 is formed thereon. The plating layers 16 and 17 preferably have a plurality of plating layers of copper, nickel, gold, etc., but may have a single layer structure. Further, as shown in FIG. 2, a large number of signal electrodes 11 and common electrodes 12 are alternately arranged in parallel at predetermined intervals (for example, intervals of about 16 dots/mm) over the entire width direction of the insulating substrate 10, and each The tip portions 11a and 12a are formed by biting into each other alternately. The biting length L of each tip portion 11a, 12a determines the size of the heat generating portion 18, which will be described later. Therefore, the tip edges of each of the tip portions 11a and 12a are formed on two straight lines, and the biting lengths L of the tip portions 11a and 12a are all uniform.

The heat generating resistor layer 13 is made of conductive ink such as carbon ink, and is formed in a band shape over the entire area in the arrangement direction at each tip portion 11a, 12aJ- of the signal electrode 11 and common electrode 12 by printing, roll coating, etc. There is. In this case, as shown in FIG. 2, the heating resistance layer 13 has a width W of each electrode 11.
It is formed to be larger than the biting length L of the tip portions 11a, 12a of No. 12, and is provided to completely cover each tip portion 11a, 12a. Therefore, this heating resistance layer 13
Now, let's take a look at the heat-generating part 1 where current actually flows during printing and generates heat.
Reference numeral 8 denotes a portion shown by mesh lines in FIG. 2, that is, a portion where the tip portion 11a of one signal electrode 11 and the tip portions 12a, 12a of two adjacent common electrodes 12.12 face each other; Other parts do not generate heat. What is important here is that since the conductive ink is applied with a substantially uniform thickness, the heating resistor layer 13 is formed in the high part 19 where the common electrode 12 is highly protruding, as shown in FIG. , the signal electrode 11 is formed in the lower part 20 which is lower than this. Note that the heat generating portion 18 between each electrode 11, 12 is formed lower than the lower portion 2o. This is because when the thermal paper 21 is placed on and brought into contact with the heat generating resistance layer 13,
This is because, in one dot, the thermal paper 21 is brought into contact only with the high parts 19, 19 of the heat generating resistor layer 13 corresponding to the common electrodes 12 on both sides, and the heat sensitive paper 21 is not brought into contact with any other part of the heat generating resistor layer 13. be. This structure is extremely effective in improving the adhesion of the thermal paper 21 to the heating resistance layer 13.

Therefore, in the above-described print head, the heat generating resistor layer 13 at the location corresponding to the common electrode 12 is formed higher, and the heat generating resistor layer 13 at the location corresponding to the signal electrode 11 is formed lower than this, so that the heat generating resistor layer 13 is formed at a lower height than this. When thermal printing is performed by disposing thermal paper 19 on layer 3, thermal paper 21 contacts only each high portion 19 of heating resistor layer 13 corresponding to each common electrode 12, and contacts other portions of heating resistor layer 13. Do not come into contact with. Therefore, the number of contact points of the heat-generating resistor layer 13 with the heat-sensitive paper 21 is reduced, and the adhesion of the heat-sensitive paper 21 with the heat-generating resistor layer 13 is improved. Considering this for one dot, the lower part 2o of the heat generating resistor layer 13 at the location corresponding to the signal electrode 11 is the high part 19. Since it is lower than 19,
Since the thermal paper 21 does not come into contact with the lower part 20 of the heat generating resistance layer 13, the number of contact points with the thermal paper 21 is reduced, which improves adhesion. It can be narrowed to some extent. Even if the dot spacing becomes narrow in this way, the thermal paper 21 can be brought into good contact with the heating resistor layer 13, so that uneven printing does not occur during printing, the printing density is uniform, and clear printing is performed. I can do it.

Note that this invention is not limited to the embodiments described above.

For example, the layer thickness of the common electrode 12 may be formed thinner than that of the signal electrode 11, and the heating resistance layer 13 on the common electrode 11 side may be formed lower than the heating resistance layer 13 on the signal electrode 12 side. In this case, in one dot, the part that the thermal paper 21 comes into contact with is the one part corresponding to the signal electrode 11, so
Adhesion becomes even better. In addition, each electrode 11.12
If the number of printed dots is about 8 dots) / mm, then after laminating a metal foil such as copper on an insulating substrate lO and etching it to pattern each electrode 11 and 12, one of the electrodes should be further half-shaped. By etching,
The layer thickness may be changed. Furthermore, the signal electrode 11 and the common electrode 12 are not necessarily connected to each tip @ 11 a, 1
It is not necessary that the electrodes 2a are alternately formed in parallel, but two tips 12a of each common electrode 12 may be arranged in parallel on both sides of the tip 11a of one signal electrode 11.

In addition, the insulating substrate 10 is not limited to a resin film, but can also be made of glass,
A substrate made of quartz, ceramic, etc. may also be used. In this case, an insulating layer may be formed on the substrate using an organic material such as polyimide resin or an inorganic material such as 5i02, and the electrodes 11 and 12 and the heating resistor layer 13 may be provided on this insulating layer.

Further, the heating resistance layer 13 does not necessarily have to be a conductive ink, but may be made of a high-resistance material such as a silicide-based material or a tartan-based material, or a polycrystalline silicon layer doped with an impurity.

Furthermore, the print head of the present invention is not limited to the above-mentioned heat-sensitive thermal printer, but can also be used as a print head for bubble generation in a bubble-type inkjet printer.

[Effects of the Invention] As described above in detail, according to the present invention, the layer thickness on one side of the signal electrode and the common electrode provided on the insulating substrate is formed thinner than on the other side, and the layer thickness on each electrode is formed thinner than on the other side. Since the height of the heating resistor layer was formed so that one side was lower than the other side in accordance with the layer thickness of each electrode, in one dot,
The number of contact points of the thermal paper, etc. can be reduced, and the distance between the contact points can be widened. Therefore, even if the distance between the drums becomes narrow, the adhesion of the thermal paper, etc. to the heating resistance layer is improved. This prevents uneven printing and enables clear printing with uniform printing density.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of the main parts of the print head of the present invention, and FIG.
3 is a plan view of the main part of a print head, FIG. 3 is a plan view of the main part of a conventional print head, and FIG. 4 is an enlarged sectional view of FIG. 3. lO...Insulating substrate, 11...Signal electrode, 12...Common electrode, 13...Heating resistance layer, 18...Heating part , 19...high part, 20...low part.

Claims (1)

[Claims] A signal electrode and a common electrode are appropriately formed in parallel on an insulating substrate, and a heating resistance layer is provided on the signal electrode and the common electrode over the entire area in the arrangement direction, so that the signal electrode and the common electrode face each other. In a print head in which a heat generating resistor layer at a location generates heat, one side of the signal electrode or the common electrode is formed thinner than the other side, and the height of the heat generating resistor layer on each electrode is set to be equal to the height of the heat generating resistor layer on each electrode. A print head characterized by having one side formed at a lower height than the other side depending on the layer thickness of the electrodes.