Printing – Intaglio – Processes
Reexamination Certificate
1998-02-23
2002-06-18
Yan, Ren (Department: 2854)
Printing
Intaglio
Processes
Reexamination Certificate
active
06405648
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an intaglio printing method, in particular, an intaglio printing method suitable for the formation of spacers for use in a touch panel, an intaglio printer for carrying out the intaglio printing method, and also a touch panel.
2. Discussion of Background
Currently employed touch panels are electrostatic touch panels, optical touch panels, and resistance-type touch panels. Of these touch panels, resistance-type touch panels are most in general use.
A resistance-type touch panel is constructed of a pair of transparent panels or sheets which face each other, provided with a transparent electrode layer such as an ITO layer on the facing side of each panel or sheet. Thus, the touch panel is composed of a pair of such transparent panels or sheets. However, when such a touch panel is used by superimposing the same on a liquid crystal display or a CRT display, a panel made of glass is usually used as the lower panel, and a panel made of a polycarbonate or PET film with a thickness of hundred several tens microns is usually used as the upper panel since it is usually necessary that the upper panel be flexible and be brought into close contact with the lower panel when the upper panel is depressed. The upper most surface of the upper panel made of such a polycarbonate film or a PET film with which is depressed with the fingers or pens is usually coated with a hard coat layer to impart durability to the upper panel.
Coating patterns of transparent electrodes such as ITO electrodes can be roughly classified into two types, a digital type and an analog type.
In the digital type transparent electrodes, long narrow transparent electrodes, divided in the shape of stripes, with the formation of slits therebetween, are formed crosswise on the upper and lower panels, so that when the upper panel is depressed and the transparent electrodes in the upper and lower panels are electrically connected, the connected point or position is detected as a positional data in a horizontal direction and a vertical direction. In the transparent electrodes of the above-mentioned digital type, the position can be identified by detecting the ON/OFF of the stripe-shaped, crosswise disposed transparent electrodes, so that the detection can be performed with high accuracy since no detection error is caused by variations in the value of the resistance of the transparent electrodes, which may be caused by non-uniform coating of the electrodes. However, it is necessary that the transparent electrodes be divided and insulated in the shape of stripes by the formation of a masking resist by photolithography and an etching treatment. Thus, the production cost of the thus divided electrodes is high. Furthermore, the resolution of the electrodes is limited by the degree of the division of the electrodes, so that the digital type transparent electrodes have the shortcoming that the digital type electrodes are not suitable for precise positional detection.
In contrast, in the analog type transparent electrodes, which are recently widely used, the electrodes are not divided, but are continuous in the entire surfaces on the panels. In the transparent electrodes of the analog type, electric current flows in one direction, for instance, in a horizontal direction, through the electrode on a first panel, while in the electrode on a second panel, electric current flows in a direction vertical to the current flow direction in the electrode of the first panel. The upper and lower transparent electrodes are electrically connected by an electroconductive pads at the upper and lower end portions or the left and right end portions of the two electrodes.
When one point of a touch panel comprising the above-mentioned analog type transparent electrodes is depressed, a resistance is determined in proportional to the distance between the depressed point and the position of the pad which may be at the upper or lower end portion, or at the left or right end portion of the electrode. Based on a calculation of the thus determined resistance, the coordinates of the position can be calculated. In comparison with the digital type transparent electrodes, the analog type transparent electrodes, for which slit-shaped division of the electrodes are unnecessary, are capable of detecting the position more precisely. However, in the analog type transparent electrodes, if non-uniformity of the thickness of the coating of the electrodes is large, the precision of the positional detection is significantly lowered, so that a highly accurate control technique is required, for instance, for the vacuum deposition of ITO for the fabrication of the analog type transparent electrodes.
If the coating thickness of the electrodes varies, the actually depressed position differs from the calculated position. Even if any of the electrodes includes one portion in which the coating thickness of the electrode is not uniform, the accuracy of the positional detection is lowered in all the positions in the direction of the flow of the current, so that if there is a plurality of portions in which the coating thickness of the electrode is not uniform, all of the errors in the course from the pad to the contact point accumulate, the accuracy of the positional detection is worsened.
Recently, a hybrid type touch panel has been proposed, in which the advantage of the digital type electrodes that the production thereof is easy, and the advantage of the analog type electrodes that highly precise positional detection can be carried out are combined. In the hybrid type touch panel, the touch panel is divided into relatively large sections with slits being formed therebetween like digital type transparent electrodes, and within each section, analog positional detection is carried out, so that while the high accuracy of the positional detection is maintained in each section, the accumulation of the errors caused by the non-uniformity of the resistance beyond the sections is avoided. By this hybrid type touch panel, the accuracy of the positional detection is significantly improved, but the hybrid type touch panel has the shortcoming that the production-cost thereof is extremely high.
In pursuing high precision in the positional detection, the positional detection systems have been changed as mentioned above. One of the most important elements that have significant effects on the cost and the accuracy of the positional detection in such detection systems is a spacer.
The spacer in the touch panel has the function that when the touch panel is not depressed, a predetermined space is maintained between the upper and lower transparent electrodes to avoid unnecessary connection of the two electrodes, while when the touch panel is depressed, the connection of the two electrodes is easily allowed, but the connected area is limited to a proper area.
The touch panel is required to be transparent because in many cases, the touch panel is used on a liquid crystal display or a CRT display. As a matter of course, the spacer for use in the touch panel is also required to be transparent. Therefore, as the material for the space, transparent resins are usually used. Furthermore, in order to improve the security and precision of the detection, and to make the spacer invisible to the eyes, it is required to make the spacer as small as possible in size.
There are two methods for producing the spacer, a printing method and a photolithographic method.
In the printing method, round holes are made in a stainless plate by etching, or round holes are made in a nickel plate by electroforming. By use of the thus produced stainless plate or nickel plate with round holes as a printing mask, for instance, an ultraviolet-curing resin is printed on a panel serving as a print receiving material, whereby a spacer is produced. As the printing masks used in such a printing method, such an etching mask and an additive mask made by electroforming can be employed. Each mask has its own advantages and disadvantages.
The production cost of the ab
Ricoh Microelectronics Co. Ltd.
Yan Ren
LandOfFree
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