| 摘要 |
The economic production of raised print characters such as Braille is achieved by a silk screen printing process, using a rotational printing machine in combination with high viscosity, "U/V" inks that make possible the depth of deposition and character solidity necessary for achieving the required tactile effect in order to be "readable" by touch. The high body ink of the thus formed characters is cured rapidly by exposure to U/V light, so that the high drying rate thus obtained enables the achievement of economically effective, high rates of production. It is found that raised patterns of significantly lesser prominence than for embossed Braille, as produced by the printing process, are more durable, being substantially less crushable than an embossed Braille product, and are readable on a short-term basis, even by trainee "readers". The desired "point " value of height of the superimposed characters is achieved by build-up of the screen thickness, by way of additional layers of the high viscosity coating emulsion through which is etched the passages that the printing ink passes through. |
