| 摘要 |
PURPOSE:To prevent liquid crystal molecules from being heated when it is irradiated with laser beams and avoid the reduction in marking contrast, by additionally providing a heat shielding function in an orientation film which is a component of said liquid crystal element. CONSTITUTION:At the time of marking, linearly-polarized laser beams 2 are projected to a liquid crystal element 1, which are turned to be penetrating laser beams 3 in accordance with the pattern data of a liquid crystal 4. The liquid crystal element 1 is composed of the liquid crystal 4, orientation films 5a, 5b, transparent electrodes 6a, 6b and, glass substrates 7a, 7b which hold all these components. The orientation films 5a, 5b are generally formed of organic polyimide, the thermal characteristic of which is not greatly different from that of the liquid crystal 4. For example, when the thickness of the orientation film 5a, 5b is 1mum, the maximum temperature of the liquid crystal 4 is 50 deg.C, whereas, when the thickness of the orientation film 5a, 5b is 0.09mum, the maximum temperature of the liquid crystal 4 is 62 deg.C which exceeds the operating limit of a liquid crystal 60 deg.C. As a result, although the printing efficiency is not changed at all in the former case, the contrast is deteriorated in the latter case. In other words, if the thickness of the orientation films 5a, 5b is made larger, the films can serve as a heat shielding layer. |
