| 摘要 |
In an image card where an image is formed on a thin plate made of special synthetic paper or plastic by engraving by sweeping the plate with the engraving needle through relative movement of an engraving needle and a plate, it is impossible to form a hidden image which can be viewed when a viewpoint is changed or form an image formed by watermark engraving and the hidden image within the same plane. A hidden image is formed on an image card by engraving while angles of stripes of striped patterns are changed in response to shading of an image. Further, an image engraving device is provided with a rotary driving unit, and engraving is performed in a state that an extending direction of striped grooves of the hidden image and a forming direction of the engraving are made equal, so that a wall face of a groove is always formed by the same side face of an engraving needle and undulation does not occur on the wall face of the groove. Similarly, a shape of a bottom face of the groove is made even. As a result, precision of the hidden image is made high and an effect as the hidden image is further improved. |
