| 摘要 |
In one aspect of the invention for which protection is sought there is provided reader apparatus for reading an identification code carried by a surface feature device, the surface feature device having a plurality of respective surface feature portions each provided at respective lateral locations over a lateral surface at one of a plurality of predetermined distances from a lateral reference plane, the apparatus comprising a light source and a light detector, the apparatus being configured to direct light from the light source onto the respective surface feature portions of the surface feature device and to detect by means of the detector light scattered by the respective surface feature portions, the detector being configured to output a detector signal indicative of the intensity of light incident thereon, the apparatus being configured to generate a reader signal responsive to the distance of each of the respective surface feature portions of the surface feature device from the reference plane in dependence on the detector signal. |
