We developed a prototype PhantomParasol with the above concepts. The prototype system consists of a gyro sensor for detecting the rotation speed, LED arrays to display ambient and detailed information, and microcontrollers to control these devices (Fig. 3).
We attached eight LED arrays on the ribs with forty-five degree intervals. Each LED array consists of fifty-two LEDs and four demultiplexers1. We put a 1-axis gyro sensor2 on the handle of the parasol, and the output of the sensor is connected to the microcontroller through a 10-bit A/D converter. We attached microcontrollers3 on the ribs beside the LED arrays. Adjacent microcontrollers are connected serially, and exchange messages with each other. In addition, one of the microcontrollers (a host microcontroller) receives data from the gyro sensor, and exchanges commands (e.g. rewriting contents) with a host PC or a PDA via RS232C interface.
Fig. 4 shows a simple usage of the prototype system. When a user holds the PhantomParasol still, it presents ambient information with two LED arrays, just like the LED level meter of audio devices. If the user rotates the parasol, it presents weather forecast icons with all flashing LED arrays.