| 摘要 |
The ventilation device (10) comprises a first plate (11) having a first set of apertures (16), and a second plate (21) having a second set of apertures (26) separated by cover portions (27). The first and second plates are slidable with respect to each other. The cover portions (27) have dimensions differing from the dimensions of the first set of apertures (16). Furthermore, the dimensions of the cover portions vary along said first direction (x) and/or in a second direction (y) perpendicular to the first direction to provide a visual indication of the degree of ventilation area achieved.
|
