| 摘要 |
<p>The t.v. receiver has a built-in time generator to initiate switching at given times, in e.g. to act as an alarm indicating to the viewer that a set time is at hand. The generator's output is used solely to produce a visible mark on the screen, e.g. spot, square, star, cross etc. a digital representing a channel number, a company's symbol or trade mark, or an extract from another programme. The mark may appear intermittently and at the edge or corner of the picture. The viewer may switch off the opticla signal at any time.</p> |
