在农村中小学及经济欠发达地区学校,投影仪至今仍是应用最为普遍、使用频率最高的电教设备。据调查,这一使用最为普遍的设备,故障率及闲置率占所有电教设备之首。其主要原因是投影仪较频繁地烧灯泡,而且绝大多数灯泡是在开机瞬间烧毁。虽然一只灯泡仅十来元,但对于大多数经济条件不很宽裕的学校,长年累月的支出也是一 In rural primary and secondary schools and schools in economically underdeveloped regions, projectors are still the most commonly used and most frequently used audio-visual equipment. According to the survey, the most commonly used equipment, failure rate and idle rate accounted for the first of all audio-visual equipment. The main reason is that projectors burn light bulbs more frequently, and the vast majority of light bulbs are burnt out at the moment of starting up. Although a light bulb is only a few dollars, but for most of the economic conditions are not well-off schools, spending for many years is also a