一、发展概况 第二次世界大战以来,飞机性能有了显著的提高,但是座舱仪表的布局无根本性变化,主仪表板仍装在驾驶员的下视场内。这种布局有在一些实际缺点,首先驾驶员不能同时看到外界环境和仪表指示的情况,必须不断变换视线方向,进行交替观察才能看到。当驾驶员观察座舱外的环境时,眼球焦距要调节至无穷远,当要观察下视场中的仪表极时就必须重新调节焦 First, the development overview Since the Second World War, the aircraft performance has been significantly improved, but there is no fundamental change in the layout of the cockpit instrument, the main dashboard is still installed in the driver's field of view. This layout has some practical shortcomings. Firstly, the driver can not see the external environment and the indication of the instrument at the same time. The driver must constantly change the direction of the line of sight and observe alternately. When the driver observes the environment outside the cockpit, the focal length of the eye needs to be adjusted to infinity, and the focus must be readjusted when observing the instrument pole in the field of view