| 摘要 |
PURPOSE:To facilitate an easy readout and to secure the safety, by increasing the illuminance on a luminous surface when a minor measurement of a narrow luminous area is displayed, decreasing the illuminance on the luminous surface when a major measurement of a wide luminous area is displayed and accordingly securing nearly a constant level of light volume given from the luminous surface at all times. CONSTITUTION:A rotary plate 4 of a speedometer turns clockwise by a prescribed angle corresponding to the speed of a car when the car is driven at a low speed. Thus a narrow luminous surface 3a is formed (a) in accordance with the speed of the car, and the surface 3a is irradiated by a light emitter via a light transmitting plate. Thus a low-speed state is displayed in terms of the area. In this case, the control is carried out to increase the quantity of conduction of the light emitter, and the illuminance of the surface 3a is maintained high enough to allow a driver to recognize easily the speed of the car. On the other hand, a large luminous surface 3a is formed (b) in accordance with the speed of the car in a high-speed driving mode. The illuminance of the large surface 3a is reduced automatically according to the speed of the car, and the driver can drive the car with safety at all times and without being dazzled by the large luminous surface 3a. |
