| 摘要 |
PURPOSE:To sense the brightness of the circumference and to automatically switch the brightness of a LED, etc., in the daytime and at night by outputting the maximum current when a light receiving element is turned on, and also, outputting a current in accordance with an external operation when it is turned off. CONSTITUTION:In the daytime, a large amount of solar light is made incident on the light receiving element 6, which turns on the light receiving element 6, and the maximum current is supplied from a current control means 30 to light emitting means 54-56, therefore, the light emitting element can be lit with the maximum luminance. Meanwhile, when the brightness of the circumference goes to the one less than a constant level, incident light quantity to the light receiving element 6 is reduced, which turns off the light receiving element 6, and the current in accordance with a variable resistor value 25 is supplied from the current control means 30 to the light emitting elements 54-56, thereby, the light emitting elements 54-56 can be lit corresponding to the current, and also, the switching with the luminance of the light emitting elements 54-56 in the daytime and a time other than the daytime (at night) can be automatically performed. Thereby, it is possible to adjust the luminance of an alarm lamp by an operator at night corresponding to the liking of the operator, and also, to automatically lighten the lamp with the maximum luminance in the daytime. |
