Light-induced luminous keyboard

摘要

A light-induced luminous keyboard includes a keyboard main part, a power supply, and a first circuit, a second circuit and a third circuit parallel to each other. The above circuits include two transistors and a negative coefficient photoresistor. While being played in a decreasing light intensity environment, the light-induced luminous keyboard has an increased resistance of a negative coefficient photoresistor and thus an increased voltage is divided for the negative coefficient photoresistor, the point that the base of the first transistor is connected with the first circuit is in a high level, thus the first transistor is available, the point that the base of the second transistor is connected with the second circuit is drawn down to zero volt, the second transistor is available, the luminous apparatus is turned on and the keyboard illuminates. Therefore, automatic illumination of the keyboard is implemented dependent on environmental light intensity.

主权项

1. A light-induced luminous keyboard, comprising:
a keyboard main part; a power supply provided on the keyboard main part; and a first circuit, a second circuit and a third circuit parallel to each other, which are connected and communicated with the power supply; wherein the first circuit comprises a first resistor connected with the power supply and a negative coefficient photoresistor in series with the first resistor; the second circuit comprises a second resistor and a first transistor in series with the second resistor, wherein the second resistor is connected with a collector of the first transistor, and a base of the first transistor is connected with the first circuit with a connection point between the first resistor and the negative coefficient photoresistor; the third circuit comprises a second transistor and a luminous apparatus in series with the second transistor, wherein the second transistor has an emitter connected with the power supply and a base connected with the second circuit with a connection point between the collector of the first transistor and the second resistor, and the luminous apparatus is connected with the collector of the second transistor; a fourth circuit comprising a third transistor which has an emitter connected with the power supply, a collector connected with the third circuit with a connection point between the luminous apparatus and the collector of the second transistor, and a base connected with a manual switch.