Holding current circuit of LED driving apparatus and operating method thereof

摘要

An electromagnetic touch-control screen structure, comprising: a display panel; a touch-control plate over the display panel; an electromagnetic induction plate over the touch-control plate; and a cover lens attached on the electromagnetic induction plate. The electromagnetic touch-control screen of the disclosure, by deploying reasonable structure and manufacturing technique, stacks an electromagnetic induction plate with a touch-control plate, a cover lens and a display panel. Compared with existing manufacturing techniques, it can reduce one time of lamination operation, and dramatically decrease the thickness and weight of the electromagnetic structure, so that it can meet the need of lightness and thinness, for touch-control display equipments, like cellphone.

主权项

1. A holding current circuit of a LED driving apparatus, comprising:
an input terminal, for receiving an input voltage; a holding resistor, coupled to the input terminal, a holding current flowing through the holding resistor; a transistor, coupled between the holding resistor and a ground terminal; a comparator comprising a first input terminal, a second input terminal, and an output terminal, wherein the output terminal is coupled to a gate of the transistor; a regulator, coupled between the ground terminal and the first input terminal of the comparator; a first resistor, coupled to a LED string; and a second resistor, coupled between the first resistor and the ground terminal; wherein the second input terminal of the comparator is coupled between the first resistor and second resistor, the comparator receives a first voltage and a second voltage through the first input terminal and the second input terminal respectively and judges whether the second voltage is larger than the first voltage, if the judged result of the comparator is yes, the comparator outputs a control signal to turn off the transistor to prevent the holding current from passing through the transistor.