| 摘要 |
PURPOSE: To set the peak current flowing through the light emitting element of the photocoupler and the holding current independent of each other by the use of a simple circuit constitution in a data transmission device which performs data transmission between two equipments by means of the photocoupler. CONSTITUTION: A receiving equipment 4 is provided with a photocoupler 10, and a transmitting equipment 2 connects and disconnects the path for energization of a light emitting diode Df of the photocoupler 10 in response to the transmit data. Thus the data are transmitted. The speed-up capacitors C1 and C2 are connected in parallel to the holding current limit resistors R1 and RB which are provided on the path for energization of the diode Df. So that a sudden rise is secured for the current (i) when the energization is started. Then a resistor RA is connected in series to the capacitor C2. Therefore, it is possible to set the peak current generated at the start of energization of the diode Df independently of the holding current by controlling the resistance value of the register RA. |
