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• Ligne n°12 : There is disclosed a high-voltage power supply device capable of high precise control with a simplified circuitry and with a reduced energy loss in which a high-voltage transformer is controlled by switching means which is driven by a power source including a negative power supply and operated in response to pulse signals.
• Ligne n°30 : Still another object of the present invention is to provide a power supply device in which a flyback transformer is driven with a negative power source.
• Ligne n°40 : FIG. 2 shows the circuit structure of an embodiment of the power supply device of the present invention, wherein shown are an oscillating circuit 11; a level-shifting Zener diode ZD1 connected with the output side of said oscillating circuit 11 for shifting the reference voltage from 0 V to -5 V; a driving circuit 12 connected with the anode of the Zener diode ZD1 and with the primary coil of a flyback transformer T1 for driving the same; a high-voltage output circuit 13 connected with a first secondary coil (hereinafter called the second coil) of said flyback transformer T1 for supplying an unrepresented load with an output high voltage; a positive voltage supply circuit 14 connected with a second secondary coil (hereinafter called third coil) of said flyback transformer T1 for generating a positive rectified voltage of +5 V for supply to said driving circuit 12; and a negative power source circuit 15 connected with a third secondary coil (hereinafter called fourth coil) of said
• Ligne n°75 : * Power source unit Cam follower with roller
• Ligne n°89 : An NPN transistor Tr4 for driving the flyback transformer, called the switching transistor, is connected, through the base thereof and the resistor R7, to the junction point between the collectors of the transistors Tr2, Tr4, is connected further at the collector to an end of the primary coil (hereinafter called first coil) of the flyback transformer T1, and is grounded at the emitter. The condenser C1 and the diode D2 are connected in parallel manner between said collector and emitter. The primary coil of the flyback transformer T1 receives, at the other end thereof, the primary power source voltage of +24 V.
• Ligne n°90 : In the high-voltage output circuit 13, a diode D3 is connected in a forward direction to an end of the high-voltage second coil of the flyback transformer T1, and a condenser C2 and a resistor R9 are connected in parallel manner between the cathode of said diode D3 and the other grounded end of said second coil to obtain an output high voltage from said cathode of the diode D3. In the positive power source circuit 14, diodes D4, D5 are serially connected in a forward direction to an end of the third coil of the flyback transformer Tr1, and a condenser C3 is connected between the junction point of said diodes D4, D5 and the other grounded end of said third coil to obtain the positive rectified voltage of +5 V from the cathode of said diode D5. In the negative power source circuit 15, a diode D6 is connected in an inverse direction to an end of the fourth coil of the flyback transformer T1 and a condenser C4 is connected between the anode of said diode D6 and the other grounded end
• Ligne n°93 : At the start of power supply, the voltages of +5 V and -5 V are not present since the third and fourth coils do not generate any voltages. Thus, upon entry of a pulse signal from the oscillating circuit 11 as shown in FIG. 3A, a current is supplied to the base of the transistor Tr4 from the power source of +24 V through the resistor R8, transistor Tr2 and resistor R7 to activate the transformer T1. Upon said activation the third and fourth coils respectively generate voltages of +5 V and -5 V, which thereafter principally govern the base drive of the transistor Tr4. More specifically the conductive state of the transistor Tr4 is attained by a current supply of +5 V to the base thereof through the transistor Tr2 and the resistor R7, and the nonconductive state of the transistor Tr4 is attained rapidly by inverse current supply to the base thereof through the transistor Tr3 and the resistor R7.
• Ligne n°94 : Thus, when the transistor Tr1 is turned on, the transistors Tr2 and Tr3 are respectively turned on and off to supply a current from the positive power source of +5 V through the transistor Tr2 and the resistor R7 to the base of the transistor Tr4, thus turning on the same (cf. FIG. 3B and 3C.). On the other hand, when the transistor Tr1 is turned off, the transistors Tr2 and Tr3 are respectively turned off and on to turn off the transistor Tr4 rapidly by the current supply from the negative power source of -5 V to the base of said transistor Tr4 (cf. FIGS. 3B and 3C).
• Ligne n°96 : In the foregoing embodiment the power sources of +5 V and -5 V are generated at the second side of the flyback transformer, but there may naturally employed any other available voltage sources.
• Ligne n°98 : As explained in the foregoing, the switching transistor for driving the flyback transformer is driven by a negative voltage source to provide the advantages of: