CONSTANT VOLTAGE POWER SUPPLY CIRCUIT

• US 20080122411A1
• Filed: 01/25/2008
• Published: 05/29/2008
• Est. Priority Date: 10/22/2004
• Status: Abandoned Application

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nishida, Junji
• Application Number:
  US12/020,258
• Publication Number:
  US 20080122411A1
• Time in Patent Office: Days
• US Class Current: 323/225
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output

Abstract

A disclosed constant voltage power supply circuit (1) has an input terminal (Vdd), an output terminal (Vout), a constant voltage power supply unit (2) that generates a constant voltage (Vo1) with a ripple voltage (Vri), and a ripple removing circuit unit (3) for removing the ripple voltage so that a constant voltage (V1) without the ripple voltage is output at the output terminal (OUT). The ripple removing circuit unit comprises a resistor (R1) connected between the constant voltage power supply unit and the output terminal; a ripple voltage detection circuit unit (5) for detecting the ripple voltage and outputting a signal depending on the detected ripple voltage; and a current circuit unit (6, 7) for receiving the signal from the ripple voltage detection circuit unit and supplying a current (io1) to the output terminal or absorbing a current (io2) from the resistor in response to the received signal, so as to cancel the ripple voltage at the output terminal.

Claims

1-8. -8. (canceled)

9. A constant voltage power supply circuit comprising:

a constant voltage power supply unit configured to generates a constant voltage; and

a ripple removing circuit unit for removing a ripple voltage in said constant voltage generated by said a constant voltage power supply unit, so that an output voltage without the ripple voltage is output at an output terminal.

10. The constant voltage power supply circuit of claim 9, wherein the ripple removing circuit unit includes

a resistor connected between the constant voltage power supply unit and the output terminal;

a ripple voltage detection circuit unit for detecting the ripple voltage and outputting an output signal depending on the detected ripple voltage; and

a current circuit unit configured to receive said output signal from the ripple voltage detection circuit unit and supplying a current to the output terminal in response to the received signal.

11. The constant voltage power supply circuit of claim 10, wherein the current supplied to the output terminal cancels the ripple voltage at the output terminal.

12. The constant voltage power supply circuit of claim 9, wherein the ripple removing circuit unit includes

a resistor connected between the constant voltage power supply unit and the output terminal;

a ripple voltage detection circuit unit for detecting the ripple voltage and outputting an output signal depending on the detected ripple voltage; and

a current circuit unit configured to receive said output signal from the ripple voltage detection circuit unit and absorb a current from the resistor in response to the received signal.