High voltage stabilizing circuit

• US 6,341,075 B2
• Filed: 02/01/2001
• Issued: 01/22/2002
• Est. Priority Date: 02/03/2000
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yasumura, Masayuki
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/773,801
• Publication Number:
  US 20010019491A1
• Time in Patent Office: 355 Days
• Field of Search: 363/21.01, 363/21.02, 363/21.04, 363/21.12, 363/21.15, 363/21.18, 363/95, 363/97, 363/131
• US Class Current: 363/21.02
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/3385 with automatic control of output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A high voltage stabilizing circuit according to the present invention has a voltage resonance type converter as a switching converter that performs switching operation using direct-current input voltage obtained from commercial alternating-current power, and switching output of the voltage resonance type converter is directly transmitted to a primary winding of a flyback transformer FBT (high voltage output transformer). Then, a rectifier circuit for high voltage connected on the secondary side of the flyback transformer FBT provides high direct-current voltage as an anode voltage for a CRT, for example. The high direct-current voltage is stabilized by controlling the switching frequency of the voltage resonance type converter on the primary side according to the level of the high direct-current voltage. This configuration requires only one switching converter to be provided on the primary side of the flyback transformer FBT.

Claims

1. A high voltage stabilizing circuit comprising:

rectifying and smoothing means for rectifying and smoothing commercial alternating-current power and thereby providing direct-current input voltage;

switching means having a switching device for interrupting said direct-current input voltage for output;

a parallel resonant circuit on a primary side formed so as to convert operation of said switching means into voltage resonance type operation;

a high voltage output transformer having a primary-side winding to which switching output of said switching means is transmitted and a secondary-side winding closely coupled to the primary winding for inducing a required high level of stepped-up alternating voltage;

high direct-current voltage generating means supplied with said stepped-up alternating voltage for generating and outputting a required high level of direct-current voltage; and

constant voltage control means for controlling said high direct-current voltage to a constant voltage by changing switching frequency of said switching device according to level of said high direct-current voltage.

2. A high voltage stabilizing circuit as claimed in claim 1, wherein:

said parallel resonant circuit is formed by a choke coil inserted between a positive terminal of a smoothing capacitor forming said rectifying and smoothing means and a switching output point of the switching device, and a parallel resonant capacitor and a diode device connected in parallel with said switching device; and

a series connection circuit of said primary-side winding and a direct current blocking capacitor is connected to said switching device.

3. A high voltage stabilizing circuit as claimed in claim 1, wherein:

said parallel resonant circuit is formed by said primary-side winding inserted between a positive terminal of a smoothing capacitor forming said rectifying and smoothing means and a switching output point of the switching device, and a parallel resonant capacitor connected in parallel with said switching device.