JP2002233146A - Switching power device - Google Patents

Switching power device

Info

Publication number
JP2002233146A
JP2002233146A JP2001026673A JP2001026673A JP2002233146A JP 2002233146 A JP2002233146 A JP 2002233146A JP 2001026673 A JP2001026673 A JP 2001026673A JP 2001026673 A JP2001026673 A JP 2001026673A JP 2002233146 A JP2002233146 A JP 2002233146A
Authority
JP
Japan
Prior art keywords
voltage
control circuit
power supply
state
switching power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2001026673A
Other languages
Japanese (ja)
Other versions
JP4251259B2 (en
Inventor
Masanori Ota
真規 太田
Maki Hashimoto
真樹 橋本
Kazunori Yasuda
和則 安田
Tsutomu Matsumoto
力 松本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yokogawa Electric Corp
Original Assignee
Yokogawa Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yokogawa Electric Corp filed Critical Yokogawa Electric Corp
Priority to JP2001026673A priority Critical patent/JP4251259B2/en
Publication of JP2002233146A publication Critical patent/JP2002233146A/en
Application granted granted Critical
Publication of JP4251259B2 publication Critical patent/JP4251259B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Abstract

PROBLEM TO BE SOLVED: To provide a switching power device whose power consumption is reduced when it is lightly loaded. SOLUTION: This switching power device has a control circuit which causes a transformer to induce a voltage in its secondary coil by turning on and off a switching element connected to a primary side of the transformer, and intermittently applying a voltage to a primary coil of the transformer and is provided with a comparison means for comparing a signal representing the level of secondary-side output power with a specified reference value, and a stopping means for forcibly stopping the control circuit when the level of the output power on a secondary side is lower than a specified reference value.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、トランスの1次側
に設けたスイッチ素子をオン・オフし、1次巻線に断続
的に電圧を印加することによって2次巻線に電圧を誘起
させるスイッチング電源装置に関するものである。更に
詳しくは、電源にかかる負荷が軽いときに低消費電力化
をするための工夫を施したスイッチング電源装置に関す
るものである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching element provided on the primary side of a transformer which is turned on and off, and a voltage is induced in a secondary winding by intermittently applying a voltage to the primary winding. The present invention relates to a switching power supply. More specifically, the present invention relates to a switching power supply device devised to reduce power consumption when the load on the power supply is light.

【0002】[0002]

【従来の技術】図3は従来におけるスイッチング電源装
置の構成例を示した図である。図3で、トランス1の1
次側に加えられる直流電源2の電圧は、大きく変動した
り、またサージ電圧やサージ電流がのっていることもあ
る。このような過電圧、過電流が電源装置の出力端子に
接続された負荷に加えられると、これを損傷する。これ
を防ぐためにスイッチング電源装置は、一般にトランス
の1次側に接続された回路と、2次側に接続された回路
とを絶縁している。
2. Description of the Related Art FIG. 3 is a diagram showing a configuration example of a conventional switching power supply. In FIG.
The voltage of the DC power supply 2 applied to the secondary side may fluctuate greatly, or may have a surge voltage or surge current. When such an overvoltage or overcurrent is applied to the load connected to the output terminal of the power supply device, the load is damaged. In order to prevent this, the switching power supply generally insulates a circuit connected to the primary side of the transformer from a circuit connected to the secondary side.

【0003】トランス1の1次巻線3の両端にはツェナ
ーダイオード4とダイオード5が直列接続されている。
スイッチ素子6は1次巻線3の一端に接続されている。
ツェナーダイオード4とダイオード5は、サージ電圧や
サージ電流を吸収するスナバ回路を構成するために設け
られている。制御回路7は、PWM信号(パルス幅変調
信号)でスイッチ素子6を例えば一定の周波数でオン・
オフ駆動する。これにより、直流電源2の電圧が1次巻
線3へ断続的に加えられ、2次巻線8には誘起電圧が発
生する。2次巻線8に発生した誘起電圧は、ダイオード
9とコンデンサ10により整流し平滑化されて直流出力
電圧Voutになる。直流出力電圧Voutが負荷(図
示せず)に供給される。制御回路7はIC(集積回路)
化されている。
A Zener diode 4 and a diode 5 are connected in series to both ends of a primary winding 3 of a transformer 1.
The switch element 6 is connected to one end of the primary winding 3.
The Zener diode 4 and the diode 5 are provided to form a snubber circuit that absorbs surge voltage and surge current. The control circuit 7 turns on the switch element 6 with a PWM signal (pulse width modulation signal) at a constant frequency, for example.
Drive off. As a result, the voltage of the DC power supply 2 is intermittently applied to the primary winding 3, and an induced voltage is generated in the secondary winding 8. The induced voltage generated in the secondary winding 8 is rectified and smoothed by the diode 9 and the capacitor 10 to become the DC output voltage Vout. The DC output voltage Vout is supplied to a load (not shown). The control circuit 7 is an IC (integrated circuit)
Has been

【0004】直流出力電圧Voutは、回路11により
電圧変換等が行われて、フォトカップラ12により1次
側に絶縁伝送される。巻線13にはトランス1が駆動さ
れることによって電圧が誘起される。誘起電圧はダイオ
ード14とコンデンサ15により整流し平滑化され、制
御回路7に電源電圧Vccとして供給される。
The DC output voltage Vout is subjected to voltage conversion and the like by a circuit 11 and is insulated and transmitted to a primary side by a photocoupler 12. A voltage is induced in the winding 13 by driving the transformer 1. The induced voltage is rectified and smoothed by the diode 14 and the capacitor 15 and supplied to the control circuit 7 as the power supply voltage Vcc.

【0005】図3のスイッチング電源装置では、電源に
かかる負荷の状態に応じて制御回路7は、スイッチ素子
6をオンにする時間を制御する。電源にかかる負荷が小
さくなったときに、制御回路7は、出力するPWM信号
のパルス幅が小さくなるように制御する。PWM信号の
発振周波数を固定して制御する場合は、パルス幅を小さ
くしても発振周波数に依存するスイッチング損失は低減
しない。スイッチング損失はスイッチが切り換わるとき
に電力が消費されることによって生じる損失である。軽
負荷時に発振周波数が低減する制御回路を用いてスイッ
チのオフ時間を長くすると、スイッチング損失は減少す
るものの、実際にスイッチ素子6がオンになっている時
間だけでなく、オフになっている時間中も制御回路7に
は電流が供給され、電力が消費され続ける。
In the switching power supply shown in FIG. 3, the control circuit 7 controls the time during which the switch element 6 is turned on in accordance with the state of the load applied to the power supply. When the load applied to the power supply is reduced, the control circuit 7 controls so that the pulse width of the output PWM signal is reduced. When the control is performed with the oscillation frequency of the PWM signal fixed, the switching loss depending on the oscillation frequency is not reduced even if the pulse width is reduced. Switching loss is a loss caused by consuming power when a switch is switched. When the off time of the switch is increased by using a control circuit that reduces the oscillation frequency at a light load, the switching loss is reduced, but not only the time when the switch element 6 is actually on, but also the time when it is off. During this time, current is supplied to the control circuit 7 and power is continuously consumed.

【0006】[0006]

【発明が解決しようとする課題】本発明は上述した問題
点を解決するためになされたものであり、スイッチ素子
をオン・オフする制御回路を軽負荷時にはオフにする期
間を設けることによって、軽負荷時における低消費電力
化を実現したスイッチング電源装置を提供することを目
的とする。
SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and provides a control circuit for turning on and off a switch element at a light load by providing a period for turning off the control circuit. It is an object of the present invention to provide a switching power supply that achieves low power consumption at the time of load.

【0007】[0007]

【課題を解決するための手段】本発明は次のとおりの構
成になったスイッチング電源装置である。
SUMMARY OF THE INVENTION The present invention is a switching power supply having the following configuration.

【0008】(1)トランスの1次側に設けたスイッチ
素子をオン・オフし、1次巻線に断続的に電圧を印加す
ることによって2次巻線に電圧を誘起させ、2次側にか
かる負荷の状態に応じて前記スイッチ素子をオンにする
時間を制御する制御回路を有するスイッチング電源装置
において、2次側の出力電力レベルを示す信号と所定の
基準値とを比較する比較手段と、この比較手段による比
較の結果、2次側の出力電力レベルが所定の基準値より
も低いときは制御回路を強制的に停止する停止手段とを
有することを特徴とするスイッチング電源装置。
(1) A switch element provided on the primary side of the transformer is turned on / off, and a voltage is intermittently applied to the primary winding to induce a voltage on the secondary winding, thereby causing a voltage on the secondary side. In a switching power supply device having a control circuit for controlling a time for turning on the switch element according to the state of the load, a comparison unit that compares a signal indicating an output power level on the secondary side with a predetermined reference value, A switching power supply device comprising: stopping means for forcibly stopping the control circuit when the output power level on the secondary side is lower than a predetermined reference value as a result of the comparison by the comparing means.

【0009】(2)前記制御回路は前記比較手段の基準
値を与える電圧を生成することを特徴とする(1)記載
のスイッチング電源装置。
(2) The switching power supply according to (1), wherein the control circuit generates a voltage for giving a reference value of the comparing means.

【0010】(3)制御回路がオン状態とオフ状態のと
きに前記比較手段に与える基準値電圧が異なることをも
とに、比較手段の出力電圧を変え、制御回路に交互にオ
ン状態とオフ状態をとらせる状態切換回路を有すること
を特徴とする(1)記載のスイッチング電源装置。
(3) The output voltage of the comparing means is changed based on the difference between the reference voltage applied to the comparing means when the control circuit is in the ON state and the OFF state, and the ON state and the OFF state are alternately transmitted to the control circuit. The switching power supply according to (1), further comprising a state switching circuit for setting a state.

【0011】[0011]

【発明の実施の形態】以下図面を用いて本発明を詳しく
説明する。図1は本発明の一実施例を示す構成図であ
る。図1で図3と同一のものは同一符号を付ける。制御
回路20は、端子CSへの入力信号によって強制的に停
止するリモートオフ機能を持つ回路である。停止手段2
1はリモートオフ機能を実現する手段である。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention. 1 that are the same as those in FIG. 3 are given the same reference numerals. The control circuit 20 is a circuit having a remote-off function of forcibly stopping by an input signal to the terminal CS. Stopping means 2
Reference numeral 1 denotes a unit for realizing a remote-off function.

【0012】抵抗31,32は、フォトカップラ12に
より1次側にフィードバックされた電圧VFBを分圧す
る。電圧VFBは2次側の負荷状態を示している。負荷
が軽いほど電圧VFBは小さくなる。請求範囲でいう出
力電力レベルを示す信号は電圧VFBの信号である。抵
抗33,34は、制御回路20から与えられた基準電圧
Vrefを分圧する。コンパレータ35は、正側入力端
子に基準電圧Vrefの分圧V1が与えられ、負側入力
端子には電圧VFBの分圧V2が与えられる。コンパレ
ータ35は、1次側にフィードバックされた電圧VFB
を所定の基準値と比較し、比較結果に応じた2値信号V
3を出力する。請求範囲でいう比較手段はコンパレータ
である。トランジスタ36は、コンパレータ35の出力
V3によってオン・オフし、制御回路20の端子CSの
電圧V4を変える。コンデンサ37はトランジスタ36
に並列接続されている。図1の破線で囲んだ部分が請求
範囲でいう状態切換回路である。
The resistors 31 and 32 divide the voltage V FB fed back to the primary side by the photo coupler 12. The voltage V FB indicates a load state on the secondary side. The lighter the load, the lower the voltage V FB . The signal indicating the output power level in the claims is a signal of the voltage VFB . The resistors 33 and 34 divide the reference voltage Vref provided from the control circuit 20. In the comparator 35, the divided voltage V1 of the reference voltage Vref is supplied to the positive input terminal, and the divided voltage V2 of the voltage VFB is supplied to the negative input terminal. The comparator 35 outputs the voltage V FB fed back to the primary side.
Is compared with a predetermined reference value, and a binary signal V corresponding to the comparison result is obtained.
3 is output. The comparing means in the claims is a comparator. The transistor 36 is turned on / off by the output V3 of the comparator 35, and changes the voltage V4 of the terminal CS of the control circuit 20. The capacitor 37 is a transistor 36
Are connected in parallel. A portion surrounded by a broken line in FIG. 1 is a state switching circuit referred to in the claims.

【0013】図1の装置の動作を説明する。図2は図1
の装置における各信号のタイムチャートである。定常負
荷では電圧VFBは高い値を維持しており、V2>V1
でありコンパレータ35の出力はローレベルである。こ
のとき、トランジスタ36はオフであるため、制御回路
20の端子CSの電圧V4は高い値になっている。これ
によって、制御回路20はオンになっている。
The operation of the apparatus shown in FIG. 1 will be described. FIG. 2 shows FIG.
6 is a time chart of each signal in the device of FIG. Under a steady load, the voltage VFB maintains a high value, and V2> V1
And the output of the comparator 35 is at a low level. At this time, since the transistor 36 is off, the voltage V4 of the terminal CS of the control circuit 20 has a high value. As a result, the control circuit 20 is turned on.

【0014】軽負荷時には電圧VFBは低下し、V2<
V1になるため、コンパレータ35の出力はハイレベル
になり、トランジスタ36はオンになる。これによっ
て、制御回路20の端子CSの電圧V4は低下し、制御
回路20は強制的なオフにされる。強制的にオフにする
のは停止手段21が行う。強制的にオフにした期間では
制御回路20は電力を消費しない。これによって、軽負
荷時の電力損失を低減できる。
At light load, voltage V FB decreases, and V 2 <
Since the voltage is V1, the output of the comparator 35 becomes high level, and the transistor 36 is turned on. As a result, the voltage V4 at the terminal CS of the control circuit 20 decreases, and the control circuit 20 is forcibly turned off. The forcible turning off is performed by the stopping means 21. The control circuit 20 does not consume power during the forcibly turned off period. Thereby, power loss at the time of light load can be reduced.

【0015】制御回路20は基準電圧Vrefを出力し
ているため、制御回路20がオフになると、電圧V1は
低下する。電圧V1が低下すると、コンパレータ35の
出力電圧V3は低下する。これにより、トランジスタ3
6に流れる電流が減少し、電圧V4は大きくなる。電圧
V4の増大により制御回路20はオンになる。制御回路
20はオンになると、基準電圧Vrefが増加して出力
電圧V3は増加し、トランジスタ36に流れる電流が増
加して、電圧V4が減少し、制御回路20がオフにな
る。このようにして制御回路20は自動的にオン状態と
オフ状態を繰り返す。図2の期間Toffで制御回路2
0はオフになり、期間Tonで制御回路20はオンにな
る。軽負荷時には制御回路20はオフ状態とオン状態を
自動的に繰り返す。
Since the control circuit 20 outputs the reference voltage Vref, when the control circuit 20 is turned off, the voltage V1 decreases. When the voltage V1 decreases, the output voltage V3 of the comparator 35 decreases. Thereby, the transistor 3
6 decreases, and the voltage V4 increases. The control circuit 20 is turned on by the increase in the voltage V4. When the control circuit 20 is turned on, the reference voltage Vref increases, the output voltage V3 increases, the current flowing through the transistor 36 increases, the voltage V4 decreases, and the control circuit 20 turns off. Thus, the control circuit 20 automatically repeats the ON state and the OFF state. In the period Toff of FIG.
0 is turned off, and the control circuit 20 is turned on in the period Ton. At light load, the control circuit 20 automatically repeats the off state and the on state.

【0016】[0016]

【発明の効果】本発明によれば次の効果が得られる。According to the present invention, the following effects can be obtained.

【0017】請求項1記載の発明では、軽負荷時には制
御回路を強制的にオフにする期間を作っているため、ス
イッチング電源装置の軽負荷時での省電力化を実現でき
る。
According to the first aspect of the present invention, since a period in which the control circuit is forcibly turned off at the time of light load is formed, power saving of the switching power supply at the time of light load can be realized.

【0018】請求項2記載の発明では、制御回路は比較
手段の基準値を与える電圧を生成しているため、基準値
を与える電圧源を別個に設ける必要がなく、回路を簡略
化できる。
According to the second aspect of the present invention, since the control circuit generates the voltage for giving the reference value of the comparing means, it is not necessary to separately provide a voltage source for giving the reference value, and the circuit can be simplified.

【0019】請求項3記載の発明によれば、軽負荷の状
態が解除されると制御回路は自動的にオン状態に復帰す
るため、スイッチング動作を再開することができる。
According to the third aspect of the invention, when the light load state is released, the control circuit automatically returns to the ON state, so that the switching operation can be resumed.

【図面の簡単な説明】[Brief description of the drawings]

【図1】本発明の一実施例を示す構成図である。FIG. 1 is a configuration diagram showing one embodiment of the present invention.

【図2】本発明の動作説明図である。FIG. 2 is a diagram illustrating the operation of the present invention.

【図3】従来におけるスイッチング電源装置の構成例を
示した図である。
FIG. 3 is a diagram showing a configuration example of a conventional switching power supply device.

【符号の説明】[Explanation of symbols]

1 トランス 2 電源 3 1次巻線 6 スイッチ素子 8 2次巻線 20 制御回路 21 停止手段 35 コンパレータ DESCRIPTION OF SYMBOLS 1 Transformer 2 Power supply 3 Primary winding 6 Switching element 8 Secondary winding 20 Control circuit 21 Stopping means 35 Comparator

フロントページの続き (72)発明者 松本 力 東京都武蔵野市中町2丁目9番32号 横河 電機株式会社内 Fターム(参考) 5H730 AA14 AS01 AS23 BB43 BB57 DD04 DD41 EE02 EE07 FD01 FF01 FF19 FG07 FG25 VV03 XC00 XX03 XX44 Continuation of front page (72) Inventor Riki Matsumoto 2-9-32 Nakamachi, Musashino-shi, Tokyo F-term in Yokogawa Electric Corporation (reference) 5H730 AA14 AS01 AS23 BB43 BB57 DD04 DD41 EE02 EE07 FD01 FF01 FF19 FG07 FG25 VV03 XC00 XX03 XX44

Claims (3)

【特許請求の範囲】[Claims] 【請求項1】 トランスの1次側に設けたスイッチ素子
をオン・オフし、1次巻線に断続的に電圧を印加するこ
とによって2次巻線に電圧を誘起させ、2次側にかかる
負荷の状態に応じて前記スイッチ素子をオンにする時間
を制御する制御回路を有するスイッチング電源装置にお
いて、 2次側の出力電力レベルを示す信号と所定の基準値とを
比較する比較手段と、この比較手段による比較の結果、
2次側の出力電力レベルが所定の基準値よりも低いとき
は制御回路を強制的に停止する停止手段とを有すること
を特徴とするスイッチング電源装置。
1. A switching element provided on a primary side of a transformer is turned on / off, and a voltage is induced on a secondary winding by intermittently applying a voltage to a primary winding to apply a voltage to a secondary side. In a switching power supply having a control circuit for controlling a time for turning on the switch element in accordance with a state of a load, a comparing means for comparing a signal indicating an output power level on the secondary side with a predetermined reference value; As a result of the comparison by the comparing means,
A switching power supply device comprising: stopping means for forcibly stopping the control circuit when the output power level on the secondary side is lower than a predetermined reference value.
【請求項2】 前記制御回路は前記比較手段の基準値を
与える電圧を生成することを特徴とする請求項1記載の
スイッチング電源装置。
2. The switching power supply device according to claim 1, wherein the control circuit generates a voltage that gives a reference value of the comparison means.
【請求項3】 制御回路がオン状態とオフ状態のときに
前記比較手段に与える基準値電圧が異なることをもと
に、比較手段の出力電圧を変え、制御回路に交互にオン
状態とオフ状態をとらせる状態切換回路を有することを
特徴とする請求項1記載のスイッチング電源装置。
3. An output voltage of the comparison means is changed based on a difference in a reference voltage applied to the comparison means when the control circuit is in an on state and an off state, and the control circuit alternately turns on and off states. 2. The switching power supply device according to claim 1, further comprising a state switching circuit that takes a state.
JP2001026673A 2001-02-02 2001-02-02 Switching power supply Expired - Fee Related JP4251259B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001026673A JP4251259B2 (en) 2001-02-02 2001-02-02 Switching power supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2001026673A JP4251259B2 (en) 2001-02-02 2001-02-02 Switching power supply

Publications (2)

Publication Number Publication Date
JP2002233146A true JP2002233146A (en) 2002-08-16
JP4251259B2 JP4251259B2 (en) 2009-04-08

Family

ID=18891454

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005110346A (en) * 2003-09-29 2005-04-21 Densei Lambda Kk Power supply and power backup method
US8218340B2 (en) 2007-06-14 2012-07-10 Mitsumi Electric Co., Ltd. Switching power supply apparatus and primary side control circuit
WO2014192399A1 (en) 2013-05-30 2014-12-04 日産自動車株式会社 Dc-dc converter and control method therefor

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CN106533175A (en) * 2015-09-11 2017-03-22 亚荣源科技(深圳)有限公司 Retracing type power converter

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005110346A (en) * 2003-09-29 2005-04-21 Densei Lambda Kk Power supply and power backup method
JP4542325B2 (en) * 2003-09-29 2010-09-15 Tdkラムダ株式会社 Power supply device and power backup method
US8218340B2 (en) 2007-06-14 2012-07-10 Mitsumi Electric Co., Ltd. Switching power supply apparatus and primary side control circuit
WO2014192399A1 (en) 2013-05-30 2014-12-04 日産自動車株式会社 Dc-dc converter and control method therefor
US9985530B2 (en) 2013-05-30 2018-05-29 Nissan Motor Co., Ltd. DC-DC converter and control method thereof

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