JPS6211156Y2 - - Google Patents
Info
- Publication number
- JPS6211156Y2 JPS6211156Y2 JP11858479U JP11858479U JPS6211156Y2 JP S6211156 Y2 JPS6211156 Y2 JP S6211156Y2 JP 11858479 U JP11858479 U JP 11858479U JP 11858479 U JP11858479 U JP 11858479U JP S6211156 Y2 JPS6211156 Y2 JP S6211156Y2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- power supply
- voltage
- fuse
- vcc
- 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.)
- Expired
Links
- 230000010355 oscillation Effects 0.000 description 7
- 230000007423 decrease Effects 0.000 description 5
- 238000001514 detection method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000001012 protector Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
Landscapes
- Emergency Protection Circuit Devices (AREA)
Description
【考案の詳細な説明】
本考案は電子回路、特にテレビジヨン受像機等
の大電力を必要とする電子回路の電源に生じる過
電圧から電子回路を保護する保護回路に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic circuit, and particularly to a protection circuit that protects the electronic circuit from overvoltages generated in the power supply of electronic circuits that require large amounts of power, such as television receivers.
電源電圧の上昇は電子回路の動作条件を悪化さ
せ、トランジスタ抵抗等の回路素子の温度上昇、
熱暴走を引き起こすこととなる。これを防止する
ため、従来では電源入力部にヒユーズまたはヒユ
ーズ抵抗を挿入するか、トランジスタの放熱器
（放熱板）を大きくしたり、抵抗のワツト数を大
きくして熱容量を上げるなどして電源電圧の上昇
に対処していた。上記防止策のうちトランジスタ
の放熱器を大きくしたり、抵抗のワツト数を増や
すことは部品の大形化につながり、プリント基板
が必要以上に大形になつてしまうことになつて小
形化の点で不利である。 An increase in power supply voltage worsens the operating conditions of electronic circuits, increasing the temperature of circuit elements such as transistor resistors,
This will cause thermal runaway. To prevent this, conventional methods have been used to increase the power supply voltage by inserting a fuse or fuse resistor into the power input section, by increasing the heat sink of the transistor, or by increasing the wattage of the resistor to increase the heat capacity. was dealing with a rise in Among the above preventive measures, increasing the size of the transistor heatsink or increasing the wattage of the resistor will lead to larger components, making the printed circuit board larger than necessary, which is an issue with downsizing. It is disadvantageous.
一方、電源入力部にヒユーズ、ヒユーズ抵抗を
挿入した保護回路では負荷端の短絡等により生ず
る過電流に対しては効果があるが、電源回路の短
絡等により生じる過電圧に対しては防止効果がき
わめて小さい。すなわち、第１図にヒユーズ抵抗
による保護回路の例を示す。図中、Vccは電圧源
１の電源電圧、Ｒはヒユーズ抵抗、Ｌは保護すべ
き負荷回路、V1はＲとＬとの接続点における電
圧である。第１図において、電源電圧Vccが上昇
したとすると電圧V1も上昇し、ヒユーズ抵抗Ｒ
に流れる電流は負荷回路Ｌにおいて増加する電流
分しか増加しないことになり、電流変化は小さ
い。このため、電源電圧が上昇してもヒユーズを
溶断するには到らず、結局ヒユーズ抵抗後の回路
に過電圧が加わつて負荷回路Ｌのトランジスタ、
抵抗等の発熱、熱暴走をひき起し、破壊を招来す
ることとなる。 On the other hand, a protection circuit in which a fuse or fuse resistor is inserted into the power supply input section is effective against overcurrents caused by short circuits at the load end, but is extremely ineffective against overvoltages caused by short circuits in the power supply circuit. small. That is, FIG. 1 shows an example of a protection circuit using a fuse resistor. In the figure, Vcc is the power supply voltage of voltage source 1, R is the fuse resistance, L is the load circuit to be protected, and V1 is the voltage at the connection point between R and L. In Figure 1, if the power supply voltage Vcc rises, the voltage V1 also rises, and the fuse resistance R
The current flowing through the load circuit L increases only by the amount of current that increases in the load circuit L, and the current change is small. Therefore, even if the power supply voltage rises, it will not blow the fuse, and eventually overvoltage will be applied to the circuit after the fuse resistor, causing the transistor in load circuit L to
This will cause heat generation and thermal runaway in the resistor, etc., resulting in destruction.
そこで本考案は、過電流発生時のみならず、過
電圧発生時においても確実に電子回路を保護しう
る過電圧保護回路を提供することを目的とする。 Therefore, an object of the present invention is to provide an overvoltage protection circuit that can reliably protect an electronic circuit not only when an overcurrent occurs but also when an overvoltage occurs.
以下本考案を図示する実施例に基いて詳述す
る。第２図に本考案による保護回路の原理的概要
図を示す。なお、第２図において第１図と同一部
分は同一符号とし説明は省略する。図中、V2は
主電源１の電圧Vccの変動と逆極性の変動（すな
わち電圧上昇に対して減少、あるいはその逆）を
する副電源２の電圧、ZDはツエナーダイオー
ド、Vzはツエナー電圧である。ツエナーダイオ
ードZDのカソードはヒユーズ抵抗Ｒと負荷回路
Ｌとの接続点に接続され、アノードは副電源２に
接続されている。副電源２は主電源１の電圧Vcc
が異常に高くなつたとき自動的に制御されて出力
電圧V2が低下し、かつ定常状態においては回路
動作に影響を与えないように主電源電圧Vccより
小さくツエナー電圧Vzより大きい電圧V2（Vcc
＞V2＞Vz）を出力する構成となつている。 The present invention will be described in detail below based on illustrated embodiments. FIG. 2 shows a schematic diagram of the principle of the protection circuit according to the present invention. Note that in FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals, and explanations thereof will be omitted. In the figure, V 2 is the voltage of the auxiliary power supply 2 that fluctuates in the opposite polarity to the fluctuation of the voltage Vcc of the main power supply 1 (i.e. decreases as the voltage increases, or vice versa), ZD is the Zener diode, and Vz is the Zener voltage. be. The cathode of the Zener diode ZD is connected to the connection point between the fuse resistor R and the load circuit L, and the anode is connected to the sub power supply 2. Sub-power supply 2 is the voltage Vcc of main power supply 1
When the output voltage V 2 becomes abnormally high, the output voltage V 2 is automatically controlled to decrease, and in a steady state, the voltage V 2 ( Vcc
＞V 2 ＞Vz).
次に動作を説明する。主電源電圧Vccが異常に
高くなると副電源２の電圧V2が自動的に低くな
り、ツエナーダイオードZDがオンとなつて接続
点電圧V1はV2＋Vzの定電圧に保たれる。この電
圧V1＝V2＋Vzを充分低く選ぶことによりヒユー
ズ抵抗Ｒの両端の電位差Vcc−V1が大きくなり、
したがつて（Vcc−V1）／Ｒで決定される電流
（ヒユーズを溶断するに足る大きさの電流）がヒ
ユーズ抵抗Ｒを流れ、ヒユーズ抵抗Ｒが溶断され
て主電源電圧Vccをしや断することができる。 Next, the operation will be explained. When the main power supply voltage Vcc becomes abnormally high, the voltage V 2 of the auxiliary power supply 2 is automatically lowered, the Zener diode ZD is turned on, and the connection point voltage V 1 is maintained at a constant voltage of V 2 +Vz. By selecting this voltage V 1 =V 2 +Vz sufficiently low, the potential difference Vcc-V 1 across the fuse resistor R becomes large.
Therefore, a current determined by (Vcc - V 1 )/R (a current large enough to blow the fuse) flows through the fuse resistor R, and the fuse resistor R is blown, cutting off the main power supply voltage Vcc. can do.
次に本考案の保護回路をテレビジヨン受像機の
回路に用いた例を第３図に示す。図中、３は保護
すべき垂直出力回路で第２図の負荷回路Ｌに相当
する。Q1は垂直ドライブトランジスタ、Q2，Q3
は垂直出力トランジスタである。４は第２図の副
電源２に相当する水平出力回路で、５は電圧検出
回路、６は水平発振回路、７は水平ドライブ回
路、８は水平出力段回路である。副電源電圧V2
はこの水平出力段回路８の出力をダイオード
D1、コンデンサＣにより整流して得られる。電
圧検出回路５は主電源電圧が何らかの原因で上昇
したとき動作し、水平発振回路６を停止させる回
路であ。L1は副電源すなわち水平出力段回路８
の負荷回路である。 Next, FIG. 3 shows an example in which the protection circuit of the present invention is used in a television receiver circuit. In the figure, 3 is a vertical output circuit to be protected, which corresponds to the load circuit L in FIG. Q 1 is vertical drive transistor, Q 2 , Q 3
is the vertical output transistor. 4 is a horizontal output circuit corresponding to the sub power supply 2 in FIG. 2, 5 is a voltage detection circuit, 6 is a horizontal oscillation circuit, 7 is a horizontal drive circuit, and 8 is a horizontal output stage circuit. Sub-power supply voltage V 2
connects the output of this horizontal output stage circuit 8 to a diode
D 1 is obtained by rectifying with capacitor C. The voltage detection circuit 5 is a circuit that operates when the main power supply voltage rises for some reason and stops the horizontal oscillation circuit 6. L 1 is the sub power supply or horizontal output stage circuit 8
This is the load circuit.
第３図において、主電源電圧Vccが異常上昇
し、その値Vccが電圧検出回路５の基準電圧を越
えると電圧検出回路５は水平発振回路６の電源を
下げて水平発振を停止させる。水平発振が停止す
ると、水平ドライブ回路７および水平出力段回路
８が動作せず、したがつて副電源電圧V2が低下
する。その結果ツエナーダイオードZDがオンし
てカソード側の電圧V1が下がり、ヒユーズ抵抗
Ｒの両端の電圧差Vcc−V1が大きくなつてヒユー
ズ抵抗Ｒに流れる電流が増加し、ヒユーズ抵抗Ｒ
が溶断して垂直出力回路３のトランジスタQ2，
Q3が保護されることになる。このように、テレ
ビジヨン受像機回路では副電源として、電圧上昇
時に水平発振等を止めて高圧の上昇を防ぐ回路、
たとえばフエイルセーフ（FALL／SAFE）また
はＸ線プロテクタ（Ｘ ray protector）等を利
用することができる。 In FIG. 3, when the main power supply voltage Vcc rises abnormally and its value Vcc exceeds the reference voltage of the voltage detection circuit 5, the voltage detection circuit 5 lowers the power supply of the horizontal oscillation circuit 6 to stop horizontal oscillation. When the horizontal oscillation stops, the horizontal drive circuit 7 and the horizontal output stage circuit 8 do not operate, and therefore the sub power supply voltage V 2 decreases. As a result, the Zener diode ZD turns on and the voltage V1 on the cathode side decreases, the voltage difference Vcc- V1 between both ends of the fuse resistor R increases, the current flowing through the fuse resistor R increases, and the voltage V1 on the cathode side decreases.
is fused and the transistor Q 2 of the vertical output circuit 3,
Q 3 will be protected. In this way, television receiver circuits use circuits as auxiliary power sources to stop horizontal oscillation, etc. when the voltage rises, and prevent high voltage from rising.
For example, a failsafe (FALL/SAFE) or an X-ray protector can be used.
以上の通り本考案によれば、何らかの原因によ
つて主電源電圧が異常上昇した場合確実に電子回
路の回路素子（例えば高価なトランジスタ等）を
保護することができ、この保護の為に既存の回路
にツエナーダイオードを追加するだけで構成する
ことができ、よつて回路構成を簡単なものとする
ことができ、既存回路への適用が容易であり、製
品の低廉化が可能であり、さらに印刷配線基板に
対する省スペース化ができるだけでなく、製造の
手間、点検等もきわめて容易なものとなる。 As described above, according to the present invention, it is possible to reliably protect the circuit elements of the electronic circuit (for example, expensive transistors, etc.) when the main power supply voltage rises abnormally for some reason. It can be configured by simply adding a Zener diode to the circuit, thus simplifying the circuit configuration, making it easy to apply to existing circuits, reducing product costs, and printing. This not only saves space on the wiring board, but also greatly facilitates manufacturing and inspection.
第１図は従来の保護回路を示す回路図、第２図
は本考案による保護回路の基本回路図、第３図は
本考案による保護回路とテレビジヨン受像機回路
を組み合わせた例を示す回路図である。
１……主電源、２……副電源、３……垂直出力
回路、４……水平出力回路、５……電圧検出回
路、６……水平発振回路、７……水平ドライブ回
路、８……水平出力段回路、Vcc……主電源電
圧、V1……接続点電圧、V2……副電源電圧、Vz
……ツエナー電圧、Ｒ……ヒユーズ抵抗、Ｌ……
負荷回路、ZD……ツエナーダイオード。
Figure 1 is a circuit diagram showing a conventional protection circuit, Figure 2 is a basic circuit diagram of a protection circuit according to the present invention, and Figure 3 is a circuit diagram showing an example of a combination of a protection circuit according to the present invention and a television receiver circuit. It is. 1... Main power supply, 2... Sub-power supply, 3... Vertical output circuit, 4... Horizontal output circuit, 5... Voltage detection circuit, 6... Horizontal oscillation circuit, 7... Horizontal drive circuit, 8... Horizontal output stage circuit, Vcc...Main power supply voltage, V1 ...Connection point voltage, V2 ...Subpower supply voltage, Vz
... Zener voltage, R ... Fuse resistance, L ...
Load circuit, ZD...Zener diode.
Claims (1)
たテレビジヨン受像機用の過電圧保護回路におい
て、前記ヒユーズ抵抗と負荷との接続点にツエナ
ーダイオードのカソードが接続され、このツエナ
ーダイオードのアノードは、水平出力回路に設け
られると共に主電源が所定値を越えたときにこの
水平出力回路の動作によつて電圧を低下させる電
源回路に接続されていることを特徴とする過電圧
保護回路。 In an overvoltage protection circuit for a television receiver in which a load is connected to the main power supply through a fuse resistor, the cathode of a Zener diode is connected to the connection point between the fuse resistor and the load, and the anode of this Zener diode is An overvoltage protection circuit characterized in that it is provided in an output circuit and is connected to a power supply circuit that reduces the voltage by operating the horizontal output circuit when the main power supply exceeds a predetermined value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11858479U JPS6211156Y2 (en) | 1979-08-29 | 1979-08-29 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11858479U JPS6211156Y2 (en) | 1979-08-29 | 1979-08-29 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5635834U JPS5635834U (en) | 1981-04-07 |
| JPS6211156Y2 true JPS6211156Y2 (en) | 1987-03-16 |
Family
ID=29350794
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11858479U Expired JPS6211156Y2 (en) | 1979-08-29 | 1979-08-29 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6211156Y2 (en) |
-
1979
- 1979-08-29 JP JP11858479U patent/JPS6211156Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5635834U (en) | 1981-04-07 |
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