JPH04367139A - Signal transmission circuit with output protection circuit - Google Patents
Signal transmission circuit with output protection circuitInfo
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- JPH04367139A JPH04367139A JP3142201A JP14220191A JPH04367139A JP H04367139 A JPH04367139 A JP H04367139A JP 3142201 A JP3142201 A JP 3142201A JP 14220191 A JP14220191 A JP 14220191A JP H04367139 A JPH04367139 A JP H04367139A
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- 230000008054 signal transmission Effects 0.000 title claims abstract description 30
- 230000005540 biological transmission Effects 0.000 claims abstract description 19
- 230000015556 catabolic process Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 16
- 238000000034 method Methods 0.000 description 10
- 230000006378 damage Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000007257 malfunction Effects 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
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Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は信号送信回路の出力保護
に関する。データ通信における信号送受信回路には各種
の方式が使用されている。信号送信回路と信号受信回路
間の距離が近接している場合には周知のＴＴＬ方式によ
る信号伝送が行われるのが一般的であるが、信号送信回
路と信号受信回路間の距離が離れている場合には、ＣＣ
ＩＴＴ（国際電信電話諮問委員会）の勧告Ｖ．１１「デ
ータ通信分野での集積回路装置に用いられる汎用の平衡
複流相互接続回路の電気的特性」に従った平衡複流方式
の信号伝送が行われることが多い。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to output protection for signal transmission circuits. Various systems are used for signal transmitting and receiving circuits in data communications. When the distance between the signal transmitting circuit and the signal receiving circuit is close, signal transmission is generally performed using the well-known TTL method, but when the distance between the signal transmitting circuit and the signal receiving circuit is large. In case, C.C.
Recommendation of ITT (International Telegraph and Telephone Advisory Committee) V. 11 "Electrical Characteristics of General-Purpose Balanced Double-Current Interconnect Circuits Used in Integrated Circuit Devices in the Data Communications Field", balanced double-current signal transmission is often performed.
【０００２】通常、信号送受信回路間には複数の信号線
が設けられるが、設計当初は信号線の容量全部を使用せ
ず、後になってから空き信号線を使用して機能拡張が行
われる場合も多い。[0002] Normally, multiple signal lines are provided between signal transmitting and receiving circuits, but the entire capacity of the signal lines is not used at the beginning of the design, and functions are expanded later using empty signal lines. There are also many.
【０００３】一方、近年のプリント配線回路（以下、パ
ッケージと記す）ではノイズによる誤動作の防止や雑音
の抑制のために、使用しない信号線などを地気に接続す
ることが多いが、設計当初は地気に接続していなかった
空き信号線を実用に供してからノイズ削減などのために
接地する例も多い。On the other hand, in recent printed wiring circuits (hereinafter referred to as packages), unused signal lines are often connected to the ground in order to prevent malfunctions due to noise and suppress noise. There are many cases where vacant signal lines that were not connected to the ground are put into practical use and then grounded to reduce noise.
【０００４】このような状況から、空き信号線に信号送
出回路を追加して機能追加を行った場合に、受信側の信
号線が地気に接続されていないことを前提に信号送出回
路を付加した信号送信回路パッケージが、その信号線が
接地されている信号受信回路パッケージに接続され、信
号送出回路が破壊する例が生じている。[0004] Under these circumstances, when a signal transmission circuit is added to an empty signal line to add functionality, the signal transmission circuit is added on the assumption that the signal line on the receiving side is not connected to the earth. There have been cases in which a signal transmitting circuit package that has been connected is connected to a signal receiving circuit package whose signal line is grounded, and the signal transmitting circuit is destroyed.
【０００５】このため、信号線が接地されている信号受
信回路パッケージに接続されても破壊することがない信
号送信回路が必要となっている。[0005] Therefore, there is a need for a signal transmitting circuit that will not be destroyed even if the signal line is connected to a grounded signal receiving circuit package.
【０００６】[0006]
【従来の技術】図３はＴＴＬ方式による従来技術の信号
送受信回路の構成図、図４はＣＣＩＴＴ勧告Ｖ．１１方
式による従来技術の信号送受信回路の構成図、図５は従
来技術のＴＴＬ方式信号送受信回路の信号波形図、図６
は従来技術のＶ．１１方式信号送受信回路の信号波形図
、図７は信号送受信回路パッケージの組合せ図である。2. Description of the Related Art FIG. 3 is a block diagram of a conventional signal transmitting/receiving circuit based on the TTL system, and FIG. FIG. 5 is a signal waveform diagram of the prior art TTL signal transmitting and receiving circuit, and FIG.
is the prior art V. FIG. 7 is a signal waveform diagram of the No. 11 signal transmission/reception circuit, and FIG. 7 is a combination diagram of the signal transmission/reception circuit package.
【０００７】図３はＴＴＬ送信素子（ドライブＩＣとも
記す）２２が搭載された信号送信回路パッケージ２１と
ＴＴＬ受信素子（レシーブＩＣとも記す）３２が搭載さ
れた信号受信回路パッケージ３１が伝送ケーブル２３を
介して対向接続された状態を図示したものである。この
方式では図のＴＴＬ送信素子２２とＴＴＬ受信素子３２
間において周知のトランジスタ−トランジスタ論理回路
（ＴＴＬ）の信号レベルにより信号の送受信を行う。FIG. 3 shows a signal transmitting circuit package 21 equipped with a TTL transmitting element (also referred to as a drive IC) 22 and a signal receiving circuit package 31 equipped with a TTL receiving element (also referred to as a receive IC) 32 connected to a transmission cable 23. This figure shows a state in which they are connected facing each other through the wires. In this method, the TTL transmitting element 22 and TTL receiving element 32 shown in the figure
Signals are transmitted and received between them according to the signal level of a well-known transistor-transistor logic circuit (TTL).
【０００８】なお、図３には説明の便のため抵抗ＲＴが
図示されているが、従来の信号送信回路パッケージ２１
においては抵抗ＲＴは接続されていない。即ち、ＲＴ＝
０Ωとする。Although a resistor RT is shown in FIG. 3 for convenience of explanation, the conventional signal transmitting circuit package 21
At , the resistor RT is not connected. That is, RT=
It is set to 0Ω.
【０００９】図５は図３の信号送受信回路の信号波形を
示した図であり、■はドライブＩＣ２２に入力される信
号波形、■はＲＴ＝０Ωの従来回路におけるドライブＩ
Ｃ２２の出力波形、即ち、出力端子２６における信号波
形である。図５に示すように、図３の点■におけるドラ
イブＩＣ２２の入力信号レベルがＶＨ （例えば２．２
Ｖ）以上であれば点■にＶＨ を超える信号（論理レベ
ル“１”の信号）が出力され、■の入力がＶＬ（例えば
０．７Ｖ）以下であれば点■にほぼ０ボルトの信号（論
理レベル“０”の信号）が出力される。信号受信回路パ
ッケージ３１では伝送ケーブル２３を経てレシーブＩＣ
３２がこの信号を受信し、論理レベル“１”の信号の受
信レベルが前記ＶＨ 以上、論理レベル“０”の信号の
受信レベルが前記ＶＬ 以下であれば図５の■と同一波
形の信号を出力する。FIG. 5 is a diagram showing signal waveforms of the signal transmitting/receiving circuit shown in FIG.
This is the output waveform of C22, that is, the signal waveform at output terminal 26. As shown in FIG. 5, the input signal level of the drive IC 22 at point ■ in FIG. 3 is VH (for example, 2.2
V) or more, a signal exceeding VH (logic level "1" signal) is output to point ■; if the input to ■ is less than VL (for example, 0.7 V), a signal of approximately 0 volts ( A signal of logic level "0") is output. In the signal receiving circuit package 31, the receiving IC is connected via the transmission cable 23.
32 receives this signal, and if the reception level of the signal with logic level "1" is above the above VH and the reception level of the signal with logic level "0" is below the above VL, it sends a signal with the same waveform as ◯ in Fig. 5. Output.
【００１０】図４はＣＣＩＴＴの勧告Ｖ．１１「データ
通信分野での集積回路装置に用いられる汎用の平衡複流
相互接続回路の電気的特性」に基づく平衡複流方式によ
り信号を送受信する回路である。図４のＶ．１１送信素
子（ドライブＩＣとも記す）２は図６の■に示す信号を
入力すると２本の信号線４に対して図６の■及び■に示
すような極性の異なる複流信号を送出する。FIG. 4 shows CCITT Recommendation V. This is a circuit that transmits and receives signals using a balanced double-current method based on 11 "Electrical characteristics of a general-purpose balanced double-current interconnection circuit used in integrated circuit devices in the data communications field." V in FIG. 11. When the transmitting element (also referred to as a drive IC) 2 receives the signal shown in ■ in FIG. 6, it sends double current signals of different polarities to the two signal lines 4 as shown in ■ and ■ in FIG.
【００１１】上記信号は伝送ケーブル３を経て信号受信
回路パッケージ１１のＶ．１１受信素子（レシーブＩＣ
とも記す）１２に受信される。レシーブＩＣ１２は差動
増幅器であり、図６の■及び■の信号をそれぞれ＋，−
の２つの入力端子に受信したとき、両信号の電位差が一
定値以上であれば論理レベル“１”を出力し、一定値以
下であれば論理レベル“０”を出力する。即ち、図６の
■及び■の信号を入力したとき、レシーブＩＣ１２は■
に示す論理レベルの信号を出力する。なお、図４におけ
る終端回路１７はＣＣＩＴＴの勧告Ｖ．１１に規定され
る終端回路である。また、平衡複流式の２本の信号線４
及び伝送ケーブル３は平衡化するため図４に示すように
ペア線を使用する。The above signal is transmitted through the transmission cable 3 to the V.V. of the signal receiving circuit package 11. 11 receiving elements (receive IC
12). The receive IC 12 is a differential amplifier, and receives the signals shown in Figure 6 as + and -, respectively.
When received at two input terminals, if the potential difference between both signals is above a certain value, a logic level "1" is output, and if it is below a certain value, a logic level "0" is output. That is, when the signals of ■ and ■ in FIG. 6 are input, the receive IC 12
Outputs a signal with the logic level shown in . Note that the termination circuit 17 in FIG. 4 is based on CCITT recommendation V. This is a termination circuit defined in No. 11. In addition, two signal lines 4 of balanced double flow type
In order to balance the transmission cable 3, a pair of wires is used as shown in FIG.
【００１２】図３及び図４に示したような信号送信回路
パッケージと信号受信回路パッケージ間には信号線が複
数設けられるのが普通であるが、前記したように、設計
当初は信号線の容量全部を使用せず、後になってから空
き信号線を使用して機能拡張が行われることも多い。Normally, a plurality of signal lines are provided between the signal transmitting circuit package and the signal receiving circuit package as shown in FIGS. 3 and 4, but as mentioned above, the capacitance of the signal lines is It is often the case that all of the lines are not used, and functions are expanded later using empty signal lines.
【００１３】一方、プリント配線機器ではノイズによる
誤動作の防止や雑音の抑制のために使用しない信号線な
どを接地しておくことが多いが、設計当初は接地してい
なかった空き信号線を実用に供してから地気に接続する
場合もある。このような場合、受信側の信号線が接地さ
れていないことを前提として付加した信号送出回路を既
存の受信回路パッケージと対向させたときに受信側が接
地されていると、ドライブＩＣなどが破壊する可能性が
ある。On the other hand, in printed wiring equipment, unused signal lines are often grounded to prevent malfunctions caused by noise and to suppress noise, but empty signal lines that were not grounded at the beginning of the design are put into practical use. In some cases, it is connected to the earth after being provided. In such a case, if the signal line on the receiving side is grounded when the added signal sending circuit is placed opposite the existing receiving circuit package and the receiving side is grounded, the drive IC etc. will be destroyed. there is a possibility.
【００１４】図７は空き信号線に信号送出回路を構成す
るドライブＩＣまたは信号受信回路を構成するレシーブ
ＩＣを付加したパッケージを「新」、空き信号線が接地
された状態となっているパッケージを「旧」として信号
送受信回路パッケージの新旧の組合せパターンを示した
ものである。FIG. 7 shows a "new" package in which a drive IC constituting a signal sending circuit or a receive IC constituting a signal receiving circuit is added to an empty signal line, and a package in which an empty signal line is grounded. "Old" indicates a combination pattern of old and new signal transmitting/receiving circuit packages.
【００１５】図７から明らかなように、相手パッケージ
において接地されていることを想定せずに付加されたド
ライブＩＣ４２またはレシーブＩＣ４４が破壊する可能
性があるのは（２） の組合せ、即ち、信号送信回路パ
ッケージが新で信号受信回路パッケージが旧の組合せの
みであり、破壊する可能性があるのはドライブＩＣ４２
である。As is clear from FIG. 7, the combination of (2), that is, the signal There is only a combination of a new transmitter circuit package and an old signal receiver circuit package, and it is the drive IC42 that may be destroyed.
It is.
【００１６】従って、信号送信回路パッケージ４１Ａ
は、図７の（２）のような接続を行ってもドライブＩＣ
４２が破壊しないような回路構成としておく必要がある
。これに対して図３の信号送信回路パッケージ２１は、
信号受信回路パッケージ３１の入力端子３６に地気が接
続されていると永久破壊となる可能性がある。これを防
ぐためにドライブＩＣ２２をオープンコレクタか高イン
ピーダンス回路とする方法があるが、これらの回路は通
常、伝送ケーブルに対して用いられないため、以下にお
いては論理レベルでの信号送受信を前提に出力保護を行
う方法を考える。Therefore, the signal transmitting circuit package 41A
Even if the connection as shown in (2) in Figure 7 is made, the drive IC
It is necessary to have a circuit configuration in which 42 is not destroyed. On the other hand, the signal transmission circuit package 21 in FIG.
If earth air is connected to the input terminal 36 of the signal receiving circuit package 31, permanent damage may occur. To prevent this, there is a way to make the drive IC 22 an open collector or a high impedance circuit, but since these circuits are usually not used for transmission cables, the output protection below assumes that signals are transmitted and received at a logic level. Think about how to do it.
【００１７】上記出力保護の方法としてはＴＴＬ−ＩＣ
であるドライブＩＣ２２の出力部に図３に示すような電
流制限用の抵抗ＲＴを挿入するのが効果的であり、抵抗
ＲＴの値を適当に設定すれば、出力端子２４に地気が接
続されてもドライブＩＣ２２の出力電流を該ＩＣに許容
される最大出力電流以下に抑えることが可能となる。[0017] As a method of output protection, TTL-IC
It is effective to insert a current limiting resistor RT as shown in FIG. However, the output current of the drive IC 22 can be suppressed below the maximum output current allowed by the IC.
【００１８】しかし、抵抗ＲＴを挿入すると、図５の■
に示すように信号電流の最大値が下降して最小値が上昇
し、スレショールド電圧のＶＨ 以上、及びＶＬ 以下
の条件を満たせなくなる可能性がある。また、抵抗ＲＴ
が伝送ケーブルの容量性インピーダンスと組合せられて
フィルタの効果をもつため、信号波形の立ち上がり及び
立ち下がり部分が緩やかとなり、高周波成分が減衰する
。これらにより正常な伝送ができなくなったり、伝送可
能な距離が短くなる。従って、図３の回路で出力保護と
伝送特性の両方を満足することは困難である。However, if the resistor RT is inserted,
As shown in the figure, the maximum value of the signal current decreases and the minimum value increases, and there is a possibility that the conditions of the threshold voltage of VH or more and VL or less cannot be satisfied. Also, resistance RT
Since this is combined with the capacitive impedance of the transmission cable and has a filter effect, the rise and fall portions of the signal waveform become gentle and the high frequency components are attenuated. These may prevent normal transmission or shorten the possible transmission distance. Therefore, it is difficult to satisfy both output protection and transmission characteristics with the circuit shown in FIG.
【００１９】一方、図４のＶ．１１方式は論理レベルに
よる信号伝送を行わないため、信号送信回路パッケージ
１Ａ内の信号線に抵抗が挿入されても信号伝送が満足に
行われる可能性があるが、従来技術においては上記のよ
うな電流制限抵抗は挿入されていない。従って、信号受
信回路パッケージ１１の入力端子１６が接地されている
場合には信号送信回路パッケージ２内のドライブＩＣ２
が破壊する可能性が高い。On the other hand, V. of FIG. Since the No. 11 method does not transmit signals based on logic levels, there is a possibility that signal transmission will be performed satisfactorily even if a resistor is inserted into the signal line in the signal transmitting circuit package 1A. No current limiting resistor is inserted. Therefore, when the input terminal 16 of the signal receiving circuit package 11 is grounded, the drive IC 2 in the signal transmitting circuit package 2
is likely to be destroyed.
【００２０】以上の状況を勘案し、信号線が地気に接続
されている信号受信回路パッケージに接続されても破壊
することがない信号送信回路が必要となっている。In view of the above circumstances, there is a need for a signal transmitting circuit that will not be destroyed even if it is connected to a signal receiving circuit package whose signal line is connected to the ground.
【００２１】[0021]
【発明が解決しようとする課題】従来技術においては、
使用されていない信号線を利用して機能拡張を行うため
に新たに付加した信号送出回路が、信号線が接地された
既存の信号受信回路パッケージに接続された場合に信号
送出回路が破壊する可能性があった。また、ＴＴＬ方式
による信号伝送で上記の破壊を防ぐために抵抗などによ
る出力保護回路を追加すると信号伝送特性が劣化するた
め、出力保護と伝送特性の両方を満足することが困難で
あった。[Problem to be solved by the invention] In the prior art,
If a newly added signal transmission circuit that is added to expand functionality by using an unused signal line is connected to an existing signal reception circuit package whose signal line is grounded, the signal transmission circuit may be destroyed. There was sex. Furthermore, if an output protection circuit such as a resistor is added to prevent the above-mentioned destruction in signal transmission using the TTL method, the signal transmission characteristics deteriorate, making it difficult to satisfy both output protection and transmission characteristics.
【００２２】本発明は、出力側に地気が接続された場合
に破壊せず、かつ、信号伝送特性の劣化が少ない信号送
信回路を提供することを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide a signal transmitting circuit that does not break down when earth air is connected to its output side, and whose signal transmission characteristics are less degraded.
【００２３】[0023]
【課題を解決するための手段】図１は本発明の基本構成
図である。図中、１は信号送信回路、２はＣＣＩＴＴの
勧告Ｖ．１１に従った平衡複流式の信号を出力する平衡
複流式信号送出回路、３は伝送路、４は前記平衡複流式
信号送出回路２の出力信号を伝送する２本の信号線、５
は前記２本の信号線４にそれぞれ直列に出力電流を制限
する素子を挿入する出力保護回路である。[Means for Solving the Problems] FIG. 1 is a basic configuration diagram of the present invention. In the figure, 1 is a signal transmission circuit, 2 is CCITT recommendation V. 11, a balanced double-current signal transmission circuit that outputs a balanced double-current signal according to 11; 3 is a transmission line; 4 is two signal lines that transmit the output signal of the balanced double-current signal transmission circuit 2; 5;
is an output protection circuit in which an element for limiting the output current is inserted in series with each of the two signal lines 4.
【００２４】[0024]
【作用】図１において、平衡複流式信号送出回路２より
出力される信号は出力保護回路５を経て伝送路３に送信
される。出力保護回路５は平衡複流式信号送出回路２よ
りの２本の信号線４に直列に出力電流を制限する素子（
図示省略）を挿入するため、伝送路３を経た信号受信回
路（図示省略）において信号線４が地気に接続されても
出力電流が制限される。このため、平衡複流式信号送出
回路２が破壊されることがない。[Operation] In FIG. 1, the signal output from the balanced double-current signal sending circuit 2 is sent to the transmission line 3 via the output protection circuit 5. The output protection circuit 5 includes an output current limiting element (
(not shown), the output current is limited even if the signal line 4 is connected to the ground in the signal receiving circuit (not shown) via the transmission line 3. Therefore, the balanced double-current signal sending circuit 2 is not destroyed.
【００２５】[0025]
【実施例】図２は本発明の実施例回路ブロック図及び接
続図である。全図を通じて同一対象物は同一記号をもっ
て示し、１は信号送信回路パッケージ、１１は信号受信
回路パッケージ、２は平衡複流式信号送出回路を実現す
るＶ．１１送信素子（ドライブＩＣ）、１２は平衡複流
式信号受信回路を実現するＶ．１１受信素子（レシーブ
ＩＣ）である。３は伝送路で、具体的には伝送ケーブル
またはパッケージ相互間を接続するプリント配線である
。
また、１７は終端回路、Ｒ１，Ｒ２は出力保護回路５内
に設けられ、Ｖ．１１送信素子の出力電流を制限する素
子として使用される出力電流制限抵抗、Ｒ３〜Ｒ５は終
端回路１７を構成する抵抗、Ｃは同じくコンデンサであ
る。Embodiment FIG. 2 is a circuit block diagram and a connection diagram of an embodiment of the present invention. The same objects are shown with the same symbols throughout the figures, 1 is a signal transmitting circuit package, 11 is a signal receiving circuit package, and 2 is a V. 11 is a transmitting element (drive IC), and 12 is a V.I. 11 receiving elements (receive ICs). Reference numeral 3 denotes a transmission path, specifically a transmission cable or printed wiring that connects the packages. Further, 17 is a termination circuit, R1 and R2 are provided in the output protection circuit 5, and V. Output current limiting resistors used as elements for limiting the output current of the transmitting elements 11, R3 to R5 are resistors forming the termination circuit 17, and C is also a capacitor.
【００２６】図２の（１） は本発明の実施例である信
号送信回路パッケージ１が信号受信を正常に行う信号受
信回路パッケージ１１に接続された状態を示している。
図２の信号送信回路パッケージ１は図４の従来技術の信
号送信回路パッケージ１Ａに抵抗Ｒ１，Ｒ２が挿入され
た回路となっているため、２本の信号線４の各々の線に
送出される信号の波形は図５の■に示した傾向をもつ。
しかし、信号受信回路パッケージ１１のレシーブＩＣ１
２は＋側と−側の入力レベルの差により出力の論理レベ
ル“１”， “０”を決定するため、各信号線の信号レ
ベルがスレッショルド電圧のＶＨ 以上またはＶＬ 以
下となっても両信号のレベル差がある程度（例えば０．
３Ｖ）確保できれば正常に動作することができる。この
ため、出力保護回路５が挿入されても信号伝送特性が大
きく劣化することがない。FIG. 2 (1) shows a state in which a signal transmitting circuit package 1 according to an embodiment of the present invention is connected to a signal receiving circuit package 11 that normally receives signals. Since the signal transmitting circuit package 1 of FIG. 2 is a circuit in which resistors R1 and R2 are inserted in the conventional signal transmitting circuit package 1A of FIG. 4, the signal is sent to each of the two signal lines 4. The signal waveform has the tendency shown in ■ in FIG. However, the receive IC 1 of the signal receiving circuit package 11
2 determines the output logic level "1" or "0" based on the difference between the input levels on the + side and the - side, so even if the signal level of each signal line is above the threshold voltage VH or below the threshold voltage, both signals There is a certain level difference (for example, 0.
If 3V) can be secured, it can operate normally. Therefore, even if the output protection circuit 5 is inserted, the signal transmission characteristics will not deteriorate significantly.
【００２７】図２の（２） は信号送信回路パッケージ
１が信号線が接地された信号受信回路パッケージ１１に
接続された状態を示している。この例は信号受信回路パ
ッケージ１１Ａにおいて信号線が接地されていないこと
を想定して信号送受信回路を接続したときに生ずるもの
である。
２本の信号線４は信号受信回路パッケージ１１Ａにおい
て接地されているためドライブＩＣ２には大きな電流が
流れるが、抵抗Ｒ１，Ｒ２が挿入されているため電流値
は一定限度以上にはならない。この一定限度の電流がド
ライブＩＣの最大許容電流以下となるように抵抗Ｒ１，
Ｒ２の値を設定すれば、図２の（２） の状態が生じて
もドライブＩＣが破壊することはない。FIG. 2 (2) shows a state in which the signal transmitting circuit package 1 is connected to the signal receiving circuit package 11 whose signal line is grounded. This example occurs when the signal transmitting/receiving circuit is connected in the signal receiving circuit package 11A assuming that the signal line is not grounded. Since the two signal lines 4 are grounded in the signal receiving circuit package 11A, a large current flows through the drive IC 2, but since the resistors R1 and R2 are inserted, the current value does not exceed a certain limit. Resistor R1, so that this certain limit current is below the maximum allowable current of the drive IC,
If the value of R2 is set, the drive IC will not be destroyed even if the condition (2) in FIG. 2 occurs.
【００２８】以上のように、本発明によれば信号線が接
地された信号受信回路パッケージと接続した場合でも信
号送信回路パッケージのドライブＩＣが破壊することが
なく、かつ、信号電流を制限する素子を挿入することに
より信号伝送特性が大幅に劣化することがない。As described above, according to the present invention, even when the signal line is connected to a grounded signal receiving circuit package, the drive IC of the signal transmitting circuit package is not destroyed, and an element that limits the signal current is provided. By inserting this, signal transmission characteristics do not deteriorate significantly.
【００２９】以上、図２により本発明の実施例を説明し
たが、図２はあくまで本発明の一実施例を示したものに
過ぎず、本発明は図２に限定されるものでない。例えば
、図２においては信号送信回路及び信号受信回路をそれ
ぞれＶ．１１送信素子２及びＶ．１１受信素子１２のみ
で示しているが、信号送受信回路には各種の構成があり
、本発明が図２に示したもののみに限定されないことは
勿論である。Although the embodiment of the present invention has been described above with reference to FIG. 2, FIG. 2 merely shows one embodiment of the present invention, and the present invention is not limited to FIG. For example, in FIG. 2, the signal transmitting circuit and the signal receiving circuit are each connected to V. 11 transmitting element 2 and V.11 transmitting element 2 and V.11 transmitting element 2; Although only 11 receiving elements 12 are shown, there are various configurations of the signal transmitting/receiving circuit, and it goes without saying that the present invention is not limited to only the one shown in FIG.
【００３０】[0030]
【発明の効果】以上説明したように、本発明によれば、
使用されていない信号線を利用して機能拡張を行うため
に新たに付加した信号送出回路を、信号線が接地された
既存の信号受信回路パッケージと接続した場合に前記信
号送出回路が破壊することがなく、かつ、信号送出回路
の破壊を防ぐ出力保護回路の使用により信号伝送特性が
大きく劣化することがない。このため、空き信号線を利
用した機能拡張が破壊の恐れなく実施でき、かかる信号
送信回路を使用する通信の機能向上と信頼性の向上に大
きく貢献する。[Effects of the Invention] As explained above, according to the present invention,
When a newly added signal sending circuit added to expand functionality using an unused signal line is connected to an existing signal receiving circuit package whose signal line is grounded, the signal sending circuit is destroyed. Moreover, by using an output protection circuit that prevents damage to the signal transmission circuit, signal transmission characteristics do not deteriorate significantly. Therefore, functional expansion using vacant signal lines can be carried out without fear of destruction, which greatly contributes to improving the functionality and reliability of communications using such signal transmission circuits.
【図１】 本発明の基本構成図[Figure 1] Basic configuration diagram of the present invention
【図２】 本発明の実施例回路ブロック図及び接続図
[Figure 2] Example circuit block diagram and connection diagram of the present invention
【図３】 従来技術の信号送受信回路構成図（ＴＴＬ
方式）[Figure 3] Conventional technology signal transmitting/receiving circuit configuration diagram (TTL
method)
【図４】 従来技術の信号送受信回路構成図（Ｖ．１
１方式）[Figure 4] Configuration diagram of signal transmitting/receiving circuit of conventional technology (V.1
1 method)
【図５】 従来技術の信号送受信回路信号波形図（Ｔ
ＴＬ方式）[Figure 5] Signal waveform diagram of the signal transmitting/receiving circuit of the prior art (T
TL method)
【図６】 従来技術の信号送受信回路信号波形図（Ｖ
．１１方式）[Figure 6] Signal waveform diagram of the signal transmitting/receiving circuit of the prior art (V
．． 11 methods)
【図７】 信号送受信回路パッケージ組合せ図[Figure 7] Signal transmission/reception circuit package combination diagram
１ 信号送信回路 ２ 平衡複流式信号送出回路 ３ 伝送路 ４ 信号線 ５ 出力保護回路 1 Signal transmission circuit 2 Balanced double flow signal sending circuit 3 Transmission line 4 Signal line 5 Output protection circuit
Claims (1)
出力される信号を伝送路（３） に送出する信号送信回
路（１） において、前記平衡複流式信号送出回路（２
） の出力信号を伝送する２本の信号線（４） にそれ
ぞれ直列に出力電流を制限する素子を挿入する出力保護
回路（５） を備えたことを特徴とする出力保護回路付
き信号送信回路。Claim 1: A signal transmitting circuit (1) for transmitting a signal output from a balanced double-current signal transmitting circuit (2) to a transmission path (3), wherein the balanced double-current signal transmitting circuit (2)
1. A signal transmission circuit with an output protection circuit, characterized in that it is equipped with an output protection circuit (5) in which an element for limiting output current is inserted in series with each of two signal lines (4) for transmitting an output signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3142201A JPH04367139A (en) | 1991-06-14 | 1991-06-14 | Signal transmission circuit with output protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3142201A JPH04367139A (en) | 1991-06-14 | 1991-06-14 | Signal transmission circuit with output protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04367139A true JPH04367139A (en) | 1992-12-18 |
Family
ID=15309746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3142201A Withdrawn JPH04367139A (en) | 1991-06-14 | 1991-06-14 | Signal transmission circuit with output protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04367139A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004096351A (en) * | 2002-08-30 | 2004-03-25 | Canon Inc | Terminating circuit for differential signal transmission line |
| WO2007125965A1 (en) * | 2006-04-27 | 2007-11-08 | Panasonic Corporation | Multiplex differential transmission system |
| WO2007125964A1 (en) * | 2006-04-27 | 2007-11-08 | Panasonic Corporation | Multiple differential transmission system |
| WO2016108265A1 (en) * | 2014-12-29 | 2016-07-07 | ソニー株式会社 | Communication device and communication method |
-
1991
- 1991-06-14 JP JP3142201A patent/JPH04367139A/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004096351A (en) * | 2002-08-30 | 2004-03-25 | Canon Inc | Terminating circuit for differential signal transmission line |
| WO2007125965A1 (en) * | 2006-04-27 | 2007-11-08 | Panasonic Corporation | Multiplex differential transmission system |
| WO2007125964A1 (en) * | 2006-04-27 | 2007-11-08 | Panasonic Corporation | Multiple differential transmission system |
| US7692563B2 (en) | 2006-04-27 | 2010-04-06 | Panasonic Corporation | Multiple differential transmission system including signal transmitter and signal receiver connected via three signal lines |
| WO2016108265A1 (en) * | 2014-12-29 | 2016-07-07 | ソニー株式会社 | Communication device and communication method |
| US10154231B2 (en) | 2014-12-29 | 2018-12-11 | Sony Corporation | Communication device and communication method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Application deemed to be withdrawn because no request for examination was validly filed |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19980903 |