JPS6238387Y2 - - Google Patents
Info
- Publication number
- JPS6238387Y2 JPS6238387Y2 JP11031783U JP11031783U JPS6238387Y2 JP S6238387 Y2 JPS6238387 Y2 JP S6238387Y2 JP 11031783 U JP11031783 U JP 11031783U JP 11031783 U JP11031783 U JP 11031783U JP S6238387 Y2 JPS6238387 Y2 JP S6238387Y2
- Authority
- JP
- Japan
- Prior art keywords
- power supply
- transmission
- camera
- distance
- cable
- 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
- 230000005540 biological transmission Effects 0.000 claims description 17
- 230000008054 signal transmission Effects 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 6
- 238000009434 installation Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
Landscapes
- Closed-Circuit Television Systems (AREA)
- Dc Digital Transmission (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Description
【考案の詳細な説明】
〔技術分野〕
本考案は映像信号伝送用の同軸ケーブルのよう
なケーブルと同一のケーブルに重畳して電源を供
給するようにした所謂電源重畳型の映像情報信号
伝送システムに関するものである。[Detailed description of the invention] [Technical field] The present invention is a so-called power supply superimposed type video information signal transmission system in which power is supplied superimposed on the same cable as a coaxial cable for video signal transmission. It is related to.
最近、増々情報化する社会傾向にあつて、ホー
ムコンピユータとかCATVシステムのように、マ
ンシヨン、ビル、家庭内等の情報システムの発達
には目覚しいものがある。このような中で、イン
ターホン、ドアホン等の音声信号や、TVインタ
ーホンおよびモニター用TV、あるいは防犯、防
火等のセキユリテイ情報データの授受を同軸ケー
ブル、光フアイバー等の1本のケーブルを介して
行う情報伝送システムの普及が進行している。そ
こでこのような情報伝送システムにおいて、映像
情報信号の伝送システムについて考えると、一般
に第1図のようなTVカメラ1からモニターTV受
像機3迄の映像情報信号伝送距離が長くなると、
ケーブル2の分布定数の影響によつて、その伝送
信号の高域成分が低下する。そしてこの周波数高
域成分の劣化にともない、画像の鮮鋭度が実質的
に低下するのである。そこでこの周波数高域成分
の劣化を補償する為に現在は、あらかじめTVカ
メラ1側で画像信号のステツプ応答波形に適度な
プレシユートとオーバーシユートとを付加するこ
とによつて高域成分を強調した信号を伝送してい
る。即ち第2図に示す画像信号周波数特性におい
て、信号伝送距離が長い程、同図中のa,b,c
の順で高域成分が劣化する、その為同図aの如く
高域成分のレベルをあらかじめ上げて伝送するの
である。さらに具体的には、第3図aのような正
常な画像信号波形に対し、予め同図bの如く、画
像信号のステツプ応答波形に適度なプレシユート
とオーバーシユートを付加し、これを伝送するも
のであり、従来はこの高域補償の度合は、伝送距
離に応じて適当な値を設定していた。なお第3図
cは高域成分劣化時の波形である。また第1図従
来例において、4は直流電源であつて、モニター
TV受像機3側に設けられたTVカメラ1駆動用の
電源であり、配線コスト節減のためにベースバン
ド信号として伝送される映像信号と同一のケーブ
ル2によりTVカメラ1側に供給されるものであ
り、従つてケーブル2上に伝送信号は第5図のよ
うな電源重畳画像信号となる。
Recently, as society has become more and more information-oriented, there has been a remarkable development of information systems in apartments, buildings, homes, etc., such as home computers and CATV systems. Under these circumstances, information is transmitted and received via a single cable such as a coaxial cable or optical fiber, such as audio signals from intercoms and door phones, TV intercoms and monitor TVs, and security information data such as crime prevention and fire prevention. Transmission systems are becoming more popular. Therefore, in such an information transmission system, when considering the video information signal transmission system, generally speaking, as the video information signal transmission distance from the TV camera 1 to the monitor TV receiver 3 as shown in Fig. 1 increases,
Due to the influence of the distributed constant of the cable 2, the high frequency components of the transmission signal are reduced. As the high-frequency components deteriorate, the sharpness of the image substantially decreases. Therefore, in order to compensate for the deterioration of this high frequency component, the current method is to emphasize the high frequency component by adding appropriate preshoot and overshoot to the step response waveform of the image signal on the TV camera 1 side. transmitting a signal. In other words, in the image signal frequency characteristics shown in Figure 2, the longer the signal transmission distance, the more
The high-frequency components deteriorate in this order. Therefore, the level of the high-frequency components is raised in advance and transmitted as shown in a in the same figure. More specifically, for a normal image signal waveform as shown in Figure 3a, appropriate preshoot and overshoot are added in advance to the step response waveform of the image signal as shown in Figure 3b, and this is transmitted. Conventionally, the degree of high frequency compensation has been set to an appropriate value depending on the transmission distance. Note that FIG. 3c shows a waveform when the high frequency component is degraded. In addition, in the conventional example in Fig. 1, 4 is a DC power supply, and a monitor
This is the power supply for driving the TV camera 1 installed on the TV receiver 3 side, and is supplied to the TV camera 1 side through the same cable 2 as the video signal transmitted as a baseband signal in order to reduce wiring costs. Therefore, the transmission signal on the cable 2 becomes a power superimposed image signal as shown in FIG.
かくて上述のような従来例においては、TVカ
メラからモニターTV受像機までの伝送距離に応
じてその都度伝送映像信号の高域補償の度合を設
定しなければならない問題があり、設置工事が煩
雑化しこの初期設定を誤ると鮮明な画像を送るこ
とができなくなるおそれがある問題があつた。 Thus, in the conventional example described above, there is a problem in that the degree of high-frequency compensation of the transmitted video signal must be set each time according to the transmission distance from the TV camera to the monitor TV receiver, making the installation work complicated. There was a problem that if this initial setting was incorrect, it might not be possible to send a clear image.
本考案は伝送距離長を自動的に検知してこの伝
送距離に合せて高域補償を行うようにし、常に鮮
明な画像をモニタできるようにするとともに設置
工事を簡素化できるようにした映像情報信号伝送
システムを提供することを目的とするものであ
る。
This invention automatically detects the length of the transmission distance and performs high-frequency compensation according to this transmission distance, making it possible to always monitor clear images and simplify the installation work for video information signals. The purpose is to provide a transmission system.
第4図は本考案一実施例のブロツク図を示すも
のであつて、第1図従来例と同様に、モニター
TV受像機3側の直流電源4からケーブル2を介
してTVカメラ1にその作動用電源を送り込むと
ともに、TVカメラ1出力の画像信号を上記ケー
ブル2を介してモニターTV受像機3側に送るよ
うにしたものであり、このとき上記ケーブル2に
よる伝送距離が長くなればなるほど、TVカメラ
1側で検出したケーブル2上の第5図に示すよう
な電源重畳画像信号における直流電圧成分は電圧
降下により降下しているため、この直流電圧の降
下分を電源検知回路6で検出して映像信号の伝送
距離を把握し、この電源検知回路6出力で画質調
節回路5を制御するものであり、伝送距離が長い
程プレシユート、オーバーシユートのレベルを大
きくして高域成分の補償を行うものである。
FIG. 4 shows a block diagram of an embodiment of the present invention, in which, like the conventional example shown in FIG.
The operating power is sent from the DC power supply 4 on the TV receiver 3 side to the TV camera 1 via the cable 2, and the image signal output from the TV camera 1 is sent via the cable 2 to the monitor TV receiver 3 side. At this time, the longer the transmission distance by the cable 2, the more the DC voltage component in the power superimposed image signal detected by the TV camera 1 on the cable 2 as shown in Figure 5 will decrease due to voltage drop. This DC voltage drop is detected by the power supply detection circuit 6 to determine the transmission distance of the video signal, and the output of this power supply detection circuit 6 controls the image quality adjustment circuit 5, which determines the transmission distance. The longer the , the higher the preshoot and overshoot levels are to compensate for the high frequency components.
第6図に示す本考案の一実施例を説明する。ま
ず画質調節回路5は、トランジスタTrのコレク
タに接続されたインダクタンスLo及びコンデン
サCoによつてTVカメラ1出力の2次微分波形を
得ているものであり、これを抵抗R1,R2で分圧
して〜の出力を得る。ここでの位置ではプ
レシユートとオーバーシユートのレベルが大きい
ステツプ応答波形が得られ、の位置では上記
の場合より小さいが同様波形が得られるものであ
り、また、の位置では波形ひずみのない応答が
得られるようにしてある。そこでこれら〜の
位置からの出力波形を各々アナログスイツチ
SW1,SW2,SW3で制御することによつて、各々
遠距離・中距離・近距離の場合分けを行ない出力
するのである。次に第5図のような電源重畳信号
を入力する電源検知回路6においては、まずロー
ピークホルド回路16によつて第5図信号波形中
の直流電圧(DCV)を検知し、その値があらか
じめ設定した基準電圧(V1,V2,V3)の値に対し
てどのような関係にあるかをコンパレータ7,
8,9で比較し、直流電圧(DCV)の値がV3以
上の時は近距離と判断してアナログスイツチSW1
をオンし、また直流電圧(DCV)がV2〜V3のと
きは中距離と判断してアナログスイツチSW1をオ
ンにし、さらに直流電圧(DCV)がV1〜V2のと
きに遠距離と判断してアナログスイツチSW1をオ
ンするように制御するものであり、これらの判断
制御動作は2個のインバータ10,11と2個の
アンドゲート12,13とよりなるゲート回路1
4により行なわれる。なお図中15は基準電圧発
生部であり、前述の基準電圧V1〜V3を発生す
る。また上述の実施例では、画質調節を遠、中、
近距離の3段階に分けて切換えたが、さらに多段
階に分解する等、適宜の段階分けによる画質調整
を行つても良い。 An embodiment of the present invention shown in FIG. 6 will be described. First, the image quality adjustment circuit 5 obtains a second-order differential waveform of the TV camera 1 output by an inductance Lo and a capacitor Co connected to the collector of the transistor Tr, and divides this by resistors R 1 and R 2 . Press to get the output of ~. At this position, a step response waveform with large preshoot and overshoot levels is obtained, at position , a similar waveform is obtained although smaller than in the above case, and at position , a response with no waveform distortion is obtained. It's made so that you can get it. Therefore, the output waveforms from these ~ positions are converted to analog switches.
By controlling SW 1 , SW 2 , and SW 3 , the output is divided into long distance, medium distance, and short distance, respectively. Next, in the power supply detection circuit 6 which inputs the power supply superimposed signal as shown in FIG. 5, the low peak hold circuit 16 first detects the direct current voltage (DCV) in the signal waveform shown in FIG. The comparator 7 ,
8 and 9, and if the DC voltage (DCV) value is V 3 or higher, it is determined that the distance is close and the analog switch SW 1 is set.
, and when the DC voltage (DCV) is V 2 to V 3 , it is determined that the distance is medium, and analog switch SW 1 is turned on, and when the DC voltage (DCV) is V 1 to V 2 , it is determined that the distance is medium. These judgment control operations are performed by a gate circuit 1 consisting of two inverters 10, 11 and two AND gates 12, 13.
4. Note that 15 in the figure is a reference voltage generating section, which generates the aforementioned reference voltages V 1 to V 3 . In addition, in the above-mentioned embodiment, the image quality can be adjusted from far to medium.
Although switching is performed in three stages of short distance, the image quality may be adjusted in appropriate stages, such as by further dividing into multiple stages.
本考案は上述のように構成したものであるか
ら、設置状態等により映像信号の伝送距離が異な
るような場合においても、常にそのときの伝送距
離に応じた調整補償を施して信号伝送を行うこと
ができ、設置工事を煩雑化することなくしかも常
に鮮明な画像をモニタすることができるようにな
る効果を有する。
Since the present invention is configured as described above, even if the transmission distance of the video signal varies depending on the installation condition, etc., signal transmission can be performed with adjustment and compensation always performed according to the transmission distance at that time. This has the effect of making it possible to always monitor clear images without complicating installation work.
第1図は従来例のブロツク図、第2図は画像信
号の周波数特性図、第3図a〜cは夫々正常画像
信号、高域成分補償画像信号、高域成分劣化画像
信号の波形図、第4図は本考案の一実施例のブロ
ツク図、第5図は電源重畳画像信号の波形図、第
6図は本考案の一実施例の主要部の具体回路例図
であり、1はTVカメラ、2はケーブル、3はモ
ニターTV受像機、4は電源検知回路、5は画質
調節回路である。
FIG. 1 is a block diagram of a conventional example, FIG. 2 is a frequency characteristic diagram of an image signal, and FIGS. 3 a to 3 are waveform diagrams of a normal image signal, a high-frequency component compensated image signal, and a high-frequency component degraded image signal, respectively. FIG. 4 is a block diagram of an embodiment of the present invention, FIG. 5 is a waveform diagram of a power supply superimposed image signal, FIG. 2 is a cable, 3 is a monitor TV receiver, 4 is a power supply detection circuit, and 5 is an image quality adjustment circuit.
Claims (1)
ーTV受像機へ映像信号を伝送するとともに、前
記TVカメラの電源を前記ケーブルを介して前記
モニターTV受像機側から供給するようにした電
源重畳型の映像情報信号伝送システムにおいて、
前記TVカメラ側に伝送電源の電圧降下を検知す
る電源検知回路と前記伝送画像の鮮鋭度を調節す
る画質調節回路とを設け、電源検知回路で検出し
た電圧降下より伝送距離を把握してその伝送距離
に応じて上記画質調節回路により鮮明度を自動的
に調整補償するようにして成ることを特徴とする
映像情報信号伝送システム。 A power supply superimposed image display in which a video signal is transmitted from a TV camera to a monitor TV receiver via a single cable, and power to the TV camera is supplied from the monitor TV receiver via the cable. In information signal transmission systems,
A power supply detection circuit for detecting a voltage drop in the transmission power supply and an image quality adjustment circuit for adjusting the sharpness of the transmitted image are provided on the TV camera side, and the transmission distance is determined from the voltage drop detected by the power supply detection circuit and the transmission is performed. A video information signal transmission system characterized in that the image quality adjustment circuit automatically adjusts and compensates for the sharpness according to the distance.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11031783U JPS6019277U (en) | 1983-07-15 | 1983-07-15 | Video information signal transmission system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11031783U JPS6019277U (en) | 1983-07-15 | 1983-07-15 | Video information signal transmission system |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6019277U JPS6019277U (en) | 1985-02-09 |
JPS6238387Y2 true JPS6238387Y2 (en) | 1987-09-30 |
Family
ID=30256609
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11031783U Granted JPS6019277U (en) | 1983-07-15 | 1983-07-15 | Video information signal transmission system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6019277U (en) |
-
1983
- 1983-07-15 JP JP11031783U patent/JPS6019277U/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS6019277U (en) | 1985-02-09 |
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