JPH0583589A - External synchronizing device - Google Patents
External synchronizing deviceInfo
- Publication number
- JPH0583589A JPH0583589A JP24158091A JP24158091A JPH0583589A JP H0583589 A JPH0583589 A JP H0583589A JP 24158091 A JP24158091 A JP 24158091A JP 24158091 A JP24158091 A JP 24158091A JP H0583589 A JPH0583589 A JP H0583589A
- Authority
- JP
- Japan
- Prior art keywords
- synchronizing signal
- external
- input terminal
- input
- terminating
- 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.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は映像信号の外部同期装置
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external synchronizing device for video signals.
【０００２】[0002]
【従来の技術】ビデオカメラなどの映像機器において、
ビデオ・バースト・シンク（ＶＢＳ）やビデオ・シンク
（ＶＳ）などの信号を外部同期信号として使用する場
合、７５オームの抵抗で終端することが多い。2. Description of the Related Art In video equipment such as video cameras,
When signals such as video burst sync (VBS) and video sync (VS) are used as external synchronization signals, they are often terminated with a 75 ohm resistor.
【０００３】[0003]
【発明が解決しようとする課題】しかし、７５オームの
抵抗で終端すると、信号レベルが減少する。従って、複
数台の映像機器を１つのＶＢＳやＶＳでそのまま接続す
ることはできない。また、１台のビデオカメラの信号を
ＶＢＳとして使用すると、その信号レベルが減少し、ビ
デオモニタでの映像が暗くなる問題がある。However, termination with a 75 ohm resistor reduces the signal level. Therefore, it is not possible to directly connect a plurality of video devices with one VBS or VS. Further, when the signal of one video camera is used as VBS, there is a problem that the signal level is reduced and the image on the video monitor becomes dark.
【０００４】一方、７５オームの抵抗による終端をや
め、ハイインピーダンスで受けることにより、上述の問
題を解消することができる。しかし、外部同期信号を入
力しない場合、ノイズの影響を受けやすい不具合が生じ
る。例えば、入力端子を触ったり、外部からの電気的ノ
イズで、外部同期回路が誤動作して映像の同期が乱れる
ことになる。On the other hand, the above-mentioned problem can be solved by stopping the termination by the resistance of 75 ohms and receiving it with high impedance. However, when the external synchronizing signal is not input, there is a problem that it is easily affected by noise. For example, the external synchronization circuit malfunctions due to touching the input terminal or electrical noise from the outside, and the synchronization of the image is disturbed.
【０００５】本発明はこのような点に着目してなされた
ものであり、その目的は、外部同期信号を入力したとき
に信号のレベルを減少させずに、かつ外部同期信号を入
力しないときにも外乱に強い外部同期装置を提供するこ
とにある。The present invention has been made paying attention to such a point, and an object thereof is to not reduce the signal level when an external synchronizing signal is input and to not input the external synchronizing signal. Is to provide an external synchronizer that is resistant to disturbance.
【０００６】[0006]
【課題を解決するための手段】上記課題を解決する本発
明は、外部から与えられる外部同期信号を受ける同期信
号入力端子と、同期信号入力端子へ外部同期信号が与え
られているか否かを検出する検出手段と、同期信号入力
端子を終端させる終端手段と、同期信号入力端子を終端
手段により終端する若しくは開放する切り換えを行なう
切り換え手段とを備え、切り換え手段は外部同期信号の
入力が検出されたときに同期信号入力端子を開放し、外
部同期信号の入力が検出されないときに同期信号入力手
段を終端手段により終端させることを特徴とするもので
ある。The present invention for solving the above problems detects a sync signal input terminal for receiving an external sync signal from the outside and whether or not the external sync signal is applied to the sync signal input terminal. Detecting means, terminating means for terminating the synchronizing signal input terminal, and switching means for terminating or opening the synchronizing signal input terminal by the terminating means, and the switching means detects the input of the external synchronizing signal. The sync signal input terminal is sometimes opened, and the sync signal input means is terminated by the termination means when the input of the external sync signal is not detected.
【０００７】[0007]
【作用】外部同期信号の入力がない状態では、切り換え
手段はオン状態になっており、終端手段により終端され
ており、同期信号入力端子から見た入力インピーダンス
は所定の値になっている。同期信号入力端子に外部同期
信号が入ると、検出手段は外部同期信号の入力を検出
し、切り換え手段は開放される。これにより、外部同期
信号をハイインピーダンスで受けることになり、入力段
階での減衰が極力抑えられる。When there is no input of the external synchronizing signal, the switching means is in the ON state and terminated by the terminating means, and the input impedance seen from the synchronizing signal input terminal has a predetermined value. When the external synchronizing signal is input to the synchronizing signal input terminal, the detecting means detects the input of the external synchronizing signal and the switching means is opened. As a result, the external synchronizing signal is received with high impedance, and the attenuation at the input stage is suppressed as much as possible.
【０００８】[0008]
【実施例】以下、図面を参照して本発明の外部同期装置
の実施例を詳細に説明する。図１は本発明の一実施例の
構成を示す構成図である。この図において、１は入力端
子Ｔに対する終端抵抗、２は終端抵抗による終端若しく
は開放を行なうアナログスイッチ、３はバッファ回路、
４は外部から与えられる同期信号（外部同期信号）に同
期した同期信号を発生する外部同期回路、５は外部同期
回路４から同期信号が出力されたことを検出したときに
アナログスイッチ２を開放し、それ以外にアナログスイ
ッチ２をオン状態にする検出・制御回路である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an external synchronizing apparatus of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing the configuration of an embodiment of the present invention. In the figure, 1 is a terminating resistor for the input terminal T, 2 is an analog switch for terminating or opening by the terminating resistor, 3 is a buffer circuit,
Reference numeral 4 denotes an external synchronizing circuit that generates a synchronizing signal synchronized with a synchronizing signal (external synchronizing signal) given from the outside. Reference numeral 5 opens the analog switch 2 when detecting that the synchronizing signal is output from the external synchronizing circuit 4. Other than that, it is a detection / control circuit that turns on the analog switch 2.
【０００９】このように構成した本実施例装置の動作は
以下の通りである。通常の状態では、アナログスイッチ
２はオン状態になっている。このため、終端抵抗１によ
り終端されており、入力端子Ｔから見た入力インピーダ
ンスは所定の値（例えば７５オーム）になっている。こ
のため、外乱に強く、ノイズ等によって同期が乱れるこ
ともない。The operation of the apparatus of this embodiment thus configured is as follows. In a normal state, the analog switch 2 is on. Therefore, it is terminated by the terminating resistor 1, and the input impedance viewed from the input terminal T has a predetermined value (for example, 75 ohm). Therefore, it is strong against external disturbances, and the synchronization is not disturbed by noise or the like.
【００１０】入力端子Ｔに外部同期信号が入ると、外部
同期回路４が動作する。そして、検出・制御回路５は外
部同期信号の入力を検出し、Ｌレベルの信号を出力し、
スイッチ２を開放する。これにより、外部同期信号をハ
イインピーダンスで受けることになり、入力段階での減
衰を極力抑えることができる。従って、外部同期回路４
からは、外部同期信号に同期した同期信号が出力され、
図外のカメラ回路等に供給される。When an external synchronizing signal is input to the input terminal T, the external synchronizing circuit 4 operates. Then, the detection / control circuit 5 detects the input of the external synchronization signal and outputs the L level signal,
Switch 2 is opened. As a result, the external synchronizing signal is received with high impedance, and the attenuation at the input stage can be suppressed as much as possible. Therefore, the external synchronization circuit 4
Outputs a sync signal synchronized with the external sync signal from
It is supplied to a camera circuit (not shown).
【００１１】このように、同期信号の入力状態に応じ
て、入力端子の終端抵抗を切り換えることで、同期信号
の入力がないときには終端手段により入力端子が終端さ
れており、ノイズに強くなる。一方、同期信号入力端子
に外部同期信号が入ると、検出手段は外部同期信号の入
力を検出し、切り換え手段は開放され、外部同期信号を
ハイインピーダンスで受けることになり、入力段階での
減衰が極力抑えられる。従って、外部同期信号を入力し
たときに信号のレベルを減少させずに、かつ外部同期信
号を入力しないときにも外乱に強い外部同期装置を実現
できる。As described above, the terminating resistor of the input terminal is switched according to the input state of the synchronizing signal, so that the input terminal is terminated by the terminating means when there is no input of the synchronizing signal, and the terminal is resistant to noise. On the other hand, when the external synchronizing signal is input to the synchronizing signal input terminal, the detecting means detects the input of the external synchronizing signal, the switching means is opened, and the external synchronizing signal is received with a high impedance, so that the attenuation at the input stage occurs. It can be suppressed as much as possible. Therefore, it is possible to realize an external synchronization device that is strong against disturbance without reducing the signal level when the external synchronization signal is input and when the external synchronization signal is not input.
【００１２】[0012]
【発明の効果】以上詳細に説明したように、本発明で
は、外部同期信号の入力状態に応じて、入力端子の終端
抵抗を切り換えることで、入力インピーダンスを変え、
外部同期信号を入力したときに信号のレベルを減少させ
ずに、かつ外部同期信号を入力しないときにも外乱に強
い外部同期装置が実現できる。As described in detail above, according to the present invention, the input impedance is changed by switching the terminating resistance of the input terminal according to the input state of the external synchronizing signal.
It is possible to realize an external synchronization device that is strong against disturbance without reducing the signal level when an external synchronization signal is input and when the external synchronization signal is not input.
【図１】本発明の一実施例の構成を示す構成図である。FIG. 1 is a configuration diagram showing a configuration of an embodiment of the present invention.
１ 終端抵抗 ２ スイッチ ３ バッファ回路 ４ 外部同期回路 ５ 検出・制御回路 1 Termination resistance 2 Switch 3 Buffer circuit 4 External synchronization circuit 5 Detection / control circuit
Claims (1)
る同期信号入力端子と、 同期信号入力端子へ外部同期信号が与えられているか否
かを検出する検出手段と、 同期信号入力端子を終端させる終端手段と、 同期信号入力端子を終端手段により終端する若しくは開
放する切り換えを行なう切り換え手段とを備え、 切り換え手段は外部同期信号の入力が検出されたときに
同期信号入力端子を開放し、外部同期信号の入力が検出
されないときに同期信号入力手段を終端手段により終端
させることを特徴とする外部同期装置。1. A synchronizing signal input terminal for receiving an external synchronizing signal given from the outside, a detecting means for detecting whether or not the external synchronizing signal is given to the synchronizing signal input terminal, and a terminal for terminating the synchronizing signal input terminal. Means and switching means for performing switching for terminating or opening the synchronizing signal input terminal by the terminating means, and the switching means opens the synchronizing signal input terminal when the input of the external synchronizing signal is detected, External synchronizing device, characterized in that the synchronizing signal inputting means is terminated by the terminating means when no input is detected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24158091A JPH0583589A (en) | 1991-09-20 | 1991-09-20 | External synchronizing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24158091A JPH0583589A (en) | 1991-09-20 | 1991-09-20 | External synchronizing device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0583589A true JPH0583589A (en) | 1993-04-02 |
Family
ID=17076432
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24158091A Pending JPH0583589A (en) | 1991-09-20 | 1991-09-20 | External synchronizing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0583589A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2592475A1 (en) | 2007-02-06 | 2013-05-15 | Fujifilm Corporation | Photosensitive composition, lithographic printing plate precursor, lithographic printing method, and novel cyanine dyes |
-
1991
- 1991-09-20 JP JP24158091A patent/JPH0583589A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2592475A1 (en) | 2007-02-06 | 2013-05-15 | Fujifilm Corporation | Photosensitive composition, lithographic printing plate precursor, lithographic printing method, and novel cyanine dyes |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH0583589A (en) | External synchronizing device | |
| EP1333360B1 (en) | Electrical apparatus and operation of peripheral devices therewith | |
| JP2004521546A (en) | Switching method between video signals and image switching device | |
| KR0146670B1 (en) | Automatic switching apparatus of audio and video input signals | |
| KR100213480B1 (en) | Sound output-level control circuit | |
| KR100319862B1 (en) | I / O automatic switching device of camcorder | |
| JPH01256212A (en) | Two-way buffer circuit | |
| JP4018941B2 (en) | Signal interference prevention unit and signal processing apparatus | |
| KR950002408A (en) | Automatic Camera Detection Status of Multi Camera System | |
| KR950013036A (en) | Input / Output Automatic Switching Circuit of AV Equipment | |
| KR100230379B1 (en) | Pre-amplifier in monitor system | |
| JPH03187589A (en) | Video signal transmission system | |
| JP2003110949A (en) | Automatic detector for video signal/s-video signal | |
| JPH04245087A (en) | Automatic switching device for time code | |
| JP2000137276A (en) | Video camera | |
| KR920001648Y1 (en) | Audio muting circuit | |
| KR200178397Y1 (en) | Communication device between inspection and electric controller | |
| JPH07177449A (en) | Video display device | |
| JPS6222302B2 (en) | ||
| KR19980050412U (en) | Video signal output gain control device | |
| JPH04183184A (en) | Image display controller | |
| JPH04286281A (en) | Input/output circuit | |
| KR19980074975A (en) | TV AV Jack Input Signal Switching Device | |
| JPH04240948A (en) | Network controller | |
| KR19990013003A (en) | How to adjust the input status of video and audio signals on TV |