【０００１】
【発明の属する技術分野】
本発明は、テレビインターホン装置に係わり、特に、モニター増設親機の終端回路の入切を自動的に行なうことができるテレビインターホン装置に関する。
【０００２】
【従来の技術】
従来から、この種のテレビインターホン装置として、カメラ付玄関子機をモニター親機、モニター増設親機に順次直列接続し、カメラ付玄関子機からモニター親機、モニター増設親機の何れかを呼び出し、呼び出された側でカメラ付玄関子機からの映像を見ながらカメラ付玄関子機と通話できるような構成のものが知られている（例えば、特許文献１参照）。
【０００３】
【特許文献１】特開２００１−２３７９７４号公報（段落番号０００２〜００１７、図２）
【０００４】
【発明が解決しようとする課題】
ところで、このような構成のテレビインターホン装置においては、モニター親機がシステムの最終端機器となるため、施工時において、モニター親機の終端回路を切り離しかつモニター増設親機の終端回路を接続してＦＭ変調された映像信号のマッチングをとる必要がある。また、上記のモニター増設親機の下流側に他のモニター増設親機を直列接続した場合においては、下流側のモニター増設親機がシステムの最終端機器となるため、上流側のモニター増設親機の終端回路を切り離しかつ下流側のモニター増設親機の終端回路を接続する必要がある。従って、このような構成のテレビインターホン装置においては、モニター親機に複数台のモニター増設親機が接続されている場合は、テレビインターホン装置の施工時において、何れのモニター増設親機が最終端機器であるかどうかを判断し、当該判断に応じて各モニター増設親機の終端回路を入切しなければならないという難点があった。また、終端回路の入切作業が手動により行なわれることから、作業者が終端回路の入切作業を誤ったり、また入切作業を忘れたりする等の難点もあった。
【０００５】
本発明は、このような難点を解決するためになされたもので、モニター増設親機自身に流れる直流電流をフォトカプラで検出することにより、モニター増設親機の終端回路の入切を自動的に行うことができるテレビインターホン装置を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上記の目的を達成するため、本発明のテレビインターホン装置は、カメラ付玄関子機をモニター親機、複数個のモニター増設親機に順次直列接続し、カメラ付玄関子機からモニター親機、モニター増設親機の何れかを呼び出し、呼び出された側でカメラ付玄関子機からの映像を見ながらカメラ付玄関子機と通話のできるテレビインターホン装置であって、モニター増設親機は、直列接続された各モニター増設親機に設けられる終端回路と、自機に流れる直流電流を検出し自機が最終端であるかどうかを判断し、当該判断に応じて終端回路を入切するフォトカプラとを有するものである。
【０００７】
また、本発明のテレビインターホン装置におけるモニター増設親機のフォトカプラの発光部には、当該発光部と並列に、音声や映像信号を次段のモニター増設親機へ通過させる信号パス用コンデンサが接続されている。
【０００８】
本発明のテレビインターホン装置によれば、モニター増設親機自身に流れる直流電流をフォトカプラで検出することにより、モニター増設親機の終端回路の入切を自動的に行うことができ、ひいては、手動によるモニター増設親機の終端設定作業を省略することができ、また、終端設定の過誤や終端設定のし忘れも防止することができる。
【０００９】
【発明の実施の形態】
以下、本発明のテレビインターホン装置の好ましい実施の形態例について、図面を参照して詳述する。ここで、図１は、本発明のテレビインターホン装置のシステム構成図、図２は、本発明のテレビインターホン装置におけるカメラ付玄関子機のブロック図、図３は、本発明のテレビインターホン装置におけるモニター親機のブロック図、図４は、本発明のテレビインターホン装置における第１、第２のモニター増設親機のブロック図を示している。
【００１０】
図１において、本発明のテレビインターホン装置は、屋外に設置されるカメラ付玄関子機１００と、屋内に設置されるモニター親機２００および第１、第２のモニター増設親機３００、４００とを備えている。ここで、モニター親機２００は、第１の伝送路Ｌ１を介してカメラ付玄関子機１００に、第２の伝送路Ｌ２を介して第１のモニター増設親機３００にそれぞれ接続され、この第１のモニター増設親機３００には、第３の伝送路Ｌ３を介して第２のモニター増設親機４００が接続されている。
【００１１】
カメラ付玄関子機１００は、図２に示すように、カメラ回路１０１、ＦＭ変調回路１０２、不平衡ー平衡変換回路１０３、ＬＰＦ（ローパスフィルター）１０４、起動電圧検出回路１０５、呼出ボタン１０６、スピーカ１０７、スピーカアンプ１０８、マイク１０９（以下「子機マイク１０９」という。）、マイクアンプ１１０、２線４線変換回路１１１（以下「子機２線４線変換回路１１１」という。）および出力端子Ｔ１（以下「子機出力端子Ｔ１」という。）を備えている。ここで、カメラ回路１０１は、ＦＭ変調回路１０２を介して不平衡−平衡変換回路１０３に接続され、この不平衡−平衡変換回路１０３には子機出力端子Ｔ１を介して第１の伝送路Ｌ１が接続されている。また、子機出力端子Ｔ１は、ＬＰＦ１０４を介して、起動電圧検出回路１０５、呼出ボタン１０６および子機２線４線変換回路１１１に接続され、起動電圧検出回路１０５にはカメラ回路１０１、ＦＭ変調回路１０２、スピーカアンプ１０８およびマイクアンプ１１０が接続されている。さらに、子機２線４線変換回路１１１は、スピーカアンプ１０８およびマイクアンプ１１０に接続され、スピーカアンプ１０８にはスピーカ１０７が、マイクアンプ１１０には子機マイク１０９がそれぞれ接続されている。
【００１２】
モニター親機２００は、図３に示すように、映像増幅回路２０１、平衡ー不平衡変換回路２０２（以下「親機平衡ー不平衡変換回路２０２」という。）、ＦＭ復調回路２０３（以下「親機ＦＭ復調回路２０３」という。）、ビデオアンプ２０４（以下「親機ビデオアンプ２０４」という。）、ＣＲＴユニット２０５（以下「親機ＣＲＴユニット２０５」という。）、出画制御回路２０６（以下「親機出画制御回路２０６」という。）、音声信号分岐回路２０７、２線４線変換回路２０８（以下「親機２線４線変換回路２０８」という。）、データ送信回路２０９、玄関子機起動電源送出回路２１０、受話アンプ２１１（以下「親機受話アンプ２１１」という。）、送話アンプ２１２（以下「親機送話アンプ２１２」という。）、レシーバ２１３ａ（以下「親機レシーバ２１３ａ」という。）とマイク２１３ｂ（以下「親機マイク２１３ｂ」という。）から構成される送受話器２１３（以下「親機送受話器２１３」という。）、呼出検出回路２１４、フックスイッチ２１５（以下「親機フックスイッチ２１５」という。）、ＣＰＵ２１６（以下「親機ＣＰＵ２１６」という。）、呼出音アンプ２１７（以下「親機呼出音アンプ２１７」という。）、拡声スピーカ２１８（以下「親機拡声スピーカ２１８」という。）、データ送受信回路２１９（以下「親機データ送受信回路２１９」という。）、電源回路２２０（以下「親機電源回路２２０」という。）、入力端子Ｔ２ａ（以下「親機入力端子Ｔ２ａ」という。）および出力端子Ｔ２ｂ（以下「親機出力端子Ｔ２ｂ」という。）を備えている。ここで、親機入力端子Ｔ２ａは、第１の伝送路Ｌ１、親機平衡ー不平衡変換回路２０２、音声信号分岐回路２０７、データ送信回路２０９、玄関子機起動電源送出回路２１０および呼出検出回路２１４に接続され、親機平衡ー不平衡変換回路２０２には映像増幅回路２０１および親機ＦＭ復調回路２０３が接続され、この映像増幅回路２０１には親機出力端子Ｔ２ｂを介して第２の伝送路Ｌ２が、親機ＦＭ復調回路２０３には親機ビデオアンプ２０４を介して親機ＣＲＴユニット２０５がそれぞれ接続されている。また、音声信号分岐回路２０７には親機２線４線変換回路２０８を介して親機受話アンプ２１１および親機送話アンプ２１２が接続され、この親機受話アンプ２１１には親機送受話器２１３を構成する親機レシーバ２１３ａが、親機送話アンプ２１２には親機送受話器２１３を構成する親機マイク２１３ｂがそれぞれ接続されている。さらに、親機ＣＰＵ２１６は、親機出画制御回路２０６、データ送信回路２０９、玄関子機起動電源送出回路２１０、親機受話アンプ２１１、親機送話アンプ２１２、呼出検出回路２１４、親機フックスイッチ２１５、親機呼出音アンプ２１７および親機データ送受信回路２１９が接続され、親機出画制御回路２０６には映像増幅回路２０１、親機ＦＭ復調回路２０３、親機ビデオアンプ２０４および親機ＣＲＴユニット２０５が、親機呼出音アンプ２１７には親機拡声スピーカ２１８がそれぞれ接続されている。さらにまた、親機データ送受信回路２１９および親機電源回路２２０は親機出力端子Ｔ２ｂを介して第２の伝送路Ｌ２に接続されている。
【００１３】
第１のモニター増設親機３００は、図４に示すように、信号パス用コンデンサ３０１（以下「第１の増設親機信号パス用コンデンサ３０１」という。）、発光部３０２ａ（以下「第１の増設親機発光部３０２ａ」という。）と受光部３０２ｂ（以下「第１の増設親機受光部３０２ｂ」という。）で構成されるフォトカプラ３０２（以下「第１の増設親機フォトカプラ３０２」という。）、平衡ー不平衡変換回路３０３（以下「第１の増設親機平衡ー不平衡変換回路３０３」という。）、ＦＭ復調回路３０４（以下「第１の増設親機ＦＭ復調回路３０４」という。）、ビデオアンプ３０５（以下「第１の増設親機ビデオアンプ３０５」という。）、ＣＲＴユニット３０６（以下「第１の増設親機ＣＲＴユニット３０６」という。）、出画制御回路３０７（以下「第１の増設親機出画制御回路３０７」という。）、データ送受信回路３０８（以下「第１の増設親機データ送受信回路３０８」という。）、２線４線変換回路３０９（以下「第１の増設親機２線４線変換回路３０９」という。）、終端回路３１０（以下「第１の増設親機終端回路３１０」という。）、受話アンプ３１１（以下「第１の増設親機受話アンプ３１１」という。）、送話アンプ３１２（以下「第１の増設親機送話アンプ３１２」という。）、レシーバ３１３ａ（以下「第１の増設親機レシーバ３１３ａ」という。）とマイク３１３ｂ（以下「第１の増設親機マイク３１３ｂ」という。）から構成される送受話器３１３（以下「第１の増設親機送受話器３１３」という。）、フックスイッチ３１４（以下「第１の増設親機フックスイッチ３１４」という。）と、ＣＰＵ３１５（以下「第１の増設親機ＣＰＵ３１５」という。）、呼出音アンプ３１６（以下「第１の増設親機呼出音アンプ３１６」という。）、拡声スピーカ３１７（以下「第１の増設親機拡声スピーカ３１７」という。）、電源回路３１８（以下「第１の増設親機電源回路３１８」という。）、入力端子Ｔ３ａ（以下「第１の増設親機入力端子Ｔ３ａ」という。）、出力端子Ｔ３ｂ（以下「第１の増設親機出力端子Ｔ３ｂ」という。）および保護抵抗Ｒ３（以下「第１の増設親機保護抵抗Ｒ３」という。）を備えている。ここで、第１の増設親機入力端子Ｔ３ａは、第２の伝送路Ｌ２、第１の増設親機保護抵抗Ｒ３、第１の増設親機信号パス用コンデンサ３０１、第１の増設親機発光部３０２ａおよび第１の増設親機受光部３０２ｂ、第１の増設親機平衡ー不平衡変換回路３０３、第１の増設親機データ送受信回路３０８および第１の増設親機２線４線変換回路３０９に接続され、第１の増設親機信号パス用コンデンサ３０１および第１の増設親機発光部３０２ａには第１の増設親機出力端子Ｔ３ｂを介して第３の伝送路Ｌ３が、第１の増設親機受光部３０２ｂには第１の増設親機終端回路３１０が、第１の増設親機平衡ー不平衡変換回路３０３には第１の増設親機ＦＭ復調回路３０４および第１の増設親機ビデオアンプ３０５を介して第１の増設親機ＣＲＴユニット３０６が、第１の増設親機２線４線変換回路３０９には第１の増設親機受話アンプ３１１および第１の増設親機送話アンプ３１２がそれぞれ接続されている。さらに、第１の増設親機ＣＰＵ３１５は、第１の増設親機出画制御回路３０７、第１の増設親機データ送受信回路３０８、第１の増設親機受話アンプ３１１、第１の増設親機送話アンプ３１２、第１の増設親機フックスイッチ３１４および第１の増設親機呼出音アンプ３１６に接続され、第１の増設親機出画制御回路３０７には第１の増設親機ＦＭ復調回路３０４、第１の増設親機ビデオアンプ３０５および第１の増設親機ＣＲＴユニット３０６が、第１の増設親機受話アンプ３１１には第１の増設親機送受話器３１３を構成する第１の増設親機レシーバ３１３ａが、第１の増設親機送話アンプ３１２には第１の増設親機送受話器３１３を構成する第１の増設親機マイク３１３ｂが、第１の増設親機呼出音アンプ３１６には第１の増設親機拡声スピーカ３１７がそれぞれ接続されている。
【００１４】
第２のモニター増設親機４００も第１のモニター増設親機３００と同様に、信号パス用コンデンサ４０１（以下「第２の増設親機信号パス用コンデンサ４０１」という。）、発光部４０２ａ（以下「第２の増設親機発光部４０２ａ」という。）と受光部４０２ｂ（以下「第２の増設親機受光部４０２ｂ」という。）で構成されるフォトカプラ４０２（以下「第２の増設親機フォトカプラ４０２」という。）、平衡ー不平衡変換回路４０３（以下「第２の増設親機平衡ー不平衡変換回路４０３」という。）、ＦＭ復調回路４０４（以下「第２の増設親機ＦＭ復調回路４０４」という。）、ビデオアンプ４０５（以下「第２の増設親機ビデオアンプ４０５」という。）、ＣＲＴユニット４０６（以下「第２の増設親機ＣＲＴユニット４０６」という。）、出画制御回路４０７（以下「第２の増設親機出画制御回路４０７」という。）、データ送受信回路４０８（以下「第２の増設親機データ送受信回路４０８」という。）、２線４線変換回路４０９（以下「第２の増設親機２線４線変換回路４０９」という。）、終端回路４１０（以下「第２の増設親機終端回路４１０」という。）、受話アンプ４１１（以下「第２の増設親機受話アンプ４１１」という。）、送話アンプ４１２（以下「第２の増設親機送話アンプ４１２」という。）、レシーバ４１３ａ（以下「第２の増設親機レシーバ４１３ａ」という。）とマイク４１３ｂ（以下「第２の増設親機マイク４１３ｂ」という。）から構成される送受話器４１３（以下「第２の増設親機送受話器４１３」という。）、フックスイッチ４１４（以下「第２の増設親機フックスイッチ４１４」という。）と、ＣＰＵ４１５（以下「第２の増設親機ＣＰＵ４１５」という。）、呼出音アンプ４１６（以下「第２の増設親機呼出音アンプ４１６」という。）、拡声スピーカ４１７（以下「第２の増設親機拡声スピーカ４１７」という。）、電源回路４１８（以下「第２の増設親機電源回路４１８」という。）、入力端子Ｔ４ａ（以下「第２の増設親機入力端子Ｔ４ａ」という。）、出力端子Ｔ４ｂ（以下「第２の増設親機出力端子Ｔ４ｂ」という。）および保護抵抗Ｒ４（以下「第２の増設親機保護抵抗Ｒ４」という。）を備えている。ここで、第２の増設親機入力端子Ｔ４ａは、第３の伝送路Ｌ３、第２の増設親機保護抵抗Ｒ４、第２の増設親機信号パス用コンデンサ４０１、第２の増設親機発光部４０２ａおよび第２の増設親機受光部４０２ｂ、第２の増設親機平衡ー不平衡変換回路４０３、第２の増設親機データ送受信回路４０８および第２の増設親機２線４線変換回路４０９に接続され、第２の増設親機信号パス用コンデンサ４０１および第２の増設親機発光部４０２ａには第２の増設親機出力端子Ｔ４ｂが、第２の増設親機受光部４０２ｂには第２の増設親機終端回路４１０が、第２の増設親機平衡ー不平衡変換回路４０３には第２の増設親機ＦＭ復調回路４０４および第２の増設親機ビデオアンプ４０５を介して第２の増設親機ＣＲＴユニット４０６が、第２の増設親機２線４線変換回路４０９には第２の増設親機受話アンプ４１１および第２の増設親機送話アンプ４１２がそれぞれ接続されている。さらに、第２の増設親機ＣＰＵ４１５は、第２の増設親機出画制御回路４０７、第２の増設親機データ送受信回路４０８、第２の増設親機フックスイッチ４１４、第２の増設親機受話アンプ４１１、第２の増設親機送話アンプ４１２および第２の増設親機呼出音アンプ４１６に接続され、第２の増設親機出画制御回路４０７には第２の増設親機ＦＭ復調回路４０４、第２の増設親機ビデオアンプ４０５および第２の増設親機ＣＲＴユニット４０６が、第２の増設親機受話アンプ４１１には第２の増設親機送受話器４１３を構成する第２の増設親機レシーバ４１３ａが、第２の増設親機送話アンプ４１２には第２の増設親機送受話器４１３を構成する第２の増設親機マイク４１３ｂが、第２の増設親機呼出音アンプ４１６には第２の増設親機拡声スピーカ４１７がそれぞれ接続されている。
【００１５】
次に、このように構成された本発明のテレビインターホン装置の動作について説明する。
【００１６】
先ず、第１のモニター増設親機３００に第３の伝送路Ｌ３を介して第２のモニター増設親機４００を接続し、第１、第２の増設親機保護抵抗Ｒ３、Ｒ４をそれぞれ図４に示すように接地した場合においては、モニター親機２００の親機電源回路２２０から第２の伝送路Ｌ２に重畳される直流電流が第１の増設親機発光部３０２ａで検出され、これにより、第１の増設親機受光部３０２ｂが動作し第１の増設親機終端回路３１０が自動的に切り離される。また、第２のモニター増設親機４００の第２の増設親機出力端子Ｔ４ｂは開放状態にあることから、すなわち、第２のモニター増設親機４００自身が最終端機器となることから、第３の伝送路Ｌ３に重畳される直流電流は第２の増設親機保護抵抗Ｒ４を介して大地へ流れる。これにより、第２の増設親機受光部４０２ｂが動作せず、ひいては、第２の増設親機終端回路４１０は切り離されることなく終端設定された状態が維持される。
【００１７】
以上により、第１、第２のモニター増設親機３００、４００の第１、第２の増設親機終端回路３１０、４１０の入切がそれぞれ自動的に設定される。
【００１８】
このような状態において、先ず、来訪者がカメラ付玄関子機１００の呼出ボタン１０６を押下すると、呼出信号が、ＬＰＦ１０４および第１の伝送路Ｌ１を経由して、モニター親機２００の呼出検出回路２１４へ伝送される。そして、かかる呼出信号が呼出検出回路２１４で検出されると、親機ＣＰＵ２１６の制御により、玄関子機起動電源送出回路２１０、親機出画制御回路２０６および親機呼出音アンプ２１７がそれぞれ駆動される。そして、玄関子機起動電源送出回路２１０が駆動されると、親機電源回路２２０から第１の伝送路Ｌ１を経由してカメラ付玄関子機１００へ動作電源が供給され、かかる動作電源が起動電圧検出回路１０５で検出されると、カメラ回路１０１、ＦＭ変調回路１０２、スピーカアンプ１０８およびマイクアンプ１１０の各部へ電源が供給される。また、親機出画制御回路２０６が駆動されると、映像増幅回路２０１、親機ＦＭ復調回路２０３、親機ビデオアンプ２０４および親機ＣＲＴユニット２０５が能動状態に制御される。さらに、親機呼出音アンプ２１７が駆動されると、親機ＣＰＵ２１６から出力する呼出信号が増幅され、親機拡声スピーカ２１８から呼出音が鳴動し、居住者に対して呼出報知が行なわれる。
【００１９】
また、これと同時に、親機ＣＰＵ２１６から第１、第２の増設親機呼出信号が出力され、第１の増設親機呼出信号は、親機データ送受信回路２１９、第２の伝送路Ｌ２および第１の増設親機データ送受信回路３０８を経由して第１の増設親機ＣＰＵ３１５へ、第２の増設親機呼出信号は、親機データ送受信回路２１９、第２の伝送路Ｌ２、第１の増設親機信号パス用コンデンサ３０１、第３の伝送路Ｌ３および第２の増設親機データ送受信回路４０８を経由して第２の増設親機ＣＰＵ４１５へそれぞれ伝送される。以上の第１、第２の増設親機呼出信号がそれぞれ第１、第２の増設親機ＣＰＵ３１５、４１５で検出されると、それぞれ第１、第２の増設親機ＣＰＵ３１５、４１５の制御により、第１、第２の増設親機出画制御回路３０７、４０７および第１、第２の増設親機呼出音アンプ３１６、４１６が駆動される。そして、それぞれ第１、第２の増設親機出画制御回路３０７、４０７が駆動されると、第１、第２の増設親機ＦＭ復調回路３０４、４０４、第１、第２の増設親機ビデオアンプ３０５、４０５および第１、第２の増設親機ＣＲＴユニット３０６、４０６が能動状態に制御される。また、それぞれ第１、第２の増設親機呼出音アンプ３１６、４１６が駆動されると、第１、第２の増設親機ＣＰＵ３１５、４１５から出力する第１、第２の増設親機呼出信号が増幅され、第１、第２の増設親機拡声スピーカ３１７、４１７から呼出音が鳴動し、それぞれ居住者に対して呼出報知が行なわれる。
【００２０】
一方、カメラ回路１０１で撮像された来訪者の映像は、ＦＭ変調回路１０２においてＦＭ変調され、ＦＭ映像信号として不平衡−平衡変換回路１０３、第１の伝送路Ｌ１および親機平衡−不平衡変換回路２０２を経由して親機ＦＭ復調回路２０３へ、不平衡−平衡変換回路１０３、第１の伝送路Ｌ１、親機平衡−不平衡変換回路２０２、映像増幅回路２０１、第２の伝送路Ｌ２および第１の増設親機平衡−不平衡変換回路３０３を経由して第１の増設親機ＦＭ復調回路３０４へ、不平衡−平衡変換回路１０３、第１の伝送路Ｌ１、親機平衡−不平衡変換回路２０２、映像増幅回路２０１、第２の伝送路Ｌ２、第１の増設親機信号パス用コンデンサ３０１、第３の伝送路Ｌ３および第２の増設親機平衡−不平衡変換回路４０３を経由して第２の増設親機ＦＭ復調回路４０４へそれぞれ伝送される。かかるＦＭ映像信号は、親機ＦＭ復調回路２０３、第１、第２の増設親機ＦＭ復調回路３０４、４０４においてそれぞれ復調され、これにより、来訪者の映像が親機ＣＲＴユニット２０５、第１、第２の増設親機ＣＲＴユニット３０６、４０６にそれぞれ出画される。
【００２１】
ここで、居住者が、来訪者の映像を見ながら、第２の増設親機送受器４１３を取り上げて呼出応答すると、カメラ付玄関子機１００と第２のモニター増設親機４００間に通話路が形成され、第１の増設親機送受器３１３を取り上げて呼出応答すると、カメラ付玄関子機１００と第１のモニター増設親機３００間に通話路が形成され、また、親機送受器２１３を取り上げて呼出応答すると、カメラ付玄関子機１００とモニター親機２００間に通話路が形成さる。なお、居住者が通話を終え、親機送受器２１３、第１、第２の増設親機送受器３１３、４１３を下ろすと、親機ＣＲＴユニット２０５および第１、第２の増設親機ＣＲＴユニット３０６、４０６が非能動とされ、待受状態に戻る。
【００２２】
以上のように、本発明のテレビインターホン装置によれば、カメラ付玄関子機１００からモニター親機２００、第１、第２のモニター増設親機３００、４００の何れかを呼び出し、呼び出された側でカメラ付玄関子機１００からの映像を見ながらカメラ付玄関子機１００と通話することができる。
【００２３】
次に、第１のモニター増設親機３００に第２のモニター増設親機４００を接続しない場合は、第１のモニター増設親機３００の第１の増設親機出力端子Ｔ３ｂが開放状態にあるため、すなわち、第１のモニター増設親機３００自身が最終端機器となることから、第２の伝送路Ｌ２に重畳される直流電流は第１の増設親機保護抵抗Ｒ３を介して大地へ流れる。これにより、第１の増設親機受光部３０２ｂが動作せず、ひいては、第１の増設親機終端回路３１０は切り離されることなく終端設定された状態が維持される。
【００２４】
このような構成のテレビインターホン装置においても、前述と同様に、カメラ付玄関子機１００からモニター親機２００、第１のモニター増設親機３００の何れかを呼び出し、呼び出された側でカメラ付玄関子機１００からの映像を見ながらカメラ付玄関子機１００と通話することができる。
【００２５】
なお、前述の実施例においては、モニター親機に２台のモニター増設親機を直列接続した場合について説明しているが、システムの規模により、３台以上のモニター増設親機を直列接続してもよい。
【００２６】
【発明の効果】
以上の説明から明らかなように、本発明のテレビインターホン装置によれば、モニター増設親機自身に流れる直流電流をフォトカプラで検出することにより、モニター増設親機の終端回路の入切を自動的に行うことができる。従って、本発明のテレビインターホン装置によれば、施工時において、手動によるモニター増設親機の終端設定作業を省略することができ、また、終端設定の過誤や終端設定のし忘れも防止することができる。
【図面の簡単な説明】
【図１】本発明のテレビインターホン装置の一実施例を示すシステム構成図。
【図２】本発明のテレビインターホン装置におけるカメラ付玄関子機のブロック図。
【図３】本発明のテレビインターホン装置におけるモニター親機のブロック図。
【図４】本発明のテレビインターホン装置における第１、第２のモニター増設親機のブロック図。
【符号の説明】
１００…カメラ付玄関子機
２００…モニター親機
３００…第１のモニター増設親機
３０１…信号パス用コンデンサ（第１の増設親機信号パス用コンデンサ）
３０２…フォトカプラ（第１の増設親機フォトカプラ）
３０２ａ・・・発光部（第１の増設親機発光部）
３０２ｂ・・・受光部（第１の増設親機受光部）
３１０・・・終端回路（第１の増設親機終端回路）
４００…第２のモニター増設親機
４０１…信号パス用コンデンサ（第２の増設親機信号パス用コンデンサ）
４０２…フォトカプラ（第２の増設親機フォトカプラ）
４０２ａ・・・発光部（第２の増設親機発光部）
４０２ｂ・・・受光部（第２の増設親機受光部）
４１０・・・終端回路（第２の増設親機終端回路）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a television intercom apparatus, and more particularly to a television intercom apparatus capable of automatically turning on and off a termination circuit of a monitor extension master unit.
[0002]
[Prior art]
Conventionally, as a TV intercom device of this type, a camera-equipped entrance slave unit is connected in series to a monitor master unit and a monitor extension master unit, and one of the monitor master unit and the monitor extension master unit is called from the camera-equipped entrance slave unit. A configuration is known in which the called side can talk with the camera-equipped entrance device while viewing the image from the camera-equipped entrance device (for example, see Patent Document 1).
[0003]
[Patent Document 1] JP-A-2001-237974 (paragraphs 0002 to 0017, FIG. 2)
[0004]
[Problems to be solved by the invention]
By the way, in the TV intercom apparatus having such a configuration, since the monitor base unit is the last terminal device of the system, at the time of construction, the terminal circuit of the monitor base unit is disconnected and the terminal circuit of the monitor expansion base unit is connected. It is necessary to match the FM-modulated video signal. Also, when another monitor extension master unit is connected in series to the downstream side of the above monitor extension master unit, the downstream monitor extension master unit becomes the last terminal device of the system, so that the upstream monitor extension master unit is used. It is necessary to disconnect the terminating circuit of the monitor and connect the terminating circuit of the monitor expansion master unit on the downstream side. Therefore, in the television intercom apparatus having such a configuration, when a plurality of monitor extension master units are connected to the monitor master unit, any of the monitor extension master units is the terminal device at the time of construction of the TV intercom unit. There is a drawback in that it is necessary to determine whether or not this is the case, and to turn on and off the terminating circuit of each additional monitor base unit in accordance with the determination. In addition, since the on / off operation of the terminal circuit is manually performed, there is a problem that the operator mistakes the on / off operation of the terminal circuit or forgets the on / off operation.
[0005]
The present invention has been made in order to solve such a difficulty, and automatically detects the direct current flowing in the monitor extension master unit itself with a photocoupler, thereby automatically turning on and off the termination circuit of the monitor extension master unit. It is an object of the present invention to provide a television intercom device capable of performing the operation.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the television intercom apparatus of the present invention is configured such that a camera-equipped entrance slave unit is connected in series to a monitor parent unit, a plurality of monitor extension parent units, and the camera-equipped entrance slave unit is connected to the monitor parent unit and the monitor. A television intercom device that can call one of the extension base units and allow the called side to talk to the camera-mounted entrance unit while watching the image from the camera-enclosed base unit. The monitor expansion base unit is connected in series. And a photocoupler that detects the DC current flowing to the own device to determine whether the own device is the final end, and turns the terminal circuit on and off according to the determination. Have
[0007]
In addition, a signal path capacitor for passing audio and video signals to the next monitor additional master unit is connected to the light emitting unit of the photocoupler of the monitor additional master unit in the television intercom apparatus of the present invention in parallel with the light emitting unit. Have been.
[0008]
ADVANTAGE OF THE INVENTION According to the television intercom apparatus of this invention, by detecting the direct current which flows into the monitor addition master unit itself with a photocoupler, the termination circuit of the monitor addition master unit can be automatically turned on and off, and as a result, In this case, it is possible to omit the terminal setting work of the monitor extension master unit, and also to prevent an error in terminal setting and forgetting to set terminal.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the television intercom apparatus of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a system configuration diagram of the television intercom apparatus of the present invention, FIG. 2 is a block diagram of a front door unit with a camera in the television intercom apparatus of the present invention, and FIG. 3 is a monitor in the television intercom apparatus of the present invention. FIG. 4 is a block diagram of a main unit, and FIG. 4 is a block diagram of first and second additional monitor units in the television intercom apparatus of the present invention.
[0010]
In FIG. 1, a TV intercom apparatus of the present invention includes a camera-equipped entrance slave unit 100 installed outdoors, a monitor master unit 200 installed indoors, and first and second monitor expansion master units 300 and 400. Have. Here, the monitor base unit 200 is connected to the camera-equipped entrance slave unit 100 via the first transmission line L1 and to the first monitor expansion base unit 300 via the second transmission line L2, respectively. The second additional monitor base unit 400 is connected to the first additional monitor base unit 300 via the third transmission line L3.
[0011]
As shown in FIG. 2, the camera-equipped entrance device 100 includes a camera circuit 101, an FM modulation circuit 102, an unbalanced-balanced conversion circuit 103, an LPF (low-pass filter) 104, a start-up voltage detection circuit 105, a call button 106, and a speaker. 107, a speaker amplifier 108, a microphone 109 (hereinafter, referred to as “slave microphone 109”), a microphone amplifier 110, a two-wire / four-wire conversion circuit 111 (hereinafter, referred to as “slave device two-wire / four-wire conversion circuit 111”), and an output terminal T1 (hereinafter referred to as “slave device output terminal T1”). Here, the camera circuit 101 is connected to the unbalanced-balanced conversion circuit 103 via the FM modulation circuit 102, and the unbalanced-balanced conversion circuit 103 is connected to the first transmission line L1 via the slave unit output terminal T1. Is connected. The slave unit output terminal T1 is connected to a start-up voltage detection circuit 105, a call button 106, and a slave unit two-wire / four-wire conversion circuit 111 via an LPF 104, and the start-up voltage detection circuit 105 has a camera circuit 101 and an FM modulation. The circuit 102, the speaker amplifier 108, and the microphone amplifier 110 are connected. Further, the slave unit two-wire / four-wire conversion circuit 111 is connected to a speaker amplifier 108 and a microphone amplifier 110, and a speaker 107 is connected to the speaker amplifier 108, and a slave unit microphone 109 is connected to the microphone amplifier 110, respectively.
[0012]
As shown in FIG. 3, the monitor base unit 200 includes a video amplification circuit 201, a balanced-unbalanced conversion circuit 202 (hereinafter, referred to as a "base unit balanced-unbalanced conversion circuit 202"), and an FM demodulation circuit 203 (hereinafter, referred to as a "parent unit"). FM demodulation circuit 203), video amplifier 204 (hereinafter referred to as "base unit video amplifier 204"), CRT unit 205 (hereinafter referred to as "base unit CRT unit 205"), and image output control circuit 206 (hereinafter referred to as "base unit CRT unit 205"). A master signal output control circuit 206), an audio signal branch circuit 207, a two-wire / four-wire conversion circuit 208 (hereinafter, referred to as a "main device two-wire / four-wire conversion circuit 208"), a data transmission circuit 209, and a front-end slave unit. Start-up power supply sending circuit 210, receiving amplifier 211 (hereinafter referred to as “base unit receiving amplifier 211”), transmitting amplifier 212 (hereinafter referred to as “base unit transmitting amplifier 212”), and receiver 21. a (hereinafter, referred to as a “base unit receiver 213a”) and a microphone 213b (hereinafter, referred to as a “base unit microphone 213b”), a handset 213 (hereinafter, referred to as a “base unit handset 213”), and a call detection circuit 214. , A hook switch 215 (hereinafter, referred to as a "base unit hook switch 215"), a CPU 216 (hereinafter, referred to as a "base unit CPU 216"), a ring tone amplifier 217 (hereinafter, referred to as a "base unit ring tone amplifier 217"), and a loudspeaker 218. (Hereinafter, referred to as “master speaker loudspeaker 218”), a data transmission / reception circuit 219 (hereinafter, referred to as “master device data transmission / reception circuit 219”), a power supply circuit 220 (hereinafter, referred to as “master device power supply circuit 220”), and an input terminal T2a. (Hereinafter, referred to as “master device input terminal T2a”) and an output terminal T2b (hereinafter, referred to as “master device output terminal T2b”). There. Here, the base unit input terminal T2a is connected to the first transmission line L1, the base unit balanced-unbalanced conversion circuit 202, the audio signal branch circuit 207, the data transmission circuit 209, the entrance terminal start-up power supply transmission circuit 210, and the call detection circuit. 214, a video amplifier circuit 201 and a parent machine FM demodulation circuit 203 are connected to the parent machine balanced-unbalanced conversion circuit 202, and a second transmission is performed to the video amplifier circuit 201 via the parent machine output terminal T2b. The main unit CRT unit 205 is connected to the main unit FM demodulation circuit 203 via the main unit video amplifier 204. In addition, a base unit receiver amplifier 211 and a base unit transmitter amplifier 212 are connected to the audio signal branching circuit 207 via a base unit two-wire / four-wire converter circuit 208, and the base unit receiver / receiver 213 is connected to the base unit receiver amplifier 211. Are connected to the base unit receiver 213a, and the base unit transmission amplifier 212 is connected to the base unit microphone 213b forming the base unit transmitter / receiver 213, respectively. Further, the base unit CPU 216 includes a base unit output control circuit 206, a data transmission circuit 209, an entrance terminal start-up power supply transmission circuit 210, a base unit receiver amplifier 211, a base unit transmission amplifier 212, a call detection circuit 214, a base unit hook. A switch 215, a base unit ringing amplifier 217, and a base unit data transmission / reception circuit 219 are connected. The base unit output control circuit 206 includes a video amplification circuit 201, a base unit FM demodulation circuit 203, a base unit video amplifier 204, and a base unit CRT. In the unit 205, a base unit loudspeaker 218 is connected to the base unit ring tone amplifier 217. Further, master device data transmission / reception circuit 219 and master device power supply circuit 220 are connected to second transmission line L2 via master device output terminal T2b.
[0013]
As shown in FIG. 4, the first monitor additional parent device 300 includes a signal path capacitor 301 (hereinafter, referred to as a “first additional parent device signal path capacitor 301”) and a light emitting section 302a (hereinafter, referred to as a “first capacitor”). A photocoupler 302 (hereinafter, referred to as a “first additional master photocoupler 302”) including a light emitting unit 302a for the additional master unit and a light receiving unit 302b (hereinafter, “light receiving unit 302b for the first additional master device”). ), A balance-unbalance conversion circuit 303 (hereinafter, referred to as a "first additional base unit balance-unbalance conversion circuit 303"), an FM demodulation circuit 304 (hereinafter, a "first expansion base unit FM demodulation circuit 304"). ), A video amplifier 305 (hereinafter, referred to as “first extension master unit video amplifier 305”), a CRT unit 306 (hereinafter, referred to as “first extension master unit CRT unit 306”), and an image output control circuit. 307 (hereinafter, referred to as a "first additional parent device output control circuit 307"), a data transmission / reception circuit 308 (hereinafter, referred to as a "first additional parent device data transmission / reception circuit 308"), and a two-wire / four-wire conversion circuit 309 ( Hereinafter, the first extension base unit 2-wire 4-wire conversion circuit 309), the termination circuit 310 (hereinafter, referred to as the "first extension base unit termination circuit 310"), the receiving amplifier 311 (hereinafter, the "first extension unit"). A main unit receiver amplifier 311 "), a transmission amplifier 312 (hereinafter referred to as" first additional base unit transmitter amplifier 312 "), and a receiver 313a (hereinafter referred to as" first additional base unit receiver 313a "). A handset 313 (hereinafter, referred to as a "first additional base unit handset 313") including a microphone 313b (hereinafter, referred to as a "first additional base unit microphone 313b"), and a hook switch 314 (hereinafter, referred to as a "first additional base unit microphone 313b"). Increase A main unit hook switch 314), a CPU 315 (hereinafter, referred to as a "first additional base unit CPU 315"), a ring tone amplifier 316 (hereinafter, referred to as a "first additional base unit ring tone amplifier 316"), and loudspeakers. A speaker 317 (hereinafter, referred to as a "first additional base unit speaker 317"), a power supply circuit 318 (hereinafter, referred to as a "first additional base unit power supply circuit 318"), an input terminal T3a (hereinafter, referred to as a "first additional parent unit"). Device terminal T3a), an output terminal T3b (hereinafter, referred to as a "first additional parent device output terminal T3b"), and a protection resistor R3 (hereinafter, referred to as a "first additional parent device protection resistor R3"). ing. Here, the first additional base unit input terminal T3a is connected to the second transmission line L2, the first additional base unit protection resistor R3, the first additional base unit signal path capacitor 301, and the first additional base unit light emission. Unit 302a, first additional base unit light receiving unit 302b, first additional base unit balance-unbalance conversion circuit 303, first additional base unit data transmission / reception circuit 308, and first additional base unit 2-wire 4-wire conversion circuit The first transmission line L3 is connected to the first additional base unit signal path capacitor 301 and the first additional base unit light emitting unit 302a via the first additional base unit output terminal T3b. The first additional base unit terminating circuit 310 is provided in the additional base unit light receiving unit 302b, and the first additional base unit FM demodulation circuit 304 and the first additional unit are provided in the first additional base unit balanced-unbalanced conversion circuit 303. The first extension base unit CRT user via the base unit video amplifier 305 Tsu DOO 306, the first extension master station 2-wire 4-wire conversion circuit 309 first extension master stations receiving amplifier 311 and the first extension master station transmitter amplifier 312 are respectively connected. Further, the first extension master unit CPU 315 includes a first extension master unit output control circuit 307, a first extension master unit data transmission / reception circuit 308, a first extension master unit reception amplifier 311, a first extension master unit. The transmission amplifier 312, the first extension base unit hook switch 314, and the first extension base unit ringing tone amplifier 316 are connected to each other, and the first extension base unit image output control circuit 307 is connected to the first extension base unit FM demodulation. The circuit 304, the first extension base unit video amplifier 305, and the first extension base unit CRT unit 306, and the first extension base unit receiver amplifier 311 constitutes a first extension base unit transmitter / receiver 313. The extension base unit receiver 313a is connected to the first expansion base station transmission amplifier 312, and the first expansion base unit microphone 313b constituting the first expansion base unit handset 313 is connected to the first expansion base unit ringing amplifier. At 316, the first expansion master unit is expanded. Speaker 317 are connected respectively.
[0014]
Similarly to the first monitor extension master unit 300, the second monitor extension master unit 400 also includes a signal path capacitor 401 (hereinafter, referred to as a “second extension master unit signal path capacitor 401”), and a light emitting unit 402a (hereinafter, light-emitting unit 402a). A photocoupler 402 (hereinafter, referred to as a “second additional master unit”) including a “second additional master unit light emitting unit 402a” and a light receiving unit 402b (hereinafter, “second additional master unit light receiving unit 402b”). A photocoupler 402 "), a balance-unbalance conversion circuit 403 (hereinafter, referred to as a" second additional base unit balance-unbalance conversion circuit 403 "), and an FM demodulation circuit 404 (hereinafter, a" second expansion base unit FM "). A video amplifier 405 (hereinafter, referred to as a “second extension base unit video amplifier 405”), a CRT unit 406 (hereinafter, referred to as a “second extension base unit CRT unit 406”). ), An image output control circuit 407 (hereinafter, referred to as a “second additional parent device output control circuit 407”), a data transmission / reception circuit 408 (hereinafter, referred to as a “second additional parent device data transmission / reception circuit 408”), 2 Line 4-wire conversion circuit 409 (hereinafter, referred to as "second extension base unit 2-wire 4-wire conversion circuit 409"), termination circuit 410 (hereinafter, referred to as "second extension base unit termination circuit 410"), and receiving amplifier 411. (Hereinafter, referred to as “second extension base unit receiver amplifier 411”), transmission amplifier 412 (hereinafter, referred to as “second extension base station transmission amplifier 412”), and receiver 413a (hereinafter, “second extension base unit”). A transmitter / receiver 413 (hereinafter, referred to as a "second additional base unit transmitter / receiver 413") including a receiver 413a) and a microphone 413b (hereinafter, referred to as a "second additional base unit microphone 413b"), and a hook switch. 41 (Hereinafter, referred to as a "second additional base unit hook switch 414"), a CPU 415 (hereinafter, referred to as a "second additional base unit CPU 415"), and a ring tone amplifier 416 (hereinafter, referred to as a "second additional base unit ring tone amplifier"). 416 "), a loudspeaker 417 (hereinafter referred to as a" second additional base unit loudspeaker 417 "), a power supply circuit 418 (hereinafter referred to as a" second additional base unit power supply circuit 418 "), and an input terminal T4a ( Hereinafter, this is referred to as a "second additional base unit input terminal T4a", an output terminal T4b (hereinafter referred to as a "second additional base unit output terminal T4b"), and a protection resistor R4 (hereinafter referred to as a "second additional base unit protection resistor"). R4 ”). Here, the second additional base unit input terminal T4a is connected to the third transmission line L3, the second additional base unit protection resistor R4, the second additional base unit signal path capacitor 401, and the second additional base unit light emission. Unit 402a, second additional base unit light receiving unit 402b, second additional base unit balance-unbalance conversion circuit 403, second additional base unit data transmission / reception circuit 408, and second additional base unit 2-wire 4-wire conversion circuit 409, the second additional base unit signal path capacitor 401 and the second additional base unit light emitting unit 402a have a second additional base unit output terminal T4b, and the second additional base unit light receiving unit 402b has A second extension base unit termination circuit 410 is connected to the second extension base unit balanced-unbalanced conversion circuit 403 via a second extension base unit FM demodulation circuit 404 and a second extension base unit video amplifier 405. The second extension base unit CRT unit 406 is The base unit 2-wire 4-wire conversion circuit 409 second extension master stations receiving amplifier 411 and the second extension master stations transmitter amplifier 412 are respectively connected. Further, the second extension master CPU 415 includes a second extension master output control circuit 407, a second extension master data transmission / reception circuit 408, a second extension master hook switch 414, and a second extension master. The receiving amplifier 411, the second extension base unit transmission amplifier 412, and the second extension base unit ringing tone amplifier 416 are connected to each other, and the second extension base unit image output control circuit 407 is connected to the second extension base unit FM demodulation. The circuit 404, the second additional base unit video amplifier 405 and the second additional base unit CRT unit 406, and the second additional base unit receiver amplifier 411 constitutes the second additional base unit transmitter / receiver 413. The extension base unit receiver 413a has a second extension master unit transmission amplifier 412, and the second extension master unit microphone 413b constituting the second extension base unit handset 413 has a second extension base unit ringing amplifier. At 416, the second expansion base unit expansion Speaker 417 are connected respectively.
[0015]
Next, the operation of the television intercom apparatus of the present invention thus configured will be described.
[0016]
First, the second monitor expansion base unit 400 is connected to the first monitor expansion base unit 300 via the third transmission line L3, and the first and second expansion base unit protection resistors R3 and R4 are connected to each other in FIG. In the case where the grounding is performed as shown in (1), a DC current superimposed on the second transmission line L2 from the master unit power supply circuit 220 of the monitor master unit 200 is detected by the first additional master unit light emitting unit 302a. The first additional base unit light receiving section 302b operates, and the first additional base unit termination circuit 310 is automatically disconnected. Further, since the second additional monitor output terminal T4b of the second additional monitor 400 is in an open state, that is, the second additional monitor 400 itself is the final device, the third additional monitor 400 is the third terminal. The DC current superimposed on the transmission line L3 flows through the second additional parent device protection resistor R4 to the ground. As a result, the second extension base unit light receiving unit 402b does not operate, and the second extension base unit termination circuit 410 is maintained in a terminated state without being disconnected.
[0017]
As described above, the on / off of the first and second extension base unit termination circuits 310 and 410 of the first and second monitor expansion base units 300 and 400 are automatically set.
[0018]
In such a state, when the visitor first presses the call button 106 of the camera-equipped entrance cordless handset 100, the call signal is transmitted via the LPF 104 and the first transmission line L1 to the call detection circuit of the monitor master unit 200. 214. Then, when such a call signal is detected by the call detection circuit 214, under the control of the master unit CPU 216, the entrance slave unit start-up power supply sending circuit 210, the master unit image output control circuit 206, and the master unit ring tone amplifier 217 are respectively driven. You. Then, when the entrance terminal start-up power supply sending circuit 210 is driven, operation power is supplied from the parent device power supply circuit 220 to the camera-equipped entrance terminal 100 via the first transmission line L1, and the operation power is activated. When the voltage is detected by the voltage detection circuit 105, power is supplied to the camera circuit 101, the FM modulation circuit 102, the speaker amplifier 108, and the microphone amplifier 110. Further, when the parent device image output control circuit 206 is driven, the video amplification circuit 201, the parent device FM demodulation circuit 203, the parent device video amplifier 204, and the parent device CRT unit 205 are controlled to be active. Further, when base unit ringing amplifier 217 is driven, a ringing signal output from base unit CPU 216 is amplified, a ringing sound is sounded from base unit loudspeaker 218, and a resident is notified of the calling.
[0019]
At the same time, first and second extension base unit calling signals are output from base unit CPU 216, and the first expansion base unit calling signal is transmitted to base unit data transmission / reception circuit 219, second transmission line L2, and second transmission line L2. The second extension base unit calling signal is sent to the first extension base unit CPU 315 via the first extension base unit data transmission / reception circuit 308, the base unit data transmission / reception circuit 219, the second transmission line L2, the first extension The signals are transmitted to the second additional master CPU 415 via the master signal path capacitor 301, the third transmission line L3, and the second additional master data transmission / reception circuit 408, respectively. When the first and second extension master unit calling signals are detected by the first and second extension master unit CPUs 315 and 415, respectively, under the control of the first and second extension master unit CPUs 315 and 415, respectively. The first and second additional parent device output control circuits 307 and 407 and the first and second additional parent device ring tone amplifiers 316 and 416 are driven. When the first and second extension master unit image output control circuits 307 and 407 are driven, the first and second extension master unit FM demodulation circuits 304 and 404, the first and second extension master units, respectively. The video amplifiers 305, 405 and the first and second additional master unit CRT units 306, 406 are controlled to be active. When the first and second extension base unit ring tone amplifiers 316 and 416 are driven, the first and second extension base unit calling signals output from the first and second extension base unit CPUs 315 and 415, respectively. Is amplified, and a ringing tone sounds from the first and second extension master unit loudspeakers 317 and 417, and a call notification is made to each resident.
[0020]
On the other hand, an image of a visitor captured by the camera circuit 101 is FM-modulated by an FM modulation circuit 102, and is converted into an unbalanced-balanced conversion circuit 103, a first transmission path L1, and a master unit balanced-unbalanced conversion as an FM video signal. An unbalanced-balanced conversion circuit 103, a first transmission path L1, a base station balanced-unbalanced conversion circuit 202, a video amplifier circuit 201, and a second transmission path L2 are sent to a master FM demodulation circuit 203 via a circuit 202. And the first additional base unit balanced-unbalanced conversion circuit 303 to the first expanded base unit FM demodulation circuit 304, the unbalanced-balanced conversion circuit 103, the first transmission line L1, the base unit balanced-unbalanced The balance conversion circuit 202, the video amplification circuit 201, the second transmission line L2, the first additional parent device signal path capacitor 301, the third transmission line L3, and the second additional parent device balance-unbalance conversion circuit 403 Via the second They are respectively transmitted to 設親 machine FM demodulation circuit 404. The FM video signal is demodulated in the master FM demodulation circuit 203 and the first and second additional master FM demodulation circuits 304 and 404, respectively, so that the image of the visitor is displayed on the master CRT unit 205, The image is output to the second extension master unit CRT units 306 and 406, respectively.
[0021]
Here, when the resident picks up the second additional base unit handset 413 while viewing the image of the visitor and answers the call, the communication path between the camera-equipped entrance slave unit 100 and the second monitor additional base unit 400 is established. Is formed, and when the first additional base unit handset 313 is picked up and answered, a communication path is formed between the camera-equipped entrance slave unit 100 and the first monitor additional base unit 300, and the base unit handset 213 Is picked up and a call path is formed between the camera-equipped entrance slave unit 100 and the monitor master unit 200. When the resident ends the call and lowers the base unit handset 213 and the first and second extension base unit handsets 313 and 413, the base unit CRT unit 205 and the first and second extension base unit CRT units 306 and 406 are deactivated and return to the standby state.
[0022]
As described above, according to the television intercom apparatus of the present invention, any one of the monitor base unit 200 and the first and second monitor extension base units 300 and 400 is called from the camera-attached entrance slave unit 100 and the called side is called. The user can talk with the camera-equipped entrance terminal 100 while watching the image from the camera-equipped entrance terminal 100.
[0023]
Next, when the second monitor extension master unit 400 is not connected to the first monitor extension master unit 300, the first extension master unit output terminal T3b of the first monitor extension master unit 300 is open. That is, since the first monitor extension master unit 300 itself is the last terminal device, the DC current superimposed on the second transmission line L2 flows to the ground via the first extension master unit protection resistor R3. As a result, the first additional base unit light-receiving unit 302b does not operate, and the state in which the first additional base unit termination circuit 310 is terminated without being disconnected is maintained.
[0024]
Also in the television intercom apparatus having such a configuration, similarly to the above, one of the monitor main unit 200 and the first monitor expansion main unit 300 is called from the camera-equipped entrance slave unit 100, and the camera-equipped entrance door is called on the called side. The user can talk with the camera-equipped entrance slave 100 while watching the image from the slave 100.
[0025]
In the above-described embodiment, a case is described in which two monitor extension master units are connected in series to the monitor master unit. However, depending on the scale of the system, three or more monitor extension master units are connected in series. Is also good.
[0026]
【The invention's effect】
As is apparent from the above description, according to the television intercom apparatus of the present invention, the direct current flowing in the monitor extension base unit itself is detected by the photocoupler, so that the termination circuit of the monitor extension base unit is automatically turned on and off. Can be done. Therefore, according to the television intercom apparatus of the present invention, it is possible to omit manual termination setting work of the monitor extension master unit at the time of construction, and it is also possible to prevent erroneous termination setting and forgetting to set termination. it can.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing one embodiment of a television intercom apparatus of the present invention.
FIG. 2 is a block diagram of a front door unit with a camera in the television intercom apparatus of the present invention.
FIG. 3 is a block diagram of a monitor main unit in the television intercom apparatus of the present invention.
FIG. 4 is a block diagram of first and second additional monitor base units in the television intercom apparatus of the present invention.
[Explanation of symbols]
100 ... Entrance cordless handset with camera
200… Monitor parent machine
300: The first monitor expansion base unit
301: Signal path capacitor (first additional base unit signal path capacitor)
302 ... Photocoupler (first additional master photocoupler)
302a ... light emitting unit (first additional base unit light emitting unit)
302b... Light receiving unit (first additional base unit light receiving unit)
310 termination circuit (first extension parent machine termination circuit)
400: Second monitor expansion base unit
401: Signal path capacitor (second additional master signal path capacitor)
402 ... Photocoupler (second additional master photocoupler)
402a... Light emitting unit (second additional base unit light emitting unit)
402b... Light receiving unit (second additional master unit light receiving unit)
410.. Termination circuit (second extension base unit termination circuit)
