EP0990345A2 - Appareil d'enregistrement/de reproduction video - Google Patents

Appareil d'enregistrement/de reproduction video

Info

Publication number
EP0990345A2
EP0990345A2 EP99910593A EP99910593A EP0990345A2 EP 0990345 A2 EP0990345 A2 EP 0990345A2 EP 99910593 A EP99910593 A EP 99910593A EP 99910593 A EP99910593 A EP 99910593A EP 0990345 A2 EP0990345 A2 EP 0990345A2
Authority
EP
European Patent Office
Prior art keywords
coupled
terminal
supply voltage
video recorder
output
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.)
Withdrawn
Application number
EP99910593A
Other languages
German (de)
English (en)
Inventor
Teunis H. Uittenbogaard
Peter Boekestein
Hendricus M. Van Der Wijst
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Priority to EP99910593A priority Critical patent/EP0990345A2/fr
Publication of EP0990345A2 publication Critical patent/EP0990345A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/765—Interface circuits between an apparatus for recording and another apparatus
    • H04N5/775—Interface circuits between an apparatus for recording and another apparatus between a recording apparatus and a television receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/765—Interface circuits between an apparatus for recording and another apparatus
    • H04N5/775—Interface circuits between an apparatus for recording and another apparatus between a recording apparatus and a television receiver
    • H04N5/7755—Interface circuits between an apparatus for recording and another apparatus between a recording apparatus and a television receiver the recorder being connected to, or coupled with, the antenna of the television receiver

Definitions

  • Video recorder/reproducer apparatus
  • the invention relates to a video recorder/reproducer apparatus, provided with
  • tuner circuit having an input coupled to the antenna input terminal, and an output
  • the invention also relates to switching means for use in the apparatus.
  • Usp 3,824,335 discloses a video recorder/reproducer apparatus provided with a passive splitter circuit.
  • Present day video recorder/reproducer apparatuses make use of an active splitter circuit that requires a supply voltage, for the reason that the splitter circuit generally also has an amplifier function.
  • FIG. 1 A schematic block diagram of a conventional video recorder/reproducer (VCR) apparatus is given in Fig.1.
  • Terminal 1 is the antenna input terminal and terminal 2 is the antenna output terminal for coupling to a TV apparatus.
  • the VCR apparatus is not used ("stand-by"), at least the wide band splitter amplifier must always be switched on to ensure reception of TV signals in the TV set. Power consumption in stand-by can be reduced if the supply voltage of the VCR apparatus can be switched off, but special measures must be taken to ensure the reception of TV signals in the TV set.
  • the invention aims at providing a video recorder/reproducer apparatus having a relatively low power consumption, but ensures the antenna signal to be supplied to the antenna output terminal, even if the supply voltage for the splitter circuit has been switched off.
  • the apparatus defined in the opening paragraph is characterized in that the video recorder apparatus further comprises
  • the switching means having a first terminal coupled to the antenna input terminal and a second terminal coupled to the antenna output terminal, the switching means being adapted to realize an internal connection between its two terminals in response to the supply voltage generator means being switched off and for realizing an open connection between its two terminals in response to the supply voltage generator means being switched on, the switching means comprising a FET (4), having its main electrodes coupled to the first and second terminal of the switching means.
  • the invention is based on the following recognition. If a FET (field effect transistor), more specifically a depletion type silicon Mosfet or a Mesfet, is used in its linear region, this FET can be used as a variable resistor. The resistance depends on the bias voltage between Gate and Source and the pinch - off voltage of this FET. If this bias voltage is lower than the pinch - off voltage the resistance of the FET is infinite. If this bias voltage is much higher than the pinch - off voltage the resistance of the FET is low. Due to this, a FET can be used as a switch. At low Gate - Source voltages the FET is switched off and at high Gate - Source voltages the FET is switched - on.
  • a FET field effect transistor
  • this FET can be used as an RF (Radio Frequency) switch. With this RF switch, RF signals can be switched off and on.
  • the newly developed BF1107 is a triode Mosfet intended for switching RF signals. If the Drain - Source voltage is set to OV, this Mosfet is biased in its linear region. This Mosfet has a pinch - off voltage of appr. -3V. Therefore this Mosfet is switched - on if the Gate - Source voltage is OV. Together with a Drain - Source voltage of OV this means that the Mosfet is switched - on if all bias voltages are OV. If the Gate - Source voltage is set to a value lower than -3V this Mosfet is switched off.
  • figure description shows in figure 1 the conventional video recorder/reproducer apparatus, figure 2 the apparatus in accordance with the invention, provided with a FET, figure 3 a test circuit for measuring the behaviour of the switching circuit, figure 4 the test results, figure 5 a more elaborate circuit diagram of the switching circuit, figure 6 a further elaborated version of the switching circuit, and figure 7 an improved version of the switching circuit.
  • FIG. 2 shows an schematic embodiment of the VCR apparatus in accordance with the invention, provided with a switch, in the form of a FET 4, between the antenna terminals 1 and 2.
  • a switch in the form of a FET 4
  • the switch must be conductive if the VCR supply voltage is switched off, and be non-conductive if the VCR supply voltage is switched on.
  • Mosfets or Mesfets could be used as switching elements.
  • a switch in the form of a depletion type silicon Mosfet is chosen. This Mosfet is switched on if all the supply voltages at the Mosfet are 0. The Mosfet is switched off if the Gate - Source voltage has a negative value, more negative than the pinch-off voltage of the Mosfet.
  • the Mosfet switch When the supply voltage of the VCR apparatus is switched on, the Mosfet switch must be switched off. In a further elaboration of the apparatus of figure 2, this can be done by connecting the Drain or the Source of the Mosfet 4 to the supply voltage via a resistor R3 and connecting the Gate to ground and adding a capacitor Ci between the Mosfet 4 and one of the terminals 1 or 2, or by adding capacitors between the Mosfet and both terminals.
  • the antenna signal flows through the Mosfet switch to the TV set.
  • the supply voltage 5V (as an example)
  • the Drain - and Source voltages of the Mosfet switch are 5V.
  • the capacitor Ci ensures that the Drain and the Source voltages are equal.
  • the Gate voltage is 0 (Gate is grounded) and the antenna signal flows through the VCR as usual. It should be further noted that, in this circuit construction, the Mosfet acts as a bidirectional switch.
  • a newly developed depletion type silicon Mosfet that is of specific use in this application is the BF1 107 Mosfet.
  • This Mosfet has the specific advantage over GaAs Mesfets that it is cheaper.
  • an advantage of the Mosfet is low losses. In the 'on'- state of the Mosfet, the losses must be low, because losses determine, for a large amount, the increase of the noise that may become visible on the screen of the TV set. In the 'off- state, the isolation must be high because the oscillator signal from the modulator must be kept very small at the antenna input.
  • the main advantage of applying the BF1107 as a switch for the passive loop through is that this Mosfet uses no current. Not in the on state and not in the off state. Switching is done only with voltages.
  • the performance of the RF switch 4 BF1107 was measured in a circuit as given in Fig. 3. In this circuit, isolation and losses as a function of frequency were measured. To measure the isolation properties of the switch 4 when it is switched off, a voltage V s , which is in the present circuit equal to 5 Volts, should be applied to the terminal 10 in the circuit of figure 3. To measure the properties of the switch when it is in its conductive state, a voltage equal to 0 Volts should be applied to the terminal 10. The gate of the switch 4 is connected to a point 12 of constant potential (ground). The results of these measurements are given in Fig. 4, where the losses are plotted along the left hand side of the diagram in figure 4 and the isolation is plotted along the right hand side of the diagram. Curve 22 in the diagram of figure 4 shows the behaviour of the losses, whereas the curve 20 shows the isolation as a function of frequency.
  • the isolation (Mosfet is switched off) in the testcircuit is mainly determined by the feedback of the Mosfet in common Gate configuration plus the parasitic capacitance of the testcircuit between Drain and Source. This parasitic capacitance must be very small.
  • the losses (Mosfet is switched - on) in the testcircuit are at low frequencies determined by the R DS on of the Mosfet and at high frequencies by the R DS on and the Drain - Gate and Source - Gate capacitances of the Mosfet.
  • the parasitic capacitances of the circuit must be kept much lower than the capacitances of the Mosfet.
  • Fig. 2 only the principle of the application circuit of the switch in the VCR apparatus is given.
  • the input and output of the wide band splitter amplifier are connected to the input and output of the switching circuit.
  • the losses in the 'on'-situation of the switch are also determined by the capacitances at the input and the output of the switch. If in the circuit of Fig.2 the Mosfet is switched on, then the wide band splitter amplifier is still connected to the RF switch. This results into higher losses. Therefore special measures are needed to reduce the influence of the presence of the amplifier on the losses. Theoretically, this can be done by disconnecting the input as well as the output of the amplifier from the switch.
  • the two diodes in Fig. 5 must have low resistance if the switching circuit 8 is on and they must have a low capacitance in both the on and off position of the switching circuit 8. This can be realized by means of the diodes 30 and 32. With the right choice of the diodes 30 and 32, the resistance is low if the diode is forward biased and the capacitance is low if the bias voltage of the diode is OV. Diodes that can be applied are bandswitching diodes (e.g. BA792 or BA277).
  • the splitter circuit 6 is "disconnected" from the switching circuit 8 when the supply voltage V s is equal to OV and "connected" when the supply voltage V s is equal to 5V.
  • the BF1107 switch 4 is a specially developed triode Mosfet for the application as RF switch. In the on condition of the switch as well as in the off condition no DC current flows through the Mosfet.
  • the requirements in the application of the FET in a switching circuit 8 for a VCR apparatus are:
  • the switching circuit of Fig. 6 is further provided with a decoupling capacitor C 3 inserted between the terminal V s and "earth". If this switching circuit is applied the supply voltage of the VCR can be switched - off in the "stand - by" condition of the VCR. The RF signal path to the T.V. set is then via the switch and not via a (power consuming) wide band splitter amplifier.
  • the switching circuit in accordance with the invention has the advantage over prior art switching circuits that it requires less components, so that it is relatively cheap.
  • Figure 7 shows a further improvement of the circuit of figure 6.
  • a diode Di is coupled between the gate of the Mosfet 4 and the point of constant potential (ground) and further, a resistor R d is coupled between the gate of the mosfet 4 and the power supply terminal V s .
  • the circuit of figure 7 shows an improved behaviour, in that the losses in the conductive mode of the mosfet are decreased.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Electronic Switches (AREA)
  • Amplifiers (AREA)
  • Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)

Abstract

L'invention concerne un appareil d'enregistrement/de reproduction vidéo comportant une borne d'entrée d'antenne (1), une borne de sortie d'antenne (2), un circuit répartiteur (6) dont une entrée est couplée à la borne d'entrée d'antenne et dont une sortie est couplée à la borne de sortie d'antenne, un circuit d'accord (syntoniseur) dont une entrée est couplée à la borne d'entrée d'antenne et dont une sortie est couplée à une unité d'enregistrement/de reproduction. L'appareil comporte en outre un modulateur dont une entrée est couplée à la sortie de l'unité d'enregistrement/de reproduction et dont une sortie est couplée à la borne de sortie d'antenne (2). Un générateur de tension d'alimentation (38) produit une tension d'alimentation pour alimenter au moins le circuit répartiteur (6). Un système de commutation (4,8) a une première borne couplée à la borne d'entrée d'antenne (1) et une seconde borne couplée à la borne de sortie d'antenne (2). Le système de commutation établit une connexion interne entre ses deux bornes lorsque le générateur de tension d'alimentation (38) est hors fonction, et il établit une connexion ouverte entre ses deux bornes lorsque ledit générateur est en fonction. Le système de commutation comprend un transistor à effet de champ (4) dont les première et seconde électrodes principales sont couplées aux première et seconde bornes du système de commutation, respectivement.
EP99910593A 1998-04-16 1999-04-08 Appareil d'enregistrement/de reproduction video Withdrawn EP0990345A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP99910593A EP0990345A2 (fr) 1998-04-16 1999-04-08 Appareil d'enregistrement/de reproduction video

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP98201218 1998-04-16
EP98201218 1998-04-16
EP99910593A EP0990345A2 (fr) 1998-04-16 1999-04-08 Appareil d'enregistrement/de reproduction video
PCT/IB1999/000607 WO1999055085A2 (fr) 1998-04-16 1999-04-08 Appareil d'enregistrement/de reproduction video

Publications (1)

Publication Number Publication Date
EP0990345A2 true EP0990345A2 (fr) 2000-04-05

Family

ID=8233607

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99910593A Withdrawn EP0990345A2 (fr) 1998-04-16 1999-04-08 Appareil d'enregistrement/de reproduction video

Country Status (5)

Country Link
EP (1) EP0990345A2 (fr)
JP (1) JP2002511225A (fr)
KR (1) KR20010013758A (fr)
CN (1) CN1266585A (fr)
WO (1) WO1999055085A2 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003071680A1 (fr) 2002-02-25 2003-08-28 Koninklijke Philips Electronics N.V. Commutation de signaux haute frequence
KR100852582B1 (ko) * 2007-06-20 2008-08-14 주식회사 케이이씨 안테나 신호 전환 장치
EP2162986B1 (fr) * 2007-06-29 2013-02-13 Thomson Licensing Circuit syntoniseur doté d'une fonction en boucle
CN105577205A (zh) * 2007-11-27 2016-05-11 Nxp股份有限公司 接收具有环路输出的rf信号的装置和通过接收rf信号的装置循环rf输入信号的方法
EP2308172B1 (fr) 2008-06-13 2014-10-15 Nxp B.V. Commutateur rf pour diviseur rf

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1346222A (en) * 1971-04-28 1974-02-06 Pye Ltd Recording television signals
GB1560991A (en) * 1975-12-08 1980-02-13 Rca Corp Video record player system
DE3440119A1 (de) * 1984-11-02 1986-05-07 Philips Patentverwaltung Gmbh, 2000 Hamburg Schaltungsanordnung fuer ein bildaufzeichnungs- und -wiedergabegeraet
EP0679025B1 (fr) * 1994-04-21 2000-03-22 Philips Patentverwaltung GmbH Arrangement de circuit pour l'alimentation d'un signal d'antenne
DE19538172A1 (de) * 1995-10-13 1997-04-17 Philips Patentverwaltung Schaltungsanordnung zum Einspeisen eines Antennensignals
JP3481388B2 (ja) * 1995-08-30 2003-12-22 アルプス電気株式会社 アンテナブースタミキサ回路
GB2313238A (en) * 1996-05-14 1997-11-19 Alps Electric Co Ltd Antenna booster mixer circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9955085A2 *

Also Published As

Publication number Publication date
KR20010013758A (ko) 2001-02-26
JP2002511225A (ja) 2002-04-09
CN1266585A (zh) 2000-09-13
WO1999055085A2 (fr) 1999-10-28
WO1999055085A3 (fr) 2000-01-06

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