KR800001019B1 - Video record player switching system - Google Patents

Abstract

This video record player includes means for recovering recorded signals respectively representative of picture information, and accompanies sound information. This apparatus comprises an external signal input terminal, a player output terminal, a player on/off switch(41), a power supply(40) developing a plurality of supply potentials in response to switching of the player on/off switch to the "ON" condition.

Description

Video record player system

1 is a partial schematic and partial opening diagram of a video record system embodying the principles of the present invention;

FIG. 2 is a schematic circuit diagram advantageously used for circuits and transmissions connected to the FIG. 1 system. FIG.

The present invention relates to a video record system, and more particularly to a novel device and a television receiver that facilitates the interconnection of video sources between different video record players.

In a recording playback apparatus for video signals representing an image, it is often conveniently used to provide the player output in a modulated carrier format suitable for application to the antenna input of a television receiver. Thus, the latter facility can be provided without internal modification to reproduce the recorded video information. An urban example of such a player system is John Kay. Video disc playback apparatus as described in US Pat. No. 3,842,194 to Clemens. An example of a simplified transmission circuit used to carry video signals (and audio accompanying) that are lapsed in a suitable modulation carrier type for antenna terminal applications is David J. It is illustrated in US Pat. No. 3,775,555 to Carlson.

According to Winry of the present invention, the video record player connects the television receiver and the player to facilitate switching the receiver between the recorded signal response mode and its normal broadcast signal response mode (or cable distributed signal response mode). Is equipped with a new switching device. According to a schematic embodiment of the present invention, a video recorder player has an RF input for coupling to an external signal source (e.g., a broadcast receiving antenna) and a player output terminal for coupling to an RF input of a receiver and power of the player's power source. The absence of a switching device provides a first low impedance signal path between them. The switching device blocks the aforementioned signal paths while responding to the powering of the player's power supply by completing a second low impedance signal path between the player's transmitter circuit and the player output terminal.

In the preferred form, the switching system described above comprises a normally closed relay and a pair of diodes.

In the absence of player power, the normally closed relay completes the first signal path, while the non-conduction state for one diode provided as a series element in the second signal path establishes the latter path.

Also, the non-conduction state for the second diode is bound between the player's RF input and a point of reference potential and prevents shunting the signal away from the first signal path. Powering the player's power supply is effective for the opening of the conduction by the relay and the diode by providing a proper connection between the player's power supply and the diode and the relay control winding.

Under these circumstances. The second signal path is completed by the first conducting diode while the first signal path is blocked by the relay opening (and bypassed by the second conducting diode). The combination of an open relay and a second conducting diode ensures high isolation of the player's RF input from the player's transmission circuitry (eg, attenuating the transmission output of approximately 65 db).

According to another aspect of the invention, the transmitter circuit of the player is switched in such a way that it is directed to the television receiver to correct the stability of the receiver's voice channel whenever a carrier signal is required whenever a recorded signal response mode is set. In connection with, it is preferable. Such a result is efficient by presiding carrier production by a transmission circuit having a power source that efficiently switches to the recorded signal response mode.

According to another aspect of the invention, the transmission circuit parameters are preferably selected in such a way as to set a relatively high (eg 7: 1) ratio between the video and audio carrier labels. Thus, at an unfair level, voice color bead disturbances can be avoided in television receiver operation, while eliminating the complexity and expense of crystal control in the transmission circuit. According to the preferred form of the transmission circuit, the achievement of a high rate of amplitude modulation of the image carrier is helpful by connecting the modulation transformer and the balanced resistor network.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows the application of the principles of the present invention to a reproducing apparatus. It is shown for the video disc player type specified in US Pat. No. 3,911,476 to Kaiser. In the arrangement of FIG. 1, the pickup circuit 11 performs frequency modulation in accordance with the image carrier and low frequency signals which are frequency modulated by the overall composite color video signal of the correlated brightness and chroma signal components during reproduction of the recorded information (1). It is provided to recover from the video disc in a form involving the received voice carrier.

The first bandpass filter 13 coupled to the output of the pickup circuit 11 selectively passes the voice carrier and its sideband through the limiter 15 to the input of the first FM detector 17. Detector 17 provides voice carrier modulation to generate the low frequency signal recorded at its output terminal A. The second bandpass filter 21 is also coupled to the output of the pickup circuit 11 and selectively passes the image carrier and its axle band through the limiter 23 to the input of the second FM detector 25. The detector 25 is applied to the video signal processing circuit 27 by demodulating the image carrier so as to generate a synthesized video signal recorded at the output. The recorded format of the composite color video signal, for example, as described in the Kaiser patent described above is different from that required by the connected color television receiver, and the processing circuit 27 returns the recovered signal in a form that conforms to the latter requirements. The converter key serves. The processing circuit 27 provides the brightness and chroma signal component outputs at the output terminals L and C, respectively. These outputs are summed in the composite signal adder 29 to form a composite color video output signal at its output terminal CV.

The player device of FIG. 1 further comprises a transmitter 30 responsive to respective recorded signal outputs appearing at terminals A and CV, respectively. The transmitter 20 includes a frequency modulated generator 31 which receives a modulated signal input from terminal A. In the absence of a modulated signal, the normal operating frequency of generator 31 is chosen to match the ″ intercarrier ″ frequency (video-to-voice carrier difference) of the television system in which the associated receiver is designed. Schematically, such frequency selection is 4.5 MHz and the carrier output of generator 31 deviates from it according to the low frequency signal output of detector 17 when the signal follows.

The output of generator 31 combines the output of summer 29 with synthesized color video signal output in signal synthesizer 33 to generate a modulated signal for directing to modulated signal input terminal M of carrier amplitude modulator 35. RF input terminal R of modulator 35 receives the output of VHF oscillator 37. The operating frequency of oscillator 37 is selected to match a selected one of the video carrier frequencies to which the associated television receiver responds. The modulated carrier output of modulator 35 is fed to transmitter output terminal T through degraded sideband filter 39 (designed to pass a selected carrier, one of its sidebands, and a small portion of the remaining axis band).

According to the study of the present invention, the player of FIG. 1 includes a switching system which will now be described. The transmitter output terminal T is connected to the cathode of the switching diode 62 (e.g., PIN type), whose anode is coupled to the player's RF output via capacitor 63. Capacitor 61 is coupled between the cathode of the diode and the point of reference potential (eg, player chassis ground).

The anode of diode 62 is also connected to terminal P 'of lead relay 50, which is normally closed. When no current flows in the control winding ″ w ″ of the relay, the switch blade ″ b ″ conducts a conductive connection between the terminal P of the relay 50 and the second terminal P ′. Terminal P 'is connected to the anode of the second switching diode 66 (same as diode 62). Its cathode is connected to the reference potential described above. Terminal P 'is also connected to (1) a pair of antenna input terminals a, a' provided on the outside of the player housing via capacitor 67 and (2) a cable input jack outside the player housing. Is bound to U ″.

The player of FIG. 1 also includes a power source 40 responsive to the staggering current energy applied to the player's AC input terminals i, i 'when the player's on-off switch 41 is stopped in the " on " state. The power supply 40 has a number of DC potential outputs to supply energy potential to the various elements of the player device. Only two of the power output terminals are shown briefly in FIG. 1, which provides an energy potential input to transmitter 30 when the (+ 15V) switch 41 is in the ″ on ″ (dotted) state. Another power supply output (+ 20V) is connected by resistor 65 to the anode of diode 66 and resistor 64 to the anode of diode 62. Relay control winding ″ W ″ is connected between + 20V.

When the player's on-off switch is in the ″ on ″ state, the following happens:

(1) Transmitter 30 is activated, (2) diodes 66 and 62 are conducting and (3) relay 50 is open. (Removes the conductive connection between terminals P ′ and P). The result is (1) at terminal T that the output signal of the transmitter is hardly reduced and coupled to output jack 0. (2) The signal from antenna input terminals a, a '(or from input jack ″ U ″) is not effectively guided to output jack 0 by the extremely low impedance shunt formed by conductive PIN diode 66. The signal divider forms it with capacitor 67 and is inhibited by the high series impedance set by the opening of relay 50. Moreover, the high series impedance of the open relay 50 and the low shunt impedance of the conducting diode 66 ensure a high insulation of about 65db between the output terminal T of the active transmitter and the antenna terminals a, a '. Thus sufficient release of the transmitter output is practically prevented.

When the player's on-off switch 11 is in the ″ off ″ state (1) transmitter 30 is inactive, (2) diodes 62 and 66 are non-conducting and (3) relay 50 is closed. The result is that antenna inputs a, a '(and input jack ″ U ″) are connected to the player's output jacks by a path that is nearly attenuated (e.g. less than 1 db) at a typical broadcast carrier frequency, while The signal path between output terminal T and output jack 0 is interrupted.

In view of the characteristics of the switching system operation described above, it has been considered that the normal RF input power of the receiver must be coupled to the appropriate one of the inputs of the player. As shown schematically in FIG. 1, such a coupling device includes a coupling of antenna lead lines X, X 'balanced to the antenna input terminals a, a' of the player. In addition, a coupling is established between the player's RF output jack 0 and the receiver's appropriate RF input to be used for playback purposes. Where the receiver to be used is a color television receiver of the type (e.g. for TV input purposes) that conforms to the RF input jack ″ j ″ as shown in Figure 1, the combination is a suitable shield that combines jack 0 and ″ j ″. It simply consists of a cable 80. Where the receiver to be used lacks such an input, the output of the cable 80 may be applied via a balun coupler suitable for the balanced input terminals (b, b ') of the receiver.

When the aforementioned combinations are provided, one ensures that the receiver automatically couples to its normal RF input power whenever the player is not active. Furthermore, by simply translating the player into the active state, one ensures that such normal coupling is automatically interrupted and the receiver automatically reacts to the player output. In addition, one ensures that video and audio carriers are automatically fed to the receiver input whenever antenna coupling interference is effective. The generation of annoying noise by the voice channel of the receiver during the non-playback period is eliminated by the static effect of the appearance of the carrier.

At various times during the fixing of the record reproducing operation (e.g., during a record conversion, while searching for a desired portion of a record, etc.), useful video and audio signals can be eliminated from the output of the pickup circuit 11. Under these circumstances, the player preferably includes suitable squelch circuitry so that noise is not induced at terminals A and CV at the input of transmitter 30. Schematically, a. Squelch circuits of the type described in Baker's U.S. Patent Application No. 590,484 are designed to provide adequate squelch signals to the squelch input terminal SQ of summer 29 (and to the squelch input terminal SQ ′ of detector 17) to prevent such noise induction. Can be used. The output at terminal T will in this case include an unmodulated voice carrier and an image carrier which will ensure the static of the receiver's voice channel.

FIG. 2 schematically illustrates a preferred arrangement for implementing the functions of summer 29, oscillator 31, combiner 33, modulator 35, and oscillator 37 and filter 39 of the FIG. 1 system. The summer 29 includes a clamping circuit 101 which responds to the clamping pulses guided at terminal C ₁ to provide recovery of the direct current component of the recorded brightness signal.

The switching arrangement comprising switch 104 and switching diodes 102, 103 is connected to oscillator 37 and filter 39 to be selected within the image carrier frequency as specified in the Carlson patent mentioned above.

The oscillator 31's controlled crystal is not used for simple retrospect and cost reduction purposes. Although the deviation of the oscillation frequency may lead to the deviation of the negative color bead frequency from its normally expected deadlock characteristic, the bead visibility problem is preferably solved in different ways. That is, the voice carrier amplitude is reduced to provide an efficient video carrier-to-voice carrier ratio higher than standard for broadcast signals. Schematically, the output levels for oscillators 31 and 37 are set such that the audio carrier level in the terminal T-sensor transmitter output is about 17 db, less than the peak image carrier level.

As such a level correlation (about 1: 7), a frequency deviation of 5 KHz with respect to the resting frequency of oscillator 31 is shown in the displayed image due to the visible bead by the voice carrier and color subcarrier components of the signal processed by the television receiver. Allowed without encountering annoying effects. However, the voice carrier level reduction above the ratio 1:10 is undesirable because of the significant adverse effect on the signal-to-noise ratio of the receiver's voice output.

Modulator 35 is shown in FIG. 2 as a ring modulator type using diode bridge 107 consisting of four diodes D _1, D ₂ , D ₃ , and D ₄ arranged in ring form. The ring input terminals (at D ₁ , D ₂ , and D ₃ , D ₄ junctions) are connected to the ends of the secondary winding of the input transformer 109 while the ring output terminals D ₁ , D ₂ , and D ₃ , D ₄ junction point) is connected to the input terminal of the balun output transformer 109. The image carrier wave from terminal R is applied to the primary winding of the input transformer 105 while the modulation signal from terminal M is applied to the center tap CT of the secondary winding of the input transformer 105. The bias voltage supplied by the voltage divider formed by resistors 111 and 113 is a diode transformer with diode ring to complain ring modulators (forward bias to diodes D ₁ and D ₂ , reverse bias to diodes D ₂ and D ₄ ). It is applied through a winding. The voltage divider output amplitude and polarity are (1) when the clamp video signal guided by emitter follower 106 to summer output terminal M is at the synchronous peak level, the image carrier wave passes through the modulator output at the desired peak image carrier level, (2) When the clamped video signal directed to terminal M has a peak backlay, the image carrier level at the modulator output is reduced to an appropriate amount (e.g., a level corresponding to 12.5% of the peak carrier level).

With the correct matching of the diodes of the ring 107, the exact position of the center tap CT and the winding of the output transformer 109, the predetermined voltage level at the terminal CV is associated with 100% modulation of the image carrier. (Ie, balancing of carrier outputs). However, as a practical limit on mass production, such results cannot be easily identified. Therefore, it is difficult to guarantee the acquisition of a high rate of modulation (e.g. 87.5%), which is expected at peak backlevel appearance at the adder output. To overcome this problem, modulator 35 includes an additional balanced network formed by a pair of resistors 115 and 117 which actually have a matching resistance value. Resistor 115 is connected between terminal M and one end of the secondary winding of the input transformer. The presence of equilibrium resistors 115 and 117 reduces the unbalanced efficiency of diode mismatch and transformer winding mismatch so that it is quite certain that the desired high rate modulation will be obtained when peak back levels appear at the summator output. For greater precision on modulator unbalance, resistor networks 115 and 117 can be replaced with potentiometers having terminals connected to secondary winding terminals and adjustable tabs connected to terminals M and CT.

When lead relay 50 (FIG. 1) is in the closed state, the conductive path between terminals P and P 'will exhibit some inductive impedance at the RF frequency of the signal passed to output jack 0. However, the closed state of relay 50 is accompanied by the non-conducting state for diodes 62 and 66 and the non-conducting diodes appear as shunt capacitive impedances at each end of the relay's conductive path (P-P '). Therefore, the pie network is formed of devices exhibiting low pass filter characteristics. Thus, by properly selecting the relay, the cutoff frequency for the formed lowpass filter can be above the range of the carrier frequency passed (e.g. 300MHz) so that the signal is relatively attenuated (e.g. 1db or less) and the player's RF It can be easily passed through to the output.

Claims (1)

As described in the text and shown in the drawings, in a video record player, an external signal input terminal; A player output terminal; A player on and off switch for switching between a ″ on ″ and a ″ off ″ state; A power source for generating a plurality of supply commissions only when the player on and off switches are in the " on "state; An apparatus operable in response to the generation of a supply potential by said power source for forming a player output signal comprising an image carrier frequency oscillation and an acoustic carrier frequency oscillation; The video carrier signal frequency oscillation according to the video signal input terminal coupled to the recorded signal recovery apparatus, the audio signal input terminal coupled to the recorded recovery apparatus, and the video signal information recovered when appearing on the video signal input terminal. The player output signal forming apparatus having a device for modulating amplitude and a device for modulating the voice carrier frequency oscillation frequency according to the recovered voice signal information when it appears at the voice signal input terminal; And coupled to the power source and operated with the first mode upon generation of one of the power supply potentials, while operated with the second mode in the absence of the one power potential. Providing a first low impedance signal path for coupling said player output signal to said player output terminal, while insulating said external signal input terminal from said player output terminal and said output signal forming apparatus and In operation, providing a second low impedance signal path for coupling said external signal pressure terminal to said player output terminal while insulating said output signal forming device from said player output and said external signal output terminal. Playback of the recording signals representing the video information and the corresponding audio information Video record player system for growing.

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