JP3208230B2 - Control signal transmission receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for transmitting or receiving mode information such as switching pulses, recording, and reproduction on a minimum channel to a magnetic head or an amplifier mounted on a rotary head of a video tape recorder, for example. to signal <br/> Den sending and receiving devices.

[0002]

2. Description of the Related Art In a video tape recorder (hereinafter, referred to as a VTR), a video signal and an audio signal are recorded and reproduced on a magnetic tape using a rotary head. This rotary head is provided on the rotary substrate side of the rotary drum. As is well known, a rotary transformer is used to transmit a signal to the fixed circuit board to the rotary head.

In recent years, the functions of VTRs have been improved, and there have been some recorders that not only perform recording / reproduction simply by using two rotary heads but also provide special reproduction by providing a large number of rotary heads. As a rotary head, a system has been developed in which not only a video rotary head for recording and reproducing video signals but also a rotary head for audio is provided and an audio signal is recorded and reproduced on the same track as a video track.

[0004] Rotary transformers having many transmission channels have come to be used, so that the price is high and the cost of the whole VTR set is increased. Also, since the number of rotating heads is variously selected according to the VTR specifications,
Rotary transformers are also required to have specifications corresponding to them,
The number of models increased, which hindered standardization.

In order to cope with such a problem, an amplifier for amplifying a reproduced signal of each head, a changeover switch for switching the amplifier, and a distribution switch for a recording system are provided on a rotating substrate in a rotating drum, thereby providing a rotary transformer. A system has been developed to reduce the number of channels and to standardize the rotary transformer. For example, 199
On June 6, 2009, ICEE (IEEE International Confer
In this system, a head switching signal for controlling a head switching switch provided on the rotating head side, and mode information such as recording / reproduction are multiplexed and rotated on one channel. Transmitted to the head side.

That is, the edge information of the head switching signal is
The signal is modulated, and the FM wave is AM-modulated according to the mode information to form one signal, so that a plurality of control signals can be transferred on one channel.

The head switching signal includes a video head switching signal VSWP for switching the channels CH1 and CH2 of the video head and an audio switching signal A for switching the channels CH1 and CH2 of the audio head.
SWP. Normally, the phase relationship between switching signal VSWP and ASWP is always constant. Considering the control of the well-known double azimuth 4-head system,
Head amplifier switching signal HASW for switching SP head pair and EP head pair also required. Focusing on the head amplifier switching signal HASW and considering special reproduction in the SP mode, the phase of the switching signal is generated at an arbitrary phase and is not constant. Further, as the mode information, not only the above-mentioned recording and reproducing modes, but also a special reproducing mode and head configuration information are required.

According to such a multiplexed signal transmission and reception system, although the FM wave is AM-modulated by the mode information, the resolution of the AM modulation level is restricted on the system, and multiplexing is difficult. Therefore, at most, only binary mode information indicating the recording and reproduction modes can be transmitted, and the system expandability is poor. Also, the head amplifier switching signal HA
As described above, SW generates a phase at an arbitrary phase, but means for simultaneously transmitting such phase information is required. If there is a variation in the circuit of the FM demodulator on the rotating head side, the DC level after the demodulation will also cause a malfunction.

[0009]

As described above, in the case of the conventional system, transmission of many control signals is restricted, resulting in poor flexibility. In particular, at the time of special reproduction such as noiseless picture search, there is a problem that a control signal cannot be appropriately transmitted. SUMMARY OF THE INVENTION It is an object of the present invention to provide a system capable of appropriately transmitting a control signal required for trick play on one channel.

[0010]

According to the present invention, on the transmission side, a head amplifier switching signal and a special reproduction mode signal are frequency-modulated and transmitted as mode information and transmitted by a delay circuit. Only the switching timing from the mode to the normal reproduction is delayed, and the FM wave is AM-modulated only during the special reproduction according to the delay output. On the receiving side, the FM wave is frequency-demodulated to obtain the mode information and the amplitude demodulation. To obtain the head amplifier switching signal,
On the basis of the special reproduction mode signal sent as the mode information, a head amplifier switching signal is obtained from the AM demodulated output during special reproduction and from the mode information during normal reproduction.

[0011]

According to the above-mentioned means, since the AM modulation is stopped except at the time of the special reproduction, the quality of a video signal at the time of normal reproduction or recording can be improved. In addition, a delay circuit is used to switch between the special playback mode and the normal playback mode.
Since it can be set to a state where modulation is applied, there is no data reading error at the time of mode transition.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a transmitting side and a receiving side in one embodiment of the present invention, and corresponds to a fixed side and a rotating drum side in a VTR. FIG. 2 is a signal waveform diagram shown for explaining the operation of the system of FIG.

In FIG. 1, an input terminal 11 supplies a video head switching signal VSWP, and an input terminal 12 supplies an audio head switching signal ASWP. Input terminal 1
3 supplies a plurality of mode information, and an input terminal 14 supplies a head amplifier switching signal HASW.

The video head switching signal VSWP and the audio head switching signal ASWP are supplied to the edge pulse train detector 2
1 and the edge attribute detector 22. The edge pulse train detector 21 extracts all edges of each switching signal in a phase order to obtain a synthesized edge pulse train, and supplies this to a serial transfer sequence circuit 23 and a quaternary signal generator 25. The edge pulse train detector 21 supplies the video edge pulse VE and the audio edge pulse AE to the edge attribute detector 22.

The edge attribute detector 22 utilizes the condition that the mutual phase relationship between the video head switching signal VSWP and the audio head switching signal ASWP is constant, and the fact that it is possible to specify which signal the current edge belongs to. Then, it is possible to predict which signal the next arriving edge belongs to and how the polarity changes. Based on this prediction, attribute (polarity) information of the next edge is created and supplied to the parallel-serial converter 24 as edge attribute information (for example, 2-bit parallel data). The mode information (for example, 4
Bit parallel data).

The parallel-serial converter 24 is supplied with a timing signal from the serial transfer sequence circuit 23, and outputs serial data based on the timing signal. This serial data is supplied to a quaternary signal generator 25. The quaternary signal generator 25 is supplied with a serial clock from the serial transfer sequence circuit 23 and an edge pulse train from the edge pulse train detector 21.

Here, referring to FIGS. 2 (a) to 2 (i),
The above video head switching signal VSWP, audio head switching signal ASWP, edge pulse train, serial data,
The clock will be described. (A) to (D)
FIG. 9 shows the enlarged period T of (a) to (d).

In FIG. 2, the rectangular waves in FIGS. 2A and 2B are a video head switching signal VSWP and an audio head switching signal ASWP. This rectangular wave always has a fixed phase relationship. Next, the pulse C1 of the quaternary signal (C) shown in an enlarged scale is obtained by dividing each edge of the rectangular waves of (A) and (B) by:
It is a train of edge pulses extracted and combined in phase order.
For example, the first four bits of the serial data SD following the edge pulse C1 are mode information MD, and the last two bits are edge attribute data AD. Each bit data is superimposed on a clock.

Here, the attribute data AD will be described. The edge attribute data AD indicates the polarity of the next arriving edge depending on the content. In the example of the figure, the phase relationship is such that the edge of the audio head switching signal ASWP of the positive polarity comes after the edge of the video head switching signal VSWP of the positive polarity. The phase relationship is such that the edge of the video head switching signal VSWP of the negative polarity comes after the edge of the audio head switching signal ASWP of the positive polarity. Further, following the edge of the video head switching signal VSWP of the negative polarity, the audio head switching signal AS of the negative polarity is
There is a phase relationship in which the edges of the WP arrive.

Further, in the quaternary signal generator 25,
The following relationship is set between the level of the edge pulse train, the serial data, and the clock. That is, the clock is the first level L1, the serial data superimposed on this clock is the second level L2, and the edge pulse C1 is the third level L3 with respect to the reference level Lr.
It is a quaternary signal of r, L1, L2, and L3.

The quaternary signal obtained in this way is FM
The frequency modulation is performed by the modulator 26, and the FM wave is further supplied to the AM modulator 27. Here, the FM wave is amplitude-modulated by the head amplifier switching signal HASW, and the control signal can be transmitted as a multiplex signal for one channel.

Here, the above head amplifier switching signal HA
The SW does not require special timing switching at the time of normal reproduction or recording, so that if it is transmitted as the mode information, the amplitude modulation becomes unnecessary. In this case, since the influence on the crosstalk to the video signal and the HiFi signal is reduced, the signal quality of these signals can be further improved.

In FIG. 1, the head amplifier switching signal HA
A description will be given of switching between the special reproduction of the SW and the normal reproduction. That is, the head amplifier switching signal data and the special reproduction mode data are set in the mode information supplied to the input terminal 13, and the special reproduction mode data is transmitted to the delay circuit 29.
To supply. Further, the edge pulse trains VE and AE obtained by the edge pulse train detector 21 are supplied to the delay circuit 20 to delay only the switching timing of the special reproduction mode data from the special reproduction to the normal reproduction. By controlling the switch 30 with this delay output, the AM modulator 27 is controlled so as to apply amplitude modulation only during special reproduction.

In FIG. 2, for example, a video head switching signal VSWP and an audio head switching signal ASWP exist at timings (a) and (b), respectively, and (e).
It is assumed that the special reproduction mode data is switched at the timing shown in the figure. At this time, from the output of the delay circuit 29 in FIG. 1, a (f) delay circuit output is obtained which is delayed only by the switching timing from the special reproduction to the normal reproduction by the video edge pulse VE and the audio edge pulse AE. Using this, the AM modulator 27 is turned ON / OFF as shown in FIG.
Turn OFF.

The demodulation of the multiplex signal transmitted as described above will be described. The multiplex signal introduced to the input terminal 31 is supplied to an AM demodulator 32 and an FM demodulator 33. A
From the M demodulator 32, a reproduced head amplifier switching signal HASW can be obtained. From the FM demodulator 33, a reproduced quaternary signal can be obtained. The quaternary signal is supplied to the clamp circuit 34 to reproduce the reference level (lowest potential), thereby stabilizing the next decoding process. The clamp circuit 34 requires a capacitor,
Since the minimum potential period is long, the capacity of the capacitor is small, and an IC can be formed. The output (quaternary signal) of the clamp circuit 34 is supplied to a quaternary signal decoder 35.

The quaternary signal decoder 35 reproduces an edge pulse train in accordance with the quaternary value and reproduces the first half mode information MD and the second half serial data SD including edge attribute data AD and a clock.
The serial data SD is supplied to a serial / parallel converter 36. The serial / parallel converter 36 separates the mode information MD and the edge attribute data AD based on the clock, supplies the parallel converted edge attribute data AD to the rectangular wave synthesizing circuit 37, and also converts the parallel converted mode information MD.
Is supplied to the synchronization circuit 38. The rectangular wave synthesizing circuit 37 reproduces the video head switching signal VSWP and the audio head switching signal ASWP using the edge attribute data AD and the edge pulse train. The synchronization circuit 38 outputs the mode information in synchronization with the edge pulse train, and derives it as a system state switching signal. FIG. 2D shows that mode information M0, M1, M2,... Has been transmitted.

Here, the mode data changeover switch 39 switches between the head amplifier changeover signal HASW reproduced by the AM demodulator 32 and the mode information output from the synchronization circuit 38 in accordance with the special reproduction mode data obtained from the synchronization circuit 38. Either is selected and output as a head amplifier switching signal.

On the receiving side, the switching timing of the mode information is uniformly delayed by at least one edge pulse by the synchronization circuit 38. For this reason, in FIG. 2, the (h) trick play mode data on the receiving side is delayed from the (e) trick play mode data input on the transmitting side. Incidentally, in this example, the delay is one edge pulse. The head amplifier switching signal is selected according to the mode data, and the final output is as shown in (i). In this case, when the mode data changeover switch 39 switches the output of the AM demodulator 32 to the mode information output from the synchronization circuit 38, the head amplifier switching signal HASW malfunctions.

Therefore, if the delay amount of the delay output shown in (f) is set larger than the delay amount of the synchronization circuit 38, the modulation on the receiving side is always performed when the special reproduction mode is switched. it can. On the other hand, since the serial data is constantly sent to the receiving side regardless of the special reproduction mode data, no data reading error occurs. In the case of this example, the delayed output of (f) corresponds to the edge pulse 2 with respect to (e).
One minute later. At the timing (h) when the mode is actually switched, as shown in (g), the AM
Since the modulation is applied, the reproduced head amplifier switching signal HASW and the mode information can be smoothly switched.

In the above embodiment, the head amplifier switching signal HASW is AM-modulated.
Instead of modulation, frequency modulation may be performed, and mode information may be frequency-multiplexed with frequency-modulated FM waves and transmitted. In this case, on the receiving side, the same effect as described above can be obtained by separating each FM wave using a filter.

[0031]

As described above, according to the control signal transmitting and receiving apparatus of the present invention, the A
Since the head switching signal is transmitted by M modulation, the quality of a video signal or the like during normal reproduction or recording can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the circuit operation of FIG. 1;

FIG. 3 is a conventional circuit configuration diagram.

FIG. 4 is a timing chart for explaining the operation of the circuit in FIG. 3;

[Explanation of symbols]

11 to 14: input terminals, 21: edge pulse train detector,
22: edge attribute detector, 23: serial transfer sequence circuit, 24: parallel-serial converter, 25: 4-level signal generator.

Claims (3)

(57) [Claims] 1. A transmission side means for frequency-modulating a head amplifier switching signal and a special reproduction mode signal into an FM wave, and amplitude-modulating the FM wave according to the head amplifier switching signal only during special reproduction. Means on the receiving side, comprising: means for frequency demodulating the FM wave; and means for amplitude demodulating the amplitude-modulated head amplifier switching signal, wherein the special reproduction mode signal obtained by frequency demodulation is provided. But,
The head amplifier is switched by the head amplifier switching signal obtained by amplitude demodulation of the FM wave during special reproduction, and the head amplifier is switched by the head amplifier switching signal obtained by frequency demodulation of the FM wave during normal reproduction. a control signal Den sending and receiving devices. 2. The receiving side further includes means for uniformly delaying the special reproduction mode signal, and the transmission side includes a delay means for delaying a switching timing from special reproduction to normal reproduction in the special reproduction mode signal; 2. The control signal transmission / reception device according to claim 1, further comprising: means for applying an amplitude modulation to the output of the delay means only at the time of special reproduction, and performing amplitude modulation at the time of transition to the special reproduction mode on the receiving side. Communication device. The method according to claim 3, wherein the amplitude modulation and an amplitude demodulation, frequency modulation and replaced by frequency demodulation, the control signal Den sending and receiving apparatus according to claim 1, wherein the transmitting the FM wave frequency-multiplexed manner.