JPH0887785A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE: To enable both analog recording and digital recording by selecting suitable recording signal processing in accordance with a signal to be recorded and performing the signal processing while recording a prescribed control signal in accordance with the signal to be recorded. CONSTITUTION: When an input signal is an analog signal, the analog signal inputted from an input terminal 1 is sent to a changeover circuit 10. The changeover circuit 10 is switched to connect the input signal to a recording system analog signal processing circuit 30. In the case of digital recording, a digital signal inputted from the input terminal 1 is inputted to the changeover circuit 10. The changeover circuit 10 is switched over to a recording system digital signal processing circuit 20, and hence the digital input signal is sent to the recording system digital signal processing circuit 20. Thus, by equipping the device with both analog recording and digital recording signal processing circuits, a VTR capable of digital recording and reproducing and also being used as an analog VTR can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a magnetic tape to
The present invention relates to an information recording / reproducing apparatus capable of recording both analog signals and digital signals in a mixed manner on one recording medium by a rotary magnetic head that scans a magnetic tape.

[0002]

2. Description of the Related Art Video tape recorders (V) used for recording and reproducing information signals such as color video signals.
TR) is now widespread in each household. Home VTR
Is a so-called analog recording system (VHS, etc.). On the other hand, in the field of broadcasting business, a digital recording type VTR is used.
Is in the practical stage. Digital recording VTR
There is a D1, D2, D3 format,
It is currently used by broadcasting stations. Such V for broadcasting business
It is considered that the TR technology will eventually be utilized in home VTRs.

Further, various digital information services are being promoted with the development of digital lines, and VTRs compatible with digital video information services are required. In this case, the digital recording method is considered to be suitable.

Considering the above points, it is considered that the next-generation home VTR will be a digital recording system. However, if a VTR dedicated to digital recording is created, the user will need to add the digital VTR to the conventional analog VTR.
It is necessary to purchase a new TR, which increases the financial burden. In addition, it is not easy to use because it is necessary to manage each tape and the like.

Therefore, it would be convenient if there was a VTR capable of digital recording / reproducing corresponding to the above-mentioned conventional system and capable of analog recording / reproducing, but no such VTR has been found conventionally.

[0006]

Considering the VTR capable of analog recording and digital recording, it is desirable that analog recording and digital recording can be mixed on the same recording medium from the viewpoint of user's convenience. The present invention provides a VTR in which analog recording and digital recording can be mixed on the same recording medium, and further, a user-friendly VTR capable of automatically identifying the recording system during reproduction and reproducing.
The purpose is to realize TR.

[0007]

In order to achieve the above object, the information recording / reproducing apparatus of the present invention has a digital recording system as a signal processing system in addition to the conventional analog recording system. Further, it has means for recording the recording mode together with the control signal serving as the reference of the servo during reproduction.
During reproduction, the recorded signal is automatically identified from this information, and reproduction signal processing is performed accordingly.

[0008]

In the VTR of the present invention, the recording signal processing is appropriately selected according to the signal to be recorded, and the signal processing is performed. Further, a predetermined control signal is recorded according to the signal to be recorded. At the time of reproduction, the servo is controlled by the reproduction signal of the control signal, the recording signal is identified, and the reproduction signal processing corresponding to it is automatically selected and performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is an input terminal of a signal to be recorded, 1
0, 11, 12, 13, 14 are switching circuits, 20 is a recording system digital signal processing circuit for adding an error correction code and digital modulation when recording a digital signal, and 30 is signal processing such as FM modulation when recording an analog signal. A recording system analog signal processing circuit, 40 is a control signal generating circuit for generating a predetermined control signal according to the recording signal, 45 is a control head for recording / reproducing the control signal, 50 is a recording amplifier, 52 is a magnetic tape,
53 and 53 'are magnetic heads, 55 is a cylinder, 57 is a reproduction amplifier, 60 is an identification circuit for identifying recorded signals from reproduced control signals, and 70 is digital demodulation and error correction during reproduction of digital signals. A reproducing system digital signal processing circuit, 80 is a reproducing system analog signal processing circuit for performing signal processing such as FM demodulation when reproducing an analog signal, and 5 is an output terminal of a reproduced signal.

An information signal to be recorded is input from the input terminal 1. The information signals recorded by this system are:
Consider a color video signal or a digital video signal supplied from a digital line. Examples of digital lines include satellite broadcasting, telephone lines, and cable television.

First, recording when the input signal is an analog signal will be described. The analog signal input from the input terminal 1 is sent to the switching circuit 10. The switching circuit 10 switches so as to connect the input signal to the recording system analog signal processing circuit 30. The signal input to the recording system analog signal processing circuit 30 is subjected to predetermined recording signal processing. Here, as an example, the current home VTR (VHS
Method). That is, the color video signal is separated into a luminance signal and a color signal, and the luminance signal is F
This is a method in which M modulation is performed and a color signal is converted into a low frequency band and then superimposed on an FM modulated luminance signal to be recorded. The analog recording signal subjected to the signal processing by the recording-system analog signal processing circuit 30 is sent to the switching circuit 11. Switching circuit 11
Switches so that the output of the recording system analog signal processing circuit 30 is connected to the recording amplifier 50, and the analog recording signal is transmitted through the recording amplifier 50 to the magnetic heads 53, 53 '.
Sent to The magnetic heads 53, 53 'are, for example, 1
It is assumed that they are arranged facing each other by 80 °. The magnetic tape 52 is wound around the cylinder 55 by 180 ° or more, and the recording signal is recorded on the magnetic tape 52 by the magnetic heads 53 and 53 ′. Here, cylinder 5
5. The magnetic tape 52 is controlled by the servo control circuit 65 at a predetermined cylinder rotation speed and tape feeding speed. The control signal generation circuit 40 generates a predetermined control signal synchronized with the input signal and sends it to the switching circuit 14. The switching circuit 14 switches so as to connect the control signal generating circuit 40 and the control head 45 during recording. The control signal output from the control signal generation circuit 40 is recorded on the magnetic tape 52 by the control head 45 via the switching circuit 14. This control signal is used for servo control during reproduction.

The servo control will be described with reference to FIG. A recording control signal (FIG. 2 (2)) synchronized with the analog input signal (FIG. 2 (1)) is generated by the control signal generation circuit 40 and recorded on the magnetic tape 52. This control signal is used as a reference signal for the rotation phase of the cylinder 55 during reproduction. Although not shown, a pulse generator PG is attached to the cylinder 55 at a position with a 180 ° phase shift, and is used for detecting the rotation phase of the cylinder 55 and for output switching signals of the magnetic heads 53, 53 ′. 2 (3) and 2 (4) show the detection pulse of the PG. The head switching signal shown in FIG. 2 (5) is generated from this detection pulse to switch the outputs of the magnetic heads 53 and 53 '. On the other hand, the control signal reproduced by the control head 45 (FIG. 2 (6)) is waveform-shaped and becomes a reproduction control signal (FIG. 2 (7)). The servo control circuit 65 operates so as to maintain a predetermined phase relationship between the PG detection pulse and the reproduction control signal. At this time, the reproduction control signal serving as the reference signal uses only one edge thereof, that is, the rising edge in the example of FIG.

Next, the reproduction signal processing of the analog signal will be described. The outputs of the magnetic heads 53 and 53 'are sent to the switching circuit 12 via the reproduction amplifier 57. on the other hand,
The reproduction control signal from the control head 45 is input to the identification circuit 60 and the servo control circuit 65 via the switching circuit 14. The switching circuit 14 switches so as to connect to the control head 45, the identification circuit 60, and the servo control circuit 65 during reproduction. Identification circuit 60
Then, the type of the recorded signal is identified from the reproduction control signal, and the servo control circuit 65 controls a predetermined tape feeding speed, cylinder rotation speed, etc. according to the result and the reproduction control signal. The operation of the identification circuit 60 will be described later in detail. Based on the identification result, the switching circuit 12 automatically connects the reproduction amplifier 57 and the reproduction system analog signal processing circuit 80, and the switching circuit 13 automatically connects the reproduction system analog signal processing circuit 80 and the output terminal 5. Switch. The reproduced analog signal is input to the reproduction system analog signal processing circuit 80 and subjected to predetermined reproduction signal processing, that is, signal processing reverse to that at the time of recording. First, after separating the luminance signal and the color signal, the luminance signal is FM demodulated,
The color signal is frequency-converted and then synthesized again with the luminance signal. The reproduced analog signal subjected to the above reproduction signal processing is output from the reproduction system analog signal processing circuit 80 through the switching circuit 13 from the output terminal 5.

Next, the case of digital recording will be described. The digital signal input from the input terminal 1 is input to the switching circuit 10. The switching circuit 10 is switched to be connected to the recording system digital signal processing circuit 20, and the digital input signal is sent to the recording system digital signal processing circuit 20. The signal input to the recording system digital signal processing circuit 20 is subjected to predetermined recording signal processing, for example, an error correction code is added, and signal processing for digital modulation is performed to generate a digital recording signal. The digital recording signal processed by the recording system digital signal processing circuit 20 is sent to the switching circuit 11. The switching circuit 11 switches so as to connect the digital recording signal to the recording amplifier 50, and the digital recording signal is sent to the magnetic heads 53 and 53 ′ via the recording amplifier 50 and recorded on the magnetic tape 52. Here, the cylinder 55 and the magnetic tape 52 are controlled by the servo control circuit 65 at a predetermined cylinder rotation speed and tape feeding speed. The control signal generation circuit 40 also generates a predetermined control signal in synchronization with the input signal and sends it to the switching circuit 14. The switching circuit 14 switches so as to connect the control signal generating circuit 40 and the control head 45 during recording. The control signal output from the control signal generation circuit 40 is recorded on the magnetic tape 52 by the control head 45 via the switching circuit 14.

Servo control is basically the same as during analog recording. A recording control signal basically synchronized with the digital input signal is generated by the control signal generation circuit 40 and recorded on the magnetic tape 52. This control signal is used as a reference signal for the rotation phase of the cylinder 55 during reproduction. A pulse generator PG is attached to the cylinder 55 at a position 180 ° out of phase,
This detection pulse is used for the detection of the rotation phase of the cylinder 55 and the output switching signal of the magnetic heads 53, 53 '. On the other hand, the servo control circuit 65 operates so as to maintain the control signal reproduced by the control head 45 and the detection pulse in a predetermined phase relationship. At this time, the reproduction control signal serving as the reference signal uses only one edge thereof, for example, the rising edge.

Next, the reproduction signal processing of the digital signal will be described. The outputs of the magnetic heads 53 and 53 'are sent to the switching circuit 12 via the reproduction amplifier 57. The reproduction control signal reproduced by the control head 45 is input to the identification circuit 60 and the servo control circuit 65 via the switching circuit 14. The switching circuit 14 switches so as to connect to the control head 45, the identification circuit 60, and the servo control circuit 65 during reproduction. Identification circuit 60
Then, the type of the recorded signal is identified from the reproduction control signal, and the servo control circuit 65 controls a predetermined tape feeding speed, cylinder rotation speed, etc. according to the result and the reproduction control signal. According to the identification result of the identification circuit 60, the switching circuit 12 connects the reproduction amplifier 57 and the reproduction system digital signal processing circuit 70, and the switching circuit 13 connects the reproduction system digital signal processing circuit 70 and the output terminal 5. Automatically switches to. The circuit configuration and circuit operation of the identification circuit 60 will be described in detail later. The reproduced digital signal is input to the reproduction system digital signal processing circuit 70 and subjected to predetermined reproduction signal processing. Basically, the reproduced signal is digitally demodulated, and error correction is performed using the error correction code added during recording. The reproduced digital signal subjected to the above reproduction signal processing is output from the reproduction system digital signal processing circuit 70 through the switching circuit 13 from the output terminal 5.

As described above, by providing both analog recording and digital recording signal processing circuits,
Digital recordable / reproducible and conventional analog VT
A VTR that can also be used as R can be realized. It is expected that various types of digital video services will emerge in the future, but this can be dealt with by providing a signal processing circuit that performs signal processing in a format suitable for each type.

In such a VTR, analog recording portions and digital recording portions may be recorded in a mixed manner on the same recording medium. However, it is not convenient for the user to identify the type of the signal recorded during reproduction and switch the reproduction mode. In addition, as described above, a VT compatible with a plurality of digital video services
Considering R, automatic identification of a recording signal at the time of reproduction is essential.

A method of identifying a recording signal using a control signal according to the present invention will be described below. The control signal is used as a reference signal for servo control as described above, but what is actually used as a reference is information on one edge (a rising edge in the embodiment). Therefore, in the present invention, the polarity change point and the duty ratio of the control signal to be recorded are changed depending on whether the signal is an analog signal or a digital signal. An example of digital signal recording is shown in FIG. For example, when an analog signal is recorded as described above, a control signal having a duty ratio of 50% is recorded as shown in FIG. 2 (2), and when a digital signal is recorded as shown in FIG. 3 (2) during analog recording. And record the control signal with the polarity change point changed. At this time, the output of the control head 45 and the reproduction control signal obtained by reproducing the digital signal are as shown in FIGS. 3 (6) and 3 (7). As described above, the servo control uses only one edge of the reproduction control signal (the rising edge of the control signal in this embodiment). Therefore, recording the control signal with the duty ratio changed as described above does not affect the servo control at all. In this embodiment, an example in which the rising edge of the control signal is used as the servo reference signal will be described, but the present invention is not limited to this. By changing the polarity change point between the edge used as the servo reference signal and the opposite edge, it can be used for data identification without affecting servo control.

As described above, by changing the polarity change point of the control signal at the time of recording and detecting the difference of the polarity change point at the time of reproduction, it is possible to identify the recording signal. FIG. 4 shows a configuration example of the identification circuit 60. In FIG. 4, 100 is an input terminal for the output from the control head 45, 110 is a waveform shaping circuit that shapes the head output to detect rising and falling edges of the control signal, 120 is a monostable multivibrator, and 13
0 is a D flip-flop. The circuit operation is shown in FIGS.
Will be explained. FIG. 5 is a diagram for explaining the circuit operation in the case of analog recording and FIG. 6 is a diagram for explaining the circuit operation in the case of digital recording. First, the case of analog recording will be described. Reproduction output of control head 45 (Fig. 5 (1))
Is input from the input terminal 100 of the identification circuit 60 and sent to the waveform shaping circuit 120. In the waveform shaping circuit 120,
Signal with rising and falling edges shaped
((2) and (3) in FIG. 5) is output. The signal CU (FIG. 5 (2)) whose rising edge is detected is the same as the reproduction control signal of FIG. 3 (7). The signal CU drives the monostable multivibrator 120 to obtain an output signal JG (FIG. 5 (4)) having a predetermined pulse width τ. At this time, the predetermined pulse width τ is determined by the polarity change point of the control signal to be recorded, and is longer than the time τ2 (shown in FIG. 6) from the rising edge to the falling edge during digital recording and is longer than that during analog recording. Is shorter than the time τ1 (shown in FIG. 5). Then, the signal CD (FIG. 5) in which the falling edges of the signal JG and the control signal are detected
(3)) is input to the D flip-flop 130. D
The flip-flop 130 outputs the polarity of the signal JG when the control signal falls. In the example of FIG. 5, since the pulse width τ of the signal JG is set to satisfy τ2 <τ <τ1, the output of the D flip-flop 130,
That is, the polarity of the identification signal becomes Low level.

On the other hand, the case of digital recording will be described with reference to FIG. Reproduction output of the control head 45 (Fig. 6)
(1)) is input from the input terminal 100 of the identification circuit 60 and sent to the waveform shaping circuit 120. Waveform shaping circuit 12
At 0, the signals (FIGS. 6 (2) and 6 (3)) in which the rising edge and the falling edge are shaped are output. The signal CU (FIG. 6 (2)) whose rising edge has been detected is the same as the reproduction control signal of FIG. 3 (7). The signal CU drives the monostable multivibrator 120 to obtain an output signal JG (FIG. 6 (4)) having a predetermined pulse width τ. At this time, the predetermined pulse width τ is determined by the polarity change point of the control signal to be recorded, and is the time τ1 from the rising edge to the falling edge during digital recording.
Longer (shown in FIG. 6), time τ2 during analog recording
It is shorter (shown in FIG. 5). And signal J
The signal CD (FIG. 6 (3)) in which G and the falling edge of the control signal are detected is input to the D flip-flop 130. The D flip-flop 130 outputs the polarity of the signal JG when the control signal falls. Figure 6
In the example, the pulse width τ of the signal JG is set so that τ2 <τ <τ1. Therefore, the D flip-flop 1
The output of 30, that is, the polarity of the identification signal becomes High level. In this way, by detecting the difference in the polarity change points of the control signal, it becomes possible to automatically identify the type of the recorded signal during reproduction. According to the method of the present invention, it is possible to newly use it as an identification signal of a recording signal without affecting the point of the servo control reference signal which is the purpose of the conventional control signal.

FIG. 7 is a diagram for explaining the operation when the time τ3 from the rising edge to the falling edge of the control signal during digital recording is set longer than the time τ1 during analog recording. In this case, the pulse width τ of the monostable multivibrator 120 is set so that τ1 <τ <τ3. At this time, the polarity of the identification signal is Low in digital recording and the polarity of the identification signal is High in analog recording. In this way, although the polarities of the identification signals are different, it is possible to identify the recording signals as in the example of FIG.
However, in the example of FIG. 6, the maximum time until identification is τ1, whereas in the example of FIG. 7, it takes a maximum of τ3.
Therefore, when recording by changing the control signal, the time required for identification is minimized by changing the control signal before the polarity change point (τ1) of the control signal during analog recording as in the example of FIG. To be suppressed.

In this embodiment, a VTR capable of recording one type of analog recording and one type of digital recording is taken as an example. However, there are several types of video information services that serve as input signals, such as satellite broadcasting and cable television. Therefore, a VTR may support many types of signals, not just two. Even in that case, by changing the polarity changing point of the control signal corresponding to each signal, the recorded signal can be identified without any problem during reproduction.

FIG. 8 shows a structural example of the discrimination circuit 60 for discriminating three types of signals. In FIG. 8, 100 is an input terminal, 110 is a waveform shaping circuit, 120 is a monostable multivibrator, 130 is a D flip-flop, and 140.
Is an identification pulse generation circuit composed of a monostable multivibrator 120 and a D flip-flop 130, 141 is an identification pulse generation circuit composed of a monostable multivibrator and a D flip-flop, as in 140, and 105 is an output terminal of an identification signal Is. The basic operation is the same as that of the identification circuit shown in FIG. The difference is that the output pulse widths of the monostable multivibrators forming the identification pulse generating circuits 140 and 141 are set according to the polarity change points of the control signal during recording. Figure 9
The operation of the identification circuit 60 shown in FIG. 8 will be briefly described using. First, the reproduction control signal input from the input terminal 100 is sent to the waveform shaping circuit 110. The reproduction control signal is recorded by changing the polarity changing point according to the recording signal, that is, by changing the duty ratio.
9 (1), (2), and (3) show reproduction control signals in each case. The time from the rising edge to the falling edge of the control signal is different from .tau.1, .tau.2, .tau.3 for the recording signals 1, 2, and 3, respectively. The reproduction control signal is a waveform shaping circuit 110.
Is shaped into a signal CU indicating a rising edge and a signal CD indicating a falling edge, and the identification pulse generation circuit 14
0,141. Identification pulse generation circuit 140,
In 141, the output pulse widths of the monostable multivibrator are set to τa and τb, respectively (FIG. 9 (8),
(9)), driven at the rising edge of the control signal. Here, the pulse width of the monostable multivibrator is set to τ3 <τa <τ2 <τb <τ1. As a result, the outputs J1 and J2 of the identification pulse generation circuits 140 and 141
Is as follows. In the case of the recording signal 1, the reproduction control signal is as shown in FIG. 9 (2), and J1 = Low, J2
= High is obtained. In the case of the recording signal 2, the reproduction control signal is as shown in FIG. 9 (5), and J1 = Low,
J2 = Low is obtained. In the case of the recording signal 3, the reproduction control signal is as shown in FIG. 9 (7), and J1 =
High, J2 = High is obtained, and identification is possible. As described above, by changing the polarity changing point of the control signal in correspondence with the recording signal and recording, the recording signal can be automatically identified at the time of reproduction.

The configuration of the discrimination circuit of this embodiment uses the monostable multivibrator, but the present invention is not limited to this, and it is possible to detect the difference in the polarity change points of the reproduction control signal and the difference in the duty ratio. The circuit configuration works without problems.

The above identification method using the control signal has the following advantages. That is, the format suitable for the recording signal can be set relatively freely if only the recording area of the control signal on the recording medium is matched.
For example, even if the tape speed is changed according to the amount of information to be recorded and the inclination or the like of the recording track of the video information changes, the control track is not affected at all, so that the recording signal can be reliably identified.

Further, although the present embodiment does not touch on the channel division recording, it is also effective for the channel division recording.

[0028]

As described above, according to the present invention, an information recording / reproducing apparatus capable of both analog recording and digital recording can be realized, and a recording signal is automatically identified when reproducing. Therefore, it is possible to provide a recording / reproducing device that is easy for the user to use. Further, if the compatibility is maintained only in the recording area of the control signal, the recording signal can be identified, so that the degree of freedom in determining the recording format is relatively high.

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating servo control during analog recording.

FIG. 3 is a diagram illustrating servo control during digital recording.

FIG. 4 is a block diagram showing a configuration example of an identification circuit 60.

FIG. 5 is a signal waveform diagram for explaining the operation of the identification circuit 60 during analog recording.

FIG. 6 is a signal waveform diagram for explaining the operation of the discrimination circuit 60 during digital recording.

FIG. 7 is a signal waveform diagram for explaining the operation of the identification circuit 60 during digital recording.

FIG. 8 is a block diagram showing a configuration example of an identification circuit 60 corresponding to a plurality of types of signals.

9 is a signal waveform diagram for explaining the operation of the identification circuit 60 shown in FIG.

[Explanation of symbols]

20 ... Recording system digital signal processing circuit, 30 ... Recording system analog signal processing circuit 10, 11, 12, 13, 14, ...
Switching circuit, 40 ... Control signal generating circuit, 65
... servo control circuit, 60 ... identification circuit, 70 ... reproduction system digital signal processing circuit, 80 ... reproduction system analog signal processing circuit.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H04N 5/93 (72) Inventor Jinro Owase 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Video Media Laboratory (72) Inventor Nobutaka Amada 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Stock Company Hitachi Ltd.Video Media Laboratory (72) Inventor Shigeru Yamazaki 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Hitachi Inside the Visual Media Research Center

Claims (3)

[Claims] 1. An information recording / reproducing apparatus for recording / reproducing on / from a magnetic recording medium by a rotary magnetic head, and recording system analog signal processing means for performing predetermined recording signal processing on an input analog signal, and predetermined for an input digital signal. Recording system digital signal processing means for performing recording signal processing, means for generating a control signal serving as a servo reference signal, means for recording / reproducing the control signal on a magnetic tape, and data recorded from the reproduction control signal A reproduction system analog signal processing means for performing a predetermined reproduction signal processing on the reproduced analog signal, and a reproduction system digital signal processing means for performing a predetermined reproduction signal processing on the reproduced digital signal. In addition, at the time of recording, recording signal processing is performed by the above predetermined recording signal processing means according to an input signal, and The means for generating the control signal records a control signal having a predetermined polarity change point corresponding to each signal to be recorded, and the means for identifying the recorded data at the time of reproduction is the polarity change of the reproduced control signal. An information recording / reproducing apparatus characterized in that recorded data is identified by detecting a point, the reproduction signal processing means is switched based on the identification result, and predetermined reproduction signal processing is performed. 2. The information recording / reproducing apparatus according to claim 1, wherein the predetermined polarity change point of the control signal makes an edge position opposite to an edge used as a reference for servo control different. 3. The information recording / reproducing apparatus according to claim 1, wherein the recording area of the control signal on the magnetic recording medium is not changed regardless of whether the recording signal is an analog signal or a digital signal.