JP3029130B2 - Rotating head type playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type reproducing apparatus, and more particularly to an apparatus for reproducing a signal from a tape-shaped recording medium by sequentially using a plurality of rotary heads.

[0002]

2. Description of the Related Art Conventionally, a video tape recorder (VTR)
In order to make the playback screen easier to see when the player enters an unrecorded portion of the magnetic tape during the playback operation, the playback video signal is displayed on a predetermined self-oscillation screen (a so-called blue back or the like).
There is a known technique for substituting for the following.

It is also known to use such detection of an unrecorded portion for detection of an unrecorded portion, so-called blank search.

Further, in general, when a reproduced signal is used for detecting the unrecorded portion, when the reproduced signal is not used, a good reproduction signal cannot be obtained. Switching between the modes may be considered.

Conventionally, the detection of a non-recording portion as described above is performed by detecting the period of a tracking control pulse signal (hereinafter, simply referred to as CTL) reproduced from the fixed head during reproduction, or detecting the period from the reproduction head. The reproduction RF signal is monitored for a predetermined period.

[0006]

However, in recent years,
In this type of device, the mechanism is simplified without using a fixed head, and the size and weight of the device are reduced, and the CTL described above cannot be used in this type of device.

In the method of monitoring the reproduction RF signal over a predetermined period as described above, it is necessary to lengthen the monitoring period due to the existence of various reproduction modes. That is, there are a plurality of recording modes having different tape transport speeds, such as slow motion reproduction, and reproduction of a recording tape that is difficult to track (for example, when reproducing a tape on which a PAL signal is recorded on an NTSC VTR). In view of this, it is necessary to check the reproduced RF signal over a relatively long period.

In addition, when the above-mentioned monitoring is performed by a microprocessor, it is sometimes difficult to secure a sufficient period for the above-mentioned monitoring due to a limitation in software configuration, which causes erroneous detection and malfunction. I was

Under such a background, an object of the present invention is to provide a rotary head type reproducing apparatus capable of quickly and reliably detecting a non-recording portion of a tape-shaped recording medium.

[0010]

For such a purpose,
According to the present invention, in an apparatus for reproducing a signal from a tape-shaped recording medium using a plurality of rotary heads, a detecting unit for detecting a signal reproduced by the plurality of rotary heads, and an output of the detecting unit Sample means for sampling each rotating head; detecting means for performing a logical operation on the plurality of sample results for all of the plurality of rotating heads and detecting a non-recording portion of the tape-shaped recording medium based on the calculation result; Is provided.

[0011]

According to the above-described structure, it is possible to immediately discriminate the defective recording or the head clogging from the reproduction of the non-recorded portion, and to quickly and quickly record the non-recorded portion of the tape-shaped recording medium. It has become possible to detect it reliably.

[0012]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram showing a schematic configuration of a video tape recorder (VTR) as one embodiment of the present invention.
FIG. 2 is a diagram showing a schematic configuration of a tape running system of the VTR of FIG.

In FIG. 1, reference numerals Ha, Hb, Hc and Hd denote reproduction rotary heads, respectively, and reference numerals 2a, 2b, 2c and 2d denote reproduction amplifiers for amplifying reproduction signals of the reproduction heads Ha, Hb, Hc and Hd, respectively. , 3c are switches for selectively outputting the reproduced signals of the four rotating heads according to the rotating phases of the rotating heads.

In the VTR of this embodiment, the tape 25
Is wound around the drum D of FIG. 2 over an angular range of 270 ° or more, and the four reproducing heads Ha to Hd rotate with a phase difference of 90 ° from each other, and Ha, Hb, Hc, Hd. The method of sequentially recording video signals for one field in this order is adopted. As is well known, the head Ha and the head Hc have the same azimuth angle, and the head Hb and the head Hd have the same different azimuth angle.

Reference numeral 4 denotes a reproduced video signal processing circuit for reproducing a video signal from a reproduced RF signal obtained through the switches 3a, 3b, 3c, 5 an output terminal of the reproduced video signal,
Reference numeral 6 denotes a detection circuit that detects the reproduced RF signal, and reference numeral 7 denotes a comparator that outputs a high-level signal when the detection output of the detection circuit is equal to or lower than a predetermined voltage. That is, when the output signal of the comparator 7 is at the high level, it indicates that the reproduced RF signal is at or below the predetermined level.

Reference numeral 8 denotes a reference voltage generation source for reducing the comparison reference level in the comparator 7. Reference numeral 9 designates a binary signal (high level and low level) output from the comparator 7 as input data, and sequentially holds and shifts the data by a clock signal. The shift register 10 is an AND circuit that inputs in parallel the outputs from a plurality (four) of ports from which the internal data of the shift register 9 is taken out.

Reference numeral 11 denotes a servo / system controller for controlling each part of the VTR of the present embodiment, which comprises a microprocessor and its peripheral circuits.

In the VTR of this embodiment, in the servo / system controller 11, the drum motor 26 and the capstan motor 27 shown in FIG.
The servo / system controller 11 is configured to generate a drum rotation frequency detection signal (hereinafter, referred to as DFG) that detects the rotation frequency of the drum motor 26, and a drum rotation phase detection signal. (Hereinafter referred to as DPG) and a capstan motor rotation frequency detection signal (hereinafter referred to as CFG).

The servo / system controller 11 uses these inputs to convert a drum rotation control signal and a capstan rotation control signal into a drum motor control circuit 1.
7 and the capstan motor control circuit 18 respectively. Since the software servo is not directly related to the present invention and has a well-known content, a detailed description thereof will be omitted in this specification.

Reference numeral 12 denotes an operation unit for determining the operation mode of the VTR of this embodiment, and 19 denotes a tape loading motor control circuit which operates according to the operation of the operation unit 12.

Hereinafter, detection of a non-recording portion in the VTR of the present embodiment will be described in detail with reference to the timing chart of FIG.

In the present embodiment, in the reproduction mode, whether or not a non-recording portion is constantly detected.
When a command for detecting a non-recorded portion, such as a blank search command, is issued, the reproduction amplifiers 2a, 2b, 2c, 2
Operate d.

As described above, the reproduced RF signal detected by the detection circuit 6 is compared with the reference voltage from the reference voltage generation source 8. When the output from the detection circuit 6 is lower than the reference voltage, the high level output is output. Is obtained.

On the other hand, the servo / system controller 11
In, the operation of forming a rotation control signal for the drum motor 26 by the DPG 13 and DFG 14 is performed.
In synchronization with this operation, the switches 3a, 3 of the reproduced RF signal
Head switching pulses 23 and 24 for operating b and 3c are output. The head switching pulse is as shown in FIG.
It will be apparent that the outputs of a, Hb, Hc, Hd are output sequentially. Therefore, as described above, a continuous reproduced RF signal is obtained at the output terminal of the switch 3c.

The input clock 20 of the shift register 9 is
As shown in FIG. 3, the reproducing heads Ha, Hb, Hc, and H are formed in synchronization with the head switching pulse.
d includes one pulse at the same timing of the video signal of one field to be reproduced.

The binary signal output from the comparator 7 by the clock 20 is sequentially taken into the shift register 9 and is held and shifted. The output of the AND circuit 10 is checked by the microprocessor in the servo / system controller 11,
When the output of the AND circuit 10 goes high, that is, when the levels of the reproduced RF signals relating to the four reproducing heads all become lower than a predetermined value as shown in FIG. Judge that there is.

In response to this determination, the servo / system controller 11 controls each unit of the device. For example, in the reproduction mode, the reproduction video signal processing circuit 4 is accessed to switch the reproduction video signal to a predetermined self-oscillation screen such as a blue screen and output the screen. In the blank search, when the tape is running at a high speed, an operation of controlling the capstan motor control circuit 18 to stop the tape running, an operation of setting the VTR to the recording standby mode, and the like are performed.

In the embodiment having the above-described configuration, a detection signal of a reproduced RF signal obtained by sequentially using a plurality of rotary heads is sampled at a predetermined timing in synchronization with the rotation of each rotary head. When a no-signal state is continuously indicated by the number corresponding to the number of heads, the detection itself is performed in an extremely short time because the non-recording portion is detected. Further, at this time, even if the tape conveying speed or the tracking state is different, the determination is made by the logical product of the four detection signals, so that there is almost no erroneous determination, and reliable detection is possible.

In this embodiment, the comparator 7, the shift register 9, and the AND circuit 10 are
C, which is configured as hardware using a digital IC, the output signal of the detection circuit 6 may be directly captured into the A / D input port of the microprocessor at the timing of the clock 20, thereby configuring these as software. It is possible.

Further, the output signal of the comparator 9 is connected to the port of the microprocessor and is read at the timing of the clock 20 in the same manner.
The AND circuit 10 may be configured by software.

[0032]

As described above, according to the rotary head type reproducing apparatus of the present invention, it is possible to detect the non-recorded portion of the tape-shaped recording medium quickly and reliably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a video tape recorder (VTR) as one embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a tape running system of the VTR of FIG.

FIG. 3 is a timing chart for explaining a non-recording portion detection operation of the VTR of FIG. 1;

[Explanation of symbols]

 Ha, Hb, Hc, Hc Reproduction rotary head 2a, 2b, 2c, 2d Reproduction amplifier 3a, 3b, 3c Switch 4 Video signal reproduction processing circuit 6 RF signal detection circuit 7 Comparator 8 Reference voltage generation source 9 Shift register 10 AND circuit 11 Servo / system controller 12 Operation keys 17 Drum motor control circuit 18 Capstan motor control circuit

Claims (4)

(57) [Claims] 1. An apparatus for reproducing a signal from a tape-shaped recording medium using a plurality of rotary heads, comprising: a detecting means for detecting a signal reproduced by the plurality of rotary heads; A sampler that samples each head; and a detector that performs a logical operation on a plurality of sample results for all of the plurality of rotary heads and detects a non-recording portion of the tape-shaped recording medium based on the operation result. Rotating head type playback device. 2. The rotating head type reproducing apparatus according to claim 1, wherein said sampling means samples an output of said detecting means in accordance with a signal synchronized with said rotating head. 3. The transport of the tape-shaped recording medium according to an output of the detecting means.
A rotary head type reproducing apparatus as described in the above. 4. An apparatus for reproducing a signal from a tape-shaped recording medium by using a plurality of rotary heads, wherein: a detecting means for detecting a signal reproduced by the plurality of heads; Sampling means for sampling each time, and detecting when the plurality of sample results for all of the plurality of rotary heads indicate a no-signal state, that the signal is a non-recording portion of the signal on the tape-shaped recording medium. And a rotating head type reproducing apparatus.