JP3227935B2 - Magnetic recording / reproducing 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 magnetic recording / reproducing apparatus capable of detecting clogging of a magnetic head or the like (hereinafter referred to as clog).

[0002]

2. Description of the Related Art In a conventional magnetic recording / reproducing apparatus, when there are a plurality of reproduction signals having different information (for example, information such as a luminance signal and a chrominance signal of a video signal) at the same time, each reproduction signal is A detection circuit and a comparator are provided for each signal to detect the lack of the reproduced signal. In such a conventional magnetic recording / reproducing apparatus, since the loss of the reproduction signal can always be detected, when the loss of the reproduction signal occurs, it is possible to immediately correct or repair the lost signal.

[0003]

However, when a reproduced signal is lost, a magnetic recording / reproducing apparatus which does not use the reproduced signal missing information for interpolation, correction and restoration of the missing signal,
For example, in a digital VTR with an error correction function,
In some cases, it may be sufficient to only issue a warning with light, sound, or the like based on the reproduction signal missing information.

In such a case, there is a problem that the circuit scale becomes large and the cost becomes high when the number of reproduced signals is large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording / reproducing apparatus in which only a warning is issued only when a reproduced signal is lost as described above. To get.

[0006]

In order to achieve the above object, the present invention provides a selecting means for selecting one of a plurality of reproduction signals, a control means for providing a control signal to the selecting means, A detecting means for detecting an output signal of the detecting means, and a comparing means for comparing the level of the output signal of the detecting means.

[0007]

In the magnetic recording / reproducing apparatus of the present invention having the above-mentioned structure, by obtaining the output signal of the comparing means as the reproduced signal missing information, the information of the signal missing generated in the plurality of reproduced signals is obtained by a set of the detecting means and the comparing means. Can be obtained at

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows one embodiment of the present invention.
FIG. 2 is a block diagram showing a system configuration of a rotary head type magnetic recording / reproducing apparatus using four heads 1, 2, 3, and 4 indicated by B, C, and D.

In FIG. 1, signals reproduced by a head 1 (A head) and a head 2 (B head) pass through a rotary transformer 11 and a reproducing amplifier 5 to become a reproduced signal 7 of an A / B head. Similarly, the signals reproduced by the head 3 (C head) and the head 4 (D head) pass through the rotary transformer 11 and the reproduction amplifier 6 to become the reproduction signal 8 of the C / D head. The reproduction signal 7 and the reproduction signal 8 are alternately selected and output at a fixed time interval by a reproduction signal selection switch 9 and a switch switching signal 10 output from a control circuit (not shown), and become a mixed reproduction output signal 14. . The mixed reproduction output signal 14 is detected by the detection circuit 12 to become an envelope detection signal 15, which is compared with the reference level 18 by the comparator 13. Then, the LED of the clog warning circuit 17 emits light to notify the user that a head clog has occurred.

FIG. 2 is a waveform diagram showing signal waveforms at various parts in FIG. Here, the suffixes attached to the reference signs A to D indicate the number of reproduction output of each head.

In FIG. 2, the reproduced signals 7 and 8 are such that the A head causes clogging in a part of the A1 section and the B head
Clogging occurs in a part of the two sections, indicating that the D head is continuously clogged. When the switch switching signal 10 is at a high level, the reproduction signal 7 of the A / B head is selected, and when it is at a low level, the reproduction signal 8 of the C / D head is selected. As a result, A1 of A head
It can be seen that partial clogging of the section and clogging of the D head in the D2 section have been detected.

Although a period in which clogging of the head cannot be detected occurs as in the period D1 in FIG. 2, continuous clogging of the head can be sufficiently detected, and there is no practical problem.

As described above, according to the present invention, the detection circuit 1 is controlled by the reproduction signal selection switch 9 and the switch switching signal 10.
2 and the reproduction signal input to the comparator 13 can be divided and input in time series, so that even if there are a large number of reproduction signal outputs, only one detection circuit and one comparator are necessary for detecting the head clog. Can be configured.

Although the switch signal 10 is switched every frame (two fields) in FIG. 2, it may be switched in units of a plurality of frames.

[0016]

As is apparent from the above description, according to the present invention, since the reproduction signal selection switch is provided in front of the detection circuit and the comparator, even if there are a large number of reproduction signal outputs, the head clog is output. Only one detection circuit and comparator are required for detecting the signal, which enables downsizing, weight reduction, and cost reduction of the device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a waveform chart showing waveforms at various parts in FIG. 1;

[Explanation of symbols]

 9 Reproduction signal selection switch 10 Switch switching signal 12 Detection circuit 13 Comparator

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Claims (3)

(57) [Claims] 1. A magnetic recording / reproducing apparatus having a plurality of reproduction signals having different information at the same time, wherein said selection means selects one of said plurality of reproduction signals and said selection means comprises a plurality of reproduction signals. Control means for providing a control signal for specifying which of the reproduction signals to select, detection means for detecting an output signal of the selection means, and a reference voltage having a predetermined output level of the detection means. A magnetic recording / reproducing apparatus, comprising: comparing means for comparing, wherein an output signal of the comparing means is obtained as reproduction signal missing information. 2. The magnetic recording apparatus according to claim 1, wherein the control means provides the selection means with a control signal for sequentially selecting one of the plurality of reproduction signals at a constant interval. Playback device. 3. The control unit according to claim 1, wherein the control unit supplies the control unit with a control signal for sequentially selecting one of the plurality of reproduction signals at intervals of one frame or a plurality of frame periods. 3. The magnetic recording and reproducing device according to claim 1.