JPS59101084A - Rotary head type recorder - Google Patents

Abstract

PURPOSE:To detect a head clogging at recording by making a erasing rotary head perform erasing and reproducing operation by each one time. CONSTITUTION:Recording rotary heads 2A, 2B and one erasing rotary head 2E are fitted in the relation of position as shown in figure. The heads 2A, 2B, 2E perform respective operation at time axes in Figs. A, B, C respectively. Time t2-t5, t3-t5 correspond respectively to the range of angle of 180 deg. and 31 deg.. Since the head 2E is positioned ahead by 90 deg. from the 2A, an erasing current is applied to the head 2E at a time earlier by 90 deg.. Through the operation above, tracks TA, TB are formed alternately on a tape 3 as shown in Fig. D. A locus shown in broken lines in the figures is a locus by the head 2E. The locus when the track pitch is a half the value in Fig. D is shown in Fig. E. In this case, erasing is done by a locus 4A of the head 2E and the head 2E performs reproduction at the period when the next locus 4B is drawn. The head clogging is detected depending on the presence of the reproducing signal.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a rotary head type recording device equipped with a rotary head for erasing.

BACKGROUND ART AND PROBLEMS There is known a rotary two-head recording device that records video and/or audio signals on a magnetic tape using a rotary head. This is because conventional rotary two-head recording devices were constructed with two heads.

Since it was not possible to monitor recording, it was not possible to detect head gap clogging (referred to as head clog) that occurred during recording. Head clog occurs when magnetic powder separated from the magnetic tape gets stuck in the gap.

OBJECT OF THE INVENTION The object of the present invention is to provide a rotary head type recording device that is capable of detecting heald clogs during recording.

``Summary of the Invention'' The present invention enables reproduction during a recording operation by causing an erasing rotary head to perform an erasing operation and a reproducing operation every rotation.

In the present invention, when the running speed of the magnetic tape is the slower of two types of magnetic tape running speeds of 1%, the nine-rotary head performs the reproducing operation during the period when the nine-rotary head does not have to perform the erasing operation.

"Embodiment" An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 indicates a one-rotation drum, and this rotary drum 1 rotates clockwise at a field frequency. Attached to the rotary drum 1 are recording rotary heads 2A, 2B and one erasing rotary head 2E. The rotating heads 2At2B are arranged at angular intervals of 180°, and the 1-turning head 2E is provided at a position preceding the two 1-turning heads by an angular interval of 90°. Also, the one-rotation heads 2A and 2B.

placed at the same height. Furthermore, for inclined azimuth recording, the extension directions of the gaps of the 9-rotation heads 2 + 2 B are different (for example, ±10). The reason for using one rotary head instead of two for erasing is to save on the number of heads.

Fixed tape guide drums (not shown) having the same diameter are provided above and below the rotating drum 1, and the magnetic tape 3 is wound obliquely around the cylindrical surface formed by these drums.
In this state, the vehicle is run at a predetermined speed in the direction of the arrow. The winding angle θ of this magnetic tape 3 is 180 or more, for example, with an interval of 221°. Therefore, one rotation of heads 2A, 2B is 3
The magnetic tapes 3 are in sliding contact with each other within a tape winding angle range of 1. In this overlap section, one field's worth of PCM audio signals that have been compressed on the time axis are recorded. In this case, a no-signal interval of a period corresponding to the angular range of 3 is interposed between the recording interval of the color video signal and the recording interval of the audio PCM signal in order to avoid the influence of signal switching transients.

Also, since only one one-rotation head 2E is killed, when the magnetic tape 3 is scanned once, the one-rotation head 2A1
The erased track width of the one-rotation head 2E is made larger than the track width of the rotary heads 2A and 2B so that the area scanned by the head 2B can be erased in advance. For example, rotating heads 2A, 2
Track width H1 of B is 16 μm 1 rotation head Rotary head 2
The human width H3 is assumed to be 40 pm.

Further, in this embodiment, the running speed of the magnetic tape 3 during recording can be set to two types: a first running speed and a second running speed. This switching is performed by changing the speed of the capstan that runs the magnetic tape 3. The track pitch P1 at the first running speed is 20 μm, and the track pitch P at the second running speed is 10 μm. Figure 2 is.

This is to explain the recording operation in the case of the first running speed. When two rotating heads start sliding on the magnetic tape 3 at the timing shown by tl, the audio PCM signal is recorded in an interval corresponding to an angular range of 28 degrees. Recording of the video signal is started at the timing indicated by t after the no-signal interval of the interval corresponding to the angular range of the first and third angles.

When recording a color video signal, the )t51 degree signal is FM modulated and one color signal is converted to a low carrier frequency (
For example, 688 KHz).

For the N degree signal, crosstalk from adjacent tracks is suppressed by using azimuth loss. Color signals.

For example, the phase of the carrier signal recorded on one of the adjacent tracks is inverted every LH (one horizontal interval) so that crosstalk from adjacent tracks can be removed by a comb filter provided in the reproducing circuit. Ru. This recorded color video signal is 1 from the timing shown by e t2.
The data is recorded up to the timing t5 corresponding to the angular range of 80, and after the timing t, the rotation head 2 is recorded again in the primary order.
Until timing t7 when a person comes into contact with the magnetic tape 3, there is a blank running section. Rotary head 2A shown in FIG.

The positional relationship between 2B and 2E is at timing t2.

At timing t4, which is a time corresponding to the angular range of 31 before the two rotating heads reach timing t, the one-rotating head 2B begins to come into sliding contact with the magnetic tape 3, and during this overlap period, the audio p CM signal is transferred to the rotating head. Recorded by 2B.

After timing t5, a color video signal is recorded by the rotary head 2B. And (t.

In the overlap period from ~t8), audio PCM signals are recorded by two heads making one revolution.

The rotary head 2E for erasing is 90
Since it is provided in the preceding position, the erasing current is supplied to the rotary head 2E at a timing earlier than the time corresponding to the angular range of 90. In FIG. 2C, the section (to""
At t3), an erase current is supplied to the rotary head 2E, and an erase operation is performed.

As a result of this operation, as shown in FIG. 3A, the tracks T A + T B of the magnetic tape 3 are formed on the rotating head 2A with a trunk pitch Pt (=20 μm).

2B alternately formed. In fig.

The locus shown by the broken line is due to the rotation Radar 2E. In addition, FIG. 3 shows the rotating heads 2A and 2B @ 2 at a point slightly before the timing tt (see FIG. 2).
The respective scan positions of E are shown.

Even when the running speed of the magnetic tape 3 is as described above, the audio PCM signal and the color video signal are recorded on the magnetic tape 3 by the same operation. In this case, since the track pitch is P2 (=10 .mu.m), as shown in the third [B], there is no guard band between the tracks TA and TB, and an area of 6 .mu.m width is recorded overlappingly. Furthermore, the pitch of the scanning locus of the one-rotation head 2E also varies. Therefore, as shown in No. 31"11B, the area in which four tracks are formed can be erased by the scanning trajectory 4A of the one-rotation head 2E, so when the next scanning trajectory 4B of the rotational head 2E is formed. There is no need to perform erasing.The rotating head 2E performs a reproducing operation once during the period in which the scanning locus 4B of the rotating head 2E is drawn.

When the track pitch is P2, as shown in FIG. 3B, the track formed by the 9-rotary head 2E is 1
It has a width of 6 μm, and the 6 μm width is rewritten when new recording is performed by two rotating heads in the 9th time. therefore.

Since the nine rotating heads 2E scan in advance for the two rotating heads, the rotating heads 2E scan this 6 μm wide area.
can reproduce the recorded signal.

In this case, a low frequency (for example, 100 KHz or less) pilot signal in the recorded signal is reproduced. This pilot signal is used for automatic tracking follow-up control, and is recorded, for example, on four consecutive tracks as signals of different frequencies. and,
By detecting the frequency and level of the pilot signal in the reproduced signal, the height of the head is varied by the piezoelectric element for one revolution so that the reproduced scanning trajectory accurately scans the track. Furthermore, even if tilt azimuth recording is performed, in the case of a low frequency pilot signal, this pilot signal can be reproduced by the one-rotation head 2E without causing azimuth loss.

When the rotary head 2E performs a reproducing operation, if a reproducing signal is obtained, it is determined that head clog has not occurred.

However, if no reproduction signal is obtained, it is detected that head clog is occurring in the two-rotation head 2E.

In this case, there is an abnormality in which erasing is not performed by the one-rotation head 2E.

Generally, when head clog occurs in one rotary head 2E, other 1111 rotary heads 2A, 2
It is determined that there is a high possibility that head clog will occur in B, or that head clog has already occurred. Therefore, when the clock of the 9-turn head 2E is detected.

An alarm is generated and recording operation is interrupted.

FIG. 4 shows a circuit according to an embodiment of the present invention (.j7 configuration), in which a recorded color video signal including a pilot signal is supplied to an input terminal indicated by 5, and one input terminal of each of the switch circuits S++82 is supplied with a recorded color video signal including a pilot signal. Furthermore, audio PCM1a is supplied to the input terminal indicated by 6, and is applied to the other input terminal of each of the switch circuits S1+82.

These switch circuits S H+ 82 are controlled by switching pulses from terminal 7.8. The switch circuit s, I s2 is the audio P
In the CM signal recording section, the other input terminal to which the audio P CM signal is supplied is connected to the output terminal.

In other sections, one input terminal to which the recorded color video signal is supplied is controlled to be connected to the output terminal.

The respective outputs of the switch circuits S1+Bt are supplied to the rotary heads 2A, 2B via recording amplifiers 9A, 9B and rotary transformers (not shown). The time-related recording signals shown in FIGS. A and 5B are for the rotary head 2A.

2B.

Further, in FIG. 4, 10 indicates an erase oscillation circuit,
The output of this erase oscillation circuit 10 at a frequency of, for example, 3.5 MHz is transmitted via the amplifier 11 to the terminal a of the switch circuit Ss.
supplied to A terminal d of this switch circuit S is supplied to the rotating head 2E via a rotating transformer (not shown).

Further, the reproduction output of the one-rotation head 2E is supplied to the reproduction amplifier 13 via the terminal d and the terminal S of the switch circuit S3. The output of this reproducing amplifier 13 is supplied to a detection circuit 14, and a detection signal is taken out to an output terminal 15 of this detection circuit 14. The above-mentioned switch circuit S8 also includes a terminal C, and when the terminal C and the terminal d are connected, the one-rotation head 2E is in an off state in which neither erasing nor reproducing operations are performed. This switch circuit S3 is controlled by a switching pulse from terminal 12.

The erasing operation and the reproducing operation are repeated every rotation, and the head 2E is turned off during a free running period during which the head 2E does not come into contact with the magnetic tape 3.

As shown in FIG. 5C, the rotary head 2E performs an erasing operation before the one-rotation head 2A performs a recording operation.

At this time, terminals a and d of the switch circuit S are connected, and an erase current is supplied to the one-rotation head 2E. Next 1
During the idle running period of the rotary head 2E, the terminals C and d of the switch circuit S3 are connected and turned off. In the next period of this off state, the terminals S and d of the switch circuit S3 are connected, and the regeneration state is entered.

As described above, in this reproduction state, the rotary head 2E draws the scanning locus 4B and reproduces the pie-four signal from a portion of the adjacent track. This reproduced signal is supplied to the detection circuit 14 via the amplifier 13.

This detection circuit 14 includes a rectifier circuit that rectifies the reproduced signal,
A comparison circuit is provided to compare the output of the rectifier circuit with a reference level. This comparison circuit compares whether the reproduced signal is higher than a reference level or not, and the comparison result is outputted to the output terminal 15 as a detection signal. This detection signal is supplied to alarm generation circuits such as lamps and buzzers, and system control circuits that control the operation of the VTR.

When the playback output level is lower than the reference level.

An alarm is generated, a recording operation is canceled, etc.

"Application Example" The rotary heads 2E may all perform the reproducing operation in the idle running section, except during the period in which the erasing operation is performed.

This invention can also be applied when one rotary head is used for recording. Further, the present invention can be applied to the case where an audio PCM signal is recorded by a rotary head.

"Effects of the Invention" According to this invention, when there are two running speeds of a magnetic tape and recording is performed at the second speed slower than the first speed, the rotating head for erasing erases data every rotation. It is possible to perform operations and playback operations.

Therefore, it is possible to detect the clog of the rotary head based on the level of the reproduction signal, and it is possible to know that the recording is not being performed correctly.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the arrangement of the rotary head in an embodiment of the present invention; FIG. 1 fA2 and FIG. FIGS. 4 and 5 are block diagrams of one embodiment of the present invention and time charts used to explain its operation. 1...Rotating drum, 2A, 2B...B1 rotating head for recording, 2F...Rotating head for erasing, 3...Magnetic tape, 10 . . . Erase oscillation circuit, 14 . . . Detection circuit. Agent Masato Sugiura

Claims (1)

[Claims] at least one recording rotary head; and an area of the recording medium in which a track is formed by the recording rotary head; an erasing rotary head for erasing; a means for causing the recording medium to travel at either a first speed or a second speed slower than the first speed;
A rotary head type recording device comprising a switching circuit for causing the erasing rotary head to repeat an erasing operation and a reproducing operation every rotation during a recording operation at a speed of .