JPS6252746A - Method for preventing miserasing of rotary head type tape recorder - Google Patents

Abstract

PURPOSE:To prevent a miserasure by writing a miserasing preventing information into the miserasing prevention area of each track so as to inhibit the revision of the recording at re-recording. CONSTITUTION:The miserasing preventing area A recorded with the miserasing preventing information at the start edge is formed to tracks taua, taub of a tape 12, and a main area B on which a PCM signal and a pilot signal are recorded to the remaining areas other than the miserasing prevention area A is formed. The digital signal of the miserasing prevention information recorded in the miserasing prevention area A, that is, a digital signal outputted from a forming circuit 4 consists of a synchronizing data SYa, the miserasing prevention data CD and a CRC code CRa for error detection. The area preventing the miserasing of the tape 12 and the area not preventing it are discriminated depending on the presence of the recording of the miserasing prevention information of the area A so as t prevent the miserasing.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a rotary head type tape recorder that prevents erroneous erasure of rotary head type tape recorders such as a rotary head type digital audio tape recorder and an 8 mm video tape recorder. Concerning a method for preventing accidental erasure.

[Conventional technology]

Conventionally, in fixed-head audio tape recorders, video tape recorders, etc., the magnetic tape for recording and playback is formed from a cassette tape. As described in Japanese Patent No. 58-187035, a cassette tape case is provided with a protrusion or a protrusion for preventing accidental erasure.

During recording, the presence or absence of the protrusion or claw is detected by a mechanical detector such as a limit switch, and if the protrusion or claw is broken and missing, updating of the record is prohibited to prevent accidental erasure. .

On the other hand, rotary head type tape recorders such as rotary head type digital audio recorder (hereinafter referred to as R-DAT) and 8 mm video tape recorder C (hereinafter referred to as 8 mm VTR) use a magnetic field formed by helical scanning of the rotary head. Time-compressed audio information and the like are recorded on each track diagonal to the running direction of the tape, and in this case too, the magnetic tape is formed by a cassette tape.

[Problem that the invention seeks to solve]

In the case of rotary head type tape recorders such as R-DAT and 8mm VTR, the above-mentioned protrusion or hole is provided on the cassette tape case, and erroneous erasure is prevented based on the detection of the presence or absence of the protrusion or hole. It is possible that

However, in the case of a method that prevents erroneous erasure based on the detection of the presence or absence of protrusions or ridges, even if the ridges or ridges are broken off to prevent erroneous erasure, for example, the protrusions or nails may be removed. If a sticker etc. adheres to the position,
There is a problem that erroneous detection occurs, records are updated, and erroneous erasure cannot be reliably prevented.

Furthermore, if mistaken erasing is prevented based on the detection of the presence or absence of protrusions or claws, updating of all records on a cassette tape whose protrusions or claws have been broken off is prohibited; Even when a record is made to prevent accidental erasure only on the cassette tape, it is not possible to update all the records on the tape, resulting in the problem that the cassette tape cannot be used effectively.

The technical problem of this invention is to ensure that only a desired portion of a magnetic tape such as a cassette tape is prevented from being accidentally erased in a rotary head type tape recorder such as an R-DAT or an 8mm VTR. do.

[Means for solving problems]

This invention forms an erroneous erasure prevention area in which erroneous erasure prevention information is recorded at the starting end of each track of a magnetic tape that is helically scanned by a rotating head, and when re-recording, the erroneous erasure prevention area of each track is traced. During the period, the head is controlled to play, and it is determined from the reproduction signal of the accidental erasure prevention area whether or not the accidental erasure prevention information is recorded, and if the accidental erasure prevention information is not recorded, the accidental erasure of each track is performed. The rotary head type is characterized in that if information on remaining areas other than the prevention area is recorded, the head is controlled to reproduce during the tracing period of the remaining areas to prohibit updating of records in the remaining areas. This is a method to prevent accidental erasure of a tape recorder.

[Effect]

Therefore, by writing and recording accidental erasure prevention information in the accidental erasure prevention area of each track where recording is made to prevent accidental erasure on the magnetic tape, when re-recording, each track on which accidental erasure prevention information is recorded Updating of the track record is prohibited to prevent accidental erasure, and at this time, the recording of the remaining tracks on which no accidental erasure prevention information is recorded, that is, the portion of the magnetic tape that does not need to be prevented from accidental erasure, is prohibited from updating. It is lent.

〔Example〕

Next, the present invention will be described in detail with reference to drawings showing one embodiment thereof.

Figure 1 shows the circuit block when applied to R-DAT. In the figure, (It) and (Ir) are the left and right channel input terminals of the stereo audio signal to be recorded, and (1) is the input terminal for both inputs. This is a PCM processing circuit into which the left and right channel audio signals of (It) and (Ir) are input, and performs digital conversion and time axis compression of both input terminals (Iz) and (Ir) to create a stereo audio signal. form a PCM signal,
The PCM signal is output to one contact (c) of the recording signal changeover switch (2).

(3) is a recording control switch for accidental erasure prevention information whose one end is grounded, and (4) is an accidental erasure prevention information formation circuit connected to the other end of switch (3). When recording of the erasure prevention information is instructed, a digital signal of the erroneous erasure prevention information is formed and outputted from the other contact υ)VC of the switch (2).

(5) is a pilot signal generation circuit that forms and outputs a pilot signal for the capstan servo; (6) is an adder with one input terminal connected to the switching piece of switch (2); A terminal is connected to a generating circuit (5). (7) is an amplifier whose input terminal is connected to the output terminal of the adder (6).

(8) is a recording/reproduction changeover switch whose recording contact (r) is connected to the output terminal of the amplifier (7), (9) is a head changeover switch whose changeover piece is connected to the changeover piece of switch (9), and OQ.
.

αυ is a pair of rotating heads for recording and reproducing the magnetic tape (b), which are connected to the two contacts (hx) and (by) of the switch (9), respectively, and have mutually different azimuth angles. The head cylinder α3 is provided at a position opposite to the head cylinder α3, and rotates as the cylinder α3 rotates based on the rotation of the cylinder motor α4.

Q9 is a reproduction signal changeover switch, and a switching piece is connected to the reproduction contact (p) of the switch (8). aQ is a PCM signal reproducing circuit with one contact (r) of the switch α connected to VC, which performs time axis expansion and analog conversion of the input reproduced PCM signal, and outputs the left and right channel output terminals (oz), ror ), played left.

Outputs the right channel audio signal.

αη is an erroneous erasure prevention information reproducing circuit connected to the other contact [δ] of the switch aFJ, and when a reproduction digital signal of erroneous erasure prevention information is input, the erroneous erasure prevention of logic 1 (hereinafter referred to as 1) is detected. An information detection signal sa is output.

A servo circuit 08 is connected to the regeneration contact (p) of the switch (8), and outputs a servo control signal for the capstan motor (not shown) based on the regenerated pilot signal.

09 is a timing signal generation circuit to which the detected temperature @Sa is input; together with the detection signal Sa, the head rotation detection signal sb from the rotation detection head is input;
), (s), (9) Q As shown in the figure, a pair of guide poles an installed near cylinder a3
, the tape (2) runs along g, and at this time, as shown by the broken line VC in the same figure, the tape a reaches the cylinder (to) 90°.
It travels while being wrapped around a predetermined angle θ. Note that the arrow in FIG. 2 indicates the running direction of the tape (2).

Also, the head GO, θυ rotates at a constant speed according to the rotation of the cylinder α1, and at this time, due to the helical scan, the tracing direction of the head GO, aυ shown by the arrow Since the heads QG and αυ trace the tape α diagonally in the running direction, the heads QG and αυ alternately trace the tape α diagonally in the running direction.
) are formed alternately with tracks (τa) and (τb) having different azimuth angles, and during reproduction, the tracks (τa) and (τb) on the tape are sequentially reproduced and traced.

And each track (τa), (τb) of tape (6)
In this case, an accidental erasure prevention area (A) is formed in which accidental erasure prevention information is recorded at the starting end, and an accidental erasure prevention area (A) is formed at the starting end.
A main area (B) is formed in which the remaining portions other than A), such as VCPCM signals and pilot signals, are recorded.

In addition, the digital signal of the accidental erasure prevention information recorded in the accidental erasure prevention area (A) K, that is, the digital signal output from the formation circuit (4), is synchronized with the synchronization data SYa and the accidental erasure prevention data as shown in Figure @4. CD, CR for error production
It is formed from the C code CRaVc.

Furthermore, a PCM signal is recorded in the king area (B).

That is, the PCM signal of the stereo audio signal output from the processing circuit (1) is synchronized with the synchronization data SY as shown in FIG.
After b, 3 blocks of left channel audio data Lt
, L2, L3 and three blocks of right channel audio data R1, R2, Ra are arranged alternately, and after the last right channel audio data R3, P for error correction is arranged.
Q code Ep, Eq and CRC code C for error detection
, Rb.

On the other hand, head QO, (the rotation of lυ is detected by the head plane, and from the head plane to the generation circuit QIK, the detection signal sb which changes alternately to the cylinder α3, that is, one track Cτa by the head QG), from the start of tracing to the cylinder α
3 rotates half a turn and the other track (τb
) until the tracing of the next track (τa) starts [11 m], and Okc is detected from the start of the tracing of the head aυ until the cylinder (to) turns half a revolution and the tracing of the next track (τa) by the head QQ starts. A signal sb is output.

The rising and falling edges of the detection signal sb correspond to each track (τ
Since it becomes the starting point of the trace of a) and (τb), the generation circuit α flaw forms a switching signal se that alternately changes to 1 and 0 in synchronization with the detection signal sb, and outputs it to the switch (9). death,
While the head αq traces the tape α4, the switch (
9) is switched to the contact (hx), and while the head αυ traces the tape 0, the switch (9) is switched to the contact (hy).

Further, tracing of each track (τa) and (τb) is started from the rise and fall of the detection signal sb, respectively, and at this time, the heads αQ and αυ trace each track (τa).

The accidental erasure prevention area (A) of Cτb) is traced for a certain period of time ta from the start of tracing, and the accidental erasure prevention area (5)
Since the main area (B) forming the remaining area is traced next, the generation circuit 01 is traced based on the detection signal sb.
is a certain period ta from the start of tracing of each track (τa) and (τb), that is, the trace period Vcl of the accidental erasure prevention area (A), and the accidental erasure prevention area (
During the remaining period tb other than the tracing period of A), OK detection signals sc and sf are formed and output to the switch (2) (each in one frame, and the erroneous erasure prevention area (A) f7) is used to start tracing. Switch (2), connect Q$ to contact (β, (
δ), and switch (2) and Qυ are switched to contacts (α) and (γ) during the trace period of the king area ('B).

Furthermore, the switching signal sd outputted from the generating circuit 09 to the switch (8) is OK and held when the first recording of the tape @ is set by operating a mode changeover switch (not shown), for example. 1 based on the presence or absence of the detection signal @sa of the reproducing circuit αη when re-recording is set.
．． It changes to 0 and is held at 1 when tape (2) is set to be played.

To explain the operation during the first recording of tape 4, the switching signal sd is held at 0 and the switch (8) is turned into the contact (r).
), the head α0, Ql) is controlled to always record at V.

Also, the left and right channel audio signals to be recorded are connected to the input terminals (
Iz) and (Ir) are input to the processing circuit (1), and the processing N
Through the processing of the circuit (11), PCM signals for one track of the format shown in FIG. Contact point (2) (
(b)) PCM signals for 11 racks each are output.

On the other hand, during recording to prevent erroneous erasure, the switch (3) is operated and set to on, and when the switch (3) is turned on, the formation circuit (4) operates and traces each track (τa) and (τb). During this period, a digital signal of the accidental erasure prevention information in the format shown in FIG. 4 is formed and output from the forming circuit (4) to the contact φ)VC of the switch (2).

In addition, there is a switch (3) between records that do not prevent accidental erasure.
is held off, the processing circuit (4) stops operating, and the digital signal of the accidental erasure prevention information is not output.

Then, based on the switching signal 5CiC, the accidental erasure prevention area (
Switch (2) is switched to contact (a) during the trace period of A), and switch (2) is switched to contact (a) during the trace period of main area (B).
2) is switched to the contact φ), during recording to prevent erroneous erasure, the switch (
2), adder (6), amplifier (7), switch (s)
? (9) The digital signal of the accidental erasure prevention information alternately outputted from the head QOp 01) vc is recorded,
In the main area (B) of each track (τa), (τb), there is a switch (2) from the processing circuit (υ).

Adder (6), amplifier (7), switch (s) t (
9) head α1.01) VC alternately outputted PCM signals are recorded.

Also, between recordings that do not prevent erroneous erasure, there is a forming circuit (4
), the digital signal of the accidental erasure prevention information is not recorded in the accidental erasure prevention area (A) of each track (τa) and (τb).
For each track (τa) and (τb), only PCM [marking, Roku] is performed to the main area (13).

In other words, when recording tape a for the first time, switch (3)
) on each track (τa), (τb) of the recorded portion to prevent accidental erasure [, recording of digital signal of accidental erasure prevention information in the accidental erasure prevention area (A) and king area CB) The recording of the PCM signal of the stereo audio signal is performed, and each track (τa), (τ
b) Only the recording of the PCM signal of the stereo true signal in the main area (B) is recorded.

In addition, the main area (B) of each track (ra), (rb)
During the trace period, the generator (5) to the adder (6)
Since the pilot word for the tracking plate is output in the main area (B) of each track (ra) and (rb)
IC records the pilot signal of the generation circuit (5) together with the PCM signal of the stereo audio signal.

Next, the operation for re-recording on the tape will be explained with reference to FIGS. 6 and 7.

Now, suppose that re-recording of the part of the tape @ where the digital signal of the erroneous erasure prevention information is not recorded, that is, the part where there is no need to prevent erroneous erasure, is started, and at this time, the generation circuit QlK! 6. As shown in Figure 6 (a), a detection signal sb that changes alternately between 1 and 0 is input every half rotation of cylinder a3 in synchronization with the switching of heads αQ and Qυ, as shown in Figure 6 (b). The ejection signal 5bVc is synchronously 1
, 0, the switching signal se is generated by the generation circuit Q'J.
It is output from switch (9).

Note that the detection signal sb and the switching signal se rise.

The falling point becomes the trace starting point for each trunk (ra) and (rb).

In addition, the switching signal sd output from the generating circuit 09 is outputted from the switch (8) to each track (r
It becomes 1 during at least a certain period ta from the starting point of the traces a) and (rb), that is, during the trace period of the accidental erasure prevention area (A).

Therefore, during the trace period of the accidental erasure prevention area (A) of each track (ra) and (rb), the switch (8) is connected to the contact (
f)), and the head GO and (Jυ) are controlled to playback.

Furthermore, the switching signals sc and sf outputted from the generating circuit α9 to the switch (2) and is are switched to each track (ra) as shown in FIG. , (rb) becomes 1 for a certain period ta during which it is traced, and each track (ra)*(rb) (7) remains for the remaining period tb[0
fcfiru.

So switch (2), Q! 9 is each track (r
a), (rb) of the accidental erasure prevention area (A) during the trace period taVc contact stem), (δ), respectively, and each track (ra).

The main area (B) of (rb) is switched to the contacts (α) and (e) during the tracing period tb of the remaining area to be traced.

Therefore, the trace period taK of the accidental erasure prevention area (A) of each track (ra), (rb) is the head GO.

The playback signal of Oυ switches (9)□, (8), Q
υ to the reproduction circuit α7) [input.

Then, the playback circuit performs decoding processing on the input playback signal, determines whether the playback signal is a digital signal with information to prevent accidental erasure, and, if the part does not prevent accidental erasure, prevents accidental erasure. Area (A) [Since the digital signal of the accidental erasure prevention information is not recorded, the detection signal sa is not output from the reproduction circuit Qη to the generation circuit Ql as shown in Figure 6 (e) K, and the detection signal sa is not output from the reproduction circuit αη. The output signal to circuit 09 is held at O.

Furthermore, since the detection signal Sa is not input, the generation circuit 0
As shown in FIG. 6C, the switching signal sd is changed to O from immediately after the end of period ta until the start of the next period ta, that is, during period tb.

Therefore, the main area (B) of each track (ra) and (rb)
During the trace period of , switch (8) is at contact (r) 'i
C is switched and heads αq and αυ are controlled to record.

On the other hand, in order to update the recording on the tape (6), the input terminal (
The left and right channel audio signals of the new stereo audio signals input to Iz) and (Ir) are converted into PCM signals by the processing circuit (1), and are output to each track (ra) and (rb
) during the tracing period of the king area (B), the processing circuit (1)
The PCM signal of the above-mentioned new stereo audio signal is output from the switch (2), the adder (6), and the amplifier (7) to the contact (r) of the switch (8).

And the king area (B) of each track (ra), (rb)
Since the switch (8) is switched to the contact (r) VC during the trace period, the P output from the processing circuit (1)
The CM signal is sent to each track (ra
), (rb), and the recording in the king area (B) of each track (ra), (rb) is updated.

Note that when re-recording, each track (ra)
, (rb) during the tracing period of the accidental erasure prevention area (A), the heads αq and αυ are controlled to reproduce, so that no recording is performed in the accidental erasure prevention area (A).

Also, since the pilot signal of the generation circuit (5) is recorded in each track (τa) and (rb) together with the PCM signal, the pilot signal is updated together with the PCM signal in each track (τa) and (rb).

Therefore, the portion of the tape μs that does not prevent erroneous erasure is
By re-recording, the recording of each track (τa) and (rb) is updated, and a new PCM signal of a stereo audio signal is recorded.

Next, when re-recording of the part of the tape a2 where the digital signal of the information to prevent accidental erasure is recorded, that is, the part that prevents accidental erasure, is started, at this time as well, as shown in FIG. 7(a), the cylinder The detection signal sb, which alternately changes between 1 and O every half rotation of α3, is input to the generation circuit a, and
), a switching signal se synchronized with the detection signal sb is output from the generation circuit 01 to the switch (9).

In addition, the switching signal Sd output from the generation circuit α1 to the switch (3) is changed to each track (τ
It becomes 1 during the trace period ta of the accidental erasure prevention area (A) in a) and (rb), and the switching signal SC output from the generation circuit 09 to the switch (2) and αO as shown in FIG. , sf also becomes 1 during the trace period ta of the erroneous erasure prevention area (A) of each track (τa), (rb).

Therefore, in the trace period ta of the accidental erasure prevention area (A) of each track (τa), (rb), the head 00, a]
) is controlled for reproduction, the reproduction signals of the heads αl and C1υ are input to the reproduction circuit αη, and the digital signal of the erroneous erasure prevention information is recorded in the erroneous erasure prevention area (A) of the part that prevents erroneous erasure. , @7 As shown in Fig.
A detection signal sa of 1 is output from the generation circuit α*.

Since the detection signal Sa is input, the generation circuit a1 holds the switching signal sd at 1 during the period tb as well, and controls and holds the heads αQ and αυ in reproduction mode, as shown in FIG.

Therefore, the part that prevents accidental erasure is that during re-recording, the head (IQ, α) is always held in playback, and each track (
Since updating of the records in the king area (A) of τa) and (rb) is prohibited, the original arrangement of each track Cτa) and (rb) is not erased, and erroneous erasure is prevented.

Then, it is determined whether or not the re-recording of each track (τa) and (rb) is not possible, depending on whether or not the digital signal of the accidental erasure prevention information is recorded, and the digital signal of the accidental erasure prevention information of the tape is changed. In order to prevent accidental erasure by prohibiting playback and recording of the part where the cassette tape is recorded, that is, the part that prevents accidental erasure, the presence or absence of protrusions or claws provided on the cassette tape case prevents accidental erasure. Erroneous erasure can be prevented more reliably than a method that uses mechanical detection to prevent erroneous erasure.

In addition, as described above, each track (τa) of the portion of the tape α■ where the digital signal of the erroneous erasure prevention information is not recorded, that is, the portion where erroneous erasure is not prevented.

Since the recording on the king track (B) of (rb) is updated by re-recording, one tape (6) can be provided with a part where accidental erasure is prevented and a part where it is not. It can be used.

By the way, during normal playback of tape α4, the circuit block shown in Figure 1 operates as explained below.

First, even during normal playback, a detection signal sb that alternately changes between 1 and 0 every half rotation of the cylinder αj is input to the generation circuit Q9 as shown in Figure 8 (a), and as shown in Figure 8 (b). As shown in the figure, the switch (9N?-detection signal s
A switching signal se synchronized with b is output.

Further, the switching signal sd outputted from the generating circuit θ1 to the switch (8) is always held at 1 as shown in FIG. 8(C) based on the reproduction setting.

Furthermore, the switching signals @sc and sf output from the generation circuit αl to the switch (2) and QG are applied to the accidental erasure prevention area (A ) becomes 1 during the traced period ta and becomes 0 during the remaining period tb. Since the switching signal sd is always held at Vcl, the heads αQ and αυ are always controlled to reproduce, and the head α is.

The tape (6) is reproduced and traced by qυ.

Furthermore, based on the switching signal sf, each track αQ, 9
During the trace period of the accidental erasure prevention area (A) at
, (τb), the switch 0υ is switched to the contact (r) during the tracing period of the main area (B), so each track (τ
The reproduction signals of the accidental erasure prevention area (A) of a) and (τb) are input to the reproduction circuit group η, and the reproduction signals of the respective tracks (τa) and (τb
) is input to the reproduction circuit αQ.

The reproducing circuit 'lη selectively generates the detection signal sa% depending on the presence or absence of the digital signal of the erroneous recording prevention information. Output to.

However, the generation circuit 0* is independent of the presence or absence of the detection signal Sa.
In order to output the cl switching signal sd, for example, the tape u
As shown in FIG. 8(d), even if the output signal from the reproducing circuit 3'i) to the generating circuit 01 is held at O, due to the reproducing trace of the portion where it is not necessary to prevent erroneous recording of the head α0. Qυ continues to be controlled by regeneration.

On the other hand, the reproduction circuit αG processes the input reproduction signal of the king area (B), and outputs the audio signals of the left and right channels reproduced by the VC through the output terminals (Oz) and (Or).

In addition, the tape q played from the head oct, aυ
The effective pilot signal is input to the servo circuit (to), and the running of the tape (2) during playback is controlled by the control of the servo circuit (to).

By the way, in the accidental erasure prevention area (A) and main area (B) of each track Cτa), (τb), there is a digital signal of the accidental erasure prevention information in a format different from that shown in FIGS. 4 and 5, and a stereo audio signal. Of course, PCM signals may also be recorded.

When applied to an 8mm VTR, etc., it is sufficient to time-divisionally form an area to prevent accidental erasure and multiple areas where various signals such as PCM signals are recorded on each track of the tape. Of course, there may be other areas closer to the starting end than the area.

〔Effect of the invention〕

As described above, according to the method for preventing erroneous erasure in a rotary head type tape recorder of the present invention, the erroneous erasure prevention area (A ) K By recording the accidental erasure prevention information, when re-recording, the part of the tape □□□ that prevents accidental erasure and the area that prevents accidental erasure will be protected, regardless of whether or not the accidental erasure prevention information is recorded in the accidental erasure prevention area (A). It is possible to improve re-recording by discriminating between parts that are not erased, prohibiting re-recording of parts that prevent accidental erasure, and updating records of parts that do not prevent accidental erasure.
In this case, erroneous erasure can be prevented much more reliably than conventional mechanical methods, and the tape (6) can be used more effectively.

[Brief explanation of drawings]

The drawings show an embodiment of the method for preventing accidental erasure in a rotary head tape recorder according to the present invention, and FIG. 1 is a block diagram, and FIG.
Figure 3 is an explanatory diagram of the running of the magnetic tape, Figure 3 is a pattern diagram of the magnetic tape, Figures 4 and 5 are diagrams explaining the format of each signal recorded in the accidental erasure prevention area of the magnetic tape and the main area. Figures (a) to (e) are timing charts for explaining the operation of Figure 1 when re-recording a portion where no accidental erasure prevention information is recorded. A timing chart for explaining the operation of FIG. 1 when re-recording a recorded portion, and FIGS. 8(a) to (e) are timing charts for explaining the operation of FIG. 1 during playback.
1)...PCM conversion processing circuit, (2)...recording signal changeover switch, (3)--two-way control switch for 1i information to prevent accidental erasure, (4)...information formation circuit to prevent accidental erasure, (5)
... Pilot signal generation circuit, (6) ... Adder,
(7)...Amplifier, (8)...Recording/playback switch,
(9)...Head selection switch, QO, (1υ...
Rotating head, α snoring...Magnetic tape, α3...Head cylinder, α迀...Cylinder motor, OQ...Reproduction signal changeover switch, OQ...PCM signal reproduction circuit, αη
... Erroneous erasure prevention information reproducing circuit, (to)... Servo circuit, 09... Timing signal generation circuit, (τa), (
τb)... Track, (A)... Accidental erasure prevention area.

Claims (1)

[Claims] (1) An accidental erasure prevention area in which accidental erasure prevention information is recorded is formed at the starting end of each track of the magnetic tape that is helically scanned by a rotating head, and during re-recording, a trace period of the accidental erasure prevention area of each track is formed. At the same time, it is determined whether or not the accidental erasure prevention information is recorded from the reproduction signal of the accidental erasure prevention area, and if the accidental erasure prevention information is not recorded, the accidental erasure prevention of each track is controlled. The head is controlled to record during the trace period of the remaining area other than the area to update the record of the remaining area, and if the accidental erasure prevention information is recorded, the head is also used during the trace period of the remaining area. A method for preventing erroneous erasure in a rotary head tape recorder, characterized in that the remaining area is prohibited from being updated by controlling the playback area.