JPS6371902A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To display a third signal such as character information etc. on a reproduced screen only when necessary, preventing the occupation of a part of video signals recorded in the surface layer by the third signal such as character information etc. by recording the third signal such as character information etc. in the deepest layer of a magnetic tape, and then recording audio signals in the deep layer and recording video signals in the surface layer. CONSTITUTION:Recording is made to the deepest part of the magnetic layer of a magnetic tape as Bi-phase modulated by erasing heads ER, EL and impressed as large amplitude signals. On the other hand, audio signals FM modulated by an audio signal recording circuit 11 are applied to audio heads AR, AL of azimuthal angle + or -30 deg., effective gap 0.8mum through a mode change-over switch 5b and become deep layer record recorded to nearly the middle of the magnetic layer. Composite video signals are surface layer recorded on the deep layer record by surface layer recording heads VL, VR through an amplifier circuit 1, a recording circuit 4a and a switch 5a.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention records a third signal, which is character information such as date and time, when recording a video signal or an audio signal on a magnetic tape. The present invention relates to a magnetic recording and reproducing apparatus that displays third information such as character information on the reproduction screen when a signal is generated at +tg.

[Prior Art] FIG. 5 is a block diagram showing the structure of a conventional magnetic recording and reproducing bag. In the figure, (1) is a video signal amplification circuit which adjusts a composite video signal consisting of a luminance signal, a color signal, and a synchronization signal to level "A".

(2) is a character information generation circuit that generates characters such as time and date, (3) is a composite signal generation circuit, and each of the above circuits (1)
, (2) are combined into a video signal using the same synchronization signal as a reference. (4) is a composite signal recording circuit, which converts the composite video signal into FM signal, and generally consists of an FM modulator and an FM signal amplification circuit.

(5a) is a mote switching circuit, which is a rotary video head (VR)
), (VL) to be used in recording mode or playback mode, and is generally composed of a relay circuit or an electronic switch circuit using an IC.

(6) is a rotating tram equipped with four rotating heads, two of which are for recording and reproducing composite video signals (VR) and (VL) on magnetic tape, and the other two heads (AR) are for recording and reproducing composite video signals on magnetic tape. ) and (AL) record and reproduce audio signals to be described later on a magnetic tape. (7) is a composite signal reproducing circuit which amplifies and demodulates the FM signal on the tape. (8) is the combined brightness, color, synchronization,
This is a video signal output terminal consisting of a character signal.

(]l) is an audio signal recording circuit that adjusts the level of the audio signal and performs FM modulation. (5b) is a mode switching circuit that switches whether the rotary audio heads (AR) and (AL) are used in recording mode or playback mode. (12) is an audio signal reproducing circuit that demodulates the modulated FM audio signal. Audio signal output terminal (1) via circuit (13b)
4a) and (14b).

Next, the operation of the above configuration will be explained. The configuration described above is for the case where daily newspapers and the like at the time of recording are loaded into a magnetic recording/reproducing device known as a high-fidelity video.

First, the video signal from the video signal amplification circuit (1) and the date and time signal from the character information generation circuit (2) are mixed by the synthesis circuit (3), and the date and time signal is mixed into one video signal. I get stuck in it.

Next, the video signal with date and time is recorded in a composite signal recording circuit (4
), the signal is converted into an FM signal, amplified, and then applied to the surface recording rotary video heads (VR) and (VL) via a mode switching circuit (5a). This signal distribution is shown in FIG. 6(a).

On the other hand, the audio signal is 2 as shown in FIG. 6(b).
The FM signal is modulated into an FM signal having 1 carrier wave, and is applied to the deep recording rotary head (8R) and (AL) via the mode 1 to switching circuit (5b).

Kote rotating head (VFI), (Vl,) and (AR),
(AL) refers to the head gap (VR), (VL), gap (g) < (A
II), (AL) is related to the gap (gl). Further, in order to reduce interference between the video signal recorded on the surface layer and the audio signal recorded on the deep layer, the azimuth angles are set to be different from ±6° and ±30°. Furthermore, FIG. 8 shows the recording process from the magnetic tape surface.

[Problems to be Solved by the Invention] Conventional magnetic recording and reproducing devices are configured as described above. In order to add character information such as date and time to a video signal and record it on a magnetic tape, a recording process is required. Should the video signal be F?
Before M modulation, it was necessary to insert text information into a part of the video signal, that is, to add text information by deleting part of the video signal, and then to perform FM modulation. Therefore, during playback, characters are always inserted into a part of the audio signal, that is, a part of the playback screen, and part of the video information on the screen is hidden by the text information.
There were problems such as not being able to erase text information even when it was in the way.

This invention was made in order to solve the above-mentioned problems, and in addition to recording the video signal, text information such as [1] is recorded, and the text information is displayed on the screen only when necessary during playback. An object of the present invention is to provide a magnetic recording/reproducing device capable of displaying.

[Means for Solving the Problems] The magnetic recording and reproducing apparatus according to the present invention records video signals superficially recorded on the surface of a magnetic tape by a video head and audio signals recorded deep in a deep part of the magnetic tape by an audio head. providing a third head for erasing;
The third head is characterized in that a third signal such as character information is deeply recorded.

[Operation] In this invention, a third signal such as character information is recorded in the deepest part of the magnetic tape, an audio signal is then recorded in the deep layer, and a video signal is recorded in the surface layer on the surface of the magnetic tape. This prevents the third signal such as text information from occupying a part of the video signal recorded on the surface. Also, it is possible to display :JS3 signals such as character information on the playback screen only when necessary.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of a magnetic recording/reproducing apparatus according to an embodiment of the present invention. In the figure, the same or corresponding components as those of the conventional magnetic recording/reproducing apparatus shown in FIG. 5 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, (4a) is a video signal recording circuit; (7) is a video signal recording circuit;
A) is a video signal reproducing circuit with a built-in bandpass filter.

(100) is a character generator (100a) that generates characters such as date and time, a parallel-serial conversion circuit (100b) that converts the character signal into a serial signal, and a modulation circuit that Bi-phase modulates the serial signal. (10
This is a character information generation circuit consisting of 0c).

(+01) is an erase signal generator that applies a high frequency signal to the third head, the flying erase head (ER) and (EL), to erase all signals on the magnetic tape frame by frame. be. (102) is a changeover switch for the above-mentioned flying erase head (ER), (EL).
) is used to switch between erasing, recording, and reproducing operations, and it emits a large signal during erasing.

A relay is preferable since it handles small signals during playback.

(103) is a low-pass filter that extracts the character signal from the composite signal reproduced during playback, and (104) is a Bi-ph filter.
a demodulation circuit that demodulates the ase-modulated character signal, (io
s) is a serial-parallel conversion circuit that converts serial signals to parallel signals, (+05) is a latch circuit that temporarily stores parallel signals, (tQ7) is a character generator that rearranges character signals to reproduce them on the screen, (108) is a mix circuit that mixes a character signal for display with the reproduced video signal, and (109) is a mix circuit for mixing the reproduced video signal with a character signal for display. 'iIII period signal as a large signal, latch circuit (105), character generator (107)
This is a sequence control circuit that generates control signals for controlling. Further, (110) is a switch that turns on/off the output of the character generator (107).

Next, the operation of the above configuration will be explained based on FIGS. 1 to 4.

First, the character generator (IO) of the character information generation circuit (100)
Ua) and the output example of the parallel-to-serial converter circuit (100b), for example, as shown in No. 24 (a), record the date of July 30, 1985, 16:59 and the symbol +24 on a recording tape. do. This character information generation circuit (10
The character generator (100a) in 0) is used to create information such as date and time records, and a perpetual calendar based on a digital clock is generally adopted.

This information is applied to the parallel-to-serial conversion circuit (]00b), and as shown in Figure 752 (b), for example, the first 4 bits specify the address (a), and the next 4 bits specify the specified address (a). It converts the characters into a specified serial format and sends out the information of A, B, C, . . ., P one after another.

As a concrete example, as shown in the correspondence diagram shown in FIG. 2(a), the first 4 bits specify an address, and the next 4 bits input the data of the address (a). Note that the * mark in the figure means a logic signal that varies depending on the character.

Bi
-Perform phase modulation. Bi-Phasa
Modulation is performed by converting the signal before modulation into InOKI+7. If it is a digital signal, the recording signal after modulation is +00 K11z +
The signal has the main spectrum of Ilz at 50 KHz x 1/2 = 75. Moreover, the data transmission rate is Illμsec (100KtlZ),
Assuming 8 bits and 16 characters (A to P), IOμsec
x 8 bits x 16 - 1.28 85 during m5ec period
It is possible to send the date July 30, 2016 + 116:59 and the information No. 024.

In this way, the Bi-Phase modulated 16 character character information takes 1.28 m5ec to be sent out from the character information generation circuit (100), passes through the changeover switch (+02), and then goes to the flying erase head (ER).
(El) is added.

Here, the frequency of the character information signal mentioned in L is: f53
Shown in Figure (C). In addition, Flyinquilles Herrad (E
R) and (EL) are effective head gaps of 3.5 gm to Co pm to erase all signals on the magnetic tape.
(Video head 0.35m, audio head 0.
．． It is large, with an azimuth angle of 0° (video head ±6°, audio head ±30”).

This erase head (ER), (El,) has 8i-Ph
Since the ase modulated character signal is applied as a large amplitude signal, it is recorded to the deepest part of the magnetic layer of the magnetic tape, as shown in FIG. That is, since the effective gap is large and a low frequency signal is driven with a large vA main current, the magnetic layer is recorded until it is saturated.

On the other hand, the audio signal FM modulated by the audio signal recording circuit (11) is applied to the audio heads (AR) and (AL) with an azimuth angle of ±30° and an effective gap of 0.8 pm via a mode changeover switch (5b). . The FM-modulated audio signal at this time is an FM signal concentrated at IJ Mtlz, 1.7 MHz, as shown in FIG. 83(b). This signal becomes as shown in FIG. 4 in deep recording where the signal is recorded to approximately the middle depth of the magnetic layer.

Then, the composite video signal passes through the amplifier circuit (1), the recording circuit (4a), and the switch (5a), and is recorded on the surface layer after being deep recorded by the surface layer recording heads (VL) and (VR). This point is the same as that of the conventional device shown in FIG.

The state of this recording is shown in Figure 3 (a), (b),
At the same time as shown in (c), FIG. 4 shows the state of recording from the magnetic tape surface. In other words, l1 near 75 K11z
The i-Phase modulated character signal is recorded in the deepest layer, the FM modulated audio signal is recorded in the intermediate layer, and finally the composite video signal is recorded in the surface layer.

Furthermore, the azimuth angles of the signals recorded in each layer are different, reducing mutual crosstalk interference.

Next, the time of reproduction will be explained.

The video signal reproduced by the surface recording and reproducing heads (VR) and (VL) passes through the switch (5a) to the video signal.
The signal is demodulated by a reproducing circuit (7).

The video signal reproduced by the deep recording/reproducing head (AR), (At) is applied to the video signal reproducing circuit (12a) via the switch (5b), and the output terminal (+4a) is applied to the video signal reproducing circuit (12a) as in the conventional circuit shown in FIG. ), a reproduced audio signal is obtained in (14b).

On the other hand, the erase head (ER) is a deep recording/playback head.
), (El,), the character signal reproduced is first 20
The signal is applied to a low-pass filter (103) below 0 Hz, and demodulated by a demodulation circuit (104).

Since this demodulated character signal is a serial digital signal, it is converted into a parallel signal and is converted into a latch circuit (10
6) is applied. This latched character signal is applied to the character generator (1, (17)), resulting in a screen character signal as shown in FIG. 2(a).The sequence of these digital signals is controlled by the sequence control circuit (
+09) is controlled. This reference signal is created from the vertical and horizontal synchronizing signals of the video signal reproducing circuit (7), and generally uses a small-scale microcomputer.

The date and time character signals created by the character generator (107) are added to the mix circuit (108) via the switch (+10), so the date and time can be input by the user during playback. Only when this is done, characters like those shown in Figure i2 (a) can be reproduced on part or the entire screen.

Finally, erasing will be explained.

During erasing, approximately 81Il is generated from the erasing signal generator (101).
The high frequency signal of l'Iz is amplified to a large amplitude, and the switch (
102), the full erase head (ER), (E
L), and all the magnetic flux from the deepest part of the magnetic tape to the surface layer is erased by a high frequency signal. That is, it is possible to erase all the signals of the magnetic material parts for each field, and the original connection operation can be performed cleanly.

In the above embodiment, the character information to be recorded in the blind is limited to only numbers as shown in FIG. be.

In addition, the character information in Figure 2 (a) has been explained in terms of the method of recording it between - fields, or there is no need to actually record it for each field, for example, one piece of information can be recorded using dozens of fields. Since this is sufficient, it is possible to record complex characters, and the carrier frequency of the character signal can also be lowered to an extremely low level.

Pulse code modulation is not limited to Bi phase modulation.

In addition, Flying Erase Head (ER), (E
The cost can also be reduced by making the track width twice that of the video track by using only one track L). At this time, a frame recording/reproducing method is used in which character information is recorded or reproduced once in two fields.

[Effects of the Invention] As described above, according to the present invention, the third signal such as character information such as date and time is superimposed with the audio signal and recorded in the deep layer, and the video signal is recorded in the surface layer. , the third signal such as the above character information is
There is no possibility that a part of the video signal will be occupied and cause any kind of interference to the reproduced video signal or the reproduced audio signal.

Furthermore, the third signal such as recorded character information can be called up arbitrarily only when needed, and can be simply deleted when it is no longer needed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a magnetic recording/reproducing device according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing an example of character information, and FIG. 3 is a frequency characteristic diagram of each signal according to the embodiment of FIG. 1. , FIG. 4 is a block diagram showing the recording format of the magnetic tape thickness according to the embodiment of FIG. 1, FIG. 5 is a block diagram showing a conventional magnetic recording/reproducing device, and FIG. 6 is a frequency characteristic diagram of each signal. FIG. 7 is a block diagram showing a conventional recording format in the tape thickness direction, and FIG. 8 is a block diagram showing a conventional tape surface recording format. (6)...Rotating tram, (VR), (Vshi)...
- Video head, (AR), (AL)... Audio head, (El+), (F, L)... Erase head (third head). In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A video head that records and plays video signals on a rotating drum, an audio head that records and plays audio signals,
A third head erases the video signal and audio signal recorded by each of the heads, and the third head records a third signal other than the video signal and audio signal in addition to the erase function. A magnetic recording/reproducing device characterized in that it is configured as follows.