JPS63234483A - Magnetic reproducing device - Google Patents

Abstract

PURPOSE:To correctly and rapidly search by comparing a current frame with a prescribed frame at the time of searching for controlling so as to reproduce the video signal of the prescribed frame and switching the travel mode of a magnetic tape according to the difference. CONSTITUTION:When a search mode is selected according to the operation of a controller 300, a frame code FC is supplied to a CPU 51 from a decoder 63 and written in the buffer part of a RAM 53 as the current frame. Then, at the time of reproducing the video signal of the prescribed frame, the current frame is compared with the prescribed frame and the travel mode of the magnetic tape T is switched according to the difference. For instance, when the difference is large, a high speed tape travel mode is obtained and when the difference is small, a low speed tape travel mode is obtained so as to effectively obtain the frame code. Thereby, the search can be correctly and rapidly carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic reproducing device for reproducing a video signal from a magnetic tape in which a frame code is superimposed on the video signal and recorded on an inclined track.

[Summary of the invention]

The present invention provides a magnetic reproducing apparatus that reproduces video signals from a magnetic tape in which a frame code is superimposed on a video signal and is recorded on an inclined track. and a predetermined frame, and the running mode of the magnetic tape is switched according to the difference.
This allows searches to be performed accurately and quickly.

(Prior Art) Conventionally, in a video tape recorder (VTR) that records and reproduces a video signal on an inclined track of a magnetic tape, a video tape recorder (VTR) that records and reproduces a video signal by superimposing a frame code has been proposed.Such a VTR It is conceivable to provide a search function for controlling the reproduction of a predetermined frame of video signal based on the frame code obtained from the reproduced video signal.

[Problem that the invention seeks to solve]

In order to provide such a search function, if the specified frame to be searched is relatively far from the current frame and the search is performed in low-speed playback mode to accurately obtain the frame code, the search time will be large. There are such inconveniences.

In view of this point, the present invention is designed to allow searches to be performed accurately and quickly.

[Means for solving problems]

The present invention is directed to a magnetic tape T in which a frame code FC is superimposed on a video signal and recorded on inclined tracks TA and TB.
This is a magnetic reproducing device that reproduces a video signal from a predetermined frame, and at the time of a search that controls the reproduction of a predetermined frame of the video signal, the current frame and the predetermined frame are compared, and the running mode of the magnetic tape T is changed according to the difference. It can be switched.

The current frame is the frame indicated by the frame code FC obtained from the reproduced video signal, and during the period when the frame code FC is not obtained, the control pulse C'I' L obtained in connection with the running of the magnetic tape T is used. is counted and predicted.

For example, if the predetermined frame to be searched is relatively far from the current frame, fast forward or rewind mode,
The magnetic tape running mode is sequentially switched and searched in the order of high-speed playback mode and low-speed playback mode.

[Effect]

In the above configuration, the running mode of the magnetic tape is switched depending on the difference between the current frame and a predetermined frame. For example, when the difference is large, a high-speed tape running mode is selected, and when the difference is small, the frame code is reliably read. Since the tape running mode is set at a low speed so that it is possible to obtain the desired speed, the search can be performed accurately and quickly.

〔Example〕

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

In the figure, (100) is a rotating two-head helical scan type video tape recorder (VTR). VT
R(100), HA and HB are 180 each other
It is a rotating magnetic head arranged with an angular spacing of 2°.
It rotates once in a field (1 frame) period. Further, T is a magnetic tape, which is wound diagonally around the circumferential surface of the tape guide drum (1) by more than 180° during recording and reproduction, and runs at a predetermined speed.

As shown in FIG. 2, the magnetic tape T has inclined recording tracks TA and TB on which video signals are recorded. The video signal includes, for example, the 17th field of the first field and the second field that constitute each frame as shown in FIG.
A frame code FC is superimposed on the 18th horizontal period. This frame code FC is, for example, a 24-bit B code in which each digit of a 6-digit decimal number is expressed as a 4-bit binary number.
CD code, its high level 1'' and low level''
0'' is the white level of the luminance signal (for example, 80I
RE) and the pedestal level. In this case, the video signal is a carrier color signal C that has been low-pass converted.
It is recorded in the form of a composite signal of L and an FM-modulated luminance signal YFM.

Figure 4 shows an example of the frequency spectrum.
The luminance signal Y is FM modulated so that the leading edge of the synchronization signal is 3.8 MIIz and the white beak is 5.4 MHz. In addition, the color subcarrier frequency is 3.58MHz (NTS
The carrier color signal C of the C method) has a color subcarrier frequency of 688.
The frequency is converted to kHz.

In addition, as shown in FIG. 2, in the longitudinal direction of the magnetic tape T, there are two recording tracks TA and TB, that is, one recording track per frame.
Control track TC in which control pulses CTL are recorded, and audio track T4. in which left and right audio signals are recorded. ．． TR is formed.

Figure 5 shows the mechanical parts of the VTR (100), where 11) is the tape guide drum mentioned above, (2) is a capstan, (3) is a movable pinch roller, and (4) is for erasing audio signals. 1a air head, (5) control pulse CT
These are an L magnetic head for recording and reproducing and a magnetic head for recording and reproducing audio signals. (6) to (13) are tape guides,
Of these, (71, (8), (11), (12)
) and (13) are moving tape guides, and the others are fixed tape guides. Also, (15) is a tape cassette, (
16) is its supply reel, and (17) is its take-up reel.

Further, (20) is a magnetic head for reproducing the control pulse CTL, which is also used as an erasing magnetic head for erasing the entire width of the magnetic tape T.

In such a mechanism, during recording and reproduction, the magnetic tape T is pulled out from the tape cassette (15), and the tape winding means (21) consisting of a moving tape guide etc.
(16) → (6) → (20) → (7) → (1) → (4)
→(5)→(2)→(13)→(12)→(11)→(
The magnetic tape is wound around the tape guide drum (1) and runs through a first magnetic tape running path of 8)→(9)→(10)→(17). In this case, during reproduction, the control pulse cTL is obtained by being reproduced from the magnetic head (5).

Also, during fast forwarding and rewinding, the tape winding means (2
1), the winding angle of the magnetic tape T with respect to the tape guide drum (1) is greatly reduced or it is not wound at all, and the magnetic tape T is wound around the tape cassette (15).
The magnetic tape 'r is (16) → (6) → (20)
→(7)→(8)→(9)→(1o)→Second of (17)
The magnetic tape is configured to run along the magnetic tape running path. In this case, the control pulse CTL is obtained by being reproduced from the magnetic head (20).

Returning to FIG. 1, when the heads HA and HB sequentially scan the recording tracks on the magnetic tape T during reproduction, the reproduction signals obtained from the heads HA and HB are transmitted to the reproduction amplifier (
The switch circuit (31A) and (31B)
2) is supplied to the A side and B side fixed terminals. This switch circuit (32) is supplied with an RF switching pulse PRF from a terminal (33), and is switched to the A side and the B side during one field period when the heads HA and HB scan the magnetic tape T, respectively.

The output signal of the switch circuit (32) is supplied to a bi-pulse filter (34) and an FM luminance signal Y- is extracted.
This FM brightness signal YFM is passed through a limiter (35) to
The luminance signal Y is demodulated by the M demodulator 36). This luminance signal Y is supplied to a synthesizer (38) via a low-pass filter (37).

Further, the output signal of the switch circuit (32) is supplied to a low-pass filter (39) to extract a low-pass converted color signal CL, and this low-pass converted color signal CL is sent to an ACC circuit (40).
The signal is supplied to the frequency conversion circuit (41) via the carrier color signal C and the color subcarrier frequency is 3.58M)Iz. This carrier color signal C is supplied to a synthesizer (38) via a bandpass filter (42).

A video signal SV in which the luminance signal Y and the carrier color signal C are combined is obtained from the synthesizer (38), and this video signal SV is led out to the output terminal (44) via the output amplifier (43). .

In the VTR (100), a video signal recording system and an audio signal recording/reproducing system are omitted from illustration for the purpose of simplifying the drawing.

Further, (46) is a microcomputer (hereinafter referred to as microcomputer) provided in the VTR (100), and the VT
It controls the operation of R(100).

Also, (200) is the microcomputer (4) inside the VTR (100).
This is a microcomputer for supplying command signals to 6).

In the microcomputer (200), (51) is the CPU, (5
2) is a ROM, and (53) is a RAM.

The controller (300) operated by the user is connected to the CPU via an input/output interface (54).

Further, the CPU (51) generates a command signal CMD according to the user's operation of the controller (300), and this command signal CMD is transmitted to the VTR (100) (7) microcontroller (
As described above, the operation of the VTR (100) is controlled by the microcomputer (46) based on this command signal Cl91D.

Furthermore, the luminance signal Y from the low-pass filter (37) is supplied to the comparator (62) via the amplifier (61). This comparator (62) has a white level (e.g. 801R).
A reference voltage VRIEF corresponding to an intermediate level between E) and the Bedeskle level is supplied, and the luminance signal Y is compared with this reference voltage VREF. When the brightness signal Y is higher or lower in level than the reference voltage VREF, the comparator (62) outputs signals of high level "1" and low level "O", respectively.

Therefore, when the frame code FC is added to the luminance signal Y, the high level "1" and the low level "0" are displayed in the 17th and 18th horizontal periods of the first and second fields constituting each frame. A frame code FC consisting of the following is output.

The output signal of this comparator (62) is supplied to a decoder (63), in which the frame code FC
is extracted, and the 24-bit BCD code is
For example, it is converted into a binary code. The frame code FC from this decoder (63) is input to the input/output interface (5).
6) to the CPU (51).

Although not mentioned above, the output signals of the magnetic heads (5) and (20) of the VTR < 100 are transmitted to the reproduction amplifier (
A of the switch circuit (49) via (47) and (48)
Supplied to the fixed terminals on the side and B side. This switch circuit (49) is supplied with a switching control signal from a microcomputer (46), and is connected to the A side during playback, and is connected to the B side during fast forwarding and rewinding. During reproduction, as described above, the magnetic tape T follows the first magnetic tape running path (the fifth
Since the control pulse CTL is obtained by being reproduced from the magnetic head (5), the control pulse CTL is output from the switch circuit (49). On the other hand, during fast forwarding and rewinding, as described above, the magnetic tape T is set to the second magnetic tape running path (shown by the broken line in FIG. 5), and the control pulse CTL is reproduced and obtained from the magnetic head (20). A control pulse CTL is output from the switch circuit (49). Switch circuit (49) empty control pulse CT
L is supplied as a clock to the counter (57) of the microcomputer (200).

Further, when the search mode is selected by the user's operation of the controller (300), when the frame code FC is supplied to the CPU (51) from the decoder (63), the CPU (51) is indicated by this frame code FC. The frame is written into the buffer section of the RAM (53) as the current frame. Then, each time the frame code FC is supplied to the CPU (51), the RAM (53)
The contents of the buffer section are updated sequentially. In addition, in this search mode, the count value of the counter (57) is supplied to the CPU (51) at predetermined intervals, and a frame is calculated from the change in the value and the frame written in the buffer section of the RAM (53). It is predicted that

Then, when the frame code FC is not supplied, the CPU (51) writes this predicted frame into the buffer section of the RAM (53) as the current frame.

For example, the frame code FC is not supplied at all in the fast-forward mode or the rewind mode, and in the high-speed playback mode, since the heads HA and HB diagonally cross the recording tracks TA and TB, the frame code FC is supplied only every predetermined frame.

In addition, in this search mode, the microcontroller (200)
The CPU (51) operates according to the flowchart shown in FIG.

That is, the IFcI of the difference frame (hereinafter referred to as the difference frame) between the current frame written in the buffer section in step (2) and the predetermined frame specified by the user is 30.
It is determined whether or not there are 00 frames or more. If there are more than 3000 frames, a command signal CMD is generated to put the VTR (100) into fast forward or rewind mode depending on the direction of the predetermined frame in step ) is supplied to the microcomputer (46), and the process returns to step (2).

If IFcI is not 3000 frames or more in step (2), it is determined in step (2) whether the mode is fast forward mode or rewind mode. When in fast forward mode or rewind mode, in step ■, the difference frame IF
It is determined whether cI is 500 frames or more. 50
When the number is 0 frames or more, step ■ will turn the VTR (
The microcomputer (46) of the VTR (100) generates a command signal CMD to set the VTR (100) to 8x playback mode in the direction of a predetermined frame, and sends the command signal CMD to the microcomputer (46) of the VTR (100) via the input/output interface (55).
and return to step ■.

If it is not the fast forward mode or the rewind mode in step (2), and if it is not 500 frames or more in step (2), it is determined in step (2) whether or not the difference frame IFcI is 60 or more frames. When the number of frames is 60 or more, a command signal CMD is generated to set the VTR (100) to 8x playback mode in the direction of the predetermined frame in step (2), and the command signal CMD is sent to the VTR (100) via the input/output interface (55).
100) to the microcomputer (46), and return to step (2).

If the number of frames is not 60 or more in step (2), it is determined in step (2) whether the difference frame IFcI is 10 or more frames. If it is 10 frames or more, in step (2), a command signal CMD is generated to set the VTR (100) to 1x playback mode in the direction of the predetermined frame, and the command signal CMD is sent to the microcomputer (4B) of the VTR (100) via the input/output interface (55). and return to step ■.

If it is not 10 frames or more in step (2), it is determined in step (2) whether the difference frame IFCI is greater than the θ frame. If it is larger than O frame, in step [phase], a command signal CMD is generated to put the VTR (100) into the 1/10 speed playback mode in the direction of the predetermined frame, and the input/output interface 7! , (55)
Supplied to the microcomputer (46) of R (100), step ■
Return to

If it is not larger than O frame in step ■, that is, it is 0 frame, then in step ■, a command signal CMD is generated to set the VTR (100) to Bose mode (still playback mode), and input/output interface 7 Nice (55) is generated. The search is then completed by supplying the data to the VTR (100) (D-Z-D-IN (46)).

This example is configured as described above, and based on the user's operation of the controller (300), the microcomputer (200)
The command signal CMD is sent from the PU (51) to the VTR (100
), and the VTR (100) is controlled to the operating state specified by the user.

When the user instructs a search to reproduce a video signal of a predetermined frame, the VTR (10
0) mode is sequentially switched and search is performed.
For example, when the first difference frame IFcI is 3000 frames or more, the VTR (100) modes are set in the following order: fast forward mode or rewind mode - 8x playback mode - 1x playback mode - 1/10x playback mode - Bose mode The search is performed by switching sequentially.

Therefore, according to this example, at the time of search, when the difference frame IFC1 between the current frame and the predetermined frame is large, the high-speed running mode is set, and when the difference frame IFcI is small, the frame code FC can be reliably obtained. Since it is a low-speed driving mode that allows
Even if the difference frame IFcI is large, the search can be performed accurately and quickly. Moreover, according to this example, even when the frame code FC cannot be obtained, such as in fast forward mode or rewind mode, the control pulse CTL is supplied to the counter (57) of the microcomputer (200), and this counter (57) Since the current frame is predicted by the change in the count value and written into the buffer section of the RAM (53), the search can be performed more accurately and quickly.

Note that the mode switching point at the time of search in the above-described embodiment and the double-speed playback mode are merely examples, and the present invention is not limited thereto. In short, the smaller the frame IFcI of the difference between the current frame and the predetermined frame is, the slower the running mode should be.In addition, in the above embodiment, the VTR (100) is in Bose mode at the end of the search. However, it may be set to normal playback mode.

〔Effect of the invention〕

According to the present invention described above, when the frame difference between the current frame and the designated predetermined frame is large during the search, the high-speed running mode is selected, and when it is small, the low-speed running mode is selected so that the frame code can be reliably obtained. mode, the search can be performed accurately and quickly even if the difference in frames is large. Moreover, according to the present invention, even when a frame code cannot be obtained, the control pulses obtained in connection with the running of the magnetic tape are counted and the current frame is predicted, so that the search can be performed more accurately and quickly. .

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing one embodiment of the present invention, Figures 2 to 6
The figure is a diagram for explaining the same. (100) is a VTR, (200) is a microcomputer, (300 is a
) is the controller.

Claims (1)

[Claims] In a magnetic reproducing device that reproduces a video signal from a magnetic tape in which a frame code is superimposed on the video signal and is recorded on an inclined track, during a search to control to reproduce the video signal of a predetermined frame. , the current frame and the predetermined frame are compared, the running mode of the magnetic tape is switched according to the difference, the current frame is set as a frame indicated by the frame code obtained from the reproduced video signal, and the frame code is A magnetic reproducing apparatus characterized in that a period in which the magnetic tape cannot be obtained is predicted by counting control pulses obtained in connection with the running of the magnetic tape.