JP2876888B2 - 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 and, more particularly, to a method for pulling in a capstan phase at the start of tape running.

[0002]

2. Description of the Related Art A servo mechanism of a conventional magnetic recording / reproducing apparatus (hereinafter referred to as VTR) will be described. FIG. 9 shows a conventional V
FIG. 3 is a block diagram illustrating a configuration of a servo mechanism when reproducing a TR. A cylinder motor 902 for driving the rotary head 903, a first frequency generator 905 for detecting the rotation speed of the cylinder motor 902, and a cylinder motor 902
A phase detector 904 for detecting the rotation phase of the first frequency generator, a first frequency discriminator 907 for detecting an error of an output signal of the first frequency generator 905 with respect to a reference cycle, and a reference signal generator 91.
1, a head switching signal 927 (HSW signal) obtained from the output signal 926 of the phase detector 904 and the output signal 928 of the first frequency generator 905, and the reference signal generator 91.
1 and a first phase comparator 910 for detecting a phase error with the reproduction reference signal obtained from the first phase comparator 910.
A first adder 909 which mixes the phase error output 929 of the first frequency discriminator with the speed error output 930 of the first frequency discriminator 907;
A first driving circuit 906 for driving the first amplifier 908 and the cylinder motor 902; a capstan motor 925 for running the magnetic tape at a constant speed; and a second frequency generator for detecting the rotation speed of the capstan motor 925. 924
And a second frequency discriminator 923 for detecting an error of the output signal 931 of the second frequency generator 924 with respect to the reference cycle.
And a circuit 913 for generating a tracking error signal 934 used for tracking control of the capstan from a pilot signal recorded on the magnetic tape, and comparing the tracking error signal with 1/2 Vcc obtained from the terminal 918 to compare the rotational phase of the capstan. Phase detector 9 for detecting
19 and the phase error output 9 of the second phase comparator 919
32 and the speed error output 933 of the second frequency discriminator 923
Adder 920 for mixing with the second amplifier 92
1 and a second drive circuit 922 for driving the capstan motor 925.

Next, an outline of tracking control using pilot signals of a plurality of frequencies will be described. Hereinafter, a description will be given assuming that the pilot signal is composed of two types of frequencies f1 and f2. The structure of the rotary head is shown in FIG.
As shown in the figure, the R1 and L1 and R2 and L2 heads are combined, and two tracks of information are recorded on the tape while each combination head performs one scan.

FIG. 11 shows a magnetic trajectory of a two-frequency pilot signal. f1 and f2 indicate pilot signals for tracking control. In FIG. 11, f0 is no signal. Each pilot signal is recorded with a video signal superimposed thereon, and f0->f1->f0->f2-> f0 for each scan of the rotary head.
-> F1 and sequentially switched and recorded. No pilot signal is recorded in the heads L1 and L2. The signal f1 of each pilot is 120
kHz and f2 are set to 180 kHz. By comparing the reproduction level difference between f1 and f2 by a method described later, it is possible to know the amount of deviation of the head scanning from the recording magnetization locus.

FIG. 10 is a block diagram of a processing circuit for obtaining a tracking error signal from a reproduced pilot signal. In the figure, a circuit 1001 has a frequency of 120 kHz and a frequency of 1 kHz.
This is a band-pass filter that extracts a frequency component of 80 kHz. Circuit 1002 is a tuning circuit that tunes to a signal having a frequency of f1. Circuit 1003 is a tuning circuit that tunes to a signal having a frequency of f2. After the output signals of the tuning circuits are detected and rectified by the circuits 1004 and 1005, their levels are compared by the comparison circuit 1006. The comparison circuit output signal is inverted by an inverting circuit 1008 around 1/2 Vcc (Vcc is a power supply voltage). The inverted and non-inverted outputs are input to the switch circuit 1010, and are alternately switched and output each time the combination head performs one scan in accordance with the head switching signal (HSW signal) supplied from the terminal 1009. As is clear from FIG. 11, the head displacement direction with respect to the recording track and the change in the reproduction level of the signals f1 and f2 have opposite relationships between the R1 / L1 track and the R2 / L2 track. Therefore, the inverting circuit 10
If the polarity is switched for each scan of the combination head by using 10, the polarity of the tracking error signal obtained at the terminal 1011 will be the polarity corresponding to the track deviation regardless of the scanning track.

In a format in which one frame is completed with a plurality of tracks, it is necessary for the reproducing circuit to recognize the track position in one frame. Therefore, for each track, a track number is recorded so as to be superimposed on information signals of all tracks. You. During playback, the track number is demodulated,
The track indicating the head of the track number and a reference frame signal (hereinafter, RF) output from the reference signal generator 911
The control is performed so that edges of the S signal coincide with each other. As an example, FIG. 7 shows a magnetization locus recorded in a format in which one frame is completed by 10 tracks. In this example, it is obvious that the reference frame signal is a signal obtained by dividing the reference rotation signal by five. FIG. 8 shows the phase relationship between the RFS signal and the track number of each track.
It can be seen from FIGS. 7 and 8 that when only normal tracking control is performed, there are five types of pull-in possibilities for the phase relationship between the head scanning and the RFS signal. A method for keeping the phase relationship between the RFS signal and the track number constant (hereinafter referred to as frame synchronization) will be described below.

In the conventional frame synchronization, as a first method, the phase control of the capstan is turned off until the RFS signal and the track number have a normal phase, and the phase control is performed when the head scan scans a normal track. Alternatively, as a second method, the phase relationship between the retracted track and the RFS signal is determined, and the speed of the capstan is forcibly accelerated or decelerated based on the phase relationship, thereby normalizing the phase relationship between the RFS signal and the track number. Methods have been taken to fix it.

[0008]

However, in the first method of the prior art, the track number and the RFS
There is a drawback that it takes time until the signal phase becomes normal, and the screen is disturbed for a long time when the still is released. Further, the second method of the prior art has a disadvantage that the tape is easily damaged due to forced acceleration or deceleration.

An object of the present invention is to provide a magnetic recording / reproducing apparatus which does not damage the tape and does not disturb the screen when the still is released.

[0010]

In order to solve the above-mentioned problems, a magnetic recording / reproducing apparatus according to the present invention detects a level difference of the pilot signal leaking from both tracks adjacent to a track scanned by a rotary head. Means for performing tracking control based on the level difference, means for detecting the track number, means for outputting a signal corresponding to the track number, and a reference which is a rotation reference of a cylinder motor for driving the rotary magnetic head. Reference generating means for generating a rotation signal and a reference frame signal, capstan stopping means for stopping the capstan motor in synchronization with the reference frame signal, and capstanting by a signal corresponding to the track number when the capstan motor stops. An arithmetic processing unit for determining a motor start timing is provided.

[0011]

According to the present invention, the track number and the phase of the reference frame signal are obtained when the capstan reaches a constant speed at the start of tape running such as when the still is released, even in a format in which one frame is completed by a plurality of tracks. The relationship can be matched, and the phase pull-in of the capstan motor can be accelerated at the start of tape running.

[0012]

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

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, a block denoted by 101 is a conventional V
It has the same function as the configuration of the TR servo mechanism.

First, the stop timing of the capstan motor 925 will be described with reference to FIG. When information for switching from the normal reproduction to the still command is input to the microcomputer 917 from the terminal 916, the microcomputer 917 sends to the second drive circuit 922 a command 935 to stop the capstan motor 925 at the timing of the rising edge of the RFS signal 102. Output, and the capstan motor 925 is stopped. Next, the setting of the capstan activation timing in the still state will be described. The reproduction information signal obtained from the rotating head 903 is amplified by the head amplifier 914 and input to the demodulation circuit 915. The demodulation circuit extracts the track number of the track being scanned by the rotary head. In the still state, the signal 1 corresponding to the track number extracted by the demodulation circuit 915
03 to the microcomputer 917. The microcomputer 917 determines the capstan ON command timing according to the track number. Next, the timing at which the still is released will be described with reference to FIG. Upon receiving a start command from the terminal 916, the microcomputer 917 outputs a capstan ON command to the second drive circuit 922 at the start timing determined in the still state and at a timing synchronized with the rising edge of the RFS signal. Then, the capstan motor 925 is started. The start timing of the microcomputer 917 is set by a timer or the like and a capstan ON / OFF command is output from a general-purpose port. The set value of the timer is a predetermined time ΔT required for starting the capstan motor from the on-track timing. It is necessary to set the expected timing. Also, it is obvious that the polarity of the tracking error signal can be matched between the stop and the start by synchronizing the stop and the start of the capstan motor with the rising edge of the RFS signal.

Next, software processing of the microcomputer 917 will be described with reference to FIGS. 2, 3, 4 and 5. After the power is turned on, the main processing shown in FIG. 2 is performed. In FIG. 2, a process 201 is a process for performing initial setting, and is a process for clearing the RAM FLG1 and FLG2. After the process 201, the process proceeds to a process 202. Processing 2
02 is a determination process for determining whether the command input from the terminal 916 is a capstan ON or OFF.
If a capstan OFF command has been input from the terminal 916, the process proceeds to step 203. If the capstan OFF command has been issued, the process enters a standby state. The process 203 is performed in a RAM FL described later.
This is a process of storing 1 in G1. The process 204 is a process for decoding the signal 103 input to the microcomputer 917. Process 205 is a process for determining the type of the track number from the signal 103.
Or, it is a process of determining whether or not 1 is indicated. Processing 2
If the track number is 0 or 1 in 05, the process proceeds to step 210, otherwise the process proceeds to step 206. Process 206 is a determination process for determining whether the track number is 2 or 3. Track number 2 in process 206
If it is 3 or 3, the process proceeds to the process 211;
Proceed to. Process 207 is a determination process for determining whether the track number is 4 or 5. Processing 20
If the track number is 4 or 5 at 7, the process proceeds to step 212, otherwise the process proceeds to step 208. The process 208 is a determination process for determining whether the track number is 6 or 7. If the track number is 6 or 7 in the process 208, the process proceeds to the process 213, and otherwise proceeds to the process 209. Processes 210, 211, 212, 213, and 209 are processes for determining the set value of the timer for setting the timing for activating the capstan motor for each track number. The above is the detailed description of FIG.

FIG. 3 shows an external interrupt process in which an interrupt occurs every time the HSW signal is input to the microcomputer 917. Process 301 is a determination process. If a capstan ON command has been input from the terminal 916, process 3
02, if capstan OFF command, process 30
Go to 9. The process 302 is a determination process, and is performed when the RAM FL
If G1 is 1, the process proceeds to step 303; The process 303 is a determination process. If the level of the HSW signal is H, the process proceeds to a process 304. If the level of the HSW signal is L, the process proceeds to a process 308. Process 304 is a judgment process, in which the level of the RFS signal 102 is inverted and
Processing 305 when the level of the signal 102 is inverted from L to H
Otherwise, the process proceeds to process 308. Processing 3
05 is a process for clearing the RAM FLG1. Process 306 is a process for clearing the RAM FLG2. The process 307 is a process for starting a timer so that a timer interrupt occurs at the timing set in the main process of FIG. The process 309 is a judgment process, and the RAM FL
If G2 is 1, the process proceeds to step 308; otherwise, the process proceeds to step 310. The process 311 is a judgment process. When the level of the RFS signal 102 is inverted, and when the level of the RFS signal 102 is inverted from L to H, the process proceeds to the process 312.
The process proceeds to step S8. The process 312 is executed by the microcomputer 917 to send the capstan OF to the second drive circuit 922.
This is the process of outputting the command of F. After the process 312, the process proceeds to a process 313. The process 313 is a process for storing 1 in the RAM FLG2. The above is the detailed description of FIG.

Next, FIG. 4 will be described. FIG. 4 shows a timer interrupt process, which occurs when the timer started in process 307 in FIG. 3 reaches a set value. In the process 401, the capstan ON command is transmitted to the second
This is a process of outputting to the drive circuit 922 of FIG. FIG. 4
It is a detailed description of. Here, the RAM FLG1 is a flag for passing the processing after the processing 305 and the FLG2 only once for the processing after the processing 312 at the time of the capstan ON / OFF operation.

The above is the software processing performed by the microcomputer 917. In the present embodiment, the signal 103 corresponding to the track number may be parallel or serial. Further, in this embodiment, the mode transition from the still mode to the normal reproduction mode has been described. However, it is obvious that the present invention can also be applied to the transition shooting and the pull-in of the track phase at the start of the insertion. Further, in the present embodiment, the set value of the timer is set at a timing that allows a margin for a predetermined time ΔT required for starting the capstan motor from the on-track timing, but it depends on the inertia of the motor and the like. The set value may be changed accordingly. In this embodiment, the capstan stopping means and the driving means are implemented by the same microcomputer. Also, the signal 103 corresponding to the track number may have a plurality of patterns due to the head scanning crossing the track when the capstan is stopped. When designing the demodulation circuit 915, when designing the demodulation circuit 915, either the first half or the second half of the head scanning is used. Is determined in advance, and the capstan activation timing may be determined based on the information.

[0019]

As is apparent from the above description, according to the present invention, even in a magnetic recording / reproducing apparatus in which one frame is completed by a plurality of tracks, the capstan has a constant speed at the start of tape running such as when the still is released. The track number and the reference frame signal when the tape is running, the capstan motor phase can be pulled in quickly when the tape starts running, and a mode transition from still to normal playback without screen noise is realized. it can.

[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 flowchart of a main processing program of a microcomputer applied to the present invention;

FIG. 3 shows the HS of the microcomputer applied to the present invention.
Flowchart of the processing program when a W interrupt occurs

FIG. 4 is a flowchart of a processing program when a timer interrupt of a microcomputer applied to the present invention is input;

FIG. 5 is a timing chart showing a capstan stop timing in one embodiment of the present invention.

FIG. 6 is a timing chart showing capstan activation timing in one embodiment of the present invention.

FIG. 7 is a schematic diagram illustrating a magnetization locus recorded in a format in which one frame is completed by ten tracks in one embodiment of the present invention.

FIG. 8 is a timing chart showing a phase relationship among a reference frame signal, an HSW signal, and a track number in one embodiment of the present invention.

FIG. 9 is a block diagram of a main part of a servo mechanism during reproduction of a conventional magnetic recording / reproducing apparatus.

FIG. 10 is a block diagram of a conventional circuit for generating a tracking error signal.

FIG. 11 is a schematic diagram showing a magnetization locus of the same-frequency pilot signal.

FIG. 12 is a schematic diagram showing a head configuration of a cylinder motor equipped with two pairs of heads having the same combination head configuration.

[Explanation of symbols]

 901 Magnetic tape 902 Cylinder motor 903 Magnetic head 904 Rotational phase detector 905 Frequency generator 906 Cylinder motor drive circuit 907 Frequency discriminator 908 Amplifier circuit 909 Adder 910 Phase comparator 911 Reference signal generator 912 HSW signal generator 913 Tracking error Signal generator 914 Head amplifier 915 Demodulation circuit 917 Microcomputer 919 Phase comparator 920 Adder 921 Amplification circuit 922 Capstan motor drive circuit 923 Frequency discriminator 924 Frequency generator 925 Capstan motor

Claims (1)

(57) [Claims] 1. An information signal recorded diagonally by a rotating magnetic head, and pilot signals f0, f1, f0, f2, f0, f1,... The information signal is superimposed and recorded, and is the information signal in which one frame of information is recorded in a plurality of tracks, and the information signal in which a track number is recorded for each track is reproduced. Means for comparing the level difference of the pilot signal reproduced from each adjacent track located on both sides of the track scanned by the rotating magnetic head; means for performing tracking control based on the level difference; and means for detecting the track number Means for outputting a signal corresponding to the track number, and a cylinder motor for driving the rotary magnetic head. Reference generating means for generating a reference rotation signal and a reference frame signal as a rotation reference, capstan stopping means for stopping a capstan motor in synchronization with the reference frame signal, and a track number when the capstan motor is stopped. A magnetic recording / reproducing apparatus comprising arithmetic processing means for determining a start timing of a capstan motor based on a corresponding signal, and speeding up the pull-in of the capstan motor at the start of tape running.