JPH01276979A - magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a stable slow-motion reproduced picture even from a tape which is deteriorated in interchangeability by controlling the braking timing to a capstan motor by means of a control signal calculated by an auto-tracking device and phase difference information to the reference phase of a rotary magnetic head. CONSTITUTION:A slow auto-tracking process is performed by respectively storing head switching signals inputted to the 2nd input terminal of a capture controller 800 and the data of a capture register 700, to which the count value of envelope comparing signals inputted to the 5th input terminal are fetched, in memories 3 and 4 and finding the difference between the data stored in the memories 3 and 4. By alternately performing the slow tracking quantity change and comparison of magnitude of phase difference between the head switching signals and envelope comparing signals in such way each driving intermittently a capstan motor 6, a further optimum slot tracking point can be found.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording/reproducing device having an auto-tracking function in slow motion playback, and in particular provides a device that can be realized easily and at low cost using a microprocessor. It is.

BACKGROUND OF THE INVENTION In recent years, microprocessors have become widespread and are being used in many household electrical appliances. Home video tape recorder (hereinafter abbreviated as VTR)
This is no exception, and microprocessors are used at the center of the system to control the loading mechanism that pulls out the magnetic tape from the cassette and wraps it around the rotating head, and to make program reservations using a timer. However, precision rotation control devices for the cylinder motor that drives the rotating head and the capstan motor that runs the magnetic tape at a constant speed require complex judgment operations and rapid processing of detection signals, so microprocessors are not required. It has relied on specialized hardware.

FIG. 12 is a block diagram showing the configuration of a servo mechanism during playback of a conventional VTR, in which rotary magnetic heads 81 and 82 are close to each other, one-rotation magnetic heads 91 and 92 are close to each other, and each rotates approximately 180 mm. A cylinder motor that drives four rotating magnetic heads 81, 82, 91, and 92, which are arranged at a position of .degree. and have one rotation magnetic heads 81 and 91 having the same azimuth angle, and rotating magnetic heads 82 and 92 having the same azimuth angle. 2, a first frequency generator 3 that detects the rotational speed of the cylinder motor 2, a phase detector 4 that detects the rotational phase of the cylinder motor 2, and an output signal of the first frequency generator 3. A first frequency discriminator 40 that detects an error with respect to the reference period, a reference signal generator 42, and a phase between the rotational phase signal obtained from the phase detector 4 and the reproduced reference signal obtained from the reference signal generator 42. a first phase comparator 41 that detects an error; a first adder 43 that mixes the phase error output of the first phase comparator 41 and the speed error output of the first frequency discriminator 40; A first amplifier 44, a first drive circuit 12 that drives the cylinder motor 2, a capstan motor 6 that runs the magnetic tape at a constant speed, and a second frequency power generator that detects the rotational speed of the capstan motor 6. a control head 5 that detects a control signal recorded on the lower end of the magnetic tape 1, and a second frequency discriminator 4 that detects an error in the output signal of the second frequency generator 7 with respect to a reference period.
6, a tracking monomulti circuit 46 whose delay time is varied by a variable resistor 60 triggered by the output signal of the reference signal generator 42, and the control head 5.
a second phase comparator a47 that detects the phase error between the control signal obtained from the control signal and the output signal of the tracking monomulti circuit 46, the phase error output of the second phase comparator 47, and the second frequency a second adder 48 for mixing the velocity error output of the discriminator 45; and a second amplifier 4
9, a second drive circuit 1a that drives the capstan motor 6, and a forced acceleration command signal and a motor using the rotational phase signal and the control signal as reference signals in order to intermittently drive the capstan motor during slow motion regeneration. It is composed of an intermittent running control circuit 61 that outputs a 0N10FF signal, a current direction switching signal, etc., and a third adder 63 that mixes the output of the second amplifier 48 and the forced acceleration command signal of the intermittent running control circuit 610. There is.

Regarding the VTR configured as described above, the operation during normal playback will be briefly explained using the configuration diagram shown in FIG. 12 and the timing chart of the main parts shown in FIG. Figure 13 N
is the output waveform of the reference signal generator 42 in FIG.
6. The trapezoidal wave signal in FIG. 130 is an internal waveform of the first phase comparator 41, and is the phase reference signal of the cylinder motor triggered by the rising edge of FIG. Detector ・Sampled from the rotational phase signal obtained from the device 4, that is, the falling edge of P in FIG. 13, and the velocity error obtained from the hold signal (not shown) and the first frequency discrimination 1s40 in FIG. The signal is mixed by a first adder 43 and supplied to the first drive circuit 12 via a first amplifier 44. Therefore, the cylinder motor, that is, the rotation head 8 rotates in phase synchronization with the reference signal shown in FIG. 13N. Figure 13q shows the tracking monomulti circuit 46 in Figure 12.
This is the charging/discharging waveform of the capacitor (not shown) in the first
It is triggered by the rising edge of FIG. 3N, and the delay time can be varied by changing the time constant with the variable resistor 60 of FIG. 13R is the output waveform of the tracking monomulti circuit 46.
The trapezoidal wave signal in FIG. 12 is the internal waveform of the second phase comparator 47 in FIG. 12, and the falling edge in FIG. The playback control signal obtained from the control head 5 in the figure, that is, the hold signal (not shown) sampled by the rising edge in FIG.
and the speed error signal obtained from the second frequency discriminator 46 in FIG.

At this time, the forced acceleration command signal of the intermittent running control circuit 61 has a high impedance.

Therefore, the capstan motor 6 rotates in phase synchronization with the output signal of the tracking monomulti circuit 46 shown in FIG. 13H, which is obtained by phase-shifting the reference signal shown in FIG. 13H. As described above, during normal playback of a VTR, by synchronizing the phases of the rotary head 8 and the playback control signal (13.5T), the rotary head 8 can optimally track the tracks recorded on the magnetic tape 1. become.

Next, the operation during slow motion reproduction will be explained with reference to the timing chart shown in FIG. In order to improve transient characteristics during slow motion playback, the second
The phase error output of the phase comparator 47 is AC grounded,
The capstan motor 6 is rotated by being provided with only a speed control system. Figure 14 U and V are the forced acceleration command signal synchronized with the rotation phase signal of the cylinder motor in Figure 14 P and the motor 0N1.
0FF signal, W in Figure 14 is capstan motor 6
This is the current direction switching signal of the slow tracking monomulti circuit (the delay time can be set by the variable resistor 62 inside the intermittent running control circuit 61) which is triggered by the control signal shown in FIG. 14T. Output signal (set by the 14th diagram and reset after a certain period of time. With the above three signals (Fig. 14 U, V, W),
As shown in FIG. 14XK, motor current flows through the capstan motor e and the magnetic tape 1.
is intermittently driven by transitioning from stop → acceleration → constant speed → deceleration → stopped state. The four rotating magnetic heads 81, 82, 91, and 92 are constantly rotating, and when the magnetic tape 1 is stopped, still playback is not performed, and when the magnetic tape is transferred, normal playback is not performed. By skillfully switching the rotating magnetic head, noiseless slow-motion playback images can be obtained, but the most important thing is to set the timing for moving or stopping the magnetic tape so that the playback image is not disturbed.

Problems to be Solved by the Invention For this reason, the timing of stopping the C capstan motor 6 is important. When stopping the C capstan motor 6, the control signal is picked up as described above, and the deceleration state is started after a certain delay time from that signal. The magnetic tape is then stopped at a position where the rotating head stably traces the recording track (not shown) on the magnetic tape.If the formats of the tracks recorded on the magnetic tape are compatible. ,
The variable resistor 62 may be a fixed resistor, but it may be used when the magnetic tape expands or contracts due to environmental changes such as temperature changes, or when playing back in slow motion a tape recorded on another VTR in which an error with the mechanism occurs. In this case, it becomes necessary to change the brake timing in order to optimize the tracking state. For this purpose, the variable resistor 62 shown in FIG. 12 is necessary. Furthermore, this variable resistor needs to be made into a volume with a click point to make it available to the user. Generally, the resistance value at the click point of a volume with a click point varies, and in order to compensate for this variation, another variable resistor is required. Therefore, in the conventional VTR, not only an adjustment volume is required for tracking, but also the usability of the operability knob needs to be improved.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording/reproducing device of the present invention automatically adjusts the phase difference between the control signal and the rotating magnetic head so that the rotating magnetic head can optimally track the recorded track. A magnetic recording and reproducing apparatus has an auto-tracking function to control the speed of the magnetic tape, and a slow-motion reproducing function by repeatedly stopping and moving a magnetic tape transferred by a capstan motor, are adjacent to each other, a second and a fourth are adjacent to each other, and each is also located at approximately 1800 degrees, the first and second have the same azimuth angle, and the third and fourth have the same azimuth angle. Four rotating magnetic heads, a cylinder motor that drives the four rotating magnetic heads, and a head switching signal that indicates the rotational phase of the cylinder and cylinder motors to control the two rotating magnetic heads that are in contact with the magnetic tape inside each of the rotating magnetic heads. a switch means for extracting a reproduced signal from the magnetic head;
Comparing means for comparing the output/bell of the two reproduced signals from the switch means, phase difference detection means for detecting a phase difference between the head switching signal, and a control signal calculated by the auto-tracking device and the rotating magnetic head. The apparatus further includes variable tracking means for controlling the timing at which the brake is applied to the capstan motor based on the phase difference information with respect to the reference phase and the phase difference information obtained from the phase difference detection means.

Operation In the present invention, with the above-described configuration, recording was performed using other VTRs in which the magnetic tape expanded or contracted due to environmental changes such as temperature changes, or other VTRs in which mechanical errors occurred. It is possible to obtain a magnetic recording and reproducing apparatus that realizes stable slow-motion reproducing images even with tapes having deteriorated compatibility.

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

FIG. 1 shows a configuration diagram of a VTR having an auto-tracking function during slow-motion playback (hereinafter referred to as auto-slow tracking) according to an embodiment of the present invention. The rotating magnetic heads 81 and 92 are close to each other, and the rotating magnetic heads 91 and 92 are close to each other.
have the same azimuth angle, and the rotating magnetic heads 82 and 92
four rotating magnetic heads having the same azimuth angle;
A microprocessor 10 controls the cylinder motor 2 that drives the four rotating magnetic heads 81, 82, 91° 92 and the capstan motor 6 that runs the magnetic tape 1 at a constant speed, and also realizes an auto-slow tracking function. a first drive circuit 12 that drives the cylinder motor 2 by a signal outputted from the microprocessor 1o via a first analog signal output terminal 3; and a second analog signal output terminal from the microprocessor 1o. a second drive circuit 13 that drives the capstan motor e (according to the signal outputted through the second drive circuit 32), and amplify the reproduced video signals obtained from the four rotating magnetic heads 81, 82, 91, 92, respectively; The microprocessor 10 has input terminals 21 to 26 connected to a first frequency generator 3 and a first phase detector. 4 and a control head 6 and a second frequency generator 7
and the output of the head amplifier circuit 11 are connected.

The inside of the microprocessor 10 includes a register 100 for storing data and a random access memory (indicated by the abbreviation RAM in the figure, hereinafter referred to as R).
It is abbreviated as 5■. )20°, a 16-pit arithmetic unit that executes arithmetic and logical operations on digital data (indicated by the abbreviation MLU in the figure, hereinafter abbreviated as MLU)3oO, and a sequential execution unit. An instruction execution circuit (indicated by the abbreviation PL in the figure) stores an instruction to be executed and controls the operations of the registers 1oo and 31M2O0 and the MLU 300 via a control path 460 based on the instruction. ) 4oO, a 17-bit time base color/reference signal (indicated by the abbreviation TBC in the figure) that counts down the reference clock signal applied to the clock terminal 20, and a counter bus 550. A capture register block (0APRRG in the figure) is supplied with the count data of the time base counter 60°, and the output data is sent to the data bus 600 connected to the register 100, the RAM 200, and the RAM 300. (Indicated by an abbreviation.) To.

and the first to sixth input terminals 21, 22, 23°24.2
A capture controller (abbreviated as CAPTRCTRL in the figure) transfers the count data of the time base counter 600 to the capture register block 700 when the edge of five types of capture symbols, each having a different generation source, arrives. The reference clock signal applied to the clock terminal 2o is a timing generator (indicated by the abbreviation TG in the figure).
900 to the instruction execution circuit 400, and the data bus 600 includes a read-only memory (indicated by the abbreviation ROM in the figure. Hereinafter abbreviated as ROM) 1000 first D; system converter 1400. Second
0Dm converter 1500. Timer counter 1100. A master latch circuit 1200 for data output is connected, and a slave latch circuit 1300 is connected to receive the output data of the master latch circuit 1200 in response to a count completion pulse of the timer counter 1100. each has an address decoder 250.1050.

The capture controller 800 and the capture register block 700 receive count data from the time base counter 500 when the edge of the capture signal arrives, and the minimum decomposition accuracy is higher than the execution cycle of the instruction.

It constitutes a capture circuit that sends the result to the MLU 300, the register 1oO, or the RAM 200 according to a specific instruction from the instruction execution circuit 400.

FIG. 2 shows the internal configuration of the head amplifier circuit 11, and shows the internal configuration of the head amplifier circuit 11.
two head amplifiers 111, 112° 1f3, 114,
A first switch 116 to which the head amplifiers 111 and 112 are input, a second switch 116 to which the head amplifiers 113 and 114 are input, and an output between the first switch 116 and the second switch 116. The first switch 116 and the second switch 116 are configured by a third switch 117 to which an output is input, and a level comparator 118. The switch 117 is controlled by a head amplifier switching signal inputted from an input terminal 122, and the outputs of two pairs of heads in contact with the magnetic tape 1 are inputted to the third switch 117 and level comparator 118. And in the level comparator 118, 2
The output terminal 1 outputs the result of determining the magnitude of the two head output levels.
Output to 19.

Regarding the VTR configured as described above, the configuration diagram shown in FIG. 1 and the capture controller 8 shown in FIG.
The operation will be explained with reference to a specific configuration diagram of 00 and a timing chart of the main parts shown in FIG.

First, FIG. 3 shows the capture controller 800 of FIG.
It is a logic circuit diagram showing a specific configuration example, in which control units 810 to 850 of the same configuration are read directly from the first to sixth input terminals 21, 22, 23°24.2sKii, and the Control units 810-850
each have a common reference clock input terminal 801 and a data transfer lock input terminal 802 to the capture register block 700, and one individual reset terminal 81.
1 to 861 and individual flag output terminals 812 to 862,
It has individual data transfer terminals 813-853.

Next, FIG. 4 shows a control unit 86 that includes the capture controller 800 shown in FIG.
Fig. 4B shows the clock signal waveform applied to the clock terminal 2o of Fig. 1, and Fig. 4B shows the signal waveform of Fig. 4M. This signal is supplied as a reference clock signal to the reference clock input terminal 8o1 in FIG. In addition, FIG. 4G shows the count clock signal waveform of a time-paced color/receiver 500 constructed by a synchronous counter whose unit stage is seven lip-flops in the master-slape format. At the (leading edge), the output of the master portion of the flip-flop of each unit stage changes, and at the trailing edge (trailing edge), the output of the slave section changes. The fourth diagram shows a clock signal waveform for data transfer created from the signal waveforms of FIGS. 4 and B, and is supplied to the data transfer/feed lock input terminal 802 of FIG.

Now, when the signal waveform shown in FIG. 3E is applied to the sixth input terminal 25 in FIG. 3, after the leading edge arrives, the reference clock input terminal 8010 level becomes "
At the time when the output level of the HAND gate 864 shifts to "1" as shown in FIG. 4F, the output level of the HAND gate 855 shifts to "1" as shown in FIG. As shown in FIG. As shown in FIG. 4H, it shifts to "1". Each of the HAND gates 854, 855, and 866 is connected to another HA that is a pair.
Since it forms a bistable circuit with the ND gate, when the output level shifts to "1", it will maintain that state until a reset signal is applied to the other (iAND) gate. At the point when the output level of 856 shifts to "1", the output rep of the paired HAND gate 867
Since the output level of the HAND gate 868 also shifts to "o", the HAND gates 854 and 8
The output level of 55 returns to "0".

In this way, when the leading edge of the external signal arrives at the sixth input terminal 25, the second data transfer terminal 8
63, a signal waveform as shown in FIG.

This signal causes the time base counter 6oO in FIG.
Count data is transferred from the capture register block 700 to the capture register block 700.

The output signal of the 11fAND gate 866 is sent to the flag output terminal 852 and is used as a capture flag signal indicating that the count data of the time base counter 60o has been transferred. The reset signal is applied after the software (program) confirms that the flag is set.

Next, FIG. 51 is a configuration diagram showing a specific example of the capture register block 700, in which each data input terminal is connected to a Do terminal to a D15 terminal, and a data output terminal is connected to a Q1 terminal to a Q16 terminal. Unit registers 710 and 720 configured by 16 memory cells
(!:, The whole unit registers 730, 740, 750 are configured by 16 memory cells whose data input terminals are connected to the D1 terminal to D16 terminal, and whose data output terminals are connected to the Q1 terminal to Q16 terminal. Each of the unit registers 710 to 750 has two control signal terminals, and the read terminals 711 to 751 each receive a data transfer signal from the capture controller 80° shown in FIG. The instruction execution circuit 40 is applied to the select terminals 712 to 752.
The output side of each unit register is made active by a specific read instruction stored in the program storage area of 0, and the readout side is sent to the data bus 80o in FIG. 1 via the data output terminals Q114 to Q16. A second select signal is applied.

By the way, in FIG. 6, unit registers 730 to 750
The connection positions of the data input terminal and data output terminal of the data input terminal and the data output terminal are shifted by one bit, and this is due to the following reason.

First, regarding the unit registers 710 and 720, in order to improve the resolution of the timing of capturing the edge of the external signal (
The LSB of the time base counter 50o and the LSB of the unit register are matched, but the unit registers 730 to 75
For 0, the data input terminal is shifted to the right by one bit so that twice the interval can be processed at once with the same number of bits as the unit registers 710 and 720.

With this bit shift configuration of the unit registers 730 to 760, for example, the frequency of the reference clock signal can be changed to 2M.
1-(When selecting z, unit register 710.720
Count data with a resolution of 5 oons is obtained from the unit registers 730 to 750, while count data with a resolution of 5 oons is obtained from the unit registers 730-750
It is possible to measure the arrival period of an external signal having a frequency of Tianjohen in one process.・The configuration diagram shown in Figure 1 and Figure 6 for the VTRK with the auto-slow tracking function configured as above.
The operation will be explained with reference to the operation flowcharts and operation waveform diagrams shown in FIGS. FIG. 6 is a flowchart showing an example in which a control means for intermittent driving operation of the capstan motor 6 during slow motion reproduction is realized by a program built in the microprocessor 1o of FIG. Regarding the flowchart in Figure 6, Section 12
This will be explained with reference to the operational waveform diagram of a conventional VTR shown in the figure.

Branches 401.404, 408°413.4 in Figure 6
Reference numerals 17, 421, and 427 are for executing the necessary processes in a sequence to intermittently drive the capstan motor 6 by branching according to the value of the state variable M.
First, when the sum is 0, branch 401 causes branch 401 to
2, the head switching signal (hereinafter referred to as H8f) is generated.

) is "1", and if yes, the process moves to processing block 403 and the state variable M is set to "1".

When the signal level is 1, branch 404 advances to branch 405, where it is determined whether the signal level of the H8W signal is rOJ, and if it is, it means that a falling edge of the H5W signal has been produced. Then, the time until the start timing of the capstor/motor 6 is subtracted from the count value of the time pace counter 500 (down count) in FIG. This corresponds to point b in FIG.

When the time is 2, the branch 408 advances to the branch 409, and the time base counter 50o (hereinafter referred to as TBC)
Purify. ) and process block 406
If the difference is within the count range of timer 11oo in FIG.
The output data is set to 0, and the difference data is sent to the timer 11o.

Set K. Here, the data set in the master latch circuit is a signal corresponding to V in Fig. 14, that is, motor 0N1.
This is to output the 0FF signal to the output terminal 29. The data-set timer transfers the data of the master latch circuit to the slave latch circuit 13oO after completion of counting regardless of software (program), so that a jitter-free signal can be obtained. Next, processing block 4
11, in order to determine the forced acceleration period (the period from point 0 to point d in FIG. 14), a count value is set in the memory in the same manner as in processing block 406, and processing block 4
12 makes the number 3.

When the number of points is 3, branch 414 and processing block 416 process the 14th point corresponding to point d in FIG.
1. Turn off the 9H signal, that is, the forced acceleration command signal,
The capstan motor 6 is driven at a constant speed (transition to C). Here, the forced acceleration command signal is the second Dm conversion 5150 in FIG.
0 output (not shown).

When the time is 4, the process proceeds to branch 418, where it is determined by a flag whether or not a control signal input to the third input terminal of the capture controller 800 has arrived;
If the control signal has arrived, processing block 4
19 and the TB when the control signal arrives
Capture register 70 that captures the count value of C
The data of 0 is taken into the storage accumulator CC (not shown) in the register 1oo of FIG. 1, and the data of memory 1 (described later) where the slow tracking shifter amount is stored is transferred Subtract and note the result! 72 and set the value to 5 (point e in Figure 14).

When the count value is 6, processing block 422 compares the data in memory 2 stored in processing block 419 with the count value of TBC, and branches 423 and processing block 424.
The forced acceleration command signal and the fourteenth
Both current direction switching signals corresponding to figure W are set to "1",
The motor is shifted to a deceleration state (point f in Fig. 14). Next, in processing block 426, in order to determine the braking period (the period from point f to point g in FIG. 14), a count value is set in the memory in the same manner as in processing block 406, and in processing block 426, the count value is set to 6. do.

When the time is 6, branch 428 and processing block 429 perform the same procedure as that performed in branch 409 and processing block 410.
The motor 0R10FF signal shown in FIG.

With the above, the capstan motor 6 can be driven intermittently.

Next, the auto-slow tracking operation will be explained using the flowcharts of FIG. 7 and FIGS. 81(L) and (b) and the operation waveform diagrams of FIGS. 9 to 11.

9 to 11 are track trajectories during still playback at different slow tracking points and waveform diagrams of various parts of the head amplifier circuit of FIG. 2, respectively. The deviation A is also a field neutral state due to the rotating magnetic heads 81 and 91, and the waveform J is the head amplifier 112 of the rotating magnetic head 91.
The waveform is the envelope output signal of the head amplifier 111 of the rotating magnetic head 81, and the waveform is the envelope output signal of the head amplifier 111 of the rotating magnetic head 81. The waveform is the envelope output signal of the head amplifier 111 of the rotating magnetic head 81. Waveform P is the head switching signal.

The waveform proof is the head amplifier switching signal applied to the input terminal 122IC in FIG. 2, and the waveform 2 is the envelope output signal level of the head amplifier 111 of the level comparison circuit 118 in FIG. 2 and the envelope output of the head amplifier 112. This is a signal level and magnitude comparison output (envelope comparison signal). As can be seen by comparing Figure 9 to Figures 1 and 1, the tracking condition in Figure 9 is optimal and the tracking condition in Figure 10 and Figure 1 is the best.
In Figure 1, noise appears because the envelope output near the head switch has decreased. The phase difference between the head switching signal and the machine/beam comparison signal changes accordingly.
It can be seen that the optimal tracking point is when the phase difference is minimum.

FIG. 7 is a flowchart showing an example in which means for obtaining phase difference information between the control signal calculated by the auto-tracking device and the base phase of the rotating magnetic head is realized by a program built into the microprocessor 10 shown in FIG. , during still playback during slow motion playback, first, in branch 431, it is determined whether or not a slow tracking command indicating that the slow motion operation has been started has arrived, using a flag, and if it has arrived,
The process moves to processing block 433, where "1" is assigned to a counter variable C indicating that slow auto tracking is being executed.

Next, in processing block 434, the register 1o of FIG.
In processing block 436, muco is multiplied by a coefficient α, and a constant β is added to convert it into a phase difference for slow motion reproduction. The converted value is stored in the memory 1 described in the explanation of FIG. 6 as the slow tracking shift amount in processing block 436. At this point, rough slow auto tracking is established. Further, in branch 432, it is determined whether or not the count of counter variable G is "0", and if it is not "0", processing of processing blocks 433 to 436 is skipped, and the process moves to FIG. 81 (IL).

Next, means for producing a phase difference between the head switching signal and the envelope comparison signal will be explained using the flowchart shown in FIG. 8(&). Similar to the phase difference conversion means in FIG. 7, the program runs only once for each still during slow motion playback.
1, respectively, the capture controller 8oO
a head switching signal input to a second input terminal of the head switching signal;
It is determined by the flag whether or not the empe comparison signal inputted to the fifth input terminal has arrived, and if it has arrived, the process proceeds to processing blocks 438 and 442, and counts the TBC when each signal arrives. The data of the capture register 700 with the value taken in is taken into the memory 3 or 00, respectively, and stored in the memory 3 or the memory 4, and the H flag and the X flag are set in processing blocks 439 and 443, respectively. Processing blocks 440 and 444 then reset the respective flags in the capture registers.

Finally, the main flow of slow auto tracking will be explained using the flowchart of FIG. 8(b).

The phase difference detection means shown in FIG. 8 (IL) is configured to run the program after both the head switching signal and the comparison signal arrive.

This determination is made in branch 446. In the branch 445, if both the H flag and the
7, if the value of mu aC is negative, processing block 44
Proceed to step 8, find the two's complement of the value of CC, and calculate it again to OA.

Next, in branch 449, if the noise of MuaC exceeds the value of threshold 1 (denoted as THl in the figure),
Processing block 460 assumes that there is an @ symbol in the input of the empe comparison signal in the phase difference detection of FIG. 8 (IL).
Reset the X flag with and restart phase difference detection.

If not in the branch 449, then in the branch 461, the noise of the mu CO is set to threshold 2 (TH2 in the figure).
If the threshold is exceeded, the processing block 462 is entered and the slow tracking shifter t is determined.
In order to shift by t-minus 11111, a value corresponding to 11 ns is subtracted from memory 1 mentioned in the explanation of FIG. Next, the process proceeds to processing block 467, where the H flag and the Ba,
In processing block 469, the counter variable G is set to "0" and the slow auto tracking process is ended. If the branch 469 is negative, the flow passes through the branch 432 in FIG. 7, and the phase difference detection is repeated again. If no in the branch 461, the process reaches a processing block 461, sets the counter variable C to rOJ, resets the H flag and the X flag in a block 462, and ends the auto-tracking process for slow motion playback. In addition, the branch 447
In , if the value of Mu CO is positive, the branch 44
9. Similarly to 451, in branch 453, the force λ at which the value of MuaC exceeds the threshold 1 is determined.

If yes, the H flag is reset in processing block 454, assuming that there was an error in the capture of the head switching signal in the phase difference detection in FIG. 8 (IL), and the phase difference coalfield is slightly corrected. For example, branch 466 determines whether 500 1 shifts exceeds the threshold 2 shifts, and if yes, proceeds to processing block 466 where 1 shift is performed to shift the slow tracking shifter 791111g.
Add bamboo corresponding to 1 mS from the memory 1 described in the explanation of FIG. 6, and proceed to the processing of the processing blocks 467 to 460.
Do 2 Geography.

Through the above flow, the optimal tracking point for slow-motion playback is determined from the phase difference between the control signal and the rotating magnetic head calculated by auto-tracking, and then the capstan motor 6 is driven intermittently. By changing the tracking force and alternately comparing the magnitude of the phase difference between the head switching signal and the power comparison signal, it is possible to further pursue the optimum slow tracking point.

Effects of the Invention As is clear from the above description, the magnetic recording/reproducing device having the auto-slow tracking function of the present invention uses a control signal and a rotating magnetic head so that the rotating magnetic head can optimally track a recorded track. This magnetic recording and reproducing device has an auto-tracking function that automatically controls the phase difference between the magnetic tapes and a slow-motion reproducing function by repeatedly stopping and moving the magnetic tape transported by a capstan motor. Well, the first
and the third are close to each other, the second and fourth are close to each other, and.

In addition, four rotating magnetic heads (in the embodiment, rotating magnetic heads 81 and 82) are each arranged at a position of about 1800°, the first and second have the same azimuth angle, and the third and fourth have the same azimuth angle. . switch means (in the embodiment, expressed as a first switch and a second switch) for extracting reproduced signals from two rotating magnetic heads; and envelopes of the two reproduced signals from the switch means. Comparison means (
In the embodiment, it is expressed by an envelope comparison circuit. )
and a phase difference producing means for detecting the phase difference between the envelope comparison signal obtained from the comparing means and the head switching signal (in the embodiment, the phase difference detecting means is configured according to the flow chart 2 of FIG. 8 (IL)). ), a homemade phase difference detector, and a means (in the embodiment, the flowchart of FIG. 7) K for obtaining phase difference information with respect to the control signal calculated by the auto-tracking device and the base phase of the rotating magnetic head. ing. ) for controlling the timing at which the brake is applied to the capstan motor based on the phase difference information obtained from the above (in the embodiment, the tracking variable manual blower is configured according to the flowchart in FIG. 8(b)). This system was characterized by the fact that the magnetic tape expanded and contracted due to environmental changes such as temperature changes, and mechanical errors occurred, so it was recorded on nine VTRs. It is possible to obtain a magnetic recording and reproducing device that realizes a stable auto-slow tracking function even for tapes with degraded compatibility. Of course, since there is no need for an adjustment volume like in a conventional VTR, operability can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording and reproducing device having an auto-tracking function according to an embodiment of the present invention, FIG. 2 is a block diagram showing the specific internal configuration of the head amplifier circuit 11 of FIG. 1, and FIG. Capture controller 80 in FIG.
4 is a timing chart explaining the circuit operation of FIG. 3, FIG. 6 is a configuration diagram of the capture register block Too, and FIGS. 6, 7, and 8 (IL ), (b) is a flowchart showing the operation of the main part of FIG. 1, and FIGS.
Figure 12 is a block diagram showing the configuration of the servo mechanism during playback of a conventional VTR. Figures 13 and 14 are the main components of Figure 12. 3 is a timing chart for explaining the operation of the section. 1...Magnetic tape, 2...Cylinder motor, 6...Capstan motor, 11...
...head amp. 1oO...Register, 200...RA
M, 300...-MU LU, 400... Instruction execution means, SOO... Time base counter, 700... Capture register controller, goo...・・Capture controller, 100
0...ROM, 1100...Timer,
1400.1500...DM converter. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
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Claims (1)

[Claims] It has an auto-tracking function that automatically controls the phase difference between the control signal and the rotating magnetic head so that the rotating magnetic head can optimally track the recorded track, and the magnetic head is transported by a capstan motor. A magnetic recording and reproducing device having a slow motion reproducing function by repeatedly stopping and moving a tape,
The first and third are adjacent, the second and fourth are adjacent, and also each are located at approximately 180°, the first and second have the same azimuth angle, and the third and fourth has four rotating magnetic heads having the same azimuth angle, a cylinder motor that drives the four rotating magnetic heads, and a head switching signal indicating the rotational phase of the cylinder motor. a switching means for extracting reproduction signals from two rotating magnetic heads; a comparison means for comparing envelopes of the two reproduction signals from the switching means; and an envelope comparison signal obtained from the comparison means and the head switching signal. and phase difference detection means for detecting a phase difference between the capstan and the control signal calculated by the auto-tracking device, phase difference information with respect to the reference phase of the rotating magnetic head, and phase difference information obtained from the phase difference detection means. 1. A magnetic recording and reproducing device comprising variable tracking means for controlling the timing at which a brake is applied to a motor.