JPH03104484A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize an automatic tracking function by performing the sampling of an envelope detected from a reproducing video signal with a constant phase with a head switching signal for several times, and controlling a tracking varying means corresponding to output obtained by the comparison of mean data with a peak value. CONSTITUTION:A reproducing envelope signal obtained from a rotary head 8 or 9 is amplified at an amplifier circuit 14 or 16. And the envelope of a video signal reproduced at a detection circuit 15 or 17 is detected, and the envelope is sampled for several times with a constant cycle with the head switching signal. The mean of the data obtained by sampling is taken, and also, the peak value is detected from the mean data. The reference phase of the tracking varying means 32 is shifted by a prescribed quantity in a plus or minus direction corresponding to comparison output obtained by the comparison of the mean data with the peak value. when the mean data goes less than a prescribed threshold value, the reference phase is returned by the prescribed quantity in a reverse direction, and the optimum tracking position can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to tracking control in a magnetic recording and reproducing device, and in particular provides a device that easily realizes an auto-tracking function at low cost using a microprocessor.

BACKGROUND OF THE INVENTION In recent years, microprocessors have become widespread and are now being used in many household electrical products. Home video table recorder (hereinafter abbreviated as VTR).

) is no exception, and microprocessors are actively used at the center of the system, such as controlling the loading mechanism that pulls the magnetic tape out of the cassette and winding it around the rotating head, and the program reservation system that combines 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 used. have relied on specialized hardware.

FIG. 8 is a block diagram showing the configuration of a servo mechanism during playback of a conventional VTR. A cylinder motor 2 that drives a rotating head 8, 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 a first frequency generator 3 that detects the rotational speed of the cylinder motor 2. A first frequency discriminator (CCYL SC) 40 detects an error in the output signal of the generator 3 with respect to the reference period, and a rotational phase signal obtained from the phase detector 4 and a reference signal generator (R
EF) 42, and a first phase comparator (CYL SC) 41 for detecting a phase error with respect to the reproduction reference signal obtained from the EF) 42, and a phase error output of the first phase comparator 41 and a first frequency discrimination. The speed error output of the adder 40 is added to the l-th adder 43.
After mixing and amplifying by the first amplifier 44, the cylinder motor 2 is driven through the first drive circuit (D R 1 >12).

Also, a capstan motor 6 that runs the magnetic tape 1 at a constant speed, a second frequency generator 7 that detects the rotational speed of the capstan motor 6, and a control signal recorded on the lower end of the magnetic tape 1 are detected. a second frequency discriminator (CAP) that detects an error with respect to the reference period of the output signal of the second frequency generator 7
SC) 45, a tracking mono multi circuit (TRMM) 4B whose delay time is changed by a variable resistor 50 triggered by the output signal of the reference signal generator 42, and a parallel control signal obtained from the control head 5 and a tracking mono multi circuit 46. a second phase comparator (GAPPC) 47 that detects a phase error with the output signal of
A second adder 48 mixes the phase error output of the second phase comparator 47 and the speed error output of the second frequency discriminator 45,
After increasing with the second amplifier 49, the second drive circuit (D
The capstan motor 6 is driven through the R 2 ) 13.

The operation of the VTR configured as described above will be briefly explained using the configuration diagram shown in FIG. 8 and the timing chart of the main parts shown in FIG.

FIG. 9(a) shows the output waveform of the reference signal generator 42 of FIG. This signal is supplied as a reference signal during reproduction to the first phase comparator 4l and the tracking monomulti circuit 46 in FIG.

The trapezoidal wave signal in FIG. 9(b) is an internal waveform of the first phase comparator 41, and is the phase reference signal of the cylinder motor triggered by the leading edge in FIG. 9(a).

FIG. 9(C) is a rotational phase signal obtained from the phase detector 4 of FIG. 8. The trailing edge in FIG. 9(C) samples FIG. 9(b). The hold signal (not shown) and the first frequency discriminator 40 of FIG.
The resulting speed error signals are mixed in a first adder 43 and supplied to the first drive circuit 12 via a first amplifier 44. Therefore, the cylinder motor, that is, the rotary head 8 rotates in phase synchronization with the reference signal shown in FIG. 9(a).

FIG. 9(d) is a charging/discharging waveform of a capacitor (not shown) in the tracking monomulti circuit 4e of FIG.
The leading edge shown in FIG. 9(a) causes a Change the time constant with the variable resistor 50 in Figure 8! This allows the delay time to be changed.

FIG. 9(e) shows the output waveform of the tracking monomulti circuit 46. FIG.

The trapezoidal wave signal in FIG. 9(f) is the internal waveform of the second phase comparator 47 in FIG. 8, and is the phase reference signal of the capstan motor triggered by the trailing edge in FIG. 9(e). It is.

FIG. 9(g) shows a reproduction control signal obtained from the control head 6 of FIG. FIG. 9(f) is sampled by the leading edge of FIG. 9(g). The hold signal (not shown) and the speed error signal obtained from the second frequency discriminator 45 in FIG. 13. Therefore, the capstan motor 6 uses a ninth signal which is phase-shifted from the reference signal shown in FIG. 9(a).
It rotates in phase synchronization with the output signal of the tracking monomulti circuit 46 shown in FIG. 4(e).

As described above, by synchronizing the phases of the rotary head 8 and the reproduction control signal (FIG. 9(g)) during VTR reproduction, the rotary head 8 can best run on the tracks recorded on the magnetic tape 1. Become.

Problems to be Solved by the Invention The variable resistor 50 may be a fixed resistor as long as the formats of the tracks recorded on the magnetic tape are compatible, but if the tape expands or contracts due to environmental changes such as temperature changes or mechanical errors occur, the variable resistor 50 may be a fixed resistor. When playing back a tape recorded on a VTR in which noise has occurred, noise may appear on the screen due to tracking deviation.

Therefore, tracking adjustment is required. Tracking adjustment is performed using the variable resistor 50 shown in FIG. Further, the variable resistor 50 needs to be a volume with a click point in order to be open to the user and easy to use.

Therefore, in the conventional VTR, a tracking adjustment volume is required for tracking adjustment, and there is a need for improvement in operability, that is, usability.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording and reproducing apparatus of the present invention provides a head switching signal of a rotary head and a head switching signal of a rotary head when reproducing a magnetic tape on which a video signal and a control signal are recorded. an error detection means for detecting an error of a phase difference with a control signal with respect to a reference phase; a control means for controlling rotation of the magnetic tape running motor based on an error signal detected by the error detection means; tracking variable means for changing the phase; sampling means for sampling the envelope of the reproduced video signal multiple times at a constant phase with the head switching signal; and calculation means for averaging the plurality of sampling data obtained by the sampling means. and a first detection means for detecting a peak value from the average zit obtained by the arithmetic means each time the reference phase is changed by the variable tracking means with the reference phase as a starting point; a first selection means for selecting a sampling point;
a second detection means for detecting that the average data obtained when changing the reference phase from the sampling point obtained by the first selection means has become equal to or less than a predetermined threshold; a second selection means for selecting the sampling point detected by the means; a third selection means for selecting either the first selection means or the second selection means according to the tape playback speed; data storage means for taking in the reference phase for the sampling point obtained by the selection means; and sending means for sending the reference phase stored in the data storage means to the tracking variable means as the final reference phase. .

Effect of the Invention With the above-described configuration, the present invention samples the envelope detected from the reproduced video signal multiple times at a constant phase with the head switching signal, averages the data obtained by the sampling, and compares the average data with the peak value. The auto-tracking function is realized by controlling the tracking variable means according to the output obtained by the above.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a VTR having an auto-tracking function in one embodiment of the present invention.

A cylinder motor 2 that drives two pairs of rotary heads 8 and 9 that record and reproduce video and audio signals, respectively, a capstan motor 6 that runs the tape 1 at a constant speed, and these 2.
a microprocessor 10 that controls two motors and realizes an auto-tracking function, and a first drive circuit ( DRI) 12, a second drive circuit (DR2) 13 that drives the capstan motor 6 by a signal output from the microprocessor 10 via the second analog signal output terminal 28, and amplifier circuits 14 and 16 that amplify the reproduced envelope signals, respectively, and a detection circuit (ENV DETI, EN) that performs heat detection on the amplified reproduced envelope signals.
VDET2) 15.17, the output of the detection circuit 15 is output when the audio signal is not recorded or the level of the audio signal is below a certain value, and the output of the detection circuit 17 is output when the audio signal is recorded. Switch circuit 18 for selecting output
The output of the switch circuit 18 is converted to an AD converter (ADC).
) 19, is AD converted, and is input via the analog signal input terminal group 26 of the microprocessor io.

A first frequency generator 3 connected to the cylinder motor 2 is connected to the input terminals 21 to 24 of the microprocessor 10.
and a second frequency generator 7 which is connected to the first phase detector 4, the control head 5 and the capstan motor 6.

The inside of the microprocessor IO consists of a register (REG) 100tiJ for storing data, a random access memory (indicated by the abbreviation RAM in the figure, hereinafter abbreviated as RAM) 200, and digital data. A 16-bit arithmetic unit (indicated by the abbreviation ALU in the figure) that executes arithmetic and logical operations.
It is abbreviated as ALU. ) 300 and instructions to be executed sequentially, and based on the instructions, the register 100, RAM 200, and ALU 30 are stored via the control bus 450.
an instruction execution circuit (indicated by the abbreviation PLA in the figure) 400 that controls the operation of 0, and a 17-bit time base counter (indicated by the abbreviation PLA in the figure) that counts down the reference clock signal applied to the clock terminal 20. In the figure, the time base counter 50 is indicated by the abbreviation TBC.
Count data of 0 is supplied, and the output data is sent to register 100. It is connected to a capture register block (indicated by the abbreviation CAP REG in the figure) 700 that sends data to a data path 600 connected to the RAM 200 and ALU 300, and the first to fourth input terminals 21 to 24, A capture controller (in the figure, C
It is designated by the abbreviation APTR CTRL. )80
It is equipped with 0.

Further, the reference clock signal applied to the clock terminal 20 is supplied to the instruction execution circuit 400 via a timing generator (indicated by the abbreviation TG in the figure), and the data path 600 is provided with a read-only signal. Memory (indicated by the abbreviation ROM in the figure; hereinafter referred to as R
It is abbreviated as OM. )1000. I port
T) 1100, first DA converter (DAC I H 2
0 0. Second DA converter (DAC 2 H 3
0 0. A data latch (LT) 1400 is connected, and furthermore, RAM 200 and RO°M 1000 have address decoders 250 and 1050, respectively.

Note that the capture register block 700 and the capture controller 800 capture count data from the time base counter 500 when an edge of the capture signal arrives, and transmit the result to the ALU 300 or the register 10 according to a specific instruction from the instruction execution circuit 400.
0 or a capture circuit for sending data to the RAM 200.

The operation of the VTR having the auto-tracking function configured as above will be explained.

FIG. 2 shows a control means for operating the capstan motor 6 by processing count data obtained when the leading edge of the control signal recorded on the magnetic tape 1 arrives as running phase detection data of the magnetic tape 1;
In other words, the phase control during regeneration of the capstan motor 8 is
2 is a flowchart showing an example realized by a program built into the microprocessor 10 shown in the figure.

Regarding the flowchart in Figure 2, the conventional VT in Figure 9
This will be explained with reference to the operation waveform diagram of R.

Processing blocks 451, 453 and branch 452 in FIG.
A reference signal for VTR playback, that is, a signal corresponding to FIG. 9(a) is created by 453, and REF and TRM in the processing block 453 are constants, and are determined by the repetition period of the reference signal and the tracking thick amount, respectively. is the central value of
Memory 1 contains the count value corresponding to the leading edge of the next reference signal, that is, the time corresponding to the leading edge in Figure 9 (a), and Memory 2 contains the tracking thick amount, that is, the trailing value in Figure 9 (e). The time corresponding to the edge is written.

As will be explained in detail later, the amount of change in the tracking thick amount from the center value is written in the memory 3 for the auto-tracking function.

Processing blocks 454 and 456 and branch 455 then generate the capstan motor phase reference signal, ie, FIG.
A trapezoidal wave signal corresponding to f) is created, and processing block 454 and branch 455 check whether the count value of time base counter 500 in FIG. 1 does not exceed the tracking thick amount written in memory 2. If the NL flag is exceeded, the NL flag for checking whether or not the reproduction control signal has arrived is reset (indicating that the reproduction control signal has not arrived) in processing block 456.
A count value corresponding to the boundary point between the high level (hereinafter abbreviated as H level) period and the slope section of the trapezoidal wave signal shown in FIG. 3(f) is written. Therefore, TPZ in processing block 456 is a constant corresponding to the H level period.

Next, in branch 457, it is determined whether a reproduction control signal has arrived. This indicates that the capture controller 800 has transferred the count value of the time base counter 500 to the capture register block 700 at the leading edge of the playback control signal applied to the third input terminal 23 of the microprocessor 10 in FIG. This can be executed by determining whether or not the CTL flag is set. If the CTL flag is set. ↓ If so, the process proceeds to processing block 458, where the accumulator (hereinafter referred to as
It is abbreviated as 800. ), the count value latched in the register file, that is, the capture register block 700 in FIG. 1, is transferred to the memory 5.

After determining the NL flag in branch 459, processing block 460 and branch 461 determine that the time when the control signal written in memory 4 arrives, that is, the H level section in FIG. 9(f), is the slope section. It is determined whether it is earlier than the boundary point. If yes, proceed to processing block 463 and set Acc to a value corresponding to the H level in FIG. 9(f); if no, processing block 462
Proceed to.

Processing block 462 and branch 464 determine whether the arrival time of the control signal has passed the slope section shown in FIG. 9(f). K in processing block 462
EISHA is a count value (constant) corresponding to the slope section in FIG. 9(f). If the inclination section has been passed, the process proceeds to processing block 465 and the Acc is changed to FIG. 9(f).
The low level of the trapezoidal wave signal (hereinafter abbreviated as L level).

). Then, by processing blocks 469 and 470, a value corresponding to the phase error left in Acc is written into the memory 6, and the NL flag is set. If the control signal has not arrived in branch 457, that is, if the CTL flag is not set, processing block 466 and branch 467 change the count value of time base counter 500 to the slope interval and L of FIG. 9(f). It is determined whether the time corresponding to the boundary point of the level interval has passed, and if yes, a value corresponding to the L level in FIG. 9(f) is set to Acc in processing block 468, and processing block 469 move on.

As described above, the phase control of the cab stan motor 6 is performed.

Next, the auto-tracking operation will be explained using the flowchart of FIG. 3 and the operation waveform diagram of FIG. 4.

FIG. 3 shows a signal obtained by amplifying the reproduced envelope signal obtained from the rotary head 8 or 9 in FIG.
The microprocessor 1 shown in FIG.
2 is a flowchart showing an example realized by a program built into 0.

FIG. 4(a) shows a head switching signal for a pair of rotary heads 8 or 9 attached to a cylinder motor. FIG. 4(b) shows a reproduced envelope signal obtained from the rotary head 8 or 9. FIG. 4(C) shows a signal obtained by peak-detecting the signal shown in FIG. 4(b) by the detection circuit 15 or 17 of FIG. 1. That is, the signal shown in FIG. 4(c) is input to the AD converter 19 of FIG.

Branches 401, 405, and 410 in FIG. 3 are processes for branching the flow according to the value of the state variable A set in the RAM, that is, the memory.

first,. When A=O, the process proceeds to processing block 402 via branch 401, and a head switching signal (see FIG. 4(a)) inputted to I port 1100 in FIG.
After the signal level of the signal (abbreviated as W signal) is taken into Acc, it is detected that the HSW signal is at the L level, and the processing block 404 sets the state variable A to 1.

When A=1, processing block 4 is executed by branch 405.
06, the signal level of the HSW signal is loaded into Acc, the leading edge of the HSW signal is detected in branch 407, and the process proceeds to processing block 408, which takes approximately 8 ms.
Set a timer to detect the end. This is because, as can be seen from the envelope signal shown in Figure 4(b), the envelope signal output obtained from the rotating head is not constant due to variations in the head, non-linearity of the recording track, etc. This is to ensure that the comparison point is always at the same position, that is, approximately 8 ms after the leading edge of the HSW signal. Regarding the timer set, the time base counter 500 in FIG.
This can be achieved by using a soft counter based on the number of times a specific instruction in the program is passed.

Next, proceeding to processing block 409, state variable A is set to 2.

When A=2, branch 410 causes branch 411
Then, it is determined whether the timer set when A=1 has completed counting. If yes, branch 41
Proceeding to step 2, it is determined whether the state variable AVC is O. When AVC=0, as explained in FIGS. 3 and 4, the signal (fourth
(see figure (C)) is transferred from the register file to memory A (processing block 4 1 3), setting the state variable AVC to 1 (processing block 414), and resetting A (processing block 422). ). When AVC≠O, it is determined in branch 415 whether AVC=1. When AVC=1, the AD conversion value is transferred from the register file to memory B (processing block 416), and the state variable AVC is set to 2 (processing block 417).
Reset A (processing block 422). AVC≠1
At this time, it is determined in branch 418 whether AMC=2. When AMC=2, processing block 419 adds memory A and memory B, and stores the divided data in memory 7. Next, at processing block 420, the ADC
Set the flag. This flag is set every time data is stored in the memory 7, and reset when data is transferred from the memory 7. In other words, memories A and B
Approximately 8ms after the leading edge of the HSW signal (
The data of the register files R1 and R2) in FIG. 4 have been taken in, and the average value of memory A and memory B will be stored in memory 7. The reason for taking the average is to minimize errors and variations due to noise.

By repeating the above flow, the average value of the amplitude level of the envelope signal after a certain period of time from the leading edge of the HSW signal can always be taken into the memory. Furthermore, the average number of times can be increased by adding the state variable AVC and memory and performing the same processing as when AVC=O.

Next, the optimum tracking position will be explained using the characteristic diagram shown in FIG. 5 showing the amplitude level of the envelope signal.

FIG. 5 is a characteristic diagram showing the relationship between the tracking thick amount and the amplitude level of the playback bellows when the tracking amount is changed during playback of a standard recording tape and a triple recording tape.

In the case of a standard recording tape, the amplitude level of the reproduction envelope has a peak value as shown in FIG. 5(a), and the video signal SN ratio similarly has a peak value in the peak value. Furthermore, since the image quality is optimal at the point where the SN ratio is maximum, the optimal tracking position can be obtained by detecting the peak value.

In the case of 3x recording tape, the track width is narrower than that of standard recording tape, but since both use heads of the same width, the amplitude level of the playback envelope has a flat part as shown in Figure 5 (b). waveform. In addition, image quality and SN
Considering the ratio, the point where the waveform in FIG. 5(b) begins to become flat is the optimal tracking position.

From the above explanation, it is best to search for the point where the amplitude level of the envelope signal reaches its peak value for standard recording tapes, and the point where the amplitude level of the envelope signal becomes below the threshold value for the first time from the peak value for triple recording tapes. Tracking position can be detected.

Hereinafter, a method of searching for the optimal tracking position will be explained with reference to a flowchart of automatic tracking in FIG. 6.

First, branch 501 determines whether or not auto-tracking is being executed. If not, proceed to branch 502; if yes, proceed to branch 505.

In branch 502, it is determined whether the VTR is in recording mode or reproduction mode. Go to branch 503 in playback mode and select the first
It is determined whether the first switch circuit 31 shown in the figure has been pressed by the user. If yes (if the switch is on), the process advances to processing block 504, sets variables Di and D2 set in memory to 6 and 3, respectively, clears memory 6, and stores memory 3 (tracking thick amount). ni f
The iX value (value corresponding to the tracking position and reference phase during recording) is set, and the process proceeds to branch 505.

Further, if no in branch 502 and branch 503, the program moves to the next program.

Next, depending on the value of state variable B, branches 505 and 512
, 521, 535, and 545, the flow is branched.

First, when state variable B is O, processing proceeds to processing block 50B via branch 505, where variable D1 is decremented, and then, at branch 507, it is determined whether variable D1 is 0 or not.

That is, using variable D1, processing blocks 504 and 50
6 and branch 507 implement a soft 1 timer, which delays the time required for the program to pass through processing block 506 eight times. This is because it takes time for the cab stan motor 6 of FIG. 1 to complete phase pull-in after the tracking shifter amount is set in processing block 504.

After a certain period of time, the process proceeds to processing block 508, and in processing block 412 of the flow shown in FIG.
and then stored in the memory 6 again. Next, the process proceeds to processing block 509, in which a value corresponding to the tracking amount +lms is added to the data in the memory 3 described in the explanation of FIG. 2 in order to shift the tracking thick amount by +lms.

Note that the variable range of the tracking thick amount is ±10 ms. In branch 510, it is determined whether the tracking thick amount exceeds +10 ms, and if yes, the tracking shifter amount is set to +10 ms, and branch 53
Go to 1. If not, the process proceeds to processing block 511, where state variable B is set to 1.

When state variable B is 1, the process proceeds to processing block 513 via branch 512, where variable D2 is decremented, and then whether variable D2 is O is determined at branch 514. A soft timer is configured using variable D2. After a certain period of time, the process proceeds to processing block 515, where variable D2 is set to 6. Next, in branch 516, the memory 6 stores the amplitude level of the envelope signal when the tracking shifter amount is set to the fix value, and the memory 6 stores the amplitude level of the envelope signal when the tracking thick amount is shifted by +lms. I am comparing it with 7. As a result, if the memory 6 is larger, the process advances to branch 517, and if the memory 7 is larger, the process returns to processing block 509 and shifts the tracking thick amount by +1 ms. In branch 517, it is determined whether the number of passes is the first time. If yes, proceed to processing block 519;
The tracking thick amount is shifted by -2 ms, and state variable B is set to 2 in processing block 520. If not, it means that a peak value has been detected, and the process proceeds to processing block 518 to set the optimum tracking position, shifts the tracking shifter amount by -1 ms, and proceeds to branch 531.

That is, state variable B is 0. 1, the tracking shifter amount searches for the peak value of the amplitude level of the envelope signal in 100,000 directions around the fix value. In addition, in the process where the state variable B is 2, the tracking thick amount searches for the peak value of the amplitude level of the envelope signal in the minus (one) direction centering on the fix value.

If state variable B is 2, branch 521 leads to processing block 522 . Processing block 522 and branch 5
In step 23, a soft timer is configured using the variable D2, and is delayed for a certain period of time. After a certain period of time, variable D2 is set to 6 in processing block 524, and the process proceeds to branch 525. Here, the amplitude levels of the envelope signals (memories 8 and 7) before and after changing the tracking thick amount are compared. If memory 8 is larger, processing block 5
26, the tracking shifter amount is shifted by +1 mS, and the process proceeds to branch 531. If the memory 7 is larger, the process advances to processing block 527 and the data in the memory 7 is stored in the memory 6. Here, the peak value will be stored in the memory 6.

Next, in processing block 528, the tracking thick amount is shifted by 1'''fm s'', and in branch 529, it is determined whether the tracking thick amount is -10 ms or less.

If yes, processing block 530 sets the tracking thick amount to −
10 ms and proceeds to branch 531. If not, the process returns to processing block 520, sets state variable B to 2, and repeats the above process when state variable B is 2.

In branch 531, it is determined whether flag 2 is on or off. Flag 2 is used in triple recording mode processing and is a forced termination flag for auto tracking operation. When the standard recording mode is selected, flag 2 is always in the OFF state, and the recording mode is determined in branch 532, and processing block 5 is executed.
At step 34, flag 1 is turned off, state variable B is set to O, and the auto-tracking operation is completed. When the 3x recording mode is selected, the process advances to processing block 533 and state variable B is set to 3.

In the above standard recording mode, state variable B is 0, 1, 2.
The auto-tracking operation is completed by the above processing.

However, in the triple recording mode, the auto-tracking operation cannot be performed accurately with only the above processing, so the processing described below is further performed.

When state variable B is 3, branch 535 advances to processing block 536, where variables Di and D2 are set to 6 and 3, respectively.
Set. Next, in branch 537, it is determined whether the peak value of the amplitude level of the envelope signal is approximately 1.9V or less.

If not, processing block 542 sets the tracking shifter amount to f.
ix value by -8 ms, processing block 543 sets flag 2, and processing block 544 sets state variable B.
Set it to O and try peak detection again. Note that flag 2 is 3
Turn on to shift the tracking thick amount by -8 ms and search for the peak value again when the optimal tracking position is not searched by the automatic tracking operation in the double recording mode. Also, if it is true in branch 537, the tracking thick amount is increased by +1 in processing block 538.
ms shift, and in branch 539 it is determined whether the tracking thick amount exceeds +10 ms. If yes, proceed to processing block 542.

If not, state variable B is set to 4 in processing block 540. If state variable B is 4, processing proceeds to processing block 546 via branch 545, and in conjunction with branch 547, a soft timer is constructed using variable D2 and delayed for a certain period of time. There is.

After a certain period of time, the process proceeds to branch 548 and compares the threshold value with the memory 7 in which data of the amplitude level of the envelope signal after shifting the tracking thick amount is stored. When the former is large, it means that the optimal tracking position in triple recording mode has been searched.

The tracking thick amount is shifted by -1 ms and the process proceeds to processing block 534 to complete the auto-tracking operation. If the latter is larger, the process proceeds to processing block 533;
Repeat the operation when state variable B is 3.

Note that the threshold value here is set to 90% of the peak value.

The size of the threshold affects the setting accuracy, and if the threshold is large, the flat part on the right side of the amplitude level characteristic of the envelope signal in FIG. If is small, the settling position will vary due to the slope of the slope on the left side of the characteristic. Thresholds are set taking these into account. Further, a value obtained by subtracting a certain value from the peak value can also be set as the threshold value.

Through the above flow, the tracking thick amount is changed from the fixed value in the plus (+) and minus (-) directions by 1 ms, and the amplitude level of the reproduction envelope is compared each time, and the peak value of the amplitude level of the reproduction envelope and the The tracking thick amount at that time is detected, and when the tape recording mode is the standard recording mode, the tracking thick amount becomes the optimal tracking position. In the 3x recording mode, the tracking shift amount is shifted by +lms each time the amplitude level of the envelope signal is compared with the threshold value, and when the former becomes smaller than the latter, the tracking shift amount is determined. -1
The value shifted by ms becomes the optimal tracking position.

However, if the amplitude level of the mechanical rope signal does not become smaller than the threshold even if the tracking shifter amount exceeds +10ms in operation in the 3x recording mode, the tracking shifter amount is shifted by -8ms from the fix value. is set, peak detection is performed, and the tracking thick amount that becomes the peak value is set as the final tracking thick amount.

Further, FIG. 7 is a flowchart in which a manual tracking operation is realized by the three-position switch 32 of FIG. 1. The operation will be explained below.

Branch 900 determines whether switch 32 is on or off. If switch 32 is on, processing block 9
01, the soft counter TC is decremented, and a branch 902 determines whether TC=O. When TC=O, TC is set to 10 and it is determined whether the output of the switch 32 is at H level (branch 902). 904).H
If the level is the tracking thick amount, that is, data equivalent to 100 μs is added to the memory 3 (branch 905),
If it is L level, subtract that amount (branch 906)
.

That is, by operating the switch 32, tracking adjustment can be performed manually.

Effects of the Invention As is clear from the above description, the magnetic recording and reproducing device having the auto-tracking function of the present invention detects the envelope of the reproduced video signal, and samples the envelope multiple times at a constant period with the head switching signal. , average the data obtained by sampling, detect the peak value from the average data, and add (+) the reference phase of the tracking variable means according to the comparison output obtained by comparing the average data and the peak value. or minus (-)
When the average data falls below a predetermined threshold (approximately 90% of the peak value), the reference phase is moved back in the opposite direction by a predetermined amount to reach the optimal tracking position, so temperature changes, etc. There is no need for manual tracking adjustment, even for tapes that have expanded or contracted due to environmental changes, or for tapes recorded with a VTR that has mechanical errors, and there is no need for a tracking adjustment volume, so you can avoid accidentally shifting the tracking. There is no need to store the magnetic recording/reproducing device, and a magnetic recording/reproducing device with improved operability that realizes a high-performance auto-tracking function can be obtained, which has a great effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic recording and reproducing device having an auto-tracking function according to an embodiment of the present invention, and FIGS. 2, 3, and 6 are flow charts showing the operation of the main parts of FIG. 1. , FIG. 4 is a timing chart for explaining the flowchart in FIG. 3, FIG. 5 is a characteristic diagram showing the relationship between the tracking thick amount and the reproduced envelope signal level during playback of a standard recording tape and a triple-speed recording tape. FIG. 7 is a flowchart showing the operation of the means for realizing manual tracking, FIG. 8 is a block diagram showing the configuration of the servo mechanism during playback of a conventional VTR, and FIG. 9 explains the operation of the main parts of FIG. 8. This is a timing chart for 1...Magnetic tape, 2...Cylinder motor, 6
...capstan motor, 19...AD converter, 100...register, 200...RAM.
300...ALU, 400...Instruction execution means, 500...Time base counter, 7
00...Capture register controller, 80
0...Capture controller, 1000...
・ROM, 1400...Latch.

Claims (1)

[Scope of Claims] Error detection means for detecting an error with respect to a reference phase in a phase difference between a head switching signal of a rotary head and the reproduced control signal when reproducing a magnetic tape on which a video signal and a control signal are recorded. , control means for controlling the rotation of the magnetic tape running motor based on the error signal detected by the error detection means; tracking variable means for changing the reference phase; sampling means for sampling a plurality of times at a constant phase with the head switching signal; arithmetic means for averaging a plurality of sampling data obtained by the sampling means; a first detection means for detecting a peak value from the average data obtained by the arithmetic means; a first selection means for selecting a sampling point detected by the first detection means; and a first selection means for selecting a sampling point detected by the first detection means. a second detection means for detecting that the average data obtained when changing the reference phase from the sampling point obtained by the sampling point has become less than a predetermined threshold; and the sampling detected by the second detection means. a second selection means for selecting a point; a third selection means for selecting either the first selection means or the second selection means according to the tape playback speed; and a point obtained by the third selection means. A magnetic recording/reproducing device comprising: a data storage means for taking in a reference phase for a sampled point; and a sending means for sending the reference phase stored in the data storage means as a final reference phase to the variable tracking means.