JPH0246559A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To detect an optimum tracking position by searching a point where an amplitude level of an envelope signal becomes a peak value or below in the case of a standard picture recording tape and a point where an amplitude level of an envelope signal becomes smaller than a threshold level for the first time from a peak value in the case of a three times picture recording tape. CONSTITUTION:The amplitude levels of a reproducing envelope generated every time a tracking shifter amt. is varied by 1ms in the positive and negative directions respectively from a fixed value is compared with each other, and the peak value of the amplitude level of the reproducing envelope and the tracking shifter amt. at that time are detected, and when the picture recording mode of a tape is the standard picture mode, this tracking shifter amt. is regarded as the optimum tracking position. In the case of three times picture recording mode tracking shifter amt. is shifted by + 1ms, and the amplitude level of the envelope signal is compared with the threshold level every time the shift is performed, and when the former becomes smaller than the latter, a value obtained by shifting the tracking shifter amt. at this time by - 1ms is regarded as the optimum tracking position. Consequently, an autotracking function can be realized without needing a tracking adjustment volume.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a magnetic recording and reproducing device having an auto-tracking function, and in particular provides a device that can be easily realized 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 appliances. Home video tape 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 cylinder motors that drive a single-rotation head and capstan motors that run a magnetic tape at a constant speed require complex judgment operations and rapid processing of detection signals, so microprocessors are not used. have relied on specialized hardware.

FIG. 2 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 The first one detects the error with respect to the reference period of the output signal of machine 3.
a frequency discriminator 40, and a first phase comparator 41 that detects a phase error between the rotational phase signal obtained from the phase detector 4 and the reproduced reference signal obtained from the reference signal generator 42. 1 on the phase error output of the phase comparator 41.
The speed error output of the frequency discriminator 40 and the first adder 4
3 and amplified by the first amplifier 44,
The cylinder motor 2 is driven through a first drive circuit 12.

a capstan motor 6 that runs the magnetic tape at a constant speed;
A second frequency generator 7 detects the rotational speed of the capstan motor 6, and a control head 5 detects the control signal recorded on the lower end of the magnetic tape 1.
, a second frequency discriminator 45 that detects an error in the output signal of the second frequency generator 7 with respect to the reference period, and a variable resistor 50 that is triggered by the output signal of the reference signal generator 42.
A tracking mono multi-circuit 46 whose delay time changes according to The phase error output of the second phase comparator 47 and the speed error output of the second frequency discriminator 45 are mixed by the second adder 48 and amplified by the second amplifier 49, and then the second drive circuit 13
The capstan motor 6 is driven through the capstan motor 6.

The operation of the VTR constructed as described above will be briefly explained using the configuration diagram shown in FIG. 2 and the timing chart of the main parts shown in FIG.

FIG. 3(a) shows the output waveform of the reference signal generator 42 of FIG. This signal is used as a reference signal during reproduction by the first phase comparator 41 and the tracking monomulti circuit 4 in FIG.
6.

The trapezoidal wave signal in FIG. 3(b) is the internal waveform of the first phase comparator 41, and is the phase reference signal of the cylinder motor triggered at the leading edge of FIG. 3(a).

FIG. 3(c) shows a rotational phase signal obtained from the phase detector 4 of FIG. The trailing edge in FIG. 3(C) samples FIG. 3(b). The hold signal (not shown) and the speed error signal obtained from the first frequency discriminator 40 of FIG. is supplied to circuit 12. Therefore, the cylinder motor 11 rotates the head 8 in phase synchronization with the reference signal shown in FIG. 3(a).

Figure 3(d) shows the tracking monomulti circuit 4 in Figure 2.
This is a charging/discharging waveform of a capacitor (not shown) in FIG. 3(a), and is triggered by the leading edge of FIG. 3(a).

By changing the time constant using the variable resistor 50 shown in FIG. 2, the delay time can be changed.

FIG. 3(e) shows the output waveform of the tracking monomulti circuit 46.

The trapezoidal wave signal in FIG. 3(f) is the internal waveform of the second phase comparator 47 in FIG. 12, and is the phase reference signal of the capstan motor triggered by the trailing edge in FIG. 3(e). It is.

FIG. 3(g) shows a reproduction control signal obtained from the control head 5 of FIG. Sample FIG. 3(f) with the leading edge of FIG. 3(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 is operated as shown in FIG.
It rotates in phase synchronization with the output signal of the tracking monomulti circuit 46 in e).

As described above, by synchronizing the phases of the rotary head 8 and the reproduction control signal (FIG. 3(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. In addition, this variable resistor needs to be a volume with a click point to make it open to the user and easy to use.

Therefore, conventional VTRs require a tracking adjustment volume, and there is also a need for improvement in operability, that is, usability.

In view of the above problems, an object of the present invention is to provide a magnetic recording and reproducing device that realizes an auto-tracking function that does not require a tracking adjustment volume and is easy to use.
This is the first objective.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording and reproducing apparatus of the present invention includes a magnetic recording and reproducing apparatus in which a video signal is recorded by a rotating head, and
error detection means for detecting an error in phase difference between a head switching signal of the rotary head and a reproduced control signal with respect to a reference phase when reproducing a magnetic tape on which a control signal of a constant period is recorded by a control head;
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; and based on the video signal reproduced from the magnetic tape. sampling means for sampling the signal obtained by the head switching signal at a constant phase with the head switching signal, and each time the reference phase is changed by the tracking variable means using the reference phase as a starting point, the magnitude of the sampling data obtained by the sampling means is compared, and a peak value is obtained. a first detecting means for detecting the first detecting means, a first selecting means for selecting a sampling point that has been successfully detected by the first detecting means, and a reference phase is determined by a tracking variable means from the sampling point obtained by the first selecting means. a second detection means for detecting that the sampling data obtained by the sampling means when the change is made is less than a threshold value obtained from the peak value detected by the first detection means; a second selection means for selecting the sampling point detected by the method; a third selection means for selecting either the first selection means or the second selection means according to the tape playback speed; and a sending means for sending the reference phase stored in the data storage means to the tracking variable means as the final reference phase.

Function: With the above-described configuration, the present invention does not require a tracking adjustment volume and can be used with high performance even for tapes that have expanded or contracted due to environmental changes such as temperature changes, or tapes recorded with other VTRs that have mechanical errors. A magnetic recording and reproducing device that realizes an auto-tracking function can be obtained.

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

FIG. 1 shows a block diagram of a VTR having an auto-tracking function according to an embodiment of the present invention. A cylinder motor 2 drives two pairs of rotary heads 8 and 9 that record and reproduce video and audio signals, respectively, and a capstan motor 6 that runs the tape 1 at a constant speed. A microprocessor 10 and its microprocessor 1
0 through the first analog signal output terminal 27 to drive the cylinder motor 2, and the microprocessor 10 through the second analog signal output terminal 28. A second drive circuit 13 drives the capstan motor 6 by the signal, and an amplifier circuit 14.16 amplifies the reproduced envelope signal 1'J from the rotary head 8.9, and amplifies the amplified -1 and reproduced envelope signal. A detection circuit 15 that detects the peak of
．． 17, and if no audio signal is recorded or the level of the audio signal is below a certain value, the detection circuit 1
A switch circuit 18 selects the output of the detection circuit 17 when an audio signal is recorded, and the output of the switch circuit 18 is input to an AD converter 19.
The signals are AD converted and input via the analog signal input terminal group 26 of the microprocessor 10.

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.

Inside the microprocessor 10, there is a register 100 for storing data and a random access memory (indicated by the abbreviation "RAM" in the figure. Hereinafter, referred to as RAM).
It is abbreviated as ) 200 and a 16-bit arithmetic unit (A in the figure) that executes arithmetic and logical operations on digital data.
It is indicated by the abbreviation LU. Hereinafter, it will be abbreviated as ALU. ) 300 and an instruction execution circuit (indicated by the abbreviation PLA in the figure) that stores instructions to be executed sequentially and controls the operations of the register 100, RAM 200, and ALU 300 via the control bus 450 based on the instructions. ) 400 and clock terminal 20
1 to count down the reference clock signal applied to
A 7-bit time base counter (indicated by the abbreviation TBC in the figure) 500 and a counter bus 55
The count data of the time base counter 500 is supplied through the register 1001, and the output data is sent to the register 1001.
RAM200. A capture register block (indicated by the abbreviation CAPREG in the figure) sends data to the data bus 600 connected to the ALU 300.
700 and the first to fourth input terminals 21.22.23.2
A capture controller (abbreviated as CAPTRCTRL in the figure) transfers the count data of the time base counter 500 to the capture register block 700 when the edge of four types of capture signals, each having a different generation source, arrives. It is shown.

)800.

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) 900, and the data bus 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 boat 1100, 1st
DA converter 1200. Second DA converter 13001
A data latch 1400 is connected, and a RAM
200 and the ROM 1000 each have an address decoder 25011050.

Note that the capture register block 7.00 and the capture controller 800 capture count data from the time base counter 500 when the edge of the capture word arrives, and transmit the result to the ALU 300 or It constitutes a capture circuit that sends data to the register 100 or RAM 200.

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

FIG. 4 shows a control means for operating the capstan motor 6 by processing the count data obtained when the leading edge of the control signal recorded on the magnetic tape arrives as magnetic tape running phase detection data, that is, the capstan motor 6. 2 is a flowchart showing an example in which phase control during reproduction is realized by a program built into the microprocessor 10 of FIG. 1.

Regarding the flowchart in Figure 4, the conventional VTR in Figure 3
This will be explained with reference to the operation waveform diagram.

Processing blocks 451 and 453 and branch 452 in FIG.
A reference signal for VTR playback, that is, a signal corresponding to FIG. is the central value of
Memory 1 stores the count value corresponding to the leading edge of the next reference signal, that is, the leading edge of FIG. 3(a).
A time corresponding to the tracking shift amount, that is, a time corresponding to the trailing edge in FIG. 3(e) is written in the memory 2.

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

Processing blocks 454 and 456 and branch 455 then process the capstan motor phase reference signal, that is, the phase reference signal shown in FIG.
), and processing block 454 and branch 455 check whether the count value of time base counter 500 in FIG. If it exceeds the threshold, the processing block 456 resets the NL flag that checks whether or not the reproduction control signal has arrived (indicating that it has not arrived), and further stores the high level of the trapezoidal wave signal shown in FIG. 3(f) in the memory 4. A count value corresponding to the boundary point between the level (hereinafter abbreviated as H level) period and the slope section is written. Therefore, T in processing block 456
PZ is a constant corresponding to the H level period.

Next, in branch 457, it is determined whether a reproduction control signal has arrived. This means that 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 a CTL flag indicating that the count value of the time base counter 500 has been transferred to 00 is set. If the CTL flag is set, proceed to processing block 458;
The accumulator of register 100 in FIG.
It is abbreviated as c. ) via the register file i.e. the first
The count value latched in the capture register block 700 shown in the figure is transferred to the memory 5.

After determining the NL flag in branch 459,
Processing block 460 and branch 461 cause memory 4
It is determined whether the time at which the control signal written in , that is, the H level section in FIG. 3(f) arrives, is earlier than the boundary point of the slope section. If yes, proceed to processing block 463 and set AcC to a value corresponding to the H level in FIG. 3(f); if not, proceed to processing block 463.
Proceed to step 2.

Processing block 462 and branch 464 determine whether the arrival time of the control signal has passed the slope section shown in FIG. 3(f). The slope in processing block 462 is a count value (constant) corresponding to the slope section of FIG. 3(f). If the slope interval has been exceeded, the process proceeds to processing block 465, where Acc is set to a value corresponding to the low level (hereinafter abbreviated as L level) of the trapezoidal wave signal shown in FIG. 3(f). And then processing block 4E39
．． At step 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 value shown in FIG.
) is determined whether the time corresponding to the boundary point between the slope section and the L level section has passed, and if yes, a value corresponding to the L level in FIG. 3(f) is set in Acc in processing block 468. The process then proceeds to processing block 469.

As described above, the phase of the capstan motor 6 is controlled.

Next, the auto tracking operation is shown in Figures 5 and 8 (
This will be explained using the flowchart of aL(b) and the operation waveform diagram of FIG.

In FIG. 5, the reproduced envelope signal obtained from the rotary head 8 or 9 in FIG.
2 is a flowchart showing an example in which a means for importing digital data AD-converted by a converter 19 into a memory is realized by a program built into the microprocessor 10 of FIG. 1.

FIG. 6(a) shows a head switching signal for a pair of rotary heads 8 or 9 attached to a cylinder motor. FIG. 6(b) shows a reproduced envelope signal obtained from the rotary head 8 or 9. FIG. 6(c) shows a signal obtained by peak-detecting the signal shown in FIG. 6(b) by the detection circuit 15 or 17 of FIG. That is, the signal shown in FIG. 6(C) is input to the AD converter 19 of FIG.

Branches 401, 405, and 410 in FIG. 5 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, where the head switching signal (HS Wl (FIG. 6(a); hereinafter abbreviated as H8W signal) is input to EBO) 1100 in FIG. After the level is taken into Acc, it is detected that the H8W signal is at the L level, and the processing block 404 sets the state variable A to 1.

When A=1, processing block 40 is executed by branch 405.
The process proceeds to E3, the signal level of the H8W signal is loaded into Acc, the leading edge of the H8W signal is detected in branch 407, and the process proceeds to processing block 408, where approximately 8
Set a timer to detect after ms. This is the 6th
As can be seen from the envelope signal shown in Figure (b), the envelope signal output obtained from the rotating head is not constant due to variations in the head and non-linearity of the recording track. This is to always keep it at the same position, that is, approximately 8 ms after the leading edge of the H8W signal. Regarding the timer set, use the time base counter 500 in Fig. 1.
This can be achieved by using a soft counter that determines how many times a specific instruction in the program is passed.

Processing then proceeds to block 409 where state variable A is set to 2.

When A=2, the process proceeds from branch 410 to branch 411, and it is determined whether the timer set when A=1 has completed counting. If yes, processing block 4
Proceeding to step 12, as explained in FIGS. 5 and 6, the AD conversion value of the peak-detected signal (FIG. 6(C)) of the reproduced envelope signal is transferred from the register file to the memory 7.

In other words, data of the register file approximately 8 ms after the leading edge of the H8W signal (RLR2 in FIG. 6) is taken into the memory 7. Next, in processing block 413, state variable A is reset to O.

By repeating the above flow, the amplitude level of the envelope signal after a certain period of time from the leading edge of the H8W signal can always be captured in the memory.

Next, the optimal tracking position will be explained using the graph shown in FIG. 7 showing the amplitude level of the envelope signal.

FIG. 7 is a graph showing the relationship between the tracking shifter amount and the amplitude level of the reproduction envelope when the tracking amount is changed during reproduction of a standard recording tape and a triple recording tape.

In the case of a standard recording tape, the amplitude level of the playback envelope has a peak value as shown in FIG. 7(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 a 3x recording tape, the track width is narrower than that of a 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 7(b). waveform. Also, when examining the image quality and SN ratio, the point where the waveform in FIG. 7(b) begins to become flat is the optimal tracking position.

From the above explanation, search for the point where the amplitude level of the envelope signal reaches its peak value for standard recording tape, and search for the point where the envelope signal amplitude = 23- level becomes below the threshold value for the first time from the peak value for triple recording tape. This allows the optimal tracking position to be detected.

Hereinafter, a method of searching for the optimum tracking position will be explained with reference to the auto-tracking flowcharts shown in FIGS. 8(a) and 8(b).

First, branch 501 determines whether or not auto-tracking is being executed. If not, proceed to branch 502; if yes, proceed to branch 505. 1-1 on branch 502
Determine whether the VTR is in recording mode or playback mode.

In the playback mode, the process advances to branch 503, and it is determined whether the first switch circuit 31 of FIG. 1 has been pressed by the user. If yes (if the switch is ON), the process advances to processing block 504, and the variable D1 set in the memory is
Set D2 to 6 and 3, clear the memory 6, set the fix value (value corresponding to the tracking position and reference phase during recording) in the memory 3 (tracking shifter amount), and proceed to branch 505.

Also, 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 505.512.
521.535.545 branches the flow.

First, when state variable B is O, the process proceeds to processing block 506 via branch 505, where variable D1 is decremented, and then, at branch 507, it is determined whether variable D1 is O.

That is, using variable D1, processing block 504.50
6 and branch 507 implement a soft timer, which delays the time required for the program to pass through processing block 506 six times. This is because it takes time for the capstan motor 6 of FIG. 1 to complete phase arching 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 tracking fi+1 ms is added to the data in the memory 3 described in the explanation of FIG. 4 in order to shift the tracking shifter amount by +1 ms.

Note that the variable range of the tracking shifter amount is +10 m5. In branch 510, it is determined whether the tracking shifter amount exceeds +10ms, and if yes, the tracking shifter amount is set to +10m5, 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, at branch 514, it is determined whether variable D2 is O. 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.
Set.

Next, in branch 516, the tracking shifter amount is fi
The memory 6 that stores the amplitude level of the envelope signal when set to the x value and the tracking shifter amount +1
A comparison is made with the memory 7 in which the amplitude level of the envelope signal when shifted by ms is stored. 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 shifter amount by +1 ms. brunch 5
In step 17, it is determined whether the number of passes is the first time.

If yes, the process proceeds to processing block 519, in which the tracking shifter amount is shifted by 12m5, and in processing block 520, the state variable B is set to 2. 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 m5, 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 the child direction with the fix value as the center. In addition, in the process where the state variable B is 2, the tracking shifter amount is f
The peak value of the amplitude level of the envelope signal is searched in one direction around the ix value. When state variable B is 2, branch 521 causes processing to proceed to processing block 522.

A soft timer is constructed using variable D2 in processing block 522 and branch 523-, 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 6 and 7) before and after changing the tracking shifter (2) are compared. If the memory 6 is larger, the process proceeds to processing block 526, where the tracking shifter amount is shifted by +1 ms, and the process proceeds to branch 531.

Also, if the memory 7 is larger, the processing block 527
Then, the data in memory 7 is stored in memory 6. The peak value is now stored in the memory 6.

Next, in processing block 528, the tracking shifter amount is shifted by 1 m5, and in branch 529, it is determined whether the tracking shifter amount is -10 ms or less. If yes, the tracking shifter amount is set to -10 m5 in processing block 530, and the process proceeds to branch 531. If not, processing block 520
Return to , set state variable B to 2, and repeat 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, the state variable B is 011.2.
Auto tracking 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, the process proceeds to processing block 536 via branch 535, and variables Di and D2 are set to 6 and 3, respectively. 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 yes, the tracking shifter amount is shifted by 18 ms from the fix value in processing block 542, flag 2 is set in processing block 543, and processing block 54
In step 4, set the state variable B to 0 and perform peak detection again.

Incidentally, flag 2 is turned on when the optimum tracking position is not searched by the automatic tracking operation in the triple recording mode and the tracking shifter amount is shifted by 18 ms to perform the peak price tag search again. If branch 537 is negative, processing block 538 shifts the tracking shifter amount by +1 ms, and branch 539
It is determined whether the tracking shift amount exceeds +10 ms. If yes, proceed to processing block 542. If not, processing block 540 sets state variable B to 4.

When state variable B is 4, processing proceeds to processing block 546 via branch 545, and a soft timer is constructed using variable D2 along with branch 547 to delay a certain period of time. 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 shifter amount is stored. When the former is large, it means that the optimal tracking position in triple recording mode has been searched.

The tracking shifter amount is shifted by 1 m5 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 value affects the setting accuracy, and if the threshold value is large, the flat part on the right side of the amplitude level waveform of the envelope signal in Figure 7(b) may be affected by noise, and the threshold value may be lowered. If is small, the settling position will vary due to the slope of the slope on the left side of the waveform. We take these into consideration when setting thresholds. 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 shifter amount is changed from the fix value by 1 ms in one direction, and the amplitude level of the playback envelope is compared each time, and the amplitude level of the playback envelope is the peak value and the tracking shift amount at that time. is detected, and when the tape recording mode is the standard recording mode, the tracking shifter amount becomes the optimal tracking position. In 3x recording mode, the tracking shifter amount is shifted by +1 ms, and each time the amplitude level of the envelope signal is compared with the threshold value, when the former becomes smaller than the latter, the tracking thick amount at that time is adjusted. The value shifted by 1 m5 becomes the optimal tracking position.

However, if the amplitude level of the playback envelope does not become smaller than the threshold even if the tracking thick amount exceeds +10ms in operation in 3x recording mode, set the tracking shifter amount to a value shifted by 18m5 from the fix value. Then, peak detection=32- is performed, and the tracking shifter amount that becomes the peak value is set as the final tracking shifter amount.

The second switch circuit 32 in FIG. 1 is a 3-position switch, and when its output is at H level, the data in the memory 3 is changed to 0.5 ms in order to shift the tracking shifter amount by +0.5 ms. Add the value equivalent to 5ms, and if the output is L level, set the tracking shifter amount to -0.
, 0.5m to the data in memory 3 to shift 5ms
Manual tracking is possible by subtracting the value corresponding to s.

Effects of the Invention As is clear from the above description, the magnetic recording/reproducing device having an auto-tracking function of the present invention records a video signal using a rotating head, and a fixed-period control signal records a magnetic recording/reproducing device having an auto-tracking function. 7f of the tape (represented as magnetic tape 1 in the example)
Error detection means (in the embodiment, the error detection means is configured according to the flowchart of FIG. ), and a control means (implemented) for controlling the rotation of the magnetic tape running motor (represented by a capstan motor 6 in the embodiment) based on the error signal detected by the error detection means. In the example, the phase control means is configured according to the flowchart in FIG. 4.)
Tracking variable means for changing the reference phase (in the embodiment, processing blocks 509, 518, 519 in FIG. 8)
．． 528.528.538.542.549 constitute a tracking variable means. ) and a signal based on a video signal (expressed as a reproduction envelope signal in the embodiment) reproduced from the magnetic tape (expressed as a detection signal in the embodiment) as a head switching signal and a localization signal, respectively. Sampling means to sample in phase (
In the embodiment, the sampling means is configured according to the flowchart shown in FIG. ) and a first detection means (in the embodiment, the branch shown in FIG. 8 516 and 525) and a first selection means for selecting the sampling point detected by the first detection means (in the embodiment, it is comprised of processing blocks 518 and 526 and branch 517 in FIG. ), and the sampling data obtained by the sampling means when the reference phase is changed by the tracking variable means from the sampling point obtained by the first selection means is the peak value detected by the first detection means. A second detection means for detecting that the threshold value obtained by A second selection means (in the embodiment, it is constituted by the processing block 549 in FIG. 8), ! - a third selection means (comprised of branch 532 in FIG. 8 in the embodiment) for selecting either the first selection means or the second selection means depending on the tape playback speed; Data storage means (in the embodiment, it is composed of processing blocks 518, 526, and 549 in FIG. 8) that captures the reference phase of the tracking variable means for the sampling point obtained by the selection means; The present invention is characterized by comprising a sending means (in the embodiment, it is composed of processing blocks 509, 518, 526, and 549 in FIG. 8) that sends the obtained reference phase to the tracking means as the final reference phase. It is an operation that achieves high-performance auto-tracking function without the need for tracking adjustment volume, even for tapes that have expanded or contracted due to environmental changes such as temperature changes, or tapes recorded with VTRs that have mechanical errors. A magnetic recording/reproducing device with improved performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording and reproducing apparatus having an auto-tracking function according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a servo mechanism during reproduction of a conventional VTR, and FIG. Timing charts for explaining the operation of the main parts in the figure, Figures 4, 5, and 8 are
A flowchart showing the operation of the main parts of the figure.
FIG. 7, which is a timing chart for explaining the flowchart in the figure, is a graph showing the relationship between the tracking shifter amount and the reproduction envelope signal level during reproduction of a standard recording tape and a triple speed recording tape. 1...Magnetic tape, 2...Cylinder motor, 6
・Capstan motor, 191AD converter, 10
0 ・lz register, 2001RAM, 300
...ALU, 400...Instruction execution means, 50
0: Time base counter, 7oo: Capture register controller, 8ooI: Capture controller, l OOo: RoMl 14oo:
·latch. Name of agent: Patent attorney Shigetaka Awano (1 person) [cl-
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Claims (1)

[Claims] When reproducing a magnetic tape on which a video signal is recorded by a rotary head and a control signal of a constant period is recorded by a control head, a reference phase of a phase difference between a head switching signal of the rotary head and the reproduced control signal. error detection means for detecting an error with respect to the
control means for controlling the rotation of the magnetic tape running motor based on the error signal detected by the error detection means; and tracking variable means for changing the reference phase;
sampling means for sampling a signal based on the video signal reproduced from the magnetic tape at a constant phase with the head switching signal; and the sampling means each time the reference phase is changed by the tracking variable means starting from the reference phase. a first detection means for detecting a peak value by comparing the magnitude of sampling data obtained by the first detection means; a first selection means for selecting a sampling point detected by the first detection means; and the first selection means. When the reference phase is changed by the tracking variable means from the sampling point obtained by the sampling point, the sampling data obtained by the sampling means becomes less than the threshold value obtained from the peak value detected by the first detection means. a second detection means for selecting the sampling point detected by the second detection means; and a second selection means for selecting the sampling point detected by the second detection means; a third selection means for selecting a selection means; and a data storage means for capturing a reference phase of the tracking variable means for the sampling point obtained by the third selection means;
A magnetic recording and reproducing apparatus comprising: sending means for sending the reference phase stored in the data storage means as the final reference phase to the variable tracking means.