JPH03108969A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the operability by starting the tracking operation by a specific automatic tracking means at the time of detecting the reproducing mode by a reproducing mode detecting means. CONSTITUTION:At the time of reproducing a magnetic tape 1 where a video signal is recorded by a rotary head 8 and a control signal having a certain period is recorded, the error of the phase difference between the head switching signal of the rotary head 8 and the reproduced control signal to a reference phase is detected, and rotation of a running motor 6 of the magnetic tape 1 is controlled based on the detected error signal. An automatic tracking means 101 is provided which performs tracking based on information of the signal obtained by a tracking varying means, which changes the reference phase, at the time of reproducing the magnetic tape 1, and the tracking operation is started when the reproducing mode is detected by a reproducing mode detecting means 103. Thus, a tracking adjusting volume is unnecessary to improve the operability.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a magnetic recording/reproducing device having an automatic 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 products. Home video tape recorder (hereinafter abbreviated as VTR).

) is no exception, and microprocessors are actively used at the center of the system to control the loading mechanism and program reservations combined with timers. There is.

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 used. have relied on specialized hardware.

FIG. 9 is a block diagram showing the configuration of a servo mechanism during playback of a conventional VTR. A cylinder motor 2 that drives the rotating head 8, a first frequency generator 3 that detects the rotational speed of the cylinder motor 2, and a cylinder motor 2.
a first frequency discriminator (CYL 5C) 40 that detects an error with respect to the reference period of the output signal of the first frequency generator 3; Rotational phase signal and reference signal generator (RE
It is equipped with a first phase comparator (CYL PG) 41 that detects a phase error with respect to a reproduction reference signal obtained from F > 42, and a first frequency discrimination between the phase error output of the first phase comparator 41 and a first frequency discrimination. The cylinder motor 2 is driven through the first drive circuit (DRl) 12 after being mixed with the speed error output of the converter 40 by a first adder 43 and amplified by a first amplifier 44 .

A capstan motor 6 that runs the magnetic tape 1 at a constant speed, and a second motor that detects the rotational speed of the capstan motor 6.
a frequency generator 7 and a control head 5 that detects the control signal recorded on the lower end of the magnetic tape 1.
and a second frequency discriminator (CAP 5C) that detects an error with respect to the reference period of the output signal of the second frequency generator 7.
) 45, a tracking mono multi circuit 46 (TRMM) whose delay time is changed by a variable resistor 50 triggered by the output signal of the reference signal generator 42, and a control signal obtained from the control head 5 and the tracking mono multi circuit 46. A second phase comparator (CAP PC) 47 that detects a phase error with the output signal,
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 being amplified by the second amplifier 49, the second drive circuit (DR
2) The capstan motor 6 is driven through the motor 13.

The operation of the VTR configured as described above will be briefly explained using the configuration diagram shown in FIG. 9 and the timing chart of the main parts shown in FIG. 10.

FIG. 10(a) shows the output waveform of the reference signal generator 42 of FIG. This signal is supplied to the first phase comparator 41 and the tracking monomulti circuit 46 in FIG. 9 as a reference signal during reproduction.

The trapezoidal wave signal in FIG. 10(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. 10(a).

FIG. 10(C) is a rotational phase signal obtained from the phase detector 4 of FIG. 9. The trailing edge in FIG. 10(C) samples FIG. 10(b). The hold signal (not shown) and the speed error signal obtained from the first frequency discriminator 40 in FIG. circuit 1
2. Therefore, the cylinder motor, that is, the rotary head 8 rotates in phase synchronization with the reference signal shown in FIG. 10(a).

FIG. 10(d) is a charging/discharging waveform of a capacitor (not shown) in the tracking monomulti circuit 46 of FIG.
It is triggered by the leading edge in FIG. 10(a). By changing the time constant using the variable resistor 50 shown in FIG. 9, the delay time can be changed.

FIG. 10(e) shows the output waveform of the tracking monomulti circuit 46.

The trapezoidal wave signal in FIG. 10(f) is the internal waveform of the second phase comparator 47 in FIG. 9, and is the phase reference signal of the capstan motor triggered by the trailing edge in FIG. 10(e). be.

FIG. 10(g) shows a reproduction control signal obtained from the control head 5 of FIG. Sample FIG. 10(f) with the leading edge of FIG. 10(g). The hold signal (not shown) and the second
The speed error signal obtained from the frequency discriminator 45 of
are mixed in an adder 48 and sent to a second
is supplied to the drive circuit 13 of. Therefore, the capstan motor 6 rotates in phase synchronization with the output signal of the tracking monomulti circuit 46 shown in FIG. 10(e), which is obtained by shifting the phase of the reference signal shown in FIG. 10(a).

As described above, by synchronizing the phases of the rotary head 8 and the reproduction control signal (FIG. 10(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 If the formats of the tracks recorded on the magnetic tape are compatible, the variable resistor 50 for tracking adjustment may be a fixed resistor. When playing a tape recorded with a VTR that has a mechanical error or a soft tape sold outside, noise may appear on the screen due to the track jig being misaligned.

Therefore, tracking adjustment is required, and the adjustment is performed manually using the variable resistor 50 shown in FIG.

Also, this variable resistor needs to be a volume with a click point to make it easier to use.

Therefore, conventional VTRs require a tracking adjustment volume, and there is also 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 uses a magnetic tape on which a video signal is recorded by a rotating head and a control signal of a constant period is recorded by a control head. and an error detection means for detecting an error in the phase difference between the head switching signal of the rotating head and the reproduced control signal with respect to a reference phase during reproduction, and an error detection means for detecting an error with respect to a reference phase between the head switching signal of the rotary head and the reproduced control signal; a control means for controlling the rotation of a running motor; a tracking variable means for changing the reference phase; and an automatic tracking means for performing tracking based on information of a signal obtained by the tracking variable means when reproducing the magnetic tape. , playback mode detection means for detecting a mode transition from another operation mode to normal playback mode or a change in playback speed mode; and when the playback mode detection means detects the playback mode, tracking is performed by the automatic tracking means. and tracking operation control means for starting the operation.

Effect of the Invention With the above-described configuration, the present invention does not require a tracking adjustment volume and can be used for tapes that have expanded or contracted due to environmental changes such as temperature changes, or for tapes recorded with other VTRs that have mechanical errors. A magnetic recording and reproducing device that realizes a high-performance automatic 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 automatic tracking function according to an embodiment of the present invention. A cylinder motor 2 that drives a pair of rotary heads 8 for recording and reproducing video signals, a capstan motor 6 that runs the tape 1 at a constant speed, and a microprocessor 1 that controls these two motors and realizes an automatic tracking function.
0, a first drive circuit (DRl) 12 that drives the cylinder motor 2 by the first analog signal output from the control means 104 of the microprocessor 10, and a first analog signal output from the control means 104 of the microprocessor 10. a second drive circuit (DR2) 13 that drives the capstan motor 6 with the analog signal of the rotary head 8; an amplifier circuit 14 that amplifies the reproduced envelope signal obtained from the rotary head 8; and a peak detection circuit for the amplified reproduced envelope signal. The output of the detection circuit 15 and the output of the detection circuit 15 are AD
automatic tracking means 101 of the microprocessor 10 for converting and inputting, mode inputting means 16 for inputting the operation mode, and reproduction mode detection means 1 for detecting the reproduction mode from the operation mode input by the mode inputting means 16.
03, and a tracking operation control means 102 that starts a tracking operation when the reproduction mode is detected by the reproduction mode detection means 103. Note that the control means 104, the tracking operation control means 102, the automatic tracking means 101, and the reproduction mode detection means 103 are constituted by software stored inside the microprocessor 10.

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

FIG. 3 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. 2 is a flowchart showing an example in which phase control of the stun motor 6 during regeneration is realized by a program built into the microprocessor 10 of FIG. 1. FIG.

Regarding the flowchart in FIG. 3, the conventional V in FIG.
This will be explained with reference to an operation waveform diagram of the TR.

Processing blocks 451, 453 and branch 452 in FIG.
Therefore, the reference signal during VTR playback, that is, the reference signal in Fig. 10 (a
), processing block 453
REF and TRM are constants, which are the repetition period of the reference signal and the center value of the tracking shifter amount, respectively, and the memory 1 stores the count value corresponding to the leading edge of the next reference signal, that is, as shown in FIG. The time corresponding to the leading edge in a) is written into the memory 2, and the time corresponding to the tracking shift amount, that is, the trailing edge in FIG. 10(e), is written in the memory 2.

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

Processing blocks 454, 456 and branch 455 then generate the capstan motor phase reference signal, i.e., the 10th
A trapezoidal wave signal corresponding to the one shown in FIG. Determine whether it has exceeded the limit, and if it has exceeded the limit, proceed to processing block 45.
At step 6, the NL flag that checks whether the reproduction control signal has arrived is reset (indicating that it has not arrived), and the high level of the trapezoidal wave signal (FIG. 10(f)) is stored in the memory 4.
Hereinafter, it will be abbreviated as H level. ) The count value corresponding to the boundary point between the period and the slope section 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 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 a value has been transferred is set. If the CTL flag is set, proceed to the next processing block 458 and proceed to the second
The count value latched in the register file, that is, the capture register block 700 in FIG. 2, is transferred to the memory 5 via the accumulator (hereinafter abbreviated as ACC) of the register (REG) 100 in the figure.

After determining the NL flag in branch 459, processing block 460. Branch 461 determines whether the time at which the control signal written in memory 4 arrives, that is, the H level section in FIG. 10(f), is earlier than the boundary point of the slope section. If yes, proceed to processing block 463 and set the ACC to H in FIG. 10(f).
A value corresponding to the level is set, and if not, processing proceeds to processing block 462.

Processing block 462 and branch 464 determine whether the arrival time of the control signal has passed the slope section shown in FIG. 10(f). KEISHA in the processing block 462 is a count value (constant) corresponding to the slope section of FIG. 10(f).

Then, if the slope section has been passed, processing block 4
Proceeding to 65, the low level (hereinafter abbreviated as L level) of the trapezoidal wave signal in FIG. 10(f) is applied to Acc 4B9, 47
0, 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 487 determine whether the count value of time base counter 500 has passed the time corresponding to the boundary point between the slope section and the L level section in FIG. Processing block 46
At step 8, Acc is set to a value corresponding to the L level in FIG. 10(f), and the process proceeds to processing block 468.

As described above, the phase of the capstan motor 8 is controlled.

Next, automatic tracking operation will be explained using the flowchart of FIG. 4 and the operation waveform diagram of FIG. 5.

FIG. 4 shows that the reproduced envelope signal obtained from the rotary head 8 of FIG.
2 is a flowchart showing an example in which a means for importing D-converted digital data into a memory is realized by a program built into the microprocessor 10 of FIG. 1. FIG.

FIG. 5(a) shows a head switching signal for a pair of rotating heads 8p attached to a cylinder motor. FIG. 5(b) shows a reproduced envelope signal obtained from the rotary head 8. Fig. 5(C) shows the detection circuit 15 of Fig. 1 in Fig. 5(b).
This shows the signal obtained by peak detection. That is, the signal shown in FIG. 5(C) is inputted to the □ converter 19 shown in FIG. 2, and is stored in the microprocessor 10 as digital data.

Branches 401, 405, and 410 in FIG. 4 are RAM,
In other words, this is a process of branching the flow according to the value of the state variable A set on the memory.

First, when A; 0, the process proceeds to processing block 402 via branch 401, and the signal level of the head switching signal (see FIG. 5(a), hereinafter abbreviated as H8W signal) is changed to AC.
After loading into C, it is detected that the H8W signal is at L level, and processing block 404 sets state variable A to 1.

When A=1, processing block 4 is executed by branch 405.
08, 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, 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 5(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, about 8 ms after the leading edge of the H8W signal. In addition, regarding the timer set, the time pace counter 50 in FIG.
This can be achieved by using 0 or by using a soft counter based on how many times a specific instruction on the program has been passed.

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

When A=2, branch 410 causes branch 411
Proceed to step 1 and determine whether the timer set when °·A′=1 has completed counting. If yes, the process proceeds to processing block 412, where the AD conversion value of the signal (FIG. 5(C)) obtained by peak-detecting the reproduced envelope signal as explained in FIGS. 4 and 5 is stored in the memory 7 from the register file.
is being transferred to.

That is, the data of the register file approximately 8 ms after the leading edge of the H8W signal (R1 and R2 in FIG. 5) is taken into the memory 7. Next, processing block 41
At step 3, state variable A is reset to zero.

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. 6 showing the amplitude level of the envelope signal.

FIG. 6 is a graph showing the relationship between the tracking thick 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. 6(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 with the same width as in standard recording mode, the amplitude level of the playback envelope is as shown in Figure 6 (b). The waveform has a flat part.

Furthermore, when considering image quality and SN ratio, the point where the waveform in FIG. 6(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 described using a flowchart of automatic tracking of the seventh solid state curve = Wandering.

First, branch 501 determines whether automatic tracking is being executed. If not, proceed to branch 502; if yes, proceed to branch 505. In branch 502, VT
It is determined whether R is in recording mode or reproduction mode. In the playback mode, the process advances to branch 503, and it is determined whether the switch circuit 31 in FIG. 2 has been pressed by the user. If yes (if the switch is on), the process proceeds to processing block 504, and the variables Di and D2 set on the memory are each set to 6
and 3, clears the memory θ, sets a fix value (a value corresponding to the tracking position and reference phase at the time of recording) in the memory 3 (tracking shifter amount), and proceeds to branch 505. Also, branch 502 and branch 503
If not, move on to the next program.

Next, depending on the value of state variable B, branches 505 and 512
．． The flow is branched by 521, 536, and 545.

First, when state variable B is O, proceed to processing block 50B via branch 505, decrement variable D1,
In the next branch 507, it is determined whether the variable D1 is 0 or not.

That is, using variable D1, processing block 504.50
8 and branch 507, the time required to pass through the soft timer 6 six times is delayed. this is,
This is because it takes time for the capstan motor 8 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 +1 ms is added to the data in the memory 3 described in the explanation of FIG. 3 in order to shift the tracking thick 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 thick amount exceeds +Ioms, 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 in the next branch 514, it is determined whether variable D2 is 0 or not. Here again, variable D2 is used to configure a soft timer. After a certain period of time, the process proceeds to processing block 515, where variable D2 is set to 6. Next, in branch 516,
Comparing the memory 6 that stores the amplitude level of the envelope signal when the tracking thick amount is set to the fixed value and the memory 7 that stores the amplitude level of the envelope signal when the tracking shifter amount is shifted by +1 ms. There is. 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 508, and the tracking shift amount is increased by +1.
ms shift. In branch 517, it is determined whether the number of passes is the first time. If yes, processing block 51
9, the tracking shifter amount is shifted by 12m5, and the 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 thick amount by 1 m5, and branches 531
Proceed to.

That is, by processing in which the state variable B is 0 or 1, the tracking shifter amount searches for the peak value of the amplitude level of the envelope signal in the plus (+) direction centering on the fix value. Further, in the process in which the state and variable B are 2, the tracking thick amount searches for the peak value of the amplitude level of the envelope signal in the negative (-) 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 6 and 7) before and after changing the tracking shifter amount are compared. If memory 6 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 m5, and in branch 529, it is determined whether the tracking shift amount is less than 110 m5. If so, set the tracking thick amount to -10m5 in processing block 530.
and proceed to branch 531. If not, processing block 52
returns to 0, sets state variable B to 2, and sets state variable B to 2.
Repeat the above process when .

In branch 531, it is determined whether flag 2 is on or off. Flag 2 is used in the triple recording mode process and is a forced termination flag for automatic tracking operation. When the standard recording mode is selected, flag 2 is always off, and the recording mode is determined in branch 632, and processing block 53 is executed.
4, flag 1 is turned off, state variable B is set to 0, and the automatic 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.

As described above, when in standard recording mode, state variable B is 0, 1
．． The automatic tracking operation is completed by the above processing in step 2. However, in the triple recording mode, the automatic 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. In the next branch 637, 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 18m5 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 O and perform peak detection again.

In addition, flag 2 shifts the tracking shifter amount by 18m5 when the optimum tracking position is not searched by the automatic tracking operation in the 3x recording mode.
Turn on to search for peak values again. Also,
If no in branch 537, the tracking shifter amount is shifted by +1 ms in processing block 538, and it is determined in branch 539 whether the tracking thick amount exceeds +10 m5. If yes, proceed to processing block 542. If not, state variable B is set to 4 at processing block 540.

When state variable B is 4, the process proceeds to processing block 54θ via branch 545, and along with branch 547, a soft timer is configured using kD2 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 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 m5 and the process proceeds to processing block 534 to complete the automatic tracking operation. If the latter is larger, the process proceeds to processing block 533 and repeats the operation when state variable B is 3.

Note that the threshold value here is set to 80% 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 waveform of the envelope signal in Fig. 6(b) may be affected by noise, and the threshold 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. Thresholds are set taking these into consideration. Further, a value obtained by subtracting a certain value from the peak value can also be set as the threshold value.

According to 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 playback envelope is compared each time, and the amplitude level of the playback envelope is the peak value. The tracking thick 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. 1
The value shifted by m5 becomes the optimal tracking position.

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

Next, the operation of the automatic tracking operation control means will be explained. The automatic tracking operation control means controls the execution timing of the automatic tracking operation described above. The operation will be explained using the flowchart of FIG.

First, the mode input means 1θ of FIG. 1 encodes the input operation mode and serially transfers it.

The transferred data is received by microprocessor 10 as serial data and stored in internal RAM by processing block 602 in FIG. The reproduction mode is detected by the reproduction mode detection means 103 based on the stored data. When the reproduction mode is detected, the process advances to branch 803, where it is determined whether the previously input operation mode and the currently input operation mode are the same. If the operation mode is different, this means that the playback operation is to be started, so the tracking operation is started in block 805 and the tracking is adjusted.

If the operating modes are the same, the process advances to branch 604, where it is determined whether the playback speed mode has changed. If there is a change, the tracking operation is started in block 605, and if there is no change, the tracking operation control means is terminated.

Due to the above processing, automatic tracking operation is started when magnetic tape playback is started, when normal playback returns from special playback, or when the playback speed mode changes,
You can enjoy videos with the best tracking.

Effects of the Invention As is clear from the above description, in the magnetic recording/reproducing device having an automatic tracking function of the present invention, a video signal is recorded by a rotating head, and - a fixed-period control signal is recorded by a control head. Error detection means for detecting an error with respect to a reference phase in a phase difference between the head switching signal (H8W signal) of the rotary head and the reproduced control signal during reproduction of a magnetic tape (magnetic tape 1) (flowchart in FIG. 3) ), and a control means for controlling the rotation of the magnetic tape running motor (capstan motor 8) based on the error signal detected by the error detection means (flowchart in FIG. 3). ) and tracking variable means (processing blocks 509, 518, 519, 5 in FIG. 7) for changing the reference phase.
26,528.538.542.649 constitute a tracking variable means. ), automatic tracking means (the automatic tracking means is constituted by the flowchart of FIG. 7), which performs tracking based on the information of the signal (reproduction envelope signal) obtained by the tracking variable means when reproducing the magnetic tape; Reproduction mode detection means (consisting of processing block 601 and branches 802, 803, and E304 in FIG. 8) detects a mode transition from another operation mode to normal reproduction mode or a change in reproduction speed mode.

), and a tracking operation control means (configured by the processing block E305 in FIG. 8) that causes the automatic tracking means to start the tracking operation when the reproduction mode is detected by the reproduction mode detection means. Tracking is possible even with tapes that have expanded or contracted due to environmental changes such as temperature changes, tapes recorded with VTRs that have mechanical errors, or even if the recording time mode changes and tracking deviates. It is possible to obtain a magnetic recording/reproducing device with improved operability that realizes a high-performance automatic tracking function without requiring manual adjustment using an adjustment volume.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a magnetic recording and reproducing apparatus having an automatic tracking function according to an embodiment of the present invention, FIG. 2 is a block diagram of a microprocessor, and FIGS. 3, 4, 7, and 8.
The figure shows the operation of the main parts in Figure 1. Figure 5 is a timing chart to explain the flowchart in Figure 4. Figure 6 shows the operation of standard recording tape and triple speed recording tape. FIG. 8 is a block diagram showing the configuration of the servo mechanism during playback of a conventional VTR, and FIG. 10 explains the operation of the main parts of FIG. 9. This is a timing chart for 1...Magnetic tape, 2...Cylinder motor, 6
...capstan motor, 19-AD converter,
100...Register, 200...RAM1 3
00...ALU1 400...Instruction execution means,
500...Time base counter, 700...
・Capture register controller, 800...
Capture controller, 1000...ROM,
1400... La Petit. Figure 1 1-One circle 1 tape 2・-Cylinder strip 6---〒Yapstari motor

Claims (1)

[Scope of 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 head switching signal of the rotary head and the reproduced control signal are combined. error detection means for detecting an error in the phase difference with respect to a reference phase; control means for controlling rotation of the magnetic tape running motor based on the error signal detected by the error detection means; and changing the reference phase. automatic tracking means that performs tracking based on information of a signal obtained by the tracking variable means when reproducing the magnetic tape; A magnetic recording and reproducing device comprising: a reproduction mode detection means for detecting a change in mode; and a tracking operation control means for causing the automatic tracking means to start a tracking operation when the reproduction mode detection means detects a reproduction mode. Device.