JPS60237658A - Mode discriminator for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To discriminate automatically the tape speed during recording by reproducing plural pilot signals of different frequencies by a rotary magnetic head, extracting and detecting the signal components for the frequency difference from the frequency of a carrier signal and comparing the same with a set threshold value. CONSTITUTION:The pilot signals of the frequencies f1-f4 are superposed on a video signal and are recorded in the diagonal tracks on a magnetic tape by a rotary magnetic head 8 in synchronization with the head switch signal to be inputted to a terminal 1. A selection switch 6 is set to the play side and the signal component for the frequency difference between the detected pilot signals and the frequency of the carrier signal is obtd. from a mixer 11 and is detected with BPFs 12, 13 in the stage of reproducing. The detected output is passed through a subtractor 16 and is made into the tracking error signal from a terminal 19. Said output is also supplied via gate circuits 30, 31 to comparators 21, 22 by which the output is compared with the set threshold value. A relational discrimination circuit 24 can discriminate the tape speed from the speed generator signal from a capstan motor inputted to a terminal 25 and the outputs from the comparators 21, 22.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a mode discrimination device for a magnetic recording/reproducing device.
In particular, the present invention relates to a mode discrimination device during reproduction in a pilot signal type magnetic recording and reproducing apparatus capable of recording and reproducing at a plurality of tape speeds.

[Prior Art] Conventionally, in magnetic recording and reproducing apparatuses, there have been two types of tape speed running control systems: one using a control signal and the other using a pilot signal.

In the system using control signals, a control track separate from the video signal track is provided on the magnetic tape, and the control track is used to record and reproduce the control signal, thereby controlling the retrieval run. There are magnetic recording and reproducing devices that use this control signal that are capable of recording and reproducing at multiple tape speeds, and these devices have a mode determination function that automatically determines the tape running mode during playback. was provided. This mode discrimination device discriminates the tape running mode during playback by using the above-mentioned control signal.

On the other hand, in the method using a pilot signal, a pilot signal for tape speed control generated in synchronization with the rotation of a rotating magnetic head is superimposed with the video signal on the video signal track of the magnetic tape and recorded. A pilot signal was extracted from the reproduced signal, and tape running and lj were controlled by the pilot signal. Currently, only devices that record and reproduce data at a single tape speed are commercially available as magnetic recording and reproducing apparatuses that use this pilot signal. Naturally, therefore, such devices are not provided with mode discrimination for determining tape speed.

Next, tracking control in a pilot signal type magnetic recording/reproducing device will be described. Figure 1 shows a conventional magnetic recording/reproducing WAll (V
FIG. 2 is a block diagram of a tracking control means of TR. In the figure, a head switch signal input terminal 1 is connected to an adder 3 via a pilot signal generator 2. Further, the head switch signal input terminal 1 is connected to the switch 18.

The video signal input terminal 4 is connected to the adder 3. The recording amplifier 5 is connected to a changeover switch 6, and the changeover switch 6 is connected to a magnetic head 8 through a rotary transformer 7. The magnetic head 8 is provided on a rotating drum (not shown),
The magnetic head 8 obliquely scans a magnetic tape (not shown) at a rotation angle L along with the rotation of the rotary drum. A head switch signal representing the switching timing of the rotating magnetic head, which is input to the rad switch signal input terminal 1, is applied to the pilot signal generator 2 and the switch 18. Pilot signal generator 2 sequentially generates pilot signals in response to the leading edge and IN edge of the head switch signal described above.

During recording, a video signal is input to the video signal input terminal 4, superimposed on the above-mentioned pilot signal by the adder 3, and then input to the recording amplifier 5 where it is amplified. The changeover switch 6 is connected to the REC side, and the output of the recording amplifier 5 is supplied to the magnetic head 8 via the 0-Tari transformer 7 and recorded on a magnetic tape (not shown).

The selector switch 6 is a regenerative amplifier 9. Low pass filter 10
It is connected to the mixer 11 via. Also, pylon 1~
Signal generator 2 is connected to mixer 11 . During playback, the selector switch 6 is switched and connected to the PLAY side, and the video signal including the pilot signal reproduced by the magnetic head 8 is reproduced via the rotary transformer 7 and the selector switch 6. The signal is input to an amplifier 9 and amplified. The output of the regenerative amplifier 9 is given to a low-pass filter 10, and a pilot signal component is extracted from the regenerated signal. This pilot signal component j3 and the aforementioned pilot signal (
Below, during playback, Gitria signal t is used. ) is input to the mixer 11, and a signal component having a frequency corresponding to the frequency difference between the two signals is output. Mixer 11
are bandpass filter 12 and bandpass filter 1
Connected to 3. The bandpass filter 12 is a detector 14
The bandpass filter 3 is connected to the subtracter 16 via a detector 15. Subtractor 16 is connected to switch 18 . Further, the subtracter 16 is connected to a switch 18 via an inverting amplifier 17. Switch 18 is connected to tracking error signal output terminal 19.

The output of the mixer 11 is simultaneously applied to a bandpass filter 12 having a pass band of 16 kHz and a band pulse filter 13 having a pass band of 46 kHz. The signal that has passed through the bandpass filter 12 is subjected to envelope detection by a detector 14, and its output is given to a subtractor a16. On the other hand, the signal that has passed through the bandpass filter 13 is envelope-detected by a detector 15, and its output is also subtracted by 1e.
Given at t16. The output of the subtracter 16 is sent to the tracking error signal output terminal 1 as a signal with the same polarity as it is by a switch 18 that is switched in response to the head switch signal, or as a signal with the opposite polarity via an inverting amplifier 17.
A tracking error signal is output at 9.

FIG. 2 is a diagram showing a pattern of video signal tracks formed on the magnetic tape 20 at an angle in the longitudinal direction of the tape, and a pilot signal recorded on each video signal track in a manner superimposed with the video signal. . The operation of the tracking control means shown in FIG. 1 will be roughly explained in detail with reference to the second section.

During recording, the pilot signal generator 2 generates four different frequencies f, , r2 . . . in synchronization with the leading and trailing edges of the head switch signal. Pilot signals f, , f4 are generated by switching each field.

For example, when recording an NTSC video signal, these four frequencies are fl=102kHz, fz-
118kl-1z, fs=164kHz.

As f+=148kHz, the frequency difference α between t, and f2 is equal to the dark frequency difference between r, and t, and the frequency gll difference between f4 and f2 is almost twice α. is set to the value. These pilot signals are superimposed on the video signal, and as shown in FIG. 2, the magnetic head 8 sends the Il!
Image signal tracks are formed into fields and recorded.

In FIG. 2, video signal track F1. F2. Fa,
F4 indicates that pilot signals of frequencies f+, fz, re, and f< are recorded, respectively.

During playback, the magnetic head 8 plays back the signal recorded from the video signal track on the magnetic tape 20, and this playback signal is input to the playback amplifier 9 via the rotary transformer 7 and the changeover switch 6, where it is amplified. Ru. The output of the regenerative amplifier 9 is given to a low-pass filter 10, and the pilot signal component contained in the regenerated signal is extracted. For example, if we consider a case where the magnetic head 8 is tracking a video signal track F on the magnetic tape 20 as shown in FIG. 2, the pilot signal component reproduced by the magnetic head 8 includes: Video signal track F,
In addition to the pilot signal of frequency f, which is superimposed on the image signal track adjacent to the picture signal track (F2 and F4> in the example of Fig. Included, and
The magnitude of the pilot signals detected from these adjacent video signal tracks is determined by the magnitude of the image being tracked by the magnetic head 8! As the amount of misalignment of the signal track from the center increases, it increases accordingly.

The above-mentioned pilot signal component extracted by the low-pass filter 10 when tracking the video 11 signal track F, and the key 11 rear signal f c, =f, generated by the pilot signal generator 2 are input to the mixer 11. , the pilot signal frequency f2-118kHz of one adjacent video signal track E2 and the carrier signal frequency f c *
-r + -102k@Z and the signal component having a frequency of 16kHz, the other adjacent video signal track F,
A signal component having a frequency of 46 kHz, which is the difference between the signal frequency f<-148 kHz and the carrier signal frequency f c R-r + -102 kHz, is obtained from the pylon. These 16kHz and 46kHz signal components are further
The signals are extracted separately by a bandpass filter 12 with a passband of 15kl-1z and a bandpass filter 13 with a passband of 46kHz. The output of the bandpass filter 12 is envelope-detected by the detector 14, and the output level represents the magnitude of the positional shift of the magnetic head 8 to the adjacent video signal track F2 on the right side.

On the other hand, the output of the bandpass filter 13 is subjected to envelope detection by the wave detector 15, and the output level represents the maximum displacement of the magnetic head 8 to the adjacent video signal track F on the left side. Subtractor 1
6, the positional deviation from the center of the video signal 1 to rack of the magnetic head 8 can be obtained. However, when the magnetic head 8 is tracking the video signal track F1 or F3, and when the magnetic head 8 is tracking the video signal track F2 or F4,
When tracking , the frequency difference between the right and left adjacent isthmus image signal tracks is in an inverse relationship, so the output of the subtracter °16 has an opposite polarity. Therefore, by providing an inverting amplifier 17 for inverting the polarity and switching the switch 18 to "C" by the head switch signal, the magnetic head 8 is set to the video signal track F2 or F.

When tracking, it is necessary to invert the polarity of the output of the subtracter 16. In this way, the above-mentioned magnetic head 8 is reflected on the trunking error 1J@output terminal 19! A tracking encoder (No. 3) having a voltage corresponding to the position deviation peak from the center of the j11 signal track is output, and this No. 7 is packed into the capstan motor to form a servo control system. Dragging is performed.

[Summary of the Invention] The present invention has been made based on the above-mentioned problems. Therefore, the main object of the present invention is to record and reproduce data at a plurality of tape speeds in a pilot signal type magnetic recording and reproducing device. If you configure a device that is capable of
It is an object of the present invention to provide a mode discrimination device that can automatically discriminate the tape speed during recording.

To summarize the present invention, in a pilot signal type magnetic recording/reproducing device, a pilot signal of a specific frequency is generated only within a predetermined time in synchronization with a signal indicating switching of a rotating magnetic head, and this is used as a carrier signal. Then, a plurality of pilot signals with different frequencies recorded on diagonal tracks on the magnetic tape in the form of information signals are reproduced by a rotating magnetic head, and the frequency between the plurality of reproduced pilot signal frequencies and the carrier signal frequency is determined. By extracting the difference signal component and applying the output obtained by detecting this frequency difference component to a comparison means having a preset threshold,
This mode discrimination device creates a signal to replace the control signal in a conventional control signal type magnetic recording and reproducing device, and determines the tape speed of the magnetic tape from this signal and the output of a capstan motor speed detection means. .

The above-mentioned objects and features of the present invention will become clearer from the following description of embodiments with reference to the drawings.

[Embodiment of the Invention] An embodiment of the invention will be explained below with reference to FIGS. 3 to 7. 7. In the description of this embodiment, the description of parts that overlap with the description of FIGS. 165 and 2 will be omitted as appropriate. - Fig. 3 is a schematic diagram of a mode discriminating device in a pilot signal type magnetic recording/reproducing apparatus according to an embodiment of the present invention. The difference from the configuration of the G υJll1 means is that the following circuit is added for mode determination t1.

That is, the detector 14 is connected to the gate circuit 30. The detector 15 is connected to the selector circuit 23 through the comparator 21, and the detector 15 is connected to the gate circuit 31. Through the comparator 22 -
(Connected to the selector circuit 23.

The selector circuit 23 and the speed signal input terminal 25 are connected to a comparison and discrimination circuit 24, and the comparison and discrimination circuit 24 is connected to a mode command signal output terminal 26. Furthermore, a gate circuit 3 is connected between the switch 18 and the tracking error signal output terminal 19.
2 is the point where it is connected. Both gate circuits 30 and 31 are gate circuits that allow the output of the detector 14 and 15 to pass for a predetermined time T and do not allow the output to pass for other times, and the comparators 21 and 22 have a predetermined threshold value S. This is a comparator. The selector circuit 23 is a selector circuit that alternately selects and outputs the signals from the comparators 21 and 22, and can be composed of, for example, an SR flip 70 tube with a tAm embedded input and an analog switch as shown in FIG. The comparison and discrimination circuit 24 is a comparison and discrimination circuit that discriminates the mode from the speed generator signal from the capstan motor input to the speed signal input terminal 25 and a signal from the selector circuit 23 that can replace the conventional control signal. The output of the comparison/discrimination circuit 24 is output to the mode command signal output terminal 26. The gate circuit 32 is a gate circuit that does not allow human power to pass through for a predetermined time T, but allows this input to pass during other times.

FIG. 4 is a time chart when the video signal track is accurately tracked by reproducing at the same Q1 speed (mode) as during recording. FIG. 5 is a time chart during playback at a tape speed 172 times that of recording. FIG. 6 is a time chart during playback at twice the tape speed of recording. In Figure 4.5.6, (a) shows the head switch signal, (b) shows how the pilot signal during recording is switched by the head switch signal (a), and (C) shows how the head switch signal changes during playback. The pilot signal is always set to F for a predetermined time T when the head switch signal (a) is switched, and the other times are switched in the same manner as during recording. (d) is 16kl-12
The output detected by the 16k)-IZ acid component detector 14 which has passed through the bandpass filter 12 having a passband of (e) shows the relationship between the value S and the gate circuit 31 which allows the output of the detector 15 to detect the 46kHz component that has passed through the bandpass filter 13 having a passband of 46kl-1z for a predetermined period of time. The output obtained through and comparator 2
2 and the threshold value S, ([) is the comparator 21
．． This is the output of the selector circuit 23 that alternately selects the outputs of 22, and is a signal that can replace the conventional control signal.

As shown in FIG. 2, the magnetic head 8 is connected to the video signal track F,
Suppose you are tracking. The reproduced signal has a frequency t
, and both adjacent frequencies f4. If there is a component of f2 and the carrier frequency coefficient rca is tl, then both adjacent components r, -f, = 46 kHz, f, -f
, -16kH2 components are obtained almost equally, and this 16kH2 component is obtained almost equally.
A tracking error signal as shown in the first factor can be detected from the difference signal between the H2 component and the 46 kHz component.

Next, assuming that the magnetic head 8 is tracking the video signal track F2, the reproduced signal includes a main component of the frequency f2 and both adjacent frequencies 1. ．． There is a component of 1.

At this time, if the carrier signal frequency t and ct are f, then t 2-r of the main component.

-16kHz component and adjacent component fs-f+=62kHz
The 16 kHz component at this time is the main component and is therefore much larger than the adjacent components.

Similarly, the magnetic head 8 is on the video signal track F.

When tracking the carrier signal frequency rc
When t is set to f, the main component f, -1+=62kHz
f 2−f+ ” ”I 6 which is the component of z and both adjacent components
kHz2 component, r4-t, -46kHz7 component are obtained, and when the carrier signal frequency rct is f while the magnetic head 8 is tracking the image (g@track F), the main component f4-f+ = 46 kH2 component and adjacent valve ?allo f s f .

=62kHz component is obtained. Therefore, when the carrier signal frequency rct is set to r, the level varies somewhat depending on the width of the magnetic l\rad and the width of the video signal track, but the 16 kHz component reaches the maximum when tracing the video signal track F2. The 46kHz2 component reaches its maximum when tracing the video signal track F4.

The above-mentioned principle will be explained with reference to FIGS. 4-6. As shown in the time chart of FIG. 4, when reproducing at the same tape speed as during recording, the carrier signal frequency +' ct, which should be the same (b) as during recording, is calculated, for example, by (0 ), synchronizing with the switching of the I\rad switch signal (a), the frequency 11 is always set at a predetermined time by filT.
is the Chiyaria signal frequency fcl. From the above principle,
Bandpass filter 12 with a passband of 16kHz
Passed 16. A gate circuit 30 that allows the output of the kHz component detected by the detector 14 to pass through only when the clock is open at a predetermined time.
(As shown in (1), when tracking the video signal track F2, a large output cuff Jl hJ is generated, 46k) (passes through the band hash filter 13 whose pass band is z/=46kHz When the applied force whose component is detected by the detector 15 is passed through the cable L!!L path 3] for a predetermined time + ffi T, the video signal 1 to rack F4 are transmitted as shown in (e). A large output can be obtained when tracking the gate circuit 30.
．． By passing the output of 31 through comparators 21 and 22 having a predetermined threshold value S, the positions of the video signal transformers F2 and F can be detected, and the outputs of the comparators 21 and 22 can be alternately selected by the selector circuit 23. By passing through, a signal like (-f) is obtained. This signal has one pulse in a period corresponding to two fields and is equivalent to a control signal.

Similarly, as shown in the time chart in Figure 5, if we consider the case where the tape is being played back at half the speed of recording, the phase control of the running control does not work properly. The magnetic tape is running at a speed substantially close to the above-mentioned speed due to speed control. At this time, if a carrier signal is generated as shown in (C), the same video signal track will be traced twice, so the output of the gate circuit 30 will be as shown in (d), and the output of the gate circuit 31 will be as shown in (e). become that way. Therefore, the output of the selector circuit 23 becomes one pulse in a period corresponding to four fields, as shown by (i), and is equivalent to a control signal.

Similarly, when the tape is played back at twice the recording speed as shown in the time chart of FIG. 6, two video signal tracks are traced at one time, so the gate circuit 3
The output of 0, the output of the gate circuit 31, and the output of the selector circuit 23 are as shown in (d), (e), and <r>, respectively, and (z) is one pulse in a period equivalent to one field, which is equivalent to the control signal. It is.

Therefore, even if the tape speed is different during recording and playback, a signal equivalent to the conventional control signal can be obtained, so that the output of the selector circuit 23 and the speed power generation from the capstan motor input to the speed signal input terminal 25 The mode (tape speed) can be determined from the machine signal by the comparison and determination circuit 24 using a method similar to the conventional method. That is, the tape speed is determined by counting the output pulse (speed generator signal) f output from the speed generator at the time interval of the output of the selector circuit 23 and comparing this counted value with a predetermined reference value. can do. This determination result is output as a mode command signal to the mode command output terminal 26,
The playback mode can be set to the same mode as the recording mode. In this case, the tracking error signal becomes abnormal only during the predetermined time 111T, but since the predetermined time T is at most several times the water hand scanning period, conventional tracking control with a response band of about several Hz is not possible. It has almost no effect on the system itself. Furthermore, in this case, if a gate circuit 32 is provided that does not allow the tracking error signal to pass during a predetermined time period T and makes the tracking error signal bold, but allows the tracking error signal to pass during the other vf periods, this effect can be completely eliminated. (Become.

In the above embodiment, a pilot signal with a frequency t is used as a carrier signal at a predetermined time T, but a pilot signal with another frequency may be used.

[Effects of the Invention] As described above, according to the present invention, in a pilot signal type magnetic recording/reproducing device, a pilot signal of a specific frequency is generated only at a predetermined number in synchronization with a signal indicating switching of a rotating magnetic head. - Generates an ffi signal and uses it as a carrier signal, and reproduces multiple pilot signals with different frequencies recorded on diagonal tracks on the magnetic tape superimposed on the information signal using a magnetic head, and reproduces multiple pilot signals. By extracting the signal component of the frequency difference between the pilot signal@frequency and the carrier signal frequency, and applying the output obtained by detecting this frequency difference component to a comparison means having a preset threshold, A signal is created to replace the control signal in the magnetic recording and reproducing bag U using the conventional control signal system, and the time interval of this signal is measured from the output of the speed detection means of the capstan motor. k
The tape speed of the magnetic tape is determined by comparing it with a predetermined reference value, so that a mode discriminator r can be obtained that can automatically determine the tape speed when recording an information signal when reproducing an information signal. I can do it.

In addition, this mode discrimination device can be configured by adding a small amount of circuitry such as a comparator to a conventional pilot signal type magnetic recording/reproducing device and using a mode discrimination circuit using conventional control signals. can be easily constructed and manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a tracking control means in a conventional pilot signal type magnetic recording/reproducing bag ff (VTR). FIG. 2 is a diagram showing the relationship between a video signal track pattern formed on a magnetic tape and a pilot signal recorded on the video signal track pattern in a superimposed manner with the video signal, as well as a magnetic head. FIG. 3 is a schematic block diagram of a mode discrimination device in a pilot signal type magnetic recording/reproducing apparatus (VTR') which is an embodiment of the present invention. FIG. 4 is a time chart when reproducing at the same tape speed as recording. FIG. 5 is a time chart when reproducing at a tape speed 1/2 that of recording. FIG. 6 is a time chart during playback at twice the tape speed of recording. FIG. 7 is a diagram showing an example of the configuration of the selector circuit. In the figure, 1 is a head switch signal input terminal, 2 is a pilot signal generator, 3 is an adder, 4 is a video signal input terminal, 5 is a recording amplifier, 6 is a changeover switch, 7 is a rotary transformer, and 8 is a magnetic head. , 9 is a regenerative amplifier, ] 0 is a low-pass filter, 11 is a mixer, 12.13 is a band-pass filter, 14.15 is a detector, 16 is a subtracter, 1
7 is an inverting amplifier, 18 is a switch, 19 is a tracking error signal output terminal, 20 is a magnetic tape, 21.22 is a comparator, 23 is a selector circuit, 2/I is a comparison/discrimination circuit, 25 is a speed signal input terminal, 26 is a Mode command signal output terminals 30, 31, and 32 are gate circuits. J3, the same reference numerals in each figure indicate the same or corresponding parts. Masuo Oiwa

Claims (2)

[Claims] (1) When recording an information signal on a diagonal track on a magnetic disk by a rotating magnetic head, a plurality of pilot signals having different frequencies generated in synchronization with a signal indicating switching of the rotating magnetic head are superimposed on the information signal. the plurality of pilot signals from the reproduction signal reproduced from the diagonal track when the rotating magnetic head reproduces the information signal from the diagonal track; In a pilot signal type magnetic recording and reproducing apparatus, the magnetic recording and reproducing apparatus controls the running of the magnetic tape by extracting the plurality of pilot signals in sequence and detecting a tracking error signal for the diagonal track of the rotating magnetic head based on the extracted plurality of pilot signals. , the pilot signal generating means for generating the plurality of pilot signals generates any one of the plurality of pilot signals only within a predetermined time in synchronization with a signal indicating switching of the rotating magnetic head; The plurality of pilot signals are configured to be repeatedly generated in the predetermined order outside the predetermined time, and any one of the plurality of pilot signals generated within the predetermined time and the extracted a level of a signal component responsive to a frequency difference between the signal component and the plurality of pilot signals is detected by first and second level detecting means; first and second comparison means for comparing the outputs of the first and second comparison means with a threshold; selection means for alternately selecting the outputs of the first and second comparison means; speed detecting means for detecting the speed of the capstan motor; measuring a time interval between the outputs of the selecting means from the output of the speed detecting means, and comparing the measured time interval with a predetermined reference value to determine the speed of the magnetic tape; 1. A mode discriminating device for a magnetic recording/reproducing device, characterized in that it comprises a comparison discriminating means for discriminating a tape speed of a magnetic recording/reproducing device. (2) A mode determination device for a magnetic recording/reproducing apparatus according to claim 1, which holds the tracking error signal for the predetermined time so as not to affect the running control of the magnetic tape. .