JPS62289950A - Information signal reproducing device - Google Patents

Abstract

PURPOSE:To obtain a good reproduced signal without being affected by the linearity of tracks, the degradation in SN ratio, etc., by multiplying a reproduced pilot signal by a reference signal and sampling the output with the rotation phase of a rotating head and performing comparison plural times to discriminate a track pitch. CONSTITUTION:A reproduced pilot signal PB is multiplied by four kinds of reference signal having the same frequency, and multiplication results are allowed to pass BPFs 12 and 13 and are detected by detectors 14 and 15 to obtain two kinds of signal, and they are compared with each other by a comparator 16 to obtain a tracking error signal ATF. This signal ATF is led to an S/H circuit 1, which samples and holds the signal is every field, through a hysteresis amplifier 17, and the output of the circuit 1 is led to 1/2 and 1/3 S/H circuits 2 and 3 which sample and hold the signal in every second and third fields respectively. Outputs of circuits 2 and 3 are delayed in delay circuits 4 and 5 by two fields and four fields and are compared with signals before delay by a comparator, and the track pitch is discriminated by a discriminating circuit 7.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an information signal reproducing device, and more particularly, the present invention relates to an information signal reproducing device that reproduces a plurality of types of barilot signals having different frequencies at a predetermined rotation rate for each track. Recording media recorded on -
This relates to a device that relaxes the function of distinguishing the track pitch of F.

[Prior Art] In recent years, in VTRs (video cheap recorders), in addition to the normal recording/playback mode 1' (hereinafter referred to as SP mode), a long-time mode in which the tape feed speed (i.e., track pitch) is halved is used. Some VTRs are equipped with a recording/playback mode (hereinafter referred to as an LP mode), and these recording modes must be determined during playback in this type of VTR. Therefore, by multiplying the regenerated pilot signal by four types of reference signals (hereinafter referred to as local pilot signals) having the same frequency as the regenerated pilot signal from the control target track using the well-known 4-frequency tracking method, the regenerated pilot signal is obtained. The tracking error signal (hereinafter referred to as the ATF signal) is derived at a predetermined phase of the rotary head, that is, at a predetermined phase of each field of the reproduced video signal, its fundamental wave is derived, and the reference clock is calculated within the period of this fundamental wave. - A method of determining the recording mode based on the counted value was considered.

FIG. 2 is a block diagram showing a configuration example for obtaining an ATF signal using the four-frequency method, in which 12.13 is a band pass filter (BPF), 14.15 is a detector (DET), 1
6 is a comparator.

In a VTR that performs 4-frequency tracking, the tracking pilot signal is switched between 4 different frequencies at the field cycle, so the video signal and P
Each is recorded superimposed on the CM audio signal. This 4
Type of tracking pilot signal frequency f +, f
2. f3. f4 is 102.6KHz, 11.
9KH,,165,4KH,? , 146, 8
K ) (selected by z, If, -f21= 1
f3-f41=16KH2If, -f41= If
2-f31=46KH2. Also, the frequency rotation of the pilot signal in recorded poetry is f,
+f2→f3→f4→f1. The frequency rotation of the local pilot signal during playback is f1 → f4-p
f3→f2−f.

Then, the BPF 12 of the 46Kl-12 outputs a signal obtained by multiplying the pilot signal obtained from the reproducing head (reproducing pilot signal) by the local pilot signal which is sequentially switched by the above-mentioned rope John. and 16KH
, , 1 corresponding to the black talk components from both adjacent tracks of the target track.
A detection circuit (DET
) 14 and DET 15 to obtain a voltage signal with a value corresponding to each amplitude, and then a comparator 16 calculates the difference between the two to obtain an ATF signal.

[Problems to be solved by the invention] As mentioned above, in conventional devices, the ATF signal, which is the standard for determining the recording mode, is a relatively low-level analog signal, and the linearity and S/N of the recording state of the tape are
As a result, the determination circuit lacks reliability and stability, and it takes time to determine the recording mode.

This invention was made in view of such problems,
It is an object of the present invention to provide an information signal reproducing device having a new and effective function of identifying recording track pitch.

[Means for Solving the Problems] The information signal reproducing device according to the present invention reproduces a plurality of types of reference signals having different frequencies in a predetermined rotation in synchronization with the rotational phase of a reproducing rotary head as a reproducing pilot signal. The track pitch is automatically determined by multiplying the level comparison output of two types of frequency components obtained by sampling the output at a predetermined rotational phase of the head, and comparing the sampling signals multiple times within a predetermined period. be.

[Function] In this invention, since the track pitch is determined by comparing the signals obtained by performing sampling in phase with the predetermined rotation f☆ of the rotary head multiple times, the linearity of the track, the S/N ratio deteriorates, Furthermore, the track pitch of the recording track can be identified without being affected by variations in mechanical accuracy of the device.

[Example] Figures 1(a) and (b) show V as an example of the present invention.
It is a block diagram showing the main part configuration of TR, l is a spatula t・
A sample hold (hereinafter referred to as 30PG) which samples and holds an ATF signal via a hysteresis amplifier 17 (described later) at a predetermined phase for a signal (hereinafter referred to as 30PG) that is synchronized with the rotation of the video signal and inverted every field of the video signal every field.
There is a S/+4) circuit, and 2 is a circuit that samples and holds the S/H circuit power at a desired phase for 30PG every 2 fields (=1 frame), and 3 is a circuit that samples and holds the S/H circuit power every 2 fields (=1 frame). This is an S/11 circuit that samples and holds the S/H circuit circuit power, and 4.5 is a delay circuit having delay times of 2 fields and 4 fields, respectively, and 6a is a delay circuit 4 that outputs the output of the S/H circuit 2. 6b is an exclusive OR (EX-OP) circuit that compares the output delayed by 2 fields 1 to the output of 5711 circuit 2, and 6b is the output of S/11 circuit 3 which is delayed by 4 fields by delay circuit 5. There is an EX-OR circuit that compares the output of the S/11 circuit 3, 6 is a comparison circuit constituted by these two EX-OR circuits, 7 is a comparison circuit composed of two ant circuits 7a and 7b, an inverter 7c, and an OR circuit. There is a judgment circuit C consisting of one circuit 7d, and the input signal to the inverter 7c is a system controller (not shown) that determines that the recording mode is an SP mode.When the bar C level is ``H'', it is judged that it is an LP mode. This is a signal from the system controller that becomes low level "L" when the

The ATF signal obtained by the comparator 16 in FIG. 2 passes through a hysteresis amplifier 16 having an intermediate threshold value (approximately zero level), and the output thereof is supplied to the 8/11 circuit l. This signal is basically DET14 in Figure 2.
, 15 detected by 16KH,, components and 46KH
A digital signal has two states, "H" and "L", depending on the levels of the two components. 16KHz component or 4
If the level is higher than the 6KH2 component, this signal goes “L”.
” state, and conversely, if the level of the 46KHz component is higher, it takes the “H” state. However, if the ATF signal or θ
The state will not be reversed even if there is a slight fluctuation near the level.

Next, the principle of recording mode discrimination during so-called high-speed search playback using this signal will be explained.

3. Figures 4, 5, and 6 show the recording mode in forward search, reverse search, and SP mode in playback mode 1~, respectively.
Track pattern when changing the four combinations of LP motes - the locus of the L head and the resulting 16
It is a figure for explaining a KHz component, a 46KH component, and a component. In this example, the tape feeding speeds of the SP mode and the LP mode are 20 ALm/sec, respectively.
gm, and the head width for recording and reproduction is 15 gm. Soc, sp mort.

In each of the LP motes, the tape feed speed ratio for forward search, reverse search, and normal playback is 9 near:1.

Figures 3 (a) and (b) show the track pattern and head trace locus when performing a 9x speed stop direction search and -7x speed reverse search using the LP mode on a tape recorded in the recording mode, respectively. This is what is shown. As shown in the figure, the rotary head scans over several consecutive tracks, or the signal obtained by superimposing the local pilot signal with the reproduced pilot signal obtained by scanning the head between the 1 fields is indicated by diagonal lines in the figure. 16KH, which is proportional to the pilot signal reproduced from the part that has been applied, and 4KH, which is proportional to the pilot signal that is reproduced from the part that has been applied with plaid.
Contains 6KH, ingredients.

Now, if we look at this pattern at a predetermined rotational phase of the rotary head, we can see that it has a regularity of 8 fields equaling one period.

Figures 4 (a) and (b) show the track pattern and head trace locus when performing a 9x forward speed search and -7x reverse speed search in SP mode, respectively, on a tape recorded in LP mode. . As is clear from this figure,
The generation pattern of the 16KH and 46KH components has a regularity in which 4 fields constitute one cycle.

FIGS. 5(a) and 5(b) are diagrams showing track patterns and head trace trajectories when SP dry recording is performed and a 9x speed EF rotation search and -7x speed reverse search are performed using SP mode. . Further, FIGS. 6(a) and 6(b) are diagrams showing track patterns when recording is performed in LP mode and a 9x speed forward rotation search and a -7x speed reverse rotation search are performed using the LP shade.

The generation patterns of the 16KH component and the 46KH component when performing a stop rotation search and a reverse search in the two cases shown in Figures 5 and 6, that is, when the motes match in recording and playback, are It is the same for each field.

That is, 511(a), (b), Figure 6(a), (b)
As is clear from
I can see that it is a cycle.

Mote and 16KH2 components during recording and playback.

Table 1 shows the period of the generation pattern of the 46KH2 component.

Table 1 This period is the S/11 circuit which samples and holds the ATF signal via the hysteresis amplifier 17 in synchronization with a certain phase of the 30PG mentioned above.
/+1 signal) (signal (e) in FIG. 1).

FIGS. 7 and 8 show timing charts of sampling signals in the S/11 circuit 2 and 5711 circuit 3, and timing charts of the field S/H signal, respectively. In this example, as described above, it is assumed that the tape feeding speed ratio of the SP mode to the P mode is 2:1, and the tape feeding speed ratio of the standard playback to the forward search and backward search is 1:9:-7.

As shown in Figure 8, if the recording and search playback modes match (SP-+SP, LP-LP), the field S/H signal is in a constant state of either "H" or "L". Become. On the other hand, if a record in LP mode is searched in SP mode, the field signal will invert the state every two fields, and if a record in SP mode is searched in LP mode, the field S/H signal will be inverted every four fields. This is a signal that is inverted to .

Now, the case where a tape recorded with an LP mote is searched for forward rotation and reverse rotation with an SP mote will be explained using the timing charts of FIGS. 7 and 8 and the block diagram of FIG. 1(a). The output (a) of the mono multivibrator 8 in FIG.
This is the output of the mono-multivibrator 9 which generates a pulse width of Δt in response to the falling edge of . Further, (E) is a field S/II signal obtained by sampling and holding the output signal of the hysteresis amplifier 17 at the rising edge of the output (B). That is, the output signal of the hysteresis amplifier 17 is sampled and held at a predetermined phase of the S/H circuit board field.

The 1/2 S/l-1 circuit 2 generates the field S/H signal (E) at the rising edge of the signal (C) obtained by dividing the output (B) by 1/2 using the 1/2 frequency divider 10. 1/4 5711 circuit 3 is a frequency divider 1
The output of 0 (c) is further divided by 1/2 by the 1/2 frequency divider 11, and the field S/
This circuit samples and holds the No. 11 signal (e).

Considering the case where a tape recorded with LP mote is searched with SP mote, the period of the field S/H signal is
Looking at the output of the S/H circuit 2, which has 4 fields and samples and holds every 2 fields, it is clear from Figure 8 or Table 1 that the output of the 1/2 S/H circuit 2 is transferred to the delay circuit 4. signal delayed by 2 fields (this is 1/2
S/fl (i)) and the output of the 1/2 5711 circuit 2 (which is referred to as 1/2 S/H (ii)) have the following relationship.

1/2 S/H (i) = 1/2 S/H (ii) Therefore, the output signal (
4) is in the "H" state.

On the other hand, when searching a tape recorded in SP mode using an LP mode, the period of the field S/H signal is 8 fields from Table 1, so 1/4 of the S/■ circuit 3
A signal obtained by delaying the output (g) of
It can be seen that the output of the /H circuit 3 (which is referred to as 1/4 S/H (ii)) has the following relationship: 1/4 S/H (i) = 1 ohm ding σ°C. Therefore, the signal recorded with SP mode is
When searching in P mode, the output signal (su) obtained by taking the exclusive OR of both in the EX-OR circuit 6b is “H”.
” becomes.

Also, if the motes at the time of recording and search playback match,
Does the field S/H signal vary depending on the sampling timing, or is the S/H signal the same and in phase for 30PG?
Then, it becomes stable at either "H" or "L". Therefore, it is clear that the two outputs (J) and (S) of the comparator circuit 6 are both L''. Therefore, if the two outputs (J) and (S) of the comparison circuit 6 match, the mote error signal that is the output of the judgment circuit 7 is “
It remains in the "L" state.

In other words, if the exclusive OR of the two outputs obtained by sampling and holding the field S/11 signal for each frame (J) is "H", the tape recorded in the LP mode is searched in the SP mode. It can be considered that the field S/H signal is sampled and held every two frames, and the exclusive OR is taken of the two outputs.
If it is in "H" state, it can be assumed that the tape recorded in SP mode is being searched in LP mode.
It is T-noh. The judgment circuit 7 takes into consideration the motes currently set by the system controller, and is configured with logic gates to avoid erroneous judgment operations. For example, if the signal (CH) is in the “H” state, that is, “LP-3P
Even if it is deemed that there is a mote error °C, the mode discrimination signal will not go to "H" unless the current mote or SP mote is present.Similarly, if the signal (S) or However, if the current mote is not an LP mote, it is assumed that the mote is malfunctioning and the mote discrimination signal is not changed.This prevents malfunctions such as non-recording portions from occurring.

In FIG. 1(b), 21 is a counter that counts the rising and low edges of the signal (d) that occurs in FIG. When the discrimination signal is "H", this is a counter that counts up at the rising edge of the signal (d), and 23 is the counter 2.
This judgment circuit is made up of logic gates that compare the count value of 2 with a predetermined number and set the mote error signal to "H" as described later.

Next, a detailed description will be given of a configuration for eliminating discrimination malfunctions using the circuit shown in FIG. 1(b).

Generally, a capstan is not controlled only by a speed control signal, but is servo-controlled by mixing a phase control signal such as an ATF signal.

In addition, the width of the head and installation may vary due to variations in position, etc.
If the mode is different between recording and reproducing, the mote discrimination signal does not always remain "H" and may become "L". At this time, when the system controller detects the mote discrimination signal, it is erroneously determined that they match, even though the recording and playback modes are actually different. Conversely, even though the modes are the same during recording and playback, it may be determined that the motes are different, resulting in a one-shot error.

Therefore, the counter 21 counts the falling edges of the signal (d) in FIG.
T l ), the counter 22 and judgment circuit 23 are reset. The counter 22 counts the number of times (HCONT) of the mote discrimination signal "H" of the period counter 22 corresponding to the set value (CONT l) determined by the counter 21. Then, the determination circuit 23 compares it with a predetermined determination reference number setting value (CONT2) to determine whether or not to raise the mote error signal to "H".

For example, if the setting value (CONTl) of the counter 21 is set to 6 times and the judgment reference number of times (CONT2) is set to 4 times, in an ideal state, the counted value of the counter 22 immediately before reset (HCONT) = CONTI>CONT2. .

However, as mentioned above, the head does not necessarily trace an ideal track pattern, so in reality, H
Since it is considered that CONT≦C0NT 1, as a means to prevent misjudgment, C0NT2 is set to allow two misjudgments out of six.
is set to 4, and the number of “H” of the mode discrimination signal (HCO
If NT) is -F four times or more, it can be determined that the motes used during recording and playback are different.

In the above embodiment, the tolerance rate for misjudgment is set to 173, or if this tolerance rate is set too low (for example, C0NT2=2), tracking deviation may occur even when the recording and playback modes match. It is conceivable that erroneous judgments such as tape dropout may also occur.

Therefore, by setting an appropriate setting value that satisfies C0NTl≧HCONT≧C0NT2, it is possible to eliminate misjudgment.

In this embodiment, the forward search is performed at 9 times the speed, and the reverse search is performed at the 7 times speed, and the normal recording mode and the long-time recording mode corresponding to 1/2 of the normal recording mode are selectively used for recording and reproduction. Consider a case in which the search speed is N times the recording speed (N is an integer) in the system.

In general, the tape speed during playback is (4n+1) times the speed during recording (
(n is an integer), the ATF signal has the same waveform in l field periods. Furthermore, when the tape speed during playback is (4n+3) times that during recording, the ATF signal has the same waveform in two field cycles, and the field S/H signal is inverted every 1 field]9. Also, the tape speed during playback is (4) during recording.
When the number is n) times or (4n+2) times, the ATF signal or the same waveform is generated every 4 fields, and the field SIN signal is inverted every 2 fields. Furthermore, when the tape speed during playback is (n + 1/2) times the speed during recording, the ATF signal has the same waveform at a period of 8 fields, and the field S/11 signal is inverted every 4 fields.

Here, if N is an odd number, when searching and playing back a tape recorded with SP mode using LP mode, (n +
1/2) times the tape speed, and when a tape recorded in the LP mode is searched and reproduced in the SP mode, the tape is played back at a tape speed 2n times the recording speed. Therefore, if the pitches during recording and playback are the same, the ATF signal will have a uniform waveform in at least two field cycles, so it is possible to use the circuit shown in Figure 1 to handle 16 different track pitches. . Incidentally, when using the mono multivibrator 8, the S/11 timing of the S/H circuit 1 is desirably set to a timing at which the absolute value of the ATF signal becomes larger by appropriately adjusting a constant.

In addition, this embodiment is not limited to high-speed search playback such as forward search and reverse search, but as is clear from the above explanation, the same circuit performs mode discrimination even during standard playback corresponding to N=1. Is possible. That is, if the mode matches in normal playback, field S/1! The signal is always in the “L” state, but if the mode is different, it will be “H” or “L”.
is repeated regularly, 1/2 S/41 circuit 2 and 1/4 S/11 circuit 3 are also regularly set to "H", '
Therefore, the 1,000-toe error signal also rises to H'', making it possible to determine the mode even during normal playback.

And the 1/2 S/11 circuit and the 1/4 S/11 circuit do not necessarily need to be sampled every 2 fields, every 4 fields (sample holes), but every 2 m fields and every 4 m fields (however m is All you have to do is sample and hold the sample (odd number). Therefore, the delay circuit 4.5
The respective delay times are a 2m field delay and a 4m field delay.

[Effects of the Invention] As explained below, two types of frequency components obtained by multiplying a plurality of types of reference signals having different frequencies in a predetermined rotation and a pilot signal reproduced by a rotating head. The track pitch is determined by sampling the level comparison output of the head at a predetermined rotational phase of the head and comparing the sampled link signals obtained within a predetermined period multiple times. The effect is that track pitch can be determined reliably and with high reliability regardless of the media running speed, and stable functionality can be obtained even in the face of flutter and playback output signal dropouts. big.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are block diagrams showing the configuration of the end portion of an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration for obtaining the ATF signal, FIG. 3, 41Δ, Figure 5, 6th
The figures each show the locus of the head and the track pattern in predetermined states, and FIGS. 7 and 8 are timing charts showing the waveforms of the 1N6 section, respectively. In the figure. 1.2.3 S/11 circuit 4, 5; Delay circuit 6: Comparison circuit 7 Two judgment circuits 8.9: Mono multi-biflator 10.11: Frequency divider 13.14: BPF15, 1
6: DET 17: Comparator 18: Hysteresis amplifier

Claims (1)

[Claims] In an apparatus for reproducing an information signal from a recording medium in which a plurality of types of pilot signals having mutually different frequencies are recorded together with the information signal in a predetermined rotation for each track, the information signal is reproduced from the reproducing rotary head in synchronization with the rotational phase of the reproducing rotary head. Multiplying the reproduced pilot signal by a plurality of types of reference signals having mutually different frequencies in a predetermined rotation, and sampling the resulting level comparison output of the two types of frequency components at a predetermined rotational phase of the head,
An information signal reproducing device characterized in that the track pitch of the track is determined by comparing the sampling signals obtained within a predetermined period a plurality of times.