JP3162933B2 - Recording / reproducing apparatus and tape position searching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus and a tape position searching method, and more particularly to a recording / reproducing apparatus and a tape position searching method having, for example, a high-speed search function and used for a digital VTR or the like.

[0002]

2. Description of the Related Art In conventional analog video such as VHS (registered trademark), when a high-speed search is performed, CTL pulses by a fixed head or pulses generated by a FG of a reel motor or a sensor attached to a reel are counted. As a result, a search was performed by calculating the amount of travel of the tape to find the target position.

On the other hand, there is a digital VTR as a next-generation VTR whose standards are currently being studied separately from these. Since the digital VTR aims at miniaturization of the cassette and the mechanism, the use of a conventional CTL head or reel motor which is not suitable for miniaturization of the apparatus may damage the standard. Therefore, in the digital VTR, the conventional method using the CTL pulse cannot be adopted, and instead of the CTL servo,
A specification is adopted in which ATF servo is performed by a digital pilot signal digitally multiplexed on the main track.

[0004] In the case of a digitally recorded tape,
When the tape is fed at a high speed, the relative speed between the head and the tape greatly changes, so that the PLL of the clock generation circuit for detecting data cannot follow and the data cannot be detected. Therefore, in order to correct this, as shown in FIG. 7, a high-speed search is realized by changing the rotation speed of the cylinder over a wide range and changing the relative speed of the head so as to enter the capture range of the PLL. Was.

As an example, Table 1 shows the relationship between the cylinder rotation speed and the tape speed at the time of cylinder rotation correction.

[0006]

[Table 1]

In this case, if the tape feed double speed is about ± 20 times, the correction rate of the cylinder rotation number is about ± 4%, and the capture range of the PLL is slightly improved without correcting the cylinder rotation number. Then the data can be detected. Generally, in normal reproduction by a digital recording / reproducing apparatus, the capture range of the PLL is sufficient if the operating frequency is ± 2 to 3%.

[0008]

However, when it is necessary to reproduce data such as subcodes at the time of high-speed search, a capture range as wide as the operating frequency ± 10% or more is required. It is technically very difficult to expand the capture range of the PLL at a high frequency. Therefore, for example, in a high-frequency PLL circuit whose operating frequency is as high as 42 MHz, it is necessary to extremely reduce the delay time in the loop in order to secure a wide capture range.
This is a very difficult task.

[0009] For this purpose, as a means for high-speed search,
It is necessary to greatly change the cylinder speed. However, with this, noise, vibration, electric power, and noise increase respectively, and the structure of the motor, the structure of the mechanism, and the EMI countermeasures need to be reviewed, which increases the cost. In addition, naturally, the servo circuit and the control circuit also become complicated.

Therefore, a main object of the present invention is to provide a recording / reproducing apparatus which can perform a high-speed search with a simple and low-cost circuit.

[0011]

According to a first aspect of the present invention, there is provided a first search means for feeding a tape based on a track crossing pulse, a second search means for sending a tape to a target position based on position information recorded on the tape, And selecting means for selecting either one of the first searching means and the second searching means based on the position of the tape.
Envelope detection that detects the envelope of the signal from the
Means, traverse the pulse by pulsing the envelope
Pulsing means to obtain a track crossing pulse
Position detecting means for detecting the position of the tape based on the
And a recording / reproducing apparatus.

A second invention is a tape position searching method for searching for a tape position from a current position to a target position, wherein (a) a step of feeding the tape and detecting the tape position based on a track crossing pulse; and (b) A) a tape position searching method comprising, when the tape position reaches a predetermined switching point, feeding the tape to a target position based on position information recorded on the tape.

[0013]

First, the tape is fed at a high speed by the first search means based on the track crossing pulse. At this time,
The envelope of the signal from the tape is detected by the envelope detecting means. The detected envelope is pulsed by pulsing means to obtain a track crossing pulse. The position detecting means detects the position of the tape based on the count of the track crossing pulse.

When the tape position reaches a predetermined switching point, the selection means selects the second search means. Thereafter, the tape is sent to the target position with high accuracy by the second search means based on the position information recorded on the tape. Thus, in the first search means,
Since the search is performed without using the position information recorded on the tape, high-speed search can be performed even if a part of the information recorded on the tape cannot be picked up. Then, when approaching the target position, the mode is switched to the second search means, and the search is performed using the position information recorded on the tape, so that the target position can be accurately converged. That is, the search can be performed at high speed and with high accuracy.

This recording / reproducing apparatus can be used for a digital VTR.

[0016]

According to the present invention, only by combining the high-speed first search means and the high-accuracy second search means,
High-speed search can be realized with a simple and low-cost circuit. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0017]

Referring to FIG. 1, a recording / reproducing apparatus 10 of this embodiment is used, for example, in a digital VTR. The recording / reproducing apparatus 10 includes a recording / reproducing head 14 that scans on a tape 12. The signal read by the recording / reproducing head 14 is amplified by a recording / reproducing amplifier 16 and sent to a waveform equalizing circuit 18. The waveform equalizing circuit 18 shapes the amplitude and phase characteristics of the read signal so that it can be easily identified as the original "1" or "0". Waveform equalization circuit 1
8 is supplied to a PLL circuit 20, a clock component is extracted and a clock is reproduced, and a data detection circuit 22
Given to.

The data detection circuit 22 restores the signal from the waveform equalization circuit 18 to digital data at a given clock timing, and supplies the digital data to the SYNC / ID detection circuit 24. The SYNC / ID detection circuit 24 detects the SYNC / ID in the track, and the data reproduction circuit 26 reproduces various data in the track, and the signal processing circuit 28
Given to. In the signal processing circuit 28, signals (video, audio, etc.) in the track are restored. Further, a subcode is provided from the data reproducing circuit 26 to the servo circuit 30.

The following points should be noted with respect to the present invention. That is, the signal from the recording / reproducing amplifier 16 is supplied to the envelope detection circuit 32. The envelope detection circuit 32 detects the envelope of the RF signal. This envelope has an abacus ball shape corresponding to the tape feeding speed. The envelope-detected signal is pulsed by the pulse generator 34 to obtain a track-crossing pulse. Then, the number of track crossing pulses is counted by the pulse counter 36, and the counted number is given to the control microcomputer 38. A key input circuit 40 is connected to the control microcomputer 38, and a target position to be searched is input from the key input circuit 40. In the control microcomputer 38,
A signal corresponding to the given target position and count number is given to the servo circuit 30. The servo circuit 30 provides a control signal for controlling a cylinder motor, a capstan motor, a reel motor, and the like to the mechanism 42 based on the subcode from the data reproduction circuit 26 and a signal from the control microcomputer 38. The mechanism 42 runs the tape 12 based on the provided control signal.

In such a recording / reproducing apparatus 10, the locus of the recording / reproducing head 14 as viewed from the tape 12 side when the tape 12 is run at high speed in the FF (fast forward) and REW (rewind) directions respectively is shown in FIG. As shown in
The recording / reproducing head 14 traverses a plurality of tracks. As an example, in azimuth recording with two 180 ° facing heads, Bc
No output of the h track is output, and similarly, no output of the Ach track is output from the Bch head.

In the FF direction at N times speed, the recording / reproducing head 14 detects (N-1) abacus ball-shaped signals per one rotation of the cylinder. Further, in the REW direction at −N times speed, the recording / reproducing head 14 detects (−N + 1) abacus ball-shaped signals. As shown in FIG. 3A, a signal in the form of an abacus ball related to the feed speed is detected by the recording / reproducing head 14 for each rotation of the cylinder. After being amplified by the recording / reproducing amplifier 16, it is envelope-detected by an envelope detection circuit 32 as shown in FIG. 3B, and formed into a pulse by a pulse-forming circuit 34 as shown in FIG. Obtain a transverse pulse. FIG. 3 shows the contact between the recording / reproducing head 14 and the tape 12 (hereinafter, referred to as a contact)
(Referred to simply as “head touch”).

The track crossing pulse is counted by the pulse counter 36, and the counted value is
8 to detect the running distance, that is, the position of the tape 12. If shown in FIGS. 4A and 4B,
Even when the head touch becomes unstable during high-speed running and only a part of the track can obtain an envelope, the track crossing pulse (FIG. 4C) of the part ENV-OK where the envelope is normally obtained is obtained. Counted, RF
The ratio with the -SW pulse is determined. Then, it is converted into the number of pulses in the entire period, and track crossing pulses for all tracks are obtained.

According to the present invention, the tape 12 is caused to run at high speed based on the information based on the track crossing pulse, the position information before the high-speed search and the information on the target position. And
The tape feed speed is switched to a value within the PLL capture range near the target position, and the tape 12 is fed to the target position based on the position information recorded on the tape 12, thereby realizing a high-speed search.

That is, as shown in FIG. 5, first, during high-speed running, rough tape feed is performed based on the track crossing pulse, and near the target position, the tape feed speed is changed to fall within the capture range of the PLL circuit 20. The search is performed while reading the position information (track number, frame number, etc.) recorded on the tape 12. The operation of the recording / reproducing device 10 will be described with reference to FIG.

First, in FIG. 6, when reproduction is started, a target position to be searched is input from the key input circuit 40 in step S1, and the current position is confirmed in step S3. Then, in step S5,
The number of tracks from the current position to the target position is calculated by the control microcomputer 38. For example, in a 525/60 system in the digital VTR standard, 1 second = 30 frames = 300 tracks. Therefore, one hour =
3600 seconds = 108,000 frames = 1,080,0
00 tracks. Here, the number of tracks = track crossing pulse holds.

Next, in step S7, the tape is fed based on the track crossing pulse. Step S9
At step S11, it is checked at step S11 whether or not the counted number, that is, the tape position has reached a switching point determined by the following equation (3).
If step S11 is "NO", the process returns to step S9, and if "YES", the process proceeds to step S13.

In step S13, the tape is fed based on the position information recorded on the tape 12.
Then, in step S15, the tape 1 is moved to the target position.
It is determined whether 2 has been sent. If "NO" in the step S15, the process returns to the step S13, and if "YES", the process ends. The relationship between the parameters is shown in Equations 1 to 3.

[0028]

(Equation 1)

[0029]

(Equation 2)

[0030]

(Equation 3)

T: distance traveled by tape (total tape)
Feed length) T₁₀₀: Destination position (100%) T₀ : Current position (0%) T_S : Switching point of tape feed t: Search time (time required for access) S₂₀₀: Tape feed double speed based on track crossing pulse S₂₀ : Tape feed double speed based on tape position information t₂₀₀: Time of tape feed based on track crossing pulse t₂₀ : Based on the tape position information, the tape feed time based on the track crossing pulse is 3
Number S₂₀₀, Tape feed double speed S based on tape position information
₂₀, Search time t, destination position T₁₀₀, Current position T ₀Is set
If this is done, the tape feed switching point T_SIs set
It is understood that it is.

[0032]

[Table 2]

As can be seen from Table 2, the tape feed double speed based on the track crossing pulse is 200 times, and the tape feed double speed based on the position information recorded on the tape 12 is 20 times.
If it is doubled, when prolonged high speed search of 1-4 hours, rapid search by setting a percentage of the total tape feed length T of switching point T _S of the tape feed the (T _S / T) to less than 0.95 Can be realized. The ratio of the tape feed switching point T _{S to} the total tape feed length T (T _S /
As T) approaches 1, the search time can be reduced,
Starting of the motor (not shown), the response characteristics and, more considering the time loss during the reverse rotation, the ratio of total tape feed length T of switching point T _S (T _S / T) is 0.95
Range is considered to be optimal.

Here, the case where the tape feed double speed based on the track crossing pulse is 200 times and the tape feed double speed based on the position information recorded on the tape 12 is 20 times has been described. It goes without saying that the number, ie the speed, is not limited to this value. Also,
The present invention can be applied to any VTR other than the digital VTR as long as the VTR does not use a CTL pulse (for example, an 8 mm system).

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is an illustrative view showing a locus of a recording / reproducing head during high-speed running of a tape;

FIG. 3 is an illustrative view showing an envelope, an envelope detection output, and a track crossing pulse (when head touch is good) during high-speed running.

FIG. 4 is an illustrative view showing an envelope, an envelope detection output, and a track crossing pulse (when head touch is unstable) during high-speed running.

FIG. 5 is an illustrative view showing a search method according to the embodiment;

FIG. 6 is a flowchart showing the operation of this embodiment.

FIG. 7 is an illustrative view showing a conventional search method;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Recording / reproducing apparatus 12 ... Tape 14 ... Recording / reproducing head 16 ... Recording / reproducing amplifier 18 ... Waveform equalizing circuit 20 ... PLL circuit 22 ... Data detecting circuit 24 ... SYNC / ID detecting circuit 26 ... Data reproducing circuit 28 ... Signal processing Circuit 30 ... Servo circuit 32 ... Envelope detection circuit 34 ... Pulsing circuit 36 ... Pulse counter 38 ... Control microcomputer 40 ... Key input circuit 42 ... Mechanism

Claims (3)

(57) [Claims] A first search means for feeding a tape based on a track crossing pulse; a second search means for sending the tape to a target position based on position information recorded on the tape; and the first search means and the first search means. (2) selecting means for selecting one of the search means based on the position of the tape , wherein the first search means includes an envelope for detecting an envelope of a signal from the tape.
Rope detection means, pulsing the envelope to generate a track crossing pulse
Pulsing means for obtaining and the power of said cross-track pulse.
Position detection for detecting the position of the tape based on the und
Recording / reproducing apparatus including means . 2. A digital VTR according to claim 1.
The recording / reproducing apparatus according to claim 1. 3. A tape position searching method for searching a tape position from a current position to a target position, comprising: (a) a step of feeding a tape and detecting a tape position based on a track crossing pulse; When a certain switching point is reached,
A tape position search method, comprising: feeding a tape to a target position based on position information recorded on the tape.