JPH0785437A - Information reproducer - Google Patents

Abstract

PURPOSE:To speed up leading-in of tracking and to shorten the time for shift to a reproducing state. CONSTITUTION:The kind of a tracking pilot signal contained in a reproduction signal from a head 2b is discriminated by a pilot detecting discriminating part 6. A tracking part 7 switches over the polarity of a tracking error signal 24 prepared from a tracking pilot signal contained in a reproduction signal of a head 2a, on the basis of a discrimination signal 25, and uses that signal for a tracking control. According to this constitution, leading-in of tracking from the vicinity of an unstable point is eliminated and the tracking is led in to the nearest balance point. Therefore, the time for leading-in is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information reproducing apparatus for reproducing information such as images, sounds and data from a tape medium.

[0002]

2. Description of the Related Art In a reproducing apparatus for reproducing an information signal recorded as an oblique track on a tape, such as a video tape recorder, a rotary scan is usually performed by a rotary head. At that time, in order to obtain the reproduced signal correctly,
Tracking control is required to control the scanning position so that the head traces each track accurately. The ATF method is known as one means for this. For example, Japanese Patent Laid-Open No. 4-285746 discloses an example in which two kinds of tracking pilot signals having different frequencies are frequency-multiplexed with a data signal and recorded on a track on a tape, and tracking control is performed using this. Has been done.

[0003]

In such an information reproducing apparatus, when the reproduction is started, it is necessary to perform the pulling operation of the tracking control. If the transient response time until completion of the pulling operation at this time is long, the responsiveness of the device is deteriorated. By the way, in the conventional information reproducing apparatus using the pilot signal, the control polarities do not match because the tracking error detection characteristics have zero cross points (equilibrium points) having polarities different from each other as shown in FIG. 3B, for example. If the pull-in is started near the unstable zero-cross point, it takes a long time to complete pull-in.

In view of the above problems, it is an object of the present invention to provide an information reproducing apparatus having excellent responsiveness by speeding up the transition to the reproducing state.

[0005]

In order to solve the above-mentioned problems, the information reproducing apparatus of the present invention cyclically records two or more kinds of tracking pilot signals of different frequencies in a cycle of four tracks or more selectively. An information reproducing apparatus for reproducing a signal by rotating a head mounted on a rotating cylinder on a tape medium, wherein the first head and a scanning locus of the first head are tracked by about one track. A tracking pilot signal amplitude is detected from the reproduction signal of the second head that scans at a position displaced in the width direction and the reproduction signal of the first head, and based on this, the tracking pilot mainly included in the reproduction signal of the first head. Pilot detection and identification means for identifying a signal and outputting an identification signal, and a reproduction signal from the second head are used to detect a track adjacent to both scanning tracks. A tracking error signal detecting means for detecting a tracking pilot signal amplitude recorded in the clock, and creating and outputting a tracking error signal based on the amplitude, and a tracking means for performing tracking control based on the tracking error signal and the identification signal. Be prepared.

[0006]

According to the present invention having the above structure, the type of the tracking pilot signal included in the reproduction signal of the first head is identified by the pilot detection identification means, and is created from the tracking pilot signal included in the reproduction signal of the second head. By switching the polarity of the tracking error signal based on the identification result and using it for tracking control,
Since the pull-in is always performed to the closest equilibrium point, it is possible to speed up the transition to the reproduction state.

[0007]

Embodiments of the information reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of an information reproducing apparatus according to an embodiment of the present invention. In FIG. 1, 1
Is a magnetic tape (tape), 2a and 2b are magnetic heads having different azimuths, 3 is a cylinder, 4 is a cylinder control unit, 5 is a tracking error detection unit, 6 is a pilot detection identification unit, 8 is a capstan control unit, Reference numeral 9 is a capstan motor, 10 is a capstan, 11 is a pinch roller, and the block 7 shown by a broken line constitutes a tracking unit. The information reproducing apparatus configured as described above will be described with reference to FIGS.

FIG. 2 schematically shows a track pattern recorded on the tape 1. The symbols "f1" and "f2" shown in each diagonal track indicate the type of the tracking pilot signal recorded on the track data in a superimposed manner. That is, the first tracking pilot signal (f1) and the second tracking pilot signal (f2) having a frequency different from the first tracking pilot signal are alternately recorded every other track. Further, "-" indicates that the tracking pilot signal is not recorded.

Tape 1 having tracks formed in this way
Is wound around the cylinder 3 for a period of about 180 degrees, sandwiched between the capstan 10 and the pinch roller 11, and runs in the longitudinal direction thereof. Cylinder 3 is cylinder control unit 4
The rotation is controlled to a predetermined rotation speed by. The rotation of the capstan motor 9 directly connected to the capstan is controlled by the capstan control unit 8 so that the tape 1 advances by one track during the half rotation period of the cylinder 3. The heads 2a and 2b are mounted at 180 ° opposite positions as shown in FIG. 1, and scan the tape as the cylinder 3 rotates. With this configuration, each head scans a position displaced by one track from each other as shown in the lower part of FIG. The cylinder control unit 4 also detects the rotational phase of the cylinder 3 and identifies the head that is in contact with the tape 1 by a high level and low level binary head switch signal 23.
Is output. The head switch signal indicates a period in which the head 2a is in contact with the tape when it is at a high level and the head 2b is in contact when it is at a low level.

The reproduced signal 22 from the head 2a is input to the tracking error detector 5. FIG. 3A shows the amplitude of the tracking pilot signal included in the reproduction signal when the scanning position of the head is plotted on the horizontal axis. The broken line indicates the track boundary, and the type of the tracking pilot signal recorded is shown at the upper part. The tracking error detector 5 includes f included in the reproduced signal.
The amplitudes of the 1 and f2 components are detected and their difference (f1 component amplitude −
The f2 component amplitude) is output as the tracking error signal 24. The tracking error signal has a detection characteristic as shown in FIG.

The tracking unit 7 performs tracking control so that the tracking error signal becomes 0, and in this example, controls the rotational speed of the capstan. However, as is clear from the track pattern of FIG. 2, the tracking pilot arrangement of the adjacent tracks is switched every time the head 2a is scanned, so that the polarities of the tracking error signals are inverted like the scanning positions a1 and a2 shown in FIG. . Therefore, in order to keep the control polarity constant, the polarity is inverted (switching between inversion and non-inversion) for each scan and then added to the speed control system of the capstan.

By the way, the scanning state shown in the lower part of FIG. 3, that is, the head 2a is a1, a2, ..., The head 2b is b.
The polarity of the control system is completely inverted even if the tracking error signal is 0, depending on which of scanning a1 and scanning a2 is inverted in the state of sequentially scanning positions 1, b2, .... To do. That is, one is stable,
The other becomes unstable, and if left unattended, a pull-in operation occurs up to a position of opposite polarity which is offset by two tracks, and finally a stable state is reached. Further, in that case, a very long time is required as compared with the case where the tracking error signal is pulled in in a linear range with respect to the head position deviation. It cannot be determined from the reproduction signal 22 from the head 2a whether it is at a stable point or at an unstable point.

However, in the reproduced signal 21 of the head 2b, the tracking pilot f1 is dominant at the scanning position b1 and the tracking pilot f2 is dominant at the scanning position b2, so that it is possible to distinguish between these two states. The pilot detection / identification unit 6 uses the reproduction signal 21 from the head 2b.
Is input, the tracking pilot signal mainly contained therein is identified, and the result is output as an identification signal 25. As a configuration, for example, as shown in FIG. 4, a tracking error detection unit 13 (equivalent to the tracking error detection unit 5) and a pilot identification unit 12 that determines the level (positive / negative) and outputs the result as an identification signal. It can consist of and. The detection characteristic of the identification signal obtained as a result is shown in FIG.
It becomes like (c). That is, it is shown that f1 is dominant at the high level and f2 is dominant at the low level. Further, the pilot identifying unit 12 holds the immediately preceding output during a period in which the reproduction signal from the head 2b is not obtained, that is, during the scanning period of the head 2a.

The tracking unit 7 switches the control polarity according to the value of the identification signal 25. The simplest configuration is to set inversion / non-inversion directly from the value of the identification signal.
With this configuration, the polarity reversal operation in the tracking unit is always in a stable control state. Alternatively,
The inversion / non-inversion is not performed every cylinder rotation, and the switching phase may be modified so that the identification signal 25 and the inversion / non-inversion switching have a predetermined relationship. At this time, when the identification signal 25 and the inversion / non-inversion switching are not in a predetermined relationship, the switching polarity may be corrected after confirming that the state has been maintained for a certain period. This makes it possible to avoid instability (erroneous determination due to noise) of the identification signal 25 when the tracking is deviated and the tracking pilot signal level in the reproduced signal is low, which is preferable from the viewpoint of operation stability. However, the entire pull-in operation time is required to be long only during the confirmation period.

Further, even when the scanning position is deviated from the positions a1 to b2 in FIG. 3, the identification signal 25 has the same value in the range of ± 1 track, so that the pulling operation is always performed to the closer zero cross point. Be seen. That is, the pull-in is always performed in the shortest path, and the time required for the pull-in is the shortest.

As described above, according to this embodiment, the head 2
The type of the tracking pilot signal included in the reproduced signal from b is identified by the pilot detection identifying unit 6, and the tracking unit 7 identifies the polarity of the tracking error signal 24 created from the tracking pilot signal included in the reproduced signal of the head 2a. By switching based on the signal 25 and using it for tracking control, pulling to the closest equilibrium point is always performed, so that the transition to the reproduction state (tracking pull-in) can be speeded up.

Next, a second embodiment of the present invention will be described with reference to FIG.
And FIG. 6 will be described. FIG. 5 is a block diagram showing a more simplified configuration in the case where the pilot detection / identification unit of FIG. 1 has the configuration of FIG. The tracking error detection unit 13 included in the configuration of FIG. 4 is a block that is completely equivalent to the tracking error detection unit 5 of FIG. 1, so these are combined into one and the reproduction signals of the heads 2a and 2b are shared by time division. The processing is simplified to simplify the configuration. The switch 14 is a block added for that purpose, and is operated by the head switch signal 23 to select and combine the reproduction signals obtained from the heads 2a and 2b alternately in a time division manner. In this case, when the head switch signal 23 is at a high level, the switch 14 operates to select the terminal a and at the low level to select the terminal b. The arrangement of the tracking pilot signal on the tape is also as shown in FIG. The track on which the tracking pilot signals f1 and f2 are recorded has the same azimuth as the head 2b, and the track on which the tracking pilot signals are not recorded has the same azimuth as the head 2a.
The tracking pilot signal detection characteristic in the case of such a configuration is 2a because the tracking pilot signal is selected at a low frequency that is not easily affected by azimuth loss.
2b is almost the same for both heads and is the same as in FIG.

FIG. 6 shows the signal waveform of each part of FIG.
(A) is a head switch signal 23, which shows a period in which the head 2a is reproducing a signal from the tape in a high level period and the head 2b is in a low level period. (B) is a tracking error signal 24 detected by the tracking error detector 5 from the reproduction signal 26 switched by the head switch signal 23. The polarity is (f1-f2) and head 2
The scanning position of b is shown in a state where the tracking pilot signal shown in the upper part of FIG. Therefore, the level of the tracking error signal (b) is high during reproduction of the f1 track, low during the reproduction period of the f2 track, and almost zero during the scanning period of the head 2a. The capstan controller 8 samples the tracking error signal (b) during the period when the head switch signal is at the high level as shown in FIG. 6 (c). On the other hand, the pilot identification unit 12 samples the tracking error signal (b) during the period when the head switch signal is at the low level, as shown in FIG. 6 (d). Pilot level identification unit 1
In 2, the processing of ( _Equation 1) is applied to these sampling values S _ij .

[0020]

[Equation 1]

That is, the sum of the sampled values in each scanning period is obtained, and the difference between this and the summed value in the previous scanning is obtained.
As shown in FIG. 6 (b), this calculation is a process for avoiding the influence of a noise component generally superimposed on the tracking error signal. The positive / negative of the calculation result is determined and an identification signal is output. In this example, positive is high level, and negative is low level. The output value is held until the next discrimination result is obtained after one cycle of the head switch signal. In addition,
When applying to a system in which the noise component is sufficiently small, the process of (Equation 1) may be omitted and the determination may be made directly from one sample.

In the capstan control unit 8, the sampling tracking error signal is subjected to polarity switching processing, for example, non-inversion at high level and inversion at low level, according to the identification signal value at that time, and then the capsulation control processing is performed. Tracking control is realized by adding to the stun speed control loop. At this time, the switching polarity is set so that tracking control becomes stable. Of course, as in the example of FIG. 1, the switching itself is switched between inversion and non-inversion for each rotation of the cylinder (that is, based on the 1/2 frequency-divided signal of the head switch signal), and the identification signal and the switching polarity have a predetermined relationship. If not, the identification signal may be reflected in the switching polarity when the state continues for a certain period (for example, n scanning period, n is an integer).

As described above, according to this embodiment, the head 2
Tracking error detection unit 5 based on reproduced signals from a and 2b
After the tracking error signal is detected by, the pilot identifying unit 12 identifies the type of the tracking pilot signal included in the reproduction signal during the scanning period of the head 2b using the tracking error signal, and the tracking unit 7 causes the head 2
By switching the polarity of the tracking error signal 24 generated from the reproduction signal in the scanning period of a based on the identification signal 25 and using it for tracking control, the pulling to the closest equilibrium point is always performed, so that the reproduction state is changed. A faster transition (tracking pull-in) can be realized. Further, since a part of the pilot detection identification section is shared with the tracking error detection section, it can be realized with a simpler configuration.

The embodiment is only one example of the present invention. Regarding the arrangement of tracking pilots, an example in which two types of pilot signals are alternately arranged every other track has been shown, but the present invention is not limited to this, and for example, 8
It can also be applied to the case where four types of pilot signals are sequentially arranged over four tracks such as a milliVTR.

The head arrangement on the cylinder is not limited to two heads. The present invention can be similarly applied if there is a head pair that scans the tape by shifting one track from each other.

[0026]

As described above, in the information reproducing apparatus of the present invention, a tape medium on which two or more kinds of tracking pilot signals of different frequencies are selectively recorded cyclically in a cycle of four tracks or more, An information reproducing apparatus for reproducing a signal by rotationally scanning a head mounted on a rotary cylinder, the position being deviated from the scanning locus of the first head in the track width direction by approximately one track. And a tracking pilot signal amplitude is detected from the reproduction signal of the second head for scanning
Based on this, pilot detection / identification means for identifying the tracking pilot signal mainly contained in the reproduction signal of the first head and outputting the identification signal, and the reproduction signal of the second head from the reproduction signal of the second head to the tracks adjacent to the scanning track. A tracking error detection unit that detects the recorded tracking pilot signal amplitude and creates and outputs a tracking error signal based on the amplitude is provided, and a tracking unit that performs tracking control based on the tracking error signal and the identification signal. Since the pull-in from the vicinity of the unstable point that takes a long time is eliminated and the pull-in to the closest equilibrium point is always performed, the speed of transition to the reproduction state (tracking pull-in) can be realized.

Further, the first tracking pilot signal and the second tracking pilot signal having a frequency different from that of the first tracking pilot signal are alternately recorded on every other track on the tape medium on the rotating cylinder. An information reproducing apparatus for reproducing a signal by rotationally scanning an attached head, the information reproducing apparatus being mounted on the rotating cylinder and having the same azimuth as the track on which the first and second tracking pilot signals are recorded. And a second head that has the same azimuth as the track on which the first and second tracking pilot signals are not recorded and that scans at a position that is displaced from the scan trajectory of the first head by approximately one track in the track width direction. , The first and second heads are reproduced from the reproduction signals obtained in a time division manner alternately. And a second tracking pilot signal amplitude, and a tracking error detecting means for creating and outputting a tracking error signal based on the amplitude, and a tracking pilot mainly included in the reproduction signal of the first head based on the tracking error signal. By providing a pilot identifying means for identifying a signal and outputting an identifying signal, and a tracking means for performing tracking control based on the tracking error signal and the identifying signal, with a simpler configuration than the configuration of the invention described above, It is possible to realize an information reproducing device that can be rapidly shifted to the reproducing state.

The tracking error detecting means outputs the difference between the detected amplitudes of the first and second tracking pilot signals as a tracking error signal, and the pilot identifying means outputs the tracking error signal level of the first head during two scanning periods. By identifying the tracking pilot signal based on the difference, the noise component that is superimposed on the tracking error signal is suppressed and the pilot is identified accurately, so that the stability and reliability of pull-in can be improved. Therefore, it is possible to provide an information reproducing apparatus having a short state transition time and excellent responsiveness to scanning.

[Brief description of drawings]

FIG. 1 is a block diagram of an information reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a track pattern diagram according to an embodiment of the present invention.

FIG. 3 is a signal waveform diagram for explaining an embodiment of the present invention.

FIG. 4 is a configuration diagram of a pilot detection / identification unit according to the present invention.

FIG. 5 is a block diagram of an information reproducing apparatus according to a second embodiment of the present invention.

FIG. 6 is a signal waveform diagram for explaining an embodiment of the present invention.

[Explanation of symbols]

 1 Tape 2a, 2b Head 3 Cylinder 4 Cylinder Control Section 5 Tracking Error Detection Section 6 Pilot Detection Identification Section 7 Tracking Section 8 Capstan Control Section 12 Pilot Identification Section 14 Switch

Claims (5)

[Claims] 1. A head mounted on a rotary cylinder is rotationally scanned with respect to a tape medium on which two or more kinds of tracking pilot signals of different frequencies are selectively recorded cyclically in a cycle of four tracks or more. An information reproducing apparatus for reproducing a signal by means of: a first head; a second head for scanning a position displaced from the scanning locus of the first head by approximately one track in the track width direction;
Pilot detection / identification means for detecting a tracking pilot signal amplitude from the reproduction signal of the head, identifying the tracking pilot signal mainly included in the reproduction signal of the first head based on the amplitude, and outputting the identification signal.
Tracking error detection means for detecting the tracking pilot signal amplitude recorded on tracks adjacent to the scanning track from the reproduction signal of the second head, and creating and outputting a tracking error signal based on the amplitude, and the tracking error signal. An information reproducing apparatus, comprising: a tracking unit that performs tracking control based on the identification signal. 2. A tape cylinder on which a first tracking pilot signal and a second tracking pilot signal having a frequency different from that of the first tracking pilot signal are recorded alternately on every other track, on a rotating cylinder. An information reproducing apparatus for reproducing a signal by rotationally scanning an attached head, which scans a position which is deviated from the scanning locus of the first head by approximately one track in the track width direction. A second head and the first
Detecting the amplitudes of the first and second tracking pilot signals from the reproduction signal of the head of the
The pilot detection and identification means for identifying the tracking pilot signal mainly included in the reproduction signal of the head and outputting the identification signal, and detecting the first and second tracking pilot signal amplitudes from the reproduction signal of the second head,
An information reproducing apparatus comprising: a tracking error detecting means for creating and outputting a tracking error signal based on this; and a tracking means for performing tracking control based on the tracking error signal and the identification signal. 3. A tape cylinder on which a first tracking pilot signal and a second tracking pilot signal having a frequency different from that of the first tracking pilot signal are recorded alternately on every other track, on a rotating cylinder. An information reproducing apparatus for reproducing a signal by rotationally scanning a mounted head, comprising: a first head having the same azimuth as a track on which first and second tracking pilot signals are recorded; A second head which has the same azimuth as the track on which the second tracking pilot signal is not recorded, and which scans at a position which is displaced from the scanning locus of the first head by approximately one track in the track width direction; The first and second tracking pyros are reproduced from the reproduction signals obtained from the second head in a time division manner. Error detection means for detecting a tracking signal amplitude and creating and outputting a tracking error signal based on the detected tracking signal amplitude, and a tracking pilot signal mainly included in the reproduction signal of the first head based on the tracking error signal. An information reproducing apparatus comprising: pilot identifying means for outputting an identifying signal; and tracking means for performing tracking control based on the tracking error signal and the identifying signal. 4. The tracking means switches the polarity of the tracking error signal in the second head scanning period based on the identification signal and uses the tracking error signal for tracking control. Information reproducing apparatus described. 5. A tracking error detecting means outputs the difference between the detected amplitudes of the first and second tracking pilot signals as a tracking error signal, and a pilot identifying means outputs the tracking error signal of two scanning periods of the first head. 4. The information reproducing apparatus according to claim 3, wherein the tracking pilot signal is identified based on the level difference.