DE19581346C2 - Digital video tape recording appts. with high speed reproduction mode - Google Patents

Abstract

A video tape recorder device using a rotary head (103) has a recording signal processing section (111) which processes digital signals in such a way that data to be reproduced at high speed are recorded at dispersed positions on a number of tracks, and are arranged along the rotary head scanning locus. A mark adding section (113) generates marks indicating the track positions of the data and adds the marks to a control signal. A control head (105) records and reproduces the control signals, and a mark detecting section (117) reads the marks from the reproduced signals. A phase comparing section (116) detects phase difference between the marks and a reference signal synchronised with the rotary head rotation. A capstan servo (115) then controls the speed of the tape to set the phase difference at a prescribed reference value.

Description

The present invention relates to magnetic recording / reproduction device, especially a digital video recorder (VTR: Video Tape Recorder), for recording / playing back a digital image signal Use of a rotary magnetic head and also for tracking a variable speed playback, the playback being drifted at a given speed higher than a normal one Playback speed is performed.

Due to the rapid advances in digital technology in the In recent years there has been an increasing trend towards digital processing processing or digitizing a variety of information for the purpose of Storage and transfer as well as their reuse.

Among other things, digitization techniques for audio information or Signals developed early. In fact, digital audio products are like so-called compact disks (CD) already on the market and in technology well known.

On the other hand, in the areas of broadcasting and news the digitization of the image or video signal a remarkable  Progress made. Indeed, in the United States and other countries digital broadcast accompanying the progress in image coding and Compression techniques have been put to practical use.

Under these circumstances is now the development of a digital video recorder in progress. An example is used to try a digital up draw using a so-called VHS (Video Home System) Realize system video recorders, which act as video recorders for the Home use is popular. In this context, if the digital video or picture signal from the VCR, like for example, the VHS system video recorder actually recorded to be, one has to be from the standpoint of recording quality, one Recording time, a large amount of use of the magnetic tape and other factors necessarily from the image encoding or compression make use of techniques.

As one of the image compression (or coding) techniques may be an example MPEG (abbreviation of Moving Picture Experts Group) called system by the ISO (the International Organization for Standardization tion) is recommended. Include many of the image compression techniques The above-mentioned MPEG scheme becomes an inter-frame correction lation (that is, correlation between the frames) used to make a to achieve high image compression ratio without deterioration to suffer in the image or image quality. In other words, it becomes used such a characteristic that the picture or scene of one Frame to another frame is hardly subject to change as long as these are consecutive. With such an image compression technique the amount of data can be significantly reduced because coding le diglich the difference between two consecutive frames  is what, however, leads to the problem that only the image of subsequent frames is allowed to be reproduced.

If a variable speed playback with the Ver video or image data recorded by the video recorder the data is reproduced by a rotary magnetic head ben that is moved over the tracks. As a result, the below Use playback at variable speed Image data is not obtained as the data from successive frames will. Because of this, it was previously impossible to play with variable speed of the image to realize if this before opening drawing by the video recorder undergoing compression processing was pulled.

As a recording / playback method that uses image compression / coding technology nik used according to the MPEG scheme and compatible with the variable-speed playback, for example "FAST SCAN TECHNOLOGY FOR DIGITAL VIDEO TAPE RECORDS: IEEE Trans actions on Consumer Electronics, Vol. 39, No. 3, (AUGUST 1993) "he be imagined.

According to this system, the image data for the speed variable Playback independently and at specific or specific positions or Locations that match the scan path of the playback head and that depend on the running speed of the magnetic tape on the magnet band recorded recorded. By performing intra-frame compression The data for variable speed playback can be the image of the reproduced data (i.e. data compression within the Frame), which corresponds to the one frame for the speed dependent playback are intended to be restored.  

An exemplary data arrangement or structure on a magnetic tape, which results from the recording according to the aforementioned scheme, is shown in FIG. 9.

In Fig. 9, reference numeral 104 denotes a magnetic tape, 402 denotes a scanning path followed by the rotary magnetic head in a normal playback mode, 403 denotes a scanning path which is used in a triple-speed playback (i.e., in the playback, the at followed by a speed three times the normal or standard playback speed), 404 denotes a scanning path of the rotary magnetic head at a speed nine times playback (that is, the playback which is at a speed nine times the normal or standard playback speed) ), 405 denotes fields or areas for recording the image data for normal playback, 406 denotes fields or areas for recording the image data for speed triple playback, 407 denotes the fields or areas for recording the image data for the speed its nine times playback, and 408 denotes a control track.

In triple-speed playback, the rotary magnetic head performs a playback operation by crossing three tracks as indicated by an arrow 403 , and the image data for triple-speed playback are arranged at positions like those indicated by 406 . On the other hand, the scanning path of the rotary magnetic head in the speed-nine reproduction is such as indicated by an arrow 404 , and it is possible to reproduce the image data intended for the speed-nine reproduction by arranging this image data at the positions indicated at 407 .

In accordance with the previously known scheme, as described above variable-speed playback occurs Problems mentioned below.

Namely, because they are intended for variable-speed playback Image data on specific tracks according to the previously known scheme are recorded, it is necessarily necessary to the rotation to control the magnetic head so that it tracks the relevant tracks in the speed can play with variable accuracy with accuracy. The Tax funds that are to be used for this purpose, however, are ignored donated.

In the case of the so-called VHS system video recorder is a control signal used for tracking control on the control track recorded in the positions of the tracks for playback under Reference to the control signal determined in the playback mode be detected approximately.

The controller for scanning the specific or specific track at the However, speed-variable playback was ignored gives and difficulties arise in detecting the positions of the Tracks for variable speed playback when the data is in are arranged in the manner described above, making it impossible the video or video intended for variable speed playback Play image data correctly.

The aim of the invention is therefore a magnetic recording / reproduction device with improved high-speed playback create.  

This goal is achieved by a magnetic recording / reproducing device tion achieved according to claim 1. Further configurations are in the Subclaims defined.

A magnetic recording / reproducing device according to the present invention The invention includes a recording device for recording a Signals on a magnetic tape with a rotating head and a re output device with a standard playback mode for playing back the  Signals at a standard tape speed and a high speed speed reproduction mode for reproducing the signal at a predetermined one Belt speed that is higher than the standard belt speed. A reproduction signal processing unit processes a digital signal which should be recorded so that the digital signal that is in the high speed playback mode to be played, distributed over predetermined positions on a plurality of predetermined tracks is recorded. Data for high-speed playback recorded so as to be at positions along a scan path of the Rota tion head on the magnetic tape in the high-speed playback mode are arranged. A branding unit generates brands accordingly the positions on the track, on the digital signal data contained in the High-speed playback mode should be played are drawn to add the marks to a control signal. A Control head records the control signal with the added marks at the Signal recording by the recording device in each case accordingly the track positions and gives the control signal with the added Marks when the signal is reproduced by the reproducing device. A mark recognition unit recognizes the marks from the control signal as it is played. A phase comparison unit recognizes a phase difference between the mark and a reference signal that is in sync with the rotation of the rotary head was generated. A capstan drive unit controls the running speed of the magnetic tape so that the phase differences limit assumes a predetermined reference value.

Incidentally, it should be mentioned that the high-speed re output mode of the magnetic recording / reproducing apparatus according to the present invention a variety of different speeds can be adjusted. In the playback mode, which is called "speedy variable playback mode "in the description of the present  Application is called, are a plurality of high belt running speeds that are different from one another are set, one desired speed any (i.e. variable) from the majority the set speeds can be selected.

Since the information regarding the starting positions for recording the for the variable-speed playback of certain data by adding as a mark to the control signal is recorded, it is possible to Detect position at which the recording of the for the speedy variable playback specific data is recorded. By the Phase control of the capstan based on the result of the phase ver between the time at which the mark is detected and the Reference signal is performed, the rotary magnetic head can be the front certain tracks on which the data is variable for speed Playback are recorded.

Fig. 1 is a block diagram showing the recording / reproducing apparatus showing a structure of a magnetic In accordance with an exemplary embodiment of the present invention.

Fig. 2 is a block diagram showing a concrete structure of a mark adding unit.

Fig. 3 is a waveform / timing chart showing the operation of the label feeder.

Fig. 4 is a view showing a recording pattern of tracks to be reproduced in a high speed playback mode.

Fig. 5 is a block diagram showing a structure of a brand recognition unit specifically.

Fig. 6 is a waveform / timing chart showing the operation of the mark recognition unit.

Fig. 7 is a view showing another recording pattern of tracks intended for playback in a high-speed playback mode.

Fig. 8 is a view showing another recording pattern of tracks intended for playback in a high-speed playback mode.

Fig. 9 is a view showing a recording pattern on a magnetic tape in a conventional digital video recorder already known.

Fig. 10 is a block diagram concretely showing an example of a configuration of a tracking error detection unit.

Fig. 11 is a view showing a recording pattern of tracks to be reproduced in a four-speed playback mode and a eight-speed playback mode.

Fig. 12 is an enlarged schematic view showing fragments of tracks to be played in a high-speed playback mode.

FIG. 13 is a waveform / timing chart showing the operation of the tracking error detection unit shown in FIG. 10.

Fig. 14 is a block diagram showing another configuration of the tracking error detection unit.

Fig. 15 is a block diagram showing the recording / reproducing apparatus according to another form approximately exporting of the present invention showing a structure of a magnetic on.

Fig. 16 is a block diagram concretely an exemplary circuit configuration of a Nachführfehlererkennungseinheit Vorrich in the processing according to the showing in FIG. Embodiment shown 15 °.

Fig. 17 is an enlarged schematic view showing a fragment of a track reproduced in a high-speed playback mode.

FIG. 18 is a diagram showing the characteristic of an output signal from the tracking error detection unit shown in FIG. 16.

Fig. 19 is a block diagram showing an arrangement of a magnetic recording / reproducing apparatus according to another execution form of the present invention.

The following are exemplary embodiments of the present Invention described with reference to the drawings.  

Fig. 1 is a diagram showing a structure of a Nachführsteuerungsvor direction according to an exemplary embodiment of the present invention.

In Fig. 1, reference numeral 101 designates a supply tape reel for supplying magnetic tape, 102 designates rotary magnetic heads, each for signal recording and reproduction, 103 designates a drum in which the rotary magnetic heads are arranged, 104 designates the magnetic tape for receiving a signal, 105 designates one Control head for recording / reproducing a control signal, 106 denotes a capstan forcing the magnetic tape to run, 107 denotes a pinch roller. 108 denotes a recording tape reel for recording the magnetic tape, 109 denotes a switching means, 110 denotes a playback signal processing unit for processing a reproduced signal, 111 denotes a recording signal processing unit for processing a recording signal (i.e. a signal to be recorded), 112 denotes a reference signal Generation unit for generating a reference signal, 113 denotes a label adding unit for adding a label to the control signal, 114 denotes a changeover switch, 115 denotes a capstan drive circuit for controlling the rotation of the capstan, 116 denotes a phase comparison unit for comparing the phase of the reference signal with that of the reproduced control signal, 117 denotes a mark recognition unit for recognizing a predetermined mark from the reproduced control signal, 118 denotes a system controller for commanding a reproduction speed, 119 denotes a signal output terminal, 120 denotes a signal input terminal, and 20 denotes a tracking error detection unit.

First, the description focuses on the operation of the above described digital video recorder in a recording mode.  

A digital image signal that is intended to be recorded by the digital video recorder according to the present exemplary embodiment of the present invention is supplied to the signal input terminal 120 . The above-mentioned digital image signal is obtained as a result of image compression processing which is carried out, for example, according to the MPEG (Moving Picture Experts Group) scheme and which is received via satellite broadcasting, a cable television network or the like.

The above-mentioned digital image signal is divided into blocks each of a predetermined length by the recording signal processing circuit 111 . Data for each block is provided with a block address indicating the address of the associated block on the tape, an error correction / concealment code for correcting or hiding errors during playback, and the like for the purpose of enabling the data to be reproduced on a block -by-block basis, even if the data is replicated fragmentarily by the rotary magnetic head 102 crossing the tracks.

Data for the variable-speed reproductions are similarly supplemented with the block address, the error correction / concealment code and the like on a block-by-block basis, the block addresses and the error correction / concealment code as shown in Fig. 9 at predetermined positions on the Track can be inserted. The recording of the data for the variable-speed reproduction can be realized by storing the data which has been subjected to the compression processing in a memory on a frame-by-frame basis and outputting on a predetermined number of tracks during which Memory output data can be divided accordingly. Subsequently, the data for each track is modulated to thereby be converted into a signal suitable for recording on the magnetic tape 104 .

By the above-mentioned controls, the signal for each track which has undergone the predetermined processing in the aforementioned recording signal processing circuit 111 is supplied to the rotary magnetic heads 102 which rotate in synchronism with a reference signal, thereby being recorded on the magnetic tape 104 .

The rotating drum 103 (not shown) via a drum drive controlled, so that the rotation drum 103 wind speed for a Rotationsgeschwindig rotates from 1800 rpm while their rotational phase is controlled to have a predetermined phase relationship to the reference signal 112 via a phase comparison controller that realizes is by making use of the reference signal 112 (30 Hz), a drum rotation pulse signal and other uses. Furthermore, the tape running speed is controlled so as to obtain a predetermined speed via the cap stan drive while the running phases (position) control of the magnetic tape via a phase comparison control (not shown) of a signal by an appropriate frequency division of a capstan FG signal is derived, executed. These controls are completely the same as those used in the already known video recorders of the analog VHS system.

On the other hand, a control track 408 for recording a control signal is separately provided on the magnetic tape in its longitudinal direction in addition to the image signal tracks for recording the image signal. The control signal is recorded by the control head 105 , which is a stationary head, which is used in the tracking control of the head in the playback mode.

In the case of video recorders of the conventional analog type of the VHS system, the reference signal 112 of 30 Hz, which is used for the phase control of the rotary drum as the control signal, is intactly recorded on the magnetic tape by means of a stationary head. In the playback mode, the tracking control for the head is performed via a phase comparison control between the playback timing of the control signal and the reference signal 112 so that the head can correctly scan the recorded track.

In the case of the digital video recorder to which the present invention relates, the variable speed playback tracks to be scanned by the rotary magnetic heads in the variable speed playback mode are predetermined. As a result, a signal is required to enable tracking control for the tracks intended for variable speed playback. For this reason, in the apparatus shown in Fig. 1, marks serving as identification information are added to the control signal in synchronism with leading tracks for the start of recording the data intended for the variable speed reproduction by means of the mark adding unit 113 , so that the marks as that Tracking control signal can be used in the variable-speed playback mode.

The recording signal processing circuit 111 constructs the data to be recorded on each track so that the data for variable-speed playback is recorded at respective predetermined positions on the track by data 406 for playback at three times the speed of the normal or standard playback speed (im hereinafter referred to as triple-speed playback) together with data 407 for playback at nine times the speed of normal or standard playback speed (hereinafter referred to as nine-speed playback) are mixed into the data 405 for the normal-speed playback shown in FIG. 9, with the built up or synthesized data are supplied to the rotary magnetic head. As a result, the pattern of the recorded tracks is as shown in FIG .

At the same time, the recording signal processing circuit 111 supplies a mark feed command to the mark feed circuit 113 at every leading position of the variable speed reproduction tracks, that is, at every sampling timing for the head, around the data 406 and 407 for the variable speed reproduction located at the lowermost ends of the tape 9 when taking the head scan paths 403 and 404 shown in Fig. 9 as an example. The tag feed circuit 113 operates to add a predetermined tag to a reference signal in accordance with the aforementioned tag feed command, the control signal being added to the tags at all times to record the leading tracks for a group of data constituting the variable speed playback tracks is output to the control head.

The operation of the mark supply circuit 113 will now be described in conjunction with a concrete exemplary record shown in FIG. 2.

In Fig. 2, reference numeral 201 designates a reference signal input, 202 denotes a Markenzufügesignaleingang, 203 denotes a first pulse generating unit, 204 denotes a second pulse generating unit, 205 denotes a switch, 206 denotes a control signal output, 207 denotes an output of the first pulse generation unit and designates 208 a Output of the second pulse generation unit.

The output signal of the reference signal generating unit 112 has 30 Hz (with a period t = 33.3 ms), and a nominal ratio (load ratio) thereof is 50%. This reference signal is input to the reference signal input terminal 201 . The first pulse generating circuit 203 generates a pulse 207 having a pulse width of 10 ms with the rise of the above-mentioned reference signal. Similarly, the second pulse generation circuit 204 is configured to generate a pulse 208 with a pulse width of 5 ms in response to the rise in the aforementioned reference signal. The changeover switch 205 is designed to respond to the mark feed control signal 202 and thereby switch the reference signal 201 , the output 207 of the first pulse generation circuit and the output 208 of the second pulse generation circuit accordingly from one to the other. The output 207 of the first pulse generation circuit has a nominal ratio which is equivalent to 30%, while the output 208 of the second pulse generation circuit has a nominal ratio of 15%. As a result, the control signal 206 modulated with respect to the nominal ratio according to the mark control signal 202 can be obtained as shown in the timing chart of FIG. 3. The reference signal provided with the added mark is transmitted to the control head via the changeover switch 114 so as to be recorded on the magnetic tape as the control signal.

Using the processing described above, the tagged control signal is recorded on the magnetic tape in synchronism with the leading tracks from which the variable-speed playback data recording is based, as shown in Fig. 4. In the case of the exemplary track pattern shown in Fig. 4, the output of the first pulse generating circuit will be used as a mark b to identify triple speed reproduction, while the output of the second pulse generating circuit will be used as a mark c to identify triple speed reproduction and nine times speed reproduction.

The description below relates to the operation of the magnetic on Drawing / playback device in the variable speed re mode, in which triple speed playback as an example is used.

When variable speed playback is commanded, controller 118 issues a command to capstan drive circuit 115 which causes the capstan to rotate 106 at three times the speed in the recording mode (hereinafter referred to as triple speed). . This causes the magnetic tape 104 to run at triple speed as a result. In this case, the recorded control signal is reproduced by the control head 105 at the triple speed. This control signal is then fed to the mark recognition unit 117 via the changeover switch 114 .

The mark recognition unit 117 is designed to recognize the mark corresponding to the playback speed from the marks to be added to the control signal in the playback mode. As a result, in the triple speed reproduction mode, the mark corresponding to the track intended for the triple speed reproduction is recognized.

The description now turns to the operation of the mark recognition unit 117 .

Fig. 5 shows an exemplary embodiment of the concrete Markenerken drying unit 117. In the figure, reference numeral 501 denotes a control signal input, 502 denotes a speed designation signal input, 503 denotes a pulse generation unit, 504 denotes a hold circuit, 505 denotes a mark detection signal output, and 506 denotes the output of the pulse generation unit.

The control signal input terminal 501 is input with the control signal reproduced by the control head. Further, the speed designation signal input terminal 502 is input with a speed designation or command signal, which is supplied from the system controller 118 .

In the triple-speed playback mode, the control signal is reproduced at three times the speed of that in the standard playback mode. At this time, the frequency of the control signal 501 is 90 Hz. In this connection, suppose that the nominal ratio of the control signal bearing the mark b for triple speed reproduction is 30% and that the nominal ratio for the control signal bearing the mark c for the triple-speed playback and the nine-speed playback carries 15%, the H-level duration of the control signal during the detection of these marks is about 3.3 ms (b) and 1.6 ms (c), respectively. Since the nominal ratio of the control signal with no mark recorded on it is 50%, the corresponding H level period or duration is about 5.5 ms. As a result, by checking the signal segment in which the H level duration of the control signal is shorter than 4 ms, for example, it is possible to recognize the marks b and c.

Fig. 6 is a waveform diagram showing the above-described operation. The pulse generation circuit 503 responds to the rising edge of the control signal 501 reproduced by the control head 105 and input to the control signal input terminal, thereby generating a pulse with a duration of 4 ms (see a signal waveform 506 ). On the other hand, the hold circuit 504 responds to the falling edge of the pulse 506 , thereby holding the control signal 501 mentioned above. In the case of the ordinary or normal control signal without a mark recorded therein, the H level duration or period is not longer than 4 ms. As a result, the held signal segments are always at the "H" level (see a signal waveform 505 ). In contrast, in the mark fields b and c, the H level duration of the control signal 501 is short, and as a result, the control signal 501 takes precedence over the aforementioned pulse 506 . Accordingly, the held signal segment 505 assumes a "L" level. As a result, it is possible to recognize the positions of the marks b and c from the control signal 501 .

The phase comparator 116 compares the phase of the brand recognition signal generated by the brand recognition unit 117 and has a frequency of 30 Hz with that of the reference signal 112 , the rotation phase of the capstan motor (not shown) being controlled so that the error resulting from the results in the above-mentioned phase comparison, assumes a predetermined value.

As a result, the tracking phase of the rotary magnetic head 102 coincides with the scanning of a predetermined track 403 on which the data for triple-speed reproduction is recorded.

Furthermore, the data recorded on the magnetic tape and intended for triple speed playback are reproduced by the rotary magnetic head 102 . The data reproduced by the rotary magnetic head 102 is input to the reproduction signal processing circuit 110 through the changeover switch 109 , thereby being output to the signal output terminal 109 as image data after being subjected to predetermined processing carried out by the reproduction signal processing circuit 110 .

Incidentally, in the case of the exemplary embodiment described above, the mark c designates two types of variable-speed playback tracks since the start positions where the variable-speed playback tracks are in the variable-speed playback mode in triple-speed and nine-speed playback are to be scanned, are superimposed on one another. In this connection, however, it should be noted that by deviating the positions of the variable-speed playback tracks that differ from each other in terms of the playback speed in such a manner as shown in FIG. to establish a one-to-one correspondence between the marks and the playback speeds. In this case, two pulse generation units can be provided for the brand recognition, so that the individual brands can be recognized independently of one another by realizing such an arrangement that can only recognize the brand of a predetermined width.

Incidentally, in the case of the recording as shown in Fig. 4, when the position of the mark c indicating the nine-speed reproduction can be recognized, it is then possible to determine the position of the mark b indicating the three-speed reproduction based on the relationship between the positions of the tracks for both of the above-mentioned playback speeds. As a result, the mark to be recorded can only be the mark c. Fig. 8 is a view showing an exemplary embodiment of the invention, which has been realized for this purpose. By measuring the number of control signals after recognition of the mark c, the start position of the track for playback at three times the speed can be identified in a simple manner. Even if the arrangement of the tracks for the variable-speed reproduction should change, it is possible to determine the starting positions of the individual tracks by calculation based on at least one mark, provided the track arrangement is known.

In the foregoing, the invention has been described by way of examples triple replay for the variable-speed reproductions playback speed and nine times the playback speed gene, but it is understood that the invention is not is limited to such companies, but in the tracking control of the Magnetic tape can be applied to the data from tracks contains recorded that for variable speed playback at other given playback speeds are determined. Besides can the invention in the same way for the tracking control for variable-speed playback not only in the forward direction but also applied in the backward direction, which is not must necessarily be mentioned.

In the case of the examples described above, the modulation of the Nominal ratio of a control signal as the mark recording method accepted. However, the invention is not based on such modulation limited, but can also be used where a majority of successive control signals with the same nominal ratio be modulated, the brands based on the numbers of the modulated Control signals are distinguished from one another and identified. Further the marks can also be recorded by using patterns  Is made use of by combining the control signals with differing nominal ratio are formed.

From the foregoing, it is apparent that according to the present Invention a tracking control device is provided, which is capable of the tracks for the variable-speed reproductions on which the Data for variable-speed playback on the magnetic tape are tracked with accuracy, keeping the information for the speed variable renditions at any given Speeds higher than normal or standard playback are distributed over the track positions along the scanning path of the rotary magnetic head are recorded.

A magnetic recording / reproducing apparatus according to a second embodiment of the present invention will be described below with reference to other drawings. In the magnetic recording / reproducing apparatus according to the first embodiment of the invention, the rotary magnetic head is caused to access the track on which the data blocks for variable-speed reproduction are arranged in response to the detection of the mark contained in the control signal. In this connection, however, it should be noted that although the magnetic recording / reproducing apparatus is usually made so that the fixed position of the control head 105 takes a predetermined position relative to the rotational phase of the rotary magnetic head 102 , there are actually deviations or fluctuations in the position of the control head 105 exist among the recording / reproducing devices (VCRs) actually manufactured or under various types of recording / reproducing devices. Such positional deviations appear as detection errors and consequently as tracking errors when determining the tracks for the speed-variable reproduction by recognizing the marks. According to the teaching of the invention embodied in the second exemplary embodiment, the error between the speed variable reproduction track and the rotary magnetic head is detected by the tracking error detection unit 20 shown in FIG. 1 even when the mark recording position and the position of the track for the variable-speed playback according to this mark should vary from one to another magnetic recording / reproducing device, in order to thereby correct the tracking deviation of the head in variable-speed playback by appropriately adjusting the running speed of the magnetic tape, so that the magnetic head is always the desired track for the ge Desired speed variable playback follows or follows with high accuracy.

The tracking correction operation will now be explained by taking, for example, the tracking operation shown in FIG. 11, which is aimed precisely at the track 403 for quadruple speed reproduction. It is intended that this control be realized by changing a reference value for controlling the phase comparison unit 116 , which carries out a phase comparison between the mark detection signal and the reference signal, and can ensure compatibility during playback under the video recorders.

Referring to Fig. 11, the hatched fields or areas denoted by reference numeral 401 represent data for playback at a speed four times the normal or standard playback speed (hereinafter referred to as four-speed playback) while mesh-like fields or areas denoted by 403 represent data for playback at eight times as fast as normal or standard playback speed (hereinafter referred to as eight times speed reproduction). Furthermore, reference numeral 403 denotes tracks which are subjected to quadruple speed reproduction and 404 denotes one Track intended for eight-speed playback. Further, reference numeral 405 in the same figure denotes a control track in which a position at which the control signal with a nominal ratio of 50% and formed by the output reference signal is to be recorded intact is designated by a, while a position at which the control signal output from the pulse generation circuit 203 to be recorded at the nominal ratio of 30% is denoted by b, with a position where the control signal output from the pulse generation circuit 204 to be recorded at the nominal ratio of 15% is to be recorded by c.

The control signals indicating the recorded positions on the track are recorded by the control head 105 . In this connection, it should be noted that the control head 105 is not always located in exactly the same position in all video devices. For this reason, the recorded position of the control signal relative to the recording position on the track may differ from one video device used for recording to another, which leads to a problem when the compatibility among the video recorders used for playback is considered.

In the video recorder, which is able to receive the digital signal according to the to record / reproduce the present invention becomes one Assuming an arrangement in which the recording positions of the tracks for the variable-speed reproductions with the help of the control signal added brands can be recognized. Accordingly, if the above mentioned problem occurs, the shooting position of the mark may not be accurate  the recording position of the track for variable-speed playback show what makes it impossible to track with the magnetic head while ensuring compatibility among individuals To realize video recorders.

The above-mentioned problem can be solved by providing an adjustment device arranged to correct the reference point for the phase comparison circuit 116 depending on the output of the tracking error detection unit 20 in the reproduction mode. In this connection, the above-mentioned correction can be implemented, for example, by shifting the phase of the mark signal recognized by the mark recognition unit 117 or the phase of the phase reference signal generated by the reference signal generation circuit 112 or, alternatively, by imparting a signal offset to the output of the phase comparison circuit 116 . Of course, other methods can be used for this purpose.

The video recorder according to the present invention, which is capable of performing digital recording / reproduction, is designed so that a phase shift amount, as required depending on the tracking error, is recognized by the tracking error detection unit 20 shown in FIG. 1 and is determined, the tracking correction being carried out in accordance with the detected phase shift quantity.

The operation of the tracking error detection unit 20 is described below with reference to FIG. 10, which specifically shows an exemplary configuration of the tracking error detection unit 20 . In Fig. 10, reference numeral 701 denotes a speed command input terminal to which a playback speed command output from the system controller 118 is supplied, and 702 and 703 each designate block address input terminals to which block addresses output from the playback signal processing unit 110 are supplied with the track identification (ID) number of the block currently being scanned by the magnetic head is input to terminal 702 while the block identification (ID) number is input to terminal 703 . Further, reference numeral 704 denotes a ROM (read-only memory) in which the respective block addresses are stored, 705 denotes a comparison circuit for comparing the block identification number read out from the ROM 704 with the block identification number output from the reproduction signal processing circuit 8 , and a sign 706 denotes a sample-hold circuit which, when the track identification number read out from the ROM 704 matches the track identification number output from the reproduction signal processing unit 110 , interchangeably performs a sample operation while otherwise performing the hold operation. Further, reference numeral 707 denotes a tracking error signal output terminal from which the result of the comparison made by the comparison circuit 705 is output.

The tracking error detection unit 20 shown in FIG. 10 is implemented to detect the tracking error of the magnetic head relative to the track for variable speed playback based on the track identification number and the block identification number supplied from the playback signal processing unit 110 .

FIG. 12 is a view showing the principle on which the error detection operation of the tracking error detection unit 20 shown in FIG. 10 is based, and shows selected parts of fragments of the reproduction pattern on the magnetic tape 104 . In the figure, reference numeral 801, 802 and 803 scan paths of the rotary magnetic head 102, the scan path 801 represents a path along which the magnetic head 102 scans the track 403 line for the quadruple speed reproduction along the center. Furthermore, characters inserted into the tracks indicate the block addresses of each track, the characters in front of the decimal points representing the track identification (ID) numbers, while the characters following the decimal point represent the block identification (ID) numbers. As can be seen from the figure, the block identification number of the block on which the magnetic head following the scan path 801 reaches the track to which the track identification number "4" is assigned is "27". In this connection, it should be noted that the recording signal processing unit 7 previously determines the arrangements of the data for the variable-speed reproduction according to a predetermined algorithm based on the block addresses. Accordingly, the block identification number "27" is determined beforehand and, as a result, can be stored in a memory device such as a ROM as a reference block identification number. Assuming that path 802 or 803 is the scan path that the magnetic head actually follows, the block identification number of the block of the track of block identification number "4" to which the magnetic head arrives is "30" or "22". As a result, the difference between these values and the above-mentioned reference block identification number is "3" and "-5", each of which is proportional to the phase difference from the scan path 801 representing the reference phase.

In this way, by storing the relationships between the track identification numbers and the block identification numbers in the ROM 704 in quadruple-speed reproduction, which is performed by the magnetic head scanning the track 403 along its center line and by comparing the reproduced block address with the reference block address, it is possible to recognize the tracking deviation from the track 403 provided for the quadruple speed reproduction.

Fig. 13 is a waveform diagram showing the above-described operation assuming that the magnetic head scans along a path such as the scanning path 803 . In the figure, block addresses read from the ROM 704 are shown at (A) and (B). As can be seen, the track identification (ID) number "4" and the block identification (ID) number "27" are output from the ROM 704 as the block addresses to serve as the reference in quadruple speed reproduction. Also shown in the same figure are block addresses output from the reproduction signal processing unit 110 at (C) and (D), which represent the address of the blocks currently scanned by the magnetic head. Also shown in the same figure is the operation of sample and hold circuit 706 at (E). As can be seen, when a match of the track identification numbers shown at (A) and (C) occurs, the scanning operation is switched to a mode in which the difference between the block identification numbers is output from the comparison circuit 705 and, as in (B) and (D ) is shown, is scanned. The sample-hold circuit 706 is immediately switched to the hold mode, and the difference "-5" between the two block identification numbers is output from the tracking error detection unit 20 (see Fig. 13, (F)).

Since the sign of the tracking error signal is negative or a minus sign, it can be seen that the phase of the scan path 803 is leading relative to the scan path 801 used as the reference scan path , which consequently indicates that the scan path 803 is from the scan path 801 in the right direction ( that is, in the direction opposite to the tape running direction) deviates. In other words, this indicates that the mark recording position in the right direction deviates relative to the recording position of the track for quadruple speed reproduction. As a result, it is possible to perform such control that the magnetic head precisely scans the track 403 for quadruple-speed reproduction substantially along its center line by the phase of the mark signal reproduced by the mark recognition unit 117 or the phase of that by the reference signal generator 112 based on the tracking error signal generated reference signal is shifted.

Incidentally, it should be noted that although the exemplary embodiment of the mark recognition unit 117 shown in Fig. 5 is arranged to correspond to the marks b and c corresponding to the track for quadruple speed reproduction in the high speed mode, that is, in the quadruple speed reproduction mode, To detect or detect, detection of only the mark c, which corresponds to the track for eight-speed playback in the high-speed mode, by changing or modifying the duration of the "H" level of the pulse shown in FIG. 5 generating circuit 503 output holding pulse can be realized in such a manner as described below.

Since the period of the control signal re-produced during the eight-speed reproduction in the high-speed mode is 4.2 msec (milliseconds), the period or duration of the "H" level of the mark a is 2.1 msec, which is equivalent to the nominal ratio of 50% , while the period or duration of the "H" level of the mark b is 1.3 msec equivalent to the nominal ratio of 30%. Furthermore, the duration of the "H" level of the mark c is 0.6 msec, which is equivalent to the nominal ratio of 15%. In this case, by setting the H-level duration of the hold pulse output from the pulse generating circuit 503 at, for example, 1.0 msec, only the mark c can be recognized in the eight-speed reproduction of the high-speed mode.

Furthermore, the detection of marks corresponding to the tracks for the eightfold speed reproduction and the sixteenfold speed reproduction in a medium speed mode, as well as the detection of the marks corresponding to the tracks for the sixteenfold speed reproduction and the thirty-twofold speed reproduction respectively, can be realized in a low-speed mode in which the H-level duration is realized of the hold pulse output from the pulse generation circuit 503 is changed accordingly.

Further, although in connection with the operation of the tracking error detection unit 20 shown in Fig. 13 in the magnetic recording / reproducing apparatus according to the second exemplary embodiment of the invention, it is shown that the track identification numbers for the tracks are compared with the block numbers to be subjected to the comparison, are fixed to specific track numbers, the present invention is not limited to such an arrangement, but it is equally possible to recognize the tracking error signals in a plurality of tracks when necessary.

Incidentally, in the case of the exemplary embodiment of the tracking error detection unit 20 shown in Fig. 10, the tracking deviation of the magnetic head relative to the speed variable reproduction track is recognized by a relationship between the track identification (ID) number of the block currently scanned by the magnetic head and the block identification number is used. However, the tracking error detection method is not limited to such a scheme.

Fig. 14 concretely shows another exemplary embodiment of the error detection unit 20 after threading. In the figure, reference numeral 701 denotes a speed command input terminal to which a speed command issued by the system controller 118 is applied, 702 denotes a track number input terminal to which the track identification number of the block currently scanned by the magnetic head and by the playback signal processing unit 110 is output, applied, 703 denotes a head change signal input terminal to which a head switch signal for changing the magnetic heads is input, 724 denotes a ROM in which relationships between the track identification numbers and the magnetic head scan times are stored, 725 denotes a comparison circuit for comparing the the ROM 704 time read out by a timer 726 which is in response to a rising edge and a falling edge of the head switch signal for measuring the elapsed time since the start of the scan bed the magnetic head has expired, is reset, is output, and reference numeral 727 denotes a sample-and-hold circuit that interchangeably immediately performs a sampling operation when the identification number read out by the ROM 724 matches the track identification number output by the reproduction signal processing unit 110 while otherwise the holding operation is carried out. Further, reference numeral 707 designates a tracking error signal output terminal, from which the result of the comparison made by the comparator 725 is output.

The ROM 724 included in the tracking error detection unit 20 shown in Fig. 14 is configured to store a data table having a relationship between the track identification number of a specific track on which the digital signal data to be reproduced in the variable playback speed mode and one Reference time, which is taken for the recognition of a predetermined track from the time at which the scanning of the specific track is started. Furthermore, timer 726 measures the elapsed time from the start of the track scan. The tracking error detection operation of the device shown in FIG. 14 will be briefly explained with reference to, for example, the track pattern shown in FIG. 12 for quadruple speed playback. The time it takes for the magnetic head to reach track # 4 from the point at which the scanning operation starts from the leading end of track # 3, which defines a normal center scanning path, is previously known as this will be explained below, and stored in the ROM 724 as a reference time. It is self-explanatory that if the path actually followed by the magnetic head is such as path 802 , the real time that the magnetic head takes to track No. 4 from the time when the scanning operation from the leading end portion of the Track # 3 as measured by timer 726 starts to differ from the reference time mentioned above. The difference between the real time and the reference time corresponds to the tracking error.

During a single scan operation of the magnetic head in the variable-speed reproduction, the magnetic head 102 reproduces all the block identification numbers assigned to the blocks arranged on the track in the longitudinal direction thereof, from the block designated by an initial identification number to the block designated by the final identification number is started while scanning over a plurality of tracks. In this connection, the time required for the individual scanning operation of the magnetic head is determined via the rotational speed of the rotary drum 103 , which is 1800 rpm. Since a pair of magnetic heads 102 are arranged on the rotary drum 103 opposite to each other with an intermediate angular distance corresponding to 180 ° to each other, the time required for the above-mentioned scanning operation is 16.66 msec. Based on this relationship, it can be seen that there is a proportional relationship between the block identification number of the block reproduced by the magnetic head and the time elapsed from the start of the scan by the magnetic head. As a result, it is possible to recognize the tracking error signal based on the relationship between the track identification number and the sampling time by means of the tracking error detection unit shown in FIG. 14 as well as in the case of detecting the tracking error signal by the one described above with reference to FIG. 10 Tracking error detection unit based on the relationship between the track identification number and the block identification number.

At this point, it should be noted that a situation may arise in which the rotational speed of the rotary drum 103 relative to the reference rotational speed "1800 rpm" of the rotary drum 103 must be corrected to make the transmission rate of the reproduced digital signal in the variable-speed reproduction equal to that in the normal - or to make standard playback. In this case, the time required for the single scanning operation of the magnetic head is not, as mentioned above, 16.66 msec. However, since the correction amount for the rotational speed is determined by the speed in the variable-speed reproduction, the magnetic head required for executing the single scan can be easily determined for each speed used in the variable-speed reproduction, and a proportional relationship between the block identifiers cation number and the head sampling time may be valid, as is the case with the case described above.

The circuit configuration of the tracking error detection unit shown in Fig. 14 is favorable when the tracking error detection unit is realized by using a single chip microcomputer which includes a timer, counter or the like, since then the tracking error detection can be performed without the need for the block identification number for the external one Input signal processing unit 110 while eliminating the need to provide additional other circuitry.

Furthermore, the tracking error detection unit 20 can also be implemented to detect the tracking deviation from the track for variable-speed reproduction by the magnetic head by, for example, the reproduction output level of the magnetic head instead of using the digital reproduced data as previously with reference to Figs. 10 and 14, use is made. Since the magnetic head performs the scanning operation over a plurality of tracks in the variable-speed reproduction, the output level of the signal reproduced by the magnetic head varies periodically at a predetermined interval in the course of the scanning. In this case, the timings or times at which the output level of the reproduced signal becomes maximum are limited to various specific times, which are determined according to the path along which the scanning is performed by the magnetic head.

Accordingly, it is possible to track the tracking deviation for the speed variable reproduction of the magnetic head by previous Saving the timings or times at which the output level of the reproduced signal during the scan along the Center line of the track for variable speed playback by the Magnetic head becomes maximum, and by comparing the saved times with those at which the output level of the reproduced signal was selected rend of the scanning operation actually performed by the magnetic head maximum will determine.  

In the case of the above exemplary embodiment of the invention the description was made on the assumption that four times Speed used in variable-speed playback becomes. However, the present invention is not limited to such Limited speed for variable speed playback, but can be used in the same way for tracking control of a magnetic ban on which the data relating to tracks are recorded are for variable speed playback at a given or arbitrary speed are provided. Furthermore, the is above Description on the variable speed playback mode in the Forward direction, it being understood that the invention in the same way to a tracking control with variable speed Playback can be applied in the reverse (or reverse) direction can.

In the case of the trademark recording process of the State of the art, the nominal ratio of a control signal is modulated. However, the invention is not limited to such a modulation. To a plurality of successive control signals can be used for this purpose can be modulated with an identical nominal ratio to identify the Brand according to the number of modulated with the same ratio Control signals or alternatively patterns can be used be by combining the control signals with each other under different nominal ratios are shown. It is also next to it possible the mark by modulating the control signal during the period an "H" level or "L" level thereof.

Instead of modulating the nominal ratio, you can also use a current used to record the control signal can be varied or alternatively, a method of additively using a special one  Signals are adopted in the control signal. Of course others can different trademark recording methods can be used without using the Depart from the scope or spirit of the present invention.

As can now be seen from the previous description, power the present inventive arrangement that information for the ge variable speed playback at a given speed performed faster than normal or standard playback speed is recorded, taking the positions corresponding to the Paths to be followed by the magnetic head in the scanning operation is distributed with the tracks for variable-speed playback can be scanned in the magnetic head by adding those to the control signal Marks are recognized to track the speed variable Playback to identify when the variable speed playback using a magnetic tape with independent, for the speed variable playback performed and recorded tracks executed shall be. Additionally, since the result of the phase comparison was obtained can be made by using the reproduced block addresses is made, a tracking control can be realized in the Is able, with high accuracy, essentially along the center line of the Scan track for variable speed playback. Furthermore, since it is prescribed that the speed for the speed variable playback identical to the absolute speed for that Magnetic tape in recording / playback modes with several tape speeds is the tracks (recording patterns) for the speedy variable playback on the magnetic tape identical to each other in all available recording / playback modes, where a simplification of the circuit configurations for processing the Record signals and the playback signals can be realized.  

Referring to Fig. 15, a third exemplary embodiment of the magnetic recording / reproducing apparatus according to the present the invention. In the case of the magnetic recording / reproducing apparatus according to the present embodiment of the invention, it is provided that such control is performed by first adopting the tape speed in the variable-speed playback or high-speed playback mode. Subsequently, the magnetic head is controlled to access the positions on the tracks where the data for the variable-speed reproduction are recorded by recognizing the marks contained in the control signal. Subsequently, the tracking control is carried out such that the scanning path of the rotary magnetic head follows a center line of the track for the variable-speed reproduction. The tracking control is realized by using a motor control of a capstan motor speed. In this case, the tracking control may be changed or modulated depending on the state of a damping coefficient used in the speed drive control.

Incidentally, in Fig. 15, parts or components denoted by the same reference numerals as those in Fig. 1 denote the elements which are intended to serve similar or equivalent functions. As a result, repeated description of them is unnecessary.

Fig. 15 is a block diagram showing a magnetic re-recording / reproducing apparatus according to the third embodiment of the present OF INVENTION dung. In the figure, reference numeral 103 designates a rotary drum, and reference numerals 102 a and 102 b each designate a pair of rotary magnetic heads which are attached to the rotary drum 103 and each have azimuth angles which are oriented to each other in opposite directions. In this context, it is assumed that the rotary magnetic head 102 a has a positive azimuth angle and the rotary magnetic head 102 b is oriented at a negative azimuth angle. Furthermore, the reference numeral 7 denotes a capstan motor for rotationally driving a capstan 106 , 8 denotes a frequency generator or in abbreviation FG (or a tachometer generator) for generating a frequency signal in synchronism with the rotational speed of the capstan motor 7 , 9 denotes a high-speed running control unit for rotating the capstan motor 107 to allow the magnetic tape to be fed at a high speed, 10 denotes an adder, 11 denotes a motor drive circuit, 116 denotes a phase control unit for controlling the rotation phase of the capstan 106 , reference numeral 20 denotes one Tracking error detection unit for detecting a tracking error relative to the track to be scanned by the magnetic heads for variable-speed reproduction, and 121 denotes a changeover switch.

The phase comparison unit 116 carries out a phase comparison between the brand recognition signal generated by the brand recognition unit 117 and the reference signal in order to transmit an error signal, which is representative of the phase difference recognized in the phase comparison, to the phase control unit 16 , which controls the rotation phase of the capstan motor 7 to spend. More specifically, when the phase of the mark detection timing lags behind the reference signal, the phase comparison unit 116 operates to output an error signal of a positive polarity and at a level corresponding to the amount of the phase delay, while when the phase of the mark detection timing leads relative to that of the reference signal, the phase comparison unit 116 operates to generate and output an error signal of a negative or minus polarity with a level corresponding to the height of the phase projection.

The tracking error detection unit 119 is designed to detect a deviation of the rotary magnetic head from the center of the desired track to be scanned on the basis of additional information signals of the track identification number and the block identification number reproduced by the reproduction signal processing unit 110 , thereby to detect a tracking error signal with a polarity corresponding to the direction of the deviation and a level corresponding to the amount of the deviation.

Fig. 16 is a block diagram showing the circuit configuration of a concrete exemplary circuit Nachführfehlererkennungseinheit 20 shows. In this figure, reference numeral 703 denotes a playback signal input terminal, 802 denotes a block identification number recognition circuit, 803 denotes a special lane identification number detection circuit, 804 denotes a block error arithmetic circuit, 805 denotes an error signal generation circuit, 701 denotes a speed instruction input terminal, and 707 denotes a tracking error signal.

The additional information signals reproduced by the reproduction signal processing unit 110 are input to the block identification number recognition circuit 802 and the special track identification number recognition circuit 803 . The block identification number detection circuit 802 recognizes the block identification numbers respectively added to the individual blocks from the additional information signals, in order to supply the recognized block identification numbers to the block error arithmetic circuit 804 . On the other hand, the block error arithmetic circuit 804 recognizes the amount of the deviation relative to the center of the desired track from the block identification numbers of the blocks to be reproduced on the particular track to be scanned by the rotary magnetic head based on the track identification number and contained in the reproduced additional signal Block identification number and the speed command signal 701 .

In the following, the operation of the tracking error detection unit 20 is illuminated in detail by taking, for example, a nine-speed variable speed reproduction (that is, a reproduction at a speed nine times the normal or standard reproduction speed).

In the nine-multiple speed reproduction of the rotary magnetic head 102a are during a single scanning operation data on nine tracks again. Accordingly, if it is assumed as an example that a track is composed of 96 blocks labeled with block identification numbers from "0" to "95", the data for nine-speed playback are recorded approximately in twelve blocks on each track.

Fig. 17 is a relationship between ge desired scan paths is an enlarged view of the head 102 a in a particular track that contains the data blocks for the variable-speed playback and block addresses, wherein data for the variable speed reproduction at the nine-time reproduction speed at the locations corresponding to the block identification number "18" to "29" in the track of the identification number "2" are recorded. In order to reproduce the data mentioned above, the sampling phase 801 of the magnetic head 102 a must be as shown by the thick solid lines in FIG. 8 (assuming that data reproduction is possible as far as the magnetic head 102 a tracks over one Half of the track width can be scanned) is specified.

In contrast, when the tracking performed by the magnetic head 102a differs in the direction A or the direction B in the figure, this causes the identification numbers of the blocks for reproduction to vary as the direction increases or decreases. More specifically, when the Ab sensing path of the magnetic head 102 a in the direction A deviates to the According to guiding state to take, as represented by the thin solid lines in the figure, this causes the block from which the data is reproduced, shifts from the desired block in the upward direction, as exemplified by the shift from the block of identification number "20" to block "31". In contrast, when the magnetic head 102a deviates in the direction B to take the tracking state as indicated by the broken lines in the figure, the reproduced block shifts downward from the desired block like this is exemplified by the shift from block "16" to block "27".

For example, when the lane identification number recognized by the special lane identification number detection circuit 803 is "2", the block error arithmetic circuit 804 determines a deviation of an average block identification number relative to the reference value based on maximum and minimum values of the identification numbers of the block which is subjected to reproduction in the track of the identification number "2". More specifically, relative to the average block identification number "23.5" (obtained by averaging the minimum value "18" and the maximum value "29"), which serves as a reference, the block error arithmetic circuit 804 determines "25.5" as the average block identification number on scan A to thereby output a value "+2" as an error or a deviation from the reference value "23.5". On the other hand, in the case of scan B, the block error arithmetic circuit 804 arithmetically determines as the average block identification number "21.5" (obtained by averaging the minimum value "16" and the maximum value "27"), where "-2" is relative as an error is output to the reference value "23.5".

On the other hand, the error signal generation circuit 805 responds to the result of the block error arithmetic determination output from the block error arithmetic circuit 804 to thereby generate a tracking error signal 707 having such a characteristic as shown in FIG. 18. More specifically, when the head position is in the direction A (that is, when the scanning phase of the head is advanced), the error signal generation circuit 805 outputs an error signal of positive polarity at a level corresponding to the amount of the block deviation, while when the head position is in the B direction (i.e., in the direction) which lags the sampling phase of the head), the error signal generating circuit 805 outputs an error signal of a negative polarity and with a level corresponding to the amount of the deviation as a tracking control signal. In other words, in the case of nine-speed playback, the detection of a single block unit corresponds to a resolution of about 0.1 (8/96) with respect to the track width because the signals corresponding to 96 blocks over 8 tracks are in nine-speed playback are reproduced. To put it another way, this is equivalent to detecting the tracking error with a degree of accuracy less than 1/10 of the track width.

The phase control unit 16 is controlled by the system controller 118 to thereby perform a sampling phase control of the rotary magnetic head and thus the control of the tape travel speed on the basis of the error signal of the phase comparison unit 116 or the tracking error detection unit 20 , which is input via the changeover switch 121 . When the command from the system controller 118 is an open loop control command, a fixed reference voltage corresponding to the tape speed is output to the adder 10 . On the other hand, if the command issued by the system controller 118 is a closed loop control command, a phase control loop is established based on the control signal for the changeover switch 121 . Returning to this closed-loop control, when the error signal from the phase comparison unit 116 or the tracking error detection unit 20 is of positive polarity, the tape speed is accelerated, thereby causing the scanning phase of the rotary magnetic head to lag in the relative sense while when the above-mentioned error signal is of negative polarity, the tape speed is decelerated, thereby allowing the scanning phase of the rotary magnetic head to advance in the relative sense. Thus, the tracking error comparison control is performed by the phase comparison unit 116 while the tracking control of the rotary magnetic head is effected by the tracking error detection unit 20 relative to the center line of the desired track to be scanned.

The operation of the magnetic recording / reproducing apparatus according to the third exemplary embodiment of the invention shown in FIG. 15 will now be described.

An example is used to assume that a speed variable Play command button (not shown) operated by an operator where the nine-speed playback (forward direction) is selected , this choice will initially be the result of the fact that the contact of the Changeover switch121 to position b is closed by the system control118 recognized. As a result, the phase control unit115 on set an open loop control mode. In addition a Steueri Signal for starting the control of the high-speed running control unit9  output and at the same time a speed command value is issuedn = "9" the brand recognition unit117 fed. By the way, posesn a Multiple "n" of normal or standard playback speed.

As a result, the rotation speed control of the capstan motor 7 is started by the high-speed running control unit 9 , with the result that the tape speed of the magnetic tape 104 is increased to a speed for the commanded nine-speed playback.

When the tape speed reaches the predetermined speed for the ninefold speed reproduction, this state is keitssteuersystems by the system controller 118 on the basis of the convergence of the error control voltage of a VELOCITY contained in the high-speed running control unit 9 or another factor determined, whereupon the system controller 118, in turn, the control signal for adjusting the outputs control operation performed by the phase control unit 16 in a closed loop control mode. As a result, at a time when the tape speed reaches the nine-speed playback speed, the phase control system is set to the closed-loop control mode according to the control signal of the phase comparison unit 116 , and the phase control takes effect. At the time when the phase control system is set to the closed loop (regulation), the magnetic head 102 a (as well as the magnetic head 102 b) does not always scan the recording track for the data for the nine-speed playback, but can from that desired scanning path.

If the sampling phase of the magnetic head 102 is advanced a relative to the desired for the ge schwindigkeitsvariable playback track, after the phase control system has been set to the closed-loop control mode, the phase comparison unit 116 outputs a track restoration error signal of positive polarity as a result of the operation described above. As a result, the phase control unit 16 accelerates the speed of the capstan motor 7 and thus the tape speed, thereby restoring the correct head position by shifting the head over a number of tracks according to the error, so that the above-mentioned error signal becomes zero.

In contrast, if the sampling phase of the magnetic head 102 a lagging relative to the desired scan path, after the phase control system has been set to the closed-loop control mode, the phase comparison unit 116 outputs an error signal of negative polarity. As a result, the tape speed deceleration control takes effect, and the head scan position restoring control is performed on the variable speed playback track.

Subsequently, if the scanning phase of the magnetic head 102 a falls within a certain range of the desired scanning phase, b 13608 00070 552 001000280000000200012000285911349700040 0002019581346 00004 13489, for example an area of a single track, the controller 118 under the track restoration control performed by the phase comparison unit 116 recognizes this fact from the fact of the error signal output from the phase comparison unit 116 , in order to in turn output a control signal for switching the contact of the changeover switch 121 from the position b to the position a. As a result, the subsequent control performed by the phase control unit 16 is switched to the tracking control which is effected by using the control signal available from the output of the tracking error detection unit 20 .

From the foregoing, it is now clear that the control signal available from the tracking error detection unit 20 is a fine error signal generated on a block-by-block detection basis. As a result, on the effected using the above-mentioned control signal tracking control of the magnetic head 102 a track with the recorded thereon VELOCITY keitsvariablen playback data along the center line are sampled exactly elevated accuracy with.

The above description of the third exemplary embodiment of FIG Invention was made on the assumption that the speed variable Play a nine-speed playback in the forward direction is. However, the invention is not speedy to such a special one variable playback, but can in the same way on the speed variable playback in the reverse direction given Speeds are applied.

Further, although the error detection operation of the track error detection unit 20 has been described with reference to FIG. 15 on the assumption that the error detection is performed for a single specific track, the invention is not limited to such an arrangement. In the same way, it is possible to perform the tracking error detection for a plurality of tracks if necessary.

Consequently, in the case of the device shown in FIG. 15, the phase control unit 16 can be saved by assigning its function to the phase comparison unit 116 and the tracking error detection unit 20 , which is simple for the person skilled in the art.

Furthermore, the exemplary embodiment of the mark adding unit 113 shown in Fig. 15 is implemented to add the mark by changing the nominal ratio of a single control signal, but this does not impose any limitation on the scope of the invention. For example, the nominal ratios of several successive control signals can be changed or the nominal ratio of the H-level duration (period) or the L-level duration (period) of a single or several successive control signals can be changed to generate the mark. Alternatively, combinations of control signals with different nominal ratios can be used as the brands. In short, various modifications of the branding unit 113 may be readily available to those skilled in the art without departing from the spirit and scope of the present invention.

Fig. 19 is a block diagram showing another exemplary form of execution Nachführsteuervorrichtung according to the present invention. In this figure, reference numeral 24 denotes a damping coefficient control unit. In this figure, components denoted by the same reference symbols as those used in Fig. 15 denote the same or equivalent parts serving for substantially the same or corresponding functions.

The tracking control device shown in Fig. 19 is designed so that the damping coefficient control unit 24 is controlled only during the track restoration control process carried out by the phase comparison unit 116 to control the damping coefficient involved in the tape speed control, thereby taking into account the maximum speed of the capstan motor increase acceleration of the phase recovery response speed while increasing the speed when accessing the tracking for variable-speed playback.

In the control system in which the speed control and the phases control can be used in combination if the damping coefficient  for speed control, that is the ratio of sensitive speed control system to that of the phase control system, is increased, the phase recovery response speed becomes lower ger, while if the sensitivity ratio or the above mentioned damping coefficient decreases, the phase recovery response speed increases. As a result, phase recovery can occur a high speed by adjusting the damping coefficient be realized at a small value. In terms of stability of the control system in the normal phase control mode (tracking control mode) However, the damping coefficient cannot be reduced immediately.

In general, the damping coefficient is usually set to one value on the order of "1" to "2" by adjusting the stability of the Tax system is taken into account. As a result, the phase recovery is response speed naturally has a certain limit He puts. In this context, however, it should be mentioned that the Stability of the control system in the phase recovery process for the predetermined track intended for variable-speed playback is not essential. As a result, the damper only during this process.

In light of the foregoing, the exemplary embodiment shown in Fig. 19 is implemented to increase the track access speed by weakening the damping in the track phase recovery process since stability of the control system is not required during this process.

Although a detailed description of the damping coefficient control unit 24 is omitted, it should be noted that the damping coefficient control unit 24 may be constituted by, for example, a gain switching circuit or the like, so that the damping coefficient of the speed control system is between a second predetermined value in a normal reproduction mode (including the speed variable reproduction mode). and a first predetermined value less than the second predetermined value may be switched in response to a control signal output from the system controller 118 .

Due to the above-mentioned arrangement, the system controller 118 outputs a control signal when the tape speed has reached a predetermined speed for variable-speed playback under the control of the high-speed running control unit 9 , as in the case of the exemplary embodiment described above with reference to FIG. 15 .

Upon receipt of the control signal from the system controller 118 , the damping coefficient control unit 24 operates to change the gain to the first value, which is less than the second value effective in the normal playback mode. As a result, the control sensitivity of the speed control system is weakened when the phase recovery control is performed on the desired track to be scanned under the control of the phase comparison unit 116 . To put it another way, the control sensitivity of the phase control system is intensified in a relative sense, increasing the maximum speed of the capstan motor to speed up the phase control response.

Subsequently, when the sampling phase of the magnetic head 102a, a desired sampling phase within a predetermined range reached, that is, within the range which as described above in connection with in FIG. Exemplary embodiment shown 15, corresponding to a single track, a control signal is again the Attenuation coefficient control unit 24 supplied by the system controller 118 , to which the attenuation coefficient control unit 24 operates to switch the gain from the first small value to the second value for normal reproduction. In this way, the damping coefficient of the speed control system is kept at the second standard value, which is the normal or standard reproduction in the tracking control performed using the tracking error detection unit 20 , followed by the tracking operation in the state in which the stability of the control systems is ensured.

Although the damping coefficient control unit 24 is included in the speed control path in the case of the system shown in Fig. 19, the invention is not limited to such an arrangement. For example, the damping coefficient controller 24 may be included in the phase control system or loop to thereby relatively increase the control sensitivity during the process of restoring the phase to the desired track phase. Furthermore, the switching of the damping coefficient can be carried out at any time, provided that this precedes the transition to the tracking control. Accordingly, the switching of the damping coefficient is not limited to the time at which the phase error has converged on one track as mentioned above. In addition, the switching of the damping coefficient is not limited to a single switching, but can be carried out a number of times or step by step depending on the convergence in phase recovery to the predetermined track. As a result, various modifications are possible without departing from the spirit and scope of the present invention.

As is clear from the above description, according to the present invention, a magnetic recording / reproducing apparatus device created in which the control signal ver as the tracking control signal is used in the magnetic tape on which only for the speed variable playback at a given speed higher than that Normal playback speed is provided, provided digital image data at individual track positions according to the scanning path of the rotary magnetic head are recorded, the tracking control in the speed variant blen playback is subjected, and in which the marks the control signal according to the positions where the data for the speed variable Playback can be recorded, added, and the phases as production to the desired track to be scanned depending on the result of the phase comparison between the recognized brands at the variable-speed playback and the reference signal performed will, while after restoring the scanning phase of the rotating magnet the tracking control is performed on the predetermined area is made by the tracking error based on the additional information signals, the track identification number and the block identification number indicates which of the magnetic head itself reproduced signals are recognized. As a result, the Scanning position or phase of the magnetic head in the speed variable Playback operation restored or to the desired target track, the is intended for variable-speed playback be achieved while compatibility is realized during playback can be done without the need for tracking correction tools that have been available so far due to variations in the position of the control head below the VCRs were absolutely necessary. As a result, it can a tracking control device can be realized which is stable with high Accuracy can work.  

In addition, as a result of such an arrangement, as by the Invention is taught that the damping control for the speed speed control during the process of restoring the phase or Head position on the track for variable speed playback a smaller value can be switched, the track access speed be increased, which of course leads to the realization of tracking device contributes and improved quality of the reproduced image and ensures improved handling of the device.

Claims (11)

A magnetic recording / reproducing apparatus including: a recording apparatus for recording a signal on a magnetic tape ( 104 ) by means of a rotary head ( 102 ) and a reproducing apparatus ( 110 ) having a standard reproducing mode for reproducing the signal at a standard tape speed and a high-speed reproducing mode Reproducing the signal at a predetermined tape speed that is higher than the standard tape speed,
Record signal processing means ( 111 ) for processing a digital signal to be recorded so that the digital signal to be recorded in the high-speed playback mode is recorded at predetermined positions ( 406 , 407 ) on a plurality of predetermined tracks ( 403 , 404 ), data for high-speed playback so recorded to be located at positions along a scanning path of the rotary head ( 102 ) on the magnetic tape ( 104 ) in the high-speed playback mode;
Mark adding means ( 113 ) for generating marks (b, c) corresponding to positions on the track where digital signal data to be reproduced are recorded in the high speed playback mode, thereby adding these marks (b, c) to a control signal;
a control head ( 105 ) for recording the control signal with the marks (b, c) on the magnetic tape in accordance with the track positions when the signal is recorded by the recording device and for reproducing the control signal with the marks (b, c) when the signal is reproduced by the reproducing apparatus ;
Mark recognition means ( 117 ) for recognizing the mark from the reproduced control signal;
Phase comparison means ( 116 ) for detecting a phase difference between the marks (b, c) and a reference signal ( 112 ) which is generated in synchronism with the rotation of the rotary head ( 102 ); and
Capstan drive means ( 106 , 107 , 115 ) for controlling the speed of the magnetic tape ( 104 ) so that the phase difference assumes a predetermined reference value. The magnetic recording / reproducing apparatus according to claim 1, wherein the mark adding means ( 113 ) the mark (s) (b, c) by changing the nominal ratio of a single control signal or a plurality of successive control signals or alternatively by performing pulse width modulation of one or more Ren successive control signals generated during either a high level period or a low level period thereof. 3. The magnetic recording / reproducing apparatus according to claim 1, further comprising:
Means ( 20 ) for detecting a tracking error indicating a deviation between the track with the digital signal data recorded thereon to be reproduced in the high speed playback mode and an actual scanning path which the rotary head ( 102 ) actually follows; and
Phase adjustment means ( 116 ) for changing the phase of the mark (b, c) recognized by the phase comparison means or the phase of the reference signal ( 112 ) or alternatively changing the phase difference so that the tracking error disappears in the high-speed playback mode. 4. A magnetic recording / reproducing apparatus according to claim 3, wherein the mark adding means ( 113 ) generates the mark (s) (b, c) by the nominal ratio of a single control signal or a plurality of successive control signals or alternatively by performing pulse width modulation of the one or the plurality of successive control signals generated during either a high level period or a low level period thereof. 5. The magnetic recording / reproducing apparatus according to claim 3, wherein each of these tracks is formed by a plurality of data blocks, the digital signal being recorded distributed on the plurality of data blocks, and each of these data blocks containing a main information signal and an additional information signal recorded, that contains identification information indicating a lane identification number;
said tracking error detection means ( 20 ) including storage means ( 704 ) storing a data table containing the track identification numbers of specific tracks on which the digital signal data to be reproduced in the high speed playback mode is recorded and a reference frame identification number which is recognized when the specific track is scanned; contains; and
wherein the tracking error detection means ( 20 ) is a difference between the reference frame identification number contained in the data table and the frame identification number contained in the additional information signal which is obtained when the one or more special tracks are actually scanned according to the mark (s) (b, c) is reproduced by means of the rotary head ( 102 ) in the high-speed playback mode, in order to generate the tracking error signal corresponding to this difference. The magnetic recording / reproducing apparatus according to claim 3, wherein each of these tracks is formed by a plurality of data blocks, the digital signal including recorded on said plurality of data blocks, and wherein a main information signal and an additional information signal are recorded on each of these data blocks , which contains identification information indicating the track identification numbers;
said tracking error detection means ( 20 ) including storage means ( 704 ) for storing a data table, the relationships between the track identification numbers of specific tracks with the digital signal data recorded thereon to be reproduced in the high-speed playback mode and a reference time for detecting a predetermined track of one Indicates the time at which scanning of the particular track is needed, and a timer for measuring an elapsed time from the start of that track scanning; and
wherein the tracking error detection means ( 20 ) detects a real time using said timer ( 706 ) for the detection of the predetermined track from a point in time at which the rotary head ( 102 ) actually scans one or more of the special tracks ( 403 , 404 ) corresponding to the mark (n) (b, c) started in the high-speed playback mode, is taken, and then detects a difference between the reference time contained in the data table and the detected real time, thereby generating the tracking error signal according to this difference. The magnetic recording / reproducing apparatus according to claim 3, wherein the phase adjusting means adjusts either the phase of the mark or the phase of the reference signal depending on the signals generated by the tracking error detecting means ( 20 ) in a direction in which the difference becomes zero or in alternatively, the value of the phase difference output from the phase difference detection means is modified so that the difference becomes zero. 8. The magnetic recording / reproducing apparatus according to claim 1, further comprising:
High speed run control means ( 9 ) for enabling the magnetic tape ( 104 ) to run higher than the standard speed in the high speed playback mode at this predetermined speed;
Means ( 20 ) for detecting a tracking error indicating a deviation between the track on which the digital signal data to be reproduced in the high-speed reproduction mode and the actual scanning path of the rotary head ( 102 ) in the high-speed reproduction mode;
Switching means ( 121 ) responsive to a control signal to selectively output either a single one of the phase difference to be supplied by the phase comparison means ( 116 ) or the tracking error supplied by the tracking error detection means ( 20 ); and
Control means ( 118 ) for generating the control signal to cause the switching means to select the tracking error supplied by the tracking error detection means ( 20 ) when the magnetic tape ( 104 ) reaches the predetermined speed while allowing the switching means ( 121 ) to do so select switching errors supplied to the tracking error detection means ( 20 ) when the phase difference is within a predetermined range in the high-speed reproduction mode;
wherein the capstan drive means ( 106 , 107 , 115 ) responds to the output of the switching means ( 121 ) to thereby control the running speed of the magnetic tape ( 104 ) so that the phase difference assumes a predetermined reference value or, alternatively, the tracking error Becomes zero. The magnetic recording / reproducing apparatus according to claim 8, wherein the mark adding means ( 113 ) the mark (s) (b, c) by changing the nominal ratio of one or more control signals or alternatively by performing pulse width modulation of the one or more successive Control signals generated during either a high level period or a low level period thereof. 10. The magnetic recording / reproducing apparatus according to claim 8, further comprising:
Means (24) for setting a control attenuation coefficient, if the capstan drive means (106, 107, 115) controls the running speed of the magnetic tape (104), said Dämpfungskoeffizienteinstellmittel (24) uses a first damping coefficient until the power supplied from the phase comparison means (116) Phase difference has reached a predetermined value while using a second attenuation coefficient larger than the first attenuation coefficient after the phase difference supplied by the phase comparison means ( 116 ) has reached the predetermined value. The magnetic recording / reproducing apparatus according to claim 10, wherein the mark adding means ( 113 ) generates the marks (b, c) by changing the nominal ratio of the one or more successive control signals, or alternatively by the pulse width modulation of the one or the several successive control signals during either a high level period or a low level period thereof.