Magnetic recording and reproducing apparatus

Abstract: A magnetic recording and reproducing apparatus capable of recording video, audio and other information on a magnetic tape by, for example, the helical scanning method. A rotary head is rotated at an m-fold speed to record intermittent tracks on the magnetic tape so that real-time simultaneous monitoring is performed. By high-speed dubbing due to high-density intermittent recording and by increasing the number of repetition of track scanning, the information is recorded and reproduced simultaneously with a plurality of channels. Any tracking error is detected to form a continuous and uniform track pattern. With this intermittent comb-shaped recording, reciprocating recording and reproducing can be realized.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: This invention relates to a magnetic recording and reproducing apparatus for recording video and audio information on a magnetic tape in a helically scanning system. 2. Description of the Related Art: For accurately recording a digital video signal and a digital audio signal by a digital video tape recorder, it has hitherto necessary to confirm the state of recording by reproducing the recorded data soon after recording, namely, to perform simultaneous monitoring. FIG. 10 shows one example of a tape format for a magnetic recording reproducing apparatus which enables reciprocating reproducing, the tape format being described in, for example, a book "NHK Home Video Description" (page 213) issued from Japan Broadcasting Association (Nippon Hoso Kyokai). A magnetic tape 510 is 1/2 inch wide, on which surface each track is formed in the following format. Specifically, a video track 511-V1 is a track on and from which video signals are to be recorded and reproduced in the direction of forward tape feed; an audio track 511-A1 is a track on and from which audio signals are to be recorded and reproduced in the direction of forward tape feed; a video track 511-V2 is a track on and from which video signals are to be recorded and reproduced in the direction of reverse tape feed; and an audio track 511-A2 is a track on and from which audio signals are to be recorded and reproduced in the direction of reverse tape feed. The object of this prior art apparatus using such a tape format is to enable long-time recording and recording and reproducing band of audio signals by reciprocatingly use the magnetic tape 510. By multiplying the rate of magnetic tape feed about two times, the tape format of FIG. 10 can be formed within a width (1/4 inch) which is a half of the magnetic tape 510 having a 1/2-inch width as used in the VHS method or such. The formed tape format includes the video tracks 511-V1, 511-V2 for recording and reproducing in the helically scanning method and the audio tracks 511-A1, 511-A2 for recording and reproducing on linear tracks. For example, using the lower half (1/4 inch) of the magnetic tape 510 during forward tape feed, the video signals are recorded on the video track 511-V1, and the audio signals are recorded on the audio track 511-A1. Then, when the direction of the magnetic tape feed becomes relatively reversed by turning the magnetic tape 510 inside out, the video signals and the audio signals are recorded on the video track 511-V2 and the audio track 511-A1, using the lower half (1/4 inch) of the magnetic tape 510. Concerning the recording and reproducing of video signals, this prior system is equivalent to only one-way recording and reproducing of the VHS method, but the audio signals for recording and reproducing to the linear track is increased in relative speed to improve the recording and reproducing band of the audio signals. With this prior magnetic recording and reproducing apparatus, it is necessary to turn the magnetic tape inside out when the direction of tape feed is switched from the forward to the reverse and vice versa. Also it is impossible to switch the tape feed direction instantly. SUMMARY OF THE INVENTION With the foregoing prior art problems in view, following are objects of this invention: to enable instant switching from forward tape feed to reverse tape feed and vice versa and to keep signals in high quality. This objects are achieved by a magnetic recording and reproducing apparatus having the features mentioned in claim 1. The invention is further developed by the features indicated in the subclaims. With this arrangement, the direction of feed of the magnetic tape is reciprocated and inverted by a tape feed direction control means. During forward recording, one track for every two-track space is formed on the magnetic tape. Namely, by selectively driving the magnetic head, a half space is used for recording. Then during backward recording, a space other than the space used for recording during the forward recording is used for recording. Namely, recording is performed between the tracks formed by the forward recording. During forward reproducing, by selectively driving the magnetic head, a half track is scanned for reproducing. Then during backward reproducing, a track other than the track scanned for reproducing during the forward reproducing is scanned for reproducing. Namely, reproducing is performed between the tracks scanned by the magnetic head during the forward reproducing. As a result, it is possible to make an instantaneous shift from forward recording/reproducing to backward recording/reproducing, without forcing the user to reset the magnetic tape as conventional. Also, adequate quality can be achieved. The track designating means may include a tracking control means for controlling the tracking position of the magnetic head and fixing the scanning direction of the magnetic head which is now performing recording and reproducing, thus improving the quality. The tracking control means may include a forward track detecting means, a tracking storage, and a scanning direction adjusting means. The forward track detecting means detects the position of the target track of backward recording and backward reproducing by one of the magnetic heads which is not performing recording and reproducing. The tracking storage stores the detected position of the track. The scanning direction adjusting means adjusts the scanning direction of one of the magnetic heads which is associated with the backward recording and backward reproducing based on the position stored in the tracking storage. The arrangement may additionally include the following. An A/D converter and a D/A converter; the former converts analog recording signals into digital recording signals, and the latter converts digital reproducing signals into analog reproducing signals. Using these converters, it is possible to cope with the case in which signals to be exchanged between this apparatus and the exterior must be analog. Therefore digital signals can be recorded and reproduced on and from the magnetic tape. Further, a time axis compressing means for compressing the time axis of the recording signal by 1/m times, and a time axis expanding means for expanding the time axis of the reproducing signal by m times. Some of the foregoing five arrangements need both of the two means, and also to the remaining arrangements, these two means are effective in recording all of information contained in the signals supplied from the exterior. In recording and reproducing digital signal accurately, the apparatus should preferably include means for encoding the digital recording signal for error correction, and means for decoding the digital reproducing signal for error correcting. Further, in recording and reproducing the digital recording signal in code suitable for recording and reproducing on and from the magnetic tape, the apparatus should preferably include means for encoding the digital recording signal for recording, and means for decoding the digital reproducing signal for recording. Finally, for using the magnetic head commonly in recording and reproducing, the apparatus should preferably include a recording/reproducing switching means. The above and other advantages, features and objects of this invention will be manifest to those versed in the art upon making reference to the following detailed description and the accompanying drawings in which several preferred embodiments incorporating the principles of this invention are shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a magnetic recording and reproducing apparatus according to an embodiment; FIG. 2 is a diagram showing a track pattern on the magnetic tape when the magnetic tape is fed in the forward direction in the embodiment; FIG. 3 is a diagram showing a track pattern on the magnetic tape when the magnetic tape is fed in the backward or reverse direction in the embodiment; FIG. 4 is a diagram showing data to be recorded and the movement of the magnetic heads when the magnetic tape is fed in the forward direction in the embodiment; FIG. 5 is a diagram showing data to be recorded and the movement of the magnetic heads when the magnetic tape is fed in the backward or reverse direction in the embodiment; FIG. 6 is a diagram showing data to be reproduced and the movement of the magnetic heads when the magnetic tape is fed in the forward direction in the embodiment; FIG. 7 is a diagram showing data to be reproduced and the movement of the magnetic heads when the magnetic tape is fed in the backward or reverse direction in the embodiment; FIG. 8 is a diagram showing a track pattern on the magnetic tape when the magnetic tape is fed in the forward direction according to a second embodiment; FIG. 9 is a diagram showing track pattern when the magnetic tape is fed in the backward or reverse direction in the second embodiment; FIG. 10 is a diagram showing a track pattern on the magnetic tape in a magnetic recording and reproducing apparatus according to the prior art. DETAILED DESCRIPTION FIG. 1 shows a digital recording and reproducing apparatus according to an embodiment. In FIG. 1, 2010 designates a magnetic tape; 2001-1, a first magnetic head; and 2001-2, a second magnetic head. The rotary drum 2002 causes the first and second magnetic heads 2001-1, 2001-2 to rotate, thus enabling helical scan recording. A first magnetic head actuator 2016-1 causes the first magnetic head 2001-1 to move perpendicularly to the direction of scanning by the rotary drum 2002. A second magnetic head actuator 2016-2 causes the first magnetic head 2001-2 to move in the same manner as that by the first magnetic actuator 2016-1. FIG. 1 further shows capstans 2082-1, 2082-2 for feeding the magnetic tape 2010 at a constant speed, pinch rollers 2114-1, 2114-2, and a tape feed control circuit 2089 for controlling the feed speed of the magnetic tape 2010 by controlling the capstans 2082-1, 2082-2 and the pinch rollers 2114-1, 2114-2 and for enabling the reciprocating feed of the magnetic tape 2010. A tracking control circuit 2014 controls the position of the magnetic heads 2001-1, 2001-2, based on a tracking error signal, by controlling the magnetic head actuators 2016-1, 1016-2. A tracking memory 2115 stores one track of the amount of control from the tracking control circuit 2014 to the magnetic head actuators 21-6-1, 2106-2. A head switch 2033 switches the connection between the magnetic heads and the circuits. This switching is performed in response to a head switch changeover signal. FIG. 2 shows a track pattern on the magnetic tape 2010 in this embodiment. This track pattern is a recording track pattern during forward tape feed. A track 2011-1 is a forward track on which the first magnetic head 2001-1 makes forward recording during the first rotation of the rotary drum 2002, and a track 2011-2 is a forward track on which the first magnetic head 2001-1 makes forward recording during the second rotation of the rotary drum 2002. During the next rotation of the rotary drum 2002, the first magnetic head 2001-1 makes recording on the track 2011-3 and further recording on the track 2011-4 during next to the next rotation. FIG. 3 shows a recording track pattern during reverse or backward tape feed. During the first rotation of the rotary drum 2002, the second magnetic head 2001-2 makes recording on a reverse or backward track 2011-5. During the second rotation of the rotary drum 2002, the second magnetic head 2001-2 makes recording on a reverse or backward track 2011-6. Further, at the time point of FIG. 3, a track 2011-7 is being formed·recorded by the second magnetic head 2001-2. In FIG. 3, inclined lines in the track pattern indicate the azimuthal angle of the magnetic heads 2001-1, 2001-2. FIGS. 4 shows data to be recorded and the movement of the magnetic heads when the magnetic tape is fed in the forward direction, and FIG. 5 shows data to be recorded and the movement of the magnetic heads when the magnetic tape is fed in the backward or reverse direction. Also shown in FIGS. 4 and 5 are recording video data, recording data obtained as the result of time axis compression and modulation by encoding the recording video data, the scanning manner of the first magnetic head 2001-1, and the scanning manner of the second magnetic head 2001-2. FIG. 5 further shows the content of the tracking memory 2115. Each of the frame portions on a line indicating the scanning of the head represents a magnetic head tracing period. Of various patterns in the individual frames, a checker pattern represents the magnetic head fixing state; a hatched pattern, the control amount applying state; and a zigzag pattern, the tracking state. FIG. 36 shows data to be reproduced and the movement of the magnetic heads when the magnetic tape is fed in the forward direction. FIG. 7 shows data to be reproduced and the movement of the magnetic heads when the magnetic tape is fed in the backward or reverse direction. In FIGS. 6 and 7, recording video data and recording data are substituted by reproducing video data and reproducing data which are reproduced prior to demodulation, decoding and time-axis expansion. In operation, the rotary drum 2002, unlike a rotary drum in a magnetic recording and reproducing apparatus in which the VHS method is used, is driven to rotate in the following manner. Specifically, in the VHS method, during the period corresponding to one frame (one cycle of scanning of information) of a recording video signal, the rotary drum makes one rotation. During this one rotation, two tracks are recorded on the magnetic tape. In this embodiment, by doubling the number of rotations of the rotary drum 2002, the rotary drum 2002 makes two rotations during the period corresponding to one frame, and the first and second magnetic heads 2001-1, 2001-2 trace two tracks twice (i.e., scan four tracks in total). Further, by doubling the feed speed of the magnetic tape 2010, it is possible to obtain an adequate width of the tracks. Here to record one field for one track, it is necessary to compress the time axis for recording. This embodiment is directed particularly to a digital VTR for digitally processing video signals and performing recording and reproducing. In the following description, explanation concerning audio signals is omitted. Practically, audio signals together with video signals are recorded and reproduced as digital data. In the recording system, a recording video signal is first band-restricted by the LPF 2050 so that only the video signal band component is sampled by the A/D converter 2051 in a predetermined synchronism to convert analog signals into digital video data. To the digital video data, error correction codes or such are added by the encoder 2052 so that recording/reproducing with no error can be performed. This encoding is performed by using a buffer memory 2038. In the encoder 2052, at the same time, compressing of the time axis is performed, and the time-axis-compressed data are outputted. The digital video data are further encoded, by the modulator 2053, into optimum codes suitable for recording/reproducing on the magnetic tape 2010. The recorded and encoded data are recorded on the magnetic tape 2010 by the magnetic head 2001-1 or 2001-2 via the magnetic head amplifier 2042 and the head switch 2033. Here, a head switch changeover signal is generated in synchronism with the rotation of the rotary drum 2002 as the rotary drum 2002 is switched at every 1/2 rotation by the head switch 2033. In the reproducing system, the signals reproduced by the magnetic heads 2001-1, 200-2 are supplied, via the head switch 2033, to the reproducing amplifier 2043 for amplifying. The resulting signal is decoded, for recording, by the demodulator 2054 as reproducing digital video data. As a result, the original data before encoding by the modulator 2053 is obtained. Errors of the original data are corrected and detected by the decoder 2055. Here in decoding, a buffer memory 2101 is used. The output of the decoder 2055 is time-expanded to restore the original time axis of the data. The reproducing digital video data are converted back into analog video signals by the D/A converter 2056 and are band-restricted by the LPF 2057. As a result, reproducing video signals are obtained. With the foregoing digital processing, data of one field are recorded/reproduced on one track. The reciprocating recording/reproducing method will now be described. The magnetic tape 2010 are fed by capstans 2082-1, 2082-2 and pinch rollers 2114-1, 2114-2 disposed on opposite sides of the rotary drum 2002. The direction of feed of the magnetic tape is switched between forward and backward by a tape feed control circuit 2089. During reproducing and backward recording, the tape feed control circuit 2089 controls, by the pilot signal recorded in the track, the phase between the capstans 2082-1, 2082-2 and the rotary drum 2002 in such a manner that the magnetic heads 2001-1, 2001-2 scan near the individual track. The recording track pattern when the magnetic tape is fed in the forward direction is such as shown in FIG. 2. Namely, in this case, recording is performed by only the first magnetic head 2001-1; during the first rotation of the rotary drum 2002, data of the first field in one frame are recorded on a forward track 2011-1. During the second rotation of the rotary drum 2002, data of the second field are recorded on a forward track 2011-2. Data are thereby recorded on the magnetic tape 2010 every other track (skipping a space where a reverse and backward track is to be formed). Further, when the magnetic head is fed in the reverse or backward direction, recording is performed by only the second magnetic head 2001-2. During the first rotation of the rotary drum 2002, data of the first field are recorded on the backward track 2011-5. During the second rotation, data of the second field are recorded on the backward track 2011-6. However, when the magnetic tape is fed in the backward or reverse direction, the angle of inclination of the recording track is apt to be slightly different, compared to the case in which the magnetic tape is fed in the forward direction. Therefore, for compensating this difference, a movable magnetic head must be used to record data on the backward track between the adjacent forward tracks. To this end, in this embodiment, as shown in FIG. 1, there are provided a magnetic head actuator 2106-1 for moving the first magnetic head 2001-1 and another magnetic head actuator 2106-2 for moving the second magnetic head 2001-2. In recording by such movable magnetic heads, for example, when the magnetic tape is fed in the forward direction, the positions of the magnetic head actuators 2106-1, 2106-2 are controlled by the tracking control circuit 2014 to fix the magnetic heads 2101-1, 2101-2 in predetermined positions, thus recording by the first magnetic head 2101-1. This operation will now be described in greater detail with reference to FIG. 4. Firstly, recording video data W-DATA1, W-DATA2, ... are encoded, time-compressed and modulated. The resulting data are supplied to the first magnetic head 2001-1 as recording data WP1, WD2 .... The first magnetic head 2001-1 is fixed in position, and the recording data are recorded by only this first magnetic head 2001-1. Accordingly the track pattern will be intermittent as shown in FIG. 2. Then when the magnetic tape is fed in the backward direction, as shown in FIG. 5, the scanning by the first magnetic head 2001-1 which is the preceding head is performed prior to the scanning by the second magnetic head 2001-2 which is the recording head. The object of this scanning is the preceding adjacent track recorded (i.e., forward track). At that time, the output of the first magnetic head 2001-1 is supplied to the reproducing amplifier 2043, and the tracking control circuit 2014 detects a tracking error signal from an envelop of the reproducing signal, i.e., the output of the reproducing amplifier 2043. The tracking control circuit 2014 controls the first magnetic head actuator 2106-1 to control the position of the first magnetic head 2101-1, thereby scanning the forward track by the first magnetic head 2101-1. Here, the tracking control circuit 2014 stores in the tracking memory 2115 an amount of control of the first magnetic head actuator 2106-1 which amount is equivalent to the amount of deviation to the track inclination of one track. Then, the position of the second magnetic head 2106-2 scanning on the magnetic tape 2010 is controlled, by the second magnetic head actuator 2016-2, so as to follow the forward track 2011-1 or the forward track 2011-2, depending on the amount of control that are read from the tracking memory 2115 by the tracking control circuit 2014. FIG. 5 shows the flow of forward recording. In FIG. 5, recording data are recorded by the second magnetic head 2001-2. At that time, the first magnetic head 2001-1 which is the preceding head makes tracking, and the tracking control circuit 2014 reads the amount of control TR1, TR2, ... to store it in the tracking memory 2115. Thus the amount of control stored in the tracking memory 2115 is used for controlling the second magnetic head actuator 2106-2 in recording the recording data on the magnetic tape 2010. Reproducing is performed in the same method. First when the magnetic tape is fed in the forward direction, as shown in FIG. 6, the positions of the magnetic head actuator 2106-1, 2106-2 are controlled to fix the magnetic heads 2001-1, 2001-2 at respective predetermined positions. In addition, data on the forward track are reproduced by only the first magnetic head 2001-1. The reproducing data RD1, RD2, ... reproduced by the first magnetic head 2001-1 are demodulated, decoded and time-expanded, thus becoming reproducing video data R-DATA1, R-DATA2 .... Then when the magnetic tape is fed in the backward direction, as shown in FIG. 7, the first magnetic head 2001-1 makes tracking of the preceding adjacent track (i.e., forward track) prior to the second magnetic head 2001-1 which is the reproducing head. Here, likewise during the recording, the amount of control of the first magnetic head actuator 2106-1 is stored in the tracking memory 2115. The second magnetic head 2002-2 traces the magnetic tape 2010 to do reproducing based on the content of the tracking memory 2115. Namely, the amount of control TR1, TR2, ... stored in the tracking memory 2115, i.e. the result of the tracking by the first magnetic head 2001-1, is applied to the second magnetic head actuator 2106-2 during reproducing by the second magnetic head 2001-2. As mentioned above, the first magnetic head 2001-1 makes recording/reproducing when the magnetic tape is fed in the forward direction and tracking of the forward track, while the second magnetic head 2001-2 makes recording and reproducing when the magnetic tape is fed in the backward direction. Therefore, reciprocating recording/reproducing can be realized. In this embodiment, the forward track and the backward track are alternately arranged. The forward and backward tracks may be arranged in an alternative pattern such as shown in FIGS. 8 and 9. In recording when the magnetic tape is fed in the forward direction, the first magnetic head 2001-1 records on the forward track 2011-1 during the first rotation of the rotary drum 2010, and the second magnetic head 2001-2 records the forward track 2011-2 during the same first rotation. In recording when the magnetic tape is fed in the backward direction, the first magnetic head 2001-1 makes tracking of the forward track 2011-1 during the first rotation of the rotary drum 2010. The amount of control at that time is stored in the tracking memory 2115, and the second magnetic head 2001-2 at the first rotation of the rotary drum 2010 records the backward track 2011-5, with applying the amount of control to the second magnetic head actuator 21001-2. Further, the first magnetic head 2001-1 at the second rotation of the rotary drum 2010 records the backward track 2011-6, with applying to the first magnetic head actuator 2106-1 the amount of control by which the forward track 2011-1 was subjected to tracking. Then in reproducing when the magnetic tape is fed in the forward direction, like during recording, the first and second magnetic heads 2001-1, 2001-2 perform reproducing of the forward track 2011-1, 2011-2 during the first rotation of the rotary drum 2010. Also when the magnetic tape is fed in the backward direction, the forward track 2011-1 is subjected to tracking so that the backward tracks 2011-5, 2011-6 are reproduced by the first and second magnetic heads 2001-1, 2002. In this embodiment, only one magnetic head is used. Alternatively, two magnetic heads are fixed on the magnetic head actuators in combination. Further in this embodiment, one cycle of information is defined as one frame, and one cycle of information is recorded on two tracks. Alternatively, one cycle of information may be one field, or one field plus an integral number of frames. The number of tracks on and from which one cycle of information is to be recorded and reproduced should not be limited to any specific number. As mentioned above, partly since during one cycle scanning period of information the rotary drum is rotated at a more-than-one-fold speed to scan 2N or more tracks during one cycle scanning period, partly since intermittent forward recording/reproducing is performed on the magnetic tape at the forward scanning track by a plurality of magnetic heads and, during the backward scanning track, a plurality of or one magnetic head are caused to follow the forward recorded portion by the tracking control circuit, and partly since backward recording/reproducing is performed, during part of forward recording/reproducing on tracks of the magnetic heads, by storing the amount of head position control and by applying the amount of head position control stored in the magnetic head actuators which moves the magnetic heads making backward recording, it is possible to instantaneously switch from forward recording/reproducing to backward recording/reproducing and vice versa without turning the magnetic tape inside out, thus enabling reciprocating recording/reproducing. Further, it is possible to increase the number of scanning tracks so that video·audio signals can be recorded/reproduced with high quality.

Claims: A magnetic recording and reproducing apparatus comprising (a) a rotary drum (2002) having an outer periphery which is frictionally engageable with a magnetic tape (2010) in such a manner that the axis of rotation of said rotary drum is disposed at a predetermined angle with respect to the moving direction of the magnetic tape; and (b) ℓ pairs (ℓ stands for an integer equal to or larger than 1) of magnetic heads (2001-1, 2001-2) each pair of which includes two magnetic heads disposed adjacent to each other on the outer periphery of said rotary drum for performing scanning on the magnetic tape so as to record on a predetermined-width track on the magnetic tape a recording signal to be applied during recording, and so as to pick up a reproducing signal from the predetermined-width track on the magnetic tape during reproducing; characterized by (c) a tape feed direction control means (2089) for reciprocating and inverting the direction of feed of the magnetic tape; and (d) a track designating means (2016-1, 2016-2) for selectively actuating one of a pair of magnetic heads to perform recording and reproducing on one track per two tracks during forward-recording and forward-reproducing and for actuating the other of a pair of magnetic heads for the tracks other than said one track of the forward-recording and forward-reproducing during backward-recording and backward-reproducing. A magnetic recording and reproducing apparatus according to claim 1, wherein said track designating means includes a tracking control means (2014) for controlling the tracking positions of said magnetic head to fix the scanning direction of said magnetic heads which is presently performing recording and reproducing. A magnetic recording and reproducing apparatus according to claim 2, wherein said tracking control means includes: a forward track detecting means for detecting the position of the target track of forward-recording and forward-reproducing by one of said magnetic heads which is not performing recording and reproducing during backward-recording and backward-reproducing; a tracking storage (2115) for storing the detected position of the track; and a scanning direction adjusting means for adjusting the scanning direction of one of said magnetic heads which is associated with backward-recording and backward-reproducing based on the position stored in said tracking storage means. A magnetic recording and reproducing apparatus according to claim 1, further comprising: an A/D converter (2051) for converting an analog recording signal into a digital recording signal and for supplying the latter to said magnetic head; and a D/A converter (2056) for converting a digital reproducing signal, which is picked up by said magnetic head, into an analog reproducing signal. A magnetic recording and reproducing apparatus according to claim 1, further comprising: a time axis compressing means for compressing the time axis of the recording signal by 1/m times and for supplying the compressed recording signal to said magnetic head; and a time axis expanding means for expanding the time axis of the reproducing signal by m times. A magnetic recording and reproducing apparatus according to claim 1, further comprising: means for encoding (2052) the digital recording signal for error correction; and means for decoding (2055) the digital reproducing signal for error correction. A magnetic recording and reproducing apparatus according to claim 1, further comprising: means for encoding (2052) the digital recording signal for recording; and means for decoding (2055) the digital reproducing signal for recording. A magnetic recording and reproducing apparatus according to claim 1, further comprising a recording/reproducing switching means (2033) for supplying a recording signal to said magnetic head during recording and for taking out a recording signal from said magnetic head during reproducing.

Inventors: HONGO KIMITOSHI, ONISHI KEN, TAKADA YUKARI, HONGO, KIMITOSHI, ONISHI, KEN, TAKADA, YUKARI, HONGO, KIMITOSHI, C/O MITSUBISHI DENKI ENG. K.K., ONISHI, KEN, C/O MITSUBISHI DENKI K.K., TAKADA, YUKARI, C/O MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: G11B5
IPC codes: G11B15, H04N9, G11B27, G11B5, H04N5, G11B20