|Publication number||USRE39029 E1|
|Application number||US 10/349,954|
|Publication date||Mar 21, 2006|
|Filing date||Jan 24, 2003|
|Priority date||Oct 20, 1994|
|Also published as||DE69520401D1, DE69520401T2, EP0708436A2, EP0708436A3, EP0708436B1, EP1026664A2, EP1026664A3|
|Publication number||10349954, 349954, US RE39029 E1, US RE39029E1, US-E1-RE39029, USRE39029 E1, USRE39029E1|
|Inventors||Kouhei Baba, Haruo Ohta, Hideaki Mukae, Jun Takeuchi, Haruo Isaka|
|Original Assignee||Matsushita Electric Industrial Co., Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (18), Non-Patent Citations (1), Classifications (20), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a reissue application of U.S. Pat. No. 5,953,482, issued Sep. 14, 1999.
This application is a continuation of now abandoned application, Ser. No. 08/544,535, filed Oct. 18, 1995, now abandoned.
1. Field of the Invention
This invention relates to a magnetic recording/reproducing apparatus for recording audio signals and video signals.
2. Description of the Prior Art
In a video tape recorder (VTR), transmission of a signal between a magnetic head and RF circuit is made through rotary transformers. In general and in a business-purpose VTR or the like, the RF circuit may be carried on the cylinder. Here, the RF circuit includes a recording amplifier, a reproducing amplifier, an equalizer and the like.
In the case of business-purpose VTR, simultaneous playback function and insert-editing function are essential in order to ensure the editing performance. As a result, a recording head, a reproducing head and an erasing head are required to be disposed on the cylinder. Here, the simultaneous playback function is a function to perform recording and reproduction simultaneously, which is necessary for confirming a recorded state or performing editing.
Referring to head-arrangement, It is general to dispose a plurality of heads at equal intervals peripherally of the cylinder in order to make sure of good head-to-tape contact and easy signal processing. Here, the head-to-tape contact indicates contact condition of head and tape. Also, disposing a plurality of heads at equal intervals peripherally of the cylinder is to arrange them equlangularly on the cylinder. In this case, however, when the tape winding angle is 180 degrees, two heads in pair or Ach (channel) head and Bch head are disposed so as to make an angle of 180 degrees with each other on the cylinder or diametrically oppositely disposed thereon.
Referring to a rotary transformer construction, a crosstalk measure between channels by providing short-rings between the recording/reproducing/erasing channels is taken thereby the rotary transformer forming a core of one body type. Conventional examples shown above can be clearly seen in a commercially available business-purpose video cassette recorder (VCR), for example, a D3 standard VCR or a D5 standard VCR, or in commercially available VCR, for example, a VHS standard VCR.
Recently, down-sizing a main body of a home-use VTR and even of business-purpose one has been required. In order to meet such requirement, it is necessary to make a diameter of the cylinder small (a small cylinder) and a recording track-pitch narrow (narrow track-pitch recording). However, with a VTR of having narrow track-pitch recording by the with a small cylinder, the following problems may be arisen as arise:
However, in the case of the narrow track-pitch recording, as because the recording trackwidth is narrow originally, the narrowing track and the off-tracking as its cause when editing are required to be further reduced than would be made by the conventional ones, which is difficult to be attained at a conventional tracking accuracy.
With the VTR of narrow track-pitch recording by the small cylinder, however, the erase timing and the record timing are difficult to be set so as to satisfy the editing accuracy by applying such a conventional method that uses a PG signal from the cylinder (a rotational phase detecting signal of the cylinder), an FG signal from the motor (rotational frequency control signal of the motor), and a control signal from the linear track.
An object of this invention is to provide a magnetic recording/reproducing apparatus capable of realizing following functions with a VTR of narrow track-pitch recording by a small cylinder as: (1) a simultaneous playback function, (2) editing functions such as insert-editing and (3) a reproduction compatible function to any tape recorded in the long play mode with a different track-pitch (or, with further narrow track-pitch).
To achieve this object, a magnetic recording apparatus of this invention comprises: a rotary cylinder for winding thereon a video tape over an angle of substantially 180°; first and second recording heads mounted on the rotary cylinder at positions apart from each other by 180° in a rotating direction of the rotary cylinder for recording on the video tape first-channel and second channel video signals, respectively; and first and second erasing heads mounted on the rotary cylinder at positions apart from each other by 180° in the rotating direction of the rotary cylinder for erasing first-channel and second channel video signals, respectively recorded on the video tape, wherein the first recording head and the first erasing head are disposed adjacent to each other in the rotating direction of the rotary cylinder, and the second recording head and the second erasing head are disposed adjacent to each other in the rotating direction of the rotary cylinder.
Preferably, a magnetic recording and reproducing apparatus of this invention comprises: a rotary cylinder; a recording head mounted on the rotary cylinder; an erasing head mounted on the rotary cylinder; a reproducing head mounted on the rotary cylinder; a first rotary transformer disposed on a first core and coupled to the recording head; a second rotary transformer disposed on the first core and coupled to the erasing head; a third rotary transformer disposed on a second core and coupled to the reproducing head; and a conduct shielding member disposed between the third rotary transformer and the first and second rotary transformers.
With constructions as shown above, even with the magnetic recording and reproducing apparatus which performs narrow track-pitch recording by a small cylinder, simultaneous recording and reproduction can be attained by maximizing a distance between the reproducing head and the recording/erasing heads and at the same time, by taking such a shield measure that the rotary transformer for the reproducing head is disposed dependently at the upper portion of the cylinder. Furthermore, the erase/record timing setting and tracking when editing (particularly when insert-editing) are made possible by providing optimum arrangement of the recording/erasing heads. Besides, by reproducing function by the recording head, a reproduction compatible function to a long-time recording format recorded at a narrower track-pitch by the cylinder having a same diameter and a same lead angle can be realized.
A magnetic recording/reproducing apparatus according to an embodiment of this invention will be described on in relation to its operation when insert-editing, circuit structure in response to a simultaneous recording and reproduction, and reproduction compatible function to the long-time recording format in this order.
In this embodiment, a tape winding angle is substantially 180 degrees and a number of a recording channel is one (1), which means that it is not of the multi-channel system recording but of the one-channel system recording.
Next, referring to the head width of each head, track-pitch Tp2 and recording trackwidth, if the recording head width is expressed as HWrec, the reproducing head width is expressed as HWpb and the erasing head width is expressed as HWer, the relation as HWpb, HWer>Tp2≧HWrec may be obtained. Also, there does not impose particular limitation on the relation between the reproducing head width HWpb and erasing head width HWer.
First, explanations will be made from the recording system. A recording signal is received from an input terminal 23 and supplied through a recording system signal processor 24 to a recording amplifier 25 and a recording amplifier 26. The recording system signal processor 24 converts the input signal into an optimal signal to be recorded and supplied to the recording amplifier 25 and recording amplifier 26 at a predetermined timing. The signal supplied to the recording amplifier 25 is sent through a switching circuit 27 to the recording head 1 at the desired recording timing and recorded on a tape 56. On the other hand, the signal supplied to the recording amplifier 26 is sent through a switching circuit 28 to the recording head 4 at the desired recording timing and recorded on the tape 56. The recording head 1 and the recording head 4 are used for recording in general and functional as reproducing heads, respectively, in a part of the track when editing and recording and reproducing simultaneously, or in the all tracks when compatibly reproducing the tape having been recorded in the long play mode. The switching circuits 27 and 28 are for switching the recording heads 1 and 4 between recording and reproducing sides, respectively. In case that the switching circuits 27 and 28 are switched to the reproducing side, the signals are sent through a reproducing amplifier 29 and a reproducing amplifier 30 and a head switching circuit 31 to a reproducing system signal processor 32. The head switching circuit 31 is controlled by the head switching signal supplied from an input terminal 39. The reproducing system signal processor 32 processes the signal from the reproducing amplifiers to output to an output terminal 32, and during editing and simultaneous recording and reproducing operations, supplies the track information data 55 to a timing generator 34 and at the same time, supplies a control signal 54 to a tracking controller 57. The tracking controller 57 is to track each head basically by the control signal 54 generated from the reproduced signal by the recording head when recording (including editing and simultaneous recording and reproducing) and compatibly reproducing of the long play mode, and by a control signal 53 generated from the reproduced signal by the reproducing head when normally reproducing. The timing generator 34 supplies record timing signals 46, 47 and 48 to the recording system signal processor 24, the recording amplifier 25 and the recording amplifier 26, respectively, in response to the track information data single signal 55 and a mode identification signal received from the input terminal 58. Also, the timing generator 34 supplies the switching circuits 27 and 28 with recording/reproducing mode switching control signals 49 and 50, respectively. Furthermore, the timing generator 34 supplies the erasing amplifiers 36 and 38 with erase timing signals 51 and 52, respectively. Referring to the erasing system, erasing signals generated by erase frequency oscillators 35 and 37 are amplified by erasing amplifiers 36 and 38 and supplied to the erasing heads 2 and 3 5 at the desired erase timing, respectively.
Referring to the reproducing system, reproduced signals reproduced through the reproducing heads 3 and 6 from the tape 56 are supplied respectively through reproducing amplifiers 40 and 41 to a head switching circuit 42. The reproduced signal switched by a head switching signal supplied from an input terminal 45 is processed through a reproducing system signal processor 43 and supplied to an output terminal 44. Here, the reproducing system signal processor 43 supplies the control signal 53 to the tracking controller 57.
Next, explanations will be made on the operation when insert-editing of this embodiment, which will be made mainly on the operation of each head on the Ach side when the audio data region 22 shows in
When editing such as insert-editing in VTR, the erase timing and tracking are required to be decided prior to the recording. However, in the case of VTR of narrow track-pitch recording, with the conventional method using PG signal from the cylinder, FG signal from the motor and control signal from the linear track, it is difficult to set erase/record timing as well as to do tracking so as to satisfy the editing accuracy.
In the case of this embodiment, as shown in
The operation in this case is explained by referring to FIG. 5. The track information data 20 reproduced by the recording head 1 is supplied through the reproducing amplifier 29 to the reproducing system signal processing circuit 32. The reproducing system signal processing circuit 32 supplies the track information data to the timing generator 34 and the control signal 54 to the tracking controller 57. The timing generator 34 determines the erase timing of the erasing head 2 and the playback switch timing of the switching circuit 27 in response to the track information data signal. An example of the operational timing of this case is shown in FIG. 4. The erase timing setting and the tracking of this case are based on the track information data of two tracks before of the edit-object track to be erased, and the recording head 1 and the erasing head 2, as shown in
In addition, by preceding the erasing head by two tracks from the recording head, the track just after insert-recording can be prevented from being erased by the erasing head having wider head width. As shown in
Further in addition, as shown in
Next, the circuit construction in order to accommodate to the simultaneous recording and reproducing operations will be explained below.
As shown in
Besides, as shown in
On the other hand, in case that the reproducing amplifier is not carried on the cylinder, additionally to the occurrence of the crosstalk between the transformers, inter-channel crosstalk in the rotary transformer for the reproducing use will be arisen as a problem. That is, in order to down-size the cylinder body, It is necessary to suppress the height (opposite length) of the rotary transformer, leading to a reduction in distance between channels. As a result, the separation between channels in the rotary transformer becomes unsatisfactory, so that the effect of the opposite channel (Bch) can be exercised on the channel (for example, Ach) during reproducing. Accordingly, with the rotary transformer 7 for the reproducing use shown in
The short-ring is not necessary to be disposed between opposite channels because the crosstalk performance between the opposite channels when recording and erasing is not so required as in the case of the reproducing system. In this case, however, a short-ring 17 is necessary to be provided between the recording and erasing channels.
In addition, by disposing the rotary transformer 7 for the reproducing use at the upper portion of the rotary transformer 11 for the recording/erasing use, any effects by the motor or the like in the cylinder can be avoided, and the wiring to the reproducing amplifiers can be easily shortened. Referring to the cylinder assembling accuracy, by disposing the rotary transformer 7 for the reproducing use having a small number of channels at the upper portion thereof, the allowable accuracy of the mechanism can be reduced compared with the case of disposing the rotary transformer 11 for the recording/erasing use at the upper portion thereof.
Next, the reproduction compatible function to the long-time recording format will be explained below.
As already shown above,
As explained above, according to this embodiment, even with VTR of narrow-track-pitch recording by a small cylinder, the simultaneous recording and reproduction can be attained by maximizing the distance between the reproducing head and the recording/erasing heads and at the same time, by applying such a shield measure that the rotary transformer for the reproducing use is disposed independently at the upper portion of the cylinder. Furthermore, the erase/record timing setting and tracking when editing (particularly when insert-editing) are made possible by providing the optimum arrangement of the recording/erasing heads. Besides, with the reproducing function by the recording head, the reproduction compatible function to the long-time recording format recorded at a narrower track-pitch by the cylinder having the same diameter and same lead angle can be realized.
In addition, the tracking when reproducing normally is performed by reproducing the pilot signal superposed onto the recorded data.
Also, according to this embodiment, the rotary transformer was made of the periphery-to-periphery type (coaxial type), but not limited thereto, a face-to-face type (plane type) one may be used for this purpose.
In addition, according to this embodiment, the rotary transformer 7 for the reproducing use and the rotary transformer 11 for the recording/erasing use each does not have particular limitation upon the gap between the rotor and the stator, however, it is needless to say that if the gap in the rotary transformer 7 for the reproducing use is made larger than that in the rotary transformer 11 for the recording/erasing use, the allowable accuracy of the mechanism in assembling cylinder can be further reduced.
Further in addition, according to this embodiment, the short-ring 13 was inserted into the rotary transformer 7 for the reproducing use, but not limited thereto, it is needless to say that if the inter-channel crosstalk can be held without inserting the short-ring in the transformer having an equivalent or less-opposite length, the short-ring does not need to be used.
Besides, according to this embodiment, the number of recording channels was made one (1), but not limited thereto, it is needless to say that if the number of recording channels is made N (N>1), the same effect can be obtained.
Also, according to this embodiment, it is needless to say that the same effect can be obtained even with an analog recording VTR or digital recording VTR.
In addition, according to this embodiment, referring to the crosstalk to the reproducing system, the crosstalks from the recording and erasing channels were suppressed to the same level, however, if the erase frequency is set to be out of the frequency bandwidth of reproduced signal, the crosstalk allowance from the erasing channels becomes large. As a result, in the rotary transformer 11 for the recording/erasing use, the erasing channels (erase Ach 18, erase Bch 19) and the recording channels (record Ach 15, record Bch 16) can exchange their positions with each other.
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|U.S. Classification||386/237, 360/118, 360/66, 386/236, 386/289|
|International Classification||G11B5/53, G11B5/008, G11B5/024, G11B15/12, G11B15/467, H04N5/7826, H04N5/93|
|Cooperative Classification||G11B5/534, G11B5/53, G11B5/0086, G11B15/125, G11B15/4675|
|European Classification||G11B5/53D3, G11B15/12A, G11B5/53|
|Feb 16, 2007||FPAY||Fee payment|
Year of fee payment: 8
|Apr 18, 2011||REMI||Maintenance fee reminder mailed|
|Sep 11, 2011||LAPS||Lapse for failure to pay maintenance fees|