CA1316594C - Apparatus for recording and reproducing video signals - Google Patents
Apparatus for recording and reproducing video signalsInfo
- Publication number
- CA1316594C CA1316594C CA000550478A CA550478A CA1316594C CA 1316594 C CA1316594 C CA 1316594C CA 000550478 A CA000550478 A CA 000550478A CA 550478 A CA550478 A CA 550478A CA 1316594 C CA1316594 C CA 1316594C
- Authority
- CA
- Canada
- Prior art keywords
- signal
- joint portion
- segments
- video signal
- time period
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/91—Television signal processing therefor
- H04N5/93—Regeneration of the television signal or of selected parts thereof
- H04N5/937—Regeneration of the television signal or of selected parts thereof by assembling picture element blocks in an intermediate store
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/91—Television signal processing therefor
- H04N5/92—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
Abstract
APPARATUS FOR RECORDING AND REPRODUCING VIDEO SIGNALS
Abstract:
The specification discloses a recording and reproducing apparatus for dividing a video signal of one field into a plurality of segments and recording the video signal onto a plurality of tracks on a recording medium. By the recording and reproducing apparatus, an additional period is inserted between the adjoining segments. Further, the signal included in one of the adjoining segments is used as a signal of the additional period.
Abstract:
The specification discloses a recording and reproducing apparatus for dividing a video signal of one field into a plurality of segments and recording the video signal onto a plurality of tracks on a recording medium. By the recording and reproducing apparatus, an additional period is inserted between the adjoining segments. Further, the signal included in one of the adjoining segments is used as a signal of the additional period.
Description
1316~9~
APPARATUS FOR RECORDING AND REPRODUCING VIDEO SIGNALS
Field of the Invention:
The present invention relates generally to an apparatus for recording video signals on a recording medium and reproducing the signals from the record on the medium and more particularly to a recording and reproducing apparatus for dividing a video signal of one field into a plurality of "segments" and recording the video signal onto a plurality of tracks on a recording medium by use of rotary heads provided therewith.
Description of Prior Art:
As a method of recording by use of a magnetic recording and reproducing apparatus (hereunder referred to simply as a VTR) a signal of a wide band (hereunder referred to as a wide-band video signal) such as a high vision signal, (that is, a high deflnition television signal) in which the band width of the luminance signal is 20 MHz and whose band is wider than that of the existing video signal including the NTSC signal, there has been performed what is called a "segment recording" method for dividing a video signal of one field into a plurality of segments and recording the video signal onto a plurality of tracks on a recording medium.
Fig. l(a) shows one field period Tv of the foregoing ~5 wide-band video signal. In case of effecting the "segment recording" method of such a signal by the VT~ without changing its format, the heads are switched while the video signal of one field is being reproduced. However, when the 131~59~
heads are switched, a discontinuity (called skew~ of the reproduced signal on the time base occurs due to the expansion and contraction of a magnetic tape. To prevent this, there is a method whereby the skew is corrected by S switching the heads within the horizontal blanking period of the video signal. However, when considering the compatible reproduction or the like, the amount of the skew often reaches that corresponds to about a few ysec. Therefore, the skew cannot be completely corrected within the hori~ontal blanking period of the video signal which is generally set to a short period.
Therefore, the wide-band video signal is not recorded in segments without changing its format but an additional period longer than the skew amount is provided at the head switching position. A practical example is shown in Fig. l(b). Fig. l(b) shows the case of the two-segment recording in which the video signal of one field is recorded onto two tracks on a recording medium. In the wide-band video signal shown in Fig. l(a) as the original signal, a 20 vertical blanking period VB which does not appear on the TV
screen is reduced. An additional period To corresponding to only the reduced period is provided in the joint portions of respective segments Sl and S2 which are obtained by dividing one field into two sections. The heads are switched at the positions indicated by arrows AR in the portion near almost the middle position of the additional period To and in the non-signal portion of the reduced vertica7 b~anking period.
Due to this, the video information is not dropped out since ~3~6~
the period To is longer than the skew amount. On the other hand, by removing such an additional period To by the process ~not shown~ upon reproduction of the video signal, the wide-band video signal with the original format can be recovered. The additional period To is inserted in such a manner to be located in the overlap interval of each recording track.
As mentioned above, the additional period ~0 which was interposed between the segments upon recording is of the video signal removed upon reproduction of the video signal and does not appear on the TV screenO Therefore, in the Conventional VTR, a simple format such as a constant level signal or the like as shown in Fig. l(b) is used as a slgnal o each additional period To~
In the process such that what is called a "mixed signai" is transmitted to the frequency modulator (not shown) at the next stage in order to record the "mixed signal" in the above described manner after the additional period To was inserted by reducing the vertical blanking 20 period of the original signal, if a coupling capacitor is used, the DC component is lost. To obvia-te this, there is a method whereby the DC level of the "mixed signal" is aligned by performing the clamping process and thereafter -the signal is transmitted to the frequency modulator or the like.
25 However, even in the case of aligning the DC level of the "mixed signal" by the clamping in this transmitting method, it is difficult to transmit with a high fidelity the signal of the low frequency component which is represented by the ~3~59~
DC component signal under characteristics (for example, a response characteristic) of the clamping circuit. When the signal in each additional period To of the "mixed signal" is set to the DC component of the black level as shown in Fig.
5 l(b), a phenomenon called a "sag" such that the flat portion of the signal being inclined occurs in the additional period To~ Therefore, a sag also happens in the video signal of each segment just after the additional period To due to the influence of the signal in the additional period To in which 10 the sag occurs. In the video signal of each segment, the DC
component is deviated from the inherent position, such a "mixed signal" inputted to the frequency modulator and further the modulated signal is recorded by the VTR.
On the other hand, even in the case where the "mixed 15 signal" is transmitted to the frequency modulator by directly coupling without using a coupling capacitor, it is hard to transmit the DC component with a high fidelity.
Therefore, the signal portion in the additional period To which was set at the black level in the "mixed signal" is 20 set at the signal level which was deviated from the inherent black level. The format of the inherent "mixed signal"
cannot be recorded by the VTR with a high fidelity.
On the other hand, even in the reproducing process (not shown) for recovering the original wide-band video 25 signal by eliminating the additional period inserted upon recording of the original signal, the clamping process is performed. However, so long as the response characteristic or the like of the clamping circuit is not perfect, the sag ~, .
~31~9~
which occurred upon recording of the video signal cannot be completely eliminated upon reproduction of the video signal.
As described above, in the "mixed signal", the signal in the additional period (which was set in the joint portion between the respective segments obtained by dividing the video signal of one field) is set into the DC component signal such as a black level or the like. Such a "mixed signal" is used upon xecording of the video signal so that a sag easily occurs in the transmitting step of the "mixed signal". The video signal level which being different from the inherent signal level is recorded by the VTR. The sag remains and appears in the wide-band video signal which was recovered by eliminating the additional period so long as the characteristic of the clamping circuit executed upon reproduction of the video signal is not perfect. Thus, there is a problem such that this sag is displayed as a visible image on the television screen, or the like.
Further, the portion near the arrow AR in Fig. l(b) is recorded at the edge of the track which is formed on the recording of medium such as the magnetic tape. Although the contact state of the head with the recording medium, what is called a "head touch" is generally stable at the center of the track, it is likely to be unstable at the edge.
As above stated, the recording signal in the conventional VTR of the "segment recording" system is as shown in Fig. l(b). l'herefore, it is necessar~ to correct the deterioration in picture quality in the joint portion of the segments which is caused due to the defective "head 13~9~
touch" at the edge of the track upon reproduction of the video signalO AS the corrective means, it is considered to replace the portion of the deteriorated picture quality with the signal of the different scanning lines by use of a dropout corrective circuit. However, this correcting system has a problem such that it is insufficient as a countermeasure for the defective "head touch".
The present inven~ion is made to solve tha foregoing problems and it is accordingly an ob;ect of the invention to provide a recording and reproducing apparatus in which even if an additional period is provided between the segments, a sag hardly occurs in the "mixed signal".
It is anoth0r object of the invention to provide a recording and reproducing apparatus in which even when the 15 head defectively comes into contact with the storage medium at one edge of each track, the good video signal can be reproduced.
According to a recording and reproducing apparatus of the present invention, as a signal in an additional period provided in the joint portion between respective segments which are obtained by dividing one field into a plurality of segments in order to perform the "segment recording", a mixed signal is formed so as to directly and subse~uently use the signal of the last one line included in the segment 2S located immediately before the additional period (or that of the first one line included in the segment located directly after the additional period), and the occurrence of the sag in the transmitting process of the "mixed signal" upon " ,~ . ~ ~ . . ;, 13~6~fl recording o the video signal is reduced as little as possible.
In the apparatus of the present invention, since -the signal in the additional period is formed by continuing -the signal of the last one line of the preceding segment immediately before the additional period, when the mixed signal upon recording of the video signal is transmitted, a sag hardly occurs in the video signal of the segment just after the additional period.
According to a recording and reproducing apparatus of the present invention, in the apparatus for dividing the video signal of one field into a plurality of segments and recording the segments on a recording medium, an additional period is provided between the respective segments.
Further, the signals of the first P (P is a natural number) lines of the next segment are interposed and recorded onto a recording medium corresponding to the former half portion in the additional period, while the signals of the last Q (Q is a natural number) lines of the preceding segment are interposed and recorded onto the medium corresponding to the latter half portion.
When a de~ective "head touch" occurs at one edge of a track upon reproduction of the video signal, the signals of the (P ~ Q) lines interposed within the additional period are used to correct the reproduced signal in the portion where the defective "head touch" occurs.
As described above, according to the invention, in the apparatus for recording one field onto a plurality of ~316~
tracks, as the signal in the additional period provided in the joint portion between the respective segments which are obtained by dividing the video signal of one field into a plurality o~ segments, the signal of the last one line in the segment located immediately before the additional period (or of the first line in the segment located directly after the additional period) is used. Therefore, when the mixed signal is transmitted after the additional period was inserted, an increase in sag due to the insertion of the additional period does not occur. The DC component can be recorded by the VTR with a high fidelity.
Furthermore, as mentioned above, according to the invention, in the VTR for dividing the video signal of one field into a plurality of segments and recording the segments on a recording medium, an additional period is provided between the respective segments and the signals immediately before and after the additional period are interposed and recorded in the additional period.
Therefore, even if the defective "head touch" occurs a-t one edge of the track and the reproduced signal was dropped out upon reproduction of the video signal, it can be corrected by use of the reproduced signal of the portion of the additional period. ~here is an effect such that the good reproduced images can be obtained.
25 Brief Description of the Drawings:
Other objects and features of the present invention will be apparent to those skilled in the art on consideration of the following description taken in i316~9~
connection with t~e accompanying drawings wherein like par-ts in each of the several figures are designated by the same reference numeral and wherein:
Figs. l(a) and (b) are time charts for illustrating 5 the operation of a conventional apparatus;
Fig. 2 is a block diagram showing structure of a recording portion of a recording and reproducing apparatus embodying the present invention;
Figs. 3(a), (b), (e) and (d) are time eharts for illustrating the operation of the embodiment of Fig. 2;
Fig. 4(a) is a block diagram showing structure of a reeording portion of another embodiment of the present invention;
Fig. 4(b) is a block diagram showing struc-ture of a 15 reprodueing portion of the embodiment of Fig. 4(a3; and Figs. 5(a) to (e) are time eharts for illustrating the operation of the embodiment of Figs. 4(a) and (b).
Description of the Preferred Embodiments:
An embodiment of the present invention will be 20 deseribed hereinbelow with referenee to Figs. 2 and 3. In this ease, an explanation will be made with respect to the example of the rotary two-head helical scan type VTR of the two-segment recording type in which the video signal of one ield is recorded onto two tracks.
Fig. ~ is a bloc~ diagram showing structure of a reeording portion of a reeording and reproducing apparatus embodying the present invention. In the diagram, reference numeral 11 and 20 denote a mixing control eircuit and a ~ 3~6~
mixing circuit, respectively. A vertical sync signal VS of a field period Tv (not shown), a horizontal sync signal HS
of one horizontal scanning period TH, and a clock signal CLK
whose phase is locked with that of the sync signals of the original signal which were separated from the wide-band video signal as the original signal are inpu-t to the mixing control circuit 11. The mixing circuit 20 comprises an A/D
converter 21, a memory circuit 22, and a D/A converter 23.
The wide-band video signal as the original signal and the clock signal CLK are input to the A/D converter 21. Digital data 15, which is obtained by sampling and digitizing the original signal, is inputted to the memory circuit 22.
A write/read control signal Cl, which is, inputted from the mixing control circuit 11 to the memory circuit 22, is a signal to control the writing or reading operation in the memory circuit 22 with respect to the digital data 15 or the like regarding the original signal. In the case of reading from the memory circuit 22, the video signal of the last one line having one horizontal scanning period TH f the segment located directly before the additional period in the additional period which is provided in the joint portion between the respective segments which are obtained by dividing one field into two segments is subsequently repeatedly read out and is used as the signal in the additional period. It is sufficient that the additional period is set to be longer than the amount of skew which occurs. The additional period is not limited to the period which is integer times as long as one horlzontal scanning ~316~
period TH. Readout data 16 which was read out of the memory circuit 22 is input to the D/A converter 23. The digital data is converted into the analog signal, so that a "mixed signal" 17 is derived.
Figs. 3~a) and (b) respect~vely show the original signal and the mixed signal which have been described in Fig. 1. Fig. 3(a) is a diagram showing the wide-band video signal as the original signal for one field period Tv. Fig.
3(b) shows the mixed signal 17 which is output from the D/A
converter 23 and shows the additional period ~0 provided in the joint portion between the respective segments by controlling the writing or reading operation of the memory circuit 22 and reducing the vertical blanking period VB in the original signal of Fig. ;3(a). Figs. 3(c) and (d) are enlarged diagrams of the portion of the additional perlod To indicated by the portion A in Fig. 3(b). In these diagrams, the example in the case where the additional period To = 2 x TH is shown. In ths additional period To shown in Fig. 3(c), after a video signal 70 of the last one line of the preceding segment S1 is directly repeated for the period of two lines, the video signal of the next segment S2 follows. On the other hand, in the additional period To shown in Fig. 3(d), a video signal 80 of the first line of the next segment S2 is repeated for the period of two lines directly after the video signal of the last one line of the preceding segment Sl~
After the mixed signal 17 was transmitted to a frequency modulator 31 and modulated in to the FM signal, it 1~ -5 9 ~
is recorded through a recording amplifier 32 onto a magnetic tape 2 from magnetic heads la and lb attached to a rotary cylinder 3 in such a manner that the needs face each other at a distance of an angle of 180. Further, the heads are switched at the position indicated by an arrow (AR) which is almost the middle position in each additional period To in the mixed signal shown in Fig. 3(b). Further, since each additional period To is recorded in the overlap interval on each recording track on the magnetic -tape, the video signal is not dropped out. Therefore, although not shown, by eliminating each additional period upon reproduction of the video signa~, the wide-band video signal can be recovered without dropping out any video signal.
As described above, in the mixed si~nal 17 which is transmitted to the frequency modulator 31, as shown in Fig.
3(c) or (d), the signal of the last one line in the segment located immediately before the additional period (or of the first one line in the segment located directly after the additional period) is repeatedly used as the signal in the additional psriod. Therefore, in the process to transmit the mixed signal, even in the case where the mixed signal is transmitted by directly coupling without using a coupling capacitor, and in the case where after a coupling capacitor was used, the clamping process is performed to make the DC
level o~ the mixed signal constant, then the signal is transmitted, or the like a sag hardly occurs in the video signal in the segment just after the additional period of the mixed signal. The DC component can be recorded by the ~316~
VTR with a high fidelity. Therefore, in the process upon reproduction of the video signal, even if the charac-teristic such as a clamping characteristic or the like is improper so that the DC component cannot be sufficiently transmitted, a sag hardly occurs in the reproduced wide-band video signal which was recovered by eliminating the additional periods.
In the foregoing embodiment, as shown in Fig. 2, the sync signal of the wide~band video signal or original signal is what is called a negative polarity sync signal of the polarity opposite to that of the video signal. The negative polarity sync signal of the original signal is directly used even in the mixed signal which is outputted from the mixing circuit 20 in Fig. 2. However, in the mixing circuit 20, the negative polarity sync signal may bë replaced by the signal of the format suitable for recording by the VTR and the signal of the last one line of the preceding segment located directly before the additional period (or of the first one line of the segment located directly after the additional period) having the replaced neyative polarity sync signal may be also used as the signal in ths additional period.
On the other hand, as the video signal having what is called a positive polarity sync signal in which the sync signal has the same polarity as that of the video signal, 25 there is MUSE seignal or the like which has been described in detail, for example, in the monthly report (published on July, 1984) by NHK Technical Institute. When the video signal having such a positive polarity sync signal is yiven 131659~
as the original signal, an effect similar to -that in the foregoing embodiment is ob-tained even by adding the negative polarity sync signal suitable for recording by the VTR in the mixing circuit 20 and by using the signal of the last one line of the preceding segment directly before the additional period (or that of the first one line of the segment immediately after the additional period), having the negative polarity sync signal added as the signal in the additional period.
Further, even in the case where the original signal which is input to the mixing circuit 20 is the video signal having no sync signal although it has the horizontal blanking period and the video information such as luminance signal, chrominance signals and so on of the components, an effect similar to that in the foregoing embodiment can be also derived by adding the negative polarity sync signal suitable for recording by the VTR in the mixing circuit 20 and by using the signal of the last one line in the preceding segment immediately before the additional period (or that of the first one line in the segment directly after the additional period) having the negative polarity sync signal added as the signal in the additional period.
Another embodiment of the present invention will be described hereinbelow with reference to Figs. 4 and 5. In this case, an explanation will be made with respect to the example of the rotary two-head VTR of the two-segment recording type in which the video signal of one field is recorded onto two tracks.
13~G~aL~
Figs. 4(a) and 4(b) are block diagrams showing structure of a recording portion and tnat of a reproducing portion of the VTR embodying the present invention, respectively. In the diagram, reference numerals 51 and 61 denote A/D converters; 52 and 62 are memories; 53 a memory control circuit of the recording portion which circuit receives as an input signal a vertical sync signal VD in a field period T (not shown) which was separated from a wide-band video signal or original signal and a horizontal sync signal HD in a horlzontal scanning period TH; 54 and 64 D/A
converters; and 55 a fre~uency modulator. Reference numeral 66 denotes a requency demodulator; 67 is a dropout detecting circuit for receiving the reproduced signal, (that is, output of a head amplifier (not shown)) and detecting the occurrence of the dropout from its amplitude or period;
68 a sync signal processor for rscei~ing an output of a frequency demodulator 66, for separating and detecting the vertical sync signal VD and the horizontal sync signal HD, and for generating a pseudo vertical sync signal VD and pseudo horizontal sync signal HD to compensate them when the vertical and horizontal sync signals VD and HD canno-t be detected for a predeterminated period; and 63 a memory control circuit of the reproducin~ portion for receiving outputs of the dropout detecting circuit 67 and sync signal ~5 processor 68 and for outputting a signal to control the memory 62. For brevity of drawing, a clock signal is omitted in Figs. 4(a) and 4(b).
~316~
The operation of this embodiment will be described hereinbelow. The wide-band signal as the original signal shown in Fig. 5(a) is converted into the digital signal by the A/D converter 51 and written into the memory 52. In at least the operations which will be explained hereunder, the memory 52 consists of a plurality of "line memories" such that the write period and the read period do not coincide.
Fig. 5(b) shows an output of the memory 52 as a format of an analog signal. This signal is converted into the analog signal by the D/A converter 54 and frequency modulated into the FM signal by the frequency modulator 55 and thereafter, it is recorded onto a magnetic tape. On the other hand, Flg. 5~c) is an enlarged diagram of the portion A in Fig.
5(b). The numbers M, M+1 ..., etc. in the signal denote the scanning line numbers. As is obvious from Figs. 5(b) and 5(c), the additional period To in this embodiment is equal to 3TH (TH is a horizontal scanning period). The signals of the first line (The (M+l)th line) of the second segment S2 are interposed in the former half TH period in the To 20 period. The signals of the last line (the Mth line) of the first segment S1 are repeatedly interposed in the latter half 2TH period. The foregoing signals are obtained in the read contrl from the memory 52 by continuously reading with respect to the first to (M+l)th lines and then after reading 25 the Mth line twice, by again continuously reading from the (M+l)th line.
Upon reproduction of the video signal, the heads are switched at the positions shown by the arrows AR in Figs.
- 16 ~
~31~5~
(b) and 5(c). When the heads are switched, the heads are located at the edges of the magnetic tape, that is, the edges of the track. As mentioned above, the defective "head touch" occurs in the edge portion of the track and the deterioration of the reproduced signal is liable to occur.
Therefore, in this embodiment, the portion where the possibility of the occurrence of the deterioration of the reproduced signal i6 large, namely, the signals of the Mth and (M+l)th lines are reproduced twice. That is to say, the signals are reproduced at the upper and lower edges of the track by the different heads, respectively. Therefore, the reproduced signals of the last line (the Mth line) in the additional period To are used in the case where the occurrence of the deterioration of the reproduced images is predicted due t~ the outputs of the dropout detecting circuit 67 and sync signal processor 68, such as in the cases where the dropout of the signal of a predetermined width or wider occurred upon reproduction of the last line (the Mth line) of the first segment, where the horizontal sync signal is not detected, and the like. Similarly, if the deterioration of the reproduced signals of the first line, ~that is, the (M+l)th line) of the second segment is predicted, the reproduced signals of the first line, (that is, the (M~l)th line) in the additional period To which has already been written in the memory 62 are used.
Thus, the same coda is reproduced twice with regard to the signals of the Mth and (M+l)th lines so that, the other reprocuced signals are used when the defective "head ;.
131~9~
touch" occurred, thereby enabling the reproduced images without deterioration to be obtained.
On the other hand, the signals having the correlation with the signals immediately before and after the additional period are interposed in the additional period in this embodiment. Therefore, the occurrence of the sag upon DC
reproduction can be prevented. Mamely, in the conventional apparatus, the signal at a constant level having no correlation with the signals immediately before and after the additional period has been interposed in the additional period. However, according to such a conventional system, upon DC reproduction, the signals are influenced by the signal in the additional period and the sag occurs. The embodiment is also effecti~e to prevent the occurrence of the sag. Although the probability is low, when both of the signals which are reproduced twice have deteriorated, they are replaced with the signals of the different lines by the dropout correction in a manner similar to the conventional apparatus.
The foregoing embodiment has been shown with respect to the case of the two-segment recording type VTR. However, the number of segments is not limited to two. The invention oan be also applied to the VTR of the "multi-segment recording" type and to the VTR of the "multi-channel and 25 multi-segment recording" type in which the channel division recording system is also used.
The duration To of the additional period and the signal which is interposed in the additional period are not 1 3 ~
limited to those in the foregoing embodiments. When the signal period of one line upon recording of the video signal is set to TQ, To is set as follows:
To = (~ ~ Q) x T~ + ~
wh~re P and Q are natural numbers and 0 S ~ < TQ.
The similar e~fect is obtained in a manner such that the same signal as that in the first P x T~ period of the next segment in the additional period is interposed in the former half P x T~ period of the additional period To~ while the same signal as that in the last Q x TQ period of the preceding segment directly before the additional period is interposed in the latter half Q x T~ period of the additional period To~ 8ecause the signal in the period of is not used as the correction signal, the signal which is interposed upon recording of the video signal is not limited.
While the preferred embodiments have been described, it is to be understood that further modifications will be apparent to those skilled in the art without departing from the sprit of ~he invention. The scope of the invention is therefore to be determined solely by the appended claims.
- 19 - .
APPARATUS FOR RECORDING AND REPRODUCING VIDEO SIGNALS
Field of the Invention:
The present invention relates generally to an apparatus for recording video signals on a recording medium and reproducing the signals from the record on the medium and more particularly to a recording and reproducing apparatus for dividing a video signal of one field into a plurality of "segments" and recording the video signal onto a plurality of tracks on a recording medium by use of rotary heads provided therewith.
Description of Prior Art:
As a method of recording by use of a magnetic recording and reproducing apparatus (hereunder referred to simply as a VTR) a signal of a wide band (hereunder referred to as a wide-band video signal) such as a high vision signal, (that is, a high deflnition television signal) in which the band width of the luminance signal is 20 MHz and whose band is wider than that of the existing video signal including the NTSC signal, there has been performed what is called a "segment recording" method for dividing a video signal of one field into a plurality of segments and recording the video signal onto a plurality of tracks on a recording medium.
Fig. l(a) shows one field period Tv of the foregoing ~5 wide-band video signal. In case of effecting the "segment recording" method of such a signal by the VT~ without changing its format, the heads are switched while the video signal of one field is being reproduced. However, when the 131~59~
heads are switched, a discontinuity (called skew~ of the reproduced signal on the time base occurs due to the expansion and contraction of a magnetic tape. To prevent this, there is a method whereby the skew is corrected by S switching the heads within the horizontal blanking period of the video signal. However, when considering the compatible reproduction or the like, the amount of the skew often reaches that corresponds to about a few ysec. Therefore, the skew cannot be completely corrected within the hori~ontal blanking period of the video signal which is generally set to a short period.
Therefore, the wide-band video signal is not recorded in segments without changing its format but an additional period longer than the skew amount is provided at the head switching position. A practical example is shown in Fig. l(b). Fig. l(b) shows the case of the two-segment recording in which the video signal of one field is recorded onto two tracks on a recording medium. In the wide-band video signal shown in Fig. l(a) as the original signal, a 20 vertical blanking period VB which does not appear on the TV
screen is reduced. An additional period To corresponding to only the reduced period is provided in the joint portions of respective segments Sl and S2 which are obtained by dividing one field into two sections. The heads are switched at the positions indicated by arrows AR in the portion near almost the middle position of the additional period To and in the non-signal portion of the reduced vertica7 b~anking period.
Due to this, the video information is not dropped out since ~3~6~
the period To is longer than the skew amount. On the other hand, by removing such an additional period To by the process ~not shown~ upon reproduction of the video signal, the wide-band video signal with the original format can be recovered. The additional period To is inserted in such a manner to be located in the overlap interval of each recording track.
As mentioned above, the additional period ~0 which was interposed between the segments upon recording is of the video signal removed upon reproduction of the video signal and does not appear on the TV screenO Therefore, in the Conventional VTR, a simple format such as a constant level signal or the like as shown in Fig. l(b) is used as a slgnal o each additional period To~
In the process such that what is called a "mixed signai" is transmitted to the frequency modulator (not shown) at the next stage in order to record the "mixed signal" in the above described manner after the additional period To was inserted by reducing the vertical blanking 20 period of the original signal, if a coupling capacitor is used, the DC component is lost. To obvia-te this, there is a method whereby the DC level of the "mixed signal" is aligned by performing the clamping process and thereafter -the signal is transmitted to the frequency modulator or the like.
25 However, even in the case of aligning the DC level of the "mixed signal" by the clamping in this transmitting method, it is difficult to transmit with a high fidelity the signal of the low frequency component which is represented by the ~3~59~
DC component signal under characteristics (for example, a response characteristic) of the clamping circuit. When the signal in each additional period To of the "mixed signal" is set to the DC component of the black level as shown in Fig.
5 l(b), a phenomenon called a "sag" such that the flat portion of the signal being inclined occurs in the additional period To~ Therefore, a sag also happens in the video signal of each segment just after the additional period To due to the influence of the signal in the additional period To in which 10 the sag occurs. In the video signal of each segment, the DC
component is deviated from the inherent position, such a "mixed signal" inputted to the frequency modulator and further the modulated signal is recorded by the VTR.
On the other hand, even in the case where the "mixed 15 signal" is transmitted to the frequency modulator by directly coupling without using a coupling capacitor, it is hard to transmit the DC component with a high fidelity.
Therefore, the signal portion in the additional period To which was set at the black level in the "mixed signal" is 20 set at the signal level which was deviated from the inherent black level. The format of the inherent "mixed signal"
cannot be recorded by the VTR with a high fidelity.
On the other hand, even in the reproducing process (not shown) for recovering the original wide-band video 25 signal by eliminating the additional period inserted upon recording of the original signal, the clamping process is performed. However, so long as the response characteristic or the like of the clamping circuit is not perfect, the sag ~, .
~31~9~
which occurred upon recording of the video signal cannot be completely eliminated upon reproduction of the video signal.
As described above, in the "mixed signal", the signal in the additional period (which was set in the joint portion between the respective segments obtained by dividing the video signal of one field) is set into the DC component signal such as a black level or the like. Such a "mixed signal" is used upon xecording of the video signal so that a sag easily occurs in the transmitting step of the "mixed signal". The video signal level which being different from the inherent signal level is recorded by the VTR. The sag remains and appears in the wide-band video signal which was recovered by eliminating the additional period so long as the characteristic of the clamping circuit executed upon reproduction of the video signal is not perfect. Thus, there is a problem such that this sag is displayed as a visible image on the television screen, or the like.
Further, the portion near the arrow AR in Fig. l(b) is recorded at the edge of the track which is formed on the recording of medium such as the magnetic tape. Although the contact state of the head with the recording medium, what is called a "head touch" is generally stable at the center of the track, it is likely to be unstable at the edge.
As above stated, the recording signal in the conventional VTR of the "segment recording" system is as shown in Fig. l(b). l'herefore, it is necessar~ to correct the deterioration in picture quality in the joint portion of the segments which is caused due to the defective "head 13~9~
touch" at the edge of the track upon reproduction of the video signalO AS the corrective means, it is considered to replace the portion of the deteriorated picture quality with the signal of the different scanning lines by use of a dropout corrective circuit. However, this correcting system has a problem such that it is insufficient as a countermeasure for the defective "head touch".
The present inven~ion is made to solve tha foregoing problems and it is accordingly an ob;ect of the invention to provide a recording and reproducing apparatus in which even if an additional period is provided between the segments, a sag hardly occurs in the "mixed signal".
It is anoth0r object of the invention to provide a recording and reproducing apparatus in which even when the 15 head defectively comes into contact with the storage medium at one edge of each track, the good video signal can be reproduced.
According to a recording and reproducing apparatus of the present invention, as a signal in an additional period provided in the joint portion between respective segments which are obtained by dividing one field into a plurality of segments in order to perform the "segment recording", a mixed signal is formed so as to directly and subse~uently use the signal of the last one line included in the segment 2S located immediately before the additional period (or that of the first one line included in the segment located directly after the additional period), and the occurrence of the sag in the transmitting process of the "mixed signal" upon " ,~ . ~ ~ . . ;, 13~6~fl recording o the video signal is reduced as little as possible.
In the apparatus of the present invention, since -the signal in the additional period is formed by continuing -the signal of the last one line of the preceding segment immediately before the additional period, when the mixed signal upon recording of the video signal is transmitted, a sag hardly occurs in the video signal of the segment just after the additional period.
According to a recording and reproducing apparatus of the present invention, in the apparatus for dividing the video signal of one field into a plurality of segments and recording the segments on a recording medium, an additional period is provided between the respective segments.
Further, the signals of the first P (P is a natural number) lines of the next segment are interposed and recorded onto a recording medium corresponding to the former half portion in the additional period, while the signals of the last Q (Q is a natural number) lines of the preceding segment are interposed and recorded onto the medium corresponding to the latter half portion.
When a de~ective "head touch" occurs at one edge of a track upon reproduction of the video signal, the signals of the (P ~ Q) lines interposed within the additional period are used to correct the reproduced signal in the portion where the defective "head touch" occurs.
As described above, according to the invention, in the apparatus for recording one field onto a plurality of ~316~
tracks, as the signal in the additional period provided in the joint portion between the respective segments which are obtained by dividing the video signal of one field into a plurality o~ segments, the signal of the last one line in the segment located immediately before the additional period (or of the first line in the segment located directly after the additional period) is used. Therefore, when the mixed signal is transmitted after the additional period was inserted, an increase in sag due to the insertion of the additional period does not occur. The DC component can be recorded by the VTR with a high fidelity.
Furthermore, as mentioned above, according to the invention, in the VTR for dividing the video signal of one field into a plurality of segments and recording the segments on a recording medium, an additional period is provided between the respective segments and the signals immediately before and after the additional period are interposed and recorded in the additional period.
Therefore, even if the defective "head touch" occurs a-t one edge of the track and the reproduced signal was dropped out upon reproduction of the video signal, it can be corrected by use of the reproduced signal of the portion of the additional period. ~here is an effect such that the good reproduced images can be obtained.
25 Brief Description of the Drawings:
Other objects and features of the present invention will be apparent to those skilled in the art on consideration of the following description taken in i316~9~
connection with t~e accompanying drawings wherein like par-ts in each of the several figures are designated by the same reference numeral and wherein:
Figs. l(a) and (b) are time charts for illustrating 5 the operation of a conventional apparatus;
Fig. 2 is a block diagram showing structure of a recording portion of a recording and reproducing apparatus embodying the present invention;
Figs. 3(a), (b), (e) and (d) are time eharts for illustrating the operation of the embodiment of Fig. 2;
Fig. 4(a) is a block diagram showing structure of a reeording portion of another embodiment of the present invention;
Fig. 4(b) is a block diagram showing struc-ture of a 15 reprodueing portion of the embodiment of Fig. 4(a3; and Figs. 5(a) to (e) are time eharts for illustrating the operation of the embodiment of Figs. 4(a) and (b).
Description of the Preferred Embodiments:
An embodiment of the present invention will be 20 deseribed hereinbelow with referenee to Figs. 2 and 3. In this ease, an explanation will be made with respect to the example of the rotary two-head helical scan type VTR of the two-segment recording type in which the video signal of one ield is recorded onto two tracks.
Fig. ~ is a bloc~ diagram showing structure of a reeording portion of a reeording and reproducing apparatus embodying the present invention. In the diagram, reference numeral 11 and 20 denote a mixing control eircuit and a ~ 3~6~
mixing circuit, respectively. A vertical sync signal VS of a field period Tv (not shown), a horizontal sync signal HS
of one horizontal scanning period TH, and a clock signal CLK
whose phase is locked with that of the sync signals of the original signal which were separated from the wide-band video signal as the original signal are inpu-t to the mixing control circuit 11. The mixing circuit 20 comprises an A/D
converter 21, a memory circuit 22, and a D/A converter 23.
The wide-band video signal as the original signal and the clock signal CLK are input to the A/D converter 21. Digital data 15, which is obtained by sampling and digitizing the original signal, is inputted to the memory circuit 22.
A write/read control signal Cl, which is, inputted from the mixing control circuit 11 to the memory circuit 22, is a signal to control the writing or reading operation in the memory circuit 22 with respect to the digital data 15 or the like regarding the original signal. In the case of reading from the memory circuit 22, the video signal of the last one line having one horizontal scanning period TH f the segment located directly before the additional period in the additional period which is provided in the joint portion between the respective segments which are obtained by dividing one field into two segments is subsequently repeatedly read out and is used as the signal in the additional period. It is sufficient that the additional period is set to be longer than the amount of skew which occurs. The additional period is not limited to the period which is integer times as long as one horlzontal scanning ~316~
period TH. Readout data 16 which was read out of the memory circuit 22 is input to the D/A converter 23. The digital data is converted into the analog signal, so that a "mixed signal" 17 is derived.
Figs. 3~a) and (b) respect~vely show the original signal and the mixed signal which have been described in Fig. 1. Fig. 3(a) is a diagram showing the wide-band video signal as the original signal for one field period Tv. Fig.
3(b) shows the mixed signal 17 which is output from the D/A
converter 23 and shows the additional period ~0 provided in the joint portion between the respective segments by controlling the writing or reading operation of the memory circuit 22 and reducing the vertical blanking period VB in the original signal of Fig. ;3(a). Figs. 3(c) and (d) are enlarged diagrams of the portion of the additional perlod To indicated by the portion A in Fig. 3(b). In these diagrams, the example in the case where the additional period To = 2 x TH is shown. In ths additional period To shown in Fig. 3(c), after a video signal 70 of the last one line of the preceding segment S1 is directly repeated for the period of two lines, the video signal of the next segment S2 follows. On the other hand, in the additional period To shown in Fig. 3(d), a video signal 80 of the first line of the next segment S2 is repeated for the period of two lines directly after the video signal of the last one line of the preceding segment Sl~
After the mixed signal 17 was transmitted to a frequency modulator 31 and modulated in to the FM signal, it 1~ -5 9 ~
is recorded through a recording amplifier 32 onto a magnetic tape 2 from magnetic heads la and lb attached to a rotary cylinder 3 in such a manner that the needs face each other at a distance of an angle of 180. Further, the heads are switched at the position indicated by an arrow (AR) which is almost the middle position in each additional period To in the mixed signal shown in Fig. 3(b). Further, since each additional period To is recorded in the overlap interval on each recording track on the magnetic -tape, the video signal is not dropped out. Therefore, although not shown, by eliminating each additional period upon reproduction of the video signa~, the wide-band video signal can be recovered without dropping out any video signal.
As described above, in the mixed si~nal 17 which is transmitted to the frequency modulator 31, as shown in Fig.
3(c) or (d), the signal of the last one line in the segment located immediately before the additional period (or of the first one line in the segment located directly after the additional period) is repeatedly used as the signal in the additional psriod. Therefore, in the process to transmit the mixed signal, even in the case where the mixed signal is transmitted by directly coupling without using a coupling capacitor, and in the case where after a coupling capacitor was used, the clamping process is performed to make the DC
level o~ the mixed signal constant, then the signal is transmitted, or the like a sag hardly occurs in the video signal in the segment just after the additional period of the mixed signal. The DC component can be recorded by the ~316~
VTR with a high fidelity. Therefore, in the process upon reproduction of the video signal, even if the charac-teristic such as a clamping characteristic or the like is improper so that the DC component cannot be sufficiently transmitted, a sag hardly occurs in the reproduced wide-band video signal which was recovered by eliminating the additional periods.
In the foregoing embodiment, as shown in Fig. 2, the sync signal of the wide~band video signal or original signal is what is called a negative polarity sync signal of the polarity opposite to that of the video signal. The negative polarity sync signal of the original signal is directly used even in the mixed signal which is outputted from the mixing circuit 20 in Fig. 2. However, in the mixing circuit 20, the negative polarity sync signal may bë replaced by the signal of the format suitable for recording by the VTR and the signal of the last one line of the preceding segment located directly before the additional period (or of the first one line of the segment located directly after the additional period) having the replaced neyative polarity sync signal may be also used as the signal in ths additional period.
On the other hand, as the video signal having what is called a positive polarity sync signal in which the sync signal has the same polarity as that of the video signal, 25 there is MUSE seignal or the like which has been described in detail, for example, in the monthly report (published on July, 1984) by NHK Technical Institute. When the video signal having such a positive polarity sync signal is yiven 131659~
as the original signal, an effect similar to -that in the foregoing embodiment is ob-tained even by adding the negative polarity sync signal suitable for recording by the VTR in the mixing circuit 20 and by using the signal of the last one line of the preceding segment directly before the additional period (or that of the first one line of the segment immediately after the additional period), having the negative polarity sync signal added as the signal in the additional period.
Further, even in the case where the original signal which is input to the mixing circuit 20 is the video signal having no sync signal although it has the horizontal blanking period and the video information such as luminance signal, chrominance signals and so on of the components, an effect similar to that in the foregoing embodiment can be also derived by adding the negative polarity sync signal suitable for recording by the VTR in the mixing circuit 20 and by using the signal of the last one line in the preceding segment immediately before the additional period (or that of the first one line in the segment directly after the additional period) having the negative polarity sync signal added as the signal in the additional period.
Another embodiment of the present invention will be described hereinbelow with reference to Figs. 4 and 5. In this case, an explanation will be made with respect to the example of the rotary two-head VTR of the two-segment recording type in which the video signal of one field is recorded onto two tracks.
13~G~aL~
Figs. 4(a) and 4(b) are block diagrams showing structure of a recording portion and tnat of a reproducing portion of the VTR embodying the present invention, respectively. In the diagram, reference numerals 51 and 61 denote A/D converters; 52 and 62 are memories; 53 a memory control circuit of the recording portion which circuit receives as an input signal a vertical sync signal VD in a field period T (not shown) which was separated from a wide-band video signal or original signal and a horizontal sync signal HD in a horlzontal scanning period TH; 54 and 64 D/A
converters; and 55 a fre~uency modulator. Reference numeral 66 denotes a requency demodulator; 67 is a dropout detecting circuit for receiving the reproduced signal, (that is, output of a head amplifier (not shown)) and detecting the occurrence of the dropout from its amplitude or period;
68 a sync signal processor for rscei~ing an output of a frequency demodulator 66, for separating and detecting the vertical sync signal VD and the horizontal sync signal HD, and for generating a pseudo vertical sync signal VD and pseudo horizontal sync signal HD to compensate them when the vertical and horizontal sync signals VD and HD canno-t be detected for a predeterminated period; and 63 a memory control circuit of the reproducin~ portion for receiving outputs of the dropout detecting circuit 67 and sync signal ~5 processor 68 and for outputting a signal to control the memory 62. For brevity of drawing, a clock signal is omitted in Figs. 4(a) and 4(b).
~316~
The operation of this embodiment will be described hereinbelow. The wide-band signal as the original signal shown in Fig. 5(a) is converted into the digital signal by the A/D converter 51 and written into the memory 52. In at least the operations which will be explained hereunder, the memory 52 consists of a plurality of "line memories" such that the write period and the read period do not coincide.
Fig. 5(b) shows an output of the memory 52 as a format of an analog signal. This signal is converted into the analog signal by the D/A converter 54 and frequency modulated into the FM signal by the frequency modulator 55 and thereafter, it is recorded onto a magnetic tape. On the other hand, Flg. 5~c) is an enlarged diagram of the portion A in Fig.
5(b). The numbers M, M+1 ..., etc. in the signal denote the scanning line numbers. As is obvious from Figs. 5(b) and 5(c), the additional period To in this embodiment is equal to 3TH (TH is a horizontal scanning period). The signals of the first line (The (M+l)th line) of the second segment S2 are interposed in the former half TH period in the To 20 period. The signals of the last line (the Mth line) of the first segment S1 are repeatedly interposed in the latter half 2TH period. The foregoing signals are obtained in the read contrl from the memory 52 by continuously reading with respect to the first to (M+l)th lines and then after reading 25 the Mth line twice, by again continuously reading from the (M+l)th line.
Upon reproduction of the video signal, the heads are switched at the positions shown by the arrows AR in Figs.
- 16 ~
~31~5~
(b) and 5(c). When the heads are switched, the heads are located at the edges of the magnetic tape, that is, the edges of the track. As mentioned above, the defective "head touch" occurs in the edge portion of the track and the deterioration of the reproduced signal is liable to occur.
Therefore, in this embodiment, the portion where the possibility of the occurrence of the deterioration of the reproduced signal i6 large, namely, the signals of the Mth and (M+l)th lines are reproduced twice. That is to say, the signals are reproduced at the upper and lower edges of the track by the different heads, respectively. Therefore, the reproduced signals of the last line (the Mth line) in the additional period To are used in the case where the occurrence of the deterioration of the reproduced images is predicted due t~ the outputs of the dropout detecting circuit 67 and sync signal processor 68, such as in the cases where the dropout of the signal of a predetermined width or wider occurred upon reproduction of the last line (the Mth line) of the first segment, where the horizontal sync signal is not detected, and the like. Similarly, if the deterioration of the reproduced signals of the first line, ~that is, the (M+l)th line) of the second segment is predicted, the reproduced signals of the first line, (that is, the (M~l)th line) in the additional period To which has already been written in the memory 62 are used.
Thus, the same coda is reproduced twice with regard to the signals of the Mth and (M+l)th lines so that, the other reprocuced signals are used when the defective "head ;.
131~9~
touch" occurred, thereby enabling the reproduced images without deterioration to be obtained.
On the other hand, the signals having the correlation with the signals immediately before and after the additional period are interposed in the additional period in this embodiment. Therefore, the occurrence of the sag upon DC
reproduction can be prevented. Mamely, in the conventional apparatus, the signal at a constant level having no correlation with the signals immediately before and after the additional period has been interposed in the additional period. However, according to such a conventional system, upon DC reproduction, the signals are influenced by the signal in the additional period and the sag occurs. The embodiment is also effecti~e to prevent the occurrence of the sag. Although the probability is low, when both of the signals which are reproduced twice have deteriorated, they are replaced with the signals of the different lines by the dropout correction in a manner similar to the conventional apparatus.
The foregoing embodiment has been shown with respect to the case of the two-segment recording type VTR. However, the number of segments is not limited to two. The invention oan be also applied to the VTR of the "multi-segment recording" type and to the VTR of the "multi-channel and 25 multi-segment recording" type in which the channel division recording system is also used.
The duration To of the additional period and the signal which is interposed in the additional period are not 1 3 ~
limited to those in the foregoing embodiments. When the signal period of one line upon recording of the video signal is set to TQ, To is set as follows:
To = (~ ~ Q) x T~ + ~
wh~re P and Q are natural numbers and 0 S ~ < TQ.
The similar e~fect is obtained in a manner such that the same signal as that in the first P x T~ period of the next segment in the additional period is interposed in the former half P x T~ period of the additional period To~ while the same signal as that in the last Q x TQ period of the preceding segment directly before the additional period is interposed in the latter half Q x T~ period of the additional period To~ 8ecause the signal in the period of is not used as the correction signal, the signal which is interposed upon recording of the video signal is not limited.
While the preferred embodiments have been described, it is to be understood that further modifications will be apparent to those skilled in the art without departing from the sprit of ~he invention. The scope of the invention is therefore to be determined solely by the appended claims.
- 19 - .
Claims (11)
1. An apparatus for processing a video signal to be recorded on a magnetic recording medium comprising:
means for separating the video signal into a plurality of segments;
means for detecting a joint portion between adjoining segments;
means for inserting an additional time period between adjoining segments of the video signal; and means for inserting further signals into the additional time period, said further signals including signals corresponding to signals included in at least one of the segments adjoining the detected joint portion.
means for separating the video signal into a plurality of segments;
means for detecting a joint portion between adjoining segments;
means for inserting an additional time period between adjoining segments of the video signal; and means for inserting further signals into the additional time period, said further signals including signals corresponding to signals included in at least one of the segments adjoining the detected joint portion.
2. The apparatus as set forth in claim 1 wherein said means for inserting inserts a signal of at least one line included in at least one of the segments adjoining the detected joint portion.
3. The apparatus as set forth in claim 2 wherein said means for inserting inserts the signal of the last line of the segment located immediately before the detected joint portion into the additional time period.
4. The apparatus as set forth in claim 2 wherein said means for inserting inserts the signal of the first line of the segment located immediately after the detected joint portion into the additional time period.
5. The apparatus as set forth in claim 4 wherein said means for inserting additionally inserts, into the additional time period, the signal of the last line of the segment located immediately before the detected joint portion between the inserted signal of the first line of the segment located immediately after the detected joint portion and the segment located immediately after the detected joint portion.
6. A method for processing a video signal to be recorded on a magnetic recording medium comprising the steps of:
separating the video signal into a plurality of segments;
detecting a joint portion between adjoining segments;
inserting an additional time period between adjoining segments; and inserting further signals into the additional time period, said further signals including signals corresponding to signals in at least one of the segments adjoining the detected joint portion.
separating the video signal into a plurality of segments;
detecting a joint portion between adjoining segments;
inserting an additional time period between adjoining segments; and inserting further signals into the additional time period, said further signals including signals corresponding to signals in at least one of the segments adjoining the detected joint portion.
7. The method of claim 6 wherein said step of inserting includes inserting a signal of at least one line included in at least one of the segments adjoining the detected joint portion.
8. The method of claim 7 wherein said step of inserting includes inserting the signal of the last line of the segment located immediately before the detected joint portion into the additional time period.
9. The method of claim 7 wherein said step of inserting includes inserting the signal of the first line of the segment located immediately after the detected joint portion into the additional time period.
10. The method of claim 9 wherein said step of inserting additionally includes inserting, into the additional time period, the signal of the last line of the segment located immediately before the detected joint portion between the inserted signal of the first line of the segment located immediately after the detected joint portion and the segment located immediately after the detected joint portion.
11. An apparatus for processing a video signal recorded on a magnetic recording medium, said video signal being separated into a plurality of segments with a joint portion and an additional time period having been inserted in the joint portion between adjoining segments and further signals inserted in the additional time period including signals corresponding to signals included in at least one of the segments adjoining the additional time period, said apparatus comprising:
a plurality of means for respectively recovering each segment of the video signal from the magnetic recording medium, each of the means for recovering being able to recover the signal in each respective segment and additional time period joined thereto;
means for detecting a joint portion; and means for switching from one of the means for recovering to another means for recovering upon detection of the joint portion, so that said another means for recovering recovers the same signal as said one of the means for recovering.
a plurality of means for respectively recovering each segment of the video signal from the magnetic recording medium, each of the means for recovering being able to recover the signal in each respective segment and additional time period joined thereto;
means for detecting a joint portion; and means for switching from one of the means for recovering to another means for recovering upon detection of the joint portion, so that said another means for recovering recovers the same signal as said one of the means for recovering.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP257406/1986 | 1986-10-28 | ||
| JP61257406A JP2630388B2 (en) | 1986-10-28 | 1986-10-28 | Recording and playback device |
| JP27568986A JPS63129565A (en) | 1986-11-19 | 1986-11-19 | Magnetic recording and reproducing device |
| JP275689/1986 | 1986-11-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1316594C true CA1316594C (en) | 1993-04-20 |
Family
ID=26543199
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000550478A Expired - Fee Related CA1316594C (en) | 1986-10-28 | 1987-10-28 | Apparatus for recording and reproducing video signals |
Country Status (4)
| Country | Link |
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| US (1) | US5067031A (en) |
| CA (1) | CA1316594C (en) |
| DE (1) | DE3737056A1 (en) |
| NL (1) | NL192766C (en) |
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|---|---|---|---|---|
| JP2925214B2 (en) * | 1990-01-24 | 1999-07-28 | キヤノン株式会社 | Image signal recording and reproducing device |
| JPH043592A (en) * | 1990-04-20 | 1992-01-08 | Hitachi Ltd | Video signal processor unit |
| JP2995847B2 (en) * | 1990-10-23 | 1999-12-27 | ソニー株式会社 | Recording and playback device |
| US5561608A (en) * | 1992-11-18 | 1996-10-01 | Kabushiki Kaisha Toshiba | Multisystem adaptable type signal processing and recording/reproducing apparatus |
| US5510905A (en) * | 1993-09-28 | 1996-04-23 | Birk; Yitzhak | Video storage server using track-pairing |
| KR100188294B1 (en) * | 1993-10-29 | 1999-06-01 | 니시무로 타이죠 | Multi-recording media, reproducing method and the method therefor |
| US5764846A (en) * | 1993-10-29 | 1998-06-09 | Kabushiki Kaisha Toshiba | Multi-scene recording medium and apparatus for reproducing data therefrom |
| US5845046A (en) * | 1995-06-15 | 1998-12-01 | Kabushiki Kaisha Toshiba | Multi-scene recording medium and apparatus for producing data therefrom |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4224481A (en) * | 1975-03-10 | 1980-09-23 | Eli S. Jacobs | Compression and expansion circuitry for a recording and playback system |
| US4021852A (en) * | 1975-08-21 | 1977-05-03 | Rca Corporation | Signal defect compensation |
| US4489354A (en) * | 1980-11-24 | 1984-12-18 | Eastman Kodak Company | Information recording system with recording process monitoring function |
| US4563710A (en) * | 1981-02-05 | 1986-01-07 | Independent Broadcasting Authority | Digital television tape recording |
| DE3114273A1 (en) * | 1981-04-09 | 1982-11-04 | Robert Bosch Gmbh, 7000 Stuttgart | METHOD AND CIRCUIT ARRANGEMENT FOR RECORDING AND / OR PLAYING BACK DIGITAL SIGNALS |
| JPS581829A (en) * | 1981-05-06 | 1983-01-07 | Sony Corp | Video tape recorder |
| JPS5894288A (en) * | 1981-11-30 | 1983-06-04 | Sony Corp | Video signal recording device |
| DE3233389A1 (en) * | 1982-09-09 | 1984-08-02 | Telefunken Fernseh Und Rundfunk Gmbh, 3000 Hannover | Circuit for reducing head-change interferences in a recorder |
| DE3307325A1 (en) * | 1983-03-02 | 1984-09-06 | Telefunken Fernseh Und Rundfunk Gmbh, 3000 Hannover | Video recorder including the recording of a sound carrier |
| AU573235B2 (en) * | 1983-07-29 | 1988-06-02 | Sony Corporation | Multi-channel low-frequency high-definition video signal transmission system |
| DE3340113A1 (en) * | 1983-11-05 | 1985-05-15 | Robert Bosch Gmbh, 7000 Stuttgart | SYSTEM FOR STORING DIGITALLY CODED SIGNALS ON MAGNETIC TAPE |
| JPH084336B2 (en) * | 1984-06-26 | 1996-01-17 | 株式会社日立製作所 | Skew-distortion remover |
| DE3424816A1 (en) * | 1984-07-06 | 1986-01-16 | Robert Bosch Gmbh, 7000 Stuttgart | METHOD FOR STORING DIGITALLY CODED, IMAGE-SYNCHRONOUS SOUND SIGNALS |
| DE3584399D1 (en) * | 1984-07-20 | 1991-11-21 | Hitachi Ltd | METHOD AND DEVICE FOR RECORDING AND PLAYING BACK VIDEO SIGNALS. |
| JPS61148608A (en) * | 1984-12-21 | 1986-07-07 | Mitsubishi Electric Corp | Magnetic recording and reproducing device |
| US4752840A (en) * | 1985-06-25 | 1988-06-21 | Sharp Kabushiki Kaisha | Multitrack magnetic recording and reproducing device |
| US4686582A (en) * | 1986-01-06 | 1987-08-11 | Eastman Kodak Company | Head switching in high resolution video reproduction apparatus |
| US4752839A (en) * | 1986-01-06 | 1988-06-21 | Eastman Kodak Company | Head switching in high resolution video reproduction apparatus |
| US4739419A (en) * | 1986-01-06 | 1988-04-19 | Eastman Kodak Company | Apparatus for eliminating midfield skew error by delaying the lower half field of a T M format video signal to be recorded on the second of two tracks |
| NL8600254A (en) * | 1986-02-03 | 1987-09-01 | Philips Nv | METHOD FOR WRITING AND / OR READING A VIDEO SIGNAL, FOR EXAMPLE, A MAC SIGNAL, APPARATUS FOR CARRYING OUT THE METHOD AND OBTAINING A MAGNETIC RECORD CARRIER ACCORDING TO THE METHOD. |
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1987
- 1987-10-28 NL NL8702557A patent/NL192766C/en not_active IP Right Cessation
- 1987-10-28 CA CA000550478A patent/CA1316594C/en not_active Expired - Fee Related
- 1987-10-28 DE DE19873737056 patent/DE3737056A1/en active Granted
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1990
- 1990-03-06 US US07/489,877 patent/US5067031A/en not_active Expired - Fee Related
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| NL8702557A (en) | 1988-05-16 |
| DE3737056A1 (en) | 1988-05-11 |
| NL192766C (en) | 1998-01-06 |
| NL192766B (en) | 1997-09-01 |
| DE3737056C2 (en) | 1990-04-26 |
| US5067031A (en) | 1991-11-19 |
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