JPS59116913A - Apparatus for recording video signal on moving tape - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

BACKGROUND OF THE INVENTION This invention relates to the recording of digital television signals, and to a video tape recorder (hereinafter referred to as a VTR) that can be used with multiple television standards.

Patent Application No. 17401 dated February 4, 1981 discloses a tape format and scanning method for a digital VTR having a head wheel with three heads spaced at 120° intervals and a tape winding angle of 24o0. ing.

In such a head configuration, two heads are always in contact with the tape required for a two-channel record. The above application also discloses a segmented tape format in which six portions of a television image are recorded in separate scans in such a manner that recording one field requires two rotations of the headwheel. Another aspect of this format is that three heads record the top, middle, and bottom A of the television image, respectively.
This provides a technique for reciprocating image display in which the data is then played back (the image is visible even when the VTR is in fast forward or fast reverse mode).

For recording and reproducing digital video signals in the standard form of 625 lines 50H2 (PAL-, SECAM) or 525 lines 60Hz (NTSC), it is desirable to use the same tape feed section of the VTR. The image shows head rotation (ratio of 30150 (field ratio)
Therefore, when the sampling rate is constant, the bit recording density along the trunk is 16.7% higher for the 625 tree line than for the 525 tree line. It is desirable that the bit densities be equivalent or similar between the two standards, since higher bit densities require narrower magnetic head gaps and respect for magnetic tape grains. It is also desirable to use the same magnetic head and magnetic tape for both 625-tree and 525-tree television receivers. Furthermore, in order to increase the commonality of the reciprocating image display circuit for both standards, it is desirable to use the same division (number of divisions per field) for both standards. However, in the case of a split-type recorder with a two-channel electronic circuit, three heads, and a tape winding angle of 240°, in order to optimize the VTR format and the design of the feed section, it is necessary to The optimal recorder for 625 line images is (
20% faster rotation (due to field frequency differences) and smaller diameter (to maintain constant recording density along the trunk)
It is necessary to use a head wheel. This difference in head wheel diameter does not satisfy the condition of using the same feed section for both standards.

Therefore, it is desirable to have a VTR that operates with two different standards, yet has the same recording density along the trunk, the same partitioning method, and the same headwheel diameter in the two standards.

According to the present invention, in order to record any one video signal of a plurality of standards, a moving tape is placed along an arcuate path, and while the tape traces the arcuate path, a selected video signal is recorded. The signal is recorded in selected scans on tape according to established standards.

[Embodiments of the invention]

FIG. 1 shows a block diagram of one embodiment of the recording method according to the invention. CCIR, an international digital standard, requires 8 pins sampling the analog luminance component at 13°5 MHz (256 gray levels) and 8 pins sampling each of the a analog color components at 6.75 MHz. The luminance component is sampled twice as often as each color component, so the combined signal is 13.5M
It can be processed as one 16-bint signal sampled at Hz.

A digital video signal according to the CCIR international standard is applied in parallel to the 16-bit input terminal 10 at the far left in FIG.

If still only a composite analog signal such as NTSC, PAL or SECAM is provided, it is received at input terminal 16 and applied to analog-to-digital converter 18.

This analog signal is generated by the master clock 20 at 13.
It is converted to 9 -bit digital signals with a 5MHz sampling frequency (excess L bit is for handling increased dynamic range of its synthetic signal), and it is also applied to the component decinating device 22, and here is Y, according to the above standard.
The RY and B-Y components are supplied to the 16-bit input 24 of the switch 14.

Switch 14 applies the digital signal at input IO to the input of 16-bit buffer 26, whichever is available as the digitized signal from decoder 22.

These signals are introduced using a clock frequency of 13.5 MHz. In order to save tape space and increase recording density, the horizontal blanking period is not recorded (instead of the horizontal period, a unique code with a short duration, such as a cursor, is recorded), so this buffer is used. The reading Xy and the frequency fn are 12.0 MHz as shown below. That is, the above international standard has 525 tree lines and 61 tree lines per I frame.
25 For both expressions of the tree line, 2 for the effective part of the line.
Specify 0 digital.

Also, if 48 samples are sufficient for the above code word for horizontal synchronization, error control, parity checking, and other recorder control signals, then the recorded horizontal line will contain '768 samples in both 525 and 625 tree formats. will be included. Reading frequency fR = '768fh
Here, fh is the horizontal frequency, which is 15.734266KHz for the 525 tree method and 15.625KHz for the 625 tree method. Therefore, fR is 5
l for the 25-line system and the 625-tree system, respectively.2.
084+1ll (z and 12MHz, that is, real 1
The same is true for festivals.

The sample read from the buffer 26 is then applied alternately to two different channels.

is applied to the arrangement 28. Therefore, the distributor 2B has 16P of electrons.
Consists of DT switch. According to the principle of the present invention, two channels are used because two heads record at the same time in order to increase the amount of data compared to when only one head is used for recording at the same time. If one channel fails, the other channel will provide at least a low-resolution signal.

On the 2nd day of the distributor, the clock frequency is 20 to 6.0MHz (fR/
2) Accept the signal as a channel switching signal.

The channel electronics 30.32 adds a unique and therefore easily detectable digital code word to replace the horizontal synchronization signal lost in reading the buffer 26, error correction code and parity check bits, all known to those skilled in the art. do.

This channel electronic circuit device 30. , the output of 32 is 3
16-bit switches 34A, 34B%
34G is applied to a distributor 33 containing 34G.

This switch 34 alternately applies the signals of channels 1 and 2 to the 16 bits (16 bits) 36.3B and 40 in accordance with the control signal from the gate timer 42. Each gate 36.
The timing of connecting each channel J12 to 3B and 40 is shown in FIGS. 2 and 3 for the 625 tree and 525 tree systems, respectively, depending on the gate signal applied to each gate. It can be seen that in the 625 tree system, gate 36 provides the channel 1 signal during at least the first 120 degrees of rotation. Only gate 40 is narrowly open during this period, and this gate would provide the channel 2 signal. During the 120-240° period, gate 36 continues to supply the signal to the channel, and gate 3 begins supplying the channel 2 signal. Switch 34A,X
φ4B operates at 360° and 7200°, respectively, while switch 34G operates at 120° and 480°. The same applies to the remaining period and the 525 tree line method in FIG. Next, the switching waveform of the switch 34 will be explained with reference to FIG.

The output signals of the distributor 33 are applied to gates 36, 38, 40, respectively, which are controlled by a gate timer 42.

The timer 42 determines whether the signal to be recorded is 525 tree line method or 625
Two equal degrees 5.5. Accept one of the period signals. This 2fv signal is also applied to a conventional head wheel motor servo circuit 46 so that one revolution of the head wheel 48 corresponds in time to a dedicated field according to the selected standard. From Figure 2, 625
In the operation of the main line system, each gate 36.3B, 40 is opened for 240 degrees (scan angle) of the head wheel to pass the signal. It can be seen that only a scan angle of 00 is opened.

Therefore, by reducing the scanning angle, the 525 tree system successfully reduces the diameter of the head wheel compared to the 625 tree system, and since the 525 tree system has a higher vertical frequency, the rotation speed can be reduced. I'm raising it.

The output signals of gates 36, 38, 4o are respectively 16; 1
Multiplex+! ll-200, 202, 204, and the output of this multiplexer (approximately 96 MH
z) is applied to the recording heads A and BXC, which are attached to the head wheel 4 and rotate together with it.

The head wheel 48 is typically disposed inside the drum 56 and covers the magnetic recording tape 5 over a 240° circumference of the drum.
8 is wound by rollers 60, '62.

The tape 58 is moved by a servo-driven motor and capstan (not shown) from a supply reel (not shown) around a roller 62 (reference 00 point) and around the drum 56 and then from the drum 56 to the roller 60 position. It separates and proceeds to a take-up series (not shown). In this manner, the tape 58 is spirally scanned. That is, in the 625 tree line system, each head records on the entire tape wound at 240 degrees from the rollers 62 to 60, but in the 525 tree line system, it records only between 2000 degrees from the roller 62 to the position indicated by the arrow 64.

In Figure 4 a, b, tape area numbers are attached to each LJC.
The tape format and head activation timing for the 625-line system are shown, and FIGS. 5a and 5b each show similar information for the 525-line system. In either method, there are six recording areas (five complete and one half) in the L field period, and these areas have numbers as shown in the figure, and three navel FAs to record them, B, , and C are attached. l
Since the number of fields is an integer, every point of the original raster is always recorded equidistant from the side edge of tape 5B.

Therefore, during playback this point appears at the same point that appears in the rask of the signal recorded on the rask, regardless of the playback speed. Therefore, it is possible to display images back and forth without storing fields for timing adjustment at that point. still!
In the frame 625 tree scheme, 240 per false field
0 and each head corresponds to 240 degrees, so 312.5 per area (wood/field) divided by 3 (field/one rotation of the henodic wheel or 1 area) or 1
There will be oa-+76 lines. ■Frame 52
In the five-tree system, since each field corresponds to 2000 and each head corresponds to 200', 1p per region is 262,
5. (Book/Field) Divide S (Field/1 area)
That is, there are 8'7.5 lines. 625 tree line method and 5
The ratio of in-track recording densities in the 25-tree tree method is as follows, that is, they are practically the same.

The 525 tree format has a recording gap, indicated by X in FIG. . Control signal trunks 68 for audio track 66 and tape drive servo (not shown) control are present in both formats.

FIG. 6 shows a circuit for generating various signals within the master clock 20 of FIG. A stable 13.5 MHz oscillator 70 feeds its output signal to a frequency divider 72, which programmable frequency divider 72 determines whether the 625 tree signal is recorded or not.
Switch ' depending on whether a 25-tree signal is recorded.
864 selected at 74 is divided at 858, respectively.

Switch 74 is typically associated with switch 44 of FIG. The output signal of frequency divider 72 has a horizontal frequency fH for a particular signal and is applied to one input of frequency comparator 76. Voltage controlled oscillator (VCO) '78 is 12.0M
Only Hz i has a frequency of 12,084 MHz, which is divided by 2 by the divider 71 and supplied to the divider 28 as a switching signal. Frequency divider 80 divides the frequency of VCO'i'8 by 768, so the frequency of its output signal will be fH if fR is correct. This signal is transmitted to comparator 76
is applied to the other input of The error signal e output from the comparator '76 is amplified by a factor of G by an amplifier 82 and applied to the VCO '7B for frequency control so that its output frequency becomes exactly fR. The output signal of the frequency divider 72 is applied to the phase-locked loop (PLL) "I" 7 and '79 through the 625 frequency divider 73 and the 525 frequency divider 75, respectively, and is applied to the switch 44 for PAL mode and NTSC mode. 2fv vertical synchronization signal is supplied.

FIG. 7 is a block diagram of the gate timer shown in FIG. 1 using the 625 tree line system, and FIG. 8 is its timing diagram. Ru.

FIG. 8g shows the 2fv input signal from the switch 44
As shown for the head wheel rotation angle on the bottom side of the figure, this signal is applied to the center power S and reset power R of the flip 70 knob '700 and to the inputs of the delay line '702. Flip-flop 700 generates signals A and B shown in FIGS. 8-c at its Q output and output, respectively, which are applied to switches 34A and aB, respectively. Signal A is also applied to AND gates 'i', 04, 'i'06, and signal B is also applied to AND gates 'i', 04, 'i'+4. Delay line 702 is 120° of head wheel rotation.
Since the length of the field (720°) is approximately 20 milliseconds (in the case of the 625 tree line method), the delay time is approximately 3.33 milliseconds. 2 which is the delayed 2fv signal from this delay line 702
fvn 1 is as shown in FIG.
3mi! It is applied to the input of a delay line 710 with a delay of J seconds. The Q output signal of flip-flop '708 is shown in Figure 8e.
With signal C shown in , switch 34C and AND gate '70
4,'7J6, and the 100 output signal is the signal shown in the lower part of FIG. The output signal of this flip-flop 720 )Q is applied to the flip-flop +720.
The signal E shown in the figure is applied to gates 716 and '714. The CIB force signal of flip-flop 720 is signal F of FIG. 8 and is applied to gate 718.706.

The output signals A and C of the gate 704 and the output signals B and D of the gate 12 are applied to the gate 722. It is shown with a symbol indicating whether it is formed. The output signal of this gate 722 is applied to gate 38, so that FIG. 8j corresponds to FIG.

The output signals C and E of gates 716 and 718, and F, are applied to the OR gate 724. The output signal of this gate 724 is shown in FIG. 8k corresponding to FIG. 2c and is applied to gate 40. The output signals B, E, A, and F of iH and 706 are applied to the 725, and the output signal of the 726 is applied to the second
A signal corresponding to FIG. a is applied to the gate 36.

In the NTSC system, a circuit similar to that shown in FIG. 7 can be used, but the delay time needs to be changed, and each AND gate still has soo, 200' as shown in FIG.

. . . requires a delay time that provides a waveform with edges.

FIG. 9 is a block diagram of an apparatus for reproducing tapes having the formats shown in FIG. 4 and FIG. 5. 1st
As in the recorder shown, the tape 58 is moved to the roller 601.
62 is wound around the drum 56. The head wheel 48 has heads A, BX C around it and is driven by an electric motor (not shown) under the control of a servo system 46. The servo system 46 receives from the master clock 20 the 2fv signal selected by the switch 44 depending on whether the signal on the tape 58 is being reproduced in the 625-tree system or the 525-tree system.

The signals reproduced from the belly buttons FA, B, and C are applied to amplifiers +00A, X100B, and X100C, respectively, and the amplified signals are applied to data detectors 102A and 10, respectively.
2B.

102C is applied. The data detector 102 can be made into a simple threshold circuit using non-return-to-zero (NRZ) recording, but when using non-return-to-zero-interleaved (NRZ-I) recording, it can be made into a simple threshold circuit. Patent Application No. 111 '798 filed on June 21, 1958
The one disclosed in No. 1 is preferred.

The output of data detector 102 is applied to I:167''' multiplexer JOA') 210B) 210G, and each output of demultiplexer 210 is applied to ]6PD'
1' switches 134A, 134B, and 134G.

The timing of the switch 134 is shown in FIG.
4A, 134B) Parts necessary for controlling 1340,
For example, it is controlled by a timer 142 that includes a flip-flop 700, 'i'08, and a delay line '702.

The switch 134 has samples for each of the three signal channels alternately, and the channel electronics 130
．． 132 into two channels. Here, the unique codeword is decoded to obtain the horizontal synchronization signal, and errors are detected and corrected. The outputs of circuits I30 and I32 are applied to a sample splitter 128 where the alternating samples are combined into one 16-bit wide signal.
applied to buffer 126. Buffer +26 is frequency fR
and fw signals to restore proper timing for each horizontal line. Switch +14 is 16 bits wide and should be in the position shown in Figure 9 when a digital output signal is required.
A digital video signal is supplied to 10.

However, when you need an analog output signal, switch +1
4 is in the opposite position to Figure 9, and the digital analog (D
A, > converter 190.192.194 respectively Y,,
Supplies R-YXB-Y digital signals.

DA converter 190. The l'92.194 analog output signal is applied to a composite encoder 196 and the resulting composite analog signal appears at output terminal 116.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a recording system according to an embodiment of the present invention, and FIGS. 2 and 3 are a 625-line system and a 5-line system, respectively.
Figures 4 and 5 are diagrams showing the gate timer numbers generated in the embodiment of FIG. 1 in the operation of the 625 tree system and 525 tree system, respectively. Figure 6 is a diagram showing the master clock in Figure 1, Figure ÷ is a block diagram of the gate timer used in Figure 1, Figure 8 is shown in Figure 7. A signal waveform diagram, FIG. 9, is a diagram showing a reproducing apparatus according to the present invention. 36.3B, 40, 42...scanning angle selection device, 58.
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Claims (1)

[Claims] (1) To record video signals of different standards, the video signal is recorded on a moving tape that describes an arcuate path, and includes a device that selects the scanning angle at which the recording is performed according to the standard of the signal being recorded. device to do.