JPS6120948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an address recording and reproducing method for a strip-shaped recording medium such as a magnetic tape used in a magnetic recording and reproducing apparatus (hereinafter abbreviated as VTR), and particularly relates to a dubbing operation between VTRs. The present invention aims to provide an address recording/playback method suitable for tape positioning in an automatic SLE (spliceless editor) editing device.

The tape positioning methods used in such SLE automatic editing devices include the pulse count timer (PCT) method that counts some pulses, and the method that records an address code on the tape and reads it out (hereinafter referred to as the address method). It has been put into practical use. Although the pulse count timer method is a simple device, it has many problems, such as being prone to miscounts (especially at startup, for example, about 4 to 5 seconds from startup). On the other hand, for accurate tape positioning, a method using a tape address code has been used.

Regarding this tape address code method,
Various systems are shown in "Broadcasting Technology" (October 1977 issue), but one of them, the SMPTE system, requires complicated equipment and requires improvements to the VTR queue track. 4 heads of
There was a problem in that it was not easy to incorporate an editing device into a VTR, and the DATATRON method also had the disadvantage that modulation and demodulation were complicated because the time code was a pulse-width modulated wave that was amplitude-modulated at a higher frequency.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to overcome the above-mentioned problems and drawbacks and to provide an address method for easily and accurately obtaining tape position and time information by combining the pulse count timer (PCT) method with the accuracy of the addressing method. An object of the present invention is to provide an information signal recording and reproducing method.

That is, in the present invention, if time information is added to a plurality of specific pulses of a pulse train having a constant period and recorded on a magnetic tape together with the pulse train,
This method was developed based on the fact that it is possible to form an address information signal that can be used in both the pulse count timer method and the address method. During recording, time information is obtained by counting a control pulse train having a constant period from the time when the recording tape is started. After a certain period of time has elapsed during which the recording tape is in a stable running state after startup, the time information is used to count the control pulse train in the control pulse train. A specific pulse is pulse width modulated, and the pulse width modulated output is stored as an address information signal together with a control pulse train on a cue track on the recording tape and also supplied to a pulse count timer. During playback, the address information signal reproduced from the cue track is , obtain time information and a control pulse train of a constant period, and after a certain period of time has elapsed for the recording tape to be in a stable running state after starting the recording tape, correct the count value of the pulse count timer with the reproduced time information, and then The present invention is characterized in that by counting the reproduced control pulse train, the tape time is displayed based on the count value of the pulse count timer.

Hereinafter, details of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the circuit configuration when recording an address information signal, FIG. 2 is a block diagram showing the circuit configuration when reproducing the address information signal, and FIGS. 3A to 3C are the address information signal recording and reproducing system according to the present invention. FIG. 2 is a signal waveform diagram showing an example of an address information signal used in FIG.

First, time code generation and tape recording of time information will be explained. In FIG. 1, a signal from a crystal oscillator 1 is frequency-divided by n by an n frequency divider 2 to extract an accurate 300 Hz pulse train (see FIG. 3A). This pulse train is supplied to the microcomputer 3. The microcomputer 3 uses this pulse train as a synchronization signal and synchronizes with it to set the time information address code to a binary level "1".
and “0”. To elaborate further,
In the microcomputer 3, for example, a timing program is started by an external start trigger at the same time as the VTR is started, and the above-mentioned 300Hz pulse train is counted as a clock pulse.
Create a clock inside the computer and record the necessary time data in the computer's internal registers. Here, a case will be described in which the address code is a time information time code in the form of a time display. Therefore, in microcomputer 3,
Desired time data is sequentially read out from the internal register using the above-mentioned 300Hz pulse as a synchronization signal, and the time information time code, for example, the minute time data "61 minutes" and the second time data "18 minutes" shown in FIG.
In the illustrated example, add "0" as a star bit to the immediately preceding bit of each minute and second time data, and then add "61 minutes" to the minute time data.
Read out the codes indicating this sequentially from the internal register and input “1” trigger input TG ₁ and “0” trigger input.
The signal is separated into TG ₀ and supplied to the code generation circuit 4, respectively. Note that "1" is added as a stop bit immediately after each time data code.

Code generation circuit 4 generates a pulse with a duty ratio of 75% when trigger input TG ₁ is applied.
When trigger input TG ₀ is applied, duty ratio is 25
% pulse is generated. These pulses are generated at a period of 1/300 seconds as shown in FIG. 3C, and the rise of each pulse is assumed to be synchronized with the rise of the 300 Hz pulse described above. Incidentally, such pulses having different duty ratios can also be generated by the microcomputer 3 itself by appropriately programming the microcomputer 3.

In the example of the time code pulse train for time information shown in FIG. After a certain period of time after starting the engine, the running condition became stable. Insert time information (address code) at one location, for example, 1 second, 2 seconds, etc. remaining 280
It is assumed that the pulse stores data "1" as long as it is not necessary.

Note that the superposition of the address code is not limited to the combination of signals with different data ratios, and can be performed by any desired method, such as by changing the pulse amplitude.

Furthermore, in FIG. 1, a pulse train containing a time code (address code) of time information synchronized with 300 Hz generated as described above from the code generation circuit 4, that is, an address information signal, is generated after a certain period of time after starting the VTR. More specifically, at a point in time between 1 and 5 seconds from startup when the VTR is in a stable running state, it passes through the buffer 5 and is recorded as a cue track address signal of the VTR 6. Address information signal is pulse count timer (PCT) 7
The signal is also supplied to the address information signal, and by counting the number of pulses in the address information signal, the relative position information of the tape of the VTR 6 is obtained.

In this way, since the time information to be superimposed only takes 1, 2, or 3 seconds, the required number of bits is also very small, such as 3 or 4 bits.

Furthermore, in order to match the display of the PCT7's count value with the time code (absolute position information) of the time information recorded in the cue track, the magnetic From the microcomputer 3 at the same point in time when recording time information to the tape.
PCT display regulation data is supplied to the PCT 7 to regulate the display, count pulse trains of a constant period, and display the recording time in a form that can be detected by human systems.

In addition, the frequency division ratio in PCT7 is 10 frequency division for 300Hz, 10 frequency division and 3 frequency division, 10 frequency division, 6 frequency division, 10 frequency division
By dividing the frequency and dividing the frequency by 10, from each division stage
Can take out time display output in 30PH pulse, frame, seconds, 10 seconds, minutes and 10 minutes.

Next, I will talk about the operation during playback.

In FIG. 2, the address information signal reproduced from the cue track of the VTR 6 is passed through a waveform shaping circuit 8 such as a Schmitt circuit to obtain a reproduced address information signal whose waveform is restored to the waveform at the time of recording. This reproduction address information signal is supplied to the signal processing circuit 9, and data D consisting of time "1" and "0" is generated.
Form a 300Hz trigger signal TG. These time information data D and trigger signal TG are supplied to the microcomputer 3.

(1) When the VTR is in the PLAY state The PCT 7 counts the address information signal obtained from the waveform shaping circuit 8 as a simple pulse of 300 PPS (pulses/second). Here, while the VTR 6 is stabilizing to normal rotation, the PCT 7 is likely to cause miscounts, but when the VTR 6 is in a stable running state, that is, when time information is recorded on the key track during recording, the trigger is activated. Time information data D at the timing of signal TG
The address code inside is sent to microcomputer 3.
This is decoded by the PCT 7 and transferred as display regulation data to correct the miscounted value of the PCT 7 and regulate the display. As mentioned above, the rising points of each pulse in the address information signal are kept at exactly 1/300 second intervals, so once you have calibrated it, you can accurately display the time simply by counting the number of pulses in the address signal. and the tape position match, and the position of the VTR tape is determined and control to the VTR (such as generation of SLE control) is performed based on the count value of PCT7. Furthermore, once the microcomputer 3
Once the data in the PCT 7 is regulated, the microcomputer 3 becomes unnecessary and can be assigned to other tasks. In this case, the address information signal is “1” for bits other than the address code.
Therefore, the start bit "0" is detected, and demodulation is performed from the next pulse according to a predetermined number of bits (in this example, 4 bits each) as the address code. In this example, 4 bits are used as the address code to display time in seconds, and a start bit ``0'' and a stop bit ``1'' are added before and after each bit. When eight or more "1"s are detected, it is assumed that there is no address code, and the address code demodulation is reset and a standby state is entered.

(2) When the VTR is in fast forward/rewind mode Address code demodulation is difficult due to the high speed, but PCT7 counts the pulses in the address information signal reproduced from the cue track of VTR6 and By adding the counting results to the display and updating the display, the approximate tape position can be displayed.

As is clear from the fact that the address code according to the present invention is periodically superimposed on the pulses from the crystal oscillator as described above, it is inserted independently from the frame of the television signal, and therefore Since the time interval at which the address code is recorded on the tape always matches real time, frame error correction is not necessary. Furthermore, when switching the screen, if you specify the switching time and give a trigger to the video switching circuit of the VTR body, as was conventionally done, the frame signal is detected inside the VTR, and this video switching circuit inside the VTR body is detected. is activated and the video is switched during the vertical blanking period. Therefore, even if the address code is inserted independently of the frame of the television signal and the frame error is not corrected, there will be no adverse effects such as image disturbances caused by switching the image in the middle of the screen. Of course.

As is clear from the above, according to the present invention, the following effects can be obtained.

(1) Address codes can be generated more easily than conventional methods, and address codes can be read easily.

(2) Since the pulse of the address code 300PPS is used as the input for the pulse count timer (PCT), the PCT display will be accurate from now on by decoding the address code once when the running condition becomes stable after startup. Tape position can be displayed.

(3) High accuracy as it only counts frequencies 10 times the frame frequency of approximately 30Hz. 300Hz (4) Since the oscillation power from the crystal oscillator can be divided and used, it is highly accurate and can match real time.

(5) When combined with a VTR, fewer modifications are required to the VTR.

(6) Tape position can be expressed even during fast forwarding.

(7) Since time information of 1 second, 2 seconds, or 3 seconds is only recorded, the required number of bits is only about 4 bits, and the remaining bits can be used for other purposes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a circuit configuration when recording an address information signal according to the present invention, FIG. 2 is a block diagram showing a circuit configuration when reproducing an address information signal according to the present invention, and FIGS. FIG. 3 is an explanatory signal waveform diagram of an address information signal in the invention address information signal recording/reproducing method. 1...Crystal oscillator, 2...N frequency divider, 3...Microcomputer, 4...Code generation circuit, 5
...Batsuhua, 6...VTR, 7...PCT, 8...
... Waveform shaping circuit, 9... Signal processing circuit.

Claims (1)

[Claims] 1. In a method of recording and reproducing address information signals on a recording tape using a pulse count timer, during recording, time information is obtained by counting a control pulse train having a constant period from the time when the recording tape is started. , After a certain period of time has elapsed during which the recording tape is in a stable running state after the activation, a specific pulse in the control pulse train is pulse width modulated based on the time information, and the pulse width modulated output is used together with the control pulse train as an address information signal. is stored in the cue track on the recording tape and also supplied to the pulse count timer, and at the time of playback, obtains time information and a control pulse train of a constant period from the address information signal reproduced from the cue track, and after starting the recording tape. After a certain period of time has elapsed during which the recording tape is in a stable running state, the count value of the pulse count timer is corrected using the reproduced time information, and after that, the pulse count is calculated by counting the reproduced control pulse train. A method for recording and reproducing an address information signal for a recording tape, characterized in that the tape time is displayed by the count value of a count timer.