JPS5841452A - Recording speed discriminating system for recording medium - Google Patents

Abstract

PURPOSE:To easily obtain a suitable reproducing speed in response to the request of reproducing speed at reproduction, by automatically discriminating the speed at recording for a VTR or the like, through the provision of two specific frequency-dividers, a counter and a comparison means. CONSTITUTION:A reference clock 2<n> times the control pulse frequency of a recording medium is frequency-divided at a frequency divider 14, for one time at normal/double speed/tripple reproducing speed, for 1/2 time at 1/2 time reproducing speed and for 1/3 time at 1/3 time speed reproduction, and a reproducing control pulse is frequency-divided at the 2nd frequency-divider 13, for one time at normal 1/2 speed 1/3 speed reproduction, for 1/2 time at double speed reproduction, and for 1/3 time at tripple speed reproduction. The period of pulse of an output of the frequency-divider 13 is counted 22 by taking an output of the frequency-divider 14 as a clock input, and the count value B and two constants A, C are compared 23 and 24, and whether or not the moving speed of the recording medium is suitable is discriminated from the result of comparison.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining the recording speed of a recording medium such as a video recorder (hereinafter referred to as VTR) for determining the speed during tape recording.

In general, VTRs use a helical scan method for recording and reproducing using a rotary head, and the magnetic tape used for this is also of the cassette type.

■ With the development of recording and playback technology, these 11 VTRs can record for one hour (hereinafter referred to as IH mode), two-hour recording (hereinafter referred to as 2H mode), even on magnetic tapes of the same length.
mode) and 3-hour recording (hereinafter referred to as 3H mode), you can set your favorite recording time by selecting the mode.

■ On the other hand, in terms of playback operation, there are four rich functions: 1x speed (normal) playback, 2x speed playback, 3x speed playback, l/
It is also possible to play at 2x speed, 1l/3x speed, and still playback at 3x speed.

■ Therefore, when playing back a tape in IH mode, if you want to achieve double or triple speed playback, set an appropriate double playback speed for the tape speed at the time of recording, and play the tape in 2H mode. To do so, you must set an appropriate double-speed playback tape speed for the recording tape speed.

In a VTR such as the one described above, if the tape speed during playback is manually set by switching, the operation becomes extremely complicated. Also, if you only look at the magnetic tape,
Since it is not possible to determine from the outside what mode the tape is being recorded in, it takes time and effort to write it on the label of the Rikiryutto before recording.

The present invention was made in order to deal with devices that can write at various speeds during recording and reproduce at various playback speeds during playback, as described above. An object of the present invention is to provide a method for determining the recording level of a recording medium that is effective for automatically determining the speed of a recording medium and obtaining an appropriate playback speed in accordance with a playback speed request during playback.

Embodiments of the present invention will be explained below with reference to the drawings.

In this invention, Table 1 summarizes the frequencies of the capstan synchronization detection pulses when playing at IF, IH mode, 2H mode, 1x 1 normal, 2x, and 3x speed. As shown in , the capstan rotation detection ΔRus wave number (hereinafter referred to as 70 frequency for rounding) when a nine tape recorded in IH mode is normally played back is 7.
The frequency is 20 Hz. Considering this as a standard, 2
When the speed is double, the tape speed is double, so the capstan rotation speed is also double.J), 720 us
2 ” 1440: HI OF 0 frequency. Similarly, Table 1 shows the 0th frequency division ratio of 4, which is a summary of 70 frequencies when playing each card tape at various double speeds. However, this is the ninth step in converting the #rotation detection Δlus to an easy-to-handle frequency when introducing it into the digital nerve I@ path.

Next, in this invention, the control pulse frequency when a tape recorded in IK mode is played back for 1 hour in the IH mode, and the control pulse frequency when the tape recorded in IH mode is played back for 2 hours and 3 hours, respectively. Table 2K summarizes the control pulse frequencies when playing at double speed. The control pulse frequencies are also summarized when a tape recorded in 2H mode or 3 mode is played back at double speed in 1 hour playback mode, 2 hour playback mode, and 3 hour playback mode.

As seen from Table 2, the regeneration control pulse Ji
The lt wave number is 10Hs, 1!, -x, -x2, normal, 2x, 32x, 10Hs, 1!, 2x, 32x, 2x, 32x, 10Hs, 1! us e
30 Hz m 60 Ha * 90 Ha ()
Preferably, the frequency is at the control pulse frequency.

On a VTB that allows 1 hour recording, 2 hour recording, and 3 hour recording, you can specify 1 hour playback mode, 2 hour playback mode, and 3 hour playback mode even during playback. can. Therefore, there is no playback mode different from the mode at the time of recording.

Therefore, the present invention provides a method for automatically determining the recording mode of the tape being played back by using the control pulse frequency (Table 2). When circuitized, it is constructed as shown in FIG.

In FIG. 1, 11 is an input terminal to which a reproduced pulse is applied, and 12 is an input terminal to which a reference Δ pulse of a constant frequency is applied. The reference clock is obtained from the counter of the amplified digital circuit.

The input terminals 11exz are each connected to a frequency divider 13°141i.
c is connected.

■ It has a 1x frequency division function, and these O frequency division ratios are
5. The switching circuit IS sets the frequency division ratios of the frequency dividers 13 and 14 in response to a user's reproduction request.

That is, as shown in Table 3 below, the frequency division ratio is specified in response to the reproduction request.

That is, for normal playback, the frequency dividers 13 and 14 are 1x, for double speed playback, the frequency divider 13 is 1/2x, and the divider 14 is 1x,
For 3x speed playback, the frequency divider IJ is 1/3x, the divider 14 is 1x, and for 1/2x playback, the frequency division sIS is 1x, the divider 14 is 1/2x, 1/3x In the case of reproduction, the frequency divider 13 is 1
The frequency divider 14 is set to a frequency division ratio of 1/3.

The frequency-divided output of the frequency divider 13 is applied to the clock input terminal of the first 7-lip-frog circuit 1e. 7 rip 7
Gastric circuit 1g, 17.1M, AND circuit 19, 20.
The counter 2j is a circuit that counts the reference value q obtained from the frequency division @Ii in one period of the output pulse of the frequency divider I3. In other words, it is a circuit that measures the period. Also,
Flip-flop circuit 11. The AND circuit 21 is a circuit that generates a clock for the counter 25.

Flig7cIg circuit 111. The operation signal waveforms in I'l, 1g and AND circuits II, III, and 11 are arranged as shown in second WIA(a) to (quantity).

FIG. 2(1) shows the clock pulses applied to the clock input terminals of the seven logic circuits 17 and 18, and FIG.

If (@) e (d) in the same figure is the output pulse waveform of the output terminals Q and Q of the slip 70ff circuit 16, and (@) is the output pulse waveform of the output terminal Q of the slip 70ff circuit 110. Figure θ) The output pulse of the AND circuit 19 is used as a clear pulse for the counter 22. Next, the same IP
I(x) is the value added to the first input terminal of the AND circuit 2o.
When this pulse is at a high level, the AND circuit 2o becomes conductive and adds the output of the frequency divider 14 to the counter 22 as a μ. Same picture) Mine 7rig 70
The waveform of the output terminal QC) of the output terminal of the logic circuit 18 is the output pulse waveform of the AND circuit 11C).

The counter 22 counts the clock input to the clock input terminal at the pulse period manually input to the clear terminal.

The count value of counter 22 is applied to one input terminal of comparator 23.24 of III, 12. , comparator 2
3.24 compares the magnitude relationship between the output B from the counter z2 and the respective constants C.

B is the output of the counter 22, M is the constant of the comparator xs,
Assuming that the constant of the comparator 24 is C, the comparison GSS obtains the judgment result of M〉B, and in this case, a high level output is applied to the down-count control terminal of the counter 25, and this counter 2j is down-counted. Switch to Further, the comparator 24 obtains a determination output of C<B, and in this case, a high level output is applied to the up-count control terminal of the counter 25, and the counter 21 is switched to up-count. The count output of the counter 25 is the decoder 2
g9' (added. This decoder 2IIF calculates the VTRf) playback time 'E-P (IH, 2H, 3H
). First, depending on this judgment result, memory 2
2 provides a designation signal for setting the frequency division ratio of the cab stan rotation detection pulse to an appropriate frequency division ratio. This memory 2r generates a frequency division ratio as shown in Table 1 based on the reproduction request signal ss and the determination result. The playback request signal is
It is determined by the user's specifications.

Next, the operation of the above circuit will be explained.

In this case, the reference pulse of the input terminal 11 is set to 512 Hz, and the counter 22 is set to 7 bits, and the counter 25 is set to 2 bits. When the VTR is put into playback mode, the first step is decoding 1zt.
tld. Assuming that a chive in IH mode is currently being played, set the VTRK 1-hour playback mode.

In this case, Ude wants normal playback, and frequency divider 1
3゜14 is specified with a division ratio of 1, and memory xr
A designated signal for normal playback is also added to K.

For normal playback, as shown in Table 2, the frequency of 1 control/4 pulses must be 30 Ha no matter what mode the tape is in. If the VTR is playing a tape in IH mode, the counter 22 will count 17 pulses. Here, comparator 24
If the constant of the comparator 21C is set to "15" and the constant of the comparator 21C is set to "19", neither the up count command signal nor the count/count command signal is applied to the counter 2J. Then, the outputs of the comparisons @xs and xi are both at low level.The controller determines this and maintains the current reproduction state.

Next, if the tape being played now is in 2H mode, the VTR is playing it as if it were in 11 mode, so II! ! 2, a 15 Hz control pulse is obtained.

In this case, when the counter JJ counts 19 or more pulses (tlJ), the comparator 24 outputs an up-count command signal.

As a result, Gouko/26 switches the VTR to 2-hour playback mode. When K is set in this way, the frequency of the reproduction control pulse becomes 30 Hz, and the counter 2f becomes "17".
K so as to output count values. Even though the count value of the counter 22 does not reach "17",
9, the VTR is switched assuming that it is playing a tape in 3H mode.

The above explanation is for the case where normal playback is requested, but
Next, a case where the user specifies 1x speed will be explained. It is now assumed that the tape installed in the VTR is in 3H mode. First, when a play operation is performed, the decoder 2
6 is reproduced as being in IH mode, so 45Hs is obtained as a control pulse. At this time, the frequency divider IS has a frequency division ratio of 1xO. On the other hand, since the reference pulse is frequency-divided by half by the frequency divider 14, the frequency divider 14
A frequency-divided output of 256 Ha is obtained. At this time,
The counter ff1Jd outputs a count of 15 or less.

Therefore, a down-count command signal is obtained from the comparator 23, and the contents of the counter 25 are included in this signal. Decoder 26 determines this, and decoder 2#
Specify R to playback mode for 2 hours. In this way,
When the frequency of the reproduction control pulse is 22.5 Hs, the counter 22 is cleared according to the relationship of 256/22.5, so the count output is less than ls. Accordingly, the K VTR was switched to the 3-hour playback mode,
With K in this way, the regeneration control amount Lus a15H
zt1kl), count output tfr of the force outputter 22
The ζ0 playback code is maintained as a value obtained by counting 17 J 0Δ pulses.

According to the present invention, and <K, the counter 220
Constant r15J for count output.

19, but this means is the same when determining the tape in any mode.
You can use it. This uses frequency dividers 13 and 14,
Next 01iI! This is because the frequency division ratios of the frequency dividers 13 and 140 are set as shown in 3.

f#3 Figure 3 shows an example of a V'rR server I device using this invention, including a jJFi tape, 32 a capstan printer, a 331dw control head, and 34 a co-rotating head P disk motor. . Kiya! The methane motor 32 is provided with a carbancer circuit S5. Casostancer? The circuit 3j includes a cyclic counter 3g, a first
．． second latch circuit sr, ss% first . @2 subtraction circuit II, 40. fa) analog converter circuit 41 and motor bib circuit 42).

The cyclic counter 36 counts ripples), and the latch circuits sr and xzK each receive pulses that are symmetrical in phase comparison as latch pulses. latch circuit s
v and sa each latch the count value of the cyclic counter SlO by inputting a latch pulse. Therefore, if the difference between the contents of both zeros is calculated by the subtraction circuit 39, the phase difference of the ΔRus function that is symmetrical for comparison can be measured by the count value of the cyclic counter J#. The so-called time difference output of the subtraction circuit seO is input to the subtraction circuit 40, and a constant is subtracted therefrom. This is to find the center value of the manipulated variables. For example, if the continuous time difference is rxJ
If the value is 9, then it is sufficient to set rx/2J to a constant.If you do this, then becomes a manipulated output that can vary in your direction.

This output is converted into an analog quantity by the digital-to-analog conversion circuit 41, and is applied to the motor bi-2 decoy path 42.
Controls the cab stan motor 32.

The disk sensor circuit 5 for the rotary head disk motor 34 has the same configuration as the capstaff sensor 2 circuit 35, and the zero and I circuits 35 and 51 commonly use a cyclic counter sg.

1st. To the latch circuits 45 and 46 of the cell 2, the comparatively symmetrical /# pulse is added as a latch pulse. 10th
The subtraction circuit 4r has a first subtraction circuit 4r. Second latch circuit 45.4gC
), and the 20th subtraction circuit 48 sets the manipulated variable using a constant.

The output of the subtraction circuit 48 is converted into an analog quantity by the 5P digital-to-analog conversion circuit 4#, and is added to the motor drive circuit 50 as a control signal.
Controls evening 34.

The rotating head disk is synchronized with a vertical synchronizing signal VK during VTR recording, and a vertical synchronizing Δ pulse is input to the latch circuit 45 via switch B, and the latch circuit 41 detects the rotation of the disk motor 34. ΔRus is input. Further, during the reproduction operation, the rotary head disk expansion is synchronized with control pulses from the control spatula ysx.

On the other hand, Kya! The stun motor S2 is set to a constant rotational speed during the recording operation. Finally, the first. The amplifier frequencies shown in Table 1 are input to the 20th latch circuits sr and sa in accordance with each mode and double speed.

Frequency divider 4# divides the FGI 11 wave number according to the designated mode and designated speed. During the playback operation, the recording speed determination device 44 determines the tape 0 recording mode, and the frequency is divided @4S according to the determination result and the specified speed specified by the playback request.
The frequency division ratio is set. Note that during the operation of determining the tape speed during recording, the output of the forced KP circuit 42 is set by the previous decoder. In addition, the latch circuit 3r
switch 8. A control pulse is inputted as a two-touch pulse via.

As described above, this invention provides a method for determining the recording speed of a recording medium that is effective for automatically determining the recording medium's sickle time speed and obtaining an appropriate speed in accordance with the required playback speed at the end of playback. can be provided.

Table 3

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of this invention, Figure 2-)
~(1) is a signal engraving diagram of each part of the circuit in Figure 1, and Figure 3 is a configuration explanatory diagram showing an example of a V'rR system using this invention.・Frequency divider, 22-kakunta, 23°2.
4... Comparator.

Claims (1)

[Scope of Claims] A 20th frequency divider that performs normal reproduction, double speed reproduction, and triple frequency of a reference clock of 02'' times the control pulse frequency of the recording medium; and a 20th frequency divider that performs normal reproduction of the reproduction control pulse;
The frequency division output of the 20th frequency divider O is used as a clock input, and the 20th
means including a counter for measuring the pulse period of the divided output of the frequency divider using the count value of the tarok; and determining the magnitude relationship between the count value and each constant using the count value and at least two constants; A method for determining a speed at the time of recording of a recording medium, comprising a comparison means and a means for determining the comparison result of the comparator IR to determine whether or not the moving speed of the recording medium is appropriate.