JPS5835744A - Recording speed discriminating system for recording medium - Google Patents

Abstract

PURPOSE:To automatically discriminate a tape speed at recording and to set a reproducing tape speed, by monitoring a rotating detection pulse frequency at the reproducing mode of a VTR and a reproduced control pulse frequency from a tape. CONSTITUTION:A reproduced control pules is inputted to a sequence pulse generator 13. Each output of this sequence control pulse generator 13 is to obtain conduction/nonconduction control of an AND circuit 14, a clear timing of a counter 15 and a latch timing of a latch circuit 16. When the AND circuit 14 to which a rotation detecting pulse of a capstan motor is inputted is controlled at a conductive state, the rotation detecting pulse is a clock to the counter 15. The count value of the counter 15 is latched at a latch circuit 16, compared with different constants at comparators 17, 18 and the speed at recording can be discriminated.

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 recording.

In general, a VTR uses a helical scan method for recording and reproducing using a rotating disk, and the magnetic tape used for this is also a cassette tape or a tape tape.

■ With the development of recording and playback technology, this type of VTRK can record for one hour (hereinafter referred to as IH mode), for two hours (hereinafter referred to as 2H mode), and for three hours even if the length of the magnetic tube is the same. Time recording (hereinafter referred to as 3H mode) is possible, and you can set your preferred writing time by selecting the timer.

■ On the other hand, regarding playback operations, there are many functions, including special playback such as 1x speed playback, 2x speed playback, 3x speed playback, 1/2x speed playback, 1/:1x speed playback, and still playback. It is possible.

■ By the way, if you want to get double or triple speed playback when playing back a chive in 1M mode, set the appropriate double playback tape speed for the tape speed at the time of placement. When playing back a 2H mode, a playback speed that is double the speed at which it was recorded must be set.

As mentioned above, in the t-VTR, if the speed during playback is set by changing the speed manually, the operation is extremely cumbersome. Also, just by looking at the magnetic tape,
Since it is not possible to determine from the outside what mode this is being recorded in, it takes time and effort to write it on the label of the cassette in advance at the time of recording.

In order to cope with the above-mentioned devices and the like that have a wealth of functions related to speed, the present invention provides a recording medium that can automatically determine the tape speed at the time of recording the tape and set a playback speed that satisfies the playback request. The purpose is to provide a recording speed discrimination method.

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

First, in the present invention, the cab stun rotation detection/Gurus j [number (hereinafter referred to as FG frequency for simplicity) in the playback mode of the VTR and the control noise frequency played from the Chil are monitored. By this,
It determines whether the recording mode of the tape is IH, 2H, or 3H, and depending on the result of this determination, the mode suitable for the playback request (2x speed, 3x speed, 1/2x speed, 1/3x speed) is determined. This allows switching to playback tape speed.

For this reason, the inventor has prepared a table as shown at the end of the detailed description, and based on this table, constructs the judgment circuit.

First, Table 1 shows the FG frequency when a tape in recording mode (IH) (2H) (3H) is played back at double speed.
It is Hz. Considering this as a standard, 1A times,
Each PG frequency during IA times, 2 times, and 3 times speed playback is 240
Hz, 360Hz.

1440Hz and 2160Hz correspond to playback requests. Similarly, F when each tape in 2H mode and 3H mode is played in response to each playback request.
The G frequency range is as shown in Table 1.

The frequency division ratio shown in Table 1 can be used to detect cab tongue rotation/dulse! When using a standby system, it is easy to use to detect the amount of error using a standby circuit. This is the value that Qi sets on the circuit side to convert to the ring frequency.

Next, Table 2 shows the control k/kx frequency for each playback i request when a tape in one recording mode is played back in the wrong time mode and in the normal time mode. Leave the tape in IH mode in playback mode for 1 hour, and
If you switch to double speed, you will get a control dulse of 10Hz, 1/! 2x speed 9 Normal beak When switching to 2x speed and 3x speed, respectively, 15 e 30 * 60 m 90Hs
This relationship is 2
Leave the tape in H mode in playback mode for 2 hours, and then
1/2x 1 Normal (10°15.
30,60.90Hz. Also, a tape in 3H mode can be played back 17'3 times in 3 hour playback mode.

1/! 9 times normal, 10°15 even when switching to 2x or 3x speed
．． 3'0,60.9'OHi and similar related tonals.

That is, if the correct playback time mode is set, the tape of each i-de will be multiplied by IA, l/! times 1 normal.

When switching to 2x or 3x speed, 10 times depending on each speed *
15 * 30 a 6-Oe 90HiOko7to
- You will be able to obtain Luno Lus.

However, even though I am playing a tape in IH mode, 2
When the time playback mode is set and normal playback is performed, the control noise frequency becomes 15Hz. If this is played back at double speed, the control pulse frequency will be 30 Hz. Table 2 shows such a relationship, and shows the control/failure frequency when an incorrect playback time mode is set for each mode and each double speed playback is specified at that time.

Next, Table 3 shows the relationship between the FG frequency and the control/arm frequency ratio by looking at the relationship between Tables 1 and 2.As shown in Table 3, when playing a tape in 1■ mode, In this case, no matter what playback time mode and double speed mode you set, the FG frequency/control nose frequency is 24 (J), and the tape in 2'H mode is played back. If the tape is played back in 12.3H mode, the result will be 8.

FIG. 1 shows a circuit that determines in which mode the tape being played back was recorded by looking at the ratio between the FG frequency and the control noise frequency. Reference numeral 11 denotes an input terminal to which rotation detection of the capstan motor is applied, and reference numeral 12 denotes an input terminal to which reproduction control/reference is applied. The playback control/f pulse is input to the sequence master pulse generator 13. This sequence/master pulse generator 13 receives the reproduction control/f pulse as input data, transfers it by chromatography, and outputs a sequence pulse. Each output pulse of this sequence/dal 1 generator 7s is a conduction of the AND circuit 14 at the clock input part of the counter 15, a clear tie of the non-conduction control counter 1! get the results. When the AND circuit 14 is controlled to be in a conductive state, the rotation detection/error of the capstan motor becomes a clock signal to the counter 15.

The count value of the counter 150 is latched by the timing of the latch circuit 16 and compared with different constants in the ratio IIR device 11.18.

The above sequence norse generator IJ and counter fJ
K! Therefore, the ratio between the playback control/pulse frequency and the capstan motor rotation detection/arm pulse frequency can be easily determined. This measurement can be freely selected at which seismic period of the regeneration control I base Rus, depending on the required accuracy.

Next, for example, the comparator 11 selects M≧B, and the comparator 18 selects A≦C.
, the constants B and C are determined by referring to Table 3.
is set to satisfy the following equation. Note that the output from the latch circuit 16 is output from the latch circuit 16.

8 m (C (12 m (B It is possible to discriminate and determine the tape speed at which recording can be performed.The 3H mode is selected when neither Mu≧l nor Mu≦C is present.
．． This is to determine the 2H mode from the output of Even if I don't know what to do, I'll turn that tape into V.
If you set it to TR and drive and playback, you can immediately tell the difference. If this discrimination is possible, from the discrimination output,
The capstanser can automatically select and switch the system's capstan detection/arm division ratio, etc. As can be seen from Table 1, the frequency division ratio for normal playback or double speed playback is known in advance for each mode, so the judgment result is compared with the playback request specified from the outside. , just select the frequency division ratio at that position.

Furthermore, according to the method of the present invention, when the tape mode is switched midway, for example, when about half of the data is recorded in IH mode and the remaining half is recorded in 2H mode, If the speed at the time of recording is determined, even if this tape is played continuously, a discrimination output will be automatically obtained.
This is effective for setting the tape speed according to the playback request from that point on. In addition, it can be detected even at the start-up time of tape running, and ζ can be achieved by setting the speed to a speed corresponding to the reproduction request, which has a quick response.

FIG. 2 shows a system (1) to which the present method is applied, and the state of the switches tj Wll 8 Wl is changed to the reproduction state. 11 is a magnetic tape To'), xx
is a capstan motor, and JJ is a rotating Rad motor. A circuit 24 is applied to the capstan motor 21, and a rotary head motor 23 is applied to the capstan motor 21.
The rotary head diffuser circuit 25 acts on the rotary head diffuser circuit 24, and the rotary head diffuser circuit 2j has basically the same configuration, and uses the digital Asahi method. This has already been filed by the applicant and is also described in detail in the specification.

To briefly explain the circuit, the capstancer circuit 24 includes a cyclic counter 26, a first . second latch circuit xy, 2B, first . Second subtraction circuit 29. :10
．． The digital-to-analog conversion circuit 31 and the like are configured. The output of the digital-to-analog conversion circuit 31 is input to the capstan motor drive circuit s2.

As the latches of Ml, the second latch circuits xv, and xtt, the latch whose phase and frequency are to be compared is used.゜2II overwrites the count value of the counter at that time when each latch/gus is input.

2. of each latch circuit sr, Hg. The contents of the subtraction circuit xm<
The subtraction process is performed, but this result is stored in the cyclic counter 2.
The 60 count value will be used to calculate the time difference between each latch/4 pulses.

If this time difference is always the desired value, it means that the occurrence of latch/4 pulses is normal.

The second subtraction circuit SO sets an operation range (variable range) by subtracting a constant from the data representing the above-mentioned time difference. Now, the time difference under normal conditions is set to cl. If you do this,
The time difference increases or decreases with L as the center, and it is possible to output it as a manipulated variable. This output is input to the digital-to-analog conversion circuit 11 and then input to the motor drive circuit 32 as an analog control signal.

Disfuner? A similar configuration is used in the circuit 25, and the first. The second latch circuit j3゜34, the first latch circuit j3゜34. Second subtraction circuit ss, set, digital-to-analog conversion circuit 31
, a drive circuit J8 are provided. t, this is-
In the circuit, the count output of the cyclic counter 26 is used in common with the cannostanchy circuit 24. In the disk drive circuit (i), when in the recording state, the rotary head is vertically It is set to synchronize with the synchronization signal (V). In the playback state, the control pedal 4 is designed to synchronize with the signal from the control pedal 4o. 3# is a correction circuit for the control pedal, which is 1A times 1/2. times 0 normal.

This is for switching to a frequency that is easy for the circuit to handle during special playback such as double or triple speed, and can be specified externally. This frequency is determined by the number of pits in the cyclic counter and the frequency of the clock.

Next, the capstancer is connected to the circuit 74, and the capstan is detected/detected so that the rotational frequency is constant during recording.
4 pulses are input to the latch circuits zv and xa.

Next, at the time of playback, 2. The sub circuit 21 receives the reproduction control/main signal latch/floating signal input, and the sub circuit 28 receives the frequency division of the cab stan rotation detection signal by the divider 41. The 0 frequency divider 41 input as a latch/4I pulse is provided with a table mode setting circuit as shown in Table 1. If a command for normal playback is input from the outside, and if there is a determination output 1 from the recording speed determination circuit 42, a division ratio of 1/6 is set. Further, when there is an external designation of 3x speed and there is a determination output of %2H, a 1/90 frequency division ratio is set. The recording speed discriminating circuit 42 is a circuit using the method of the present invention explained in FIG. 1), and automatically discriminates the recording time mode. This determination is made instantaneously when the VTR is put into the playback state and is started up, and after that, the circuit performs a pulling operation for stable running.

According to the above invention, various speeds can be set regarding the recording speed of the recording medium.
Special playback (1/2.1/'3) during playback.

It is possible to provide a recording speed determination method that is effective for a device with rich functions that can perform double, triple speed, etc., and can automatically determine the recording mode.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining one implementation of the method of the present invention, and FIG. 2 is a block diagram showing a system of a video recorder using the method of the present invention. 13-.Sequence pulse generator, 15..Counter, IC..Latch circuit, 1r, 11j..Comparator. Applicant's agent Patent attorney Takehiko Suzue 245-

Claims (1)

[Claims] Detecting the ratio between the rotation detection frequency of the rotating shaft that drives the recording medium and the reproduction control frequency obtained by reproducing the signal recorded on the recording medium at a constant frequency, and A method for determining a recording speed of a recording medium, characterized in that a value of a detection result is compared with a constant, and an output for determining a recording speed when a signal is recorded on the recording medium is automatically obtained.