JPS6328180A - Selection signal generator for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce a delay time and to obtain a selection signal generator extremely strong to an impact or the like by forming a delay pulse from one obtained by dividing the frequency of an FG signal. CONSTITUTION:When the selection signal ER1 is obtained, a pulse signal d1 delayed by a time t5 from the rise edge of the output (c) of a frequency divider 17 and a pulse signal d2 delayed a time t6 from a rise edge are formed by a pulse delay circuit 20. The signal (c) and a PG signal (a) are formed in a selection pulse generating circuit 14 to form selection pulses (f3), (f6) and in a selection circuit 21, the AND of the signals d1 and the signal f3 is taken and the AND of a set signal e4, a signal d2, and a signal f6 is taken and outputted as a reset signal e3. When the output is inputted to the set terminal and the reset terminal of an RS-FF22b, a desired selection signal ER1 is obtained. By using a signal obtained by dividing the frequency of an FG signal, the delay time can be considerably reduced and when the selection signal ER1 is formed, a selection signal generator extremely strong to the impact or the like is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic head selection signal generating device for a magnetic recording/reproducing device such as a video tape recorder.

Conventional Technology When recording, reproducing, or erasing information on a magnetic tape using a helical scan using a rotating cylinder equipped with a magnetic head, there is a selection method for generating a signal selected by the recording, reproducing, or erasing head at a position that meets the specifications. A signal generator is required.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the above-described conventional selection signal generation device is applied to a two-head helical scan type magnetic recording/reproducing apparatus with flying erase will be described below with reference to the drawings.

FIG. 2 is a configuration diagram of the rotating cylinder. In FIG. 2, l is a rotary cylinder, 2 and 3 are recording/reproducing heads making an angle of 180° to each other, 4 and 5 are erasing heads making an angle of 180° to each other, and erasing head 4 is a recording/reproducing head. It forms an angle of 60° with respect to the rotation direction of the reproducing head 2. 6 is a magnetic tape, 7 and 8 are tape guides, and the magnetic tape 6 is wound around the rotating cylinder 1 as shown in the figure.

A method of generating a signal for selecting the magnetic heads arranged as described above will be explained with reference to FIG.

The signal PCI is a signal that generates one pulse every time the rotary cylinder 1 rotates once, and the signal PG2 is about 1 pulse from the signal PCI.
It has a phase difference of 80°. The signal PLY used to select the reproduced signals from the recording/reproducing heads 2 and 3 is a signal with a duty ratio (df) of 0.5 whose phase is adjusted by monomultiplying from the signal PGI and the signal PG2. Signal E
RI and the signal ER2 are signals for controlling the supply of erase current to the erasing pads 4 and 5, and when at a high level, the erasing current flows to the erasing pads 4 and 5. Signal ER1 varies from the falling edge of signal FLY to 1. t! from the time-delayed delayed signal and the rising edge! It is formed by using a time-delayed signal to set R3-FF with the former and reset it with the latter. Also, the phase of signal ER2 is 180° with respect to signal ERI.
Unlike signal ER1, it is formed using a delayed signal from the edge of signal FLY. The approximately 60° phase lead of the signal ER1 relative to the other signal FLY is because the erasing heads 4 and 5 are mounted on the rotary cylinder 1 at positions 60° ahead of the recording/reproducing heads 2 and 3 in the rotational direction. It is. Furthermore, since the recording area on the magnetic tape is wider than the reproduction area, the signal ERI is a signal whose high-level period is 3H (H is horizontal synchronization) longer than that of the signal FLY. A recording signal selection signal to the recording/reproducing head is also formed in the same manner as described above. Thus, conventional selection signal generators require very long delays.

For example, in the NTSC system, approximately t + =11.23 (
ms).

It is approximately tz" 11.61 (ms).

Problems to be Solved by the Invention However, with the above configuration, the circuit configuration is complicated, and the delay time when generating the delayed signal is long (and the pulses generated due to mechanical shocks etc. generated during that time are long). The time axis shift of the signal is not transmitted to the delayed signal at all, and the position of the rotary head relative to the magnetic tape and the electrical timing are shifted, resulting in erasing, recording, and reproduction of other areas on the tape.

In view of the above-mentioned problems, the present invention provides a selection signal generating device for a magnetic recording/reproducing device, which has a simple configuration, has an extremely small delay time, and has an extremely small time axis shift of an electric signal due to an impact or the like. be.

Means for Solving the Problems In order to solve the above problems, the present invention forms the delay pulses from a frequency-divided FC signal, thereby reducing the delay time.

Effects of the Invention With the above-described configuration, the present invention uses a high-frequency FC signal that follows the rotation of the rotary head, so the delay time can be made extremely small, resulting in a selection signal generation device for a magnetic recording and reproducing device that is extremely resistant to shocks and the like.

Embodiment Hereinafter, an embodiment of the present invention applied to a helical scan type magnetic recording/reproducing apparatus with a two-head type flying erase will be described with reference to the drawings.

As shown in FIG. 3, a video track 36 is formed on the magnetic tape 6 and is inclined at a predetermined angle with respect to the tape running direction. Further, the upper and lower parts of the magnetic tape 6 are an audio trunk 35 and a control track 37, respectively.

Since the magnetic recording/reproducing apparatus is of a two-head type, two video tracks are formed by one revolution of the rotary cylinder, and one video track is formed by half a revolution of the video track. Here, for example, if a shift occurs in the selection signal of the erase head, information recorded on the audio track 35 or the control trunk 37 will be erased, which is extremely inconvenient.

FIG. 1 is a block diagram of a selection signal generating device according to an embodiment of the present invention.It will be explained below with reference to the drawings.In FIG. 1, 10 is a magnet, 1 is a rotary cylinder equipped with a magnet 9 is a magnetic head fixedly arranged opposite to the magnet 10, 11 is an amplifier that amplifies the signal from the magnetic head, 12 is an integrator that integrates the signal from the amplifier 11, and 13 is a signal from the integrator. This is a comparator that generates a PCC signal that compares the signal level with a reference level and generates one pulse every time the rotating cylinder 1 rotates. 13 constitutes a PG signal generator, 15 is a motor that drives the rotating cylinder, 16 is an FC signal generator that generates 72 pulses every rotation of the rotating cylinder in order to read rotation information of the motor 15, and 17 is a PG signal generator. A frequency divider that is reset by the signal a and divides the frequency of the FC signal by 1/12 to form a signal C that generates 6 pulses every rotation of the rotating cylinder. 14 is a 3-bit counter 23 and a decoder 24.
In the 0 selection pulse generator 14, which is a selection pulse generator configured by is,
The count value of the 3-bit counter 23 is input to a decoder 24, and the output of the decoder 24 becomes the output of the selection pulse generator 14. The output is a signal that is at a high level for only one cycle of the large force signal C, which is the amount that the rotating cylinder makes one revolution;
Therefore, the large force signal C that makes one revolution of the rotating cylinder has six types of selection signals f (fl to f
6). 20 is a pulse delay circuit composed of a differentiating circuit 25, an oscillator 27, a counter 26, and a decoder 28, and the input signal C is inputted to the differentiating circuit 25. The differentiating circuit 25 detects the rising edge of the human waveform and generates a sufficiently short pulse at the edge position on the time axis.
The signal is input to the counter 26's glue set terminal.

The output of an oscillator 27, which includes a crystal resonator and generates a 1.79 MHz clock pulse, is input to a clock terminal of a counter 26. The counter 26 is reset by a reset signal from the differentiating circuit 25 and starts counting clock pulses from the oscillator 27. The count value is always sent to decoder 2.
8, the decoder 28 decodes a plurality of predetermined count values, and outputs a plurality of decoded signals.
This becomes the output d of the pulse delay circuit 20. 21 is a selection circuit that selects the delayed pulse group d using the selection pulse f and outputs a set signal and a reset signal; 33 is a set composed of R3-FF 22 that is set by the set signal and reset by the reset signal; /Reset circuit.

Next, the operation of the circuit with the above configuration will be explained with reference to the timing chart shown in FIG. Note that the symbols attached to the signals in this figure correspond to the symbols attached to the block diagram in FIG. 1, indicating the signal waveforms on the block diagram.

The selection signal ERI is a signal for controlling the supply of erase current to the erase head 4, and the erase current flows to the erase head 4 when it is at the noise level. To obtain the selection signal ERI, a pulse signal d1 delayed by t3 hours from the rising edge of the output C of the frequency divider 17 and a pulse signal d2 delayed by t4 hours from the rising edge are formed by the pulse delay circuit 20, and the selection pulse generation circuit 14, the selection pulses f3 and f6 are formed using the signal C and the PCC signal, and the selection circuit 21 ANDs the signal di and the signal f3 to generate a set signal e4.
AND the signal d2 and the signal f6 to generate the reset signal e.
Output as 3. If the output is input to the set terminal/reset terminal of R3-FF22b, the desired selection signal ER is generated.
1 is obtained. Further, when forming the selection signal PL'Y used for selecting the reproduction signal from the recording/reproducing radars 2 and 3, a delay pulse with a delay time t is formed and selected, and the selection signal ER2 When forming , there is a delay time t.

A signal can be formed by selecting delayed pulses of and t, and selection signals other than those described above can be formed in the same way.

For example, in the case of the NTSc system, approximately t s = 0.11 (m
s).

Approximately t h = 0.30 (ms).

As described above, by using the signal obtained by dividing the frequency of FG (No. 8), the delay time can be significantly reduced (selection signal ERI
When generating , the delay time in this embodiment is several tenths of a second compared to the conventional example. ) It becomes an extremely strong selection signal generator such as impact.

In this embodiment, the FLY signal for selecting the reproduction signal during reproduction and the signals ERI and ER2 for determining the energization time to the erasing head during recording have been described, but other selection signals (for example, when recording, the recording head A signal that determines the energization time can also be easily and stably obtained.

Effects of the Invention As described above, the present invention can generate a selection signal that stably and accurately follows the rotation of a rotary cylinder, and can use the FG double signal and PG double signal conventionally used for speed phase control, making it practical. extremely useful.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a selection signal generating device of a magnetic recording/reproducing device according to an embodiment of the present invention, Fig. 2 is a block diagram showing the structure of a rotating cylinder, and Fig. 3 shows various tracks formed on its surface. FIG. 4 is a waveform diagram showing the operation of forming the selection signal of the selection signal generator of the magnetic recording/reproducing apparatus in one embodiment of the present invention, and FIG. 5 is a plan view of the conventional magnetic recording/reproducing apparatus. 1 is a block diagram showing a selection signal generating device of FIG. 1... Rotating cylinder, 2... Recording/playback head a, 3... Recording/playback head b, 4...
... Erasing head a, 5... Erasing head b
, 9... Magnetic head, 10... Magnet, 14... Selection pulse generator, 15...
...Motor that drives the rotating cylinder, 16...
・FC signal generator, 17... Frequency divider, 20...
...Pulse delay circuit, 21...Selection circuit,
33...Set/reset circuit. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] A rotating cylinder having a rotating magnetic head that records, reproduces, or erases information by scanning a magnetic tape over a certain rotation angle, and a frequency generator that generates a speed panel signal (FG signal) by rotating the rotating cylinder. and one pulse (P
a PG pulse generator that generates a PG signal), a frequency divider that is reset by the PG signal and divides the frequency of the speed pulse, and a pulse delay that delays the output pulse of the frequency divider and generates a plurality of delayed pulses. a selection pulse generator that generates a selection pulse based on the output pulse of the frequency divider and a PG signal; and a selection pulse generator that selects the output of the pulse delay circuit based on the output of the selection pulse generator and outputs a set signal and a reset signal. 1. A selection signal generating device for a magnetic recording/reproducing device, comprising a selection circuit and a set/reset circuit whose output is set by a set signal of the selection circuit and set by a reset signal.