JPH0666943B2 - Magnetic recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, such as a video tape recorder, capable of achieving high image quality by raising an image carrier.

2. Description of the Related Art In recent years, video tape recorders (hereinafter referred to as VT
R) is abbreviated as high image quality, and high resolution VTRs are being developed by various companies. Regarding high resolution, (i) video carrier is mentioned. (Ii) Raise the white clip and dark clip. (Iii) Broaden the band of the filter. (Iv) Measures such as changing the peaking frequency of the RF system are taken, and on the other hand, measures such as changing the amount of emphasis of the luminance signal are generally well taken against S / N deterioration caused by raising the carrier. It has been subjected.

Problems to be Solved by the Invention However, with the above-mentioned configuration, the conventional standard VTR
When a tape recorded with (for example, VTR of VHS standard) is reproduced with the high resolution VTR, the peaking frequency of the RF (high frequency) system is different, resulting in poor S / N and different white clips. There is a problem that it is easy to occur and that the tape being played back is a conventional standard or a tape recorded with a high resolution VTR cannot be identified.

In view of the above problems, the present invention provides a magnetic recording / reproducing apparatus capable of discriminating between a tape recorded by a conventional standard VTR and a tape recorded by a high resolution VTR, and switching and displaying various modes. It is what

Means for Solving the Problems In order to solve the problems, a magnetic recording / reproducing apparatus of the present invention is a switch unit for switching the RF output of a video tape recorder by a vertical synchronization signal or a horizontal synchronization signal, and a switch unit thereof. The bandpass filter that extracts the required band of the RF output after switching by the, the detection circuit that detects the output of the bandpass filter, the comparison unit that compares the output of the detection circuit with the reference voltage, and the output of the comparison unit A data holding unit that holds the data holding unit, a timing unit that determines the timing of the data holding unit, a mode switching unit that switches the mode according to the output of the data holding unit, and a display unit that displays the output of the data holding unit. It is equipped and configured.

Operation With the above-described configuration, the present invention makes it possible to reproduce a tape recorded in a conventional standard VTR in a high-resolution VTR, and also display the tape discrimination display.

Example Hereinafter, a magnetic recording / reproducing apparatus of an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of an essential part showing an embodiment of the present invention. In FIG. 1, 1 is a switch circuit to which a VTR RF signal is input, 2 is a buffer amplifier, 3 is a bandpass filter (BPF), 4 is an amplifier, 5 is a buffer amplifier, 6
Is a coupling capacitor, 7 is a detection circuit including diodes 8a and 8b, capacitor 9 and resistor 10, 11 and 12 are resistors for creating reference voltage Es, 13 is a comparator, 14 is a timing circuit, and 15 is data retention D type flip-flop (DFF) circuit, 16 is a mode switch, 17 is a base resistor, 18 is a light emitting diode for display (LE
D), 19 is a current limiting resistor, and 20 is an LED drive transistor.

The operation of the magnetic recording / reproducing apparatus of the present embodiment configured as described above will be described below with reference to FIGS. 1 and 2.

First of all, FIG. 1 shows a discrimination circuit of a conventional standard VTR or a high resolution VTR and a switching circuit portion. FIG. 2 shows signal waveforms and timings at each part at that time.

In FIG. 1, an RF signal, which is the output of a head amplifier of a VTR, is input to a switch circuit 1 and is switched by a vertical synchronizing signal or a horizontal synchronizing signal (in the following description, the case of the vertical synchronizing signal will be described for simplification). To do. This output
It is input to the bandpass filter 3 through the buffer amplifier 2. The bandpass filter 3 has a center frequency f
Set ₁ to the FM modulation frequency that corresponds to the sync chip of the high resolution VTR, and make the filter with a narrow band and steep characteristics. This output [shown in FIG. 2 (c)] is passed through the amplifier 4 and the buffer amplifier 5, and then detected by the detection circuit 7 [see FIG. 2 (d)]. Then, the detected output is compared by the comparator 13 with the reference voltage Es, and the comparator output [see FIG. 2 (e)] is compared with the D flip-flop circuit 15.
Send to. The clock of the D flip-flop circuit 15 is generated by the timing circuit 14 from the falling edge of the vertical synchronizing signal so that the rising edge comes about half the width of the vertical synchronizing signal [see FIG. 2 (f)]. Therefore, the comparator output is held at the rising edge of the D flip-flop circuit 15 until the next vertical synchronizing signal arrives.

As described above, in the conventional standard VTR, since there is no output to the bandpass filter 3, the comparator output is low (Lo
w) level, and in a high resolution VTR, the comparator output becomes high level as shown in FIG. With this output, the mode selector switch 16 is used to switch the video carrier, white clip, dark clip, and the like. Further, the LED 18 is driven by the transistor 20 to perform tape discrimination and display.

As described above, according to this embodiment, by providing the RF signal switch unit, bandpass filter unit, detection circuit unit, comparison unit, data holding unit, timing circuit unit, mode switching unit and display unit, A tape recorded with a standard VTR can also be played back without blurring or S / N deterioration in a high-resolution VTR, and the tape being played back is a tape recorded with a conventional standard or a high-resolution VTR. It is possible to determine whether the tape is recorded on the display unit.

Next, another embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a circuit diagram of a main part of a magnetic recording / reproducing apparatus showing a second embodiment of the present invention. In the figure,
Reference numeral 21 is a buffer amplifier, 22 is a bandpass filter, 23 is an amplifier, 24 is a buffer amplifier, 25 is a coupling capacitor, and 26 is a detection circuit including diodes 27a and 27b, a capacitor 28 and a resistor 29. Others are the same as those in FIG. That is, the difference from the configuration of FIG. 1 is that the reference input (E ₁ ) of the comparator 13 is obtained by the detection output of the steep bandpass filter 22 that passes only the FM modulation frequency corresponding to the sync chip of the conventional VTR. That is the point.

The operation of the magnetic recording / reproducing apparatus of this embodiment configured as described above will be described below. As described above, the bandpass filter 3 sets the center frequency f ₁ to the FM modulation frequency corresponding to the high-resolution VTR sync chip, and the bandpass filter 22 sets the center frequency f ₂ to the conventional standard VTR sync chip. The FM modulation frequency corresponding to the chip is set.
Therefore, when the tape recorded by the conventional standard VTR is reproduced, the relationship between the input E ₁ and the input E ₂ of the comparator 13 is
E ₁ > E ₂ , and the comparator output goes low.
Further, when a tape recorded with a high resolution VTR is reproduced, the relationship between the inputs E ₁ and E ₂ of the comparator 13 becomes E ₁ <E ₂ and the comparator output becomes high level.

As described above, a bandpass filter whose center frequency is the FM modulation frequency corresponding to the sync chip of the conventional standard VTR.
22 is provided, and the signal whose output is detected is comparator 13
By using the reference input of, the detection outputs of the two bandpass filters 3 and 22 can be compared with each other, and more reliable operation with respect to noise and the like can be expected.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to obtain an excellent effect that a tape recorded in a conventional standard VTR can be reproduced in a high resolution VTR and a tape discrimination display can be performed. You can

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts of a magnetic recording / reproducing apparatus according to a first embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part of FIG. 1, and FIG. 3 is a second embodiment of the present invention. 3 is a block diagram of a main part of the magnetic recording / reproducing apparatus according to the first embodiment. FIG. 1 ... Switch circuit, 3,22 ... Band pass filter, 7,
26 …… Detector circuit, 13 …… Comparator, 14 …… Timing circuit, 15 …… Flip-flop circuit, 16 …… Mode selector switch, 18 …… LED, 20 …… LED drive transistor.

Claims (1)

[Claims] 1. A switch unit for switching the RF output of a video tape recorder by a vertical synchronizing signal or a horizontal synchronizing signal, a bandpass filter for extracting a required band of the RF output after the switching by the switch unit, and a bandpass thereof. A detection circuit that detects the output of the filter, a comparison unit that compares the output of the detection circuit with a reference voltage, a data holding unit that holds the output of the comparison unit, and a timing unit that determines the timing of the data holding unit, A magnetic recording / reproducing apparatus comprising: a mode switching unit that switches a mode in accordance with an output of the data holding unit, and a display unit that displays an output of the data holding unit.