JPH0124729Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic recording and reproducing device incorporating a frequency characteristic display circuit.

Until now, there has been no magnetic recording/playback device with a built-in frequency characteristic display circuit.

The frequency characteristics of magnetic recording and playback devices are measured by the manufacturer, but users can easily measure the frequency characteristics of their own magnetic recording and playback devices to determine bias,
Also, it was not possible to set the equalizer etc. according to the purpose of use.

The present invention has been made in view of the above, and an object of the present invention is to provide a magnetic recording and reproducing device that has a built-in frequency characteristic display circuit and can easily determine the frequency characteristics.

The present invention will be explained below with reference to examples.

FIG. 1 is a block diagram of one embodiment of the present invention.

In FIG. 1, 1 is a variable frequency oscillator. The output of the variable frequency oscillator 1 is sent to the recording head 2a.
and the output of the reproducing head 2b is applied to the rectifier circuit 4a.
is applied and rectified. On the other hand, variable frequency oscillator 1
The output is applied to the rectifier circuit 4b and rectified. The outputs of the rectifier circuits 4a and 4b are applied to a comparator 5, and the comparator 5 detects that the output of the rectifier circuit 4a is lower than the output of the rectifier circuit 4b by, for example, 3 dB. Further, the output of the variable frequency oscillator 1 is applied to the display 6. The display 6 is applied with the output of the comparator 5 and is configured to display the oscillation frequency of the variable frequency oscillator 1 while the output of the comparator 5 is being generated. The output of the rectifier circuit 4a is applied to a display 6' so that the level of the output signal of the rectifier 4a is displayed on the display 6'.

In one embodiment of the present invention configured as described above, the variable frequency oscillator 1 is driven, the output of the variable frequency oscillator 1 is recorded on a magnetic tape via the recording head 2a, and the magnetic tape is reproduced by the playback head 2b. . The oscillation output of the variable frequency oscillator 1 is rectified by a rectifier circuit 4b and converted to a DC level, and the output of the reproduction head 2b is also rectified by a rectifier circuit 4a and converted to a DC level. At the same time, the output levels of rectifier circuits 4a and 4b are compared by comparator 5. During this time, the rectifier circuit 4
The level of the output signal a is displayed on the display 6'. Next, the oscillation frequency of the variable frequency oscillator 1 is changed.

As the oscillation frequency of the variable frequency oscillator 1 is changed, the output levels of the rectifier circuits 4a and 4b also change, and the display on the display 6' shows that the oscillation frequency of the variable frequency oscillator 1 is changed.
It changes as the oscillation frequency changes. On the other hand, when changing the oscillation frequency of the variable frequency oscillator 1, the output level of the rectifier circuit 4a is
The comparator 5 generates an output when the output level is 3 dB lower than the output level of the comparator 5, and the display 6 displays the oscillation frequency of the variable frequency oscillator 1 when the output level of the comparator 5 is generated. Therefore, the upper limit frequency of the reproduction frequency characteristic is displayed on the display 6.

Next, other embodiments of the present invention will be described.

FIG. 2 is a block diagram of another embodiment of the present invention.

In FIG. 2, 12 is a microcomputer. The reference frequency oscillator 7, phase comparator 8, low pass filter 9, voltage controlled oscillator 10, and programmable divider 11 constitute a frequency synthesizer, and the programmable divider 11 has its frequency division ratio set by the output signal of the microcomputer 12. . Also, a frequency divider 13 that receives the output of the frequency synthesizer, a pit generation ROM 14, a digital-to-analog converter (hereinafter referred to as a D/A converter) 15 that converts the output of the pit generation ROM 14 into an analog signal, and a D/A converter 15. The low-pass filter 16 that filters the output of the programmable divider 11 and the frequency synthesizer constitute an equivalent variable frequency oscillator that generates a pseudo sine wave.
The oscillation frequency can be varied by changing the frequency division ratio. Reference numerals 17a, 17b, and 18 are amplifiers and equalizers of a conventional magnetic recording/reproducing device. Further, 20 and 21 are amplifiers and equalizers of a conventional magnetic recording/reproducing device. low pass filter 1
6 is applied to the recording head 2a via amplifiers 17a, 17b and an equalizer 18. The output of the reproduction head 2b is applied to the rectifier circuit 4a via the amplifier 20 and the equalizer 21, and
a output analog/digital converter (hereinafter referred to as A/D
The signal is digitally converted by a converter 22a and then applied to the microcomputer 12. Also, amplifier 1
The output of 7a is applied to the rectifier circuit 4b, and the rectifier circuit 4
The output of b is applied to the microcomputer 12 after being digitally converted by the A/D converter 22b. Further, the microcomputer 12 displays the oscillation frequency of the variable frequency oscillator on a display 23 consisting of a 7-segment light emitting element based on the setting value of the programmable divider 11, and also displays the output of the A/D converters 22a and 22b, that is, the rectifier circuits 4a and 4b.
The output level is read and displayed on a level meter 24. Note that 19 is a bias oscillator.

In another embodiment of the present invention configured as described above, the frequency synthesizer emits an output at a frequency determined by the frequency division ratio of the programmable divider 11. The oscillation frequency of the frequency synthesizer is divided by a divider 13, and the divided frequencies are combined by a bit generation ROM 14, converted to an analog signal by a D/A converter 15, and passed through a low-pass filter 16 to convert the frequency to an analog signal. A pseudo sine wave having the same frequency as the output frequency of the synthesizer is output, and this pseudo sine wave signal is amplified by amplifiers 17a and 17b, applied to recording head 2a via equalizer 18, and recorded on a magnetic tape. This recorded magnetic tape is reproduced by a reproduction head 2b, amplified by an amplifier 20, and equalized by an equalizer 21.The output of the equalizer 21 is then converted to a DC level by a rectifier circuit 4a. Further, the pseudo sine wave signal amplified by the amplifier 17a is converted to a DC level by the rectifier circuit 4b. The outputs of rectifier circuits 4a and 4b are A/D
It is converted into a digital signal by the converters 22a and 22b, read into the microcomputer 12, and displayed on the level meter 24,
Output of A/D converter 22a and A/D converter 22b
The output of On the other hand, the microcomputer 12 uses the specified programmable divider 1.
The frequency of the pseudo sine wave is varied by changing the frequency division ratio of 1, and the output levels of the rectifier circuits 4a and 4b converted into digital signals by the A/D converters 22a and 22b are read and compared. By this comparison, the output level of the rectifier circuit 4a is determined by the output level of the rectifier circuit 4b.
When the microcomputer 12 determines that the output level has decreased by 3 dB from the output level of the programmable divider 11, the microcomputer 12 stops changing the frequency division ratio of the programmable divider 11.

In this way, even when the oscillation frequency of the variable frequency oscillator is changed, the oscillation frequency of the variable frequency oscillator is displayed on the display 23 as it changes. Therefore, when the change in the oscillation frequency of the variable frequency oscillator is stopped, the oscillation frequency of the variable frequency oscillator at the time when the change is stopped is displayed on the display 23, and the maximum frequency characteristic is determined from the displayed frequency on the display 23. You can know the frequency.

In addition, the gain of the amplifier 17a is adjusted and the rectifier 4
It is also possible to see the frequency characteristics when the output level of the rectifier 4b is changed to -10 dB, -20 bB, etc. by setting the output level of the rectifier 4b to various values.

As explained above, according to the present invention, when the DC output level of the signal reproduced from the magnetic tape is lower by a predetermined value than the DC output level of the signal from the variable frequency oscillator recording on the magnetic tape, the variable frequency oscillator at that time Since the oscillation frequency is displayed on the display, the frequency characteristics of the magnetic tape can be seen and the magnetic tape can be selected according to the purpose of use. You can also set and check the bias oscillation and equalizer settings according to the user's purpose. Also, the recording head and playback head may become dirty.
It also has the effect of allowing early detection of malfunctions in the magnetic tape running system when it wears out.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention;
The figure is a block diagram of another embodiment of the present invention, and FIG. 3 is a flowchart for explaining the operation of another embodiment of the present invention. 1...Variable frequency oscillator, 2a and 2b...
Recording head and playback head, 4a and 4b...
... Rectifier circuit, 5 ... Comparator, 6 and 6' ... Display device, 7 ... Reference frequency oscillator, 8 ... Phase comparator, 9 and 16 ... Low pass filter, 10 ...
...Voltage controlled oscillator, 11... Programmable divider, 12... Microcomputer, 13...
...Minute period, 14...Bit generation ROM, 15...
D/A converter, 17a, 17b and 20...amplifier, 18 and 21...equalizer, 22a and 22b...A/D converter, 23...display unit,
24...Level meter.

Claims (1)

[Scope of utility model registration request] a variable frequency oscillator that oscillates at a constant output level for recording the output onto a magnetic tape via a recording head; a first rectifier circuit that converts the output of the variable frequency oscillator to a DC level; The second converts the regenerated output to DC level.
a rectifying circuit, a detecting means for detecting that the output level of the second rectifying circuit is lower than the output level of the first rectifying circuit by a predetermined value, and the variable frequency oscillator when the output of the detecting means is generated. 1. A magnetic recording and reproducing device comprising: a display device that displays at least the oscillation frequency of the magnetic recording and reproducing device.