JPS5914902Y2 - Tape recorder bias adjustment display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bias adjustment display device in a tape recorder.

In order to obtain the best performance using any of the various commercially available tapes in the above tape recorder,
It is necessary to adjust the bias current to suit each tape.

In particular, for cassette tapes, normal type (γ-Fe2
There are quite a number of types of tape (tape whose main magnetic material is O3), and the electromagnetic conversion characteristics differ from tape to tape, or even from lot to lot, even for the same type of tape, and if used as is, each tape will have different In particular, there is a problem in that the frequency characteristics change.

At this time, by adjusting the bias to be appropriate for each tape, the frequency characteristics can be leveled out, and the best condition can be achieved in terms of distortion, etc.

The simplest method for adjusting the bias of a tape recorder is simply a knob that adjusts the output of the bias oscillator.

This is done by the user in advance with the tape they are using.
This involves recording and playing back music or sounds, listening to the reproduced sound, determining whether the frequency characteristics have changed compared to the original sound, and making adjustments.

However, this method has the disadvantage that it depends on the user's sense and cannot be adjusted accurately without skill.

In addition, a tape recorder is equipped with an oscillator for a mid-frequency range and an oscillator for a high-frequency range, and when adjusting the bias, the outputs of the two oscillators are sequentially recorded one by one by switching between both total oscillators using a switch. There is a method of reading the reproduced output with a level meter and adjusting the bias so that the reproduced signals output from the two oscillators are the same.

According to this method, relatively accurate adjustment is possible, but if you are not very skilled, you need to check the frequency of the reproduced signal of the output of the oscillator switched by the switch, and check its level before adjusting the bias adjustment knob. The problem is that I can't decide what to do.

Also, 1. The outputs of two high-frequency and low-frequency oscillators installed at There is a method in which the low frequency signal is divided into two signals, each level is indicated by two meters, and the bias is adjusted so that the two meters indicate the same signal.

However, this method also has the disadvantage that if you are not used to it, you will be confused about the meaning of the readings on the two meters, and you will not be able to decide what to do next with bias adjustment.

In view of the above problems, the present invention provides a bias adjustment display device that allows bias adjustment to be performed more easily and accurately.

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

In FIG. 1, 1 is a magnetic tape running in the direction of the arrow.

2 is a recording head, 3 is a playback head, 4 is a recording amplifier, 5
is a first oscillator that oscillates a mid-range frequency, and 6 is a second oscillator that oscillates a high-range frequency; these two oscillators 5,
The output levels of 6 are equal and mixed by recording amplifier 4,
Recording is performed on the magnetic tape 1 by the recording head 2.

7 is a bias oscillator whose output is variable, and the variable knob is attached to the surface of the tape recorder body as a bias adjustment knob.

8 is a regenerative amplifier, 9 is a first bandpass filter corresponding to the output frequency of the first oscillator 5, 10 is a second bandpass filter corresponding to the output frequency of the second oscillator 6, 11 and 1.
Reference numeral 2 designates first and second level comparators, which compare the output levels of the first bandpass filter 9 and the second bandpass filter 10; When the output level is higher than the output level of the second bandpass filter 10 by a preset level or more, an output signal is generated.
0 is higher than the output level of the first bandpass filter 9 by a preset level or more, an output signal is generated.

Reference numeral 13 denotes a display drive circuit that drives one of the displays 14, 15 and 16 using the outputs of the first and second bandpass filters 9 and 10.

In this case, the output a of the display drive circuit 13 causes the display 1 to
4 is driven, the output C drives the display 16, and the output C drives the display 15.

In the above configuration, the mixed signal of two frequencies recorded by the recording head 2 passes through the playback head 3 and the playback amplifier 8 and is applied to the first and second bandpass filters 9 and 10, and from the first bandpass filter 9, A signal with a middle frequency 11 and a signal with a high frequency 12 are output from the second bandpass filter 10, respectively.

This output f1. As for f2, the reproduction output changes as shown in FIG. 4A by changing the bias current.

These two outputs are sent to the first and second level comparators 11 and 12.
is input.

The first level comparator 11 has a frequency of 11 as described above.
When the output of the frequency 12 is higher than the output of the frequency 12 by a preset level a2, an output is generated, and as the bias current changes, the output is output as shown in b of FIG. 4B.

On the other hand, the second level comparator 12 determines that the output of frequency 12 is higher than the output of frequency 10 at a preset level a1.
When the bias current is high, an output is generated, and as the bias current changes, an output is generated as shown in a of FIG. 4B.

The outputs of the first and second bandpass filters 11.12 are input to the display drive circuit 13, and a circuit within this circuit generates an output only when there is no output in either the first or second bandpass filters 11.12. The outputs a, l), and c are applied to the display devices 16, 14, and 15 from the display drive circuit 13 to display the bias adjustment state.

In other words, when the bias is shallow (less), the high frequency range rises, and 12 becomes higher than the preset level, and the output from the second level comparator 12 appears, and a
is output and the display 14 lights up.

If the bias is deep (large), the high range will be reduced and f2 to 11 will be louder than the preset level,
An output appears from the first level comparator 11, which becomes the output b, and the display 16 lights up.

When the bias is within a preset range for a proper value, the first and second level comparators 11.1
There is no output for both 2 and 2, and as a result, the output of C is output from the display drive circuit 13, and the display 15 lights up to indicate that the adjustment is correct.

2 and 3 show other embodiments of the displays 14-16.

FIG. 2 shows three frequency characteristic curves 17, 18, and 19, and one of the curves is displayed as a luminescent display depending on the degree of bias.

That is, when the bias is shallow, only curve 17 emits light, when the bias is deep, only curve 19 emits light, and when the bias is within a preset range of proper values, curve 18 emits light.

In addition, in Fig. 3, indicators 21, 22, and 23 are installed around the bias adjustment knob 20, and when the bias is within a preset range for an appropriate value, the indicator 21 emits light. However, when the bias is shallow, an arrow-shaped indicator 2 directs the knob 20 in the direction of rotation to deepen the bias.
3 emits light, and conversely, when the bias is deep, an arrow-shaped indicator 22 that instructs the rotation direction of the knob 20 to make the bias shallower emits light.

By forming the display into a shape that indicates the appropriate direction for the knob 20, adjustment becomes easier.

As explained above, according to the present invention, bias adjustment can be easily performed by driving different display devices depending on the bias state (shallow, deep, appropriate) and displaying the state. In particular, bias adjustment can be made easier by forming the display device in a shape that indicates the respective frequency characteristics or in a shape that directs the knob of the bias adjustment device in an appropriate adjustment direction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a bias adjustment display device for a tape recorder according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing other embodiments of the display portion of the same device, and FIG. 4A
, B is a characteristic diagram of reproduction output with respect to bias current and a diagram showing each output waveform. 1...magnetic tape, 2...recording head, 3...playback head, 4...recording amplifier, 5...middle range an oscillator that oscillates a frequency, 6
......Oscillator that oscillates high frequency, 7...
... Bias oscillator, 8 ... Regenerative amplifier, 9
, 10...Band filter, 11.12...
...Level comparator, 13...Display drive circuit,
14.15°16...Indicator.

Claims (3)

[Scope of utility model registration request] (1) A first oscillator connected to a recording amplifier and a first
a second oscillator that oscillates at a higher frequency than the oscillator;
a recording bias current adjustment device; a first filter that receives the output of the regenerative amplifier and corresponds to the oscillation frequency of the first oscillator; a second filter that corresponds to the oscillation frequency of the second oscillator; a first comparator that compares the output levels of the filter and the second filter and generates an output signal when the level of the first filter is higher than the level of the second filter by a preset level or more; a second comparison that compares the output levels of the first filter and the second filter and generates an output signal when the level of the second filter is higher than the level of the first filter by a preset level or more; vessel, and the first and second
The output of the comparator is manually operated, and when the output signal of the first comparator is detected, the first display is driven; when the output signal of the second comparator is detected, the second display is driven; A bias adjustment display device for a tape recorder, comprising a display drive unit that drives a third display when there are no output signals from both the first comparator and the second comparator. (2) The bias adjustment display device for a tape recorder according to claim 1, wherein the first, second, and third indicators each have a shape that indicates a frequency characteristic. (3) Utility model registration claim 1, characterized in that the first, second, and third indicators are shaped and arranged to indicate the bias adjustment knob in the proper adjustment direction. Bias adjustment display device for the tape recorder described.