JPS6327766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder, and its purpose is to
The purpose is to easily set the optimum recording level that makes full use of the characteristics of the magnetic tape.

Currently, there are many types of magnetic tape on the market that have different magnetic properties such as coercive force and electromagnetic conversion properties.
These various magnetic tapes have different appropriate bias current values, and if recording is performed on a magnetic tape that is not suitable for a certain bias current value, the characteristics of that magnetic tape will not be fully exhibited. For this reason, conventional tape recorders are provided with a tape type changeover switch that changes the bias current value depending on the type of magnetic tape used. However, by simply switching the bias current using the tape type changeover switch, it is possible to only roughly set the bias current, and it is not possible to obtain the optimum bias current value for the magnetic tape used. Therefore, conventionally, tape recorders have been known that can finely adjust the bias current value and are equipped with a test signal oscillator for calibration so that the frequency characteristics can be calibrated to be flat while finely adjusting the bias current value. It is being According to this type of tape recorder, it is possible to adjust and set the optimum conditions for the magnetic tape used, so that the best recording and playback can be performed. However, the above adjustment is performed so that the display level of the level meter is at a predetermined value, and since this value differs depending on the type of magnetic tape, it is necessary to memorize the value corresponding to the magnetic tape being used. However, the adjustment was troublesome and there was a high possibility that the adjustment would be made incorrectly.

The present invention solves these conventional drawbacks, and one embodiment thereof will be described below with reference to the drawings. In the figure, 1 is a playback head for the stereo L channel, 2 is a playback equalizer amplifier,
3 is a flat amplifier, 4 is a changeover switch, and 5 is a playback signal output terminal.The output of the L channel detected by playback head 1 is amplified by playback equalizer amplifier 2 and flat amplifier 3, and the fixed contact a of changeover switch 4 is connected to the movable The signal is output to the playback signal output terminal 5 via contact c. Furthermore, 6 is a recording signal input terminal, 7 is a changeover switch, 8 is a variable resistor for adjusting the recording level, 9 is a flat amplifier, 10 is a recording amplifier, 11 is a recording head, 12 is a recording equalizer adjuster, 13 is a bias oscillator, 14 is a recording bias current regulator, and the recording signal input to the recording signal input terminal 6 is input to the fixed contact d, movable contact g, variable resistor 8, flat amplifier 9, and recording amplifier 10 of the changeover switch 7, The signal is superimposed with the bias signal from the bias oscillator 13 by the amplifier 10 and recorded on a magnetic tape by the recording head 11.

Reference numeral 15 denotes a tape type switching circuit whose output can be changed depending on whether the tape used is, for example, normal tape, chrome tape, or metal tape, and this output causes the reproduction equalizer amplifier 2 to set an appropriate time constant. The bias oscillator 13 is set to a standard bias current depending on the tape. The output of this tape type switching circuit 15 allows the level meter 16 to select normal tape, chrome tape,
One of the indicators 16a representing the metal tape lights up.

Next, a selection drive circuit for the level meter 16 will be explained. Reference numeral 17 designates a band pass filter that passes only a signal with a frequency 3f ₁ that is three times the reference signal f ₁ of the test oscillator, which will be described later. It is connected. The output of the bandpass filter 17 is inputted to the level meter amplifier 19 via the fixed contact h and the movable contact j of the changeover switch 18, and further inputted to the level meter 16. On the other hand 2
0 does not have a bandpass filter, etc., and directly inputs the signal appearing at the playback output terminal 5, and uses the level meter 16.
This is an amplifier for a level meter that drives. Note that the output of the reproduction head 21 for the R channel is applied to the other fixed terminal i of the changeover switch 18. Further, a changeover switch 22 interlocked with the changeover switch 18 increases the amplification degree of the level meter amplifier 19 by 30 dB when the fixed contact k is selected, compared to when the fixed contact l is selected in normal operation.

23 is a test oscillator that generates a reference signal f ₁ (for example, 400Hz), and its output is connected to the changeover switch 7.
is connected to the fixed terminal e. The changeover switch 24 selectively controls the output level of the test oscillator, and when the terminal is connected to the terminal m, the output level is 20 dB lower than the reference level, and when the terminal is connected to the terminal n, the output level is 10 dB higher than the reference level. Furthermore, 25 is a test oscillator that applies a reference signal f ₂ (for example, 8 KHz) to the fixed terminal f of the changeover switch 7, and its output level is set 20 dB lower than the reference level.

Next, the procedure for setting the bias current will be explained.

() Recording and playback of reference signal _f1 First, select the tape to be used with the tape type selection switch 15. Assuming that it is a chrome tape, the reproduction equalizer amplifier 2 and bias oscillator 13 are switched to standard settings for chrome tape, and the indicator 16a in the level meter 16 lights up, indicating B for the chrome tape.

Next, when the changeover switch 24 is closed and the fixed contact n is connected, and the changeover switches 4 and 7 are connected to the fixed contacts b and e, respectively, the output level of the reference signal f ₁ of the test oscillator 23 (set to +10 dB) is measured by the level meter. 16 L channel display section 16L. At this time, the variable resistor 8 for adjusting the recording level is adjusted so that the output level of the reference signal _f1 swings to the position of the indicator B.

In this state, the reference signal _f1 is sent to the recording head 1 via the flat amplifier 9 and the recording amplifier 10.
4 to record on magnetic tape. When the changeover switch 4 is switched to fixed terminal a and this magnetic tape is played back, the indicator B on the L channel display section 16L of the level meter 16 is transmitted from the playback equalizer amplifier 2, flat amplifier 3, changeover switch 4, and level meter amplifier 20. The level of the reference signal _f1 up to the position is displayed.

() Recording bias current adjustment using harmonic component _3f1 When the interlocking switches 18 and 22 are respectively switched to the fixed terminals h and k in the magnetic tape playback state, the level R of meter 16
The reproduction level of the third harmonic component 3f ₁ of the reference signal f ₁ recorded above is displayed on the channel display section 16R. At this time, the level meter amplifier 19
The amplification degree is set 30 dB higher than normal, so on the level meter 16, the display on the L channel display section (playback level of _f1 ) and the display on the R channel display section (playback level of 3fi) are equal. This means that the playback level, including high-frequency distortion components, has been flattened.

Therefore, while adjusting the recording bias current regulator 14 so that the display on the L channel display section and the display on the R channel display section are equal as described above, the reference signal _f1 of the recording tape is recorded and played back. Repeat.

() Recording Equalizer Adjustment Next, the changeover switch 24 is opened, and the changeover switch 7 is alternately switched to the fixed contacts e and f to record the reference signal f ₁ (400Hz) and reference signal f ₂ (8KHz) on the recording tape. At this time, both test oscillators 2
The output levels of Nos. 3 and 25 are both −20 dB and equal. Then, the changeover switch 4 is connected to the fixed contact a, the recording tape is played back, and the recording equalizer adjuster 15 is adjusted so that the playback levels at both frequencies are equal, that is, the frequency characteristics are flat.
Adjust and repeat recording and playback.

By following the steps above, the optimal characteristics of the recording bias current and recording equalizer compatible with chrome tape can be obtained. That is, according to the above-mentioned procedure, it is possible to flatten the frequency characteristics and perform bias adjustment that also takes into account the distortion rate, making it possible to obtain appropriate recording characteristics depending on the type of tape. Also, display the playback signal on the level meter,
In addition, by providing an indicator corresponding to the type of tape in this level meter, it is possible to adjust the playback signal so that the level meter lights up to the position indicated by the indicator,
Bias adjustment is very easy.

Next, a second embodiment of the present invention will be described.
Note that circuits that are the same as those in the embodiment shown in FIG. 1 are designated by the same numbers. This embodiment is characterized in that the test oscillator 23 is controlled by the tape type switching circuit 15, and the level of the output signal _f1 of the test oscillator 23 is changed depending on whether the tape is a normal tape, a chrome tape, or a metal tape. , if the variable resistor 8 for adjusting the recording level is set to the maximum position, the second
Recording is performed at the levels indicated by positions A, B, and C of the indicator 16a shown in the figure. Therefore,
In the procedure () in the description of the first embodiment above, it is no longer necessary to adjust the recording level adjustment variable resistor 8 when recording _f1 , that is, the standard level (indicator) of each tape is automatically adjusted during recording. Since recording is performed at positions A, B, and C),
The user only has to adjust the recording bias and recording equalizer of () and (), and the adjustment procedure can be simplified.

As is clear from the above embodiments, according to the present invention, not only the bias adjustment to simply flatten the frequency, but also the two By supplying the signal to the display section and displaying two output levels, it is possible to perform bias adjustment in consideration of the distortion factor. Further, since the level indicator is provided with a mark means (indicator) whose position changes depending on the output of the switch depending on the type of tape, adjustment can be made very easily even when the type of tape is different. Furthermore, this mark means can be used as a guide for the input level during normal recording, and is very convenient for recording at an appropriate level.

In addition, if the output level of the test oscillator is changed in conjunction with the change of the tape type selection switch, the test signal can be recorded at an appropriate level depending on the type of tape, reducing the number of steps required by the user. It is very convenient to be able to do this.

As described above, according to the present invention, it is possible to provide an excellent tape recorder in which the recording characteristics can be adjusted appropriately according to the type of tape, the display is clear, and the adjustment can be made in easy steps for the user. It is.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a main part of a tape recorder according to one embodiment of the present invention, FIG. 2 is a front view of a level meter, and FIG. 3 is a circuit diagram of a main part of another embodiment. 10... Recording amplifier, 12... Recording equalizer adjuster, 13... Bias oscillator, 14... Recording bias current regulator, 15... Tape type switching circuit, 16... Level meter, 16a... Indicator, 16L... ...L channel display section, 16R...
...R channel display section, 17... Bandpass filter, 23, 25... Test oscillator, 22, 24...
...Switch.

Claims (1)

[Claims] 1. A tape type selection switch that switches the recording bias current from a recording bias oscillator according to the type of magnetic tape, a recording bias current adjustment means that finely adjusts the recording bias current, and a time constant of a recording equalizer. a recording equalizer adjustment means for fine adjustment; a test oscillator that supplies a test signal for adjusting the recording bias current and the time constant of the recording equalizer; and a filter that passes only the third harmonic of the test signal; A level display having two display parts, and two of this level display
a switch means for displaying the level of the reproduced signal obtained by recording and reproducing the test signal on a magnetic tape and the output level of the filter, respectively, on one display section; and a switch means for instructing the level display to adjust the level according to the type of magnetic tape. A tape recorder comprising mark means whose position changes in response to switching of the tape type selection switch. 2. The tape recorder according to claim 1, wherein the output level of the test oscillator is switched in conjunction with switching of a tape type selection switch.