JPH0433522Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape recorder, and more particularly to a tape recorder that can automatically set the optimal recording bias current amount, recording equalizer amount, and tape sensitivity for the magnetic tape used.

The types of magnetic tape currently on the market are roughly divided into four types depending on the type of magnetic material used: LH (normal) tape, chrome tape, ferrichrome tape, and metal tape (hereinafter referred to as the main classification). ), each with different recording characteristics.

Therefore, the tape recorder side is designed so that four types of recording characteristics can be selected and set corresponding to these four types of magnetic tapes.

However, in reality, even if the magnetic tapes are of the same type, the magnetic properties of the magnetic materials are slightly different and the recording characteristics are different, so it has been substantially insufficient to be able to select from four types of recording characteristics.

Therefore, in conventional tape recorders, four types of recording characteristics can be roughly set based on the above main classification, and a means is added to the normally used manual tape selector switch to allow fine adjustment of the recording characteristics within a predetermined range at each setting position. By controlling this fine adjustment means with a microcomputer (hereinafter referred to as microcomputer), the recording characteristics are changed little by little and a test signal is recorded and reproduced on the magnetic tape each time (hereinafter referred to as recording/playback). The optimal recording characteristics were determined and automatically set for the magnetic tape used. To explain the operation of such an automatic recording characteristics adjustment device using the flowchart shown in Fig. 1, adjusting the recording characteristics of a tape recorder specifically involves adjusting the amount of recording bias current, recording equalizer, and recording sensitivity. Yes, the recording bias amount is first adjusted. The recording bias adjustment method has a standard frequency signal (400Hz to 1KHz) that is almost unaffected by bias changes, and a comparison frequency signal (5KHz to 10KHz) that is sensitive to bias changes. This adjusts the bias amount so that they match (the recording input level is the same for both the reference signal and comparison signal).
The bias adjustment range is ± with respect to the reference bias set with the manual tape selector before automatic adjustment.
It is about 20-30%. When the adjustment of the recording bias is completed, the adjustment is sequentially performed from the recording sensitivity to the recording equalizer.

The recording equalizer adjustment method uses the recording/playback output of the reference frequency signal mentioned above and the comparison frequency signal (10KHz to 15KHz).
The equalizer characteristics are adjusted so that the recording/reproducing output of the signal is approximately equal (the recording input level is the same for both the reference signal and comparison signal). By completing all of the above three adjustments, the recording characteristics are set to be optimal for the magnetic tape to be used.

Recently, magnetic tapes have appeared in which the optimum recording bias amount exceeds the bias adjustment range (±20 to 30%) mentioned above. Adjustment becomes impossible (ERROR) and the adjustment is completed (END) without sensitivity adjustment or equalizer adjustment, making automatic adjustment impossible. Expanding the bias adjustment range may be considered as a countermeasure to prevent such adjustment failure, but if the adjustment range is expanded any further, there is a risk that the operation of the bias oscillator will become unstable and the bias current will fluctuate.
For magnetic tapes that require an optimum recording bias that is significantly different from the reference value, even if the optimum recording bias is set, the recording characteristics may deteriorate.

In other words, with magnetic tape that requires a large amount of recording bias, even if recorded with the optimal recording bias, the high frequency characteristics (10KHz or more) will deteriorate, and the MOL (maximum output level) in the high frequency band will decrease significantly. On the other hand, with magnetic tapes that have a significantly lower recording bias, the distortion rate in the low and middle frequency bands worsens, so simply expanding the adjustment range of the recording bias amount risks deteriorating the recording characteristics of the magnetic tape. .

The present invention eliminates the above-mentioned drawbacks,
Its feature is that it is equipped with multiple variable time constant circuits that adjustably set the compensation amount of the recording equalizer provided corresponding to one of the above-mentioned main classifications of magnetic tape, and that the compensation amount adjustment range by each time constant circuit is different. If the recording bias amount cannot be set when recording characteristics are automatically adjusted,
To provide a tape recorder which enables automatic setting of recording characteristics by switching a predetermined variable time constant circuit to another variable time constant circuit and performing bias adjustment again.

The present invention will be explained below based on the illustrated embodiments.

FIG. 2 is a block diagram showing one embodiment of the recording characteristic automatic setting device of the present invention. 1 is a test signal oscillator, which outputs a reference frequency (400Hz) signal and a comparison frequency (10KHz) signal when adjusting the recording bias. , 400Hz signal and recording equalizer adjustment
Outputs 13KHz signal. 2 is a recording equalizer circuit, which is a variable time constant circuit 2 for normal (LH) tape.
a. Variable time constant circuit 2 for chrome (CrO) tape
b. Variable time constant circuit 2 for metal (MT) tape
It has C ₁ , 2C ₂ , and 2C ₃ . Among these, variable time constant circuits 2C ₁ , 2C ₂ , and 2C ₃ for MT tape have three types of variable time constant circuits, and one can be selected by a switch SW controlled by a microcomputer, which will be described later. is the main part of this invention.

In other words, the variable time constant circuit 2C ₁ is used to set an equalizer amount suitable for standard metal tape, and the variable time constant circuit 2C ₂ is used for bias adjustment based on the standard time constant circuit 2C ₁ even at the minimum bias variable value. When the amount of bias is too large and bias adjustment is impossible, it acts to increase the high frequency characteristics and enables bias adjustment. In addition, the variable time constant circuit _2C3 acts to attenuate the high frequency characteristics compared to the standard time constant circuit _2C1 , and when adjusting the bias, even at the maximum bias variable value, the bias is insufficient and the bias cannot be adjusted. Used in the case of Next, reference numerals 3a and 3b are tape selector switches, which select a variable time constant circuit suitable for the classification to which the magnetic tape to be used and a bias variable range are selected prior to automatic setting of recording characteristics.

4 is a recording bias oscillator, and the amount of bias current is controlled by a bias adjustment circuit 5 based on a command from a microcomputer MC. Note that the bias adjustment circuit 5
The bias variable range is selected in advance by the tape selector switch 3b according to the type of tape used. 6 and 7 are a recording magnetic head and a reproducing magnetic head, respectively, and 8 is a reproducing preamplifier. 9
is a mode selection switch, which is switched by a command from the microcomputer MC when recording characteristics are automatically set. In bias adjustment mode a, it is connected to a bias detection circuit BC, which will be described later. In sensitivity adjustment mode b and equalizer adjustment mode C, it is connected to a dedicated detection circuit (not shown). (not connected). The bias detection circuit BC includes a reference frequency signal separation circuit 10a, a comparison frequency signal separation circuit (10KHz) 10b, and each separation circuit 10a, 10.
Rectifier/integrator circuit 11 that converts the AC signal from b to DC
a, 11b and a comparator 12 that compares the levels of the reference frequency signal and the comparison frequency signal, and the comparison output from the comparator 12 is sent to the microcomputer MC.
is input as detection information. The microcomputer MC controls each of the detection circuits BC during automatic setting of recording characteristics.
The output frequency of the test signal oscillator 1 is changed to 0, and the variable time constant circuits 2a, 2b, 2C are input based on the input information such as adjustment possible/unadjustable information, tape drive machine operation information, automatic setting start information S, etc. ₁ ,
It controls the variable control P of 2C ₂ and 2C ₃ , the switching Q of the switch SW, the adjustment range control R of the bias adjustment circuit 5, the switching U of the mode changeover switch 9, and the control of the tape drive mechanism at the time of setting. Furthermore, this microcomputer
The MC may be a microcomputer that is normally used to control the operation of a tape recorder, or may be used in combination with the microcomputer.

The configuration is as described above, and its operation will be explained next.

(a) When using standard metal tape Automatic setting operation is started by setting the tape selector switches 3a and 3b to the MT position and giving the automatic setting start command S to the microcomputer. 2C ₁ ),
Set the mode selector switch 9 to bias detection mode a, and output the frequency signal _{1 for bias adjustment from the test signal oscillator 1} [reference frequency signal (400
Hz)], ₂ [Comparison frequency signal (10KHz) is output alternately. The ₁ + ₂ signal that has passed through the recording equalizer 2 is outputted from the bias oscillator 4 with a stepwise varying bias current (within the variable range set by the metal tape position) [Figure 3a] Bv added.
It is recorded on the magnetic tape T by the recording head 6 in the form ₁ + ₂ + Bv. This recorded signal is transmitted to the playback head 7.
is immediately reproduced and input to the bias detection circuit BC via the reproduction preamplifier 8 and switch ₉ .
₂ is separated, and the obtained ₁ and ₂ are input to the comparator 12 via rectifying and integrating circuits 11a and 11b, respectively, and the levels of ₁ and ₂ are compared. The output of the comparator 12 is input to the microcomputer MC, which detects the amount of bias when the output of the comparator 12 disappears, that is, when ₁ = ₂ , and sets the bias oscillator 4 using this as the optimum bias amount. When the setting of the bias amount is completed, the switch 9 is set to sensitivity detection mode B by a command from the microcomputer MC, and when the setting of the optimum sensitivity is completed, the switch 9 is switched to equalizer detection mode C, and the test signal oscillator 1 outputs a 400Hz signal ₁ , Comparison frequency signal for equalizer [13KHz] ₃ is output alternately, variable time constant circuit 2
₁ + 3 is amplified by the recording equalizer 2 in which _the amount of compensation changes stepwise as shown in Fig. 3b by _C1 .
Recording is performed on the magnetic tape T by the recording head 6 by applying a previously set bias current. recorded
₁ + ₃ is immediately reproduced by the reproduction head 7 and transmitted to an equalizer detection circuit (not shown) via the reproduction preamplifier 8, and is set to a compensation amount such that the signal levels of ₁ and ₂ match.

(b) In the case of a metal tape whose recording bias amount is outside the bias adjustable range If the tape selector switches 3a and 3b are set to the MT position and the automatic setting operation is started, the above signals ₁ and ₂ will not be adjusted during bias adjustment. The levels do not match, making it impossible to set the optimal bias. If the signal level of signal ₂ is smaller than the signal level of signal ₁ (that is, if even the minimum amount of bias within the bias adjustment range of this device results in excessive bias), the microcomputer MC detects this condition and sets the switch SW. Give a switching command, switch to E contact, select variable time constant circuit 2C ₂ , and perform bias adjustment again. Variable time constant circuit 2C ₂
Since the compensation characteristic of the recording equalizer 2 is a high frequency rising characteristic, the new bias adjustment changes this to a flat frequency characteristic. On the other hand, ₁
If the signal level of _{2 is larger than the signal level of 2} (in other words, the bias is insufficient even with the maximum bias amount by this device), select variable time constant circuit 2C ₃ with the switch SW and redo the bias adjustment. . The compensation characteristic of the recording equalizer 2 by the variable time constant circuit _2C3 is a high-frequency lowering characteristic, and these are flattened by a new bias adjustment. After completing the bias adjustment, perform sensitivity adjustment and equalizer adjustment (fine adjustment is performed using the newly selected variable time constant circuit) as in (a) below.

In this embodiment, the recording equalizer switching means of the present invention was used only for metal tapes, but it can also be applied to normal tapes and chrome tapes, if necessary.

Also, when performing a new bias adjustment after switching the variable time constant circuit in (b), the magnetic tape may be rewound to the previous bias adjustment start point before recording/playback operation, or the recording/playback operation may be performed as is. The operation may continue.

As described above, the present invention is configured such that the amount of recording bias current and the amount of compensation of the recording equalizer can be adjusted within a predetermined range depending on the type of magnetic tape, and the amount of recording bias current and the amount of compensation are adjusted to suit the recording characteristics of the magnetic tape used. In a tape recorder having an automatic adjustment device that provides a variable A switch is provided to select one of the time constant circuits, and if the optimum recording bias current amount of the magnetic tape used is not within the recording bias adjustment range given by the automatic adjustment device, the switch can be operated to select a variable time constant. After changing the circuit, the recording bias current amount is automatically adjusted once again, so the recording bias adjustment range can be substantially expanded, and the variable range of the bias oscillator can be forcibly expanded to reduce the oscillator. There is no risk of deteriorating the performance of the magnetic tape or damaging the original recording characteristics of the magnetic tape.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the operation of a conventional recording characteristic automatic adjustment circuit, FIG. 2 is a block diagram of the recording characteristic automatic adjustment circuit of the present invention, and FIGS. 3a and 3b are shown in FIG. FIG. 3 is a characteristic diagram showing a recording bias variable characteristic and a recording equalizer compensation characteristic of the circuit. Explanation of symbols, 1... Test signal oscillator, 2...
Recording equalizer, 3a, 3b... Tape selector switch, 4... Recording bias oscillator, 5... Bias control circuit, MC... Microcomputer, 2a, 2
b, 2C ₁ , 2C ₂ , 2C ₃ ... variable time constant circuit, SW
...Switch.

Claims (1)

[Scope of utility model registration request] In a tape recorder having an automatic adjustment device configured to be able to adjust the amount of recording bias current and the amount of compensation of a recording equalizer within a predetermined range for each type of magnetic tape, and providing the amount of recording bias current and compensation amount matching the recording characteristics of the magnetic tape used. , a plurality of variable time constant circuits that allow the compensation amount of the recording equalizer to be adjusted within a predetermined range corresponding to a predetermined type of magnetic tape and each having a different time constant variable range; and selecting one of the variable time constant circuits. If the optimum recording bias amount of the magnetic tape used is not within the recording bias adjustment range given by the automatic adjustment device, after changing the variable time constant circuit by operating the switch, a new A tape recorder that automatically adjusts the amount of recording bias current.