JPS6224325Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a recording/reproducing device, and in particular sets the frequency characteristics of the recording amplification system according to the magnetic characteristics of the magnetic tape used, so that the overall frequency characteristics of the recording and reproduction amplification systems can be adjusted to the audible frequency. It is designed to be even across the bandwidth, and its control is suitable for automation.

A simple block diagram of the recording and playback system of a conventional recording/playback device is shown in Figure 1, and the recording signal input from the recording terminal _T1 in the recording system is as shown in Figure 2a. A bias current is further superimposed on the recording head 2 onto the magnetic tape 3 via the recording amplifier circuit 1 which has the required frequency characteristics such that the required level is raised in the low frequency range and the required peaking characteristic is given in the high frequency range. The reproduced signal recorded and reproduced by the reproduction head 4 in the reproduction system is taken out from the reproduction terminal _T2 via the reproduction amplifier circuit 5 having standardized frequency characteristics. Ideally, the overall frequency characteristics of this recording and playback system should be flat in the audible frequency band, but for example, the magnetic properties of magnetic tapes, which are broadly classified into iron oxide tapes, chrome tapes, and metal tapes, Characteristics vary greatly depending on the type, and even within the same type, making it difficult to obtain the ideal overall frequency characteristics for all magnetic tapes. be.

The present invention eliminates such conventional drawbacks,
To explain this in detail with reference to the drawings, FIG. 3 shows a block diagram of an embodiment of the present invention, which is equipped with an independent recording head 2 and a reproducing head 4, and can simultaneously reproduce signals recorded on a magnetic tape 3. This system is applied to tape recorders to automatically set the frequency characteristics of the recording amplification system.

Switches S ₁ and S ₂ of the recording and playback systems are usually located at the dotted line positions in the diagram, and recording signals such as audio are applied to the recording terminal T ₁ , and playback signals are applied to other equipment from the playback terminal T ₂ . However, in the automatic frequency response setting mode,
It is switched to the solid line position in the figure. The signal supplying means 6 normally outputs first to fourth signals having mutually different required frequencies and the same level obtained by dividing the oscillation frequency of the crystal oscillator ₆₁ by a required frequency divider ₆₂ , for example. The signal is supplied to the first correction circuit 7 according to the selection of analog switches A61 to A64. The first to third signals are for controlling the frequency characteristics in the present invention, and the first signal is for mid-range frequency ₁ , the second signal is for controlling frequency characteristics in the present invention, and
and the third signal have high frequency ₂ and
_{The fourth} signal is for the final check described later and is set to a mid-range frequency of ₄ , but in the example, ₁ , ₂ , ₃ and ₄ are selected to be 400Hz, 10kHz, 20kHz and 2kHz, respectively. ing. Further, in this embodiment, a case will be described in which the overall frequency characteristic is such that the high frequency region is lowered as shown in the pattern shown in FIG. 2b.

FIG. 4a shows an embodiment of the first correction circuit 7, in which the output terminal of the operational amplifier ₇₁ to which the signal from the signal supply means is applied to the non-inverting input terminal (+) is inverted via the resistor _R7 . Connected to the input terminal (-), and between the connection point of this inverting input terminal (-) and resistor _R7 and ground G, three sets of circuits each having a capacitor, a resistor, and an analog switch connected in series are connected to each other. connected in parallel. The capacitance values and resistance R ₇₁ of these capacitors C ₇₁ , C ₇₂ and C ₇₃ ,
Each resistance value of R ₇₂ and R ₇₃ is a normally open analog switch.
In response to the selection of a desired combination of _A71 to _A73 , the first correction circuit 7 converts the first signal of frequency 1, the second signal of frequency ₂ , and the second signal of frequency ₃ to the first signal of frequency 1, as shown in FIG. _2c . It is set to give eight sets of different frequency characteristics so that the level of the region formed between the signal No. 3 and the signal No. 3 changes in the direction of increasing the level.

Furthermore, FIG. 4b shows an embodiment of the second correction circuit 8, which consists of three sets of circuits each connected in series with a resistor _R8 , an analog switch, and a capacitor in parallel with each other. connected to
An operational amplifier 7 ₁ formed of an RC parallel circuit and forming a first correction circuit 7 in the previous stage at one connection point.
output terminal is connected.

The respective capacitance values of this resistor R ₈ and capacitors C ₈₁ , C ₈₂ and C ₈₃ are determined by the second correction circuit 8 according to the selection of the required combination of normally open analog switches A ₈₁ to A ₈₃ as shown in FIG. In the region formed between the second signal of frequency ₂ and the third signal of frequency ₃ , the slope is set in the direction in which the level of the third signal becomes higher than the level of the second signal. 8 to change
set to provide a set of different frequency characteristics.

The other connection point of this RC parallel circuit is amplifier circuit 1
connected to. The amplifier circuit 1 is constructed using the required operational amplifiers, etc., and as shown in FIG. A required bias current is further superimposed via a well-known bias trap circuit and recorded on the magnetic tape 3 by the recording head 2.

The signal recorded on the magnetic tape 3 is transferred to the playback head 4.
The reproduced borrowed symbol is simultaneously reproduced by a reproducing amplifier circuit 5 having standardized frequency characteristics, and further converted into a digital signal with a required number of bits by an A/D converter 9, and a computer circuit 10 forming a control means. is input as measurement data. The computer circuit 10 controls the analog switch of the signal supply means 6 according to a preset program, and also controls the first correction circuit 7 and the second correction circuit by comparing the calculation result of the measured data with the data stored in advance.
The analog switch of the correction circuit 8 is controlled.

The operation of the device of the present invention having the above configuration will be explained using FIG. When the automatic setting mode is selected, the computer circuit 10 sequentially closes the analog switches A ₆₁ , A ₆₂ and A ₆₃ of the signal supply means 6 for the required time from the initial state in which each analog switch is open. , the second and third signals are recorded on the magnetic tape 3, and their reproduction output levels d ₁ , d ₂ and d ₃ are sequentially captured as measurement data, as shown in FIG.
When the data shown in is obtained, first, the reproduction output levels d ₂ and d ₃ of the second signal and the third signal are compared, and the difference data △d ₁ is compared with the stored data, and the second correction is performed. Set the analog switches _A81 to _A83 of circuit 8 to one of the eight combinations as shown in Figure 5b.
Correction is performed so that the reproduction output level d ₃ becomes equal to d ₂ as shown in FIG. Next, the first signal and the second signal
The reproduction output levels d ₁ and d ₂ of the signals are compared, and the analog switches A ₇₁ to A ₇₃ of the first correction circuit 7 are compared with the difference data Δd ₂ and the stored data.
is set to one of eight combinations and the fifth
As shown in Figure c, correction is made so that the reproduction output level of the area formed between the second signal and the third signal is equal to the reproduction output level _d1 , and the overall recording and reproduction amplification system is Although the frequency characteristics are assumed to be flat, as a final check, the above-mentioned corrected fourth signal is recorded and reproduced, and measurement data of its reproduction output level _d4 is taken in. If the difference data between the reproduction output levels _d1 and _d4 of the first signal and the fourth signal is equal to or greater than the specified value, the above-mentioned correction is performed again, or the bias value of the bias current is changed and re-correction is performed. will be carried out.

It should be noted that the measurement data of the reproduction output levels of the first, second and third signals is, for example, as shown in Fig. 5d.
There are some exceptional magnetic tapes that do not take the pattern shown in Figure 5b, but for such magnetic tapes, the measured data can be corrected to the pattern shown in Figure 5b by changing the bias value of the bias current. The correction may be performed by the correction circuit 7 of No. 1.

In the above-described embodiment, the first correction circuit 7 and the second correction circuit 8 each include three sets of analog switches to provide eight types of frequency characteristics, but the invention is not limited to this, and the number of analog switches etc. can be increased to provide even more. By providing many frequency characteristics, more detailed correction can be made.

Furthermore, even if the pattern of the overall frequency characteristics is opposite to that shown in Fig. 2b and the high frequency range rises, it is of course possible to perform the same correction by providing first and second correction circuits that respectively provide the required frequency characteristics. .

Furthermore, the correction methods of the first and second correction circuits are not limited to the embodiments.
After adjusting the second correction circuit based on the reproduction level of the first and third signals, the first correction circuit may be adjusted based on the reproduction level of the first and third signals. The same correction can be made even if the first correction circuit is adjusted based on the reproduction level of the second signal and then the second correction circuit is adjusted based on the reproduction level of the second and third signals. Of course.

According to the device of the present invention, it is possible to easily bring the overall frequency characteristics of the recording and reproduction amplification system to an ideal state according to the magnetic characteristics of the magnetic tape used, regardless of the type of magnetic tape used as the recording medium. Not only is it possible, but it is also easy to automate the control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the conventional example, FIGS. 2 a to d are frequency characteristic diagrams for explaining the device of the present invention, FIG. 3 is a block diagram of an embodiment of the device of the present invention, and FIG. 4 5a and 5b show circuit diagrams of one embodiment of the first and second correction circuits, respectively, and FIGS. 5a to 5d show diagrams for explaining the operation of the device of the present invention, respectively. 3... Recording medium, 6... Signal supply means, 7... First correction circuit, 8... Second correction circuit, 10... Control means, ₁ , ₂ , ₃ ... Frequencies of first, second and third signals .

Claims (1)

[Claims for Utility Model Registration] A first signal having a desired frequency in the middle range of the audible frequency band, a second signal having a high frequency in the band, and a second signal within the band. signal supply means for outputting third signals each having a higher frequency at the same level; a second correction circuit that is controlled to change a frequency characteristic that gradually increases or gradually decreases over substantially the entire frequency region formed between the signal and the signal, and substantially changes the mutual signal level difference within the frequency region. a recording amplification system including a first correction circuit that is controlled to change the level of the signal in the frequency domain with respect to the level of the first signal; a regenerative amplification system that outputs reproduced signals of the first, second, and third signals; and a control means that receives the reproduced signals and generates a desired control output; The second correction circuit is controlled in a direction to eliminate the level difference between these reproduced signals based on the reproduced signal of the third signal, and the reproduced signal of the first signal and the second or third signal is controlled. The recording/reproducing device is configured to control the first correction circuit in a direction to bring the level of the reproduced signal of the second or third signal closer to the level of the reproduced signal of the first signal based on the reproduction signal. Device.