JPS6115489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC bias type tape recorder, and an object thereof is to improve frequency characteristics when recording a recording signal.

In conventional AC bias type tape recorders, the bias oscillation output is fixed to one preset value, but for this reason, if the frequency characteristics of the recording signal are in a wide range from low to high frequencies, The amplitude of the bias oscillation output is too small for low-frequency recording signals, increasing recording distortion on the tape, and the amplitude of the bias oscillation output is too large for high-frequency recording signals, causing the output of the magnetic head to decrease. As a result, the recording frequency characteristics no longer extend to high frequencies.

Therefore, the present invention aims to eliminate such conventional drawbacks. Specifically, the recording signal is frequency-divided, and the amplitude of the bias oscillation output is reduced for the divided high-frequency recording signal. The amplitude of the bias oscillation output is increased for low frequency recording signals, and the recording frequency characteristics as a whole are made good from low to high frequencies. I will explain it together.

In the figure, reference numeral 1 denotes a recording signal input terminal, into which, for example, a signal from a microphone or the like is input. 2,3
are low pass filter and high pass filter,
4 and 5 are recording equalizer circuits, 6 and 7 are mixing circuits for recording signals and bias oscillation output, 8 is an analog switch which is a time division circuit, 9 is a recording head, 10 is a magnetic tape, 11 is a recording bias oscillation circuit, 12 and 13 are semi-fixed resistors which are amplitude adjusters of the bias oscillation output, and 14 is a waveform shaping circuit for operating the analog switch 8 with the bias oscillation output.

In the above embodiment, the recording signal input to the input terminal 1 is frequency-divided into low and high frequencies by a low-pass filter 2 and a high-pass filter 3, and is supplied to mixing circuits 6 and 7 via recording equalizer circuits 4 and 5, respectively. Ru. The above mixing circuit 6,
7 has a semi-fixed resistor 1 from the bias oscillator 11
A bias oscillation output whose amplitude has been adjusted is supplied to the mixing circuit 6 through the circuits 2 and 13. In other words, a bias oscillation output with a large amplitude is supplied to the mixing circuit 6, and a bias oscillation output with a small amplitude is supplied to the mixing circuit 7. Therefore, in the mixing circuits 6 and 7, the bias oscillation output having the optimum amplitude for the band is mixed with each band-divided recording signal, and the outputs a and b are shown in FIG. 2 a and b. The waveform will look like this. These two waveform signals are time-divisionally supplied to the recording head 9 using the analog switch 8, and the magnetic tape 10 is supplied from the head 9 to the magnetic tape 10.
In this case, the analog switch 8 is controlled by a signal obtained by shaping the output of the bias oscillator 11 with the waveform shaping circuit 14 (the waveform of the output c of the waveform shaping circuit 14 is shown in FIG. 2c). Therefore, no beat occurs between the switching frequency of the analog switch 8 and the bias oscillation frequency. This is the same even if the switching frequency is set to an integral multiple of the bias oscillation frequency, and no beat generation occurs.

In the tape recorder of this embodiment, the bias oscillation output is made large in amplitude by the semi-fixed resistor 13 for recording signals in the low frequency range that pass through the low-pass filter 2, and the amplitude of the bias oscillation output in the high frequency range that passes through the bypass filter 3 is increased. For the recording signal, the bias oscillation output is made small in amplitude by the semi-fixed resistor 12, thereby increasing the output in the low frequency range and reducing distortion, and increasing the output in the high frequency range. Therefore, while the conventional single-bias method sets the bias as a compromise between the optimal bias conditions for both low and high frequencies, this embodiment makes it possible to set the appropriate bias for each band. As a result, the recording characteristics can be greatly improved. Needless to say, in the above embodiment, each filter is designed to cover the mid-range signal so that the original input signal can be obtained by mixing the outputs of the low-pass filter 2 and the bypass filter 3.

In the above embodiment, the recording signal is divided into two parts, but this may be divided into three parts: low range, middle range, and high range.
Furthermore, it may be divided into four or more. It is also possible to further improve the characteristics by increasing the number of band divisions.

As explained above, the tape recorder of the present invention divides the recording signal into bands according to the frequency, and mixes the divided recording signal with the bias oscillation output of the optimum amplitude. It is possible to achieve good results from low to high frequencies.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 a to 2 b are waveform diagrams of essential parts thereof. 1... Recording signal input terminal, 2... Low pass filter, 3... Bypass filter, 6, 7... Mixing circuit, 8... Analog switch, 9... Recording head, 10... Magnetic tape, 11... AC bias oscillator, 12, 13... Half Fixed resistor, 14... Waveform shaping circuit.

Claims (1)

[Claims] 1. In an AC bias type tape recorder equipped with a bias oscillator, there are multiple filters for dividing the recording signal into multiple bands according to the frequency, and a plurality of band-divided recording signals output from these filters. A mixing circuit that adjusts and mixes the bias oscillation output from the bias oscillator, and a time division circuit that time-divides the outputs from these mixing circuits and supplies them to the magnetic head, and a period of time division operation of the time division circuit. A tape recorder in which the cycle is set to match the cycle of the bias oscillation output or to an integral multiple thereof.