JPS623484B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording circuit for a tape recorder that allows recording in an optimal state at all times.

In order to be able to record and play back the original sound as faithfully as possible with a tape recorder, it is generally possible to switch between recording conditions that match the type of tape being used, and select the conditions for each tape being used. are doing.

However, there are many types of tapes on the market, and even tapes of the same type have variations in performance depending on the individual tapes, so it is difficult to switch and obtain the optimum recording condition.

The present invention provides a recording circuit for a tape recorder that allows an optimum recording condition to be obtained while recording.

The present invention will be explained below with reference to the drawings. Reference numeral 1 denotes a tape for recording information, which is brought into contact with an erasing head 2, a recording head 3, and a reproducing head 4 in this order.

Reference numeral 5 denotes a recording circuit connected to the recording head 3, a recording amplifier 7 connected to a recording signal source 6 such as a microphone or a tuner, and a variable characteristic recording amplifier whose frequency characteristics change depending on the magnitude of the applied DC signal. 8, a bias trap 9 and a bias oscillation circuit 10. 11 is playback head 4
A reproducing circuit connected to the reproducing circuit includes a reproducing preamplifier 12 and a reproducing amplifier 13. A first integral holding circuit 15 is connected to the recording amplifier 7 via a band filter 16 that passes only the frequency signal to be compensated, and temporarily integrates and holds the recording signal to be recorded. A second integral holding circuit 17 is connected to the reproduction preamplifier 12 via a band filter 18 having the same pass frequency band as described above, and integrates and holds the reproduced signal reproduced by the reproduction head 4 in the same manner as described above.

19 is a comparison circuit that compares the outputs of the first integration holding circuit 15 and the second integration holding circuit 17; 20 is a gate circuit that gates the output of the comparison circuit 19; 21, 22, and 23 are the first and second integration holding circuits; This is a monostable multivibrator that controls the integral holding circuits 15 and 17 and the gate circuit 20. 24 is an astable multivibrator, and the generated pulse signal is
A part of it is directly applied to the first integral holding circuit 15 and the monostable multivibrator 21, and the rest of the generated pulse signal is applied to the second integral holding circuit 17, the monostable multivibrator 22, 23.

26 is a control circuit that controls the clock frequency of the frequency dividing circuit 25, and a rotation detector 27 that detects the rotation speed of a rotating body such as a flywheel that is related to the running speed of the tape 1; Waveform shaping circuit 28 that shapes the signal into a rectangular wave signal
and a PLL circuit 32. The PLL circuit 32
consists of a phase comparison circuit 30 and a voltage controlled oscillation circuit 31 to which the rectangular wave signal is applied to one input and the output of the frequency divider 29 is applied to the other input, respectively.

Next, the operation of the present invention will be explained. The recording signal from the recording signal source 6 (FIG. 2 D) is sent to the recording head 2 along with the bias signal from the bias oscillation circuit 10 via the recording amplifier 7 and the variable characteristic recording amplifier 8.
is added to Tape 1 and recorded on Tape 1. A part of the recording signal is applied to the first integration holding circuit 15 through the band filter 16, where it is integrated (FIG. 2(e)) and held (FIG. 2(f)).

On the other hand, the signal recorded on tape 1 is sent to playback head 4.
is played back by the playback preamplifier 12 and the playback amplifier 1.
3 and drives the speaker 14. The reproduction signal (FIG. 2 H) amplified by the reproduction preamplifier 12 is filtered by a band filter 18,
It is integrated by the second integral holding circuit 17 (Fig. 2),
It is retained (Fig. 2).

The outputs of the first integral holding circuit 15 and the second integral holding circuit 17 are then added to the comparing circuit 19 for comparison. If the distance between them is l and the tape speed is v, there is a time difference of Δt=l/v.

Therefore, after the recording signal is held in the first integral holding circuit 15, it is played back in the playback head 14 after Δt seconds.
It is necessary to compare the signal held in the second integral holding circuit 17.

Therefore, at the rising edge of the pulse signal of the astable multivibrator 24 (Fig. 2 C), the first integral holding circuit 1
5, and at the same time, the maximum peak value of the integrated value of the recording signal that arrives while the monostable multivibrator 21 is being inverted is held.

On the other hand, the second integral holding circuit 17 receives a frequency-divided pulse signal (FIG. 2-T) obtained by dividing the clock pulse signal (FIG. 2-B) from the control circuit 26 by the frequency dividing circuit 25.
is added.

Since this frequency-divided pulse signal has the same rising edge as the pulse signal from the astable multivibrator 24 and is set to have the same time as Δt, the second integral holding circuit 17 also receives the frequency-divided pulse signal. If the operation is performed at the falling edge of the signal, the operation start time of the second integral holding circuit 17 will be delayed by Δt, so that the reproduced signal at the same time as that held in the first integral holding circuit 15 will be transferred to the second integral holding circuit 17. is also retained.

At this time, the monostable multivibrator 22 is inverted by the frequency-divided pulse signal, and the maximum peak value of the integrated value of the reproduced signal within the same time as above is held, and is held in the first and second integral holding circuits 15 and 17. Compare the signals. Monostable multivibrator 22
When is restored, the monostable multivibrator 23 is inverted, turning on the gate circuit 20.
If there is a difference between the signals compared by the comparison circuit 19, a positive or negative signal is generated from the comparison circuit 19 (see FIG. 2), and the frequency characteristics of the variable characteristic recording amplifier 8 are changed to compensate.

Although the case where only the frequency signal is compensated has been described, if it is desired to compensate for several frequency signals, it is sufficient to provide a band filter and an integral holding circuit corresponding to each frequency to be compensated.

Although the case where the frequency characteristics of the variable characteristic amplifier 8 are compensated has been described above, the gain of the variable characteristic amplifier 8 can also be compensated.

As described above, in the recording circuit of the tape recorder of the present invention, the integral holding time of the second integral holding circuit is delayed from the integral holding time of the first integral holding circuit by approximately the tape running time between the recording head and the playback head. Since the two integral holding circuits integrate and hold the recorded signal integrated and held in the first integral holding circuit and the playback signal at the same time, the comparing circuit can compare the same signals. Therefore, even when recording music or the like whose characteristics change significantly over time, it can always be recorded in good condition.

[Brief explanation of the drawing]

FIG. 1 shows the recording circuit of the tape recorder of the present invention.
FIG. 2 is a signal waveform diagram of each part of the present invention. DESCRIPTION OF SYMBOLS 1...tape, 3...recording head, 4...playback head, 5 ...recording circuit, 8...variable characteristic amplifier, 11 ...playback circuit, 15...first integral holding circuit, 17...second Integral holding circuit, 19... Comparison circuit, 20... Gate circuit, 24... Astable multivibrator, 25... Frequency dividing circuit, 26 ... Control circuit.

Claims (1)

[Claims] 1. A first integral holding circuit that integrally holds a part of the recorded signal, and a second integral holding circuit that integrally holds a reproduced signal obtained by reproducing the recorded signal with a playback head.
a pulse signal generation circuit that generates a pulse signal that controls the holding time of the first integral holding circuit;
A frequency dividing circuit that forms a frequency divided signal that controls the holding time of the integral holding circuit, a comparison circuit that compares the signals integrally held in the first and second integral holding circuits, and a comparator circuit that is connected to the recording signal processing system. It consists of a compensation circuit whose characteristics are compensated by the output of the comparator circuit, and uses the frequency divided signal to delay the integral holding time of the second integral holding circuit, so that the recording signal is the same as the recording signal integrally held in the first integral holding circuit. 1. A recording circuit for a tape recorder, characterized in that a time playback signal is integrally held in a second integral holding circuit.