JPS60164964A - Tape recorder - Google Patents

Abstract

PURPOSE:To obtain a normal recording and reproducing characteristic by providing a sampling removing filter thereby controlling the compression and expansion characteristic of a noise reducing circuit by the level of an audio signal without being influenced by a sampling frequency signal from a digital audio equipment. CONSTITUTION:A signal inputted to an inut terminal 1 is inputted to a recording system noise reducing circuit 10 through a recording system sampling frequency removing filter 12. Output signals of the circuit 10 are recorded and reproduced by a tape head system 2, and reproduced signals are inputted to a reproducing system noise reducing circuit 11 through a reproducing system sampling frequency removing filter 13. Output signals of the circuit 11 are outputted from an output terminal 3. By providing the recording system sampling frequency signal removing filter 12 in the front stage of the circuit 10 and providing the reproducing system frequency signal removing filter 13 in the front stage of the circuit 11, input signals can be recorded and reproduced without subjected to the interference of sampling frequency signals, and normal noise reducing effect can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tape recorder equipped with a noise reduction circuit.

Conventional Structure and Problems In recent years, digitized recording sources, such as digital audio discs, have come to be used as recording sources for tape recorders. SN
Noise reduction circuits are very effective when recording high quality digital sources with conventional tape recorders.

A conventional tape recorder will be explained below.

FIG. 1 is a block diagram showing an example of a conventional tape recorder, in which a signal input to an input terminal 1 is supplied to an adder 6, and a variable pull no bus filter 4.
The signal is supplied to the adder 6 via the .

The output signal of the variable pull bypass filter 4 passes through the detector 5 and is input to the other input terminal of the adder 6 while controlling the cutoff frequency and attenuation amount of the variable pull bypass filter 4 . The signal obtained by adder 6 is
Recorded with tape head type 2.

will be played. The internally generated signal passes through the calculator 7 and reaches the output terminal 3, and at the same time is supplied to the variable noise filter 8. The output signal of the variable pull/pass filter 8 is supplied to the other input terminal of the subtracter 7 and simultaneously supplied to the detector 9. The output signal of the detector 9 controls the cutoff frequency and attenuation amount of the variable pull bypass filter 8. Above are the variable pull bypass filter 4, the detector 5. and adder 6 constitute ten recording system noise reduction circuits. Attenuator complete, variable pull bypass filter 8. The detector 9 constitutes an 11 reproduction system noise reduction circuit.

The operation of the conventional tape recorder configured as described above will be described below.

In the recording noise reduction circuit 10, a signal input to the input terminal 1 is divided into two paths. One is a first thread path that is directly input to the adder 6, and the other is a second thread path that is input to the adder 6 after passing through the variable bypass filter 4. When a low level signal is input to the input terminal 1, the level of the high frequency component at the output end of the adder 6 increases by the amount added via the second thread path. That is, the signal level of the high frequency component is compressed.

In the reproduction system noise reduction circuit 11, the high frequency component that has passed through the variable bypass filter 8 is subtracted from the output signal of the tape head system 2 in the subtracter 7, thereby reducing the signal input to the input terminal 1. Restore output terminal 3
to play. That is, the signal level of the high frequency component is expanded. The amount of the noise component generated by the tape head thread 2 that has passed through the barrier pull bypass filter 8 is removed by the subtracter 7, and the noise is reduced. The above operation is performed only when the signal level is low, and the outputs of the variable bypass filters 4 and 8 are reduced from a predetermined level or higher.

However, when a digital source is recorded with the conventional tape recorder, the sampled frequency signal has strong energy, so it may be mixed into the input signal or directly into the recording/writing circuit. Since the sampling frequency signal passes through the variable pull bypass filter 4, the sum of the sampling frequency signal components to the input signal is detected by the detector 6, and the variable pull bypass filter The output level of 4 becomes smaller, and the compression ratio becomes smaller. However, the sampling frequency is higher than the audible frequency band, and the tape head thread 2 cannot perform recording and playback. Therefore, since the expansion ratio of the reproduction system noise reduction circuit 11 is different from the compression ratio of the recording system noise reduction circuit 10, there is a drawback that the signal input to the input terminal 1 is not restored and output from the output terminal 3. Additionally, if a signal with no sampling frequency signal ml is recorded during recording, and the sampling frequency signal directly enters the playback noise reduction circuit 11 during playback, it may be difficult to restore the input signal or the signal may not function normally. The drawback was that the noise reduction effect could not be obtained.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems of the conventional technology and is capable of recording signals from digital audio equipment.

When playing back or placing digital audio equipment near a tape recorder, the input signal can be recorded and played back on tape without interference from the sampling frequency signal, and the normal noise reduction effect is maintained. The purpose is to provide a tape recorder that can be obtained.

Structure of the Invention The present invention is a tape recorder equipped with a noise reduction circuit having compression/expansion characteristics and a sampling frequency signal removal filter,
By configuring the sampling frequency signal removal filter to prevent the sampling frequency signal from being input to the noise reduction circuit, recording and playback can be performed without receiving interference from digital audio equipment; It is possible to obtain a normal noise reduction effect.

DESCRIPTION OF THE EMBODIMENTS FIG. 2 is a block diagram of a tape recorder in a first embodiment of the invention. In Fig. 2, 1 is an input terminal;
12 is a recording system sampling frequency removal filter; 10 is a recording system noise reduction circuit; 2 is a tape head system; 13 is a reproduction system sampling frequency removal filter; 11 is a reproduction system noise reduction circuit;
3 is an output terminal, and components having the same functions as those of the tape recorder shown in FIG. 1 are designated by the same reference numerals. The signal input to the input terminal 1 is input to the recording system noise reduction circuit 10 via the recording system sampling frequency removal filter 12.

The output signal of the recording system noise reduction circuit 10 is recorded and played back by the tape head system 2, and the playback signal passes through the playback system sampling frequency removal filter 13 and then is sent to the playback system noise reduction circuit 1.
1 is input. The output signal of the reproduction system noise reduction circuit 11 is output from the output terminal 3.

The operation of the tape recorder of this embodiment configured as described above will be explained below.

The input signal input to the input terminal 1 without being switched is input to the sampling signal removal filter 12, which removes the sampling frequency signal that is outside the audible frequency band and is harmful to the recording system noise reduction circuit 10, and the signal is input to the sampling signal removal filter 12. The signal is input to the system noise reduction circuit 10. Therefore, the recording noise reduction circuit 10 is controlled only by the audio signal, and the signal level is compressed. The output signal of the recording system noise reduction circuit 10 is recorded and recorded by the tape head system 2.
The signal is reproduced and input to the reproduction system sampling frequency signal removal filter 13. The tape head system 2 cannot record or reproduce the sampling frequency signal, but if a digital audio device is connected to the tape recorder, there is a possibility that the sampling frequency signal will directly enter the playback amplifier or the like. Even in such a case, since the sampling frequency signal is not input to the reproduction system noise reduction circuit 11, the reproduction system noise reduction circuit 11
is controlled only by the audio signal, and the signal level is expanded. Therefore, the audio signal inputted to the input terminal 1 is directly output from the output terminal 3, and at the same time, a normal noise reduction circuit is obtained by the recording system noise reduction circuit 10 and the reproduction system noise reduction circuit 11.

As described above, according to this embodiment, the recording system noise reduction circuit 1
By providing the recording system sampling frequency signal removal filter 12 before the reproduction system noise reduction circuit 11 and the reproduction system sampling frequency signal removal filter 13 before the reproduction system noise reduction circuit 11, the input signal can be removed without being interfered with by the sampling frequency signal. can be recorded and played back, and can obtain the normal noise-low sincerity effect.

In the embodiment shown in FIG. 2, when a signal from a digital audio disk is to be recorded and the digital audio disk is installed near a tape recorder, the recording system sampling frequency signal removal filter 12 and the reproduction system sampling The frequency signal removal filter 13 has a frequency of 44.1 kHz.
If the configuration is such that the frequency signal of z is excluded, the effects described in the previous embodiment can be obtained. 'Also, when recording signals from digital audio equipment that uses a rotating head such as a VTR, or when installing a digital audio equipment that uses a rotating head near a tape recorder, use the recording system sampling frequency signal removal filter. 12 and reproduction system sampling frequency signal removal filter 13 are 44.066 k)l
If the configuration is such that the frequency signal of z is excluded, the effects described in the previous embodiment can be obtained.

In the embodiment shown in Fig. 2, the recording system and playback system are explained separately, but in actual noise reduction circuits, the same circuit is often used for recording and playback by switching with a switch. The same effect can be obtained even if the same sampling frequency signal removal filters are used by switching them, and it is needless to say that this does not apply to the present invention.

Furthermore, since the reproduction system sampling frequency signal removal filter 13 of the embodiment shown in FIG. 2 generally cannot reproduce the sampling frequency signal, it may be omitted if there is no possibility that the sampling frequency signal will be mixed directly. It goes without saying that a tape recorder in which a sampling frequency signal removal filter is provided only in the recording system is also included in the invention.

Effects of the Invention As described above, according to the present invention, by providing the sampling removal filter, the noise reduction circuit can perform compression according to the level of the audio signal without being influenced by the sampling frequency signal from the digital audio equipment. - Since the expansion characteristics are controlled, it is possible to realize a tape recorder that provides normal recording/playback characteristics and a normal noise reduction circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional tape recorder, and FIG. 2 is a block diagram of a tape recorder according to an embodiment of the present invention. 1. Input terminal, 2.. Tape head system, 3.. Output terminal, 10.. Recording system noise reduction circuit, 11.
. . . Reproduction string noise reduction circuit, 12 . . . Recording system sampling frequency signal removal filter, 13 . . . Reproduction system sampling frequency signal removal filter.

Claims (3)

[Claims] (1) A noise reduction circuit that has compression characteristics during recording and expansion characteristics during playback, and is provided in the previous stage of the noise reduction circuit to remove sampling frequency signals of digital audio equipment that are mixed into this noise reduction circuit. A tape recorder comprising a sampling frequency signal removal filter. (2) The sampling frequency signal removal filter is 44.1k
The cheap recorder according to claim (1)m, characterized in that it is configured to remove the H2 signal component. (3) Sampling frequency signal removal filter, 44.056
The tape recorder according to claim 1, characterized in that the tape recorder is configured to exclude kl(+ signal components).