JPS61261803A - Fm audio recording device - Google Patents

Abstract

PURPOSE:To reduce hop noises by providing a recording amplifier circuit which raising the recording current of an overlap part of audio signal tracks of an FM audio recording and reproducing device above a normal recording current level and a circuit which gives the current level a specific time constant and controls the high current to the constant current. CONSTITUTION:The FM audio recording and reproducing device is equipped with a recording current control circuit 12 which raises the recording current above the normal recording level with the specific time constant in the overwriting time 20 from a point where a different audio signal 16 is overwritten on a recorded track pattern 14 to a point 19 where a flying erase head operates and a circuit 11 which performs recording amplification after an audio signal input 21 is FM-modulated. Thus, the current of the overwrite part is controlled to suppress an abrupt change of an audio reproduction envelope near a clean join and then prevent hop noises from being generated, thereby perform smooth audio clean join recording.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an FM audio recording circuit for a magnetic recording/reproducing device.

Prior Art 2 - In recent years, demand for video tape recorders in the consumer field has been increasing as they have been equipped with FM audio to improve sound quality. Also, in the field of special equipment, the need for FM audio editing machines has made it necessary to connect FM audio.

An example of a conventional FM audio recording circuit will be described with reference to the following drawings.

FIG. 4 shows a block diagram of conventional FM audio. In FIG. 4, 1 is an audio input, 2 is a buffer, and 3 is a VCA circuit for current-voltage conversion. 4 is a BPF circuit that detects the signal level and removes unnecessary signals.

6 is RMS amplification, which detects and amplifies the effective value of the signal input.

3 and 4.5 are collectively referred to as db× (registered trademark), which is the encoding circuit of the system. 6 is a pre-amp circuit that boosts the high frequency range, 7 is an FM modulation circuit, 8 is a recording amplification circuit, and 9 is an audio head.

The conventional FM audio 3 channel configured as described above.

The operation of the recording circuit will be explained below.

First, the signal flow of the FM audio recording circuit is as follows.
From voice input 1 through buffer circuit 2, d of 3.4.5
After the audio level is linearly compressed and encoded in decibels using the bx system, the pre-emphasis circuit 6 boosts the high range, reduces noise, and improves the breathing phenomenon. The signal is subjected to FM modulation by an FM modulation circuit 7, passes through a recording amplifier circuit for providing a recording current to be recorded on the tape, and is supplied to an audio head 9 via a rotary transformer 22.

In the conventional configuration, the recording current is constant in the overwritten recording portion when audio signals are connected because there is only a recording amplifier circuit.

Problems to be Solved by the Invention However, in the above configuration, when audio signals are connected, the recording current in the overwritten portion of the audio signal track is constant, so when that portion is played back, the audio envelope level may suddenly change. Therefore, there is a problem in that pop noise occurs and its level is high.

Means for Solving the Problems In view of the problems mentioned above, the present invention provides a recording amplifier circuit that makes the recording current of the overwritten portion of the audio signal track at the time of splicing higher than the normal recording current, and a recording amplifier circuit of the circuit. It is equipped with a recording current control circuit that reduces the current from a high current to a certain constant current with a specific time constant.

According to the above-described structure, the present invention reduces the recording current of the overwritten portion of the audio signal track from a high current to a certain constant current with a specific time constant, so that when reproducing that portion, Changes in the audio playback envelope level can be minimized and the pop noise level can be reduced.

EMBODIMENTS Below, an FM audio recording circuit according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an FM audio recorder/recorder amplifying section according to an embodiment of the present invention. 10 is an FM modulation circuit, 11 is a recording amplifier circuit, 12 is a recording current control circuit, 13
is the audio head.

FIG. 2 shows an audio track pattern during insert editing when a rotating cylinder is provided with an audio head and a flying eraser that can erase audio tracks. 14 is a recorded audio track pattern, 16 is another audio signal track during insert editing, 15 is an overwritten portion of 14 and 16, and 17 is a portion where the flying erase head is operated. 18 is an editing frame entrance.

The feature of this embodiment is that a recording current control circuit is used to flow the recording current through the 11 recording amplifier circuits from the overwritten portion of the audio track 15 to the point 17 in FIG. I made it work.

As described above, by multiplexing the recording current for the overwritten portion of the audio track with a time constant, sudden changes in the audio reproduction device/bellow near the joint can be suppressed, thereby preventing the occurrence of hop noise and smoothing the recording current. It is possible to repeat the voice over and over again.

Effects of the Invention As described above, the present invention provides a recording amplifier circuit that makes the recording current of the overwritten portion of the audio signal track higher than the normal recording current level, and a constant current that reduces the recording current level of the circuit from a high current level. By providing a specific time constant such that

[Brief explanation of drawings]

Fig. 1 is a block diagram of an FM audio recording circuit according to an embodiment of the present invention, Fig. 2 is an audio track pattern diagram of an embodiment of the present invention, and Fig. 3 is a recording current waveform diagram of the overlapping portion of Fig. 2. , FIG. 4 is a block diagram of a conventional FM audio recording circuit. 1o...FM modulation circuit, 11...recording amplifier circuit, 12...recording current control circuit, 13...audio head.

Claims (1)

[Claims] In a magnetic recording/reproducing device using a helical scan method, in which a rotating cylinder is provided with an audio-dedicated head and an audio track is formed on a magnetic tape, when another audio is continuously recorded on a track where an audio signal has already been recorded, the above-mentioned and later-mentioned A recording amplifier circuit that makes the overlapping portion of two audio signal tracks higher than the normal audio recording current level, and a recording current level of the circuit that has a specific time constant and decreases from a high current to a certain constant current. An FM audio recording circuit characterized by comprising a recording current control circuit that controls the current.