JPS61120377A - Tape recorder - Google Patents

Abstract

PURPOSE:To prevent AGC from operating owing to the changeover shock noise of a shorting type switch through simple constitution by connecting the shorting type switch in parallel to a capacitor for time constant setting which constitutes an automatic sound recording control circuit. CONSTITUTION:The output of a tuner 1 or microphone 2 is supplied to a sound recording amplifier 11 which incorporates an AGC function through coupling capacitors C2 and C3 and an input changeover switch S1-1, and the output of the sound recording amplifier 11 is superposed upon the output of a bias oscillation circuit 6 and applied to a sound recording head 5. The AGC means equipped with a current circuit 8 which serializes the output of an amplifier 7 and a variable impedance circuit 9 to which the output of this rectifying circuit 8 is inputted through a capacitor C1 and a resistance R constituting a time constant circuit is connected to the input and output of the amplifier 7 in said sound recording amplifier 11, and the shorting type switch S1-3 which is associated with said input changeover switch S1-1 is connected in parallel to the capacitor C1.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a tape recorder.

Conventional technology In recent years, tape recorders, especially cassettes with radio receivers,
High added value for tape recorders.

There is a shift towards higher functionality.

Generally, standard type tape recorders are equipped with an automatic recording level control circuit that controls the degree of amplification according to the output level of the recording amplifier.

As shown in Fig. 3, this automatic recording level control circuit inputs the output of the tuner 1 or microphone amplifier 2 to the recording amplifier 3, which has a built-in AGO function, via a manual selector switch 51-1, and outputs the output of the recording amplifier 3. was configured to be applied to RAD 6 for recording.

Problems to be Solved by the Invention However, in such an automatic recording level control circuit, when the manual selection switch 51-1 or the like is operated during recording, the current increases or decreases due to switching of the switch, or The drawback was that a pulse-like shock sound was generated by the charging and discharging of the capacitor, and the shock sound activated the automatic recording level control circuit, reducing the degree of enhancement for a preset period of time. For this reason, conventionally a manual changeover switch S is used as shown in Figure 3.
A muting circuit 4 that responds to a switch 51-2 that is linked to a switch 51-2 is installed on the input side of the recording amplifier 3, and muting is applied for a preset time when the switch is switched to prevent the AGC from operating due to shock noise. I was correcting it. In other words, the muting circuit 4 is connected to the switch 51-2.
When switching, the impedance is lowered for a preset time, and the input to the recording amplifier 3 is attenuated.

The present invention prevents the AGC from operating due to the switching sound of a switch with a simple structure without providing a conventional muting circuit.

Means for Solving the Problems The tape recorder of the present invention has a seven-toothing type switch connected in parallel to a time constant setting capacitor constituting an automatic recording level control circuit.

Function: In the tape recorder of the present invention, by connecting the fixed contacts of the shorting type switch to both ends of the AGC time constant setting capacitor, the time constant setting capacitor is always shorted when the switch is changed, and the switch is It is possible to prevent the phenomenon in which the AGC is activated by the shibok sound at the time of switching, and the degree of increase in power decreases during the one hour recovery period.

Embodiment FIG. 1 shows an embodiment of the tape recorder of the present invention, in which the output of the tuner 1 or the microphone amplifier 2 is connected to a built-in AGC function via coupling capacitors C2 and C3 and an input selector switch 51-1. The output of the recording amplifier 11 is superimposed on the output of the bias oscillation circuit 6 and applied to the recording head 5. Here, the recording amplifier 11 is an AGC circuit including a current circuit 8 that converts the output of the amplifier T into a direct current, and a variable impedance circuit 9 in which the output of the rectifier circuit is manually inputted via a capacitor C1 and a resistor R1 that constitute a time constant circuit. Means is connected between the input and output of the undef 0, and a shorting type switch 51-3 which is interlocked with the input changeover switch 51-1 is connected in parallel to the capacitor C1.

In the tape recorder of this embodiment, the input selector switches 51-1 and 51-3 are currently in the state a, and when switching to the state b during recording, the tuner 10 coupling capacitor 02 and the manual selector switch S1-' 1b through the variable impedance circuit 9. This charged current produces a pulse-like shuffling sound and lowers the gain of the recording amplifier 11. In other words, the pulse-like shock sound is amplified by the amplifier 7, rectified by the rectifier circuit 8, and C1
The impedance of the time variable impedance circuit 9 determined by R1 is lowered, and the overall gain reaching the recording head 6 is lowered. However, since the shorting type switch 51-3 that is linked to the input selector switches S and -1 has a structure in which the fixed contact pieces a and b are short-circuited during switching,
The capacitor C1 connected to the fixed contacts a and b of the switch 51-3 is short-circuited during switching, so that the variable impedance circuit 9 maintains a high impedance and does not lead to a decrease in the overall gain. At this time, the shock sound generated by the current charging the coupling capacitor C2 causes A
The time during which the GC circuit operates must be set shorter than the time during which the switches a and b of the switch 51-3 are short-circuited. Figure 2 shows the structure of a cutting type switch.

Figure 2 A shows a state in which the fixed contact piece a and the movable contact piece C are connected.
Figure 2 shows a state where movable contact piece C is connected to fixed contact pieces a and b, and Figure 2 c shows a state where movable contact piece C is connected to fixed contact pieces a and b.

As described above, in the present invention, the AGC circuit is activated by the shock sound generated by the input selector switch, and the amplification degree is temporarily lowered, which can easily prevent the recorded content from feeling strange. I can do the market. In addition, the same effect can be obtained not only in the manual changeover switch but also in other switches that produce shock sounds if the same connection is made. Furthermore, in addition to the shock sound, in the circuit shown in the embodiment, in the state before switching the switch, for example, when there is a sufficiently large input to the microphone amplifier 2 and the AGC is operating, the switch 51-1
When set to the tuner side, the overall gain remains low for a certain period of time, but such a case can be similarly prevented by the action of the switch 51-3.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the tape recorder of the present invention, FIG. 2 is an explanatory diagram of the operation of switches used in the tape recorder, and FIG. 3 is a block diagram of a conventional cheap recorder. 11...Recording amplifier, 7...Amplifier,
8... Rectifier circuit, C1... Capacitor for time constant setting, R... Resistor for time constant setting, 9.
...Variable impedance circuit, S...
Manual cut-off switch, 51-3... Shooting switch. Name of agent: Patent attorney Toshio Nakao and 1 Rochu 1st Cr Hitsu Ashika
・・l Physical resistance

Claims (1)

[Claims] A tape recorder characterized in that a shorting switch is connected in parallel to a time constant setting capacitor constituting an automatic recording level control circuit.