JPS6336778Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a tape recorder in which a windscreen is moved and placed on the sound reporting surface of a built-in microphone in conjunction with the switching operation of a switching button of a microphone sensitivity switching circuit. The present invention relates to a microphone sensitivity switching device.

In a conventional tape recorder, as shown in FIG.
is input and amplified. Next, when the microphone input reaches a certain value, for example, point A, as shown in FIG. 2, the output of the recording amplifier 5 connected to the ALC circuit 4 is controlled so as to remain constant. Ru.

Nowadays, tape recorders are sometimes used as dictation recorders for notes, such as microcassette recorders. In this case, when you speak from a few centimeters to several tens of centimeters away from the built-in microphone, especially when pronouncing "B" or "P" in English, sound pressure called a plosive is applied directly to microphone 1. . Therefore, the amplification degree of the ALC circuit 4 is temporarily lowered, and the recording level of the voice input immediately after the plosive sound is lowered, making it difficult to hear during playback. Furthermore, even in the case of Japanese pronunciation, sound pressure called wind noise is added to the microphone 1 when pronouncing the ``sa'' line, resulting in a harsh sound during playback.

Conventionally, as a countermeasure to these problems, it has been considered to set the rise time of the ALC circuit 4 to be long for plosive sounds. However, if there is an audio input that exceeds the amplifier's saturation, it will take a long time for the audio to clip and become muddy, making it difficult to hear during playback. Also, the above
It is also conceivable to shorten the recovery time of the ALC circuit 4 so that even if a dropout occurs, it will recover immediately. However, if recorded in a very noisy place, noise would be generated at every break between the words, like waves, which would make it difficult to hear.

In addition, to reduce wind noise, it is also possible to lower the high frequency range of the recording frequency. However, there are drawbacks such as a lack of clarity during playback, and no absolute countermeasures have been taken. In order to prevent the sound pressure of the above-mentioned plosive sounds and wind noises, it is possible to cover the sound reporting surface of the microphone with a windscreen made of foamed urethane, but in small devices such as microcassette recorders, the sound of the built-in motor can be , it is not possible to obtain a sufficient S/N ratio. Particularly when recording conferences rather than close-range recordings, installing a windscreen will result in an extremely poor S/N ratio.

This idea was developed in view of the above circumstances, and it improves the S/N ratio during close recording by switching the microphone sensitivity for conference recording and close recording by operating a switch button, and also improves the S/N ratio during close recording. The purpose of the present invention is to provide a microphone sensitivity switching device for a tape recorder, which prevents wind pressure caused by plosive sounds and wind noise by moving and arranging a wind screen in front of the sound of a built-in microphone during close recording in conjunction with the operation of a button. do.

An embodiment of this invention will be described below with reference to the drawings.

As shown in FIGS. 3 and 4, the recorder 6 includes a circuit board 7, a microphone 8, and a microphone sensitivity switch 9. The recess 12 on the bottom of the microphone sensitivity changeover button 11 is fitted into the protruding sliding terminal 10 of the microphone sensitivity changeover switch 9, and the head of the button is slid in the direction shown by the arrow in the figure, thereby causing the protrusion. By sliding the sliding terminal 10 and selecting an arbitrary terminal of the microphone sensitivity switch 9, an arbitrary sensitivity is set in a known microphone sensitivity switching circuit as shown in FIGS. 5 and 6. The microphone sensitivity switching circuit is a well-known one, and its detailed explanation will be omitted, but in FIG. 5 it changes depending on the increase or decrease of the load resistance, and in FIG. The microphone sensitivity is set by

A wind screen 13 made of, for example, a foamed urethane sheet or a non-woven fabric is connected to the microphone sensitivity switching button 11 and can be placed in front of the microphone 8 for sound reporting. For example, in the case of close recording, the microphone sensitivity switching button 11 is operated to the low side in order to lower the microphone sensitivity, and the ALC circuit 4 is turned on by the input sound at about 10 cm from the microphone in the microphone sensitivity switching circuit. Set the microphone sensitivity as desired. At the same time, the wind screen 13 is interlocked and stopped directly above the microphone 8, as shown in FIG. 4, and is arranged so as to block the sound reporting surface of the microphone. As a result, the wind screen 13 can prevent plosive sounds and wind noise from the microphone 8. On the other hand, in order to increase the microphone sensitivity when recording a conference, the microphone sensitivity switching button 11 is operated to the high side, thereby setting the high microphone sensitivity in the microphone sensitivity switching circuit and at the same time, the wind screen 13 is In conjunction with this, the microphone 8 is removed from the front surface.

As described above, according to this invention, the microphone sensitivity can be switched between conference recording and close-range recording by operating the switch button.
The N ratio can be improved, and at the same time, the wind screen can be moved and placed in front of the built-in microphone during close recording in conjunction with the operation of the switching button, reducing the plosive sounds and wind noise that occur with the input sound. It is possible to obtain a microphone sensitivity switching device for a tape recorder that can prevent wind pressure.

[Brief explanation of drawings]

Fig. 1 shows a conventional control circuit for transmitting input sound to a recording head; Fig. 2 shows the relationship between the microphone input and the recording amplifier output in the circuit example shown in Fig. 1; Fig. 3 shows a side view of the main part of one embodiment of this invention; Fig. 4 shows a plan view of the main part of Fig. 3; Figs. 5 and 6 show known microphone sensitivity switching circuits. 8... microphone, 9... microphone sensitivity switch, 1
1...Microphone sensitivity switch button, 13...Windscreen.

Claims (1)

[Scope of utility model registration request] Microphone, microphone sensitivity switching circuit, ALC
In a tape recorder having a built-in circuit or AGC circuit, a wind screen is arranged on the sound reporting surface of the microphone in conjunction with the switching operation of the microphone sensitivity switching button of the microphone sensitivity switching circuit, and the wind pressure of plosive sounds and wind noise is A microphone sensitivity switching device for a tape recorder, characterized in that the windscreen is connected to the microphone sensitivity switching button to prevent this.