close

Вход

Забыли?

вход по аккаунту

?

JPH1011901

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH1011901
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
recording / reproducing apparatus provided with a noise canceling circuit, and more particularly
to a recording / reproducing apparatus provided with a noise canceling circuit of a digital signal
type recording / reproducing apparatus.
[0002]
2. Description of the Related Art Conventionally, a noise cancel circuit for picking up extraneous
noise with a microphone arranged near the listening position, adding noise picked up by the
microphone to the main signal channel with a waveform of reverse phase and canceling
extraneous noise heard at the listening position 1 Is a well-known technology, for example, as
shown in FIG. 2, from a microphone (noise pick-up microphone) 5 disposed in the vicinity of the
listening position of the main channel 4 from the sound source 2 such as music and voice to the
speaker (headphones) 3 The noise picked up is added from the feedback circuit 6 having a
predetermined feedback constant to the mixing circuit 7 to be added to the main channel signal
so as to cancel extraneous noise that can be heard by the ear at the listening position. Such a
noise cancellation circuit is also described in Japanese Patent Application Laid-Open No. 2231899.
[0003]
03-05-2019
1
By the way, when this circuit is applied to a digital signal system, an AD (analog-digital)
conversion circuit for digitizing a signal picked up by a microphone and an operation unit (DSP =
for performing digital signal processing) A Digital Signal Processor and a DA (digital-analog)
conversion circuit for converting into an analog signal and outputting the signal are required.
Therefore, there is a drawback that the cost is considerable.
[0004]
Therefore, the problem to be solved by the present invention is to provide a recording /
reproducing apparatus provided with a noise canceling circuit provided with a noise canceling
circuit configured at low cost in a recording / reproducing apparatus of digital signal system. To
provide.
[0005]
SUMMARY OF THE INVENTION In order to solve this problem, a recording / reproducing
apparatus provided with a noise cancellation circuit according to claim 1 of the present invention
performs A / D conversion for A / D conversion of an output of a recording microphone. In a
digital recording / reproducing apparatus provided with a circuit and a DSP for processing the
output of the digital recording / reproducing circuit and a speaker for receiving the output of the
DSP, a microphone for noise pickup disposed near the speaker and picking up extraneous noise,
and for recording during reproduction The microphone is separated from the A / D conversion
circuit, and the noise pickup microphone is switched to the A / D conversion circuit (recording /
reproduction changeover switch S1). (A recording / playback switch S2) for A / D conversion of
the output of the noise pickup microphone during playback, The phase is inverted by DSP and
supplied to the speaker to cancel external noise.
[0006]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the
present invention will be described below with reference to FIG.
FIG. 1 is a circuit diagram of a recording / reproducing apparatus provided with the noise
canceling circuit of the present invention. In FIG. 1, an audio digital signal from the digital
recording / reproducing circuit 8 is converted to a D / A converter circuit 13 via a DSP 9. To the
analog signal and to the speaker (headphones) 3.
03-05-2019
2
This signal path is the main channel 4, to which a recording microphone 12 operating at the time
of recording and a recording channel 12 consisting of an A / D conversion circuit 11 are
attached.
[0007]
The noise pickup microphone 5 is disposed in the vicinity of the speaker (headphones) 3 to pick
up external noise. Between the noise pick-up microphone 5 and the recording microphone 10
and the A / D conversion circuit 11, a two-contact switch (recording / reproduction changeover
switch) S1 is interposed. Between the circuit 8 and the DSP 9, a two-contact switch (recording /
reproduction changeover switch) S2 is interposed, and between the input terminal 9a and the
output terminal 9b of the DSP 9 (recording / reproduction changeover switch) S3. Is intervened.
[0008]
Then, in the reproducing operation in the state of FIG. 1, the switch S1 connects the contacts S1a
and S1c, connects the noise pickup microphone 5 to the A / D conversion circuit 11, and
simultaneously connects the switches S2c and S2a. Then, the DSP 9 is connected to the A / D
conversion circuit 11, and at the same time, the switch S3 is set to the contact S3a side.
[0009]
In this reproduction state, the signal of the main channel 4 is A / D converted from the external
noise obtained from the noise pickup microphone 5 disposed in the vicinity of the speaker
(headphones) 3 and added to the DSP 9 to multiply a predetermined feedback coefficient. In
addition to the D / A conversion circuit 13, the D / A conversion circuit 13 performs D / A
conversion and outputs the main channel signal from the speaker 3.
As a result, the external noise entering the listener's ear in the vicinity of the speaker 3 and the
signal of the phase opposite to the external noise passing through the speaker 3 cancel each
other, and the listener can hear only the main channel signal.
[0010]
Then, in the recording operation using the recording microphone 10, the switch S1 connects the
03-05-2019
3
contacts S1b and S1c, connects the recording microphone 10 to the A / D conversion circuit 11,
and at the same time, the switch S2 connects the contacts S2c and S2b. The digital recording /
reproducing circuit 8 is connected to the A / D conversion circuit 11. At the same time, the
switch S3 is on the contact S3b side, the DSP 9 is excluded from the main channel 4, and the
output signal of the digital recording / reproducing circuit 8 is It is added to the D / A conversion
circuit 13 to be an analog signal and output from the speaker 3 to be a monitor at the time of
recording.
[0011]
According to the present invention, since the A / D conversion circuit, which has been used only
in the conventional recording in the digital recording / reproducing apparatus, is used for the
external noise cancellation circuit in the reproduction. It is possible to provide a recording /
reproducing apparatus provided with a noise cancellation circuit that constitutes a noise
cancellation circuit at low cost.
[0012]
Brief description of the drawings
[0013]
1 is a circuit diagram of a recording / reproducing apparatus provided with the noise
cancellation circuit of the present invention.
[0014]
2 is a circuit diagram of an audio reproduction apparatus provided with a conventional noise
cancellation circuit.
[0015]
Explanation of sign
[0016]
DESCRIPTION OF SYMBOLS 1 ... noise cancellation circuit, 2 ... sound source, 3 ... speaker
(headphones), 4 ... main channel, 5 ... microphone for noise pick-up, 6 ... feedback circuit, 7 ...
mixed circuit, 8 ... digital recording / reproducing circuit, 9 ... DSP , 10: recording microphone,
11: A / D conversion circuit, 12: recording channel, 13: D / A conversion circuit, S1, S2, S3:
recording / reproduction changeover switch
03-05-2019
4
03-05-2019
5
Документ
Категория
Без категории
Просмотров
0
Размер файла
12 Кб
Теги
jph1011901
1/--страниц
Пожаловаться на содержимое документа