JPH11285016

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DESCRIPTION JPH11285016
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
apparatus for correcting color misregistration of an image, for example, in a projection type color
receiver.
[0002]
2. Description of the Related Art In a projection type color receiver in which three projection
tubes are enlarged and projected onto a screen, when left and right speakers and a center
speaker are installed for sound reproduction, each speaker is built in as shown in FIG. In general,
the speaker is constructed using a magnetic shield type speaker using a cancel magnet as
disclosed in Japanese Patent Application No. 6-45136. It was
[0003]
However, in the above configuration, the external magnetic flux generated in response to the
current flowing through the speaker can not be completely prevented, and the external magnetic
flux is projected at the time of sound reproduction at a large volume. It has the drawback of
affecting the
[0004]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present
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invention comprises a cancel coil for canceling external magnetic flux and a circuit for
controlling the current supplied to the cancel coil by the strength of the audio signal.
According to the present invention, it is possible to reduce the influence of the external magnetic
flux, which changes due to the strength of the audio signal, on the projection tube.
[0005]
According to the first aspect of the present invention, an external magnetic flux canceling coil for
a center speaker is provided, and an inverting amplifier for supplying a canceling current
proportional to a center audio signal is provided in this coil. The present invention is
characterized by generating a canceling magnetic flux proportional to the strength of the
external magnetic flux of the center speaker, and has an effect of reducing the influence of the
external magnetic flux of the center speaker on the projection tube.
[0006]
According to a second aspect of the present invention, in the invention according to the first
aspect, the inverting amplifier further includes external magnetic flux canceling coils for the left
and right speakers, and generates canceling currents proportional to the respective left and right
audio signals in the coils. Is provided to generate a canceling magnetic flux in proportion to the
strength of the external magnetic flux of the left and right speakers, and has an effect of reducing
the influence of the external magnetic flux of the left and right center speakers on the projection
tube.
[0007]
The invention according to claim 3 of the present invention is characterized in that, in the
invention according to claim 2, the inverting amplifier generating the cancel current is common
to all the cancel coils, and the addition signal of the left and right voices is used as the control
signal. It has the effect of being able to simplify the circuit.
[0008]
The invention according to a fourth aspect of the present invention is characterized in that, in the
invention according to the second aspect, it is divided into an inversion amplifier which generates
left and right cancel current and an inversion amplifier which generates a center cancellation
current. By stopping the operation of the center cancellation circuit when the center speaker is
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not used, the adverse effect of the cancellation circuit when the center speaker is not used can be
prevented.
The invention according to claim 5 of the present invention provides external magnetic flux
canceling coils for the left and right speakers, and provides an inverting amplifier for flowing
cancellation current in proportion to the respective left and right audio signals to this coil,
thereby providing external magnetic fluxes for the left and right speakers. It is characterized in
that a canceling magnetic flux is generated in proportion to the strength of the motor and has an
effect of reducing the influence of the external magnetic flux of the left and right speakers on the
projection tube.
[0009]
The invention according to claim 6 of the present invention is characterized in that, in the
invention according to claim 5, the inverting amplifier for generating the cancel current is
common to the left and right cancel coils, and the addition signal of the left and right voices is
used as the control signal. It has the effect of being able to simplify the circuit.
[0010]
The invention according to claim 7 of the present invention is characterized in that, in the
invention according to claim 6, the left and right cancel coils are sized to cover the whole of the
three projection tubes, and the control signal is an addition signal of the left and right voices.
Thus, the circuit can be simplified by reducing the number of cancel coils.
[0011]
(First Embodiment) FIG. 2 is a horizontal sectional view of a projection type color receiver,
showing a specific construction of the present invention, and FIG. 1 is an enlarged vertical
sectional view of the vicinity of the center thereof.
1 is a cabinet, 2 is an optical block, 3, 4 and 5 are projection tubes, 6 is a left speaker, 7 is a right
speaker, 8 is a center speaker, 9 is a center cancellation coil, 10 is an amplifier for left speaker,
11 is a right speaker An amplifier 12, an amplifier for center speaker 12, and an inverting
amplifier 13 for center cancellation coil.
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In this configuration, when the center sound signal is driven by the center speaker amplifier 12
and the center speaker 8 is driven, an external magnetic flux is generated outside the center
speaker 8 due to the strength of the sound signal. affect.
At this time, the same center audio signal is driven by the center cancel coil inverting amplifier
13 to generate the cancel magnetic flux in the reverse direction to the external magnetic flux,
thereby reducing the influence on the projection tube. .
[0012]
(Embodiment 2) Although the cancel coil which cancels only the external magnetic flux of the
center speaker was provided in the above Embodiment 1, as shown in FIG. 3, the inversion
amplifier 16 for left speakers and the left cancel coil are respectively provided to the left and
right speakers. 14, a right speaker inverting amplifier 17 and a right cancel coil 15 are provided,
and a cancel circuit for external magnetic flux of the left and right speakers is provided.
[0013]
Third Embodiment Further, in the second embodiment described above, as shown in FIG. 4, the
inverting amplifier 18 for canceling coil has a configuration common to all the canceling coils.
[0014]
(Fourth Embodiment) Furthermore, in the second embodiment, as shown in FIG. 5, the amplifiers
for the cancellation coil are the center cancellation coil inversion amplifier 13 and the left and
right cancellation coil inversion amplifier 19 for left and right speakers.
[0015]
(Fifth Embodiment) In the case of a projection type color receiver which does not have a center
speaker, as shown in FIG. 6, only the left and right cancel coils and the left and right cancel coil
inverting amplifiers are used.
[0016]
Sixth Embodiment In the above fifth embodiment, as shown in FIG. 7, the cancel coil is driven by
a signal obtained by adding the left and right audio signals by an adder, and the left and right
cancel coil inverting amplifier 19 is made common. .
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[0017]
Seventh Embodiment In the above fifth embodiment, as shown in FIG. 8, the left and right cancel
coils are sized to cover the entire three projection tubes, and the control signal is added to the
left and right voice addition signals. It was set as the structure to be used.
[0018]
According to the present invention, the external magnetic flux, which changes in accordance with
the current flowing to the speaker by the audio signal, is always canceled by using the audio
signal to cancel magnetic flux proportional to the magnitude of the external magnetic flux. As it
can be generated, the influence on the projection tube can be reduced.
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