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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to sound reproducing apparatus and,
more particularly, is directed to a sound reproducing apparatus which is
automatically made operative at a preset time for reproducing sound with a
selected volume.
2. Description of the Prior Art
Sound reproducing apparatus has been proposed for receiving an audio signal
from a broadcast radio receiver, an audio disk of tape player or other
audio signal source and for reproducing sound based on such audio signal,
and wherein a time control is provided for automatically controlling the
main power supply and other operating components of the sound reproducing
apparatus to start and stop at predetermined or present times. Such known
sound reproducing apparatus is further provided with a remote controller
by which the main power supply can be activated and other operations can
be made to start or stop in response to command signals issued from a
remote location.
In the known sound reproducing apparatus provided with the time control and
remote control functions described above, the volume of the sound
reproduced it response to the time control or the remote controller is
controlled by varying the effective resistance value of a variable
resistor which, for example, is included in an audio amplifier of an audio
signal processing circuit, and which is controlled by a volume control
signal. The variable resistor for effecting volume control can be
electronically controlled, for example, in the form of a semi-conductor
resistive device with its variable resistance controlled directly by a
control signal, or it can be a mechanically driven variable resistor in
the form of a rotary or linearly slidable variable resistive device
provided with an actuator, such as, an electric motor, which drives the
rotary or linearly slidable variable resistive device in response to a
control signal.
The above described known sound reproducing apparatus provided with time
control and remote control functions may be employed as an alarm for
waking a sleeping person, in which case the time control function
commences operation of the audio signal processing circuit for producing
the sound output at a preset time, and the variable resistor is employed
for obtaining the reproduced sound with an appropriate volume, that is,
loud enough to wake a sleeping person.
For causing the volume controlling variable resistor to operate so that an
appropriate volume of the reproduced sound is obtained from the apparatus
provided with both the time control and remote control functions when used
as an alarm for waking a person, it is necessary to recognize or sense the
condition of the volume controlling variable resistor when the preset time
is being established, and also at such preset time, that is, when the
variable resistor becomes operative for obtaining the desired volume
control. When the volume controlling variable resistor is constituted by
an electronically controlled semi conductor resistive device having its
variable resistance controlled directly by a control signal, the
recognition and estimate of the resistance value of the volume controlling
variable resistor can be easily achieved, at any time, on the basis of the
control signal which is applied to the semi-conductor resistive device.
On the other hand, when a mechanically driven rotary or linearly slidable
variable resistor is used for achieving the volume control, it is
necessary to provide a device for detecting positions of a slider of the
variable resistive device for use in recognizing and estimating the
effective resistance value of the volume controlling variable resistor.
Such slider position detecting device produces a detection output signal
corresponding to the position of the slider of the sliding variable
resistive device, and hence to its effective resistance value, and a
circuit arrangement including a waveform shaping circuit, an
analog-to-digital converter, a pulse counter and so on, for processing the
detection output signal. The foregoing arrangement is disadvantageous in
that it undesirably increases the complexity and cost of the sound
reproducing apparatus.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a sound
reproducing apparatus having a mechanically driven variable resistor for
effecting volume control in an audio signal processing circuit, and which
avoids the previously mentioned disadvantages of the prior art.
More specifically, it is an object of this invention to provide a sound
reproducing apparatus in which an audio signal processing circuit is made
operative at a preset time and a variable resistor having a mechanically
driven slider is provided in such circuit for controlling the volume of
the reproduced sound which is thereby obtained with an appropriate volume
without the need for employing a slider position detecting device in
association with the mechanically driven variable resistor.
Another object of the invention is to provide a sound reproducing
apparatus, as aforesaid, in which the mechanically driven variable
resistor provided in the audio signal processing circuit for controlling
the volume of the reproduced sound is surely and accurately operated at
the preset time when operation of the sound reproducing apparatus is
commenced, and in which such desirable characteristics of the apparatus
are attained without unduly increasing the complexity and cost of the
apparatus.
In accordance with an aspect of this invention, a sound reproducing
apparatus is provided with a audio signal processing circuit for receiving
an audio signal from an input circuit and applying the same to a speaker
or sound producer through a variable resistor which is mechanically
adjusted or driven to vary its effective resistance value by an actuator,
such as, an electric motor, operating in response to a drive signal so as
to reproduce sound corresponding to the audio signal with a volume
determined by the effective resistance value of the variable resistor, a
time control for causing the audio signal processing circuit to commence
operation automatically at a preset time, duration setting means operative
in response to a duration setting signal and having a memory in which data
corresponding to a selected duration of operation of the actuator are
stored, and control means programmed to be operative, when the time
control causes the commencement of the operation of the audio signal
processing circuit at the preset time, to apply the drive signal to the
actuator for the selected duration corresponding to the data stored in the
memory so as to determine the volume of the sound from the speaker or
sound producer at the end of such selected duration.
In a preferred embodiment of the invention, the control means is further
programmed to cause the variable resistor to have an effective resistance
value at one end of its range of varying effective resistance values when
the audio signal processing circuit is made to commence operation at the
preset time, and only thereafter is the drive signal applied to the
actuator for the selected duration for varying the effective resistance
value of the variable resistor in the direction away from said one end of
the range of effective resistance values. Thus, it is made certain that,
upon each commencement of operation of the audio signal processing
circuit, the application of the drive signal to the actuator for the
selected duration will consistently result in a desired volume of the
reproduced sound.
Consequently, in the sound reproducing apparatus embodying the present
invention and in which the variable resistor provided for volume control
is mechanically driven by an actuator, the sound reproduced subsequent to
the preset time has its volume controlled automatically by the variable
resistor so as to be at an appropriate high level without requiring
detection of the condition of the variable resistor and, therefore,
without requiring undue complication of the apparatus and an undesirable
increase in its cost.
Further, since the variable resistor provided in the audio signal
processing circuit for controlling the volume of the reproduced sound is
driven by its associated actuator or motor so as to provide initially the
effective resistance value at one end of its variable range of effective
resistance values, and then to vary the effective resistance of the
variable resistor in the direction away from that one end of the range to
an extent determined by the duration for which the drive signal is applied
to the actuator, it will be apparent that the sound volume subsequent to
the preset time at which operation of the audio signal processing circuit
is commenced is controlled automatically so as to be a constant value.
The above, and other objects, features and advantages of the present
invention, will be apparent in the following detailed description of
preferred embodiments when read in conjunction with the accompanying
drawings, in which corresponding parts and components are identified by
the same reference numerals in the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram showing a sound reproducing apparatus
according to an embodiment of the present invention;
FIG. 2 is a flow chart showing a sequence of steps or operations performed
by the apparatus of FIG. 1 in accordance with a program established by a
microcomputer included therein when setting a desired volume of the sound
to be reproduced;
FIG. 3 is a flow chart showing a sequence of steps or operations performed
by the apparatus of FIG. 1 in accordance with a program established by the
microcomputer when the apparatus is performing an alarm function;
FIG. 4 is a schematic block diagram showing a sound reproducing apparatus
according to another embodiment of the present invention; and
FIG. 5 is a flow chart showing a sequence of steps or operations performed
by the apparatus of FIG. 4 under the control of a microcompter included
therein when performing an alarm function of such apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring initially to FIG. 1, it will be seen that a sound reproducing
apparatus according to an embodiment of the present invention is there
shown to be in the form of a stereophonic broadcast signal receiver which
includes a tuning and demodulating unit 11 connected to a signal receiving
antenna 10. The tuning and demodulating unit 11 contains a conventional
electronic tuning device for selecting a desired one of a number of
stereophonic broadcast signals recieved by the antenna 10, and a
demodulating device for demodulating the selected stereophonic broadcast
signal and thereby providing a stereophonic audio signal composed of left
and right audio signals which are supplied to respective inputs 12L and
12R of an input signal selector 12. The input signal selector 12 is
further shown to have auxiliary inputs 12XL and 12XR and auxiliary inputs
12YL and 12YR which are connected to respective auxiliary input terminals
13 to which left and right audio signals forming stereophonic audio
signals are supplied from other audio signal sources, such as, various
audio disk or tape players. Selected left and right audio signals SL and
SR are obtained from the input signal selector 12 and supplied to
preamplifiers 14 and 15, respectively.
The amplified left and right audio signals SL and SR are supplied from
preamplifiers 14 and 15, respectively, through balance adjusters 16 and
17, respectively, to a volume controller 18. The balance adjusters 16 and
17 may be, as shown, constituted by respective variable resistors
including resistive elements connected together, at one end, to ground,
and having their other ends connected to the preamplifiers 14 and 15,
respectively, and sliders which are independently adjustable along the
resistive elements for providing to the volume controller 18 balance
adjusted left and right audio signals with a desired relation of their
levels to each other.
The volume controller 18 is shown to include a slidable variable resistor
19 for controlling the volume of the left audio signal SL and a slidable
variable resistor 20 for controlling the volume of the right audio signal
SR. The variable resistors 19 and 20 include respective resistive elements
connected, at one end, to the sliders of the variable resistors forming
the balance adjustors 16 and 17, respectively, while the other ends of the
resistive elements of the variable resistors 19 and 20 are connected
together to ground. The variable resistors 19 and 20 further include
sliders movable along the respective resistive elements, and being both
driven simultaneously by an actuator, for example, in the form of a motor
21. It will be appreciated that, in response to the operation of the motor
21, the sliders of the variable resistors 19 and 20 are slidably moved
along the respective resistive elements so as to simultaneously increase
or decrease the effective resistance values of the resistors 19 and 20,
and thereby decrease or increase, respectively, the levels of the
resulting left and right level-controlled audio signals SL' and SR',
respectively, derived from the volume controller 18.
The level-controlled left and right audio signals SL' and SR' are supplied
from volume controller 18 through power amplifiers 22 and 23 to sound
reproducers or speakers 24 and 25, respectively. Thus, the speakers 24 and
25 produce sound outputs in accordance with the level-controlled left and
right audio signals SL' and SR'.
All of the above described elements from the tuning and demodulating unit
11 to the speakers 24 and 25 are hereinafter referred to as constituting
an audio signal processing circuit 30, which is provided with an operation
controlling circuit 40. The operation controlling circuit 40 is shown to
include a control unit 41 which may be constituted by a microcomputer, a
timer 42 and a memory 43 each operatively coupled with the control unit
41, and a drive signal generator 44 connected with the motor 21. The
control unit 41 is operative to produce a tuning control signal Ct which
is supplied to the tuning and demodulating unit 11 for determining the
broadcast signal which is to be selected, a motor control signal Cm which
is supplied to the drive signal generator 44, and a plurality of operation
control signals Cx which are supplied to various portions of the audio
signal processing circuit 30 for causing the latter to be selectively
operative and inoperative and for effecting other controls thereof. The
drive signal generator 44 responds to the motor control signal Cm for
producing a corresponding drive signal Dm which is supplied to the motor
21.
A remote control signal receiver 45 which is provided at the outside of a
block or housing containing the operation control circuit 40, and an alarm
setting switch 46 are also shown to be connected with the control unit 41.
The remote control signal receiver 45 is operative to receive a remote
control signal Cr, radiated or transmitted from a remote commander 47, and
converts such remote control signal Cr into corresponding electrical
signals supplied to the control unit 41. The remote commander 47 has a
power control push-button switch 48, volume control push-button switches
49, and push-button switches forming a key-pad 50 and which are used for
tuning control, time setting and the remote control of other operations.
The remote commander 47 is operative, in response to the selective
actuation of one or more of the push-button switches 48, 49 and 50, to
transmit the remote control signal Cr in the form of corresponding
demodulated infra red signals which are sensed by the receiver 45.
Further, when the alarm setting switch 46 is actuated or turned ON, the
control unit 41 causes the sound reproducing apparatus to perform its
alarm function, as hereinafter described in detail.
It will be appreciated that, in using the above described sound reproducing
apparatus according to the embodiment of this invention shown on FIG. 1,
the power control push-button switch 48 of the remote commander 47 is
first actuated so that the corresponding remote control signal Cr, when
received by the remote control signal receiver 45, causes the control unit
41 to provide the operation control signals Cx by which the audio signal
processing circuit 30 is made operative. Then, selective actuation of the
push-button switches of the key-pad 50 is performed for exercising tuning
control, and the resulting remote control signal from commander 47 is
converted by receiver 45 into electrical signals which cause the control
unit 45 to provide a suitable tuning control signal Ct by which the tuning
and demodulating unit 11 is made to select and demodulate the desired one
of the stereophonic broadcast signals received by the antenna 10. With the
input signal selector 12 being conditioned for connection to its inputs
12L and 12R, the left and right audio signals SL and SR obtained from the
tuning and demodulating unit 11 are passed through the selector 12 to the
preamplifiers 14 and 15, respectively. The preamplified left audio signal
from the preamplifier 14 is supplied through the balance adjuster 16 to
the slidable variable resistor 19 in the volume controller 18, and the
resulting level controlled left audio signal SL' is supplied through the
power amplifier 22 to the speaker 24. Similarly, the preamplified right
audio signal SR is supplied from the preamplifier 15 through the balance
adjuster 17 to the slidable variable resistor 20 in the volume controller
18, and the resulting level controlled right audio signal SR' is supplied
through the power amplifier 23 to the speaker 25. Thus, reproduced sounds
based on the level-controlled left and right audio signals SL' and SR' are
obtained from the speakers 24 and 25, respectively.
When one or the other of the volume control push-button switches 49 of the
remote commander 47 is actuated, the resulting remote control signal Cr is
converted by the receiver 45 into electrical signals which cause the
control unit 41 to supply a corresponding motor control signal Cm to the
drive signal generator 44. In response to the motor control signal Cm, the
drive signal generator 44 provides a corresponding drive signal Dm to the
motor 21 for operating the same. As a result of such operation of the
motor 21, the sliders of the variable resistors 19 and 20 in the volume
controller 18 are simultaneously driven to correspondingly vary the
effective resistance values of the variable resistors 19 and 20, with the
result that the volumes of the sounds output by the speakers 24 and 25 are
correspondingly increased or decreased. Thus, during the normal operation
of the sound reproducing apparatus embodying this invention, the volume of
the reproduced sound can be varied at will merely by selective actuation
of the volume control push-button switches 49 of the remote commander 47.
If the sound reproducing apparatus is operated when a person is retiring,
the volume of the sound may be reduced for inducing sleep, and,
thereafter, the sound reproducing apparatus may be automatically rendered
inoperative. However, such reduced volume of the reproduced sound may not
be sufficient to ensure that a sleeping person will be awakened thereby if
the sound reproducing apparatus is again made operative at a preset time
so as to function as an alarm.
Therefore, in accordance with the present invention, the volume of the
sounds emanating from the speakers 24 and 25 is automatically controlled
to ensure that such sounds will be sufficient to awaken a sleeping person
when performing the alarm function of the apparatus, that is, when the
apparatus is made operative at a preset time and its alarm function has
been selected. Prior to performance of the alarm function, time setting
and sound volume setting operations are carried out independently of each
other.
When performing the time setting operation, the pushbutton switches of the
key-pad 50 of the remote commander 47 are selectively actuated according
to the time to be set and, in response thereto, the remote control signal
Cr representing such preset time is radiated or transmitted from the
remote commander 47 to the remote control signal receiver 45. The
resulting electrical signals supplied from the receiver 45 to the control
unit 41 establish the time setting mode of the latter in which the control
unit 41 operates to store in the memory 43 data corresponding to the
preset time represented by the remote control signal Cr. Such present time
data stored in the memory 43 are compared with output data obtained from a
continuously operating timer (not shown) included in the control unit 41.
For performing a sound volume setting operation, the alarm setting switch
46 is depressed or turned ON for at least a predetermined period of time,
for example, for at least 2 seconds, as measured by the timer 42, while
the speakers 24 and 25 emit respective sounds at an ordinary or normal
volume, and with the control unit 41 continuing to operate in its time
setting mode. During the time in which the control unit 41 remains in its
time setting mode, one of the volume control pushbutton switches 49 of the
remote commander 47 is actuated so as to cause an increase in the volume
of the sound outputs from the speakers 24 and 25. So long as one of the
volume control pushbutton switches 49 is actuated for increasing the
volume of the sound outputs from the speakers 24 and 25, the remote
control signal Cr transmitted from the commander 47 to the receiver 45 is
in the form of a volume control signal Cra. The control unit 41, in its
time setting mode, provides data corresponding to the duration of the
period of time in which the volume control signal Cra is transmitted and,
hence, in which the volume of the speaker outputs is being increased. When
the volume of the sound produced by the speakers 24 and 25 has become
sufficiently high in response to the continued actuation of the volume
increasing push-button switch 49, the alarm setting switch 46 is again
turned ON and, in response thereto, the control unit 41 operates to store
in the memory 43 the data corresponding to the duration of the time in
which the volume control signal Cra was transmitted for increasing the
volume. Upon the storing of such duration indicating data in the memory
43, a new sound volume setting has been effected.
If neither of the volume control push-button switches 49 is actuated within
a predetermined period of time, for example, within 5 seconds as measured
by the timer 42, after the time setting mode of the control unit 41 has
been established, or if the alarm setting switch 46 is not turned ON after
one of the volume control push-button switches 49 has been actuated, the
control unit 41 is released from its time setting mode and a sound volume
setting is not performed, that is, data corresponding to the duration of
actuation of one or the other of the switches 49 is not stored in the
memory 43.
After a sound volume setting operation has been completed, the control unit
41 changes-over to its alarm mode for performing the operations required
for its alarm function Similarly, if the alarm setting switch 46 is
depressed or turned ON for a period of time shorter than 2 seconds at a
time when a sound volume setting has not been newly effected, the control
unit 41 is again changed-over to its alarm mode.
In performing the alarm function with the control unit 41 in its alarm mode
after a time setting operation and a sound volume setting operation have
been carried out as described above, the operation control signals Cx are
supplied from the control unit 41 to the various portions of the audio
signal processing circuit 30 to cause the latter to be operative when the
current time data obtained from the timer (not shown) within the control
unit 41 come to coincide with the data stored in the memory 43 for
representing the preset time. Simultaneously with such commencement of the
operation of the audio signal processing circuit 30 at the preset time,
the motor control signal Cm is supplied from the control unit 41 to the
drive signal generator 44 for a period of time represented by the set
duration data stored in the memory 43. In response to such signal Cm, the
drive signal generator 44 produces the drive signal Dm and supplies the
same to the motor 21 for the set duration during which the motor 21 is
operated. Consequently, the sliders of the variable resistors 19 and 20 in
the volume controller 18 are driven by the motor 21 for a period of time
corresponding to the set duration so as to change the effective resistance
values of the resistors 19 and 20 in a sense for increasing the volume of
the sounds produced by the speakers 24 and 25. It will be appreciated that
the extent of such increase in the volume of the produced sounds
corresponds to the duration during which the motor 21 is operated in
response to the drive signal Dm, and hence in response to the set duration
indicating data previously stored in the memory 43.
Therefore, in the manner described above, sounds of predetermined increased
volume are obtained from the speakers 24 and 25 after the preset time at
which the audio signal processing circuit is made operative so that the
sounds of increased volume will be an effective alarm for rousing a
sleeping person.
The program carried out by the microcomputer constituting the control unit
41 for performing a sound volume setting operation with the apparatus of
FIG. 1, will now be further described with reference to the flow chart of
FIG. 2. As shown on FIG. 2, the program is initiated or started in
response to turning ON of the alarm setting switch 46 whereupon, in step
51, operation of the timer 42 is commenced. In the next step 52 it is
determined whether the alarm setting switch 46 is turned ON for a
substantial interval of time or merely momentarily. In other words, if the
alarm setting switch 46 has been only turned ON momentarily, the answer to
the query in decision step 52 is NO and the program advances to step 53 in
which the operation of the timer 42 is halted. In the following step 54,
the alarm mode of the control unit 41 is established and, thereafter, the
sound volume setting program is terminated
On the other hand, if it is determined in step 52 that the alarm setting
switch 46 has been more than momentarily depressed or turned ON, the
program proceeds to step 55 in which it is determined whether or not 2
seconds have elapsed since the alarm setting switch 46 was initially
turned ON. If 2 seconds have not elapsed since the alarm setting switch 46
was turned ON, the program is returned to step 52. On the other hand, if
the alarm setting switch 46 has been turned ON for at least 2 seconds,
the time setting mode of the control unit 41 is established in step 56.
Then, in step 57, it is determined with reference to data obtained from
the timer 42, whether or not 5 seconds have elapsed since the time setting
mode of the control unit 41 has been established. If 5 seconds have
elapsed since the time setting mode of the control unit 41 was
established, the operation of the timer 42 is halted in step 58, and the
control unit 41 is released from its time setting mode in the following
step 59, whereupon the sound volume setting program is terminated.
On the other hand, if it is determined in step 57 that 5 seconds have not
yet elapsed since the time setting mode of the control unit 41 was
established, the program proceeds to step 60 where it is checked whether
or not the remote control signal Cr is being received by the remote
control signal receiver 45. If the remote control signal Cr is not being
received, the program is returned to step 57. On the other hand, if it is
determined in step 60 that the remote control signal Cr is being received
by the remote control signal receiver 45, the program proceeds to step 61
in which it is determined whether or not the received remote control
signal is a volume control signal Cra, as results when one of the volume
control push-button switches 49 is depressed or actuated.
If it is determined in step 61 that the remote control signal Cr
transmitted to receiver 45 is not a volume control signal Cra, operation
of the timer 42 is halted in step 62 and the control unit 41 is released
from its time setting mode in step 63, whereupon the control operation
corresponding to the remote control signal Cr which is being transmitted
to the receiver 45 is carried out in step 64. Thereafter, the sound volume
setting program is terminated.
On the other hand, if it is determined in step 61 that the remote control
signal Cr being transmitted to the receiver 45 is in fact a volume control
signal Cra, the duration Tt of the period of time during which the volume
control signal Cra has been transmitted is calculated in step 65 and data
corresponding to such duration Tt is provided. In the next step 66, it is
determined whether or not the alarm setting switch 46 has been again
depressed or turned ON. If the alarm setting switch 46 is not again turned
ON, the program returns to step 57. On the other hand, if it is determined
in step 66 that the alarm setting switch 46 is again turned ON, the data
representing the duration Tt calculated in step 65 are stored in the
memory 43 in the following step 67. In the next step 68, the control unit
41 is released from its time setting mode and the program proceeds to step
53 in which the operation of the timer 42 is halted. Thereafter, in step
54, the alarm mode of the control unit 41 is established, and then the
sound volume setting program is terminated.
Referring now to FIG. 3, it will be seen that a program carried out in the
microcomputer constituting the control unit 41 for performing the alarm
function of the sound reproducing apparatus illustrated in FIG. 1 is
started at the preset time corresponding to data stored in the memory 43.
At such preset time operation control signals Cx are supplied from the
control unit 41 to the various parts of the audio signal processing
circuit 30 for causing the latter to become operative. After initiation of
the program for performing the alarm function, it is determined in step 71
whether or not the alarm mode of the control unit 41 has been established.
If the control unit 41 is not in its alarm mode, the program is
terminated. On the other hand, if it is determined in step 71 that the
control unit 41 is in its alarm mode, the data representing the duration
Tt are read from the memory 43 in the following step 72. In the next step
73 the operation of the timer 42 is initiated and, substantially
simultaneously therewith, in step 74, the motor control signal Cm is
supplied from control unit 41 to the drive signal generator 44 for causing
the latter to provide the drive signal Dm by which the motor 21 is
operated Thereafter, in step 75, the set duration corresponding to the
data read from the memory 43 is compared with the elapsed time indicated
by the timer 42 for determining whether or not the set duration Tt has
elapsed since commencement of the operation of the motor 21. So long as
the set duration Tt has not elapsed, step 75 is repeated. However, when it
is determined, in step 75, that the set duration Tt has elapsed, the
program proceeds to step 76 in which the motor control signal Cm is
terminated. Then, in succession, the operation of the timer 42 is halted
in step 77 and the control unit 41 is released from its alarm mode in step
78, whereupon the program for performing an alarm operation is terminated.
It will be appreciated that during the period of time corresponding to the
duration Tt in which the motor control signal Cm is supplied to the drive
signal generator 44 for operating the motor 21, the variable resistors 19
and 20 in the volume controller 18 have their effective resistance values
changed so as to increase the volume of the sounds produced by the
speakers 24 and 25 to the extent previously selected during the sound
volume setting operation previously described with reference to the flow
chart of FIG. 2.
Referring now to FIG. 4, it will be seen that a sound reproducing apparatus
according to another embodiment of the present invention is there shown to
also be in the form of a stereophonic broadcast signal receiver similar to
that described above with reference to FIG. 1, and in which devices,
circuits and components corresponding to those described with reference to
FIG. 1 are identified by the same reference numerals and will not be
further described herein.
In the embodiment of FIG. 4, the control unit 41A, which again may be
desirably constituted by a microcomputer, is additionally operative at
appropriate times, as hereinafter further described, to supply a muting
control signal Cu to each of the power amplifiers 22A and 23A for muting
the output from such power amplifiers to the loud speakers 24 and 25, and
further to selectively supply motor control signals Cm and Cm' to the
drive signal generator 44 for causing the latter to produce drive signals
Dm and Dm', respectively, by which the motor 21 is driven in opposite
directions for increasing and decreasing, respectively, the volume of the
sound produced by the speakers 24 and 25.
The sound reproducing apparatus of FIG. 4 operates generally in the same
manner as described above with reference to the apparatus of FIG. 1 apart
from its performance of the alarm function under the control of the
control unit 41A. More specifically, after the time setting and sound
volume operations have been carried out in the manner described above for
the embodiment of FIG. 1, the alarm mode of the control unit 41A is
similarly established and operation control signals Cx are supplied from
the control unit 41A to the various portions of the audio signal
processing circuit 30 for causing operation of the latter when data
obtained from a time (not shown) container in the control unit 41A
coincide with the data stored in the memory 43 for indicating the preset
time at which an alarm operation is to be performed. Simultaneously with
the commencement of operation of the audio signal processing circuit 30,
the control unit 41A supplies the muting control signal Cu to each of the
power amplifiers 22A and 23A so that no sound output is obtained from the
speakers 24 and 25. At the same time, the motor control signal Cm' is
supplied from the control unit 41A to the drive signal generator 44 so
that the latter produces the drive signal Dm' by which the motor 21 is
driven in the direction to change the effective rcsistance values of the
variable resistors 19 and 20 toward one end, for example, the upper or
maximum end, of the range of effective resistance values of the variable
resistors 19 and 20.
After the variable resistors 19 and 20 have been driven to provide their
maximum effective resistance values, which correspond to a minimum volume
of sound produced by the speakers 24 and 25, the motor control signal Cm
is supplied from the control unit 41 to the drive signal generator 44
which, in response thereto, produces the drive signal Dm for operating the
motor 21 in the opposite direction, that is, in the direction for reduced
the effective resistance values of the resistors 19 and 20. Such drive
signal Dm is supplied to the motor 21 for a set duration which is
established by a sound volume setting operation, as described in
connection with the embodiment of the invention shown on FIG. 1
Consequently, the variable resistors 19 and 20 are driven for the set
duration so a to decrease the effective resistance values thereof starting
from their maximum effective resistance values so that the sound outputs
of the speakers 24 and 25 are increased to a predetermined constant
volume. The predetermined constant volume to which the sound outputs of
the speakers 24 and 25 are increased is sufficient to ensure that, when
the audio signal processing circuit 30 is made operative at a set time,
the sound produced by the speakers 24 and 25 in accordance with the left
and right audio signals SL and SR will be of sufficient loudness to awaken
a sleeping person, and thereby serve as an alarm, even if the last
preceding use of the sound reproducing apparatus had employed relatively
low sound volumes, for example, for inducing sleep.
The program carried out by the microcomputer constituting the control unit
41A for readying the sound reproducing apparatus of FIG. 4 for its alarm
operation will now be described with reference to the flow chart of FIG.
5. As shown on FIG. 5, the program is initiates or started in response to
the supplying of the operation control signals Cx from the control unit
41A to the various parts of the audio signal processing circuit 30 for
causing operation of the latter at the set time. Upon such starting of the
processor, it is determined, in step 81, whether or not the control unit
41A is in its alarm operation mode. If the control unit 41 is not in its
alarm operation mode, the program for readying the sound reproducing
apparatus for its alarm operation is terminated. On the other hand, if the
control unit 41A is determined to be in its alarm operation mode, the
program proceeds to step 82 in which the muting control signal Cu is
supplied from the control unit 41A to the power amplifiers 22A and 23A for
causing the cuting of the outputs therefrom to the respective speakers 24
and 25. In the following step 83, operation of the timer 42 is commenced
and then, in step 84, the motor control signal Cm' is supplied from the
control unit 41A to the drive signal generator 44. The program then
proceeds to step 85 in which it is determined, with reference to the timer
42, whether or not is seconds have elapsed since commencement of the
supplying of the motor control signal Cm' to the drive signal generator
44. If 10 seconds have not elapsed, step 85 is repeated. On the other
hand, if it is determined that 10 seconds have elapsed since commencement
of the signal Cm', the supplying of such signal to the drive signal
generator 44 is halted in step 86. It should be noted that, in the 10
second interval during which the motor control signal Cm' is supplied to
the drive signal generator 44, the drive signal Dm' supplied to the motor
21 is operative to drive the variable resistors 19 and 20, from any
positions they may have occupied, to positions corresponding to their
maximum effective resistance values.
After the motor control signal Cm' has been halted in step 86, the
operation of the timer 42 is halted in step 87 and then, in step 88, the
supplying of t | | |
