Abstract:
An audio apparatus comprises a tuner for receiving broadcast waves; a digital reproducing unit; operation switches for operating the tuner and the digital reproducing unit; and a control unit for controlling the tuner and the digital reproducing unit in response to an operation of the operation means. In a first mode of operation, the control unit controls if an audio signal from the tuner is selected as a source such that the power of the digital reproducing unit is turned on, and wherein, in a second mode operation, the control unit controls if an audio signal from the tuner is selected as a source such that the power of the digital reproducing unit is turned off, alternatively if an audio signal from the digital reproducing unit is selected as a source, the power thereof is turned on.

Description:
RELATED APPLICATION DATA 
     The present application claims priority to Japanese Application(s) No(s). P2003-092330 filed Mar. 28, 2003, and P2004-038488 filed Feb. 16, 2004, which application(s) is/are incorporated herein by reference to the extent permitted by law. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an audio apparatus, and in particular, to an audio apparatus including a tuner unit and a digital reproducing unit. 
     2. Description of the Related Art 
     As a consumer-use audio apparatus, there is a so-called system stereo. This system stereo, for example, is comprised of an AM-FM tuner, recording/reproducing components such as a cassette tape recorder, a compact disc (CD) player, a mini disc (MD) recorder/player and the like, and they are integrated and housed in a single cabinet. 
       FIG. 6  is a frontal view showing one example of a specific appearance of such system stereo. This system stereo in this example can handle AM/FM broadcasts, a CD, a compact cassette as its source, and optionally an MD recorder/player unit is connected if desired. 
     This system stereo is formed generally into a rectangular shape, and on the front panel there are provided a display  11 , a CD disc tray  12 , and a cassette loading slot  13 . Also, on the front panel there are provided a power on-off  25  key  14 , function keys  15 , a volume up-down key  16   a ,  16   b , and operation mode control keys  17 . 
     In this example, these keys  14  to  17  are composed of non-lock type push button switches. The function keys  15  are provided for switching over the sources, and by pushing this function key  15 , either of the AM broadcast tuner, FM broadcast tuner, a CD player, a cassette player, or a MD recorder/player can be selected. Further, the operation mode control key  17  serves to shift a receiving frequency to receive a desired broadcast station when receiving AM or FM broadcast waves, as well as serves to switch a mode of operation between a reproducing mode, a pause mode, a stop mode, etc. when using the CD player or cassette recorder/player. 
     Further, on the left and the right sides of the system stereo, there are disposed a pair of speakers  28 L and  28 R for left and right channels, respectively. A system control of this system stereo is executed by a built-in microcomputer (not shown). 
     Therefore, according to this system stereo described above, advantages in space-saving, a reduced production cost, and the like can be achieved, and also eliminating the need of messy wiring around of cables between respective components. 
     However, this system stereo as described above has such a drawback that radio frequency noise components of a clock of the built-in microcomputer for use in the system control reaches an AM or FM frequency bands and interferes with the reception of the AM or FM broadcast waves. 
     Therefore, it is arranged in some of the system stereos such that while receiving broadcast waves, a clock frequency of the microcomputer is slightly shifted corresponding to the receiving frequency of the broadcast so as to ensure for the radio frequency noise components of the clock not to coincide with or come into the vicinity of the receiving broadcast frequency, thereby preventing the interference with the reception of broadcasting. Here, the Japanese Patent No. 3122102 is referred to as a related art. 
     Generally, a CD player or an MD recording/reproducing unit executes a digital processing of audio signals, and also various controls thereof is digitally processed. Therefore, radio frequency noise components which reaches AM or FM frequency bands are also generated in the CD player and MD recording/reproducing unit. In addition, in the system stereo as described above, the tuners of AM broadcast and FM broadcast as well as the CD player are disposed in the same cabinet. 
     Thereby, it often occurs that radio frequency noise components generated in the CD player readily enters the tuner thereby causing interference with the reception of broadcasting, in particular, the reception of AM broadcast waves. That is, in case of receiving broadcast waves from a local station, as a signal level of the received signal is substantially high, the radio frequency noise components of the CD player are suppressed by an automatic gain control (AGC), thereby causing no problem effectually. However, in case of receiving broadcast waves from a remote station or under a weak receiving condition, its reception is likely to be affected by the radio frequency noise components due to a weak signal level of the received signal. 
     In order to solve this problem as described above, the power of the CD player may simply be turned off when receiving the broadcast waves. That is, when listening to a radio broadcast station, as it is not required to reproduce a CD, there will be no problem even if the power of the CD player is turned off. If the power of the CD player is turned off, the CD player no more produces radio frequency noise components, thereby preventing for the CD player to interfere with the reception of the broadcast waves. 
     However, as for the CD player, when the power thereof is turned on, it needs to initialize each section and read out information from a table of contents (TOC), accordingly, it is required a few seconds to complete all of these initializing processing. 
     Thereby, if the power of the CD player is arranged to be turned off during the reception of the broadcast waves, and when the source of the system stereo is switched from the AM broadcast tuner to the reproduction of a CD, a non-operable state of the system stereo occurs for such few seconds. 
     Of course, if the power of the CD player is kept turned on during the time of listening to the broadcast station, a CD can be immediately reproduced as soon as the source is switched from the reception of the broadcast station to the reproduction of CD. However, in this case, the above-mention problem of interference with the reception of broadcast waves is involved. The present invention is contemplated to solve the above-mentioned problems associated with the related art. 
     SUMMARY OF THE INVENTION 
     A novel audio apparatus provided according to an aspect of a preferred embodiment of the present invention is comprised of: a tuner unit for receiving broadcast; a digital reproducing unit; operating means for operating the tuner unit and the digital reproducing unit; a control unit for controlling the tuner unit and the digital reproducing unit in response to an operation of the operating means, wherein, in a first mode, when an audio signal outputted from the tuner unit is selectively received, the control unit controls to turn on the power of the digital reproducing unit; and wherein, in a second mode, when an audio signal outputted from the tuner unit is selectively received, the control unit controls to turn off the power of the digital reproducing unit, then to turn on the power thereof when selecting the audio signal outputted from the digital reproducing unit. 
     In the system stereo according to a preferred embodiment of the present invention, the power of the CD player is controlled as shown in  FIG. 5 , wherein if a CD power flag “CDPWRF” is set “CDPWRF=1”, the power of the CD player is kept constantly ON thereby enabling to reproduce a CD instantly the function key is pushed, thus enabling the switching circuit to be switched to the CD player. 
     Alternatively, if it is set “CDPWRF=0”, and if a broadcasting is being received, the power of the CD player is turned off. Thereby, in the case where a low level weak signal from a remote broadcasting station is being received, the interference by the radio frequency noise component from the CD player can be prevented. Namely, a user is able to select the defect to be eliminated of the system stereo by selecting operation mode according to the present invention. 
     Further, in a case where a new switch for switching the CD power flag “CDPWRF” is to be provided, it incurs an increase in the cost and a problem in determining where the new switch is to be installed. However, in the system stereo according to a preferred embodiment of the present invention, as it is arranged such that the switching of the CD power flag “CDPWRF” is effected only when a simultaneous operation of plural keys is executed, provided that the conditions (1) to (3), to be described later, are satisfied, wherein such combination of plural keys is most unlikely to occur in the normal use, and accordingly there is no need for providing any new key. Therefore, the increase in the cost and the problem of installing any additional new key are eliminated. Also, an erroneous operation of the keys is reduced. 
     The radio frequency noise components in the vicinity of AM band generated in the CD player are noted to have caused a significant problem to interfere, in particular, with the AM band. However, it should be noted also that it may interfere with the FM band. Further, other radio frequency noise components generated in other digital reproducing units, other than the CD player, such as a MD recording/reproducing unit, digital audio tape (DAT) recorder, digital versatile disc (DVD) player may also interfere with the AM band, FM band, or TV broadcasting. To such problems, the present invention is applicable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will become more apparent from the following description of the presently preferred exemplary embodiment of the invention taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram showing a configuration of an audio signal circuitry in a system stereo according to an embodiment of the present invention, 
         FIG. 2  is a schematic diagram showing a configuration of a power circuitry therein, 
         FIG. 3  is a flowchart showing procedures of operations according to the embodiment of the invention, 
         FIG. 4  is a flowchart showing the details of a part thereof shown in  FIG. 3 , 
         FIG. 5  is a block diagram showing exemplary modes of operation according to the present invention, and 
         FIG. 6  is a frontal view of the system stereo according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     At first, configuration of an audio signal circuitry and its basic operations of the invention is described. 
       FIG. 1  is a schematic diagram showing an audio signal circuitry in a system stereo according to an exemplary embodiment of the present invention. This exemplary embodiment specifies such one operable on AM/FM broadcasting, a CD and a cassette as its source, and, in addition, an MD recording/reproducing unit which is optionally connected. An appearance thereof as viewed from its front is given in  FIG. 6 . 
     By referring to  FIG. 1 , this system stereo has, as its sources, an AM/FM tuner  21 , a cassette tape deck  22 , a CD player  23 , and a line input terminal  24 . In this embodiment, the AM/FM tuner  21  which is a synthesizer type tuner and has a microcomputer (not shown) for control of reception, is constructed to be able to change a receiving band and a receiving frequency freely in response to a command accompanying data sent from a microcomputer  30  for use in a system control (to be described later). 
     Also, the cassette tape deck  22  and the CD player  23  have a microcomputer (not shown) for control of its operation, and are arranged to be able to change the operation mode thereof freely in response to the command and data from the microcomputer  30 . Further, the input terminal  24  is connected to an external source optioned such as MD recorder/reproducer  50  for supplying optional audio signals therefrom. 
     Then, audio signals from the AM/FM tuner  21 , cassette tape deck  22 , CD player  23  and input terminal  24 , i.e., those from the sources  21  to  24  are supplied to a switching circuit  25  which is provided for input source selection. This switching circuit  25  is controlled by the microcomputer  30  in response to an output (an instruction) from one of the function keys  15  so that a particular audio signal from a particular source from among a plurality of audio signals from a plurality of sources  21  to  24  is selected to be selected in response to the instruction entered via the function key  15 . 
     Then, the audio signal selected via the switching circuit  25  is supplied to an amplifier  26 , worked on processing of volume control, tone control, sound field calibration and so on, after then, supplied to left and right channel speakers  28 L and  28 R via output terminals  27 L,  27 R. 
     The microcomputer  30  for use of the system control as described above has a central processing unit (CPU)  31 , a read only memory (ROM)  32  and a non-volatile memory  33 . Various  20  programs for controlling the system stereo are stored on this ROM  32 , and as a part of these programs, for example, routine  100 , routine  200  as shown in  FIGS. 3 and 4  are provided. The routines  100 ,  200  will be described more in detail later. In  FIGS. 3 and 4 , however, more specific parts thereof relating  25  to the present invention are extracted and shown. 
     The memory  33  is also used to retain information and data relating to a set-up or initialize of the system stereo, operational conditions thereof and the like. For example, if a power off operation is performed, data on the set-up or  30  initialize and its current operational state of the system is saved, and then if a power on operation for initializing the system stereo is performed, the preceding state of the system prior to the power off operation is restored. 
     Further, the microcomputer  30  is connected to a power key  14 , function keys  15 , volume up and down keys  16   a ,  16   b , operation mode control keys  17  which include a record key, a playback key, a pause key, a rewind key, a music return key, a stop key, a music forward key, a quick forward key, etc., and also to a display  11 . Various control signals are outputted from the microcomputer  30  and supplied to the sources  21  to  23 , switching circuit  25  and the amplifier  26 , respectively. 
     By way of example, as for the operation mode control keys  17 , the record key is shared as a common key by the cassette tape recorder and the MD player, while the playback key, pause key, rewind key, music return key, stop key, music forward key and quick forward key are shared as common keys by the CD player, the cassette tape recorder and the MD player. In addition, the music return key and the music forward key are also used as a search key of a broadcast station for the tuner. Switching over between these keys is effected by pushing the function keys  15 . 
     Thereby, if one of the function keys  15  is operated, the switching circuit  25  is controlled by the microcomputer  30  to select an audio signal of a particular source selected from the sources  21  to  24  corresponding to the operation of the function keys  15 , and this selected audio signal is outputted as a reproduced sound from the speakers  28 L,  28 R. If the up or down keys  16   a ,  16   b  are operated at this instant, the level of the audio signal is changed by the amplifier  26  so as to adjust a volume level of the reproduced sound. 
     Still further, a prescribed display signal is formed in the microcomputer  30  to be supplied to the display  11 , whereby particular source information, for example, a frequency of broadcast if during reception of a radio station is displayed on the display  11 , or a track number, an elapsed time and the like is displayed if during reproduction of a CD. 
     Next, a configuration of the power circuitry and basic operation thereof is described. 
       FIG. 2  is a schematic block diagram showing an example of a power circuitry of the system stereo described above. Namely, a commercial AC voltage is supplied via a power plug  41  to a power circuit  42  and rectified to a prescribed stable DC voltage VDC. This DC voltage VDC is supplied to the microcomputer  30  as an operational voltage. 
     Further, the DC voltage VDC from the power circuit  42  is also supplied via the switching circuit  43  to the AM/FM tuner  21 , cassette tape deck  22 , amplifier  26  and the display  11  as their operating voltage. Also, the DC voltage VDC outputted from the switching circuit  43  is supplied to the CD player  23  via a switching circuit  44  as its operating voltage. Further, a prescribed control signal is outputted from the microcomputer  30  and supplied to the switching circuits  43 ,  44  as their control signals. 
     Then, if the user operates the power key  14 , the microcomputer  30  discriminates this operation, and in response to a control signal from the microcomputer  30 , the switching circuit  43  is controlled to be turned on or off. In this instance, the state of the turn on and off of the switching circuit  43  is alternatively reversed every time the power key  14  is pushed. Thereby, every time the power key  14  is depressed, the power supply to this system stereo is switched over between ON and OFF. 
     Further, as will be described later, in dependence on a state of use of the CD player  23 , the switching circuit  44  is controlled to become ON or OFF in response to a control signal from the microcomputer  30 , thereby controlling the power supply to the CD player  23 . 
     Now, the control of the power supply to the CD Player is described. 
       FIG. 5  shows an example of a power supply mode of the CD player  23 . In this drawing of  FIG. 5 , a symbol “CD power flag CDPWF” indicates a flag for controlling the power of the CD player  23 . Every time the user carries out a prescribed key operation, a value of this flag is switched alternatively between “0” and “1”, for example, by the routine  100 . 
     In the case of the routine  100 , the switching of this flag “CDPWRF” is carried out if all of the following conditions (1) to (3) are met.
     (1) The power of the system stereo is OFF as viewed from the user,   (2) In the condition of the above (1), a prescribed key operation is executed, for example, while depressing the stop key in the operation mode control keys  17 , the power key  14  is pushed in conjunction therewith, and   (3) In the condition of the above (2), the switching circuit  25  is selected the CD player  23 .   

     By way of example, the flag “CDPWRF” is stored in a non-volatile memory  33 . 
     In dependence on the switching of the function keys and a value of the CD power flag “CDPWRF”, the power mode of the CD player  23  is controlled as shown in  FIG. 5 . That is, although this control is executed by a routine  200 , if the function key  15  selects reception of broadcasting (the switch  25  selects AM or FM reception signal outputs from the AM/FM tuner  21 ), and if “CDPWRF=1”, the power of the CD player  23  is set ON. It is noted here that even if the function key selects any source other than the broadcasting, the power of the CD player is set ON. 
     However, if the function key  15  selects reception of broadcasting and if “CDPWRF=0”, the power of the CD player  23  is turned OFF. Further, if the function key  15  selects another source other than reception of the broadcasting, then, irrespective of the values of the flag “CDPWRF”, the power of the CD player  23  is set ON. 
     The routines  100  and  200  provided for realizing the above-mentioned processing have the following instructions. Namely, if the commercial AC voltage is connected to the power plug  41 , processing by CPU  31  in the microcomputer  30  starts at step  101  in the routine  100 , then in step  102 , initialization of respective units is executed. In this initialization step, “CDPWRF=1” is assumed (default). By way of example, at this time, although the power of each unit becomes ON, the power of the system is OFF when viewed from the user. 
     Subsequently, the process moves from step  102  to step  111 . In this step  111 , the process is in a standby mode waiting for operation of the power key  14 . That is, if the user pushes the power key  14  in this mode, this system stereo becomes operable instantly. 
     Switching of the CD power flag “CDPWRF” is described as follows. 
     In case of switching the CD power flag “CDPWRF”, in the off-state of the power (under the condition (1) described above), a prescribed key operation is performed, i.e., the power key  14  is pushed while also pushing the stop key in the operation mode control keys  17 . Then, upon the push down operation of the power key  14 , the process moves from step  111  to step  112 . In step  112 , whether or not the stop key in the operation mode control keys  17  is pushed is determined. In this instance, as an elapsed time from the operation of the step  111  to that of step  112  is instantaneous, as a result, it is considered to verify simultaneous operations (push-down) of both the stop key and the power key  14  in the step  112 . 
     In this instant case, because both the stop key and the power key  14  are pushed simultaneously as prescribed (the condition (2) holds), the process moves from step  112  to step  113 . In this step  113 , by judging whether or not the switching circuit  25  is selected the CD player  23 , it is determined for the function whether it is switched to the CD or not. 
     If determined to be switched to the CD (if the condition (3) holds), the step moves from step  113  to step  121 . In this step  121 , its CD power flag “CDPWRF” is reversed. That is, if currently “CDPWRF=1”, it is reversed to “CRPWRF=0”, alternatively if currently “CRPWRF=0”, it is reversed to “CDPWRF=1”. By way of example, in no steps other than this step  121 , the CD power flag “CDPWRF” will be operated. 
     Subsequently, the process advances to step  122 . In step  122 , the switching circuit  43  is controlled to become ON, thereby turning on the powers of the AM/FM tuner  21 , cassette tape deck  22 , amplifier  26  and display  11 . Then, the step goes to step  123 . In this step  123 , a prescribed display signal is supplied to the display  11 , and a power mode of the CD player  23  is displayed on the display  11 . 
     That is, if “CDPWRF=1”, a message “CD POWER ON” is displayed on the display  11 , and if “CDPWRF=0”, a message “CD POWER OFF” is displayed thereon. Then, after this message indicating the power mode of the CD player  23  is displayed, for example, for 3 seconds, the process jumps from step  123  to step  132 . 
     Therefore, whenever the operation under conditions (1) to (3) is executed, the CD power flag “CDPWRF” is alternatively switched between “0” and “1” for each operation. Further, in accordance with a result of its switching, the power mode of the CD player  23  is displayed on the display  11 . 
     In the step  113 , if the function is not switched to CD player  23  (if the condition (3) does not hold), the process returns from step  113  to step  111 , and thus the switching of the CD power flag “CDPWRF” is not executed. 
     By way of example, the accomplishment of the condition (2) is determined by a prescribed key operation, for example, a simultaneous push-down operation of a plurality of keys, i.e., the stop key in the operation mode control key  17  and the power key  14  in combination. In this instance, the stop key and the power key already exist, and this combination of the two keys to be operated simultaneously is selected from those that are most unlikely to occur in a normal use. 
     Operation of normal use is described with regard to the power control of the CD Player  23 . 
     In case of a normal use, for example, such as receiving broadcasting or reproducing a CD, the power key  14  is pushed alone if the power is cut off. Then, the process advances from step  111  to step  131  via step  112 . In this step  131 , the switching circuit  43  is controlled to become ON, thereby causing the powers of the AM/FM tuner  21 , cassette tape deck  22 , amplifier  26  and display  11  to be turned on. 
     Subsequently, the process goes to step  132 . In this step  132 , on the basis of information saved in memory  33 , a preceding switching position in the switching circuit  25 , a preceding audio signal level in the amplifier  26  and the like are read out to restore a previous state immediately before the power was cut off last time. Then, the process goes to step  133 . 
     In this step  133 , the routine  200  is called in and executed, and then the power of the CD player  23  is controlled as shown in  FIG. 5 . Also by referring to  FIG. 4 , when the processing of CPU  31  is transferred to routine  200 , it starts at step  201 , and in a subsequent step  202 , it is judged whether or not the switching circuit  25  is switched to the output of the AM/FM tuner  21 . 
     Then, if the switching circuit  25  is switched to the output of the AM/FM tuner  21 , the process goes from step  202  to step  203 . In this step  203 , its CD power flag “CDPWRF” is judged. If “CDPWRF=0”, the process goes from step  203  to step  204 . In this step  204 , the switching circuit  44  is controlled to become OFF, thereby causing the power of the CD player  23  to be turned off. Then, in step  206 , the routine  200  ends, and the process returns to the routine  100 . 
     Further, in step  202 , if the switching circuit  25  is switched to any source other than the output from the AM/FM tuner  21 , the process jumps from step  202  to step  205 . Also, in step  203 , if “CDPWRF=1”, the process jumps from step  203  to step  205 . In this step  205 , the switching circuit  44  is controlled to become ON, thereby causing the power of the CD player  23  to be turned on. Subsequently, in step  206 , the routine  200  is ended. 
     Therefore, according to the routine  200 , corresponding to the status of function switching and the value of the CD power flag “CDPWRF” while the routine  200  is executed, the power of the CD player  23  is controlled as shown in  FIG. 5 . 
     As a result, if the power key  14  is pushed alone when the power is OFF, the powers of the AM/FM tuner  21 , cassette tape deck  22 , amplifier  26  and display  11  are turned on in step  131  ( FIG. 3 ), and at the same time, the power of CD player  23  is controlled to become ON or OFF in step  133  in routine  200  ( FIGS. 3 and 4 ). That is, the power of the system stereo becomes ON as viewed from the user. 
     Then, the process of CPU  31  in routine  100  after step  133  goes to step  140 . In this step  140 , in accordance with the operations of function keys  15 , volume key  16  and operation mode control keys  17 , a switching operation between the sources  21  to  24 , control of volume and the like are executed, thereby allowing this system stereo to be used in a normal mode of operation as designated by the operation of the keys  15  to  17 . 
     However, in this step  140 , it should be noted that, every time the switching circuit  25  is switched over by the operation of the function keys  15 , the routine  200  is called in and executed so as to control the power of the CD player  23  as shown in  FIG. 5 . 
     Then, in any state of use, if the power key  14  is pushed, the operation of which is discriminated by step  141  in routine step  140 , the process goes from step  141  to step  151 . In this step  151 , the information at use in step  132  is saved in memory  33 . In the following step  152 , the switching circuits  43  and  44  are disconnected thereby cutting off the power of the system. Then, the process returns to step  111 . 
     Thereby, if the power key  14  is pushed under this condition of the power OFF, this system stereo can be used as a normal system stereo.