Abstract:
An audiovisual system including a circuit coupled to the first input and having an adjustable sensitivity control and a detector configured to detect the presence of a signal from the second input. The sensitivity control is responsive to the detector to set the sensitivity for a first input sensitivity level when the detector detects the presence of the signal from the second input and to set the sensitivity for a second input sensitivity level when the detector does not detect the signal from the second input.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to the field of audiovisual systems for vehicles, and more particularly, the invention relates to audiovisual systems for vehicles that allow for adjustment of the input sensitivity at which a signal from an auxiliary device is received. 
       BACKGROUND 
       [0002]    Portable entertainment devices have become common and include portable devices that generate audio output only, which are referred to herein as portable audio devices, as well as portable devices that generate both audio and video outputs, which are referred to herein as portable audiovisual devices. Examples of portable audio devices include digital music players, compact disc players, and cassette tape players. Examples of portable audiovisual devices include video game consoles, portable DVD players, and portable digital video players. 
         [0003]    The voltages of the audio output signals provided by different portable entertainment devices is not standardized, which can cause volume discrepancies during playback. For example, a portable audio device may provide an output signal at a voltage of 300 mV, while a portable audiovisual device may provide its audio output at a voltage of approximately 1 V. 
         [0004]    In response to the proliferation of portable entertainment devices, it has become common to include means for interfacing with portable entertainment devices in the audiovisual systems of vehicles. In a vehicle, volume discrepancies can cause driver distraction. For example, if an audio signal having a voltage of 1 V is provided to an automobile audiovisual system that is calibrated to receive input signals at 300 mV, the automobile audiovisual system will produce an abnormally loud output volume. If this occurs while a driver is operating the vehicle, the driver could become distracted by the unexpected change in volume. Conversely, if an audio signal having a voltage of 300 mV is provided to an audiovisual system that is calibrated to receive an audio input signal at 1 V, the resulting output volume will be abnormally soft, and the driver will likely increase the volume setting. Subsequently, when a different input source is selected, the automobile audio system may produce an abnormally loud output. 
         [0005]    One known method for accommodating audio input signals of differing voltages is to provide a manual switch, by which a user may manually change the input sensitivity of the audiovisual system. While effective, an affirmative action by the user is required, and the user may not remember to adjust the input sensitivity prior to beginning operation of the portable audiovisual device. Another method involves detecting the voltage of the audio signal provided by the portable audiovisual device and adjusting the input sensitivity of the audiovisual system accordingly. However, this solution requires complicated circuitry that increasing the total cost of the vehicle&#39;s audiovisual system. 
       SUMMARY 
       [0006]    The invention provides an audiovisual system that includes a first input and a second input. A circuit having an adjustable sensitivity control is coupled to the first input. A detector is configured to detect the presence of a signal from the second input. The sensitivity control of the circuit is responsive to the detector to set the sensitivity for a first input sensitivity level when the detector detects the presence of the signal from the second input. The sensitivity control is further responsive to the detector to set the sensitivity for a second input sensitivity level when the detector does not detect the signal from the second input. 
         [0007]    According to an embodiment, the first input includes at least one audio input jack, and the second input includes at least one video input jack. Furthermore, the at least one audio input jack could be an RCA-type audio input jack, and the at least one video input jack could be an RCA-type video input jack. 
         [0008]    In some embodiments, the audiovisual system may include an audio system that is coupled to the circuit, as well as a video display system that is coupled to the second input. 
         [0009]    By other embodiments, the first input can be selectively connectable to an audio output of at least one of a portable audio device or a portable audiovisual device, while the second input can be selectively connectable to a video output of the portable audiovisual device. 
         [0010]    In a further embodiment, the first input sensitivity level corresponds to a first predetermined voltage value, and the second input sensitivity level corresponds to a second predetermined voltage value. The first predetermined voltage value can be approximately 1 V. The second predetermined voltage can be approximately 300 mV. 
         [0011]    In some embodiments, the detector detects the presence of a video output plug and a video input jack by sensing a video signal that is provided to the video input jack by the video output plug. In other embodiments, the detector includes a mechanical switch to detect the presence of the video output plug and the video input jack by sensing engagement of the video output plug and the video input jack. 
         [0012]    The invention also provides a method for operating an audiovisual system that has an audio jack that is adapted for receiving an audio output plug, a video input jack that is adapted for receiving a video output plug, and an adjustable input sensitivity circuit. The method includes the steps of generating a control signal indicative of whether a plug is inserted into the video input jack, and setting the adjustable input sensitivity circuit in response to the control signal so that the input sensitivity is set at a first input sensitivity level when a video output plug is in the video input jack, and at a second input sensitivity level when no video output plug is in the video input jack. 
         [0013]    By one embodiment, the method further includes the steps of setting the first input sensitivity level corresponding to a first predetermined voltage value and setting the second input sensitivity level corresponding to a second predetermined voltage value. By another embodiment, the method includes the steps of setting the first predetermined voltage at approximately 1 V and setting the second predetermined voltage at approximately 300 mV. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0015]      FIG. 1A  is an illustration showing connection of a portable audio device to an audiovisual system according to the invention; 
           [0016]      FIG. 1B  is an illustration showing connection of a portable audiovisual device to the audiovisual system according to the invention; 
           [0017]      FIG. 2  is a block diagram showing an in-vehicle audio system having an automatic input sensitivity selector; and 
           [0018]      FIG. 3  is a flowchart showing operation of the automatic input sensitivity selector according to the first embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIGS. 1A-1B  show an audiovisual system  10  according to the invention that is selectively connectable to an auxiliary device, such as a portable audio device  1  or a portable audiovisual device  5 , so that the audiovisual system  10  can receive an input signal from the portable audio device  1  or the portable audiovisual device  5 . The audiovisual system  10  may be mounted in a vehicle (not shown). To receive the input signal, the audiovisual system  10  may have one or more audio and video jacks or combined audio/video jacks of any type now known or hereafter devised. For example, the audiovisual system  10  could have a plurality of RCA-type audio and video jacks, such as a left audio input jack  12 , a right audio input jack  14 , and a video input jack  16 . Alternatively, the audiovisual system  10  could receive the input signal wirelessly. 
         [0020]    The portable audio device  1  can be any device operative to produce audio output signals. The portable audio device  1  may be selectively connectable to the audiovisual system  10  by an audio cable  2 . The audio cable  2  may include a left audio input plug  3  and a right audio input plug  4 , which are selectively connectable to the left audio input jack  12  and the right audio input jack  14 , respectively. 
         [0021]    The portable audiovisual device  5  can be any device operative to produce one or more audio output signals and one or more video output signals, such as a video game console, a portable DVD player, a portable digital video player, etc. The portable audiovisual device  5  may be selectively connectable to the audiovisual system  10  by an audiovisual cable  6 . The audiovisual cable  6  may be an RCA-type audiovisual cable that has a left audio input plug  7 , a right audio input plug  8 , and a video input plug  9 , which are selectively connectable to the left audio input jack  12 , the right audio input jack  14 , and the video input jack  16  of the audiovisual system  10 . 
         [0022]    Although the portable audio device  1  and the portable audiovisual device  5  are described herein as selectively connectable to the audiovisual system  10  using the audio cable  2  and the audiovisual cable  6 , it should be understood that the portable audio device  1  and the portable audiovisual device  5  could be coupled to the audiovisual system  10  by other means. As an example, the invention could be applied to an audiovisual system  10  that is coupled to either a portable audio device  1  or a portable audiovisual device  5  by a single cable by utilizing a digital transmission, multiplexing, or other known methods. As another example, the audiovisual system  10  can be coupled to either of the portable audio device  1  or the portable audiovisual device  5  by a wireless connection. Moreover, any of the signal-transferring connections between components described herein can be achieved by coupling the components electrically, optically, wirelessly, or by any other means now known or hereafter devised, whether analog, digital, or otherwise. 
         [0023]    As shown in  FIG. 2 , the audio system receives a left audio input signal  18 , a right audio input signal  20 , and a video input signal  22 , which are input signals that correspond to the output signals provided by the portable audio device  1  or the portable audiovisual device  5 . The left audio input  18  and the right audio input  20  are coupled to an audio system  24  that has an adjustable audio signal characteristic, an adjustable sensitivity or an adjustable gain control. The audio system  24  conditions the signals provided by the left audio input signal  18  and the right audio input signal  20  and provides an adjusted signal or signals to one or more output devices, such as speakers  26 . 
         [0024]    The video input signal  22  is coupled to a signal detector  28 . The signal detector  28  is configured to detect the presence of a signal from the video input  22 . The signal detector  28  could detect the presence of a signal from the video input  22  by mechanically detecting the presence or absence of the video input plug  9  within the video input jack  16  of the audio visual system  10  using a switch that is engaged by the video input plug  9  upon insertion into the video input jack  16 . Alternatively, the signal detector  28  could detect the presence of the video input plug  9  within the video input jack  16  electrically, for example, by detecting the signal provided to the video input  22  by way of the video input jack  16  from the video input plug  9 . The signal detector  28  is coupled to the audio system  24  so that the audio system  24  can be responsive to the presence or absence of a video input signal  22 , as will be explained in detail herein. The signal detector  28  is further coupled to a video display system  30 , which receives and processes the video input signal  22  and then displays the processed video input signal  22  on an output device such as a video monitor  32 . 
         [0025]    As will be explained with reference to  FIG. 3 , the audio system  24  adjusts the audio signal characteristic of the audiovisual system  10  based on the presence or absence of the video input signal  22 . After the process starts in step S 40 , the audio system  24  determines whether or not the video input signal  22  is present in step S 423  based on input provided to the audio system  24  by the signal detector  28 . If the audio system  24  determines that the video input signal  22  is not present, the process proceeds to step S 44 . If the audio system  24  determines that the video input signal  22  is present, the process proceeds to step S 50 . In step S 44 , it is judged that a low audio input level is present, and the process proceeds to step S 46 . In step S 46 , the audio system  24  sets a high input sensitivity level, for example, 300 mV, and the process then ends at step S 48 . If the audio system  24  determined that the video input signal  22  was present in step S 42 , the audio system  24  judges that a high audio input level is present in step S 50 , and the process proceeds to step S 52 . In step S 52 , the audio system  24  sets a low input sensitivity level, such as 1 V, and the process then ends at step S 48 . 
         [0026]    In use, a user may connect either a portable audio device  1  or a portable audiovisual device  5  to the audiovisual system  10 . If the user couples a portable audio device  1  to the audiovisual system  10 , the signal detector  28  determines that the video input signal  22  is not present. In response to the absence of the video input signal  22  as determined by the signal detector  28 , the audio system  24  sets a high input sensitivity or high gain for the audio system  24  and adjusts the left and right audio input signals  18 ,  20  accordingly before passing those signals to the speakers  26 . 
         [0027]    If the user couples the portable audiovisual device  5  to the audiovisual system  10 , the signal detector  28  detects the presence of the video input signal  22 . In response to the presence of the video input signal  22 , the audio system  24  adjusts the left audio input signal  18  and the right audio input signal  20  according to a low input sensitivity value and passes the resulting audio output signal to the speakers  26 . 
         [0028]    Although the invention has been described in connection with an audiovisual system  10  having a single set input jacks, such as the left audio input jack  12 , the right audio input jack  14 , and the video input jack  16 , it should be understood that the invention is not limited to an audiovisual system  10  having a single set of input jacks. On the contrary, the audiovisual system  10  could have multiple sets of input jacks. For example, multiple sets of input jacks could be provided to allow simultaneous connection of the portable audio device  1  and the portable audiovisual device  5  to the audiovisual system  10 , and a user operated switch could be provided to allow the user to select which set of input jacks is utilized. In this case, the signal detector  28  would determine whether the video input signal  22  is present with reference to the set of input jacks selected by the user. 
         [0029]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.