Patent Publication Number: US-2006012685-A1

Title: Wireless surveillance and communications system

Description:
BACKGROUND OF THE INVENTION  
      Field of the Invention  
      The present invention relates to audio and video surveillance systems. More particularly, one or more camera systems capture video and audio information, and transmit the information wirelessly to a monitor system. The system also allows transmission of audio information from the monitor system to the one or more camera systems, allowing two-way audio communication between users at both locations.  
      Prior surveillance systems initially transmitted across wires. Early wireless systems transmitted audio only, then video only, and finally audio and video. Some systems were black and white, or used less than 24 frames per second, resulting in less than full motion.  
      Recent systems have transmitted in color at full motion frame rates, but suffer from several other issues. Many systems are designed to be viewed on a standard television or monitor. Therefore, they transmit at VHF frequencies, somewhere less than 300 MHz. These systems suffer from two main drawbacks. First, the range of transmission is very low, particularly with low power transmitters and through objects, such as walls and ceilings. Second, the television or monitor generally has not been portable.  
      Other systems have transmitted at higher frequencies, allowing them to be designed to be viewed on a portable monitor. However, the designers have had to make a significant tradeoff with these systems.  
      Cameras using a charge coupled device (CCD) provide increased sharpness over cameras using a complementary metal oxide semiconductor (CMOS). Where a CMOS camera may sharply define a subject at 12 feet, a CCD camera can equally define a subject at 40 feet. Therefore, designers would prefer to use CCD cameras over the inferior CMOS cameras.  
      CCD cameras require more advanced circuitry than CMOS cameras. This circuitry tends to heat up more than the CMOS counterparts. At transmission frequencies of up to 1.2 GHz, this heat does not pose a significant problem. Therefore, transmission systems using CCD cameras were available at up to 1.2 GHz frequencies. While this transmission frequency provides increased range and picture quality over VHF frequencies, it is still very susceptible to walls and other objects in the line of transmission.  
      It would have been preferable to transmit at 2.4 GHz. However, because the cameras and transmission circuitry needed to be in a relatively compact space, the additional heat from the CCD camera circuitry posed a significant problem. The signal would degrade, and eventually the transmission would fail completely. Therefore, prior 2.4 GHz systems would be limited to CMOS cameras, which ran at lower heat. The tradeoff, as stated above, is much lower camera capture quality.  
     SUMMARY OF THE INVENTION  
      According to one aspect of the present invention, a camera system is provided for use in a wireless transmission system. The camera system includes a camera body mounted on a supporting base. A lens is mounted to and a CCD image sensor is mounted within the camera body. A microphone is mounted on the supporting base. Wireless transmission system circuitry is located within the supporting base, to transmit light received by the CCD image sensor and sounds received by the microphone. The circuitry transmits on a frequency of at least 2.4 GigaHertz.  
      The camera body may be mounted on the supporting base to allow rotation up, down, left, and right. To facilitate this, the camera body may be mounted on a supporting arm, which is in turn mounted to the supporting base. The supporting arm can rotate relative to the supporting base in a first plane, and the camera body can rotate relative to the supporting arm in a second plane substantially orthogonal to the first plane.  
      The supporting arm may be substantially hollow, and the CCD image sensor may be connected to the wireless transmission system circuitry by a wire which runs substantially through the hollow supporting arm, from the camera body to the supporting base.  
      The camera system may include a light source mounted near the lens, to illuminate the area generally in front of the lens, and to thereby increase the light received through the lens. The light source may provide visible or infrared light, and may be a plurality of light emitting diodes. The light emitting diodes may be arranged in a plurality of concentric circles around the lens.  
      The camera system may include a wireless reception system in the supporting base for receiving signals from a remote transmitter. The signals may be audio signals which can then be projected by a speaker.  
      According to another aspect of the present invention, a monitor system is provided to receive wirelessly transmitted signals, and to display images and project audio from those received signals. The monitor system may be portable, and may be powered by batteries or alternating current power. The batteries may be rechargeable, and the alternating current power may also recharge the batteries while simultaneously powering the system. Again, the transmission frequency is at least 2.4 GigaHertz.  
      The monitor system may receive signals from more than one remote source. The monitor system may display images and project sounds corresponding to one remote source for a predetermined period of time, then switch to another source. Preferably, the monitor system includes controls to allow a user to select one of the sources for display and projection.  
      Additionally, the monitor system may include a microphone to receive audible sounds, and a wireless transmission system to transmit that audio information to a remote receiver. The microphone may have an activation control, or may automatically activate when audio sounds are detected. In the case where the monitor system can receive signals from more than one remote source, one aspect of the system transmits signals only to the remote receiver corresponding to the remote source whose signals are being displayed and projected. Another aspect of the system transmits signals to all receivers corresponding to all remote sources operably connected to the monitor system.  
      In combination, the monitor system and one or more camera systems make a complete wireless surveillance and communications system.  
      According to yet another aspect of the present invention, a wireless reception system is provided. The wireless reception system includes a receiver adapted to wirelessly receive video and audio signals from a plurality of remote sources at a frequency of at least 2.4 GigaHertz. It also includes a plurality of source selector controls and source indicators, one for each remote source. The controls allow a user to selectr a particular source, and the indicator indicates which source is selected. There is also a scan selector control, directing the system to alternately select each remote source for a predetermined period of time. Finally, there is an output jack, to output signals from the currently selected source to a display and speaker. The output jack may be a coaxial cable jack.  
      The predetermined period of time can be selected or modified by a user, and can be different for each remote source. There can also be an additional audio/video output. The system may include a remote control, allowing a user to select any of the controls or to modify the predetermine period of time remotely. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings wherein:  
       FIG. 1  shows a camera system, according to the prior art.  
       FIG. 2  shows a monitor system, according to the prior art.  
       FIG. 3  shows a block diagram of a surveillance system, according to the prior art.  
       FIG. 4  shows an embodiment of a camera system, according to the present invention.  
       FIG. 5  shows an embodiment of a monitor system, according to the present invention.  
       FIG. 6  shows an alternate embodiment of a wireless reception system, according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring to  FIG. 1 , there is shown a camera system  1  according to the prior art. A camera body  3  includes a lens  5 . The lens  5  focuses light onto a one-quarter inch CCD or a CMOS sensor (not shown), positioned within the camera body  3 . The camera body  3  may be mounted on a stand  7 . There is also a microphone  9  attached to the rear of the camera body  3 , for receiving sound.  
      Surrounding the lens  5  are light emitting diodes  11 . These light emitting diodes  11  may emit visible light or infrared light. The light emitting diodes  11  increase the illumination of the subject being viewed by the lens  5 , thereby increasing the light on the CCD or CMOS sensor.  
      Referring to  FIG. 2 , there is shown a monitor system  13 , according to the prior art. A housing  15  contains an LCD monitor  17 , for displaying images. The housing  15  also contains a speaker (not shown) for projecting audible sound. Located on the housing  15  are a plurality of input selector buttons  19 , for selecting image and audio signals from a plurality of sources.  
      Referring to  FIG. 3 , the operation of a prior art wireless surveillance system including a camera system  1  and a monitor system  13  is shown. A CCD or CMOS sensor  23  and microphone  9  within or on the camera body  3  each send signals to a wireless transmission system  25 . The wireless transmission system  25  is also located within the camera body  3 . The wireless transmission system  25  transmits the audio and image information to a wireless reception system  27 , located in the housing  15 . As stated earlier, if the sensor  23  is a CCD, then the transmission occurs at no greater than 1.2 GHz. If the sensor  23  is a CMOS, then the transmission can occur at up to 2.4 GHz. The wireless reception system  27  separates the received signals into image signals, which are then passed to the LCD monitor  17  for display, and audio signals, which are then passed to a speaker  29  for projection.  
      For CCD camera systems, the wireless transmission system  25  and wireless reception system  27  are designed to transmit NTSC signals on a frequency of 1.2 GHz. This frequency presents several problems. First, picture quality is not optimal, compared with 2.4 GHz. Second, interference often occurs, further degrading picture quality. Third, because the system is designed to transmit signals to a remote location often through walls or other obstructions, transmission range is severely limited.  
      For CMOS camera systems, the wireless transmission system  25  and wireless reception system  27  can transmit at frequencies up to 2.4 GHz. However, CMOS camera systems are inferior to CCD camera systems. Therefore, the initially captured picture is of a much lower quality than with CCD camera systems.  
      Referring to  FIG. 4 , there is shown a camera system  31  according to the present invention. A camera body  33  includes a lens  35 . Located within the camera body  33  is a CCD optical image sensor (not shown). The CCD optical image sensor receives the light through the lens  35 , and converts the image to a digital signal suitable for transmission. The camera body  33  is mounted to a supporting arm  37 , which is in turn mounted on a supporting base  39 . The camera body  33  may be rotated up or down relative to the supporting arm  37 , and the supporting arm may be rotated left or right relative to the supporting base  39 . These two ranges of motion allow the camera body  33  to pan up, down, left, or right.  
      The supporting arm  37  is hollow. Wires (not shown) extend from the CCD optical image sensor in the camera body  33 , out through the supporting arm  37 , and down into the supporting base  39 . Once inside the supporting base  39 , the wires connect to the transmission circuitry (not shown). By removing the transmission circuitry from the camera body  33  into the supporting base  39 , the problems associated with transmitting CCD camera images at 2.4 GHz are removed, and transmission can occur at 2.4 GHz or higher frequencies. The supporting base  39  can provide adequate ventilation to cool the transmission circuitry, and the distance between the transmission circuitry and the CCD optical image sensor is increased. Despite this, the camera system  31  remains both compact and portable.  
      Surrounding the lens  35  are several light emitting diodes  40  for illuminating the area in front of the lens  35 . Preferably, the light emitting diodes  40  are arranged in substantially concentric circles, and most preferably there are two substantially concentric circles. The light emitting diodes  40  may be visible light, infrared light, or any other suitable illumination. The light emitting diodes  40  increase the illumination of the subject being focused on by the lens  35 , thereby increasing the amount of light passed to the CCD optical image sensor. Light sources other than light emitting diodes  40  may be used.  
      Located on the front face of the supporting base  39  is a microphone  43 . The microphone  43  receives audio signals, and is connected to the transmission circuitry, to allow the circuitry to transmit audio signals along with the corresponding images.  
      Locating the microphone  43  on the front face of the supporting base  39  provides several advantages. First, unlike prior art surveillance systems where the microphone  9  was mounted on the camera body  3 , the microphone  43  is facing the subject. This increases the range of the microphone  43 . Additionally, space is not at such a premium on the supporting base  39  as it is on the camera body  3 , so the microphone  43  can be larger. This also increases range and sensitivity.  
      The camera system  31  also uses rechargeable batteries (not shown). Preferably, these batteries are lithium-ion batteries, and are located in the supporting base  39 .  
      An antenna  45  is attached to the supporting base  39 . The antenna  45  facilitates transmission of image and audio signals, and reception of audio signals from a remote location.  
      A speaker (not shown) may be located on the supporting base  39 . In a two-way communication system, the antenna  45  may receive signals from a remote location, which are translated into audio signals by reception circuitry (not shown), also located in the supporting base  39 . The speaker would then project these audio signals, allowing full two-way communication between the camera system  31  and a remote location.  
      Referring to  FIG. 5 , there is shown a monitor system  47 , according to the present invention. A housing  49  contains a wireless reception system (not shown) for receiving image and audio signals from a remote source. The remote source may be a camera system  31  according to the present invention, a camera system  1  according to the prior art, or any other suitable transmitter. The wireless reception system converts the received signals into images for display on a LCD color visual display  51 , and into audio signals to be projected by a speaker (not shown). For a silent mode, the speaker can be disabled or muted.  
      Located on the housing  49  are a plurality of input selector buttons  53 , for selecting image and audio signals from a plurality of remote sources. Preferably, the housing  49  is connected to a stand  57 , which can be extended to allow the housing  49  to rest at a comfortable viewing angle. The stand  57  can also be retracted flat against the housing  49 , to facilitate portability.  
      The housing  49  preferably includes a condenser microphone (not shown), to convert sound in to signals suitable for transmission. The signals can then be transmitted by a wireless transmission system (not shown) located within the housing  49 , to a remote receiver, such as the camera system  31 . The housing  49  may also include a microphone jack (not shown), to allow connection of an external microphone.  
      Either the condenser microphone or the external microphone may be controlled in a variety of ways. Either one could automatically activate upon receiving audio sounds of a predetermined level. This predetermined level could be adjusted by a user. With this “auto-on” activation, the wireless transmission system would also automatically transmit signals corresponding to the audio signals.  
      More preferably, the housing  49  could include a microphone control (not shown), which is selectively activated by a user and activates one of the microphones. The microphone control could also activate the wireless transmission system. The microphone control could be a sensitivity control, such as a dial, a button, or any other suitable control.  
      The input selectors  53  control which received images are displayed on the LCD color visual display  51 , and which received audio signals are projected by the speaker. Additionally, the input selectors  53  could control to which remote receiver the wireless transmission system transmits the audio signals from the condenser microphone or external microphone.  
      The monitor system  47  contains a power source (not shown). The preferred power source is direct current batteries. The batteries are preferably rechargeable, and most preferably are four AA batteries. The housing  49  also may contain an input (not shown) for an alternating current power supply as a second power source. Preferably, the alternating current power supply would provide sufficient power to operate the monitor system  47 , and simultaneously recharge the batteries.  
      Referring to  FIG. 6 , there is shown an alternate embodiment of a wireless reception system  59 . This wireless reception system  59  is suitable for use with any of the same transmitters that can be used with the monitor system  47 , but allows additional display options. The wireless reception system  59  contains a wireless receiver (not shown), capable of receiving signals from a plurality of sources. The wireless reception system  59  has a housing  61  containing an input selector button  63  for each of the possible sources. There is also a light emitting diode  65  for each of the input selector buttons  63 . When the user depresses one of the input selector buttons  63 , the corresponding light emitting diode  65  illuminates, indicating that the particular input source is selected. The light emitting diode  65  will also illuminate when the particular input source is selected by methods other than depressing the input selector button  63 , as discussed more thoroughly below.  
      There is also a control button  67  and light emitting diode  69  for an auto-scan feature. When the user depresses the control button  67 , the light emitting diode  69  illuminates, indicating that the wireless reception system  59  is in auto-scan mode. In this mode, the wireless reception system  59  will scan through the input sources in order, for a predetermined period of time. As each input source is selected, the corresponding light emitting diode  65  illuminates, along with the light emitting diode  69  for the auto-scan feature.  
      The housing  61  also has up and down buttons  71 . These up and down buttons  71  allow the user to specify the length of time that a particular input source will be selected during the auto-scan feature. For example, the default selection time may be one second. The user will depress one of the input selector buttons  63 . To display the corresponding input source for longer, the up button  71  will be pressed one or more times. To display the corresponding input source for a shorter time, the down button  71  will be pressed one or more times. The user will then press a different input selector button  63 , and repeat the process with the up and down buttons  71 . When the user selects the auto-scan feature by pressing the control button  67 , the wireless reception system  59  will scan through the input sources in order, each for the preset time.  
      Regardless of the mode of operation, when a particular input source is selected, the wireless reception system  59  outputs the signal from that source onto a variety of outputs. The first alternative is a coaxial cable output  73 , which can connect to a standard coaxial cable. Of course, the wireless reception system  59  has internal circuitry to convert the received signal to the appropriate output signal. The second alternative is audio/video outputs  75 . Other suitable outputs are possible. This variety of outputs allows the wireless reception system  59  to display or project onto a television, monitor, personal computer, VCR, or any other suitable display. The monitor system  47  may also include audio/video inputs (not shown) to display signals received by the wireless reception system  59 .  
      The wireless reception system  59  is also adapted to operate by remote control. Each of the controls on the housing  61  can have a counterpart control on a remote control (not shown). The remote control may operate by infrared, through an infrared sensor (not shown) on the housing  61 , or by any other suitable remote transmission means.  
      While this invention has been described in detail with reference to certain preferred embodiments, it should be appreciated that the present invention is not limited to those precise embodiments. Rather, in view of the present disclosure, which describes the current best mode for practicing the invention, many modifications and variations would present themselves to those of skill in the art without departing from the scope and spirit of this invention. The scope of the invention is, therefore, indicated by the following claims rather than the foregoing description. All changes, modifications, and variations coming within the meaning and range of equivalency of the claims are to be considered within their scope.