Patent Publication Number: US-10785457-B2

Title: Audio/video recording and communication devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 15/456,560, filed on Mar. 12, 2017, which claims priority to provisional application Ser. No. 62/422,830, filed on Nov. 16, 2016, and provisional application Ser. No. 62/308,746, filed on Mar. 15, 2016. The entire contents of the priority applications are hereby incorporated by reference as if fully set forth. 
    
    
     TECHNICAL FIELD 
     The present embodiments relate to audio/video (AN) recording and communication devices, including A/V recording and communication doorbell systems. In particular, the present embodiments relate to improvements in the configuration and functionality of A/V recording and communication devices. 
     BACKGROUND 
     Home safety is a concern for many homeowners and renters. Those seeking to protect or monitor their homes often wish to have video and audio communications with visitors, for example, those visiting an external door or entryway. Audio/Video (A/V) recording and communication doorbell systems provide this functionality, and can also aid in crime detection and prevention. For example, audio and/or video captured by an A/V recording and communication doorbell can be uploaded to the cloud and recorded on a remote server. Subsequent review of the A/V footage can aid law enforcement in capturing perpetrators of home burglaries and other crimes. Further, the presence of an A/V recording and communication doorbell at the entrance to a home acts as a powerful deterrent against would-be burglars. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various embodiments of the present audio/video (A/V) recording and communication doorbells now will be discussed in detail with an emphasis on highlighting the advantageous features. These embodiments depict the novel and non-obvious A/V recording and communication doorbells shown in the accompanying drawings, which are for illustrative purposes only. These drawings include the following figures, in which like numerals indicate like parts: 
         FIG. 1  is a functional block diagram illustrating an A/V recording and communication doorbell system according to the present embodiments; 
         FIG. 2  is a flowchart illustrating a process for streaming and storing A/V content from an A/V recording and communication doorbell system according to various aspects of the present disclosure; 
         FIG. 3  is a functional block diagram illustrating an embodiment of an A/V recording and communication doorbell system according to the present disclosure; 
         FIG. 4  is a front perspective view of an embodiment of an A/V recording and communication doorbell according to the present disclosure; 
         FIG. 5  is a rear perspective view of the A/V recording and communication doorbell of  FIG. 4 ; 
         FIG. 6  is a partially exploded front perspective view of the A/V recording and communication doorbell of  FIG. 4  showing the cover removed; 
         FIGS. 7, 8, and 9  are front perspective views of various internal components of the A/V recording and communication doorbell of  FIG. 4 ; 
         FIG. 7A  is a front perspective view of another embodiment of an infrared (IR) light-emitting diode (LED) printed circuit board (PCB) according to various aspects of the present disclosure; 
         FIG. 10  is a right-side cross-sectional view of the A/V recording and communication doorbell of  FIG. 4  taken through the line  9 - 9  in  FIG. 4 ; 
         FIGS. 11-13  are rear perspective views of various internal components of the A/V recording and communication doorbell of  FIG. 4 ; 
         FIG. 14  is a flowchart illustrating a process according to various aspects of the present disclosure; 
         FIG. 15  is a functional block diagram illustrating an embodiment of a shunt according to the present disclosure; 
         FIGS. 16 and 17  are circuit diagrams illustrating embodiments of first and second comparator circuits, respectively, of the shunt of  FIG. 15 ; 
         FIGS. 18 and 19  are waveform diagrams for the first comparator circuit of  FIG. 16 ; 
         FIGS. 20 and 21  are waveform diagrams for the second comparator circuit of  FIG. 17 ; 
         FIGS. 22 and 23  are flowcharts illustrating processes according to various aspects of the present disclosure; 
         FIG. 24  is a schematic diagram of a technique for creating intrusion zones according to various aspects of the present disclosure; 
         FIG. 25  is a front perspective view of another embodiment of an A/V recording and communication doorbell according to the present disclosure; 
         FIG. 26  is a right-side perspective, cross-sectional, detail view of the A/V recording and communication doorbell of  FIG. 25  taken through the line  26 - 26  in  FIG. 25 ; 
         FIG. 27  is a functional block diagram illustrating another embodiment of an A/V recording and communication doorbell system according to the present disclosure; 
         FIG. 28  is a functional block diagram of a client device on which the present embodiments may be implemented according to various aspects of the present disclosure; and 
         FIG. 29  is a functional block diagram of a general-purpose computing system on which the present embodiments may be implemented according to various aspects of present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments of the present audio/video (A/V) recording and communication doorbells have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of the present embodiments as expressed by the claims that follow, their more prominent features now will be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description,” one will understand how the features of the present embodiments provide the advantages described herein. 
     One aspect of the present embodiments includes the realization that in current audio/video (A/V) recording and communication doorbell systems other than the present embodiments, it is difficult if not impossible to connect the A/V recording and communication doorbell to the existing household AC power supply (may also be referred to as AC mains), because the A/V recording and communication doorbell draws an amount of power from the AC power supply that is above the threshold necessary for causing the signaling device to sound. The A/V recording and communication doorbell thus causes frequent inadvertent sounding of the signaling device, which is not only bothersome to the home&#39;s occupant(s), but also undermines the usefulness of the doorbell. The present embodiments solve this problem by limiting the power consumption of the A/V recording and communication doorbell to an amount that is below the threshold necessary for causing the signaling device to sound. The present A/V recording and communication doorbell can thus be connected to the existing household AC power supply and the existing signaling device without causing inadvertent sounding of the signaling device. 
     Another aspect of the present embodiments includes the realization that, in current A/V recording and communication doorbell systems other than the present embodiments, using the camera alone for detecting motion may have drawbacks under certain circumstances. For example, during nighttime hours the level of ambient light about the doorbell may be low. Since the camera detects motion by comparing successive video frames, if there is inadequate light to illuminate the field of view of the camera, then the camera may be unable to detect changes in successive video frames. Providing an illumination source, such as infrared LEDs, during nighttime hours may compensate for this issue. However, infrared LEDs may have range limitations. For example, infrared LEDs may not be well suited for illuminating the camera&#39;s field of view beyond a certain distance, such as about fifteen feet. The present embodiments solve this problem by providing a motion sensor in addition to the camera. For example, in some of the present embodiments the motion sensor may comprise one or more passive infrared (PIR) sensors. PIR sensors detect changes in the amount of IR radiation impinging upon them, which varies depending on the temperature and/or surface characteristics of the object(s) in front of the sensors. PIR sensors are thus effective at detecting motion even under low light conditions, particularly motion of persons and other objects that generate heat. Further, the PIR sensors may be effective at detecting objects at great distances from the camera, such as thirty feet or more. The PIR sensors thus may provide increased range as compared to infrared LEDs. In some of the present embodiments, therefore, the PIR sensors enhance the motion detecting capabilities of the doorbell, particularly when there is a low level of ambient light about the doorbell. In some embodiments, one or more of the PIR sensors may comprise a pyroelectric infrared sensor. 
     Yet another aspect of the present embodiments includes the realization that, in current A/V recording and communication doorbell systems other than the present embodiments, under nighttime or low ambient light conditions reflected infrared light can confuse the camera as to the actual light intensity in the camera&#39;s field of view. For example, if the doorbell is located opposite a wall or other structure that reflects a significant amount of the infrared light from the infrared light source, the image seen by the camera may appear to be very bright, which may confuse the camera as to the actual light intensity level in the field of view. The present embodiments solve this problem by providing a light sensor in addition to the camera. The light sensor may be configured to detect light in both the infrared and visible spectrums, and to provide information to the processor about the intensity of light in these spectrums in the camera&#39;s field of view. 
     The following detailed description describes the present embodiments with reference to the drawings. In the drawings, reference numbers label elements of the present embodiments. These reference numbers are reproduced below in connection with the discussion of the corresponding drawing features. 
     The embodiments of the present audio/video (A/V) recording and communication doorbells are described below with reference to the figures. These figures, and their written descriptions, indicate that certain components of the apparatus are formed integrally, and certain other components are formed as separate pieces. Those of ordinary skill in the art will appreciate that components shown and described herein as being formed integrally may in alternative embodiments be formed as separate pieces. Those of ordinary skill in the art will further appreciate that components shown and described herein as being formed as separate pieces may in alternative embodiments be formed integrally. Further, as used herein the term integral describes a single unitary piece. 
     With reference to  FIG. 1 , the present embodiments include an audio/video (A/V) recording and communication doorbell  100 . The A/V recording and communication doorbell  100  is typically located near the entrance to a structure (not shown), such as a dwelling, a business, a storage facility, etc. The A/V recording and communication doorbell  100  includes a camera  102 , a microphone  104 , and a speaker  106 . The camera  102  may comprise, for example, a high definition (HD) video camera, such as one capable of capturing video images at an image display resolution of 720p or better. While not shown, the A/V recording and communication doorbell  100  may also include other hardware and/or components, such as a housing, one or more motion sensors (and/or other types of sensors), a button, etc. The A/V recording and communication doorbell  100  may further include similar componentry and/or functionality as the wireless communication doorbells described in US Patent Application Publication Nos. 2015/0022620 (application Ser. No. 14/499,828) and 2015/0022618 (application Ser. No. 14/334,922), both of which are incorporated herein by reference in their entireties as if fully set forth. 
     With further reference to  FIG. 1 , the A/V recording and communication device  100  communicates with a user&#39;s network  110 , which may be for example a wired and/or wireless network. If the user&#39;s network  110  is wireless, or includes a wireless component, the network  110  may be a Wi-Fi network compatible with the IEEE 802.11 standard and/or other wireless communication standard(s). The user&#39;s network  110  is connected to another network  112 , which may comprise, for example, the Internet and/or a public switched telephone network (PSTN). As described below, the A/V recording and communication doorbell  100  may communicate with a user&#39;s client device  114  via the user&#39;s network  110  and the network  112  (Internet/PSTN). The user&#39;s client device  114  may comprise, for example, a mobile telephone (may also be referred to as a cellular telephone), such as a smartphone, a personal digital assistant (PDA), or another communication device. The user&#39;s client device  114  comprises a display (not shown) and related components capable of displaying streaming and/or recorded video images. The user&#39;s client device  114  may also comprise a speaker and related components capable of broadcasting streaming and/or recorded audio, and may also comprise a microphone. The A/V recording and communication doorbell  100  may also communicate with one or more remote storage device(s)  116  (may be referred to interchangeably as “cloud storage device(s)”), one or more servers  118 , and/or a backend API (application programming interface)  120  via the user&#39;s network  110  and the network  112  (Internet/PSTN). While  FIG. 1  illustrates the storage device  116 , the server  118 , and the backend API  120  as components separate from the network  112 , it is to be understood that the storage device  116 , the server  118 , and/or the backend API  120  may be considered to be components of the network  112 . 
     The network  112  may be any wireless network or any wired network, or a combination thereof, configured to operatively couple the above mentioned modules, devices, and systems as shown in  FIG. 1 . For example, the network  112  may include one or more of the following: a PSTN (public switched telephone network), the Internet, a local intranet, a PAN (Personal Area Network), a LAN (Local Area Network), a WAN (Wide Area Network), a MAN (Metropolitan Area Network), a virtual private network (VPN), a storage area network (SAN), a frame relay connection, an Advanced Intelligent Network (AIN) connection, a synchronous optical network (SONET) connection, a digital T1, T3, E1 or E3 line, a Digital Data Service (DDS) connection, a DSL (Digital Subscriber Line) connection, an Ethernet connection, an ISDN (Integrated Services Digital Network) line, a dial-up port such as a V.90, V.34, or V.34bis analog modem connection, a cable modem, an ATM (Asynchronous Transfer Mode) connection, or an FDDI (Fiber Distributed Data Interface) or CDDI (Copper Distributed Data Interface) connection. Furthermore, communications may also include links to any of a variety of wireless networks, including WAP (Wireless Application Protocol), GPRS (General Packet Radio Service), GSM (Global System for Mobile Communication), CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), and/or OFDMA (Orthogonal Frequency Division Multiple Access) cellular phone networks, GPS, CDPD (cellular digital packet data), RIM (Research in Motion, Limited) duplex paging network, Bluetooth radio, or an IEEE 802.11-based radio frequency network. The network can further include or interface with any one or more of the following: RS-232 serial connection, IEEE-1394 (Firewire) connection, Fibre Channel connection, IrDA (infrared) port, SCSI (Small Computer Systems Interface) connection, USB (Universal Serial Bus) connection, or other wired or wireless, digital or analog, interface or connection, mesh or Digi® networking. 
     According to one or more aspects of the present embodiments, when a person (may be referred to interchangeably as “visitor”) arrives at the A/V recording and communication doorbell  100 , the A/V recording and communication doorbell  100  detects the visitor&#39;s presence and begins capturing video images within a field of view of the camera  102 . The A/V recording and communication doorbell  100  may also capture audio through the microphone  104 . The A/V recording and communication doorbell  100  may detect the visitor&#39;s presence by detecting motion using the camera  102  and/or a motion sensor, and/or by detecting that the visitor has depressed the button on the A/V recording and communication doorbell  100 . 
     In response to the detection of the visitor, the A/V recording and communication doorbell  100  sends an alert to the user&#39;s client device  114  ( FIG. 1 ) via the user&#39;s network  110  and the network  112 . The A/V recording and communication doorbell  100  also sends streaming video, and may also send streaming audio, to the user&#39;s client device  114 . If the user answers the alert, two-way audio communication may then occur between the visitor and the user through the A/V recording and communication doorbell  100  and the user&#39;s client device  114 . The user may view the visitor throughout the duration of the call, but the visitor cannot see the user (unless the A/V recording and communication doorbell  100  includes a display, which it may in some embodiments). 
     The video images captured by the camera  102  of the A/V recording and communication doorbell  100  (and the audio captured by the microphone  104 ) may be uploaded to the cloud and recorded on the remote storage device  116  ( FIG. 1 ). In some embodiments, the video and/or audio may be recorded on the remote storage device  116  even if the user chooses to ignore the alert sent to his or her client device  114 . 
       FIG. 2  is a flowchart illustrating a process for streaming and storing A/V content from an A/V recording and communication doorbell system according to various aspects of the present disclosure. At block B 200 , the A/V recording and communication doorbell  100  detects the visitor&#39;s presence and begins capturing video images within a field of view of the camera  102 . The A/V recording and communication doorbell  100  may also capture audio through the microphone  104 . As described above, the A/V recording and communication doorbell  100  may detect the visitor&#39;s presence by detecting motion using the camera  102  and/or a motion sensor, and/or by detecting that the visitor has depressed the button on the A/V recording and communication doorbell  100 . 
     At block B 202 , a communication module of the A/V recording and communication doorbell  100  sends a request, via the user&#39;s network  110  and the network  112 , to a device in the network  112 . For example, the network device to which the request is sent may be a server such as the server  118 . The server  118  may comprise a computer program and/or a machine that waits for requests from other machines or software (clients) and responds to them. A server typically processes data. One purpose of a server is to share data and/or hardware and/or software resources among clients. This architecture is called the client-server model. The clients may run on the same computer or may connect to the server over a network. Examples of computing servers include database servers, file servers, mail servers, print servers, web servers, game servers, and application servers. The term server may be construed broadly to include any computerized process that shares a resource to one or more client processes. 
     In response to the request, at block B 204  the network device may connect the A/V recording and communication doorbell  100  to the user&#39;s client device  114  through the user&#39;s network  110  and the network  112 . At block B 206 , the A/V recording and communication doorbell  100  may record available audio and/or video data using the camera  102 , the microphone  104 , and/or any other sensor available. At block B 208 , the audio and/or video data is transmitted (streamed) from the A/V recording and communication doorbell  100  to the user&#39;s client device  114  via the user&#39;s network  110  and the network  112 . At block B 210 , the user may receive a notification on his or her client device  114  with a prompt to either accept or deny the call. 
     At block B 212 , the process determines whether the user has accepted or denied the call. If the user denies the notification, then the process advances to block B 214 , where the audio and/or video data is recorded and stored at a cloud server. The session then ends at block B 216  and the connection between the A/V recording and communication doorbell  100  and the user&#39;s client device  114  is terminated. If, however, the user accepts the notification, then at block B 218  the user communicates with the visitor through the user&#39;s client device  114  while audio and/or video data captured by the camera  102 , the microphone  104 , and/or other sensors is streamed to the user&#39;s client device  114 . At the end of the call, the user may terminate the connection between the user&#39;s client device  114  and the A/V recording and communication doorbell  100  and the session ends at block B 216 . In some embodiments, the audio and/or video data may be recorded and stored at a cloud server (block B 214 ) even if the user accepts the notification and communicates with the visitor through the user&#39;s client device  114 . 
     Many of today&#39;s homes include a wired doorbell system that does not have A/V communication capabilities. Instead, standard wired doorbell systems include a button outside the home next to the front door. The button activates a signaling device (such as a bell or a buzzer) inside the building. Pressing the doorbell button momentarily closes the doorbell circuit, which may be, for example, a single-pole, single-throw (SPST) push button switch. One terminal of the button is wired to a terminal on a transformer. The transformer steps down the 120-volt or 240-volt household AC electrical power to a lower voltage, typically 16 to 24 volts. Another terminal on the transformer is wired to a terminal on the signaling device. Another terminal on the signaling device is wired to the other terminal on the button. A common signaling device includes two flat metal bar resonators, which are struck by plungers operated by two solenoids. The flat bars are tuned to different notes. When the doorbell button is pressed, the first solenoid&#39;s plunger strikes one of the bars, and when the button is released, a spring on the plunger pushes the plunger up, causing it to strike the other bar, creating a two-tone sound (“ding-dong”). 
     Many current A/V recording and communication doorbell systems (other than the present embodiments) are incompatible with existing wired doorbell systems of the type described in the preceding paragraph. One reason for this incompatibility is that the A/V recording and communication doorbell draws an amount of power from the household AC electrical power supply that is above the threshold necessary for causing the signaling device to sound. The A/V recording and communication doorbell thus causes frequent inadvertent sounding of the signaling device, which is not only bothersome to the home&#39;s occupant(s), but also undermines the usefulness of the doorbell. The present embodiments solve this problem by limiting the power consumption of the A/V recording and communication doorbell to an amount that is below the threshold necessary for causing the signaling device to sound. Embodiments of the present A/V recording and communication doorbell can thus be connected to the existing household AC power supply and the existing signaling device without causing inadvertent sounding of the signaling device. 
     Several advantages flow from the ability of the present embodiments to be connected to the existing household AC power supply. For example, the camera of the present A/V recording and communication doorbell can be powered on continuously. In a typical battery-powered A/V recording and communication doorbell, the camera is powered on only part of the time so that the battery does not drain too rapidly. The present embodiments, by contrast, do not rely on a battery as a primary (or sole) power supply, and are thus able to keep the camera powered on continuously. Because the camera is able to be powered on continuously, it can always be recording, and recorded footage can be continuously stored in a rolling buffer or sliding window. In some embodiments, about 10-15 seconds of recorded footage can be continuously stored in the rolling buffer or sliding window. Also because the camera is able to be powered on continuously, it can be used for motion detection, thus eliminating any need for a separate motion detection device, such as a passive infrared sensor (PIR). Eliminating the PIR simplifies the design of the A/V recording and communication doorbell and enables the doorbell to be made more compact. Also because the camera is able to be powered on continuously, it can be used as a light detector for use in controlling the current state of the IR cut filter and turning the IR LED on and off. Using the camera as a light detector eliminates any need for a separate light detector, thereby further simplifying the design of the A/V recording and communication doorbell and enabling the doorbell to be made even more compact. 
       FIGS. 3-13  illustrate one embodiment of an A/V recording and communication doorbell  130  according to various aspects of the present disclosure.  FIG. 3  is a functional block diagram illustrating various components of the A/V recording and communication doorbell  130  and their relationships to one another. For example, the A/V recording and communication doorbell  130  includes a pair of terminals  131 ,  132  configured to be connected to a source of external AC (alternating-current) power, such as a household AC power supply  134  (may also be referred to as AC mains). The AC power  134  may have a voltage in the range of 16-24 VAC, for example. The incoming AC power  134  may be converted to DC (direct-current) by an AC/DC rectifier  136 . An output of the AC/DC rectifier  136  may be connected to an input of a DC/DC converter  138 , which may step down the voltage from the output of the AC/DC rectifier  136  from 16-24 VDC to a lower voltage of about 5 VDC, for example. In various embodiments, the output of the DC/DC converter  138  may be in a range of from about 2.5 V to about 7.5 V, for example. 
     With further reference to  FIG. 3 , the output of the DC/DC converter  138  is connected to a power manager  140 , which may comprise an integrated circuit including a processor core, memory, and/or programmable input/output peripherals. In one non-limiting example, the power manager  140  may be an off-the-shelf component, such as the BQ24773 chip manufactured by Texas Instruments. As described in detail below, the power manager  140  controls, among other things, an amount of power drawn from the external power supply  134 , as well as an amount of supplemental power drawn from a battery  142 , to power the A/V recording and communication doorbell  130 . The power manager  140  may, for example, limit the amount of power drawn from the external power supply  134  so that a threshold power draw is not exceeded. In one non-limiting example, the threshold power, as measured at the output of the DC/DC converter  138 , may be equal to 1.4 A. The power manager  140  may also control an amount of power drawn from the external power supply  134  and directed to the battery  142  for recharging of the battery  142 . An output of the power manager  140  is connected to a power sequencer  144 , which controls a sequence of power delivery to other components of the A/V recording and communication doorbell  130 , including a communication module  146 , a front button  148 , a microphone  150 , a speaker driver  151 , a speaker  152 , an audio CODEC (Coder-DECoder)  153 , a camera  154 , an infrared (IR) light source  156 , an IR cut filter  158 , a processor  160  (may also be referred to as a controller  160 ), a plurality of light indicators  162 , and a controller  164  for the light indicators  162 . Each of these components is described in detail below. The power sequencer  144  may comprise an integrated circuit including a processor core, memory, and/or programmable input/output peripherals. In one non-limiting example, the power sequencer  144  may be an off-the-shelf component, such as the RT5024 chip manufactured by Richtek. 
     With further reference to  FIG. 3 , the A/V recording and communication doorbell  130  further comprises an electronic switch  166  that closes when the front button  148  is depressed. When the electronic switch  166  closes, power from the AC power source  134  is diverted through a signaling device  168  that is external to the A/V recording and communication doorbell  130  to cause the signaling device  168  to emit a sound, as further described below. In one non-limiting example, the electronic switch  166  may be a triac device. The A/V recording and communication doorbell  130  further comprises a reset button  170  configured to initiate a hard reset of the processor  160 , as further described below. 
     With further reference to  FIG. 3 , the processor  160  may perform data processing and various other functions, as described below. The processor  160  may comprise an integrated circuit including a processor core, memory  172 , non-volatile memory  174 , and/or programmable input/output peripherals (not shown). The memory  172  may comprise, for example, DDR3 (double data rate type three synchronous dynamic random-access memory). The non-volatile memory  174  may comprise, for example, NAND flash memory. In the embodiment illustrated in  FIG. 3 , the memory  172  and the non-volatile memory  174  are illustrated within the box representing the processor  160 . It is to be understood that the embodiment illustrated in  FIG. 3  is merely an example, and in some embodiments the memory  172  and/or the non-volatile memory  174  are not necessarily physically incorporated with the processor  160 . The memory  172  and/or the non-volatile memory  174 , regardless of their physical location, may be shared by one or more other components (in addition to the processor  160 ) of the present A/V recording and communication doorbell  130 . 
     The transfer of digital audio between the user and a visitor may be compressed and decompressed using the audio CODEC  153 , which is operatively coupled to the processor  160 . When the visitor speaks, audio from the visitor is compressed by the audio CODEC  153 , digital audio data is sent through the communication module  146  to the network  112  via the user&#39;s network  110 , routed by the server  118  and delivered to the user&#39;s client device  114 . When the user speaks, after being transferred through the network  112 , the user&#39;s network  110 , and the communication module  146 , the digital audio data is decompressed by the audio CODEC  153  and emitted to the visitor through the speaker  152 , which is driven by the speaker driver  151 . 
     With further reference to  FIG. 3 , some of the present embodiments may include a shunt  176  connected in parallel with the signaling device  168 . The shunt  176  facilitates the ability of the A/V recording and communication doorbell  130  to draw power from the AC power source  134  without inadvertently triggering the signaling device  168 . The shunt  176 , during normal standby operation, presents a relatively low electrical impedance, such as a few ohms, across the terminals of the signaling device  168 . Most of the current drawn by the A/V recording and communication doorbell  130 , therefore, flows through the shunt  176 , and not through the signaling device  168 . The shunt  176 , however, contains electronic circuitry (described below) that switches the shunt  176  between a state of low impedance, such as a few ohms, for example, and a state of high impedance, such as &gt;1 K ohms, for example. When the front button  148  of the A/V recording and communication doorbell  130  is pressed, the electronic switch  166  closes, causing the voltage from the AC power source  134  to be impressed mostly across the shunt  176  and the signaling device  168  in parallel, while a small amount of voltage, such as about 1V, is impressed across the electronic switch  166 . The circuitry in the shunt  176  senses this voltage, and switches the shunt  176  to the high impedance state, so that power from the AC power source  134  is diverted through the signaling device  168 . The diverted AC power  134  is above the threshold necessary to cause the signaling device  168  to emit a sound. Pressing the front button  148  of the doorbell  130  therefore causes the signaling device  168  to “ring,” alerting any person(s) within the structure to which the doorbell  130  is mounted that there is a visitor at the front door (or at another location corresponding to the location of the doorbell  130 ). In one non-limiting example, the electronic switch  166  may be a triac device. 
     With reference to  FIGS. 4-6 , the A/V recording and communication doorbell  130  further comprises a housing  178  having an enclosure  180  ( FIG. 6 ), a back plate  182  secured to the rear of the enclosure  180 , and a shell  184  overlying the enclosure  180 . With reference to  FIG. 6 , the shell  184  includes a recess  186  that is sized and shaped to receive the enclosure  180  in a close fitting engagement, such that outer surfaces of the enclosure  180  abut conforming inner surfaces of the shell  184 . Exterior dimensions of the enclosure  180  may be closely matched with interior dimensions of the shell  184  such that friction maintains the shell  184  about the enclosure  180 . Alternatively, or in addition, the enclosure  180  and/or the shell  184  may include mating features  188 , such as one or more tabs, grooves, slots, posts, etc. to assist in maintaining the shell  184  about the enclosure  180 . The back plate  182  is sized and shaped such that the edges of the back plate  182  extend outward from the edges of the enclosure  180 , thereby creating a lip  190  against which the shell  184  abuts when the shell  184  is mated with the enclosure  180 , as shown in  FIGS. 4 and 5 . In some embodiments, multiple shells  184  in different colors may be provided so that the end user may customize the appearance of his or her A/V recording and communication doorbell  130 . For example, the A/V recording and communication doorbell  130  may be packaged and sold with multiple shells  184  in different colors in the same package. 
     With reference to  FIG. 4 , a front surface of the A/V recording and communication doorbell  130  includes the button  148  (may also be referred to as front button  148 ,  FIG. 3 ), which is operatively connected to the processor  160 . In a process similar to that described above with reference to  FIG. 2 , when a visitor presses the front button  148 , an alert may be sent to the user&#39;s client device to notify the user that someone is at his or her front door (or at another location corresponding to the location of the A/V recording and communication doorbell  130 ). With further reference to  FIG. 4 , the A/V recording and communication doorbell  130  further includes the camera  154 , which is operatively connected to the processor  160 , and which is located behind a shield  192 . As described in detail below, the camera  154  is configured to capture video images from within its field of view. Those video images can be streamed to the user&#39;s client device and/or uploaded to a remote network device for later viewing according to a process similar to that described above with reference to  FIG. 2 . 
     With reference to  FIG. 5 , a pair of terminal screws  194  extends through the back plate  182 . The terminal screws  194  are connected at their inner ends to the terminals  131 ,  132  ( FIG. 3 ) within the A/V recording and communication doorbell  130 . The terminal screws  194  are configured to receive electrical wires to connect to the A/V recording and communication doorbell  130 , through the terminals  131 ,  132 , to the household AC power supply  134  of the structure on which the A/V recording and communication doorbell  130  is mounted. In the illustrated embodiment, the terminal screws  194  are located within a recessed portion  196  of the rear surface  198  of the back plate  182  so that the terminal screws  194  do not protrude from the outer envelope of the A/V recording and communication doorbell  130 . The A/V recording and communication doorbell  130  can thus be mounted to a mounting surface with the rear surface  198  of the back plate  182  abutting the mounting surface. The back plate  182  includes apertures  200  adjacent its upper and lower edges to accommodate mounting hardware, such as screws (not shown), for securing the back plate  182  (and thus the A/V recording and communication doorbell  130 ) to the mounting surface. With reference to  FIG. 6 , the enclosure  180  includes corresponding apertures  202  adjacent its upper and lower edges that align with the apertures  200  in the back plate  182  to accommodate the mounting hardware. In certain embodiments, the A/V recording and communication doorbell  130  may include a mounting plate or bracket (not shown) to facilitate securing the A/V recording and communication doorbell  130  to the mounting surface. 
     With further reference to  FIG. 6 , the shell  184  includes a central opening  204  in a front surface. The central opening  204  is sized and shaped to accommodate the shield  192 . In the illustrated embodiment, the shield  192  is substantially rectangular, and includes a central opening  206  through which the front button  148  protrudes. The shield  192  defines a plane parallel to and in front of a front surface  208  of the enclosure  180 . When the shell  184  is mated with the enclosure  180 , as shown in  FIGS. 4 and 10 , the shield  192  resides within the central opening  204  of the shell  184  such that a front surface  210  of the shield  192  is substantially flush with a front surface  212  of the shell  184  and there is little or no gap ( FIG. 4 ) between the outer edges of the shield  192  and the inner edges of the central opening  204  in the shell  184 . 
     With further reference to  FIG. 6 , the shield  192  includes an upper portion  214  (located above and to the sides of the front button  148 ) and a lower portion  216  (located below and to the sides of the front button  148 ). The upper and lower portions  214 ,  216  of the shield  192  may be separate pieces, and may comprise different materials. The upper portion  214  of the shield  192  may be transparent or translucent so that it does not interfere with the field of view of the camera  154 . For example, in certain embodiments the upper portion  214  of the shield  192  may comprise glass or plastic. As described in detail below, the microphone  150 , which is operatively connected to the processor  160 , is located behind the upper portion  214  of the shield  192 . The upper portion  214 , therefore, may include an opening  218  that facilitates the passage of sound through the shield  192  so that the microphone  150  is better able to pick up sounds from the area around the A/V recording and communication doorbell  130 . 
     The lower portion  216  of the shield  192  may comprise a material that is substantially transparent to infrared (IR) light, but partially or mostly opaque with respect to light in the visible spectrum. For example, in certain embodiments the lower portion  216  of the shield  192  may comprise a plastic, such as polycarbonate. The lower portion  216  of the shield  192 , therefore, does not interfere with transmission of IR light from the IR light source  156 , which is located behind the lower portion  216 . As described in detail below, the IR light source  156  and the IR cut filter  158 , which are both operatively connected to the processor  160 , facilitate “night vision” functionality of the camera  154 . 
     The upper portion  214  and/or the lower portion  216  of the shield  192  may abut an underlying cover  220  ( FIG. 10 ), which may be integral with the enclosure  180  or may be a separate piece. The cover  220 , which may be opaque, may include a first opening  222  corresponding to the location of the camera  154 , a second opening (not shown) corresponding to the location of the microphone  150  and the opening  218  in the upper portion  214  of the shield  192 , and a third opening (not shown) corresponding to the location of the IR light source  156 . 
       FIGS. 7-10  illustrate various internal components of the A/V recording and communication doorbell  130 .  FIGS. 7-9  are front perspective views of the doorbell  130  with the shell  184  and the enclosure  180  removed, while  FIG. 10  is a right-side cross-sectional view of the doorbell  130  taken through the line  10 - 10  in  FIG. 4 . With reference to  FIGS. 7 and 8 , the A/V recording and communication doorbell  130  further comprises a main printed circuit board (PCB)  224  and a front PCB  226 . With reference to  FIG. 8 , the front PCB  226  comprises a button actuator  228 . With reference to  FIGS. 7, 8, and 10 , the front button  148  is located in front of the button actuator  228 . The front button  148  includes a stem  230  ( FIG. 10 ) that extends into the housing  178  to contact the button actuator  228 . When the front button  148  is pressed, the stem  230  depresses the button actuator  228 , thereby closing the electronic switch  166  ( FIG. 8 ), as described below. 
     With reference to  FIG. 8 , the front PCB  226  further comprises the light indicators  162 , which may illuminate when the front button  148  of the doorbell  130  is pressed. In the illustrated embodiment, the light indicators  162  comprise light-emitting diodes (LEDs  162 ) that are surface mounted to the front surface of the front PCB  226  and are arranged in a circle around the button actuator  228 . The present embodiments are not limited to the light indicators  162  being LEDs, and in alternative embodiments the light indicators  162  may comprise any other type of light-emitting device. The present embodiments are also not limited by the number of light indicators  162  shown in  FIG. 8 , nor by the pattern in which they are arranged. 
     With reference to  FIG. 7 , the doorbell  130  further comprises a light pipe  232 . The light pipe  232  is a transparent or translucent ring that encircles the front button  148 . With reference to  FIG. 4 , the light pipe  232  resides in an annular space between the front button  148  and the central opening  206  in the shield  192 , with a front surface  234  of the light pipe  232  being substantially flush with the front surface  210  of the shield  192 . With reference to  FIGS. 7 and 10 , a rear portion of light pipe  232  includes a plurality of posts  236  whose positions correspond to the positions of the LEDs  162 . When the LEDs  162  are illuminated, light is transmitted through the posts  236  and the body of the light pipe  232  so that the light is visible at the front surface  234  of the light pipe  232 . The LEDs  162  and the light pipe  232  thus provide a ring of illumination around the front button  148 . The light pipe  232  may comprise a plastic, for example, or any other suitable material capable of transmitting light. 
     The LEDs  162  and the light pipe  232  may function as visual indicators for a visitor and/or a user. For example, the LEDs  162  may illuminate upon activation or stay illuminated continuously. In one aspect, the LEDs  162  may change color to indicate that the front button  148  has been pressed. The LEDs  162  may also indicate that the battery  142  needs recharging, or that the battery  142  is currently being charged, or that charging of the battery  142  has been completed. The LEDs  162  may indicate that a connection to the user&#39;s wireless network is good, limited, poor, or not connected. The LEDs  162  may be used to guide the user through setup or installation steps using visual cues, potentially coupled with audio cues emitted from the speaker  152 . 
     With further reference to  FIG. 7 , the A/V recording and communication doorbell  130  further comprises a rechargeable battery  142 . As described in further detail below, the A/V recording and communication doorbell  130  is connected to an external power source  134  ( FIG. 3 ), such as AC mains. The A/V recording and communication doorbell  130  is primarily powered by the external power source  134 , but may also draw power from the rechargeable battery  142  so as not to exceed a threshold amount of power from the external power source  134 , to thereby avoid inadvertently sounding the signaling device  168 . With reference to  FIG. 3 , the battery  142  is operatively connected to the power manager  140 . As described below, the power manager  140  controls an amount of power drawn from the battery  142  to supplement the power drawn from the external AC power source  134  to power the A/V recording and communication doorbell  130  when supplemental power is needed. The power manager  140  also controls recharging of the battery  142  using power drawn from the external power source  134 . The battery  142  may comprise, for example, a lithium-ion battery, or any other type of rechargeable battery. 
     With further reference to  FIG. 7 , the A/V recording and communication doorbell  130  further comprises the camera  154 . The camera  154  is coupled to a front surface of the front PCB  226 , and includes a lens  238  and an imaging processor  240  ( FIG. 9 ). The camera lens  238  may be a lens capable of focusing light into the camera  154  so that clear images may be captured. The camera  154  may comprise, for example, a high definition (HD) video camera, such as one capable of capturing video images at an image display resolution of 720p or better. In certain of the present embodiments, the camera  154  may be used to detect motion within its field of view, as described below. 
     With further reference to  FIG. 7 , the A/V recording and communication doorbell  130  further comprises an infrared (IR) light source  242 . In the illustrated embodiment, the IR light source  242  comprises an IR light-emitting diode (LED)  242  coupled to an IR LED printed circuit board (PCB)  244 . In alternative embodiments, the IR LED  242  may not comprise a separate PCB  244 , and may, for example, be coupled to the front PCB  226 . 
     With reference to  FIGS. 7 and 10 , the IR LED PCB  244  is located below the front button  148  ( FIG. 7 ) and behind the lower portion  216  of the shield  192  ( FIG. 10 ). As described above, the lower portion  216  of the shield  192  is transparent to IR light, but may be opaque with respect to light in the visible spectrum.  FIG. 7A  illustrates an alternative embodiment of the IR LED PCB  244 ′ comprising three IR LEDs  242 . In an embodiment including the IR LED PCB  244 ′ of  FIG. 7A , or including any IR LED PCB having more than one IR LED  242 , the size of the third opening in the cover may be increased to accommodate the larger size of the IR LED PCB  244 ′. 
     The IR LED  242  may be triggered to activate when a low level of ambient light is detected. When activated, IR light emitted from the IR LED  242  illuminates the camera  154 &#39;s field of view. The camera  154 , which may be configured to detect IR light, may then capture the IR light emitted by the IR LED  242  as it reflects off objects within the camera  154 &#39;s field of view, so that the A/V recording and communication doorbell  130  can clearly capture images at night (may be referred to as “night vision”). 
     With reference to  FIG. 9 , the A/V recording and communication doorbell  130  further comprises an IR cut filter  158 . The IR cut filter  158  is a mechanical shutter that can be selectively positioned between the lens  238  and the image sensor of the camera  154 . During daylight hours, or whenever there is a sufficient amount of ambient light, the IR cut filter  158  is positioned between the lens  238  and the image sensor to filter out IR light so that it does not distort the colors of images as the human eye sees them. During nighttime hours, or whenever there is little to no ambient light, the IR cut filter  158  is withdrawn from the space between the lens  238  and the image sensor, so that the camera  154  is sensitive to IR light (“night vision”). In some embodiments, the camera  154  acts as a light detector for use in controlling the current state of the IR cut filter  158  and turning the IR LED  242  on and off. Using the camera  154  as a light detector is facilitated in some embodiments by the fact that the A/V recording and communication doorbell  130  is powered by a connection to AC mains, and the camera  154 , therefore, is always powered on. In other embodiments, however, the A/V recording and communication doorbell  130  may include a light sensor separate from the camera  154  for use in controlling the IR cut filter  158  and the IR LED  242 . 
     With reference back to  FIG. 6 , the A/V recording and communication doorbell  130  further comprises a reset button  170 . The reset button  170  contacts a reset button actuator  246  ( FIG. 8 ) coupled to the front PCB  226 . When the reset button  170  is pressed, it may contact the reset button actuator  246 , which may trigger the erasing of any data stored at the non-volatile memory  174  and/or at the memory  172  ( FIG. 3 ), and/or may trigger a reboot of the processor  160 . 
       FIGS. 11-13  further illustrate internal components of the A/V recording and communication doorbell  130 .  FIGS. 11-13  are rear perspective views of the doorbell  130  with the back plate  182  and additional components removed. For example, in  FIG. 11  the back plate  182  is removed, while in  FIG. 12  the back plate  182  and the main PCB  224  are removed, and in  FIG. 13  the back plate  182 , the main PCB  224 , and the front PCB  226  are removed. With reference to  FIG. 11 , several components are coupled to the rear surface of the main PCB  224 , including the communication module  146 , the processor  160 , memory  172 , and non-volatile memory  174 . The functions of each of these components are described below. With reference to  FIG. 12 , several components are coupled to the rear surface of the front PCB  226 , including the power manager  140 , the power sequencer  144 , the AC/DC rectifier  136 , the DC/DC converter  138 , and the controller  164  for the light indicators  162 . The functions of each of these components are also described below. With reference to  FIG. 13 , several components are visible within the enclosure  180 , including the microphone  150 , a speaker chamber  248  (in which the speaker  152  is located), and an antenna  250  for the communication module  146 . The functions of each of these components are also described below. 
     With reference to  FIG. 7 , the antenna  250  is coupled to the front surface of the main PCB  224  and operatively connected to the communication module  146 , which is coupled to the rear surface of the main PCB  224  ( FIG. 11 ). The microphone  150 , which may also be coupled to the front surface of the main PCB  224 , is located near the opening  218  ( FIG. 4 ) in the upper portion  214  of the shield  192  so that sounds emanating from the area around the A/V recording and communication doorbell  130  can pass through the opening  218  and be detected by the microphone  150 . With reference to  FIG. 13 , the speaker chamber  248  is located near the bottom of the enclosure  180 . The speaker chamber  248  comprises a hollow enclosure in which the speaker  152  is located. The hollow speaker chamber  248  amplifies the sounds made by the speaker  152  so that they can be better heard by a visitor in the area near the A/V recording and communication doorbell  130 . With reference to  FIGS. 5 and 13 , the lower surface  252  of the shell  184  and the lower surface (not shown) of the enclosure  180  may include an acoustical opening  254  through which the sounds made by the speaker  152  can pass so that they can be better heard by a visitor in the area near the A/V recording and communication doorbell  130 . In the illustrated embodiment, the acoustical opening  254  is shaped generally as a rectangle having a length extending substantially across the lower surface  252  of the shell  184  (and also the enclosure  180 ). The illustrated shape is, however, just one example. With reference to  FIG. 5 , the lower surface  252  of the shell  184  may further include an opening  256  for receiving a security screw (not shown). The security screw may extend through the opening  256  and into a similarly located opening in the enclosure  180  to secure the shell  184  to the enclosure  180 . If the doorbell  130  is mounted to a mounting bracket (not shown), the security screw may also maintain the doorbell  130  on the mounting bracket. 
     With reference to  FIG. 13 , the A/V recording and communication doorbell  130  may further include a battery heater  258 . The present A/V recording and communication doorbell  130  is configured for outdoor use, including in cold climates. Cold temperatures, however, can cause negative performance issues for rechargeable batteries, such as reduced energy capacity, increased internal resistance, reduced ability to charge without damage, and reduced ability to supply load current. The battery heater  258  helps to keep the rechargeable battery  142  warm in order to reduce or eliminate the foregoing negative performance issues. In the illustrated embodiment, the battery heater  258  comprises a substantially flat, thin sheet abutting a side surface of the rechargeable battery  142 . The battery heater  258  may comprise, for example, an electrically resistive heating element that produces heat when electrical current is passed through it. The battery heater  258  may thus be operatively coupled to the power manager  140  and/or the power sequencer  144  ( FIG. 12 ). In some embodiments, the rechargeable battery  142  may include a thermally sensitive resistor (“thermistor,” not shown) operatively connected to the processor  160  so that the battery  142 &#39;s temperature can be monitored and the amount of power supplied to the battery heater  258  can be adaptively controlled to keep the rechargeable battery  142  within a desired temperature range. 
       FIG. 14  is a flowchart illustrating an embodiment of a process for drawing supplemental power from the battery  142  of the present A/V recording and communication doorbell  130  in order to avoid inadvertent sounding of the connected signaling device  168 . At block B 280 , the A/V recording and communication doorbell  130  draws power, below a threshold power, from an external power source. The external power source may be, for example, the AC power source  134 , as shown in  FIG. 3 . The threshold power may be, for example, the power level at which the signaling device  168  ( FIG. 3 ) would sound. In one non-limiting example, the threshold power may be measured at the output of the DC/DC converter  138  ( FIG. 3 ). The threshold power may be measured by the power manager  140  ( FIG. 3 ), for example. In one non-limiting example, the threshold power, as measured at the output of the DC/DC converter  138 , may be equal to 1.4 A. 
     At block B 282 , the process determines whether the power drawn from the external power source  134  has reached the threshold power. In some embodiments, the power manager  140  ( FIG. 3 ), for example, may determine whether the power drawn from the external power source  134  has reached the threshold power. If the power drawn from the external power source  134  has not reached the threshold power, then the process loops back to block B 280 . If, however, the power drawn from the external power source  134  has reached the threshold power, then the process moves to block B 284 . At block B 284 , the A/V recording and communication doorbell  130  draws supplemental power from the battery  142  as needed so that the power drawn from the external power source  134  does not exceed the threshold power. In this manner, the process of  FIG. 14  avoids inadvertent sounding of the connected signaling device  168 . Examples of scenarios where the power drawn from the external power source  134  might reach the threshold power include, but are not limited to, when switching the IR cut filter  158  from daytime mode to nighttime mode (and vice versa), or when a call is in progress between a visitor at the A/V recording and communication doorbell  130  and a user using a client device and the IR light source  156  is illuminated. In some embodiments, when the power being drawn from the external power source  134  is below the threshold power, the power manager  140  may direct a portion of the power drawn from the external power source  134  to the battery  142  in order to recharge the battery  142 . 
     As discussed above, and with reference back to  FIG. 3 , some of the present embodiments may include a shunt  176  connected in parallel across the terminals of the signaling device  168 . The shunt  176  facilitates the ability of the A/V recording and communication doorbell  130  to draw power from the AC power source  134  without inadvertently triggering the signaling device  168 .  FIG. 15  illustrates an example embodiment of the shunt  176 . With reference to  FIG. 15 , the shunt  176  comprises a full-wave bridge rectifier  300 , a capacitor  302 , a diode  304 , a shunt switch  306 , a first resistor R Shunt    308 , and a second resistor R Bias    310 . In some embodiments, the shunt switch  306  may be an opto-coupled switch, for example. The first resistor R Shunt    308  presents a relatively low electrical impedance, such as a few ohms for example, while the second resistor R Bias    310  presents a higher electrical impedance, such as &gt;1 K ohms for example. 
     During normal standby operation, the shunt switch  306  is closed. The shunt  176 , therefore, presents a relatively low electrical impedance across the terminals AC 1 , AC 2  of the signaling device  168 , because the impedance of the first resistor R Shunt    308  is relatively low and the impedance of the switch is even lower, such as about 1 ohm or less in one example. Most of the current drawn by the A/V recording and communication doorbell  130 , therefore, flows through the shunt  176 , and not through the signaling device  168 . When the front button  148  of the A/V recording and communication doorbell  130  is pressed, however, the electronic switch  166  closes, causing the voltage from the AC power source  134  to be impressed mostly across the shunt  176  and the signaling device  168  in parallel, while a small amount of voltage, such as about 1 V in one example, is impressed across the electronic switch  166 , if it is implemented as a triac for example. The circuitry in the shunt  176  senses the voltage across its terminals AC 1 , AC 2 , causing the shunt switch  306  to open, which puts the shunt  176  into a high impedance state. When the shunt  176  receives enough AC voltage, the full-wave bridge rectifier  300  provides and outputs enough DC voltage such that the diode  304  biased by resistor  310  R bias  conducts enough current to cause the switch  306  to change to an open or very high impedance state. Thus, the switching action of the shunt  176  makes nearly all available power from the AC power source  134  usable by the signaling device  168 , when it is desired. The amount of diverted AC power from the AC power source  134  is above the threshold necessary to cause the signaling device  168  to emit a sound. Pressing the front button  148  of the doorbell  130  therefore causes the signaling device  168  to sound, alerting any person(s) within the structure to which the doorbell  130  is mounted that there is a visitor at the front door (or at another location corresponding to the location of the doorbell  130 ). 
     With continued reference to  FIG. 15 , the shunt  176  further comprises a first comparator circuit  312  and a second comparator circuit  314 .  FIGS. 16 and 17  are circuit diagrams illustrating example embodiments of the first and second comparator  324  circuits  312 ,  314 , respectively, of the shunt  176  of  FIG. 15 . The comparators  312 ,  314  of  FIGS. 16 and 17  are both open collector-type or open drain-type. These types of comparators are advantageous because they allow the outputs to be tied together without conflict, commonly known as a “wired-OR” connection. As further described below, the first comparator circuit  312  serves the purpose of returning the state of the shunt switch  306  to the normally closed, low impedance state, when an opening event is detected at the electronic switch  166  ( FIG. 3 ). The second comparator circuit  314  serves as a time out safety trigger, returning the state of the shunt switch  306  to the normally closed, low impedance state, in the event that the first comparator circuit  312  fails to perform its intended function. 
     With reference to  FIG. 16 , the first comparator circuit  312  comprises a first comparator  316 , and an RC network at each of its two inputs  318 ,  320 . The first (positive) input  318  of the first comparator  316  has an RC network having time constant Tau 1 , where Tau 1 =C 1 *R 1 . The second (negative) input  320  of the first comparator  316  has a voltage divider R 2 /(R 2 +R 3 ) and time constant Tau 2 , where Tau 2 =C 2 *((R 2 *R 3 )/((R 2 +R 3 ))). With reference to  FIGS. 18 and 19 , which are waveform diagrams for the first comparator circuit  312  of  FIG. 16 , the first comparator circuit  312  behavior is as follows. At time t 1 , when the V DC  at the capacitor  302  ( FIG. 15 ) ramps up due to closure of the electronic switch ( FIG. 3 ), both inputs  318 ,  320  to the first comparator  316  rise, with V 2  rising slower and asymptotically approaching V MAX *(R 2 /(R 2 +R 3 )), while V 1  rises faster and approaches V MAX . The ratio R 2 /(R 2 +R 3 ) may be chosen based on noise level consideration, particularly to ensure a positive drive with margin into the first comparator  316 , for all times when the electronic switch  166  is closed. This assures the output V OUT    322  of the first comparator  316  will be high impedance, since it is an open collector-type or an open drain-type output. Upon the electronic switch  166  opening at time t 2 , the voltage V DC  at the capacitor  302  drops, and the voltage V 1  drops below V 2 . The first comparator  316  responds by driving its output V OUT    322  on, which pulls down the voltage and starts to turn off the diode  304  in the shunt switch  306 . The shunt switch  306  responds by reverting back to its normally closed position. 
     With reference to  FIG. 17 , the second comparator circuit  314  comprises a second comparator  324 , and an RC network at each of its two inputs  326 ,  328 , but with the addition of a diode  330  in one of the series branches. The first (positive) input  326  of the second comparator  324  receives an attenuated version of V DC . More precisely, it receives a voltage given by V DC *(R 6 /(R 6 +R 5 )). In some embodiments, a capacitor (not shown) may be provided across R 6 , as some filtering may be advantageous. The second (negative) input  328  of the second comparator  324  receives a voltage V 4  that rises slowly after V DC  ramps up. With reference to  FIGS. 20 and 21 , which are waveform diagrams for the second comparator circuit  314  of  FIG. 17 , the second comparator circuit  314  behavior is as follows. The rising waveform is given by V 4 (t)=V DCMAX *(1−exp(−t/Tau 3 )) where Tau 3 =C 4 *R 4 . While V 4  asymptotically approaches V DCMAX , it will hit V DCMAX *(R 6 /(R 6 +R 5 )) at time t 3 , which is given by t 3 =Tau 3 *ln(1+R 6 /R 5 ). Because of delays in the feedback mechanism, the voltage V 4  will actually go higher than V 3 , causing the output V OUT    332  of the second comparator  324  to be pulled low. This causes the diode  304  in the shunt switch  306  to discharge and turn off, which in turn causes the shunt switch  306  in SW 1  to revert to its normally closed position. The feedback mechanism is positive in that the turning off of the diode  304  puts the shunt  176  in a low impedance state, which causes the diode  304  to turn off even faster, since a low impedance state of the shunt  176  will collapse the AC 1 , AC 2  terminals, if the electronic switch  166  is not closed. Reducing the voltage across AC 1 , AC 2  will reduce the output of the full-wave bridge rectifier  300 , V DC . 
       FIG. 22  is a flowchart illustrating an embodiment of a process for sounding the signaling device  168  connected to the present A/V recording and communication doorbell  130  according to various aspects of the present disclosure. At block B 380 , the A/V recording and communication doorbell  130  draws power from an external power source. The external power source may be, for example, the AC power source  134 , as shown in  FIG. 3 . At block B 382 , the power flows through the signaling device  168  and the shunt  176  in parallel, and the shunt  176  is in the low impedance state. At block B 384 , the process determines whether the front button  148  has been depressed. If the front button  148  has not been depressed, then the process returns to block B 382 . If, however, the front button  148  has been depressed, then the process moves to block B 386 . At block B 386 , the electronic switch  166  closes, thereby causing the shunt  176  to transition to the high impedance state, which in turn causes the power drawn from the external power source to be diverted through the signaling device  168 , which in turn causes the signaling device  168  to emit a sound. Also, when the front button  148  is depressed, the speaker  152  of the A/V recording and communication doorbell  130  may emit a sound to alert any persons within earshot of the speaker  152  that a visitor has pressed the front button  148 . 
       FIG. 23  is a flowchart illustrating another embodiment of a process for sounding the signaling device  168  connected to the present A/V recording and communication doorbell  130  according to various aspects of the present disclosure. At block B 350 , the A/V recording and communication doorbell  130  draws power from an external power source. The external power source may be, for example, the AC power source  134 , as shown in  FIG. 3 . At block B 352 , the power flows through the signaling device  168  and the shunt  176  in parallel, and the shunt  176  is in the low impedance state. At block B 354 , the process determines whether the front button  148  has been depressed. If the front button  148  has not been depressed, then the process returns to block B 352 . If, however, the front button  148  has been depressed, then the process moves to block B 356 . Also, when the front button  148  is depressed, the speaker  152  of the A/V recording and communication doorbell  130  may emit a sound to alert any persons within earshot of the speaker  152  that a visitor has pressed the front button  148 . 
     At block B 356 , the process determines whether the power in the battery  142  is above a threshold. This determination helps ensure that the battery  142  does not drain completely while the power manager  140  is drawing supplemental power from the battery  142 . If the power in the battery  142  is not above the threshold, then the process returns to block B 352 . If, however, the power in the battery  142  is above the threshold, then the process moves to block B 358 . At block B 358 , the electronic switch  166  closes, thereby causing the shunt  176  to transition to the high impedance state, which in turn causes the power drawn from the external power source to be diverted through the signaling device  168 , which in turn causes the signaling device  168  to emit a sound. 
     Also at block B 358 , a first timer is activated. The first timer, which may be implemented by the processor  160 , for example, enables several advantages. For example, the first timer enhances the compatibility of the present A/V recording and communication doorbell  130  with different types of existing signaling devices  168 . Many existing signaling devices are of two types: electro-mechanical and electronic. Electro-mechanical signaling devices typically include a pair of metal tubes (or plates) that are tuned to different notes and act as resonators when struck. A plunger strikes the tubes or plates in quick succession, creating the “ding-dong” sound that is characteristic of many traditional doorbells. Electronic signaling devices, by contrast, typically include an audio speaker that acts as an electro-acoustic transducer. The speaker can in many instances be made to play custom ringtones having different durations. 
     During initial setup of some embodiments of the present A/V recording and communication doorbell  130 , the duration of the first timer may be set according to the type of signaling device  168  with which it is paired, and the duration of the first timer may be customizable. For example, if the doorbell  130  is paired with an electro-mechanical signaling device  168 , then the first timer may be set to a relatively short duration, such as 250 ms. A short duration for the first timer enables the electro-mechanical signaling device  168  to emit the characteristic “ding-dong” sound, because the plunger of the signaling device  168  will strike a first one of the metal tubes (or plates) when the electronic switch  166  closes and strike the second one of the metal tubes (or plates) when the electronic switch  166  opens. If the doorbell  130  is paired with an electro-mechanical signaling device  168 , the duration of the first timer may be preset (not customizable by the user). If, however, the doorbell  130  is paired with an electronic signaling device  168 , then the first timer may be set to a relatively long duration, such as from 1 second to 10 seconds, and the duration of the first timer may be selectable by the user. For example, if the user&#39;s electronic signaling device  168  plays a ringtone having a duration of about 3 seconds, then the user may set the duration of the first timer to be about 3 seconds. 
     During initial setup of some embodiments of the present A/V recording and communication doorbell  130 , the user may be prompted to indicate what type of signaling device  168  the doorbell  130  is to be paired with. If the user indicates that the signaling device  168  is electro-mechanical, then the process may automatically set the duration of the first timer to a relatively short duration. If, however, the user indicates that the signaling device  168  is electronic, then the process may prompt the user to enter a desired duration for the first timer. In some embodiments, the process may prompt the user that the duration must be within a preset range. 
     At block B 360 , the process determines whether the first timer has expired. If the first timer has expired, then the process moves to block B 364 , which is described below. If, however, the first timer has not expired, then the process moves to block B 362 . At block B 362 , the process determines whether a notification has been received that a call to the user&#39;s client device has been answered. If no notification has been received that a call to the user&#39;s client device has been answered, then the process returns to block B 360 . If, however, a notification has been received that a call to the user&#39;s client device has been answered, then the process moves to block B 364 . At block B 364 , the electronic switch  166  opens, and a second timer is activated. The second timer, which may be implemented by the processor  160 , for example, prevents a subsequent press of the front button  148  from closing the electronic switch  166 , thereby preventing the visitor from repeatedly sounding the signaling device  168  (by rapidly pressing and re-pressing the front button  148 ). The second timer also allows time for the battery  142  to recharge. The process then moves to block B 366 . At block B 366 , the process determines whether the front button  148  has been depressed. If the front button  148  has not been depressed, then the process returns to block B 366 . If, however, the front button  148  has been depressed, then the process moves to block B 368 . At block B 368 , the process determines whether the second timer has expired. If the second timer has not expired, then the process returns to block B 366 . If, however, the second timer has expired, then the process returns to block B 356 . 
     In some embodiments, the present A/V recording and communication doorbell  130  may detect a visitor (by detecting motion) before the visitor presses the front button  148 . In such cases, the A/V recording and communication doorbell  130  may initiate a call to the user&#39;s client device in a manner similar to that described above with respect to blocks B 202 -B 210  of  FIG. 2 . If the user answers the call on his or her client device before the visitor presses the front button  148  of the A/V recording and communication doorbell  130 , then the front button  148  may be blocked out as long as the call between the visitor and the user is still in progress. That is, if the visitor presses the front button  148  while the call between the visitor and the user is in progress, the electronic switch  166  may be prevented from closing. If, however, the visitor presses the front button  148  of the A/V recording and communication doorbell  130  before the user answers the call on his or her client device, then the process may proceed according to that described above with respect to  FIG. 23  (beginning at block B 354 ). 
     Some of the present embodiments provide advantageous motion detection algorithms and techniques. For example, during an initial setup process, or at any time after the A/V recording and communication doorbell  130  has been setup, the user may designate one or more zones within the field of view  400  of the camera  154  as motion zones of interest, also referred to as “intrusion zones.” With reference to  FIG. 24 , when configuring the camera  154 &#39;s motion detection, a configuration process may present the user with a visual representation of the field of view  400  of the camera  154 . For example, an application executing on the user&#39;s client device  800 , such as a smartphone, may show a live view from the camera  154  of the user&#39;s A/V recording and communication doorbell  130  on the display  806  of the user&#39;s client device  800  ( FIG. 28 ). The configuration process may prompt the user to designate one or more intrusion zones  402  by selecting areas on the display  806  of the user&#39;s client device  800 . For example, the user may draw one or more polygons  404 ,  406 ,  408  on the display  806  to designate the intrusion zone(s)  402 . If the display  806  of the user&#39;s client device  800  is a touchscreen, the user may designate the intrusion zone(s)  402  by tracing the polygon(s)  404 ,  406 ,  408  on the display  806  with his or her finger. The configuration process may enable the user to designate intrusion zone(s)  402  having any shape and/or number of sides. For example, the intrusion zone(s)  402  may be regular polygons such as the square  404 , rectangle  406 , and hexagon  408  shown in  FIG. 24 , or any other type of regular polygon such as circles, pentagons, octagons, decagons, etc., or any type of irregular polygons. The configuration process may allow the user to designate any number of intrusion zones  402 , such as one intrusion zone  402 , two intrusion zones  402 , three intrusion zones  402 , etc. When all desired intrusion zones  402  have been created, the configuration process may prompt the user to save the intrusion zones  402 , after which the created intrusion zones  402  may be sent from the user&#39;s client device  800  to a device in the network, such as a server  900 C ( FIG. 29 ), and to the user&#39;s A/V recording and communication doorbell  130  via the user&#39;s network  110  ( FIG. 1 ). 
     After one or more intrusion zones  402  have been designated, embodiments of the present motion detection algorithms and techniques may incorporate those intrusion zones  402 . For example, the camera  154 , which may be powered on at all times, may continuously monitor motion within the field of view  400 . The A/V recording and communication doorbell  130 , however, may not begin recording and/or streaming video to the user&#39;s client device  800  unless and until a moving object enters one of the intrusion zones  402 . The recording and/or streaming may continue until the moving object exits the intrusion zone  402  it earlier entered. Further, if the moving object stops moving, but remains in the intrusion zone  402 , the recording and/or streaming may continue while the object remains stationary within the intrusion zone  402 . This aspect of the present embodiments creates an advantage over systems that rely on other types of motion sensors, such as passive IR sensors, that typically only detect moving objects, and therefore do not typically record and/or stream stationary objects. The object may, of course, be a person. 
     Some of the present embodiments may incorporate motion detection algorithms and techniques that vary according to the level of ambient light. Generally, the quality of video recorded during daylight hours is good enough to detect moving objects of interest while correctly filtering out other unnecessary and unwanted moving objects (e.g. tree branches or flags swaying in the wind, sun glare, etc.). At night, however, the A/V recording and communication doorbell  130  turns on the IR light source  156  to increase the incoming light intensity. However, the light intensity level can be affected by other light sources, such as porchlights, outdoor security lights, streetlights, and headlights of passing cars. These light sources are preferably filtered out in order to reduce false positives (also referred to as false alarms). Thus, to accurately detect moving objects of interest while correctly filtering out other unnecessary and unwanted moving objects, embodiments of the present A/V recording and communication doorbell  130  may use different motion detection algorithms during the day versus at night. 
     For example, as discussed above, the A/V recording and communication doorbell  130  may not begin recording and/or streaming video to the user&#39;s client device  800  unless and until a moving object enters one of the intrusion zones  402 . During periods of low levels of ambient light, however, such as after nightfall, the A/V recording and communication doorbell  130  may not begin recording and/or streaming video to the user&#39;s client device  800  unless and until the moving object that enters one of the intrusion zones  402  is a human. In some of the present embodiments, a process for determining whether a moving object is a human compares characteristics of the motion of the moving object with a dataset. For example, in each frame, the A/V recording and communication doorbell  130  may detect object regions, extract features from those object regions, and then compare those features with trained features in the dataset. If a comparison score and a confidence level are above a pre-defined threshold, then the algorithm returns a positive output (e.g. human) on the detected object region. Thus, for example, during daylight hours the A/V recording and communication doorbell  130  may begin recording and/or streaming video to the user&#39;s client device  800  as soon as any moving object enters one of the intrusion zones  402 , but during nighttime hours the A/V recording and communication doorbell  130  may begin recording and/or streaming video to the user&#39;s client device  800  only if the moving object that entered one of the intrusion zones  402  is a human. 
     Differentiating between moving humans and moving non-human objects during nighttime hours may help to reduce false positives, because nighttime motion detection can be affected by uneven lighting conditions. For example, at night an A/V recording and communication doorbell may interpret a sudden change in ambient light, such as a porchlight being turned on, as motion. These kinds of false positives are reduced in the present embodiments by limiting recording and/or streaming video to the user&#39;s client device  800  to those instances when a detected object in an intrusion zone  402  is a human. 
     One example embodiment of a technique for determining whether a detected object in an intrusion zone  402  is a human is tracking moving objects by tracking the center of mass of each object, and predicting the trajectory of the object based on the observed motion of the center of mass. In some embodiments, the center of mass for an arbitrary shape of a detected region may be calculated as an average of multiple small centroid regions. With a finite number of small centroids, the total centroid can be calculated as: 
     The centroid of a finite set of k points x1, x2, . . . xk, in Rn is
 
 C =( x   1   +x   2   + . . . +x   k )/ k  
 
     Tracking moving objects by tracking the center of mass of each object, and predicting the trajectory of the object based on the observed motion of the center of mass, can advantageously reduce false positives. For example, a person moving through the camera  154 &#39;s field of view  400  typically follows a predictable trajectory. If the person is moving in a first direction at a given instant, the person is likely to be moving in that same direction in the next instant. By contrast, many objects that move within the camera  154 &#39;s field of view  400  follow very unpredictable trajectories. For example, a tree branch swaying in the breeze follows a somewhat random trajectory that depends upon which way the wind is blowing at any given moment. Thus, by attempting to predict the trajectory of the center of mass of an object moving through the camera  154 &#39;s field of view  400 , and then determining whether the object actually follows the predicted trajectory, the present embodiments can make an educated guess as to whether an object being tracked is an object of interest, such as a person, or another object, such as a tree branch. With this trajectory analysis, embodiments of the present A/V recording and communication doorbell  130  can successfully distinguish objects of interest from false positives by combining the trajectory analysis with detection of other changes in each frame. 
     Some of the present embodiments provide advantageous night vision algorithms and techniques for determining when to activate night vision mode and when to deactivate night vision mode. When night vision mode is activated, the IR light source  156  may be illuminated (turned on), the IR cut filter  158  may be turned off, and the camera  154  may transition from color mode to grayscale mode. Conversely, when night vision mode is deactivated, the IR light source  156  may be turned off, the IR cut filter  158  may be turned on, and the camera  154  may transition from grayscale mode to color mode. 
     In one example technique, some embodiments of the present night vision algorithms may measure the average luminance of the pixels and the average standard deviation of the pixels in each frame of video shot by the camera  154 . The average luminance and the average standard deviation may then be tracked across frames by keeping a running average of each value. If the running averages of both values fall below a first pair of threshold values, then the A/V recording and communication doorbell  130  may activate night vision mode. Conversely, if the running averages of both values rise above a second pair of threshold values, then the A/V recording and communication doorbell  130  may deactivate night vision mode. For example, if the running average of the average luminance (AL) falls below a first threshold value (AL1), and the running average of the average standard deviation (ASD) falls below a first threshold value (ASD1), then the A/V recording and communication doorbell  130  may activate night vision mode. Conversely, if the running average of the average luminance (AL) rises above a second threshold value (AL2), and the running average of the average standard deviation (ASD) rises above a second threshold value (ASD2), then the A/V recording and communication doorbell  130  may deactivate night vision mode. Using separate threshold values for activating night vision mode versus deactivating night vision mode helps to prevent the A/V recording and communication doorbell  130  from oscillating between night vision mode and non-night vision mode during periods of fading light, such as dusk, and periods of rising light, such as dawn. 
     In some embodiments, sudden changes in light conditions may be ignored when tracking the running averages of the average luminance (AL) and the average standard deviation (ASD). For example, when night vision mode is active (e.g. after nightfall), if a porchlight is turned on near the A/V recording and communication doorbell  130  the average luminance and the average standard deviation in the pixels will suddenly spike. But, it is still after nightfall and the porchlight may soon be turned off, so it may be advantageous to keep night vision mode active. Some of the present embodiments, therefore, may not factor these sudden changes in the values AL and ASD into the running averages for those values. 
     In some embodiments, the proximity of the A/V recording and communication doorbell  130  to large objects or structures may affect whether night vision mode is activated or deactivated. For example, if the A/V recording and communication doorbell  130  is located directly across from a wall of a structure, a large percentage of the IR light generated by the IR light source  156  may be reflected back toward the camera  154 . This reflected IR light could cause the A/V recording and communication doorbell  130  to deactivate night vision mode even under conditions of low ambient light, because the IR light reflected into the camera  154  increases the average light intensity value. A conventional night vision algorithm based on frame intensity level would cause night vision mode to be deactivates even when the current ambient light level was low. Thus, some of the present embodiments may compensate for this situation by measuring how many pixels in the field of view  400  of the camera  154  are saturated. Then, by comparing the number of saturated pixels to a threshold value, the process can determine whether to maintain the A/V recording and communication doorbell  130  in night vision mode. For example, if night vision mode is active, and the number of saturated pixels is above the threshold value, then night vision mode may remain active even when the values of AL and ASD rise above the second pair of threshold values (AL2, ASD2). 
     As described above, the present embodiments advantageously limit the power consumption of the A/V recording and communication doorbell to an amount that is below the threshold necessary for causing the signaling device to sound (except when the front button of the doorbell is pressed). The present A/V recording and communication doorbell can thus be connected to the existing household AC power supply and the existing signaling device without causing inadvertent sounding of the signaling device. 
     Several advantages flow from the ability of the present embodiments to be connected to the existing household AC power supply. For example, the camera of the present A/V recording and communication doorbell can be powered on continuously. In a typical battery-powered A/V recording and communication doorbell, the camera is powered on only part of the time so that the battery does not drain too rapidly. The present embodiments, by contrast, do not rely on a battery as a primary (or sole) power supply, and are thus able to keep the camera powered on continuously. Because the camera is able to be powered on continuously, it can always be recording, and recorded footage can be continuously stored in a rolling buffer or sliding window. In some embodiments, about 10-15 seconds of recorded footage can be continuously stored in the rolling buffer or sliding window. Also because the camera is able to be powered on continuously, it can be used for motion detection, thus eliminating any need for a separate motion detection device, such as a passive infrared sensor (PIR). Eliminating the PIR simplifies the design of the A/V recording and communication doorbell and enables the doorbell to be made more compact. Also because the camera is able to be powered on continuously, it can be used as a light detector for use in controlling the current state of the IR cut filter and turning the IR LED on and off. Using the camera as a light detector eliminates any need for a separate light detector, thereby further simplifying the design of the A/V recording and communication doorbell and enabling the doorbell to be made even more compact. 
     As discussed above, another aspect of the present embodiments includes the realization that, in current A/V recording and communication doorbell systems other than the present embodiments, using the camera alone for detecting motion may have drawbacks under certain circumstances. For example, during nighttime hours the level of ambient light about the doorbell may be low. Since the camera detects motion by comparing successive video frames, if there is inadequate light to illuminate the field of view of the camera, then the camera may be unable to detect changes in successive video frames. Providing an illumination source, such as infrared LEDs, during nighttime hours may compensate for this issue. However, infrared LEDs may have range limitations. For example, infrared LEDs may not be well suited for illuminating the camera&#39;s field of view beyond a certain distance, such as about fifteen feet. The present embodiments solve this problem by providing a motion sensor in addition to the camera. For example, in some of the present embodiments the motion sensor may comprise one or more passive infrared (PIR) sensors. PIR sensors detect changes in the amount of IR radiation impinging upon them, which varies depending on the temperature and/or surface characteristics of the object(s) in front of the sensors. PIR sensors are thus effective at detecting motion even under low light conditions, particularly motion of persons and other objects that generate heat. Further, the PIR sensors may be effective at detecting objects at great distances from the camera, such as thirty feet or more. The PIR sensors thus may provide increased range as compared to infrared LEDs. In some of the present embodiments, therefore, the PIR sensor(s) enhance the motion detecting capabilities of the doorbell, particularly when there is a low level of ambient light about the doorbell. In some embodiments, one or more of the PIR sensor(s) may comprise a pyroelectric infrared sensor. 
       FIGS. 25-27  illustrate another embodiment of an A/V recording and communication doorbell  430  according to the present disclosure. The doorbell  430  includes many of the same components and much of the same functionality as the doorbell  130  shown in  FIGS. 3-24 . Thus, for simplicity, components that are common to both doorbells  130 ,  430  will be labeled with the same reference numbers in the figures. 
     With reference to  FIG. 25 , the doorbell  430  includes a PIR sensor  432  integrated within the front button  434 . Generally, a PIR sensor detects changes in the amount of infrared radiation impinging upon it, which varies depending on the temperature and/or surface characteristics of the object(s) in front of the sensor. When an object, such as a person, passes in front of the sensor, the temperature at that point in the sensor&#39;s field of view rises from ambient temperature to body temperature. The PIR sensor converts the resulting change in the incoming infrared radiation into a change in an output signal (e.g., a voltage), which triggers the detection. Objects of similar temperature but different surface characteristics may also have a different infrared emission pattern, and thus moving them with respect to the background may trigger the PIR sensor as well. In various embodiments, the PIR sensor  432  may be any type of sensor capable of detecting and communicating the presence of a heat source within its field of view. Further, alternative embodiments may comprise one or more motion sensors either in place of or in addition to the PIR sensor  432 . Such alternative motion sensors may be configured to detect motion using any methodology, such as a methodology that does not rely on detecting the presence of a heat source within a field of view. 
     With reference to  FIG. 26 , the PIR sensor  432  is located behind a front cover  436  of the front button  434 . The front cover  436  preferably comprises a material that is substantially transparent to infrared radiation so that it does not interfere with the operation of the PIR sensor  432 . For example, in some embodiments the material of the front cover  436  may comprise one or more plastic materials, such as polycarbonate, ABS, or polyethylene. With reference to  FIG. 27 , the PIR(s)  432  is/are operatively connected to the processor  160 . When the PIR sensor  432  detects a change in the incoming infrared radiation, it produces an output signal (e.g., a voltage) to the processor  160 , which indicates to the processor  160  that motion is present in the field of view of the PIR sensor  432 . 
     In the illustrated embodiment, only one PIR sensor  432  is provided, but in alternative embodiments any number of PIR sensors  432  may be provided. Further, in the illustrated embodiment the PIR sensor  432  is integrated within the front button  434 , but in alternative embodiments the PIR sensor  432 ( s ) may be located in another area of the doorbell  430  away from the front button  434 . Nevertheless, locating the PIR sensor  432  within the front button  434  provides advantages. For example, locating the PIR sensor  432  within the front button  434  leverages available space within the outer envelope of the doorbell  430  so that the size of the doorbell  430  does not need to be increased in order to accommodate the PIR sensor  432 . Further, in some embodiments, the front cover  436  of the front button  434  may comprise a Fresnel lens. For example, an outer surface  440  of the front cover  436  may be substantially smooth and curved (e.g., spherically curved) and an inner surface  442  of the front cover  436  may include a plurality of ridges. The Fresnel lens is thus configured to focus incoming light (including infrared radiation) passing through the front cover  436  onto the PIR sensor  432 , thereby increasing the sensitivity and/or detection range of the PIR sensor  432 . Locating the PIR sensor  432  within the front button  434  thus provides the further advantage that the front cover  436  may comprise a Fresnel lens that increases the sensitivity and/or detection range of the PIR sensor  432 . In some embodiments, the PIR sensor  432  may be capable of detecting objects that are thirty feet away or more from the A/V recording and communication doorbell  430 , which may be a longer range than the camera  154  can achieve under nighttime or low light conditions when the field of view is illuminated by the IR light source  156 . 
     The A/V recording and communication doorbell  430  of  FIGS. 25-27 , which includes both the camera  154  and the PIR sensor  432 , may use both the camera  154  and the PIR sensor  432  for motion detection. This functionality provides advantages because the capabilities of the camera  154  and the PIR sensor  432  are in some ways complementary to one another, such that each component  154 ,  432  may compensate for one or more shortcomings of the other component  154 ,  432 , as described below. 
     For example, some advantages of the PIR sensor  432  include: Speed—object movements very quickly result in an output signal from the PIR sensor  432 ; Long range—objects can be detected from 30 feet away or more; and good nighttime sensing capability—no need for the field of view to be illuminated. In contrast, some disadvantages of the PIR sensor  432  include: False alarms created by unwanted moving objects; and no information provided about the object that caused the motion detection (e.g., no information about the object&#39;s size, location within the field of view, or distance from the PIR sensor  432 ). 
     Some advantages of the camera  154 , in its capacity for detecting motion, include: Accuracy—there is much more information available on an image domain than there is in a temperature change (which is what the PIR sensor  432  detects); Location specific—can be used to determine the location of an object within the field of view, which facilitates the creation of custom motion detection zones; and enables object classification—provides very reliable classification for the type of object (e.g., person, small animal, vehicle, etc.) within the field of view. In contrast, some disadvantages of the camera  154  include: Ambient lighting limitations—heavily dependent on the lighting conditions; and slow—requires time to analyze object in successive images before determining whether motion is present. 
     The present embodiments, by combining the functionalities of the camera  154  and the PIR sensor  432 , achieve numerous advantages. For example, the camera  154  and the PIR sensor  432  may compensate for each other&#39;s daytime and nighttime performance. During daytime hours (e.g., when there is a high level of ambient light), the camera  154  provides more reliable motion detection than the PIR sensor  432 , while during nighttime hours (e.g., when there is a low level of ambient light), the PIR sensor  432  provides more reliable motion detection than the camera  154 . Thus, in some embodiments, the camera  154  alone may be used for motion detection when there is a high level of ambient light, and the PIR sensor  432  alone may be used for motion detection when there is a low level of ambient light. The level of ambient light may be detected or measured using the camera  154  and/or a light sensor (described below with reference to  FIG. 27 ), and the detected/measured level of ambient light may be compared to one or more threshold values in order to determine if the level of ambient light is high or low. 
     In further embodiments, the camera  154  and the PIR sensor  432  may be used in tandem for motion detection, with a first one of the components  154 ,  432  detecting motion and the other one of the components  154 ,  432  independently verifying the motion detection before an alert is sent to the user&#39;s client device  114 . For example, if the PIR sensor  432  triggers a motion detection, the camera  154  may independently verify the detection before an alert is sent to the user&#39;s client device  114 , and if the camera  154  triggers a motion detection, the PIR sensor  432  may independently verify the detection before an alert is sent to the user&#39;s client device  114 . In this way, “false alarm” motion detections are reduced or eliminated and the reliability of the motion detection process is increased through an independent verification process. The independent verification process may be particularly advantageous during daytime hours, when the camera  154 , which is more reliable for motion detection under bright light conditions, may be used to independently verify motion detections by the PIR sensor  432 , and during nighttime hours, when the PIR sensor  432 , which is more reliable for motion detection under low light conditions, may be used to independently verify motion detections by the camera  154 . Further, during nighttime hours, the PIR sensor  432  may trigger a motion detection, the camera  154  may independently verify the motion detection, and, while the camera  154  is analyzing video frames to verify the motion detection, the PIR sensor  432  may validate continuous motion within the field of view. 
     Additional advantages that may be achieved by combining the functionalities of the camera  154  and the PIR sensor  432  in the present embodiments include, but are not limited to, the greater motion detection range of the PIR sensor  432  (e.g., 30 feet or more) as compared to the camera  154 , and the PIR sensor  432  can facilitate continuous sensor data reading and analyzing. 
     As discussed above, yet another aspect of the present embodiments includes the realization that, in current A/V recording and communication doorbell systems other than the present embodiments, under nighttime or low ambient light conditions reflected infrared light can confuse the camera as to the actual light intensity in the camera&#39;s field of view. For example, if the doorbell is located opposite a wall or other structure that reflects a significant amount of the infrared light from the infrared light source, the image seen by the camera may appear to be very bright, which may confuse the camera as to the actual light intensity level in the field of view. The present embodiments solve this problem by providing a light sensor  438  ( FIG. 25 ) in addition to the camera  154 . The light sensor  438  may be configured to detect light in both the infrared and visible spectrums, and to provide information to the processor  160  about the intensity of light in these spectrums in the camera  154 &#39;s field of view. The A/V recording and communication doorbell  430  is thus able to accurately detect the actual light intensity in the camera  154 &#39;s field of view so that the doorbell  430 &#39;s night vision functionality can be activated when needed, and deactivated when not needed. 
     With reference to  FIG. 25 , the light sensor  438  may be located next to the microphone  150 , above the camera  154 , and behind the upper portion  214  of the shield  192  ( FIG. 4 ), although the illustrated location for the light sensor  438  is just one non-limiting example. The light sensor  438 , which is operatively connected to the processor  160  ( FIG. 27 ), may detect the level of ambient light, and the processor  160  may use the detected level of ambient light to determine when to activate the camera  154 &#39;s night vision functionality. For example, the light sensor  438  may detect the level of ambient light, and the processor  160  may use the detected level of ambient light to control the current state of the IR cut filter  158  and to turn the IR light source  156  on and off. In some embodiments, the light sensor  438  alone may be used to detect the level of ambient light, while in other embodiments the camera  154  and the light sensor  438  may work in tandem to detect the level of ambient light. 
     With reference to  FIG. 27 , in some embodiments of the A/V recording and communication doorbell, the power manager  140  may further comprise a charge monitor (not shown) that monitors the level of charge in the rechargeable battery  142 . When the charge monitor indicates that the level of charge in the rechargeable battery  142  is low, such as below a preset threshold, the power manager  140  may direct incoming power from the DC/DC converter  138  to the rechargeable battery  142  in order to recharge the rechargeable battery  142 . 
       FIG. 28  is a functional block diagram of a client device  800  on which the present embodiments may be implemented according to various aspects of the present disclosure. The user&#39;s client device  114  described with reference to  FIG. 1  may include some or all of the components and/or functionality of the client device  800 . The client device  800  may comprise, for example, a smartphone. 
     With reference to  FIG. 28 , the client device  800  includes a processor  802 , a memory  804 , a user interface  806 , a communication module  808 , and a dataport  810 . These components are communicatively coupled together by an interconnect bus  812 . The processor  802  may include any processor used in smartphones and/or portable computing devices, such as an ARM processor (a processor based on the RISC (reduced instruction set computer) architecture developed by Advanced RISC Machines (ARM).). In some embodiments, the processor  802  may include one or more other processors, such as one or more conventional microprocessors, and/or one or more supplementary co-processors, such as math co-processors. 
     The memory  804  may include both operating memory, such as random access memory (RAM), as well as data storage, such as read-only memory (ROM), hard drives, flash memory, or any other suitable memory/storage element. The memory  804  may include removable memory elements, such as a CompactFlash card, a MultiMediaCard (MMC), and/or a Secure Digital (SD) card. In some embodiments, the memory  804  may comprise a combination of magnetic, optical, and/or semiconductor memory, and may include, for example, RAM, ROM, flash drive, and/or a hard disk or drive. The processor  802  and the memory  804  each may be, for example, located entirely within a single device, or may be connected to each other by a communication medium, such as a USB port, a serial port cable, a coaxial cable, an Ethernet-type cable, a telephone line, a radio frequency transceiver, or other similar wireless or wired medium or combination of the foregoing. For example, the processor  802  may be connected to the memory  804  via the dataport  810 . 
     The user interface  806  may include any user interface or presentation elements suitable for a smartphone and/or a portable computing device, such as a keypad, a display screen, a touchscreen, a microphone, and a speaker. The communication module  808  is configured to handle communication links between the client device  800  and other, external devices or receivers, and to route incoming/outgoing data appropriately. For example, inbound data from the dataport  810  may be routed through the communication module  808  before being directed to the processor  802 , and outbound data from the processor  802  may be routed through the communication module  808  before being directed to the dataport  810 . The communication module  808  may include one or more transceiver modules capable of transmitting and receiving data, and using, for example, one or more protocols and/or technologies, such as GSM, UMTS (3GSM), IS-95 (CDMA one), IS-2000 (CDMA 2000), LTE, FDMA, TDMA, W-CDMA, CDMA, OFDMA, Wi-Fi, WiMAX, or any other protocol and/or technology. 
     The dataport  810  may be any type of connector used for physically interfacing with a smartphone and/or a portable computing device, such as a mini-USB port or an IPHONE®/IPOD® 30-pin connector or LIGHTNING® connector. In other embodiments, the dataport  810  may include multiple communication channels for simultaneous communication with, for example, other processors, servers, and/or client terminals. 
     The memory  804  may store instructions for communicating with other systems, such as a computer. The memory  804  may store, for example, a program (e.g., computer program code) adapted to direct the processor  802  in accordance with the present embodiments. The instructions also may include program elements, such as an operating system. While execution of sequences of instructions in the program causes the processor  802  to perform the process steps described herein, hard-wired circuitry may be used in place of, or in combination with, software/firmware instructions for implementation of the processes of the present embodiments. Thus, the present embodiments are not limited to any specific combination of hardware and software. 
       FIG. 29  is a functional block diagram of a general-purpose computing system on which the present embodiments may be implemented according to various aspects of present disclosure. The computer system  900  may execute at least some of the operations described above. The computer system  900  may be embodied in at least one of a personal computer (also referred to as a desktop computer)  900 A, a portable computer (also referred to as a laptop or notebook computer)  900 B, and/or a server  900 C. A server is a computer program and/or a machine that waits for requests from other machines or software (clients) and responds to them. A server typically processes data. The purpose of a server is to share data and/or hardware and/or software resources among clients. This architecture is called the client-server model. The clients may run on the same computer or may connect to the server over a network. Examples of computing servers include database servers, file servers, mail servers, print servers, web servers, game servers, and application servers. The term server may be construed broadly to include any computerized process that shares a resource to one or more client processes. 
     The computer system  900  may include at least one processor  910 , memory  920 , at least one storage device  930 , and input/output (I/O) devices  940 . Some or all of the components  910 ,  920 ,  930 ,  940  may be interconnected via a system bus  950 . The processor  910  may be single- or multi-threaded and may have one or more cores. The processor  910  may execute instructions, such as those stored in the memory  920  and/or in the storage device  930 . Information may be received and output using one or more I/O devices  940 . 
     The memory  920  may store information, and may be a computer-readable medium, such as volatile or non-volatile memory. The storage device(s)  930  may provide storage for the system  900 , and may be a computer-readable medium. In various aspects, the storage device(s)  930  may be a flash memory device, a hard disk device, an optical disk device, a tape device, or any other type of storage device. 
     The I/O devices  940  may provide input/output operations for the system  900 . The I/O devices  940  may include a keyboard, a pointing device, and/or a microphone. The I/O devices  940  may further include a display unit for displaying graphical user interfaces, a speaker, and/or a printer. External data may be stored in one or more accessible external databases  960 . 
     The features of the present embodiments described herein may be implemented in digital electronic circuitry, and/or in computer hardware, firmware, software, and/or in combinations thereof. Features of the present embodiments may be implemented in a computer program product tangibly embodied in an information carrier, such as a machine-readable storage device, and/or in a propagated signal, for execution by a programmable processor. Embodiments of the present method steps may be performed by a programmable processor executing a program of instructions to perform functions of the described implementations by operating on input data and generating output. 
     The features of the present embodiments described herein may be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and/or instructions from, and to transmit data and/or instructions to, a data storage system, at least one input device, and at least one output device. A computer program may include a set of instructions that may be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program may be written in any form of programming language, including compiled or interpreted languages, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. 
     Suitable processors for the execution of a program of instructions may include, for example, both general and special purpose processors, and/or the sole processor or one of multiple processors of any kind of computer. Generally, a processor may receive instructions and/or data from a read only memory (ROM), or a random access memory (RAM), or both. Such a computer may include a processor for executing instructions and one or more memories for storing instructions and/or data. 
     Generally, a computer may also include, or be operatively coupled to communicate with, one or more mass storage devices for storing data files. Such devices include magnetic disks, such as internal hard disks and/or removable disks, magneto-optical disks, and/or optical disks. Storage devices suitable for tangibly embodying computer program instructions and/or data may include all forms of non-volatile memory, including for example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices, magnetic disks such as internal hard disks and removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, one or more ASICs (application-specific integrated circuits). 
     To provide for interaction with a user, the features of the present embodiments may be implemented on a computer having a display device, such as an LCD (liquid crystal display) monitor, for displaying information to the user. The computer may further include a keyboard, a pointing device, such as a mouse or a trackball, and/or a touchscreen by which the user may provide input to the computer. 
     The features of the present embodiments may be implemented in a computer system that includes a back-end component, such as a data server, and/or that includes a middleware component, such as an application server or an Internet server, and/or that includes a front-end component, such as a client computer having a graphical user interface (GUI) and/or an Internet browser, or any combination of these. The components of the system may be connected by any form or medium of digital data communication, such as a communication network. Examples of communication networks may include, for example, a LAN (local area network), a WAN (wide area network), and/or the computers and networks forming the Internet. 
     The computer system may include clients and servers. A client and server may be remote from each other and interact through a network, such as those described herein. The relationship of client and server may arise by virtue of computer programs running on the respective computers and having a client-server relationship to each other. 
     In a first aspect, a method for an audio/video (A/V) recording and communication doorbell system is provided, the A/V recording and communication doorbell including a camera, a speaker, a microphone, a power manager, a battery, an AC/DC rectifier, and a DC/DC converter, wherein the A/V recording and communication doorbell is connected to an external AC power source through the AC/DC rectifier and the DC/DC converter, the method comprising the power manager drawing power, up to a threshold power, from the AC power source, wherein the threshold power is measured at an output of the DC/DC converter; and when the power drawn from the AC power source reaches the threshold power, the power manager drawing supplemental power from the battery such that the power drawn from the AC power source never exceeds the threshold power as measured at the output of the DC/DC converter. 
     In an embodiment of the first aspect, the threshold power as measured at the output of the DC/DC converter is about 1.4 A. 
     In another embodiment of the first aspect, the A/V recording and communication doorbell further includes a button and an electronic switch, wherein when the button is depressed the electronic switch closes, thereby diverting power from the AC power source away from the power manager. 
     In another embodiment of the first aspect, when the electronic switch closes power from the AC power source is diverted through a signaling device to cause the signaling device to emit a sound. 
     In another embodiment of the first aspect, prior to the electronic switch closing, the power drawn from the AC power source flows through the signaling device and a shunt connected in parallel with the signaling device. 
     In another embodiment of the first aspect, prior to the electronic switch closing the shunt is in a low impedance state. 
     In another embodiment of the first aspect, when the electronic switch closes the shunt transitions to a high impedance state. 
     In another embodiment of the first aspect, the signaling device is electro-mechanical or electronic. 
     In another embodiment of the first aspect, the signaling device is external to the A/V recording and communication doorbell. 
     In another embodiment of the first aspect, the A/V recording and communication doorbell further includes a timer, wherein when the button is depressed the timer is activated and the electronic switch remains closed until the timer expires, unless the A/V recording and communication doorbell receives a notification that a call to a client device has been answered. 
     Another embodiment of the first aspect further comprises the electronic switch opening when the A/V recording and communication doorbell receives the notification that the call to the client device has been answered. 
     In another embodiment of the first aspect, the timer is a first timer and the A/V recording and communication doorbell further includes a second timer, the method further comprising the electronic switch opening, the second timer being activated when the electronic switch opens, and the electronic switch being prevented from closing again until after the second timer expires. 
     Another embodiment of the first aspect further comprises the A/V recording and communication doorbell, in response to the button being depressed, sending an alert signal and a video signal to a network device, the video signal including images captured by the camera. 
     Another embodiment of the first aspect further comprises, when the power drawn from the AC power source is below the threshold power, the power manager directing a portion of the power drawn from the AC power source to the battery to charge the battery. 
     In a second aspect, an audio/video (A/V) recording and communication doorbell system is provided, the A/V recording and communication doorbell comprising an A/V recording and communication doorbell including a camera, a speaker, a microphone, a power manager, a battery, an AC/DC rectifier, and a DC/DC converter, wherein the A/V recording and communication doorbell is connected to an external AC power source through the AC/DC rectifier and the DC/DC converter; wherein the power manager is configured to draw power, up to a threshold power, from the AC power source, wherein the threshold power is measured at an output of the DC/DC converter; and when the power drawn from the AC power source reaches the threshold power, the power manager is further configured to draw supplemental power from the battery such that the power drawn from the AC power source never exceeds the threshold power as measured at the output of the DC/DC converter. 
     In an embodiment of the second aspect, the threshold power as measured at the output of the DC/DC converter is about 1.4 A. 
     In another embodiment of the second aspect, the A/V recording and communication doorbell further includes a button and an electronic switch, wherein when the button is depressed the electronic switch is configured to close, thereby diverting power from the AC power source away from the power manager. 
     In another embodiment of the second aspect, the A/V recording and communication doorbell is further configured such that when the electronic switch closes power from the AC power source is diverted through a signaling device to cause the signaling device to emit a sound. 
     Another embodiment of the second aspect further comprises a shunt, wherein the A/V recording and communication doorbell is further configured such that, prior to the electronic switch closing, the power drawn from the AC power source flows through the signaling device and the shunt connected in parallel with the signaling device. 
     In another embodiment of the second aspect, prior to the electronic switch closing the shunt is in a low impedance state. 
     In another embodiment of the second aspect, when the electronic switch closes the shunt transitions to a high impedance state. 
     In another embodiment of the second aspect, the signaling device is electro-mechanical or electronic. 
     In another embodiment of the second aspect, the signaling device is external to the A/V recording and communication doorbell. 
     In another embodiment of the second aspect, the A/V recording and communication doorbell further includes a timer, wherein the A/V recording and communication doorbell is further configured such that when the button is depressed the timer is activated and the electronic switch remains closed until the timer expires, unless the A/V recording and communication doorbell receives a notification that a call to a client device has been answered. 
     In another embodiment of the second aspect, the electronic switch is configured to open when the A/V recording and communication doorbell receives the notification that the call to the client device has been answered. 
     In another embodiment of the second aspect, the timer is a first timer and the A/V recording and communication doorbell further includes a second timer, wherein the A/V recording and communication doorbell is further configured such that when the electronic switch opens the second timer is activated and the electronic switch is prevented from closing again until after the second timer expires. 
     In another embodiment of the second aspect, the A/V recording and communication doorbell is further configured to send, in response to the button being depressed, an alert signal and a video signal to a network device, the video signal including images captured by the camera. 
     In another embodiment of the second aspect, the A/V recording and communication doorbell is further configured such that when the power drawn from the AC power source is below the threshold power, the power manager directs a portion of the power drawn from the AC power source to the battery to charge the battery. 
     In a third aspect, a method for an audio/video (A/V) recording and communication doorbell system is provided, the A/V recording and communication doorbell including a camera, a speaker, a microphone, a button, and an electronic switch, wherein the A/V recording and communication doorbell is connected to an external power source, the method comprising the A/V recording and communication doorbell drawing power from the power source; the power flowing through a signaling device and a shunt connected in parallel with the signaling device, wherein the shunt is in a low impedance state; and when the button is depressed, the electronic switch closing and the shunt transitioning to a high impedance state, thereby diverting power from the power source through the signaling device to cause the signaling device to emit a sound. 
     In an embodiment of the third aspect, the signaling device is electro-mechanical or electronic. 
     In another embodiment of the third aspect, the signaling device is external to the A/V recording and communication doorbell. 
     In another embodiment of the third aspect, the A/V recording and communication doorbell further includes a timer, wherein when the button is depressed the timer is activated and the electronic switch remains closed until the timer expires, unless the A/V recording and communication doorbell receives a notification that a call to a client device has been answered. 
     Another embodiment of the third aspect further comprises the electronic switch opening when the A/V recording and communication doorbell receives the notification that the call to the client device has been answered. 
     In another embodiment of the third aspect, the timer is a first timer and the A/V recording and communication doorbell further includes a second timer, the method further comprising the electronic switch opening, the second timer being activated when the electronic switch opens, and the electronic switch being prevented from closing again until after the second timer expires. 
     Another embodiment of the third aspect further comprises the A/V recording and communication doorbell, in response to the button being depressed, sending an alert signal and a video signal to a network device, the video signal including images captured by the camera. 
     In another embodiment of the third aspect, the A/V recording and communication doorbell further comprises a rechargeable battery. 
     Another embodiment of the third aspect further comprises, in response to the button being depressed, comparing a power level of the rechargeable battery to a threshold value. 
     Another embodiment of the third aspect further comprises the electronic switch closing only if the power level of the rechargeable battery is equal to or greater than the threshold value. 
     In a fourth aspect, an audio/video (A/V) recording and communication doorbell system is provided, comprising an A/V recording and communication doorbell including a camera, a speaker, a microphone, a button, and an electronic switch, wherein the A/V recording and communication doorbell is connected to an external power source; wherein the A/V recording and communication doorbell is configured to draw power from the power source such that the power flows through a signaling device and a shunt connected in parallel with the signaling device, wherein the shunt is in a low impedance state; and when the button is depressed, the electronic switch is configured to close, thereby transitioning the shunt to a high impedance state and diverting power from the power source through the signaling device to cause the signaling device to emit a sound. 
     In an embodiment of the fourth aspect, the signaling device is electro-mechanical or electronic. 
     In another embodiment of the fourth aspect, the signaling device is external to the A/V recording and communication doorbell. 
     In another embodiment of the fourth aspect, the A/V recording and communication doorbell further includes a timer, wherein the A/V recording and communication doorbell is further configured such that when the button is depressed the timer is activated and the electronic switch remains closed until the timer expires, unless the A/V recording and communication doorbell receives a notification that a call to a client device has been answered. 
     In another embodiment of the fourth aspect, the electronic switch is configured to open when the A/V recording and communication doorbell receives the notification that the call to the client device has been answered. 
     In another embodiment of the fourth aspect, the timer is a first timer and the A/V recording and communication doorbell further includes a second timer, wherein the A/V recording and communication doorbell is further configured such that when the electronic switch opens the second timer is activated and the electronic switch is prevented from closing again until after the second timer expires. 
     In another embodiment of the fourth aspect, the A/V recording and communication doorbell is further configured to send, in response to the button being depressed, an alert signal and a video signal to a network device, the video signal including images captured by the camera. 
     In another embodiment of the fourth aspect, the A/V recording and communication doorbell further comprises a rechargeable battery. 
     In another embodiment of the fourth aspect, the A/V recording and communication doorbell is further configured to, in response to the button being depressed, compare a power level of the rechargeable battery to a threshold value. 
     In another embodiment of the fourth aspect, the A/V recording and communication doorbell is further configured to close the electronic switch only if the power level of the rechargeable battery is equal to or greater than the threshold value. 
     In a fifth aspect, an audio/video (A/V) recording and communication doorbell is provided, comprising a housing having an enclosure; a camera located at least partially within the enclosure; a speaker located at least partially within the enclosure; a microphone located at least partially within the enclosure; a button located at least partially within the enclosure and protruding outwardly from a front of the enclosure; and a shield located at the front of the enclosure; wherein the shield includes an upper portion that extends along the front of the enclosure above the button and a lower portion that extends along the front of the enclosure below the button; and wherein the camera is located behind the upper portion of the shield. 
     In an embodiment of the fifth aspect, the upper portion of the shield and the lower portion of the shield are separate pieces. 
     In another embodiment of the fifth aspect, the upper portion of the shield is transparent or translucent. 
     In another embodiment of the fifth aspect, the lower portion of the shield is transparent to infrared light, but partially or mostly opaque with respect to light in the visible spectrum. 
     Another embodiment of the fifth aspect further comprises a shell overlying the enclosure. 
     In another embodiment of the fifth aspect, the shell includes a recess that is sized and shaped to receive the enclosure in a close fitting engagement, such that outer surfaces of the enclosure abut conforming inner surfaces of the shell. 
     Another embodiment of the fifth aspect further comprises a back plate secured to a rear of the enclosure, wherein the back plate is sized and shaped such that edges of the back plate extend outward from edges of the enclosure, thereby creating a lip against which the shell abuts when the shell is mated with the enclosure. 
     In another embodiment of the fifth aspect, the shell includes a central opening in a front surface. 
     In another embodiment of the fifth aspect, the central opening is sized and shaped to accommodate the shield. 
     In another embodiment of the fifth aspect, the shield resides within the central opening of the shell such that a front surface of the shield is substantially flush with a front surface of the shell and there is little or no gap between outer edges of the shield and inner edges of the central opening in the shell. 
     In a sixth aspect, an audio/video (A/V) recording and communication doorbell is provided, comprising a housing having an enclosure; a camera located at least partially within the enclosure; a speaker located at least partially within the enclosure; a microphone located at least partially within the enclosure; a button located at least partially within the enclosure and protruding outwardly from a front of the enclosure; and a plurality of shells configured to overlie the enclosure; wherein each of the shells includes a recess that is sized and shaped to receive the enclosure in a close fitting engagement, such that outer surfaces of the enclosure abut conforming inner surfaces of each of the shells; and wherein each of the shells is a different color. 
     Another embodiment of the sixth aspect further comprises a shield located at the front of the enclosure. 
     In another embodiment of the sixth aspect, each of the shells includes a central opening in a front surface. 
     In another embodiment of the sixth aspect, the central opening is sized and shaped to accommodate the shield. 
     In another embodiment of the sixth aspect, the shield is configured to reside within the central opening of each of the shells such that a front surface of the shield is substantially flush with a front surface of each of the shells and there is little or no gap between outer edges of the shield and inner edges of the central opening in each of the shells. 
     In a seventh aspect, a method for an audio/video (A/V) recording and communication doorbell system is provided, the A/V recording and communication doorbell including a camera, a front button, a motion sensor, and a light sensor, the method comprising: detecting a level of ambient light using at least one of the camera and the light sensor; comparing the detected level of ambient light to a threshold value to determine whether the detected level of ambient light is high or low; when it is determined that the detected level of ambient light is high, detecting motion in a field of view of the A/V recording and communication doorbell using the motion sensor; attempting to independently verify the motion detection of the motion sensor using the camera; and sending an alert to a user&#39;s client device only when the camera independently verifies the motion detection the motion sensor. 
     In an embodiment of the seventh aspect, the motion sensor comprises a passive infrared (PIR) sensor. 
     In another embodiment of the seventh aspect, the motion sensor is integrated within the front button. 
     In another embodiment of the seventh aspect, the front button comprises a material that is substantially transparent to infrared radiation. 
     In another embodiment of the seventh aspect, the front button comprises a Fresnel lens configured to focus incoming light onto the motion sensor. 
     In another embodiment of the seventh aspect, an outer surface of the front button is substantially smooth and curved and an inner surface of the front button includes a plurality of ridges. 
     In another embodiment of the seventh aspect, the A/V recording and communication doorbell further comprises a speaker and a microphone. 
     In an eighth aspect, a method for an audio/video (A/V) recording and communication doorbell system is provided, the A/V recording and communication doorbell including a camera, a front button, a motion sensor, and a light sensor, the method comprising: detecting a level of ambient light using at least one of the camera and the light sensor; comparing the detected level of ambient light to a threshold value to determine whether the detected level of ambient light is high or low; when it is determined that the detected level of ambient light is low, detecting motion in a field of view of the A/V recording and communication doorbell using the camera; attempting to independently verify the motion detection of the camera using the motion sensor; and sending an alert to a user&#39;s client device only when the motion sensor independently verifies the motion detection the camera. 
     In an embodiment of the eighth aspect, the motion sensor comprises a passive infrared (PIR) sensor. 
     In another embodiment of the eighth aspect, the motion sensor is integrated within the front button. 
     In another embodiment of the eighth aspect, the front button comprises a material that is substantially transparent to infrared radiation. 
     In another embodiment of the eighth aspect, the front button comprises a Fresnel lens configured to focus incoming light onto the motion sensor. 
     In another embodiment of the eighth aspect, an outer surface of the front button is substantially smooth and curved and an inner surface of the front button includes a plurality of ridges. 
     In another embodiment of the eighth aspect, the A/V recording and communication doorbell further comprises a speaker and a microphone. 
     In a ninth aspect, an audio/video (A/V) recording and communication doorbell is provided, comprising a camera; a front button; and a motion sensor; wherein the camera and the motion sensor are configured to work in tandem to detect motion in a field of view of the A/V recording and communication doorbell such that a first one of the camera and the motion sensor detects motion and the other one of the camera and the motion sensor independently verifies the motion detection before an alert is sent to a user&#39;s client device. 
     In an embodiment of the ninth aspect, when the motion sensor triggers a motion detection, the camera independently verifies the motion detection before the alert is sent to the user&#39;s client device. 
     In another embodiment of the ninth aspect, when the camera triggers a motion detection, the motion sensor independently verifies the motion detection before the alert is sent to the user&#39;s client device. 
     In another embodiment of the ninth aspect, the motion sensor comprises a passive infrared (PIR) sensor. 
     In another embodiment of the ninth aspect, the motion sensor is integrated within the front button. 
     In another embodiment of the ninth aspect, the front button comprises a material that is substantially transparent to infrared radiation. 
     In another embodiment of the ninth aspect, the front button comprises a Fresnel lens configured to focus incoming light onto the motion sensor. 
     In another embodiment of the ninth aspect, an outer surface of the front button is substantially smooth and curved and an inner surface of the front button includes a plurality of ridges. 
     Another embodiment of the ninth aspect further comprises a light sensor. 
     In another embodiment of the ninth aspect, the light sensor is configured to detect light in both the infrared and visible spectrums. 
     Another embodiment of the ninth aspect further comprises a speaker and a microphone. 
     In a tenth aspect, an audio/video recording and communication device (A/V device) is provided, comprising: a camera; a motion sensor, wherein the motion sensor and the camera are configured to work in tandem to detect motion within a field of view of the A/V device; a communication module; a processor operatively connected to the camera, the motion sensor, and the communication module; and a memory storing a program comprising instructions that, when executed by the processor, cause the A/V device to: detect, using the camera, possible motion within the field of view of the A/V device; independently verify the possible motion by the camera using the motion sensor; and send an alert, using the communication module, to a client device. 
     In an embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to detect, using the camera, the possible motion within the field of view of the A/V device by capturing, using the camera, video and comparing successive video frames of the video to detect at least one change in the successive video frames. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to independently verify the possible motion by the camera using the motion sensor by detecting, using the motion sensor, the possible motion within the field of view of the A/V device. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to detect, using the camera, the possible motion within the field of view of the A/V device at a first time, and independently verify the possible motion by the camera using the motion sensor at a second time, wherein the second time is later than the first time. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to capture video using the camera. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to transmit, using the communication module, the video to a server. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to send the alert to the client device via a server. 
     In another embodiment of the tenth aspect, the motion sensor comprises at least one passive infrared (PIR) sensor. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to detect a level of ambient light and compare the detected level of ambient light to a threshold value to determine whether the detected level of ambient light is high or low. 
     In another embodiment of the tenth aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to, when the detected level of ambient light is high, forgo independently verifying the possible motion by the camera using the motion sensor. 
     In an eleventh aspect, an audio/video recording and communication device (A/V device) is provided, comprising: a motion sensor; a camera, wherein the camera and the motion sensor are configured to work in tandem to detect motion in a field of view of the A/V device; a communication module; a processor operatively connected to the motion sensor, the camera, and the communication module; and a memory storing a program comprising instructions that, when executed by the processor, cause the A/V device to: detect, using the motion sensor, possible motion within the field of view of the A/V device; independently verify the possible motion by the motion sensor using the camera; and send an alert, using the communication module, to a client device. 
     In an embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to independently verify the possible motion by the motion sensor using the camera by capturing, using the camera, video and comparing successive video frames of the video to detect at least one change in the successive video frames. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to detect, using the motion sensor, the possible motion within the field of view of the A/V device at a first time, and independently verify the possible motion by the motion sensor using the camera at a second time, wherein the second time is later than the first time. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to capture video using the camera. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to transmit, using the communication module, the video to a server. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to send the alert to the client device via a server. 
     In another embodiment of the eleventh aspect, the motion sensor comprises at least one passive infrared (PIR) sensor. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to detect a level of ambient light and compare the detected level of ambient light to a threshold value to determine whether the detected level of ambient light is high or low. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to, when the detected level of ambient light is low, forgo independently verifying the possible motion by the camera using the motion sensor. 
     In another embodiment of the eleventh aspect, the program comprises further instructions that, when executed by the processor, further cause the A/V device to, when the detected level of ambient light is low, while the camera is independently verifying the possible motion by the motion sensor, continuously validate, using the motion sensor, motion within the field of view of the A/V device. 
     The above description presents the best mode contemplated for carrying out the present embodiments, and of the manner and process of practicing them, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which they pertain to practice these embodiments. The present embodiments are, however, susceptible to modifications and alternate constructions from those discussed above that are fully equivalent. Consequently, the present invention is not limited to the particular embodiments disclosed. On the contrary, the present invention covers all modifications and alternate constructions coming within the spirit and scope of the present disclosure. For example, the steps in the processes described herein need not be performed in the same order as they have been presented, and may be performed in any order(s). Further, steps that have been presented as being performed separately may in alternative embodiments be performed concurrently. Likewise, steps that have been presented as being performed concurrently may in alternative embodiments be performed separately.