Patent Publication Number: US-2016231169-A1

Title: Infrared detecting switch for surveillance camera

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 201510065871.6 filed on Feb. 9, 2015, the contents of which are incorporated by reference herein. 
     FIELD 
     The subject matter herein generally relates to infrared detecting switch for surveillance cameras. 
     BACKGROUND 
     Surveillance cameras may include video cameras which can be used for observing an area. The surveillance cameras are often connected to recording devices through network, and may be viewed for security reasons. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is a block diagram of an embodiment of an infrared detecting switch for a surveillance camera. 
         FIG. 2  is a circuit diagram of the infrared detecting switch for the surveillance camera of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. 
       FIG. 1  illustrates an infrared detecting switch for a surveillance camera in accordance with an embodiment. The infrared detecting switch includes a detector  100 , an amplifier circuit  200 , a switch circuit  300 , and a surveillance camera  400 . 
       FIG. 2  illustrates that the detector  100  includes a detector  110 , a first resistor R 1 , a second resistor R 2 , and a capacitor C. The detector  110  includes a gate, a source, and a drain. The gate of the detector  110  is grounded. The source of the detector  110  is grounded via the first resistor R 1 . The drain of the detector  110  receives a first DC voltage via the second resistor R 2 . The drain of the detector  110  is grounded via the capacitor C. In one embodiment, the detector  110  is an infrared heat detector. The first DC voltage is about +5 volts. 
     The amplifier circuit  200  includes an amplifier  210 , a third resistor R 3 , a fourth resistor R 4 , and a fifth resistor R 5 . The amplifier  210  includes an inverting input terminal, a non-inverting input terminal, an output terminal, and a power terminal. The non-inverting input terminal of the amplifier  210  is electrically coupled to the source of the detector  110  via the third resistor R 3 . The inverting input terminal of the amplifier  210  is grounded via the fourth resistor R 4 . The inverting input terminal of the amplifier  210  is electrically coupled to the output terminal of the amplifier  210  via the fifth resistor R 5 . The power terminal of the amplifier  210  receives the first DC voltage. 
     The switch circuit  300  includes a MOSFET Q, a sixth resistor R 6 , and a seventh resistor R 7 . The MOSFET Q includes a gate, a source, and a drain. The gate of the MOSFET Q is electrically coupled to the output terminal of the amplifier  210 . The source of the MOSFET Q is grounded via the sixth resistor R 6  and is electrically coupled to the surveillance camera  400 . The drain of the MOSFET Q receives a supplying DC voltage via the seventh resistor R 7 . In one embodiment, the MOSFET Q is an n-channel MOSFET. The supplied DC voltage is about +3.3 volts. A resistance of the sixth resistor R 6  is about 1000 ohm. A resistance of the seven resistor R 7  is about 1000 ohm 
     In use, when a person moves into a surveillance area of the surveillance camera  400 , the detector  110  detects infrared radiation emitted by the person. The detector  110  outputs a voltage signal to the amplifier  210 . The non-inverting input terminal of the amplifier  210  receives the voltage signal and amplifies the voltage signal. The MOSFET Q turns on when the gate of the MOSFET Q receives the amplified voltage signal. The surveillance camera  400  is coupled to the supplying DC voltage and being supplied. The surveillance camera  400  can work to take videos. 
     In one embodiment, the detector  110  can detect an infrared radiation which is can be recognized as a person to output the voltage signal. 
     The embodiments shown and described above are only examples. Many details are often found in the art such as the other features of an infrared detecting switch for surveillance camera. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the details, including in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.