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Insight - How WebCam works

Written By: 

Arpit Jain

 

Webcam is a device used to capture images, audio and videos. Webcam are either inbuilt or can be externally attached with the laptop or the computer.  The most common application of a webcam is video chat, video recording, image capturing. A webcam generally consist of a lens, an image and sound sensors, electronic circuitry to process the data and send it to PC.  A variety of webcams with different features are available in the markets. Depending on the features and quality, the technologies used and the prices vary. However the basic function remains the same.

Webcam

Fig. 1: Image of Laptop Webcam

 

The webcam attached on the laptop is shown in the image above.  You can see an optical lens to capture the images/videos and a small hole to capture sound. The bottom part of the body consists of a plastic casing which provides support to the webcam and a mechanism to fix the webcam on the top of the laptop.

Neck

webcam neck

Fig. 2: Rotating Neck of Webcam

 

The neck of this webcam can rotate along the horizontal and vertical axis up to certain angles. The rotation is restricted by means of mechanical stoppages which will be shown later in the article.

Mechanical Hooks

webcam hooks
 
Fig. 3: Image Indicating Hooks that Bind Together Front and Back of Webcam
 
The front and back face of the plastic casing are fixed to each other by means of four mechanical hooks. Two of them are visible in the image above and the other two are just opposite to them. 

Bottom Assembly

 

Components of Webcam

Fig. 4: Inside View of Plastic Casing

 

The plastic casing from inside is shown in the image above.
 
Body of webcam
 
Fig. 5: Spring-Loaded Screw Mechanism of Laptop
 
In order to fix the webcam on the laptop a spring loaded screw mechanism is used. The front face of the bottom part can be pulled to fix on the laptop. A spring force keep it fixed.

Neck Movement Mechanism 

Webcam Neck Movement Structure
 
Fig. 6: Image Indicating Mechanics of Neck Movement of Webcam
 
How webcam works7
 
Fig. 7: Plastic Casing with Slot for Rubber Rings
 
The mechanical structure of the neck of the webcam is responsible for its motion along the horizontal and vertical axis. The two rubber rings at the end of the cylindrical rod have a special shape to provide the rotational movement.  The casing has a special slot for the rubber rings.  

Top Half Internal Structure

Internal Structure of Webcam

Fig. 8: Electronic Circuitry at Top of Webcam

 

The top part of the webcam contains all the electronic circuitry required to do its job. It is guarded by a pair of plastic casing which are fixed to each other by means of mechanical hooks.

PCB-Back View

PCB in Webcam
 
Fig. 9: PCB and Wire Connections
 
The PCB which contains all the electronic components embedded in it is shown in the image above.

PCB-Front View

Webcam Circuit Diagram
 
Fig. 10: PCB Configuration
 
The other side of the PCB showing the major components: lens, CMOS sensor, microphone, semiconductor chips etc.

Microphone

Microphone in Webcam
 
Fig. 11: Microphone and PCB Setting
 
The microphone also called the sound sensor is used to capture the sound signals and convert them into electrical signals for further processing by the processor. An electret condenser microphone is used for this purpose. Refer to the working of electret condenser microphone for details.

CMOS Sensor

CMOS Sensor in Webcam
 
Fig. 12: CMOS Image Sensor of Laptop Webcam
 
The image/video sensor, which is the most important part of the webcam, is shown in the image above. The sensor used here is a CMOS Image sensor. The purpose of the image sensor is to convert the optical light signals into electrical signals. A CMOS sensor is made up of an array of photo detector with amplifiers, noise- correction and digitization circuit. It uses the CMOS technology for its manufacturing. The output of the CMOS sensor is digitalized signals.

Electronic Components

Webcam electronic Components
 
Fig. 13: ICs and Electronic Circuitry of PCB
 
The rest of the electronic components in the circuitry are shown in the image above. Two major semiconductor IC can be seen. 24C02 is a serial EEPROM memory manufactured by Atmel used to store the data. The data stored in this memory is not lost even when the power is turned off. VC0326 IC manufacture by Vimicro is a chip with many functions embedded in it. It has an 8- bit microcontroller, 10 bit imaging processor, JPEG encoder engine, inbuilt ADC, audio and video class USB support and complies with USB 2.0 protocols for transferring data to the PC. It collects the data from the image and the sound sensor, processes it and sends it to the PC using the USB.

Lens Housing

Webcam lens housing
 
Fig. 14: Lens of Webcam and its Housing Pattern
 
The lens is placed in a separate plastic housing which is screwed to the front plastic casing of the webcam. The housing ensures mechanical stability and protection from external damages.

Lens

Webcam Lens
 
Fig. 15: Close-up View of Lens
 
The lens of the webcam is generally made up of plastic and has a fixed focal length.  The focal length and aperture size define the quality of the lens.  A lens is used to focus the image of objects on the CMOS sensor.

Comments

Good Article!!!

thank"s ....

thanks to write this

it's great

IT WAS GOOD, THANKS 

thankyou so much.....smiley

Things are good but not as much expected. It's just overview of the things used in it, its not technical as required. Like, Try to co-relate all things like when CMOS Sensor catpure the image then what's next going to happen after it, what is further step and so on.
Just a Little bit of advice. Though, appreciate you effort.

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Regards
Gaurav Sharma

ya this information is very fantastic becoz i never seen such a variety things 

thanx a lot...!

 

Thanks

This site and given information is superb

Thank u very much....