Digital Camera Working Principle
Camera is a device which is used to record images or videos. Modern digital camera does not use film to record the images. In this article we are going to study “Digital Camera Working Principle”.
Digital camera is an combination of array of photoelectric sensor, and the same record the incoming pattern of light. Each sensor returns an electrical current when it’s struck by the incoming light.
Because the amount of current that’s returned varies with the amount of light, your digital camera’s electronic innards can combine the different current levels into a composite pattern of data that represents the incoming light — in other words, an image in the form of a binary file.
System layout of Digital Camera
It is divided into component and sub system as and lay them out in them in the system diagram. We need the input tell the smart phone to allow the camera application to take the picture. This input is red UR screen that measures changes in capacitance in the output X and Y coordinate or more touches. This input feeds into CPU and RAM.
The CPU acts as brain and thinking power of a smart phone. RAM is the working memory it is like of thinking our-self as any moment. Software and program of the any movement camera application moved from the smart phone storage location in this case solid state drive into RAM.
It would be wasteful smart phone always have camera application loaded in active working memory RAM. Once camera software is loaded camera is an activated light sensor measure the brightness of the environment and laser range measures the distance of the objects in front of the camera.
Based on these readings CPU and software sets the electronics shutter to limit amount of incoming light. The miniature motor moves the camera lens forward and backward in order to get object in focus. The active in image from sent back to the display depending on the environment in the LED is used to eliminate the seen.
Finally the camera triggered picture is taken and sent to the display for review and to solid state drive for storage.
This is the lot of rather complex components and they are still two more critical puzzle is power supply and wires. All of the component needs electricity and from the battery pack and power regulator. Wires carry these components where separate wires carry electrical signals allows communicating between each other.
The printed circuit board contains lots of components having CPU, RAM, solid state drive are maintained.
Analogy between a smart phone and human
There is a system layout of the smart phone and human body.
The human body it might have similar function those we have described sub system of a smart phone.
For example CPU is the brain of the problem solving area where RAM is short term memory. These are comparison we can operate.
Interesting to find so many common between these two which are different nervous and signal wires both are high speed signal to different areas of the body. Where smart phone electrical pulses one is made of copper and one is made of cells. Also human mind is similar level of memory to that of CPU and RAM and solid state drive.
The human eye the cornea is the outer lens takes the wider angle of light and focus. The amount of light passing into the eye is limited by Iris. Second lens shape can be changed by the muscles around it then light to focus the image.
This focused image travel to the eye and hits the Retina. Here massive create is lot of ROD cells and core cells absorbs the photons of light and output electrical signals to the nerve fiber goes to the brain for processing.
Rods can observe the all types of colours in visible light and output black and white image. The three types of cones cells observe red, green and blue and blue provide colour damage.
Now this brings us the question if eye has three different types of cone cells each absorb only red, green and blue. How do we see this entire spectrum of colour?
The red, green and blue cone absorbs the range of light not just single colour. This means the blue cone picks up the little rate in the range of purple as well as in the awkward range.
Eyes don’t detect the single light wavelength at a time rather the mixed of wavelength this mixed shows the unique colour
Digital Camera Lens Working:
The smart phone camera has a set of lenses with motor to allow changes the focus.
These lenses take wide angle of light and focuses to create a clear image. The electric shutter controls the amount of light that hits the sensor. After the back camera a massive create of microscopic light Sensitive Square. They create a circuit called image sensor each individual light sensitive square is called pixel.
A 16 megapixel camera has about 16 million of tiny light sensitive squares or pixels in a rectangular in a rectangular grid. If we zoomed an actual sensor as well as more zoomed a cross section of the pixel. The micro lens and colour filter fixed top of the each individual pixel to fresh focus the light. Then each one has red, green, and blue there by allowing only that specific range of light passes through and triggers the pixel.
The lighted zone is the light sensitive region called photo diode.
The photo diode observes the photons and observes energy into electricity. When photon hits the junction of materials in the photo diode called PN junction atoms to absorb photons energy and jumps into a higher energy state and leaves the atom.
Usually electrons recombine with the atom extra energy will be converted back into layer. The rejected electron pushed away and it can’t recombine with atom. When lot of photons reject the electrons and current of electrons builds up and current can be measured.
In the sensor there is lot of additional circuits beyond the photo-diodes that is required to read and required each value for all 16 million light sensitive squares. The most common method of reading of electrical current is row by row specially one row is spread out ADC at a time. Rolling electronic shutter is a timed with row value reading in order to turn off the sensor sensitive light.
The ADC build up a electrons converts into digital value from 0-4095 is stored in a 12 bit memory location.