You are referring to 1/4" and 1/3" image sensors (CCD). The bigger the image sensor in a CCD camera a better image resolution can be achieved. Having multiple sensors is even better, but to answer your question 1/3" is better.
why we use LED in a hidden CCD camera?
CCD = Charge Coupled Device.
In the past, cameras took still photos and videos by focusing light on film. Now, in a CCD video camera, the lens of the camera focuses light onto a small CCD sensor. CCD stands for "charge-coupled device."
Firstly CMOS and CCD are manufactured differently, yet they perform the same process. CMOS sensors are more susceptible to noise, whereas, CCD sensors create high quality, low-noise image. This then makes the difference between them. So CMOS generally has lower pixels and longer battery life, plus a cheaper option, CCD uses more power and has higher pixels, and is more expensive. So depending on you budget, and what you are looking for in a camera. This could help you make up your mind of how much you can afford to spend, and what quality of camera you are looking for.
CCD stands for charge-coupled device
The price of a color CCD camera can vary depending on the brand and features. Most color CCD cameras are between $200 and $1200. There are a lot of factors that go into choosing one and the CCD camera with the best features tends to be the one that is the highest price.
A CCD camera uses a special chip which detects light photons hitting an array. This data is then converted to binary which can then be interpreted by the camera into an image.
The CCD is the part of the camera that changes the light that enters the camera into a digital signal that is then saved on the memory card. You can think of it as where the film would be in a regular 35mm film camera.
One of the best types of cameras to attach to a microscope for specimen images is a CCD camera. A CCD camera is also known as a charge coupled device camera.
Sensors are devices that can take the light let into the camera and convert the bits of data into colored pixels, "digitalizing" it, if you will. The two sensors are CCD (charge coupled device) and CMOS (complimentary metal-oxide semiconductor) sensors. They each have their pros and cons and are used in different cameras for different reasons.
CCD Sensor (in a digital camera) = Retina