Panoramic camera
Working principle of the camera
Working principle of the camera is approximately: scene through the lens (the LENS) an optical image generated by projecting onto the image sensor surface, and then converted to an electrical signal through the A / D (analog-digital conversion) converted into a digital image signal, and then sent to a digital signal processing chip (DSP) in processing, reprocessing through the USB interface to the computer, the image can be seen through the display.
sensor chip (SENSOR)
is an important part of a digital camera, depending on the divided elements:
CCD (Charge Coupled Device, CCD element) Application technical aspects of high photographic imaging element.
CMOS (Complementary Metal-Oxide Semiconductor, MOS element) applied to a lower image quality products.
It is a multi-element CCD size 1/3 inch or 1/4 inch, in the same resolution, should choose a larger element size as well.
CCD advantages are high sensitivity, low noise, signal to noise ratio. But the complicated production process, high cost, high power consumption.
CMOS has the advantage that high integration, low power (less than 1/3 CCD), and low cost. However, relatively large noise, low sensitivity, high requirements on the light source. CCD imaging often permeability, sharpness is good in the same pixel, color reproduction, exposure may be substantially guaranteed accurate. The permeability of CMOS products are often general, color reproduction of the kind of weak, exposure is also not very good.
Therefore, more should pay attention to technique when we use the camera, especially the use of CMOS chip products:
First, do not use (this CCD with) in backlit environments, in particular, not directly to the sun, or “magnifying glass to burn ants” tragedy occurs in your camera. Secondly ambient light is not too weak, otherwise directly affect image quality. There are two ways to overcome this difficulty, it is to strengthen the surrounding brightness, and second,Select the minimum illumination requirements of small products, and now some cameras already reached 5lux.
Finally, note that it is reasonable to use a zoom lens, do not underestimate this point, by proper adjustment, the camera also can have the function of the imaging chip. Currently, the market sales of digital cameras, the CCD and CMOS basically evenly divided. In the use of CMOS components of photosensitive product, the video source by using automatic gain reinforcement technology, automatic brightness, white balance control, color saturation, contrast, edge enhancement, gamma correction and other advanced image control technology, can and CCD camera to achieve comparable results. Limited by the market situation and market development, the camera uses a CCD image sensor of the few manufacturers, mainly due to high cost of CCD image sensor influence.
image sensor belongs to the optoelectronics industry in the photovoltaic element class, with the rapid development of digital technology, semiconductor manufacturing technology and network, the current market and industry are faced with various platforms across video, audio, large integrated communications era the arrival of the beauty of everyday life outlined the future of mankind. Its application in daily life, you have to belong to digital cameras, the rapid pace of development can be used to describe. Just a few years, digital cameras on the hundreds of thousands of pixels, the development of the 400, 500 million pixels or more. Not only in the developed western countries, the digital camera has a large market, is in the development of Chinese digital camera market is growing at an alarming rate, and therefore, its key components – becomes the current image sensors the object of concern to the industry and the future, attracting many manufacturers invest. Product class discrimination, the image sensor is divided into the product CCD, CMOS sensor and CIS three. This article will focus on technology and industry Introduction to CCD and CMOS sensor development status.
First, the CCD image sensor
CCD (Charged Coupled Device) in 1969 in the Bell Labs successfully developed, followed by a mass production companies such as the Japanese, the course of its development has been for nearly 30 years from over 10 million pixels it has grown to 500 early-megapixel mainstream applications. CCD can be divided into linear (Linear) and the plane type (Area) are two,Which is applied to the linear image scanner and fax machine, and face type is mainly used in digital cameras (DSC), the camcorders, surveillance cameras and many other video input products.
is generally considered, the CCD sensor has the following advantages:
1. The high resolution (High Resolution): size of the image points is μm level can be sensed and identified the fine object, to improve image quality . From the early 1 inch, 1/2 inch, 2/3-inch, 1/4-inch to 1/9 inch recently launched, the number of pixels from more than 10 million to the current 400 to 500 million pixels early;
[ 123] 2. low noise (low noise) high sensitivity: CCD readout noise with a very low dark current and noise, thereby improving the SNR (the SNR), while having high sensitivity, low luminosity incident light can be detected, which signal is not masked, so that application of CCD weather bound less affected;
3. the wide dynamic range (High dynamic range): detection and simultaneously running strong points light and low light, use of the system to improve the environment, not because of a large luminance signal difference caused by the phenomenon of contrast;
4. a good linear characteristic curve (linearity): intensity of incident light source and output signal magnitude as well proportional relationship, the object information without loss, reduces the signal compensation processing costs;
high photon conversion efficiency (high Quantum efficiency): very weak incident light can be recorded, if the match with the image intensifier tube and the emitter, even in the distant night scene still has To obtain detected;
The large area of the photosensitive (Large Field of View): may be manufactured using semiconductor technology has been a large-area wafer ccdd now comparable to conventional 35mm film size has started a CCD used in digital camera, a key element unsubstituted professional advantageous optical camera; wide
spectral response (broad spectral response): can detect a wide range of wavelengths, to increase system flexibility to expand system applications;
6. low image distortion (Low Image Distortion): using a CCD sensor, which image processing is not distorted in the case, so that the original object information faithfully be reflected;
7. The small size, light weight: CCD have small size and light weight characteristics, and therefore, the device can be easily and all kinds of satellite navigation systems;
Mao low power, is not strong electromagnetic field 8. Effect;
9. the charge transfer efficiency is good: the efficiency coefficient impact noise ratio, resolution rate, if the charge transfer efficiency is poor, the image becomes blurry;
10. the mass producible, stable quality, sturdy, not aging, easy to use and easy to maintain.
According to In-Stat noted in the 2001 report on the global image sensor, CCD industrial top seven vendors are all Japanese manufacturers, accounting for 98.5% of global market share, in terms of technological development, currently more featured major vendors should be Sony, Philips and Kodak.
Philips Advantages in CCD products for having the industry’s largest-size CCD sensor, digital camera applications, its 35mm-sized CCD has been used in “Contax” digital camera, become professional digital camera spokesperson. Secondly, the company also has a unique “Frame-Transfer CCD” (scanning surface) technology, the product application may be implemented in a rate of 30-60 frames per second. This is the true speed of the video signal.
using the Kodak CCD CCD acclaimed the ITO (indium tin oxide) technology, rather than the traditional silicone compound. Which is characterized by higher sensitivity, the light-transmissive increased by 20% than the average CCD, a breakthrough for the improved CCD sensor is generally weak blue interference and noise immunity aspect, it increased 2.5-fold induction of the blue light capability, while dramatically reducing noise interference, make the image more sharp, color is more accurate, provides high resolution for professional digital photography, image sharpness.
uses a conventional CCD photosensitive cells are rectangular, and two years ago developed Fuji “superccd (super honeycomb structure) using an octagonThe photosensitive unit, using a honeycomb structure of the octagon, therefore the photosensitive unit area than a conventional CCD. This will get three advantages, one can increase the sensitivity of the CCD, the second is to improve the dynamic range, third is to improve the signal to noise ratio. These three advantages plus SuperCCD generate higher pixel become the biggest selling point in Fuji digital camera products.
Function: the panoramic camera is not necessarily 360 degrees all imaging, but wider than the imaging angle is generally camera, imaging wide such ordinary camera is 120 degrees, which is between 160 ° -180 ° views, than the ordinary camera broader classification see
bis .CCD camera
divided by color imaging
(1) color camera:! suitable for detailed scene discrimination, such as identify the color of clothing or scenery. Due to the color information increases, the amount of information is generally considered to be 10 times that of black and white camera.
(2) monochrome camera: for low-light areas and regions of the lighting device can not be installed at night, when only monitoring the position or movement of the scene, the choice of black and white camera resolution is usually higher than the color cameras.
divided by the resolution of the camera
(1) image pixels about 250,000 pixels (Pixel), the color resolution of 330 lines, black and white low resolution of about 400 line type.
(2) image pixel between 250,000 – 380,000, the color resolution of 420 lines, black and white 500 line resolution in the mid-range type.
(3) more than 380,000 points in the image, color resolution equal to or greater than 480 lines, black and white resolution, high-resolution 600 lines or more.
divided by the sensitivity of the camera
(1) Normal: normal work required illuminance is 1 ~ 3 LUX (lux)
(2) moon type: Normal work for an illuminance of about 0.1 LUX
(3) Star type: normal work required illuminance 0.01 LUX or less
(4) infrared illumination type: in principle, be zero illumination, infraredLight sources for imaging.
according to the size of the image pickup element CCD plane is divided
(1) 1in the target surface having a width 12.7mmX high 9.6mm, diagonal 16mm
(2) 2 / 3in target surface having a width 8.8mmX high 6.6mm, diagonal 11mm
(3) 1 / 2in target surface having a width 6.4mmX high 4.8mm, diagonal 8mm
[123 ] (4) 1 / 3in target surface having a width 4.8mmX high 3.6mm, diagonal 6mm
(5) 1 / 4in target surface having a width 3.2mmX high 2.4mm, 4mm diagonal [ 123]
(6) 1 / 5in under development, is not yet available formal product
in addition the CCD camera have points of PAL and NTSC, the image may be divided according to the camera signal processing or press structure distinguish.
III. Lens (the LENS)
lens performance and appearance distinguishing
The lens performance and appearance distinction, there are P-type, E-type, L-type and auto-zoom lenses and other types of data from the instrument Chinese supermarkets are described as follows:
1. P type lens
industrial lens
(1) automatic positioning lens pupil coke itself has regulate, need to check the sharpness from the largest to the smallest magnification ratio, it is the same, is clear.
(2) Test concentricity, i.e., the maximum magnification to minimum magnification image taken in the same position, not offset or no offset too, are regarded as defective products, it is necessary to replace the lens.
(3) The optical magnification of 0.7-4.5X, i.e. a total of nine kinds of magnification between 0.7 times to 4.5 times.
(4) sharpness correction block according to the determination, the actual object imaged reflected.
2. E type lens
(1) This is a common industrial camera lens, pupil adjust focus manually, after the machine is installed, so that manual adjustmentWhen using the maximum and minimum magnification ratio, the same image is clear, if you can not adjust the sharpness regarded as defective products, adjust the lens if there are unstable factors such as the presence of rock, also regarded as defective products.
(2) Test concentricity, i.e., the maximum magnification to minimum magnification image taken in the same position, not offset or no offset too, are regarded as defective products, it is necessary to replace the lens.
magnifying lens
(3) The optical magnification of 0.7-4.5X.
(4) performs sharpness correction block according to the interpretation, to reflect the actual object imaged.
3. L lenses
(1) This is a common industrial camera lens, pupil adjust focus manually, after the machine is installed, the manual adjustment so that the maximum magnification and the minimum magnification, the same image is clear, if you can not adjust the sharpness regarded as defective products, adjust the lens if there are unstable factors such as the presence of rock, also regarded as defective products.
(2) Test concentricity, i.e., the maximum magnification to minimum magnification image taken in the same position, not offset or no offset too, are regarded as defective products, it is necessary to replace the lens.
(3) The optical magnification of 0.7-4.5X.
(4) performs sharpness correction block according to the interpretation, to reflect the actual object imaged.
4. The zoom lenses
(1) for the automatic positioning of the lens itself is already adjusted power pupil, need to check the sharpness from the maximum to minimum magnification ratio, are the same, is clear.
(2) Test concentricity, i.e., the maximum magnification to minimum magnification image taken in the same position, not offset or no offset too, are regarded as defective products, it is necessary to replace the lens.
(3) The optical magnification of 0.7-4.5X.
(4) performs sharpness correction block according to the interpretation, to reflect the actual object imaged.