Multichannel Optical Fiber Spectral And Imaging System For Measurement Of Displays

As the information industry developed rapidly,panel display products play an important part in daily life.People take full advantage of them,which makes them an important interface in man-machine interaction.As a tendency in the market,small pitch-size LED displays have advantages like low power consumption,high luminance,wide viewing-angle,long lifetime,and low failure rate.As a popular developing direction,OLED displays have advantages of a thin panel,wide color gamut,high resolution,high contrast,short response time,and flexibility.The application in commercial products is well-received.Though high stability sticks out as a prominent feature of LED display,light decay and chroma excursion may occur in LED displays,which leads to inhomogeneity of luminance and chroma after long-term usage due to manufacturing,heat dissipation,and aging.The junction temperature of chips can cause partial dead pixels that will affect the usage of the display because of the high integration of LED chips in displays.Meanwhile,the stability of luminance and chroma need to be taken into consideration.In consequence,evaluating the display quality objectively requires synthesizing photometric and colorimetric parameters and lifetime.Considering that existing instruments are not able to fulfill pixel-level measurement and that imaging photometer/colorimeter lacks overall analysis of spectrum information,a multichannel optical fiber spectral and imaging system for measurement of LED display is proposed in this dissertation,mainly containing following aspects:(1)Design and build the multichannel optical fiber spectral and imaging system for pixel-level measurement of LED display.A 4×4 array of optical fibers is contained in the system,along with a prime lens imaging the display and switching between reduction mode and magnification mode.Each optical fiber is preciously focused on a pixel of the display with the help of laser and camera.The spectrum of the pixel corresponding to the optical fiber is collected by the multiplexer and spectrometer.Luminance,color coordinates,and color gamut,etc.can be derived from the spectrum,which helps to make a full analysis of the quality of the display.(2)Build the multichannel optical fiber spectral and imaging system for measurement of the miniature display,in order to measure displays with micron-sized pixels more precisely,which increase applicability.(3)Develop a control software compatible with the proposed system.It is able to monitor the imaging plane with the camera,to control the rail with the motion controller,to choose one of the optical fibers with the multiplexer,to measure the spectrum with the spectrometer,and to measure the object distance with the distance meter.Besides,the calibration file can be imported so that the accuracy is assured.(4)Measuring the standard light source,the small pitch size LED display,and the OLED miniature display to testify the result of the system.Compared to the result of the German Instrument System TOP-100 probe,the maximum error of the average luminance of the standard light source is below 10%,and the average error of luminance of the LED display is 2.2%,which proves the accuracy and practicability of the system.The lifetime test of the LED display provides a new direction to the display measurement.Compared to the existing spectroradiometer and filter-based CCD/CMOS imaging photometer/colorimeter,the proposed system is able to take pixel-level measurement of LED displays.The result contains detailed spectrum information,which provides an elaborate evaluation of displays.The proposed system can be extended into measurement system for miniature display in order to perform pixellevel measurement on future displays like micro-LED displays.