TDI line image sensor including source follower amplifiers

1. A time delay integration (TDI) line image sensor, the sensor comprising: a pixel unit including N line sensors each having M charge-coupled devices (CCDs) arranged in a line, wherein the N line sensors are arranged horizontally in a scan direction, configured to horizontally move charges accumulated in respective columns of the line sensors and accumulate the charges, wherein N and M are integers greater than 1; and an output unit configured to receive the charges accumulated in the pixel unit from the respective columns in parallel as inputs, perform analog-to-digital (AD) conversion on the charges to output a digital signal, store the digital signal, and then sequentially output the digital signal, wherein the output unit comprises: M amplifiers configured to receive the charges accumulated in the pixel unit from the respective columns in parallel as inputs at charge storage nodes and respectively amplify the charges; M AD converters configured to respectively perform AD conversion on signals output from the amplifiers; and a memory buffer configured to store and sequentially output the digital signal of the AD converters; wherein the amplifiers are configured as source follower amplifiers that are turned on according to electric potentials of the charge storage nodes and output voltage values, the electric potentials being based on charges accumulated at the charge storage nodes.