TDI line image sensor including source follower amplifiers

Abstract

The present invention provides a TDI line image sensor. The TDI line image sensor according to the present invention is characterized by comprising: a pixel unit, which has N line sensors having M CCDs arranged in a line and being arranged horizontally to a scan direction, horizontally moves charges accumulated in the respective columns of the line sensors, and accumulates same; and an output unit for parallelly receiving as inputs the charges accumulated in the pixel unit from the respective columns, performing analog-to-digital conversion on and storing the charges, and then sequentially outputting same.

Claims

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.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a block diagram illustrating a time delay integration (TDI) line image sensor according to one embodiment of the present invention.

(2) FIG. 2 is a view illustrating a structure of a pixel unit of the TDI line image sensor according to one embodiment of the present invention.

(3) FIG. 3 is a view for describing movement of charges in the TDI line image sensor according to one embodiment of the present invention.

MODES OF THE INVENTION

(4) Hereinafter, a time delay integration (TDI) line image sensor according to one embodiment of the present invention will be described with reference to the accompanying drawings. In this process, thicknesses of lines, sizes of components, and the like illustrated in the drawings may be exaggerated for clarity and convenience of description.

(5) Further, some terms which will be described below are defined in consideration of functions in the present invention and meanings may vary depending on, for example, a user or operator's intentions or customs. Therefore, the meanings of these terms should be interpreted based on the scope throughout this specification.

(6) FIG. 1 is a block diagram illustrating the TDI line image sensor according to one embodiment of the present invention, FIG. 2 is a view illustrating a structure of a pixel unit of the TDI line image sensor according to one embodiment of the present invention, and FIG. 3 is a view for describing movement of charges in the TDI line image sensor according to one embodiment of the present invention.

(7) As illustrated in FIGS. 1 and 2, the TDI line image sensor according to one embodiment of the present invention includes a pixel unit 10 and an output unit 20.

(8) The pixel unit 10 includes N line sensors 12_1 to 12_N each having M charge-coupled devices (CCDs) 14 arranged in a line, wherein the N line sensors 12_1 to 12_N are horizontally arranged in a scan direction, horizontally move charges accumulated in respective columns of line sensors 12_1 to 12_N using a TDI method, and accumulate the charges.

(9) That is, as illustrated in FIG. 3, each of the charges accumulated in the CCDs 14 is moved to an adjacent CCD 14 by sequentially controlling voltages V1, V2, and V3 of each of the CCDs 14, overlaps a charge storage node FD, and is output.

(10) Since a configuration of the pixel unit 10 corresponds to a general configuration of a pixel unit of a TDI line image sensor, a detailed description of the configuration will be omitted in the present embodiment.

(11) The output unit 20 includes amplifiers 22, analog-to-digital (AD) converters 24, and a memory buffer 26 so as to receive charges accumulated in the pixel unit 10 from the respective columns in parallel as inputs, perform AD conversion on the charges to output a digital signal, store the digital signal, and then sequentially output the digital signal.

(12) In order to amplify each of the charges accumulated in the pixel unit 10 by receiving the charges from the respective columns in parallel to charge storage nodes ED as inputs, the amplifiers 22 include M amplifiers so as to correspond to the number of the CCDs 14 arranged in a single line sensor 12_1 to 12_N.

(13) In this case, the amplifiers 22 may be configured as source follower amplifiers in which charges are moved from a last line sensor 12_N of the pixel unit 10, the charges are turned on according to accumulated electric potentials of the charge storage nodes ED, and voltage values thereof are output.

(14) The AD converters 24 respectively perform AD conversion on signals output from the M amplifiers 22.

(15) The memory buffer 26 stores image signals converted into digital signals in the M AD converters 24, then sequentially outputs the image signals and allows a signal processing unit (not illustrated) to process the image signals for each line.

(16) When the TDI line image sensor configured in this way performs scanning and imaging, the charges accumulated in the CCDs 14 of each of the line sensors 12_1 to 12_N of the pixel unit 10 using a TDI method are synchronized with the scanning, are moved to an adjacent line sensor 12_1 to 12_N in respective columns thereof, and are output to the charge storage nodes FD of the output unit 20.

(17) After the charges accumulated in the charge storage nodes FD are amplified through the amplifiers 22, AD conversion is performed on the charges, and the charges are output as signals. Then, the charge storage nodes FD may be reset to have a voltage VDU connected to a reset drain RD through a reset gate RG, and may receive charges of a next line sensor 12_1 to 12_N as inputs.

(18) In this way, since the pixel unit 10 is configured in a TDI method through the CCDs, a high-resolution image having a sufficiently satisfactory amount of light may be obtained.

(19) Further, since the charges stored in the charge storage nodes FD of the output unit 20 are amplified through the amplifiers 22, are converted into digital signals in the AD converters 24, are stored in the memory buffer 26, and are then output without being moved through the CCDs, a degree of integration may be improved and a transmission rate may be improved even with less power consumption due to a complementary metal-oxide-semiconductor (CMOS) device.

(20) As described above, in the TIN line image sensor according to the embodiment of the present invention, since the pixel unit is configured to accumulate charges through the CCDs in a TDI method and the output unit is configured to perform AD conversion on the charges accumulated in the CCDs in each column, store the charges in the memory buffer, and then sequentially output the charges, resolution and a transmission rate may be improved and power consumption and noise may be reduced due to characteristics of a CCD and a CMOS device.

(21) While the present invention has been described with reference to the embodiment illustrated in the accompanying drawings, the embodiment should be considered in a descriptive sense only, and it should be understood by those skilled in the art that various alterations and equivalent other embodiments may be made.

(22) Therefore, the scope of the present invention should be defined by only the following claims.