BIDIRECTIONAL TDI LINE IMAGE SENSOR

Abstract

The present disclosure provides a bidirectional TDI line image sensor. The bidirectional TDI line image sensor according to one embodiment of the present invention comprises: a pixel unit, which has N line sensors having M CCDs arranged in a line and being arranged in a scan direction, moves, in the scan direction, charges accumulated in the respective columns of the line sensors, and accumulates the 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 bidirectional time delay integration (TDI) line image 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 in a scan direction and configured to move, in the scan direction, charges accumulated in respective columns of the line sensors and accumulate the charges; and an output circuit configured to receive the charges accumulated in first and last ones of the line sensors of the pixel unit parallelly in respective columns, selectively according to the scan direction, perform analog-to-digital (AD) conversion on the received charges, store the resulting signals, and then sequentially output the stored signals.

2. The bidirectional TDI line image sensor of claim 1, wherein the output circuit comprises: first amplifiers configured to receive the charges accumulated in the first line sensor of the pixel unit parallelly in respective columns at corresponding charge storage nodes and amplify the received charges; second amplifiers configured to receive the charges accumulated in the last line sensor of the pixel unit parallelly in respective columns at corresponding charge storage nodes and amplify the received charges; multiplexers configured to respectively select either ones of the first amplifiers and the second amplifiers according to the scan direction; AD converters configured to AD-convert output signals from the multiplexers, respectively; and a memory buffer configured to store output signals from the AD converters and sequentially output the stored signals.

3. The bidirectional TDI line image sensor of claim 2, wherein the amplifiers are source follower amplifiers.

4. The bidirectional TDI line image sensor of claim 2, wherein at least one of the multiplexers are arranged adjacent the first line sensor, while at least one of the other multiplexers are arranged adjacent the last line sensor.

5. The bidirectional TDI line image sensor of claim 2, wherein at least one of the AD converters are arranged adjacent the first line sensor, while at least one of the other AD converters are arranged adjacent the last line sensor.

6. The bidirectional TDI line image sensor of claim 2, wherein the multiplexers and the AD converters are arranged adjacent only one of the first line sensor and the last line sensor.

7. The bidirectional TDI line image sensor of claim 2, wherein respective pairs of the multiplexers and the AD converters are arranged adjacent the first line sensor and the last line sensor in an alternating manner.

8. The bidirectional TDI line image sensor of claim 1, wherein the output circuit is commonly connected to the line sensors regardless of the scan direction.

9. The bidirectional TDI line image sensor of claim 2, wherein a column of the line sensors is correspondingly connected to one of the first amplifiers, one of the second amplifiers, one of the multiplexers, and one of the AD converters.

10. The bidirectional TDI line image sensor of claim 2, wherein each of the multiplexers is configured to receive a selection signal, receive an input from either one of the first amplifiers and the second amplifiers according to the selection signal, and transmit the received input to each of the AD converters.

11. A bidirectional TDI line image sensor, comprising: line sensors, each of the line sensors including a plurality of CCDs arranged in a first direction, and the line sensors being arranged in a second direction perpendicular to the first direction and configured to move, in a scan direction, charges accumulated in respective column sections of the line sensors and accumulate the charges, the scan direction being either the same as or opposite to the second direction; an output circuit configured to receive the charges accumulated from the line sensors and comprising selectors configured to select which of first or last line sensor to receive the charges from.

12. The bidirectional TDI line image sensor of claim 11, wherein the selectors are multiplexers.

13. The bidirectional TDI line image sensor of claim 12, wherein the selectors are analog multiplexers.

14. The bidirectional TDI line image sensor of claim 11, wherein the output circuit further comprises: first amplifiers configured to receive the charges accumulated in the first line sensor parallelly in respective columns at corresponding charge storage nodes and amplify the received charges; and second amplifiers configured to receive the charges accumulated in the last line sensor parallelly in respective columns at corresponding charge storage nodes and amplify the received charges.

15. The bidirectional TDI line image sensor of claim 14, wherein the selectors are further configured to select either ones of the first amplifiers and the second amplifiers according to the scan direction.

16. The bidirectional TDI line image sensor of claim 11, wherein the output circuit further comprises: AD converters configured to AD-convert output signals from the multiplexers, respectively; and a memory buffer configured to store output signals from the AD converters and sequentially output the stored signals.

17. The bidirectional TDI line image sensor of claim 14, wherein the amplifiers are source follower amplifiers.

18. The bidirectional TDI line image sensor of claim 11, wherein at least one of the multiplexers are arranged adjacent the first line sensor, while at least one of the other multiplexers are arranged adjacent the last line sensor.

19. The bidirectional TDI line image sensor of claim 16, wherein at least one of the AD converters are arranged adjacent the first line sensor, while at least one of the other AD converters are arranged adjacent the last line sensor.

20. The bidirectional TDI line image sensor of claim 11, wherein the output circuit is commonly connected to the line sensors regardless of the scan direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a block diagram showing the configuration of a bidirectional time delay integration (TDI) line image sensor according to one exemplary embodiment of the present invention.

[0023] FIG. 2 is a layout diagram of analog-to-digital (AD) converters of the bidirectional TDI line image sensor, which are separately arranged, according to one exemplary embodiment of the present invention.

[0024] FIG. 3 is a circuit diagram of an amplifier and a MUX of the bidirectional TDI line image sensor according to one exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0025] Hereinafter, a bidirectional 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, the thickness of lines, the size of components, and the like illustrated in the drawings may be exaggerated for clarity and convenience of description.

[0026] Further, some terms which will be described below are defined in consideration of functions in the present invention, and their meanings may vary depending on, for example, the user or operator's intention or custom. Therefore, the meanings of these terms should be interpreted based on the scope throughout this specification.

[0027] FIG. 1 is a block diagram showing an exemplary configuration of a bidirectional time delay integration (TDI) line image sensor according to one embodiment of the present invention, and FIG. 2 is a layout diagram of analog-to-digital (AD) converters of the bidirectional TDI line image sensor according to one embodiment of the present invention.

[0028] 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.

[0029] The pixel unit 10 includes N line sensors 12_1 to 12_N, each having M charge-coupled devices (CCDs) 14 arranged in the form of a line or strip, wherein the N line sensors 12_1 to 12_N are arranged in parallel with the scan direction. The N line sensors 12_1 to 12_N move, in the scan direction, charges accumulated in respective columns of line sensors 12_1 to 12_N using a TDI method, and accumulate the charges. That is, the charges accumulated in each of the CCDs 14 are moved to its adjacent CCD 14 by sequentially controlling each CCD 14's voltages V1, V2, and V3, in the stated order or the reverse order depending on the scan direction, to be accumulated at a charge storage node FD and be output.

[0030] Since the pixel unit 10 may be a general configuration of a pixel unit of a bidirectional TDI line image sensor, a detailed description of the configuration is not made in the present embodiment.

[0031] The output unit 20 receives the charges accumulated in the pixel unit 10 from one line sensor 12 of the first line sensor 12_1 and the last line sensor 12_N, which is selected according to the scan direction, parallelly in respective columns, performs AD conversion on the received charges, stores the resulting signals, and then sequentially outputs the stored signals. To this end, the output unit 20 includes first amplifiers 21, second amplifiers 22, a MUX 24, AD converters 26, and a memory buffer 28.

[0032] The first amplifiers 21 receive the charges accumulated in the first line sensor 12_1 of the pixel unit 10 in parallel at corresponding charge storage nodes FD on a column-by-column basis and amplify the received charges, respectively. To this end, the first amplifiers 21 include M first amplifiers corresponding respectively to the CCDs 14 arranged in each line sensor 12.

[0033] The second amplifiers 22 receive the charges accumulated in the last line sensor 12_N of the pixel unit 10 in parallel at corresponding charge storage nodes FD on a column-by-column basis and amplify the received charges, respectively. To this end, the second amplifiers 22 include M second amplifiers corresponding respectively to the CCDs 14 arranged in each line sensor 12.

[0034] The MUX 24 selects either of the first amplifiers 21 and the second amplifiers 22 according to the scan direction UP/DOWN.

[0035] FIG. 3 is a circuit diagram of the amplifiers and MUX of the bidirectional TDI line image sensor according to one exemplary embodiment of the present invention.

[0036] The operations of the amplifiers and MUX will hereinafter be described with reference to FIG. 3. Either the first amplifiers 21 or the second amplifiers 22 are selected by select signals SELU and SELD corresponding to the scan direction UP/DOWN, and turned on according to potentials of the charge storage nodes FD at which the charges from the first line sensor 12_1 or last line sensor 12_N of the pixel unit 10 are moved and accumulated, so as to output predetermined voltages. To this end, the first amplifiers 21 and the second amplifiers 22 may be configured as source follower amplifiers.

[0037] The charges accumulated at the charge storage nodes FD are amplified by the first amplifiers 21 or the second amplifiers 22 and then output to the AD converters 26. Thereafter, the charge storage nodes FD are reset to a VDD voltage by the application of a reset signal RST to receive the charges from the next line sensor 12.

[0038] The AD converters 26 AD-convert output signals from the M first amplifiers 21 or M second amplifiers 22, respectively.

[0039] Here, the AD converters 26 include M AD converters, which may all be disposed at one side of the pixel unit 10 as shown in FIG. 1 or may be disposed separately in half at both sides of the pixel unit 10 as shown in FIG. 2.

[0040] The memory buffer 28 stores image signals, which are converted into digital signals at the M AD converters 26, and then sequentially outputs the image signals and allows a signal processing unit (not illustrated) to process the image signals for each line.

[0041] When the bidirectional 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.

[0042] As such, a high resolution image can be obtained with a conventional amount of light by configuring the pixel unit 10 including CCDs in accordance with a TDI method.

[0043] Further, since the charges stored in the charge storage nodes FD of the output unit 20 are amplified through the amplifiers 22, converted into digital signals in the AD converters 26, stored in the memory buffer 28, and then output without being moved through the CCDs, the degree of integration and also the transmission rate can be improved even with less power consumption due to the use of complementary metal-oxide-semiconductor (CMOS) devices.

[0044] In addition, while the scanning is bidirectionally performed, the charges from the first line sensor 12_1 and the charges from the last line sensor 12_N are output in common through one output unit 20, which can lead to the reduction in the device size.

[0045] As is apparent from the above description, in a bidirectional TDI line image sensor according to an embodiment of the present invention, a pixel unit includes CCDs configured in a TDI method, and an output unit receives charges of respective columns accumulated in CCDs of first and last line sensors of the pixel unit selectively according to a scan direction, performs AD conversion on the received charges, stores the resulting signals in a memory buffer, and then sequentially outputs the stored signals. Therefore, the resolution and transmission rate can be improved, while power consumption and noise can be reduced, owing to the characteristics of CCDs and CMOS devices. Further, the device size can be reduced owing to the common configuration of the output unit.

[0046] 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.

[0047] Therefore, the scope of the present invention should be defined by only the following claims.