DE19739249A1 - CCD with time delayed and integrating function - Google Patents

Abstract

The CCD includes a charge transmission unit, a reset unit, a horizontal shift register, and at least one cell column with several cell units connected in series, which define a shift register to horizontal, as a charge flow aligned downstream. Each cell unit has a photocell, which produces charge, if it is illuminated and at least one buffer cell for the storing of charges. The photo cell and the buffer cell are connected in series. The charge transmission unit, which is connected with each of the photo cells and the buffer cells. The component controls by transmitting charges downstream between the individual cells and by the transmission of charges from the first cell column to the horizontal shift register. The reset unit of each of the photo cells, would be reset, after the charges accumulated in each of the photocells were transmitted from these.

Description

The present invention relates to charge coupled devices Blocks with time delay and integration function.

Charge-coupled devices (CCD) with time delay and integration function (TDI) are known. A TDI-CCD sensor consists of several rows or rows of photo cells, also known as pixels, or stages. Light reflected from an object or generated by an object strikes the photocells and generates charges in the photocells. Reference is now made to FIG. 1A, which shows a schematic diagram of a TDI-CCD sensor, generally designated by reference numeral 100 . The sensor 100 has a plurality of photocells, generally designated by the reference symbol 102 , which are arranged in a two-dimensional field which has a plurality of rows or rows 104 and a plurality of columns 106 . Sensor 100 also includes a horizontal shift register 112 located at the bottom of each of the columns and connected to the bottom of each of the columns.

The main principle according to which the sensor 100 operates is to accumulate and move charges in synchronism with the movement of an object 110 . When the photocell 102 f is exposed to light from an object 110 , charges are generated in the photocell 102 f and stored therein. When the object moves to the photo cell 102 e, the charges accumulated in the photo cell 102 f are transferred to the photo cell 102 e, and at the same time who transfers the charges from the photo cell 102 e to the photo cell 102 d. The photocell 102 e is then exposed to light from the object 110 , as a result of which additional charges are generated and accumulated in the photocell 102 e. When the object moves to the photo cell 102 d, the charges accumulated in the photo cell 102 e are transferred to the photo cell 102 d, etc. up to the photo cells 102 c and 102 b. Finally, the b in the photocell 102 accumulated charges, the L exposures of photocells 110 correspond ject through the Ob, where L represents the number of rows in the sen sor 100, a of a horizontal shift register transferred to a cell 112, and then shifted to the output.

The same occurs in each of the columns. The photocells 102 of each row or row 104 simultaneously transfer the accumulated charges to the photocells of the next row or row as a result of the movement of the object 110 . The charges accumulated by one line are added to the newly created charges on the next line as the object moves from one line to the next. As a result, a line of an image of the object is formed in the lowest part of the field, which has been accumulated by all lines of the field. For this reason, a TDI sensor generally has a sensitivity that is greater by a factor corresponding to its number of levels than with a linear sensor (single-line sensor). Due to its increased sensitivity, a TDI image sensor has many applications in which the sensitivity of a single-line sensor is not sufficient, such as when checking fast-moving and / or dark web material, in reconnaissance and similar applications.

Reference is now made to FIG. 1B, which shows general timing diagrams of a conventional TDI sensor 100 . Line 140 shows an object movement synchronization signal which always assumes a high level when the object 110 moves to the next photocell line. Line 142 shows a signal that is high during vertical charge transitions or shifts and low during the time the photocells are exposed. Line 144 shows a signal that is high during horizontal shifts of a horizontal shift register 112 .

Vertical charge transitions from the photocell 102 f ( FIG. 1A) of one line to the photocell 102 e of the next line must now be carried out in synchronism with the relative movement between the sensor 100 and the object 110 . If the distance between photocells in the direction of movement (distance between the lines) is ΔY, the charge transfer from line to line or the line-by-line charge transfer must take place whenever the object has moved a distance ΔY on the sensor level. A specific point on the object, through which the photocell 102 f is exposed at a predetermined time, is considered below as an example. After the point has traveled the distance ΔY on the image plane, the charges accumulated by the point through the photocell 102 f of the line 104 f are transferred to the photocell 102 e of the next line 104 e, and this photocell of the line 104 e becomes now illuminated by the point (the point is seen through this photocell). The charges transferred from line 104 f are added to the new light-generated charges of line 104 e, which are assigned to the same point of object 110 . This mode of operation of the line-by-line charge transfer synchronized with the relative movement of the object on the image plane continues until the charges assigned to this point reach the horizontal shift register (HSR) 112 at the lower end of the field. In the horizontal shift register HSR, the charges of the line are quickly shifted to output 130 . If the TDI sensor has L stages, a signal is output at the output of the TDI sensor, which represents elements of an object, which have been seen by elements of the sensor and have been accumulated L times. Therefore, a TDI sensor can theoretically be L times as sensitive as a conventional linear CCD sensor. The synchronization of the vertical line-by-line charge transfer with respect to the object movement can be achieved, depending on the application, by using a rotary encoder or encoder or by another device.

Unlike a linear CCD sensor, a conventional one cher TDI sensor due to the fact that charges continuously can be accumulated, no electronic exposure control on. Therefore, photocells cannot be returned set state.

T _EXP denotes the time in which a given photocell is exposed and therefore charges are accumulated. In a conventional TDI-CCD sensor, T _EXP corresponds to the time for a charge transfer between two successive lines. That is, T _EXP is the time it takes an object to cover a distance on the image plane that is equal to the distance between two successive lines of sensor 100 .

The main feature of the conventional TDI mechanism is based on the synchronization with the distance and the movement or the displacement. If the relative speed of the object is not constant, the time it takes for an object to cover a given distance is not constant, but depends on the speed. Therefore, the integration time T _{EXP of} the photocells of the conventional TDI sensor changes when the speed of the object changes. As a result, the charge generated in the photocells changes with a change in speed and not just as a factor of the brightness of the object.

For applications where the review is more agile Sheet materials is provided is a De to be recorded sometimes change the color of the sheet material as. A change in the output signals due to a Ge change in the speed of the web material can sometimes do that have the same appearance in an actual De perfect. This also applies to linear single-line sensors.

A conventional method for solving this problem the Si caused by a change in speed Signal change when using linear sensors consists of to use an electronic exposure time. By To apply a constant exposure time that is shorter than the minimum time for charge transfer between on consecutive lines (those at the maximum speed object), the integration time is the Photocells regardless of the object speed stant.

Another method of solving the above Problem, the output signal is corrected by the Ge speed of the relative movement of the object is measured and the gain level is changed accordingly. At a still other methods are mechanical or LCD Ver conclusions used. The above procedures are nor sometimes due to the complexity of their implementation, of the large dynamic range required when the speed range is large, the required  Compensation or correction accuracy, etc., problema table.

Conventional TDI sensors do not have electronic ones Exposure control on. This makes it difficult and sometimes impossible to use the TDI sensor if the Object speed changes with respect to the sensor. A Disadvantage of conventional TDI sensors is that the Over-brightening or blooming effects cannot be eliminated Can that occur when those accumulated in the photocell Charges exceed a predetermined level.

An exposure control can be used in a TDI sensor Interline transfer (IL) architecture Architecture). The interline transition architecture has a partial degree of filling, which is essential represents disadvantage. This technique is described in "Novel In terline Transfer CCD Array for Near-Infrared Applications ", Stacy R. Kamaz et al., SPIE, vol. 2415, pages 106-116, be wrote.

It is an object of the present invention to provide a to provide novel TDI-CCD sensor through which the Disadvantages of conventional sensors can be eliminated.

It is another object of the present invention be a novel TDI-CCD sensor with exposure control to sit down with a fill level of almost 100% of the formed object. By the present Exposure control provided by the invention can be the sensor be used for applications in which the Relativge speed of the depicted object is not constant, as well as other TDI and line scan applications where an electronic lock is required.

According to the invention is a charge-coupled device with time delay and integration function provides, the module a charge transfer unit, a reset unit, a horizontal shift register and has at least one cell column. The cell fissure  has several cell units connected in series, through the one (down) to the horizontal shift register a directed charge flow is defined. Each of the cells units has a photocell that generates charges, when exposed, and at least one buffer cell to Storage of charges, whereby the photocell and the min at least one buffer cell is connected in series.

The charge transfer unit is with each of the photos cells and the buffer cells connected and controls the construction stone directed downwards by transferring charges between cells and by transferring charges of the cell columns to the horizontal shift register. By the reset unit, the photocells are reset, after the charges of these were transferred.

According to another embodiment of the invention the vertical length of the cell units of the double verti same length as the photocells.

According to yet another embodiment of the invention is the vertical length of the cell units of the vertical The length of the photocells is essentially the same.

A preferred embodiment of an inventive Building block has cell units with two buffer cells.

Each of the cell columns can also have one with the hori zonal shift register additional series connected Have photocell.

The preferred embodiment of an invention Building blocks have cell units with a single buffer cell on.

A cell intended for a TDI-CCD chip unit has a photocell that generates and accumulates charges if exposed and at least one buffer cell to store charges on, the photocell and the at least one buffer cell connected in series are.  

According to another embodiment of the invention a charge coupled device with time delay and Integration function provided, the block ei ne charge transfer unit, a reset unit, a ho horizontal shift register and at least one cell column with several cell units connected in series, some down to the horizontal shift register Define reported charge flow.

Each of the cell units has a photocell, the La generated when it is exposed, and one under the Photocell arranged and connected to the photocell Buffer cell for storing charges.

The charge transfer unit is with each of the photos cells and the buffer cells connected and controls the construction stone by transferring charges in a selected one Cell unit from a photocell of the selected cells unit to a buffer cell of the selected cell unit. The charge transfer unit also controls the module by transferring charges between the buffer cells below towards the horizontal shift register. The Reset unit resets the photocells after the in charges accumulated by the photocells are transferred from them were.

The reset unit can each of the cell columns individually reset to default. Alternatively, the reset unit sets individual ones Rows of cell units back.

According to another embodiment of the invention a cell unit for installation in a TDI-CCD module provided with: a photocell that generates charges and accumulates when exposed, and at least one ner buffer cell for storing charges. The buffer cell is located under the photocell.

According to yet another embodiment of the invention, a method for operating a TDI-CCD module is provided, wherein the TDI-CCD module has a plurality of cell gaps, each cell column has a number of cell units, each cell unit has a photo cell and one arranged under the photo cell and connected buffer cell and each of the buffer cells of the cell units is connected in series to define a downward structure and ending in a shift register, the method comprising the step of repeating the following steps:
Activating the exposure of the photocells;
Detecting light from an object through the photo cells to generate charges through the photo cells;
Transferring the charges in each cell unit from the photocells to the buffer cells;
Deactivating the exposure of the photocells; and
Transfer of charges between the buffer cells facing down to the shift register.

According to another embodiment of the invention, a method for operating a TDI-CCD module is provided, the TDI-CCD module having a plurality of cell columns, each of the cell columns having a plurality of photocells connected in series, each of the cell units having a photocell and one thus has a series-connected buffer cell and the last cell unit of each cell column is connected to a shift register. The method has the step of repeating the following steps:
Enabling detection of light from an object to generate charges through the photocell;
Transferring the charges in each cell unit from the photocells to the buffer cells;
Transferring the charges from the buffer cell of the last cell unit to the shift register;
Disable the detection of light by the photo cells; and
Transferring charges between the buffer cells downward to the shift register from a buffer cell of a selected cell unit to a photocell of a subsequent cell unit.

According to another embodiment of the invention, a method for operating a TDI-CCD module is provided, wherein the TDI-CCD module has a plurality of cell columns, each of the cell columns has a number of cell units and a last cell unit, and each of the cell units has a photo cell and one with it has buffers connected in series bright and each of the last cell units has a photocell and is connected to a shift register. The method has the step of repeating the following steps:
Enabling detection of light from an object to generate charges through the photocells;
Transferring the charges in each cell unit from the photocells to the buffer cells;
Transferring the charges from each last photocell to the shift register;
Disable the detection of light by the photo cells; and
Transfer of charges between the cell units directed downwards to the shift register from a buffer cell of a selected cell unit to a photo cell of a subsequent cell unit.

According to a further embodiment of the invention, a method for operating a TDI-CCD module is provided, the TDI-CCD module having several cell columns, each of the cell columns having a plurality of cell units connected in series, each of the cell units having a photocell, one with of the photocell connected in series with the first buffer cell and a second buffer cell connected in series with the first buffer cell and the last cell unit of each cell column is connected to a shift register. The method has the step of repeating the following steps:
Enabling detection of light from an object to generate charges through the photocells;
Transferring the charges in each cell unit from the photocells to the first buffer cells;
Disable the detection of light by the photo cells;
Transferring charges between the cell units downward to the shift register from a second buffer cell of a selected cell unit to a photocell of a subsequent cell unit;
Transferring charges in each cell unit from the first buffer cells to the second buffer cells; and
Transfer of charges from the second buffer cell of the last cell unit to the shift register.

Any of the above methods can also Steps to transfer loads from the shift register ster, to reset the photocells, to activate one Exposure by disabling the reset state of the photo cells and to deactivate the exposure by activating the reset state of the photocells.

The present invention is accomplished by the following Description in more detail in conjunction with the drawings explained; show it:

Figure 1A is a schematic diagram of a conventional TDI-CCD sensor.

Fig. 1B is a schematic representation of impulse diagrams of the conventional TDI sensor shown in Fig. 1A;

Fig. 2A is a schematic representation of a preferred embodiment of a TDI-CCD sensor of the invention which is operable in accordance with a preferred embodiment of a erfindungsge MAESSEN method;

Fig. 2B is a schematic representation of the electrical functions of the TDI-CCD sensor of Fig. 2A and its reset mechanism;

Fig. 3 is a schematic representation of pulse diagrams of the TDI-CCD sensor of Figures 2A and 2B, which is operable according to a preferred embodiment of a method according to the invention.

4A is a schematic illustration of another embodiment of the invention be vorzugten TDI-CCD sensor, which is operable in accordance with another preferred embodiment of a method according to the invention.

FIG. 4B is a schematic representation of the electrical functions of the TDI-CCD sensor of FIG. 1A;

4C is a schematic representation of another preferred embodiment of a TDI-CCD sensor, which is operable in accordance with a further preferred embodiment of a method according to Invention.

Figure 5 is a schematic representation of pulse diagrams of the device of Figures 4A and 4B;

Fig. 6 is a schematic representation of yet another preferred embodiment of a method according to the invention is operable according to the invention of a TDI-CCD sensor, the approximate shape according to yet another preferred exporting;

Figure 7 is a schematic representation of another embodiment vorzugten be standardized a Zellenein invention which is operable according to another preferred embodiment of a method according to the invention.

Figure 8 is a three-dimensional schematic illustration of yet another preferred embodiment of to the invention OF INVENTION TDI sensor and a shift register.

FIG. 9 shows a schematic flow diagram of another embodiment of a method according to the invention for operating the TDI sensor from FIG. 2A;

FIG. 10 shows a schematic flow diagram of a further embodiment of a method according to the invention for operating the TDI-CCD sensor from FIG. 4A;

Fig. 11 is a schematic representation of impulse diagrams to illustrate the operation of the TDI-CCD sensor of Fig. 8 according to another preferred embodiment of a method according to the invention, and

FIG. 12 shows a schematic flowchart of a preferred embodiment of a method according to the invention for operating the module from FIG. 8.

Reference is now made to Figures 2A and 2B.

Fig. 2A shows a schematic representation of a, generally designated by the reference numeral 200 exporting preferred approximate shape of a TDI-CCD sensor according to the invention, in accordance with a preferred. Embodiment of a method according to the invention can be operated. Fig. 2B shows a schematic representation of the electrical functions of the TDI-CCD sensor 200 and its reset mechanism. Sensor 200 , also referred to as a single buffer sensor, has a plurality of photo cell rows, generally designated by reference number 210 , a plurality of buffer cell rows, generally designated by reference number 212 (individually designated by suffixes A, B, etc.) and a horizontal shift register 232 . Each of the photocell rows 210 has a plurality of photocells generally designated by the reference numeral 202 (individually denoted by Suf fixe A, B, etc.) and associated electrodes 203 for vertical charge transfer. Each of the buffer cell rows 212 has a plurality of buffer cells, generally designated by reference numeral 204 , and associated electrodes 205 for vertical charge transfer (individually denoted by suffixes A, B, etc.), each buffer cell 204 being covered in such a way that they are not influenced by light can. The electrodes 203 and 205 are only shown in FIG. 2B.

The photocells 202 generate charges when exposed. The charges in each photocell 202 are then transferred to an adjacent, downstream buffer cell 204 . According to the example shown, the charge transfer is carried out by supplying potentials at a suitable point in time to the CCD electrodes of a predetermined photocell 202 and an adjacent, downstream buffer cell 204 .

Each photocell 202 has an associated reset mechanism 214 , which may be formed in a horizontal structure, a vertical structure, or a similar structure. Basically, the reset mechanism consists of a gate electrode 216 for controlling the charge transfer ( FIG. 2B) and a reset drain electrode 218 for deriving the charges from the photocells to the reset potential V _r . According to the example shown, the drain electrodes for controlling the charge transfer of all photocells are controlled jointly by the T _LR clock signal 220 . The reset structure can also be used to prevent brightening or blooming effects and for memory selection.

The reset structure can also be used to prevent over-lighting or blooming effects by providing an anti-blooming potential to the reset drain electrode 218 so that when a photocell has an excessive charge, the gate electrode 216 to control the Charge transfer is turned on and excessive charges are discharged.

According to the example shown, the buffer cell 204 is used as a buffer for the charges generated by the photocell 202 , as a result of which the photocell 202 can be reset and the charge can be shifted to the next photocell at a suitable time. According to the example presented, the vertical length ΔY₂ of a buffer cell is smaller than the vertical length ΔY₁ of a photocell in order to minimize possible inadequate scanning (incomplete detection) of the object in the Y direction, which can occur if short exposure times are used who is there and a slow speed.

Reference is made below to FIG. 3, which shows a schematic pulse diagram of a TDI-CCD sensor 200 which can be operated according to a preferred embodiment of a method according to the invention.

Line 252 shows the synchronization signal relating to the relative movement between the sensor 200 and the detected object. Line 254 shows the exposure reset sequence of the photocells, where T _{EXP represents} an exposure time. Line 256 shows a sequence, generally denoted by T _{C → B} , according to which charges are transferred from one photocell to an adjacent, downstream buffer cell. Line 258 shows a sequence, generally denoted by T _{B → C} , according to which charges are transferred from the buffer cell to an adjacent, downstream photocell. Line 260 shows a sequence generally denoted by T _{LB → HSR} , according to which charges are transferred from the last buffer cell 212 E to the horizontal shift register. Line 262 shows the clock at which charges are transferred from horizontal shift register 232 to output 234 .

The synchronization signal 252 is determined according to the Relativbe movement between the sensor 200 and the detected object be.

The signal T _LR represented by line 254 is the signal used to reset the photocells 202 , a high level representing a reset command and a low level representing an exposure command to accumulate charges. After T _{LR has reached} a low level, charges are transferred from one buffer cell to an adjacent, downstream photocell. This charge transfer is carried out in a time period T _{B → C} represented by reference numeral 258 . After the exposure period T _EXP , charges are transferred from a given photocell to the adjacent, downstream buffer cell, as represented by the signal T _{C → B} represented by reference numeral 256 .

The time between the falling edge of the signal T _LR and the beginning (the rising edge) of the signal T _{C → B} is the actual exposure time T _EXP . After the charge transfer from a photocell 202 to a buffer cell 204 is completed, as represented by the falling edge of the signal T _{C → B} , the signal T _LR assumes a high level and the potential 202 is reset. Resetting the photocell is easy by dissipating the charges in photocell 202 to a V _r reset potential 222 . The photocell 202 is held in the reset state until the object has traveled the distance ΔY = ΔY₁ + ΔY₂ on the image plane, which represents the vertical distance between two adjacent photocells.

After the next rising edge of the object movement synchronization signal 252 , at which the signal T _LR assumes a low level, ie the reset function is deactivated, charges are transferred from a buffer cell 204 to an adjacent, downstream photocell 202. At the same time, because light from detected object, the same photocell is used to generate and accumulate more charges.

Therefore, all photocells 202 in a column of sensor 200 are exposed by the object as it moves vertically from the top to the bottom of the sensor.

The accumulated charges are transferred from one photocell to an adjacent buffer cell and on to the next photocell as the object moves from one photocell to the next photocell on the image plane of sensor 200 , the charges of one photocell to the charges of the next photocell be added. Therefore, the charges from the last buffer cell at the lower end of array 230 , which has N photocells arriving at horizontal shift register 232 , represent N times exposures of photocell 202 through the object. The total exposure is multiplied by N times the exposure time with the size ΔY₁ × ΔX of a photocell ( Fig. 2A), where ΔX is the width of a photocell.

The charge transfer from the last buffer line of the field to the horizontal shift register 232 can be controlled separately, and is carried out during the time T _{LB → HSR} . This transfer can be carried out simultaneously with the other charge transfer from the buffer cells to the photocells controlled according to the signal T _{B → C} , or it can be carried out immediately after the charge transfer from the photocells to the buffer cells controlled according to the signal T _{C → B} . The horizontal shift of the charges in the horizontal shift register (HSR) 232 to the output 234 can be carried out after the charge transfer controlled according to the signal T _{LB → HSR} .

A reset mechanism can also be used net to reset the buffer cells.

The sensor 200 eliminates the disadvantage of the conventional sensor by controlling the exposure time of the photo cells, thereby eliminating the influence of a variable relative speed of the detected object.

By the present invention, a degree of filling of almost 100% achieved.

Reference is now made to Figures 4A and 4B.

Fig. 4A shows a schematic representation of another preferred embodiment of the present invention, my designated by the reference numeral 400 TDI-CCD sensor according to another preferred embodiment of a method according to the invention is operable general. FIG. 4B shows a schematic representation of the electrical radio functions of the TDI-CCD sensor 400 and its Rücksetzmechanis mus. The designated as a double buffer Sensor Sensor 400 has a plurality, generally designated by the reference numeral 420 cell columns (individually by suffixes A, B etc Marked net) and a horizontal shift register 432 . Each column 420 has a plurality of cell units 430 (individually identified by suffixes A, B, etc.), each cell unit having a photocell 402 , a first buffer cell 404 and a wide buffer cell. 406 . In addition to electrodes 403 for vertical charge transfer (individually identified by suffixes A, B, etc.), sensor 400 has associated with photocells 402 and buffer cells 404 and 406 (individually identified by suffixes A, B, etc.) ), and a reset mechanism 408 for resetting the photocell 402 . According to the invention, the first and the second buffer cells 404 and 406 each have a charge shift mechanism in a cell unit 430 , by means of which an independent timing of the charge transfer is made possible.

According to the invention, the vertical length ΔY of a photo cell 402 is the same as the combined vertical length of a first buffer cell 404 and a second buffer cell 406 . That is, the vertical length of a cell unit 430 is twice the vertical height ΔY of the photocell 402 . The timing of the charge transfer between the different cells is periodic and synchronized with the relative movement between the sensor 400 and the detected object.

The structure of the reset mechanism is not limited to ver tical structures limited. According to other embodiments The structure of the reset mechanism can be of the invention horizontal, combined vertical and horizontal or similar be trained.  

Hereinafter also referred to Fig. 4C, the approximate shape is a schematic representation of a generally designated by reference numeral 450 further preferred exporting a TDI-CCD sensor of the invention and its return mechanism shows that according to a further before ferred embodiment of an inventive method are operable.

The TDI-CCD sensor 450 is a double buffer CCD sensor essentially similar to the TDI-CCD sensor 400 ( FIG. 4A) with a differently constructed reset mechanism. The photo cell row 252 A is followed by a first row 454 A of buffer cells and a second row 456 A of buffer cells. The 452 B series of photocells is followed by a first row 454 B of buffer cells and a second row 456 B of buffer cells.

The reset electrode structure is horizontal and each electrode controls a row of cells. In the present example, a reset electrode 460 A resets the photo cell row 452 A and a reset electrode 460 B resets the photo cell row 452 B. Such a reset structure enables a step-by-step selection for controlling the exposure time. In the illustrated example, each of the series when 460 B of the reset state of the photocells is series through the electrode 452 to get right, he 452 B upstream Rei, z. B. the photocell series 452 A, substantially deactivated four. In this case, the charges transferred from the 452 A series of photocells via the 454 A and 456 A series of buffer cells are discharged when they arrive at the 452 B series of photocells.

Reference is also made below to FIG. 5, which shows a schematic pulse diagram of the module 400 , which can be operated according to a further preferred embodiment of a method according to the invention.

Line 502 represents the synchronization signal with respect to Figure 5 of the relative movement between the sensor 400 and the detected object. Line 504 shows the exposure reset sequence of the photocells, where T _{EXP represents} an exposure time. Line 506 shows a sequence or clock sequence, generally designated by T _{C → B1} or 526 , according to which charges are transferred from a photocell to a first buffer cell of the same cell unit. Line 508 shows a sequence generally denoted by T _{B1 → B2} or 528 , according to which charges are transferred from a first buffer cell to a second buffer cell of the same cell unit. Line 510 shows a sequence, generally denoted by T _{B2 → C} or 530 , according to which charges are transferred from the second buffer cell of a cell unit to a photo cell of an adjacent, downstream cell unit. Line 512 shows a general sequence designated by T _{LB1 → LB2} or 532 , according to which charges are transferred from a first buffer cell to a second buffer cell in the last cell unit 430 A. Line 514 shows a sequence generally denoted by T _{LB2 → HSR} or 534 , according to which charges are transferred from a second buffer cell in the last cell unit 430 A to a horizontal shift register 432 . Line 516 shows a clock, generally designated 536 , according to which charges are transferred from horizontal shift register 432 to output 434 .

The object motion synchronization signal 502 assumes a high level after the object has traveled the distance ΔY on the image plane. This determines the beginning of a line period. The signal T _LR then assumes a low level and the photocells begin to accumulate charges generated by light. After the signal T _{LR has reached} a low level, the charges stored in the buffer cell 406, for example, are transferred to the next vertically adjacent photocell 402 B during the period T _{B2 → C.} Simultaneously or later, the charges stored in the first buffer cell 404 A are transferred to the second buffer cell 406 A of the same cell unit 430 during the time period T _{B1 → B2} .

The charges transferred from the second buffer cells 406 A to the photo cells 402 B are added to the charges generated by light in the photo cells 402 B. After the required exposure time T _EXP , the charges accumulated in a given photocell 402 B are transferred to the next vertically adjacent, downstream first buffer cell 404 B during the time period T _{C → B1} . The first buffer cell 404 B stores the charges while the photocell 402 B is kept in a reset state, which is represented by the high level of the signal T _LR .

The exposure time of the photocells is the time between the falling edge of the signal T _LR and the rising edge of the signal T _{C → B1} . The photocells are kept in a reset state by the signal T _LR until the beginning of the next line period, after the object has moved on the image (sensor) plane over the distance ΔY. Then the reset state is deactivated again, the charges stored or held in the second buffer cell 406 B are transferred to the next adjacent, downstream photocell 402 C of the next cell unit in the column 420 B, and the photocell accumulates new charges and generated by light and adds this to the charges transferred from the adjacent second buffer cell.

The object-forming, light-generated charges previously detected by the preceding photocell in a given column will last for the time the object is moving from a given photocell to the next downstream photocell in a given column 420 moved on the image plane, via which he transferred the first buffer cell 404 and the second buffer cell 406 to the next photocell 402 . For example, in the photo cell 402 C, the new charges generated by light are added to the charges accumulated by the preceding photo cell 402 B.

This process continues until the charges representing the detected object reach the first buffer cell 404 X of the last cell unit 430 A. The charges are transferred from the first buffer cell 404 X to the second buffer cell 406 X according to the signal T _{LB1 → LB2} . The charges are transferred according to the signal T _{LB2 → HSR} from the second buffer cell 406 X to the horizontal shift register (HSR) 432 . According to an embodiment of the present invention, the signal sequences T _{LB1 → LB2} and T _{LB2 → HSR can be} synchronous, as represented by reference numerals 532 A and 534 A ( FIG. 5).

According to another embodiment of the invention, the clock signals T _{LB1 → LB2} and T _{LB2 → HSR can occur} earlier, after the clock signal T _{C → B1} , as represented by reference numerals 532 B and 534 B. The transfer of charges in all columns 420 of the last cell unit 430 a to the horizontal shift register (HSR) 432 and further to the output 434 takes place after the vertical charge transfer from the second buffer cell 404 X in each column to the horizontal shift register 432 . Therefore, if the sensor has 400 N photocells in a column 420 , the output signal represents an object exposed by photocells ΔY × ΔX N times with the applied exposure time.

The advantage of the double buffer architecture compared to the single buffer architecture is that the double buffer architecture does not result in insufficient scanning or detection of an object. The sensor 400 covers all detected objects in the direction of movement in the full detection range or in the full detected angle of view.

Reference is made below to FIG. 6, which shows a schematic representation of yet another preferred embodiment of a TDI-CCD sensor according to the invention, generally designated by reference numeral 600 , which can be operated according to yet another preferred embodiment of a method according to the invention. The sensor 600 has a horizontal shift register 632 and a plurality of cell columns, generally designated by the reference symbol 630 , which have a plurality of cell units 620 and at least one last photo cell 610 L. Each of the cell units has a photocell, generally indicated by reference number 610 (individually identified by suffixes A, B, etc.) and at least one last buffer cell, indicated generally by reference number 612 (individually indicated by suffixes A, B, etc.). In the example shown, the cell units 620 have a single buffer cell.

In accordance with the present embodiment, the charges generated and accumulated in the last photocell 610 L are transferred directly to the horizontal shift register 632 , thereby eliminating any delays caused by further transfer of charges to intermediate buffers or wasted CCD area.

Reference is made below to FIG. 7, which shows a schematic illustration of another preferred embodiment of a cell unit according to the invention, generally designated by the reference numeral 750 , which can be operated according to another preferred embodiment of a method according to the invention.

The cell unit 750 has a photocell 752 and a buffer cell 754 arranged under the photocell 752 . The unit cell 750 also includes electrodes gene or Übertra shifting of charges from the photo cell 752 to the buffer cell 754, electrodes for transferring or shifting of charges from the buffer cell 754 to the next benachbar th buffer cell 754 and a reset mechanism.

The photocell 752 detects light and thereby generates charges. At the end of the charge generation process, the charges are transferred down to the buffer cells 754 . The charges are then transferred from the buffer cells 754 to the next neighboring buffer cell 754 , which is arranged under the next neighboring photocell 752 .

An advantage of the present embodiment is that by placing the buffer cell 754 under the photocell 752, the exposure area of the cell unit 750 is maximized and the silicon area is minimized.

Another advantage of the illustrated embodiment is that when the charges go from the photocell to the buffer cell were transferred, this no longer to another Photocell must be transferred as below is written, reducing the timing of the cargo transmission is simplified.

Reference is now made to FIG. 8, which shows a three-dimensional schematic representation of yet another embodiment of a TDI sensor according to the invention, generally designated by reference numeral 700 , and a shift register, generally designated by reference numeral 730 .

The TDI sensor 700 has a plurality of cell units 702 , 708 , 714 , 718 and 726 which are substantially similar to the cell unit 750 of FIG. 7.

The cell unit 702 has a photocell 704 and a buffer cell 706 . The cell unit 708 has a photocell 710 and a buffer cell 712 . The cell unit 714 has a photocell 715 and a buffer cell 716 . The cell unit 718 has a photocell 720 and a buffer cell 722 . The shift register 730 has four cells: 732, 734, 736 and 738 .

The photocells 704 , 710 , 715 and 720 capture light during an exposure period and generate charges accordingly. When the exposure time has expired, who will transfer the charges down to the associated buffer cell. Therefore, the charges accumulated in each of the photocells 704 , 710 , 715 and 720 are transferred down to the buffer cells 706 , 712 , 716 and 722 , respectively, and the photocells are kept in the reset state until the next exposure period begins.

The loads are then shifted down one level. That is, the charges of the buffer cell are transferred 722 to the cell 732 of the shift register 730, the charges of the buffer cell are transferred 716 to the buffer cell 722, the charges of the buffer cell are transferred 712 to the buffer cell 716 and the charges of the buffer cell are transferred 706 to the buffer cell 712th The charge transfers or shifts between the buffer cells are carried out in the manner described.

When charges are transferred between the buffer cells that, the photocells can be exposed and thereby generate more charges. If the charge transfer between the buffer cells has been completed, they can now be Transfer photocells generated charges to the buffer cells gen and there along with that from previous cells carried charges are accumulated.

The detection of an object moving along the cell units 702 , 708 , 714 and 718 is described below. First, the object faces the cell unit 702 , and the photocell 704 generates charges when it detects light from the object. When the object has moved to the cell unit 708 , the charges generated in the photocell 704 are transferred to the buffer cell 706 and further to the buffer cell 712 . The object now faces cell unit 708 and photocell 710 generates charges when it detects light from the object. When the object has moved to cell unit 714 , the charges generated by photocell 710 are transferred to buffer cell 712 , which adds these charges to the charges received by buffer cell 706 . The charges accumulated in the buffer cell 712 are then transferred to the buffer cell 716 .

When the object faces the cell unit 714 , the photocell 715 generates charges when it detects light from the object. When the object has moved to the cell unit 718, the charges generated by the photocell 715 are transferred to the buffer cell 716 , which adds them to the charges received by the buffer cell 712 . The charges accumulated in the buffer cell 716 are then transferred to the buffer cell 722 .

When the object faces the cell unit 718 , the photocell 720 generates charges when it detects light from the object. When the object of the cell unit 718 is no longer facing, the charges generated by the photocell 720 are transferred to the buffer cell 722 , which adds them to the charges received by the buffer cell 716 . The buffer cell 722 now has the total charges generated by the photocells 704 , 710 , 715 and 720 , which are associated with the object that was detected by each of these photocells. Finally, the charges accumulated in the buffer cell 722 are transferred to the cell 732 of the shift register 730 .

The same process takes place in the remaining columns of the TDI-CCD sensor 700 , and at this point all buffer cells of the last row (the row of cell unit 718 ) transfer their charges to the corresponding cells 732 , 734 , 736 and 738 . At this point, the loads are horizontally transferred to a storage unit (not shown) for further processing to the right.

Reference is made below to FIG. 9, which shows a schematic flow diagram of another embodiment of a method according to the invention for operating the TDI-CCD sensor of FIG. 2A.

At step 800, the photocells of device 200 are activated so that they can sense light from an object and thereby generate charges.

At step 802, the charges accumulated in each photocell are transferred to the adjacent associated cell. For most photocells, the neighboring cell is the neighboring buffer cell. The charges are therefore transferred from the photocell 210 A to the buffer cell 212 A. In the TDI sensors according to the invention, in which no buffer cells are connected downstream of the last photocell, such as in the case of the module 600 shown in FIG. 6, the cell adjacent to the last photocell is the corresponding cell in the shift register. In these cases the charges are transferred from the last photocell to the shift register.

If the TDI structure of the last photocell has switched buffer cells, the charges of this last photocell to the corresponding cell of the Shift registers are transferred after these buffer cells have gone through

At step 804, the photocells of device 200 are deactivated. This activation and deactivation in steps 804 and 800 can be achieved by applying a predetermined constant voltage to the photocells, activating and deactivating a reset state, etc.

At step 806, the charges in each of the buffer cells are transferred to the next photocell. Therefore, the charges are transferred from the buffer cell 212 A to the next photo cell 210 B. The cell next to the last buffer cell is the corresponding cell in the shift register. Therefore, the charges are transferred from the buffer cell 212 E to the shift register 232 .

At step 808, the charges are shifted ghost pushed out.

Reference is made below to FIG. 10, which shows a schematic flow diagram of a further embodiment of a method according to the invention for operating the TDI-CCD sensor 400 from FIG. 4A.

At step 850, the photocell P _{i is} activated to detect tightly from an object and thereby generate charges.

At step 852, the charges are transferred from the B _{SECOND, i-1} buffer cell to the P _i photocell and accumulated with new, densely generated charges. According to the example shown, the charges contained in the buffer cell 406 A are transferred to the photo cell 402 B.

At step 854, the charges are transferred from buffer cell B _{FIRST, i} to the next adjacent assigned buffer cell B _{SECOND, i} . In the example shown, the charges are transferred from the buffer cell 404 A to the buffer cell 406 A.

At step 856, the charges generated by the photocell are transferred from photocell P _i to the next cell. For most cells, the next cell is the neighboring, assigned buffer cell B _{FIRST, i} . For example, the charges are transferred from photocell 402 A to buffer cell 402 B. At step 858, the photocells of device 400 are deactivated.

At step 860, the photocells of device 400 are reset.

At step 862, the charges are transferred from the last buffer cell to the corresponding shift register cell. In the example shown, the charges are transferred from buffer cell 406 X to shift register 432 .

At step 864, the charges are transferred from the B _{cell FIRST, LAST} to the cell B _{SECOND, LAST} . In the example shown, the charges are transferred from the buffer cell 404 X to the buffer cell 406 X.

The process is then repeated from step 850, while the photocell P _{i + 1} generates charges and adds these newly generated charges to the charges previously transferred from the B _{SECOND, i} buffer cell, thereby accumulating charges.

At step 866, those in the shift register cell arranged loads for further processing and presentation transferred to a storage unit.

Steps of this method can be carried out in a different order, for example steps 862 and 864 can be carried out before step 852 (see FIG. 5 for further explanation).

Reference is now made to FIG. 11, which shows a schematic representation of pulse diagrams for operating the TDI-CCD sensor 700 of FIG. 8 according to another preferred embodiment of the present invention.

Diagram 900 shows a clock provided by a control device, which represents the movement of an object detected by the TDI-CCD sensor 700 . Time period 910 shows a signal that the object is facing selected cell units.

Diagram 902 shows the exposure and reset clock of the photocell unit, where T _{EXP is} the length of time that a photocell of the selected cell unit is activated to generate charges when it detects light from the object. The time period 912 is followed by a reset time period T _RESET 914 , in which the photocell of the selected cell unit is reset.

Diagram 904 shows the clock for transferring charges from the photocells to the buffer cells of a selected cell unit. In time period 916 , the charges generated by a photocell are transferred to a buffer cell arranged under the photocell J. In terms of time, this period of time is arranged at the extreme end of the exposure time of 912 T _EXP . The charges that are transferred from the photo cell to the buffer cell are added to the charges already in the buffer cell.

Diagram 906 shows the clock signal of the buffer-to-buffer charge transfer. In time period 918 , charges are transferred down from one buffer to the next buffer of the same column.

Diagram 908 shows the clock signal T _{HSR of} the horizontal shift register. In the time period 920 , the charges arranged in each of the cells of the horizontal shift register 730 are output and can be processed and displayed by image processing hardware and software.

Reference is made below to FIG. 12, which shows a schematic flow diagram of another preferred embodiment of a method according to the invention for operating the module 700 .

At step 870, the photocell P _{i is} activated to detect light from an object and thereby generate charges.

At step 872, the charges generated by the photocell P _i er are transferred to the buffer cell B _{i of} the same cell unit. In the example shown, the charges accumulated in the photocell 710 are transferred to the buffer cell 712 .

In step 874 the photocells P _i are disabled.

At step 876 preserved the ent in the buffer cell B _i charges to the next adjacent cell buffer B _{i + 1} are transmitted. At the same time, the charges contained in the last buffer cell B _LAST are transferred to the corresponding shift register cell. In the example shown, the charges are transferred from the buffer cell 722 to the shift register cell 732 .

At step 878, a reset signal is applied to the photocell P _i . As described above, the structure of the invention resets the photocells, thereby reducing the over-brightening or blooming effect.

Steps 878 and 876 can be simultaneous and general my run in any order.

At step 880, those are placed in the shift register ned loads for further processing and presentation give.

Claims (19)

1. Charge-coupled device with time delay and integration function (TDI-CCD device), with:
a charge transfer unit;
a reset unit;
a horizontal shift register; and
at least one cell column with a plurality of cell units connected in series, which define a charge flow directed downstream to the horizontal shift register;
wherein each of the plurality of cell units has a photocell that generates charges when exposed and has at least one buffer cell for storing charges, the photocell and the at least one buffer cell being connected in series;
the charge transfer unit connected to each of the photocells and the buffer cells controls the device by transferring charges downstream between the individual cells and by transferring charges from the first cell column to the horizontal shift register; and
the reset unit resets each of the photocells after the charges accumulated in each of the photocells have been transferred therefrom. 2. Module according to claim 1, wherein
each of the cell units has a first vertical length;
each of the photocells has a second vertical length; and
the first vertical length is equal to twice the second vertical length. 3. Module according to claim 1, wherein
each of the cell units has a first vertical length;
each of the photocells has a second vertical length; and
the first vertical length is substantially the same as the second vertical length. 4. Module according to one of claims 1 and 2, each of the cell units has two buffer cells. 5. Module according to claim 1, wherein the at least one Cell column also one with the horizontal shoot additional photocell connected in series having. The device of claim 1, wherein each of the cell units ten has a single buffer cell. 7. cell unit for insertion into a TDI-CCD module, with a photocell that generates and accumulates charges if it is exposed, and at least one Buffer cell for storing charges, the Pho top cell and the at least one buffer cell in series are switched. 8. Charge-coupled device with time delay and integration function (TDI-CCD device), with:
a charge transfer unit;
a reset unit;
a horizontal shift register; and
at least one cell column with a plurality of cell units connected in series, which define a flow of charge directed downstream towards the horizontal shift register;
wherein each of the plurality of cell units has a photocell that generates charges when exposed and a buffer cell disposed below the photocell and connected to the photocell for storing charges;
the charge transfer unit connected to each of the photo cells and the buffer cells controls the device by transferring charges in a selected cell unit from a photo cell of the selected cell unit to a buffer cell of the selected cell unit;
the charge transfer unit further controls the device by transferring charges between the buffer cells down to the horizontal shift register; and
the reset unit resets each of the photocells after the charges accumulated in each of the photocells have been transferred therefrom. 9. Charge-coupled device according to claim 8, wherein the Reset unit each of the at least one cell columns resets individually. 10. Charge-coupled device according to claim 8, wherein the Reset unit individual rows of cell units resets. 11. Cell unit for insertion into a TDI-CCD module, with a photocell that generates and accumulates charges if it is exposed, and at least one Buffer cell for storing charges, the min at least a buffer cell under the photocell is not.   12. A method for operating a TDI-CCD module, the TDI-CCD module having a plurality of cell columns, each of the cell columns having a plurality of cell units, each of the cell units having a photocell and a buffer cell connected to and arranged beneath the photocell, and the buffer cells of the cell units are connected in series to define a structure which is downstream and ends in a shift register, the method comprising the step of repeating the following steps:
Exposing the photocells;
Detecting light from an object to generate charges through the photocells;
Transferring the charges in each cell unit from the photocells to the buffer cells;
Deactivating the exposure of the photocells; and
Transfer of charges between the buffer cells downstream to the shift register. 13. A method for operating a TDI-CCD module, the TDI-CCD module having a plurality of cell columns, each of the cell columns having a plurality of cell units connected in series, each of the cell units having a photocell and a buffer cell connected in series, and the last Cell unit of each cell column is connected to a shift register, where the method has the step of repeating the following steps:
Activating the detection of light from an object to generate charges through the photocells;
Transferring the charges in each cell unit from the photocells to the buffer cells;
Transferring charges from the buffer cell of the last cell unit to the shift register;
Deactivating the detection of light by the photocells; and
Transfer of charges between the buffer cells downstream of the shift register from a buffer cell of a selected cell unit to a photo cell of a downstream cell unit. 14. A method for operating a TDI-CCD module, the TDI-CCD module having a plurality of cell columns, each of the cell columns having a plurality of cell units and a last cell unit, each of the cell units having a photocell and a buffer cell connected in series therewith, and each of the last cell units has a photocell and is connected to a shift register, the method comprising the step of repeating the following steps:
Activating the detection of light from an object to generate charges through the photocells;
Transferring the charges in each cell unit from the photocells to the buffer cells;
Transferring charges from each of the last cell units to the shift register;
Deactivating the detection of light by the photocells; and
Transfer of charges between the cell units downstream of the shift register from a buffer cell of a selected cell unit to a photo cell of a downstream cell unit. 15. A method for operating a TDI-CCD module, the TDI-CCD module having a plurality of cell columns, each of the cell columns having a plurality of cell units connected in series, each of the cell units a photocell, a first buffer cell connected in series with the photocell and has a second buffer cell connected in series with the first buffer cell and the last cell unit of each cell column is connected to a shift register, the method comprising the step of repeating the following steps:
Activating the detection of light from an object to generate charges through the photocells;
Transferring the charges in each cell unit from the photocells to the first buffer cells;
Deactivating the detection of light by the photocells;
Transferring charges between the cell units downstream of the shift register from a second buffer cell of a selected cell unit to a photocell of a downstream cell unit;
Transferring charges in each cell unit from the first buffer cells to the second buffer cells; and
Transfer of charges from the second buffer cell of the last cell unit to the shift register. 16. The method of claim 12, 13, 14 or 15, further comprising the step of transferring charges from the slider ghost. 17. The method according to claim 12, 13, 14 or 15, further comprising the step to reset the photocells. 18. The method of claim 12, 13, 14 or 15, wherein the Step to expose the photocells to Deactivating a return fed to the photocells has set signal. 19. The method of claim 12, 13, 14 or 15, wherein the Step to deactivate the exposure of the photocells  the step to activate one of the photocells led reset signal.