CN100481184C - Method for controlling light charge quantity of light sensing LED and image sensor thereof - Google Patents
Method for controlling light charge quantity of light sensing LED and image sensor thereof Download PDFInfo
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- CN100481184C CN100481184C CNB2005101350639A CN200510135063A CN100481184C CN 100481184 C CN100481184 C CN 100481184C CN B2005101350639 A CNB2005101350639 A CN B2005101350639A CN 200510135063 A CN200510135063 A CN 200510135063A CN 100481184 C CN100481184 C CN 100481184C
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- light sensitive
- sensitive diode
- transistor
- reference voltage
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Abstract
This invention relates to a method for measuring photoelectric charges of a light sensing diode in controllable active pixels and a sensing device, in which, the method includes: providing a reference voltage greater than the earth potential to the grid of a converted transistor when a light sensing diode is exposed and one end of which contacts to the earth to control the photoelectric charges stored by light sensing diode, which advoides image resort and halation.
Description
Technical field
The invention provides a kind of initiatively method of pixel of controlling, refer to the method and the Image sensor apparatus thereof of the charge quantity of light that a kind of sense of control optical diode can store especially.
Background technology
See also Fig. 1, Fig. 1 is the previous initiatively circuit diagram of pixel 8.Active pixel 8 comprises clamps down on type light sensitive diode (pinned photodiode) 10, one conversion (transfer) transistor 12, replacement (reset) transistor 14, one source pole follower (source follower) 16 and one column select switch (row selector) transistor 18.Clamp down on type light sensitive diode 10 and be used for receiving light; Conversioning transistor 12 is used for controlling and is stored in the electric charge clamped down in the type light sensitive diode 10 and shifts; Reset transistor 14 is used for resetting and clamps down on type light sensitive diode 10; The current potential of the source electrode of source follower 16 can change along with the electric charge that grid received (charge) of source follower 16; Column select switch transistor 18 is used for controlling the storage of light signal or reset signal.
Initiatively pixel 8 is as follows to the running that stores light signal from acquisition light.At first carry out the action of resetting, starting resetting transistor 14 and conversioning transistor 12 impose on a noble potential (the ceiling voltage Vdd of circuit operation), to reset to clamping down on type light sensitive diode 10 at the grid place of transistor 12,14.Then enter exposure mode, pick-up image just, close conversioning transistor 12 and reset transistor 14 this moment, the grid of closing conversioning transistor 12 in the prior art and be at conversioning transistor 12 imposes on an electronegative potential (0 volt), clamps down on type light sensitive diode 10 this moment and receives light and store charge in wherein.See also Fig. 2, Fig. 2 is Fig. 1 mid point P and the synoptic diagram of some R place store charge, and the stored quantity of electric charge of type light sensitive diode 10 is clamped down in the representative of its mid point P place, and puts the quantity of electric charge that the R place represents the source electrode place storage of reset transistor 14.
Then read reset signal earlier.Please continue to consult Fig. 3, Fig. 3 is the synoptic diagram that reads reset signal.The electric charge that utilizes source follower 16 and column select switch transistor 18 branchpoint R places to store, this moment, conversioning transistor 12 was in closed condition with reset transistor 14, and source follower 16 is in opening with column select switch transistor 18.After having read reset signal, read light signal again, see also Fig. 4; Fig. 4 is the synoptic diagram that reads light signal.Open conversioning transistor 12 and clamp down on electric charge stored in the type light sensitive diode 10, utilize source follower 16 and column select switch transistor 18 to store light signal again, promptly finish image capture with transfer.
It is halation phenomenon that the shortcoming that prior art active pixel 8 is easy to generate has two: one; Two problems for the image delay are in explanation respectively down.
Please continue to consult Fig. 5 and Fig. 6, Fig. 5 is for conversioning transistor 12 and clamp down on the synoptic diagram of type light sensitive diode 10 under high light; The synoptic diagram that Fig. 6 overflows for optical charge among Fig. 5.Owing to during exposure, execute the grid of 0 volt of current potential, so conversioning transistor 12 is a closed condition at conversioning transistor 12.If through strong illumination, may cause the charge quantity of light that receives too much, and exceed the maximum optical charge capacity that 10 of type light sensitive diodes can hold of clamping down on.Because the conversioning transistor 12 of this moment is a closed condition, too much optical charge do not have that other path can be led off thereby overflow to around pixel in, influence the image capture of neighborhood pixels, cause having in the image the dizzy phenomenon of opening, this phenomenon is called halation phenomenon (blooming).
In addition, in the semiconductor preparing process (process) of diode, it is considerable that 10 quantities of electric charge that can store of type light sensitive diode are clamped down in control, if the bad meeting of control causes image as shown in Figure 7 to be detained (image lag) problem, Fig. 7 is the synoptic diagram that Fig. 1 mid point P and some R place image are detained.Because the electric charge of Fig. 7 mid point P can't shift away fully, that is to say residual electric charge in clamping down on type light sensitive diode 10, thereby produce the phenomenon that image is detained.The quantity of electric charge size that prior art utilizes technology (CONTROL PROCESS parameter) to change to clamp down on quantity of electric charge size that 10 of type light sensitive diodes can store or the source electrode place that changes reset transistor 14 can store usually is to avoid the phenomenon generation of Fig. 7.Yet, CONTROL PROCESS and be not easy and cost too high, therefore need more easy control mode solve the problem that image is detained.
Summary of the invention
The object of the present invention is to provide a kind of method and Image sensor apparatus thereof of charge quantity of light of sense of control optical diode, to solve the above problems.
In order to realize described purpose, technical scheme of the present invention is:
A kind of Image sensor apparatus of charge quantity of light of sense of control optical diode comprises:
One light sensitive diode is used for receiving light;
One the first transistor, its source electrode is connected in described light sensitive diode, and this first transistor is used for controlling the transfer of optical charge in this described light sensitive diode;
One reference voltage control module, be connected in the grid of described the first transistor, this reference voltage control module receives a plurality of control signals that the result that detects according to image generates when light sensitive diode is in exposure status, and according to described a plurality of control signals provide a reference voltage in the grid of described the first transistor to control the charge quantity of light that described light sensitive diode can store;
One transistor seconds, its source electrode is connected in the output terminal of described the first transistor, and drain electrode is connected in a voltage source, the described transistor seconds described light sensitive diode that is used for resetting;
One the 3rd transistor, its drain electrode is connected in described voltage source, and grid is connected in the source electrode of described transistor seconds; And
One the 4th transistor, its drain electrode are connected in the described the 3rd transistorized source electrode, and source electrode is connected in a character line, and whether described the 4th transistor is used for selecting output signal.
Described reference voltage control module is provided in the reference voltage of grid of described the first transistor between zero volt and described voltage source.
When described reference voltage control module provided the grid of described reference voltage in the first transistor, described light sensitive diode was under the exposure status, in order to control the charge quantity of light that described light sensitive diode can store.
Described light sensitive diode is to clamp down on the type light sensitive diode.
A kind of method of controlling the charge quantity of light of light sensitive diode in the active pixel comprises:
When an end ground connection of light sensitive diode exposure and described light sensitive diode, the result who detects according to image generates control signal, and according to described control signal provide one greater than the reference voltage of earthing potential in the grid of a conversioning transistor, to control the charge quantity of light that described light sensitive diode can store.
Described reference voltage is less than a maximum working voltage.
Described light sensitive diode is to clamp down on the type light sensitive diode.
Provide the grid of described reference voltage by a reference voltage control module according to a plurality of control signals that received, to control the charge quantity of light that described light sensitive diode can store in described conversioning transistor.
Detect image whether abnormal occurrence is arranged.
Whether whether the detection image has abnormal occurrence to comprise detection has image to be detained.
Whether whether the detection image has abnormal occurrence to comprise detection halation phenomenon.
The present invention disclose a kind of can be when an end ground connection of light sensitive diode exposure and this light sensitive diode, provide one greater than the reference voltage of earthing potential in the grid of a conversioning transistor, to control the charge quantity of light that described light sensitive diode can store, avoided image to be detained and halation phenomenon thus.The present invention is after preparation technology finishes, utilize a reference voltage control module to change the quantity of electric charge size that the type light sensitive diode of clamping down on can store, it is comparatively simple and precisely, cost is also cheaper to utilize the mode of CONTROL PROCESS (CONTROL PROCESS parameter) to change quantity of electric charge size that the type light sensitive diode of clamping down on can store with respect to prior art.
Description of drawings
Fig. 1 is the previous initiatively circuit diagram of pixel;
Fig. 2 is Fig. 1 mid point P and the synoptic diagram of putting R place store charge;
Fig. 3 reads the synoptic diagram of reset signal for Fig. 1 active pixel;
Fig. 4 reads the synoptic diagram of light signal for Fig. 1 active pixel;
Fig. 5 is for conversioning transistor and clamp down on the synoptic diagram of type light sensitive diode under high light;
The synoptic diagram that Fig. 6 overflows for optical charge among Fig. 5;
Fig. 7 is initiatively pixel mid point P and the synoptic diagram of putting the image delay of R place of Fig. 1;
Fig. 8 is the conversioning transistor and the synoptic diagram of clamping down on the type light sensitive diode of Fig. 1 active pixel;
Fig. 9 presentation graphs 8 is clamped down on the synoptic diagram of the size of the quantity of electric charge that the type light sensitive diode can store;
The schematic representation of apparatus that Figure 10 clamps down on the type light sensitive diode quantity of electric charge for the present invention's control;
Figure 11 to Figure 13 is for clamping down on the synoptic diagram of type light sensitive diode amounts of stored charge under the different reference voltages;
Figure 14 to Figure 16 is respectively and shifts the synoptic diagram of clamping down on type light sensitive diode electric charge among Figure 11 to Figure 13;
Figure 17 clamps down on the process flow diagram of the type light sensitive diode quantity of electric charge for the present invention's control.
The main element symbol description:
8 active pixels 10 are clamped down on the type light sensitive diode
12 conversioning transistors, 14 reset transistors
16 source follower, 18 column select switch transistors
20 reference voltage control module P, R point
Embodiment
The invention provides a kind of control and clamp down on the method for 10 quantities of electric charge that can store of type light sensitive diode, with the problem of image delay and halation phenomenon in the solution prior art.
Notion of the present invention at first is described.The generation that image is detained is because the electric charge of clamping down in the type light sensitive diode 10 can't shift fully.Therefore if 10 charge capacities that can store of type light sensitive diode are clamped down in minimizing, the image trapping phenomena can be avoided.In addition, halation phenomenon is owing to receive too much charge quantity of light, causes the optical charge overflow to pixel on every side.Therefore also can clamp down on 10 charge capacities that can store of type light sensitive diode, reduce the generation of halation phenomenon by control.
See also Fig. 8, Fig. 8 is conversioning transistor 12 and the synoptic diagram of clamping down on type light sensitive diode 10.When a voltage V is provided
gWhen the grid of conversioning transistor 12, because transistor itself has a threshold voltage (threshold) V
Th, so the voltage of conversioning transistor 12 source electrodes is V
gDeduct V
Th, this V
ThComprise matrix effect (body effect).Please continue to consult Fig. 9, clamp down on the synoptic diagram of the size of 10 quantities of electric charge that can store of type light sensitive diode in Fig. 9 presentation graphs 8, wherein more down its value is big more for the magnitude of voltage among Fig. 9, just V
PinnedGreater than (V
g-V
Th).As shown in Figure 9, clamp down on the controlled scope V that is formed on of charge capacity of type light sensitive diode 10
PinnedTo (V
g-V
Th) between.
The two voltages source that can be learnt the capacity that influences the quantity of electric charge of clamping down on type light sensitive diode 10 by Fig. 9 is V
PinnedAnd (V
g-V
Th), clamp down on the bolt voltage V of type light sensitive diode 10
PinnedWith threshold voltage V
ThAfter preparation technology finishes, be fixed value, therefore can impose on the voltage V of conversioning transistor 12 grids by change
gChange the size of clamping down on 10 energy amounts of stored charge of type light sensitive diode.In other words, the voltage that imposes on conversioning transistor 12 grids is big more, and the size of clamping down on 10 energy amounts of stored charge of type light sensitive diode is just more little.
Therefore, the present invention is that the voltage of control transformation transistor 12 grids under exposure mode is clamped down on 10 quantities of electric charge that can store of type light sensitive diode with change.See also Figure 10, the schematic representation of apparatus that Figure 10 clamps down on the type light sensitive diode quantity of electric charge for the present invention's control.The present invention sets up a reference voltage control module 20, when generation of image trapping phenomena or halation phenomenon generation, send a plurality of control signals in reference voltage control module 20, adjusting the reference voltage of the grid that under exposure mode, is provided in conversioning transistor 12, mat and change the size of clamping down on 10 energy amounts of stored charge of type light sensitive diode among Fig. 9.
Under exposure mode, provide zero in the prior art and lie prostrate, so that conversioning transistor 12 is in closed condition in the grid of conversioning transistor 12.Yet, the present invention under exposure mode, provide one greater than the reference voltage of zero volt in the grid of conversioning transistor 12, and reference voltage is less than the maximum voltage of circuit operation.
For instance, under exposure mode, provide reference voltage greater than zero volt in the grid of conversioning transistor 12.See also Figure 11 to Figure 13, Figure 11 to Figure 13 is for clamping down on the synoptic diagram of type light sensitive diode 10 amounts of stored charge, wherein V under the different reference voltages
1Less than V
2And V
2Less than V
3Three figure can learn thus, clamp down on type light sensitive diode 10 open ended quantity of electric charge maximums among Figure 11, are Figure 12 secondly, the open ended quantity of electric charge minimum of Figure 13.Just, the voltage that imposes on conversioning transistor 12 grids is big more, and it is just more little to clamp down on 10 quantities of electric charge that can store of type light sensitive diode.Through over-reset, expose and read reset signal after, then shift the electric charge of clamping down in the type light sensitive diode 10.See also Figure 14 to Figure 16, Figure 14 to Figure 16 is respectively and shifts the synoptic diagram of clamping down on type light sensitive diode 10 electric charges among Figure 11 to Figure 13.If the image that produces as Figure 14 is detained, then increase imposes on the voltage of conversioning transistor 12 grids, as applies voltage V
3, the generation that can avoid image to be detained, as shown in figure 16, it can make the electric charge of clamping down on type light sensitive diode 10 shift fully.
More than be the explanation of the embodiment of the invention, wherein light sensitive diode is not defined as and clamps down on type light sensitive diode 10, and structure of the present invention also can adopt the active light sensitive diode of other type.
See also Figure 17, Figure 17 clamps down on the process flow diagram of type light sensitive diode 10 quantities of electric charge for the present invention's control.
Step 100: carry out and reset and exposure, store optical charge so that clamp down on type light sensitive diode 10;
Step 102: read reset signal;
Step 104: shift the optical charge of clamping down in the type light sensitive diode 10, and read light signal;
Step 106: whether have unusually, abnormal occurrence can comprise phenomenons such as halation, image delay if detecting image.If image abnormal enters step 108; If no abnormal, enter step 110;
Step 108: send control signal in reference voltage control module 20, with under exposure mode, provide one greater than the reference voltage of zero volt in conversioning transistor 12 grids, to reduce to clamp down on 10 quantities of electric charge that can store of type light sensitive diode, follow rebound step 100;
Step 110: finish the control of clamping down on 10 quantities of electric charge that can store of type light sensitive diode.
With respect to prior art, the invention provides a kind of control and clamp down on the method for the type light sensitive diode quantity of electric charge, grid at conversioning transistor 12 provides a reference voltage greater than earthing potential, change and clamp down on 10 quantity of electric charge sizes that can store of type light sensitive diode, avoid image to be detained and halation phenomenon by this.The present invention is after technology finishes, utilize a reference voltage control module to change and clamp down on 10 quantity of electric charge sizes that can store of type light sensitive diode, utilize the mode of processing procedure to change to clamp down on 10 quantity of electric charge sizes that can store of type light sensitive diode comparatively simple and precisely, cost is also cheaper with respect to prior art.
The above only is preferred embodiment of the present invention, and all equalizations of being done according to the present patent application claim change and modify, and all should belong to covering scope of the present invention.
Claims (11)
1. the Image sensor apparatus of the charge quantity of light of a sense of control optical diode is characterized in that comprising:
One light sensitive diode is used for receiving light;
One the first transistor, its source electrode is connected in described light sensitive diode, and this first transistor is used for controlling the transfer of optical charge in this described light sensitive diode;
One reference voltage control module, be connected in the grid of described the first transistor, this reference voltage control module receives a plurality of control signals that the result that detects according to image generates when light sensitive diode is in exposure status, and according to described a plurality of control signals provide a reference voltage in the grid of described the first transistor to control the charge quantity of light that described light sensitive diode can store;
One transistor seconds, its source electrode is connected in the output terminal of described the first transistor, and drain electrode is connected in a voltage source, the described transistor seconds described light sensitive diode that is used for resetting;
One the 3rd transistor, its drain electrode is connected in described voltage source, and grid is connected in the source electrode of described transistor seconds; And
One the 4th transistor, its drain electrode are connected in the described the 3rd transistorized source electrode, and source electrode is connected in a character line, and whether described the 4th transistor is used for selecting output signal.
2. Image sensor apparatus according to claim 1 is characterized in that: described reference voltage control module is provided in the reference voltage of grid of described the first transistor between zero volt and described voltage source.
3. Image sensor apparatus according to claim 1, it is characterized in that: when described reference voltage control module provides the grid of described reference voltage in the first transistor, described light sensitive diode is under the exposure status, in order to control the charge quantity of light that described light sensitive diode can store.
4. Image sensor apparatus according to claim 1 is characterized in that: described light sensitive diode is to clamp down on the type light sensitive diode.
5. method of controlling the charge quantity of light of light sensitive diode in the pixel initiatively is characterized in that comprising:
When an end ground connection of light sensitive diode exposure and described light sensitive diode, the result who detects according to image generates control signal, and according to described control signal provide one greater than the reference voltage of earthing potential in the grid of a conversioning transistor, to control the charge quantity of light that described light sensitive diode can store.
6. method according to claim 5 is characterized in that: described reference voltage is less than a maximum working voltage.
7. method according to claim 5 is characterized in that: described light sensitive diode is to clamp down on the type light sensitive diode.
8. method according to claim 5, it is characterized in that: provide the grid of described reference voltage by a reference voltage control module according to a plurality of control signals that received, to control the charge quantity of light that described light sensitive diode can store in described conversioning transistor.
9. whether method according to claim 5: detecting image has abnormal occurrence if is characterized in that also comprising.
10. method according to claim 9 is characterized in that: whether whether the detection image has abnormal occurrence to comprise detecting has image to be detained.
11. method according to claim 9 is characterized in that: whether whether the detection image has abnormal occurrence to comprise detecting halation phenomenon.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101350639A CN100481184C (en) | 2005-12-23 | 2005-12-23 | Method for controlling light charge quantity of light sensing LED and image sensor thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101350639A CN100481184C (en) | 2005-12-23 | 2005-12-23 | Method for controlling light charge quantity of light sensing LED and image sensor thereof |
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| Publication Number | Publication Date |
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| CN1987973A CN1987973A (en) | 2007-06-27 |
| CN100481184C true CN100481184C (en) | 2009-04-22 |
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| CN104571645B (en) * | 2013-10-23 | 2017-09-22 | 原相科技股份有限公司 | Image sensor apparatus and the optical navigator using this Image sensor apparatus |
| CN107093417B (en) | 2017-07-03 | 2020-06-16 | 京东方科技集团股份有限公司 | Photosensitive circuit, driving method thereof and electronic device |
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