CN116744108A - Image sensor and signal reading control method thereof - Google Patents
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Abstract
The invention provides an image sensor and a signal reading control method thereof, wherein the image sensor comprises a pixel array and a row selection control line, a focusing photosensitive pixel unit part in a focusing pixel column included in the pixel array is shielded to obtain an output value thereof, and focus control is carried out based on the output value; the row selection control line receives a row selection control signal and controls and selects pixel units of rows to be read out according to the row selection control signal to read out pixel signals; in a normal working mode, the image sensor reads out each pixel row in the pixel array row by row; in the combined readout mode, at least two rows of pixel rows spaced by odd rows receive row selection control signals at the same time, and a focusing photosensitive pixel unit and a non-focusing photosensitive pixel unit spaced by odd rows receive row selection control signals at the same time in a focusing pixel column correspond to one readout channel respectively, wherein one readout channel is opened, and the other readout channel is closed. The invention improves the phase focusing performance and the frame rate of pixel processing.
Description
Technical Field
The present invention relates to image signal control technology, and more particularly, to an image sensor and a signal reading control method thereof.
Background
Image sensors are commonly used in various electronic devices and products, such as digital cameras, video monitoring devices, face recognition, unmanned aerial vehicles, and the like, to capture and recognize images.
In the prior art, various optimization schemes are required to enhance the phase focusing technique, and the pixel array of the bayer array is shown in fig. 1, where G represents Green, R represents Red, and B represents Blue in the three primary colors. Two G's are used in a 2x2 pixel array because they are the most sensitive to green by the human eye.
For the bayer array shown in fig. 1, the circuit diagram of the bayer array is shown in fig. 2, the 4 photodiodes correspond to filters of three colors, signals of the photodiodes are controlled by tx series transmission tubes to be transmitted to the node FD, the signals are used for resetting by a reset transistor rst, and finally, a pixel selection transistor rs is controlled by a control signal rowsel to perform row selection operation, so that pixel information is paid out.
However, the conventional bayer array is inserted with a phase focusing technology, so that the phase focusing performance is relatively poor, and therefore, a solution to the technical defect is needed.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide an image sensor and a signal reading control method thereof, which are used for solving the problem of poor phase focusing performance in the prior art.
To achieve the above and other related objects, the present invention provides an image sensor comprising:
a pixel array including a plurality of pixel units arranged in a bayer array, each of the pixel units including pixel points laid out in a 2×2 structure and having the same color; the pixel array comprises a focusing pixel column, wherein part of blue pixels or red pixels in the focusing pixel column are replaced by green pixels to form a focusing photosensitive pixel unit, and the focusing photosensitive pixel unit is partially shielded to acquire an output value of the focusing photosensitive pixel unit and perform focusing control based on the output value;
a row selection control line for receiving a row selection control signal and controlling and selecting pixel units of rows to be read to read out pixel signals according to the row selection control signal;
the image sensor comprises a normal working mode and a combined reading mode; in the normal working mode, pixel rows in the pixel array are read out row by row; in the combined readout mode, at least two rows of pixel rows spaced by odd rows receive row selection control signals at the same time, and in the focusing pixel columns, focusing photosensitive pixel units simultaneously receiving row selection control signals and non-focusing photosensitive pixel units spaced by odd rows correspond to one readout channel respectively, wherein one readout channel is opened, and the other readout channel is closed.
Preferably, the pixel signal reading circuit further comprises a column line for reading out the pixel signals of the pixel units of the row to be read, wherein the column line comprises a first column line and a second column line; in the focusing pixel column, the focusing photosensitive pixel units are read out through a first column line, and the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows are read out through a second column line.
Preferably, each two focusing photosensitive pixel units located in the same pixel row form a focusing photosensitive pixel unit pair, and the blocked areas of the focusing photosensitive pixel units in each focusing photosensitive pixel unit pair are complementary to obtain an output value of each focusing photosensitive pixel unit in each focusing photosensitive pixel unit pair respectively, and focus control is performed based on the output values.
Preferably, two of the focusing photosensitive pixel units in the focusing photosensitive pixel unit pair are spaced by an odd number of columns.
Preferably, the focus sensitive pixel cells occupy 3% of the pixel array.
Preferably, in each pixel column, one pixel unit of two pixel units receiving the row selection control signal is read out through the first column line, and the other pixel unit is read out through the second column line.
Preferably, the row selection control lines include a first group of row selection control lines and a second group of selection control lines;
the pixel array comprises focusing pixel rows provided with the focusing photosensitive pixel units, and the first group of row selection control lines are used for controlling non-focusing photosensitive pixel units in the focusing pixel rows to read out pixel signals; the second group of row selection control lines are used for controlling the focusing photosensitive pixel units in the focusing pixel rows to read out pixel signals;
in the normal working mode, the first group of row selection control lines are used for controlling the non-focusing photosensitive pixel units to read out pixel signals, and the second group of row selection control lines are used for controlling the focusing photosensitive pixel units to read out pixel signals;
in the merging readout mode, the focusing pixel row does not perform readout of pixel signals, wherein four pixel units of an mth column of a kth row, an mth+2th column of a kth row, an mth column of a kth+2th row, and an mth+2th column of a kth+2th row receive row selection control signals at the same time, and adjacent pixel units located in the same pixel row and spaced from one pixel unit are merged and read out through the same column line, and adjacent pixel units located in the same pixel column and spaced from one pixel unit are read out through different column lines; wherein K and M are positive integers.
Preferably, the nth row of pixels and the row selection control line of the N-2 th row of pixels are symmetrically arranged, wherein N is a positive integer greater than or equal to 2.
Preferably, the N-2 th row of pixels is correspondingly provided with the first group of row selection control lines and the second group of row selection control lines;
in the N-2 th row of pixel rows, the first group of row selection control lines are used for controlling pixel signals to be read out from pixel units which are positioned in the same column as the non-focal sensitive pixel units in the N-th row of pixel rows, and the second group of row selection control lines are used for controlling pixel signals to be read out from pixel units which are positioned in the same column as the focal sensitive pixel units in the N-th row of pixel rows.
Preferably, the first group of row selection control lines outputs a first control signal to the nth row of pixels and the N-2 th row of pixels to control the unfocused photosensitive pixel units in the nth row of pixels and the N-2 th row of pixels to read out pixel signals respectively;
the second group of row selection control lines output a second control signal to the N-2 row of pixel rows to control pixel units in the N-2 row of pixel rows and the pixel units in the same column with the focusing photosensitive pixel units in the N row of pixel rows to read out pixel signals;
The second group of row selection control lines output a third control signal to the nth row of pixel rows to control the focusing photosensitive pixel units in the nth row of pixel rows to read out pixel signals.
To achieve the above and other related objects, the present invention also provides a signal reading control method of an image sensor, the method at least comprising the steps of:
controlling the pixel array to enter a focusing mode;
receiving a control signal, and controlling pixel units of rows to be read to read pixel signals according to the control signal;
the row selection control line is used for controlling a first area of one focusing photosensitive pixel unit in the focusing pixel column to read out pixel signals and outputting a first output value through a first column line;
the row selection control line is used for controlling a second area of the other focusing photosensitive pixel unit in the focusing pixel column to read out pixel signals and outputting a second output value through the first column line; the second region and the first region form a complementary region of a focusing photosensitive pixel unit;
and performing focusing control according to the first output value and the second output value.
Preferably, the performing focus control according to the first output value and the second output value includes:
Generating a first phase value from the first output value;
generating a second phase value from the second output value;
and performing focusing control according to the first phase value and the second phase value.
Preferably, the method further comprises:
the pixel array is controlled to enter a normal working mode, and the row selection control lines sequentially output row selection control signals to each pixel row so as to read out the pixel rows in the pixel array row by row;
controlling the pixel array to enter a merging read-out mode, and simultaneously receiving row selection control signals by every two rows of pixel rows of the odd-numbered rows at intervals; in a pixel column provided with a focusing photosensitive pixel unit, controlling a channel read out by the focusing photosensitive pixel unit through a first column line to be opened, and closing a channel read out by a non-focusing photosensitive pixel unit which is separated from the focusing photosensitive pixel unit by an odd number row through a second column line; or alternatively, the process may be performed,
in the pixel column provided with the focusing photosensitive pixel units, the channel read out by the focusing photosensitive pixel units through the first column line is closed, and the channel read out by the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows through the second column line is opened.
Preferably, two sets of row selection control lines are provided, wherein the first set of row selection control lines are used for controlling pixel units in the N-2 th row of pixel rows and pixel units in the same column with the non-focusing photosensitive pixel units in the N-th row of pixel rows to read out pixel signals; the second group of row selection control lines are used for controlling pixel units in the N-2 th row of pixel rows, which are positioned in the same column as the focusing photosensitive pixel units in the N-th row of pixel rows, to read out pixel signals.
Preferably, in the merging readout mode, a readout channel of the pixel signal of the focusing pixel row is controlled to be closed, and four pixel units of an mth column of a kth row, an mth+2column of a kth row, an mth column of a kth+2row, and an mth+2column of a kth+2row are controlled to simultaneously receive a row selection control signal, wherein adjacent pixel units located in the same pixel row and spaced from one pixel unit are merged and read out through the same column line, and adjacent pixel units located in the same pixel column and spaced from one pixel unit are both read out through the first column line and the second column line respectively.
As described above, the image sensor and the signal reading control method thereof of the present invention have the following advantages:
the image sensor realizes the control of selecting pixel units of a row to be read through the pixel array with optimized layout and the control signals received simultaneously to respectively and simultaneously read out the pixel signals; the pixel unit layout in the pixel array can realize a larger pixel range and a photosensitive area, and four pixel points included in the pixel unit adopt the same control signal, so that the pixel processing speed can be greatly improved, and the frame rate of pixel processing can be further improved.
Drawings
FIG. 1 is a schematic diagram of a prior art Bayer array layout;
fig. 2 is a schematic circuit diagram of a bayer array according to the prior art;
FIG. 3 is a schematic layout of a pixel unit according to an embodiment of the invention;
FIG. 4 is a schematic diagram showing a layout structure of an image sensor according to an embodiment of the invention;
FIG. 5 is a timing diagram showing the readout of the image sensor shown in FIG. 4 in a normal operation mode;
FIG. 6 is a timing diagram showing readout in the vertical merge readout mode of the image sensor shown in FIG. 4;
FIG. 7 is a schematic diagram showing an image sensor layout structure according to another embodiment of the present invention;
FIG. 8 is a timing diagram showing the turning off of PDAF during lateral readout of the image sensor shown in FIG. 7;
fig. 9 shows a timing chart of turning on the PDAF at the time of lateral readout of the image sensor shown in fig. 7.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 3-8. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
The invention adopts one or two groups of control signals to respectively control the pixel units through time sequence, then realizes the control functions of transverse/longitudinal combined reading (binding) and phase focusing through two lines, and simultaneously improves the performance of phase focusing (Phase detection auto-focus, PDAF) and the dynamic range.
Based on the technical conception, the invention provides a technical scheme of an image sensor and a signal reading control method thereof to solve the problems in the prior art, and the technical conception and the technical scheme of the invention are described in detail through the following embodiments.
Embodiment one:
fig. 4 is a schematic layout structure of an image sensor according to an embodiment of the invention. The embodiment of the present invention will be described in detail with reference to fig. 4.
The image sensor provided by the invention comprises:
a pixel array including a plurality of pixel units arranged in a bayer array, each pixel unit including pixel points laid out in a 2×2 structure and having the same color; the pixel array comprises a focusing pixel column, wherein part of blue pixels or red pixels in the focusing pixel column are replaced by green pixels to form a focusing photosensitive pixel unit, and the focusing photosensitive pixel unit is partially shielded to acquire an output value of the focusing photosensitive pixel unit and perform focusing control based on the output value;
a row selection control line for receiving the row selection control signal and controlling and selecting the pixel units of the row to be read to read the pixel signals according to the row selection control signal;
the image sensor comprises a normal working mode and a combined reading mode; in a normal working mode, pixel rows in the pixel array are read out row by row; in the combined readout mode, at least two rows of pixel rows spaced by odd rows receive row selection control signals at the same time, and in the focusing pixel columns, focusing photosensitive pixel units receiving row selection control signals at the same time and non-focusing photosensitive pixel units spaced by odd rows correspond to one readout channel respectively, wherein one readout channel is opened, and the other readout channel is closed.
In the layout setting of the pixel array, the invention replaces part of blue pixels or red pixels in the focusing pixel columns with green pixels to form the focusing photosensitive pixel units, so that the pixel array has more photosensitive units of green pixels, and the photosensitive performance of the pixel array is further improved. Specifically, the pixel array of the present invention includes 8×8 pixel units arranged in a bayer array, each pixel unit being, as shown in fig. 3, pixel dots having the same color and being laid out in a 2×2 structure, green (Green, G), red (Red, R), and Blue (Blue, B), respectively. The whole array of the pixel array is highly symmetrical, and the tubes in the pixel units are all NMOS tubes, so that the transmission speed is high, and high-level enabling is required in the control process.
According to the image sensor, pixel units of a row to be read are controlled and selected to read through the pixel array with optimized layout and the control signals received simultaneously; in the normal working mode, pixel rows are read out row by row, in the combined reading mode, at least two rows of pixel rows which are separated by an odd number of rows are used for receiving row selection control signals at the same time, so that at least two rows of pixel rows can be read out at the same time, the frame rate of pixel processing can be further improved, and as focusing photosensitive pixel units are formed by replacing partial blue pixels or red pixels with green pixels, color blocks among the pixel rows which are simultaneously received with control signals are different, two reading channels are used for respectively outputting pixel signals, and for other pixel rows which are simultaneously received with control signals and have the same color block, another reading channel can be idled or not arranged, so that the frame rate of pixel processing of the invention is not affected. In addition, the pixel unit layout in the pixel array can realize a larger pixel range and a photosensitive area, and four pixel points included in the pixel unit adopt the same control signal, so that the pixel processing speed can be greatly improved. Meanwhile, the performance of phase focusing can be greatly improved by adopting the arrangement mode of the Bayer array.
As a further limitation of the present invention, each two focusing photosensitive pixel units located in the same pixel row form a focusing photosensitive pixel unit pair, and the blocked areas of the focusing photosensitive pixel units in each focusing photosensitive pixel unit pair are complementary to obtain an output value of each focusing photosensitive pixel unit in the focusing photosensitive pixel unit pair, respectively, and focus control is performed based on the output values.
In the embodiment of the present invention, the left half side of one focusing photosensitive pixel unit and the right half side of the other focusing photosensitive pixel unit are complementary to each other in the blocked area, and as other embodiments, the upper half side of one focusing photosensitive pixel unit and the lower half side of the other focusing photosensitive pixel unit in the pair of focusing photosensitive pixel units may also be used; or one quarter of one focus sensitive pixel unit and three quarters of the other focus sensitive pixel unit.
Further, at least two pixel rows spaced by an odd number of rows receive the row selection control signal at the same time, wherein the spaced odd number of rows may be spaced by one row, three rows, or the like.
Specifically, in the present invention, the focusing photosensitive pixel units in the focusing photosensitive pixel unit pair are spaced by odd columns. In the embodiment of the present invention, the pixel unit corresponding to the 2 nd Row and the 3 rd Column (Row 2, column 3) and the pixel unit corresponding to the 2 nd Row and the 7 th Column (Row 2, column 7) in the pixel array are set as the focusing pixel photosensitive pixel unit pair. In the phase focusing process, two focusing photosensitive pixel units are respectively blocked, for example, in fig. 4, the left half of a first focusing photosensitive pixel unit corresponding to the 2 nd Row and the 3 rd Column (Row 2, column 3) is blocked, the right half of a second focusing photosensitive pixel unit corresponding to the 2 nd Row and the 7 th Column (Row 2, column 7) is blocked, and the left half blocking area of the first focusing photosensitive pixel unit and the right half blocking area of the second focusing photosensitive pixel unit are complemented, so that output values of the focusing photosensitive units, namely, a first output value output by the first focusing photosensitive pixel unit and a second output value output by the second focusing photosensitive pixel unit, are obtained, and focusing control is performed through a first phase value generated by the first output value and a second phase value generated by the second output value. That is, the right half imaging of the focusing photosensitive pixel unit pair is realized through the first output value, the left half imaging of the focusing photosensitive pixel unit pair is realized through the second output value, the phase difference is generated according to the first phase value and the second phase value, and then the phase shift is carried out to realize one-step quick focusing.
Because of the existence of the focusing photosensitive pixel units, in order to better optimize and control the signal readout of the image sensor, the image sensor further comprises a column line, which is used for reading out the pixel signals of the pixel units of the row to be read, and comprises a first column line and a second column line; in the focusing pixel column, the focusing photosensitive pixel units are read out through a first column line, and the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows are read out through a second column line.
In the invention, the pixel signals are read out through the two column lines, and the focusing photosensitive pixel units in the focusing pixel columns and the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows can be independently controlled, namely, the pixel signals are read out through different column lines. Wherein the spaced odd rows may be spaced one row, three rows, etc., but must be consistent with the color before the focus sensitive pixel cells are replaced with green pixels.
As shown in fig. 4, the color block arrangement of the 2 nd Row (Row 2) pixel Row is different from that of the 0 th Row (Row 0) pixel Row, and because of parasitic capacitance on the signal lines, the surrounding environments of the pixel units need to be kept consistent, so in order to perform better optimal control when the pixel array is read out, one Row selection control line is arranged for each Row of pixel rows, and two column lines are arranged for focusing pixel columns. As shown in fig. 4, the two Column lines of Column3 (Column 3) are Bitline3_0 and Bitline3_1, respectively; the two Column lines of Column7 (Column 7) are bitlin7_0 and bitlin7_1, respectively. And in order to further match each pixel column on the layout, two column lines are provided for all pixel columns. As shown in fig. 4, two Column lines are provided for the pixel columns such as the 1 st Column (Column 1), the 2 nd Column (Column 2), and the 4 th Column (Column 4) except for the two Column lines of the 3 rd Column (Column 3) and the 7 th Column (Column 7). Therefore, in each pixel column of the present invention, one pixel unit of two pixel units receiving a row selection control signal is read out through a first column line, and the other pixel unit is read out through a second column line. The invention simultaneously inputs the row selection signals to the pixel blocks of the pixel columns which are separated by one row, so that the two pixel color blocks with the same color are simultaneously read out, thereby saving the frame rate. For example, the focusing photosensitive pixel units corresponding to the 2 nd Row and the 3 rd Column (Row 2, column 3) are read out through the first Column line, the non-focusing photosensitive pixel units corresponding to the 0 th Row and the 3 rd Column (Row 0, column 3) are read out through the second Column line, and the image sensor provided by the embodiment of the invention can output the Row selection control signals by using a group of Row selection control lines, wherein the timing of reading out the image sensor using a group of Row selection control lines in the normal working mode is shown in fig. 5, and the timing of reading out the image sensor using a group of Row selection control lines in the longitudinal combination reading mode is shown in fig. 6.
In some embodiments of the present invention, a combination of lateral merging readout and longitudinal merging readout may be implemented on a pixel array capable of using a phase focusing function, and fig. 7 is a schematic diagram of an image sensor layout structure in another embodiment of the present invention, as shown in fig. 7, since the colors of a focusing photosensitive pixel unit on a focusing pixel column and a non-focusing photosensitive pixel unit on a separate row are inconsistent, in order to perform better optimal control on the focusing pixel column, a row selection control line includes a first group of row selection control lines and a second group of selection control lines; the pixel array comprises focusing pixel rows (row 2 in fig. 7) provided with focusing photosensitive pixel units, and a first group of row selection control lines rs are used for controlling non-focusing photosensitive pixel units in the focusing pixel rows row2 to read out pixel signals; the second group of row selection control lines rsp are used for controlling the focusing photosensitive pixel units in the focusing pixel row2 to read out pixel signals;
in the normal working mode, the first group of row selection control lines rs are used for controlling the non-focusing photosensitive pixel units to read out pixel signals, and the second group of row selection control lines rsp are used for controlling the focusing photosensitive pixel units to read out pixel signals;
In the combined readout mode, the readout of the pixel signals is not performed on the focused pixel row2, wherein four pixel units of the kth row, the mth+2column, the kth+2row, the mth Column, and the kth+2row are simultaneously received a row selection control signal, for example, four pixel units of row1, column3, row3, column1, and row3 in fig. 7 are simultaneously received a row selection control signal to perform the readout of the pixel signals, and adjacent pixel units located in the same pixel row and spaced by one pixel unit are combined and read out through the same Column line, and adjacent pixel units located in the same pixel Column and spaced by one pixel unit are both read out through different Column lines; wherein, K and M are positive integers, namely, row1 Column1 and row1 Column3 are read out by the same Column line, row3 Column1 and row3 Column3 are read out by the same Column line, row1 Column1 and row3 Column1 are read out by different Column lines, row1 Column3 and row3 Column3 are read out by different Column lines.
The invention receives row selection signals at the same time for focusing photosensitive pixel units in the focusing pixel columns and non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows, but outputs pixel signals through different column lines, and a device which passes through a time sequence gating column line is arranged at an ADC (analog to digital converter), so that the effect is equivalent to that of arranging an equivalent switch, and in the subsequent image processing, the pixel units with closed reading channels are processed into the same display as the pixel units with open reading channels.
In the invention, the N-th row of pixel lines and the N-2-th row of pixel lines of the focusing photosensitive pixel unit pair are symmetrically arranged, wherein N is a positive integer greater than or equal to 2. In the embodiment of the present invention, as shown in fig. 7, the layout is more matched by selecting the distribution of the control lines (rs and rsp) in the 0 th Row (Row 0) and the 2 nd Row (Row 2) symmetrically. As another embodiment, the Row selection control lines for selecting the 2 nd Row (Row 2) pixel Row and the 4 th Row (Row 4) pixel Row may be symmetrically arranged.
In a preferred embodiment, the N-2 th row of pixels is provided with a first set of row selection control lines and a second set of row selection control lines, respectively; in the N-2 row pixel row, the first group of row selection control lines are used for controlling pixel units in the same column as the non-focus photosensitive pixel units in the N row pixel row to read out pixel signals, and the second group of row selection control lines are used for controlling pixel units in the same column as the focus photosensitive pixel units in the N row pixel row to read out pixel signals. And two groups of row selection control lines are arranged on the pixel rows without focusing photosensitive pixel units, but when the actual signal is controlled, only one group of row selection control lines are used for controlling and selecting the selected pixel rows to read out the pixel signals, and the other group of row selection control lines are suspended.
Specifically, the first group of row selection control corresponds to a control signal, specifically, the first control signal dd_rs is transmitted to the first group of row selection control lines rs <0> and rs <2> corresponding to the 0 th row and the 2 nd row of pixels, the second control signal dd_rsp <0> is transmitted to the second group of row selection control lines rsp <0> and the third control signal dd_rsp <2> corresponding to the 0 th row of pixels, and the third control signal dd_rsp <2> is transmitted to the second group of row selection control lines rsp <2> corresponding to the 2 nd row of pixels.
Specifically, the first group of row selection control lines output a first control signal to the nth row of pixel rows and the N-2 th row of pixel rows to respectively control the unfocused photosensitive pixel units in the nth row of pixel rows and the N-2 th row of pixel rows to read out pixel signals;
the second group of row selection control lines output a second control signal to the N-2 row of pixel rows to control pixel units in the N-2 row of pixel rows, which are positioned in the same column as the focusing photosensitive pixel units in the N row of pixel rows, to read out pixel signals;
the second group of row selection control lines output a third control signal to the nth row of pixel rows to control the focusing photosensitive pixel units in the nth row of pixel rows to read out pixel signals.
More specifically, as shown in fig. 7, in the present invention, a first group of row selection control lines rs receives a first control signal dd_rs, and sequentially controls and selects a 0 th row of pixel row to be read and a 2 nd row of pixel row to read the pixel signals according to the first control signal dd_rs; the second group of Row selection control lines rsp receives a second control signal dd_rsp <0>, and controls and selects non-focusing photosensitive pixel units (Row 0, column 3) which are positioned in the same Column as the focusing photosensitive pixel units in the 2 nd Row pixel Row in the 0 th Row pixel Row to be read according to the second control signal dd_rsp <0> to read pixel signals; the second group of Row selection control lines rsp receives the third control signal dd_rsp <1>, and controls and selects the focusing photosensitive pixel units (Row 2, column 3) in the 2 nd Row of pixels to be read according to the third control signal dd_rsp <1> to read out the pixel signals.
As another preferred embodiment, two sets of row selection control signals are set for all pixel rows, that is, a first set of row selection control lines rs <0:7> and a second set of row selection control lines rsp <0:7> are adopted for the pixel units of each row to individually control two different color blocks in the same pixel row according to the mode requirement.
Specifically, in the normal operation mode, the signal readout process of the image sensing is as follows:
for the N-2 th row of pixels (non-focusing row of pixels): the N-2 row of pixel rows is correspondingly provided with a first group of row selection control lines and a second group of row selection control lines; in the N-2 row pixel row, the first group of row selection control lines are used for controlling pixel units in the same column as the non-focus photosensitive pixel units in the N row pixel row to read out pixel signals, and the second group of row selection control lines are used for controlling pixel units in the same column as the focus photosensitive pixel units in the N row pixel row to read out pixel signals. More specifically, in the embodiment of the present invention, in the 0 th Row of pixels (Row 0), rs <0> in the first group of Row selection control lines controls the non-focusing photosensitive pixel units (pixel units corresponding to column1, column2, column4, column5, column6, column 8) to read out pixel signals based on the first control signal dd_rs, and rsp <0> in the second group of Row selection control lines controls the focusing photosensitive pixel units (pixel units corresponding to Row0/column3 and pixel units corresponding to Row0/column 7) to read out pixel signals based on the second control signal dd_rsp <0 >.
For the nth row of pixels (focusing pixel row): the N-th row of pixel rows is correspondingly provided with a first group of row selection control lines and a second group of row selection control lines; the first group of row selection control lines are used for controlling the non-focusing photosensitive pixel units in the focusing pixel rows to read out pixel signals, and the second group of row selection control lines are used for controlling the focusing photosensitive pixel units in the focusing pixel rows to read out pixel signals. More specifically, in the embodiment of the present invention, the focusing pixel Row2 (Row 2), based on the first control signal, the first group of Row selection control lines rs <2> control the non-focusing photosensitive pixel units (pixel units corresponding to column1, column2, column4, column5, column6, column 8) to read out pixel signals, and the second group of Row selection control lines rsp <2> control the focusing photosensitive pixel units (pixel units corresponding to Row2/column3 and pixel units corresponding to Row2/column 7) to read out pixel signals.
For other rows (N-1 row, n+1 row, etc.) of pixels: and controlling all pixel units in the corresponding pixel row to read out pixel signals through the first group of row selection control lines or the second group of row selection control lines. More specifically, in the embodiment of the present invention, the 1 st Row of pixel rows (Row 1), based on the first control signal, the first group of Row selection control lines rs <1> control all the pixel units (pixel units corresponding to column1-column 8) to read out the pixel signals.
In the mode of the lateral-longitudinal combined readout, the signal readout process of the image sensing is:
the focusing pixel row does not read out the pixel signals, and the adjacent pixel units which are positioned in the same pixel row and are separated by one pixel unit are read out through the same column line, and the adjacent pixel units which are positioned in the same pixel column and are separated by one pixel unit are read out through different column lines; that is, the four pixel units (e.g., row1/column1, row1/column3, row3/column 1) of the other pixel rows except for the focus pixel row (row 2) that does not operate receive the row selection control signal at the same time, but the pixel unit corresponding to row1/column1 and the pixel unit corresponding to row1/column3 are read out by merging the second column line (Bitline 1_0), and the pixel unit corresponding to row3/column3 and the pixel unit corresponding to row3/column1 are read out by merging the first column line (Bitline 3_1).
The time sequence control during the transverse and longitudinal combination readout control is shown in fig. 8 and 9, and it is to be noted that the dashed lines in fig. 8 and 9 represent that the corresponding signals in the time sequence can be low level or high level, and the technical scheme of the scheme can be realized. Since the focusing pixel PDAF in the lateral binning is different from the color block of the pixel unit to be combined, the Row2 (Row 2) needs to be controlled, and the readout binning cannot be effectively combined laterally, so that the signals of the Row2 (Row 2) need to be all turned off. In the merge read mode, the signals of Row2 (Row 2) need to be all turned off. The two groups of row selection control lines are used for respectively controlling the focusing photosensitive pixel units and the non-focusing photosensitive pixel units, so that the focusing pixel rows cannot be opened when the pixel array is read out in a horizontal merging mode, and correspondingly, adjacent pixel units of other pixel rows and at intervals of one pixel unit are read out in a merging mode through the same column line, and two adjacent pixel units of the same pixel column and at intervals of one pixel unit are read out through different column lines, the pixel value data of the obtained pixel units are changed into 1/4 of the original value, and the time for processing all data in a corresponding mode is changed into 1/4 of the original value. Thus, the frame rate of image processing is greatly improved, so that more slow actions can be captured.
In the invention, the focusing photosensitive pixel unit occupies 3% of the pixel array, so that the pixels are not greatly reduced, namely, the pixel units corresponding to the phase focusing PDAF are fewer when the image information is read out normally, and the phase information can be obtained; when the binding is read out in a transverse merging mode, phase information cannot be obtained, and one row of pixel units are fewer when image information is obtained, but the frame rate can be greatly improved.
Embodiment two:
the invention also provides a signal reading control method of the image sensor, which at least comprises the following steps:
controlling the pixel array to enter a focusing mode;
receiving a control signal, and controlling pixel units of rows to be read to read pixel signals according to the control signal;
the row selection control line is used for controlling a first area of one focusing photosensitive pixel unit in the focusing pixel column to read out pixel signals and outputting a first output value through a first column line;
the row selection control line is used for controlling a second area of another focusing photosensitive pixel unit in the focusing pixel column to read out pixel signals and outputting a second output value through the first column line; the second area and the first area form a complementary area of the focusing photosensitive pixel unit;
And performing focusing control according to the first output value and the second output value.
In this embodiment, since the image sensor is described in detail in the first embodiment, a detailed description is omitted in this embodiment.
In the reading control method of the image sensor, during a focusing mode, focusing photosensitive pixel units in a pixel focusing column are controlled by simultaneously receiving row selection control signals, and focusing control is respectively carried out through the output first output value and the output second output value.
As a preferred embodiment of the present invention, performing focus control based on the first output value and the second output value includes:
generating a first phase value from the first output value;
generating a second phase value from the second output value;
and performing focusing control according to the first phase value and the second phase value.
After the first output value and the second output value are obtained, a first phase value and a second phase value can be calculated and generated, phase difference information of the first phase value and the second phase value can be converted into focusing distance information, and phase focusing is achieved by adjusting the position of the lens according to focusing distance information, so that phase focusing detection is simpler to achieve.
As a further definition of an embodiment of the present invention, the method further comprises:
Controlling the pixel array to enter a normal working mode, and sequentially outputting row selection control signals to each pixel row by a row selection control line so as to read out the pixel rows in the pixel array row by row;
controlling the pixel array to enter a merging read-out mode, and simultaneously receiving a row selection control signal by every two rows of pixel rows of the odd-numbered rows at intervals; in the pixel column provided with the focusing photosensitive pixel units, controlling the opening of a channel read out by the focusing photosensitive pixel units through a first column line, and closing a channel read out by the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows through a second column line; or the channel read out by the first column line of the focusing photosensitive pixel unit is closed, and the channel read out by the second column line of the non-focusing photosensitive pixel unit which is separated from the focusing photosensitive pixel unit by odd rows is opened.
In the embodiment of the invention, the reading is performed through the two column lines, so that effective reading can be performed no matter whether the focusing photosensitive pixel unit is closed or not during longitudinal reading.
Considering the existence of focusing photosensitive pixel units, when transverse readout control or transverse and longitudinal readout control is carried out, the row selection control lines are provided with two groups of row selection control lines, wherein the first group of row selection control lines are used for controlling pixel units in the N-2 row pixel rows, which are positioned in the same column with non-focusing photosensitive pixel units in the N row pixel rows, to read pixel signals; the second group of row selection control lines are used for controlling pixel units in the same column as the focusing photosensitive pixel units in the N-2 row pixel rows to read out pixel signals.
As a preferred implementation manner of the embodiment of the present invention, in the combined readout mode, the readout channel of the pixel signal of the focused pixel row is controlled to be closed, and four pixel units of the mth column of the kth row, the mth+2th column of the kth row, the mth column of the kth+2th row, and the mth+2th column of the kth+2th row are controlled to simultaneously receive the row selection control signal, and among the four pixel units, adjacent pixel units located in the same pixel row and spaced from one pixel unit are combined and read out through the same column line, and adjacent pixel units located in the same pixel column and spaced from one pixel unit are both read out through the first column line and the second column line, respectively.
When the invention enters the merging read-out mode, because the color blocks of the focusing pixel PDAF and the pixel units needing to be merged are different, the read-out channels of the pixel signals of the focusing pixel row are required to be controlled to be closed, the adjacent pixel units which are positioned in the same pixel row and are separated by one pixel unit are merged and read out through the same column line, and the adjacent pixel units which are positioned in the same pixel column and are separated by one pixel unit are read out through different column lines; when the data are read out through the first combination of the same column, one column line is output, and the other column line is idle, so that the number of columns is combined, the data are halved in the process of reading out the data in the column direction, the frame rate is improved, and the data are halved when the data are longitudinally combined, and the further improvement of the frame rate is realized; the whole realization effect is: the data output at the same time is the same as before the non-integrated reading, but the total data amount is 1/4 of the original data amount, so the time for processing all the data for the corresponding processing is also 1/4 of the original data amount. Thus, the frame rate of image processing is greatly improved, so that more slow actions can be captured.
In summary, the image sensor of the invention realizes the control of selecting the pixel units of the row to be read to respectively and simultaneously read out the pixel signals through the pixel array with optimized layout and the control signals received simultaneously; the pixel unit layout in the pixel array can realize a larger pixel range and a photosensitive area, and the four pixel points included in the pixel unit adopt the same control signal, so that the pixel processing speed can be greatly improved. Meanwhile, the Bayer array arrangement mode is adopted, so that the phase focusing performance can be greatly improved. In addition, the frame rate of pixel processing can be further improved by adopting a vertical merging read-out technology. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (15)
1. An image sensor, the image sensor comprising:
a pixel array including a plurality of pixel units arranged in a bayer array, each of the pixel units including pixel points laid out in a 2×2 structure and having the same color; the pixel array comprises a focusing pixel column, wherein part of blue pixels or red pixels in the focusing pixel column are replaced by green pixels to form a focusing photosensitive pixel unit, and the focusing photosensitive pixel unit is partially shielded to acquire an output value of the focusing photosensitive pixel unit and perform focusing control based on the output value;
a row selection control line for receiving a row selection control signal and controlling and selecting pixel units of rows to be read to read out pixel signals according to the row selection control signal;
the image sensor comprises a normal working mode and a combined reading mode; in the normal working mode, pixel rows in the pixel array are read out row by row; in the combined readout mode, at least two rows of pixel rows spaced by odd rows receive row selection control signals at the same time, and in the focusing pixel columns, focusing photosensitive pixel units simultaneously receiving row selection control signals and non-focusing photosensitive pixel units spaced by odd rows correspond to one readout channel respectively, wherein one readout channel is opened, and the other readout channel is closed.
2. The image sensor of claim 1, further comprising:
a column line for reading out pixel signals of pixel units of a row to be read, the column line including a first column line and a second column line; in the focusing pixel column, the focusing photosensitive pixel units are read out through a first column line, and the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows are read out through a second column line.
3. The image sensor of claim 1, wherein each two of the focusing photosensitive pixel units located in the same pixel row form a focusing photosensitive pixel unit pair, and the blocked areas of the focusing photosensitive pixel units in each focusing photosensitive pixel unit pair are complementary to each other, so as to respectively obtain an output value of each focusing photosensitive pixel unit in the focusing photosensitive pixel unit pair, and focus control is performed based on the output values.
4. The image sensor of claim 3 wherein two of said pair of focus sensitive pixel cells are spaced apart by an odd number of columns.
5. The image sensor of claim 1, wherein the focus sensitive pixel cells occupy 3% of the pixel array.
6. The image sensor of claim 1, wherein in each pixel column, one of two pixel cells receiving a row selection control signal is read out through the first column line, and the other pixel cell is read out through the second column line.
7. The image sensor of claim 1, wherein the row select control lines comprise a first set of row select control lines and a second set of select control lines;
the pixel array comprises focusing pixel rows provided with the focusing photosensitive pixel units, and the first group of row selection control lines are used for controlling non-focusing photosensitive pixel units in the focusing pixel rows to read out pixel signals; the second group of row selection control lines are used for controlling the focusing photosensitive pixel units in the focusing pixel rows to read out pixel signals;
in the normal working mode, the first group of row selection control lines are used for controlling the non-focusing photosensitive pixel units to read out pixel signals, and the second group of row selection control lines are used for controlling the focusing photosensitive pixel units to read out pixel signals;
in the merging readout mode, the focusing pixel row does not perform readout of pixel signals, wherein four pixel units of an mth column of a kth row, an mth+2th column of a kth row, an mth column of a kth+2th row, and an mth+2th column of a kth+2th row receive row selection control signals at the same time, and adjacent pixel units located in the same pixel row and spaced from one pixel unit are merged and read out through the same column line, and adjacent pixel units located in the same pixel column and spaced from one pixel unit are read out through different column lines; and K and M are positive integers.
8. The image sensor according to claim 7, wherein an nth row of pixel rows provided with the focus-sensitive pixel units and the row selection control line of an N-2 th row of pixel rows are symmetrically arranged, wherein N is a positive integer of 2 or more.
9. The image sensor of claim 8, wherein the N-2 th row of pixels is provided with the first set of row selection control lines and the second set of row selection control lines, respectively;
in the N-2 th row of pixel rows, the first group of row selection control lines are used for controlling pixel signals to be read out from pixel units which are positioned in the same column as the non-focal sensitive pixel units in the N-th row of pixel rows, and the second group of row selection control lines are used for controlling pixel signals to be read out from pixel units which are positioned in the same column as the focal sensitive pixel units in the N-th row of pixel rows.
10. The image sensor of claim 9, wherein the image sensor further comprises a sensor element,
the first group of row selection control lines output a first control signal to the nth row of pixel rows and the N-2 th row of pixel rows so as to respectively control the non-focusing photosensitive pixel units in the nth row of pixel rows and the N-2 th row of pixel rows to read out pixel signals;
The second group of row selection control lines output a second control signal to the N-2 row of pixel rows to control pixel units in the N-2 row of pixel rows and the pixel units in the same column with the focusing photosensitive pixel units in the N row of pixel rows to read out pixel signals;
the second group of row selection control lines output a third control signal to the nth row of pixel rows to control the focusing photosensitive pixel units in the nth row of pixel rows to read out pixel signals.
11. A signal reading control method of an image sensor, the method comprising at least the steps of:
controlling the pixel array to enter a focusing mode;
receiving a control signal, and controlling pixel units of rows to be read to read pixel signals according to the control signal;
the row selection control line is used for controlling a first area of one focusing photosensitive pixel unit in the focusing pixel column to read out pixel signals and outputting a first output value through a first column line;
the row selection control line is used for controlling a second area of the other focusing photosensitive pixel unit in the focusing pixel column to read out pixel signals and outputting a second output value through the first column line; the second region and the first region form a complementary region of a focusing photosensitive pixel unit;
And performing focusing control according to the first output value and the second output value.
12. The signal reading control method of the image sensor according to claim 11, wherein the performing focus control according to the first output value and the second output value includes:
generating a first phase value from the first output value;
generating a second phase value from the second output value;
and performing focusing control according to the first phase value and the second phase value.
13. The signal read control method of an image sensor according to claim 11, characterized in that the method further comprises:
the pixel array is controlled to enter a normal working mode, and the row selection control lines sequentially output row selection control signals to each pixel row so as to read out the pixel rows in the pixel array row by row;
controlling the pixel array to enter a merging read-out mode, and simultaneously receiving row selection control signals by every two rows of pixel rows of the odd-numbered rows at intervals; in a pixel column provided with a focusing photosensitive pixel unit, controlling a channel read out by the focusing photosensitive pixel unit through a first column line to be opened, and closing a channel read out by a non-focusing photosensitive pixel unit which is separated from the focusing photosensitive pixel unit by an odd number row through a second column line; or alternatively, the process may be performed,
In the pixel column provided with the focusing photosensitive pixel units, the channel read out by the focusing photosensitive pixel units through the first column line is closed, and the channel read out by the non-focusing photosensitive pixel units which are separated from the focusing photosensitive pixel units by odd rows through the second column line is opened.
14. The signal read control method of an image sensor according to claim 11, wherein two sets of row selection control lines are provided, wherein a first set of row selection control lines is used for controlling pixel units in the N-2 th row of pixel rows, which are located in the same column as the non-focusing photosensitive pixel units in the N-th row of pixel rows, to read out pixel signals; the second group of row selection control lines are used for controlling pixel units in the N-2 th row of pixel rows, which are positioned in the same column as the focusing photosensitive pixel units in the N-th row of pixel rows, to read out pixel signals.
15. The signal read control method of an image sensor according to claim 14, wherein in the merged readout mode, a readout channel of a pixel signal of the focused pixel row is controlled to be turned off, four pixel units of an mth column of a kth row, an mth+2th column of a kth row, an mth column of a kth+2th row, and an mth+2th column of a kth+2th row receive a row selection control signal at the same time, and adjacent pixel units located in the same pixel row and spaced apart from one pixel unit are merged and read out through the same column line, and adjacent pixel units located in the same pixel column and spaced apart from one pixel unit are both read out through the first column line and the second column line, respectively.
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| CN117793563B (en) * | 2024-02-23 | 2024-05-28 | 天津希格玛微电子技术有限公司 | Readout device for image sensor |
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