CN111126343B - Driving method and driving device for photoelectric sensor and display device - Google Patents
Driving method and driving device for photoelectric sensor and display device Download PDFInfo
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- CN111126343B CN111126343B CN201911420094.7A CN201911420094A CN111126343B CN 111126343 B CN111126343 B CN 111126343B CN 201911420094 A CN201911420094 A CN 201911420094A CN 111126343 B CN111126343 B CN 111126343B
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
- G06V40/1318—Sensors therefor using electro-optical elements or layers, e.g. electroluminescent sensing
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
Abstract
The embodiment of the invention provides a driving method and a driving device for a photoelectric sensor and a display device, relates to the technical field of image sensing, and aims to improve the exposure time of the photoelectric sensor and ensure the quality of images acquired by the photoelectric sensor. The driving method comprises the following steps: in the exposure time interval, the reset transistor and the reading transistor of the light sensing circuit are cut off, and in the reset time interval, the reset transistor is turned on; in the first and second reading periods, the reading transistor is turned on. In the second reading period, the reset transistor is turned off. And the exposure time period of the ith row of light sensing circuits in one working cycle comprises the first reading time period, the second reading time period and the reset time period of each row of light sensing circuits in one working cycle in the rest N-1 rows of light sensing circuits, N is an integer which is more than or equal to 2, and i is 1, 2, … …, N-1 and N.
Description
[ technical field ] A method for producing a semiconductor device
The present invention relates to the field of image sensing technologies, and in particular, to a driving method and a driving apparatus for a photoelectric sensor, and a display apparatus.
[ background of the invention ]
In recent years, with the development of display technologies, more and more display devices are used for protecting user privacy by fingerprint recognition. When a user operates the display device with the fingerprint identification function, the authority verification can be realized only by touching the display screen with a finger, and the operation is simple.
Specifically, the fingerprint identification process includes the acquisition of a fingerprint image to be verified and the comparison process with a standard image. Therefore, in order to ensure the accuracy of fingerprint identification, the quality of the acquired fingerprint image needs to be ensured.
[ summary of the invention ]
In view of this, embodiments of the present invention provide a driving method and a driving apparatus for a photosensor, and a display apparatus, so as to improve an exposure duration of the photosensor and ensure quality of an image acquired by the photosensor.
In one aspect, an embodiment of the present invention provides a driving method for a photosensor, where the photosensor includes N rows of light sensing circuit rows, and each light sensing circuit row includes a plurality of light sensing circuits; the light sensing circuit comprises a photodiode, a reset transistor and a reading transistor;
each line of the N lines of the light sensing circuits periodically works in a plurality of working cycles, each working cycle comprises an exposure time interval, a first reading time interval, a reset time interval and a second reading time interval which occur in sequence, and the working cycles corresponding to any two lines of the light sensing circuits are staggered;
the driving method includes:
providing a cut-off signal to a control electrode of the reset transistor and a control electrode of the reading transistor of the light sensing circuit of the ith row in the exposure time period corresponding to the light sensing circuit of the ith row;
providing a conducting signal to a control electrode of the reset transistor of the light sensing circuit of the ith row in the reset time period corresponding to the light sensing circuit of the ith row;
providing a conducting signal to a control electrode of the reading transistor of the light sensing circuit of the ith row in the first reading time period corresponding to the light sensing circuit of the ith row;
providing a turn-on signal to a control electrode of the reading transistor of the light sensing circuit of the ith row and providing a turn-off signal to a control electrode of the reset transistor of the light sensing circuit of the ith row in the second reading time period corresponding to the light sensing circuit of the ith row;
the exposure time period of the light sensing circuit in the ith row in one working cycle comprises a first reading time period, a second reading time period and a reset time period of each row of the light sensing circuits in the rest N-1 rows in one working cycle; wherein N is an integer of 2 or more, and i is 1, 2, … …, N-1, N.
In another aspect, an embodiment of the present invention provides a driving apparatus for a photosensor, where the photosensor includes N rows of light sensing circuits, and each of the light sensing circuits includes a plurality of light sensing circuits; the light sensing circuit comprises a photodiode, a reset transistor and a reading transistor;
each line of the N lines of the light sensing circuits periodically works in a plurality of working cycles, each working cycle comprises an exposure time interval, a first reading time interval, a reset time interval and a second reading time interval which occur in sequence, and the working cycles corresponding to any two lines of the light sensing circuits are staggered;
the driving device includes:
the reset control module is used for providing a cut-off signal for the control electrode of the reset transistor of the light sensing circuit on the ith row in the exposure time period and the second reading time period corresponding to the light sensing circuit on the ith row; and providing a conducting signal to a control electrode of the reset transistor of the light sensing circuit of the ith row in the reset time period corresponding to the light sensing circuit of the ith row;
the reading control module is used for providing a cut-off signal for a control electrode of the reading transistor of the light sensing circuit on the ith row in the exposure time period corresponding to the light sensing circuit on the ith row; and providing a conducting signal to a control electrode of the reading transistor of the light sensing circuit of the ith row in the first reading time period and the second reading time period corresponding to the light sensing circuit of the ith row;
the exposure time period of the light sensing circuit in the ith row in one working cycle comprises a first reading time period, a second reading time period and a reset time period of each row of the light sensing circuits in the rest N-1 rows in one working cycle; wherein N is an integer of 2 or more, and i is 1, 2, … …, N-1, N.
In another aspect, an embodiment of the present invention provides a display device, which includes the driving device.
According to the driving method, the driving device and the display device for the photoelectric sensor provided by the embodiment of the invention, the first reading time period, the second reading time period and the reset time period of each line of light sensing circuit in the rest N-1 lines of light sensing circuits except the ith line of light sensing circuit in one working cycle are included in the exposure time period of the ith line of light sensing circuit in one working cycle, so that the light integration time period of each line of light sensing circuit in one working cycle can be prolonged, and the quality of a formed fingerprint image is improved. And the proportion of the exposure time period of each light sensing circuit in the working period can be improved, the working period is prevented from being excessively prolonged on the basis of improving the exposure time period, and the speed of fingerprint identification is ensured.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a photosensor;
FIG. 2 is a diagram of a light sensing circuit of FIG. 1;
fig. 3 is a timing chart of driving applied to the photosensor shown in fig. 1 according to the prior art;
fig. 4 is a driving timing chart applied to the photosensor shown in fig. 1 according to an embodiment of the present invention;
FIG. 5 is a timing diagram illustrating an operation of a display panel using fingerprint recognition technology;
FIG. 6 is a timing diagram illustrating another driving method applied to the photo sensor shown in FIG. 1 according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a driving apparatus for a photosensor according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a display device according to an embodiment of the invention.
[ detailed description ] embodiments
For better understanding of the technical solutions of the present invention, the following detailed descriptions of the embodiments of the present invention are provided with reference to the accompanying drawings.
It should be understood that the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
It should be understood that although the terms first, second, etc. may be employed to describe the read periods in the embodiments of the present invention, the read periods should not be limited to these terms. These terms are only used to distinguish the various read periods from each other. For example, the first reading period may also be referred to as a second reading period, and similarly, the second reading period may also be referred to as a first reading period, without departing from the scope of embodiments of the present invention.
Before describing the embodiments of the present invention in detail, the principles of fingerprint recognition and the problems of the prior art related to the embodiments of the present invention will be described.
When an image sensor is used for collecting a fingerprint image to be verified, a plurality of lines of sensing circuits included by the image sensor are started to work line by line according to different addresses. In the operation process of each sensing circuit, the image sensor applying the optical fingerprint identification technology mainly utilizes the reflection principle of light. When light irradiates the fingerprint, the fingerprint reflects the light, and the reflected light irradiates the photoelectric sensor to generate photoelectric charge. The amount of photo-charges is proportional to the intensity of illumination and the light integration time. Because the reflected light intensity at the positions of the valleys and ridges of the fingerprint is different, the quantity of the photo-charges generated in the photo-sensors corresponding to the different positions of the valleys and ridges of the fingerprint is also different. According to the difference of the quantity of the photoelectric charges at the positions of the valleys and the ridges of the fingerprint, the fingerprint image to be verified formed by the set of a plurality of image points with different brightness degrees in the fingerprint identification area can be obtained.
Specifically, as shown in fig. 1, fig. 1 is a schematic diagram of a photoelectric sensor, which includes a plurality of light sensing circuits 10 arranged in an array, a reset control signal line reset, a read control signal line read, a fixed voltage signal line VDD, and an output signal line Vout. As shown in fig. 2, fig. 2 is a schematic diagram of a light sensing circuit in fig. 1, and the light sensing circuit includes a reset transistor T1, a follower transistor T2, a read transistor T3 and a photodiode D. A control electrode of the reset transistor T1 is electrically connected to a reset control signal line reset, a first electrode of the reset transistor T1 is electrically connected to a fixed voltage signal line VDD, and a second electrode of the reset transistor T1 is electrically connected to a control electrode of the follower transistor T2 and a first electrode of the photodiode D. The first pole of the follower transistor T2 is also electrically connected to the fixed voltage signal line VDD. The second pole of the follower transistor T2 is electrically connected to the first pole of the read transistor T3. The control electrode of the read transistor T3 is electrically connected to the read control signal line read shown in fig. 1. The second pole of the read transistor T3 is electrically connected to the output signal line Vout. The second pole of the photodiode D is connected to the reference voltage terminal Vbias.
As shown in fig. 3, fig. 3 is a driving timing diagram applied to the photosensor shown in fig. 1 in the prior art, in which four rows of photosensor circuits are taken as an illustration, rst _ i 'is a signal diagram provided by a reset control signal line reset connected to an ith row of photosensor circuits, and read _ i' is a signal diagram provided by a read control signal line read connected to the ith row of photosensor circuits, and taking a first row of photosensor circuits as an example, the operation process of the row of photosensor circuits includes a reset period t1 ', a first read period t 21', a second read period t22 'and an exposure period t 3'.
During the reset period t 1': the reset transistor T1 is controlled to be turned on by a signal supplied from the reset control signal line reset, and the voltage on the fixed voltage signal line VDD is transmitted to the Q node through the reset transistor T1, so that the potential of the Q node is reset.
During the first reading period t 21': the reset transistor T1 is turned off by a signal supplied from the reset control signal line reset, and the read transistor T3 is turned on by a signal supplied from the read control signal line read. The follower transistor T2 generates a leakage current under the control of the Q node and transmits the leakage current to the output signal line Vout through the read transistor T3, and the output signal line Vout outputs a signal value V1'.
The potential at the Q node decreases as the exposure time increases.
During the second reading period t 22': the reset transistor T1 is turned off by a signal supplied from the reset control signal line reset, and the read transistor T3 is turned on by a signal supplied from the read control signal line read. The follower transistor T2 generates a leakage current under the control of the Q node and transmits the leakage current to the output signal line Vout through the read transistor T3, and the output signal line Vout outputs a signal value V2'.
In the fingerprint detection, the integral intensity of the optical charge in the photodiode D is different at different positions of the fingerprint identification area, and the magnitude of the integral intensity of the optical charge determines the amount of change in the potential of the Q node. Therefore, after obtaining V1 'and V2', the two can be processed subsequently, for example, the difference between the two can be made, and the difference between the two can reflect the illumination intensity received by the photodiode D.
In the above process, in the case where the intensity of the illumination light provided by the light source is constant, if the duration of the exposure period t3 ' is short, the amount of photo-charges generated by the photodiode D is small, which is reflected on the output signal, i.e., the difference between V1 ' and V2 ' is small. The quality of the fingerprint image to be authenticated formed from the difference will also be affected.
Based on the driving manner shown in fig. 3, in the working period T ' of each row of the light sensing circuits, taking the first row of the light sensing circuits as an example, in two adjacent working periods, there is a period T4 ' between the second reading period T22 ' of the previous working period and the reset period of the next working period. Although the fingerprint identification light source may still illuminate the fingerprint during this period, and the fingerprint still reflects light to the light sensing circuit, this portion of the reflected light is not reflected during the aforementioned exposure period participating in light integration. That is, there is a period t 4' during which light is not integrated in the operating period of the light sensing circuit, except for the reset period and the read period. The existence of the time period t 4' not only compresses the time of light integration in one duty cycle, affecting the quality of the formed image, but also unnecessarily prolongs the duty cycle of the light sensing circuit, reducing the speed of fingerprint recognition.
Based on the above problems in the prior art, embodiments of the present invention provide a driving method for a photo sensor, as shown in fig. 1 and fig. 2, the photo sensor includes N rows of photo sensing circuit rows 1, and the photo sensing circuit row 1 includes a plurality of photo sensing circuits 10 as shown in fig. 2; the light sensing circuit 10 includes a photodiode D, a reset transistor T1, and a read transistor T3.
As shown in fig. 4, fig. 4 is a driving timing diagram for the photoelectric sensor according to the embodiment of the present invention, in which four rows of the photosensitive circuits are taken as an illustration, rst _ i is a signal illustration provided by a reset control signal line reset connected to the ith row of the photosensitive circuits, read _ i is a signal illustration provided by a read control signal line read connected to the ith row of the photosensitive circuits, the duty cycle of each row of the photosensitive circuits includes exposure periods, a first read period, a reset period, and a second read period, which occur sequentially, and the duty cycles corresponding to any two rows of the photosensitive circuits are staggered. Taking the driving timing of the first row of photo sensing circuits as shown in fig. 4 as an example, the jth duty cycle T _1j of the row of photo sensing circuits includes an exposure period T1_1, a first reading period T21_1, a reset period T3_1 and a second reading period T22_1 which occur sequentially.
As shown in fig. 2 and 4, the driving method includes:
in the reset period T3_ i corresponding to the ith row of light sensing circuits, a turn-on signal is provided to the control electrode of the reset transistor T1 of the ith row of light sensing circuits to reset the node Q.
In the exposure period T1 — i corresponding to the ith row of photo sensing circuits, off signals are supplied to the control electrode of the reset transistor T1 and the control electrode of the read transistor T3 of the ith row of photo sensing circuits. In this period, the photodiode D generates a leakage current flowing from the Q node to the reference voltage terminal Vbias under illumination, and the potential at the Q node is lowered. The potential at the Q node decreases as the exposure time increases.
In a first reading time period T21_ i and a second reading time period T22_ i corresponding to the light sensing circuit in the ith row, a turn-on signal is provided to the control electrode of the reading transistor T3 of the light sensing circuit in the ith row, the follower transistor T2 generates a leakage current under the control of the Q node and transmits the leakage current to the output signal line Vout through the reading transistor T3, the output signal line Vout outputs first data V1 in the first reading time period T21_ i, and second data V2 in the second reading time period. Also, in the second reading period T22 — i, the off signal is also supplied to the control electrode of the reset transistor T1 of the ith row of light sensing circuits.
After obtaining V1 and V2, image data acquired by the light sensing circuit can be obtained from both.
Moreover, as shown in fig. 4, in the embodiment of the present invention, the exposure period of the ith row of photo sensing circuits in one duty cycle includes the first reading period, the second reading period and the reset period of each row of photo sensing circuits in one duty cycle in the remaining N-1 rows of photo sensing circuits; wherein N is an integer of 2 or more, and i is 1, 2, … …, N-1, N.
In the driving method provided by the embodiment of the invention, the first reading time, the second reading time and the reset time of each row of light sensing circuits in the N rows of light sensing circuits in the rest N-1 rows of light sensing circuits except the ith row of light sensing circuits in one working cycle are included in the exposure time of the ith row of light sensing circuits in one working cycle, and compared with the driving method shown in fig. 3, the time for performing the second reading on the rest rows can also be used for performing light integration on the light sensing circuits of the corresponding rows. That is, the embodiment of the present invention can shorten the time of the wasted time period t 4' in fig. 3, and extend the time length of light integration of each row of the photo sensing circuits in one duty cycle, thereby ensuring the quality of the formed fingerprint image.
Further, taking the duration of the reset period, the first reading period and the second reading period as a, and the driving timing of the 4 rows of photo sensing circuits shown in fig. 3 and 4 as an example, in fig. 3, the duration of the exposure period t3 'of one row of photo sensing circuits is equal to the sum of the durations of the first reading periods t 21' of the remaining three rows of photo sensing circuits. That is, the duration of the exposure period t 3' for one row of the photo sensing circuits is 3A. The duration of the duty cycle T ' of one row of the light sensing circuits is the sum of the durations of the reset period, the first reading period, the second reading period, the exposure period, and the waste period T4 ', i.e., the duty cycle T ' of one row of the light sensing circuits is 9A. The duty ratio of the exposure period T3 'in the duty cycle T' is 0.333.
In fig. 4, the duration of the exposure period of one row of the photo sensing circuits is equal to the sum of the durations of the first reading period, the second reading period and the reset period of each row of the photo sensing circuits in one working cycle in the remaining three rows of the photo sensing circuits. That is, the duration of the exposure period of one row of the light sensing circuit is 9A. The duration of the duty cycle of one row of the photo sensing circuits is the sum of the durations of the exposure period, the first reading period, the reset period and the second reading period, i.e., the duty cycle of one row of the photo sensing circuits is 12A. The duty ratio of the exposure period in the duty cycle is increased from 0.333 to 0.75 in fig. 3. Namely, by adopting the driving method provided by the embodiment of the invention, the working period can be prevented from being excessively prolonged on the basis of improving the exposure duration, and the speed of fingerprint identification can be ensured.
In addition, as can be seen from fig. 3, when the driving timing shown in fig. 3 is adopted, the image data of two adjacent frames are completely staggered in time, that is, in the process of cyclically driving the N rows of the light sensing circuits from row 1 to row N, after the light sensing circuit of the last row acquires the image data reflecting the current frame, the image data of the next frame is acquired from the light sensing circuit of the first row. Moreover, since the second reading operation of other lines in the same frame of image display is required in the time period t4 ', if the next reset is performed immediately after the second reading (i.e. the time period t 4') or the next reset is performed after the second reading at a shorter interval than the time period t4 '(i.e. the time period of the time period t 4' is shortened) for any line of photo-sensing circuits, during the line-by-line operation of the multi-line photo-sensing circuits, the reading of the current frame of image display by the i-th line of photo-sensing circuits and the reading of the previous frame of image display by the i + x-th line of photo-sensing circuits may occur simultaneously at a certain moment, where x is a positive integer, and the output on the output signal line Vout will be abnormal.
In the embodiment of the invention, in the process of driving the N rows of photo sensing circuits row by row from row 1 to row N, for each row of photo sensing circuits, the operation period shown in fig. 4 is periodically performed. As can be seen from comparison with FIG. 3, in the manner shown in FIG. 4, the exposure period of the j +1 th duty cycle of the ith row of photo sensing circuits of the embodiment of the invention includes the first reading period, the second reading period and the reset period of the (i + 1) th to nth row of photo sensing circuits in the j th duty cycle, and the first reading period, the second reading period and the reset period of the (1) th to (i-1) th row of photo sensing circuits in the j +1 th duty cycle; wherein, i is 2, … …, N-1, N, j is an integer of more than or equal to 1. Specifically, taking the first and second rows of light sensing circuits as an example, the exposure period T1_1 of the jth duty cycle T _1j of the first row of light sensing circuits includes the first reading period, the second reading period and the reset period of the second to fourth rows of light sensing circuits in the jth-1 th duty cycle. That is to say, when the first line of light sensing circuit carries out light integration to obtain current frame image data, the second line of light sensing circuit carries out reading and resetting operation for obtaining previous frame image data, so set up, when improving the proportion of exposure period in the duty cycle, can also guarantee that at most only one line of light sensing circuit's reading transistor switches on in order to carry out reading operation at any moment, the condition that the reading transistor of multirow light sensing circuit all switches on can not appear, guaranteed the normal output of output signal line Vout, and also can reduce the acquisition time of fingerprint image, be favorable to further improving fingerprint identification speed.
For example, as shown in fig. 4, in the driving method provided in the embodiment of the present invention, the second reading time period of the previous row of the light sensing circuits of two adjacent rows of the light sensing circuits is adjacent to the first reading time period of the next row of the light sensing circuits, so that the reading operations of two adjacent rows can be continuously performed, thereby reducing the total time for acquiring a frame of complete image data and being beneficial to further reducing the acquisition time of the fingerprint image.
Illustratively, when image data is obtained from the first data V1 and the second data V2, embodiments of the present invention provide a plurality of methods, which are separately described below.
The first method is as follows:
as shown in fig. 4, in two adjacent duty cycles corresponding to the ith row of photo sensing circuits: in the second reading period of the previous duty cycle, the reading transistor T3 is turned on, and the second data V2 is acquired through the output signal line Vout. In the first reading period of the latter duty cycle, the reading transistor T3 is turned on, and the first data V1 is acquired through the output signal line. Then, the image data of the ith row of photosensitive circuits in the next working period is obtained according to the first data V1 and the second data V2. For example, taking the row 1 photo sensing circuit shown in fig. 4 as an example, the image data of the row 1 photo sensing circuit in the jth duty cycle T _1j is obtained from the first data V1 and the second data V2 acquired at two times corresponding to the linear shading shown in fig. 4. Wherein the second data V2 is obtained during the second reading time of the j-1 th working cycle T _1(j-1), and the first data V1 is obtained during the first reading time of the j-1 th working cycle T _1 j.
The second method comprises the following steps:
as shown in fig. 4, in the same working cycle corresponding to the ith row of photo sensing circuits: in the first read period, the read transistor T3 is turned on, and first data V1 is acquired through the output signal line Vout. In the second reading period, the reading transistor T3 is turned on, and the second data V2 is acquired through the output signal line Vout. Then, the image data of the ith row of photosensitive circuits in the working period is obtained according to the first data V1 and the second data V2. For example, taking the jth duty cycle T _2j corresponding to the second row of photo sensing circuits shown in fig. 4 as an example, the image data of the second row of photo sensing circuits in the duty cycle is obtained according to the first data V1 and the second data V2 acquired at two times corresponding to the dot hatching shown in fig. 4. Wherein, the first data V1 is obtained in the first reading period in the jth duty cycle T _2j, and the second data V2 is obtained in the second reading period in the jth duty cycle T _2 j.
As can be seen from fig. 4, in the manner of one, the time intervals between the reading of the first data V1 and the reading of the second data V2 are equal in duration of the exposure period in one duty cycle. In the second way, the time interval between reading the first data V1 and the second data V2 is equal to the duration of the reset period in one duty cycle. As described above, with the method provided by the embodiment of the present invention, the exposure period of each row of photo sensing circuits in one duty cycle is extended to include the first reading period, the second reading period and the reset period of each row of photo sensing circuits in one duty cycle in the remaining N-1 rows of photo sensing circuits. Therefore, in one duty cycle, the duration of the exposure period is much longer than the duration of the reset period. Therefore, the time interval between two data reads can be reduced to the duration of the reset period in the second mode compared to the first mode. By shortening the time interval of data acquisition, the processor can have more time to process data, for example, the difference calculation is carried out on the two data, which is beneficial to improving the efficiency of fingerprint identification.
Moreover, for the Display panel adopting the fingerprint identification technology, the fingerprint identification process and the Display process of the Display picture are performed in a time-sharing manner, taking the example that the acquisition of the image data of one frame and the Display of the Display picture of one frame are performed alternately, as shown in fig. 5, fig. 5 is an operation timing chart of the Display panel adopting the fingerprint identification technology, wherein Display _ i represents the Display time of the picture of the ith frame, and the duration of the Display time is T01. During the display time of the ith frame, the scan lines in the display panel can be scanned line by line from the 1 st line to the last line. Finger _ i indicates the time when the i-th frame of fingerprint image data is acquired at the time of fingerprint identification, and the duration thereof is T02. And starting the work of the ith working cycle line by each line of light sensing circuits within the time of obtaining the ith frame of fingerprint image data. Taking a 60Hz display panel as an example, T01 is 16.7 ms. In order to ensure the imaging accuracy, the time for acquiring the fingerprint image data of each frame cannot be designed to be too short, and taking T02 as an example to be also set to be 16.7ms, for each line of photosensitive circuit, a picture display time of 16.6ms is also inserted between two adjacent work cycles shown in fig. 4. In such a case, the time interval between two data reads would be extended to around 33.4ms, in a first manner. While the time for the reset period in one duty cycle shown in fig. 4 is currently typically on the order of less than 100 mus. Therefore, in the display panel integrated with the fingerprint identification technology, the time interval for data acquisition can be greatly shortened by adopting the second mode, and the efficiency of fingerprint identification is ensured.
Optionally, as shown in fig. 4, in the embodiment of the present invention, the first reading time period and the reset time period of the ith row of photo sensing circuits in the same working cycle may be adjacent to each other, so that the first reading and resetting of the ith row of photo sensing circuits in the same working cycle can be continuously performed, and compared with the case shown in fig. 3, the time except for the resetting and reading operations in one working cycle can be used for light integration, so that the time of light integration can be maximally increased, and the quality of the formed fingerprint image can be ensured.
For example, as shown in fig. 6, fig. 6 is another driving timing diagram applied to the photosensor shown in fig. 1, and in a reset period corresponding to the ith row of photo sensing circuits, the embodiment of the present invention may provide a turn-on signal to the control electrode of the reading transistor of the ith row of photo sensing circuits, so that the signals provided to the control electrode of the reading transistor T3 in the first reading period, the reset period and the second reading period which occur continuously are signals for turning on the reading transistor, and the switching times of the signals are reduced, thereby reducing the power consumption of the photosensor. Moreover, since the output signal of the output signal line Vout does not participate in the processing of the image data in the reset period, whether or not the reading transistor T3 is turned on in the reset period does not affect the accuracy of the acquired image data.
An embodiment of the present invention further provides a driving apparatus for a photosensor, where the structure of the photosensor is shown in fig. 1, where the photosensor includes N rows of photosensitive circuits 1, and each photosensitive circuit 1 includes a plurality of photosensitive circuits 10. As shown in fig. 2, the light sensing circuit 10 includes a photodiode D, a reset transistor T1, and a read transistor T3.
The working process of each line of light sensing circuits in the N lines of light sensing circuits is as shown in fig. 4 and 6, each line of light sensing circuits periodically works in a plurality of working cycles, the working cycles include exposure time periods, first reading time periods, reset time periods and second reading time periods which occur in sequence, and the working cycles corresponding to any two lines of light sensing circuits are staggered.
As shown in fig. 7, fig. 7 is a schematic diagram of a driving apparatus for a photosensor according to an embodiment of the present invention, where the driving apparatus includes a reset control module 21 and a read control module 22. The reset control module 21 is configured to provide a cut-off signal to a control electrode of a reset transistor of the ith row of light sensing circuit in an exposure period and a second reading period corresponding to the ith row of light sensing circuit. And providing a conducting signal to a control electrode of a reset transistor of the ith row of light sensing circuits in a reset period corresponding to the ith row of light sensing circuits.
The reading control module 22 is configured to provide a cut-off signal to a control electrode of a reading transistor of the ith row of photo sensing circuits in an exposure period corresponding to the ith row of photo sensing circuits; and providing a conducting signal to a control electrode of a reading transistor of the ith row of light sensing circuits in a first reading time interval and a second reading time interval corresponding to the ith row of light sensing circuits.
Moreover, the exposure time of the ith row of light sensing circuits in one working cycle comprises the first reading time, the second reading time and the reset time of each row of light sensing circuits in the rest N-1 rows of light sensing circuits in one working cycle; wherein N is an integer of 2 or more, and i is 1, 2, … …, N-1, N.
The driving device drives the photoelectric sensor to work according to the driving method, and the specific working process of the driving device is already described in detail in the previous section and is not described herein again.
According to the driving device provided by the embodiment of the invention, through the arrangement of the reset control module 21 and the reading control module 22, the first reading time period, the second reading time period and the reset time period of each row of light sensing circuits in the rest N-1 rows of light sensing circuits except the ith row of light sensing circuits in one working cycle are included in the exposure time period of the ith row of light sensing circuits in one working cycle, so that the light integration time period of each row of light sensing circuits in one working cycle can be prolonged, and the quality of formed fingerprint images is improved. Moreover, the driving device can also improve the proportion of the exposure time period of each light sensing circuit in the working period, and can avoid excessively prolonging the working period on the basis of improving the exposure time length, thereby ensuring the speed of fingerprint identification.
Illustratively, as shown in fig. 7, the driving apparatus further includes an acquisition module 23 and a processing module 24 for obtaining image data. Specifically, the obtaining module 23 and the processing module 24 may operate according to different methods described in the first and second modes provided in the driving method section, and are described below with reference to fig. 4.
The first method is as follows:
the obtaining module 23 is configured to obtain the second data V2 through the reading transistor in the second reading period of the previous working cycle in two adjacent working cycles corresponding to the ith row of photo sensing circuits. And, in the first reading period of the latter duty cycle, the first data V1 is acquired by the reading transistor. The processing module 24 is configured to obtain image data of the ith row of photo sensing circuits in a subsequent working cycle according to the first data and the second data.
The second method comprises the following steps:
the obtaining module 23 is configured to obtain the first data V1 through the reading transistor T3 in the first reading period in the same working cycle corresponding to the ith row of photo sensing circuits. And, in the second reading period, the second data V2 is acquired by the reading transistor T3. The processing module 24 is used for obtaining the image data of the ith row of photosensitive circuits in the working period according to the first data V1 and the second data V2.
It should be noted that the position relationship of each different module in fig. 7 is only an illustration, and in an actual process, the corresponding adjustment may be performed according to different layout requirements, which is not limited in the embodiment of the present invention.
Fig. 8 is a schematic view of a display device provided in an embodiment of the present invention, where the display device includes a display panel 3 and the driving device described above. Wherein the fingerprint identification area 4 in the display area of the display panel 3 can be integrated with a photoelectric sensor as shown in fig. 1, so that the display device has a fingerprint identification function. The driving device can be arranged in a non-display area of the display panel. The specific structure and driving method of the driving device have been described in detail in the above embodiments, and are not described herein again. Of course, the display device shown in fig. 8 is only a schematic illustration, and the display device may be any electronic device with a display function, such as a mobile phone, a tablet computer, a notebook computer, an electronic book, or a television.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (11)
1. A driving method for a photosensor,
the photoelectric sensor comprises N lines of light sensing circuit lines, and each light sensing circuit line comprises a plurality of light sensing circuits; the light sensing circuit comprises a photodiode, a reset transistor and a reading transistor;
each line of the N lines of the light sensing circuits periodically works in a plurality of working cycles, each working cycle comprises an exposure time interval, a first reading time interval, a reset time interval and a second reading time interval which occur in sequence, and the working cycles corresponding to any two lines of the light sensing circuits are staggered;
the driving method includes:
providing a cut-off signal to a control electrode of the reset transistor and a control electrode of the reading transistor of the light sensing circuit of the ith row in the exposure time period corresponding to the light sensing circuit of the ith row;
providing a conducting signal to a control electrode of the reset transistor of the light sensing circuit of the ith row in the reset time period corresponding to the light sensing circuit of the ith row;
providing a conducting signal to a control electrode of the reading transistor of the light sensing circuit of the ith row in the first reading time period corresponding to the light sensing circuit of the ith row;
providing a turn-on signal to a control electrode of the reading transistor of the light sensing circuit of the ith row and providing a turn-off signal to a control electrode of the reset transistor of the light sensing circuit of the ith row in the second reading time period corresponding to the light sensing circuit of the ith row;
the exposure time period of the light sensing circuit in the ith row in one working cycle comprises a first reading time period, a second reading time period and a reset time period of each row of the light sensing circuits in the rest N-1 rows in one working cycle; wherein N is an integer of 2 or more, and i is 1, 2, … …, N-1, N.
2. The driving method according to claim 1,
the first reading time interval and the reset time interval of the light sensing circuit in the ith row are adjacent in the same working cycle.
3. The driving method according to claim 2,
and providing a conducting signal to a control electrode of the reading transistor of the light sensing circuit of the ith row in the reset period corresponding to the light sensing circuit of the ith row.
4. The driving method according to claim 1,
the N lines of light sensing circuits are driven line by line from the 1 st line to the Nth line;
the exposure period of the j +1 th working cycle of the photo sensing circuit in the ith row comprises a first reading period, a second reading period and a reset period of the photo sensing circuit in the jth working cycle in the (i + 1) th to Nth rows, and a first reading period, a second reading period and a reset period of the photo sensing circuit in the j +1 th working cycle in the 1 st to (i-1) th rows;
wherein, i is 2, … …, N-1, N, j is an integer of more than or equal to 1.
5. The driving method according to claim 4,
the second reading time interval of the previous row of the light sensing circuits is adjacent to the first reading time interval of the next row of the light sensing circuits.
6. The driving method according to claim 1, further comprising:
in the same working cycle corresponding to the light sensing circuit in the ith row:
acquiring first data through the read transistor in the first read period;
acquiring second data through the read transistor in the second read period;
and obtaining image data of the light sensing circuit in the ith row in the working period according to the first data and the second data.
7. The driving method according to claim 1, further comprising:
in the ith row, in two corresponding adjacent working cycles of the light sensing circuit:
acquiring second data through the read transistor during the second read period of a previous duty cycle;
acquiring first data through the reading transistor in the first reading period of a subsequent work cycle;
and obtaining image data of the light sensing circuit in the ith row in the next working period according to the first data and the second data.
8. A driving apparatus for a photosensor,
the photoelectric sensor comprises N lines of light sensing circuit lines, and each light sensing circuit line comprises a plurality of light sensing circuits; the light sensing circuit comprises a photodiode, a reset transistor and a reading transistor;
each line of the N lines of the light sensing circuits periodically works in a plurality of working cycles, each working cycle comprises an exposure time interval, a first reading time interval, a reset time interval and a second reading time interval which occur in sequence, and the working cycles corresponding to any two lines of the light sensing circuits are staggered;
the driving device includes:
the reset control module is used for providing a cut-off signal for the control electrode of the reset transistor of the light sensing circuit on the ith row in the exposure time period and the second reading time period corresponding to the light sensing circuit on the ith row; and providing a conducting signal to a control electrode of the reset transistor of the light sensing circuit of the ith row in the reset time period corresponding to the light sensing circuit of the ith row;
the reading control module is used for providing a cut-off signal for a control electrode of the reading transistor of the light sensing circuit on the ith row in the exposure time period corresponding to the light sensing circuit on the ith row; and providing a conducting signal to a control electrode of the reading transistor of the light sensing circuit of the ith row in the first reading time interval and the second reading time interval corresponding to the light sensing circuit of the ith row;
the exposure time period of the light sensing circuit in the ith row in one working cycle comprises a first reading time period, a second reading time period and a reset time period of each row of the light sensing circuits in the rest N-1 rows in one working cycle; wherein N is an integer of 2 or more, and i is 1, 2, … …, N-1, N.
9. The drive device of claim 8, further comprising an acquisition module and a processing module;
the acquisition module is used for acquiring first data through the reading transistor in the first reading time period in the same working cycle corresponding to the light sensing circuit in the ith row; and, in the second read interval, acquiring second data by the read transistor;
the processing module is used for obtaining image data of the ith row of the light sensing circuits in the working period according to the first data and the second data.
10. The drive device of claim 8, further comprising an acquisition module and a processing module;
the obtaining module is used for obtaining second data through the reading transistor in the second reading time period of the previous working cycle in two adjacent working cycles corresponding to the light sensing circuit in the ith row; and, in the first reading period of a subsequent duty cycle, acquiring first data by the reading transistor;
the processing module is used for obtaining image data of the ith row of the light sensing circuit in the following working period according to the first data and the second data.
11. A display device characterized by comprising a drive device according to any one of claims 8 to 10.
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| CN112860077B (en) * | 2021-02-26 | 2023-05-30 | 深圳市华星光电半导体显示技术有限公司 | Signal reading method and device of display panel |
| CN114170990B (en) * | 2021-12-06 | 2022-12-13 | 武汉天马微电子有限公司 | Display panel, ambient light detection driving method thereof and display device |
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| CN110135348A (en) * | 2019-05-15 | 2019-08-16 | 京东方科技集团股份有限公司 | Fingerprint detection circuit and its driving method, array substrate, display device |
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