CN113099144A - Pixel area adjusting system, control method, flat panel detector and camera equipment - Google Patents
Pixel area adjusting system, control method, flat panel detector and camera equipment Download PDFInfo
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- CN113099144A CN113099144A CN202110401419.8A CN202110401419A CN113099144A CN 113099144 A CN113099144 A CN 113099144A CN 202110401419 A CN202110401419 A CN 202110401419A CN 113099144 A CN113099144 A CN 113099144A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/709—Circuitry for control of the power supply
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/71—Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
- H04N25/75—Circuitry for providing, modifying or processing image signals from the pixel array
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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Abstract
The invention discloses a pixel area adjusting system, a control method, a flat panel detector and camera equipment, wherein the pixel area adjusting system comprises: the pixel reading circuit comprises two groups of pixel areas, a power supply circuit, a reading circuit and an adjusting circuit; the power supply circuit is connected with the switching transistors of the two groups of pixel areas to provide initial turn-off voltage for the two groups of pixel areas, wherein the initial turn-off voltage provided for different groups of pixel areas is not equal; the acquisition end of the reading circuit is connected with the photodiodes of the two groups of pixel areas to acquire the gray value of each group of pixel areas; the adjusting circuit is connected between the power supply circuit and the reading circuit so as to receive the gray values from the reading circuit and adjust the turn-off voltage provided by the power supply circuit to the two groups of pixel areas according to the comparison result of the gray values of the two groups of pixel areas. The invention improves the quality and the service life of the product.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to a pixel area adjusting system, a control method, a flat panel detector and camera equipment.
Background
With the development of imaging, display and detection technologies, pixel structures have found a great deal of use in a variety of devices and apparatuses.
A pixel region provided with a pixel structure often employs a Transistor (TFT) as a switching device and a driving device. The transistor is affected by radiation and long-time negative bias work, the threshold voltage of the transistor can drift, and when the transistor is turned off by adopting a preset turn-off voltage, the output current of the transistor is increased, so that an interference signal is generated, the sensitivity of a pixel area is reduced, and the image quality of a product is further reduced.
Disclosure of Invention
In view of the above, the present invention has been made to provide a standby-capable system and a display apparatus that overcome or at least partially solve the above problems.
In a first aspect, a pixel area adjustment system is provided, including:
the pixel reading circuit comprises two groups of pixel areas, a power supply circuit, a reading circuit and an adjusting circuit;
the power supply circuit is connected with the switching transistors of the two groups of pixel areas to provide initial turn-off voltage for the two groups of pixel areas, wherein the initial turn-off voltage provided for different groups of pixel areas is not equal;
the acquisition end of the reading circuit is connected with the photodiodes of the two groups of pixel areas to acquire the gray value of each group of pixel areas;
the adjusting circuit is connected between the power supply circuit and the reading circuit so as to receive the gray values from the reading circuit and adjust the turn-off voltage provided by the power supply circuit to the two groups of pixel areas according to the comparison result of the gray values of the two groups of pixel areas.
Optionally, the two groups of pixel regions include: the device comprises a sample pixel area and a source pixel area, wherein the source pixel area is used for detecting external light; the initial off-voltage provided by the power supply circuit to the sample pixel region is greater than the initial off-voltage provided by the power supply circuit to the source pixel region.
Optionally, a difference between the initial turn-off voltage and the initial threshold voltage of the switching transistor is less than or equal to 0 and greater than or equal to-6V.
Optionally, the adjusting circuit is an FPGA, and the adjusting circuit is connected to the power supply circuit through an IIC interface.
Optionally, the adjusting circuit includes: a comparison unit and an adjustment unit; the input end of the comparison unit is connected with the reading circuit to receive the gray value and calculate the difference value of the gray values of the two groups of pixel areas as the comparison result; the adjusting unit is connected between the comparing unit and the power supply circuit to control the power supply circuit to reduce the turn-off voltage provided to the switching transistor of each group of pixel areas when the absolute value of the difference is greater than a preset threshold; and when the absolute value of the difference value is less than or equal to a preset threshold value, controlling the power supply circuit to maintain the off-state voltage provided for the switching transistor of each group of pixel areas.
Optionally, the power supply circuit includes: a power supply circuit and a gate drive circuit; the output end of the adjusting circuit is connected with the power supply circuit so as to adjust the turn-off voltage output by the power supply circuit; the output end of the power circuit is connected with the switching transistors of the two groups of pixel areas through the grid driving circuit so as to provide the grid driving circuit with a turn-off voltage corresponding to the currently scanned pixel area when the grid driving circuit respectively scans the two groups of pixel areas.
Optionally, the power supply circuit includes: a first power supply, a second power supply, and a data selector; the output end of the adjusting circuit is connected with the first power supply and the second power supply so as to respectively control the first power supply and the second power supply to output turn-off voltages, wherein the turn-off voltages output by different power supplies are not equal; the output ends of the first power supply and the second power supply are connected with the grid driving circuit through the data selector so as to provide the grid driving circuit with a turn-off voltage corresponding to a currently scanned pixel region.
In a second aspect, a method for controlling a pixel area adjustment system, the pixel area adjustment system including two sets of pixel areas, the method comprising:
providing initial turn-off voltages to the switching transistors of the two groups of pixel areas, wherein the initial turn-off voltages provided to the different groups of pixel areas are not equal;
collecting the gray value of each group of pixel areas under the corresponding initial turn-off voltage;
and adjusting the turn-off voltage provided for the switching transistors of the two groups of pixel areas according to the comparison result of the gray values of the two groups of pixel areas.
Optionally, the two groups of pixel regions include a sample pixel region and a source pixel region, where the source pixel region is a pixel region for detecting external light; the providing of the initial turn-off voltage to the switching transistors of the two sets of pixel regions includes: providing an initial turn-off voltage to the switching transistors of the sample pixel region and the source pixel region such that the initial turn-off voltage provided to the sample pixel region is greater than the initial turn-off voltage provided to the source pixel region.
Optionally, a difference between the initial turn-off voltage and the initial threshold voltage of the switching transistor is less than or equal to 0 and greater than or equal to-6V.
Optionally, the adjusting the turn-off voltage provided to the switching transistors of the two groups of pixel regions according to the comparison result of the gray-scale values of the two groups of pixel regions includes: if the absolute value of the difference value of the gray values of the two groups of pixel areas is larger than a preset threshold value, reducing the turn-off voltage provided for the switching transistor of each group of pixel areas; and if the absolute value of the difference value of the gray values of the two groups of pixel areas is less than or equal to a preset threshold value, maintaining the turn-off voltage provided for the switching transistor of each group of pixel areas.
Optionally, the preset threshold is equal to 1.4-1.6 times of a turn-off standard gray scale difference, where the turn-off standard gray scale difference is a difference between gray scales of the two groups of pixel areas in a turn-off state under respective corresponding initial turn-off voltages.
In a third aspect, a flat panel detector is provided, comprising the pixel area adjustment system of the first aspect.
In a fourth aspect, there is provided an image pickup apparatus including the flat panel detector of the third aspect.
The technical scheme provided by the embodiment of the invention at least has the following technical effects or advantages:
according to the pixel area adjusting system, the control method, the flat panel detector and the camera device provided by the embodiment of the invention, two groups of pixel areas are arranged, unequal initial turn-off voltages are provided for the switching transistors of the two groups of pixel areas through the power supply circuit, and respective gray values of the two groups of pixel areas under the unequal turn-off voltages are acquired through the reading circuit. Because the initial turn-off voltage can not be effectively turned off due to excessive deviation of the threshold voltage of the transistor, and further the gray value difference of the two groups of pixel areas is increased, whether the current initial threshold voltage meets the off-state requirement of the transistor can be determined by comparing the gray values of the two groups of pixel areas, so that the adjusting circuit can adjust the turn-off voltage provided by the power supply circuit for the two groups of pixel areas according to the comparison result, the reduction of the sensitivity of the pixel areas caused by the deviation of the threshold voltage of the transistor is avoided, the product quality is improved, and the service life is prolonged.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a block diagram of a pixel area adjustment system according to an embodiment of the present invention;
FIG. 2 is a control diagram of a pixel area adjustment system according to an embodiment of the present invention;
FIG. 3 is a flowchart illustrating a control method of a pixel area adjustment system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a flat panel detector in an embodiment of the invention;
fig. 5 is a schematic diagram of an image pickup apparatus in an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The present invention provides a pixel area adjustment system, please refer to fig. 1, which is a structural diagram of a pixel area adjustment system 01 according to an embodiment of the present invention, including: two groups of pixel regions 10, a power supply circuit 20, a reading circuit 30 and an adjusting circuit 40;
the power supply circuit 20 is connected to the switching transistors of the two groups of pixel regions 10 to provide initial turn-off voltages for the two groups of pixel regions 10, wherein the initial turn-off voltages provided to different groups of pixel regions 10 are not equal to each other;
the acquisition end of the reading circuit 30 is connected with the photodiodes of the two groups of pixel regions 10 to acquire the gray value of each group of pixel regions 10;
the adjusting circuit 40 is connected between the power supply circuit 20 and the reading circuit 30 to receive the gray scale value from the reading circuit 30, and adjust the turn-off voltage provided by the power supply circuit 20 to the two groups of pixel regions 10 according to the comparison result of the gray scale values of the two groups of pixel regions 10.
The pixel area adjustment system may be provided in any device or apparatus including a pixel area controlled by a switching transistor, such as a flat panel detector, a photodetector, an X-ray machine, a camera, or a display, and is not limited herein.
Specifically, the switching transistor of the pixel region in the pixel region adjustment system may be made of amorphous silicon, or may be made of Indium Gallium Zinc Oxide (a-IGZO), which is not limited herein. Although transistors prepared from indium gallium zinc oxide have the defect of serious threshold voltage drift, the switching transistors in the pixel area adjusting system prepared from indium gallium zinc oxide have higher field effect mobility and lower off-state current compared with the switching transistors prepared from amorphous silicon, so that the pixel area adjusting system has the advantages of high frame rate, low noise and the like, and the problem of threshold voltage drift can be effectively avoided by adopting the pixel area adjusting system provided by the application.
The specific circuit structure and operation principle of the above pixel area adjustment system will be further described below.
As shown in fig. 1, the pixel area adjustment system 01 includes two sets of pixel areas 10, and specifically, a source pixel area for detecting or sensing external light (for example, a pixel area for detecting X-rays in a flat panel detector) in the pixel area adjustment system 01 may be divided into two sets of pixel areas, or a sample pixel area may be additionally provided in addition to the source pixel area, which is not limited herein. The two groups of pixel regions may be divided by pixel rows, pixel columns, or blocks, which is not limited herein.
The pixel region includes a photodiode which can sense light and perform photoelectric conversion, and a switching transistor connected to the photodiode. The turn-off voltage is a voltage applied to the gate of the switching transistor, and when the turn-off voltage is smaller than the threshold voltage of the switching transistor, the switching transistor can be effectively turned off, otherwise, a large leakage current occurs, and the sensitivity of the photodiode is affected.
The absolute value of the difference between the initial turn-off voltages of the two groups of pixel regions 10 may be set to 1-3V, for example, set to 2V, so as to consider the comparability of the difference between the acquired gray values of the two pixel regions and the sensitivity of the adjustment of the turn-off voltage. For example, the initial off-voltages of the two sets of pixel regions 10 may be set to-3V and-5V, respectively.
In some embodiments, the two sets of pixel regions 10 include a sample pixel region and a source pixel region, the source pixel region is a pixel region for detecting external light, and the sample pixel region is an additional pixel region for detecting the threshold voltage Vth of the transistor. And, the initial off-voltage supplied to the sample pixel region by the power supply circuit 20 is greater than the initial off-voltage supplied to the source pixel region by the power supply circuit 20. The arrangement enables the off-voltage of the sample pixel region to be closer to the Vth of the transistor than the off-voltage of the source pixel region, thereby ensuring that the sample pixel region always enters an insufficiently turned-off (increased off-current) state earlier than the source pixel region in the threshold voltage shift process. Therefore, before the source pixel area enters the insufficient turn-off state, the failure of the turn-off voltage caused by Vth drift can be found by comparing the gray values of the two pixel areas in time, so that the timeliness of adjusting the turn-off voltage is ensured, and the source pixel area for realizing the detection or display function of a product can be ensured to have a good turn-off state all the time.
In some embodiments, the difference of the initial turn-off voltage minus the initial threshold voltage of the switching transistor may be set to 0 or less and 6V or more, for example, the Vth of the transistor is 0V, and the turn-off voltage is set to-5V and-3V. Currently, considering that the Vth shift of a transistor can cause the image quality of a product to be degraded, the turn-off voltage is often set to be much lower than the initial threshold voltage of the switching transistor to ensure that the Vth shift of the transistor does not affect the off-state current of the transistor, for example, the Vth of the transistor is 0V, and the turn-off voltage is set to-10V. However, the excessively low off-voltage may rather aggravate the shift of Vth, reducing the lifetime of the product. Therefore, the initial turn-off voltage is set to a value closer to the initial threshold voltage of the transistor, and the detection and adjustment of the turn-off voltage are combined, so that the service life of the product can be effectively prolonged on the basis of avoiding the influence of Vth drift on the quality of the product.
As shown in fig. 1, the pixel area adjustment system 01 further includes a power supply circuit 20, a reading circuit 30, and an adjustment circuit 40. It should be noted that the power supply circuit 20, the reading circuit 30, and the adjusting circuit 40 may be integrated on the same chip, or may be separately provided, and are not limited herein.
Wherein, the output terminal of the power supply circuit 20 is connected to the switching transistors of the two groups of pixel regions 10 to provide the unequal initial turn-off voltages respectively. As shown in fig. 1, the power supply circuit 20 may include: a power supply circuit 210 and a gate drive circuit 220. The output terminal of the adjusting circuit 40 is connected to the power circuit 210 to adjust the off-voltage output by the power circuit 210. The output terminal of the power circuit 210 is connected to the switching transistors of the two groups of pixel regions 10 through the gate driving circuit 220, so as to provide the gate driving circuit 220 with the turn-off voltage corresponding to the currently scanned pixel region when the gate driving circuit 220 scans the two groups of pixel regions 10 respectively.
As shown in fig. 1, the power circuit 210 may include: a first power supply 211, a second power supply 212, and a data selector 213. The output end of the adjusting circuit 40 is connected to both the first power supply 211 and the second power supply 212 to respectively control the first power supply 211 and the second power supply 212 to output the turn-off voltages, wherein the turn-off voltages output by different power supplies are not equal. The output terminals of the first power source 211 and the second power source 212 are connected to the gate driving circuit 220 through a data selector 213(MUX), so that an off voltage corresponding to a currently scanned pixel region can be supplied to the gate driving circuit 220. The output terminal of the adjusting circuit 40 is also connected to the data selector 213 to control the data selector 213 to switch the off-voltage input by the first power supply 211 and the second power supply 212.
For example, the adjusting circuit 40 controls the data selector 213 to provide different turn-off voltages to the gate driving circuit 220 in time division. The data selector 213 supplies the gate driving circuit 220 with the off-voltage VGL _ DUM corresponding to the first pixel region outputted from the first power source 211 when the gate driving circuit 220 scans to the first pixel region in the two sets of pixel regions 10, and the data selector 213 supplies the gate driving circuit 220 with the off-voltage VGL _ ACT corresponding to the second pixel region outputted from the second power source 212 when the gate driving circuit 220 scans to the second pixel region in the two sets of pixel regions 10.
Of course, the power circuit 210 may be an adjustable power source, and outputs different off-voltages according to the control of the adjusting circuit 40, which is not limited herein.
The reading circuit 30 is connected to the photodiodes of the two sets of pixel regions 10, and the reading circuit 30 reads the integrated charges of the two sets of pixel regions region by region, converts the internal charges into an image digital signal (e.g., converted by an ADC circuit) representing the gray scale values of the two sets of pixel regions, and transmits the gray scale values to the adjusting circuit 40 via the image digital signal (e.g., a signal in LVDS format or VDI format), so that the adjusting circuit 40 can adjust the power supply circuit 20 according to the gray scale values. Of course, the reading circuit 30 may be further configured to store the image digital signal in a memory for backup.
The adjusting circuit 40 may be an FPGA, so as to modify the condition of comparing the gray-level values and modify the logic of the adjusting power supply circuit 20, thereby increasing flexibility. Of course, the adjusting circuit 40 may also be an ASIC or a controller, which is not limited herein. The adjusting circuit 40 and the power supply circuit 20 may be connected through an IIC interface, or may be connected through another data transmission interface.
In some embodiments, the adjustment circuit 40 includes: comparing unit 410 and adjusting unit 420, wherein the input terminal of comparing unit 410 is connected to reading circuit 30 to receive the gray-level value (image digital signal) and calculate the difference between the gray-level values of two sets of pixel regions as the comparing result. The gray value of each group of pixel regions may be an average value or a median value of the gray values of each pixel of the group of pixel regions.
The adjusting unit 420 is connected between the comparing unit 410 and the power supply circuit 20, so that when the absolute value of the difference is greater than the preset threshold, it is determined that the higher turn-off voltage in the two groups of pixel regions is greater than the threshold voltage of the transistor and cannot be effectively turned off, and therefore the power supply circuit 20 is controlled to reduce the turn-off voltage provided to the switching transistor of each group of pixel regions, so that the absolute value of the difference of the gray values of the two groups of pixel regions after the turn-off voltage is reduced is less than or equal to the preset threshold, and it is ensured that the turn-off voltages of the two groups of pixel regions are both less than the threshold voltage. And when the absolute value of the difference value is less than or equal to the preset threshold value, the turn-off voltages of the two groups of pixel areas are determined to be less than the threshold voltage of the transistor, and the transistor can be effectively turned off, so that the power supply circuit is controlled to maintain the turn-off voltage provided for the switching transistor of each group of pixel areas unchanged.
The preset threshold can be determined according to an actual debugging result, and the turn-off standard gray difference D of which the preset threshold is equal to 1.4-1.6 times (for example, 1.5 times) can be set, so that leakage current increase and gray value change caused by threshold voltage drift can be timely recognized on the one hand, and false triggering caused by fluctuation is avoided on the other hand. The turn-off standard gray scale difference D is a difference between gray scales of the two groups of pixel regions 10 in the turn-off state under the respective initial turn-off voltages. Wherein, the turn-off standard gray scale difference D is equal to K × Δ Q, K is the amplification factor of the read integrated charges by the reading circuit 30, and Δ Q is the charge difference caused by the turn-off of the switching transistors of the two groups of pixel regions under the respective turn-off voltages. Δ Q is equal to Δ VGL × Cgs, Δ VGL is an absolute value of a difference between off voltages of the two groups of pixel regions, and Cgs is a parasitic capacitance of the gate and the source of the switching transistor.
The difference value of the gray values is used as a comparison result, so that both high efficiency and accuracy are considered. Of course, the comparison result of the two groups of pixel regions may also be a ratio or a square difference of gray values, which is not limited herein.
The reduction range of the turn-off voltage provided to the switching transistors of each group of pixel areas by the power supply circuit 20 every time can be determined according to the actual debugging result, for example, the turn-off voltages of two groups of switching transistors are reduced by 1V to 2V every time, so that the gradual reduction of the turn-off voltage is realized, and the product life is prolonged. Of course, the reduction range may also be set according to the comparison result of the gray-level values of the two groups of pixel regions 10, the reduction range of the turn-off voltage is increased when the difference between the comparison results is large, and the reduction range of the turn-off voltage is decreased when the difference between the comparison results is small.
In some embodiments, the threshold voltage may be periodically or triggerably detected for drift and the off-state voltage may be adjusted by the pixel region adjustment system 01. For example, since the Vth voltage drift is gradually decreased in long-term use accumulation, the trigger adjustment may be performed in a cycle of a week or a month according to actual needs.
In the following, with reference to fig. 2, a specific control example is given by taking the pixel area adjustment system 01 as an example of being disposed on a flat panel detector:
and a pixel region originally used for detection in the flat panel detector is used as a source pixel region, and a sample pixel region is additionally arranged for detecting Vth voltage drift. And the off-voltage VGL _ DUM supplied to the sample pixel region by the power supply circuit 20 is set to-3V and the off-voltage VGL _ ACT supplied to the source pixel region is set to-5V.
When the switch transistor starts to operate, the threshold voltage of the switch transistor is about 0V, if the threshold voltage is larger than-3V, the two groups of pixel areas can be effectively switched off, and the corresponding off-state current is approximately in the range of the preset threshold value. With the use time of the detector continuing, the threshold voltage of the switching transistor drifts to-4V, then the sample pixel area can not be effectively turned off under the original-3V turn-off voltage, the off-state current is increased, the gray value collected by the reading circuit 30 is reduced, the source pixel area can still be effectively turned off, and the gray value collected by the reading circuit 30 is kept unchanged. Therefore, the difference between the gray values of the two groups of pixel areas is increased and exceeds the range of the preset threshold value.
Further, the trigger adjusting circuit 40 reduces the turn-off voltage of both sets of pixel regions by Δ VGL, for example, when Δ VGL is 2V, VGL _ DUM is reduced to-5V, and VGL _ ACT is reduced to-7V, so as to eliminate the image noise increase caused by Vth voltage drift. After adjustment, the two groups of pixel areas can be effectively turned off, the corresponding off-state currents are kept consistent continuously, and the gray value difference is restored to be within the range of the preset threshold value. Therefore, by setting a lower negative bias at the initial stage and adopting gradual reduction of the turn-off voltage, Vth drift of the switching transistor caused by the overlarge negative bias is effectively slowed down, and the service life of the detector is prolonged.
An embodiment of the present invention further provides a control method of the aforementioned pixel area adjustment system 01, where the pixel area adjustment system 01 includes two sets of pixel areas, as shown in fig. 3, and the method includes:
step S301, providing initial turn-off voltage to the switching transistors of two groups of pixel areas, wherein the initial turn-off voltage provided to different groups of pixel areas is not equal;
step S302, collecting the gray value of each group of pixel areas under the corresponding initial turn-off voltage;
step S303, according to the comparison result of the gray-scale values of the two sets of pixel regions, adjusting the turn-off voltage provided to the switching transistors of the two sets of pixel regions.
In some embodiments, the two sets of pixel regions include a sample pixel region and a source pixel region, the source pixel region being a pixel region for detecting external light; the providing of the initial turn-off voltage to the switching transistors of the two sets of pixel regions includes:
providing an initial turn-off voltage to the switching transistors of the sample pixel region and the source pixel region such that the initial turn-off voltage provided to the sample pixel region is greater than the initial turn-off voltage provided to the source pixel region.
In some embodiments, the difference between the initial turn-off voltage minus the initial threshold voltage of the switching transistor is equal to or less than 0 and equal to or greater than-6V.
In some embodiments, the adjusting the off-voltages provided to the switching transistors of the two sets of pixel regions according to the comparison result of the gray-level values of the two sets of pixel regions includes:
if the absolute value of the difference value of the gray values of the two groups of pixel areas is larger than a preset threshold value, reducing the turn-off voltage provided for the switching transistor of each group of pixel areas;
and if the absolute value of the difference value of the gray values of the two groups of pixel areas is less than or equal to a preset threshold value, maintaining the turn-off voltage provided for the switching transistor of each group of pixel areas.
In some embodiments, the preset threshold is equal to 1.4-1.6 times of a turn-off standard gray scale difference, where the turn-off standard gray scale difference is a difference between gray scale values of the two sets of pixel regions in an off state at respective corresponding initial turn-off voltages.
Since the control method described in the embodiment of the present invention is the control method of the pixel area adjustment system 01, details of the structure and the control method of the pixel area adjustment system 01 and the details of the original description of the pixel area adjustment system 01, those skilled in the art can understand the specific structure, the control method and the effect principle of the pixel area adjustment system 01, and thus the detailed description is omitted here. The control method of the pixel area adjustment system 01 according to the embodiment of the present invention is within the protection scope of the present invention.
An embodiment of the present invention further provides a flat panel detector, as shown in fig. 4, the flat panel detector 02 includes the aforementioned pixel area adjustment system 01. The same structure and advantageous effects as the pixel area adjustment system 01 provided as described above are also obtained.
Since the pixel area adjustment system 01 included in the flat panel detector according to the embodiment of the present invention is described in the foregoing, based on the pixel area adjustment system 01 according to the embodiment of the present invention, a person skilled in the art can understand the specific structure and effect principle of the flat panel detector, and thus details are not described herein again. It is within the scope of the present invention to include the flat panel detector of the pixel area adjustment system 01 of the embodiments of the present invention.
An embodiment of the present invention further provides an image capturing apparatus, as shown in fig. 5, including the foregoing flat panel detector 02. The same structure and advantageous effects as those of the flat panel detector 02 provided previously are also obtained.
Note that the image pickup apparatus may be: any product or component with the function of camera shooting, such as a camera, security check equipment or a medical X-ray machine.
Since the flat panel detector 02 included in the image capturing apparatus according to the embodiment of the present invention is described in the foregoing, based on the flat panel detector 02 described in the embodiment of the present invention, a person skilled in the art can understand a specific structure and an effect principle of the image capturing apparatus, and thus details are not described herein again. All imaging apparatuses including the flat panel detector 02 according to the embodiment of the present invention belong to the protection scope of the present invention.
The technical scheme provided by the embodiment of the invention at least has the following technical effects or advantages:
two groups of pixel areas are arranged, unequal initial turn-off voltages are provided for the switching transistors of the two groups of pixel areas through the power supply circuit, and respective gray values of the two groups of pixel areas under the unequal turn-off voltages are acquired through the reading circuit. Because the initial turn-off voltage can not be effectively turned off due to excessive deviation of the threshold voltage of the transistor, and further the gray value difference of the two groups of pixel areas is increased, whether the current initial threshold voltage meets the off-state requirement of the transistor can be determined by comparing the gray values of the two groups of pixel areas, so that the adjusting circuit can adjust the turn-off voltage provided by the power supply circuit for the two groups of pixel areas according to the comparison result, the reduction of the sensitivity of the pixel areas caused by the deviation of the threshold voltage of the transistor is avoided, the product quality is improved, and the service life is prolonged.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
Those skilled in the art will appreciate that the modules in the apparatus of an embodiment may be adaptively changed and disposed in one or more apparatuses other than the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
Claims (14)
1. A pixel area adjustment system, comprising:
the pixel reading circuit comprises two groups of pixel areas, a power supply circuit, a reading circuit and an adjusting circuit;
the power supply circuit is connected with the switching transistors of the two groups of pixel areas to provide initial turn-off voltage for the two groups of pixel areas, wherein the initial turn-off voltage provided for different groups of pixel areas is not equal;
the acquisition end of the reading circuit is connected with the photodiodes of the two groups of pixel areas to acquire the gray value of each group of pixel areas;
the adjusting circuit is connected between the power supply circuit and the reading circuit so as to receive the gray values from the reading circuit and adjust the turn-off voltage provided by the power supply circuit to the two groups of pixel areas according to the comparison result of the gray values of the two groups of pixel areas.
2. The pixel area adjustment system of claim 1, wherein the two sets of pixel areas comprise:
the device comprises a sample pixel area and a source pixel area, wherein the source pixel area is used for detecting external light;
the initial off-voltage provided by the power supply circuit to the sample pixel region is greater than the initial off-voltage provided by the power supply circuit to the source pixel region.
3. The pixel area adjustment system of claim 1, wherein:
the difference value of the initial turn-off voltage minus the initial threshold voltage of the switching transistor is less than or equal to 0 and greater than or equal to-6V.
4. The pixel area adjustment system of claim 1, wherein:
the adjusting circuit is an FPGA and is connected with the power supply circuit through an IIC interface.
5. The pixel area adjustment system of claim 1, wherein the adjustment circuit comprises:
a comparison unit and an adjustment unit;
the input end of the comparison unit is connected with the reading circuit to receive the gray value and calculate the difference value of the gray values of the two groups of pixel areas as the comparison result;
the adjusting unit is connected between the comparing unit and the power supply circuit to control the power supply circuit to reduce the turn-off voltage provided to the switching transistor of each group of pixel areas when the absolute value of the difference is greater than a preset threshold; and when the absolute value of the difference value is less than or equal to a preset threshold value, controlling the power supply circuit to maintain the off-state voltage provided for the switching transistor of each group of pixel areas.
6. The pixel area adjustment system according to claim 1, wherein the power supply circuit comprises:
a power supply circuit and a gate drive circuit;
the output end of the adjusting circuit is connected with the power supply circuit so as to adjust the turn-off voltage output by the power supply circuit;
the output end of the power circuit is connected with the switching transistors of the two groups of pixel areas through the grid driving circuit so as to provide the grid driving circuit with a turn-off voltage corresponding to the currently scanned pixel area when the grid driving circuit respectively scans the two groups of pixel areas.
7. The pixel area adjustment system according to claim 6, wherein the power supply circuit comprises:
a first power supply, a second power supply, and a data selector;
the output end of the adjusting circuit is connected with the first power supply and the second power supply so as to respectively control the first power supply and the second power supply to output turn-off voltages, wherein the turn-off voltages output by different power supplies are not equal;
the output ends of the first power supply and the second power supply are connected with the grid driving circuit through the data selector so as to provide the grid driving circuit with a turn-off voltage corresponding to a currently scanned pixel region.
8. A method for controlling a pixel area adjustment system, the pixel area adjustment system comprising two sets of pixel areas, the method comprising:
providing initial turn-off voltages to the switching transistors of the two groups of pixel areas, wherein the initial turn-off voltages provided to the different groups of pixel areas are not equal;
collecting the gray value of each group of pixel areas under the corresponding initial turn-off voltage;
and adjusting the turn-off voltage provided for the switching transistors of the two groups of pixel areas according to the comparison result of the gray values of the two groups of pixel areas.
9. The control method according to claim 8, wherein the two sets of pixel regions include a sample pixel region and a source pixel region, the source pixel region being a pixel region for detecting external light; the providing of the initial turn-off voltage to the switching transistors of the two sets of pixel regions includes:
providing an initial turn-off voltage to the switching transistors of the sample pixel region and the source pixel region such that the initial turn-off voltage provided to the sample pixel region is greater than the initial turn-off voltage provided to the source pixel region.
10. The control method according to claim 8, wherein a difference of the initial off-voltage minus an initial threshold voltage of the switching transistor is 0 or less and-6V or more.
11. The method as claimed in claim 8, wherein the adjusting the turn-off voltage provided to the switching transistors of the two sets of pixel regions according to the comparison result of the gray-level values of the two sets of pixel regions comprises:
if the absolute value of the difference value of the gray values of the two groups of pixel areas is larger than a preset threshold value, reducing the turn-off voltage provided for the switching transistor of each group of pixel areas;
and if the absolute value of the difference value of the gray values of the two groups of pixel areas is less than or equal to a preset threshold value, maintaining the turn-off voltage provided for the switching transistor of each group of pixel areas.
12. The control method according to claim 11, characterized in that:
the preset threshold is equal to 1.4-1.6 times of turn-off standard gray scale difference, wherein the turn-off standard gray scale difference is the difference value of gray scale values of the two groups of pixel areas in turn-off states under respective corresponding initial turn-off voltages.
13. A flat panel detector comprising a pixel area adjustment system according to any of claims 1-7.
14. An image pickup apparatus characterized by comprising the flat panel detector according to claim 13.
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