CN111193886A - Pixel structure, image sensor and terminal - Google Patents
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Abstract
The embodiment of the application discloses pixel structure, image sensor and terminal, pixel structure includes: at least two sub-pixel structures of a triangle, the sub-pixel structures comprising: the device comprises an optical filter, at least one polarization photoelectric conversion unit and a readout circuit; the optical filter is used for filtering incident light to obtain an optical signal with a specific waveband, which can be absorbed by at least one polarization photoelectric conversion unit; the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a specific waveband and converting the absorbed polarized light signal into an electric signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions. In this way, when the triangular pixel structure is adopted for polarized light absorption, the pixel density of the image sensor can be improved, and the polarized light absorption rate and the resolution of the image sensor can be improved.
Description
Technical Field
The present application relates to image technologies, and in particular, to a pixel structure, an image sensor, and a terminal.
Background
FIG. 1 is a schematic diagram of a pixel array of a conventional polarized image sensor; as shown in fig. 1, the conventional polarized image sensor includes a Photodiode (PD) array at a bottom layer, a polarizer array at a middle layer, and a microlens array at a top layer. The photodiode array structure in each pixel structure has a polarizer with different polarization directions, for example, four different angles of 0 °, 45 °, 90 °, 135 °, and each 4 pixels is used as a calculation unit. Fig. 2 is a schematic diagram of a conventional pixel structure, and as shown in fig. 2, the pixel structure includes: the pixel structure comprises a micro lens, a polaroid and a PD, wherein incident light passes through the micro lens and enters the inside of the pixel structure, light with a specific polarization direction passes through the polaroid and is absorbed by the PD, and the PD converts an absorbed polarized light signal into an electric signal for subsequent image processing. The pixels of the existing polarization image sensor are square, and the lower pixel density makes the polarization image sensor easy to lose resolution.
Disclosure of Invention
In order to solve the foregoing technical problem, embodiments of the present application desirably provide a pixel structure, an image sensor, and a terminal, which can implement that a single pixel structure absorbs polarized light signals of two specific bands, and improve the utilization rate of the polarized light signals.
The technical scheme of the application is realized as follows:
in a first aspect, a pixel structure is provided, which includes: at least two sub-pixel structures of a triangle, the sub-pixel structures comprising: the device comprises an optical filter, at least one polarization photoelectric conversion unit and a readout circuit;
the optical filter is positioned between the at least one polarization photoelectric conversion unit and the light inlet of the sub-pixel structure and is used for filtering incident light to obtain an optical signal of a specific waveband which can be absorbed by the at least one polarization photoelectric conversion unit;
the polarization photoelectric conversion unit is used for absorbing the polarized light signal of the specific waveband and converting the absorbed polarized light signal into an electric signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions;
the reading circuit is connected with the at least one polarization photoelectric conversion unit and used for reading the electric signal of the at least one polarization photoelectric conversion unit.
In a second aspect, an image sensor is provided, the image sensor comprising any one of the pixel structures described above.
In a third aspect, a terminal is provided, which includes the above image sensor.
By adopting the technical scheme, a new pixel structure is obtained, and the pixel structure comprises: at least two sub-pixel structures of a triangle, the sub-pixel structures comprising: the device comprises an optical filter, at least one polarization photoelectric conversion unit and a readout circuit; the optical filter is positioned between the at least one polarization photoelectric conversion unit and the light inlet of the sub-pixel structure and is used for filtering incident light to obtain an optical signal of a specific waveband which can be absorbed by the at least one polarization photoelectric conversion unit; the polarization photoelectric conversion unit is used for absorbing the polarized light signal of the specific waveband and converting the absorbed polarized light signal into an electric signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions. In this way, when the triangular pixel structure is adopted for polarized light absorption, the pixel density of the image sensor can be improved, and the polarized light absorption rate and the resolution of the image sensor can be improved.
Drawings
FIG. 1 is a schematic diagram of a pixel array of a conventional polarized image sensor;
FIG. 2 is a diagram of a conventional pixel structure;
FIG. 3 is a schematic diagram illustrating a sub-pixel structure according to an embodiment of the present disclosure;
fig. 4 is a schematic view of a first distribution array of polarization photoelectric conversion units in an embodiment of the present application;
fig. 5 is a schematic view of a second distribution array of polarization photoelectric conversion units in the embodiment of the present application;
FIG. 6 is a schematic longitudinal cross-sectional view of a sub-pixel structure in an embodiment of the present application;
FIG. 7 is a schematic diagram of a structure of a readout circuit according to an embodiment of the present application;
FIG. 8 is a schematic diagram of a first component structure of an image sensor in an embodiment of the present application;
FIG. 9 is a diagram illustrating a second structure of an image sensor according to an embodiment of the present disclosure;
FIG. 10 is a schematic diagram of a third component structure of an image sensor in an embodiment of the present application;
fig. 11 is a schematic structural diagram of a terminal in an embodiment of the present application.
Detailed Description
So that the manner in which the features and elements of the present embodiments can be understood in detail, a more particular description of the embodiments, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings.
In practical application, the pixel structure is used as an important component of an image sensor, and can perform photoelectric conversion on received natural light, so as to obtain an electric signal, however, when the pixel size of the pixel structure is about 600nm, the polarization photoelectric conversion unit has higher quantum efficiency, and as the pixel size is reduced, the area of a photosensitive region of the polarization photoelectric conversion unit is also reduced, so that the quantum efficiency of the polarization photoelectric conversion unit is reduced, and the imaging effect of the image sensor is affected.
Here, quantum efficiency is a measure of the efficiency of converting photons of a certain frequency/wavelength of a certain color channel into electrons, in a conventional pixel structure, as the size of a pixel is continuously reduced, the area of a photosensitive region of a polarization photoelectric conversion unit is also reduced, so that the maximum signal charge amount that can be accommodated in a charge collection potential well of the polarization photoelectric conversion unit, that is, the full well capacity (referred to as well capacity for short), is suppressed, the well capacity is suppressed, and indexes such as the dynamic range, the signal-to-noise ratio, the sensitivity and the like of a small-sized pixel are deteriorated, and these indexes directly affect the imaging quality of the small-sized pixel.
In order to ensure the quantum efficiency of the polarization photoelectric conversion unit in the image sensor, the embodiment of the application provides a pixel structure in the image sensor, and the pixel structure comprises: at least two triangular sub-pixel structures, and fig. 3 is a schematic structural diagram of a sub-pixel structure in an embodiment of the present application; as shown in fig. 3, the sub-pixel structure includes: an optical filter 301, at least one polarization photoelectric conversion unit 302, and a readout circuit 303;
the optical filter 301 is located between the at least one polarization photoelectric conversion unit and the light inlet of the sub-pixel structure, and is configured to filter incident light to obtain an optical signal of a specific wavelength band that can be absorbed by the at least one polarization photoelectric conversion unit;
the polarization photoelectric conversion unit 302 is configured to absorb the polarized light signal of the specific waveband and convert the absorbed polarized light signal into an electrical signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions;
the readout circuit 303 is connected to the at least one polarization photoelectric conversion unit 302, and is configured to read out an electrical signal of the at least one polarization photoelectric conversion unit.
In the embodiment of the application, compared with the existing square pixel structure, the triangular sub-pixel structure has the advantages that the number of pixels distributed in the same area is large, and the pixel density is large, so that the absorption rate of polarized light and the resolution of an image sensor are improved. Here, the sub-pixel structure may be an equilateral triangle, an isosceles triangle, a right-angled triangle, or other common triangles.
Specifically, incident light enters the sub-pixel structure through the light inlet and reaches at least one polarization photoelectric conversion unit along an incident light path, an optical signal of a specific waveband absorbed by the polarization photoelectric conversion unit is converted into an electrical signal, and the electrical signal of the polarization photoelectric conversion unit is read out by the reading circuit for color perception.
In some embodiments, the polarization photoelectric conversion unit is configured to absorb the polarized light signal of the specific wavelength band according to a resonance wavelength of the photosensitive region; the resonance wavelength is the wavelength when the light sensing area of the polarization photoelectric conversion unit generates resonance absorption; the different sizes of photosensitive areas correspond to different bands of resonant wavelengths.
Here, when the side length of the triangular light entrance in the sub-pixel structure is smaller than the shortest wavelength of the specific wavelength band, in order to prevent the specific wavelength band from being diffracted, the polarization photoelectric conversion unit absorbs the specific wavelength band according to the resonance wavelength of the light-sensitive region thereof.
In practical applications, the light-sensing area may be an upper surface of the polarization photoelectric conversion unit, and the resonance wavelength of the polarization photoelectric conversion unit is related to the refractive index and the size of the light-sensing area of the polarization photoelectric conversion unit, so that the resonance wavelength of the polarization photoelectric conversion unit can be adjusted by adjusting the refractive index of the light-sensing area and/or the size of the light-sensing area.
In practical application, when the side length of a triangle of a pixel light inlet is less than the shortest wavelength of a specific waveband, the polarized photoelectric conversion units with different resonance wavelengths can be obtained only by adjusting the size of a photosensitive area of the polarized photoelectric conversion unit, so that light of the specific waveband is absorbed by the polarized photoelectric conversion unit in a resonance absorption mode, and the polarized photoelectric conversion unit still has high quantum efficiency in a smaller photosensitive area.
In order to make the polarization photoelectric conversion unit still have high quantum efficiency under a small photosensitive area, the specific waveband is within the waveband range of the resonance wavelength. In the embodiment of the present application, the resonance wavelength is adjusted by adjusting the size of the photosensitive region of the polarization photoelectric conversion unit, so that the specific wavelength band to be absorbed is within the wavelength band range of the resonance wavelength of the photosensitive region of the polarization photoelectric conversion unit. Therefore, the obtained polarization photoelectric conversion unit with the smaller size can realize resonance absorption on optical signals of a specific waveband, so that the polarization photoelectric conversion unit still has higher quantum efficiency under a smaller photosensitive area. By increasing the number of the polarization photoelectric conversion units and arranging the arrangement mode of the polarization photoelectric conversion units, the absorption rate of the sub-pixel structure to optical signals in a specific wave band can be further improved.
In some embodiments, the polarization photoelectric conversion unit is shaped as a straight prism; the light sensing area of the polarization photoelectric conversion unit is a polygonal bottom surface of a straight prism. For example, the polygonal bottom surface is a regular quadrangle, a regular hexagon, a regular octagon, or the like. The upper surface of the right prism is a photosensitive area which can be a regular polygon or an irregular polygon.
Illustratively, the polygonal bottom surface of the right prism is rectangular, and the polarization direction of the polarized light signal absorbed by the polarization photoelectric conversion unit is the same as the long side direction of the rectangular bottom surface of the right prism.
In some embodiments, when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a first length, the rectangular bottom surface is used for absorbing a polarized light signal of a first specific waveband; when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a second length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a second specific wave band; and when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a third length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a third specific waveband.
Illustratively, the first length is 70nm, the first specific wavelength band is a blue light band, the second length is 90nm, the second specific wavelength band is a green light band, and the third length is 110 nm; the third specific wavelength band is a red wavelength band.
In some embodiments, when the long side direction of the rectangular bottom surface of the polarization photoelectric conversion unit is the first direction, the polarization photoelectric conversion unit is configured to absorb a polarized light signal with the polarization direction being the first direction. That is, the first direction is dependent on the polarization direction of the absorbed polarized light signal.
In some embodiments, the height of the right prisms is within a predetermined height range; wherein the preset height range is a height range which ensures that the light absorptivity of the polarization photoelectric conversion unit is greater than an absorptivity threshold. For example, the height of the polarized photodiode for absorbing blue light is 80nm-500nm, the higher the height is, the higher the absorptivity is, and the absorptivity can reach more than 98% at 1 um. The height of the polarized photodiode for absorbing green light is 500nm-1um, and the height of the polarized photodiode for absorbing red light is 500nm-2 um.
In the embodiment of the application, one sub-pixel structure is used for absorbing the optical signal of one polarization direction in one specific wave band. When the long side directions of the rectangular bottom surfaces of the light sensing areas in different sub-pixel structures are different, optical signals with different polarization directions are absorbed.
That is, the long side length of the rectangular bottom surface of the polarization photoelectric conversion unit is used to limit the wavelength of the absorbed optical signal, and the long side direction is used to limit the polarization direction of the absorbed optical signal. Therefore, in the embodiment of the application, a polarizing plate is not required to be arranged above the photoelectric conversion unit, and the arrangement direction of the photoelectric conversion unit is arranged, so that polarized light signals with the polarization direction being the arrangement direction can be absorbed, and the hardware configuration of the pixel structure is simplified.
Correspondingly, when the polarized photoelectric conversion unit is used for absorbing a blue light wave band, the optical filter can be a blue optical filter and only allows blue light; when the polarization photoelectric conversion unit is used for absorbing red light wave bands, the light filter can be a red light filter and only allows red light; when the polarization photoelectric conversion unit is used for absorbing a green light band, the filter can be a green filter, and only the green light band is allowed.
Specifically, the polarization photoelectric conversion unit may be a polarization photodiode, the polarization photodiode is shaped as a rectangular prism, the bottom surface of the rectangular prism is rectangular, and the light sensing area of the polarization photodiode is rectangular. For example, the size of the light-sensing region of the polarization photoelectric conversion unit that absorbs blue light is 70nm × 50nm, the diameter of the light-sensing region of the polarization photoelectric conversion unit that absorbs green light is 90nm × 50nm, and the diameter of the light-sensing region of the polarization photoelectric conversion unit that absorbs red light is 110nm × 50 nm. When the optical signal of a specific waveband is absorbed through the resonance absorption principle, the photoelectric conversion unit can be ensured to have higher quantum efficiency by adjusting the size of the photosensitive area of the photoelectric conversion unit, and the requirements of small size and high pixel of the image sensor are met.
In some embodiments, the top end of the at least one polarization photoelectric conversion unit is close to the optical filter; and the bottom ends of the at least one polarization photoelectric conversion unit are connected and then connected with the reading circuit.
Specifically, the at least one polarization photoelectric conversion unit is distributed on the same cross section based on an array with equal intervals of polarization directions of the polarized light signals absorbed by the sub-pixel structure.
Specifically, when the sub-pixel structure comprises a polarization photoelectric conversion unit, the optical filter polarization photoelectric conversion units are arranged in a stacked mode, the polarization direction of the optical filter polarization photoelectric conversion units is the same as the long side direction of the rectangular bottom surface of the straight prism, and the reading circuit reads out electric signals of the polarization photoelectric conversion units for color perception.
When the sub-pixel structure comprises at least two polarization photoelectric conversion units, the polarization photoelectric conversion units are distributed on the same cross section in an equidistant array mode according to the fact that the long side direction of the rectangular bottom face of each polarization photoelectric conversion unit is the same as the polarization direction, and the top ends of the polarization photoelectric conversion units are connected with the bottom end of the optical filter. All the polarized photoelectric conversion units in one sub-pixel structure absorb polarized light signals with the same polarization direction in a specific waveband. Therefore, the electrical signals converted by all the polarization photoelectric conversion units can be collected and read by the reading circuit. For example, after incident light passes through the blue filter, a polarized light signal of blue light is firstly absorbed by the M polarized photodiodes, more than 95% of the blue light is absorbed due to resonance absorption of the rectangular polarized photodiode, and is converted into an electric signal to be stored in the PD, and the read-out circuit reads out a signal of a blue light channel from the PD. The absorption of red and green light is the same and will not be described further.
In practical applications, at least two sub-pixel structures may be included in the pixel structure for absorbing optical signals with different polarization directions. For example, 2, 4, 8, 16 or more sub-pixel structures may be included to absorb more polarized light signals.
Fig. 4 is a schematic diagram of a first distribution array of polarization photoelectric conversion units in an embodiment of the present application, where the pixel structure in fig. 4 includes sub-pixel structures that absorb two different polarization optical signals, the polarization directions are 45 ° and 135 °, respectively, the left sub-pixel structure includes 4 polarization photoelectric conversion units with an arrangement direction of 45 °, and the right sub-pixel structure includes 4 polarization photoelectric conversion units with an arrangement direction of 135 °.
Fig. 5 is a schematic diagram of a second distribution array of the polarization photoelectric conversion units in the embodiment of the present application, and the pixel structure in fig. 5 includes sub-pixel structures that absorb four different polarization light signals, and the polarization directions are 0 °, 45 °, 90 °, and 135 °, respectively. The first sub-pixel structure from the left side comprises 16 polarization photoelectric conversion units with the arrangement direction of 0 degree, the second sub-pixel structure comprises 16 polarization photoelectric conversion units with the arrangement direction of 45 degrees, the third sub-pixel structure comprises 16 first polarization photoelectric conversion units with the arrangement direction of 90 degrees, and the fourth sub-pixel structure comprises 16 first polarization photoelectric conversion units with the arrangement direction of 135 degrees.
In practical applications, the pixel structure may further include a sub-pixel structure that absorbs polarized light signals with 9, 16, or more polarization directions in addition to the sub-pixel structures that absorb polarized light signals with 2 and 4 different polarization directions shown in fig. 4 and 5, so as to obtain polarized light signals with more polarization directions.
For example, a polarized light signal with 9 polarization directions is absorbed, and the polarization directions are 0 °, 20 °, 40 °, 60 °, 80 °, 100 °, 120 °, 140 °, and 160 °, respectively.
The polarization direction of the polarized light signals with 16 polarization directions is respectively 0 degrees, 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees, 90 degrees, 100 degrees, 110 degrees, 120 degrees, 130 degrees, 140 degrees, 150 degrees, 160 degrees and 170 degrees.
Fig. 6 is a schematic longitudinal cross-sectional view of a sub-pixel structure in an embodiment of the present application, in which a filter 301 in the sub-pixel structure allows light in a specific wavelength band to pass through, but does not allow light in other wavelengths to pass through, after incident light passes through the filter 301, an optical signal in the specific wavelength band is absorbed and converted into an electrical signal by a polarization photoelectric conversion unit 302, and a readout circuit 303 reads out the electrical signal for color perception. The cross section of 4 polarization photoelectric conversion units 302 is shown only as an example in fig. 6, and is not intended to limit the number of photoelectric conversion units.
Fig. 7 is a schematic diagram of a composition structure of a readout circuit in an embodiment of the present application, in which a filter 301 in a sub-pixel structure allows light in a specific wavelength band to pass through, but does not allow light in other wavelengths to pass through, after incident light passes through the filter 301, an optical signal in the specific wavelength band is absorbed and converted by a polarization photoelectric conversion unit 302 into an electrical signal, and the readout circuit reads out the electrical signal for color perception. Specifically, the readout circuit includes a Transfer Gate (TG), a Floating Diffusion (FD), a Source-follower Transistor (SF), a Row Select Transistor (RST), and a Select Transistor (SEL). The work flow of the reading circuit comprises the following steps: 1. exposing; an electron-hole pair generated by irradiating the PN junction with light is separated due to the existence of an electric field in the PN junction, the electron moves to an n region, and the hole moves to an energy accumulation region of a p region; 2. resetting; loading reverse voltage to the PN junction, or activating RST to reset the PN junction, and resetting the read-out region (n + region) to high level; 3. reading out a reset level; after the reset is completed, reading out a reset level; 4. charge transfer, activating the transfer gate TG, transferring charge from the n region completely to the n + region for readout; 5. the signal level of the n + region is read out.
By adopting the technical scheme, a new pixel structure is obtained, and the pixel structure comprises: at least two sub-pixel structures of a triangle, the sub-pixel structures comprising: the device comprises an optical filter, at least one polarization photoelectric conversion unit and a readout circuit; the optical filter is positioned between the at least one polarization photoelectric conversion unit and the light inlet of the sub-pixel structure and is used for filtering incident light to obtain an optical signal of a specific waveband which can be absorbed by the at least one polarization photoelectric conversion unit; the polarization photoelectric conversion unit is used for absorbing the polarized light signal of the specific waveband and converting the absorbed polarized light signal into an electric signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions. In this way, when the triangular pixel structure is adopted for polarized light absorption, the pixel density of the image sensor can be improved, and the polarized light absorption rate and the resolution of the image sensor can be improved.
Fig. 8 is a schematic diagram of a first composition structure of an image sensor in an embodiment of the present application, and as shown in fig. 8, an image sensor 80 includes a pixel structure 801 according to one or more embodiments, where a plurality of pixel structures form a pixel array according to a specific arrangement.
Specifically, the pixel structure 801 includes: a triangular subpixel structure, said subpixel structure comprising: at least two sub-pixel structures, the sub-pixel structures comprising: the device comprises an optical filter, at least one polarization photoelectric conversion unit and a readout circuit;
the optical filter is positioned between the at least one polarization photoelectric conversion unit and the light inlet of the sub-pixel structure and is used for filtering incident light to obtain an optical signal of a specific waveband which can be absorbed by the at least one polarization photoelectric conversion unit;
the polarization photoelectric conversion unit is used for absorbing the polarized light signal of the specific waveband and converting the absorbed polarized light signal into an electric signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions;
the reading circuit is connected with the at least one polarization photoelectric conversion unit and used for reading the electric signal of the at least one polarization photoelectric conversion unit.
In some embodiments, the polarization photoelectric conversion unit is configured to absorb the polarized light signal of the specific wavelength band according to a resonance wavelength of the photosensitive region; the resonance wavelength is the wavelength when the light sensing area of the polarization photoelectric conversion unit generates resonance absorption; the different sizes of photosensitive areas correspond to different bands of resonant wavelengths.
In some embodiments, the polarization photoelectric conversion unit is shaped as a straight prism; the light sensing area of the polarization photoelectric conversion unit is a polygonal bottom surface of a straight prism.
In some embodiments, the polygonal bottom surface of the right prism is rectangular, and the polarization direction of the polarized light signal absorbed by the polarization photoelectric conversion unit is the same as the long side direction of the rectangular bottom surface of the right prism.
In some embodiments, when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a first length, the rectangular bottom surface is used for absorbing a polarized light signal of a first specific waveband; when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a second length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a second specific wave band; and when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a third length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a third specific waveband.
In some embodiments, the height of the right prisms is within a predetermined height range; wherein the preset height range is a height range which ensures that the light absorptivity of the polarization photoelectric conversion unit is greater than an absorptivity threshold.
In some embodiments, the top end of the at least one polarization photoelectric conversion unit is close to the optical filter; and the bottom ends of the at least one polarization photoelectric conversion unit are connected and then connected with the reading circuit.
In some embodiments, the at least one polarization photoelectric conversion unit is distributed on the same cross section based on an array with equal intervals of polarization directions of the polarized light signals absorbed by the sub-pixel structures.
In the embodiment of the application, different sub-pixel structures in the same pixel structure are used for polarized light signals with the same wave band and different polarization directions, and different pixel structures are used for absorbing polarized light signals with different wave bands.
When the image sensor only comprises one pixel structure, the image sensor is formed by an array distribution mode that P rows and Q columns are formed by N pixel structures and is used for absorbing polarized light signals of the same wave band, and N is P multiplied by Q.
When at least two kinds of pixel structures are included, different kinds of pixel structures absorb polarized light signals of different wavelength bands. For example, a first pixel structure is used for absorbing blue light, a second pixel structure is used for absorbing red light, and a third pixel structure is used for absorbing blue light. When two or more pixel structures are included, the two pixel structures can be distributed at intervals to form an array distribution form of P rows and Q columns, and the number of the two pixel structures is equal.
In practical applications, the pixel structure in the image sensor is composed of one or more than two pixel structures. Different pixel structures are used for absorbing optical signals of different specific wave bands, and the optical filter only allows optical signals of one specific wave band to pass through and does not allow optical signals of other wavelengths to pass through. For example, the filter may be a blue filter, which only allows blue light to pass through; the filter can be a red filter, and only red light is allowed to pass through; the filter may be a green filter, allowing only green light to pass through.
Fig. 9 is a schematic diagram of a second structure of an image sensor according to an embodiment of the present disclosure, where the image sensor includes a pixel structure (a pixel structure is enclosed by a dashed box in fig. 9), and each pixel includes four sub-pixel structures for absorbing polarized light signals of four different polarization directions.
Fig. 10 is a schematic diagram of a third component structure of an image sensor according to an embodiment of the present disclosure, in which the image sensor includes three pixel structures, which are denoted by r (red), g (green), and b (blue), respectively, and the three pixel structures absorb red light, filter light, and blue light, respectively. Here, each pixel structure may include a triangular sub-pixel structure for absorbing a polarized light signal of one polarization direction. In practical applications, each pixel structure may include more than two triangular sub-pixel structures for absorbing polarized light signals with more than two polarization directions.
In the embodiment of the present application, a sub-wavelength ultra-small pixel structure of a pixel structure is applied to a sub-wavelength Complementary Metal Oxide Semiconductor image sensor (CIS).
In this way, when the triangular pixel structure is adopted for polarized light absorption, the pixel density of the image sensor can be improved, and the polarized light absorption rate and the resolution of the image sensor can be improved. And based on the resonance absorption principle of the polarized photoelectric conversion unit, the polarized photoelectric conversion unit still has higher quantum efficiency when the pixel size is smaller, and the absorption rate of a polarized light signal is improved.
Fig. 11 is a schematic diagram of a composition structure of a terminal in an embodiment of the present application, and as shown in fig. 11, the terminal 110 includes an image sensor 1101 described in the above embodiment.
The technical solutions described in the embodiments of the present application can be arbitrarily combined without conflict.
In the several embodiments provided in the present application, it should be understood that the disclosed pixel structure, image sensor and terminal can be implemented in other manners. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on a plurality of network units; some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, all functional units in the embodiments of the present application may be integrated into one second processing unit, or each unit may be separately regarded as one unit, or two or more units may be integrated into one unit; the integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application.
Claims (10)
1. A pixel structure, comprising: at least two sub-pixel structures of a triangle, the sub-pixel structures comprising: the device comprises an optical filter, at least one polarization photoelectric conversion unit and a readout circuit;
the optical filter is positioned between the at least one polarization photoelectric conversion unit and the light inlet of the sub-pixel structure and is used for filtering incident light to obtain an optical signal of a specific waveband which can be absorbed by the at least one polarization photoelectric conversion unit;
the polarization photoelectric conversion unit is used for absorbing the polarized light signal of the specific waveband and converting the absorbed polarized light signal into an electric signal; the polarization photoelectric conversion units in the same sub-pixel structure are used for absorbing polarization light signals in the same polarization direction, and the polarization photoelectric conversion units in different sub-pixel structures are used for absorbing polarization light signals in different polarization directions;
the reading circuit is connected with the at least one polarization photoelectric conversion unit and used for reading the electric signal of the at least one polarization photoelectric conversion unit.
2. The pixel structure according to claim 1, wherein the polarization photoelectric conversion unit is configured to absorb the polarized light signal of the specific wavelength band according to a resonance wavelength of a photosensitive region;
the resonance wavelength is the wavelength when the light sensing area of the polarization photoelectric conversion unit generates resonance absorption; the different sizes of photosensitive areas correspond to different bands of resonant wavelengths.
3. The pixel structure according to claim 1 or 2, wherein the polarization photoelectric conversion unit is shaped as a straight prism; the light sensing area of the polarization photoelectric conversion unit is a polygonal bottom surface of a straight prism.
4. The pixel structure according to claim 3, wherein the polygonal bottom surface of the right prism is rectangular, and the polarization direction of the polarized light signal absorbed by the polarization photoelectric conversion unit is the same as the long side direction of the rectangular bottom surface of the right prism.
5. The pixel structure of claim 4,
when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a first length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a first specific wave band;
when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a second length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a second specific wave band;
and when the length of the rectangular bottom surface of the polarization photoelectric conversion unit is a third length, the polarization photoelectric conversion unit is used for absorbing a polarized light signal of a third specific waveband.
6. The pixel structure according to claim 3, wherein the height of the right prism is within a predetermined height range; wherein the preset height range is a height range which ensures that the light absorptivity of the polarization photoelectric conversion unit is greater than an absorptivity threshold.
7. The pixel structure according to claim 1, wherein the top end of the at least one polarization photoelectric conversion unit is close to the optical filter;
and the bottom ends of the at least one polarization photoelectric conversion unit are connected and then connected with the reading circuit.
8. The pixel structure according to claim 1, wherein the at least one polarization photoelectric conversion unit is distributed on the same cross section based on an array with equal spacing of polarization directions of the polarized light signals absorbed by the sub-pixel structure.
9. An image sensor, characterized in that the image sensor comprises a pixel structure according to any one of the preceding claims 1 to 8.
10. A terminal, characterized in that it comprises an image sensor as claimed in claim 9.
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