CN216207039U - High-sensitivity color sensor based on thin film transistor - Google Patents
High-sensitivity color sensor based on thin film transistor Download PDFInfo
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- CN216207039U CN216207039U CN202122791563.5U CN202122791563U CN216207039U CN 216207039 U CN216207039 U CN 216207039U CN 202122791563 U CN202122791563 U CN 202122791563U CN 216207039 U CN216207039 U CN 216207039U
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Abstract
The utility model provides a high-sensitivity color sensor based on a thin film transistor, which comprises a preposed amplifying circuit based on the thin film transistor, wherein the preposed amplifying circuit is composed of a first thin film transistor TFT1, a second thin film transistor TFT2, a third thin film transistor TFT3 and a fourth thin film transistor TFT4, the first thin film transistor TFT1 and the second thin film transistor TFT2 form a current conversion voltage circuit, the third thin film transistor TFT3 and the fourth thin film transistor TFT4 form a common source amplifying circuit, the current conversion voltage circuit converts a weak current related to illumination intensity into a voltage related to the illumination intensity and outputs the voltage to the common source amplifying circuit, and the common source amplifying circuit amplifies and outputs the voltage related to the illumination intensity. The utility model has the beneficial effects that: the thin film transistor is used as the photoelectric detector, so that the sensitivity of the color sensor is improved, the color sensor can be used for a flexible panel, and the cost is reduced.
Description
Technical Field
The present invention relates to color sensors, and more particularly, to a high-sensitivity color sensor based on thin film transistors.
Background
The traditional color sensor is mainly based on a photodiode, is a passive sensor, has no internal gain and has lower sensitivity.
Therefore, how to improve the sensitivity of the color sensor is an urgent technical problem to be solved by the skilled person.
Disclosure of Invention
To solve the problems in the prior art, the present invention provides a high-sensitivity color sensor based on a thin film transistor.
The utility model provides a high-sensitivity color sensor based on a thin film transistor, which comprises a preposed amplifying circuit based on the thin film transistor, wherein the preposed amplifying circuit is composed of a first thin film transistor TFT1, a second thin film transistor TFT2, a third thin film transistor TFT3 and a fourth thin film transistor TFT4, the first thin film transistor TFT1 and the second thin film transistor TFT2 form a current conversion voltage circuit, the third thin film transistor TFT3 and the fourth thin film transistor TFT4 form a common source amplifying circuit, the current conversion voltage circuit converts a weak current related to illumination intensity into a voltage related to the illumination intensity and outputs the voltage to the common source amplifying circuit, and the common source amplifying circuit amplifies and outputs the voltage related to the illumination intensity.
As a further improvement of the present invention, the common source amplifying circuit amplifies the voltage related to the illumination intensity and outputs the amplified voltage to the rear logic computing unit, and after the voltage is computed by the rear logic computing unit, the voltage value is computed into a corresponding RGB value and is output through the standard output interface.
As a further improvement of the present invention, the first thin film transistor TFT1 is used for receiving light, and the input signal is the intensity of the light.
As a further improvement of the present invention, the first thin film transistor TFT1 and the fourth thin film transistor TFT4 both use double-gate thin film transistors.
As a further improvement of the present invention, the second thin film transistor TFT2 and the third thin film transistor TFT3 may be double-gate thin film transistors, or may be ordinary single-gate thin film transistors.
As a further improvement of the present invention, a filter is disposed corresponding to the top gate of the first thin film transistor TFT1, and the input light (e.g., white light) is received by the top gate of the first thin film transistor TFT1 after being filtered by the filter.
As a further improvement of the present invention, the drain of the first thin film transistor TFT1 is connected to a power supply voltage, the source of the first thin film transistor TFT1 and the drain of the second thin film transistor TFT2 are connected to a point a, the source of the second thin film transistor TFT2 is grounded, the drain and the gate of the third thin film transistor TFT3 are connected to the power supply voltage, the source of the third thin film transistor TFT3 and the drain of the fourth thin film transistor TFT4 are connected to a point B for outputting a voltage, the source of the fourth thin film transistor TFT4 is grounded, the bottom gate of the fourth thin film transistor TFT4 and the gate of the second thin film transistor TFT2 are connected to a point a, a voltage positively correlated to the illumination intensity is generated at the point a after a current flows through the second thin film transistor TFT2, and then the voltage at the point a is connected to the bottom gate of the fourth thin film transistor TFT4, and the common source amplifier circuit is composed of the third thin film transistor TFT3 and the fourth thin film transistor 4, the voltage at the point A is amplified, and the amplified voltage signal is output from the point B.
As a further improvement of the present invention, a bias voltage is applied to the bottom gate of the first thin film transistor TFT1, and a bias voltage is applied to the top gate of the fourth thin film transistor TFT 4.
As a further improvement of the present invention, the width-to-length ratio of the fourth thin film transistor TFT4 is larger than the width-to-length ratio of the third thin film transistor TFT 3.
As a further improvement of the present invention, the ratio of the width-to-length ratio of the fourth thin film transistor TFT4 to the width-to-length ratio of the third thin film transistor TFT3 is between 10 and 100 times.
As a further improvement of the present invention, the width-to-length ratios of the first thin film transistor TFT1, the second thin film transistor TFT2, and the third thin film transistor TFT3 are the same.
As a further improvement of the present invention, the input light (e.g. white light) is filtered by different filters to obtain different colors, and the different colors correspond to different preamplification circuits.
The utility model has the beneficial effects that: by adopting the scheme, the thin film transistor is used as the photoelectric detector, so that the sensitivity of the color sensor is improved, and the cost is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced 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 that other solutions can be obtained according to the drawings without inventive efforts.
Fig. 1 is a circuit diagram of a preamplifier of a high-sensitivity color sensor based on a thin film transistor according to the present invention.
Fig. 2 is a simulation structure of a pre-amplification circuit diagram of a high-sensitivity color sensor based on a thin film transistor according to the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The utility model is further described with reference to the following description and embodiments in conjunction with the accompanying drawings.
As shown in fig. 1 to 2, a thin film transistor-based high-sensitivity color sensor includes a thin film transistor-based preamplifier circuit, which is composed of a first thin film transistor TFT1, a second thin film transistor TFT2, a third thin film transistor TFT3 and a fourth thin film transistor TFT4, the first thin film transistor TFT1 and the second thin film transistor TFT2 form a current-to-voltage conversion circuit, the third thin film transistor TFT3 and the fourth thin film transistor TFT4 form a common source amplifier circuit, the current-to-voltage conversion circuit converts a weak current related to illumination intensity into a voltage related to illumination intensity and outputs the voltage to the common source amplifier circuit, the common source amplifier circuit amplifies the voltage related to illumination intensity and outputs the amplified voltage to a rear-end logic calculation unit 4, and after calculation by the rear-end logic calculation unit, the voltage values are calculated into corresponding RGB values, and output through a standard output interface.
The first thin film transistor TFT1 is used for receiving light, and its input signal is light intensity.
The first thin film transistor TFT1 and the fourth thin film transistor TFT4 both use double-gate thin film transistors.
The top gate of the first thin film transistor TFT1 is correspondingly provided with a filter, and the white light is filtered by the filter and then received by the top gate of the first thin film transistor TFT 1.
A drain of the first thin film transistor TFT1 is connected to a power supply voltage, a source of the first thin film transistor TFT1 and a drain of the second thin film transistor TFT2 are connected to a point a, a source of the second thin film transistor TFT2 is grounded, a drain and a gate of the third thin film transistor TFT3 are respectively connected to the power supply voltage, a source of the third thin film transistor TFT3 and a drain of the fourth thin film transistor TFT4 are connected to a point B for outputting a voltage, a source of the fourth thin film transistor TFT4 is grounded, a bottom gate of the fourth thin film transistor TFT4 and a gate of the second thin film transistor TFT2 are connected to a point a, a voltage positively correlated to an illumination intensity is generated at the point a after a current flows through the second thin film transistor TFT2, and then the voltage at the point a is connected to the bottom gate of the fourth thin film transistor TFT4, and a common source amplifier circuit composed of the third thin film transistor TFT3 and the fourth thin film transistor TFT4, the voltage at the point A is amplified, and the amplified voltage signal is output from the point B.
A bias voltage is applied to the bottom gate of the first thin film transistor TFT1, and a bias voltage is applied to the top gate of the fourth thin film transistor TFT 4.
The width-to-length ratio of the fourth thin film transistor TFT4 is greater than the width-to-length ratio of the third thin film transistor TFT 3.
The ratio of the width-to-length ratio of the fourth thin film transistor TFT4 to the width-to-length ratio of the third thin film transistor TFT3 is between 10 and 100 times.
The width-to-length ratios of the first thin film transistor TFT1, the second thin film transistor TFT2, and the third thin film transistor TFT3 are the same.
The white light is filtered by different optical filters to obtain different colors, the different colors correspond to different pre-amplification circuits, the optical filters comprise a red optical filter, a green optical filter and a blue optical filter, and the number of the pre-amplification circuits is three, namely a first pre-amplification circuit, a second pre-amplification circuit and a third pre-amplification circuit; the white light passes through the red light filter to obtain red light, and the red light is received by a first thin film transistor TFT1 of the corresponding first preamplifier circuit; after the white light passes through the green light filter, green light is obtained, and the green light is received by a first thin film transistor TFT1 of the corresponding second pre-amplification circuit; the white light passes through the blue light filter to obtain blue light, and the blue light is received by the first thin film transistor TFT1 of the corresponding third pre-amplifier circuit.
The utility model provides a high-sensitivity color sensor based on a thin film transistor, which has the following working principle:
the pre-amplification circuit based on the thin film transistor adopts a structure that a current conversion voltage circuit is combined with a common source amplification circuit, the pre-amplification circuit outputs voltage related to illumination intensity, weak current related to the illumination intensity is converted into voltage, and the voltage amplified by the common source amplification circuit is more convenient for processing of a logic calculation unit at the rear end, and meanwhile, the detection limit of the color sensor is improved.
As shown in fig. 1, after the white light passes through the red, green and blue filters and is received by the thin film transistors of different preamplification circuits, the white light acts on the channels of the thin film transistors to excite more electrons to flow through the thin film transistors. At this time, the TFT1 in fig. 1 is used as a thin film transistor for receiving light, the input signal is the intensity of light, and the preamplification circuits of different colors are separated. The current flowing through the second TFT2 generates a voltage at point a that is positively correlated to the intensity of the light. Then, the voltage at the point a is connected to the gate of the fourth thin film transistor TFT4, and the third thin film transistor TFT3 and the fourth thin film transistor TFT4 form a common source amplifying circuit, so that the voltage at the point a is amplified and output, and the amplified voltage signal is output to a rear logic computing unit.
In fig. 1, the top gate level of the first thin film transistor TFT1 is indicated by a dashed line because it needs to be transparent.
In the common-source amplifying circuit, the fourth thin film transistor TFT4 adopts a dual-gate thin film transistor structure, and there is one more top gate TG than the common thin film transistor, i.e. the fourth thin film transistor TFT4 has a source S, a drain D, a bottom gate bg (bottom gate), and a top gate TG (top gate), which facilitates adjusting the operating state of the transistor.
In the circuit, the width-to-length ratio of the fourth thin film transistor TFT4 is as much as possible larger than that of the third thin film transistor TFT3, the width-to-length ratio of the two TFTs is about 10 times to 100 times, the occupied area of the fourth thin film transistor TFT4 is reduced as the ratio is smaller, the occupied area of the corresponding whole circuit is reduced, but the obtained amplification factor is smaller; the larger the scale factor, the larger the obtained amplification factor, the larger the output voltage variation range, but it causes a problem that the input voltage range is reduced, and the area occupied by the fourth thin film transistor TFT4 is increased, which causes a problem that the layout is too compact when the array is arranged. Therefore, the aspect ratio of the fourth thin film transistor 4 to the third thin film transistor 3 is preferably in the range of about 10 to 100 times.
Fig. 2 is a simulation result of the preamplifier circuit, at this time, the power voltage is set to be 5V, the top gate bias of the fourth thin film transistor TFT4 is-1.5V, the width-to-length ratio of the first thin film transistor TFT1, the second thin film transistor TFT2, and the third thin film transistor TFT3 is 10um/10um, and the width-to-length ratio of the fourth thin film transistor TFT4 is 100um/10um, and it is assumed that the light intensity current flowing through the first thin film transistor TFT1 is a sine wave under the light intensity irradiation. Simulation results show that after the action of the second thin film transistor TFT2, the light intensity current is converted into a point a voltage, the point a voltage and the light intensity current at this time are in positive correlation, the output voltage amplitude is 0 to 3V, after passing through a common source amplifying circuit composed of the third thin film transistor TFT3 and the fourth thin film transistor TFT4, the output voltage amplitude is 1.2 to 4.8V, the difference is larger than the point a voltage, and the voltage amplifying function is achieved. Meanwhile, the preamplification circuit also plays a role in isolating input and output.
According to the high-sensitivity color sensor based on the thin film transistor, the thin film transistor is used as the photoelectric detector, so that the sensitivity of the color sensor is improved, the preparation cost of the sensor can be greatly reduced, the detection limit of the color sensor is improved, the detection range and the accuracy of the color sensor are improved, and the function of isolating input and output is achieved.
The high-sensitivity color sensor based on the thin film transistor can be used for a flexible panel.
The foregoing is a more detailed description of the utility model in connection with specific preferred embodiments and it is not intended that the utility model be limited to these specific details. For those skilled in the art to which the utility model pertains, several simple deductions or substitutions can be made without departing from the spirit of the utility model, and all shall be considered as belonging to the protection scope of the utility model.
Claims (8)
1. A high sensitivity color sensor based on thin film transistors, characterized by: the light-emitting diode comprises a preposed amplifying circuit based on a thin film transistor, wherein the preposed amplifying circuit is composed of a first thin film transistor TFT1, a second thin film transistor TFT2, a third thin film transistor TFT3 and a fourth thin film transistor TFT4, the first thin film transistor TFT1 and the second thin film transistor TFT2 form a current conversion voltage circuit, the third thin film transistor TFT3 and the fourth thin film transistor TFT4 form a common source amplifying circuit, the current conversion voltage circuit converts weak current related to illumination intensity into voltage related to the illumination intensity and outputs the voltage to the common source amplifying circuit, and the common source amplifying circuit amplifies and outputs the voltage related to the illumination intensity.
2. The thin film transistor-based high sensitivity color sensor of claim 1, wherein: the first thin film transistor TFT1 is used for receiving light, and its input signal is light intensity.
3. The thin film transistor-based high sensitivity color sensor of claim 2, wherein: the first thin film transistor TFT1 and the fourth thin film transistor TFT4 both use double-gate thin film transistors.
4. The thin film transistor-based high sensitivity color sensor of claim 3, wherein: the top gate of the first thin film transistor TFT1 is correspondingly provided with an optical filter, and input light is received by the top gate of the first thin film transistor TFT1 after being filtered by the optical filter.
5. The thin film transistor-based high sensitivity color sensor of claim 4, wherein: a drain of the first thin film transistor TFT1 is connected to a power supply voltage, a source of the first thin film transistor TFT1 and a drain of the second thin film transistor TFT2 are connected to a point a, a source of the second thin film transistor TFT2 is grounded, a drain and a gate of the third thin film transistor TFT3 are respectively connected to the power supply voltage, a source of the third thin film transistor TFT3 and a drain of the fourth thin film transistor TFT4 are connected to a point B for outputting a voltage, a source of the fourth thin film transistor TFT4 is grounded, a bottom gate of the fourth thin film transistor TFT4 and a gate of the second thin film transistor TFT2 are connected to a point a, a voltage positively correlated to an illumination intensity is generated at the point a after a current flows through the second thin film transistor TFT2, and then the voltage at the point a is connected to the bottom gate of the fourth thin film transistor TFT4, and a common source amplifier circuit composed of the third thin film transistor TFT3 and the fourth thin film transistor TFT4, the voltage at the point A is amplified, and the amplified voltage signal is output from the point B.
6. The thin film transistor-based high sensitivity color sensor of claim 1, wherein: the width-to-length ratio of the fourth thin film transistor TFT4 is greater than the width-to-length ratio of the third thin film transistor TFT 3.
7. The thin film transistor-based high sensitivity color sensor of claim 1, wherein: the width-to-length ratios of the first thin film transistor TFT1, the second thin film transistor TFT2, and the third thin film transistor TFT3 are the same.
8. The thin film transistor-based high sensitivity color sensor of claim 1, wherein: the input light is filtered by different optical filters to obtain different colors, and the different colors correspond to different preamplification circuits.
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| CN202122791563.5U CN216207039U (en) | 2021-11-15 | 2021-11-15 | High-sensitivity color sensor based on thin film transistor |
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| CN202122791563.5U CN216207039U (en) | 2021-11-15 | 2021-11-15 | High-sensitivity color sensor based on thin film transistor |
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