A pixel circuit and a display terminal

Abstract

The present invention discloses a pixel circuit and a display terminal. The pixel circuit includes a driving current source, a reset module, an energy storage module, a compensation module, a light emission control module, a PUF module, and a light emission module. When the reset module, the energy storage module, the compensation module, the light emission control module, and the PUF module are in different on-off states, the pixel circuit sequentially realizes reset and driving current compensation, and then the driving current source drives the light emission module to emit light with a constant current. When the compensation module is turned off, the reset module and the PUF module are turned on, the driving current source is connected to an external voltage, and when the driving current source no longer provides driving current for the light emission module, the PUF module compares the voltage at the second end of the driving current source with a reference voltage, and then the PUF module outputs a physically unclonable function. The present invention does not require an additional PUF module, simplifies the system, has a high integration degree, and a low cost; by using the built-in compensation technology of the display technology, the process differences are perfectly eliminated, and the security of the PUF is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of power Internet of Things security, and particularly to a pixel circuit and a display terminal. Background Art

[0002] The power Internet of Things is the application of the Internet of Things in the smart grid and is the result of the development of information and communication technologies. The power Internet of Things will effectively integrate the information and communication infrastructure resources and the power system infrastructure resources, improve the informatization and intelligence levels of the power system, improve the utilization efficiency of the existing power system infrastructure, and provide important technical support for various links such as power generation, transmission, transformation, distribution, and power consumption of the power grid.

[0003] To build a power Internet of Things system, devices with certain sensing, computing, execution, and communication functions are deployed. Through the power information and communication network, an interconnected system with ubiquitous device sensing, miniaturized sensing units, centralized Internet of Things networks, wireless data transmission, and intelligent application analysis is established to realize a network system for identifying, sensing, interconnecting, and controlling power grid equipment, facilities, personnel, and the surrounding environment. The collaboration and interaction between entities in the network enable relevant objects to perceive and feedback control each other, forming a more intelligent power production system and better meeting the monitoring requirements for power equipment.

[0004] As an important means of human-computer interaction, display screens are widely used in various power Internet of Things terminals. For example, in metering terminals such as smart meters, the display screen is used to display information such as power consumption to users in real time; in inspection robot terminals, the display screen is used to display the operation and equipment status of the power system in real time and provide a human-computer interaction interface; in power business hall payment robots, the display screen is used to provide interactive services for power users. Manufacturing process deviations of display screens can provide unique and unpredictable identity identifiers for the above-mentioned power Internet of Things terminals. As an identity authentication factor for terminal devices, it can effectively counter various attack methods such as counterfeiting attacks and improve the security level of the power Internet of Things. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is how to use a display screen to provide a unique and unpredictable identity identifier for a power Internet of Things terminal, and thus provide a pixel circuit and a display terminal.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a pixel circuit, including: a driving current source, a reset module, an energy storage module, a compensation module, a light emitting control module, a PUF module, and a light emitting module; the driving current source, its first end is connected to an external voltage through the light emitting control module, its first end is also connected to its control end through the compensation module, its second end is connected to the first end of the light emitting module through the light emitting control module, its second end is also connected to the display voltage through the compensation module, its second end is also connected to the PUF module, and its control end is connected to a low voltage signal through the reset module; the energy storage module, its first end is connected to the external voltage, and its second end is connected to the control end of the driving current source; when the reset module, the energy storage module, the compensation module, the light emitting control module, and the PUF module are in different on / off states, the pixel circuit sequentially realizes reset and driving current compensation, and then the driving current source drives the light emitting module to emit light with a constant current; when the compensation module is turned off, the reset module and the PUF module are turned on, the driving current source is connected to the external voltage, and when the driving current source no longer provides driving current for the light emitting module, the PUF module compares the voltage at the second end of the driving current source with a reference voltage, and then the PUF module outputs a physically unclonable function.

[0008] In one embodiment, the driving current source includes: a first switching transistor; the first switching transistor, its first end is connected to the external voltage through the light emitting control module, its first end is also connected to its control end through the compensation module, its second end is connected to the first end of the light emitting module through the light emitting control module, its second end is also connected to the display voltage through the compensation module, and its control end is connected to the low voltage signal through the reset module.

[0009] In one embodiment, the reset module includes: a second switching transistor; the second switching transistor, its first end is connected to the control end of the driving current source, and its second end is connected to the low voltage signal.

[0010] In one embodiment, the energy storage module includes: an energy storage capacitor; the energy storage capacitor, its first end is connected to the external voltage, and its second end is connected to the control end of the driving current source.

[0011] In one embodiment, the compensation module includes: a third switching transistor and a fourth switching transistor; the third switching transistor, its first end is connected to the display voltage, and its second end is connected to the second end of the driving current source; the fourth switching transistor, its first end is connected to the control end of the driving current source, and its second end is connected to the first end of the driving current source.

[0012] In one embodiment, the light emitting control module includes: a fifth switching transistor and a sixth switching transistor; the fifth switching transistor, its first end is connected to the first end of the driving current source, and its second end is connected to the external voltage; the sixth switching transistor, its first end is connected to the light emitting module, and its second end is connected to the second end of the driving current source.

[0013] In one embodiment, the light-emitting module includes: a light-emitting diode; the light-emitting diode, whose anode is connected to the second end of the drive current source through a light-emitting control module, and whose cathode is grounded.

[0014] In one embodiment, the PUF module includes: a switch module, a comparator, and a pull-down resistor; the switch module, whose first end is connected to the second end of the drive current source, whose second end is connected to the non-inverting input terminal of the comparator, and whose second end is also grounded through the pull-down resistor; the comparator, whose inverting input terminal is connected to a reference voltage, and whose output terminal outputs a physically unclonable function.

[0015] In one embodiment, the switch module includes: a seventh switching transistor; the seventh switching transistor, whose first end is connected to the second end of the drive current source, whose second end is connected to the non-inverting input terminal of the comparator, and whose second end is also grounded through the pull-down resistor.

[0016] In a second aspect, an embodiment of the present invention provides a display terminal, including: a plurality of pixel circuits of the first aspect.

[0017] The technical solution of the present invention has the following advantages:

[0018] The pixel circuit and the display terminal provided by the present invention, the pixel circuit includes a drive current source, a reset module, an energy storage module, a compensation module, a light-emitting control module, a PUF module, and a light-emitting module. When the reset module, the energy storage module, the compensation module, the light-emitting control module, and the PUF module are in different on-off states, the pixel circuit sequentially realizes reset and drive current compensation, and then the drive current source drives the light-emitting module to emit light with a constant current; when the compensation module is turned off, the reset module and the PUF module are turned on, the drive current source is connected to an external voltage, and when the drive current source no longer provides drive current for the light-emitting module, the PUF module compares the voltage at the second end of the drive current source with the reference voltage, and then the PUF module outputs a physically unclonable function. The present invention does not require an additional PUF module, simplifies the system, has a high integration degree and a low cost; by using the built-in compensation technology of the display technology, the process differences are perfectly eliminated, and the security of the PUF is guaranteed. Description of the Drawings

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a general pixel circuit used in the display screen in the prior art provided by the embodiment of the present invention;

[0021] Figure 2The transistor threshold voltage distribution diagram caused by process deviations provided by the embodiments of the present invention;

[0022] Figure 3 The composition diagram of a specific example of the pixel circuit provided by the embodiments of the present invention;

[0023] Figure 4 The specific circuit topology diagram of the pixel circuit provided by the embodiments of the present invention;

[0024] Figure 5 The timing diagram of the pixel circuit in the normal display state provided by the embodiments of the present invention;

[0025] Figure 6 The timing diagram of the pixel circuit using the PUF module provided by the embodiments of the present invention;

[0026] Figure 7 The schematic diagram of the n-bit key generation method provided by the embodiments of the present invention;

[0027] Figure 8 、 Figure 9 The embodiment of the PUF generation partition method provided by the embodiments of the present invention. Specific Embodiments

[0028] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "linkage" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and can also be the communication inside two components. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0031] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Embodiment 1

[0033] As Figure 1 shown, it is a simplest and most common display pixel circuit. The first switching transistor MOS1 is a current source, which provides a light-emitting current for the light-emitting diode diode, and the light-emitting intensity is related to the current magnitude. However, in actual reality, this circuit structure cannot bring a good display effect because the threshold voltage (Vth) of the first switching transistor MOS1 is unstable due to process problems, which will cause the generated driving current I = k(Vgs - Vth)^2 to be unstable and the display effect to deteriorate. Generally, the threshold voltage distribution of the first switching transistor MOS1 is as Figure 2 shown.

[0034] The embodiment of the present invention provides a pixel circuit, as Figure 3 shown, including: a driving current source 1, a reset module 2, an energy storage module 3, a compensation module 4, a light-emitting control module 5, a PUF module 6, and a light-emitting module 7.

[0035] As Figure 3 shown, for the driving current source 1, its first end is connected to an external voltage Vdd through the light-emitting control module 5, its first end is also connected to its control end through the compensation module 4, its second end is connected to the first end of the light-emitting module 7 through the light-emitting control module 5, its second end is also connected to the display voltage Vdata through the compensation module 4, its second end is also connected to the PUF module 6, and its control end is connected to a low-voltage signal through the reset module 2.

[0036] As Figure 3 shown, for the energy storage module 3, its first end is connected to an external voltage, and its second end is connected to the control end of the driving current source 1.

[0037] Specifically, when the reset module 2, energy storage module 3, compensation module 4, light emission control module 5, and PUF module 6 are in different on-off states, after the pixel circuit sequentially performs reset and drive current compensation, the drive current source 1 drives the light emission module 7 to emit light with a constant current.

[0038] Specifically, the reset module 2, compensation module 4, and light emission control module 5 of the embodiments of the present invention are internally provided with multiple switches. By controlling the on-off states of the switches, the pixel circuit is in a reset state, a compensation state, and a working state.

[0039] Specifically, when the compensation module 4, light emission control module 5, and PUF module 6 are turned off and the reset module 2 is turned on, the pixel circuit is reset. After the pixel circuit is reset, when the reset module 2, light emission control module 5, and PUF module 6 are turned off and the compensation module 4 is turned on, the drive current of the drive current source 1 is compensated. After the drive current of the drive current source 1 is compensated, when the reset module 2, compensation module 4, and PUF module 6 are turned off and the light emission control module 5 is turned on, the drive current source 1 drives the light emission module 7 with a constant current.

[0040] Specifically, resetting is to clear the residual data voltage of the previous frame to ensure the normal operation of the compensation circuit. The main function of the energy storage module 3 is to maintain stable display for one frame time. The compensation module 4 eliminates display non-uniformity. In addition, it can also mask process errors to ensure the security of the PUF.

[0041] Specifically, the physical unclonable function (PUF) utilizes the random process deviations generated during the chip manufacturing process to generate the unique "fingerprint" information of the chip, which can be used as the unique identification information of the chip. Moreover, even for chips that are completely the same in design, after being manufactured, their "fingerprints" are still different, which ensures uniqueness and security. The display manufacturing process also belongs to the semiconductor process, so process deviations will also be generated. Each pixel point has unique characteristics and is not related to each other, and each display screen generates a unique PUF. Therefore, the embodiments of the present invention provide a PUF module 6 to obtain the unique identification information of the pixel circuit.

[0042] Specifically, when the compensation module 4 is turned off, the reset module 2 and the PUF module 6 are turned on, the drive current source 1 is connected to an external voltage, and when the drive current source 1 no longer provides drive current for the light emission module 7, the PUF module 6 compares the voltage at the second end of the drive current source 1 with a reference voltage, and then the PUF module 6 outputs a physical unclonable function.

[0043] Specifically, in the embodiments of the present invention, through the reset module 2, the drive current source 1 is controlled to operate in the saturation region. At this time, I = k(Vgs - Vth)^2, and the drive current source 1 outputs current to the PUF module 6. Different currents cause the PUF module 6 to output 0 or 1 to form a physical unclonable function.

[0044] In a specific embodiment, as Figure 4 shown, the drive current source 1 includes: a first switching transistor MOS1; the first switching transistor MOS1, whose first end is connected to an external voltage through the light-emitting control module 5 (i.e., the fifth switching transistor MOS5), whose first end is also connected to its control end through the compensation module 4 (i.e., the fourth switching transistor MOS4), whose second end is connected to the first end of the light-emitting module 7 (i.e., the light-emitting diode diode) through the light-emitting control module 5 (i.e., the sixth switching transistor MOS6), whose second end is also connected to the display voltage through the compensation module 4 (i.e., the third switching transistor MOS3), and whose control end is connected to a low-voltage signal through the reset module 2 (i.e., the second switching transistor MOS2).

[0045] In a specific embodiment, as Figure 4 shown, the reset module 2 includes: a second switching transistor MOS2; the second switching transistor MOS2, whose first end is connected to the control end of the drive current source 1 (the first switching transistor MOS1), and whose second end is connected to a low-voltage signal.

[0046] In a specific embodiment, as Figure 4 shown, the energy storage module 3 includes: an energy storage capacitor CAP; the energy storage capacitor CAP, whose first end is connected to an external voltage, and whose second end is connected to the control end of the drive current source 1 (the first switching transistor MOS1).

[0047] In a specific embodiment, as Figure 4 shown, the compensation module 4 includes: a third switching transistor MOS3 and a fourth switching transistor MOS4; the third switching transistor MOS3, whose first end is connected to the display voltage, and whose second end is connected to the second end of the drive current source 1 (the first switching transistor MOS1); the fourth switching transistor MOS4, whose first end is connected to the control end of the drive current source 1, and whose second end is connected to the first end of the drive current source 1.

[0048] In a specific embodiment, as Figure 4 shown, the light-emitting control module 5 includes: a fifth switching transistor MOS5 and a sixth switching transistor MOS6; the fifth switching transistor MOS5, whose first end is connected to the first end of the drive current source 1 (the first switching transistor MOS1), and whose second end is connected to an external voltage; the sixth switching transistor MOS6, whose first end is connected to the light-emitting module 7 (the light-emitting diode diode), and whose second end is connected to the second end of the drive current source 1.

[0049] In a specific embodiment, as Figure 4 shown, the light-emitting module 7 includes: a light-emitting diode diode; the light-emitting diode diode, whose anode is connected to the second end of the drive current source 1 (the first switching transistor MOS1) through the light-emitting control module 5 (the sixth switching transistor MOS6), and whose cathode is grounded.

[0050] In a specific embodiment, the PUF module 6 includes: a switch module, a comparator, and a pull-down resistor; the switch module, its first end is connected to the second end of the drive current source 1, its second end is connected to the non-inverting input terminal of the comparator, and its second end is also grounded through the pull-down resistor; the comparator, its inverting input terminal is connected to a reference voltage, and its output terminal outputs a physically unclonable function.

[0051] In a specific embodiment, as Figure 4 shown, the switch module includes: the seventh switch transistor MOS7; the seventh switch transistor MOS7, its first end is connected to the second end of the drive current source 1, its second end is connected to the non-inverting input terminal of the comparator Comparator, and its second end is also grounded through the pull-down resistor R.

[0052] Specifically, based on Figure 4 the topological structure of the pixel circuit shown, the reset state, the compensation state, and the working state will be described below. As Figure 5 shown is the timing diagram during the normal display process. Since P-type transistors are used, the low voltage is in the conducting state. P1, P2, and P3 correspond to the reset, compensation, and working states respectively.

[0053] (1) Reset state

[0054] Figure 5 In the reset state, the second switch transistor MOS2 is conducting, and the third switch transistor MOS3 to the seventh switch transistor MOS7 are all turned off. At this time, the first switch transistor MOS1 realizes the reset.

[0055] (2) Compensation state

[0056] Figure 5 In the compensation state, the third switch transistor MOS3 and the fourth switch transistor MOS4 are conducting, the second switch transistor MOS2, the fifth switch transistor MOS5 to the seventh switch transistor MOS7 are all turned off. At this time, using the transistor characteristics, the threshold voltage Vth is "extracted" from the transistor, so that the working voltage V1 is as shown in Equation (1).

[0057] V1 = Vdata + Vth (1)

[0058] where Vdata is the display voltage.

[0059] (3) Working state

[0060] Figure 5 In the working state, the fifth switch transistor MOS5 and the sixth switch transistor MOS6 are conducting, the second switch transistor MOS2 to the fourth switch transistor MOS4, and the seventh switch transistor MOS7 are turned off. At this time, the first switch transistor MOS1 outputs a constant current to the light-emitting diode diode.

[0061] Specifically, after compensation, it enters the working state. At this time, the driving current I in the working state is: I = k(Vgs - Vth)^2 = k(V1 - Vdd - Vth)^2 = k(Vdata - Vdd)^2 (2)

[0063] Among them, Vdd is the externally connected voltage, and Vgs is the source-drain voltage of the thyristor.

[0064] It can be seen from Equation (2) that there is no longer the unstable value Vth, only Vdata and Vdd. In this case, a good display effect can be obtained and constant current driving can be achieved.

[0065] Specifically, based on Figure 4 the topological structure of the pixel circuit shown, the selection of the PUF control voltage should keep the first switching transistor MOS1 operating in the saturation region. The PUF module 6 can work in the startup stage of each frame, or when the system starts, it can be separately queried whether to run the PUF module 6.

[0066] Specifically, based on Figure 4 the topological structure of the pixel circuit shown, the timing diagram when using the PUF function is as shown in Figure 6 the P0 segment of. At this time, when Gate1, Gate3, and Gate5 are at low level, that is, the second switching transistor MOS2, the fifth switching transistor MOS5, and the seventh switching transistor MOS7 are turned on, and the third switching transistor MOS3, the fourth switching transistor MOS4, and the sixth switching transistor MOS6 are turned off. The PUF module 6 works, and the PUF control gives a gate potential to the first switching transistor MOS1 through the second switching transistor MOS2 to control the first switching transistor MOS1 to work in the saturation region. At this time, the driving current I = k(Vgs - Vth)^2. The current passes through the following resistor. Different Vths cause the module 2 to generate different voltages. Through the comparator, 0 or 1 is output. Generally, the Vref value is the voltage of the module 2 when the probability of Vth is the largest. For example Figure 2 -1.5V in

[0067] Embodiment 2

[0068] The embodiment of the present invention provides a display terminal, including: a plurality of pixel circuits of Embodiment 1.

[0069] Figure 7 is the method for generating the n-bit PUF key of the display terminal. Generally, the key requires dozens to hundreds of bits. Taking the FHD (1920*1080) display as an example, there are about 2 million pixel points. Each pixel point can generate 1 bit of key. n pixel points can be randomly selected to generate the PUF key, or as Figure 8 or Figure 9Similarly, the screen is divided into n regions, and the average value, median value, or other methods can be taken within each region.

[0070] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. The obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A pixel circuit, characterized in that, Comprising: A drive current source, a reset module, an energy storage module, a compensation module, a light-emitting control module, a PUF module, and a light-emitting module; For the drive current source, its first end is connected to an external voltage through the light-emitting control module, its first end is also connected to its control end through the compensation module, its second end is connected to the first end of the light-emitting module through the light-emitting control module, its second end is also connected to a display voltage through the compensation module, its second end is also connected to the PUF module, and its control end is connected to a low-voltage signal through the reset module; For the energy storage module, its first end is connected to an external voltage, and its second end is connected to the control end of the drive current source; When the reset module, the energy storage module, the compensation module, the light-emitting control module, and the PUF module are in different on / off states, after the pixel circuit sequentially realizes reset and drive current compensation, the drive current source drives the light-emitting module to emit light with a constant current; When the compensation module is turned off, the reset module and the PUF module are turned on, the drive current source is connected to an external voltage, and when the drive current source no longer provides drive current for the light-emitting module, the PUF module compares the voltage at the second end of the drive current source with a reference voltage, and then the PUF module outputs a physically unclonable function; The PUF module includes: a switch module, a comparator, and a pull-down resistor; for the switch module, its first end is connected to the second end of the drive current source, its second end is connected to the positive-phase input terminal of the comparator, and its second end is also grounded through the pull-down resistor; for the comparator, its inverting input terminal is connected to a reference voltage, and its output terminal outputs a physically unclonable function; The switch module includes: a seventh switch transistor; for the seventh switch transistor, its first end is connected to the second end of the drive current source, its second end is connected to the positive-phase input terminal of the comparator, and its second end is also grounded through the pull-down resistor.

2. The pixel circuit according to claim 1, wherein The drive current source includes: A first switch transistor; For the first switch transistor, its first end is connected to an external voltage through the light-emitting control module, its first end is also connected to its control end through the compensation module, its second end is connected to the first end of the light-emitting module through the light-emitting control module, its second end is also connected to a display voltage through the compensation module, and its control end is connected to a low-voltage signal through the reset module.

3. The pixel circuit according to claim 1, wherein The reset module includes: A second switch transistor; For the second switch transistor, its first end is connected to the control end of the drive current source, and its second end is connected to the low-voltage signal.

4. The pixel circuit according to claim 1, wherein The energy storage module includes: An energy storage capacitor; For the energy storage capacitor, its first end is connected to an external voltage, and its second end is connected to the control end of the drive current source.

5. The pixel circuit according to claim 1, characterized in that, The compensation module includes: A third switch transistor and a fourth switch transistor; For the third switch transistor, its first end is connected to a display voltage, and its second end is connected to the second end of the drive current source; For the fourth switch transistor, its first end is connected to the control end of the drive current source, and its second end is connected to the first end of the drive current source.

6. The pixel circuit according to claim 1, wherein The light-emitting control module includes: A fifth switch transistor and a sixth switch transistor; The fifth switching transistor has its first end connected to the first end of the driving current source, and its second end connected to the external voltage. The sixth switching transistor has its first end connected to the light-emitting module, and its second end connected to the second end of the driving current source.

7. The pixel circuit according to claim 1, wherein The light-emitting module includes: A light-emitting diode; For the light-emitting diode, its anode is connected to the second end of the driving current source through the light-emitting control module, and its cathode is grounded.

8. A display terminal, characterized in that, It includes: Multiple pixel circuits according to any one of claims 1-7.

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