Electronic device and electronic circuit thereof
By designing a transistor with a linear operating area with high output admittance in the LED driving circuit, and combining a detection unit and a feedback control unit, the problem of high power consumption in traditional LED driving technology is solved, and the LED driving effect with low power consumption is achieved.
Patent Information
- Application Number
- JP2024166535
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-29
- Filing Date
- 2024-09-25
- Publication Date
- 2025-04-30
AI Technical Summary
In traditional LED driving technology, the driving current control transistor operates in the saturated area, resulting in an increase in power consumption, making it difficult to meet the low power consumption demand.
An electronic circuit is designed, including a transistor that controls the driving signal, a detection unit and a feedback control unit. The transistor operates in a linear operating area with high output admittance, and the drive signal is adjusted by a detection unit and a feedback control unit to reduce power consumption.
Through transistors operating in the linear operation area and effective feedback control, precise adjustment of LED driving current is achieved, power consumption of the circuit is reduced, and the demand for low power consumption is met.
Smart Images
Figure 2025069062000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to electronic circuits and electronic devices that use such circuits. [Background technology]
[0002] Conventional LED driving technology uses a current control transistor to adjust the current flowing through the LED. See Figure 1. The transistor usually works in the saturation region, and in the ideal case, the drain electrode current is entirely determined by the gate electrode and source electrode voltage (the voltage from the transistor gate electrode to the transistor source electrode) and is not affected by the change in the source-drain voltage (the voltage from the transistor drain electrode to the transistor source electrode). This working principle ensures the consistency of the LED driving current, and the characteristics of the LED, such as the LED's DC voltage, change due to the manufacturing process change or the effect of temperature, which further affects the source-drain voltage. The current control transistor and the LED are electrically connected in a series connection manner, so any change in the LED's characteristics affects the source-drain voltage, but does not affect the driving current Id. VD, VDD, and VG stand for drain voltage, power supply voltage, and gate voltage, respectively.
[0003] However, such prior art techniques require a trade-off between the two. Operation in the saturation region results in a higher source-drain voltage compared to operation in the non-saturation region, which increases the power consumption of the drive current control transistor. Summary of the Invention [Problem to be solved by the invention]
[0004] An object of the present invention is to provide an electronic circuit and an electronic device, in which a light emitting element is driven by a driving current control transistor, and the requirement of low power consumption is met. [Means for solving the problem]
[0005] The present invention provides an electronic device, which includes a substrate, a plurality of light-emitting elements, and a plurality of driving circuits. The plurality of light-emitting elements are disposed on the substrate, and the plurality of driving circuits are respectively electrically connected to the plurality of light-emitting elements. The light-emitting elements emit light according to a driving signal, and the driving signal may be a driving current. The driving circuit includes a transistor for controlling the driving signal, a detection unit, and a feedback control unit. The transistor includes an input terminal and two output terminals, and transmits a driving signal (e.g., a driving current) to one or more corresponding light-emitting elements via one of the two output terminals. The transistor for controlling the driving signal defines a characteristic curve, which is defined by an output current of the transistor and a voltage difference value between the two output terminals of the transistor. The characteristic curve further defines an operating region and an output conductance within the operating region, and the output conductance is an absolute value of a ratio between a change in the output current of the transistor and a change in the voltage difference value. The operating region defines a first region and a second region, and the output conductance of the first region is greater than the output conductance of the second region, and the transistor for controlling the driving signal of the present invention operates within the first region. The detection unit provides a detection output through one of the corresponding light emitting elements. The feedback control unit guides the transistor to adjust and control the driving signal, for example, to adjust and control the driving current.
[0006] The present invention provides an electronic circuit, which includes a plurality of light emitting elements and a plurality of driving circuits, and the plurality of driving circuits are respectively electrically connected to a corresponding plurality of light emitting elements. The light emitting elements emit light according to a driving signal (e.g., a driving current). The driving circuit includes a transistor for controlling the driving signal, a detection unit, and a feedback control unit. The transistor includes an input end and two output ends, and transmits the driving signal to one or more corresponding light emitting elements via one of the two output ends. The transistor defines a characteristic curve, which is defined by an output current of the transistor and a voltage difference value between the two output ends of the transistor. The characteristic curve further defines an operating region and an output conductance within the operating region. The output conductance is an absolute value of a ratio between a change in the output current of the transistor and a change in the voltage difference value. The operating region defines a first region and a second region, and the output conductance in the first region is greater than the output conductance in the second region, and the transistor used for controlling the driving signal operates within the first region. The detection unit provides a detection output according to one of the corresponding light emitting elements. The feedback control unit guides the transistor to adjust and control the driving signal. Furthermore, the electronic circuitry can be modularized.
[0007] The above electronic device or electronic circuit has the following features.
[0008] In one embodiment, the transistors controlling the drive signals are bipolar junction transistors (BJT), insulated gate bipolar transistors (IGBT) or field-effect transistors (FET).
[0009] In one embodiment, the types of field effect transistors (FETs) include metal oxide semiconductor field effect transistors (MOSFETs), metal semiconductor field effect transistors (MESFETs) and thin film transistors (TFTs), and the transistor controlling the driving signal may be one of them.
[0010] In one embodiment, the transistor that controls the driving signal is a field effect transistor (FET); the input end of the transistor is a gate electrode, and the two output ends are a drain electrode and a source electrode; the first region of the characteristic curve of the transistor is the linear region of the FET, and the second region is the saturation region of the FET.
[0011] In one embodiment, at least a portion of one or more of the drive circuits is disposed on the substrate.
[0012] In one embodiment, the detection unit senses light from one of the corresponding light emitting elements and provides a detection output according to the sensed light.
[0013] In one embodiment, the detection unit includes a photodiode.
[0014] In one embodiment, the detection unit is a thin film formed on the substrate.
[0015] In one embodiment, the photodiode is a thin film formed on a substrate.
[0016] In one embodiment, the detection unit senses a driving signal that drives a corresponding light-emitting element, and provides a detection output according to the driving signal.
[0017] In one embodiment, the detection unit includes a resistor and a feedback control unit, the resistor and the corresponding light-emitting element are electrically connected in a series connection manner, and the feedback control unit instructs the transistor to control the driving signal according to the voltage drop across the resistor.
[0018] In one embodiment, at least a portion of the drive circuitry is formed on the substrate.
[0019] In one embodiment, at least a portion of the driver circuitry is implemented on an integrated circuit.
[0020] In one embodiment, the light emitting elements define a voltage drop of the light emitting elements, one of which is that the voltage difference value of the transistor controlling the driving signal is less than or equal to the voltage drop of the corresponding light emitting element.
[0021] In one embodiment, the voltage difference value of one of the transistors controlling the driving signal is less than or equal to two-thirds of the voltage drop of the corresponding light emitting element.
[0022] In one embodiment, the voltage difference value of one of the transistors controlling the driving signal is less than or equal to half the voltage drop of the corresponding light emitting element. [Brief description of the drawings]
[0023] [Figure 1] FIG. 1 is a diagram showing a conventional electric circuit for driving a light-emitting element. [Diagram 2] FIG. 2 is a diagram showing an electric circuit of an embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing curve characteristics of the output current-voltage difference value of the transistor of FIG. 2. [Figure 4] FIG. 4 is an electrical circuit diagram of another embodiment of the present invention. [Diagram 5] FIG. 4 is an electrical circuit diagram of another embodiment of the present invention. [Figure 6] FIG. 4 is an electrical circuit diagram of another embodiment of the present invention. [Figure 7] FIG. 4 is an electrical circuit diagram of another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The following describes the embodiments of the electronic device of the present invention with reference to the drawings. The same elements are denoted by the same reference numerals. The ratio between elements in the drawings is for the purpose of understanding the structure, and is not intended to be limiting.
[0025] Fig. 2 shows an embodiment of the present invention. The electronic device 100 in Fig. 2 mainly includes a substrate 10, a number of light emitting elements 20, and a number of driving circuits 30. The light emitting elements 20 are mounted on the substrate 10, and the driving circuits 30 are electrically connected to the light emitting elements 20 respectively.
[0026] The one or more light emitting elements 20 emit light in response to a corresponding driving signal Sdr, where the driving signal Sdr is, for example, a driving current IL. The driving circuit 30 includes a driving current control transistor 40 (hereinafter, abbreviated as “transistor 40”), a detection unit 50, and a feedback control unit 60. The transistor 40 controls the driving signal Sdr, and thus the transistor 40 is a driving current control transistor 40.
[0027] In this embodiment, the transistor 40 is, for example, a thin film transistor (TFT), which includes one input terminal and two output terminals, and transmits a driving signal Sdr (derived from the driving current IL) to one or more corresponding light-emitting elements 20 through one of the two output terminals. When the transistor 40 is directly or indirectly electrically connected to the corresponding light-emitting element 20, at least one extra element can be installed between them. The transistor 40 defines a characteristic curve as shown in FIG. 3, which is created from the relationship between the output current of the transistor 40 and the voltage difference value between the two output terminals of the transistor 40. The characteristic curve defines an operating region and an output conductance within the operating region, and the output conductance is the absolute value of the ratio between the output current change of the transistor and the voltage difference value change. It should be noted that the characteristic curve shown in FIG. 3 is an example, and does not limit the scope of the present invention.
[0028] 3, the operating region of the characteristic curve further defines a first region (Region 1) and a second region (Region 2), with the output conductance of the first region (Region 1) being greater than the output conductance of the second region (Region 2). Transistor 40 operates in the first region (Region 1).
[0029] The detection unit 50 detects a driving signal Sdr for driving at least one corresponding light-emitting element 20, and provides a detection output Sde according to the driving signal Sdr.
[0030] The feedback control unit 60 provides a feedback output Sfe to direct the transistor 40 to adjust the drive signal Sdr, eg, the drive current IL.
[0031] The transistor 40 operates in the first region of the operating region of the characteristic curve, and adjusts the driving signal Sdr, for example, to reduce the driving current IL and its power consumption. In other words, the driving signal Sdr is determined by the feedback output Sfe provided by the feedback control unit 60, which is obtained by the detection unit 50 detecting the light emitted by the corresponding light-emitting element 20.
[0032] It should be noted that the substrate 10 of the present invention can be designed in various ways, for example, one or more wiring layers or other electronic elements can be provided. Furthermore, the number of transistors provided in the driving circuit 30 is greater than the number of transistors 40 shown in FIG. 2. Although the wiring layers are usually provided independently in the driving circuit 30, for the sake of simplicity and easy understanding, the wiring layers and other electronic elements are included in the general noun, for example, in the driving circuit 30 of the present invention. Furthermore, "corresponding" or "corresponding" in this specification clearly means a one-to-one correspondence, but may also be a one-to-many correspondence, a many-to-many correspondence, or a many-to-one correspondence.
[0033] In one case, at least a portion of the drive circuitry 30 is disposed on the substrate 10 .
[0034] In one embodiment, substrate 10 may be transparent or opaque, flexible or rigid, and may be a single layer or a composite of one or more layers.
[0035] In one embodiment, the light emitting device 20 may be a conventional light emitting diode (LED), a millimeter LED (mini LED) or a micro LED (micro LED), and may be an organic or inorganic light emitting diode, or in another embodiment, the light emitting device 20 may be an EL device, such as a quantum dot light emitting device.
[0036] In one case, at least a portion of one or more driving circuits 30 is formed on the substrate 10, in particular, at least a portion of a thin film can be formed on the substrate 10 through a thin film manufacturing process. A transistor 40 for controlling a driving signal can be formed as a thin film on the substrate 10 through a thin film manufacturing process. In another case, at least a portion of the driving circuit 30 is provided on an integrated circuit (IC), and the transistor 40 for controlling a driving signal can be formed inside the IC.
[0037] The transistor 40 that controls the driving signal can be a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT) or a field effect transistor (FET). The field effect transistor (FET) includes a metal oxide semiconductor field effect transistor (MOSFET), a metal semiconductor field effect transistor (MESFET) and a thin film transistor (TFT). It should be noted that the characteristic curve of each type of transistor 40 that controls the driving signal meets the above standard and the display in FIG. 3.
[0038] The following are other embodiments of the present invention, which are shown in FIG. 4 to FIG.
[0039] The electronic device 100a shown in FIG. 4 includes a detection unit 50a, which senses the light emitted by the corresponding light-emitting element 20a, and provides a detection output in response to the emitted light. In this embodiment, a photodiode 52a is used to detect the light of the target light-emitting element 20. And the photodiode 52a is formed on the substrate 10 through a thin film manufacturing process. In one case, the photodiode 52a is a thin film element formed on the substrate 10. The feedback control unit 60a instructs the transistor 40 (TFT in this embodiment) to adjust the driving current IL according to the detection result of the detection unit 50a detecting the light emitted by the target light-emitting element 20a.
[0040] In this embodiment, the light-emitting element 20a is driven by a driving current IL. After the light emitted by the light-emitting element 20a is detected by the photodiode 52a, the photodiode 52a generates a current Ip. After the current Ip passes through a feedback control unit 60a (e.g., a feedback circuit), a feedback current Ife is generated that is directly proportional to the current Ip. The feedback current Ife keeps the transistor 40, which controls the driving signal, operating in a first region (region 1) of the operating region.
[0041] In FIG. 2 and FIG. 4, the transistor 40 controlling the driving signal is a MOSFET (or TFT), the linearity region is the first region of the characteristic curve, and the saturation region is the second region of the characteristic curve.
[0042] In FIG. 5, the transistor 40a' for controlling the driving signal of the electronic device 100' is a BJT, not a MOSFET (or TFT). In this case, the transistor 40a' (BJP) of the electronic device 100a' is also applied to the design concept that the light emitting element 20a' in the electronic device 100a is driven by the driving current IL. The light emitted by the light emitting element 20a' is detected by the photodiode 52a', and then the photodiode 52a' generates a current Ip. After the current Ip passes through the feedback control unit 60a' (e.g., a feedback circuit), a feedback current Ife is generated that is directly proportional to the current Ip. In this embodiment, the saturation region of the characteristic curve of the transistor 40a' is the first region, and the operating region is the second region of the characteristic curve of the transistor 40a'.
[0043] In FIG. 6, the electronic device 100b has a transistor 40b for controlling the driving signal, which is an insulated gate bipolar transistor, and the saturation region is the first region of the characteristic curve, and the operating region is the second region of the characteristic curve. The technical features of FIG. 6 are the same as those of FIG. 4 and FIG. 5. The electronic device 100b includes a detection unit 50b, which senses the light emitted by the corresponding light-emitting element 20b, and provides a detection output according to the emitted light. In this embodiment, a photodiode 52b is used to detect the light emitted by the target light-emitting element 20b. The feedback control unit 60b detects the detection output of the light emitted by the target light-emitting element 20b through the detection unit 50b, and instructs the transistor 40b for controlling the driving signal to adjust the driving current IL. In detail, the light emitted by the light-emitting element 20b is detected by the photodiode 52b, which generates a current Ip, and the current Ip passes through the feedback control unit 60b, resulting in a feedback current Ife that is directly proportional to the current Ip. The feedback current Ife keeps the transistor 40b operating in the first region of its operating range and adjusts and controls the drive current IL delivered to the targeted light emitting element 20b.
[0044] In Fig. 7, the electronic device 100c provides a detection unit 50c, which senses the current from the corresponding light emitting element 20c and provides a detection output according to the current of the light emitting element 20c. In this embodiment, the detection unit 50c includes a resistor 52c with a resistance value R, and the resistor 52c and one of the corresponding light emitting elements 20c are electrically connected in a series connection manner, and the feedback control unit 60c indicates the transistor 40 (e.g., TFT) to control the driving signal according to the voltage drop of the resistor 52c. In this case, the resistor 52c is installed between the transistor 40c and the light emitting element 20c. In addition, the detection unit 50c and the feedback control unit 60c include an expander, and each expander defines coefficients α and β. The equations for more detailed explanation are given below.
[0045] ((Vdata-IL * R * α) * β-Vt) * Vds * k = I L Eq. 1
[0046] IL * (R * α * β * k+1)=(Vdata * β-Vt) * Vds * k...expression 2
[0047] K is a coefficient to which the transconductance of the transistor 40c is directly proportional; Vdata is a data voltage transmitted to the driver circuit 30; Vt is a threshold voltage of the transistor 40c; and Vds is a voltage of the transistor 40c from the drain electrode to the source electrode.
[0048] If β is large enough, the drive current IL is Vdata / (R * Resistor 52c is considered a current-sensing resistor, but if the resistance R is low enough, the voltage drop across resistor 52c and the power dissipation are also low. The value of Vdata / α (this value is IL *Low power consumption can be achieved simply by considering the
[0049] In FIG. 7, transistor 40c is a BJT or an IGBT.
[0050] In one embodiment, the light emitting element 20 and the transistor 40 controlling the driving signal correspond to each other. The light emitting element 20 defines a voltage drop, and the voltage difference value of the transistor 40 controlling the driving signal is less than or equal to the voltage drop of the corresponding light emitting element 20. In one embodiment, the voltage difference value of the transistor 40 is less than or equal to two-thirds of the voltage drop of the corresponding light emitting element 20. Furthermore, the voltage difference value of the transistor 40 is less than or equal to half of the voltage drop of the corresponding light emitting element 20.
[0051] Thus, the electronic device of the present invention has a number of light-emitting elements, which are adjusted and controlled by a number of driving circuits. The driving circuits determine the light-emitting brightness of the light-emitting elements by controlling the amount of current passing through the light-emitting elements. The transistors controlling the driving signals operate in a first region of the operating region and output a driving current Id to reduce their own power consumption. The feedback control unit detects the current or light from the target light-emitting element and provides a feedback output to determine the driving current IL to be output. In other words, the electronic device of the present invention maintains a high output conductance of the electronic device and reduces power consumption by the transistors operating in a specific first region of the operating region. The driving circuit of the present invention ensures that the driving current Id is maintained at a required level by the feedback control unit. In summary, the design of the driving circuit of the present invention is more efficient in terms of power consumption than the design of conventional driving circuits. This has many advantages, such as reducing the energy consumption of lighting systems and extending the battery life of portable devices.
[0052] The foregoing is intended to be illustrative and not limiting, and all modifications or variations thereto that do not depart from the scope of the claims of the present invention are intended to be within the scope of the appended claims. [Explanation of symbols]
[0053] 100, 100a, 100a', 100b, 100c electronic equipment 10, 10a, 10a', 10b, 10c base material 20, 20a, 20a', 20b, 20c Light emitting element 30 Drive circuit 40, 40a, 40a', 40b, 40c transistors 50, 50a, 50a', 50b, 50c Detection unit 52a, 52a', 52b Photodiodes 52c resistor 60, 60a, 60a', 60b, 60c Feedback control unit Id, IL Drive current Ife Feedback current Ip current Sdr drive signal Sfe Feedback Output Sde detection output R resistor
Claims
1. An electronic device comprising: a substrate; a plurality of light-emitting elements disposed on the substrate; and a plurality of driving circuits electrically connected to the light-emitting elements, The one or more light emitting elements emit light in response to a drive signal; The driving circuit includes an input terminal and two output terminals, one of which transmits the driving signal to one or more corresponding light emitting elements; a detection unit responding to the corresponding light emitting element to provide a detection output; and a feedback control unit instructing the transistor to respond to the detection output to adjust and control the driving signal; The transistor defines a characteristic curve, the characteristic curve being defined by an output current and a voltage difference between the two output terminals, the characteristic curve defining an operating region and an output conductance within the operating region, the output conductance being an absolute value of a ratio between a change in the output current and a change in the voltage difference; the active region further defines a first region and a second region, the output conductance of the first region being greater than the output conductance of the second region, and the transistor being active within the first region.
2. 2. The electronic device of claim 1, wherein the transistor is a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), or a field effect transistor (FET).
3. 3. The electronic device of claim 2, wherein the field effect transistor (FET) includes a metal oxide semiconductor field effect transistor (MOSFET), a metal semiconductor field effect transistor (MESFET) and a thin film transistor (TFT).
4. 2. The electronic device of claim 1, wherein the transistor is a field effect transistor (FET), the input terminal is a gate electrode, the two output terminals are a drain electrode and a source electrode, the first region is a linear region of the field effect transistor, and the second region is a saturation region of the field effect transistor.
5. 2. The electronic device according to claim 1, wherein the detection unit senses the light emitted by the corresponding light-emitting element, and provides the detection output according to the light emitted by the light-emitting element.
6. 2 . The electronic device of claim 1 , wherein the detection unit senses the driving signal that drives the corresponding light-emitting element, and provides the detection output according to the driving signal.
7. 7. The electronic device of claim 6, wherein the detection unit includes a resistor, the resistor and the corresponding light-emitting element are electrically connected in a series connection manner, and the feedback control unit indicates the corresponding transistor according to a voltage drop across the resistor.
8. 2. The electronic device of claim 1, wherein at least a portion of the driving circuit is implemented in an integrated circuit.
9. 2. The electronic device of claim 1, wherein the light emitting elements define a voltage drop, and the voltage difference value of the transistor is less than or equal to the voltage drop of the corresponding light emitting element.
10. An electronic device comprising: a plurality of light-emitting elements that emit light in response to a drive signal; and a plurality of drive circuits that correspond to and are electrically connected to the light-emitting elements, The driving circuit includes an input terminal and two output terminals, one of which transmits the driving signal to a corresponding one or more light emitting elements; a detection unit responding to the corresponding light emitting element to provide a detection output; and a feedback control unit instructing the transistor to adjust and control the driving signal; The transistor defines a characteristic curve, the characteristic curve being defined by an output current and a voltage difference between the two output terminals, the characteristic curve defining an operating region and an output conductance within the operating region, the output conductance being an absolute value of a ratio between a change in the output current and a change in the voltage difference; the active region further defines a first region and a second region, the output conductance of the first region being greater than the output conductance of the second region, and the transistor being active within the first region.