CN111092091A - active backlight LED light source plate driven by a-Si TFT device and backlight module - Google Patents
active backlight LED light source plate driven by a-Si TFT device and backlight module Download PDFInfo
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- CN111092091A CN111092091A CN201811169334.6A CN201811169334A CN111092091A CN 111092091 A CN111092091 A CN 111092091A CN 201811169334 A CN201811169334 A CN 201811169334A CN 111092091 A CN111092091 A CN 111092091A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
- H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
- H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133603—Direct backlight with LEDs
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
- G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
- G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
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- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/10—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions with semiconductor regions connected to an electrode not carrying current to be rectified, amplified or switched and such electrode being part of a semiconductor device which comprises three or more electrodes
- H01L29/1025—Channel region of field-effect devices
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- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
- H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
- H01L29/41725—Source or drain electrodes for field effect devices
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- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
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Abstract
The invention is suitable for the technical field of display, and provides an active backlight LED light source plate driven by an a-Si TFT device and a backlight module. According to the invention, the first source electrode and the first drain electrode are distributed in a staggered manner in a spiral and comb shape, and the first active layer correspondingly forms a spiral and comb-shaped channel, so that the width-length ratio of the channel can be improved, the driving capability of the channel can be improved, a larger driving current is allowed to pass through the channel for driving the light-emitting element to emit light, and the requirement of the driving current used as backlight is met.
Description
Technical Field
The invention belongs to the technical field of display, and particularly relates to an active backlight LED light source plate driven by an a-Si TFT device and a backlight module.
Background
Currently, a TFT (Thin Film Transistor) is mainly used to drive each pixel, such as a liquid crystal display array, an organic light emitting diode display array, and the like. The mainstream TFTs currently can be classified into three major categories, i.e., a-Si (Amorphous Silicon), IGZO (Indium Gallium zinc oxide) and LTPS (Low Temperature polysilicon), according to the semiconductor material used. The a-Si material has low mass and small carrier mobility, so that the a-Si TFT can bear small current density, and the IGZO and LTPS have large carrier mobility and can bear larger current density.
For a single TFT, at a given current density, the maximum current it can pass is proportional to the ratio of its channel width to its length (width to length ratio). In order to limit the leakage current of the TFT and ensure the stability of the device, the channel length of the TFT must be greater than a certain value.
The current LCD array and OLED array have higher resolution, so the Pitch (Pitch) between two adjacent pixels is smaller, about 0.1mm to 1mm, as shown in fig. 1 and 2. For a current drive element such as the organic light emitting diode 001 (fig. 1), the area occupied by the TFT 002 is generally large in the total area of the pixel, and a space for further increasing the current density by increasing the area is not large. In another case, for liquid crystal display applications, the area occupied by the liquid crystal (open region) 003 must reach a certain ratio (fig. 2), and thus the area occupied by the TFT 002' is limited. Therefore, in these conventional applications, the area of the TFT cannot be large, and when a large current is required, only TFTs of higher mobility materials such as IGZO or LTPS can be used to obtain a larger current density.
The Mini-LED (Mini light emitting diode) backlight technology is one of the novel display technologies emerging in recent years, and has the advantages of high dynamic resolution, power saving, simple algorithm and the like. The common Mini-LED backlight technology at present adopts a driving method of welding an integrated circuit on a PCB (printed circuit Board) back plate, which causes the problems of large PCB design difficulty, more welding times and high production cost, while the TFT driving technology applied in the OLED field is less applied to the Mini-LED backlight display. The main reason for this phenomenon is that the current density required by the backlight LED is usually large (mA level), the conventional a-Si TFT is difficult to meet the current density requirement, and the cost of new technologies such as LTPS is high.
In a backlit Mini-LED array, the size of Pitch can typically reach 10-100mm, much larger than the traditional application scenario of TFT. In this case, there is a large amount of available area in Pitch, and therefore, even if a-Si is used as the TFT material, it is highly likely that a TFT having a large drive current will be obtained by using the large amount of area.
Disclosure of Invention
The invention aims to provide an active backlight LED light source plate driven by an a-Si TFT device, and aims to apply the traditional a-Si TFT to an LED to meet the technical problem of the requirement of driving current used as a backlight module.
The present invention is achieved as such, a light source board comprising a plurality of light emitting cells disposed on a substrate; each light-emitting unit comprises a light-emitting element and a driving thin film transistor for driving the light-emitting element;
the driving thin film transistor comprises a first grid electrode, a first active layer, a first source electrode and a first drain electrode, wherein one part of the first source electrode and one part of the first drain electrode are distributed in a comb-tooth-shaped staggered manner, the other part of the first source electrode and the other part of the first drain electrode are distributed in a spiral staggered manner, a channel is formed between the first active layer and the first source electrode and the first drain electrode correspondingly, one part of the channel is spiral, and the other part of the channel is square-wave-shaped, so that the width of the channel is increased.
In one embodiment, the area ratio of the projected area of the driving thin film transistor in the light emitting unit is 70% to 95%.
In an embodiment, a passivation layer is disposed on the driving thin film transistor, a first via hole is disposed on the passivation layer corresponding to the first drain electrode, and the light emitting element is electrically connected to the first drain electrode through the first via hole.
In an embodiment, the projection of the light emitting element is located at a central position of the light emitting unit.
In an embodiment, the first via hole is filled with a first metal conductive pillar, the passivation layer is provided with a conductive line, and the light emitting element is electrically connected to the first drain electrode through the conductive line and the first metal conductive pillar.
In one embodiment, the light emitting unit further includes a switching thin film transistor for controlling the driving thin film transistor, and a capacitor for providing a sustain voltage for turning on the driving thin film transistor.
In one embodiment, the switching thin film transistor includes a second gate electrode, a second active layer, a second source electrode, and a second drain electrode connected to the first gate electrode of the driving thin film transistor.
In one embodiment, the switching thin film transistor and the capacitor are disposed at one side of the driving thin film transistor.
In an embodiment, a second via hole is formed in the passivation layer corresponding to the first source electrode, a second metal conductive pillar is filled in the second via hole, and the first source electrode is led out to the upper surface of the passivation layer through the second metal conductive pillar.
Another objective of the present invention is to provide a backlight module including the light source plate of the above embodiments.
Compared with the prior art, the light source plate provided by the invention has the advantages that the plurality of light emitting units are arranged on the substrate, each light emitting unit comprises a light emitting element and a driving thin film transistor for driving the light emitting element, the driving thin film transistor comprises a first grid electrode, a first active layer, a first source electrode and a first drain electrode, one part of the first source electrode and one part of the first drain electrode are distributed in a comb-tooth-shaped staggered manner, the other part of the first source electrode and the other part of the first drain electrode are distributed in a spiral staggered manner, the first active layer forms a channel between the first source electrode and the first drain electrode corresponding to the first source electrode, one part of the channel is in a spiral shape, the other part of the channel is in a square wave shape, the width-length ratio of the channel can be obviously improved, the driving capability of the channel is improved, and allows a larger driving current to be used for driving the light emitting elements to emit light, satisfying the driving current requirement for use as a backlight.
Drawings
FIG. 1 is a schematic diagram of a conventional LCD array structure;
FIG. 2 is a schematic diagram of a prior art OLED array structure;
FIG. 3 is a schematic diagram of an LCD device according to an embodiment of the present invention;
FIG. 4 is a schematic side view of a backlight module according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a side view of a light-emitting unit on an active backlight LED light source board driven by an a-Si TFT device according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a driving circuit in a light emitting unit according to an embodiment of the invention;
fig. 7 is a schematic structural diagram of a driving TFT according to a first embodiment of the present invention;
fig. 8 is a schematic structural diagram of a light-emitting unit according to a second embodiment of the present invention;
fig. 9 is a schematic structural view of a driving TFT according to a third embodiment of the present invention;
fig. 10 is a schematic structural diagram of a light-emitting unit according to a fourth embodiment of the present invention;
fig. 11 is a schematic structural diagram of a light-emitting unit according to a fifth embodiment of the present invention;
fig. 12 to 14 are schematic structural views of a light emitting unit according to a sixth embodiment of the present invention;
fig. 15 to 17 are schematic top-view structural diagrams of a light emitting unit according to a seventh embodiment of the present invention.
The designations in the figures mean:
the liquid crystal display device comprises a liquid crystal display device 1, a liquid crystal display panel 2 and a backlight module 3;
a light source plate 4, a diffusion plate 5;
a substrate 40, a light-emitting unit 41, a light-emitting element 42, a driving TFT44, a switching TFT45, a capacitor 46, an auxiliary element 47, a row control line 48, a column control line 49;
a gate insulating layer 52;
a first gate electrode 441, a first active layer 442, a first intrinsic semiconductor layer 4421, an ohmic contact layer 4422, a first source electrode 443, a first drain electrode 444;
a second gate electrode 451, a second active layer 452, a second source electrode 453, and a second drain electrode 454;
a channel 4420, a first channel 4425, a second channel 4426;
a first comb handle 4431, a first comb tooth 4432, a second comb handle 4441, a second comb tooth 4442;
a first via 74, a first metal conductive pillar 75, a second via 76, a second metal conductive pillar 77,
a sub-TFT 80, a first electrical conductor 87, a second electrical conductor 88, and a third electrical conductor 89.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly or indirectly secured to the other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element. The terms "upper", "lower", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the patent. The terms "first", "second" and "first" are used merely for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. The meaning of "plurality" is two or more unless specifically limited otherwise.
In order to explain the technical solution of the present invention, the following detailed description is made with reference to the specific drawings and examples.
Fig. 3 is a schematic structural diagram of the liquid crystal display device 1 according to an embodiment of the present invention. The liquid crystal display device 1 comprises a backlight module 3 and a liquid crystal display panel 2, wherein light rays emitted by the backlight module 3 enter the liquid crystal display panel 2, and are refracted by liquid crystal molecules in a liquid crystal layer to form a picture for displaying.
Referring to fig. 4 and 5, the backlight module 3 includes a light source plate 4 for providing light. In this embodiment, the backlight module 3 is a direct type backlight module, and a diffusion plate 5 is disposed in front of the light source plate 4. The light source plate 4 includes a substrate 40 and a plurality of light emitting elements 42 uniformly arranged on the substrate 40, wherein light emitted from the light emitting elements 42 is incident forward through the rear surface of the diffuser plate 5 and enters the diffuser plate 5, and is diffused and homogenized by the diffuser plate 5 to form a surface light source, and then is emitted from the front surface of the diffuser plate 5 and provided to the liquid crystal display panel 2.
Referring to fig. 6, the substrate 40 is further provided with a row control line 48 and a column control line 49, and the row control line 48 and the column control line 49 are used for controlling the plurality of light emitting units 41 to work independently, so that each light emitting unit 41 in the backlight module 3 can be controlled independently, which is beneficial to improving the display effect. Specifically, the light emitting unit 41 includes the light emitting element 42 described above and a driving circuit for driving the light emitting element 42 to emit light.
The driving circuit may include a switching element 45, a driving element 44 and a capacitor 46. The switching element is a thin film transistor (hereinafter referred to as a switching TFT 45) connected to the row control line 48 and the column control line 49, and controls the introduction of a signal to the column control line 49 according to a timing signal from the row control line 48, the driving element 44 is a thin film transistor (hereinafter referred to as a driving TFT 44) turned on according to a signal from the column control line 49 of the switching TFT45 to drive the light emitting element 42 to emit light, and the capacitor 46 stores a signal from the column control line 49 of the switching TFT45 to provide a bias and a sustain voltage for controlling the driving TFT 44.
Specifically, as shown in fig. 5 and 6, a plurality of row control lines 48, a first gate 441 and a second gate 451 are formed on the substrate 40 through a masking process, and the second gate 451 is connected to the row control lines 48. A gate insulating layer 52 is formed on the row control line 48, the first gate electrode 441, and the second gate electrode 451, and a first active layer 442 and a second active layer 452 are formed on the gate insulating layer 52. A first source 443 and a first drain 444 are formed on both sides of the first active layer 442, a second source 453 and a second drain 454 are formed on both sides of the second active layer 452, and a plurality of row control lines 49 are formed, wherein the second source 453 is connected to the row control lines 49. Also, the second drain electrode 454 is also connected to the first gate electrode 441 through a connection hole penetrating the gate insulating layer 52.
The switching TFT45 includes a second gate electrode 451, a second active layer 452, a second source electrode 453, and a second drain electrode 454. The switching TFT45 may be an a-Si TFT or an oxide semiconductor TFT, but the present invention is not limited thereto. Also, the drive current required to switch the TFT45 is generally small, and is preferably an a-Si TFT.
The capacitor 46 has one end connected to the negative electrode of the driving power source and the other end connected between the first gate 441 and the second drain 454.
The driving TFT44 includes a first gate electrode 441, a first active layer 442, a first source electrode 443, and a first drain electrode 444. When the driving TFT44 is turned on, a current flows between the first source electrode 441 and the first drain electrode 443 to drive the light emitting element 42 to operate. The light-emitting element 42 may be connected between the positive electrode of the driving power supply and the first source 443, or between the first drain 444 and the negative electrode of the driving power supply, and the light-emitting element 42 shown in fig. 6 is connected between the first drain 444 and the negative electrode of the driving power supply.
The maximum current that can pass between the first source 443 and the first drain 444 of the driving TFT44 determines the driving current of the light source plate 4, and when used in a backlight module, the driving current of the light source plate 4 usually needs milliampere level to meet the brightness requirement, so the driving TFT44 capable of bearing the corresponding driving current should be designed or used.
In the liquid crystal display device 1 according to the embodiment of the present invention, the light emitting elements 42 are mini light emitting diodes (mini-LEDs) having a size of about 200 μm. In the light source board 4, the total number of the mini-LED tubes on the substrate 40 is about several thousands, the distance between two adjacent mini-LEDs is about 10 to 100 micrometers, or a side length of one light emitting unit 41 is 10 to 100 millimeters, which is much larger than the size of the mini-LEDs. The mini-LED and the switching element 45 and the capacitor 46 occupy a small area ratio in a light emitting unit 41, and therefore, other areas than the area occupied by the mini-LED, the switching TFT45 and the capacitor 46 can be used for the design of the driving TFT 44. In one embodiment, the area ratio occupied by the driving TFT44 in a light emitting unit 41 is 70% to 95%, preferably 75% to 85%, and more preferably 80% to 85%, which can ensure that the driving TFT44 occupies a larger area for providing a larger width-to-length ratio of the channel 4420.
The technical scheme provided by the invention is not only suitable for a Mini-LED backlight source, but also suitable for a light emitting array formed by light emitting units with other sizes, such as a light emitting array formed by elements such as traditional LEDs. For other sizes of light emitting elements, the duty ratio of the TFT in each cell is different according to the size of the light emitting cell. By adopting the technical scheme provided by the invention, all light-emitting elements needing larger driving current can be driven.
In this embodiment, the drive TFTs 44 are a-Si TFTs, and the light source panel 4 of the present invention is an active backlight LED light source panel driven by a-Si TFT devices. The first active layer 442 of the driving TFT44 includes a first intrinsic semiconductor layer 4421 formed on the gate insulating layer 52 and ohmic contact layers 4422 formed over both sides of the first intrinsic semiconductor layer 4421. The material of the first intrinsic semiconductor layer 4421 is amorphous silicon, and the ohmic contact layer 4422 is amorphous silicon doped with N-type ions, such As elements of nitrogen (N), phosphorus (P), and arsenic (As). The a-Si TFT has the advantages of simple manufacturing process, low cost, high yield and low off-state leakage current, but the material mobility is low. Therefore, what needs to be solved for the use of mini-LED in the backlight module 3 is how to improve the driving capability of the a-Si TFT.
The specific structure of the a-Si TFT will be described below to provide a drive TFT44 of large driving capability.
In the driving TFT44 according to the embodiment of the present invention, the first source electrodes 443 and the first drain electrodes 444 are designed to be alternately arranged to form a continuous and meandering gap between the first source electrodes 443 and the first drain electrodes 444, instead of the conventional rectangular shape (refer to the dotted line rectangle in fig. 1 and 2), the first active layer 442 forms a continuous and meandering channel 4420 corresponding to the zigzag gap between the alternately arranged first source electrodes 443 and the first drain electrodes 444. The minimum distance for the current to flow between the first source 443 and the first drain 444 is the length of the channel 4420, the total length of the zigzag gap between the first source 443 and the first drain 444 is the width of the channel 4420, and the channel 4420 is formed in a continuous and zigzag manner, so that the width and the width-to-length ratio of the channel 4420 can be increased, and a larger driving current can be allowed to pass.
The projections of the first source 443 and the first drain 444 in the substrate plane are defined as a plane geometry a and a plane geometry B, respectively, where a and B satisfy the following condition:
the areas of A and B are not 0;
defining the distance from any point X to A in the plane as the minimum value in a set formed by the distances from X to all points on A; in the point set at the edge of B, more than 80% of points have the same distance to A, and the distance is d1, and d1 is more than 0; less than 20% of the points are further spaced from A by a distance greater than d 1; symmetrically, in the point set at the edge of A, more than 80% of the points have the same distance to B, the distance is d2, and d2 is more than 0; and less than 20% of the points are all further from B than d 2;
length L of side A and BAAnd LBArea SAAnd SBThe following conditions are satisfied: l isA 2/SA>104，LB 2/SB>104；
Neither A nor B must be contiguous.
Specifically, please refer to fig. 7, which is a schematic structural diagram of the driving TFT44 according to the first embodiment of the present invention. The staggered distribution is the comb-shaped staggered distribution. The first source 443 is comb-shaped and includes a first comb handle 4431 and a plurality of first comb teeth 4432 connected to the first comb handle 4431, and the first drain 444 is comb-shaped and includes a second comb handle 4441 and a plurality of second comb teeth 4442 connected to the second comb handle 4441. First comb teeth 4432 and second comb teeth 4442 are arranged between the first comb handle 4431 and the second comb handle 4441 in a mutually spaced manner, a second comb tooth 4442 is sandwiched between the two first comb teeth 4432, and a first comb tooth 4432 is sandwiched between the two second comb teeth 4442.
In one embodiment, the first comb handle 4431 and the first comb teeth 4432 are respectively disposed on two sides of the first active layer 442 to maximize the width of the channel 4420, and the channel 4420 is square-wave shaped between the first comb teeth 4432 and the second comb teeth 4442.
The first comb handle 4431 and the first comb teeth 4432 are preferably connected at a vertical angle, and the second comb handle 4441 and the second comb teeth 4442 are preferably connected at a vertical angle, which is beneficial to improving the utilization rate of the area of the light emitting unit 41.
The distance between one first comb 4432 and the nearest one second comb 4442, that is, the width of the cross section of the square wave is the length L of the channel 4420, and the total length of the square wave is the width W of the channel 4420, so that the width-to-length ratio of the channel 4420 is greatly improved in a limited area, and the maximum current and the driving capability of the driving TFT44 are improved.
In one embodiment, the distance between one first comb 4432 and the nearest one second comb 4442, i.e., the length L of the channel 4420, is 1 to 10 micrometers, and L may be 1 micrometer at the minimum, so that the maximum width and the maximum width-to-length ratio of the channel of the driving TFT44 can be obtained. On the basis of such a small length L, the width of the channel 4420 is substantially proportional to the sum of the numbers of the first comb teeth 4432 and the second comb teeth 4442, and therefore, the aspect ratio of the driving TFT44 is greatly improved.
The number of the first comb 4432 and the second comb 4442 may be multiple, for example, 2, 3 … … N, where N is a natural number, and the number of the first comb 4432 and the second comb 4442 may be the same or different; for example: the first source 443 may include 10 first comb teeth 4432, and the first drain 444 includes 11 second comb teeth 4442; another example is: the first source 443 includes 12 first comb teeth 4432, and the first drain 444 includes 11 second comb teeth 4442; another example is: the first source 443 includes 10 first comb teeth 4432, and the first drain 444 includes 10 second comb teeth 4442. Fig. 7 is only for illustrating the embodiment, and the invention is not limited thereto.
The first gate 441 is disposed corresponding to the channel 4420 in a square wave shape, and the first gate 441 overlaps with the first source 443 and the first drain 444.
Fig. 8 is a schematic structural diagram of a light emitting unit 41 according to a second embodiment of the present invention. Where the driving TFT44 is referred to as described above for the first embodiment, the area (projected area) thereof accounts for 70% to 95%, preferably 75% to 85%, and more preferably 80% to 85% of the area of the light emitting unit 41, it is ensured that the driving TFT44 occupies a large area for providing a large width-to-length ratio of the channel 4420. The light-emitting element 42, the switching TFT45, and the capacitor 46 (hereinafter, the switching TFT45 and the capacitor 46 are collectively referred to as an auxiliary element 47) have an area occupying less than or equal to 30%, preferably 15% to 25%, and more preferably 15% to 20% of the area of the light-emitting unit 41, which is advantageous in that the light-emitting element 42 and the auxiliary element 47 can be ensured to have a sufficient area for design, and the auxiliary element 47 is prevented from having an excessively small area and thus being difficult to design or manufacture. The driving TFT44 occupies a larger area in the light emitting unit 41, and there is a larger area for designing the first source 443 and the first drain 444, thereby greatly improving the driving capability of the driving TFT 44.
In one embodiment, the light emitting element 42 and the auxiliary element 47 may be disposed on any side of the driving TFT44, preferably, on a side close to the first drain 444, and particularly, on a side of the second comb finger 4441 or a side of the second comb finger 4442, to facilitate connection of the light emitting element 42 and the auxiliary element 47 with the first drain 444. For example, in fig. 8, the light emitting device 42 and the auxiliary device 47 are disposed on one side of the second comb teeth 4442, and the first source 443 and the first drain 444 are adjusted according to the shapes of the light emitting device 42 and the auxiliary device 47. The second comb handle 4441 of the first drain 444 is divided into two parts, and accordingly, the lengths of the second comb tooth and the first comb tooth become shorter. The channel 4420 was still formed in a square wave shape, except that the height of a portion of the square wave was correspondingly reduced.
Of course, it is understood that the auxiliary element 47 of the light emitting element 42 may be disposed on the second comb handle 4441 side of the first drain 444 such that the middle portion of the second comb handle 4441 is closer to the first comb handle 4431. Any design that does not change the comb-like staggered distribution of the first source 443 and the first drain 444 may be applied here.
Fig. 9 is a schematic structural diagram of a driving TFT44 according to a third embodiment of the present invention. The staggered distribution is spiral staggered distribution. The first source 443 and the first drain 444 are both stripe-shaped and spirally distributed, the first source 443 is arranged between the gaps of the spiral first drain 444, in fig. 9, the gap between the first source 443 and the first drain 444 forms a channel 4420, and the channel 4420 is correspondingly stripe-shaped and spirally distributed. Current flows from the first source 443 to the first drain 444, the width of the gap between the first source 443 and the first drain 444 is the length of the channel 4420, and the total length of the spiral is the width of the channel 4420, whereby the width and width-to-length ratio of the channel 4420 are greatly improved, which is advantageous for improving the driving capability of the driving TFT 44.
The first source 443 and the first drain 444 are each rectangular spiral to correspond to the shape of the light emitting cell 41, thereby improving the area utilization of the light emitting cell 41.
The width of the gap between the first source 443 and the first drain 444, i.e., the length L of the channel 4420, is 1 to 10 micrometers, and may be 1 micrometer at minimum.
The first gate 441 is correspondingly striped and spirally disposed, and is disposed corresponding to the spiral channel 4420 and overlaps with the first source 443 and the first drain 444. It is understood that the first gate 441 may correspond to only the channel 4420, and thus, in fig. 9, the first gate 441 is a gap corresponding to the first source 443 and the first drain 444.
It should be understood that the comb-like staggered distribution and the spiral-like staggered distribution given above are not mutually exclusive, and the staggered distribution of the first source 443 and the first drain 444 may not be one in one driving TFT 44.
As shown in fig. 10, a schematic structural diagram of a light emitting unit 41 according to a fourth embodiment of the present invention is provided, wherein the driving TFT44 is referred to as the third embodiment, and the projected area of the driving TFT44 accounts for 70% to 95%, preferably 75% to 85%, and more preferably 80% to 85% of the area of the light emitting unit 41, and the areas of the light emitting element 42 and the auxiliary element 47 account for less than or equal to 30%, preferably 15% to 25%, and more preferably 15% to 20% of the area of the light emitting unit 41. The driving TFT44 occupies a larger area in the light emitting unit 41, and there is a larger area for designing the first source 443 and the first drain 444, thereby greatly improving the driving capability of the driving TFT 44.
The light emitting element 42 and the auxiliary element 47 may be provided on either side of the driving TFT 44. As shown in fig. 10, the heliciform of the first source 443 and the first drain 444 is adaptively adjusted according to the light emitting element 42, the switching TFT45, and the capacitor 46 to maximally utilize the area of the light emitting cell 41.
As shown in the present embodiment, the light emitting element 42 and the auxiliary element 47 are disposed on the side of the driving TFT44 and occupy one corner of the light emitting unit 41, and at this time, the first source 443 and the first drain 444 may be distributed in a rectangular spiral shape on the side of the light emitting element 42 and the auxiliary element 47, which inevitably wastes a part of the area of the light emitting unit 41. If the area of the light emitting unit 41 is used as much as possible, the first source 443 and the first drain 444 cannot be staggered according to a simple rectangular spiral, and other staggered distributions, such as a comb-teeth staggered distribution, can be designed on the basis of the spiral. At least a portion of the first source 443 and the first drain 444 is stripe-shaped and spirally staggered, and a portion of the first source 443 and the first drain 444 may also be stripe-shaped and staggered.
Specifically, the first source 443 includes a source stripe 4433 spirally arranged, the first drain 444 includes a drain stripe 4443 spirally arranged, the source stripe 4433 and the drain stripe 4443 are spirally staggered to form a spiral first gap, and the first active layer 442 includes a spiral first channel 4425 formed corresponding to the first gap between the source stripe 4433 and the drain stripe 4443. The first source 443 further includes a source comb 4434 extending from the source bar 4433, the second drain 454 further includes a drain comb 4444 extending from the drain bar 4443, the source comb 4434 and the drain comb 4444 are spaced apart to form a second gap that is resistant to waves, and the channel 4420 further includes a second channel 4426 that is shaped like a square wave and is formed between the source comb 4434 and the drain comb 4444.
The first channel 4425 and the second channel 4426 are connected to form a complete channel 4420, and the overall length of the channel 4420 is made to be uniform by further designing a comb-shaped staggered distribution on the basis of a spiral staggered distribution, thereby being beneficial to ensuring the stability of the driving current of the driving TFT 44.
It is understood that the interleaving distribution is not limited to the above-given two of the comb-interleaving distribution and the spiral-interleaving distribution, and the comb-interleaving distribution and the spiral-interleaving distribution are not limited to the specific illustrations of the above two embodiments, and any interleaving distribution that can make the channel 4420 zigzag and maximize the utilization of the area of the light emitting unit 41 should be included in the disclosure of the present invention.
As shown in fig. 11, in order to provide a schematic structural diagram of a light emitting unit 41 according to a fifth embodiment of the present invention, in the third and fourth embodiments, a light emitting element 42 and an auxiliary element 47 are disposed at a central position of the light emitting unit 41, and the light emitting element 42 is connected to a first drain 444 at an end of the first drain 444 located at the center of the light emitting unit 41. This has advantages in that not only the light emitted from the light emitting element 42 can be more symmetrical, but also the electrical connection between the light emitting element 42 and the driving TFT44 can be more convenient without changing the spiral shapes of the first source 443 and the first drain 444 as in the fourth embodiment of fig. 10, thereby reducing the process design and manufacturing difficulty.
As can be seen from the above description of the embodiments, the present invention provides a scheme in which the driving TFT44 is formed in a large area in the entire light emitting unit 41, the first source 443 and the first drain 444 of the driving TFT44 are designed to be in a staggered distribution, and the channel 4420 is formed zigzag and continuously. For the driving TFT44, the driving current I thereof can be approximately described by the following relation (1)
Where W is the width of the channel 4420, L is the length of the channel 4420, and k1 is the scaling factor. The invention increases the width W of the conductive channel 4420 as much as possible under the condition that the length L of the channel 4420 is constant, thereby improving the current driving capability of the a-Si TFT. For the solution provided by the present invention, the length L of the channel 4420 is not easily changed after being minimized, but it is desirable to fill the entire region with TFT elements as much as possible
W＝k2A is formula (2);
where A is the total area of the drive TFT44 and k2 is the scaling factor. The driving TFT44 should occupy most of the area of the light emitting cell 41 to raise W, the length L of the channel 4420 is constant, and the width W is approximately proportional to the area of the light emitting cell 41. By combining formula (1) and formula (2)
I ═ kA formula (3);
wherein
Therefore, in the present embodiment, the driving current is proportional to the area of the driving TFT 44.
The drive current of a conventional sized a-Si TFT is (10)-6～10-5) Of the order of uA, whereas in the present invention Mi is usedThe side length of the light-emitting unit 41 in the ni-LED backlight module 3 is (10) of a pixel point in OLED display1～103) Multiple, area of (10)2～106) The drive current can be enlarged by about (10)2～106) Multiple times, reach (10)-4～101) The mA magnitude can meet the driving requirement of the Mini-LED used in the backlight module 3.
The above embodiments describe how to improve the area utilization ratio of the driving TFT44 in the light-emitting unit 41 in the planar area of the light-emitting unit 41 to improve the aspect ratio and the driving capability of the driving TFT44, and on this basis, the following embodiments are provided to further improve the area occupancy rate of the driving TFT 44.
Fig. 12 to 14 are schematic structural views of a light emitting unit 41 according to a sixth embodiment of the present invention. The driving TFT44 and the auxiliary element 47 of the light emitting unit 41 are disposed as one layer on the substrate 40, the projection area occupied by the driving TFT44 and the auxiliary element 47 is the area of the entire light emitting unit 41, and the light emitting element 42 is disposed as another layer above the driving TFT44 and the auxiliary element 47 (the filling of the light emitting element 42 means that the light emitting element 42 and the driving TFT44 are disposed at different layers), thereby saving the area of the light emitting element 42 for the design of the driving TFT44, enabling the area ratio and the width-to-length ratio occupied by the driving TFT44 to be further increased, and enabling the driving capability of the driving TFT44 to be improved.
A passivation layer 71 is formed on the first source electrode 443 and the first drain electrode 444, the passivation layer 71 has a first via hole 74 corresponding to the first drain electrode 444 and a second via hole 76 corresponding to the first source electrode 443, the first via hole 74 is filled with a first metal conductive pillar 75, the second via hole 76 is filled with a second metal conductive pillar 77, so as to lead the first source electrode 443 and the first drain electrode 444 out to the surface of the passivation layer 71, respectively, and a conductive line 72 for connecting the first drain electrode 444 and the light emitting element 42 and a power line 73 for connecting a driving power supply and the first source electrode 443 are further formed on the passivation layer 71. Accordingly, the light-emitting element 42 does not occupy the area of the light-emitting unit 41, the area of the driving TFT44 can be further increased, the width of the channel 4420 can be further increased, and the driving capability can be further increased.
In the present embodiment, the shape of the first source 443 and the first drain 444 may be substantially any shape. Preferably, the shape of the first source electrode 443 and the first drain electrode 444 adopts a comb-tooth shape as described in the first embodiment and/or a spiral shape as described in the third embodiment, and since the auxiliary element 47 and the driving TFT44 are both disposed below the passivation layer 71, and are in the same layer, i.e., together occupy the total area of the light emitting unit 41, the driving TFT44 may adopt a design as shown in fig. 10. Thus, the aspect ratio of the driving TFT44 is also greatly increased in addition to the increase in the area occupied by the driving TFT 44.
Preferably, the first metal conductive pillar 75 and the second metal conductive pillar 77 are respectively disposed at positions close to two ends of the channel 4420, which is advantageous in that the distance between the first metal conductive pillar 75 and the second metal conductive pillar 77 can be increased or even maximized as much as possible, thereby avoiding any possible electrical connection between the first metal conductive pillar 75 and the second metal conductive pillar 77 due to process problems during the process of depositing and etching the conductive pillar metal layer.
The auxiliary element 47 may be located at one side or the center of the driving TFT44 as shown with reference to fig. 10 and 11. Since the connection between the light emitting element 42 and the first drain electrode 444 is realized by the conductive wire 72 and the first metal conductive pillar 75, the projection of the light emitting element 42 in the light emitting unit 41 can be located virtually anywhere, such as an edge position or a center position. In a preferred embodiment, the light emitting element 42 is located at the center of the light emitting unit 41, and similarly, the light emitted from the light emitting element 42 is more symmetrical, which is beneficial to improving the uniformity of the backlight source of the backlight module 3 when the light emitting unit 41 is used in the backlight module 3.
Fig. 15 to 17 are schematic structural views of a light emitting unit 41 according to a seventh embodiment of the present invention. In the present embodiment, the driving TFT44 is composed of M layers (M is a positive integer greater than or equal to 2) of sub-TFTs 80 sequentially formed on the substrate 40. The sub-TFT 80 of the layer closest to the substrate 40 is the first layer sub-TFT 80, and the sub-TFT 80 of the layer farthest from the substrate 40 is the mth layer sub-TFT 80. Each of the sub-TFTs 80 is of a bottom gate type, and includes a sub-gate formed on the substrate 40, a sub-gate insulating layer 52 formed on the first substrate 40, a sub-active layer formed on the sub-gate insulating layer 52, and a sub-source electrode and a sub-drain electrode formed on the sub-active layer. The sub-active layer includes a sub-intrinsic semiconductor layer formed on the sub-gate insulating layer 52 and sub-ohmic contact layers formed over both sides of the sub-intrinsic semiconductor layer. The sub intrinsic semiconductor layer is made of amorphous silicon, and the sub ohmic contact layer is made of amorphous silicon doped with N-type ions, such As nitrogen (N), phosphorus (P), and arsenic (As), i.e., each sub TFT 80 is an a-si TFT. The passivation layer 71 is disposed between two adjacent layers of the sub-TFTs 80.
The M layers of sub-gates are electrically connected by a first electrical conductor 87. The first electrical conductor 87 is disposed outside the M layers of sub-source, sub-drain and sub-active layers, and only needs to penetrate the M-1 layer of sub-gate insulating layer 52 and the M-1 layer of passivation layer 71. As shown in fig. 17, the first electrical conductor 87 is illustrated in dashed lines, indicating that the first electrical conductor 87 is outside the region that can be shown in fig. 17, and does not represent a metal structure such as a sub-source, which is readily understood. The M-layer sub-gates constitute a first gate 441.
The M sub-sources are electrically connected by a second electrical conductor 88. A second electrical conductor 88 penetrates the M-1 layer gate insulating layer 52 and the M-1 layer passivation layer 71. The M-layer sub-source constitutes the first source 443.
The second electrical conductor 88 is further electrically connected to the second metal conductive pillar 77 disposed on the mth layer sub-source, so that the mth layer sub-sources are all led out to the upper side of the passivation layer 71 and are connected to the driving power source through the power line 73.
The M-layer sub-drains are electrically connected by a third electrical conductor 89. A third electrical conductor 89 penetrates the M-1 layer gate insulating layer 52 and the M-1 layer passivation layer 71. The M-layer sub-drains constitute a first drain 444.
The third electrical conductor 89 is further electrically connected to the first metal conductive pillar 75 disposed on the M-th sub-drain, so that the M-th sub-drains are all led out to above the passivation layer 71 and are connected to the light emitting element 42 through the conductive line 72.
The auxiliary element 47 is disposed in a layer in which the mth layer sub-TFT 80 is located, and the switching TFT45 may be disposed in the same layer as the mth layer sub-TFT 80 (the second gate electrode 451 is disposed in the same layer as the mth layer sub-gate electrode, and the second source electrode 453 and the second drain electrode 454 are disposed in the same layer as the mth layer sub-source electrode and the sub-drain electrode). The second drain 454 of the switching TFT45 is connected to the sub-gate of the mth layer sub-TFT 80, one end of the capacitor 46 is connected between the sub-gate of the mth layer sub-TFT 80 and the second drain 454, and the other end of the capacitor 46 is connected between the positive electrode of the driving power supply and the mth layer sub-source.
In the present embodiment, by the arrangement of the M-layer sub-TFTs 80, the area of the switching TFT45 is increased by approximately M times, thereby increasing the driving capability thereof. In the case where the aspect ratio of each sub-TFT 80 is constant, the scaling factor K2 is further increased to about M times.
In this embodiment, each sub-TFT 80 may adopt the comb-teeth-shaped staggered distribution described in the first embodiment and/or the spiral staggered distribution described in the third embodiment. Thus, the aspect ratio of the driving TFT44 is greatly increased in addition to the increase in the area occupied by the driving TFT 44.
In a preferred embodiment, the third electrical conductor 89 corresponds to the first metal conductive pillar 75, the second electrical conductor 88 corresponds to the second metal conductive pillar 77, and the first metal conductive pillar 75 and the second metal conductive pillar 77 are respectively disposed at two ends of the channel 4420, which not only has the advantage that the distance between the second electrical conductor 88 and the third electrical conductor 89 can be maximized, thereby avoiding any possible electrical connection between the second electrical conductor and the third electrical conductor during each deposition and etching process, but also has the advantage that a photomask can be used when the gate insulating layer 52 and the passivation layer 71 are perforated, which is beneficial to reducing the production cost and the process complexity.
The projection of the light emitting element 42 in the light emitting unit 41 may be located virtually anywhere. In a preferred embodiment, the light emitting element 42 is located at the center of the light emitting unit 41, and similarly, the light emitted from the light emitting element 42 is more symmetrical, which is beneficial to improving the uniformity of the backlight source of the backlight module 3 when the light emitting unit 41 is used in the backlight module 3.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A light source plate is characterized by comprising a plurality of light emitting units arranged on a substrate; each light-emitting unit comprises a light-emitting element and a driving thin film transistor for driving the light-emitting element;
the driving thin film transistor comprises a first grid electrode, a first active layer, a first source electrode and a first drain electrode, wherein one part of the first source electrode and one part of the first drain electrode are distributed in a comb-tooth-shaped staggered manner, the other part of the first source electrode and the other part of the first drain electrode are distributed in a spiral staggered manner, a channel is formed between the first active layer and the first source electrode and the first drain electrode correspondingly, one part of the channel is spiral, and the other part of the channel is square-wave-shaped, so that the width of the channel is increased.
2. The light source board according to claim 1, wherein a projected area of the driving thin film transistor is 70 to 95% in the light emitting unit.
3. The light source board of claim 1, wherein a passivation layer is disposed on the driving thin film transistor, a first via hole is disposed on the passivation layer corresponding to the first drain electrode, and the light emitting element is electrically connected to the first drain electrode through the first via hole.
4. A light source board as claimed in claim 3 wherein the projection of the light emitting element is located at the center of the light emitting unit.
5. The light source board of claim 3, wherein the first via hole is filled with a first metal conductive pillar, a conductive line is disposed on the passivation layer, and the light emitting element is electrically connected to the first drain electrode through the conductive line and the first metal conductive pillar.
6. The light source board of claim 1, wherein the light emitting unit further comprises a switching thin film transistor for controlling the driving thin film transistor, and a capacitor for supplying a sustain voltage for turning on the driving thin film transistor.
7. The light source board of claim 6, wherein the switching thin film transistor comprises a second gate electrode, a second active layer, a second source electrode, and a second drain electrode, the second drain electrode being connected to the first gate electrode of the driving thin film transistor.
8. The light source board of claim 6, wherein the switching thin film transistor and the capacitor are disposed on one side of the driving thin film transistor.
9. The light source board of claim 1, wherein a second via is formed in the passivation layer corresponding to the first source electrode, a second metal conductive pillar is filled in the second via, and the first source electrode is led out to the upper surface of the passivation layer through the second metal conductive pillar.
10. A backlight module comprising the light source board of any one of claims 1 to 9.
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| CN111092092A (en) * | 2018-10-08 | 2020-05-01 | Tcl集团股份有限公司 | active backlight LED light source plate driven by a-Si TFT device and backlight module |
| CN111580304A (en) * | 2020-05-06 | 2020-08-25 | Tcl华星光电技术有限公司 | Backlight module, display panel and electronic device |
| CN112736178A (en) * | 2020-12-23 | 2021-04-30 | 惠州市华星光电技术有限公司 | Mini-LED device and manufacturing method |
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