CN210536818U

CN210536818U - Micro LED Micro projection device

Info

Publication number: CN210536818U
Application number: CN201921052066.XU
Authority: CN
Inventors: 孙雷蒙; 杨丹; 刘芳
Original assignee: Huayinxin Wuhan Technology Co ltd
Current assignee: Huayinxin Wuhan Technology Co ltd
Priority date: 2019-07-05
Filing date: 2019-07-05
Publication date: 2020-05-15
Anticipated expiration: 2029-07-05

Abstract

The utility model relates to the technical field of semiconductor light-emitting devices, and discloses a Micro LED Micro projection device, which comprises a driving circuit substrate, a Micro LED chip array, a plurality of insulating reflectors, a lens component and a projection objective; the Micro LED chip array comprises a plurality of Micro LED chips, the Micro LED chips are arranged on the drive circuit substrate respectively, the insulating reflectors are arranged on the drive circuit substrate respectively, a plurality of mounting grooves are formed in the driving circuit substrate in an arrayed mode, one Micro LED chip is distributed in each mounting groove, each insulating reflector has a reflecting surface facing the Micro LED chip, the reflecting surfaces are gradually expanded along the direction away from the drive circuit substrate, the lens assembly is arranged on the insulating reflectors, and the projection objective is arranged on the lens assembly. The utility model discloses avoided the display pixel that the cross talk leads to between the single pixel light source discontinuous, the projection is effectual.

Description

Micro LED Micro projection device

Technical Field

The utility model relates to a semiconductor light emitting device technical field, concretely relates to little projection arrangement of Micro LED.

Background

The projection display is a process that an image signal generates an image under the action of a driving circuit, the image is amplified through the combination of an optical system and a projection space, the amplified image is received by a projection screen, and finally the projection display is finished. The projection technology is going through the three generations of changes of cathode ray tube, liquid crystal optical plate, etc., and is developing to the aspects of high brightness, high quality, microminiature, etc. The micro projector is the main development direction of the third generation projector, and has the characteristics of small volume, large display size, high light energy utilization rate and the like. The structure of the micro projector is mostly composed of a BLU (Back Light Unit), a color wheel, a display Unit, a color combining prism, a reflector, a projection lens, etc., and the BLU is often a Light Emitting Diode (LED) display device. The most widely used projection systems at present are an LCoS (Liquid Crystal on Silicon) system and a DLP (Digital Light Processing) system, wherein the DLP system works on the principle that Light emitted by a BLU is time-domain dispersed by a lens, a Light homogenizing element and a color wheel, then incident Light is reflected by a DMD (Digital Micro mirror Device) and imaged, and finally the image is projected to a display screen by the projection system; the working principle of the LCoS system is that light emitted by the BLU is divided into RGB three color lights through a dichroic mirror, and then is modulated and imaged through three different liquid crystal light panels, and images are projected onto a display screen through a projection system. The display units of the two projection systems do not have the characteristic of active light emission, a large amount of light energy is lost before the light emitted by the BLU is projected to the display units, only 2.8% of light source energy can be transmitted to the display units, and a stray light interference phenomenon is generated. In addition, DMDs are expensive to produce and LCoS is difficult to dissipate heat well, and these deficiencies limit the development of these two systems. With the explosion of semiconductor technology, many new display devices have been developed in succession, reducing the size of the projection system and improving the image quality. Micro LEDs are more attractive. The advantage of the Micro LED is based on the principle characteristic of micron-sized pixel spacing, each pixel point can be independently controlled and driven, so that the Micro LED has quite excellent performance parameters such as resolution, brightness, contrast, power consumption and the like, and has the advantages of small volume, low working voltage, high luminous efficiency, high response speed, compact structure and the like, so that the application range of the Micro LED covers a plurality of fields such as display, medical treatment, biology, military affairs, communication, detection and the like. The combination of Micro LED display technology with projection systems has become a development trend in projection technology.

Compared with the Micro LED, the same self-luminous display technology, such as laser projection and AMOLED, has defects more or less, the laser projection may cause damage to retina of human eyes, and the self-luminous function of the AMOLED is harmless to human body, but compared with the AMOLED, the Micro LED screen has the advantages of low power consumption, high brightness, ultrahigh resolution and color saturation, fast reaction speed, super power saving, longer service life, higher efficiency, etc., the power consumption is about 50% of that of the OLED, the brightness is 30 times higher than that of the OLED, and the resolution can reach 1500PPI (pixel density). At present, Micro LEDs are superior to OLEDs in technical life, contrast, energy consumption, reaction time, visual angle and the like.

At present, Micro LEDs are still in a research stage, industrial mass production is not realized temporarily, and the Micro LEDs are also insufficient in projection display technology, wherein most obviously, "bright edge" problems of low pixel center brightness and too high edge brightness caused by serious crosstalk between single pixel light sources in a projection picture, or "dark area" problems between pixel light sources caused by high center brightness and too low edge brightness of a single pixel light source cause a display panel to generate an obvious pixel discontinuity phenomenon, thereby affecting a projection effect. The reason for this problem is that the light emitting angle of a single chip is too large, generally at 120-160 °, after the chip is arrayed, the light interference is inevitably generated when the chip spacing is too small, and the problem of light emitting dark areas between chips is caused when the chip spacing is too large.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome above-mentioned technique not enough, provide a little projection arrangement of Micro LED, solve among the prior art serious crosstalk between the single pixel light source and lead to the display pixel discontinuous, the not good technical problem of projection effect.

In order to achieve the technical purpose, the technical scheme of the utility model provides a Micro LED Micro projection device, which comprises a driving circuit substrate, a Micro LED chip array, a plurality of insulating reflectors, a lens component and a projection objective lens;

the Micro LED chip array comprises a plurality of Micro LED chips, the Micro LED chips are arranged on the drive circuit substrate respectively, the insulating reflectors are arranged on the drive circuit substrate respectively, a plurality of mounting grooves are formed in the driving circuit substrate in an arrayed mode, one Micro LED chip is distributed in each mounting groove, each insulating reflector has a reflecting surface facing the Micro LED chip, the reflecting surfaces are gradually expanded along the direction away from the drive circuit substrate, the lens assembly is arranged on the insulating reflectors, and the projection objective is arranged on the lens assembly.

Compared with the prior art, the beneficial effects of the utility model include: the insulating reflector and the lens component are used for refracting light beams emitted by the Micro LED chips, the emergent angle of the light beams is controlled in a smaller angle, and the light beams of a single Micro LED chip have high middle light intensity and low peripheral light intensity, so that the smaller emergent angle ensures that the problems of low pixel center brightness and high edge brightness 'bright edge' caused by serious interference between the light beams of adjacent Micro LED chips are solved, and the problems of high center brightness and low edge brightness 'dark area' of a pixel light source of the single Micro LED chip are solved.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of a Micro LED Micro projection apparatus provided in the present invention;

FIG. 2 is a top view of an embodiment of a Micro LED Micro projection device provided by the present invention;

FIG. 3 is a circuit diagram of one embodiment of a passive matrix driving scheme for a Micro LED chip array provided by the present invention;

FIG. 4 is a circuit diagram of one embodiment of an active matrix driving scheme for a Micro LED chip array according to the present invention;

FIG. 5a is a mask pattern layout of an embodiment of the hot melt photoresist and etch transfer method provided by the present invention;

FIG. 5b is a schematic view of a quartz substrate and a photoresist according to an embodiment of the present invention;

FIG. 5c is an exposure schematic diagram of an embodiment of a hot melt photoresist and etch transfer method provided by the present invention;

FIG. 5d is a schematic illustration showing the development of one embodiment of the hot melt photoresist and etch transfer process provided by the present invention;

FIG. 6 is a schematic view of a hot-melt photoresist of an embodiment of a hot-melt photoresist etching transfer method provided by the present invention;

FIG. 7 is a schematic diagram of reactive ion beam etching according to an embodiment of the present invention;

FIG. 8a is a schematic diagram of a single Micro LED chip disposed on a planar substrate;

FIG. 8b is a Tracepro ray simulation path diagram of a single Micro LED chip in FIG. 8 a;

fig. 9a is a packaging structure diagram of a single Micro LED chip in the Micro LED Micro projection apparatus provided by the present invention;

FIG. 9b is a Tracepro ray simulation path diagram of a single Micro LED chip in FIG. 9 a.

Reference numerals:

1. the LED chip comprises a driving circuit substrate, 2, a Micro LED chip, 3, an insulating reflector, 31, a mounting groove, 32, a metal electrolyte reflecting film, 4, a planar refraction lens, 41, an anti-reflection film, 5, a Micro lens, 51, a quartz substrate, 52 and photoresist.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in 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.

Example 1

As shown in fig. 1 and fig. 2, embodiment 1 of the present invention provides a Micro LED Micro projection device, which includes a driving circuit substrate 1, a Micro LED chip array, a plurality of insulating reflectors 3, a lens assembly, and a projection objective lens, which is not shown in the figure;

the Micro LED chip array comprises a plurality of Micro LED chips 2, the Micro LED chips 2 are respectively installed on the drive circuit substrate 1, the insulating reflectors 3 are respectively installed on the drive circuit substrate 1 and are arranged to form a plurality of installation grooves 31, one Micro LED chip 2 is distributed in each installation groove 31, each insulating reflector 3 has a reflection surface facing the Micro LED chip 2, the reflection surface is gradually enlarged along the direction away from the drive circuit substrate 1, the lens assembly is installed on the insulating reflector 3, and the projection objective is installed on the lens assembly.

The insulating reflector 3 can be made of silicon dioxide, and has the functions of ensuring the electrical independence between the Micro LED chips 2, realizing the first reflection and condensation of emergent light of the Micro LED chips 2, and controlling a large-angle light source emitted by the Micro LED to emit light within a certain angle range. Then, a lens assembly is mounted on the insulating reflector 3, and the lens assembly is used for reducing the light-emitting angle of the light source emitted by the insulating reflector 3 to a smaller angle. The light emitting angle of the general Micro LED chip 2 is too large, about 120-160 degrees, after the array is arranged, the light interference is generated due to too small chip distance, the light dark space is generated between the chips due to too large chip distance, the light emitting angle of the light source of the Micro LED chip 2 can be controlled within a certain small angle range after being reflected and refracted by adopting the embodiment, the serious interference can not be generated between the light sources of the Micro LED chip 2, the middle brightness of a single chip light beam can be compensated, the poor problem of the dark space can be caused due to low edge brightness, the display quality can be improved, and the projection effect can be improved.

The Micro LED chip array is driven by a driving circuit, and each chip can be independently lightened through the driving circuit. The utility model discloses well Micro LED chip array adopt current drive mode drive can, for example can adopt passive matrix drive mode, its circuit diagram is shown in FIG. 3, or 2T1C active matrix drive mode, its circuit diagram is shown in FIG. 4. Both the passive matrix driving method and the 2T1C active matrix driving method are conventional driving methods. The Micro LED array is driven by a passive matrix, each row of Micro LED chips is connected with the same anode, each column of Micro LED chips is connected with the same cathode, and the crossed points of the rows and the columns emit light in a state of simultaneous scanning. 2T1C active matrix drive, a group of circuits are formed below each Micro LED chip of the Micro LED array through CMOS integrated circuit technology, and each group of circuits comprises 2 TFT thin film transistors and 1 capacitor. The Micro LED is a current device, current cannot be stably stored, voltage can be temporarily stored by a capacitor, so that a TFT1 is required to convert the stored voltage into current, and the TFT1 and the Micro LED chip are in a series structure, that is, the current of the TFT1 is the current when the Micro LED works. The gate voltage of the TFT1 is the data voltage from the signal line in fig. 4, but there are many rows of signals on the signal line, so a TFT2 is required to selectively couple signals to the gate of the TFT1, when the scan line is the on signal, the signals enter the gate of the TFT1, when the scan line is the off signal, the gate voltage of the TFT1 is independent of the signal line, and the gate voltage is held by the capacitor C.

Preferably, as shown in fig. 1, the reflecting surface is plated with a metal electrolyte reflecting film 32.

The side surface and the bottom surface of the insulating reflector 3, which are arranged towards the Micro LED chip 2, are plated with a metal electrolyte reflecting film 32 in a magnetron sputtering mode, and the metal electrolyte reflecting film is formed by superposing an electrolyte protective film on a metal reflecting film. The metal electrolyte reflective film 32 is first coated with a metal thin film as a metal reflective film by evaporation or sputtering, and the metal reflective film can be made of aluminum, silver, gold, copper, etc. The groove formed by the insulating reflector 3 is filled with air, so that the loss of the light source in other media is reduced. In order to prevent the metal reflective film from being oxidized in the air and reducing the performance, a dielectric protective film is coated on the metal reflective film for protection. The material of the dielectric protective film may be magnesium fluoride, silicon dioxide, aluminum oxide, or the like.

Preferably, as shown in fig. 1, the lens assembly includes a planar refractive lens 4, and the planar refractive lens 4 is mounted on the plurality of insulating reflectors 3 and covers each of the mounting grooves.

The planar refraction lens 4 is used for reducing the light-emitting angle of the light source emitted from the insulating reflector 3.

Preferably, as shown in fig. 1, two side surfaces of the planar refractive lens 4 are respectively coated with antireflection films 41.

One or more layers of antireflection films 41 can be plated on the upper and lower side surfaces of the plane refraction lens 4 to reduce or eliminate the reflected light on the surface of the plane refraction lens 4 and increase the transmission amount of the plane mirror. The material of the anti-reflection film 41 may be magnesium fluoride, silicon nitride, or silicon dioxide. The silicon nitride antireflection film 41 can be formed by ionizing ammonia gas and silane by using a plasma enhanced chemical vapor deposition technology, and then depositing the ionized ammonia gas and silane on the surface of the plane mirror, so that the silicon nitride antireflection film has a high refractive index and can achieve a good antireflection effect.

Preferably, as shown in fig. 1, the lens assembly further includes a Micro lens array, the Micro lens array covers the planar refraction lens 4, the Micro lens array includes a plurality of Micro lenses 5, the number of the Micro lenses 5 is equal to that of the Micro LED chips 2 and corresponds to that of the Micro LED chips 2, and each of the Micro lenses 5 is disposed opposite to the corresponding Micro LED chip 2.

The light emitting surface of the micro-lens array is enlarged, and the light efficiency can be improved to a certain extent. The micro-lens array is manufactured by adopting the existing process. The preferred embodiment uses a hot melt photoresist plus etch transfer method. As shown in fig. 5, the hot-melt photoresist etching transfer method mainly includes three steps: photolithography, thermal melting, and reactive ion beam etching.

1. Photoetching: spin coating is performed on the surface of the quartz substrate 51, the quartz substrate 51 is shown in FIG. 5b, the layout of the mask pattern for spin coating is shown in FIG. 5a, the dimension D of the cell pattern in the layout of the mask pattern corresponds to the dimension of the upper surface of the insulating reflector 3, and the interval L between the cell patterns is set to 1.5 μm to 3 μm. As shown in fig. 5c and 5d, the quartz substrate 51 after being homogenized is exposed and developed, and the photoresist 52 forms a separated cubic array structure.

2. Hot melting the photoresist: as shown in fig. 6, the quartz substrate 51 after the photolithography is annealed, the hot melting temperature is slightly higher than the melting point of the photoresist 52, and the heating time, the holding time, and the natural cooling time are set according to the properties of the photoresist 52. After the step is completed, the photoetching spherical crown array with clear outline can be obtained.

3. Reactive ion beam etching: as shown in fig. 7, reactive ion beam etching is to introduce a reactive gas into the ion beam etching, so as to accelerate the etching rate. The velocities of the quartz substrate 51 and the photoresist 52 can be kept consistent by adjusting etching parameters such as radio frequency power, gas pressure, gas composition ratio and the like, so that the micro-lenses 5 on the photoresist 52 are transferred onto the quartz substrate 51 with high fidelity.

The single Micro lens 5 of the Micro lens array is aligned to the single Micro LED chip 2, and has the functions of making the illumination of the emergent light beam more uniform, and re-refracting the light source refracted by the planar refractive lens 4 to realize the emergent at a smaller angle.

Preferably, the microlenses 5 are plano-convex lenses.

Preferably, the Micro LED chip 2 is a Micro LED flip chip.

Micro LED flip chip, flip chip adopts flip structure for short, and flip structure adopts flip technology to realize, and flip technology is future development trend, and flip technology main advantage lies in: (1) the p electrode and the n electrode are designed on the same plane, so that the connection is more convenient, and the influence of the light-emitting area occupied by the electrodes on the light-emitting efficiency is avoided; (2) thermoelectricity of the flip chip belongs to the same channel, the heat dissipation area is large, heat can be easily led out from the interior of the chip, and the heat conduction speed is high; (3) the flip structure has no high resistance point and no insufficient point of insufficient soldering, and the condition of lamp death caused by insufficient soldering can not occur; (4) special metal bumps and wires do not need to be manufactured, the structure of the direct bonding form of the flip chip electrode and the substrate is simpler, and the reliability is improved; (5) the packaging density is greatly increased and is dozens of times of that of the normally-installed chip, the packaging volume is sharply reduced and is only 20% -30% of that of the normally-installed chip; (6) the sapphire substrate is peeled off, and the light extraction efficiency is increased.

The Micro LED flip chip sequentially comprises a sapphire or transparent substrate, a III-V group nitride, a current expansion layer, a reflecting layer and a metal connecting layer from top to bottom, wherein a P electrode and an N electrode of the metal connecting layer correspond to Pad points on the driving circuit substrate 1 one by one, so that bonding between the Micro LED flip chip and the driving circuit substrate 1 is realized.

Preferably, the reflecting surface is an inclined plane or a curved surface.

Specifically, as shown in fig. 1, the reflecting surface in the preferred embodiment is an inclined plane.

In order to verify the light condensation effect of the Micro LED Micro projection device provided by the invention, a light simulation experiment is carried out through optical processing software Tracepro. Fig. 8a shows a structure of a single Micro LED chip disposed on a planar substrate, wherein the light emitting angle of the Micro LED chip is 180 °. Fig. 9a shows the packaging structure diagram of a single Micro LED chip in the Micro LED Micro projection apparatus provided by the present invention, which enhances the light-gathering effect. Fig. 8b shows a light simulation effect diagram of a single Micro LED chip disposed on a planar substrate. Fig. 9b shows a light simulation effect diagram of a single Micro LED chip provided by the present invention. Contrast figure 8b and figure 9b can obviously find out, the utility model provides a little projection arrangement of Micro LED's emergent ray's emergence angle has obtained fine control, successfully with light emergence angle control at 5 ~ 10 small-angles, because 2 light intensity in the middle of the light beam of single Micro LED chip is higher, both sides light intensity is lower, 5 ~ 10 small-angle emergence has both guaranteed that can not seriously the perplexing between every Micro LED chip pixel light source and cause pixel central brightness low, the too high "bright edge" problem of edge brightness, the light intensity at single pixel light beam edge has been compensatied again, thereby it is high to have solved single pixel light source central brightness, edge brightness crosses lowly and "dark space" problem between the pixel light source that causes.

The above description of the present invention does not limit the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A Micro LED Micro projection device is characterized by comprising a driving circuit substrate, a Micro LED chip array, a plurality of insulating reflectors, a lens assembly and a projection objective lens;

2. A Micro LED Micro projection device according to claim 1, wherein the reflective surface is plated with a metal electrolyte reflective film.

3. A Micro LED Micro projection device according to claim 1, wherein said lens assembly comprises a planar refractive lens mounted on a plurality of said insulating reflectors and covering each of said mounting slots.

4. A Micro LED Micro projection device according to claim 3, wherein two sides of said planar refractive lens are coated with antireflection coating.

5. A Micro LED Micro projection apparatus according to claim 3, wherein said lens assembly further comprises a Micro lens array covering said planar refractive lens, said Micro lens array comprising a plurality of Micro lenses, the number of said Micro lenses being equal to the number of said Micro LED chips and corresponding to one another, each of said Micro lenses being disposed opposite to a corresponding Micro LED chip.

6. A Micro LED Micro projection device according to claim 5, wherein the Micro lens is a plano-convex lens.

7. A Micro LED Micro projection device according to claim 1, wherein the Micro LED chip is a Micro LED flip chip.

8. A Micro LED Micro projection device according to any of claims 1-7, wherein the reflective surface is an inclined plane or curved surface.