CN103018976B - Blue-phase liquid crystal display device - Google Patents

Abstract

The present invention is a kind of blue phase liquid crystal display device, and its structure comprises: upper polarizing plate, upper substrate, middle part, lower substrate and lower polarizing plate; Its position is lower polarizing plate, lower substrate successively according to the sequence of incident light passing through from bottom to top , a middle part, an upper substrate and an upper polarizer; the middle part is composed of a blue phase liquid crystal (BPLC), a first Pixel electrode, a second Pixel electrode, a slit, an insulating layer, a Common electrode and a protrusion. The present invention effectively increases the light transmittance above the electrode by introducing the slit structure and the common electrode on the bottom surface through the fringe field formed by the pixel electrode and the common electrode, thereby effectively increasing the light utilization rate of the blue-phase liquid crystal display. At the same time, the Pixel electrode and the Common electrode below it can be used as storage capacitors, reducing the production of separate storage capacitors and increasing the actual aperture ratio (transmitting area) of the blue-phase liquid crystal display.

Description

A blue phase liquid crystal display device

technical field

The invention designs a device in the technical field of liquid crystal display, in particular a device for increasing the transmittance of a blue-phase liquid crystal (BPLC) display.

Background technique

The blue phase liquid crystal display has the characteristics of response time below milliseconds, wide viewing angle and high contrast ratio, and does not require an alignment layer in the production process, nor does it need to impose strict restrictions on the thickness of the liquid crystal layer, the production cost is low, and the manufacturing process is simpler. , which is considered to have the most potential to become the next generation of liquid crystal displays. The traditional blue-phase liquid crystal display is driven in the form of the driving electrodes of the coplanar switching liquid crystal display. It is necessary to make a storage capacitor to obtain a high voltage retention rate, because only a small amount of light passes through the electrode and the area where the storage capacitor is made, and The driving voltage is also relatively high.

The pixel electrode with slits and the common electrode are arranged under the pixel electrode to form the light transmission above the electrode and the storage capacitor under the pixel electrode, which increases the light transmission area and improves the light transmittance, but the driving voltage is lower than that of the pixel electrode. The driving electrode structure of conventional coplanar switching is enlarged. In order to reduce the driving voltage, it has been proposed to use protrusions and raised electrode structures to reduce the driving voltage, and by optimizing the shape of the protrusions, a higher transmittance and a lower driving voltage have been obtained, but because the entire pixel It is still necessary to make an additional storage capacitor to maintain the voltage, so the overall light transmittance is not high.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages in the prior art, and provide a simple and effective device for improving light utilization, and the driving voltage is similar to that of the traditional coplanar switching electrode structure. In the present invention, a pixel electrode with a slit structure and a common electrode below it are arranged on the protrusion, and by adjusting the width and number of the slits, a fringe field is generated on the protrusion or on the hypotenuse of the protrusion, Effectively improve the light utilization rate of the blue-phase liquid crystal display, because the pixel electrode and the common electrode form a storage capacitor, reduce the part of the storage capacitor separately, and increase the actual aperture ratio of the liquid crystal display.

Technical scheme of the present invention is:

A blue-phase liquid crystal display device, its structure includes: an upper polarizer, an upper substrate, a middle part, a lower substrate and a lower polarizer;

Its position is the lower polarizer, the lower substrate, the middle part, the upper substrate and the upper polarizer from bottom to top in accordance with the order of incident light; the composition of the middle part is blue phase liquid crystal (BPLC), the first Pixel electrode, and the second Pixel electrode , slits, insulating layers, common electrodes and protrusions,

The middle part between the upper base plate and the lower base plate is either of the following two distribution methods:

Distribution method 1: Protrusions are evenly distributed on the upper surface of the lower substrate, the Common electrode covers the protrusions, the insulating layer covers the Common electrode and the lower substrate, and the first Pixel electrode and the second Pixel electrode intersect and cover On the insulating layer above the evenly spaced protrusions, there is a slit between the top and bottom of the first Pixel electrode or the second Pixel electrode on the protrusion; the first Pixel electrode and the second Pixel electrode are polarized Opposite potential, the blue phase liquid crystal fills the gap between the upper substrate and the lower substrate;

Or, the second distribution method: the upper surface of the lower substrate is arranged with strip-shaped Common electrodes at equal intervals, and the blank part of the lower substrate and the Common electrodes are covered with an insulating layer, and the insulating layer is flattened, and the protrusions are located on the positive sides of the Common electrodes. Above, the bottom width of the cross-section of the protrusion is smaller than that of the Common electrode, the first Pixel electrode 3 and the second Pixel electrode 4 are located above the insulating layer 6 and the protrusion 10, and the first Pixel electrode 3 or the second Pixel electrode 4 is on the protrusion There is a slit 5 between the top and the bottom of the top, the first Pixel electrode 3 and the second Pixel electrode 4 are applied with opposite polarity potentials, and the blue phase liquid crystal fills the gap between the upper substrate and the lower substrate;

The transverse cross-sectional shape of the protrusion is a triangle or trapezoid, the longitudinal projection shape is a rectangle or a "zigzag" shape, and the height is half of the thickness of the liquid crystal layer, and the range is: 2-10 μm;

The slits are obtained by etching ITO electrodes. The width range of the slits and thin electrodes can be adjusted according to the size and process of Pixel electrodes. The width of the slits is usually 2-5 μm, and the width of each thin electrode is 1- 5 μm.

The electrode thickness range of the Pixel electrode and the Common electrode is: 20nm-250nm.

The range of the distance between the protrusions is 5-20 μm.

The thickness range of the liquid crystal layer: 5-20 μm.

Compared with the prior art, the beneficial effect of the present invention is: by introducing the slit structure and the common electrode on the bottom surface, through the fringe field formed by the Pixel electrode and the Common electrode, the light transmittance above the electrode is effectively increased, thereby effectively increasing the Light utilization efficiency of blue phase liquid crystal display. At the same time, the Pixel electrode and the Common electrode below it can be used as storage capacitors, reducing the production of separate storage capacitors and increasing the actual aperture ratio (transmitting area) of the blue-phase liquid crystal display.

Other aspects and features of the present invention will become apparent from the following detailed description with reference to the accompanying drawings. However, it should be understood that the drawings are only designed for the purpose of explanation, rather than setting the scope of the present invention.

Description of drawings

Below in conjunction with accompanying drawing, specific embodiment of the present invention is described in detail, wherein:

Figure 1 is a schematic structural view of Example 1, (a) is a top view of the lower substrate surface, (b) is a cross-sectional view;

Fig. 2 is a V-T curve diagram of Embodiment 1, the square line is the existing IPS structure, the dotted line is the raised electrode, and the triangle line is the structure of this embodiment.

Figure 3 is a schematic structural view of Embodiment 2, (a) is a top view, (b) is a cross-sectional view;

Fig. 4 is a V-T curve diagram of Embodiment 2, the square line is the existing IPS structure, the dotted line is the raised electrode, and the triangle line is the structure of this embodiment.

Figure 5 is a schematic structural view of Embodiment 3, (a) is a top view, (b) is a cross-sectional view;

Fig. 6 is a V-T curve diagram of Embodiment 3, the square line is the existing IPS structure, the dotted line is the raised electrode, and the triangle line is the structure of this embodiment.

Figure 7 is a schematic structural view of Embodiment 4, (a) is a top view, (b) is a cross-sectional view;

Fig. 8 is a V-T curve diagram of Embodiment 4, the square line is the existing IPS structure, the dotted line is the raised electrode, and the triangle line is the structure of this embodiment.

FIG. 9 is a diagram of the light-transmitting area in the conventional IPS structure and the structure of this embodiment.

detailed description

The implementation of the present invention will be further described below in conjunction with the accompanying drawings: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the implementation of subordinates example.

Example 1

As shown in Figure 1 (where (a) is a top view of the surface of the lower substrate, (b) is a cross-sectional view), the structure of the blue-phase liquid crystal display device of this embodiment includes: an upper polarizer 1, an upper substrate 2, a blue-phase liquid crystal (BPLC), the first Pixel electrode 3, the second Pixel electrode 4, the slit 5, the insulating layer 6, the Common electrode 7, the lower substrate 8, the lower polarizer 9 and the triangular protrusion 10,

in:

The lower surface of the upper middle and upper polarizer 1 is connected to the upper surface of the upper substrate 2, the upper surface of the lower middle and lower polarizer 9 is connected to the lower surface of the lower substrate 8, and other components are between the upper substrate 2 and the lower substrate 8, wherein Protrusions 10 are uniformly distributed on the upper surface of the lower substrate 8, the Common electrode 7 covers the protrusions 10, the insulating layer 6 covers the Common electrode 7 and the lower substrate, and the first Pixel electrode 3 and the second Pixel electrode 4 intersecting and covering the insulating layer 6 above the evenly spaced bumps 10, the first Pixel electrode 3 or the second Pixel electrode 4 has a slit 5 between the top and bottom of the bumps; the first Pixel Electrode 3 and the second Pixel electrode 4 apply a potential of opposite polarity, and the blue phase liquid crystal fills the gap between the upper substrate and the lower substrate;

The distance between the upper substrate 2 and the lower substrate 8 is 12 μm.

The protrusions are made of transparent silicon nitride or silicon dioxide material. The cross-sectional shape is a triangle with a width of 8 μm and a height of 4 μm. The shape of the vertical top view is a rectangle, and the length is equal to the length of the pixel electrode. The spacing of each column of protrusions is 15 μm. .

The thin slit 5 is realized by photolithography process, and its plan view is rectangular. Two thin slits 5 are respectively etched on each Pixel electrode. The overall width of the outer electrode is 10 μm, and the width of the outer electrode strip is 1 μm. The electrode strips are 3 μm and the width of the slit is 2.5 μm.

The electrodes of the first Pixel electrode 3, the second Pixel electrode 4 and the Common electrode 7 are transparent conductive electrodes made of indium tin oxide material or other transparent conductive materials with a thickness of 100 nm, and the first Pixel electrodes with slits 3 and the second Pixel electrode 4 have a width and length of 10 μm and 40 μm, and a distance between the first Pixel electrode 3 and the second Pixel electrode 4 is 15 μm.

The material of the insulating layer is silicon nitride or silicon dioxide, with a thickness of 100nm.

The substrate is a glass substrate used in a thin film transistor liquid crystal display.

The polarizer is a polarizer used in thin film transistor liquid crystal displays, the model is G1220DU, and its azimuth angle is plus or minus 45 degrees (the included angle with the long side of the electrode).

The Cole constant of the blue phase liquid crystal is K=12.68nmV ^-2 , and the light wavelength λ=550nm.

The first Pixel electrode 3 , the second Pixel electrode 4 and the Common electrode 7 constitute a storage capacitor.

The V-T curve (transmittance change curve with voltage variation) of this embodiment and the existing IPS electrode and protruding electrode is shown in Figure 2. The transmittance is 0.203, and the transmittance of ordinary IPS electrodes is 0.179. The transmittance of the electrode in this embodiment is increased by 16.7% and 32.4% respectively compared with the triangular convex electrode and the common IPS electrode. The on-state voltage of this embodiment is 2.5V higher than that of common IPS electrodes, and the driving voltage can be easily lowered by changing the electrode gap.

The content of the manufacturing method of the present invention is a known technology, and for details, reference may be made to "TFLCD Panel Design and Construction Technology" written by Science Publishing House and Tian Minbo Yefeng.

Example 2

As shown in Figure 3 (where (a) is a top view of the surface of the lower substrate, and (b) is a cross-sectional view), the structure of the blue-phase liquid crystal display device of this embodiment includes: an upper polarizer 1, an upper substrate 2, a blue-phase liquid crystal (BPLC), the first Pixel electrode 3, the second Pixel electrode 4, the slit 5, the insulating layer 6, the Common electrode 7, the lower substrate 8, the lower polarizer 9 and the triangular protrusion 10,

in:

The lower surface of the upper middle and upper polarizer 1 is connected to the upper surface of the upper substrate 2, the upper surface of the lower middle and lower polarizer 9 is connected to the lower surface of the lower substrate 8, and other components are between the upper substrate 2 and the lower substrate 8, wherein Strip-shaped Common electrodes 7 are made on the upper surface of the lower substrate 8, arranged at equal intervals, covered with an insulating layer 6, and the insulating layer 6 is flattened. The protrusion 10 is located directly above the Common electrode 7, and the first Pixel electrode 3 The second Pixel electrode 4 is located above the insulating layer 6 and the protrusion 10, the first Pixel electrode 3 or the second Pixel electrode 4 has a slit 5 between the top and the bottom of the protrusion, and the first Pixel electrode 3 and the The second Pixel electrode 4 is applied with a potential of opposite polarity, and the blue phase liquid crystal fills the gap between the upper substrate and the lower substrate;

The distance between the upper substrate 2 and the lower substrate 8 is 12 μm.

The protrusions are made of transparent silicon nitride or silicon dioxide material, and their cross-sectional shape is a triangle with a width of 8 μm and a height of 4 μm. The top view shape is a rectangle, and the length is equal to the length of the pixel electrode. The spacing of each column of protrusions is 17 μm.

The thin slits 5 are realized by a photolithography process, and their top view is rectangular. Two thin slits 5 are respectively etched on each Pixel electrode. The overall width of the electrodes on the outer ring is 10 μm, and the width of the electrode strips on the outer ring is 1 μm. The electrode strip in the middle is 3 μm, and the slit width is 2.5 μm.

The electrodes of the first Pixel electrode 3, the second Pixel electrode 4 and the Common electrode 7 are transparent conductive electrodes, the material is indium tin oxide material or other transparent conductive materials, the thickness is 100nm, and the electrode width and length are 10 μm and 40 μm , the distance between the first Pixel electrode 3 and the second Pixel electrode 4 is 15 μm.

The material of the insulating layer is silicon nitride or silicon dioxide, and the thickness is 100-200nm.

The substrate is a glass substrate used in a thin film transistor liquid crystal display.

The polarizer is a polarizer used in thin film transistor liquid crystal displays, the model is G1220DU, and its azimuth angle is plus or minus 45 degrees (the included angle with the long side of the electrode).

The Cole constant of the blue phase liquid crystal is K=12.68nmV ^-2 , and the light wavelength λ=550nm.

The first Pixel electrode, the second Pixel electrode and the Common electrode constitute a storage capacitor.

The V-T curve (transmittance change curve with voltage variation) of this embodiment and the existing IPS electrode and protruding electrode is shown in Figure 4. The transmittance is 0.203, and the transmittance of ordinary IPS electrodes is 0.179. The transmittance of the electrode in this embodiment is increased by 9.9% and 24.6% respectively compared with the triangular convex electrode and the common IPS electrode. The on-state voltage of this embodiment is 0.5V lower than that of common IPS electrodes.

The content of the manufacturing method of the present invention is a known technology, and for details, reference may be made to "TFLCD Panel Design and Construction Technology" written by Science Publishing House and Tian Minbo Yefeng.

Example 3

As shown in Figure 5 (where (a) is a top view of the surface of the lower substrate, (b) is a cross-sectional view), the structure of the blue-phase liquid crystal display device of this embodiment includes: an upper polarizer 1, an upper substrate 2, a blue-phase liquid crystal (BPLC), the first Pixel electrode 3, the second Pixel electrode 4, the slit 5, the insulating layer 6, the Common electrode 7, the lower substrate 8, the lower polarizer 9 and the trapezoidal protrusion 10,

in:

The lower surface of the upper middle and upper polarizer 1 is connected to the upper surface of the upper substrate 2, the upper surface of the lower middle and lower polarizer 9 is connected to the lower surface of the lower substrate 8, and other components are between the upper substrate 2 and the lower substrate 8, wherein Strip-shaped Common electrodes 7 are made on the upper surface of the lower substrate 8, arranged at equal intervals, covered with an insulating layer 6, and the insulating layer 6 is flattened. The protrusion 10 is located directly above the Common electrode 7, and the first Pixel electrode 3 The second Pixel electrode 4 is located above the insulating layer 6 and the protrusion 10, the first Pixel electrode 3 or the second Pixel electrode 4 has a slit 5 between the top and the bottom of the protrusion, and the first Pixel electrode 3 and the The second Pixel electrode 4 is applied with a potential of opposite polarity, and the blue phase liquid crystal fills the gap between the upper substrate and the lower substrate;

The distance between the upper substrate 2 and the lower substrate 8 is 12 μm.

The protrusion is made of transparent silicon nitride or silicon dioxide material. Its cross-sectional shape is a trapezoid with a lower width of 8 μm, an upper width of 3 μm, and a height of 4 μm. The distance between objects is 15 μm.

The thin slit 5 is realized by photolithography process, and its plan view is rectangular. Two thin slits 5 are respectively etched on each Pixel electrode. The overall width of the outer electrode is 10 μm, and the width of the outer electrode strip is 1 μm. The electrode strips are 3 μm and the slit width is 2.5 μm.

The electrodes of the first Pixel electrode 3, the second Pixel electrode 4 and the Common electrode 7 are transparent conductive electrodes, the material is indium tin oxide material or other transparent conductive materials, the thickness is 100nm, and the electrode width and length are 10 μm and 40 μm , the distance between the first Pixel electrode 3 and the second Pixel electrode 4 is 15 μm.

The material of the insulating layer is silicon nitride or silicon dioxide, with a thickness of 100nm.

The substrate is a glass substrate used in a thin film transistor liquid crystal display.

The polarizer is a polarizer used in thin film transistor liquid crystal displays, the model is G1220DU, and its azimuth angle is plus or minus 45 degrees (the included angle with the long side of the electrode).

The Cole constant of the blue phase liquid crystal is K=12.68nmV ^-2 , and the light wavelength λ=550nm.

The first Pixel electrode, the second Pixel electrode and the Common electrode constitute a storage capacitor.

The V-T curve (variation curve of transmittance with voltage variation) of this embodiment and the existing IPS electrode and protruding electrode is shown in Figure 6. The transmittance is 0.207, and the transmittance of ordinary IPS electrodes is 0.179. Compared with the trapezoidal protrusion-shaped electrode and the common IPS electrode, the transmittance of the electrode in this embodiment increases by 5.8% and 22.3%, respectively. The on-state voltage of this embodiment is 1.0V lower than that of common IPS electrodes.

The content of the manufacturing method of the present invention is a known technology, and for details, reference may be made to "TFLCD Panel Design and Construction Technology" written by Science Publishing House and Tian Minbo Yefeng.

Example 4

As shown in Figure 7 (where (a) is a top view of the surface of the lower substrate, (b) is a cross-sectional view), this embodiment includes: an upper polarizer 1, an upper substrate 2, a blue phase liquid crystal (BPLC), and a first Pixel electrode 3. The second Pixel electrode 4, the slit 5, the insulating layer 6, the Common electrode 7, the lower substrate 8, the lower polarizer 9 and the triangular protrusion 10, wherein: the lower surface of the upper polarizer 1 and the upper surface of the upper substrate 2 The surfaces are connected, the upper surface of the lower polarizer 9 is connected to the lower surface of the lower substrate 8, the common electrodes 7 are located on the upper surface of the lower substrate, arranged at equal intervals, covered with an insulating layer 6, and the insulating layer 6 is flattened. The protrusion 10 is located on the Common electrode, the Pixel electrode is located on the uppermost layer, and the pixel electrode forms a zigzag shape.

The distance between the upper substrate 2 and the lower substrate 8 is 12 μm.

The thin slits 5 are realized by a photolithography process, and its top view is rectangular. Two thin slits 5 are respectively etched on each Pixel electrode. The overall width of the electrodes on the outer ring is 10 μm, and the width of the electrode strips is 1 μm. The bar is 3 μm, and the slit width is 2.5 μm.

The electrodes of the first Pixel electrode 3, the second Pixel electrode 4 and the Common electrode 7 are transparent conductive electrodes, the material is indium tin oxide material or other transparent conductive materials, the thickness is 100nm, and the electrode width and length are 10 μm and 40 μm , the distance between the first Pixel electrode 3 and the second Pixel electrode 4 is 15 μm.

The material of the insulating layer is silicon nitride or silicon dioxide, with a thickness of 100nm.

The substrate is a glass substrate used in a thin film transistor liquid crystal display.

The polarizer is a polarizer used in thin film transistor liquid crystal displays, the model is G1220DU, and its azimuth angle is plus or minus 45 degrees (the included angle with the long side of the electrode).

The Cole constant of the blue phase liquid crystal is K=12.68nmV ^-2 , and the light wavelength λ=550nm.

The first Pixel electrode, the second Pixel electrode and the Common electrode constitute a storage capacitor.

The Pixel electrodes, Common electrodes and protrusions are designed in a zigzag shape.

The protrusion is made of transparent silicon nitride or silicon dioxide material. Its cross-sectional shape is a triangle with a width of 8 μm and a height of 4 μm. The shape of the top view is a zigzag conforming to the pattern of the pixel electrode, and the length is equal to the length of the pixel electrode. The pitch of the bumps was 17 μm.

The V-T curve (transmittance change curve with voltage variation) of the present embodiment and the existing IPS electrode and the protruding electrode is as shown in Figure 8, the electrode transmittance of the zigzag triangular protruding band slit of the present embodiment It is 0.146, the transmittance of the zigzag triangular convex shape electrode is 0.133, and the transmittance of the zigzag ordinary IPS electrode is 0.12. Compared with the zigzag triangular electrode and the zigzag ordinary IPS electrode, the transmittance of the electrode with zigzag triangular protrusions and slits increased by 9.8% and 21.7%, respectively. The on-state voltage of this embodiment is 1.0V lower than that of common IPS electrodes.

The content of the manufacturing method of the present invention is a known technology, and for details, reference may be made to "TFLCD Panel Design and Construction Technology" written by Science Publishing House and Tian Minbo Yefeng.

The influence of the area of the storage capacitor on the transmittance is not considered in the calculations of the above embodiments. Considering the area of the storage capacitor, the transmittance of each embodiment of the present invention will be greater. The comparison of the area of the storage capacitor is shown in Figure 9, ( a) is a traditional IPS structure, and (b) is this embodiment, the light transmission range of the pixel is a rectangular enclosing area.

Claims (6)

1. a Blue-phase liquid crystal display device, is characterized by this device and comprises: upper polarizer, upper substrate, center section, infrabasal plate and lower polaroid;

Its position is followed successively by lower polaroid, infrabasal plate, center section, upper substrate and upper polarizer according to incident ray from the bottom to top by order; Center section consist of blue phase liquid crystal (BPLC), a Pixel electrode, the 2nd Pixel electrode, finedraw, insulation course, Common electrode and protrusion;

Center section wherein between upper substrate and infrabasal plate is that in following two, distribution mode is arbitrary:

Distribution mode one: on the upper surface of infrabasal plate, uniform intervals is distributed with protrusion, Common electrode covers on protrusion, insulation course covers on Common electrode and infrabasal plate, one Pixel electrode hands over the 2nd Pixel electrode the insulating layer covered mutually above evenly spaced protrusion, there is finedraw between top on protrusion of a Pixel electrode or the 2nd Pixel electrode and bottom; One Pixel electrode and the 2nd Pixel electrode additive polarity opposite potential, blue phase liquid crystal is filled in the space between upper substrate and infrabasal plate;

Or, distribution mode two: the upper surface of infrabasal plate is equidistantly arrange bar shaped Common electrode, a layer insulating is covered above the blank parts of infrabasal plate and Common electrode, insulation course carries out pressing process, protrusion is positioned at directly over Common electrode, the section-bottom width of protrusion is less than Common electrode, one Pixel electrode and the 2nd Pixel electrode are positioned at above insulation course and protrusion, finedraw is there is in the one Pixel electrode or the 2nd Pixel electrode between the top and low side of protrusion, one Pixel electrode and the 2nd Pixel electrode additive polarity opposite potential, blue phase liquid crystal is filled in the space between upper substrate and infrabasal plate.

2. Blue-phase liquid crystal display device as claimed in claim 1, it is characterized by described protrusion lateral cross section shape is triangle or trapezoidal, and longitudinal projection's shape is rectangle or one-tenth " it " shape, and be highly the half of liquid crystal thickness, scope is: 2-10 μm.

3. Blue-phase liquid crystal display device as claimed in claim 1, it is characterized by described finedraw is obtained by etching ITO electrode, and the width of finedraw is at 2-5 μm, and the width of the thin electrode of every bar is 1-5 μm.

4. Blue-phase liquid crystal display device as claimed in claim 1, the thickness of electrode scope that it is characterized by described Pixel electrode and Common electrode is: 20nm-250nm.

5. Blue-phase liquid crystal display device as claimed in claim 1, is characterized by the scope of described protrusion spacing: 5-20 μm.

6. Blue-phase liquid crystal display device as claimed in claim 1, is characterized by described thickness of liquid crystal layer scope: 5-20 μm.