CN207586455U - A kind of mirror lens and its ultrathin backlight module - Google Patents

Abstract

The utility model provides a kind of mirror lens and its ultrathin backlight module, the mirror lens includes exit facet, the plane of incidence, bottom cloudy surface, suspension column and reflecting surface, the suspension column is mounted on the bottom cloudy surface, the plane of incidence is symmetrical inner concavity, external CSP light sources are located at the indent center position of the plane of incidence, and the bottom cloudy surface is connect with the plane of incidence；The exit facet connects the bottom cloudy surface and the reflecting surface respectively；The exit facet and the reflecting surface respectively symmetrically are arranged on the left and right sides of the plane of incidence；Ultrathin backlight module includes：Optical diaphragm, diffuser plate, reflecting paper, lamp bar and cavity.The utility model mirror lens transmission effects are good, and backlight module can be made to achieve the effect that brightness uniformity, light efficiency be good, at low cost and appearance looks elegant.

Description

A kind of mirror lens and its ultrathin backlight module

Technical field

The utility model is related to lens and backlight technology field, more particularly to a kind of mirror lens and its ultrathin backlight mould Group.

Background technology

It is existing in field of liquid crystal display, since liquid crystal molecule does not have luminous power in itself, in existing liquid crystal Showing needs additional light source to obtain display picture in device, light source is spread mostly using LED light emitting diodes by backlight module at present With even light action, LED light source is extended to area source output.At this stage, the backlight module of display device can be divided into side entering type and Two kinds of straight-down negative, since down straight aphototropism mode set compared to side entrance back module does not need to setting light guide plate, thus with inexpensive Advantage, it is deep to be welcome by consumers in general.Side entrance back module is for down straight aphototropism mode set, because must add Light guide plate and lamp bar heat sink are filled, side entrance back module is made to be provided no advantage against in price.

Refering to Fig. 1, the LED of traditional down straight aphototropism mode set is Lambertian light source, and the optical lens installed additional on LED is in structure Upper to have rotational symmetry characteristic, for the light that LED light source is sent out after the diffusion of lens 301, the hot spot of formation is that have rotation pair The circular light spot of title characteristic, and the mismatch that down straight aphototropism mode set 201 is rectangular profile, hot spot and shape, necessarily cause to carry on the back Optical mode group corner and central area brightness it is uneven, influence to watch the quality of picture, meanwhile, in the situation of lamp bar quantity reduction Under, i.e., when lamp bar spacing is larger, the mixing of circular light spot can also cause the diffuser plate regional luminance between lamp bar relatively low, further Reduce brightness uniformity.Therefore it has to be changed the mixed light principle of conventional down straight aphototropism mode set.Traditional side entering type back of the body The light that the LED of optical mode group is sent out needs scattering by light guide plate mesh point, the refraction of light guide plate, makes the LED light of side incident Source is converted into the area source of front output, the refraction of the Multiple Scattering and light guide plate of site so that optical energy loss is serious, causes side It is low to enter formula backlight module light efficiency so that display picture brightness is low.

Traditional down straight aphototropism mode set and side entrance back module are for appearance looks elegant, thus it is thick deliberately to reduce side Degree since down straight aphototropism mode set and side entrance back module are due to internal structure, reduce side thickness and is identical to subtracting Few integral thickness, also implies that the space of television internal is less and less, and panel is caused all to be crowded together, it is this for appearance and The layout of compromise can cause TV heat dissipation effect bad, temperature raising, and TV is also because high temperature reduces the service life so that when occurring Barrier.

In the case where consumer is to the increasingly raising of viewing effect, raw material price raising and reducing the main trend of cost, how to change Traditional direct-type backlight, design produce a kind of high brightness uniformity, high, at low cost, appearance looks elegant the backlight module of light efficiency and Its display device becomes industry strategic point problem to be solved.

Utility model content

(1) technical problems to be solved

The technical problem to be solved by the present invention is to provide a kind of mirror lens and its ultrathin backlight modules, pass through a left side Right symmetrical rectangle mirror lens makes backlight module achieve the effect that brightness uniformity, light efficiency be good, at low cost and appearance looks elegant.

(2) technical solution

In order to solve the above technical problems, the utility model provides a kind of mirror lens and its ultrathin backlight module, reflection Lens are made of symmetrical two parts, generally rectangular；The mirror lens includes exit facet, the plane of incidence, bottom mist Face, suspension column and reflecting surface, the suspension column are mounted on the bottom cloudy surface, and the plane of incidence is symmetrical inner concavity, outside The CSP light sources in portion are located at the indent center position of the plane of incidence, and the bottom cloudy surface is connect with the plane of incidence；It is described go out It penetrates face and connects the bottom cloudy surface and the reflecting surface respectively；The exit facet and the reflecting surface respectively symmetrically are arranged on institute State the left and right sides of the plane of incidence.

Further, the reflecting surface is the arc surface of evagination, and the reflecting surface is arranged on the mirror lens upper position It puts；The exit facet is inclined surface, and the exit facet is acute angle with angle formed by the bottom cloudy surface.

Further, the material of the mirror lens is PMMA (polymethyl methacrylate), and the mirror lens is length Rectangular symmetrical lens.

Further, the technical program also provides a kind of ultrathin backlight module, including：Optical diaphragm, diffuser plate, reflection Paper, lamp bar and cavity, the reflecting paper are mounted on the cavity inner surface, and the reflecting paper is complete by the inner surface of the cavity It wraps entirely；The lamp bar is mounted on the cavity inner surface center position, and the bottom of the reflecting paper is provided with to put Put the bar shaped trepanning of the lamp bar；The diffuser plate is mounted on the cavity, and the optical diaphragm is mounted on the diffuser plate On；The lamp bar includes covering copper circuit PCB substrate, CSP light sources, mirror lens and connector；Wherein, the CSP light sources are located at The inner fovea part center position that the plane of incidence of the mirror lens is formed.

It covers copper circuit PCB substrate and is equipped with 4 fixed glue grooves, and 4 fixed glue groove non-rotational symmetries, pasted convenient for automation The mirror lens is fixed in the correct dispensing of piece equipment, ensures the correctness of 600 patch of mirror lens.

Further, the mirror lens is using reflective polarizer mode, after the beam shaping that the CSP light sources are sent out, Light spot energy is deviated to perpendicular to the lamp bar light source arragement direction, so as to expand perpendicular to lamp bar light source arragement direction Irradiation area makes single lamp bar backlight module, reduces cost.

The light that the CSP light sources are sent out, after the mirror lens, the circular light of the CSP source lights formation Spot is shaped as the double trapezoid hot spot similar to 8 numeric types, in most of light direct projection to the diffuser plate, remainder light It projects in the reflecting paper, is reflected by the reflecting paper, then project on the diffuser plate.Diffuser plate described in all directives Light, under the two-way dispersion characteristic of the diffuser plate, from the diffuser plate front be emitted, using the optical diaphragm Even light action, so as to form the planar luminous body of high brightness and uniform luminance.

Further, the CSP light sources are wafer-level package Chip Scale Package, are compared to traditional LED light Source, CSP light sources have many advantages, such as that light source is small, optical density is high, photochromic consistency is good, are more advantageous to the backlight of design production specular removal Module.

Further, the reflecting paper includes 1 bottom reflection paper, the 2 side arc surface reflecting papers in left and right and front and rear 2 sides End face reflection paper, the reflecting paper are fitted in completely on the inner surface of the cavity；The bar shaped trepanning is arranged on the bottom surface In reflecting paper, the mirror lens in the lamp bar is placed in trepanning, and the aperture widths of the reflecting paper are anti-more than or equal to described Penetrate the width of lens.

For the ultrathin type backlight module compared to traditional straight-down negative scheme, light source concentrates on the lamp of the chamber central On item, by being similar to the mixing superposition of 8 numeric type double trapezoid hot spots, the face for forming high brightness and high uniformity shines backlight module Body realizes single lamp bar backlight module, reduces cost.

Further, the lamp bar is screwed on the cavity backboard, after the completion of the lamp strip unit is matched, from upper The reflecting paper is assembled down, the mirror lens is inserted in the bar shaped trepanning of the reflecting paper, after the completion of the reflecting paper assembling, It need to ensure the planarization of reflection, reduce the reflecting paper bottom surface tilting and wave-like to the greatest extent, institute can be fixed on double faced adhesive tape It states on cavity backboard, then then the optical diaphragm is installed to the diffusion by diffuser plate assembling on the cavity On plate.

Further, the cavity inner surface free form surface is B-spline curves, and B-spline curves formula is as follows：

P (t)=[(- P0+3P1-3P2+3P3) t3+ (3P0-6P1+3P2) t2+ (- 3P0+3P2) t+ (P0+4P1+P2)]/6

X (t)=[(- X0+3X1-3X2+3X3) t3+ (3X0-6X1+3X2) t3+ (3Y0-6Y1+3Y2) t2+ (- 3Y0+3Y2) t+(Y0+4Y1+Y2)]/6

Y (t)=[(- Y0+3Y1-3Y2+3Y3) t3+ (3Y0-6Y1+3Y2) t2+ (- 3Y0+3Y2) t+ (Y0+4Y1+Y2)]/6

Wherein, P0 is known point, P0 coordinates (0,0), the coordinate (X4, Y4) and 200≤X4≤600 of P4,20≤Y4≤80； P1, P2 and P3 are optimal control point, and the coordinate of P1, P2 and P3 is P1 (X1, Y1), P2 (X2, Y2) and P3 (X3, Y3), and 0 ＜ X1 600,0 ＜ Y1 ＜ Y2 ＜ Y3 ＜ 80 of ＜ X2 ＜ X3 ＜；T, t2, t3 are the B sample curves calculated according to corresponding B samples curve equation On point, connected with the mode of drawing beeline section successively these points, just obtained corresponding B samples curve.

Further, the face type of the lamp bar bottom reflection paper is rectangle free form surface, and the width of bottom reflection paper More than or equal to the length of the lamp bar, the bottom reflection paper is extended around to the edge of the diffuser plate.

Further, the size range of the diffuser plate lower surface to cavity upper surface distance is 0~80mm；It is described Optical diaphragm may be selected to be brightness enhancement film, composite membrane or diffusion barrier.

Traditional backlight module appearance is old-fashioned, and thickness is uniform, without special bright spot, the appearance of backlight module in the technical program Back side both sides are arc-shaped, and thick middle both sides are thin, and consumer is made to form the vision of super-thin when watching.

(3) advantageous effect

The ultrathin backlight module of the utility model makes the circular light spot shaping of CSP light sources by completely new mirror lens To be similar to 8 numeric type double trapezoid hot spots, using the mode of reflective polarizer, mode among the placed longitudinally cavity of single lamp bar into Row projection, increases projection distance；Light source is concentrated in lamp bar, compared to traditional down straight aphototropism mode set, it is possible to reduce cost is higher Pcb board quantity, so as to reduce production cost；Double trapezoid hot spot can also improve module corner brightness simultaneously, so as to improve The brightness uniformity of entire backlight module.

Description of the drawings

Fig. 1 is the mixed light schematic diagram of conventional down straight aphototropism mode set in the prior art；

Fig. 2 is the exploded perspective view of the utility model ultrathin backlight module；

Fig. 3 is the structure diagram of the utility model ultrathin backlight module；

Fig. 4 is the utility model ultrathin backlight module mixed light schematic diagram；

Fig. 5 is the stereoscopic schematic diagram of the utility model mirror lens；

Fig. 6 is the structure diagram of the utility model mirror lens；

Fig. 7 is the structure diagram of the suspension column of the utility model mirror lens bottom；

Fig. 8 is the index path of the utility model ultrathin backlight module；

Fig. 9 is the light distribution curve of the utility model mirror lens；

Wherein：100 it is optical diaphragm, 200 be diffuser plate, 201 be down straight aphototropism mode set, 300 be reflecting paper, 301 is Lens, 400 be lamp bar, 401 be CSP light sources, 500 be cavity, 600 be mirror lens, 601 be exit facet, 602 be the plane of incidence, 603 it is bottom cloudy surface, 604 be suspension column, 605 is reflecting surface.

Specific embodiment

Refering to Fig. 2~Fig. 9, the utility model provides a kind of mirror lens and its ultrathin backlight module, refering to Fig. 5, Fig. 6 And Fig. 7, the present embodiment mirror lens 600 are made of symmetrical two parts, global shape is generally rectangular；Mirror lens 600 include exit facet 601, the plane of incidence 602, bottom cloudy surface 603, suspension column 604 and reflecting surface 605, and refering to Fig. 7, suspension column 604 is installed On bottom cloudy surface 603, the plane of incidence 602 is symmetrical inner concavity, and external CSP light sources 401 are located at the interior of the plane of incidence 602 Recessed center position, bottom cloudy surface 603 are connect with the plane of incidence 602；Exit facet 601 connects bottom cloudy surface 603 and reflecting surface respectively 605；Exit facet 601 and reflecting surface 605 respectively symmetrically are arranged on the left and right sides of the plane of incidence 602.

Refering to Fig. 5 and Fig. 6, reflecting surface 605 is the arc surface of evagination, and reflecting surface 605 is arranged on 600 upper position of mirror lens It puts；Exit facet 601 is inclined surface, and exit facet 601 is acute angle with angle formed by bottom cloudy surface 603.

Wherein, the material of mirror lens 600 is PMMA (polymethyl methacrylate), and mirror lens is rectangle or so pair The lens of title.

Refering to Fig. 2 and Fig. 3, the present embodiment also provides a kind of ultrathin backlight module, including：Optical diaphragm 100, diffuser plate 200th, reflecting paper 300, lamp bar 400 and cavity 500, reflecting paper 300 are mounted on 500 inner surface of cavity, and lamp bar 400 is mounted on chamber 500 inner surface center position of body, the bottom of reflecting paper 300 are provided with the bar shaped trepanning for placing lamp bar 400；Diffuser plate 200 are mounted on cavity 500, and optical diaphragm 100 is mounted on diffuser plate 200, and optical diaphragm 100 can pass through the extension of diaphragm edge Ear and the cooperation positioning of 500 top edge fixed bit of cavity；Lamp bar 400 includes covering copper circuit PCB substrate, CSP light sources 401, reflection Lens 600 and connector；Wherein, CSP light sources 401 are located at the inner fovea part center that the plane of incidence 602 of mirror lens 600 is formed Place.

Fig. 4 is the mixed light schematic diagram of the present embodiment ultrathin type backlight module, when ultrathin backlight module only uses a lamp bar When, region that single lamp bar needs irradiate is rectangle area source, the utility model embodiment according to module size using 5~ 50PCS light sources and 2~10PCS mirror lens, a mirror lens is corresponded to per several CSP light sources, and every mirror lens needs The region A of irradiation is double trapezoid area source.Due to irradiation region in the Y direction (lamp bar axis direction) and X-direction (perpendicular to lamp Axis direction) deviation is too big, and the circular light spot mixing of conventional lenses can not meet demand；The CSP of the utility model embodiment The light that light source is sent out after mirror lens 600 is reflected and reflected, forms the double trapezoid hot spot similar to 8 numeric types, ladder Vertical 400 axis of lamp bar of shape hot spot long axis, short axle are located on 400 axis of lamp bar.Trapezoidal light spot short-axis direction partial stack mixes, So as to complete the uniform mixing of entire backlight module light.

Wherein, it covers copper circuit PCB substrate and is equipped with 4 fixed glue grooves, and 4 fixed glue groove non-rotational symmetries, convenient for certainly The correct dispensing fixation reflex lens 600 of dynamicization patch device ensure the correctness of 600 patch of mirror lens.The PCB of lamp bar 400 Plate is high anti-ink to cover copper aluminum substrate, surface ink, and 400 quantity of lamp bar is 1PCS, described according to module size CSP quantity of light source is 5~50PCS, and mirror lens quantity is 2~10PCS, and the mirror lens shape is rectangle；It is described anti- Penetrate paper thickness 0.18mm~0.3mm；200 thickness of diffuser plate is 1.0~3mm.

Mirror lens 600 uses reflective polarizer mode, and after the beam shaping that CSP light sources 401 are sent out, light spot energy is to hanging down It is directly deviated in 400 light source arragement direction of lamp bar, so as to expand in the irradiation area perpendicular to lamp bar light source arragement direction, makes list Lamp bar backlight module, reduces cost.

The light that CSP light sources 401 are sent out, after mirror lens 600, the circular light spot quilt of 401 light of CSP light sources formation It is shaped as the double trapezoid hot spot similar to 8 numeric types, in most of light direct projection to diffuser plate 200, the projection of remainder light It onto reflecting paper 300, reflects, then is projected on diffuser plate 200 by reflecting paper 300.The light of all directive diffuser plates 200, Under the two-way dispersion characteristic of diffuser plate 200, from the outgoing of the front of diffuser plate 200, using the even light action of optical diaphragm 100, So as to form the planar luminous body of high brightness and uniform luminance.

Wherein, CSP light sources 401 are wafer-level package Chip Scale Package, are compared to Conventional LED light sources, CSP Light source has many advantages, such as that light source is small, optical density is high, photochromic consistency is good, is more advantageous to the backlight module of design production specular removal.

In the present embodiment, reflecting paper 300 includes 1 bottom reflection paper, left and right 2 side arc surface reflecting papers and front and rear 2 A side end face reflecting paper, reflecting paper 300 are fitted in completely on the inner surface of cavity 500；Bar shaped trepanning is arranged on bottom reflection paper On, the mirror lens 600 in lamp bar 400 is placed in trepanning, and the aperture widths of reflecting paper 300 are greater than or equal to mirror lens 600 Width.

Compared to traditional straight-down negative scheme, light source concentrates in the lamp bar 400 at 500 center of cavity ultrathin backlight module, Backlight module is formed high brightness and the planar luminous body of high uniformity, is realized by being similar to the mixing superposition of 8 numeric type double trapezoid hot spots Single lamp bar backlight module, reduces cost.

Wherein, lamp bar 400 is screwed on 500 backboard of cavity, after the completion of lamp bar 400 is assembled, is filled from top to bottom With reflecting paper 300, mirror lens 600 is inserted in the bar shaped trepanning of reflecting paper 300, after the completion of reflecting paper 300 is assembled, need to ensure to reflect Planarization, reduce to the greatest extent 300 bottom surface of reflecting paper tilt and wave-like, can be fixed on double faced adhesive tape on 500 backboard of cavity, Diffuser plate 200 is assembled on cavity 500 again, then optical diaphragm 100 is installed on diffuser plate 200.

Refering to Fig. 3,500 inner surface free form surface of cavity is B-spline curves, and B-spline curves formula is as follows：

P (t)=[(- P0+3P1-3P2+3P3) t3+ (3P0-6P1+3P2) t2+ (- 3P0+3P2) t+ (P0+4P1+P2)]/6

X (t)=[(- X0+3X1-3X2+3X3) t3+ (3X0-6X1+3X2) t3+ (3Y0-6Y1+3Y2) t2+ (- 3Y0+3Y2) t+(Y0+4Y1+Y2)]/6

Y (t)=[(- Y0+3Y1-3Y2+3Y3) t3+ (3Y0-6Y1+3Y2) t2+ (- 3Y0+3Y2) t+ (Y0+4Y1+Y2)]/6

Wherein, P0 is known point, P0 coordinates (0,0), the coordinate (X4, Y4) and 200≤X4≤600 of P4,20≤Y4≤80； P1, P2 and P3 are optimal control point, and the coordinate of P1, P2 and P3 is P1 (X1, Y1), P2 (X2, Y2) and P3 (X3, Y3), and 0 ＜ X1 600,0 ＜ Y1 ＜ Y2 ＜ Y3 ＜ 80 of ＜ X2 ＜ X3 ＜；T, t2, t3 are the B sample curves calculated according to corresponding B samples curve equation On point, connected with the mode of drawing beeline section successively these points, just obtained corresponding B samples curve.

Wherein, the face type of 400 bottom reflection paper of lamp bar be rectangle free form surface, and the width of bottom reflection paper be more than or Equal to the length of lamp bar 400, bottom reflection paper is extended around to the edge of diffuser plate 200.

Wherein, the size range of 200 lower surface of diffuser plate to 500 upper surface distance of cavity is 0~80mm；500 bottom of cavity Portion both sides are arc-shaped, and thick middle both sides are thin, and the size range of 200 lower surface of diffuser plate to 500 bottom plane distance of cavity is 20~80mm, the distance of 500 both sides of the face of cavity to 200 lower surface of diffuser plate is 0mm.

Optical diaphragm 100 may be selected to be brightness enhancement film, composite membrane or diffusion barrier.

Fig. 8 is the index path of the present embodiment ultrathin backlight module, and the light projected from mirror lens 600, part is directly penetrated To diffuser plate 100, directive diffuser plate 200, all 300 directives of reflecting paper are spread again for reflection of some light Jing Guo reflecting paper 300 The light of plate 200, under the two-way dispersion characteristic of diffuser plate 200, from 200 front outgoing of diffuser plate, using optical diaphragm 100 Even light action, so as to form the backlight planar luminous body of high brightness and uniform luminance.

Fig. 9 is the light distribution curve of the present embodiment mirror lens, and the light beam that CSP light sources 401 are sent out passes through the plane of incidence 602 reflect in less than x ° in reflecting surface 605, are reflected by reflecting surface 605 toward exit facet 601, and CSP light sources 401 send out light beam, Exit facet 601 is reflected more than x ° by the plane of incidence 602, the general beam direction for being sent out CSP light sources 401 passes through reflective polarizer Lens 600 are projeced into entire cavity extremely to the cavity left and right sides entirely.Wherein x ° of value range is 30 °~60 °.

Traditional backlight module appearance is old-fashioned, and thickness is uniform, without special bright spot, the appearance of backlight module in the technical program Back side both sides are arc-shaped, and thick middle both sides are thin, and consumer is made to form the vision of super-thin when watching.

The present embodiment ultrathin type backlight module makes the circular light spot of CSP light sources be shaped as class by completely new mirror lens 8 numeric type double trapezoid hot spots are similar to, using the mode of reflective polarizer, the mode among the placed longitudinally cavity of single lamp bar is thrown It penetrates, increases projection distance；Light source is concentrated in lamp bar, compared to traditional down straight aphototropism mode set, it is possible to reduce the higher PCB of cost The quantity of plate, so as to reduce production cost；Double trapezoid hot spot can also improve module corner brightness simultaneously, so as to improve the entire back of the body The brightness uniformity of optical mode group.

The above is only the preferred embodiment of the utility model, it is noted that for the common skill of the art For art personnel, under the premise of the utility model technical principle is not departed from, several improvements and modifications can also be made, these change The scope of protection of the utility model is also should be regarded as into retouching.

Claims (8)

1. a kind of mirror lens, which is characterized in that mirror lens (600) includes exit facet (601), the plane of incidence (602), bottom mist Face (603), suspension column (604) and reflecting surface (605), the plane of incidence (602) be symmetrical inner concavity, external CSP light Source (401) is positioned at the indent center position of the plane of incidence (602), the bottom cloudy surface (603) and the plane of incidence (602) Connection；The exit facet (601) connects the bottom cloudy surface (603) and the reflecting surface (605) respectively；The exit facet (601) and the reflecting surface (605) respectively symmetrically is arranged on the left and right sides of the plane of incidence (602).

2. mirror lens as described in claim 1, which is characterized in that the mirror lens (600) is by symmetrical two It is grouped as.

3. mirror lens as described in claim 1, which is characterized in that the reflecting surface (605) is the arc surface of evagination, described Reflecting surface (605) is arranged on the mirror lens (600) top position.

4. mirror lens as described in claim 1, which is characterized in that the exit facet (601) be inclined surface, the exit facet (601) and angle formed by the bottom cloudy surface (603) is acute angle.

5. a kind of ultrathin backlight module including mirror lens described in claim 1, which is characterized in that including：Optical diaphragm (100), diffuser plate (200), reflecting paper (300), lamp bar (400) and cavity (500), the reflecting paper (300) is mounted on described On cavity (500) inner surface, the lamp bar (400) is mounted on the cavity (500) inner surface center position, the reflecting paper (300) bottom is provided with the bar shaped trepanning for placing the lamp bar (400)；The diffuser plate (200) is mounted on the chamber On body (500), the optical diaphragm (100) is on the diffuser plate (200)；The lamp bar (400) including PCB substrate, CSP light sources (401), mirror lens (600) and connector.

6. ultrathin type backlight module as claimed in claim 5, which is characterized in that the reflecting paper (300) is anti-including 1 bottom surface Penetrate paper, the 2 side arc surface reflecting papers in left and right and front and rear 2 side end face reflecting papers.

7. ultrathin type backlight module as claimed in claim 5, which is characterized in that the face of lamp bar (400) the bottom reflection paper Type is rectangle free form surface, and the width of bottom reflection paper is greater than or equal to the length of the lamp bar (400), and the bottom surface is anti- Penetrate the extending around to the edge of the diffuser plate (200) of paper.

8. ultrathin type backlight module as claimed in claim 5, which is characterized in that diffuser plate (200) lower surface is described in The size range of cavity (500) upper surface distance is 0~80mm.