KR101460257B1 - LED lamp - Google Patents

Abstract

The present invention not only has a cover fixing means and a glass fixing means to facilitate maintenance, but also has a light guide plate to improve the illuminance and has a fixing means for use in a home as well as a tunnel In addition, when a plurality of LED panels are connected in parallel to each other, even when an abnormality occurs in one of the LED panels, illumination can be performed by the LEDs of the remaining LED panels, and the cover can be firmly fixed, The present invention relates to an LED lighting device that prevents a cover from being detached from a main body due to vibration caused by passage of a vehicle when installed in a tunnel.

Description

LED lighting apparatus {LED lamp}

The present invention relates to an LED lighting apparatus, and more particularly, to an LED lighting apparatus having a cover fixing means and a glass fixing means for facilitating maintenance, and a light guide plate having an improved efficiency, thereby improving illuminance .

In addition, the present invention is not limited to fixing means for use in tunnels as well as in general households, but also includes a plurality of LED panels connected in parallel so that even when an error occurs in one of the LED panels, The present invention relates to an LED light fixture which can be illuminated by a light source.

In addition, the present invention can provide a fixing means that can firmly fix the cover and facilitate the detachment of the cover, thereby facilitating maintenance. In addition, when the cover is installed in a tunnel, To an LED lighting device which prevents the LED lighting device from being detached from the main body.

Fluorescent lamps and incandescent lamps are often used as lamps, but fluorescent lamps use less fluorescent light than incandescent lamps, so they are mostly used for lighting purposes, and most offices use these fluorescent lamps. However, since a fluorescent lamp has a low luminous intensity and low energy efficiency, recently, LED lighting using a light emitting diode (hereinafter referred to as "LED") has been widely used as an illumination lamp having relatively high illuminance and low power consumption .

The LED illumination typically includes an LED substrate on which a plurality of LEDs are mounted and a circuit pattern is formed on the LED to supply power to the LED, and a housing for supporting the LED substrate. The power supply includes a power supply for supplying power to the LED. [0003] In such an LED illumination, a lot of heat is generated when the LED is emitted, and various techniques for discharging such heat have been developed. Patent literatures 1 and 2 are technologies related to such LED illumination.

Patent Document 1 is an improvement of the heat dissipation structure. In order to improve the heat dissipation effect, Patent Document 1 proposes an outer heat dissipation tube 100 in which a plurality of heat dissipation vanes 100w radially protrude from the outer surface, and a plurality of heat dissipation vanes 200w are formed on the inner surface of the inner tube 200 to allow heat dissipation to the outside. This is an air-cooling system in which the heat radiation is made only by the heat dissipation vane.

Patent Document 2 discloses a frame having an upper plate attached to a ceiling and a side plate formed on the periphery of the upper plate and having a plurality of mounting holes formed on an upper plate, A substrate mounted on a lower surface of the upper plate of the frame to close the mounting hole and having a plurality of LEDs mounted on a lower surface thereof; And a stabilizer mounted on the upper surface of the substrate and inserted into the mounting hole. The LED illumination of Patent Document 2 is advantageous in that the safety device can be easily replaced, but only a single LED panel is required to replace the entire device when a failure occurs.

In other words, in the conventional LED lighting, when a failure occurs in the panel on which the LED is mounted, it is not possible to function as an illumination unless the entire LED panel is replaced, and the cooling efficiency is lowered. There is a problem that the constituent components are easily aged by heat.

In addition, when the LED light is installed in a place such as a tunnel, a cover made of a transparent material is installed to protect the LED from foreign substances such as dust inside the tunnel. The cover is generated by a vehicle passing through the inside of the tunnel There has been a problem of causing a vehicle accident by being separated from the main body by vibration and falling.

Meanwhile, the development process of the LED illumination lamp or the illumination lamp proceeds in four ways. A process of developing a light source (LED) for packaging using an LED chip, a process of developing and processing a heat sink for emitting heat generated by the LED device, a converter as a device for supplying driving power of the LED device, Or a light guide plate (diffusion plate) for diffusing light by an amount of light.

Since most of the manufacturers that produce the LED lighting lamps developed by this process are small and medium-sized enterprises, it is difficult to research and develop the LED lighting sources. Therefore, the emphasis is on developing a heat sink for emitting heat from the LED device, a converter for driving the LED device, and an optical lens for diffusing light.

However, optical lenses require both optical technology and mold design technology. Also, since the light distribution is different according to the purpose and the purpose of use, various types of lens design and mold are required.

 For this reason, most SMEs do not develop lenses to be applied to illumination lamps and illumination lamps themselves, but purchase standardized lenses of large companies and design LED modules, heat sinks and luminaires in accordance with the diffusion unit (lens) As shown in FIG. 19, such a conventional LED light has a lens installed in each LED to diffuse light, or a diffusion unit as shown in FIG. 20 is installed to diffuse light.

However, as shown in FIG. 19, when lenses are provided in the respective LEDs, much time and manpower are required for mounting the lenses, resulting in poor productivity and mass production, raising the cost of the product. As described above, when the diffusion unit is used, each of the luminous intensities is formed in a first order, and the luminous intensities of the luminous intensities are generated by overlapping the luminous intensities of the luminous intentions.

1 Korea Utility Model Open Publication No. 2010-0009279 2 Korea Utility Model Registration No. 0468247

The present invention has been developed in order to solve the problems described above, and it is an object of the present invention to provide an LED lighting fixture having a light guide plate and improved illuminance, as well as a cover fixing means and a glass fixing means for facilitating maintenance .

Further, the present invention provides at least two LED panels connected in parallel so that even when an abnormality occurs in one of the LED panels, illumination can be performed by the LEDs of the remaining LED panels, .

Further, according to the present invention, the fixing means for fixing the cover not only facilitates the detachment of the cover, but also makes it possible to firmly fix the cover, thereby facilitating maintenance and preventing an accident caused by the fall of the cover. And to provide the above-mentioned objects.

According to an aspect of the present invention, there is provided an LED lighting device comprising: a body having a plurality of radiating fins formed on a rear surface thereof, a lamp housing part formed at a center of a front surface thereof, At least two LED panels having a plurality of LED lamps and installed at a lamp inner surface of the center of the body; A power supply installed in the electric component part of the electrical component; A switch installed in the electric component mounting portion of the electrical component; A cover detachably installed on the front surface of the body and having a transparent transparent portion 501 formed at the center thereof, Fixing means installed on the rear or side of the body for fixing the lighting device to another structure; And a clamp rotatably installed on the outer surface of the body for fixing the cover.

Preferably, a tuck is further formed between the outer surface of the lamp holding portion and the outer surface of the electrical component mounting portion, and a packing is further provided at the end of the tang.

The clamp has a handle for pivoting the handle in a state of being gripped by a hand at one end about a pivot pin for pivotally fixing the outer wall of the body, and a cover pressing portion and a clearance insertion protrusion are formed on the opposite side of the handle, When the pressing portion cover is pressed, the gap inserting portion is inserted into the gap between the jaw and the outer circumferential surface of the body, so that it can be prevented from rotating without a force acting from the outside.

As described above, the LED lighting apparatus according to the present invention is provided with a hinge means on one side of a cover, and the cover is provided so as to be completely opened so as to open the cover but not separate from the body, Therefore, the cover can be easily separated from the cover without a force exerted from the outside when the cover is closed. Thus, it is possible to prevent an accident caused by the fall of the cover.

In addition, since the fixing means can be installed in various ways, it can be used not only in tunnels but also in ordinary homes.

In addition, when a plurality of LED panels are connected in parallel, even when an abnormality occurs in one of the LED panels, illumination can be performed by the LEDs of the remaining LED panels.

1 is a perspective view of an example of an LED illumination device according to the present invention.
Fig. 2 is a perspective view of an example of the LED lighting apparatus according to the present invention,
Fig. 3 is an enlarged perspective view of the hinge means.
4 is an exploded perspective view showing an example of the fixing means.
5 is a plan view of a body and an LED panel constituting an LED lighting device according to the present invention.
6 is a longitudinal sectional view of an LED lighting device according to the present invention
Fig. 7 is a cross-sectional view of an example of a clamp constituting the LED lighting apparatus according to the present invention
8 is a cross-sectional view of a part of a radiating fin provided on the body of the LED lighting apparatus according to the present invention
9 is a rear perspective view of the LED lighting apparatus according to the present invention,
10 is a photograph of an example of a light guide plate installed in an LED lighting device according to the present invention
11 is a bottom view showing a part of the light guide plate
12 is a cross-sectional view taken along line CC of Fig. 11
13 is a cross-sectional view taken along line DD of Fig. 11
Fig. 14 is a graph showing illuminance distribution of a black and white LED lighting apparatus using a light guide plate according to the present invention
FIG. 15 is a graph showing illuminance distribution of a color LED lighting device using the light guide plate of the present invention
16 is a view showing a light distribution curve of a lighting device using the light guide plate of the present invention
17 is a photograph showing a part of the LED lighting apparatus according to the present invention
18 is a graph showing the results of simulation of uniformity of illumination of the LED lighting apparatus according to the present invention
19 is a view showing a state where the lens
20 is a diagram showing the light distribution diagram of the diffusion unit of the conventional LED lighting apparatus

Hereinafter, an LED lighting device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The terms used in the present invention are used only for describing specific embodiments, and are not intended to limit the present invention, and redundant explanations for the same parts as those of the prior art are omitted.

The present invention has not only cover fixing means and glass fixing means to facilitate maintenance, but also has a light guide plate to improve the illuminance. A plurality of radiating fins 10c are formed on the rear surface, and a lamp A body 10 in which a notched portion 10l is formed and electrical parts 10e are formed at both ends thereof; At least two LED panels (20) having a plurality of LED lamps and installed at lamp bulb portions at the center of the body; A power supply (30) installed in the electric component part of the electrical component; A switch (40) installed in the electrical component part of the electrical component; A cover (50) detachably mounted on the front surface of the body and having a transparent light transmitting portion (501) formed at the center thereof corresponding to the lamp holding portion; Fixing means (60) installed on the rear or side of the body for fixing the lighting device to another structure; And a clamp 70 that is rotatably installed on the outer surface of the body and fixes the cover.

As shown in FIGS. 1 and 2, the body 10 is formed as a hollow body having an empty interior, a portion where the LED panel 20 is installed is formed so as not to be deep inside, and a plurality of heat- So that the heat generated by the LED panel can be discharged more efficiently.

That is, the body 10 is provided with electrical component mounting portions 10e on both sides of the central lamp-receiving portion 10l. Of course, it is also possible to form only one electrical component part 10e or to form two electrical components 10e, but the switch 40 and the power supply 30 may be separately provided on both sides with the space narrowed.

2, when the electrical component mounting portion 10e is divided into two parts, and the switch 40 and the power supply 30 are installed on only one side, the other electrical component mounting portion is provided with other spare parts necessary for maintenance and repair of the luminaire It can also be used as a storage room for storing goods.

The LED panel 20 may include a plurality of LED lamps, as shown in FIGS. 1, 2 and 5. By dividing the LED panel 20 into a plurality of LED panels 20 and connecting them in parallel, even if one of the LED panels is damaged, another LED panel can be operated to perform heat generation.

The power supply 30 is a means for supplying AC power to the LED panel 20 by converting the AC commercial power into DC power. The power supply 30 is a power supply unit that supplies power to the computer system. Power Supply) can be used. The SMPS is a power supply suitable for the LED lighting apparatus of the present invention which is hung on the electric field because it is more efficient than the conventional linear power supply apparatus, has high durability, and is small and light in weight.

The switch 40 may be an ELB circuit breaker capable of protecting the LED panel from an electric leak due to leakage when it is installed outside, such as a tunnel.

The cover 50 protects and protects electrical parts including the LED panel installed inside the body 10 from the outside and serves as a window for irradiating the light generated from the LED panel to the outside. 2, a transparent transparent portion 50w is formed so as to allow light to pass through at a portion opposed to the central lamp-holding portion 101. Opposite ends opposed to the electrical-component holding portion 10e are opaque And blocked the appearance of the electrical parts on the outside.

As shown in FIG. 2, the cover 50 is hingedly fixed to the body 10 by a hinge means 90 so as to rotate around the hinge means. When the cover 50 is opened, the cover 50 is horizontally The hinge means 90 is provided adjacent to a side wall of the body so as to be openable to a degree that can be achieved, and includes a lifting and lowering fixture 91 for vertically movably fixing the lower end of the following connection pin 92; A connection pin 92 having one end thereof vertically movably inserted into an elevating groove 91g formed on one side of the elevating fixture and pivotally connected to the cover at the other end; And a cover fixing plate 93 for rotatably coupling the other end of the connection pin to the cover.

The lower end of the connecting pin 92 is elevated and lowered along the elevating groove 91g formed with the elevating and lowering fixture 91 so that the height of the connecting pin 92 is increased. When the cover is opened, the lower end of the connection pin descends to open completely to the cover, and when the cover is closed, the lower end of the connection pin descends to close the cover easily.

The clamp 70 is provided to allow the cover 50 to be opened and closed in a closed state so as to be warped to the body.

As shown in FIG. 7, the clamp 70 may be variously modified. However, it is preferable that the clamp 70 is formed with a pivot pin 70p which is rotatably fixed to the outer wall of the body, A cover pressing portion 70c and a clearance inserting portion 70g are formed on the opposite side of the handle portion so that the cover pressing portion 70c is pressed by the cover 50 The insertion protrusion 70g is fitted in the gap between the jaw and the outer circumferential surface of the body so that the insertion protrusion 70g is not rotated without a force acting from the outside.

The above-described fixing means 60 is provided to fix the lighting apparatus constructed as described above to other structures.

"형상을 이루게 제작한 것이다. 이렇게 구성된 고정수단(60)은 도 6에 도시한 바와 같이 몸체의 배면에 형성된 고정홀에 중간부분이 고정되고, 양단이 벽이나 지지구조물에 고정됨에 의해 조명기구가 원하는 위치에 설치되는 것이다. The fixing means 60 can be variously modified depending on the place where the lighting device is installed, the position of the structure, and the method of use. For example, as shown in FIGS. 1, 2 and 6, The metal plate is bent so that the cross-

6, the middle part is fixed to the fixing hole formed on the back surface of the body, and both ends are fixed to the wall or the supporting structure, It is installed at a desired position.

Another example of the fixing means 60 is configured as shown in Figs. 2, 4 and 9. As shown in FIG. 4, the lighting fixture is fixed to a fixed blade 11 formed on one side of the body and has a plurality of concentric circles on the outer surface thereof. A fixing plate 61 on which the latching groove 61g is formed; A plurality of locking projections 62d engaging with the locking grooves formed in the fixing plate, and a fixing plate 62 having a fixing groove 62g in which a fixing object is fitted and fixed to a part of the portion where the locking protrusions are formed; And fixing nuts 60n and fixing bolts 60b for fixing the fixing plate and the adjusting plate to the fixing vanes.

9, the fixed object is inserted into the fixing groove 62g, and then the fixing bolt is tightened to fasten the fixing plate 61 and the adjusting plate 62 to the engaging groove 61g formed on the mutually facing surfaces, When the direction of the lighting device is to be adjusted, the fixing bolt is loosened so that the locking protrusion 62d is released from the locking groove 61g, and the adjusting plate 62 is rotated to fix the fixing groove 62g. ≪ / RTI >

As described above, the lighting apparatus according to the present invention may be installed outside, such as a tunnel, a street, or the like. When the lighting apparatus is installed so as to be exposed to the outside, foreign substances or water may enter between the cover 50 and the body 10 . A tuck 10w is formed between the lamp inner surface portion and the electrical component mounting portion so as to prevent foreign substances or water from flowing into the lamp inner surface portion and the electrical component mounting portion, 80) was installed to prevent leakage of water or foreign matter.

As described above, a large number of heat dissipation fins 10c are formed on the rear surface of the body, as described above, in order to efficiently discharge the heat generated in the LED panel 20 as described above.

The heat dissipation fin 10c may be formed to discharge the heat generated from the LED panel to the outside. However, as shown in FIG. 8, in order to more efficiently discharge heat, a portion of the heat dissipation fin 10c, A vent hole 10h was further formed. By further forming the vent hole 10h, the air introduced into the end of the radiating fin is discharged via the outer wall of the body, thereby enhancing the cooling efficiency.

Further, the present invention is characterized in that the light guide plate 21 is provided to improve the illuminance as described above. Hereinafter, the structure of the light guide plate 21 will be described in detail.

10 is a photograph of an example of a light guide plate installed in an LED lighting device according to the present invention.

As shown in the drawing, the light guide plate 21 has a plurality of second lens portions 21d in the form of a half elliptical ball on the first lens portion 21p in the form of a plate, and a plurality of fixing portions 21d for fastening to the LED panel 20 Holes are formed.

11, a first lens portion 21p, a second lens portion 21d, and a groove 21g are formed. In this light guide plate, as shown in Figs. 12 and 13, And a semi-elliptical groove 21g is formed on the inner surface opposite to the LED panel 20. As shown in Fig.

That is, the light guide plate 21 applied to the present invention has a surface structure in which the bottom surface of the second lens portion 21d is extended to the left and right, and the semi-elliptical grooves 21g formed on the inner surface of the first lens 21p The bottom surface has an upper and lower elliptical structure, and the second lens portion 21d and the groove 21h are asymmetric as shown in Fig.

Such a light guide plate 21 will be described with reference to FIGS. 12 and 13. FIG.

Fig. 12 is a cross-sectional view taken along the line C-C of Fig. 11, and Fig. 13 is a cross-sectional view taken along the line D-D of Fig.

11, the groove 21g is formed on the side of the second lens portion 21d so that the wall between the second lens portion 21d and the groove 21g is constant So that the thickness can be maintained.

That is, as shown in FIG. 12, the second lens portion 21d is characterized by a semi-elliptical shape in which the peak is inclined from the center to one side. The angle a3 formed between the side wall of the groove 21g and the bottom surface of the light guide plate is 40 degrees to 50 degrees and the thickness of the first lens portion 21p is within a range of 2.30 mm to 2.8 mm. The second lens portion 21d is formed on the upper portion of the first lens portion 21p and has a thickness of 1.6 mm to 1.9 mm. The second lens portion 21d has a flat surface of the first lens portion 21p, The angles (a1, a2) between them are 55 degrees to 65 degrees.

13, the light guide plate 21 is disposed at one side of two angles a3 and a4 formed between the side wall of the groove 21g and the bottom surface of the light guide plate, that is, Since the angle a7 formed by the side wall of the portion is in the range of 90 to 97 degrees and the angle a8 on the multi-side is 20 to 30 degrees, the groove 21 is inclined to one side, Respectively.

The second lens 21d has a structure in which the highest point is formed at an inclined position from the center to the first side. The angle a5 of one of the two angles a5 and a6 with the surface of the light guide plate is 35 degrees to 45 degrees, The angle (a6) of the angle? Is 55 degrees to 65 degrees. Accordingly, the highest point of the groove 21g is formed opposite to the highest point of the second lens unit 21d.

As shown in FIG. 14 and FIG. 15, the light guide plate installed in the lighting apparatus according to the present invention has a uniform diffusion of light.

14 is an illuminance distribution diagram of a monochrome LED point light source using the light guide plate of the present invention. In FIG. 14 (a), the monochrome LED point light source using the LED point light source light guide plate has a maximum illumination at a distance of 1 m from the monochrome LED point light source at a center axis of 200 mm to -1000 mm on the horizontal axis, It can be seen that it is diffused. 14 (b), the vertical maximum illuminance is about 7.2 W / m 2 at the lower side of about -400 mm in the range of + 2000 mm to -2000 mm on the left and right and -2000 mm to +2000 mm on the upper and lower sides with respect to the center point, And an illuminance of 8.8 W / m 2 at a point of -350 mm. In FIG. 7 (b), when the vertical graph and the horizontal graph are compared, the light is diffused up and down and left and right, and the left and right are more diffused than the up and down.

FIG. 15 is a graph showing the illuminance intensity of an LED point light source using the light guide plate of the present invention in a color. In FIG. 15 (a), the color LED point light source using the LED point light source light guide plate has a maximum illuminance at a distance of 1 m from the color LED point light source at a center axis of 200 mm to -1000 mm on the horizontal axis, . 15 (b), the vertical maximum illuminance is about 6.9 W / m 2 at the lower side of about -400 mm in the range of -2000 mm to +2000 mm on the right and left sides and -2000 mm to +2000 mm in the upper and lower sides, And an illuminance of 8.8 W / m 2 at a point of -350 mm. Also, in FIG. 15 (b), when the vertical graph and the horizontal graph are compared, it is understood that the light is diffused upward, downward, leftward and rightward, and further diffused to the left and right than the upper and lower.

16 is a light distribution curve of the LED point light source using the light guide plate of the present invention. As shown in the drawing, the light guide plate provided in the lighting apparatus of the present invention indicates that light is diffused in a radial direction within a certain angle range.

FIG. 17 shows a photograph of one example of the lighting apparatus having the light guide plate 21 as described above. As shown in the drawing, the light guide plate 21 is fastened to the LED panel with a plurality of LED point light sources by a matrix.

18 is a simulation result of illuminance uniformity of a lighting apparatus according to the present invention. As shown, it can be seen that the illumination uniformity (Emin / Eave) of the lighting apparatus according to the present invention is 19.7 / 37 = 0.53. Generally, since the illumination uniformity required by the KSC is 0.15 or more in the case of the illumination lamp, it can be understood that the illumination to which the LED point light source light guide plate module 200 of the present invention is applied is excellent in diffusibility.

10: body 10c: radiating fin 10h: ventilation hole
10l: lamp inner part 10e: electric part inner part 10w: chin
20: LED panel
21: light guide plate 21p: first lens portion 21d: second lens portion
21g: Home
30: power supply 40: switch
50: cover 50w:
60: Fixing means
61: fixing plate 61g: engaging groove
62: adjusting plate 62d: engaging groove 62g: fixing groove
60b: Fixing bolt 60n: Fixing nut
70: clamp 70c: cover pressing portion
70g: Gap insertion projection 70h: Handle 70p: Pivot pin
80: Packing
90: Hinge means
91: lifting fixture 92: connecting pin 93: cover fixing plate

Claims (7)

A body 10 having a plurality of radiating fins 10c formed on a rear surface thereof, a lamp inner surface portion 10l formed at the center of the front surface thereof, and an electric component inner surface portion 10e formed at both ends thereof;
At least two LED panels (20) having a plurality of LED lamps and installed at lamp bulb portions at the center of the body;
A power supply (30) installed in the electric component part of the electrical component;
A switch (40) installed in the electrical component part of the electrical component;
A cover (50) detachably mounted on the front surface of the body and having a transparent light transmitting portion (501) formed at the center thereof corresponding to the lamp holding portion;
A fixing plate 61 which is provided on the back or side of the body and is fixed to the fixing vanes 11 formed on one side of the body and has a plurality of locking grooves 61g concentrically formed on the outer side thereof, And a fixing plate 62g having a fixing groove 62g for fixing and fixing the fixing object to the fixing plate 62. The fixing plate 62 and the fixing plate 62 are fixed to the fixing vanes Fixing means 60 made of a fixing nut 60n and a fixing bolt 60b for fixing the lighting device to another structure; And
And a clamp (70) rotatably installed on an outer surface of the body to fix the cover. The method according to claim 1,
A jaw 10w is further formed between the lamp inner and outer parts surrounding the electrical component part and between the lamp inner part and the electrical component inner part and a packing 80 is further provided at the end of the jaw. . 3. The method of claim 2,
The clamp 70 is formed with a handle 70 for rotating the clamp 70 in a state of being held by a hand at one end with a pivot pin 70p for rotatably fixing the outer wall of the body, The pressing portion 70c and the gap inserting portion 70g are formed so that the gap inserting protrusion 70g is inserted into the gap between the jaw and the outer circumferential surface of the body when the cover pressing portion 70c presses the cover 50, So that it can not be rotated without the force of the light. The method according to claim 1,
The cover has one end portion hingedly fixed to the body so as to be rotatable by the hinge means (90)
The hinge means 90 includes an elevating fixture 91 installed inside the body adjacent to the one side wall and vertically movably fixing the lower end of the connection pin 92,
A connection pin 92 having one end thereof vertically movably inserted into an elevating groove 91g formed on one side of the elevating fixture and pivotally connected to the cover at the other end; And a cover fixing plate (93) for rotatably coupling the other end of the connection pin to the cover. The method according to claim 1,
Both ends of the fixing means 60 are bent so as to be spaced apart from the body so that the cross-

Quot; shape. ≪ / RTI > delete The method according to claim 1,
A light guide plate (21) for diffusing light emitted from the LED is further provided on the front surface of the LED panel (20)
The light guide plate 21 includes a first lens portion 21p having a flat plate shape;
A second lens unit 21d formed in a matrix on the surface of the first lens unit, the second lens unit 21d having a semi-elliptical shape and an asymmetrical cross-section and whose peak is shifted to one side;
And a groove (21g) formed on the back surface of the second lens part (21d) and having an asymmetrical shape with a semi-elliptical cross section so that a peak of the peak is formed on the opposite side of the highest peak of the second lens part Instrument.

Images