CN100359365C - LED indicating pen o f gallium nitride base - Google Patents

Abstract

The present invention discloses an LED indicating pen with a gallium nitride base. The indicating pen comprises an LED with a gallium nitride base, a luminous surface of the LED with the gallium nitride base is provided with a narrow-band light filter layer which has high orientation selectivity and narrow band pass, and a lens is arranged in front of the light filter layer. The present invention has the advantages that the light generated from the LED pass through the light filter layer of the narrow band, so only approximate normal incidence light can transmit out. Meanwhile, the narrow band filter self can be only penetrated by the light with narrow wavelength range, so the finally generated light has good monochromaticity and is extremely close to laser. With the added lens, light beams have small faculae in use ranges, the light beams self are not coherent laser and have uniform brightness, so the light beams can not generate flash spots which make human eyes uncomfortable like laser pens. Therefore, the present invention can be used as a good indicating pen replacing the laser pens.

Description

LED indicating pen o f gallium nitride base

Technical field

The present invention relates to stylus, specifically be meant a kind of stylus that utilizes gallium nitride based light emitting diode as light emitting source.

Background technology

Along with the progress of science and technology and the development of society, many new high-tech products enter into daily life gradually, popularizing of computer and projector, make this marking tools small and exquisite, portable, fashion of laser pen replace traditional teacher's pointer more and more, have suitable application prospects at aspects such as multimedia shows.

But, because the complex structure of laser pen needs pump laser diode driver and laser diode module, in laser diode module, also needing materials such as KTP frequency-doubling crystal, cost is higher.Be subjected to the restriction of device technology and principle in addition, the color of laser pen is single, generally has only red in the market and green two kinds, and green laser pen price comparison costliness, can not satisfy the diversification and the personalized market demand.In addition, because the only coherent light that laser pen sent has a lot of shining points around the LASER SPECKLE when indication, human eye is caused very big discomfort.

And the GaN base semiconductor material has the special performance of emission blue light under high frequency, hot conditions, is the new generation of semiconductor material after Si and GaAs.By the GaN base semiconductor materials such as alloy InGaN, AlGaN that GaN, InN and AlN formed, can obtain continuously adjustable band gap from 1.9eV to 6.2eV by adjusting component, cover wave band from ultraviolet light to the visible light wide range.The inside and outside quantum efficiency height of these GaN base semiconductor materials, possess advantages such as high-luminous-efficiency, high heat conductance, high temperature resistant, radioresistance, acid and alkali-resistance, high strength and high rigidity, can be made into versicolor light emitting diodes such as blue, green, purple efficiently, white, become at present one of state-of-the-art light-emitting semiconducting material in the world.But it is big that the disadvantage of GaN based light-emitting diode is a diversity, and transmission range is short, if by straightforward procedure, adds some optical elements, can overcome the shortcoming of its existence, will be that great market outlook are arranged.

Summary of the invention

Purpose of the present invention is exactly to propose a kind ofly on the basis of GaN based light-emitting diode, by more additional optical elements, overcomes the LED indicating pen o f of its existing shortcoming.

GaN based light-emitting diode stylus of the present invention comprises: the GaN based light-emitting diode, be equipped with on the light-emitting area of GaN based light-emitting diode that directional selectivity is very high, the logical very narrow narrow-band-filter rete of band, and be equipped with condenser lens in the front of filter membranous layer.

The structure of said narrow-band-filter rete is:

α[(LH) _m1.6L(HL) _m]β[(HL) _n2.1H(LH) _n]，

Wherein L is a low-index film, and H is a high refractive index layer, and the optical thickness of L and H rete is λ ₀/ 4, λ ₀Be the logical peak position of band of described filter membranous layer, m and n are the alternative stacked number of times of L and H, m, n 〉=5, and α and β are the peak position factor, α=λ ₀/ λ _a, β=λ ₀/ λ _b, λ _aBe first rete (LH) _m1.6L (HL) _mThe logical peak position of band, λ _bBe second rete (HL) _n2.1H (LH) _nThe logical peak position of band.

Because the width of light source that the GaN based light-emitting diode sends is tens nanometers, above-mentioned narrow-band-filter rete is the very high narrow band pass filter of a kind of angular selectivity, this optical filter not only has enough narrow bandpass width under the normal incidence situation, but also can make the interior light transmission of very little ranges of incidence angles, making has only the light of near-normal incidence just can transmit, can improve the collimation of light that light emitting diode sends so greatly, simultaneously, narrow band pass filter itself can only see through the light of very narrow wavelength coverage, thereby make that the light monochromaticity of finally sending is fine, very approaching with laser.And then add lens, make light beam hot spot in the scope of using all very little, and light beam itself is not to be the laser that is concerned with, brightness is even, can not resemble and occur much allowing the shining point of human eye perceives discomfort the laser pen, therefore can substitute laser pen and use as good stylus.

Advantage of the present invention is:

1. simple in structure, compact, cost is low; Beam collimation and monochromaticity height; Brightness is even, and shades of colour is optional.

2. because the light that sends of light emitting diode is incoherent light, do not have the spot of sudden strain of a muscle, eliminated in the laser pen shining point the discomfort of human eye.

Description of drawings

Fig. 1 is the structural representation of GaN based light-emitting diode stylus of the present invention.

Transmission spectrum during narrow-band-filter rete normal incidence that Fig. 2 present embodiment is adopted.

The logical transmitance of the narrow-band-filter rete band that Fig. 3 present embodiment is adopted is with the change curve of incident angle.

Embodiment

Below in conjunction with accompanying drawing, with central wavelength lambda ₀For the green light LED of 550nm is an example, the specific embodiment of the present invention is elaborated.GaN based light-emitting diode 1 of the present invention is by grow successively on jewel or silicon carbide substrates 101 by molecular beam epitaxy or metal-organic chemical vapor deposition equipment method n-GaN lower electrode layer 102, In _xGa _1-xThe luminescent layer 103 of N/GaN quantum well structure and p-GaN upper electrode layer 104 constitutes, and can obtain the light emitting diode of different-waveband by the component x value of regulating In, and the x numerical value of present embodiment is 0.2.

Method by vacuum coating generates narrow-band-filter rete 2 on upper electrode layer 104 then, and the structure of filter membranous layer is:

α[(LH) ₁₂1.6L(HL) ₁₂]β[(HL) ₁₂2.1H(LH) ₁₂]，

Wherein L is low-refraction SiO ₂Rete, H are high index of refraction Ta ₂O ₅Rete, the optical thickness of L and H rete is λ ₀/ 4, λ ₀Be the logical peak position 550nm of band of optical filter, the alternative stacked number of times of L and H is 12 times, and α and β are the peak position factor, α=λ ₀/ λ _a, β=λ ₀/ λ _b, λ _aBe first rete (LH) ₁₂1.6L (HL) ₁₂The logical peak position of band, λ _bBe second rete (HL) ₁₂2.1H (LH) ₁₂The logical peak position of band.λ _aAnd λ _bNumerical value by its rete (LH) separately _m1.6L (HL) _m(HL) _n2.1H (LH) _nCalculating, specifically is these parameters to be input in the business softwares such as Filmstar, calculates the curve of spectrum of this rete, and the peak position on the curve is exactly λ _aAnd λ _bNumerical value.The transmission spectrum of this filter membranous layer as shown in Figure 2, the logical half-peak breadth of the band at 550nm place is very narrow, has only 0.003nm, therefore the light monochromaticity that transmits is fine, and is very approaching with laser.And the directional selectivity of this narrow band pass filter is also very high, the logical transmitance of its band with the change curve of incident angle as shown in Figure 3, from the figure as can be seen, as long as incident angle departs from the normal incidence direction a little, transmitance just sharply descends, and when incident angle was 2 °, transmitance had just dropped to 14%; When incident angle increased to 3 °, transmitance just had only 2.8%, and the light of bigger incident angle all can not pass optical filter and transmit, and therefore added that the light direction that transmits behind the above-mentioned narrow band pass filter is also fine.

On the light emitting diode for preparing, install lens 3 then, the focal length of general lens is 2.5 meters and can have satisfied request for utilization.At last, the difference extraction electrode adds power supply (dry cell or button cell) and switch on the upper and lower electrode layer of diode, promptly finishes the preparation of whole GaN based light-emitting diode stylus.

Claims (2)

1. LED indicating pen o f gallium nitride base, comprising: GaN based light-emitting diode (1) is characterized in that:

On the light-emitting area of GaN based light-emitting diode, be equipped with narrow-band-filter rete (2), be equipped with condenser lens (3) in the front of filter membranous layer by vacuum coating.

2. according to a kind of LED indicating pen o f gallium nitride base of claim 1, it is characterized in that: the structure of said narrow-band-filter rete is:

α[(LH) _m1.6L(HL) _m]β[(HL) _n2.1H(LH) _n]，

Wherein L is a low-index film, and H is a high refractive index layer, and the optical thickness of L and H rete is λ ₀/ 4, λ ₀Be the logical peak position of band of described filter membranous layer, m and n are the alternative stacked number of times of L and H, m, n 〉=5, and α and β are the peak position factor, α=λ ₀/ λ _a, β=λ ₀/ λ _b, λ _aBe first rete (LH) _m1.6L (HL) _mThe logical peak position of band, λ _bBe second rete (HL) _n2.1H (LH) _nThe logical peak position of band.

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