JP2003347581A - Led array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED array which ensures high quality printing by preventing stray light. <P>SOLUTION: There is provided an LED array wherein one conductivity type semiconductor layer 2, an inverse conductivity type semiconductor layer 3 and an individual electrode 4 are sequentially laminated on a single crystal substrate 1, a plurality of light emitting elements including a common electrode 5 and an insulation film 6 provided in parallel is allocated in a plurality of lines on an extending area 7 where this one conductivity type semiconductor layer 2 is extended, and a group 9 of light emitting elements allocating an electrode pad 8 formed in common to each individual electrode 4 of these light emitting elements is allocated in a plurality of lines. In this LED array, the other electrode pad 10 formed in common to both common electrodes 5 is also allocated by providing different electrode interval x to the common electrode 5 in the extending area 7 of each light emitting element in the group of the light emitting elements 9 and providing the equal electrode interval x to the light emitting elements of one group of light emitting elements 9 and to the light emitting elements of the other group of light emitting elements 9. Only a part of the light emitting region A is covered with the insulation film 6 and moreover the area other than the light emitting region A is covered with a protection film 12. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED array, and more particularly, to an LED array used as an exposure light source for a photosensitive drum for a page printer.

[0002]

2. Description of the Related Art The basic structure of an LED array is to arrange a plurality of light emitting elements in which a semiconductor layer of one conductivity type, a semiconductor layer of a reverse conductivity type and an electrode are sequentially laminated, and The light-emitting region of the semiconductor layer is covered with a light-transmitting electrical insulating film such as SiNx, and the portion other than the light-emitting region of the opposite conductivity type semiconductor layer is further covered with a light-transmitting transparent synthetic resin layer. are doing.

A specific example of an LED array having such a basic configuration will be described. A conventional LED array is illustrated by FIGS. FIG. 6 is a plan view of the LED array, and FIG. 7 is a sectional view thereof.

[0004] Reference numeral 21 denotes a single crystal substrate.
In the above, 22 is a semiconductor layer of one conductivity type, 23 is a semiconductor layer of the opposite conductivity type, 24 is an individual electrode, 25 is a common electrode, and 26 is an insulating film as a protective film made of a silicon nitride film or the like.

A single conductivity type semiconductor layer 22 and a reverse conductivity type semiconductor layer 23 are sequentially formed on a single crystal substrate 21 for each light emitting element. In the stack, the area of the one conductivity type semiconductor layer 22 is reduced. The area is larger than the area of the opposite conductivity type semiconductor layer 23.

An insulating film 26 is coated on the one conductivity type semiconductor layer 22, and the exposed portion thereof has a common electrode 25 (25a, 25a).
25b).

[0007] Also, for the opposite conductivity type semiconductor layer 23,
The insulating film 26 is coated thereon, and the individual electrodes 24 are connected to the exposed portions.

[0008] Further, as shown in FIG.
(25a, 25b) are set to 2 so that they belong to different groups for each adjacent light emitting element (for each island-like semiconductor layer 22, 23).
Adjacent light emitting elements (island-shaped semiconductor layers 22 and 23) are connected to the same individual electrode 24.

In this light emitting diode array structure, each light emitting element can selectively emit light by selecting a combination of the individual electrode 24 and the common electrode 25 (25a, 25b) and flowing a current.

[0010]

In recent years, there has been a need in the market for light-emitting elements of high density and miniaturization of the LED array.
In the array, it has been difficult to further reduce the number of electrode pads, which are external connection points, to further reduce the size of connection electrodes to external circuits, and to further reduce the chip size.

[0011] Therefore, the density of the light emitting element is increased,
It has not been possible to sufficiently meet the needs of the market for miniaturization of D arrays.

In order to solve this problem, an LE of a multilayer electrode structure provided with a matrix wiring electrode via an interlayer insulating film is provided.
A D array has been proposed (see JP-A-9-277592 and JP-A-11-40842).

[0013] However, in the LED array of this proposal as well, the formation of individual electrodes of each light emitting diode, the formation of matrix wiring for dividing the light emitting diodes into groups, and selecting one from each group one by one without duplication are performed twice. In addition, by performing the steps of electrically separating each of the electrodes through an insulating film or the like, the manufacturing process becomes complicated due to the multilayer electrode structure, thereby lowering the manufacturing yield and increasing the manufacturing cost. There is.

In order to solve such a problem, the present inventor has proposed a technique for simplifying the process by forming a matrix wiring once in the LED array disclosed in Japanese Patent Application Laid-Open No. 2000-76437.

According to the publication, an electrode pad common to one electrode of each light emitting element is provided for each light emitting element group, and an extending portion of each light emitting element in the light emitting element group is provided. In addition, the distance between the electrodes reaching the other electrode is different, and the distance between the electrodes of the light emitting element of one light emitting element group and the distance between the electrodes of the light emitting elements of the other light emitting element group are the same, and the other electrode is formed in common to both other electrodes. Electrode pads are provided.

By arranging an electrode pad commonly formed on a plurality of one electrodes and further arranging another electrode pad formed commonly on a plurality of other electrodes, the number of electrode pads is reduced. As a result, the arrangement area is reduced, thereby achieving a higher density of light emitting elements and a smaller LED array.

According to the LED array having the above structure,
JP-A-9-277592 and JP-A-11-4084
No. 2 Publication with LED having a multilayer electrode structure
Compared with the array, the number of processes is reduced, the manufacturing cost is reduced by not using a multilayer electrode structure with an interlayer insulating film interposed therebetween, and the LE has achieved higher density and smaller size of the light emitting element.
A D array was obtained.

However, Japanese Patent Application Laid-Open No. 2000-76437
According to the LED array disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, the insulating film disposed on the opposite conductivity type semiconductor of each light emitting element and the insulating film disposed other than this are made of the same material when coating the insulating film thereon. Therefore, by forming them at the same time, both light transmission characteristics become the same, so that the light emitted from the upper part of the opposite conductivity type semiconductor is reflected as stray light to the adjacent light emitter, and as a result, the LED array The MTF was lowered, the printing quality was lowered, and the quality of the LED head could not be stabilized.

According to each LED head described above,
The light emitting region of the opposite conductivity type semiconductor layer is covered with a light-transmitting electrical insulating film such as SiNx, and the other portion of the opposite conductivity type semiconductor layer other than the light emitting region is a light transmitting transparent synthetic resin layer. In this case, there is a problem that stray light is generated inside the light-transmitting transparent synthetic resin layer, thereby reducing the quality and reliability of light emission.

An object of the present invention has been completed in view of the above, and an object of the present invention is to provide an LED array in which such stray light is reduced or eliminated.

Another object of the present invention is to reduce the manufacturing cost and increase the density and miniaturization of the light emitting element without increasing the number of steps and without using a multilayer electrode structure with an interlayer insulating film interposed therebetween. To provide an improved LED array.

Still another object of the present invention is to prevent the occurrence of an electrical short-circuit failure in the wire bonding which is an external connection process of the LED array, to achieve a further reduction in cost due to further miniaturization, and to improve the MTF of the LED array. Another object of the present invention is to provide an LED array with improved printing quality.

[0023]

An LED array according to the present invention comprises a plurality of light-emitting elements each having at least one conductive semiconductor layer, an opposite conductive semiconductor layer, and an electrode laminated in order, and A part of the light emitting region of the opposite conductivity type semiconductor layer is covered with a light-transmitting electrical insulating film, and a part other than the light emission region of the opposite conductivity type semiconductor layer is further covered with a light-shielding synthetic resin layer. It is characterized by.

According to another LED array of the present invention, a semiconductor layer of one conductivity type, a semiconductor layer of opposite conductivity type and one electrode are sequentially laminated on a single crystal substrate, and an extended portion from which the semiconductor layer of one conductivity type is extended is formed. A plurality of light emitting elements each having an array of the other electrode and an insulating film arranged thereon, and a plurality of light emitting element groups each having an electrode pad formed in common with one electrode of each of the light emitting elements are arranged. The distance between the electrodes of the light-emitting elements in one light-emitting element group and the light-emission of the other light-emitting element group are different from each other. The electrode spacing of the element is the same, another electrode pad common to both the other electrodes is provided, and at least a portion other than the one electrode in the light emitting region of the opposite conductivity type semiconductor layer is lighted. Transparent electrical inorganic insulation It was coated with further characterized by comprising coating the light-shielding synthetic resin layer portions other than the light emitting region of the opposite conductivity type semiconductor layer.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the basic structure of an LED array according to the present invention is to cover at least a part of a light emitting region of a semiconductor layer of the opposite conductivity type with a light-transmitting electrical insulating film,
Further, a portion other than the light emitting region of the opposite conductivity type semiconductor layer is covered with a light-shielding synthetic resin layer, and the present invention is an LED array having such a configuration. This will be described in detail with reference to the drawings.

FIGS. 1 to 5 show an embodiment of the LED array of the present invention. 1 is an enlarged plan view of a main part of the LED array, FIG. 2 is a sectional view taken along line VV ′ shown in FIG. 1, FIG. 3 is a sectional view taken along line hh ′ shown in FIG. 1, and FIG. It is a top view of each light emitting element. FIGS. 2 and 3 show the directions of the cross-sectional views by clearly indicating V, V ′, h, and h ′ as reference numerals. FIG. 5 is a plan view of a main part of another LED array.

Reference numeral 1 denotes a single crystal substrate.
In the above, 2 is a semiconductor layer of one conductivity type, 3 is a semiconductor layer of the opposite conductivity type, 4 is an individual electrode as the one electrode, 5 is a common electrode as the other electrode, and 6 and 12 are protections made of an organic resin film or the like. An insulating film as a film.

Reference numerals 8 and 10 (10a, 10b) denote electrode pads for external connection.

On the single crystal substrate 1, a semiconductor layer 2 of one conductivity type and a semiconductor layer 3 of opposite conductivity type are sequentially formed for each light emitting element. In the stack, the area of the semiconductor layer 2 of one conductivity type is By extending the one-conductivity-type semiconductor layer 2 so as to be larger than the area of the opposite-conductivity-type semiconductor layer 3, the extension part 7 made of the same material as the one-conductivity-type semiconductor layer 2 is provided.

As shown in FIG. 2, an organic material such as a polyimide synthetic resin or a silicon nitride (S
Although the insulating film 6 made of an inorganic material such as iNx) or silicon oxide (SiO2) is covered, the common electrode 5 (5a, 5b) is connected to the exposed portion to provide the insulating film 6 and the common electrode. 5 are arranged side by side on the extending portion 7.

Further, a part of the light emitting region A of the opposite conductivity type semiconductor layer 3 is covered with the insulating film 6 and the exposed portion thereof is covered with the individual electrode 4.
Are connected. The protective film 12, which is the light-shielding synthetic resin layer, covers the opposite conductivity type semiconductor layer 3 and the electrode pads 8 and 10 for external connection in a partially exposed manner.

The protective film 12 is formed by covering a portion other than the light emitting region A of the semiconductor layer 3 of the opposite conductivity type.

Next, each member will be described in detail. The single crystal substrate 1 is made of a semiconductor substrate, and when it is made of a high-resistance silicon single crystal, the (100) plane is placed in the <011> direction by
A substrate or the like turned off by 7 ° is preferable.

The one conductivity type semiconductor layer 2 includes a buffer layer 2a,
It comprises an ohmic contact layer 2b and an electron injection layer 2c.

Buffer layer 2a and ohmic contact layer
2b is formed of gallium arsenide or the like, and has an electron injection layer 2c.
Is formed of aluminum gallium arsenide or the like. Ohmi
One contact type semiconductor such as silicon
1 × 10 body impurities¹⁷-10 ¹⁹atoms (atoms) / c
m^Three To the electron injection layer 2c.
Contains conductive semiconductor impurities to some extent.

The buffer layer 2a is provided to prevent misfit dislocation due to mismatch of the lattice constant between the single crystal substrate 1 and the semiconductor layer.
¹⁶ to 10 ¹⁹ atoms / cm ^{3 are} contained.

The buffer layer 2a is formed to a thickness of about 2 to 4 μm, and the ohmic contact layer 2b is formed to a thickness of 0.1 to 3.
The electron injection layer 2c is formed to a thickness of about 0 μm.
It is formed to a thickness of about 0.4 μm.

The opposite conductivity type semiconductor layer 3 includes a light emitting layer 3a, a cladding layer 3b, and another ohmic contact layer 3c.

The light emitting layer 3a and the cladding layer 3b are made of aluminum gallium arsenide, and the ohmic contact layer 3c is made of gallium arsenide.

The light emitting layer 3a, the cladding layer 3b, and the ohmic contact layer 3c are provided between the respective layers in consideration of the electron confinement effect and the light extraction effect, by mixing aluminum arsenide (AlAs) and gallium arsenide (GaAs). Different crystal ratios.

The light emitting layer 3a and the cladding layer 3b are made of zinc (Z
n) or the like and 1 × 10 ¹⁶ to 10 ²¹
atoms / cm ³ , and the ohmic contact layer 3c contains 1 × 10 ^{19 of} a reverse conductivity type semiconductor impurity such as zinc.
About 10 ²¹ atoms / cm ³ .

The light emitting layer 3a and the cladding layer 3b have a thickness of 0.2 to
The thickness d of the ohmic contact layer 3c is about 0.4 μm, and the thickness d> (0.15 μm
-Ohmic contact layer thickness).

The insulating film 6 is made of, for example, silicon nitride and has a thickness of about 2000.degree.

The individual electrodes 4 and the common electrodes 5 (5a, 5b, 5
c, 5d) are made of gold / chrome (Au / Cr) or the like,
It is formed to a thickness of about 1 μm.

Each light emitting element has the above-described configuration. Next, FIGS. 1 and 3 show the electrode structure for each light emitting element.

An electrode pad 8 is provided in common to the individual electrodes 4 of these light emitting elements, a light emitting element group 9 corresponding to each electrode pad 8 is provided, and the one light emitting element group and the other light emitting element group are provided. By alternately arranging the light emitting element groups, a plurality of light emitting element groups 9 are arranged in a line.

The common electrode 5 (5a, 5b, 5c, 5c) in the extension 7 of each light emitting element in the light emitting element group 9
The electrode spacing x leading to d) is different, and the electrode spacing of the light emitting elements of one light emitting element group 9 is the same as the electrode spacing of the light emitting elements of the other light emitting element group 9, so that both electrodes are common. Another electrode pad 10 is provided.

Then, in order to energize the common electrode 5 of each light emitting element with the same electrode spacing x, the connection lines 11 (11a, 11a, 11a, 11
b, 11c, 11d) are formed in parallel with the arrangement lines of the light emitting elements.

Further, with respect to one of the light emitting element groups and the adjacent light emitting element groups 9 as the other light emitting element group, the distance x between the individual electrodes in the light emitting element group 9 is increased or shortened in the arrangement order. In this case, a symmetrical electrode spacing pattern is obtained.

Next, FIG. 5 shows a 128-bit (bit) LED array with four different electrode intervals x.

The electrode having the shortest electrode interval x is defined as X11, and this is defined as the light emitting element at the end.
31, X41,..., X4n, X3n, X2n, X1n,.

The 128 bits are divided into four groups of 32 groups (3
By dividing into two light emitting element groups 9), n = 1 to 32.

Each of the light emitting element groups 9 is divided into groups G1, G2,.
Assuming that Gm is Gm, the light emitting elements having the electrode spacing X11 in the group G1 and the light emitting elements having the electrode spacing X12 in the group G2 are connected by the connection line 11a.
m is connected to the light emitting element at the electrode interval X1n.

The light emitting elements having the electrode spacing X21 in the group G1, the light emitting elements having the electrode spacing X22 in the group G2, and the light emitting elements having the electrode spacing X2n in the group Gm are connected by the connection line 11b.

Similarly, the electrode interval X in the group G1
31 light emitting elements and the electrode spacing X3 in the group G2.
2 light-emitting elements and the electrode spacing X3 in the group Gm
The n light-emitting elements are connected by a connection line 11c.

The light emitting elements having the electrode spacing X41 in the group G1, the light emitting elements having the electrode spacing X42 in the group G2, and the light emitting elements having the electrode spacing X4n in the group Gm are connected by a connection line 11d.

Then, a current is caused to flow through a predetermined light emitting element by selectively applying a voltage between the electrode pads 8 provided in each light emitting element group and the other group of electrode pads 10. And cause the device to emit light.

Thus, according to the LED array of the present invention,
A common electrode pad 8 is provided for each light emitting element group 9 (groups G1, G2,... Gm...), And each light emission in the light emitting element group 9 (groups G1, G2,. The electrode spacing x of the light emitting elements of one light emitting element group and the electrode spacing x of the light emitting elements of the other light emitting element group are made the same while the electrode spacing x of the element is different.
By arranging the common electrode pad 10 for
The number of electrode pads is reduced, and the area for arranging the electrodes is reduced.
Array miniaturization is achieved.

In the present invention, at the same time that the protective film 12 is formed on the surface, at least a part of the electrode pads 8 and 12 for connection to an external circuit and a part of the light emitting region A of the opposite conductivity type semiconductor layer 3 are formed. It is covered with an insulating film 6, and an individual electrode 4 is connected to an exposed portion thereof.

The thickness d of the insulating film 6 is preferably set so as to prevent reflection.

The conditions for this may be as follows.

N1: the refractive index of the insulating film 6, d: the thickness of the insulating film 6, m: an integer, λ: the emission wavelength of the light emitting element, N2: the one conductivity type semiconductor layer 2 and the opposite conductivity type semiconductor layer 3 With respect to the refractive index of the GaAs material, the condition for antireflection is (N1) d = (1/4 + m /
2) It is better to set λ and (N1) = √ (N2).

For the protective film 12, a dye may be contained in a synthetic resin material such as polyimide to make it light-shielding, and a black pigment may be contained as such a dye. For example, molybdenum disulfide, Graphite, carbon blacks such as acetylene black, Ketjen black, furnace black, magnetite cobalt oxide, metal oxides such as copper oxide and chromium oxide, and composite metal oxides such as copper oxide-chromium oxide-iron oxide,
There is a titanium black and the like.

The insulating film 6 and the protective film 12 are covered to design an optimal optical transmittance according to the wavelength of the LED array. By designing the optical transmittance to be the lowest, stray light can be reduced, and as a result, an LED array with an improved MTF can be realized.

For example, when the insulating film 6 is formed of a SiNx film and the protective film 12 is formed of an organic resin film and the wavelength of the LED is 740 nm, the optimum transmittance is 100%. On the other hand, the thickness and the refractive index of the insulating film 6 are designed so that the light transmittance is close to 100%. For example, the thickness of the insulating film 6 made of SiNx (refractive index = 1.88) may be set to about 3100A.

According to the LED array of this embodiment, an electrode pad common to one electrode of each of the light emitting elements is provided for each of the light emitting element groups as described above. The electrode spacing to the other electrode in the extending portion of each light emitting element in the group is different, and the electrode spacing of the light emitting element of one light emitting element group is the same as the electrode spacing of the light emitting element of the other light emitting element group, Another electrode pad common to both other electrodes is provided.

As described above, by disposing the electrode pad commonly formed for a plurality of one electrodes and disposing another electrode pad commonly formed for a plurality of other electrodes, the number of electrode pads is reduced. As a result, the arrangement area of the LED array is reduced, and thereby, the density of the light emitting elements is increased and the size of the LED array is reduced.

Further, Japanese Patent Application Laid-Open No. 9-277592 and Japanese Patent Application Laid-Open
The number of processes is smaller than that of the LED array having a multilayer electrode structure as proposed in JP 11-40842,
By not using a multilayer electrode structure with an interlayer insulating film interposed therebetween, manufacturing costs can be reduced, and an LED array in which a light-emitting element has a higher density and a smaller size can be obtained. Further, in order to energize the other electrode of each light emitting element with the same electrode spacing, so as to straddle the insulating film formed on the extending portion of the one conductivity type semiconductor layer,
The connection lines are formed in parallel with the arrangement lines of the light emitting elements.
Therefore, in the conventional LED array, an interlayer insulating film indispensable for electrical insulation between wirings is not formed other than the insulating film formed as is well known, thereby lowering the manufacturing cost and lowering the cost. LED array is provided. Further, for one light emitting element group and the other light emitting element group, by changing the arrangement of the individual electrodes in the light emitting element group in the arrangement order, a symmetrical electrode spacing pattern is obtained, and such a regular pattern is formed. By doing, LED
Signal processing of the light emission order when the head is mounted is relatively easy,
As a result, the design of the mounting substrate can be facilitated. Then, by providing the regular pattern on the LED array in an orderly manner, it becomes easy to design the electrode pads in other areas. A large space can be taken at the shortest part of the symmetric electrode interval. Thereby, LE
It is possible to reduce the size of the D array chip and to increase the size of the wire bonding pad when mounting the LED array. As a result, the chip size of the LED array can be reduced, and the yield in manufacturing the LED head can be improved. In addition, the above-mentioned LED array has a structure in which the resin film is formed on the surface and at the same time covers at least the portion other than the electrode connection portion with the external circuit and the upper portion of the reverse conductivity type semiconductor layer. In addition to designing the optical transmittance to be optimal,
By designing the optical transmittance to be the lowest with respect to the wavelength of the ED array, stray light is reduced and the MTF is improved.
An ED array was realized. Further, when the resin film is an opaque film containing a dye, further improvement can be achieved, and an LED head with improved MTF and high printing quality can be provided.

Next, a method for manufacturing the above-described LED array will be described.

First, on a high resistance silicon single crystal substrate 1,
MOCVD of one conductivity type semiconductor layer 2 and reverse conductivity type semiconductor layer 3
It is formed by sequentially laminating by a method or the like.

First, when these semiconductor layers 2 and 3 are formed, the substrate temperature is set to 400 to 500 ° C., whereby an amorphous gallium arsenide film having a thickness of 200 to 2000 ° is formed. From 700 to 9
One-conductivity-type semiconductor layer 2 having a desired thickness raised to 00 ° C.
And the opposite conductivity type semiconductor layer 3 are formed.

In this film formation, the source gas is TM
G ((CH_Three )_Three Ga), TEG ((C_Two H_Five )_Three G
a), arsine (AsH)_Three ), TMA ((CH_Three )_Three A
l), TEA ((C_Two H_Five )_Three Al) is used,
As the gas for controlling the conductivity type, silane (SiH
_Four ), Hydrogen selenide (H_Two Se), DMZ ((CH_Three )
_Two Zn) or the like, and H 2 is used as a carrier gas._Two
Are used.

Next, semiconductor layers 2 and 3 are patterned in an island shape so that adjacent elements are electrically separated from each other. For this purpose, wet etching using a sulfuric acid-hydrogen peroxide-based etchant or CCl ₂ F ₂
This is performed by dry etching using gas or the like.

Thereafter, an extension 7 is provided on one end side of the one conductivity type semiconductor layer 2, a part of the extension 7 is exposed on the extension 7, and is adjacent to the one conductivity type semiconductor layer 2. Etching is performed so that a region portion is exposed. The opposite conductivity type semiconductor layer 3 is etched so that the opposite conductivity type semiconductor layer 3 is formed narrower than the one conductivity type semiconductor layer 2.

Such etching is also performed by wet etching using a sulfuric acid / hydrogen peroxide-based etching solution or CCl 2
This is performed by dry etching using F2 gas.

Next, etching is performed using, for example, an alkaline aqueous solution so that adjacent light emitting elements are electrically separated from each other even on the substrate. At this time, a part of the extension portion 7 of the one conductivity type semiconductor layer 2 is exposed, and a region adjacent to the one conductivity type semiconductor layer 2 is exposed. This is performed while leaving the pattern used when etching the opposite conductivity type semiconductor layer 3 so as to be formed narrower than the conductivity type semiconductor layer 2, thereby electrically connecting the opposite conductivity type semiconductor layer 3 without any damage. To separate.

Next, an insulating film 6 formed by spin coating an organic resin is formed. The insulating film is formed by a plasma CVD method using silane gas (SiH ₄ ) and ammonia gas (NH).
_A material made of silicon nitride by using ₃ ) may be used.

The electrode pads 9 and 10 and the connection lines 11 are formed by forming and patterning chromium and gold by a vapor deposition method or a sputtering method. Finally, a protective film 12 formed by spin coating an organic resin is formed.

[0079]

As described above, according to the LED array of the present invention, at least a part of the light-emitting region of the opposite conductivity type semiconductor layer is covered with the light-transmitting electrical insulating film. By covering portions other than the light-emitting region with a light-shielding synthetic resin layer, stray light was reduced or eliminated, thereby obtaining a high-quality and highly reliable LED array with improved MTF.

In the LED array of the present invention,
A semiconductor layer of one conductivity type, a semiconductor layer of the opposite conductivity type, and one electrode are sequentially laminated on a single crystal substrate, and the other electrode and an insulating film are juxtaposed on an extending portion from which the semiconductor layer of one conductivity type is extended. A plurality of light-emitting elements comprising a plurality of light-emitting elements, and further, a plurality of light-emitting elements formed by arranging a common electrode pad for each one electrode of these light-emitting elements, further arranged in a line-like, The distance between the electrodes extending to the other electrode in the extending portion of each light emitting element in the light emitting element group is different, and the electrode distance between the light emitting elements in one light emitting element group and the electrode distance between the light emitting elements in the other light emitting element group are the same. Therefore, by arranging another electrode pad commonly formed for both of the other electrodes, the number of electrode pads is reduced, and the arranging area is reduced, thereby increasing the density of the light emitting element. And LED
Array miniaturization has been achieved.

Further, the number of steps is smaller than that of a conventional LED array having a multilayer electrode structure, and the manufacturing cost is reduced by not using a multilayer electrode structure with an interlayer insulating film interposed therebetween.
An LED array in which the density and the size of the light-emitting element were achieved was obtained.

Further, since the above-mentioned LED array has a structure in which the resin film is formed on the surface and at least the portion other than the electrode connection portion with the external circuit and the upper portion of the reverse conductive type semiconductor layer is covered, the insulating film is formed on the LED array. The optical transmittance was designed to be optimal according to the wavelength, and the resin film was designed to have the lowest optical transmittance with respect to the wavelength of the LED array, thereby reducing stray light and improving the MTF. The LED array was realized. Further, when the resin film was an opaque film containing a dye, further improvement was achieved, and an LED head having high MTF and high printing quality could be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of an LED array of the present invention.

FIG. 2 is a sectional view taken along line VV ′ shown in FIG.

FIG. 3 is a sectional view taken along the line h-h 'shown in FIG.

FIG. 4 is a plan view showing an embodiment of the LED array of the present invention.

FIG. 5 is a plan view showing one embodiment of a conventional LED array.

FIG. 6 is a sectional view showing a conventional LED array.

FIG. 7 is a plan view showing one embodiment of a conventional LED array.

[Explanation of symbols]

1 ... single crystal substrate 2 ... One conductivity type semiconductor layer 3 ... Reverse conductivity type semiconductor layer 4 ・ ・ ・ Individual electrode 5 Common electrode 6 ... Insulating film 7 ... Extended part 8 ... Electrode pad 9 ... Light-emitting element group 10 ... Electrode pad 11 Connection line x: Electrode spacing A: Light emitting area

Claims (2)

[Claims] An LED array in which a plurality of light emitting elements each having at least one semiconductor layer of a first conductivity type, a semiconductor layer of a reverse conductivity type, and an electrode sequentially laminated are arranged, and at least a light emitting region of the semiconductor layer of the opposite conductivity type is provided. Characterized in that a part of the LED array is covered with a light-transmitting electrical insulating film, and a part other than the light-emitting region of the opposite conductive semiconductor layer is covered with a light-blocking synthetic resin layer. 2. The semiconductor device according to claim 1, further comprising: a first conductive type semiconductor layer, a reverse conductive type semiconductor layer, and one electrode sequentially laminated on a single crystal substrate; A plurality of light emitting elements arranged side by side are arranged, and a plurality of light emitting element groups formed by arranging an electrode pad commonly formed for each one electrode of these light emitting elements are arranged in a line, Further, the electrode spacing to the other electrode in the extending portion of each light emitting element in the light emitting element group is different, and the electrode spacing of the light emitting element of one light emitting element group is the same as the electrode spacing of the light emitting element of the other light emitting element group. An LED array in which another electrode pad commonly formed for both of the other electrodes is provided, wherein at least a part of the light emitting region of the opposite conductivity type semiconductor layer is formed on a light transmitting electrically insulating film. Covered and then the reverse conductivity type semiconductor LED array characterized by being coated with light-shielding synthetic resin layer portions other than the light emitting region of the.