JPH07251525A - Light emitting element array device - Google Patents

Abstract

PURPOSE:To provide a light emitting element array device reducing the effect caused by the scattered light in the light emitted from a light emitting element by simple constitution and capable of always well irradiating an object with light. CONSTITUTION:The incidence quantity of the light, which is emitted toward an area other than the surface of a substrate 3 from the light emitting part 14 of an LED chip 4 to become scattered light, to the surface of the substrate 3 is absorbed by a light absorbing layer 29 to be reduced to a large extent to accurately irradiate an object with light in uniform quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting element array device used as various light sources, and more particularly to a light emitting element array device capable of reducing the influence of scattered light and performing good light irradiation.

[0002]

2. Description of the Related Art Conventionally, a light emitting element array device having a structure in which a plurality of light emitting elements such as LEDs are arranged in an array has been proposed.

FIG. 3 shows an example of a light emitting element array device of this type, which is a constituent element of an optical writing head for optically writing on a photosensitive member in an electrophotographic apparatus.

In this light emitting element array device 1, an electrode pattern (not shown) is formed on a substrate 3 made of glass or the like in which the optical fiber bundle 2 is embedded, and a substrate 3 on which this electrode pattern is formed serves as a light emitting element. The LED chips 4, 4 and the driving IC chips 5, 5 for driving the LED chips 4, 4 are arranged in an array, respectively, and the LED chips 4, the driving IC chips 5 and the electrode patterns are soldered respectively. It is formed by connecting.

FIG. 4 shows a light emitting element array device 1 shown in FIG.
FIG. 5 is a cross-sectional view showing the main part of FIG. 5, and FIG. 5 is a top view showing the shape of the electrode pattern.

As shown in FIG. 4, an undercoat layer 6 made of SiO ₂ is formed by sputtering or the like on the upper surface of the substrate 3 in which the optical fiber bundle 2 is embedded, and the LED is formed on the undercoat layer 6. Electrode patterns 7 for transmitting signals to the chip 4 and the driving IC chip 5 are formed.

The electrode pattern 7 is further composed of a plurality of layers, and the undercoat layer 6 is formed in order from the substrate 3 side.
The Cr layer 8 for increasing the adhesion strength with the Cu layer 9, the Cu layer 9 serving as the main conductor layer, the Ni layer 10, and the Au layer 11 for improving the solderability are laminated.

The solder bumps 1 provided on the LED chip 4 or the driving IC chip 5 are provided on the electrode pattern 7.
A solder dam layer 13 made of a transparent photosensitive polyimide is further laminated so as to prevent a solder flow when connecting the Nos. 2 and 12 and the Au layer 11 forming the electrode pattern 7, and the solder dam layer 13 is formed at the time of soldering. Solder bump 12 by layer 13
The LED chip 4 is automatically positioned with respect to the substrate 3 by positioning.

The side portion of the LED chip 4 and the substrate 3
Between the LED chip 4 and the substrate 3 caused by thermal expansion, and between the solder bumps 12 and the LED chip 4 or the substrate 3 are alleviated, and the LED chip 4 emits light. In order to suppress diffusion of light emitted from the portion 14 toward the substrate 3, a transparent resin 15 having a refractive index higher than that of air is filled.

As shown in FIG. 5, the electrode pattern 7 includes a common electrode 16 and an individual electrode 1 facing the common electrode 16.
7 and 7.

Each individual electrode 17 has a lead portion 18 for connecting to the solder bump 12 of the LED chip 4 described above at the tip of the lead portion 18, that is, the end portion on the side facing the common electrode 16. The solder lands 19 having a large area are formed, and the solder lands 18, 18 of the individual electrodes 17 adjacent to each other are arranged in a zigzag pattern.

In the light-emitting element array device 1 thus configured, the signal from the driving IC 5 is supplied to the LED chip 4 through the specific electrode pattern 7 based on the control signal, so that the LED chip 4 is identified. 11 emits light, and the light from this light emitting portion passes through the transparent resin 15 from one surface of the substrate 3 to the optical fiber bundle 2 embedded in the substrate 3 as shown by an arrow A in FIG. Upon incidence, it is guided to the outside from the other surface and is used for optical writing.

[0013]

However, in such a light emitting element array device, of the light generated in the light emitting section 14 of the LED chip 4, the light emitted in the direction other than the substrate 3 becomes scattered light. There is a problem that a part of the light is incident on the surface of the substrate 3 and the light cannot be extracted well.

That is, in the LED chip 4, light is generated at the PN junction surface 20 as shown in FIG. 4, and the generated light is radiated isotropically from here. Therefore, a part of the generated light is also radiated in the directions shown by arrows B and C in the figure, and is emitted from the cut surfaces 4a and 4b of the LED chip 4 to the outside of the chip.

The light emitted to the outside of the chip enters the transparent resin 15 as it is and proceeds further.
Since the refractive index of 5 is larger than that of air, part of it is reflected at the interface between the transparent resin 15 and air to become scattered light,
A part of this scattered light goes toward the substrate 3 through the solder dam layer 13 made of transparent polyimide as shown by an arrow D or E in the figure.

Of the scattered light, the light indicated by arrow E in the figure, that is, the light directed to the common electrode 16 side, has a substrate surface in a region where the light reaches, as shown in FIG. 4, made of an opaque metal layer. It does not reach the substrate surface because it is entirely covered by the common electrode 16, but the light indicated by the arrow D in the figure
That is, the light traveling toward the individual electrode 17 side is transmitted to each individual electrode 1
The area between 7 and 17 (between the lead portions 18 and 18 adjacent to each other and the land portion 1 adjacent to each other in FIG. 5).
7 and 17 or between the lead portion 18 and the adjacent land portion 19) to reach one surface of the substrate 3, and the other side through the optical fiber 2 embedded in the substrate 3 or the substrate itself. Will be released to the outside from the surface.

Since such scattered light is unnecessary light and is emitted from a place other than a desired place, when it is used as an optical writing head for optical writing on a photoconductor, for example, it is exposed to light. Except for the desired spot on the body, that is, unnecessary spots are exposed, and as a result, an electrostatic latent image is formed even on unnecessary spots. There was a problem that it occurred.

The present invention has been made in view of these points, and reduces the influence of scattered light in the light emitted from a light emitting element such as an LED chip with a simple structure,
It is an object of the present invention to provide a light emitting element array device that can always perform good light irradiation on an object.

[0019]

In order to achieve the above object, the light emitting element array device according to claim 1 forms a common electrode pattern and an individual electrode pattern on a first surface of a substrate in which an optical fiber bundle is embedded. And multiple LEDs
The chips are arranged in an array on the substrate so that the light emitting portions thereof face the first surface of the substrate, and the light from the light emitting portions of the LED chips is transmitted through the optical fiber bundle to the second surface of the substrate. In the light emitting element array device derived from the above, a driving IC chip for supplying a driving signal to the LED chip is arranged in an array on the individual electrode side of the LED chip on the substrate, and a light emitting portion of the LED chip is arranged. A transparent resin is filled between the LED chip and the drive IC and between the LED chip and the drive IC, and at least the upper surface of the transparent resin filled between the LED chip and the drive IC emits light from the LED chip. It is characterized in that a light absorption layer for absorbing the light emitted from the section is provided.

A light emitting element array device according to a second aspect is
The light emitting element array device according to claim 1, wherein the light absorption layer is formed of a color having a complementary color relationship with a light emission color of the light emitting element array.

A light emitting element array device according to a third aspect is
The light emitting element array device according to claim 1, wherein the light absorption layer is formed of a black color. A light emitting element array device according to a fourth aspect is the light emitting element array device according to the second and third aspects, wherein the light absorbing layer is formed of an oil-based ink.

[0022]

According to the present invention as set forth in claims 1 to 4, the amount of light incident on the substrate surface, which is scattered light emitted from the light emitting portion of the light emitting element in a direction other than the substrate surface, is determined. , And can be significantly reduced by absorption, and good light irradiation can always be performed on an object.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

In the following description of each embodiment, the same parts as those of the conventional one described above are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 1 shows an embodiment of a light emitting element array device of the present invention, and is a cross-sectional view showing the main part of a light emitting element array device 1 in this embodiment.

In this embodiment, the LED chip 4 is provided by providing the light absorbing layer for absorbing the light emitted from the light emitting portion of the LED chip on the transparent resin filled between the LED chip and the driving IC. The interface between the transparent resin and the air is substantially absent in the region where the light emitted from the PN junction surface 20 other than the direction toward the substrate 3 travels, and the light absorbing layer absorbs the light. However, the generation of scattered light itself is prevented.

That is, between the LED chip 4 and the substrate 3 and between the LED chip 4 and the driving IC chip 5,
While relaxing the mechanical strain generated between the LED chip 4, the substrate 3 and the solder bump 12 by thermal expansion,
A transparent resin 15 having a refractive index larger than that of air is filled in order to suppress diffusion of light emitted from the light emitting portion 14 of the LED chip 4 toward the substrate 3. However, in the present embodiment, A light absorption layer 29 is provided on the transparent resin 15, and the light absorption layer 29 is positioned such that its interface with the air is located above the upper surfaces of the LED chip 4 and the drive IC chip 5. Has been formed.

The light absorption layer 29 can absorb a large amount of light and prevent scattered light by using a color having a complementary color relationship with the color of the light emitted from the light emitting section 14. As a concrete example, the chromaticity diagram of FIG. 2 will be described. For example, when the color of the light emitted from the light emitting unit 14 is yellow, the color on the diagonal line passing through the point W in the figure is blue or blue-green. Has a complementary color relationship, and by forming this color as the light absorption layer 29, scattered light can be efficiently prevented. Similarly, the light emitting unit 1
When the color of the light emitted from 4 is red, the light absorption layer 29 may be green or blue green. Further, if the light absorption layer 29 has a black color, it is possible to absorb all colors of light regardless of the color of the light emitted from the light emitting section 14.

Further, when the light absorbing layer 29 is formed by using an oil-based ink in which a pigment such as carbon black is dispersed in an organic solvent, it is excellent in quick-drying due to the nature of the oil-based ink, and the light-emitting element array device. The manufacturing process for manufacturing can be simplified. In FIG. 1, the light absorption layer 29 is described as being relatively thick, but when ink or the like is applied, the thickness can be made extremely thin.

Next, the operation of this embodiment will be described.

Of the light generated on the PN junction surface 20 of the LED chip 4, the light emitted in the direction parallel to the surface of the substrate 3, that is, the directions indicated by arrows B and C in FIG.
The light emitted from the cut surfaces 4a and 4b of the ED chip 4 to the outside of the chip, and the light emitted to the outside of the chip enters the transparent resin 15 as it is and proceeds further. These lights further propagate from the transparent resin 15 to the light absorption layer 29 as indicated by arrows M and N in the figure, and are absorbed and attenuated there.

Therefore, according to the present embodiment, the light emitted from the light emitting portion 14 of the LED chip 4 in a direction other than the direction toward the substrate 3 does not become scattered light and does not enter the surface of the substrate 3 and is uniform. It is possible to irradiate an object with light with a high light amount and high accuracy.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified as necessary.

[0034]

As described above, the light emitting element array device of the present invention has a simple structure in which the light absorbing layer is formed.
It is possible to reduce the influence of scattered light in the light emitted from a light emitting element such as a chip, and it is possible to always perform good light irradiation on an object. Furthermore, by using a color having a complementary color relationship with the color of the light emitted from the light emitting portion for the light absorbing layer, efficient light absorption is possible and scattered light can be prevented.

Further, since the oil-based ink is quick-drying, it is not necessary to leave it to set for a certain time like a resin until it is solidified, and therefore the manufacturing process when manufacturing the light-emitting element array device can be simplified, and the light-absorbing layer made of the oil-based ink is extremely thin. Since it is a layer, there is a remarkable effect that it can be used without increasing the size of the light emitting element array device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part in an embodiment of a light emitting element array device of the present invention.

FIG. 6 is a chromaticity diagram showing a complementary color relationship.

FIG. 3 is a perspective view showing an overall configuration of a conventional light emitting element array device.

4 is a cross-sectional view showing a main part of the light emitting element array device of FIG.

5 is a top view showing a shape of an electrode pattern of the light emitting element array device of FIG.

[Explanation of symbols]

 1 Light-Emitting Element Array Device 2 Optical Fiber Bundle 3 Substrate 4 LED Chip 5 Driving IC Chip 7 Electrode Pattern 13, 24 Solder Dam Layer 14 Light Emitting Portion 15, 27, 28 Transparent Resin 16 Common Electrode 17, 21 Individual Electrode 19, 23 Solder Land Part 20 PN junction surface 29 Light absorbing layer

[Procedure amendment]

[Submission date] August 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part in an embodiment of a light emitting element array device of the present invention.

FIG. 2 is a chromaticity diagram showing a complementary color relationship.

FIG. 3 is a perspective view showing an overall configuration of a conventional light emitting element array device.

4 is a cross-sectional view showing a main part of the light emitting element array device of FIG.

5 is a top view showing a shape of an electrode pattern of the light emitting element array device of FIG.

[Description of Reference Signs] 1 light emitting element array device 2 optical fiber bundle 3 substrate 4 LED chip 5 driving ID chip 7 electrode pattern 13, 24 solder dam layer 14 light emitting part 15, 27, 28 transparent resin 16 common electrode 17, 21 individual electrode 19 , 23 Solder land portion 20 PN junction surface 29 Light absorbing layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 33/00 MN

Claims (4)

[Claims] 1. A common electrode pattern and an individual electrode pattern are formed on a first surface of a substrate in which an optical fiber bundle is embedded, and a plurality of LED chips are arranged so that their light emitting portions face the first surface of the substrate. In the light emitting element array device, which is arranged in an array on the substrate and guides the light from the light emitting portion of the LED chip from the second surface of the substrate via the optical fiber bundle, the individual LED chips on the substrate A driving IC chip for supplying a driving signal to the LED chip is arranged in an array on the electrode side, and is transparent between the light emitting portion of the LED chip and the substrate and between the LED chip and the driving IC. The resin is filled and at least the upper surface of the transparent resin filled between the LED chip and the driving IC is exposed from the light emitting portion of the LED chip. Emitting element array device is characterized by providing a light-absorbing layer that absorbs light. 2. The light emitting element array device according to claim 1, wherein the light absorption layer is formed of a color having a complementary color relationship with a light emission color of the light emitting element array. 3. The light emitting element array device according to claim 1, wherein the light absorption layer is formed in a blackish color. 4. The light emitting element array device according to claim 2, wherein the light absorption layer is formed of an oil-based ink.