JP2002043635A - Light emitting array chip and optical printer head using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element array chip and an optical printer head using the same in which a clear image can be formed by irradiating a photosensitive body with light of specified shape and intensity from each light emitting element. SOLUTION: The light emitting element array chip comprises a large number of light emitting elements 3 arranged on the upper surface of a rectangular semiconductor substrate 1 along the longitudinal direction thereof wherein a light shielding member 4 having a large number of through holes 5 for leading out light from respective light emitting elements 2 is fixed to the arranging region of the large number of light emitting elements 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED (Light Em
The present invention relates to a light-emitting element array chip in which a large number of light-emitting elements such as an itting diode are arranged in an array, and an optical printer head using the same.

[0002]

2. Description of the Related Art Conventionally, an optical printer head has been used as an exposure means of an electrophotographic printer or the like.

Such a conventional optical printer head has a structure in which a plurality of light emitting element array chips are attached and mounted in a line on the upper surface of a circuit board on which a large number of circuit wirings are attached. It is known that a large number of light-emitting elements provided on the upper surface of each light-emitting element array chip are selectively and individually made to emit light based on image data from the outside, and the emitted light is converted into an optical element such as a rod lens array. It functions as an optical printer head by irradiating an external photosensitive member via the system and forming a predetermined latent image on the photosensitive member.

Then, the latent image formed on the photoreceptor becomes a toner image through a developing process, and a predetermined image is formed on the recording paper by transferring and fixing the toner image on the recording paper.

As shown in FIG. 4, the light emitting element array chip has a large number of light emitting elements 12 linearly arranged at a predetermined dot density on the upper surface of a rectangular semiconductor substrate 11 along its longitudinal direction. And a large number of connection pads electrically connected to the light emitting elements 12. The connection pads of the light emitting element array chip are electrically connected to circuit wirings on the upper surface of the circuit board via bonding wires. Power supply, power supply power is supplied to the light emitting element 12 via circuit wiring, bonding wires and connection pads.
It is supplied to.

[0006]

However, according to the above-mentioned conventional optical printer head, the light emitted from the light-emitting element 12 (see the arrow in FIG. 4) tends to spread to the surroundings and travel to the photosensitive member. The size of the light is slightly larger than the actual size of the light emitting element 12. Therefore, when the light emitted from the light emitting element 12 is directly irradiated onto the photosensitive member without any restriction, the light of the adjacent light emitting elements 12 partially overlaps, and in particular, the light emitting element 15
In the case where are arranged at a high dot density of 600 dpi (dots per inch) or more, there is a disadvantage that the above-mentioned overlap of light becomes large and the image becomes extremely unclear.

In the above-described conventional optical printer head, a bonding wire for connecting a connection pad to a circuit conductor on a circuit board is usually formed of a glossy metal such as gold (Au) or aluminum (Al). Therefore, a part of the light emitted from the light emitting element 12 is reflected on the bonding wire and reflected, and when the reflected light is irradiated on the photoconductor, an unnecessary latent image is formed on the photoconductor. As a result, a drawback that an accurate image corresponding to the image data cannot be obtained is induced.

The present invention has been devised in view of the above-mentioned drawbacks, and has as its object to form a clear image by irradiating light emitted from each light emitting element to a photoreceptor with a predetermined size and intensity. An object of the present invention is to provide a light emitting element array chip and an optical printer head using the same.

[0009]

According to the present invention, there is provided a light emitting element array chip comprising a rectangular semiconductor substrate on which a plurality of light emitting elements are arranged along a longitudinal direction of the semiconductor substrate. A light-shielding member having a large number of through-holes for guiding light of each light-emitting element to the outside is attached to an upper surface of a semiconductor substrate and to an array region of a large number of light-emitting elements. .

Further, in the light emitting element array chip of the present invention, a large number of connection pads connected to an external electric circuit are arranged on the upper surface of the semiconductor substrate, and the light shielding between the connection pads and each light emitting element. It is characterized in that a part of the member is provided.

The optical printer head of the present invention has a plurality of light emitting element array chips mounted on a circuit board having a large number of circuit conductors, and connecting pads of the light emitting element array chips on a circuit board. It is characterized by being connected to a conductor via a bonding wire.

According to the light emitting element array chip of the present invention,
On the upper surface of the semiconductor substrate, and in the arrangement region of the light emitting elements, a light shielding member having a large number of through holes for guiding the light of each light emitting element to the outside is attached. Even if a part of them spreads to the periphery, they are absorbed on the inner surface of the through-hole or reflected toward the inside of the through-hole, and the spread of light is effectively prevented. Therefore, even when the light-emitting elements are arranged at high density, the light of the adjacent light-emitting elements does not greatly overlap on the photoconductor, and the size of each light applied to the photoconductor is determined by forming a latent image. In this case, a clear image can be formed.

Further, according to the present invention, by disposing a part of the light shielding member between each light emitting element and the connection pad, each light emitting element and the connection pad are well isolated by the light shielding member. Therefore, when an optical printer head is configured using such a light emitting element array chip, light emitted from the light emitting element hardly hits a bonding wire connected to a connection pad, and thus unnecessary light such as reflected light is emitted. Irradiation to the photoreceptor can be effectively prevented, and an accurate latent image corresponding to image data can be formed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a light-emitting element array chip according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of the light-emitting element array chip of FIG. 1 in the main scanning direction. The device 3 is a connection pad, 4 is a light shielding member, and 5 is a through hole.

The semiconductor substrate 1 is made of gallium arsenide (GaAs).
s) and a semiconductor material such as single crystal silicon (Si) are formed in a rectangular shape, and on the upper surface thereof, a number of light emitting elements 2 and a number of connection pads 3 are arranged in the longitudinal direction of the semiconductor substrate 1. It functions as a supporting base material for supporting them.

When the semiconductor substrate 1 is made of, for example, single crystal silicon, an ingot of single crystal silicon is formed by adopting a conventionally known Czochralski method (pulling method) or the like, and the ingot is formed to a predetermined thickness. It is manufactured by slicing and polishing the surface.

A large number of light emitting elements 2 provided on the semiconductor substrate 1 are linearly arranged at a dot density of, for example, 600 dpi over the longitudinal direction (main scanning direction) of the semiconductor substrate 1, and each of them is gallium arsenide. Has a structure in which a p-type semiconductor layer and an n-type semiconductor layer whose main components are a pn junction are stacked, so that when power is supplied via a circuit board or a connection pad 3 described later, Light is emitted at a predetermined luminance.

The plurality of light emitting elements 2 are of a planar type,
Any type of mesa type may be used. For example, when the mesa type light emitting element 2 is adopted, the light emitting element 2 is formed at a predetermined dot density on the upper surface of the semiconductor substrate 1 by a conventionally known MOCVD (organic metal chemical vapor deposition) method or the like. .

On the other hand, a large number of connection pads 3 provided on the upper surface of the semiconductor substrate 1 are electrically connected to the corresponding light emitting elements 2 via individual electrodes or the like, and are distributed to both sides of the arrangement of the light emitting elements 2 described above. And are arranged in parallel with the light emitting element 2.

When the light emitting element array chip is mounted on a circuit board of an optical printer head, the connection pad 3 is electrically connected to a circuit conductor on the circuit board via a bonding wire. When the light emitting element 2 emits light, power is supplied to the light emitting element 2 via the connection pads 3, bonding wires, circuit conductors on the circuit board, and the like.

The connection pads 3 are made of a metal such as gold (Au) or aluminum (Al), and are formed on a semiconductor substrate by employing a conventionally known thin film forming technique, specifically, a sputtering, photolithography technique, an etching technique or the like. 1 is attached and formed in a predetermined pattern on the upper surface.

Further, on the upper surface of the semiconductor substrate 1 and in the arrangement region of the large number of light emitting elements 2, a light shielding member 4 having a large number of through holes 5 for guiding the light of each light emitting element 2 to the outside is provided. It is attached.

The light shielding member 4 is formed by combining a pair of partition walls erected along the main scanning direction on both sides of the array of the light emitting elements 2 and a partition plate erected between the adjacent light emitting elements 2 and 2. A through hole 5 is formed in a region surrounded by the partition wall and the partition plate.

The light shielding member 4 is made of an epoxy resin or an acrylic resin having a light transmittance of, for example, 0.1% to 50% with respect to the light of the light emitting element 2. When the light emitting element 2 emits light,
Even if a part of it is going to spread around,
The light impinges on the inner surface of the through hole 5 or is reflected toward the inside of the through hole 5 to effectively prevent the spread of light.

Therefore, the light emitting element 2 is, for example, 600 dpi.
Even in the case of high density arrangement with the above dot density,
The light of the adjacent light emitting elements 2 does not greatly overlap on the photoconductor, and the size of each light irradiated on the photoconductor is set to a size suitable for forming a latent image, thereby forming a clear image. It becomes possible.

A glossy metal such as gold or aluminum is adhered to the inner surface of the through-hole 5, or a light-shielding member itself is made of a glossy material, for example, the light reflectance of the light emitted from the light emitting element 2 is 70%. As described above, if a predetermined amount of a gold pigment or the like is added to an acrylic resin or an epoxy resin or the like, most of the light hitting the inner surface of the through hole 5 is reflected toward the inside of the through hole 5. Therefore, by irradiating the photoreceptor with these reflected lights together with the direct light from the light emitting element 2, the intensity of the light applied to the photoreceptor can be maintained at a high level, whereby a clear image can be formed. Becomes possible.

Further, in this case, a part of the light shielding member 4 is disposed between each light emitting element 2 and the connection pad 3, and each light emitting element 2 and the connection pad 3 are satisfactorily isolated from each other by the light shielding member 4. Therefore, when an optical printer head is constructed using such a light emitting element array chip, the light emitting element 2
Hardly hits the bonding wire connected to the connection pad 3. Therefore, it is possible to effectively prevent unnecessary light such as reflected light from irradiating the photoreceptor, and to obtain an accurate latent light corresponding to image data. An image can be formed.

The height of the light shielding member 4 is 4 μm.
When a mesa-type light-emitting element 2 of about
The light shielding member 4 is set to 6.0 μm to 100 μm, which is equivalent to 20 times to 25 times, and when the light shielding member 4 is made of acrylic resin,
First, a liquid precursor of an ultraviolet curable acrylic resin is applied to a predetermined region on the upper surface of the semiconductor substrate using a dispenser or the like,
This is processed into a predetermined pattern through the steps of exposure and development to be integrally formed on the upper surface of the semiconductor substrate 1.

Next, an optical printer head manufactured using the above-described light emitting element array chip will be described. 3 is a cross-sectional view of an optical printer head manufactured using the light emitting element array chips of FIGS. 1 and 2, in which 6 is a circuit board, 7 is circuit wiring, 8 is a light emitting element array chip, 9 Is a bonding wire.

The optical printer head shown in FIG. 1 has a structure in which a plurality of the light emitting element array chips 8 are mounted in a row on the upper surface of a circuit board 6 formed in a rectangular shape. .

The circuit board 6 is formed of an electrically insulating material such as a glass cloth base epoxy resin, glass, or ceramic, and has a large number of circuit wirings 7, a plurality of light emitting element array chips 8, driver ICs on its upper surface. (Not shown)
It functions as a supporting base material for supporting the like.

When the circuit board 6 is made of, for example, a glass cloth base epoxy resin, a glass cloth base formed using glass threads is impregnated with a liquid epoxy resin and cured.
It is manufactured by cutting this into a predetermined rectangular shape.

The circuit wiring 7 on the upper surface of the circuit board functions as a power supply wiring for supplying power to the light emitting elements 2 of the light emitting element array chip 8. It is electrically connected to the corresponding connection pad 3 of the light emitting element array chip 8.

The circuit wiring 7 is formed, for example, by adding an appropriate organic solvent, an organic binder and a glass frit to silver powder.
A predetermined conductive paste obtained by mixing is printed and applied on the upper surface of the circuit board 1 by conventionally known screen printing or the like, and is baked at a high temperature to form a predetermined pattern.

A bonding wire 9 for connecting the circuit conductor 7 and the connection pad 3 of the light emitting element array chip 8 is provided.
Is formed of a shiny metal such as gold or aluminum, and is bonded by employing a conventionally known wire bonding method.

At this time, since the connection pads 3 to which the bonding wires 9 are connected and the respective light emitting elements 2 are isolated by the light shielding members 4 as described above, the light emitted from the light emitting elements 2 hardly hits the bonding wires 9. In addition, it is possible to effectively prevent unnecessary light such as reflected light from irradiating the photosensitive member, and to form an accurate latent image corresponding to image data.

Thus, the above-described optical printer head selectively emits a large number of light emitting elements 2 provided on the upper surface of the light emitting element array chip 8 individually on the basis of image data from the outside. To an external photoreceptor through an optical system such as a rod lens array to form a predetermined latent image, thereby functioning as an optical printer head.The latent image formed on the photoreceptor is then subjected to a developing process. Then, a toner image is formed, and a predetermined image is formed on the recording paper by transferring and fixing the toner image on the recording paper.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, the light-blocking member 4 is formed by exposing and developing an ultraviolet-curable resin and processing the resin into a predetermined shape. Specifically, the light shielding member 4 may be formed by processing a resin material or the like into a predetermined shape by sputtering, photolithography technology, etching technology, or the like.

[0040]

According to the light emitting element array chip of the present invention, on the upper surface of the semiconductor substrate and in the light emitting element array region,
Since a light-blocking member with a large number of through holes for guiding the light of each light-emitting element to the outside is attached, when the light-emitting element emits light, even if a part of the light-emitting element tries to spread around, Absorbs on the inner surface of the through hole or is reflected toward the inside of the through hole, and the spread of light is effectively prevented.
Therefore, even when the light emitting elements are arranged at a high density,
To form a clear image by preventing the light of the adjacent light emitting elements from greatly overlapping on the photoreceptor and making each light irradiated on the photoreceptor a size suitable for forming a latent image Becomes possible.

Further, according to the present invention, by disposing a part of the light shielding member between each light emitting element and the connection pad, each light emitting element and the connection pad are satisfactorily isolated from each other by the light shielding member. Therefore, when an optical printer head is configured using such a light emitting element array chip, light emitted from the light emitting element hardly hits the bonding wire connected to the connection pad, and therefore unnecessary light such as reflected light is emitted. Irradiation to the photoreceptor can be effectively prevented, and an accurate latent image corresponding to image data can be formed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a light-emitting element array chip according to one embodiment of the present invention.

FIG. 2 is a sectional view of the light emitting element array chip of FIG. 1 in a main scanning direction.

FIG. 3 is a cross-sectional view of an optical printer head manufactured using the light emitting element array chips of FIGS. 1 and 2;

FIG. 4 is a sectional view of a conventional light emitting element array chip in a main scanning direction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Light emitting element, 3 ... Connection pad, 4 ... Light shielding member, 5 ... Through-hole, 6 ...
Circuit board, 7: Circuit conductor, 8: Light emitting element array chip, 9: Bonding wire

Claims (3)

[Claims] 1. A light emitting element array chip comprising a plurality of light emitting elements arranged on a top surface of a rectangular semiconductor substrate along a longitudinal direction of the semiconductor substrate. A light-emitting element array chip, wherein a light-shielding member having a large number of through holes for guiding light of each light-emitting element to the outside is attached to a region. 2. A plurality of connection pads connected to an external electric circuit are arranged on an upper surface of the semiconductor substrate, and a part of the light shielding member is disposed between the connection pads and each light emitting element. The light emitting element array chip according to claim 1, wherein 3. A plurality of light emitting element array chips according to claim 1 are mounted on a circuit board having a large number of circuit conductors, and connection pads of these light emitting element array chips are mounted on the circuit board. An optical printer head, wherein the optical printer head is connected to the circuit conductor through a bonding wire.