JPH10244702A - Optical writing head for printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high quality print by disposing each condenser lens in contact with the emission surface of light emitting element corresponding to the condenser lens thereby eliminating warp of the condenser lens. SOLUTION: A first planoconvex lens 20 is arranged in contact with the upper surface of the emission surface 14a of an LED 10. Upper surface of the LED 10 including the first planoconvex lens 10 is then covered with an intermediate layer 22 and a second planoconvex lens 25 is arranged on the upper surface of the intermediate layer 22 continuously thereto and integrally therewith. The intermediate layer 22 and the second planoconvex lens 25 thereon are made of a same material and the second planoconvex lens 25 is arranged on a flat surface, in contact therewith, on the side opposite to the first planoconvex lens 20. Since no load is applied to the lens 20, it is not warped. Consequently, blur and distortion are eliminated from an image formed by diffracting and condensing an outgoing light from the LED 10 through the first and second planoconvex lenses 20, 25, resulting in the enhancement of print quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical writing head for a printer.

[0002]

2. Description of the Related Art Conventionally, as an optical writing head of this kind for a printer, a literature (Oki Electric R & D, 157, Vol.
60, no. 1, JAN. 1993, p. 45-48)
Are disclosed.

This optical writing head includes a plurality of light emitting elements (light emitting diodes (LE)
D)), a plurality of driver IC chips provided in parallel with and opposed to the LED array,
And a condenser lens (rod lens) provided above D. The LED and the driver IC are connected by a bonding wire.

The rod lens is a condenser lens for condensing the light emitted from the LED, and the light emitted from the LED condensed by the rod lens forms an image on a photosensitive drum and is subjected to optical writing. You.

[0005]

However, the above-mentioned optical writing head is provided with a holder for fixing a condenser lens (rod lens) above the LED. When the rod lens is fixed using this holder,
The rod lens may be warped. Hereinafter, with reference to FIGS. 11A and 11B, a description will be given of warpage when a conventional rod lens is fixed. FIG.
FIGS. 1A and 1B are diagrams for explaining warpage when a rod lens is fixed to a holder.

[0006] After the rod lens 50 is mounted on the reference surface 52a of the holder 52, pressing means from the upper surface of the holder 52,
For example, it is pressed and fixed using a screw. At this time, the rod lens 50 is bent by a distance of x below the normal line in which the central portion is not pressed by the pressing from the upper portion, and warps in the vertical direction.

[0007] Both sides of the rod lens 50 are filled with resin for fixing the rod lens 50. For this reason, when the resin is filled, the rod lens 5 may be deformed due to a difference in thermal expansion coefficient of the resin or a difference in curing speed of the resin.
The load is also applied from the side of 0, and the LED reference line (L)
However, there is a problem that a horizontal warp is caused in a direction perpendicular to the direction by the distance y.

If the rod lens 50 is warped in the vertical and horizontal directions, the optical axis of the LED and the optical axis of the rod lens are displaced, so that the image formed on the photosensitive drum is blurred or distorted. Print quality is degraded.

Therefore, there has been a demand for an optical writing head for a printer which eliminates the warpage of the condenser lens and enables high quality printing.

[0010]

Therefore, according to the optical writing head for a printer of the present invention, a plurality of light emitting elements,
In an optical writing head for a printer including a plurality of condenser lenses, each of the condenser lenses is provided in contact with a light emitting surface of a light emitting element corresponding to the condenser lens.

As described above, in the present invention, since the condenser lens is provided in contact with the light emitting surface of the light emitting element, it is not necessary to fix the condenser lens using a conventional holder or the like. Therefore, no load is applied to the condenser lens, so that the optical axis of the light emitting element and the optical axis of the condenser lens can be substantially matched. For this reason, it is possible to prevent the image condensed and formed by the light emitted from the light emitting element from being blurred or distorted.

In the present invention, it is preferable that the condenser lens is a first plano-convex lens, and the flat surface side of the first plano-convex lens is provided in contact with the light emitting surface. As described above, since the first plano-convex lens is provided in contact with the light-emitting surface, light emitted from the light-emitting surface is refracted by the first plano-convex lens and condensed at a predetermined focal length. For this reason, compared to the related art, since the lens is not warped, a good print quality can be obtained.

In the present invention, preferably, the condensing lens is constituted by an intermediate layer and a first lens provided continuously and integrally on the upper surface of the intermediate layer. Preferably, a flat lower surface is provided in contact with the light emitting surface.

As described above, in the present invention, the intermediate layer is provided in contact with the light emitting surface, and the first lens is provided on the upper surface of the intermediate layer. And is refracted by the first lens and condensed to a predetermined focal length. Also in this case, since no load is applied to the first lens, the first lens does not warp. For this reason, compared to the related art, since the lens is not warped, a good print quality can be obtained.

In the present invention, preferably, the condenser lens is a Fresnel lens. By using a Fresnel lens as the condenser lens in this way, the thickness of the lens can be reduced, so that the size of the optical writing head can be reduced.

In the present invention, the first lens is preferably a first plano-convex lens, and the intermediate layer is preferably a plane-parallel plate-like layer.

As described above, by forming the first lens as the first plano-convex lens and the intermediate layer as a plane-parallel plate-like layer, light emitted from the light emitting surface relays the plane-parallel layer to the first plane-convex layer. The light is refracted by one plano-convex lens and condenses at a predetermined focal length. Therefore, unlike the conventional case, the first plano-convex lens does not warp, so that a condensed image can have good print quality.

In the present invention, the first lens and the intermediate layer are preferably formed of the same material.

By forming the first lens and the intermediate layer with the same material in this way, the steps for forming the first lens are reduced, and the workability is improved.

In the present invention, preferably, the condenser lens includes a first plano-convex lens provided in contact with the light emitting surface,
It is preferable that the light emitting device includes an intermediate layer provided on the upper surface of the light emitting element including the first plano-convex lens, and a second lens continuously and integrally provided on the upper surface of the intermediate layer.

As described above, in the present invention, the first plano-convex lens is provided in contact with the light-emitting surface, and the intermediate layer provided on the upper surface of the light-emitting element including the first plano-convex lens is connected to the upper surface of the intermediate layer. Light emitted from the light emitting surface is refracted by the first plano-convex lens, relays the intermediate layer, and is further refracted by the second lens to a predetermined level. Focus on focal length. Also in this case, since the first plano-convex lens and the second lens are not subjected to a load as in the related art, a good image without defocus or distortion can be obtained.

In the present invention, preferably, the first lens region is opened and the other upper surface region of the intermediate layer or the second lens region is opened, and the upper surface region of the intermediate layer is covered with a light shielding film. Is good.

As described above, in the present invention, since the upper surface of the intermediate layer other than the first lens and the second lens is covered by the light-shielding film, light diverging from the light-emitting surface is shielded by the light-shielding film. . Therefore, the light emitted from the light emitting surface is
Since the light is emitted only from the surface other than the first lens and the second lens, the imaging resolution of the light emitting element is further improved.

In the present invention, preferably, the first plano-convex lens is made of silicon nitride or alumina, and the second lens is made of silicon oxide. Preferably, the first plano-convex lens is made of polycarbonate or polystyrene, and the second lens is made of polymethyl methacrylate.

As described above, by selecting the material of the first plano-convex lens and the material of the second lens, the refractive indices of the first plano-convex lens and the second lens can be arbitrarily changed. Can be condensed to a predetermined focal length.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical writing head for a printer according to the present invention will be described below with reference to the drawings. FIGS. 1 to 10 merely show the shapes, sizes and arrangements of the components so that the configuration of the optical writing head for a printer can be understood.

[First Embodiment] The structure of an optical writing head for a printer and the structure of an apparatus including this head according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view for explaining a first structural example of a main part of an optical writing head for a printer according to the present invention, in particular, a part of a light emitting element having a condenser lens, and FIG. FIG. 2 is a perspective view for explaining the overall configuration of a device including a write head. Although FIG. 1 shows an example in which two light-emitting elements (here, LEDs) are provided, a plurality of LEDs are actually arranged at a predetermined pitch.

In the optical writing apparatus for a printer according to the present invention, a condensing lens is not provided in the intermediate portion between the LED array and the photosensitive drum, but the condensing lenses are respectively associated with the light emitting surfaces of the LEDs. It is provided in contact. Thus, the light emitting element 101 in which the LED and the condenser lens are integrated and combined is referred to as an LED having a condenser lens here. Hereinafter, the structure of the LED 101 having a condenser lens will be described in detail with focus on the LED 101.

The optical writing device of the present invention can be broadly classified as follows.
It comprises an optical writing head 100 and a photosensitive drum 200 for printing an image by development (FIG. 6).

The optical writing head 100 includes an LED 101 having a plurality of condenser lenses on a wiring board (S).
And a plurality of driver ICs 103 are mounted in parallel and in parallel. Here, a plurality of LEDs 101 having a condensing lens are arranged in a straight line.
Called array 102.

Further, an electrode (not shown) provided on the light emitting surface 14a of the LED 101 having the condenser lens and the driver IC 103 are connected by a bonding wire (not shown).

In the first embodiment, the LED 101 having the condensing lens is integrally formed on the light emitting surface 14a of the LED 10 by being connected to the first plano-convex lens 20, the intermediate layer 22, and the upper surface of the intermediate layer 22. The second lens 25 is provided (FIG. 1). Then, the second lens 25
Is formed in a plano-convex lens shape. Therefore, here, the second lens 25 is referred to as a second plano-convex lens.

The LED 10 according to the first embodiment has n
-Type GaAs substrate 12, an n-type GaAsP layer 14 formed on the n-type GaAs substrate 12, and an n-type GaAs
It is composed of a p-type GaAsP diffusion region 16 formed on the P layer 14.

The first plano-convex lens 20 is provided in contact with the upper surface of the light emitting surface 14a of the LED 10. Here,
The material of the first plano-convex lens 20 is, for example, silicon nitride (S
iN ₂ ).

The intermediate layer 22 is formed of the first plano-convex lens 20.
The intermediate layer 2 provided over the upper surface of the LED 10 including
The second plano-convex lens 25 is provided continuously and integrally on the upper surface 22a of the second. The intermediate layer 22 and the second plano-convex lens 25 on the intermediate layer 22 are formed of the same material, and the second plano-convex lens 25 is formed on a flat surface of the intermediate layer 22 opposite to the first plano-convex lens 20 (intermediate layer). 22) is provided in contact with the upper surface 22a. Naturally, this intermediate layer 22
The second plano-convex lens 25 and the second plano-convex lens 25 may be separately provided, and the two may be joined to each other.

The second plano-convex lens 25 is the first plano-convex lens 2
The first plano-convex lens 20 is provided on the upper side of 0 so as to face the first plano-convex lens 20. Here, the material of the intermediate layer 22 and the second plano-convex lens 25 is silicon oxide (SiO ₂ ).

As described above, in the first embodiment,
The first plano-convex lens 20 is provided in contact with the upper surface of the light emitting surface 14a of the LED 10, and the second plano-convex lens 20 is provided in contact with the upper surface 22a of the intermediate layer.
By providing the plano-convex lens 25, a load is not applied to the lens unlike the related art, so that the lens does not warp.
For this reason, an image in which the light emitted from the LED is refracted and condensed by the first plano-convex lens and the second lens is not defocused or distorted, so that good print quality can be obtained. Further, the number of parts can be reduced because a rod lens is not required unlike the related art.

[Second Embodiment] Next, a second embodiment of the optical writing head for a printer according to the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating the structure of an LED having a condenser lens, which is a main part of the optical writing head for a printer according to the second embodiment.
In this example, an LE having a condenser lens constituting the head is used.
The structure of D is different from that of the first embodiment.

In the second embodiment, mainly the LED
It has a structure in which only the first plano-convex lens 20 is provided on the light emitting surface 14a of No. 10 and does not include an intermediate layer or a second plano-convex lens (FIG. 2). Since the configuration of the LED 10 is the same as that of the above-described first embodiment, the details are omitted here. In addition,
Here, the material of the first plano-convex lens 20 is silicon nitride (S
iN ₂ ).

As described above, since the first plano-convex lens 20 is provided in contact with the light emitting surface 14a, the light emitted from the light emitting surface 14a is refracted by the first plano-convex lens 20 and condensed at a predetermined focal length. I do. For this reason, good print quality can be obtained because the lens does not warp as in the related art.

[Third Embodiment] Next, a third embodiment of the optical writing head for a printer according to the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating the structure of an LED having a condenser lens, which is a main part of the optical writing head for a printer according to the third embodiment.
In this example, an LE having a condenser lens constituting the head is used.
The structure of D is different from the first and second embodiments described above.

In the third embodiment, on the LED 10,
An intermediate layer 22 is provided, and an upper surface (flat surface) 2 of the intermediate layer 22 is provided.
It is constituted by a first lens 23 provided integrally and continuously with 2a. Also, the intermediate layer 22 and the light emitting surface 14a
No other lens is provided between the LED 10 and the LED 10, and the flat lower surface 22b of the intermediate layer 22 is provided directly in contact with the light emitting surface 14a of the LED 10 (FIG. 3). LED 10 of Third Embodiment
Is the same as the LED configuration of the first embodiment. In addition,
Here, the first lens 23 is a so-called biconvex lens. Therefore, a portion of the upper surface 22a of the intermediate layer 22 that is in contact with the spherical surface of the biconvex lens (first lens) 23 is a concave portion having the same curvature as the spherical surface. Also in this case, the intermediate layer 22 and the first lens 23 may be individually provided and joined together, or may be integrally formed from the beginning using the same material.

As described above, in the third embodiment,
An intermediate layer 22 is provided in contact with the light emitting surface 14a of the LED 10,
Since the first lens 23 is provided on the upper surface of the intermediate layer 22, the light (emission light) emitted from the light emitting surface 14a is refracted by the first lens 23 by relaying the intermediate layer 22 to reach a predetermined focal length. Focuses and forms an image.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view illustrating the structure of an LED having a condenser lens, which is a main part of the optical writing head for a printer according to the fourth embodiment.

In this example, the structure of the LED having the condensing lens constituting the head is the first, second and third structures described above.
This is different from the embodiment.

In the fourth embodiment, an intermediate layer 22 is provided on the LED 10, and a first lens (first plano-convex lens) 23 a provided continuously and integrally on the upper surface of the intermediate layer 22.
It is constituted by. Here, the intermediate layer 22
Is a plane-parallel plate-like layer, and the first lens 23a is a plano-convex lens (hereinafter, referred to as a first plano-convex lens). Also,
The flat lower surface 22b of the intermediate layer 22 is used as the light emitting surface 1 of the LED 10.
4a is provided in direct contact with it (FIG. 4). The LED 10 according to the fourth embodiment has the same configuration as the LED configuration according to the first embodiment. Also in this case, the intermediate layer 22 and the first plano-convex lens 23a may be separately provided and joined together.

Here, the first plano-convex lens 23a and the intermediate layer 22 are formed of the same material, and the material is, for example, silicon nitride (SiN ₂ ).

In the fourth embodiment, since the first lens of the third embodiment is a first plano-convex lens 23a, the upper surface 22a of the intermediate layer 22 is provided as in the third embodiment.
Since there is no need to form a concave lens groove in the step, the working process is simplified.

[Fifth Embodiment] Next, a fifth embodiment of the optical writing head for a printer according to the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view for explaining the structure of an LED having a condenser lens, which is a main part of the optical writing head for a printer according to the fifth embodiment.

In this example, the structure of the LED having the condenser lens constituting the head is the same as the structure of the first embodiment, and is different in that a light shielding film is provided on the intermediate layer 22.

In the fifth embodiment, the second plano-convex lens 2
5 is opened, and the other upper surface area of the intermediate layer 22 is covered with a light shielding film 26 (FIG. 5).

In the fifth embodiment, as the light shielding film 26, for example, a metal film such as aluminum (Al) is used.

By providing such a light-shielding film 26 on the upper surface 22a of the intermediate layer 22, the emitted light emitted from the LED 10 does not leak to the photosensitive drum 200 side. Can obtain a good image without defocus or distortion. For this reason, even better print quality can be obtained as compared with the first embodiment.

In the fifth embodiment, the example in which the light shielding film 26 is provided on the upper surface 22a of the intermediate layer 22 of the first embodiment has been described. However, the intermediate layer 2 of the third and fourth embodiments has been described.
A light-shielding film 26 may be provided on the upper surface 22a of the second. The other configuration is the same as that of the first embodiment, and the details are omitted here.

[Method of Forming LED Having Condensing Lens of First Embodiment] Next, with reference to FIGS. 7, 8 and 9, optical writing for a printer according to the first embodiment of the present invention will be described. A method of forming the head will be briefly described. Note that FIG.
FIG. 8 and FIG. 9 are cross-sectional views for explaining a process of forming an LED having a condenser lens constituting the head of the present invention. In practice, a plurality of light emitting surfaces are provided in one LED chip, but here, one LE chip is used.
The description will be made focusing on the light emitting surface of D.

As the substrate 12, an n-type GaAs substrate is used. An n-type GaAsP layer 14 is formed on the n-type GaAs substrate 12 by epitaxial growth using, for example, the MBE method. Thereafter, an impurity element (eg, zinc) is selectively diffused into a predetermined region on the upper surface of the n-type GaAsP layer 14 to form a p-type GaAsP diffusion region 16 (FIG. 7A). As described above, the substrate 12, the n-type GaAsP layer 14, and the p-type GaAsP diffusion region 16 are collectively referred to as a light emitting element (LED) 10.

Next, n including the p-type GaAsP diffusion region 16
After an electrode (not shown) for supplying a current is formed on the p-type GaAsP layer 14, the p-type GaAsP diffusion region 1 is formed.
A silicon nitride (SiN ₂ ) film 18 is formed on the n-type GaAsP layer 14 including the silicon nitride 6 by using any suitable method (FIG. 7).
(B)). Although the SiN ₂ film 18 was used here, alumina (Al ₂ O ₃ ) was used instead of the SiN ₂ film 18.
A film, a polycarbonate film, a polystyrene film, or the like may be used.

Next, SiN is formed using photolithography technology.
₂ Etching the film 18 to form the p-type GaAsP diffusion region 16
The first plano-convex lens 20 made of the SiN ₂ film 18 is formed on the upper surface 14a of the substrate (FIG. 7C). In this case, it is preferable to repeat the photolithography process several times to etch the SiN ₂ film 18 so as to finish the first plano-convex lens 20 in order. The lens diameter of the first plano-convex lens 20 thus formed is set to 60 μm.

Since the refractive index of the first plano-convex lens 20 is determined by the material, the refractive index of SiN ₂ is 2.03.

Next, an n-type GaAs including the first plano-convex lens 20
An intermediate layer (silicon oxide (SiO ₂ ) layer) 22 is formed on the sP layer 14 using, for example, a CVD method. At this time,
Since the first plano-convex lens 20 has a convex shape, the upper surface of the silicon oxide layer 22 formed above the first plano-convex lens 20 also has a convex shape (FIG. 8A).

Next, in order to flatten the upper surface of the silicon oxide layer 22, a flattening film (photoresist film here) 24 is formed on the silicon oxide layer 22 (FIG. 8B). Thereafter, the upper surface of the silicon oxide layer 22 is made a flat surface 22a using an etch-back method (FIG. 8C).

Next, using the photolithography technique again,
A second lens 25 made of the same material as the silicon oxide layer 22 is formed on the silicon oxide layer 22 (FIG. 9). When the second lens 25 is formed, the photolithography process may be repeated several times in the same manner as when the first plano-convex lens 20 is formed, to form the second lens into a plano-convex lens shape. In this case, the material of the second plano-convex lens is silicon oxide (SiO ₂ ).
Polymethyl methacrylate may be used instead of iO ₂ .

It is preferable that the second plano-convex lens 25 is formed to face the first plano-convex lens 20 and to be larger than the diameter of the first plano-convex lens 20. Here, the lens diameter of the second plano-convex lens 25 is 80 μm. Since the refractive index of the second plano-convex lens is determined by the material of SiO ₂ ,
1.43. Through the above steps, the optical writing head according to the first embodiment is completed.

Next, the head according to the first embodiment described above,
That is, the result of obtaining the focal length of the second plano-convex lens using two lenses will be described below. In this embodiment, a ray tracing method is used as a method for obtaining the focal length.

In this embodiment, a dot density of 300
In the case of DPI, the light emitting element of each LED is 84.6.
Since they are arranged at a pitch of μm, the first plano-convex lens 2
The lens diameter of 0 is set to 60 μm. First plano-convex lens 2
0 is 30 μm and the distance between the first plano-convex lens 20 and the second plano-convex lens 25 is about 100 μm, the second
The lens diameter of the plano-convex lens 25 is 80 μm, and the curvature is 20 to 3
When it is set to 0 μm, the focal length of the second plano-convex lens 25 is about 500 μm.

As the material of the first plano-convex lens 20,
When polycarbonate is used and polymethyl methacrylate is used as the material of the second plano-convex lens 25, the focal length of the second plano-convex lens is as follows.

The refractive index of polycarbonate is 1.6, and the refractive index of polymethyl methacrylate is 1.49.

Also in this case, the individual LEDs are 84.6 μm
Therefore, the lens diameter of the first plano-convex lens 20 is set to 60 μm. At this time, assuming that the curvature of the first plano-convex lens 20 is 30 μm,
When the distance between the second plano-convex lenses 25 is about 200 μm, and when the lens diameter of the second plano-convex lenses 25 is 80 μm and the curvature is 20 to 30 μm, the focal length of the second plano-convex lenses 25 is about 500 μm.

Next, referring to FIG. 6 and FIG. 10, the first embodiment of the optical writing head for a printer according to the present invention will be described as an example, and the operating principle and the manner in which the light emitted from the LED is collected will be described. explain. FIG. 10 is a diagram for explaining how the light emitted from the LED is collected.

The driver IC 103 of the printer optical writing head 100 is supplied with print data, control signals such as a clock signal (CLK), and a power supply voltage (V _DD ). The control signal and the power supply voltage output from the driver IC 103 are supplied to the LED 101 having a condenser lens via a bonding wire (not shown) (FIG. 6).

When a lighting current corresponding to the print data is supplied to the LED 101 having the condenser lens, the LED 10 emits light. At this time, the light emitted by the LED 10 is refracted by the first plano-convex lens 20, further relayed through the intermediate layer 22, and further refracted by the second plano-convex lens 25, and the LED image is condensed to a predetermined focal length f. I do. The images converged by the first plano-convex lens 20 and the second plano-convex lens 25 are formed on the photosensitive drum 200.

In the above-described embodiment, an example in which an LED is used as a light emitting element has been described. However, the present invention is not limited to an LED, and may be applied to, for example, an electroluminescent element (EL element). It is.

Further, in the above-described embodiment, an example has been described in which the first plano-convex lens or the second lens is used as the condensing lens, but a Fresnel lens may be used instead of these lenses. Since the Fresnel lens is a lens that condenses light by reducing the thickness of the lens, the use of the Fresnel lens on the light emitting element surface has the advantage that the optical writing head can be downsized.

[0074]

As is apparent from the above description, according to the optical writing head for a printer of the present invention, each of the condenser lenses is provided in contact with the light emitting surface of the light emitting element corresponding to the condenser lens. Since there is no need to apply a mechanical pressing load or a load due to the embedded resin to the individual condensing lenses unlike the related art, there is no warping or distortion of the condensing lenses. For this reason, the image of the light emitting element condensed by the condensing lens does not cause defocus or distortion, so that good print quality can be obtained.

In the present invention, since the condenser lens is opened and the upper surface of the other intermediate layer is covered with the light shielding film,
The light emitted from the light emitting element is not blocked and leaks to the photosensitive drum side, so that the imaging resolution of the light emitting element can be further improved.

In the present invention, the size of the optical writing head can be reduced by using a Fresnel lens as the condenser lens.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a structure of an optical writing head for a printer according to a first embodiment of the present invention.

FIG. 2 is a sectional view for explaining a structure of an optical writing head for a printer according to a second embodiment of the present invention;

FIG. 3 is a sectional view for explaining the structure of an optical writing head for a printer according to a third embodiment of the present invention;

FIG. 4 is a sectional view for explaining a structure of an optical writing head for a printer according to a fourth embodiment of the present invention;

FIG. 5 is a sectional view for explaining the structure of an optical writing head for a printer according to a fifth embodiment of the present invention.

FIG. 6 is a perspective view for explaining the overall structure of the optical writing head device for a printer according to the present invention.

FIGS. 7A to 7C are cross-sectional views for explaining a method for forming an optical writing head for a printer according to the first embodiment of the present invention.

8 (A) to 8 (C) are cross-sectional views following FIG. 7 for explaining a method of forming an optical writing head for a printer.

FIG. 9 is a sectional view following FIG. 8 for explaining a method of forming the optical writing head for a printer.

FIG. 10 is a diagram for explaining how light emitted from an LED is collected by a first plano-convex lens and a second plano-convex lens.

11A and 11B are a side view and a plan view for explaining a state of a load and a warp applied to a conventional rod lens array.

[Explanation of symbols]

 101: LED having a condensing lens 10: LED 12: n-type GaAs substrate 14: n-type GaAsP layer 16: p-type GaAsP diffusion region 20: first plano-convex lens 22: intermediate layer 22a: upper surface of intermediate layer 22b: intermediate layer Lower surface 23: first lens 23a: first plano-convex lens 25: second plano-convex lens 26: light shielding film

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hiroshi Toyama 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (12)

[Claims] 1. An optical writing head for a printer comprising a plurality of light emitting elements and a plurality of condenser lenses, wherein each of the condenser lenses is in contact with a light emitting surface of the light emitting element corresponding to the condenser lens. An optical writing head for a printer, wherein the optical writing head is provided. 2. The optical writing head according to claim 1, wherein said condensing lens is a first plano-convex lens, and a flat surface side of said first plano-convex lens is provided in contact with said light emitting surface. Optical writing head for printer. 3. The optical writing head according to claim 1, wherein the condenser lens comprises an intermediate layer and a first lens provided continuously and integrally on an upper surface of the intermediate layer. An optical writing head for a printer, wherein a flat lower surface of the intermediate layer is provided in contact with the light emitting surface. 4. The optical writing head according to claim 3, wherein said first lens is a first plano-convex lens, and said intermediate layer is a plane-parallel plate-like layer. . 5. The optical writing head according to claim 3, wherein the first lens and the intermediate layer are formed of the same material. 6. The optical writing head according to claim 1, wherein the condenser lens is provided on a first plano-convex lens provided in contact with the light-emitting surface and on an upper surface of the light-emitting element including the first plano-convex lens. An optical writing head for a printer, comprising: an intermediate layer provided; and a second lens provided continuously and integrally on an upper surface of the intermediate layer. 7. The optical writing head for a printer according to claim 6, wherein the second lens is a second plano-convex lens. 8. The optical writing head for a printer according to claim 3, wherein an area of the first lens is opened, and another upper surface area of the intermediate layer is covered with a light shielding film. head. 9. The optical writing head according to claim 6, wherein an area of the second lens is opened and an upper surface area of the intermediate layer is covered with a light shielding film. 10. The optical writing head according to claim 6, wherein said first plano-convex lens is made of silicon nitride or alumina, and said second lens is made of silicon oxide. 11. The optical writing head according to claim 6, wherein said first plano-convex lens is made of polycarbonate or polystyrene, and said second lens is made of polymethyl methacrylate. 12. The optical writing head according to claim 1, wherein the condenser lens is a Fresnel lens.