JP2001301230A - Exposing unit - Google Patents

Abstract

(57) [Problem] To provide a structure that is small and has stable optical characteristics, and that can easily manufacture a lens of an optical system without using a mold or the like. An exposure apparatus is constituted by a plurality of light-emitting elements (surface-emitting type LED elements) 11 arranged in a staggered manner, microlenses 3 formed on the respective light-emitting elements 11, and the like. Micro lens 3 on 11
Is formed by the surface tension of the ultraviolet curable resin discharged in a non-contact state with the light emitting element chip 1 by, for example, an ink jet method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for an electrophotographic apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art An example of an electrophotographic apparatus is shown in FIG.

The electrophotographic apparatus shown in FIG. 5 includes a photosensitive drum 101 as an image carrier, a charger 102 disposed opposite to the photosensitive drum 101, and an electrostatic latent image corresponding to original image data. Exposure device 1 formed on body drum 101 surface
03, a developing device 104 for developing an electrostatic latent image on the surface of the photosensitive drum 101 exposed by the exposure device 103 into a visible image with toner, and a transfer roller for transferring the toner image on the photosensitive drum 101 to a sheet P 105, a fixing roller 106 for fixing a toner image on the sheet P by heat, a cleaner 107 for removing toner remaining on the photosensitive drum 101, and the like.

Conventionally, as an exposure apparatus used in such an electrophotographic apparatus, as shown in FIGS. 6 and 7, an LED array 201 in which a plurality of LED chips 211 are arranged on a substrate 210 is used. , LED chip 211
..Self-fox lens 202 arranged on 211
Generally, a structure in which output light from each LED chip 211 is condensed linearly (parallel light) by a self-fox lens 202 and irradiated onto the photosensitive drum 101 (see FIG. 5) is generally used. I am.

Another exposure apparatus is disclosed in Japanese Patent Application Laid-Open No. 8-1563.
Japanese Patent Application Laid-Open No. 20-20520 discloses an optical system that guides output light from an LED array, which is a light source, to a photosensitive drum by using a waveguide and microlenses, and forming the microlenses using an ultraviolet curable resin (LED printer head). ) Is disclosed. In the exposure apparatus described in this publication, a microlens made of an ultraviolet curable resin is integrally formed on an LED chip by using a transparent mold made of a transparent resin such as urethane acrylate resin or glass, or the like.

[0006]

However, according to the exposure apparatus using the self-fox lens, it is necessary to align the LED chip and the self-fox lens with high accuracy. There's a problem. In addition, there is a problem in that periodic light fluctuations occur depending on the position of the self-fox lens, thereby deteriorating print quality.

On the other hand, in the exposure apparatus disclosed in Japanese Patent Application Laid-Open No. 8-156320, it is necessary to bring a transparent mold into contact with the LED chip surface when forming a microlens. Also, in order to avoid damage to the bonding wires, it is necessary to cut out the LED chips after forming the microlenses on the wafer. Further, there is a problem that a transparent mold made of a transparent resin such as urethane acrylate resin or glass or the like has a short life.

The present invention has been made in view of such circumstances, and has a small and stable optical characteristic, and is capable of easily producing an optical lens without using a mold or the like. The purpose is to provide the device.

[0009]

An exposure apparatus according to the present invention is an exposure apparatus used for an electrophotographic apparatus such as a printer or a copier, and includes a plurality of light-emitting elements arranged in a staggered pattern and a light-emitting element on each of the light-emitting elements. With the formed micro lenses, each of the micro lenses is, for example, by an inkjet method,
It is characterized by being formed by the surface tension of the ultraviolet curable resin discharged in a non-contact state toward each light emitting element.

According to the exposure apparatus of the present invention, the microlens is formed integrally with the light emitting element chip by discharging the ultraviolet curable resin in a non-contact state with the light emitting element chip by an ink jet method or the like. There is no problem due to the assembly accuracy described above. In addition, since no mold is used, there is no risk of damage to the electrode wiring pattern and the like.

Further, since the lens shape is obtained by the surface tension of the ultraviolet curable resin, the microlenses can be formed by absorbing irregularities of the electrode wiring pattern and the like. Further, since the light emitting elements are arranged in a staggered arrangement, it is possible to make the lens diameter larger than the dot pitch.

In the exposure apparatus of the present invention, a surface-emitting type LED device is used as a light-emitting device. Surface-emitting LED elements are
There is an advantage that the fabrication of the device is simpler than that of the edge emitting type, and the formation of the microlens on the device is also simplified.

In the exposure apparatus of the present invention, if an optical path length adjusting layer is formed between the light emitting element and the micro lens,
The microlens can be arranged at an appropriate optical position, that is, a position where light from the junction region of the light emitting element (about 5 ° in depth) can be condensed into substantially parallel light.

In the exposure apparatus of the present invention, if a microlens is formed on the surface tension adjusting layer, the wetting angle of the ultraviolet curable resin can be adjusted, and a microlens having desired lens characteristics can be manufactured. can do. The function of the surface tension adjusting layer may be shared by the optical path length adjusting layer.

[0015] In the exposure apparatus of the present invention, the wetting angle of the ultraviolet curable resin is preferably 12 degrees or more, more preferably 4 degrees.
0 degrees or more. When the wetting angle of the ultraviolet curable resin is 12 degrees or more, it is possible to suppress a change in optical characteristics due to a change in the wetting angle.

[0016]

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

FIG. 1 is a plan view schematically showing a main part structure of an embodiment of the present invention. FIG. 2 is a sectional view taken along line AA of FIG.

An LED array chip 1 is used as a light source of the exposure apparatus of this embodiment. In the LED array chip 1, a plurality of surface-emitting type LED elements 11 are formed in a two-row staggered arrangement. Each surface emitting LED element 11
Is formed at a depth of about 5 ° from the surface of the substrate 10. An electrode wiring pattern 12 is connected to each surface-emitting LED element 11.

The surface of the LED array chip 1 (surface emitting type L
The optical path length adjustment layer 2 made of a silicon-based resin is laminated on the surface on which the ED element 11 is formed). Microlenses 3 are formed on the optical path length adjustment layer 2 at positions corresponding to positions directly above the respective surface-emitting type LED elements 11. The optical axis of each macro lens 3 coincides with the center (optical axis) of the surface-emitting LED element 11.

Next, a method of forming the micro lens 3 is shown in FIG.
This will be described with reference to FIG.

First, a predetermined amount of an ultraviolet curable resin is ejected from an ink jet nozzle N and adheres to the surface of the optical path length adjusting layer 2 on the LED array chip 1. At this time,
The outer surface of the ultraviolet curable resin R attached to the surface of the optical path length adjusting layer 2 has a lens shape due to surface tension. This lens-shaped ultraviolet curable resin R is formed in a staggered arrangement as shown in FIG. Then, all the ultraviolet curing resins R on the optical path length adjusting layer 2 are irradiated with ultraviolet rays from an ultraviolet lamp (not shown) or the like to be cured, thereby obtaining the microlenses 3 having the shape shown in FIG. it can.

Here, the wetting angle of the ultraviolet curable resin constituting the microlens 3 is preferably 12 degrees or more. When the wetting angle of the ultraviolet curable resin is 12 degrees or more, as shown in the graph of wetting angle-focal length in FIG.
Changes, the focal length f does not change much, and fluctuations in optical characteristics due to fluctuations in the wetting angle can be suppressed.

As is apparent from the graph of FIG.
If the wetting angle θ is 40 degrees or more, the focal length f shows a substantially constant value. Therefore, it is preferable to set the wetting angle of the ultraviolet curable resin to 40 degrees or more in order to obtain more stable optical characteristics.

According to the above embodiment, the surface-emitting type LED
Since the elements 11 are arranged in a staggered arrangement of two rows, the lens diameter D of the microlens 3 is set to a size (D
= Dot pitch P × √2 + α).

Further, since the optical path length adjusting layer 2 is formed below the microlens 3, the difference in the wetting angle due to different materials such as the electrode wiring pattern 12 can be absorbed, and the microscopic lens having stable optical characteristics can be always obtained. The lens 3 can be obtained.

Further, by providing the optical path length adjusting layer 2, the microlens 3 can be arranged at an appropriate optical position with respect to the surface emitting LED element 11. That is,
Since the bonding region of the surface emitting LED element 11 is formed at a depth of about 5 ° from the surface of the substrate 10, if the microlens 3 is directly formed on the surface of the LED array chip 1, It is difficult to condense the light into an appropriate shape. However, as shown in FIG.
By setting a distance between the ED element 11 and the microlens 3, the light from the surface-emitting type LED element 11 can be condensed into substantially parallel light.

If the surface of the optical path length adjusting layer 2 is coated with a surface tension adjusting layer made of fluorine resin or the like, the wetting angle of the ultraviolet curable resin can be adjusted, and the microlens having the desired lens characteristics can be obtained. 3 can be formed. Further, the function of the surface tension adjusting layer can also be used for the optical path length adjusting layer 2.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, in FIGS.
The dimensions and materials of the D array chip 1, the optical path length adjusting layer 2, and the microlens 3 were set as follows.・ LED array chip 1 dot pitch: P = 1200 dpi (21.2 μm) ・ Optical path length adjustment layer 2 Silicon resin (refractive index 1.5) Film thickness: 75 μm ・ Micro lens 3 UV curable resin (refractive index 1.5) Wetting angle: 50 degrees Lens diameter: D = 35 μm Lens focal length: F = 30 μm (n = 1.5)

[0029]

As described above, according to the present invention,
Micro lenses are integrally formed on the staggered light-emitting elements, so that the output light from the light-emitting elements can be collected in an appropriate state without using a self-FOC range that has problems in light quantity fluctuation and assembly accuracy. can do. Also,
The size of the apparatus can be reduced as compared with the case where the self-Foc range is used.

Further, since the microlenses are formed by the surface tension of the ultraviolet curable resin discharged in a non-contact state with the light emitting element chip, there is no possibility that the electrode wiring pattern or the like is damaged. Further, since the microlenses can be easily manufactured without using a transparent mold or the like, the productivity is good.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a main structure of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory diagram of a method for forming a microlens.

FIG. 4 is a diagram showing a relationship between a wetting angle of an ultraviolet curable resin constituting a microlens and a focal length.

FIG. 5 is a diagram illustrating an example of an electrophotographic apparatus.

FIG. 6 is a cross-sectional view schematically showing a main structure of a conventional exposure apparatus.

FIG. 7 is a sectional view taken along the line BB of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LED array chip 10 Substrate 11 Surface emitting LED element 12 Electrode wiring pattern 2 Optical path length adjustment layer 3 Micro lens 101 Photoconductor drum 102 Charger 103 Exposure device 104 Developing device 105 Transfer roller 106 Fixing roller 107 Cleaner

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/036 (72) Inventor Kiyoshi Tomi 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka (72) Inventor Tadashi Iwamatsu 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka F-term (reference) 2C162 AE28 AE47 FA04 FA17 FA44 5C051 AA02 CA08 DA04 DB02 DB22 DC02 DC07 DD00 5F041 AA47 CA12 CB22 DA45 DA46 DA55 DA57 DA91 EE17 FF13

Claims (6)

[Claims] 1. An exposure apparatus used in an electrophotographic apparatus such as a printer or a copier, comprising: a plurality of light emitting elements arranged in a staggered pattern; and micro lenses formed on the respective light emitting elements. An exposure apparatus, wherein a lens is formed by surface tension of an ultraviolet curable resin discharged in a non-contact state toward each light emitting element. 2. The exposure apparatus according to claim 1, wherein the light emitting device is a surface emitting type LED device. 3. The exposure apparatus according to claim 1, wherein an optical path length adjusting layer is formed between the light emitting element and the microlens. 4. The exposure apparatus according to claim 1, wherein the micro lens is formed on the surface tension adjusting layer. 5. The exposure apparatus according to claim 1, wherein light emitted from the light emitting element and transmitted through the microlens is condensed so as to be substantially parallel light. 6. The exposure apparatus according to claim 1, wherein the wetting angle of the ultraviolet curable resin forming the microlens is 12 degrees or more.