JP3550076B2 - Exposure equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exposure device used for an electrophotographic device such as a printer and a copying machine.
[0002]
[Prior art]
FIG. 5 shows an example of the electrophotographic apparatus.
[0003]
The electrophotographic apparatus shown in FIG. 5 includes a photosensitive drum 101 serving as an image carrier, a charger 102 arranged opposite to the photosensitive drum 101, and a photosensitive drum 101 for transferring an electrostatic latent image corresponding to document image data. An exposure device 103 for forming on the surface, 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 toner image on the photosensitive drum 101 for paper The image forming apparatus mainly includes a transfer roller 105 that transfers the toner image onto the sheet P, a fixing roller 106 that fixes the toner image on the sheet P by heat, and a cleaner 107 that removes the toner remaining on the photosensitive drum 101.
[0004]
Conventionally, as an exposure apparatus used in such an electrophotographic apparatus, an LED array 201 in which a plurality of LED chips 211 are arranged on a substrate 210 as shown in FIGS. The self-focusing lens 202 is arranged on the 211. The output light from each LED chip 211 is condensed linearly (parallel light) by the self-fox lens 202, and the photosensitive drum 101 (see FIG. 5) The structure of irradiating on the top is generally used.
[0005]
As another exposure apparatus, Japanese Patent Application Laid-Open No. 8-156320 discloses an optical system that guides output light from an LED array as a light source to a photosensitive drum by a waveguide and a microlens. (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 using a transparent mold made of a transparent resin such as urethane acrylate resin or glass.
[0006]
[Problems to be solved by the invention]
By the way, according to the exposure apparatus using the self-fox lens, since it is necessary to align the LED chip and the self-fox lens with high accuracy, there is a problem in productivity and equipment cost. In addition, there is a problem in that periodic light fluctuations occur depending on the position of the self-fox lens, and print quality deteriorates.
[0007]
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, and there is a possibility that the electrode wiring pattern may be damaged. 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.
[0008]
The present invention has been made in view of such circumstances, and provides an exposure apparatus which has small and stable optical characteristics and can easily manufacture an optical lens without using a mold or the like. With the goal.
[0009]
[Means for Solving the Problems]
The exposure apparatus of the present invention is an exposure apparatus for an electrophotographic apparatus in which a microlens is combined on a light emitting element, wherein the substrate, a plurality of surface emitting LED elements arranged in a staggered pattern on the substrate, and the surface emitting type An optical path length adjustment layer for adjusting the optical position of the microlens laminated on the formation surface of the LED element, a surface tension adjustment layer for adjusting the wetting angle of the ultraviolet curable resin coated on the surface of the optical path length adjustment layer, A predetermined amount of ultraviolet curable resin is discharged to a position facing each surface emitting LED element on the surface tension adjusting layer surface formed on the optical path length adjusting layer, and a microlens formed by the surface tension of the resin. It is characterized by becoming.
Further, the exposure apparatus of the present invention is an exposure apparatus for an electrophotographic apparatus in which a microlens is combined on a light emitting element, wherein the substrate, a plurality of surface emitting LED elements arranged in a staggered pattern on the substrate, An optical path length adjustment layer for adjusting the optical position of the microlens laminated on the surface on which the light emitting LED element is formed, and a predetermined amount of ultraviolet light at a position on the surface of the optical path length adjustment layer facing each surface emitting LED element. A microlens formed by discharging the cured resin, and formed by the surface tension of the resin, wherein the optical path length adjusting layer also functions as a surface tension adjusting layer for adjusting the wetting angle of the ultraviolet curable resin. Features.

[0010]
According to the exposure apparatus of the present invention, since the ultraviolet curable resin is discharged in a non-contact state to the light emitting element chip by an ink jet method or the like, and the microlenses are formed integrally with the light emitting element chip, such as a self-fox lens There is no problem due to assembly accuracy. Further, since no mold is used, there is no risk of damage to the electrode wiring pattern and the like.
[0011]
Further, since the lens shape is obtained by the surface tension of the ultraviolet curing resin, the microlenses can be formed by absorbing irregularities of the electrode wiring pattern and the like. In addition, since the light emitting elements are arranged in a staggered arrangement, the lens diameter can be made larger than the dot pitch.
[0012]
According to the exposure apparatus of the present invention, since the surface-emitting type LED element is used as the light-emitting element, the manufacture of the element is easier than that of the edge-emitting type, and the formation of the microlens on the element is also easier. There is an advantage that it becomes.
[0013]
According to the exposure apparatus of the present invention, since the forming the optical path length adjusting layer between the light emitting element and the microlens, a microlens proper optical positions, i.e. from the junction region of the light emitting element (a depth of about 5 Å) Can be arranged at a position where the light can be converged into substantially parallel light.
[0014]
According to the exposure apparatus of the present invention, since the microlens is formed on the surface tension adjusting layer coated on the optical path length adjusting layer, it is possible to adjust the wetting angle of the ultraviolet curable resin, A microlens having lens characteristics can be manufactured. 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 ultraviolet curable resin preferably has a wetting angle of 40 degrees or more. 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.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0017]
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.
[0018]
An LED array chip 1 is used as a light source of the exposure apparatus of this example. In the LED array chip 1, a plurality of surface-emitting LED elements 11 are formed in a two-row staggered arrangement. The bonding area of each surface-emitting type 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 of the surface-emitting LED elements 11.
[0019]
An optical path length adjustment layer 2 made of a silicon-based resin is laminated on the surface of the LED array chip 1 (the surface on which the surface-emitting type LED element 11 is formed). Microlenses 3 are formed in the optical path length adjustment layer 2 at positions corresponding to positions directly above the respective surface-emitting LED elements 11. The optical axis of each macro lens 3 coincides with the center (optical axis) of the surface-emitting LED element 11.
[0020]
Next, a method of forming the micro lens 3 will be described with reference to FIG.
[0021]
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 adjustment 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, by irradiating all the ultraviolet curing resins R on the optical path length adjusting layer 2 with ultraviolet rays from an ultraviolet lamp (not shown) or the like, the microlenses 3 having the shape shown in FIG. 2 can be obtained. it can.
[0022]
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 the wetting angle-focal length in FIG. Of the optical characteristics due to the above.
[0023]
Further, as is clear from the graph of FIG. 4, if the wetting angle θ is 40 degrees or more, the focal length f shows a substantially constant value. Therefore, the wetting angle of the ultraviolet curable resin is set to 40 degrees or more. It is preferable to obtain more stable optical characteristics.
[0024]
According to the above embodiment, since the surface-emitting type LED elements 11 are arranged in a staggered arrangement of two rows, the lens diameter D of the microlens 3 is set to a size equal to or larger than the dot pitch (D = dot pitch P × √2 + α). can do.
[0025]
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 microlens 3 having always stable optical characteristics can be obtained. Obtainable.
[0026]
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 type 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. 2, an optical path length adjusting layer 2 is formed on the surface of the LED array chip 1 so that the surface emitting LED element 11 and the micro lens By setting a distance between the light emitting device and the light emitting device 3, the light from the surface-emitting type LED element 11 can be collected into substantially parallel light.
[0027]
Here, in the exposure apparatus of the present invention, the surface of the optical path length adjusting layer 2 is coated with a surface tension adjusting layer made of fluororesin or the like . By forming such a surface tension adjusting layer, the wetting angle of the ultraviolet curable resin can be adjusted, and the microlens 3 having desired lens characteristics can be formed. Further, the function of such a surface tension adjusting layer can be shared by the optical path length adjusting layer 2.
[0028]
【Example】
In this embodiment, the dimensions and materials of the LED array chip 1, the optical path length adjusting layer 2, and the microlenses 3 in FIGS. 1 and 2 are 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]
【The invention's effect】
As described above, according to the present invention, since the microlenses are integrally formed on each of the light-emitting elements arranged in a staggered manner, the light emission can be performed without using a self-FOC range which has a problem in light quantity fluctuation and assembly accuracy. Output light from the element can be collected in an appropriate state. In addition, the size of the apparatus can be reduced as compared with the case where the self-fock range is used.
[0030]
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, 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 part structure of a conventional exposure apparatus.
FIG. 7 is a sectional view taken along 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 Microlens 101 Photoconductor drum 102 Charger 103 Exposure device 104 Developing device 105 Transfer roller 106 Fixing roller 107 Cleaner

Claims (3)

In an exposure apparatus for an electrophotographic apparatus in which a microlens is combined on a light emitting element,
Board and
A plurality of surface-emitting LED elements arranged in a staggered pattern on the substrate,
An optical path length adjustment layer for adjusting the optical position of the microlens laminated on the formation surface of the surface emitting LED element;
A surface tension adjustment layer for adjusting the wetting angle of the ultraviolet curable resin coated on the surface of the optical path length adjustment layer,
A predetermined amount of ultraviolet curable resin is discharged at a position on the surface tension adjusting layer surface formed on the optical path length adjusting layer, which faces each surface emitting LED element, and a microlens formed by the surface tension of the resin.
An exposure apparatus comprising: In an exposure apparatus for an electrophotographic apparatus in which a microlens is combined on a light emitting element,
Board and
A plurality of surface-emitting LED elements arranged in a staggered pattern on the substrate,
An optical path length adjustment layer for adjusting the optical position of the microlens laminated on the surface on which the surface emitting LED element is formed,
A predetermined amount of ultraviolet curable resin is discharged at a position on the surface of the optical path length adjustment layer facing each surface-emitting type LED element, and a microlens formed by surface tension of the resin,
An exposure apparatus, wherein the optical path length adjusting layer also has a function of a surface tension adjusting layer for adjusting the wetting angle of the ultraviolet curable resin . 2. The exposure apparatus according to claim 1, wherein the surface tension adjusting layer is adjusted so that the wetting angle of the ultraviolet curable resin forming the microlens is 40 degrees or more.

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