JP2007253375A - Light exposing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light exposing apparatus with a long life capable of focusing into a clear image while light power is held sufficiently largely. <P>SOLUTION: The light exposing apparatus 10 comprises a light emitting panel 21, a first gap filling layer 23, a light transmitting member 27, a second gap filling layer 25 and a light focusing lens array 24. The first gap filling layer 23 fills a gap between the light emitting panel 21 and the light transmitting member 27, and the second gap filling layer 25 fills a gap between the light transmitting member 27 and the light focusing lens array 24. Refractive indexes of the first gap filling layer 23 and the second gap filling layer 25 are ≥1.47 and ≤1.511. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an exposure apparatus including a plurality of light emitting elements and an image forming apparatus using the exposure apparatus.

2. Description of the Related Art Conventionally, there has been proposed an image forming apparatus that forms a latent image (electrostatic latent image) by selectively exposing an image forming surface of an image carrier such as a pre-charged photoconductor drum with a number of light emitting elements. As the light emitting element, for example, an EL (Electro Luminescent) element can be adopted. Patent Document 1 discloses a configuration in which a converging lens array is interposed between a light emitting element and an image carrier. The converging lens array is, for example, SLA (Selfoc Lens Array) available from Nippon Sheet Glass Co., Ltd. (Selfoc \ SELFOC is a registered trademark of Nippon Sheet Glass Co., Ltd.). According to this configuration, the utilization efficiency of light from the light emitting element is improved.
JP 2002-248803 A (FIG. 7)

By the way, in order to form a high-definition and high-quality image (latent image), it is necessary to keep the intensity of light irradiated to the image forming surface (hereinafter referred to as “optical power”) sufficiently large. However,
In the configuration using an EL element (particularly, an organic EL element) as the light emitting element, the optical power becomes small, and even if the configuration of Patent Document 1 is adopted, it is difficult to keep the optical power sufficiently high. In order to increase the optical power, it is conceivable that the EL element emits light with sufficiently high luminance. However, this leads to a shortened life of the EL element and consequently a shorter life of the exposure apparatus. In order to increase the optical power, it is conceivable to increase the size of the EL element (the area of the light emitting surface) to sufficiently increase the amount of emitted light for each EL element. However, in the above-described conventional configuration, the ratio of the image formation size to the size of the EL element (hereinafter referred to as “image formation size ratio”) is large. It will be significantly larger. This leads to the formation of a blurred latent image.
Accordingly, the present invention provides a long-life exposure apparatus capable of forming a clear image while maintaining a sufficiently high optical power, and an image forming apparatus using the exposure apparatus.

An exposure apparatus according to the present invention includes a plurality of light emitting elements arranged along one direction and a light-transmitting plate material, and a light emitting device that emits light from the plurality of light emitting elements through the plate material And a plurality of gradient index lenses capable of forming an erect real image by transmitting a part of the light emitted from the light emitting device, and an image formed by the plurality of gradient index lenses is formed. A converging lens array constituting one continuous image; a light-transmitting translucent member interposed between the light emitting device and the converging lens array; and a refractive index of 1.47 to 1.511. A light-transmitting material that fills one or both of the gap (first gap) between the light-emitting device and the translucent member and the gap (second gap) between the translucent member and the converging lens array. A gap filling layer.
Here, the “light emitting element” means an element in which a solid light emitting layer that emits light upon receiving electric energy is sandwiched between electrodes. As the light emitting element, OLED, inorganic EL element, inorganic LED (Li
ght Emitting Diode). OLED is organic EL (Electro Lumin
Also called escent element. That is, the OLED and the inorganic EL element are both types of EL elements. In this specification, an “EL element” refers to an electric field excitation type element that emits light through excitation of excitons. On the other hand, both inorganic LEDs and OLEDs are types of LEDs. In this specification, “LED” refers to a carrier injection type device that emits light through recombination of electrons and holes. The “plate material” is a concept including a light source substrate on which a plurality of light emitting elements are formed and a sealing substrate for sealing the plurality of light emitting elements. The “refractive index” of the layer filling the gap means the refractive index of the material forming the portion in the gap. Further, the gap filling layer includes the first gap and the second gap.
When the gap is filled, the “refractive index” means the refractive index of the first layer filling the first gap and the refractive index of the second layer filling the second gap. The refractive index of the first layer and the refractive index of the second layer may be the same or different. The converging lens array is a kind of gradient index lens array, and an example thereof is SLA.
According to the above exposure apparatus, the ratio of the light that enters the converging lens array out of the light emitted from the light emitting apparatus is obtained by interposing the light transmitting member between the light emitting apparatus and the converging lens array. It is possible to increase. In addition, since one or both of the first gap between the translucent member and the light emitting device and the second gap between the translucent member and the converging lens array are filled with the gap filling layer, the first gap is filled. A form in which both the gap and the second gap are filled with air, a form in which the first gap is not present and the second gap is filled with air, and a second gap is not present in the first gap The reflection loss of light from the light emitting element can be reduced as compared with a form in which is filled. Thus, loss of light from the light-emitting element can be reduced. The extent of this reduction is
The form in which both are filled is larger than the form in which one is filled.
Further, according to the above exposure apparatus, since the refractive index of the gap filling layer is 1.47 or more and 1.511 or less, the imaging size ratio becomes sufficiently small. Therefore, a sufficiently clear image can be formed while increasing the size of the light emitting element. As is clear from this, according to the above exposure apparatus, the light power can be kept sufficiently large without causing the light emitting element to emit light with sufficiently high luminance.
As described above, according to the above-described exposure apparatus, it is possible to form a clear image and to achieve a long life while keeping the optical power sufficiently large.

Another exposure apparatus according to the present invention includes a plurality of light emitting elements arranged in one direction and a light-transmitting plate, and light from the plurality of light emitting elements is transmitted through the plate and emitted. A light emitting device;
A plurality of gradient index lenses capable of forming an erect real image by transmitting a part of the light emitted from the light emitting device are arranged, and one continuous image is formed by the plurality of gradient index lenses. A converging lens array forming the image, a light-transmitting translucent member interposed between the light emitting device and the converging lens array, and a refractive index lower than that of the plate member or the translucent member A light transmissive gap filling layer filling one or both of the gap between the light emitting device and the light transmissive member and the gap between the light transmissive member and the converging lens array.
According to this exposure apparatus, the translucent member is interposed between the light emitting device and the converging lens array, the first gap between the translucent member and the light emitting device, and the translucent member and the converging property. Since one or both of the second gaps between the lens array and the lens array are filled with the gap filling layer, the loss of light from the light emitting element can be reduced. Further, according to this exposure apparatus, since the refractive index of the gap filling layer is lower than that of the plate material or the translucent member, the imaging size ratio is sufficiently small, so that the light emitting element does not emit light with sufficiently high luminance, The optical power can be kept sufficiently large. Therefore, according to this exposure apparatus, it is possible to form a clear image and to achieve a long life while keeping the optical power sufficiently large.

In each of the above exposure apparatuses, the light transmitting member has a refractive index of 1.515 or more and less than 2.
Alternatively, the refractive index of the plate material may be 1.515 or more and less than 2, or both refractive indexes may be 1.515 or more and less than 2. According to each of these exposure apparatuses, the above-described effects can be obtained more reliably. This is because the refractive index of one or both of the translucent member and the plate (light source substrate) is 1.515 based on the results of the experiment described below.
If the refractive index of the gap filling layer is 1.47 or more and 1.511 or less or lower than the plate material or the translucent member, the imaging size ratio is estimated to be remarkably small. This is because it has been found that when the refractive index of one or both of the optical member and the plate member is 2 or more, there is too much light loss due to interface reflection and the optical power cannot be kept sufficiently large.

In each of the above exposure apparatuses, the gap filling layer may be formed from an adhesive. In the exposure apparatus of this embodiment, the gap filling layer functions as a bonding layer that bonds the light emitting device (plate material) and the translucent member by bonding, so that the configuration is simplified and manufacture is facilitated.

In each of the above exposure apparatuses, the surface of the gradient index lens that emits transmitted light may be subjected to an antireflection treatment. According to this aspect, since the reflection of light on the surface is suppressed, the utilization efficiency of light from the light emitting element is further improved. Examples of the antireflection treatment include AR (Anti Reflection) coating and moss eye (Moth Eye) structuring.

The present invention also provides an image carrier, a charger for charging the image carrier, and a latent image is formed by irradiating the charged surface of the image carrier with light from the exposure apparatus. There is provided an image forming apparatus comprising: each exposure device; and a developing unit that forms a visible image by attaching toner to the latent image, and transferring the visible image to another object. According to this image forming apparatus, since each of the exposure apparatuses described above is used, availability is improved, and a high-definition image with high resolution can be formed.

Embodiments of the present invention will be described with reference to the drawings. In the following drawings,
The ratio of the dimensions of each part is made different from the actual one for convenience.

<Exposure device>
FIG. 1 is a perspective view showing an outline of an exposure apparatus 10 according to an embodiment of the present invention. An exposure apparatus 10 illustrated in the figure includes a photosensitive drum 11 in an image forming apparatus using an electrophotographic system.
It is used as a line-type optical head for writing a latent image by irradiating light to the outer peripheral surface (image forming surface) of 0.

The exposure apparatus 10 includes a light emitting panel (light emitting apparatus) 21 that emits light from a light source, a converging lens array 24 interposed between the light emitting panel 21 and the photosensitive drum 110, and the light emitting panel 2.
1 and the converging lens array 24, the first gap filling layer 23 interposed between the light emitting panel 21 and the translucent member 27, the translucent member 27 and the converging lens array. 24
And a second gap filling layer 25 interposed therebetween.

FIG. 2 is a plan view of the light emitting panel 21. As shown in FIG. 1 and FIG.
1 includes a plurality of light emitting elements 22 serving as light sources, and a light source substrate (plate material) 211 on which the plurality of light emitting elements 22 are formed. The light source substrate 211 is a long plate material having a thickness of about 0.5 mm formed from a light-transmitting material such as glass or plastic.
The posture is fixed substantially parallel to the rotation axis 10. The refractive index of the light source substrate 211 (the material forming the light source substrate 211) is 1.515 or more and less than 2. This is because the effect of the light source substrate 211 with a refractive index of 1.515 or more has been confirmed by the experiment described later, and if the refractive index of the light source substrate 211 is less than 2, the loss of light due to interface reflection is sufficient. It depends on being able to suppress it little.

The plurality of light emitting elements 22 are arranged on one surface (front surface) of the two widest surfaces (front surface and back surface) of the light source substrate 211 in the longitudinal direction of the light source substrate 211 (the direction of the rotation axis of the photosensitive drum 110). Are arranged in a line along. This is an example, and for example, there may be two or more rows, or a plurality of rows and staggered shapes. The outer shape of each light emitting element 22 when viewed from the direction perpendicular to the light source substrate 211 is a substantially circular shape having a diameter of about 40 μm. This is an example, and may be, for example, a substantially elliptical shape or a substantially rectangular shape.

The light emitting element 22 is an OLED, and as shown in FIG. 4, the first electrodes 22 facing each other.
The light emitting layer 224 is interposed in the gap between the first electrode 2 and the second electrode 222. Light emitting layer 224
Is a film body made of an organic EL material, and emits light with luminance according to a potential difference between the first electrode 221 and the second electrode 222 (in other words, a current flowing between the first electrode 221 and the second electrode 222). The first electrode 221 positioned on the light source substrate 211 side when viewed from the light emitting layer 224 is made of ITO (In
dium tin oxide) and the like. On the other hand, the second electrode 22
2 is formed of a conductive material such as aluminum or silver.

In addition, the light emitting panel 21 is a sealing substrate 2 that seals a plurality of light emitting elements 22 and protects them from the outside air.
Twelve. The sealing substrate 212 is a long member formed of a material such as glass, plastic, or metal, and is joined to the light source substrate 211 so that the longitudinal directions thereof coincide with each other.
A closed space is defined on the surface. The plurality of light emitting elements 22 exist in this closed space. Note that it is also possible to employ sealing in a form that does not use a sealing substrate (for example, sealing with a film).

In the present embodiment, the bottom emission type light-emitting panel 21 in which light from the plurality of light-emitting elements 22 is transmitted through the light source substrate 211 and emitted is used. It is also possible to employ a top emission type light-emitting panel in which light from the element 22 passes through the sealing substrate and becomes emitted light. In this case, in the present embodiment, the light source substrate 211
The restriction of the refractive index imposed on the substrate is imposed on the sealing substrate (plate material).

The translucent member 27 in FIG. 1 is a long member formed of a light transmissive material such as glass or plastic, and is joined to the light source substrate 211 with the longitudinal direction thereof aligned. However, there is a gap having a substantially uniform height between the light source substrate 211 and the translucent member 27. Hereinafter, this gap is referred to as a “first gap”. The refractive index of the translucent member 27 (the material forming it) is 1.515 or more and less than 2. This is because the effect of the translucent member 27 having a refractive index of 1.515 or more has been confirmed by experiments described later, and if the refractive index of the translucent member 27 is less than 2, light loss due to interface reflection is reduced. It depends on being able to keep it small enough.

The first gap is filled with the first gap filling layer 23. The first gap filling layer 23 is a layered member formed from a light-transmitting adhesive, and is in close contact with the light source substrate 211 and the light-transmitting member 27 to join them together. The first gap filling layer 23 can be formed, for example, by filling the first gap with a light-transmitting adhesive and solidifying it. The refractive index of the first gap filling layer 23 (adhesive forming the layer) is 1.47 or more and 1.511 or less. This has a refractive index of 1.51
This is because the effects of the five or more translucent members 27 have been confirmed by experiments described later.

FIG. 3 is a perspective view showing the configuration of the converging lens array 24. As shown in the figure, the converging lens array 24 includes a plurality of gradient index lenses (Gradient Index lens: connecting real images).
GRIN lens) 241 is a long member. The converging lens array 24, the working distance on the object side (L ₀₎ and working distance on the image side (L ₁₎ are determined. L ₀ = L ₁ L
₀ and L ₁ will be described later.

The refractive index distribution type lens 241 transmits a part of the light emitted from the light emitting panel 21 and can form an erect real image of the image on the light emitting panel 21 on the image plane, and has a plurality of refractive index distribution type lenses. 241
Is such that the image formed by these gradient index lenses 241 forms one continuous image.
Two rows and staggered shapes along the longitudinal direction of the converging lens array 24 (the direction of the rotation axis of the photosensitive drum 110) with each central axis (optical axis) oriented in a direction substantially perpendicular to the light source substrate 211 Is arranged. This is an example, and may be, for example, a single row or three or more rows.

The gradient index lens 241 is a light-transmitting member formed in a substantially cylindrical shape with a height of about 4.3 mm, and has a high refractive index at the central axis (optical axis) and moves away from the central axis toward the periphery. The refractive index is distributed in the cross section so that the refractive index becomes lower. In the gradient index lens 241 in the present embodiment, the refractive index at the central axis is 1.64 and the refractive index at the periphery is 1.31.
It is. By allowing the emitted light from the light emitting panel 21 to pass through this type of converging lens array 24, an erect image with respect to the image on the light emitting panel 21 is formed on the outer peripheral surface of the photosensitive drum 110. An example of the converging lens array 24 is SLA.

The end surface (light emitting surface) on the photosensitive drum 110 side of each gradient index lens 241 is subjected to antireflection processing for suppressing interface reflection of light. As this antireflection treatment, AR
(Anti Reflection) coating and Moth Eye structuring.

The converging lens array 24 is joined to the translucent member 27 so that the longitudinal directions thereof coincide with each other. However, there is a substantially uniform gap between the converging lens array 24 and the translucent member 27. Hereinafter, this gap is referred to as a “second gap”. The second gap is filled with the second gap filling layer 25. The second gap filling layer 25 is a layered member formed from a light-transmitting adhesive,
The converging lens array 24 and the translucent member 27 are in close contact with each other and are joined together. The second gap filling layer 25 can be formed, for example, by filling the second gap with a light-transmitting adhesive and solidifying it. The adhesive forming the second gap filling layer 25 is the same as that forming the first gap filling layer 23.

FIG. 4 is a cross-sectional view showing the configuration of each part paying attention to the optical path of the light emitted from the point P in the light emitting layer 224 of one light emitting element 22 that passes through the gradient index lens 241. As shown in this figure, a part of the light emitted from the point P consists of the first electrode 221, the first gap filling layer 23, the translucent member 27, the second gap filling layer 25, and the converging lens array 24 (a plurality of converging lens arrays 24). The light passes through the gradient index lens 241) in order and reaches the outer peripheral surface of the photosensitive drum 110. Similarly, part of light emitted from other points in the light emitting layer 224 also reaches the outer peripheral surface of the photosensitive drum 110. By these reaching lights, an erect image of an image appearing on the light emitting panel 21 due to light emission of the light emitting element 22 is formed. This upright image is called a “spot image”. Hereinafter, the diameter of the spot image is referred to as a spot diameter R. Similarly to the above, spot images are formed on the other light emitting elements 22 that emit light. Thus, a plurality of light emitting elements 2 on the outer peripheral surface of the photosensitive drum 110.
One continuous image having a spot image as a constituent element is formed in a line-shaped region facing 2. This image is an erect image of an image that appears on the light-emitting panel 21 by light emission / non-light emission of the plurality of light-emitting elements 22 within a unit time, and becomes a latent image.

In order to guide the above action, the arrangement of the light emitting panel 21 and the converging lens array 24 is determined according to L ₀ which is the working distance of the converging lens array 24 on the object side. L ₀ basically coincides with the distance between the light source and the gradient index lens 241 that enables optimal image formation. Optimum imaging ideally means that the latent image becomes an erecting equal-magnification image and the spot image becomes an erecting equal-magnification image. However, L ₀ is determined on the assumption that light emitted from the light source and incident on the gradient index lens 241 passes only in the air. Therefore, the exposure apparatus 10
As described above, in a configuration in which a substance having a refractive index higher than that of air is interposed between the light source and the gradient index lens 241, the interval at which optimal image formation is possible is longer than L ₀ . Therefore, as shown in FIG. 4, the distance d between the converging lens array 24 and the light emitting element 22 is longer than L _0.

In order to guide the above action, it is necessary to determine the arrangement of the exposure apparatus 10 and the photosensitive drum 110 according to L ₁ that is the working distance on the image side of the converging lens array 24. L ₁ basically corresponds to the distance between the image plane and the gradient index lens 241 that enables optimal image formation.
L ₁ and also, the light that reaches the the photosensitive drum 110 emitted from the gradient index lens 241 is defined on the premise that passes only through the air.

As shown in FIG. 4, the light from the light emitting panel 21 travels in the light transmissive member 27 while diverging at an angle θ. Since the refractive index of the translucent member 27 is larger than the refractive index of air, the angle θ is
In a configuration in which a layer of air is present instead of the translucent member 27, the angle is smaller than the divergence angle of light traveling in the layer. Therefore, in the exposure apparatus 10, the incident angle of light incident on the gradient index lens 241 from the light emitting panel 21 becomes small, and less light is lost due to reflection on the light incident surface of the gradient index lens 241.
Further, according to the exposure apparatus 10, the first gap between the translucent member 27 and the light emitting panel 21 is the first.
The gap filling layer 23 causes the second gap between the translucent member 27 and the converging lens array 24 to be second.
Since the gap is filled with the gap filling layer 25, not only the first gap and the second gap are filled with air, but also the first gap and the second gap are filled with air. Compared to the above, less light is lost due to interface reflection.
As described above, according to the exposure apparatus 10, it is possible to increase the proportion of the light entering the converging lens array 24 out of the light emitted from the light emitting panel 21.
In addition, since the light exit surface of each gradient index lens 241 has been subjected to antireflection treatment,
Compared to a form in which this treatment is not performed, less light is lost due to interface reflection.
Therefore, according to the exposure apparatus 10, the loss of light from the light emitting panel 21 can be sufficiently reduced.

Further, according to the above-described exposure apparatus, since the refractive index of the first gap filling layer 23 and the second gap filling layer 25 is 1.47 or more and 1.511 or less, the imaging size ratio (each of each light emitting element 22) The ratio of the spot diameter R to the diameter of the light emitting element 22) is sufficiently small. This means
This is supported by an experiment in which the light emitting element 22 emits light and the area of the spot image is measured by microscopic analysis. In this experiment, the above measurement was repeated by changing the refractive indexes of the first gap filling layer 23 and the second gap filling layer 25.

FIG. 5 is a table summarizing the measurement data of the above experiment, and FIG. 6 is a line graph thereof. These measurement data indicate that the refractive indexes of the light source substrate 211 and the translucent member 27 are both 1.515.
6 (dotted line in FIG. 6) and 1.58 (solid line in FIG. 6) were obtained by changing both the refractive indexes of the first gap filling layer 23 and the second gap filling layer 25. is there. Measurement data when the refractive index of the first gap filling layer 23 and the second gap filling layer 25 is 1 is obtained by using an air layer instead of the first gap filling layer 23 and the second gap filling layer 25. ing. The light source substrate 211 and the translucent member 27 having a refractive index of 1.515 can be formed using, for example, glass (trade name “BK7”) provided by Schott.

FIG. 7 is a table summarizing other measurement data of the above-described experiment, and FIG. 8 is a line graph thereof. These measurement data are obtained when the refractive index of the light transmitting substrate 27 is 1.58 (solid line in FIG. 8) and 1.663 (see FIG. 8), the refractive index of each of the first gap filling layer 23 and the second gap filling layer 25 is changed. The refractive index of the first gap filling layer 23 and the second gap filling layer 25 is 1
The method for acquiring measurement data in this case is as described above. The refractive index is 1.663.
The translucent member 27 can be formed using, for example, glass (trade name “BAFN11”) provided by Schott.

As shown in FIGS. 5 to 8, the spot diameter R (the area of the spot image) is determined when the refractive indexes of the first gap filling layer 23 and the second gap filling layer 25 are 1.476 or more and 1.5077 or less. Remarkably small. From these figures, it can be estimated that the spot diameter R is remarkably small when the refractive index of the first gap filling layer 23 and the second gap filling layer 25 is 1.47 or more and 1.511 or less. Further, from these figures, the refractive index ranges of the first gap filling layer 23 and the second gap filling layer 25 in which the spot diameter R is remarkably reduced are also in the refractive index of the light source substrate 211.
It can be estimated that the refractive index of the translucent member 27 does not depend on the difference in refractive index between the light source substrate 211 and the translucent member 27.

In the above experiment, the refractive index of the light source substrate and the refractive index of the translucent member are both 1.515.
That's it. Accordingly, from FIG. 5 to FIG. 8, the spot diameter R indicates that the refractive index of the first gap filling layer 23 and the second gap filling layer 25 is one of the refractive index of the light source substrate 211 and the refractive index of the translucent member 27. Alternatively, it can be estimated that when the value is lower than both, it is significantly reduced. The present embodiment may be modified based on this estimation, and the refractive indexes of the first gap filling layer 23 and the second gap filling layer 25 may be outside the above range (from 1.47 to 1.511).

Regardless of which of the above estimations, according to the exposure apparatus 10, the imaging size ratio regarding each light emitting element 22 is still sufficiently small. In the above experiment,
The thicknesses of the first gap filling layer 23 and the second gap filling layer 25 are both fixed to 10 μm, and the distance d between each light emitting element 22 and the converging lens array 24 is also fixed. Then, when changing the refractive index of the first gap filling layer 23 or the refractive index of the second gap filling layer 25, the translucent member so that the latent image becomes an equal-magnification image of the image appearing on the light emitting panel 21. The thickness of 27 was adjusted. But,
These are examples, and for example, it is known that the above range (1.47 or more and 1.511 or less) does not depend on the thicknesses of the first gap filling layer 23 and the second gap filling layer 25 or the difference therebetween.

As described above, according to the present embodiment, since the image formation size ratio is sufficiently small for each light emitting element 22, the light emitting element is used to sufficiently increase the optical power (the intensity of the irradiation light on the outer peripheral surface). Even if the size of 22 is increased, the spot diameter R becomes sufficiently small, and a clear latent image can be obtained. That is, the light power can be kept sufficiently large without causing the light emitting element 22 to emit light with sufficiently high luminance. As described above, according to the exposure apparatus 10, it is possible to form a clear image and achieve a long life while keeping the optical power sufficiently large.

The first gap filling layer 23 is not only a light-transmitting layer that transmits light emitted from the light-emitting panel 21, but also serves as a bonding layer that bonds the light source substrate 211 and the light-transmitting member 27 by adhesion. . Similarly, the second gap filling layer 25 also serves as a light transmitting layer and a bonding layer. Therefore,
The exposure apparatus 10 has a simple configuration and is easy to manufacture. Of course, one or both of the first gap filling layer 23 and the second gap filling layer 25 may not serve as the light-transmitting layer and the bonding layer. An example of a material for forming such a gap filling layer is matching oil.

Items that can be estimated from FIGS. 5 to 8 are not limited to the items described above. For example, if the refractive index of the translucent member is 1.515 or more and 1.663 or less, it can be estimated that the spot diameter R is remarkably reduced when the refractive index of the gap filling layer is in the above-described range. . For example, if the refractive index of the light source substrate is 1.515 or more and 1.58 or less, it can be estimated that the spot diameter R is remarkably reduced when the refractive index of the gap filling layer is in the above-mentioned range. . Further, for example, when the refractive index of the gap filling layer is in the above-described range, it can be estimated that the extent to which the spot diameter R is small increases as the refractive index of one or both of the translucent member and the light source substrate increases. is there. From these matters and the fact that the loss of light due to interface reflection is sufficiently reduced because the refractive indexes of the light source substrate 211 and the light transmissive member 27 are less than 2, the light transmissive member and the light source substrate If the refractive index of one or both is 1.515 or more and less than 2, it can be estimated that the spot diameter R is remarkably reduced when the refractive index of the gap filling layer is within the above-mentioned range.

The present embodiment may be modified based on these matters. For example, the refractive index of the translucent member may be limited to 1.515 or more and less than 2, or may be limited to 1.515 or more and 1.663 or less. Further, for example, the refractive index of the light source substrate may be limited to 1.515 or more and less than 2, or may be limited to 1.515 or more and 1.58 or less. For example, both the refractive index of the translucent member and the refractive index of the light source substrate may be limited to 1.515 or more and less than 2, or may be limited to 1.515 or more and less than 1.58.

For example, the refractive index of the first gap filling layer 23 may be different from the refractive index of the second gap filling layer 25 by modifying the present embodiment. Further, for example, there is a configuration in which there is no first gap in which the light emitting panel 21 and the translucent member 27 are directly joined, and a configuration in which there is no second gap in which the translucent member 27 and the converging lens array 24 are directly joined. Be considered. In other words, the first gap filling layer 23 does not exist in the former case, and the second gap filling layer 25 does not exist in the latter case. Further, for example, in a configuration in which the first gap and the second gap exist, a configuration in which one of the first gap filling layer 23 and the second gap filling layer 25 is omitted is considered. For example, as a light emitting element of a light source,
An inorganic EL element or an inorganic LED may be provided. That is, as the light-emitting element of the light source, any element in which a solid light-emitting layer that emits light upon receiving electric energy is sandwiched between electrodes can be employed.

<Image forming apparatus>
FIG. 9 is a longitudinal sectional view of the image forming apparatus according to the embodiment of the present invention. This image forming apparatus is a tandem type full-color image forming apparatus using a belt intermediate transfer body system.

In this image forming apparatus, four optical heads 10K, 10C, 10M, and 10Y having the same configuration are used.
Are four photosensitive drums (image carriers) 110K, 110C, 110M, which have the same configuration.
110Y is disposed at the exposure position. Optical heads 10K, 10C, 10M, 10
Y is an exposure apparatus according to the above-described exposure apparatus 10 or a modification thereof.

As shown in FIG. 9, this image forming apparatus is provided with a driving roller 121 and a driven roller 122, and an endless intermediate transfer belt 120 is wound around these rollers 121 and 122, as indicated by arrows. Thus, the periphery of the rollers 121 and 122 is rotated. Although not shown,
A tension applying unit such as a tension roller that applies tension to the intermediate transfer belt 120 may be provided.

Around the intermediate transfer belt 120, photosensitive drums 110K, 110C, 110M, and 110Y having photosensitive layers on four outer peripheral surfaces are arranged at predetermined intervals. Subscript K
, C, M, and Y mean that they are used to form visible images of black, cyan, magenta, and yellow, respectively. The same applies to other members. Photosensitive drums 110K and 11
0C, 110M, and 110Y are rotationally driven in synchronization with the driving of the intermediate transfer belt 120.

Around each photosensitive drum 110 (K, C, M, Y), a corona charger 111 (K, C,
M, Y), an optical head 10 (K, C, M, Y), and a developing device 114 (K, C, M, Y) are arranged. Corona chargers 111 (K, C, M, Y) have corresponding photosensitive drums 110.
The outer peripheral surface of (K, C, M, Y) is uniformly charged. The optical head 10 (K, C, M, Y)
An electrostatic latent image is written on the charged outer peripheral surface of the photosensitive drum. Each optical head 10 (K, C,
M, Y) indicates that the arrangement direction of the plurality of OLED elements 14 is the photosensitive drum 110 (K, C, M, Y).
) Along the bus (in the main scanning direction). The electrostatic latent image is written by irradiating the photosensitive drum with light from the plurality of OLED elements 14. Developer 114 (K
, C, M, and Y) form a visible image, ie, a visible image, on the photosensitive drum by attaching toner as a developer to the electrostatic latent image.

Black, cyan, magenta, and black formed by such a four-color monochromatic image forming station
The yellow visible images are sequentially primary-transferred onto the intermediate transfer belt 120 to be superimposed on the intermediate transfer belt 120, and as a result, a full-color visible image is obtained. Inside the intermediate transfer belt 120, four primary transfer corotrons (transfer units) 112 (K, C, M, Y) are provided.
Is arranged. The primary transfer corotron 112 (K, C, M, Y) is connected to the photosensitive drum 11.
0 (K, C, M, Y) are arranged in the vicinity of the photosensitive drum 110 (K, C,
The visible image is electrostatically attracted from (M, Y) to transfer the visible image to the intermediate transfer belt 120 passing between the photosensitive drum and the primary transfer corotron.

A sheet 102 as an object on which an image is finally formed is fed one by one from the sheet feeding cassette 101 by the pickup roller 103, and between the intermediate transfer belt 120 and the secondary transfer roller 126 in contact with the driving roller 121. Sent to the nip. The full-color visible image on the intermediate transfer belt 120 is secondarily transferred to one side of the sheet 102 by the secondary transfer roller 126 and fixed on the sheet 102 by passing through a fixing roller pair 127 as a fixing unit. . Thereafter, the sheet 102 is discharged onto a paper discharge cassette formed on the upper part of the apparatus by a paper discharge roller pair 128.

FIG. 10 is a longitudinal sectional view of another image forming apparatus according to the embodiment of the present invention. This image forming apparatus is a rotary developing type full-color image forming apparatus using a belt intermediate transfer body system. In the image forming apparatus shown in FIG. 10, a corona charger 168, a rotary developing unit 161, an optical head 167, and an intermediate transfer belt 169 are provided around a photosensitive drum (image carrier) 165.

The corona charger 168 uniformly charges the outer peripheral surface of the photosensitive drum 165. Optical head 1
67 writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum 165. Optical head 1
Reference numeral 67 denotes an exposure apparatus according to the exposure apparatus 10 or a modification thereof, and is installed so that the arrangement direction of the plurality of light emitting elements 14 is along the bus line (main scanning direction) of the photosensitive drum 165. The electrostatic latent image is written by irradiating the photosensitive drum with light by the plurality of light emitting elements 14 described above.

The developing unit 161 includes four developing units 163Y, 163C, 163M, and 163K.
The drums are arranged at an angular interval of ° and can be rotated counterclockwise about the shaft 161a. The developing units 163Y, 163C, 163M, and 163K supply yellow, cyan, magenta, and black toners to the photosensitive drum 165, respectively, and attach the toner as a developer to the electrostatic latent image, thereby the photosensitive drum 165. A visible image, that is, a visible image is formed.

The endless intermediate transfer belt 169 is wound around a driving roller 170a, a driven roller 170b, a primary transfer roller 166, and a tension roller, and is rotated around these rollers in a direction indicated by an arrow. The primary transfer roller 166 transfers the visible image to the intermediate transfer belt 169 that passes between the photosensitive drum and the primary transfer roller 166 by electrostatically attracting the visible image from the photosensitive drum 165.

Specifically, in the first rotation of the photosensitive drum 165, an electrostatic latent image for a yellow (Y) image is written by the exposure head 167, and a developed image of the same color is formed by the developing unit 163Y.
Further, the image is transferred to the intermediate transfer belt 169. Further, in the next rotation, an electrostatic latent image for a cyan (C) image is written by the exposure head 167 and a developed image of the same color is formed by the developing device 163C, and an intermediate transfer is performed so as to overlap the yellow developed image. Transferred to the belt 169. Then, during the four rotations of the photosensitive drum 9, the yellow, cyan, magenta, and black visible images are sequentially superimposed on the intermediate transfer belt 169. As a result, a full-color visible image is formed on the transfer belt 169. It is formed. When images are finally formed on both sides of a sheet as an object on which an image is to be formed, the same color visible images of the front and back surfaces are transferred to the intermediate transfer belt 169, and then the front and back surfaces are transferred to the intermediate transfer belt 169. A full-color visible image is obtained on the intermediate transfer belt 169 by transferring the next-color visible image.

The image forming apparatus is provided with a sheet conveyance path 174 through which a sheet passes. The sheets are picked up one by one from the paper feed cassette 178 by the pick-up roller 179, advanced through the sheet transport path 174 by the transport roller, and between the intermediate transfer belt 169 and the secondary transfer roller 171 in contact with the drive roller 170a. Pass through the nip. The secondary transfer roller 171 transfers the developed image to one side of the sheet by electrostatically attracting a full-color developed image from the intermediate transfer belt 169 collectively. The secondary transfer roller 171 can be moved closer to and away from the intermediate transfer belt 169 by a clutch (not shown). And
The secondary transfer roller 171 moves the intermediate transfer belt 169 when transferring a full-color visible image onto the sheet.
And is separated from the secondary transfer roller 171 while the visible image is superimposed on the intermediate transfer belt 169.

The sheet on which the image has been transferred as described above is conveyed to the fixing device 172 and is passed between the heating roller 172a and the pressure roller 172b of the fixing device 172, whereby the visible image on the sheet is fixed. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the direction of arrow F. In the case of double-sided printing, after most of the sheet passes through the paper discharge roller pair 176, the paper discharge roller pair 176 is rotated in the reverse direction.
75. Then, the visible image is transferred to the other surface of the sheet by the secondary transfer roller 171, the fixing process is performed again by the fixing device 172, and then the sheet is discharged by the discharge roller pair 176.

Each of the above-described image forming apparatuses uses a long-life exposure apparatus capable of forming a clear image while maintaining a sufficiently large optical power as an optical head, so that availability is improved and high resolution and high quality are achieved. An image can be formed. As described above, the image forming apparatus to which the exposure apparatus 10 or the exposure apparatus according to the modification thereof can be applied has been exemplified. However, the image forming apparatus can be applied to other electrophotographic image forming apparatuses. Are within the scope of the present invention. For example,
The present invention can also be applied to an image forming apparatus that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, and an image forming apparatus that forms a monochrome image.

1 is a perspective view showing an outline of an exposure apparatus 10 according to an embodiment of the present invention. 2 is a plan view of a light-emitting panel 21 constituting the exposure apparatus 10. FIG. 2 is a perspective view showing a configuration of a converging lens array 24 that constitutes the exposure apparatus 10. FIG. 2 is a cross-sectional view showing a configuration of each part of the exposure apparatus 10. FIG. It is the table | surface which put together the measurement data obtained by experiment. 6 is a line graph corresponding to the table of FIG. It is the table | surface which summarized another measurement data obtained by experiment. It is a line graph corresponding to the table of FIG. 1 is a longitudinal sectional view of an image forming apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view of another image forming apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 22 ... Light emitting element, 21 ... Light emission panel (light emitting device), 211 ... Light source substrate, 212 ... Sealing substrate, 23 ... First gap filling layer, 24 ... Converging lens array, 241 ... Refractive index distribution Mold lens, 25 ... second gap filling layer, 27 ... translucent member, 110 ... photosensitive drum (image carrier).

Claims (7)

A light-emitting device having a plurality of light-emitting elements and a light-transmitting plate arranged in one direction, and light emitted from the plurality of light-emitting elements is transmitted through the plate and emitted;
A plurality of gradient index lenses capable of forming an erect real image by transmitting a part of the light emitted from the light emitting device are arranged, and one image formed by the plurality of gradient index lenses is formed. A converging lens array constituting a continuous image;
A light transmissive translucent member interposed between the light emitting device and the converging lens array;
The refractive index is 1.47 or more and 1.511 or less, and the light-transmitting material that fills one or both of the gap between the light-emitting device and the translucent member and the gap between the translucent member and the converging lens array. A gap filling layer;
An exposure apparatus comprising: A light-emitting device having a plurality of light-emitting elements and a light-transmitting plate arranged in one direction, and light emitted from the plurality of light-emitting elements is transmitted through the plate and emitted;
A plurality of gradient index lenses capable of forming an erect real image by transmitting a part of the light emitted from the light emitting device are arranged, and one image formed by the plurality of gradient index lenses is formed. A converging lens array constituting a continuous image;
A light transmissive translucent member interposed between the light emitting device and the converging lens array;
A light transmissive material having a refractive index lower than that of the plate member or the light transmissive member and filling one or both of the gap between the light emitting device and the light transmissive member and the gap between the light transmissive member and the converging lens array. A gap filling layer;
An exposure apparatus comprising: The light transmitting member has a refractive index of 1.515 or more and less than 2.
The exposure apparatus according to claim 1, wherein the exposure apparatus is characterized in that The plate material has a refractive index of 1.515 or more and less than 2.
The exposure apparatus according to any one of claims 1 to 3, wherein The gap filling layer also serves as an adhesive,
The exposure apparatus according to any one of claims 1 to 4, wherein the exposure apparatus includes: An antireflection treatment is applied to the surface of the gradient index lens from which transmitted light is emitted.
6. An exposure apparatus according to claim 1, wherein An image carrier;
A charger for charging the image carrier;
The exposure apparatus according to any one of claims 1 to 6, wherein a latent image is formed by irradiating light from the exposure apparatus onto a charged surface of the image carrier.
A developing unit for forming a visible image by attaching toner to the latent image;
An image forming apparatus, wherein the visible image is transferred to another object.

Images