JP2001026139A - Exposure device and image forming apparatus equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device, wherein light emitting elements are arranged, capable of being produced by a simple method so as to achieve highly accurate image forming relation. SOLUTION: In an exposure device equipped with a light emitting element substrate 4 wherein a light emitting element row 4a comprising a plurality of light emitting elements is formed on the same base material and an image forming means 3 for forming luminous fluxes emitted from a plurality of the light emitting elements into an image on an image carrier, the luminous fluxes emitted from a plurality of the light emitting elements pass through the base material to be taken out and one surface of the image forming means and the surface of the base material on a luminous flux taking-out side are formed in a closely bonded state and constituted so as to almost become the relation of WD=t/n wherein WD is the distance between an object point and the end surface of the image forming means, n is the refractive index to the light with a light emitting center wavelength of the light emitting element of the base material and t is the thickness of the base material when air is present on the side of the light emitting element of the image forming means.

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 as an exposure system for forming a monochrome image and a color image, such as a printer, a facsimile, and a copying machine, and an image forming apparatus equipped with the exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, many image forming apparatuses such as printers, facsimile machines, digital copiers and the like use an electrophotographic system, which includes image signals output from an external computer or an image reading system. An exposure system using a light source in which light emitting elements such as light emitting diodes are arrayed has been used as an exposure system for forming a latent image corresponding to an image on a photosensitive member. The exposure apparatus is small and can easily constitute a quiet image forming apparatus.

[0003] Here, the light emitting element is composed of a light emitting diode or the like, which emits diffused light from a certain point or a certain surface. It is necessary to form an image of the diffused light emitted from the light emitting element on each minute spot. Therefore, the exposure apparatus is provided with an imaging element array represented by a rod lens array so as to form a good spot. For this reason, the relative positional relationship between the light emitting element and the imaging element is set. Is set to have high positional accuracy.

On the other hand, a device capable of forming a high-definition image on the image forming apparatus itself is expected.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an exposure apparatus in which light emitting elements which can be manufactured by a simple method so as to achieve a high-precision imaging relationship are arrayed, and the exposure apparatus is used as a light source. It is an object of the present invention to provide an image forming apparatus that can realize high-definition image formation.

[0006]

According to the present invention, there is provided an exposure apparatus comprising: a light emitting element substrate having a plurality of light emitting elements arranged on the same base; and a light emitting element radiated from each of the plurality of light emitting elements. And an image forming means for forming a light beam on the image carrier, wherein the light beam emitted from each of the plurality of light emitting elements passes through the base material to take out the light beam. And an object point and the image formed when one surface of the image forming unit and the surface of the substrate on the side from which a light beam is extracted are in close contact with each other, and the light emitting element side of the image forming unit is air. Assuming that the distance from the end face of the means is WD, the refractive index of the base material with respect to light having the emission center wavelength of the light-emitting element is n, and the thickness of the base material is t, the relationship is roughly expressed as WD = t / n. It is characterized by having done.

Further, the exposure apparatus according to the present invention comprises a plurality of light sources.
A light-emitting element array in which optical elements are arranged on the same substrate
An optical element substrate, and divergent from each of the plurality of light emitting elements.
With image forming means for forming a light beam on the image carrier
In the apparatus, each of the plurality of light emitting elements emits light.
Light beam passing through the base material and extracting the light beam.
And the luminous flux emitted from the imaging means is
Through the material to extract the luminous flux.
One surface of the image forming means and the surface of the substrate on the side from which the light beam is extracted
Between m and m (m is any natural number)
The light emitting element side of the image forming means is empty.
Distance between the object point and the end face of the imaging means
WD, the bending of the substrate relative to the emission center wavelength of the light emitting element.
Folding rate n ₁, The thickness of the substrate is t₁, The m intermediate substrates
The refractive index of the light emitting element of_Two,
n_Three, N_Four... n_m, The thickness of the intermediate substrate is t_Two, T_Three, T_Four
... t_mThen, WD = t₁/ N₁+ T_Two/ N_Two+ T_Three/ N_Three+ T_Four/ N
_Four+ ... + t_m/ N_m Is characterized in that the relationship is roughly described.

Further, in the exposure apparatus according to the present invention, in the above-mentioned exposure apparatus, the intermediate substrate is an adhesive.

Further, the exposure apparatus according to the present invention is characterized in that, in the above exposure apparatus, each of the plurality of light emitting elements is formed of an EL type light emitting element, wherein each of the light emitting layers is an organic or inorganic layer. And

Further, in the exposure apparatus according to the present invention, in the above-described exposure apparatus, the substrate on which the plurality of light emitting elements are formed substantially transmits light having a light emission center wavelength of the plurality of light emitting elements. .

Further, in the exposure apparatus according to the present invention, in the above-mentioned exposure apparatus, the image forming means is constituted by a rod lens array formed by arranging one or more rows of rod lenses.

An image forming apparatus according to the present invention is an electrophotographic type in which a light beam emitted from a light source is formed into an image by the image forming means, and the formed light beam is exposed on an image carrier to be visualized. 6. The image forming apparatus according to claim 1, wherein the exposure device according to claim 1 is provided as the light source, and an arrangement direction of the light emitting element rows is a direction orthogonal to a rotation direction of the image carrier. The exposure apparatus is provided.

[0013]

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

<Embodiment 1> A first embodiment of the present invention will be described below with reference to FIGS.

First, an overall configuration of an exposure apparatus according to the present invention will be outlined with reference to FIG. FIG. 1 is a sectional view of the exposure device 30 and the image carrier 2 exposed by the exposure device 30.

In FIG. 1, on the EL element substrate 4, there is provided a light emitting section row 4a in which a plurality of light emitting sections are arranged in a substantially straight line. The row direction on the EL element substrate 4 is parallel to the rotation axis of the columnar image carrier 2, and the light emitting unit row 4 a and the image carrier 2
A rod lens array 3 in which a large number of rod lenses are arranged substantially in parallel with the row direction of the light emitting unit rows 4a on the EL element substrate 4 and faces the light emitting unit rows 4a on the EL element substrate 4 It is positioned so as to be in close contact with the surface to be polished. Here, the luminous flux diverged from the light emitting unit row 4a is configured to be emitted to the rod lens array 3 side as shown in FIG. Image as a minute spot on the surface of. Detailed configuration of the EL element substrate 4 and the light emitting unit row 4a described here,
The relationship between the rod lens array 3, the image carrier 2, and the thickness of the substrate of the EL element substrate will be described later.

The EL element substrate 4 will be described with reference to FIG. 2. In FIG. 2, each light emitting portion EM is arranged adjacently at a pixel pitch P on a transparent glass substrate to form a light emitting portion row 4a. I have.

As shown in FIG. 3, the rod lens array 3 is formed by arranging a plurality of cylindrical rod lenses in a plurality of rows.

In the exposure apparatus 30, on the EL element substrate 4, in addition to the light emitting element section 4a, a driver section (not shown) for driving each light emitting element is formed. In order to protect these electric driving units from external moisture or the like, a sealing unit 51 is provided on the light emitting unit row 4a side of the EL element substrate. The rod lens array 3 is adhered to a cover 6 for preventing light from leaking, and is adhered to an EL element substrate 4 inserted into a substrate mounting portion of the cover 6 as shown in the figure. In order to maintain this close contact, the cover 6 and the substrate-side holding member 52 are sandwiched by the leaf spring member 53 while sandwiching the EL element substrate 4.

Further, as shown in FIG. 5, the exposure device 30 is incorporated in the image forming apparatus as an exposure device.

Here, the operation will be described with reference to FIG. 5, taking a copying machine as an example of an image forming apparatus in which the exposure apparatus of the present embodiment is incorporated.

An image of a document placed on the document table 24 is read by a reading system 95 and converted into image data. On the other hand, the recording material 80 is fed to the feeding roller 1 in the main body.
3, 14 or from outside the main body, the sheet is fed via a feed roller 15, and when it reaches the position of the registration rollers 16a, 16b, the position of the leading end of the recording material 80 is detected by a sensor (not shown). Rollers 16a,
16b. On the other hand, in accordance with the image data from the exposure device 30, the charging is performed in advance by the charger 17 and the image carrier 2 is rotated in the direction of the arrow in FIG.
To form a charged latent image. A developer (not shown) is applied to the image carrier 2 from the developing device 18 in accordance with the charged latent image. Then, at the same time that the image carrier 2 to which the developing material is applied rotates to the position on the transfer device 19, the recording material 80 also reaches the transfer device 19, and the developing material is transferred onto the recording material 80 by the transfer device 19. Transcribed. Thereby, the recording material 80
Reaches the fixing devices 22a and 22b through the conveyance path 21, the transferred developer is fixed on the recording material 80, and is discharged to the tray 23 to complete the image formation.

Here, an EL element which is a light emitting portion of the present invention will be described with reference to FIGS.

FIG. 6 is a view of the structure of a light emitting element using an EL element as viewed from the layer stacking direction, and FIG. 7 is a view showing a cross section perpendicular to the layer stacking direction. The substrate 4 in FIGS. 6 and 7 is made of ITO or the like on a transparent substrate 1101 transparent to the emission wavelength. This also has one positive electrode transparent to the emission wavelength.
Are formed separately for each light emitting element such as 102a, 1102b, 1102c, 1102d... An organic hole transport layer 110 is formed on a part of the positive electrode.
3. An organic electron transport layer 1104 is laminated,
On the organic layers 1103 and 1104, a minus electrode layer 1105 of Mg, Al or the like is laminated. Here, the plus electrodes 1102a, 1102b, 1102c, 1102d
By applying an optimum voltage between... And the minus electrode 2045, good light emission can be performed, and a light amount can be obtained in the direction of the transparent substrate 1101. In addition, in FIG. 7, the plus electrode is assumed to be connected to the power supply in parallel, but this is a diagram schematically showing that a voltage is applied, and switching may be performed for each electrode. The electrodes may be switched. Although the electron transport layer and the hole transport layer have been described as being limited to organic substances, they may be composed of inorganic substances.

Here, the relationship between the positions of the rod lens array 3 and the EL element substrate 4 and the image formation in the embodiment of the present invention will be described with reference to FIG.

In FIG. 4, 3 is a rod lens array, and 4 is an EL.
T is the thickness of the EL element substrate 4 in the optical axis direction, b is the length of the rod lens array 3 in the optical axis direction, WD
Is the end face of the rod lens array 3 and the rod lens array 3
L is the length of the best image formation plane between the air, and L is the best image formation when the rod lens array 3 is both air between the image point and the rod lens array 3 and between the object point and the rod lens array 3. This is the distance between the object point and the image point in the image state. here,
In the present embodiment, it is assumed that the rod lens array 3 is optimized for the same-magnification imaging, and that the space between the image point and the rod lens array 3 and the space between the object point and the rod lens array 3 are both air. In some cases, it is assumed that both the distance on the optical axis between the rod lens array 3 and the image point and the distance on the optical axis between the rod lens array 3 and the object point are constituted by rod lenses having WD.

As described above, since the rod lens array 3 and the EL element substrate 4 are in close contact with each other, in order to improve the image formation by the rod lens array 3, the EL element is required.
A transparent base material serving as a base of the element substrate 4 (1101 in FIG. 7)
Must be taken into account. Considering the difference between the optical path length in air and the optical path length in the transparent substrate, the optical path of the incident angle θ1 to the rod lens in the imaged state in air in FIG.
Assuming that the incident angle θ2 on the L substrate is,
Assuming that the refractive index for the wavelength near the center of the light beam from the L light emitting unit is n, sin (θ1) = n · sin (θ2) WD · tan (θ1) = t · tan (θ2) From the relationship such as: t = WD・ Tan {sin ^-1 (n ・ sin (θ2))}
/ Tan θ2. This means that the thickness of the transparent substrate must be changed by the angle θ2 of the light beam diverged from the EL light emitting unit 4a and received by the rod lens array 3, but the angle of the light beam that can be transmitted by the rod lens array 3 θ
2 is generally at most about 10 °.

Here, to give a numerical example, WD = 5 m
FIG. 8 shows the relationship between the incident angle θ2 to the rod lens array 3 and the thickness t of the transparent substrate when m and n = 1.51. Referring to FIG. 8, t is substantially constant up to a portion around θ2 = 10 ° which is a range in which the rod lens array 3 can transmit, and t / n = WD.

According to this relationship, the luminous flux diverged from the EL light emitting portion row 4a can be maintained in a good image forming state by the rod lens array 3. Under this condition, the emission surface of the transparent substrate may be flat, and the assembling of the EL element substrate 4 and the rod lens array 3 can be performed by abutting, so that the configuration of the exposure apparatus is simplified. Further, the relationship between WD and the thickness t of the transparent base material is converted into an expression of the relationship between the imaging distance L between the object point and the image point of the rod lens array 3 in the air, the lens length b, and the thickness t of the transparent base material. Then, t = n · (L−b) / 2.

As described above, the exposure apparatus of the present embodiment can produce a good image-forming state with a simple configuration, and can form a good image in the image forming apparatus using the present exposure apparatus. Becomes

<Second Embodiment> A second embodiment of the present invention will be described below with reference to FIGS.

The exposure apparatus according to the second embodiment of the present invention has the first
Compared to the embodiment of the present invention, the rod lens array is fixed to the EL element substrate via a transparent adhesive,
The configuration of the element substrate and the image forming apparatus using the exposure apparatus are the same as those in the first embodiment, and a description thereof will be omitted.

First, the overall configuration of the exposure apparatus of the present invention will be outlined with reference to FIG. FIG. 9 is a sectional view of the exposure device 230 and the image carrier 202 exposed by the exposure device 230.

In FIG. 9, on the EL element substrate 204, there is provided a light emitting section row 204a in which a plurality of light emitting sections are arranged in a substantially straight line. The row direction on the EL element substrate 204 is parallel to the rotation axis of the columnar image carrier 202, and a number of rod lenses are provided between the light emitting unit row 204 a and the image carrier 202 on the EL element substrate 204. There is a rod lens array 203 arranged substantially parallel to the row direction of the light emitting section row 4a, and
The rod lens array 203 is adhered to the surface of the EL element substrate 204 facing the light emitting unit row 204a with an adhesive 255 that is substantially transparent to the wavelength of light emitted from the light emitting unit row 204a. Here, the luminous flux emitted from the light emitting unit row 204a is configured to be emitted to the rod lens array 203 side, and the luminous flux emitted from the light emitting unit row 204a is minutely deposited on the surface of the image carrier 202. An image is formed as a spot. The above-mentioned rod lens array 203
The relationship between the image carrier 202, the thickness of the substrate of the EL element substrate, and the like will be described later.

In the exposure apparatus 230, a driver section for driving each light emitting element and the like are formed on the EL element substrate 204 in addition to the light emitting element section 204a. In order to protect those electric driving units from external humidity and the like, the sealing unit 251 is provided with the light emitting unit row 204a of the EL element substrate.
It is provided on the side. The member to which the EL element substrate 204 and the rod lens array 203 are adhered is fixed to a cover 206 for preventing light from leaking by means of screws or adhesive.

Here, the relationship between the positions of the rod lens array 203, the adhesive 255, and the EL element substrate 204 and the image formation in the embodiment of the present invention will be described with reference to FIG.

In FIG. 10, reference numeral 203 denotes a rod lens array,
04 EL element substrate, 255 is an adhesive layer, t ₁ is the thickness of the adhesive 255 located between the end face and the EL element substrate 204 of the rod lens array 3, t ₂ is the EL element substrate 204
, B2 is the length of the rod lens array 203 in the optical axis direction, WD2 is the length between the end face of the rod lens array 203 and the best imaging plane of the rod lens array 203 in air, and L2 is This is the distance between the object point and the image point in the best imaging state when the rod lens array 203 is air between the image point and the rod lens array 203 and between the object point and the rod lens array 203. Here, in the present embodiment, the rod lens array 203 is optimized for the same-magnification imaging, and between the image point and the rod lens array 203 and between the object point and the rod lens array 20.
In the case where air is present between the rod lens array 3 and the rod lens array 203, the distance between the rod lens array 203 and the image point on the optical axis and the distance between the rod lens array 203 and the object point on the optical axis are both WD2. It is assumed that

As described above, since the rod lens array 203 and the EL element substrate 204 are adhered with the adhesive 255, the EL element substrate 204 is required to maintain good image formation by the rod lens array 203. It is necessary to take into account the refractive index of the transparent base material and the adhesive 255 as the base of the adhesive. Considering the difference between the optical path length in air and the optical path length in the transparent base material as in the first embodiment, the end surface of the rod lens array 203 and the rod lens array 203 in the imaged state in air in FIG. The length WD to the best imaging plane in the air, the thickness t ₁ between the rod lens of the adhesive 255, the EL element substrate 204, and the transparent substrate, the EL of the adhesive 255
The refractive index for the wavelength near the center of the light beam from the light emitting section is n
₁ , assuming that the thickness t ₂ of the transparent base material of the rod lens and the refractive index n ₂ for the wavelength near the center of the light beam from the EL light-emitting portion, the incidence of the light beam received by the rod lens array 3 as in the first embodiment. assuming corners small, can be satisfactorily imaged on the light beam from the light emitting portion photosensitive drum surface when the relationship of _{t 1 / n 1 + t 2} / n 2 = WD2 is established. Further, under this condition, the transparent substrate can be emitted in a flat plane, and the assembly of the EL element substrate and the rod lens array 3 can be abutted, so that the configuration of the exposure apparatus is simplified.

Here, to give a numerical example, WD2 =
5.00 mm, n ₁ = 1.40, t ₁ = 0.1 mm, n
_{When 2} = 1.51, t ₂ = 7.66 mm.

The relationship between WD2 and the thickness t of the transparent substrate is defined as the relationship between the imaging distance L between the object point and the image point of the rod lens array 3 in the air, the relationship between the lens length b, and the thickness t of the transparent substrate. if correct the equation becomes (L2-b2) / 2 = t 1 / n 1 + t 2 / n 2.

As described above, the image forming element row is connected to EL
Even when an exposure apparatus is configured by bonding to an element substrate, a good imaging state can be produced according to the configuration of the exposure apparatus of the present embodiment, and in an image forming apparatus using the exposure apparatus, Good image formation becomes possible.

[0042] Incidentally, a relation t / n = WD in the first embodiment, in the second embodiment the adhesive layer is applied, has been deformed in relation _{t 1 / n 1 + t 2} / n 2 = WD2, yet another If the layer of applied is a relational expression t / n = W in the embodiment, relation _{WD = t 1 / n 1 +} t 2 / n 2 + t 3 / n 3 + t 4 / n
₄ +... + T _m / n _m and can be expanded.

[0043]

As described above, the exposure apparatus of the present invention can form a high-definition latent image, and can apply the exposure apparatus capable of forming a high-definition latent image to an image forming apparatus. High quality images can be output.

[Brief description of the drawings]

FIG. 1 is a cross section of an exposure apparatus and an image carrier according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a substrate on which an EL element according to the first embodiment of the present invention is formed.

FIG. 3 is a diagram illustrating a rod lens array used in the first embodiment of the present invention.

FIG. 4 is a diagram illustrating an image forming state of the EL element substrate and the rod lens array according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of an image forming apparatus incorporating the exposure apparatus according to the first embodiment of the present invention.

FIG. 6 is a view of the EL element according to the first embodiment of the present invention as viewed from a layer stacking direction.

FIG. 7 is a diagram of the EL element according to the first embodiment of the present invention as viewed in a cross section of each layer.

FIG. 8 is a graph showing a relationship between an incident angle of a light beam on a rod lens array and a thickness of an EL element substrate according to the first embodiment of the present invention.

FIG. 9 is a cross section of an exposure apparatus and an image carrier according to a second embodiment of the present invention.

FIG. 10 is a diagram illustrating an image forming state of an EL element substrate and a rod lens array according to a second embodiment of the present invention.

[Explanation of symbols]

 2,202 Image carrier 3,203 Rod lens array 4,404 EL element substrate 255 Adhesive

Claims (7)

[Claims] 1. A light-emitting element substrate in which a plurality of light-emitting elements are arranged on the same base material and a light beam emitted from each of the plurality of light-emitting elements is formed on an image carrier. An exposure apparatus provided with an image forming unit, wherein the light beam emitted from each of the plurality of light emitting elements is configured to pass through the base material to take out the light beam, and one surface of the image forming unit; The distance between the object point and the end face of the image forming means is WD when the light emitting element side of the image forming means is air, and the distance is WD, An exposure apparatus characterized in that, when a refractive index of a light-emitting element of a material with respect to light having a central emission wavelength is n and a thickness of the base is t, the relationship is roughly expressed as WD = t / n. 2. A light emitting element substrate in which a plurality of light emitting elements are arranged on the same base material and a light beam emitted from each of the plurality of light emitting elements is imaged on an image carrier. An exposure apparatus comprising: an imaging unit configured to extract a light beam emitted from each of the plurality of light emitting elements through the base material and to extract the light beam; and a light beam emitted from the image forming unit. Are passed through the base material to take out the light beam, and m (m is any natural number) between one surface of the imaging means and the surface of the base material from which the light beam is taken out ), The distance between the object point and the end surface of the imaging means is WD, when the light-emitting element side of the imaging means is formed with an intermediate base material interposed, and the light-emitting element of the base material is The refractive index with respect to the emission center wavelength is n ₁ , the thickness of the substrate is t ₁ , and The refractive index for light having a emission center wavelength of the light emitting element of Mamotozai _{n 2, n 3, n 4} ... n m, when the thickness of the intermediate base and _{t 2, t 3, t 4} ... t m, WD = _{t 1 / n 1 + t 2} / n 2 + t 3 / n 3 + t 4 / n
₄ + ... + t _m / n exposure apparatus characterized by being configured such that outlined in relation _m. 3. The exposure apparatus according to claim 2, wherein the intermediate substrate is an adhesive. 4. The light-emitting element according to claim 1, wherein each of the plurality of light-emitting elements is formed of an EL-type light-emitting element, wherein each light-emitting layer is an organic or inorganic layer. Exposure apparatus according to the above. 5. The substrate according to claim 1, wherein the substrate on which the plurality of light emitting elements are formed transmits light having a light emission center wavelength of the plurality of light emitting elements. Exposure equipment. 6. The exposure apparatus according to claim 1, wherein said image forming means is constituted by a rod lens array formed by arranging one or more rows of rod lenses. 7. An electrophotographic image forming apparatus which forms a light beam emitted from a light source by the image forming means and exposes the formed light beam to an image carrier by visualizing the light beam. The exposure device according to claim 1 is provided as the light source, and the exposure device is arranged such that an arrangement direction of the light emitting element rows is a direction orthogonal to a rotation direction of the image carrier. An image forming apparatus comprising: