JP2006205384A - Line head module, exposure system, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line head module which increases the luminous energy of light from a light source taken into a lens array and thereby permits good exposure, exposure system having the line head module as an exposure means and an image forming device with the exposure system. <P>SOLUTION: The line head module 101 comprises: a line head 1 in which a plurality of EL elements are lined up and arranged; and the lens array 31 to make light from the line head 1 form an image, and further comprises a refractive index layer 54 whose refractive index is higher than 1 and 1.5 or lower between the line head 1 and the lens array 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a line head module, an exposure apparatus including the line head module as an exposure unit, and an image forming apparatus including the exposure apparatus.

  A line printer (image forming apparatus) is known as an electrophotographic printer. In this line printer, devices such as a charger, a line-shaped printer head (line head), a developing device, and a transfer device are arranged close to each other on the peripheral surface of a photosensitive drum (photosensitive member) serving as an exposed portion. is there. That is, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum charged by the charger by selective light emission operation of a light emitting element provided in the printer head, and this latent image is formed. Is developed with toner supplied from a developing device, and the toner image is transferred onto a sheet by a transfer device.

By the way, in order to obtain high-definition printing, it is necessary to efficiently image light emitted from the printer head on the photosensitive drum.
Accordingly, a technique has been proposed in which a lens array including a plurality of lens elements is provided between the printer head and the photosensitive member, and the light from the printer head is condensed on the photosensitive member to form an image (for example, , See Patent Document 1).
As a lens array used in such a line printer, one having a plurality of lens elements or one having two rows in a staggered pattern is known.
In recent years, there is also a printer head provided with an organic electroluminescence element (organic EL element) on a glass substrate as a light emitting element.
Japanese Patent Laid-Open No. 5-289477

By the way, a printer head (line head) using the organic EL element (EL element) as a light source and a lens array are usually arranged to face each other with air interposed therebetween.
Therefore, for example, when the light of the organic EL element is emitted from the glass substrate side, the light passes through the air from the glass substrate and then enters the lens array.
However, when the light of the organic EL element enters the air from the glass substrate, the light is refracted due to a difference in refractive index between the glass substrate and the air. Then, as described above, the lens array has only one row of lens elements or two rows in a staggered manner, and therefore, the lens array has a plurality of lens elements in the alignment direction, and is refracted. Although light can be captured relatively well, the direction orthogonal to the alignment direction of the lens elements is as few as one lens element or two arranged in a staggered manner, so that refracted light is sufficiently captured in the lens array. I could not.
In addition, light incident on the air layer having a low refractive index from the glass substrate at a critical angle or more is totally reflected at the interface between the glass substrate and the air layer, and of course cannot be taken into the lens array.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the amount of light taken from the light source into the lens array, thereby enabling good exposure and the line head module. An object of the present invention is to provide an exposure apparatus including a head module as an exposure unit and an image forming apparatus including the exposure apparatus.

  The line head module of the present invention is a line head module comprising: a line head in which a plurality of EL elements are arranged and arranged; and a lens array that forms an image of light from the line head, wherein the line head and the lens A refractive index layer having a refractive index greater than 1 and 1.5 or less is provided between the array and the array.

In the line head module of the present invention, for example, when the light of the EL element of the line head is emitted from the glass substrate side, the light of the line head enters the refractive index layer from the glass substrate and passes through the refractive index layer. Then, it enters the lens array.
By the way, when the lens array is composed of lens elements arranged in a line, for example, there is only one lens element in a direction orthogonal to the arrangement direction of the lens elements, and it is difficult to sufficiently capture light.
The line head module of the present invention is not a layer of air (hereinafter referred to as an air layer) between the line head and the lens array as in the prior art, and is larger than the refractive index (1.0) of air. Therefore, the difference in refractive index between the glass substrate and the refractive index layer is smaller than the difference in refractive index between the glass substrate and the air layer. That is, the refraction angle at the interface between the glass substrate and the refractive index layer is smaller than the refraction angle between the conventional air layer and the glass substrate.
Then, the light emitted to the area without the lens array enters the area with the lens array by reducing the refraction angle in the present invention. Therefore, the light amount of the line head taken into the lens array increases.

In addition, a part of the light totally reflected at the interface between the glass substrate and the air layer is also provided with a refractive index layer having a small refractive index difference from the glass substrate. It enters the lens array without being totally reflected at the interface. Therefore, the amount of light taken into the lens array can be increased by taking into the lens array the light that was previously totally reflected and could not be taken into the lens array.
Further, when the optical path length in the refractive index layer is the same as the optical path length in the conventional air layer, the actual length in the optical path length is shorter in the refractive index layer having a higher refractive index than in the air layer. Therefore, when the optical path length is the same as that of the prior art, the line head and the lens array come close to each other, so that a part of the light that has been removed from the lens array can be taken into the lens array.
Therefore, for example, when the line head of the present invention is used as an exposure unit of an image forming apparatus, for example, high-definition printing can be obtained and the reliability becomes high.

Moreover, in the said line head module, it is preferable that the said refractive index layer consists of a transparent resin layer.
In this way, for example, when a transparent adhesive resin is used as the refractive index layer, the lens array and the line head can be easily aligned by the refractive index layer.

An exposure apparatus according to the present invention includes the above-described line head module and a photoconductor exposed by light from the line head module.
According to the exposure apparatus of the present invention, as described above, the photosensitive member is exposed by the line head module with the increased intensity of the light extracted to the lens array. High reliability with high reliability.

Moreover, in the said exposure apparatus, it is preferable that the optical path length in the said refractive index layer is equal to the optical path length between the said lens array and a photoreceptor.
In this way, the light of the line head that has passed through the lens array forms an erecting equal-magnification image on the photoconductor.

An image forming apparatus according to the present invention includes the above-described exposure apparatus as an exposure unit.
According to the image forming apparatus of the present invention, since the exposure apparatus having a high degree of exposure is provided as the exposure unit, for example, an image printed on a sheet becomes clear and the image forming apparatus has high reliability.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing referred to below, the dimensions and the like of each component are appropriately changed and displayed for easy understanding of the drawing.

(Line head module)
First, the line head module will be described.
FIG. 1 is a perspective sectional view of a line head module according to an embodiment. In the line head module 101 of this embodiment, a line head 1 in which a plurality of organic electroluminescence elements (EL elements) are arranged in alignment and an SL element in which light from the line head 1 is imaged at an erecting magnification are arranged in alignment. An SL array (lens array) 31, a refractive index layer 54 provided between the line head 1 and the SL array 31, and the outer periphery of the line head 1, SL array 31, and refractive index layer 54 are held. And a head case 52. The line head 1 and the SL array 31 are held in the head case 52 in an aligned state, whereby the SL array 31 concatenates the light from the line head 1 to a photosensitive drum (described later) at an equal magnification. It is supposed to be imaged. The refractive index layer 54 adheres the element substrate on the light emitting side of the line head 1 and the SL array 31 without any gaps, and air is attached to the adhesive surface with the refractive index layer 54. Shall not intervene.

(Line head)
FIG. 2 is a diagram schematically showing the line head. The line head 1 is made of glass, and a light emitting element array 3A in which a plurality of organic electroluminescent elements (hereinafter referred to as organic EL elements) 3 are arranged on a long and thin rectangular element substrate 2, and the organic EL. A drive element group composed of drive elements 4 that drive the element 3 and a control circuit group 5 that controls the drive of these drive elements 4 (drive element group) are integrally formed. The line head 1 of the present embodiment is a so-called bottom emission type that emits light of the organic EL element 3 from the element substrate 2 side.
In FIG. 2, the light emitting element array 3A is formed by one organic EL element 3. However, for example, the organic EL elements 3 may be arranged in two lines in a staggered manner. In that case, the pitch of the organic EL elements 3 in the longitudinal direction of the line head 1 can be reduced, and therefore the resolution of the image forming apparatus described later can be improved.

The organic EL element 3 includes at least an organic light emitting layer between a pair of electrodes, and emits light by supplying a current from the pair of electrodes to the light emitting layer. A power supply line 8 is connected to one electrode of the organic EL element 3, and a power supply line 7 is connected to the other electrode via a drive element 4. The drive element 4 is composed of a switching element such as a thin film transistor (TFT) or a thin film diode (TFD). When a TFT is adopted as the drive element 4, the power supply line 8 is connected to the source region, and the control circuit group 5 is connected to the gate electrode. The control circuit group 5 controls the operation of the drive element 4, and the drive element 4 controls the energization of the organic EL element 3.
The detailed structure and manufacturing method of the organic EL element 3 and the driving element 4 will be described later. Further, in the line head 1, the organic EL element 3 is used as the EL element, but it goes without saying that an inorganic EL element may be used instead.

(SL array)
FIG. 3 is a perspective view of the SL array 31. This SL array 31 is an arrangement (arrangement) of two rows of SL elements 31a having the same configuration as a SELFOC (registered trademark) lens element manufactured by Nippon Sheet Glass Co., Ltd. in a staggered manner. Further, a gap between the SL elements 31a arranged in a staggered manner is filled with a black silicone resin 32, and a frame 34 is arranged around it. Here, the SL element 31a is a cylindrical lens element and forms an erecting equal-magnification image. By arranging (arranging) such SL elements 31a in two rows in a zigzag manner, the SL array 31 enables a wide range of images to be formed.
The SL array 31 is not limited to the SELFOC (registered trademark) lens array described above, and any of various types can be used as long as the lens array is formed by aligning lens elements for imaging light from the organic EL elements 3. Things can be used.

(Head case)
Returning to FIG. 1, the line head module 101 of this embodiment includes a head case 52 that supports the outer periphery of the line head 1 and the SL array 31. The head case 52 is formed in a slit shape by a rigid material such as Al. The cross section perpendicular to the longitudinal direction of the head case 52 has a shape in which both upper and lower ends are opened, and the upper half side walls 52a and 52a are arranged in parallel to each other, and the lower half side walls 52b and 52b are Each is inclined and arranged toward the center of the lower end. Although not shown, the side walls at both ends in the longitudinal direction of the head case 52 are also arranged in parallel to each other.

The above-described line head 1 is arranged inside the upper half side wall 52a of the head case 52.
An SL array 31 is disposed in a slit-like opening formed at the lower end of the head case 52. The refractive index n is larger than 1 (refractive index of air) and 1.5 (refractive index of glass) or less between the line head 1 and the element array 2 side. A rate layer 54 is provided. The refractive index layer 54 according to the present embodiment is made of, for example, PMMA (polymethyl methacrylate) and has a refractive index of 1.49. The refractive index layer 54 is provided so as to closely contact the line head 1 and the SL array 31 with no gap. The refractive index layer is not limited to the above-described material, and may be appropriately changed as long as the material has a light transmittance such that the refractive index n is greater than 1 and 1.5 or less. Further, the case where the refractive index of the refractive index layer is 1.5 is a state where glass is embedded between the line head 1 and the SL array 31, and the refractive index difference from the element substrate 2 made of glass. Naturally does not occur.

A sealing material 55 made of an ultraviolet curable resin such as acrylic is provided on the line head 1.
FIG. 4 is an enlarged view of a connecting portion (A portion in FIG. 1) of the line head 1. As shown in FIG. 4, a stepped pedestal 53 is formed on the entire inner surface of the side wall 52 a of the head case 52. The line head 1 is disposed horizontally with the lower surface of the line head 1 abutting on the upper surface of the pedestal 53. Although details will be described later, the line head 1 is a bottom emission type, and is arranged with the element substrate 2 facing downward and the sealing substrate 30 facing upward.
In addition, the sealing material 55 is disposed on the entire upper corner formed by the side wall 52 a of the head case 52 and the line head 1. The sealing material 55 is also disposed in the gap between the inner surface of the side wall 52 a of the head case 52 and the side surface of the line head 1.

  The sealing material 55 may contain a getter agent. A getter agent means a desiccant or an oxygen scavenger and adsorbs moisture and oxygen. According to this configuration, the sealing material 55 can reliably block the transmission of moisture and oxygen. Therefore, moisture absorption and oxidation of the organic EL element 3 formed on the line head 1 can be suppressed, and a decrease in durability and shortening of the life of the organic EL element 3 can be prevented.

FIG. 5A is a diagram schematically illustrating a case where light from the line head module 101 is emitted.
Hereinafter, in FIGS. 5 to 7, the light from the organic EL element 3 is incident on the SL element 31 a ′ provided at the end portion in the arrangement direction (see the X direction in FIG. 3) of the SL elements 31 a illustrated in FIG. 3. I decided to. Since the organic EL element 3 is a self-luminous element, the emitted light spreads radially as shown in FIG. 5A, and is thus emitted at various incident angles.
Here, light emitted in a direction perpendicular to the arrangement direction of the SL elements 31a ′ (see the Y direction in FIG. 3) is taken into the SL elements 31a ′ or the SL elements 31a adjacent in a staggered manner. In the embodiment, in order to simplify the description, it is assumed that the light is taken into only the SL element 31a ′.

  Since the line head module 101 of the present invention includes the bottom emission type line head 1 as described above, the incident angle light that does not totally reflect from the organic EL element 3 at the interface between the refractive index layer 54 and the element substrate 54. Enters the refractive index layer 54 from the element substrate 2 made of glass, passes through the refractive index layer 54, and then enters the SL array 31. Note that an arrow A shown in FIG. 5A indicates a light path of the line head 1 in the line head module 101 of the present embodiment. Also, a two-dot chain line arrow B shown in FIG. 5A indicates the light path of the line head 1 in the conventional line head module 101 with an air layer interposed.

The line head module 101 of the present invention is not a layer of air (hereinafter referred to as an air layer) between the line head and the lens array as in the prior art, and is larger than the refractive index (1.0) of air. Since the refractive index layer 54 having a refractive index of 1.49 that is equal to or lower than the refractive index (1.5) is provided, the refractive index difference (0.5) between the element substrate 2 and the air layer makes the element substrate 2 and the refractive index The refractive index difference (0.01) with respect to the layer 54 is smaller. That is, if the incident angle at which the light of the organic EL element 3 enters the interface 54a between the element substrate 2 and the refractive index layer 54 is θ1, the refraction angle θ2 at the interface 54a is 1.5 × sin θ1 = 1. .49 × sin θ2 (Snell's law).
Further, the refraction angle θ2 ′ when the space between the line head 1 and the SL array 31 is an air layer as in the prior art is 1.5 × sin θ1 = 1.0 × sin θ2 ′ (Snell's law). Therefore, since the relationship obtained from the two equations is sin θ2 ′ = 1.49 × sin θ2, the refraction angle θ2 between the element substrate 2 and the air layer is smaller than the refraction angle θ2 ′ between the element substrate 2 and the air layer. As shown in FIG. 5A, it is small (θ2 <θ2 ′).

  Here, the SL array 31 is composed of the SL elements 31a arranged in two rows in a staggered manner as described above, and the SL elements 31a are arranged in a direction perpendicular to the arrangement direction (see the Y direction in FIG. 2). Only one or two are arranged. That is, since the plurality of lens elements 31a are provided in the alignment direction of the SL elements 31a (see the X direction in FIG. 2), the light from the organic EL element 3 can be taken in relatively well. However, in the direction orthogonal to the alignment direction of the lens elements 31a (see the Y direction in FIG. 2), the number of SL elements 31a (SL element 31a ′) is small, and the light of the organic EL element 3 that has spread radially is SL. The light is also emitted to a region where the element 31 a is not present, and it is difficult to sufficiently capture the light into the lens array 31. In the present invention, by reducing the refraction angle θ2 ′ at the interface 54a in the element substrate 54a as compared with the prior art, the light of the organic EL element 3 is placed in a region where the SL element 31a ′ is present as shown in FIG. The amount of light taken into the SL array 31 from the line head 1 can be increased.

FIG. 5B is a diagram showing a state where the light of the organic EL element 3 is totally reflected. A broken arrow a shown in FIG. 5B indicates the light path of the line head 1 in the line head module 101 of this embodiment. Further, a two-dot chain line arrow b shown in FIG. 5B indicates a light path of the line head 1 in the conventional line head module 101.
Here, the light of the organic EL element 3 is predetermined to the element substrate 2 made of glass having a high refractive index (n = 1.5) as in the prior art, and the air layer having a low refractive index (n = 1.0). When incident at an angle larger than the angle (critical angle), the light is totally reflected at the interface between the element substrate 2 and the air layer.

However, in this embodiment, since the refractive index layer 54 having a higher refractive index than the air layer is provided between the element substrate 2 and the SL array 31, the interface between the refractive index layer 54 and the element substrate 2 is provided. The critical angle at 54a is larger than that of the conventional air layer. Therefore, a part of the light component of the organic EL element 3 that has been totally reflected in the past can be taken into the refractive index layer 54 and can be taken into the SL element 31a ′ as a result. Therefore, the amount of light captured by the entire SL array 31 increases.

  FIG. 6 is a diagram schematically showing the positional relationship between the line head module and the light from the organic EL element 3 taken into the SL element 31a. As described above, the SL element 31a indicates a case where the light of the organic EL element 3 is taken into the SL element 31a 'provided at the end of the SL array 31, and the two-dot chain line is The light uptake of the organic EL element 3 in the conventional case is shown, and the solid line shows the light uptake of the organic EL element 3 in the present embodiment. Here, a region where the light emitted from the organic EL element 3 can be taken into the SL element 31a ′ is defined as a take-in angle. In addition, regarding the optical path between the element substrate 2 and the SL array 31, the optical path where the actual length provided with the refractive index layer 54 is d3 is the first optical path, and the air layer is provided as in the prior art. The optical path whose length is d4 is defined as a second optical path. Note that the optical path length described later is determined by the product of the refractive index between paths and the actual length of the path.

As shown in FIG. 6, the optical path length in the first optical path is 1.49 × d3. The optical path length in the second optical path is 1.0 × d4. If the optical path lengths in these two paths are the same, the actual length d3 of the first optical path provided with the refractive index layer 54 is obtained from the equation d4 = 1.49 × d3. Actually, it becomes shorter than the length d4.
Therefore, when the organic EL element 3 and the SL array 31 are arranged so as to have the optical path length, the first optical path is more organic than the second optical path, as shown in FIG. The EL element 3 approaches the SL array 31.
Then, assuming that the taking-in angle in the first optical path is θ3 and the taking-in angle in the second optical path is θ4, the SL element 31a is used in the first optical path according to the present embodiment as compared with the conventional second optical path. As 'and the organic EL element 3 serving as the light source come closer, the light take-in angle to the SL element 31a' becomes θ3> θ4.
Therefore, by increasing the capturing angle with respect to the SL element 31a, it is possible to capture light that has not been captured by the conventional SL element 31a ′ (light larger than the capturing angle). Therefore, the entire SL array 31 can increase the amount of light of the organic EL element 3 to be captured.

(Analysis example)
Next, the intensity of light taken into the SL array 31 with respect to the light from the organic EL element 3 was obtained by simulation.
The simulation was performed under the conditions according to the above embodiment. The refractive index layer 49 having a refractive index of 1.49 is provided between the line head 1 and the SL array 31, and the actual length d4 in the conventional second optical path is 2.3 mm. . Therefore, from the relationship of d4 = 1.49 × d3, the actual length in the first optical path of the present embodiment is d3 = 1.54 mm. In addition, the light capture angle θ4 in the conventional SL element 31a ′ is 11.5 °, and the capture angle θ3 obtained based on this is about 17 °. Therefore, the provision of the refractive index layer 54 increases the light take-in angle with respect to the SL element 31a ′ by about 1.5 times.
The graph of FIG. 7 shows the simulation result under the above conditions, the vertical axis of the graph shows the amount of light taken into the SL array 31, that is, the light intensity, and the horizontal axis shows the wavelength of the light. It is. In the simulation, when the light of the organic EL element 3 is perpendicularly incident on the refractive index layer 54 from the front (angle of 0 °) (PMMA0), the light of the organic EL element 3 is 10 to the refractive index layer 54. When the light is incident obliquely at an angle of 0 ° (PMMA 10), for comparison, when the light of the organic EL element in the conventional line head module is incident on the air layer from the front (angle of 0 °) (AIR0), This was performed for four patterns when light was incident on the air layer at 10 ° (AIR10).

As shown in the graph of FIG. 7, when the light emitted from the organic EL element 3 enters the refractive index layer 54 from the front (PMMA0), enters the conventional air layer from the front (AIR0). In comparison with the above, the light amount (light intensity) increases about 2.4 times.
Further, when the light emitted from the organic EL element 3 is incident on the refractive index layer 54 at 10 ° (PMMA 10), the amount of light is larger than that when incident on the conventional air layer at 10 ° (AIR10). (Light intensity) increases about 1.8 times.
In the graph of FIG. 7, two cases (incident at the front face and incident at 10 °) are shown. However, when the light is incident on the refractive index layer 54 at other angles, the conventional air is similarly used. Compared with the case of entering the layer, the present invention can increase the amount of light taken into the SL array 31.
Therefore, this simulation shows that the line head module 101 of the present embodiment can increase the amount of light (light intensity) taken into the SL array 31 from the light of the organic EL element 3.

(Manufacturing method of line head module)
Next, the manufacturing method of the line head module of this embodiment is demonstrated using FIG. First, a sealing material 55 made of an ultraviolet curable resin is applied to the entire inner surface of the head case 52 along the pedestal 53 formed on the inner surface of the upper half side wall 52a of the head case 52. Next, the line head 1 having the refractive index layer 54 attached to the inside of the head case 52 is inserted and disposed on the upper surface of the pedestal 53. Then, spot UV irradiation is performed on the applied sealing material 55 at predetermined intervals, the sealing material 55 is partially cured, and the line head 1 is temporarily fixed.
Next, the lens array 31 is inserted into the lower end opening of the head case 52. At this time, the refractive index layer 54 and the lens array 31 are in close contact with each other.

  Here, relative alignment of the lens array 31 with respect to the line head 1, that is, alignment is performed. Although the alignment method is not particularly limited, for example, a method can be employed in which the organic EL element 3 of the line head 1 is turned on and the two are aligned while confirming the imaging state by the lens array 31. At this time, the light emission line of the line head, that is, the center line of the light emitting element array 3A formed by arranging the organic EL elements 3 is made to coincide with the center line of the lens array 31, thereby minimizing the periodic unevenness of the transmitted light. It can be. The refractive index layer 54 is not limited to this embodiment, and can be changed as appropriate. For example, by using an adhesive made of a transparent resin as the refractive index layer 54, the SL array 31 and the line head 1 may be easily aligned by this refractive index layer.

Next, the entire line head module 101 is irradiated with ultraviolet rays. Thereby, the whole sealing material 55 which consists of ultraviolet curable resin hardens | cures.
At this time, the line head 1 may be hermetically bonded to the head case 52 with the sealing material 55 so that the inside thereof may be filled with nitrogen gas.
As a result, it is possible to prevent moisture and oxygen from approaching the line head 1 in the line head module, thereby suppressing moisture absorption and oxidation of the organic EL element 3 to prevent a decrease in durability and a shortened life. can do.

(Organic EL element and driving element)
Next, detailed configurations of the organic EL element 3 and the driving element in the line head 1 will be described with reference to FIGS.
In the present embodiment, since it is a so-called bottom emission type in which the light emitted from the light emitting layer 60 is emitted from the pixel electrode 23 side, the light emitted light is extracted from the element substrate 2 side. A translucent material is used. For example, glass, quartz, resin (plastic, plastic film) and the like can be mentioned, and a glass substrate is particularly preferably used.

  In the case of a so-called top emission type in which the light emitted from the light emitting layer 60 is emitted from the cathode (counter electrode) 50 side, the emitted light is extracted from the sealing substrate side that is the opposite side of the element substrate 2. Therefore, either a transparent substrate or an opaque substrate can be used. Examples of the opaque substrate include a thermosetting resin and a thermoplastic resin in addition to a ceramic sheet such as alumina and a metal sheet such as stainless steel that has been subjected to an insulation treatment such as surface oxidation.

  On the element substrate 2, a circuit unit 11 including a driving TFT 123 (driving element 4) connected to the pixel electrode 23 is formed, and an organic EL element 3 is provided thereon. The organic EL element 3 includes a pixel electrode 23 functioning as an anode, a hole transport layer 70 for injecting / transporting holes from the pixel electrode 23, a light emitting layer 60 made of an organic EL material, and a cathode 50 in this order. It is configured by being formed.

Here, when the organic EL element 3 and the driving TFT 123 (driving element 4) are shown in a schematic view corresponding to FIG. 2, it is as shown in FIG. 8B. In FIG. 8B, the power supply line 7 is connected to the source / drain electrodes of the drive element 4, and the power supply line 8 is connected to the cathode 50 of the organic EL element 3.
In the organic EL element 3 having such a configuration, the holes injected from the hole transport layer 70 and the electrons from the cathode 50 are combined in the light emitting layer 60 as shown in FIG. By doing so, it emits light.

In this embodiment, which is a bottom emission type, the pixel electrode 23 that functions as an anode is formed of a transparent conductive material, and specifically, ITO is preferably used.
As a material for forming the hole transport layer 70, in particular, a dispersion of 3,4-polyethylenediosithiophene / polystyrene sulfonic acid (PEDOT / PSS), that is, 3,4-polyethylenedioxy in polystyrene sulfonic acid as a dispersion medium. A dispersion in which thiophene is dispersed and further dispersed in water is preferably used.
In addition, as a forming material of the positive hole transport layer 70, various things can be used, without being limited to the said thing. For example, a material obtained by dispersing polystyrene, polypyrrole, polyaniline, polyacetylene or a derivative thereof in an appropriate dispersion medium such as the aforementioned polystyrene sulfonic acid can be used.

  As a material for forming the light emitting layer 60, a known light emitting material capable of emitting fluorescence or phosphorescence is used. In this embodiment, for example, a light emitting layer whose emission wavelength band corresponds to red is adopted, but of course, a light emission layer whose emission wavelength band corresponds to green or blue may be adopted. In this case, the photoconductor used has sensitivity in the light emitting region.

  Specific examples of the material for forming the light emitting layer 60 include (poly) fluorene derivative (PF), (poly) paraphenylene vinylene derivative (PPV), polyphenylene derivative (PP), polyparaphenylene derivative (PPP), and polyvinylcarbazole (PVK). ), Polythiophene derivatives, and polysilanes such as polymethylphenylsilane (PMPS) are preferably used. In addition, these polymer materials include polymer materials such as perylene dyes, coumarin dyes, rhodamine dyes, rubrene, perylene, 9,10-diphenylanthracene, tetraphenylbutadiene, Nile red, coumarin 6, and quinacridone. It can also be used by doping a low molecular weight material such as.

The cathode 50 is formed so as to cover the light emitting layer 60. For example, Ca is formed to a thickness of about 20 nm, and Al is formed thereon to a thickness of about 200 nm to form an electrode having a laminated structure, and the Al is reflected. It also functions as a layer.
Further, a sealing substrate (not shown) is stuck on the cathode 50 via an adhesive layer.

  In addition, the circuit unit 11 is provided below the organic EL element 3 as described above. The circuit unit 11 is formed on the element substrate 2. That is, a base protective layer 281 mainly composed of SiO 2 is formed on the surface of the element substrate 2 as a base, and a silicon layer 241 is formed thereon. A gate insulating layer 282 mainly composed of SiO 2 and / or SiN is formed on the surface of the silicon layer 241.

  In the silicon layer 241, a region overlapping with the gate electrode 242 with the gate insulating layer 282 interposed therebetween is a channel region 241a. The gate electrode 242 is a part of a scanning line (not shown). On the other hand, a first interlayer insulating layer 283 mainly composed of SiO 2 is formed on the surface of the gate insulating layer 282 that covers the silicon layer 241 and on which the gate electrode 242 is formed.

  Further, in the silicon layer 241, a low concentration source region 241b and a high concentration source region 241S are provided on the source side of the channel region 241a, while a low concentration drain region 241c and a high concentration drain are provided on the drain side of the channel region 241a. The region 241D is provided to form a so-called LDD (Light Doped Drain) structure. Among these, the high-concentration source region 241S is connected to the source electrode 243 through a contact hole 243a that opens over the gate insulating layer 282 and the first interlayer insulating layer 283. The source electrode 243 is configured as a part of a power supply line (not shown). On the other hand, the high-concentration drain region 241D is connected to the drain electrode 244 made of the same layer as the source electrode 243 through a contact hole 244a that opens through the gate insulating layer 282 and the first interlayer insulating layer 283.

  On the first interlayer insulating layer 283 on which the source electrode 243 and the drain electrode 244 are formed, for example, a planarizing film 284 mainly composed of an acrylic resin component is formed. The planarizing film 284 is formed of a heat-resistant insulating resin such as acrylic or polyimide, and has surface irregularities caused by the driving TFT 123 (driving element 4), the source electrode 243, the drain electrode 244, and the like. It is a well-known thing formed in order to eliminate.

  A pixel electrode 23 made of ITO or the like is formed on the surface of the planarizing film 284 and connected to the drain electrode 244 through a contact hole 23a provided in the planarizing film 284. That is, the pixel electrode 23 is connected to the high concentration drain region 241D of the silicon layer 241 through the drain electrode 244.

On the surface of the planarization film 284 on which the pixel electrode 23 is formed, the pixel electrode 23 and the above-described inorganic partition wall 25 are formed, and on the inorganic partition wall 25, an organic partition wall 221 is formed. On the pixel electrode 23, the hole transport layer 70 and the light emitting layer 60 are formed inside the opening 25 a formed in the inorganic partition wall 25 and the opening 221 a formed in the organic partition wall 221, that is, in the pixel region. Are stacked in this order from the pixel electrode 23 side, thereby forming a functional layer.
In this example, the driving element 4 such as a TFT is formed on the element substrate 2 as an element for driving the EL element. However, the driving element 4 is not formed on the element substrate 2, and the driving element 4 is driven. 4 may be externally attached. Specifically, the driver IC may be COG mounted on the terminal area of the EL element substrate, or a flexible circuit board on which the driver IC is mounted may be mounted on the EL element substrate.

Next, a description will be given of an exposure apparatus 102 according to the present invention, which is a usage pattern of the line head module 101, and includes a line head module and a photoconductor exposed by light from the line head module.
FIG. 9 is a view showing the exposure apparatus 102. As shown in FIG. 9, the exposure apparatus 102 irradiates light from a line head module 101 onto a photosensitive drum (photosensitive body) 9 serving as an exposed portion, forms an image, and performs exposure. Here, as described above, the line head 1 and the SL array 31 are integrally held in the head case 52 in a state of being aligned with each other. Therefore, in use, the line head module 101 is simply attached to the photosensitive drum 9. Just align.
Therefore, in this line head module 101, the alignment with respect to the photosensitive drum 9 is easier than in the case where the line head 1 and the SL array 31 are prepared separately, and uneven exposure due to poor alignment is surely prevented. Will come to be.
According to the exposure apparatus of the present invention, as described above, the photosensitive drum 9 is exposed by the line head module 101 whose amount of light taken into the SL array 31 is increased, so that the photosensitive drum 9 is surely exposed. Can do.
In the exposure apparatus, the optical path length in the refractive index layer is equal to the optical path length between the lens array and the photosensitive member.
In this way, the light of the line head 1 that has passed through the SL array 31 can form an erecting equal-magnification image on the photosensitive drum 9.

Next, an image forming apparatus provided with the line head 1 of the present invention will be described.
(Tandem image forming device)
FIG. 10 is a diagram showing a first embodiment of an image forming apparatus according to the present invention, and reference numeral 80 in FIG. 10 denotes a tandem image forming apparatus. The image forming apparatus 80 includes four photosensitive drums (image carriers) 41K having the same configuration corresponding to the organic EL array line heads 101K, 101C, 101M, and 101Y as an example of the line head according to the present invention. , 41C, 41M, and 41Y, respectively, and configured as a tandem system. That is, the image forming apparatus of the present invention includes the exposure apparatus as an exposure unit.

  The image forming apparatus 80 includes a driving roller 91, a driven roller 92, and a tension roller 93. The intermediate transfer belt 90 is stretched around these rollers so as to circulate and drive in the arrow direction (counterclockwise direction) in FIG. Is. Photosensitive drums 41K, 41C, 41M, and 41Y are arranged at predetermined intervals with respect to the intermediate transfer belt 90. These photosensitive drums 41K, 41C, 41M, and 41Y have a photosensitive layer as an image carrier on the outer peripheral surface thereof.

Here, K, C, M, and Y in the symbols mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are for black, cyan, magenta, and yellow, respectively.
The meanings of these symbols (K, C, M, Y) are the same for the other members. The photosensitive drums 41K, 41C, 41M, and 41Y are driven to rotate in the arrow direction (clockwise) in FIG. 10 in synchronization with the driving of the intermediate transfer belt 90.

Around each photosensitive drum 41 (K, C, M, Y), charging means (corona charger) 42 for uniformly charging the outer peripheral surface of the photosensitive drum 41 (K, C, M, Y), respectively. (K, C, M, Y) and rotation of the photosensitive drum 41 (K, C, M, Y) on the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y) And an organic EL array line head 101 (K, C, M, Y) that sequentially performs line scanning.
Here, as described above, the organic EL array line head 101 (K, C, M, Y) is integrally held together with the SL array (not shown) by the head case in a state of being aligned with each other. It is used as.

  Further, a toner as a developer is applied to the electrostatic latent image formed by the organic EL array line head 101 (K, C, M, Y) (line head module) to form a visible image (toner image). As a transfer means for sequentially transferring the developing device 44 (K, C, M, Y) and the toner image developed by the developing device 44 (K, C, M, Y) to the intermediate transfer belt 90 that is a primary transfer target. Primary transfer roller 45 (K, C, M, Y) and a cleaning device as a cleaning means for removing toner remaining on the surface of the photosensitive drum 41 (K, C, M, Y) after being transferred 46 (K, C, M, Y).

  Here, each organic EL array line head 101 (K, C, M, Y) is installed such that each array direction is along the bus line of the photosensitive drum 41 (K, C, M, Y). Then, the emission energy peak wavelength of each organic EL array line head 101 (K, C, M, Y) and the sensitivity peak wavelength of the photosensitive drum 41 (K, C, M, Y) are set to substantially coincide with each other. Has been.

  The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer. The film thickness of the developed developer is regulated by a regulating blade, and the developing roller is brought into contact with or pressed against the photosensitive drum 41 (K, C, M, Y), whereby the photosensitive drum 41 (K, C, M, A developer is attached in accordance with the potential level of Y) and developed as a toner image.

  The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). Primary transfer is sequentially performed on the transfer belt 90. The toner images that are sequentially superimposed on the intermediate transfer belt 90 to become a full color are secondarily transferred to the recording medium P such as paper by the secondary transfer roller 66 and further pass through the fixing roller pair 61 that is a fixing unit. Then, the toner image is fixed on the recording medium P and then discharged onto a paper discharge tray 68 formed on the upper part of the apparatus by a pair of paper discharge rollers 62.

  In FIG. 10, reference numeral 63 denotes a paper feed cassette in which a large number of recording media P are stacked and held, 64 denotes a pickup roller for feeding the recording media P from the paper feed cassette 63 one by one, and 65 denotes secondary transfer. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion of the roller 66; a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 90; A cleaning blade 67 serves as a cleaning unit that removes toner remaining on the surface of the intermediate transfer belt 90 after the secondary transfer.

(4-cycle image forming apparatus)
Next, a second embodiment of the image forming apparatus according to the present invention will be described. FIG. 11 is a vertical side view of a four-cycle image forming apparatus. In FIG. 11, an image forming apparatus 160 includes, as main components, a developing device 161 having a rotary configuration, a photosensitive drum 165 that functions as an image carrier, an image writing unit 167 including the line head module, an intermediate transfer belt 169, A paper conveyance path 174, a fixing roller heating roller 172, and a paper feed tray 178 are provided. That is, the image forming apparatus of the present invention includes the exposure apparatus as an exposure unit.

  The developing device 161 is configured such that the developing rotary 161a rotates in the direction of arrow A about the shaft 161b. The inside of the development rotary 161a is divided into four, and image forming units for four colors of yellow (Y), cyan (C), magenta (M), and black (K) are provided. Reference numerals 162a to 162d are arranged in the image forming units for the four colors. The developing rollers rotate in the arrow B direction, and the toner supply rollers 163a to 163d rotate in the arrow C direction. Reference numerals 164a to 164d are regulating blades that regulate the toner to a predetermined thickness.

  In FIG. 11, reference numeral 165 denotes a photosensitive drum that functions as an image carrier as described above, 166 denotes a primary transfer member, and 168 denotes a charger. Reference numeral 167 denotes image writing means serving as exposure means in the present invention, which comprises the above-described line head module. The photosensitive drum 165 is rotationally driven in the direction of arrow D, which is the direction opposite to the developing roller 162a, by a drive motor (not shown), for example, a step motor. The line head module constituting the image writing unit 167 is arranged in a state where alignment (optical axis alignment) is performed between the line head module and the photosensitive drum 165.

  The intermediate transfer belt 169 is stretched between the driving roller 170a and the driven roller 170b. The driving roller 170 a is connected to the driving motor of the photosensitive drum 165 and transmits power to the intermediate transfer belt 169. That is, the drive roller 170a of the intermediate transfer belt 169 is rotated in the direction of arrow E which is the opposite direction to the photosensitive drum 165 by the drive motor.

  The paper transport path 174 is provided with a plurality of transport rollers, a pair of paper discharge rollers 176, and the like, so that the paper is transported. An image (toner image) on one side carried on the intermediate transfer belt 169 is transferred to one side of the paper at the position of the secondary transfer roller 171. The secondary transfer roller 171 is brought into contact with and separated from the intermediate transfer belt 169 by a clutch. When the clutch is turned on, the secondary transfer roller 171 is brought into contact with the intermediate transfer belt 169 so that an image is transferred onto a sheet.

The sheet on which the image has been transferred as described above is then subjected to a fixing process by a fixing device having a fixing heater H. The fixing device is provided with a heating roller 172 and a pressure roller 173.
The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the direction of arrow F. When the paper discharge roller pair 176 rotates in the reverse direction from this state, the paper reverses its direction and advances in the double-sided printing conveyance path 175 in the direction of arrow G. 177 is an electrical component box, 178 is a paper feed tray for storing paper, and 179 is a pickup roller provided at the outlet of the paper feed tray 178.

  For example, a low-speed brushless motor is used as a drive motor for driving the transport roller in the paper transport path. For the intermediate transfer belt 169, a step motor is used because color misregistration correction is required. Each of these motors is controlled by a signal from a control means (not shown).

  In the state shown in FIG. 11, a yellow (Y) electrostatic latent image is formed on the photosensitive drum 165, and a high voltage is applied to the developing roller 162a, whereby a yellow image is formed on the photosensitive drum 165. Is done. When the yellow back side and front side images are all carried on the intermediate transfer belt 169, the development rotary 161a rotates 90 degrees in the direction of arrow A.

  The intermediate transfer belt 169 rotates once and returns to the position of the photosensitive drum 165. Next, two images of cyan (C) are formed on the photosensitive drum 165, and this image is carried on the yellow image carried on the intermediate transfer belt 169. Thereafter, the 90-degree rotation of the development rotary 161 and the one-rotation process after the image is carried on the intermediate transfer belt 169 are repeated in the same manner.

  For carrying four color images, the intermediate transfer belt 169 rotates four times, and then the rotation position is further controlled to transfer the image onto the sheet at the position of the secondary transfer roller 171. The paper fed from the paper feed tray 178 is transported by the transport path 174, and the color image is transferred to one side of the paper at the position of the secondary transfer roller 171. The sheet on which the image is transferred on one side is reversed by the discharge roller pair 176 as described above, and stands by on the conveyance path. Thereafter, the sheet is conveyed to the position of the secondary transfer roller 171 at an appropriate timing, and the color image is transferred to the other side. The housing 180 is provided with an exhaust fan 181.

In the image forming apparatuses 80 and 160 shown in FIGS. 10 and 11, the line head module 101 of the present invention as shown in FIG. 1 is provided as an exposure unit.
Therefore, since the image forming apparatuses 80 and 160 are provided with the exposure device having a high exposure degree as the exposure unit as described above, for example, the image printed on the paper becomes clear and the quality of the obtained print is obtained. Can be improved.
The image forming apparatus including the line head of the present invention is not limited to the above-described embodiment, and various modifications can be made.

It is a perspective sectional view of a line head module concerning an embodiment. It is the figure which showed the line head typically. It is a perspective view of SL array. It is an enlarged view in the joint part of a line head. (A) is explanatory drawing of refraction of light, (b) is a figure which shows the total reflection of light. It is a figure explaining the positional relationship of an organic EL element and SL element. It is a graph which shows the intensity | strength of the light taken in into SL array. (A) is principal part sectional drawing of a line head, (b) is a schematic diagram. It is a schematic block diagram which shows the exposure apparatus of this invention. 1 is a schematic configuration diagram showing a first embodiment of an image forming apparatus of the present invention. It is a schematic block diagram which shows 2nd Embodiment of the image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Line head, 3 ... Organic EL element (EL element), 31 ... Lens array (SL array), 41 ... Photosensitive drum (photosensitive body), 54 ... Refractive index layer, 80 ... Image forming apparatus, 101 ... Line head Module, 102 ... exposure device, 160 ... image forming device, 165 ... photosensitive drum (photosensitive member)

Claims (5)

A line head module comprising: a line head in which a plurality of EL elements are arranged and arranged; and a lens array that forms an image of light from the line head,
A line head module comprising a refractive index layer having a refractive index greater than 1 and 1.5 or less between the line head and the lens array.   The line head module according to claim 1, wherein the refractive index layer is made of a transparent resin layer.   An exposure apparatus comprising: the line head module according to claim 1; and a photoconductor exposed by light from the line head module.   4. The exposure apparatus according to claim 3, wherein an optical path length in the refractive index layer is equal to an optical path length between the lens array and the photosensitive member. An image forming apparatus comprising the exposure apparatus according to claim 3 as exposure means.

Images