JP2007287557A - Organic semiconductor device, optical head using this, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor device capable of securing a sufficient barrier performance against moisture and gas by using a simple sealing process. <P>SOLUTION: The organic semiconductor device seals an organic semiconductor element formed on a glass substrate by a metal material. The metal material is a flexible metal material and is adhered to the glass substrate through an adhesive. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic semiconductor device, an optical head using the same, and an image forming apparatus, and more particularly to a sealing structure of an organic light emitting device used for an optical head in which light emitting elements are arranged in a line to form a light emitting element array.

  An organic electroluminescent element is a light-emitting device that utilizes the electroluminescence phenomenon of a solid fluorescent material, and is partially put into practical use as a small display.

  Organic electroluminescent devices can be classified into several groups depending on the material used for the light emitting layer. One typical example is a low molecular weight organic electroluminescent device using a low molecular weight organic compound in the light emitting layer, which is mainly produced by vacuum deposition. The other is a polymer organic electroluminescent device using a polymer compound in the light emitting layer.

  Polymer organic electroluminescent devices can be formed by spin coating, ink-jet, printing, etc. by using a solution in which the material constituting each functional layer is dissolved. It is attracting attention as a technology that can be expected to increase the area.

  A typical polymer organic EL device is produced by laminating a plurality of functional layers such as a charge injection layer and a light emitting layer between an anode and a cathode. The structure of a typical polymer organic EL element and its production procedure will be described below.

  First, a PEDOT: PSS (mixture of polythiophene and polystyrenesulfonic acid: hereinafter referred to as PEDOT) thin film as a charge injection layer is formed by spin coating or the like on a glass substrate on which ITO (indium tin oxide) as an anode is formed. To do. PEDOT is a material that has become a de facto standard as a charge injection layer, and functions as a hole injection layer by being disposed on the anode side.

  On the PEDOT layer, polyphenylene vinylene (hereinafter referred to as PPV) and a derivative thereof, or polyfluorene and a derivative thereof are formed as a light emitting layer by a spin coating method or the like. Then, a metal electrode as a cathode is formed on these light emitting layers by vacuum deposition to complete the device.

As described above, the polymer organic electroluminescent device has an excellent feature that it can be produced by a simple process, and is expected to be applied to various applications, but it has a sufficiently large emission intensity. This is a problem to be solved in that it cannot be performed and when the driving is performed for a long time, the lifetime is not sufficient.
In particular, when used as an exposure light source in an exposure head or the like, high luminance characteristics are required, and further improvement in controllability is required for controllability of the pixel region, pixel area, and light emission characteristics in the pixel. Have been intensively studied.

  By the way, such an organic electroluminescence element is covered with a sealing portion made of glass having a bathtub shape. The sealing portion is provided so as to cover at least the entire surface of the organic electroluminescence element, and the outer peripheral portion thereof is bonded to a glass substrate or the like using an adhesive. As will be described later, organic electroluminescence devices in which the light-emitting layer is composed of a low-molecular organic material layer dislikes high temperatures and thermosetting adhesives require a long curing time. For example, a photo-curing resin that is cured by irradiation with ultraviolet rays is frequently used.

  When a direct current voltage or direct current is applied through an electric circuit (not shown) with the anode of the organic electroluminescence element having the above configuration as a positive electrode and the cathode as a negative electrode, the organic material layer is connected to the organic material layer through the hole transport layer. Holes are injected and electrons are injected from the cathode into the organic material layer. As a result, recombination of holes and electrons occurs in the organic material layer that constitutes the light emitting layer sandwiched between the anode and the cathode, and the excitons generated thereby shift from the excited state to the ground state. Luminous phenomenon occurs. (Such a portion sandwiched between at least the anode and the cathode and substantially contributing to light emission is hereinafter referred to as a “light emitting portion”.)

  As described above, the organic electroluminescence element has a very simple structure, and is attracting attention as a technique that can be mass-produced and can be expected to reduce the cost and increase the area of a display device such as a display.

  On the other hand, however, one of the challenges of organic electroluminescence devices is that the light emitting region shrinks (shrinks) over time when it is affected by moisture, or a non-light emitting region (dark spot) occurs in the light emitting region. It has been known. In order to prevent the occurrence or expansion of shrinking and dark spots, it is necessary to keep the organic electroluminescence element in a low humidity state. As described above, the organic electroluminescence element is sealed with a sealing portion such as glass. Such a method is used that the internal space of the sealing region is decompressed or pressurized, or is filled with a low-humidity inert gas. In order to further enhance the sealing effect, a desiccant is provided in a bathtub-like space formed by being covered with the glass body as described above, or a material having an adsorbing action is mixed in the adhesive. In some cases.

  Recently, for example, a so-called gas barrier laminate having a laminated structure of an organic layer made of a resin and an inorganic layer made of a metal oxide has been researched and developed as a sealing portion of an organic electroluminescence element. As an example of such a gas barrier laminate, a manufacturing method disclosed in Patent Document 1 is known. In Patent Document 1, “(Omitted) Many studies have been made on the lamination of an inorganic film, a single layer of an organic film, or an organic film / inorganic film gas barrier layer. As a result, a metal oxide film, a metal nitride film, or a metal film is provided on a substrate such as a film, an organic layer made of a thermosetting resin is laminated thereon, and a second layer is formed on the organic layer. In the gas barrier laminate provided with the metal oxide film, the metal nitride film, or the metal film, the first curing is performed in the range of 120 ° C. to 180 ° C. immediately after the organic layer as the intermediate layer is laminated, and the second After the metal oxide film, the metal nitride film, or the metal film is provided, the second thermosetting is performed in the range of 180 ° C. to 240 ° C., whereby an inorganic film, a single layer of the organic film, or an organic film / inorganic film gas barrier is formed. In such lamination layers expression is to be able to acquire a gas barrier property is difficult.

  As another approach related to sealing technology, for example, a method for manufacturing a light emitting device disclosed in Patent Document 2 is known. In Patent Document 2, as a sealing adhesive for laminating a glass substrate and a sealing portion, a thermosetting (or thermoplastic) resin is made to contain a photothermal conversion substance (that is, a substance that absorbs infrared rays or near infrared rays). By irradiating this with laser light and locally heating the part where the sealing part is to be bonded, sealing is generally performed without damaging the organic electroluminescence device having heat resistance of 100 ° C. to 120 ° C. Can be done.

Tan (C.W. Tang), S.A. Vanslyke, "Appl. Phys. Lett." (USA), Vol. 51, 1987, p. 913 JP 2004-181793 A JP 2001-237066 A

Organic electroluminescence elements are simpler to manufacture than inorganic devices, so the cost of applications such as light-emitting element substrates equipped with organic electroluminescence elements and exposure devices that use organic electroluminescence elements as light sources is reduced. It is said to be advantageous. However, in the method of Patent Document 1, there are processes having a plurality of temperature controls in the manufacturing process, which causes a decrease in productivity. Further, such sealing with a rigid material such as a metal can or glass is excellent in the shielding effect from moisture and oxygen, but requires a height, and it is difficult to reduce the size and thickness. In addition, since glass cans have low mechanical strength and impact resistance, it has been difficult to increase the size and thickness. In addition, the metal can is superior in mechanical strength and impact resistance compared to the glass can, but it has a large difference in thermal expansion coefficient from the substrate, and it is extremely difficult to increase the size.
Further, the manufacturing method of Patent Document 2 also has a problem in terms of cost because the manufacturing equipment is large because local sealing is performed using laser light.

  Further, in an actual configuration of an organic semiconductor device substrate such as an organic electroluminescence element substrate, for example, an organic electroluminescence element, for example, a drive circuit constituted by TFT, a lead wiring, and the like are formed and arranged on the substrate, and the sealing portion is formed by these. Therefore, the sealing body tends to increase in size.

  For this reason, the sealing performance such as so-called gas barrier properties is greatly influenced by the surface state of the structure to be bonded, so that the outer periphery of the sealing portion is bonded to which part of any organic semiconductor device. This is an important factor for ensuring sealing.

  Under such circumstances, sealing with a resin film can reduce the height compared to glass or metallic cans, but sealing against corrosive substances such as moisture and oxygen The shut-off performance was not sufficient, which was a problem in practical use.

  On the other hand, if a metal is used as the sealing member, the coefficient of thermal expansion of the metal is larger than that of the glass substrate. There was a problem that occurred.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an organic semiconductor device capable of ensuring a sufficient barrier property against moisture and gas using a simple sealing process. To do.
It is another object of the present invention to provide an optical head and an image forming apparatus capable of obtaining a long-life, high-quality image using such an organic semiconductor device.

Therefore, the present invention is an organic semiconductor device in which an organic semiconductor element formed on a substrate is sealed with a metal material, and the metal material is a flexible metal material and is fixed to the substrate via an adhesive. It is characterized by that.
According to this configuration, since the metal material has flexibility, the progress of cracks is suppressed even when there is a temperature change in the use environment, and the element portion can be protected. In addition, the buffering effect of the adhesive is added, and the protection is further enhanced.

Moreover, this invention contains the said organic material in the said organic-semiconductor device whose thermal expansion coefficient is 10 <^-5> or less.
With this configuration, by setting the thermal expansion characteristics close to that of glass as a base material, thermal strain can be further reduced, and adhesion between the sealing portion and the glass substrate can be improved.

Moreover, this invention includes the said organic-semiconductor device in which the said metal material has a film thickness of 0.3 mm or less.
With this configuration, it is possible to ensure flexibility that can sufficiently absorb the volume change due to heat of the metal material, so it is possible to suppress thermal strain to a smaller level and improve the adhesion between the sealing portion and the glass substrate. Can measure. In the case of iron or nickel, it is better to be slightly thinner than aluminum, but thermal strain can be suppressed if it is 0.3 mm or less.

Moreover, the present invention includes the organic semiconductor device, wherein the metal material is a laminate with a resin layer.
With this configuration, it is possible to improve the moisture resistance and insulation of the sealing part itself and the corrosion resistance of the material.

In the organic semiconductor device according to the present invention, the adhesive is formed on the substrate so as to surround the organic semiconductor element, and is fixed to the substrate only in a region where the adhesive is formed. including.
With this configuration, since the adhesive acts as a buffer material, the occurrence of cracks can be prevented.

  In the organic semiconductor device, the substrate is a glass substrate, and includes an adhesive formed on the glass substrate so as to surround the organic semiconductor element, and the metal material includes the adhesive. In other words, only the region where the adhesive is formed is included on the glass substrate.

  The present invention includes the above organic semiconductor device, wherein the metal material is nickel or a nickel alloy.

  Moreover, this invention includes the said organic-semiconductor device in which the said metal material is iron or an iron alloy.

  Moreover, this invention includes the said organic-semiconductor device in which the said metal material is a nickel iron chromium alloy.

  The present invention includes the organic semiconductor device, wherein the resin layer is a coating film formed on the metal material.

  Moreover, the present invention includes the above organic semiconductor device, wherein the organic semiconductor element is covered with a sealing resin, and a metal material is disposed outside the sealing resin.

  In the organic semiconductor device according to the present invention, the organic semiconductor element includes first and second electrodes formed on the glass substrate and a layer having a light emitting function interposed therebetween. And an organic electroluminescent device including a functional layer.

  In addition, the present invention includes the above organic semiconductor device including a light amount detection element formed on the glass substrate and an organic electroluminescent element laminated on the light amount detection element.

  In the organic semiconductor device, the present invention includes an organic electroluminescent element and a light amount detection circuit that detects light output from the organic electroluminescent element. A detection element; a capacitance element connected in parallel to the photodetection element; and a switching thin film transistor connected to the capacitance element for controlling reading of the capacitance element, wherein the amount of light of the organic electroluminescent element is reduced. It is comprised so that it may detect, and at least the said photodetection element and the said organic electroluminescent element are sealed with the said metal material, and the thing which comprises an optical head is included.

  Moreover, this invention includes the said organic-semiconductor device in which the said organic electroluminescent element is formed in the shape of a line at the position spaced apart from the end surface of the said glass substrate.

  In the organic semiconductor device according to the present invention, the glass substrate includes regions exposed from the metal material at both ends of the element row of the organic electroluminescent element, and an inspection terminal is disposed in the region. Including

  Further, the present invention includes the organic semiconductor device, wherein the element row is configured to be supplied with power from both ends of the element row via jumper wires.

  In the organic semiconductor device according to the present invention, a driving IC chip for driving the light emitting element is mounted in a region exposed from the metal material on one side opposite to one side of the glass substrate. including.

  Moreover, this invention comprises the optical head comprised with the said organic-semiconductor device.

  The present invention also constitutes an image forming apparatus using the optical head as an exposure means for image formation.

  The present invention includes the optical head in which the light detection element is formed of the same layer as the thin film transistor serving as a drive circuit for the electroluminescence element. By forming the thin film transistor and the photodetecting element from the same layer using a processing method such as etching, the manufacturing process of the optical head can be simplified and the cost required for manufacturing can be reduced. In particular, the process of forming a polycrystalline silicon layer on a glass substrate goes through a high-temperature process, but it is possible to obtain highly controllable and highly reliable characteristics by a single adjustment.

The present invention also provides an image forming apparatus including the above-described optical head. By mounting an optical head having a uniform light emission distribution, an image forming apparatus excellent in terms of durability and image quality can be obtained.
Here, the first electrode formed on the light detection element side of the electroluminescence element is usually an anode, and is made of a light-transmitting electrode material.

In the organic semiconductor device of the present invention, since it is sealed with a flexible metal material, the moisture resistance is high, the occurrence of cracks due to temperature changes is suppressed, and the element portion can be protected. .
In the optical head of the present invention, since the organic electroluminescence element is covered and protected by the metal film together with the thin film transistor constituting the light detection circuit, the light amount can be detected with high accuracy and high reliability.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
Next, the organic electroluminescence element of Embodiment 1 of the present invention will be described with reference to FIG. In the present embodiment, a flexible metal material 64 formed by laminating a resin film made of polyethylene terephthalate, polyethylene naphthylate, polyethylene, polypropylene, polystyrene or the like on an Ni—Fe alloy foil having a thickness of 0.3 μm is epoxy-based. It is fixed to the substrate 100 via an adhesive 63 made of resin to constitute a sealing portion.
The organic electroluminescence element has a usual structure, but in this embodiment mode, a metal oxide thin film is formed as a charge injection layer 115 on the light-transmitting anode 111 formed on the light-transmitting substrate 100. to form a MoO ₃ is, a buffer layer 116 having the electron blocking function on this, sequentially laminating a polymer material as a light emitting layer 112, to form a cathode 113 on this. The surface of the organic electroluminescence element is covered with a passivation film 117.

  When a DC voltage or a DC current is applied with the anode 111 of the organic electroluminescent element as a positive electrode and the cathode 113 as a negative electrode, holes are injected into the light emitting layer 112 from the anode 111 through the charge injection layer 115. At the same time, electrons are injected from the cathode 113 and blocked by the buffer layer 116, and charged particles are efficiently present in the light emitting layer. In the light emitting layer 112, the holes and electrons injected in this manner are recombined, and a light emission phenomenon occurs when excitons generated along with the recombination shift from the excited state to the ground state.

According to the organic electroluminescent element of this embodiment, since the hole injection effect by the MoO ₃ layer is high, uniform light emission characteristics can be obtained.

Next, the manufacturing process of the organic electroluminescent element of this invention is demonstrated.
First, an ITO thin film is formed on the glass substrate 100 by sputtering using a sputtering method, and then a MoO ₃ layer as a metal oxide thin film is formed by vacuum deposition. Alternatively, an ITO thin film is formed on the glass substrate 100 by sputtering. Patterning is performed by photolithography, and then a metal oxide thin film is formed by vacuum deposition, and these are patterned by photolithography or a mask to form the anode 111 and the charge injection layer 115.

  Then, the buffer layer 116 and the light emitting layer 112 are formed thereon by a coating method such as screen printing or spin coating.

  Finally, the cathode 113 (113a, 113b) is formed. At this time, the outer side is further covered with a passivation film 117. The passivation film 117 may be omitted when the metal material is a flexible film in which an insulating resin layer is laminated inside.

As described above, according to the method of the present invention, since the metal material has flexibility, the progress of the crack is suppressed even when the use environment has a temperature change, and the element portion can be protected. Become. In addition, the buffering effect of the adhesive is added, and the protection is further enhanced. It is known that the Ni—Fe alloy used here can adjust the thermal expansion coefficient between about 10 ⁻⁷ and 10 ⁻⁴ by changing the composition ratio of Ni and Fe. When glass is employed as the substrate 100, the glass generally has a coefficient of thermal expansion of about 10 ⁻⁶ and can be included in the adjustment range of the coefficient of thermal expansion of the metal material used for sealing. When a resin is used as the substrate 100, for example, even when a resin having a high hardness and a relatively low thermal expansion coefficient (10 ⁻⁵ ) such as polycarbonate is selected, the thermal expansion coefficient of the metal material is adjusted. Can be included in the range. Thus, the thermal expansion coefficients of the base material 100 and the metal material used for sealing are both small enough to satisfy 10 ⁻⁵ or less, and the mutual thermal expansion coefficients are close to each other. By doing so, thermal strain can be further reduced, and the adhesion between the sealing portion and the substrate 100 can be improved.
In the case of an alloy of iron and nickel, the composition ratio of 30% to 65% of nickel is low expansion and can be used in the present invention. More preferably, the composition ratio of nickel is 36. It may be in the range of 42% to 42%. This metal material becomes extremely close to the thermal expansion coefficient of the glass described above, and is more desirable as a flexible metal material 64 material. Furthermore, in the case of this composition ratio, the thermal expansion coefficient of silicon nitride employed in a protective film constituting an organic electroluminescent element, which will be described in detail later, is very close, improving the reliability of the entire organic semiconductor device. Therefore, it is more suitable.

Further, by forming the light emitting layer 112 on the electronic block layer 116 by screen printing, it is easy to manufacture and can be miniaturized and highly integrated. In the present embodiment, the MoO ₃ layer also functions as an electron blocking layer.

The molybdenum oxide thin film in this embodiment is an amorphous thin film manufactured by vacuum deposition. The environment during vacuum deposition is a reducing atmosphere, and molybdenum oxide undergoes reduction in the process of being heated and sublimated and deposited on the substrate. The reduced molybdenum oxide produces some oxides with a smaller oxidation number in addition to hexavalent MoO ₃ . They are, for example, tetravalent MoO ₂ and trivalent Mo ₂ O ₃ . Since receiving is equivalent to receiving electrons, an oxide having a reduced valence is more likely to release electrons than an oxide having a higher valence, that is, more likely to receive holes. This is equivalent to having a higher energy level.

As described above, the sealing portion further completely covers the cathode 113.
Here, a thermosetting resin is used as the adhesive 63. As the thermosetting resin, an epoxy resin and an acrylic resin are generally used, but an epoxy resin is adopted in consideration of a small heat shrinkability and a small degassing. In fixing the metal material 64 on the glass substrate 100 to form the sealing portion, a thermosetting resin is applied onto the glass substrate 100 using a dispenser. However, the application speed of the dispenser and the thermosetting resin The adhesive 63 can be formed to a predetermined thickness by adjusting the supply amount.

  In addition, as a coating method of a thermosetting resin, it is not limited to the above-mentioned dispenser. Although the curing conditions vary depending on the thermosetting resin used, it is desirable to perform heat treatment at 100 ° C. for 1 hour as the first curing temperature, and then heat treatment at 150 ° C. for another hour. . In order to relieve stress due to rapid heating, it is desirable to perform temperature-cure curing step by step.

  In the above embodiment, an epoxy resin is used as the thermosetting resin, but other than that, polycarbonate, polymethyl methacrylate, polyacrylate, methyl phthalate homopolymer or copolymer, polyethylene terephthalate, polystyrene, diethylene glycol bisallyl carbonate Acrylonitrile / styrene copolymer, poly (-4-methylpentene-1), phenol resin, cyanate resin, maleimide resin, polyimide resin, acrylic resin, and the like. Polyvinyl butyral, acrylonitrile-butadiene rubber, Thermosetting resins modified with functional acrylate compounds, modified with thermoplastic resins such as crosslinked polyethylene resin, crosslinked polyethylene / epoxy resin, polyphenylene ether / cyanate resin It is also possible to use such. A plurality of types of resins as listed above may be used in combination. In addition, even if it is a photocurable resin, if a hardening accelerates | stimulates by heating, it can be used.

  Further, the higher the glass transition temperature of the thermosetting resin, the higher the hardness of the resin after curing, so that the adhesive strength is reduced, which causes peeling from the substrate due to external or internal stress. Therefore, if the glass transition temperature of the resin is high, the sealing performance is not improved. On the other hand, a resin having a low glass transition temperature has a low adhesion strength inside the resin, resulting in a decrease in confidentiality. Considering these, it is desirable to select a resin having a glass transition temperature in the range of 140 ° C to 180 ° C.

  Further, an inorganic filler (filler) may be added to the resin itself in order to improve the moisture permeability of the resin. By adding an inorganic filler, it is possible to lengthen the infiltration path of moisture, gas, etc. that permeate the inside of the resin. In addition, in order to suppress damage to the polymer organic electroluminescence as much as possible by degassing from the resin, there are few solvents and reaction initiators, etc., and degassing that is accelerated by temperature change and the ability to adsorb moisture from the outside It is desirable to have a filler. As the filler (filler), silica gel, alkali rare earth oxides such as calcium oxide and barium oxide, alumina, aluminosilicate, diatomaceous earth, etc. are used. However, in terms of moisture absorption performance and dispersion formation, silica gel and resin are used. It is desirable to use polyethylene terephthalate or polyethylene. The content of the hygroscopic agent is 5 to 40% by weight, but is preferably 30 to 40% by weight considering the strength of the resin. Further, by increasing the thickness of the resin layer, the moisture absorption performance can be improved, and a resin having a thickness in the range of 20 to 100 μm, desirably 30 to 50 μm is used.

  In the above embodiment, the metal material is a single Ni—Fe foil, but it may be a laminate of the metal material and the resin layer, and has a two-layer structure, so that the moisture resistance of the sealing portion itself is improved. Can be increased. Furthermore, by using two or more layers, the thickness of the metal material (metal layer) per layer can be reduced, so that the flexibility of the material can be increased.

  Further, according to the present invention, if the metal material is fixed to the glass substrate only in a region where the adhesive is formed via the adhesive, the adhesive acts as a buffering agent. , It is possible to extend the service life.

In the organic semiconductor device according to the present invention, nickel, nickel alloy iron, iron alloy, or nickel iron chromium alloy may be used as the metal material instead of Ni-Fe. At this time, as a metal material having a thermal expansion coefficient of 10 ⁻⁶ or less, an alloy of iron and nickel or a three-element alloy of iron, nickel and cobalt is used, but the expansion coefficient is selected by changing the composition. I can do it. In the case of a three-element alloy of iron, nickel, and cobalt, an alloy that is 29% nickel and 17% cobalt and the remainder is iron is desirable as the flexible metal material 64 because it has a thermal expansion coefficient close to that of glass or silicon nitride.

In forming the metal material, a coating film may be formed on the metal material. By forming by coating or painting, the cost can be greatly reduced as compared to laminating films.
Further, as the metal material, aluminum, stainless steel, metal material such as iron, nickel, cobalt, or material plastic processed with excellent malleability such as Cu can be used. At this time, when the metal material is aluminum or an aluminum alloy, the thickness of the metal material including the coating film is 50 μm or less in the range of 0.005 to 0.3 mm, and the sealing material is flexible. Desirable for imparting sex. In the case of iron or nickel, it is better to be slightly thinner than aluminum, but it should be 0.3 mm or less.
(Embodiment 2)

FIG. 2A is a schematic plan view showing the main part of the optical head main body used in the exposure apparatus of the image forming apparatus according to Embodiment 2 of the present invention. FIG. 2B is a cross-sectional explanatory view taken along the line AA in FIG. 2A, and FIG. Hereinafter, in this embodiment, processing by dicing will be described.
As shown in FIG. 2, the optical head main body includes a substrate 100 made of a glass substrate, a photodetector circuit (pixel circuit) C including a photodetector element 120 on the substrate 100, and a light emitting element. The switching thin film transistor 130 which is a part of the photodetection circuit is formed on the end face side of the substrate 100 with respect to the light emitting element array, and the upper layer is formed with an adhesive 63. It is covered and the sealing metal film 64 is fixed through the adhesive 63.

  In the dicing process, if a crack occurs in the substrate 100, the semiconductor layer made of polycrystalline silicon constituting the thin film transistor is peeled off or deteriorated, and the device characteristics are likely to be deteriorated. The semiconductor layer (the thin film transistor 130) can be reliably protected and the reliability can be improved.

In the manufacture, as shown in FIG. 3 (a), on a glass base material called mother glass G _M, the polycrystalline silicon layer is deposited, after the patterning step and the doping step, an insulating film, a metal film such as And a light detection circuit including the light detection element 120 and an element portion such as a light emitting element. The formation of the element portion will be described later.

Thereafter, as shown in FIG. 3B, an adhesive 63 is applied to the region including the thin film transistor 130. It is desirable that the application area of the adhesive 63 be separated from the end face of the glass substrate 100 by about 1 mm. Although FIG. 2B is a sectional view, it is not drawn, but the adhesive 63 is actually applied along the entire circumference of the sealing metal film 64.
And as shown in FIG.3 (c), the metal film 64 for sealing is mounted | worn.

Then, as shown in the plan view of FIG. 4, dicing is performed along the dicing line DL, and the optical head main body shown in FIG. 1 is divided.
At this time, since the thin film transistor 130 is covered with the adhesive 63, cracks are likely to occur due to stress applied during dicing. However, since the thin film transistor constituting the photodetection circuit is covered with the adhesive, the crack progresses. In addition to being able to be suppressed, the photodetector circuit is protected with an adhesive, and reliability can be improved. Moreover, since the thin film transistor is covered with the adhesive when the sealing metal film is mounted, the stress at the time of mounting the sealing metal film is relieved, and the generation of cracks is prevented.

In the second embodiment, after the sealing metal film 64 is mounted, dicing is performed to divide each optical head main body portion. However, as shown in FIG. cut the mother glass G _M before mounting, after splitting, it may be mounted a metal film for sealing. In this case, a heat-meltable resin material may be used as an adhesive, and after applying the adhesive, dicing may be performed, and thermocompression bonding may be performed with the sealing metal film placed on the adhesive. . In this case, since dicing is covered with an adhesive, the progress of cracks during dicing is suppressed. Also in this case, since the thin film transistor is covered with the adhesive when the sealing metal film is mounted, the stress at the time of mounting the sealing metal film is relieved and the generation of cracks is prevented.
In the second embodiment, the adhesive is formed in a line shape. However, the adhesive is formed on the entire lower surface of the sealing metal film 64 so as to include a position separated from the end face of the substrate by a predetermined distance, for example, a position separated by 1 mm or more. It may be formed in a solid shape.
Further, in order to relieve stress during dicing, it is desirable that the adhesive be separated from the end face of the substrate by 1 mm or more, so that the end region not covered with the adhesive becomes the stress relieving region. This suppresses the generation of stress during dicing. Even if a crack is generated in this region, the progress of the crack is prevented by the adhesive, and the reliability can be improved.

(Embodiment 3)
Details of the optical head of the present invention and an image forming apparatus using the same will be described below.
FIG. 6 is a schematic plan view showing the main part of the optical head used in the exposure apparatus of the image forming apparatus according to the embodiment of the present invention. FIG. 7A is a sectional view taken along the line AA in FIG. 6, FIG. 7B is a sectional view taken along the line BB in FIG. 6, and FIG. This optical head is a light composed of a photodiode that arranges an element array composed of a plurality of organic electroluminescence elements as the light emitting elements 110 on the glass substrate 100 and detects light output from the light emitting elements 110. A detection element 120; a light quantity detection circuit C connected to the output of the light detection element 120 for detecting the light quantity of the light emitting element 110; a light quantity calculation circuit 150 for calculating the light quantity based on the output of the light quantity detection circuit C; The optical head includes a drive circuit 160 that controls the drive of the element 110, and the light amount detection circuit C includes a capacitive element 140 connected in parallel to the photodetector element 120, and a capacitive element 140 connected to the capacitive element 140. A switching thin film transistor 130 that controls reading of the light, and a selection transistor 130 and a light detection element 120 , They are spaced apart across the capacitive element 140. Here, the selection transistor 130, the capacitor element 140, and the light detection element 120 are sequentially arranged in a direction orthogonal to the element row of the light emitting element 120. The selection transistor 130 is connected to a processing circuit unit including a light amount calculation circuit.

  The light detection element 120 is a thin film transistor that uses the first electrode 111 positioned on the light detection element 120 side of the organic electroluminescence element 110 that is a light emitting element as a gate electrode, and selects light amount reading of the light amount detection circuit. It is composed of a polycrystalline silicon layer formed in the same process as the switching thin film transistor 130 for selecting timing. Thus, the thin film transistor (photodetection element) 120 for detecting the light amount and the switching thin film transistor 130 for signal selection are formed at the same time with good workability. It is arranged to be separated from the photodetecting element 110 by 140 minutes, so that it is possible to prevent a malfunction due to a change in threshold value due to incidence of light on the switching thin film transistor 130. In addition, the capacitor element 140 is formed by forming three layers of electrodes so as to face each other two layers through an interlayer insulating film. Therefore, the capacitor element 140 has a high light shielding property and can surely prevent stray light, thereby preventing malfunction. Therefore, it is possible to efficiently detect a photocurrent, which is a minute current, and to detect a light amount with high accuracy and high reliability.

Furthermore, the light quantity detection circuit C is arranged separately from the drive circuit 160 with the element row of light emitting elements interposed therebetween. By using this configuration, the light amount detection circuit that handles minute currents is arranged separately from the drive circuit that handles relatively large currents, avoiding the effects of noise and performing highly accurate light amount detection. Is possible.
The light amount detection circuit C includes a capacitive element 140 connected in parallel to the light detection element 120, a switching thin film transistor 130 including a thin film transistor, and a light amount calculation circuit (IC) 150 that is a processing circuit unit including the light amount calculation circuit. It is configured.
The driving circuit 160 includes a switching thin film transistor formed of a polycrystalline silicon layer 161 (161c, 161S, 161D) and a driving IC chip (not shown).

That is, the optical head according to the present embodiment has a photodetecting element on a glass substrate 100 on which a base coat layer 101 for flattening is formed, as shown in cross-sectional views in FIGS. 120 and the electroluminescence element 110 are sequentially stacked, and a thin film transistor as the switching transistor 130 for driving the electroluminescence element while correcting the driving current or the driving time according to the output of the light detection element 120, A driving circuit (160) as a chip IC connected to the thin film transistor is mounted. The photodetector element 120 is the source region 121S by doping the desired concentration at a channel region formed of the island region A _R of polycrystalline silicon layer formed on the base coat layer 101 surface of a strip-shaped i layer, a drain A source made of a polycrystalline silicon layer formed through a through hole so as to penetrate the first insulating film 122 and the second insulating film 123 made of a silicon oxide film formed in the region 121D and over the region 121D. And drain electrodes 125S and 125D. Further, an electroluminescent element 110 is formed on the upper layer through a silicon nitride film as a protective film 124, and an ITO (indium tin oxide) 111 serving as an anode as a first electrode, a protective film 124, light emission Each layer is formed in the order of the layer 112 and the cathode 113 as the second electrode. Here, the insulating film defining the light emitting region corresponds to this protective film.

  Further, as shown in FIG. 7B for the wiring, the capacitor element 140 includes a first layer electrode 141 formed of a polycrystalline silicon layer and a second layer formed in the same process as the gate electrode 133 of the selection transistor. The capacitor is formed by sandwiching the first insulating film 122 described above with the electrode 142 and sandwiching the second insulating film 123 between the second layer electrode and the third layer electrode. The capacitor 140 is composed of a conductive material of three layers, that is, a first layer electrode 141, a second layer electrode 142, and a third layer electrode 143, and an insulating film. Since these three layers of electrodes are formed in an overlapped state, if they are made of a light shielding material, they act as a light shielding film having a triple structure. Due to this existence, the source / drain regions of the thin film transistors constituting the switching thin film transistor 130 Since it can be formed in the same process as any of the gate electrodes, the process can be simplified. Alternatively, a conductive material having a desired light-shielding property may be used, and the conductive material may be formed in a separate process from the selection transistor.

On the other hand, each layer constituting the photodetecting element 120 is formed in the same manufacturing process as the selection transistor 130 as a driving transistor. That is, the source regions 132S and 132D are formed in the same process as the semiconductor island of the photodetecting element with the channel region 131C interposed therebetween, and the source / drain electrodes 134S and 134D in contact therewith are stacked, and the gate electrode 133 serves as a selection transistor. The thin film transistor is configured.
Each of these layers is formed through a usual semiconductor process such as formation of a semiconductor thin film by a CVD method, patterning by photolithography, impurity ion implantation, and formation of an insulating film.

  Here, the glass substrate 100 is a single plate of colorless and transparent glass. Examples of the glass substrate 100 include transparent or translucent soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz glass, and other inorganic oxide glasses, inorganic fluorides Inorganic glass such as glass can be used.

Other materials may be used as the glass substrate 100, for example, transparent or translucent polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyether sulfone, polyvinyl fluoride, polypropylene, polyethylene, polyacrylate, polyether sulfone. , Cycloolefin polymer, polyamide, polyethylene naphthalate amorphous polyolefin, polymer film using polymer materials such as fluororesin polysiloxane, polysilane, etc., these plastic films and sheets with silicon oxide, aluminum oxide, silicon nitride metal oxide And metal oxides such as silicon oxide, aluminum oxide, chromium oxide and magnesium oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, silicon nitride and aluminum nitride Metal nitrides such as chromium nitride, metal oxynitrides such as silicon oxynitride, metal materials such as aluminum, copper, nickel, and stainless steel, polymer resin films such as acrylic resin, epoxy resin, silicone resin, and polyester resin The light-transmitting property can be used as a single layer or a stacked layer as long as there is no hindrance to the translucency. Alternatively, transparent or translucent chalcogenoid glass such as As ₂ S ₃ , As ₄₀ S ₁₀ , S ₄₀ Ge ₁₀ , ZnO, Nb ₂ O, Ta ₂ O ₅ , SiO, Si ₃ N ₄ , HfO ₂ , TiO _2. In the case of taking out the light emitted from the light emitting region without passing through the substrate, such as a metal oxide such as metal oxide and nitride, a semiconductor material such as opaque silicon, germanium, silicon carbide, gallium arsenide, gallium nitride, Alternatively, the transparent substrate material containing a pigment or the like, a metal material having a surface subjected to insulation treatment, or the like can be appropriately selected and used, and a laminated substrate in which a plurality of substrate materials are laminated can also be used.

  Further, a circuit including a resistor, a capacitor, an inductor, a diode, and a transistor for driving the electroluminescence element 110 may be integrated on the surface of the substrate such as the glass substrate 100 or inside the substrate, as will be described later. .

  Further, depending on the application, a material that transmits only a specific wavelength, a material that converts light into a specific wavelength having a light-light conversion function, or the like may be used. The substrate is preferably insulative, but is not particularly limited, and may have conductivity depending on a range or use that does not hinder driving of the electroluminescent element 110.

A base coat layer 101 is formed on the glass substrate 100. The base coat layer 101 is composed of, for example, a first layer made of SiN and a second layer made of SiO ₂ . Each layer of SiN and SiO ₂ can be formed by vapor deposition or the like, but is preferably formed by sputtering.

On the base coat layer 101, the selection transistor 130 of the electroluminescence element 110 and the light detection element 120 are formed using a polycrystalline silicon layer formed in the same process. The driving circuit of the electroluminescence element 110 is composed of circuit elements such as a resistor, a capacitor, an inductor, a diode, and a transistor. In consideration of downsizing of the optical head, it is desirable to use a thin film transistor. In Embodiment 3, the photodetecting element 120 is located between the electroluminescent element 110 including the light emitting layer 112 and the glass substrate 100 serving as the light output surface, as is apparent from FIG. 110 of the element region _{a R} is larger than the light emission region _{a LE.} Further, since the light emission region A _LE exists inside the light detection element 120, a material that does not transmit light cannot be used for the light detection element 120. Therefore, in order not to disturb the light output from the light emitting layer 112, a material having a light transmitting property must be used for the light detection element 120. As a material of the light detecting element 120 having translucency, it is desirable to select, for example, polycrystalline silicon.

In Embodiment 3, after a uniform semiconductor layer is formed over the base coat layer 101, the semiconductor layer is etched using photolithography, so that the selection transistor 130 and the light detection element 120 are formed in the same layer. Formed from. The process of forming the selection transistor 130 and the semiconductor layer of the photodetecting element 120 independent from each other in the form of islands from the same semiconductor layer is advantageous in reducing the number of manufacturing steps and the manufacturing cost. Note in the photodetector element 120, the element region A _R for receiving the light output from the light emission region A _LE is polycrystalline silicon or amorphous silicon that is configured in an island shape having a light-detecting element 120.

On the selection transistor 130 and the photodetecting element 120 for applying an electric field to the light emitting layer 112 of the electroluminescent element 110, the first insulating layer 122, the second insulating layer 123 and the protective film 124 made of this silicon oxide film are provided. Acts as a gate insulating film with the ITO 111 as the anode of the electroluminescence element, and the drop width from the potential of the ITO is determined by the voltage drop due to this film thickness. The first insulating layer 122, the second insulating layer 123, and the protective film 124 constituting the gate insulating film are made of, for example, SiO _{2 and} are formed by vapor deposition, sputtering, or the like.

  A gate electrode 131 is formed on the surface of the first insulating layer 122 as a gate insulating film directly above the selection transistor 130. For example, Cr is used as the material of the gate electrode 131. The gate electrode 131 is formed by vapor deposition, sputtering, or the like.

  A second insulating layer 123 is formed on the substrate surface on which the gate electrode 131 is formed. The second insulating layer 123 is formed over the entire surface of the stacked body that has been formed so far. The second insulating layer 123 is made of, for example, SiN or the like, and is formed by a vapor deposition method, a sputtering method, or the like.

  On the second insulating layer, a drain electrode 125D as a light detection element output electrode, a source electrode 125S as a light detection element ground electrode, a source electrode 134S, and a drain electrode 134D are formed. The drain electrode 125D as the light detection element output electrode and the source electrode 125S as the light detection element ground electrode are connected to the source / drain regions 121S and 121D of the light detection element 120, and an electric signal output from the light detection element 120. Transmission and grounding of the light detection element 120. The source electrode 134S and the drain electrode 134D are connected to the source / drain regions 132S and 132D of the selection transistor 130, and the gate electrode 133 described above is applied with a predetermined potential difference between the source electrode 134S and the drain electrode 134D. By applying a predetermined potential, an electric field is applied to the channel region 132C, and the selection transistor 130 has a function as a switching element, and operates as a circuit for driving the electroluminescence element 110 as a light-emitting element. For example, a metal such as Cr is used as the material of the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D. As shown in FIG. 6, the drain electrode 125 </ b> D as the light detection element output electrode and the light detection element ground electrode pass through the first insulating film 122 and the second insulating layer 123 and are connected to the end of the light detection element 120. Similarly, the source electrode 134S and the drain electrode 134D penetrate the first insulating film 122 and the second insulating layer 123 and are connected to the end portion of the selection transistor 130. Therefore, prior to the formation of the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D, the first insulating film 122 and the second insulating layer 123 are formed. On the other hand, the drain electrode 125D as the light detection element output electrode and the source electrode 125S as the light detection element ground electrode and the through hole for connecting the light detection element 120, the source electrode 134S and the drain electrode 134D, and the selection transistor 130 are connected. It is necessary to provide a through hole for this purpose. The through holes are formed on the surface of the photodetecting element 120 and the surface of the selection transistor 130, that is, the contact surface between the photodetecting element 120 and the drain electrode 125D serving as the photodetecting element output electrode and the source electrode 125S serving as the photodetecting element ground electrode. 130 and has a depth until the contact surface of the source electrode 134S and the drain electrode 134D is exposed, and is provided by etching or the like directly above the ends of the photodetecting element 120 and the selection transistor 130. For the etching, a halogen-based etching gas is used. Etching gas is introduced and patterned by photolithography in a state where the surface is covered with a resist pattern having openings, thereby opening through holes in the first insulating film 122 and the second insulating layer 123. At this time, an etching gas that does not cause a chemical reaction with the materials constituting the light detection element 120 and the selection transistor 130 is selected. Processing to expose the contact surface between the source electrode 125S as the photodetection element output electrode and the source electrode 125S as the photodetection element ground electrode and the photodetection element 120 and the contact surface between the source electrode 134S and the drain electrode 134D and the selection transistor 130 is completed. After that, the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D are formed. The source electrode 134S and the drain electrode 134D are formed by forming a metal layer serving as a sensor electrode on the surface of the second insulating layer 123, the surface of the through hole and the both sensor electrodes, the surface of the light detection element 120, and the contact surface of the selection transistor 130. After uniformly forming on the surface, this metal layer is etched, and the uniform metal layer is drain electrode 125D as the photodetecting element output electrode, source electrode 125S as the photodetecting element ground electrode, and source electrode 134S. And the drain electrode 134D.

  After the drain electrode 125D as the light detection element output electrode, the source electrode 125S as the light detection element ground electrode, the source electrode 134S, and the drain electrode 134D are formed, the protective film 124 is formed. The protective film 124 is made of, for example, SiN and is formed by vapor deposition, sputtering, or the like.

An anode 111 is formed on the protective film 124. The anode 111 is made of, for example, ITO (indium tin oxide). As the constituent material of the anode 111, IZO (zinc-doped indium oxide), ATO (Sb-doped SnO ₂ ), AZO (Al-doped ZnO), ZnO, SnO ₂ , In ₂ O _{3 and the} like are used in addition to ITO. be able to. As shown in FIG. 6, the anode 111 is formed on the surface of the protective film 124 that is directly above the photodetecting element 120. As shown in FIG. 6, the anode 111 penetrates the protective film 124 and is connected to the end of the drain electrode 134D. Therefore, before forming the anode 111, it is necessary to provide a through hole for connecting the anode 111 and the drain electrode 134D to the protective film 124. This through hole has a depth until the surface of the drain electrode 134D, that is, the contact surface between the drain electrode 134D and the anode 111 is exposed, and is provided directly above the end of the drain electrode 134D by etching or the like. It is done. After this etching process is performed, a layer of the anode 111 is formed. The anode 111 can be formed by vapor deposition or the like, but is preferably formed by sputtering. In Embodiment 3, ITO is used as the anode 111.

After the anode 111 is formed, a silicon nitride film 114 as a pixel restricting portion is formed. As a material of the silicon nitride film 114 as the pixel restricting portion, a material having high insulating properties, strong against dielectric breakdown, good film forming properties and high patterning properties is desirable. In the third embodiment, silicon nitride or aluminum nitride is used as a material constituting the silicon nitride film 114 as the pixel restricting portion. A silicon nitride film 114 serving as a pixel restricting portion is provided between a light emitting layer 112 and an anode 111, which will be described later, and insulates the light emitting layer 112 outside the light emitting area _ALE from the anode 111. The place where light is emitted is regulated. Therefore, the region of the light emitting layer 112 that overlaps the silicon nitride film 114 serving as the pixel restricting portion is a non-light emitting region, and the region that does not overlap the silicon nitride film 114 serving as the pixel restricting portion is the light emitting region A _LE . Silicon nitride film as the pixel restricting portion 114 restricts so that the light emission region _{A LE} of the light emitting layer 112 is smaller than the element region _{A R} of the light-detecting element 120, and the light emission region _{A LE} photodetection element 120 configured to be placed inside the element region a _R.

After the silicon nitride film 114 as the pixel restricting portion is formed, the light emitting layer 112 is formed. The light emitting layer 112 is formed of an inorganic light emitting material, or a high molecular weight or low molecular weight organic light emitting material described in detail below. As the inorganic light emitting material for forming the light emitting layer 112, titanium / potassium phosphate, barium / boron oxide, lithium / boron oxide, or the like can be used. As the polymer organic light emitting material constituting the light emitting layer 112, a material having fluorescence or phosphorescence characteristics in the visible region and good film forming property is desirable. For example, polymers such as polyparaphenylene vinylene (PPV) and polyfluorene are used. A light emitting material or the like can be used. In addition to Alq ₃ and Be-benzoquinolinol (BeBq ₂ ), low molecular organic light emitting materials constituting the light emitting layer 112 include 2,5-bis (5,7-di-t-pentyl-2). -Benzoxazolyl) -1,3,4-thiadiazole, 4,4'-bis (5,7-benzyl-2-benzoxazolyl) stilbene, 4,4'-bis [5,7-di- (2-Methyl-2-butyl) -2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-benzyl-2-benzoxazolyl) thiophine, 2,5-bis ( [5-α, α-dimethylbenzyl] -2-benzoxazolyl) thiophene, 2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl]- 3,4-diphenylthiophene, 2,5-bis (5-methyl-2 -Benzoxazolyl) thiophene, 4,4'-bis (2-benzoxazolyl) biphenyl, 5-methyl-2- [2- [4- (5-methyl-2-benzoxazolyl) phenyl] Benzoxazoles such as vinyl] benzoxazolyl, 2- [2- (4-chlorophenyl) vinyl] naphtho [1,2-d] oxazole, 2,2 ′-(p-phenylenedivinylene) -bisbenzothiazole Such as benzothiazole, 2- [2- [4- (2-benzimidazolyl) phenyl] vinyl] benzimidazole, 2- [2- (4-carboxyphenyl) vinyl] benzimidazole, etc. Whitening agent, tris (8-quinolinol) aluminum, bis (8-quinolinol) magnesium, bis (benzo [f] -8-quino Nor) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris (5-chloro-8- Quinolinol) gallium, bis (5-chloro-8-quinolinol) calcium, poly [zinc-bis (8-hydroxy-5-quinolinyl) methane] and other 8-hydroxyquinoline metal complexes and dilithium ependridione Metal chelated oxinoid compounds, 1,4-bis (2-methylstyryl) benzene, 1,4- (3-methylstyryl) benzene, 1,4-bis (4-methylstyryl) benzene, distyrylbenzene, 1 , 4-Bis (2-ethylstyryl) benzene, 1,4-bis (3-ethyl) Styryl) benzene, 1,4-bis (2-methylstyryl) 2-methylbenzene and other styrylbenzene compounds, 2,5-bis (4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) ) Pyrazine, 2,5-bis [2- (1-naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, 2,5-bis [2- (4-biphenyl) vinyl] pyrazine, Distil pyrazine derivatives such as 2,5-bis [2- (1-pyrenyl) vinyl] pyrazine, naphthalimide derivatives, perylene derivatives, oxadiazole derivatives, aldazine derivatives, cyclopentadiene derivatives, styrylamine Derivatives, coumarin derivatives, aromatic dimethylidin derivatives and the like are used. Furthermore, anthracene, salicylate, pyrene, coronene and the like are also used. Alternatively, a phosphorescent material such as fac-tris (2-phenylpyridine) iridium can be used. The light emitting layer 112 made of a high molecular weight material or a low molecular weight material can be obtained by forming a layer in which a material is dissolved in a solvent such as toluene or xylene by spin coating and volatilizing the solvent in the solution. .

  In Embodiment 3, the light-emitting layer 112 is described as a single layer for convenience, but the light-emitting layer 112 is sequentially formed from the anode 111 side with the hole transport layer / electron block layer / the above-described organic light-emitting material layer (both The light-emitting layer 112 may have a two-layer structure of an electron transport layer / organic light-emitting material layer (both not shown) in order from the cathode 113 side, or may be positive in order from the anode 111 side. 2 layer structure of hole transport layer / organic light emitting material layer (both not shown), or hole injection layer / hole transport layer / electron blocking layer / organic light emitting material layer / hole blocking layer / A seven-layer structure (both not shown) such as an electron transport layer / electron injection layer may be used. Alternatively, the light emitting layer 112 may have a single layer structure made of only the organic light emitting material described above. As described above, the light-emitting layer 112 in Embodiment Mode 3 includes a case where the light-emitting layer 112 has a multilayer structure having functional layers such as a hole transport layer, an electron block layer, and an electron transport layer. The same applies to other embodiments described later.

The hole transport layer in the functional layer described above preferably has a high hole mobility, is transparent and has good film-forming properties, and besides TPD, porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Or 1,1-bis {4- (di-P-tolylamino) phenyl} cyclohexane, 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetrakis ( P-tolyl) -P-phenylenediamine, 1- (N, N-di-P-tolylamino) naphthalene, 4,4′-bis (dimethylamino) -2-2′-dimethyltriphenylmethane, N, N, N ′, N′-tetraphenyl-4,4′-diaminobiphenyl, N, N′-diphenyl-N, N′-di-m-tolyl-4,4′-diaminobiphe Aromatic tertiary amines such as Nyl, N-phenylcarbazole, 4-di-P-tolylaminostilbene, 4- (di-P-tolylamino) -4 ′-[4- (di-P—) Stilbene compounds such as (tolylamino) styryl] stilbene, triazole derivatives, oxazizazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcones Derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, polysilane aniline copolymers, polymer oligomers, styrylamine compounds, aromatic dimethylidin compounds, Poly-3,4 ethylene glycol Organic materials such as polythiophene derivatives such as xylthiophene (PEDOT), tetradihexylfluorenylbiphenyl (TFB), and poly-3-methylthiophene (PMeT) are used. Further, a polymer-dispersed hole transport layer in which an organic material for a low-molecular hole transport layer is dispersed in a polymer such as polycarbonate is also used. There is also a _{MoO 3, V 2 O 5,} WO 3, TiO 2, SiO, also be an inorganic oxide such as MgO. These hole transport materials can also be used as an electron block material.

  Examples of the electron transport layer in the functional layer described above include oxadiazole derivatives such as 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7), and anthraquinodimethane derivatives. , Diphenylquinone derivatives, polymer materials composed of silole derivatives, bis (2-methyl-8-quinolinolate)-(para-phenylphenolate) aluminum (BAlq), bathopproin (BCP), and the like are used. Moreover, the material which can comprise these electron carrying layers can also be used as a hole block material.

  After the light emitting layer 112 is formed, the cathode 113 is formed. The cathode 113 can be obtained, for example, by forming a layer of metal such as Al by vapor deposition or the like. As the cathode 113 of the organic electroluminescence element 110, a metal or alloy having a low work function, for example, a metal such as Ag, Al, In, Mg, or Ti, a Mg alloy such as a Mg—Ag alloy or a Mg—In alloy, Al— An Al alloy such as a Li alloy, an Al—Sr alloy, or an Al—Ba alloy is used. Alternatively, a first electrode layer in contact with a metal such as Ba, Ca, Mg, Li, or Cs, or an organic material layer made of a fluoride or oxide of these metals such as LiF or CaO, and Ag formed thereon It is also possible to use a metal laminated structure including a second electrode made of a metal material such as Al, Ag, or In.

  The optical head of Embodiment 3 as shown in FIG. 7 employs a method of outputting light from the selection transistor 130 side of the organic electroluminescence element, and the structure of such an organic electroluminescence element is referred to as bottom emission. Since the bottom emission structure extracts light from the glass substrate 100 side, the light detection element 120 needs to be made of a highly transparent material, for example, polycrystalline silicon (polysilicon), as described above. The photo-detecting element 120 made of polycrystalline silicon has a problem that the photocurrent generation capability is lower than that made of amorphous silicon, but for example, a capacitor (not shown) is made organic. The problem can be solved by providing a processing circuit that is provided in the vicinity of the electroluminescence element 110 and stores a charge based on the current output from the light detection element 120 in a capacitor for a predetermined period of time and then performs voltage conversion. In the case of the bottom emission structure, since the electrode (anode) on the side from which light is extracted can be easily made transparent, there is an advantage that manufacture is simplified.

  FIG. 6 is a configuration plan view showing the configuration in the vicinity of the light detection element of the optical head according to Embodiment 3 of the present invention.

  As shown in FIGS. 6 and 7, the optical head according to the third embodiment is configured by arranging a plurality of electroluminescent elements 110 in the main scanning direction (element array direction). One photodetecting element 120 is arranged corresponding to the region. By setting it as such a structure, the light-emission quantity of each organic electroluminescent element 110 can be measured independently with the photon detection element 120. FIG. That is, it becomes possible to measure the light quantity of the plurality of organic electroluminescence elements 110 at the same time, and the measurement time can be greatly shortened.

  A feedback signal generated by the correction circuit is determined based on the electrical signal output from the light detection element, and processing necessary for light correction is performed based on the feedback signal. In the third embodiment, the light emission amount of each electroluminescent element 110 is corrected based on this feedback signal, and the current value for driving each electroluminescent element 110 is controlled by a driver circuit (not shown). Thus, in Embodiment 3, the amount of emitted light is controlled based on the output of the light detection element 120, but so-called PWM control is performed to control the drive time of each electroluminescence element 110 based on the feedback signal. It may be configured.

  The source electrode 125S as the light detection element ground electrode is an electrode for grounding the light detection element 120. An ITO (indium tin oxide) 111 which is an anode of the electroluminescence element 110 as a light emitting element is connected to the drain electrode 134D of the selection transistor 130, and the electroluminescence element 110 is connected to the selection transistor 130 via the drain electrode 134D. It is controlled.

As shown in FIG. 7, in the optical head of the third embodiment, photodetectors 120 made of polycrystalline silicon (polysilicon) formed in an island shape are arranged in a row in the main scanning direction. light detecting element having a large device area a _R than the light emission region a _LE at the bottom of the light-emitting layer 112 where the light emission region a _{LE is} limited by the silicon nitride film 114 serving as a pixel restricting portion in the organic electroluminescent device 110 120 is arranged. By making the element region A _R (island-like portion of polycrystalline silicon formed in an island shape) of the light detection element 120 larger than the light emission region A _LE, a local change in the layer thickness of the light-emitting layer 112 is suppressed. Thus, the bias of the current flowing through the light emitting layer 112 can be suppressed. Therefore, it is possible to manufacture an optical head that achieves a uniform light emission distribution and improved lifetime.

Furthermore, since the element region A _R of the light-detecting element 120 configured in an island shape to be mounted on the optical head of the third embodiment larger than the light emitting area or the light emission region A _LE, the output light from the light-emitting layer It can be efficiently converted into an electrical signal used for light correction.

  Next, a light amount correction circuit used in the optical head of the present invention will be described. As shown in an equivalent circuit in FIG. 8, the light amount correction circuit is formed by being integrated on the above-described glass substrate 100 so as to be connected to the driving IC 150 having a charge amplifier and the input terminal of the driving IC 150. The correction circuit unit C (pixel circuit 60 in FIG. 18) is configured by the switching transistor 130, the photodetecting element 120, and the photodetecting element, which are connected in parallel, and the output of the photodetecting element. It is comprised with the capacitor | condenser 140 which charges an electric current. Although not shown in the cross-sectional view of FIG. 6, the capacitor 140 is a conductive film formed in the same process so as to be connected to the source electrode 134S and the drain electrode 134D of the photodetecting element. It is formed by sandwiching the second insulating films 122 and 123.

Here, the photodetection element performs photoelectric conversion in the polycrystalline silicon layer (channel region) 121i by the light from the electroluminescence element, and detects the amount of light by taking out the current flowing from the source region to the drain region as a photocurrent. Is. However, as described above, the ITO electrode 111 that is the anode of the electroluminescence element 110 is used as a gate electrode, and an electric field is applied to the polycrystalline silicon layer that is the channel region 121i of the light detection element by the potential of the gate electrode. A drain current _ID flows. Since the drain current _ID is added to the photoelectric conversion current, the photoelectric conversion current output from the drain electrode 125D to the correction circuit unit C (see FIG. 8) as a sensor output is converted into the actual photoelectric conversion current. The current _ID is added. For this reason, there exists a problem that the light quantity detection accuracy falls. The result of measuring the relationship between the gate voltage Vg and the drain current ID is shown by a solid line in FIG. As is apparent from this figure, it is desirable to use the thin film transistor in a region where the drain current is 0, that is, a region where the transistor operation is turned off (OFF region).

Desirably, as indicated by the broken line in FIG. 9, the thin film transistor can be used in the OFF region by making the gate potential shift in the minus direction, and the dark current can be almost eliminated. In the present invention, since it is extremely important to detect the output of the light detection element with high accuracy, it is important to detect the thin film transistor constituting the light detection element in the OFF state.
In addition, the state in which the entire polycrystalline silicon layer that becomes the channel region 121i of the thin film transistor that constitutes the light detection element is completely covered with the ITO electrode that is the anode of the electroluminescence element is controlled by the gate electric field. It is valid.

As shown in the timing charts of FIGS. 10A to 10E, the output of the photodetecting element is obtained by charging the capacitor 140 with a desired number of lighting times of the electroluminescent element by switching the selection transistor 130. By taking out, it becomes possible to detect the amount of light with high accuracy. 10A is a diagram showing the state of charge, FIG. 10B is a diagram showing the operation of the selection transistor, FIG. 10C is a diagram showing the lighting timing of the electroluminescence element, and FIG. FIG. 10D is a diagram showing the potential of the capacitive element 140, and FIG. 10E is a diagram showing the output voltage of the operational amplifier.
First, the selection transistor 130 is turned on, and the capacitor 140 is charged with the initial voltage V _ref (S1: reset step).
When the selection transistor 130 is turned off, the charge charged in the capacitor element 140 is reduced by the photocurrent flowing through the light detection element 120 (S2: lighting step).
In this state, the switch SW of the charge amplifier 150 is turned OFF, and the charge amplifier is in a measurable state (S3: measurement start step).
Then, the selection transistor 130 is turned on, and the charge lost in the capacitor element 140 is supplied from the capacitor element C _ref of the charge amplifier. As a result, the output voltage V _r0 of the operational amplifier of the charge amplifier 150 increases. Also during this period, the photocurrent of the photodetecting element flows and _Vr0 increases (S4: charge transfer step).
Then, the selection transistor 130 is turned off and V _r0 is determined. This voltage is taken in by the AD converter and output as the output voltage Vout, and the photometric operation is completed (S5: read step).

  Based on the output voltage of the light detection circuit thus obtained, the light amount calculation circuit 150 calculates a correction voltage, and the voltage applied to the anode 111 and the cathode 113 of the light emitting element via the drive circuit 160 is controlled. A voltage is applied to the light emitting layer 112 formed between them to compensate for variations in the amount of light of the light emitting elements and variations in the amount of light accompanying changes over time, so that uniform exposure is maintained.

(Embodiment 4)
A fourth embodiment will be described. In the present embodiment, an image forming apparatus 1 using exposure apparatuses 13Y to 13K in which the optical head is formed for yellow, magenta, cyan, and black colors will be described. As shown in FIG. 11, the image forming apparatus 1 includes four color development stations, a yellow development station 2Y, a magenta development station 2M, a cyan development station 2C, and a black development station 2K, in a vertical direction. Arranged above the sheet feed tray 4 for storing the recording sheet 3 is disposed above the conveyance path of the recording sheet 3 supplied from the sheet feed tray 4 at locations corresponding to the developing stations 2Y to 2K. The recording paper transport path 5 is configured in the vertical direction from the top to the bottom.

  The developing stations 2Y to 2K form toner images of yellow, magenta, cyan, and black sequentially from the upstream side of the recording paper conveyance path 5, and the yellow developing station 2Y is photosensitive to the photoreceptor 8Y and the magenta developing station 2M. 8M, cyan developing station 2C includes a photosensitive member 8C, black developing station 2K includes a photosensitive member 8K, and each developing station 2Y to 2K includes a series of electrophotographic systems such as a developing sleeve and a charger described later. The member which implement | achieves the image development process is included.

  Further, exposure devices 13Y, 13M, 13C, and 13K for exposing the surfaces of the photoreceptors 8Y to 8K to form electrostatic latent images are disposed below the developing stations 2Y to 2K.

  The developing stations 2Y to 2K are different in the color of the filled developer, but the configuration is the same regardless of the development color. Therefore, the development is performed except when it is particularly necessary to clarify the following explanation. The description will be made without specifying a specific color as in the case of the station 2, the photoconductor 8, and the exposure device 13.

  FIG. 12 is a block diagram showing the periphery of the developing station 2 in the image forming apparatus 1 of the present invention. In FIG. 12, the developing station 2 is filled with a developer 6 which is a mixture of carrier and toner. 7a and 7b are stirring paddles for stirring the developer 6. The toner in the developer 6 is charged to a predetermined potential by friction with the carrier by the rotation of the stirring paddles 7a and 7b. The inside of 2 is sufficiently stirred and mixed. The photoreceptor 8 is rotated in the direction D3 by a driving source (not shown). A charger 9 charges the surface of the photoconductor 8 to a predetermined potential. Reference numeral 10 denotes a developing sleeve, and 11 denotes a thinning blade. The developing sleeve 10 has a magnet roll 12 having a plurality of magnetic poles formed therein. The layer thickness of the developer 6 supplied to the surface of the developing sleeve 10 is regulated by the thinning blade 11 and the developing sleeve 10 is rotated in the direction D4 by a driving source (not shown). The developer 6 is supplied to the surface of the developing sleeve 10 by the action of the above, and an electrostatic latent image formed on the photoconductor 8 is developed by an exposure device 13 described later, and the developer 6 not transferred to the photoconductor 8 is developed. Collected in the developing station 2.

  Reference numeral 13 denotes an exposure apparatus. The exposure device 13 has a light emitting element array in which organic electroluminescence elements as exposure light sources are arranged in a line at a resolution of 600 dpi (dot / inch), and the photosensitive member 8 charged to a predetermined potential by the charger 9 is provided. On the other hand, an electrostatic latent image of maximum A4 size is formed by selectively turning on / off the organic electroluminescence element according to the image data. When a predetermined potential (developing bias) is applied to the developing sleeve 10, a potential gradient is generated between the electrostatic latent image portion and the developing sleeve 10. Then, the Coulomb force acts on the toner in the developer 6 that is supplied to the surface of the developing sleeve 10 and is charged to a predetermined potential, and only the toner out of the developer 6 adheres to the photoreceptor 8, and electrostatic The latent image is visualized.

  As will be described in detail later, the exposure apparatus 13 is provided with a light detection element as a light quantity measuring means for measuring the light quantity of the organic electroluminescence element.

  Reference numeral 16 denotes a transfer roller. The transfer roller 16 is provided at a position facing the recording paper conveyance path 5 with respect to the photoconductor 8, and is rotated in the direction D5 by a driving source (not shown). A predetermined transfer bias is applied to the transfer roller 16, and the toner image formed on the photoconductor 8 is transferred to the recording paper 3 conveyed through the recording paper conveyance path 5.

  Subsequently, returning to FIG.

  A toner bottle 17 stores yellow, magenta, cyan, and black toners. A toner transport pipe (not shown) is provided from the toner bottle 17 to each of the developing stations 2Y to 2K, and supplies toner to each of the developing stations 2Y to 2K.

  Reference numeral 18 denotes a paper feed roller, which rotates in a direction D1 by controlling an electromagnetic clutch (not shown), and feeds the recording paper 3 loaded in the paper feeding tray 4 to the recording paper transport path 5.

  A registration paper 19 and a pinch roller 20 pair are provided as a nip conveyance means on the inlet side in the recording paper conveyance path 5 positioned between the paper supply roller 18 and the transfer portion of the most upstream yellow developing station 2Y. The registration roller 19 and the pinch roller 20 pair temporarily stop the recording paper 3 conveyed by the paper supply roller 18 and convey it in the direction of the yellow developing station 2Y at a predetermined timing. This temporary stop restricts the leading edge of the recording paper 3 in parallel with the axial direction of the registration roller 19 and pinch roller 20 pair, thereby preventing the recording paper 3 from skewing.

  Reference numeral 21 denotes a recording paper passage detection sensor. The recording paper passage detection sensor 21 is constituted by a reflective sensor (photo reflector), and detects the leading edge and the trailing edge of the recording paper 3 based on the presence or absence of reflected light.

  When the power transmission is controlled by an electromagnetic clutch (not shown) and the rotation of the registration roller 19 is started, the recording paper 3 is conveyed in the direction of the yellow developing station 2Y along the recording paper conveyance path 5, but the rotation of the registration roller 19 is started. Starting from the timing, the electrostatic latent image writing timing by the exposure devices 13Y to 13K arranged in the vicinity of the developing stations 2Y to 2K, development bias ON / OFF, transfer bias ON / OFF, etc. Be controlled.

  Hereinafter, the description will be continued with reference to FIG.

  Since the distance from the exposure device 13 shown in FIG. 12 to the development area (near the portion where the distance between the photoconductor 8 and the development sleeve 10 is the narrowest) is a design matter, for example, exposure by the exposure device 13 is started and the photoconductor 8 is started. The time for the latent image formed above to reach the development area is also a design matter.

  In the present embodiment, starting from the rotation start timing of the registration roller 19, as described later, when printing a plurality of pages continuously, between the recording paper and the recording paper conveyed through the recording paper conveyance path 5 ( In other words, the light intensity of the organic electroluminescence elements constituting the exposure device 13 is set and turned on in the space between the sheets), and the developing bias is controlled to be off with respect to the latent image position formed on the photosensitive member 8. ing.

  Subsequently, returning to FIG.

  A fixing unit 23 is provided as a nip conveying means on the exit side in the recording paper conveying path 5 located further downstream of the black developing station 2K at the most downstream side. The fixing device 23 includes a heating roller 24 and a pressure roller 25.

  Reference numeral 27 denotes a temperature sensor for detecting the temperature of the heating roller 24. The temperature sensor 27 is a ceramic semiconductor obtained by sintering at a high temperature using a metal oxide as a main raw material, and can measure the temperature of a contacted object by applying a change in load resistance depending on the temperature. it can. The output of the temperature sensor 27 is input to an engine control unit 42 which will be described later, and the engine control unit 42 controls the power supplied to a heat source (not shown) built in the heating roller 24 based on the output of the temperature sensor 27, The surface temperature of the heating roller 24 is controlled to be about 170 ° C.

  When the recording paper 3 on which the toner image is formed is passed through the nip portion formed by the heating roller 24 and the pressure roller 25 that have been controlled in temperature, the toner image on the recording paper 3 is added to the heating roller 24. The toner image is fixed on the recording paper 3 by being heated and pressurized by the pressure roller 25.

  Reference numeral 28 denotes a recording paper trailing edge detection sensor that monitors the discharge state of the recording paper 3. Reference numeral 32 denotes a toner image detection sensor. The toner image detection sensor 32 is a reflective sensor unit that uses a plurality of light emitting elements (both visible light) having different emission spectra and a single light receiving element, and changes the image color between the background of the recording paper 3 and the image forming portion. Accordingly, the image density is detected by utilizing the fact that the absorption spectrum is different. Further, since the toner image detection sensor 32 can detect not only the image density but also the image forming position, the image forming apparatus 1 in the embodiment has two toner image detection sensors 32 in the width direction of the image forming apparatus 1 and the recording paper 3. The image formation timing is controlled based on the detection position of the image position deviation amount detection pattern formed above.

  Reference numeral 33 denotes a recording paper transport drum. The recording paper transport drum 33 is a metal roller whose surface is covered with rubber having a thickness of about 200 μm, and the fixed recording paper 3 is transported along the recording paper transport drum 33 in the direction D2. At this time, the recording sheet 3 is cooled by the recording sheet conveying drum 33 and is bent and conveyed in the direction opposite to the image forming surface. As a result, curling that occurs when a high density image is formed on the entire surface of the recording paper can be greatly reduced. Thereafter, the recording paper 3 is conveyed in the direction D6 by the kicking roller 35 and discharged to the paper discharge tray 39.

  Reference numeral 34 denotes a face-down paper discharge unit. The face-down paper discharge unit 34 is configured to be rotatable about the support member 36. When the face-down paper discharge unit 34 is opened, the recording paper 3 is discharged in the direction D7. In the closed state, the face-down paper discharge unit 34 is formed with ribs 37 along the conveyance path on the back so as to guide the conveyance of the recording sheet 3 together with the recording sheet conveyance drum 33.

  Reference numeral 38 denotes a drive source, which employs a stepping motor in the present embodiment. Peripheral portions of the developing stations 2Y to 2K including a paper feed roller 18, a registration roller 19, a pinch roller 20, photoconductors 8Y to 8K, and a transfer roller 16 (see FIG. 12), a fixing device 23, and recording paper. The conveying drum 33 and the kicking roller 35 are driven.

  A controller 41 receives image data from a computer (not shown) via an external network, and develops and generates printable image data. As will be described in detail later, a controller CPU (not shown) mounted on the controller 41 receives light amount measurement data of an organic electroluminescence element as a light emitting element from the exposure devices 13Y to 13K and generates light amount correction data. In addition to the light amount correction means, it is also a light amount setting means for setting the light amount of the organic electroluminescence element based on the light amount correction data.

  Reference numeral 42 denotes an engine control unit. The engine control unit 42 controls the hardware and mechanism of the image forming apparatus 1, forms a color image on the recording paper 3 based on the image data and the light amount correction data transferred from the controller 41, and the fixing unit 23 described above. The overall control of the image forming apparatus 1 including the temperature control of the heating roller 24 is performed.

  Reference numeral 43 denotes a power supply unit. The power supply unit 43 supplies power of a predetermined voltage to the exposure devices 13Y to 13K, the drive source 38, the controller 41, and the engine control unit 42, and supplies power to the heating roller 24 of the fixing device 23. The power supply unit also includes a so-called high-voltage power supply system such as a charging potential for charging the surface of the photoconductor 8, a developing bias applied to the developing sleeve (see FIG. 12), and a transfer bias applied to the transfer roller 16. . The engine control unit 42 controls the power supply unit 43 to adjust not only the ON / OFF of the high-voltage power supply but also the output voltage value and the output current value.

  The power supply unit 43 includes a power supply monitoring unit 44 so that at least the power supply voltage supplied to the engine control unit 42 and the output voltage of the power supply unit 43 can be monitored. This monitor signal is detected by the engine control unit 42 to detect a drop in power supply voltage that occurs when the power switch is turned off or a power failure occurs, and particularly an output abnormality of the high-voltage power supply.

  The operation of the image forming apparatus 1 configured as described above will be described with reference to FIGS.

  In the following description, FIG. 11 is mainly used for the description relating to the overall configuration and operation of the image forming apparatus 1, and the colors are divided into the developing stations 2Y to 2K, the photoconductors 8Y to 8K, and the exposure devices 13Y to 13K. Although described separately, the description related to a single color, such as exposure and development processes, will be mainly described with reference to FIG. 12 for the sake of simplicity without distinguishing colors such as the developing station 2, the photosensitive member 8, and the exposure device 13.

<Initialization operation>
First, an initialization operation when the image forming apparatus 1 is turned on will be described.

  When the power is turned on, an engine control CPU (not shown) mounted in the engine control unit 42 performs an error check on the electrical resources constituting the image forming apparatus 1, that is, a register / memory capable of writing / reading. To do. When this error check is completed, the engine control CPU (not shown) starts to rotate the drive source 38. As described above, the peripheral portion of each developing station 2Y to 2K including the paper feed roller 18, the registration roller 19, the pinch roller 20, the photoconductors 8Y to 8K, and the transfer roller 16 by the driving source 38, the fixing device 23, and the recording paper conveyance The drum 33 and the kicking roller 35 are driven. However, immediately after the power is turned on, the feeding roller 18 and the registration roller 19 involved in the conveyance of the recording paper 3 are immediately turned off by the electromagnetic clutch (not shown) for transmitting the driving force to the recording roller 3 and the recording paper 3 is conveyed. There is no control.

  Hereinafter, the description will be continued with reference to FIG.

  As the driving source 38 (see FIG. 11) rotates, the stirring paddles 7a and 7b and the developing sleeve 10 of the developing station 2 also start to rotate, whereby the developer 6 composed of toner and carrier filled in the developing station 2 is developed. While rotating around the station 2, the toner is given a negative charge by the friction between the toner and the carrier.

  The engine control CPU (not shown) starts the rotation of the drive source 38 (see FIG. 11), and after a predetermined time has elapsed, controls the power source 43 (see FIG. 11) to turn on the charger 9. The surface of the photoconductor 8 is charged to a potential of, for example, −700 V by the charger 9. The photosensitive member 8 is rotated in the direction D3, and the engine control CPU (not shown) determines the power supply unit 43 (FIG. 11) after the charged region reaches the developing region, that is, the closest position between the photosensitive member 8 and the developing sleeve 10. For example, a developing bias of −400 V is applied to the developing sleeve 10. At this time, the surface potential of the photosensitive member 8 is −700 V, and the developing bias applied to the developing sleeve 10 is −400 V. Therefore, the electric lines of force are directed from the developing sleeve 10 to the photosensitive member 8 and have a negative charge. The Coulomb force acting on the toner is in the direction from the photoconductor 8 to the developing sleeve 10. Therefore, the toner does not adhere to the photoreceptor 8.

  As described above, the power supply unit 43 (see FIG. 11) has a function of monitoring an output abnormality (for example, leakage) of the high-voltage power supply, and an engine control CPU (not shown) is connected to the charger 9 and the developing sleeve 10 with high power. It is possible to check for abnormalities when a voltage is applied.

  At the end of the series of initialization operations, an engine control CPU (not shown) performs light amount correction of the exposure device 13. An engine control CPU (not shown) mounted on the engine control unit 42 (see FIG. 11) outputs a request for creating dummy image information for light amount correction to the controller 41 (see FIG. 11). Based on this creation request, the controller 41 (see FIG. 11) generates dummy image information for light amount correction, and based on this, the organic electroluminescence elements constituting the exposure apparatus 13 are actually controlled to be turned on at the time of initialization. . In the present embodiment, the light quantity of the organic electroluminescence element is measured by the light quantity measuring means (not shown) provided in the exposure apparatus 13 described above at this time, and each organic electroluminescence is based on the detection result of the light quantity. The light amount is corrected so that the light amounts of the elements are substantially equal. As described above, the measurement of the amount of light is performed in a state where the units relating to image formation such as the photosensitive member 8 and the developing stations 2Y to 2K of the image forming apparatus 1 are driven. This is because, when the light amount is measured in a state where the rotation of the photoconductor 8 is stopped, the same portion of the photoconductor 8 is continuously exposed, so that the characteristics of the photoconductor 8 are locally deteriorated in a so-called light exposure state. is there. Therefore, it is necessary to measure the amount of light while at least rotating the photoconductor 8 and charging the photoconductor 8 with the charger 9 in order to prevent toner adhesion to the photoconductor 8.

  As will be described in detail later, the image forming apparatus 1 according to the present invention includes an exposure device 13 provided with a light emitting element array in which a plurality of light emitting elements (organic electroluminescence elements) are formed in a row. Is an image forming apparatus that performs image formation by exposing the photosensitive member 8 that is an image carrier, and a light amount setting unit that sets a light amount of a light emitting element (organic electroluminescence element) (a controller mounted on the controller 41 described above) CPU) and light quantity measuring means (light detection element provided in the above-described exposure apparatus 13) for measuring the light quantity of the light emitting element (organic electroluminescence element), and a light quantity setting means (controller CPU mounted on the controller 41) ) Is a light emitting device for measuring the light quantity of a light emitting device (organic electroluminescence device) during non-image formation. The amount of the organic electroluminescence element) is set lower than the amount at which an image is formed.

  Further, the image forming apparatus 1 according to the present invention includes an exposure device 13 provided with a light emitting element array in which a plurality of light emitting elements (organic electroluminescence elements) are formed in a row, and a photoconductor on which a latent image is formed by the exposure device 13. 8 and a developing means (developing sleeve 10 constituting the developing station 2) for developing and developing the latent image formed on the photoconductor 8, as will be described in detail later. Light quantity setting means (controller CPU mounted on the controller 41) for setting the light quantity of the light emitting element (organic electroluminescence element), and light quantity measuring means (the exposure apparatus 13 described above) for measuring the light quantity of the light emitting element (organic electroluminescence element). And a light amount setting means (a controller CPU mounted on the controller 41) is used for non-image formation. The latent image formed on the photosensitive member 8 is a developing means (developing sleeve 10 constituting the developing station 2), and the light amount of the light emitting element (organic electroluminescence element) when measuring the light amount of the light emitting element (organic electroluminescence element). ) To set the amount of light that is not developed.

  As a result, during the initialization operation of the image forming apparatus 1, the organic electroluminescence element as the exposure light source constituting the exposure device 13 emits light, and even if the light quantity is corrected by measuring the light quantity, the toner remains on the photoreceptor 8. The toner does not adhere and wastes toner. Further, toner adheres to the transfer roller 16 that rotates in contact with the photoreceptor 8, and in image formation performed following the initialization operation, the toner attached to the transfer roller 16 adheres to the back surface of the recording paper 3 and the recording paper 3. No pollution.

  In this light amount correction, the region where the photoconductor 8 is exposed by turning on the organic electroluminescent element is close to the developing sleeve 10 and passes through the so-called developing region, that is, in the measurement period for measuring the light amount of the organic electroluminescent element. It is desirable to turn off the developing bias applied to the developing sleeve 10 for the exposed region of the photosensitive member 8. This makes it possible to more effectively prevent the toner from adhering to the photoreceptor 8.

<Image forming operation>
Next, the operation of the image forming apparatus 1 during image formation will be described with reference to FIGS.

  When the image information is transferred from the outside to the controller 41, the controller 41 develops the image information in an image memory (not shown) as binary image data that can be printed. When the development of the image information is completed, a controller CPU (not shown) mounted on the controller 41 issues a startup request to the engine control unit 42. The activation request is received by an engine control CPU (not shown) mounted on the engine control unit 42, and the engine control CPU (not shown) receiving the activation request immediately rotates the drive source 38 to prepare for image formation. To start.

  This process is the same as the above-described <Initialization operation> except for the error check related to the electrical resource, and the engine control CPU (not shown) can measure the above-described light amount even at this point. However, as will be described later, the measurement of the amount of light requires about 10 seconds, which affects the first print time (time required to print the first first sheet). Therefore, the user can select whether or not to execute the light amount correction at the time of activation by an instruction from an operation panel (not shown) or the outside (for example, a computer) of the image forming apparatus 1.

  When the preparation for image formation is completed through the above-described process, an engine control CPU (not shown) mounted on the engine control unit 42 controls an electromagnetic clutch (not shown) to rotate the paper feed roller 18 to perform recording. The conveyance of the paper 3 is started. The paper supply roller 18 is, for example, a half-moon roller that lacks a part of the entire circumference. When the leading edge of the conveyed recording paper 3 is detected by the recording paper passing sensor 21, an engine control CPU (not shown) controls an electromagnetic clutch (not shown) after providing a predetermined delay period to register rollers. 19 is rotated. As the registration roller rotates, the recording paper 3 is supplied to the recording paper conveyance path 5.

  An engine control CPU (not shown) independently controls the electrostatic latent image writing timing by each of the exposure devices 13Y to 13K, starting from the rotation start timing of the registration roller 19. Since the electrostatic latent image writing timing directly affects color misregistration and the like in the image forming apparatus 1, the writing timing is not directly generated by an engine control CPU (not shown). Specifically, an engine control CPU (not shown) presets the electrostatic latent image writing timing by each exposure device 13 in a timer (not shown) such as hardware, and rotates the registration roller 19 described above. As a starting point, timer operations corresponding to the exposure apparatuses 13Y to 13K are simultaneously started. Each timer outputs an image data transfer request to the controller 41 when a preset time has elapsed.

  The controller CPU (not shown) of the controller 41 that has received the image data transfer request is synchronized with the timing signal (clock signal, line synchronization signal, etc.) generated by the timing generation unit (not shown) of the controller 41. The value image data is transferred independently to each of the exposure devices 13Y to 13K. In this way, binary image data is sent to the exposure devices 13Y to 13K, and on / off of the organic electroluminescence elements constituting the exposure devices 13Y to 13K is controlled based on the binary image data, and a photoconductor corresponding to each color. 8Y to 8K are exposed.

  The latent image formed by the exposure is visualized by toner contained in the developer 6 supplied onto the developing sleeve 10 as shown in FIG. The visualized toner images of the respective colors are sequentially transferred to the recording paper 3 conveyed through the recording paper conveyance path 5. The recording paper 3 on which the transfer of the four color toner images has been completed is conveyed to the fixing device 23, and is nipped and conveyed by the overheating roller 24 and the pressure roller 25 constituting the fixing device 23. The toner image is recorded on the recording paper by this heat and pressure. 3 is fixed.

  When the image to be formed is a plurality of pages, the engine control CPU (not shown) detects the trailing edge of the recording paper 3 of the first page by the recording paper passage detection sensor 21 and then temporarily rotates the registration roller 19. Then, after a predetermined time has elapsed, the paper feed roller 18 is rotated to start the conveyance of the next recording paper 3, and after the predetermined time has elapsed, the registration roller 19 is again rotated to start the recording paper 3 of the next page. Is supplied to the recording paper conveyance path 5. Thus, by controlling the rotation ON / OFF timing of the registration roller 19, it is possible to set the sheet interval between the recording sheets 3 when an image is formed over a plurality of pages. The time between the sheets (hereinafter referred to as the sheet interval) varies depending on the specifications of the image forming apparatus 1, but is generally set to about 500 ms. Of course, the normal image forming operation (that is, the exposure operation for the photosensitive member 8 by the exposure device 13) is not performed during the period between the sheets.

  When the image forming apparatus 1 according to the present invention forms a plurality of pages as described above, the light emitting element (organic electroluminescence element) constituting the exposure apparatus 13 in a period (inter-paper time) corresponding to each page. Is emitted and the amount of light is measured. As described in <Initialization Operation>, the light amount at this time is controlled to be lower than that during normal image formation, and a light amount that does not contribute to development is set.

  As described above, the paper interval in the present embodiment is about 500 ms. As will be described later in detail, as described in the explanation of <Initialization operation>, in the present embodiment, the time required to measure the amount of light for all the organic electroluminescence elements is about 10 seconds, It is not possible to measure the amount of light of all organic electroluminescence elements within one paper interval. Therefore, in the embodiment, when measuring the light quantity of the organic electroluminescence elements in the period corresponding to each page, the light quantity of some of the organic electroluminescence elements constituting the exposure apparatus 13 is measured. ing.

  Since the time between papers is 500 ms and the light quantity measurement period is about 10 seconds, according to simple calculation, the light quantity of all the organic electroluminescence elements constituting the exposure device 13 when the paper gap occurs about 20 times. Can be measured. Of course, the number of pages in a series of print jobs is often less than that, but in such a case, the amount of light is measured after the print job is completed (when the image forming apparatus 1 shifts to a standby state waiting for a print command). You may make it do.

FIG. 13 is a block diagram of the exposure device 13 in the image forming apparatus 1 according to the embodiment of the present invention. Hereinafter, the structure of the exposure apparatus 13 will be described in detail with reference to FIG. In FIG. 13, 50 is a colorless and transparent glass substrate. In this embodiment, borosilicate glass, which is advantageous in terms of cost, is used as the glass substrate 100. However, heat generation from a light emitting element, a control circuit formed by a thin film transistor on the glass substrate 100, a driving circuit, and the like can be radiated more efficiently. If necessary, glass containing quartz or quartz containing a thermal conductivity additive factor such as MgO, Al ₂ O _3, CaO, or ZnO may be used.

  On the surface A of the glass substrate 100, an organic electroluminescence element as a light emitting element is formed at a resolution of 600 dpi (dot / inch) in a direction (main scanning direction) perpendicular to the drawing. Reference numeral 51 denotes a lens array in which rod lenses (not shown) made of plastic or glass are arranged in a row, and the light emitted from the organic electroluminescence element formed on the surface A of the glass substrate 100 is erecting at an equal magnification. The image is guided to the surface of the photoreceptor 8 as an image. The positional relationship among the glass substrate 100, the lens array 51, and the photoconductor 8 is adjusted so that one focus of the lens array 51 is the surface A of the glass substrate 100 and the other focus is the surface of the photoconductor 8. . That is, when the distance L1 from the surface A to the surface closer to the lens array 51 and the distance L2 from the other surface of the lens array 51 to the surface of the photosensitive member 8, L1 = L2.

  For example, 52 is a relay substrate in which an electronic circuit is formed on a glass epoxy substrate. 53a is a connector A, 53b is a connector B, and at least a connector A 53a and a connector B 53b are mounted on the relay board 52. The relay board 52 temporarily relays image data, light amount correction data, and other control signals supplied from the outside to the exposure apparatus 13 through a cable 56 such as a flexible flat cable, etc., via a connector B53b, and these signals are glass boards. Pass to 100.

  Since it is difficult to directly mount the connector on the surface of the glass substrate 100 in consideration of bonding strength and reliability in various environments, in this embodiment, as a connection means between the connector A 53a of the relay substrate 52 and the glass substrate 100. An FPC (Flexible Printed Circuit) is employed (not shown), and the glass substrate 100 and the FPC are joined on the glass substrate 100 in advance using, for example, an ACF (Anisotropic Conductive Film). For example, it is configured to be directly connected to the formed ITO (Indium Tin Oxide) electrode.

  On the other hand, the connector B 53b is a connector for connecting the exposure apparatus 13 to the outside. In general, connection by ACF or the like often has a problem of bonding strength. However, by providing the connector B53b for connecting the exposure apparatus 13 on the relay substrate 52 in this way, the interface directly accessed by the user is provided. Sufficient strength can be ensured.

  Reference numeral 54a denotes a casing A which is formed by bending a metal plate, for example. An L-shaped portion 55 is formed on the side of the housing A 54 a facing the photoconductor 8, and the glass substrate 100 and the lens array 51 are disposed along the L-shaped portion 55. The end surface of the case A 54a on the side of the photoconductor 8 and the end surface of the lens array 51 are aligned with each other, and the end portion of the glass substrate 100 is supported by the case A 54a. If the accuracy is ensured, the positional relationship between the glass substrate 100 and the lens array 51 can be accurately adjusted. As described above, since the casing A 54a is required to have dimensional accuracy, it is preferable that the casing A 54a be made of metal. Further, by making the casing A 54a made of metal, it is possible to suppress the influence of noise on electronic components such as a control circuit formed on the glass substrate 100 and an IC chip surface-mounted on the glass substrate 100. It is.

  A housing B is obtained by molding a resin. A notch (not shown) is provided in the vicinity of the connector B 53b of the housing B 54b, and the user can access the connector B 53b from this notch. From the controller 41 (see FIG. 11) already described via the cable 56 connected to the connector B 53b to the exposure apparatus 13, image data, light amount correction data, control signals such as clock signals and line synchronization signals, and drive power for the control circuit A driving power source for the organic electroluminescence element which is a light emitting element is supplied.

  FIG. 14A is a top view of the glass substrate 100 related to the exposure apparatus 13 in the image forming apparatus 1 according to the embodiment of the present invention, and FIG. 14B is an enlarged view of the main part thereof. Hereinafter, the configuration of the glass substrate 100 in the embodiment will be described in detail with reference to FIG.

  In FIG. 14, a glass substrate 100 is a rectangular substrate having a thickness of about 0.7 mm and having at least a long side and a short side, and a plurality of organic electroluminescence elements that are light emitting elements in the long side direction (main scanning direction). Elements 110 are formed in rows. In the embodiment, the organic electroluminescence element 110 necessary for at least A4 size (210 mm) exposure is disposed in the long side direction of the glass substrate 100, and the long side direction of the glass substrate 100 is a space for arranging the drive control unit 58 described later. And 250 mm. In the embodiment, the glass substrate 100 is described as a rectangle for simplicity. However, a notch is provided in a part of the glass substrate 100 for positioning when the glass substrate 100 is attached to the housing A 54a. It may be accompanied by deformation.

  A drive 58 receives binary image data, light amount correction data, and control signals such as a clock signal and a line synchronization signal supplied from the outside of the glass substrate 100, and controls driving of the organic electroluminescence element 110 based on these signals. The control unit includes an interface unit that receives these signals from the outside of the glass substrate 100 and an IC chip (source driver 61) that controls driving of the organic electroluminescence element 110 based on the control signal received through the interface unit. Yes.

  Reference numeral 60 denotes an FPC (flexible printed circuit) as an interface means for connecting the connector A 53a of the relay substrate 52 and the glass substrate 100, and is directly connected to a circuit pattern (not shown) provided on the glass substrate 100 without using a connector or the like. ing. As already described, binary image data, light amount correction data and control signals such as clock signals and line synchronization signals supplied to the exposure apparatus 13 from the outside, a driving power source for the control circuit, and the organic electroluminescence element 110 which is a light emitting element. Is supplied to the glass substrate 100 through the FPC 60 after passing through the relay substrate 52 shown in FIG.

  Reference numeral 110 denotes an organic electroluminescence element, which is an exposure light source in the exposure apparatus 13. In the embodiment, 5120 organic electroluminescent elements 110 are formed in a row at a resolution of 600 dpi in the main scanning direction, and each organic electroluminescent element 110 is independently controlled to be turned on / off by a TFT circuit described later. Is done.

  Reference numeral 61 denotes a source driver supplied as an IC chip for controlling the driving of the organic electroluminescence element 110, and is flip-chip mounted on the glass substrate 100. Considering surface mounting on the glass surface, the source driver 61 adopts a bare chip product. The source driver 61 is supplied with control-related signals such as a power supply, a clock signal, and a line synchronization signal and 8-bit light amount correction data from the outside of the exposure apparatus 13 via the FPC 60. The source driver 61 is a drive current setting unit for the organic electroluminescence element 110. More specifically, it is based on light amount correction data generated by a controller CPU (not shown) mounted on the controller 41 (see FIG. 11), which is a light amount correction unit and a light amount setting unit of the organic electroluminescence element 110. The source driver 61 sets a driving current for driving each organic electroluminescence element 110. The operation of the source driver 61 based on the light amount correction data will be described in detail later.

  In the glass substrate 100, the joint portion of the FPC 60 and the source driver 61 are connected through, for example, an ITO circuit pattern (not shown) having a metal formed on the surface, and the FPC 60 is connected to the source driver 61 as drive current setting means. Control signals such as light quantity correction data, a clock signal, and a line synchronization signal are input via the control signal. Thus, the FPC 60 as the interface means and the source driver 61 as the drive parameter setting means constitute the drive control unit 58.

  Reference numeral 62 denotes a TFT (Thin Film Transistor) circuit formed on the glass substrate 100. The TFT circuit 62 includes a shift controller, a data latch unit, and the like, a gate controller (not shown) that controls the timing of turning on / off the organic electroluminescence element 110, and a driving circuit that supplies a driving current to each organic electroluminescence element 110. (Not shown, hereinafter referred to as a pixel circuit). One pixel circuit is provided for each organic electroluminescent element 110, and is provided in parallel with a light emitting element array formed by the organic electroluminescent element 110. A drive current value for driving each organic electroluminescence element 110 is set in this pixel circuit by the source driver 61 which is a drive parameter setting means.

  A gate controller (not shown) constituting the TFT circuit 62 is supplied with a control signal such as a power supply, a clock signal, and a line synchronization signal and binary image data from the outside of the exposure apparatus 13 via the FPC 60, and the gate controller (FIG. (Not shown) controls the lighting / extinguishing timing of each light emitting element based on these power sources and signals. The operations of the gate controller and the pixel circuit (both not shown) will be described in detail later with reference to the drawings.

  Reference numeral 64 denotes a sealing metal film. When the organic electroluminescent element 110 is affected by moisture, the light emitting characteristics are extremely deteriorated due to shrinkage of the light emitting region over time (shrinking) and non-light emitting sites (dark spots) in the light emitting region. Sealing is necessary to block moisture. In the embodiment, a solid sealing method in which the sealing metal film 64 is attached to the glass substrate 100 via an adhesive is employed. However, the sealing region is generally formed from a light emitting element array formed by the organic electroluminescence element 110. About 2000 μm is required in the sub-scanning direction, and in the embodiment, 2000 μm is secured as a sealing margin.

  Reference numeral 57 denotes a light quantity sensor as a light quantity detection means in which a plurality of light detection elements each constituted by a thin film transistor composed of a polycrystalline silicon layer are arranged along the long side of the glass substrate 100 in the main scanning direction. 59 are processing circuits including at least an amplifier circuit and an analog-digital conversion circuit. The light amount of each organic electroluminescence element 110 is measured by the light detection element 57. In principle, it is necessary to measure the amount of light by individually lighting the organic electroluminescence elements 110 one by one, but the light detection elements are sufficiently separated from the organic electroluminescence elements 110 to be measured. Has almost no influence of the light emission (the light emitted from the organic electroluminescence element 110 is attenuated). Therefore, in the embodiment, the light detection element 57 is composed of a plurality of light detection elements, so that a plurality of organic elements can be obtained. The light quantity of the electroluminescence element 110 can be measured simultaneously.

  Outputs of the plurality of photodetecting elements 120 are input to the processing circuit 59 through wiring not shown. The processing circuit 59 is an analog / digital mixed IC chip. The outputs of the individual photodetecting elements constituting the photodetecting element 57 are subjected to voltage conversion by the charge accumulation method in the processing circuit 59, further amplified by a predetermined amplification factor, and then converted from analog to digital. Digital data (hereinafter referred to as light quantity measurement data) is output to the outside of the exposure apparatus 33 via the FPC 60, the relay substrate 52, and the cable 56 (both see FIG. 13). As will be described in detail later, the light quantity measurement data is received and processed by a controller CPU (not shown) mounted on the controller 41 (see FIG. 11) to generate 8-bit light quantity correction data.

  FIG. 15 is a block diagram showing the configuration of the controller 41 in the image forming apparatus 1 according to the embodiment of the present invention. Hereinafter, the operation of the controller 41 will be described with reference to FIG. 15, and the light amount correction will be described in more detail.

  In FIG. 15, 80 is a computer. The computer 80 is connected to a network 81, and transfers image information, the number of prints, and print job information such as a print mode (for example, color / monochrome) to the controller 41 via the network 81. 82 is a network interface. The controller 41 receives the image information and print job information transferred from the computer 80 via the network interface 82, develops the image information into printable binary image data, and conversely detected by the image forming apparatus side. Error information or the like is transmitted as so-called status information to the computer 80 via the network 81.

  A controller CPU 83 controls the operation of the controller 80 based on a program stored in the ROM 84. A RAM 85 is used as a work area for the controller CPU 83, and temporarily stores image information, print job information, and the like received via the network interface 82.

  Reference numeral 86 denotes an image processing unit. The image processing unit 86 can perform printing by performing image processing (for example, image development processing based on printer language, color correction, edge correction, screen generation, etc.) on a page basis based on image information and print job information transferred from the computer 80. Binary image data is generated and stored in the image memory 65 in units of pages.

  Reference numeral 66 denotes a light amount correction data memory constituted by a rewritable nonvolatile memory such as an EEPROM.

  FIG. 11 is an explanatory diagram showing the contents of the light amount correction data memory in the image forming apparatus 1 according to the embodiment of the present invention.

  Hereinafter, the data structure and data contents in the light amount correction data memory will be described with reference to FIG.

  As shown in FIG. 11, the light quantity correction data memory 66 has three areas from the first area to the third area. Each area includes 5120 8-bit data equal to the number of organic electroluminescence elements 110 (see FIG. 14) constituting the exposure apparatus 13 (see FIG. 13), and occupies a total of 15360 bytes.

  First, data DD [0] to DD [5119] stored in the first area will be described with reference to FIG. 11 and FIG.

  The exposure apparatus 13 (see FIG. 13) already described includes a step of adjusting the light quantity of each organic electroluminescence element 110 (see FIG. 14) constituting the exposure apparatus 13 in the manufacturing process. In this step, the exposure apparatus 13 is attached to a predetermined jig (not shown), and the organic electroluminescence element 110 is individually controlled to be turned on based on a control signal supplied from the outside of the exposure apparatus 13.

  Furthermore, a two-dimensional light quantity distribution of each organic electroluminescence element 110 at the image plane position of the photoreceptor 8 (see FIG. 13) is measured by a CCD camera provided on a jig (not shown). A jig (not shown) calculates the potential distribution of the latent image formed on the photoconductor 8 based on the light quantity distribution, and further, the correlation with the toner adhesion amount is calculated based on the actual development conditions (development bias value). Calculate the high latent image cross section. In a jig (not shown), the driving current value for driving the organic electroluminescence element 110 is changed {as described above, the TFT circuit 62 (see FIG. 14) is connected via the source driver 61 (see FIG. 14). A current value for driving the organic electroluminescence element 110 can be set by programming an analog value in the pixel circuit to be configured. } A driving current value at which all of the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 110 are substantially equal, that is, a setting value for the pixel circuit (setting data for the source driver 61 from the viewpoint of control) To extract.

  When the light emitting area of the organic electroluminescence element 110 and the light emission amount distribution in the light emitting surface are equal and the normal development conditions are assumed, the above-described latent image cross-sectional area is substantially proportional to the light amount. Furthermore, “the amount of light emitted when the exposure time is constant” and “exposure amount” are synonymous, and generally the amount of light emitted from the organic electroluminescence element 110 and the drive current value (that is, the set value for the pixel circuit) are proportional. Therefore, by setting the drive current setting to all the pixel circuits to be the same and measuring the light emission amount of each organic electroluminescence element 110 once, the latent image cross-sectional area by each organic electroluminescence element 110 is made constant. It is also possible to obtain a setting value for the pixel circuit (setting data for the source driver 61 as described above) by calculation.

  In the first area of the light quantity correction data memory 66, the setting data for the source driver 61 obtained in this way is stored. The number thereof is 5120 equal to the number of organic electroluminescence elements 110 constituting the exposure apparatus 13 as described above (that is, equal to the number of pixel circuits). As described above, the first area of the light quantity correction data memory 66 stores “the set value of the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 110 in the initial state”. .

  Next, data ID [0] to ID [5119] stored in the second area will be described with reference to FIG. 11 and FIG.

  At the same time that the jig acquires data stored in the first area, 8-bit light quantity measurement data based on the output of the light detection element 57 (see FIG. 14) via the processing circuit 59 (see FIG. 14) of the exposure apparatus 13. To get. As a result, “light quantity measurement data when the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 110 in the initial state are equal” can be acquired. The 8-bit light quantity measurement data ID [n] is stored in the second area.

  Now, the driving condition of the organic electroluminescence element 110 when acquiring ID [n] by the jig needs to be the same as that at the time of measuring the light amount. In the embodiment, one line of the image forming apparatus 1 is described later. A lighting period of about 30 ms in total is given by applying 350 μs, which is a period (raster period), a plurality of times.

  In this way, data stored in the first area and the second area in the manufacturing process of the exposure apparatus 13 is acquired, and these data are written from the jig to the light amount correction data memory 66 by electrical communication means (not shown). .

  Next, data ND [0] to ND [5119] stored in the third area will be described with reference to FIGS. 13, 14, and 15 in FIG.

  The image forming apparatus 1 according to the embodiment of the present invention includes a light amount correcting unit {controller CPU 83 (a controller CPU 83 () that corrects the light amount of each of the organic electroluminescence elements 110 substantially equally based on the measurement result by the light detecting element 57 as the light amount measuring unit. )}, And based on the output of the light quantity correction means, the light quantity setting means (also the controller CPU 83) sets the light quantity of each organic electroluminescence element 110 when the image is formed. In the third area, the light amount setting value of each organic electroluminescence element 110 when the image is formed by the controller CPU 83 as the light amount correcting means, that is, light amount correction data is written.

  In the image forming apparatus 1 according to the embodiment, the initialization of the image forming apparatus 1, the start of the image forming operation, the interval between sheets, the completion of the image forming operation, and the like of the organic electroluminescence element 110 constituting the exposure apparatus 13 are performed. Measuring the amount of light is as described above. The controller CPU 83 makes the light quantity measurement data measured at these times equal to the “latent image sectional areas formed by the individual organic electroluminescence elements 110 in the initial state” stored in the first area in the manufacturing process of the exposure apparatus 13. The set value of the source driver 61 for performing the process is the same as the “cross-sectional area of the latent image formed by each organic electroluminescence element 110 in the initial state” stored in the second area in the manufacturing process of the exposure apparatus 13. Light quantity correction data is generated based on the "light quantity measurement data".

  Hereinafter, the calculation content of the light amount correction data by the controller CPU 83 will be described, but in order to clarify the point of the present invention, the light amount at the time of light amount measurement is first assumed to be equal to that at the time of image formation.

  DD [n] (where n is the value in the main scanning direction) stored in the first area is “the set value of the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 110 in the initial state”. Individual organic electroluminescence element numbers (hereinafter the same), “light quantity measurement data when the latent image cross-sectional areas formed by the individual organic electroluminescence elements 110 in the initial state are equal” stored in the second area is ID [ n], when the light quantity measurement data newly measured in the initialization operation or the like is PD [n], the new light quantity correction data ND [n] written in the third area is based on (Expression 1). Generated by.

  The calculation formula shown in (Expression 1) is a basic calculation formula for calculating the light amount correction data, and should be applied when the light amount at the time of image formation and the light amount measurement is equal as described above. In the embodiment, the light quantity of the organic electroluminescence element 110 at the time of light quantity measurement related to the light quantity correction is set smaller than the light quantity at the time of image formation. In order to realize this, when measuring the light quantity, DD [n] is multiplied by a constant k smaller than 1 as the light quantity correction data to be sent to the exposure device 13, and the organic electroluminescence element 110 is turned on based on this. Just do it. For example, k is set to 0.5, and the light quantity correction data DD [n] multiplied by k is programmed into a pixel circuit (not shown) via the source driver 61 (see FIG. 14) as described above, whereby the organic electroluminescence device 110 is programmed. Can be emitted with an amount of light (unit: cd / m 2) that is 0.5 times that in image formation. The new light quantity correction data ND [n] at this time may be generated based on (Equation 2).

  The light quantity correction data ND [n] generated in this way is once written in the area 3 of the light quantity correction data memory 66 (see FIG. 15). Thereafter, prior to image formation, the light amount correction data ND [n] is copied from the light amount correction data memory 66 to a predetermined area of the image memory 65 (see FIG. 15). The light amount correction data ND [n] copied to the image memory 65 when the image is formed is temporarily stored together with binary image data in a buffer memory 88 (see FIG. 15), which will be described later, and the printer interface 87 (see FIG. 15). ) To the engine control unit 42 (see FIG. 15).

  The light quantity measurement data is subjected to voltage conversion by the charge accumulation method in the processing circuit 59 (see FIG. 14). The charge accumulation method is effective for improving the S / N ratio. However, since the output (current value) of the light detection element constituting the light detection element 57 (see FIG. 14) is very small, a certain amount of charge is accumulated for charge accumulation. Need time. In the embodiment, the SN ratio in the light amount measurement = 48 dB is secured by setting the accumulation time to about 30 ms. However, if the accumulation time is 30 ms, it takes a long time to measure the amount of light. When the amount of light is measured one by one for 5120 organic electroluminescence elements 110 (see FIG. 14), it is 5120 × 30 ms = 154 seconds, which is not practical. Therefore, in the embodiment, a polycrystalline silicon sensor formed by integrating the light detection element 57 constituting the light detection element 120 on a glass substrate is divided into two even and odd groups, and charge is accumulated simultaneously in units of groups. By measuring the terminal voltage of the photodetection element after accumulation, the processing speed is increased while suppressing crosstalk between adjacent photodetection elements. As a result, the light quantity can be measured in 154/16 = 9.6 seconds.

  Hereinafter, the description will be continued returning to FIG.

  Reference numeral 88 denotes a buffer memory. The binary image data stored in the image memory 65 and the light amount correction data described above are temporarily stored in the buffer memory 88 when transferred to the engine control unit 42. The buffer memory 88 is constituted by a so-called dual port RAM in order to absorb the difference between the transfer speed from the image memory 65 to the buffer memory 88 and the data transfer speed from the buffer memory 88 to the engine control unit 42.

  Reference numeral 87 denotes a printer interface. The binary image data and light amount correction data in page units stored in the image memory 65 are transferred to the engine control unit 42 via the printer interface 87 in synchronization with the clock signal and line synchronization signal generated by the timing generation unit 67. The

  FIG. 17 is a block configuration diagram showing the configuration of the engine control unit 42 in the image forming apparatus 1 according to the embodiment of the present invention. Hereinafter, the operation of the engine control unit 42 will be described in detail with reference to FIG.

  In FIG. 17, 90 is a controller interface. The controller interface 90 receives light amount correction data transferred from the controller 41, binary image data in units of pages, and the like.

  An engine control CPU 91 controls an image forming operation in the image forming apparatus 1 based on a program stored in the ROM 92. A RAM 93 is used as a work area when the engine control CPU 91 operates. 94 is a so-called rewritable nonvolatile memory such as an EEPROM. The nonvolatile memory 94 stores information on the lifetime of the constituent elements such as the rotation time of the photoconductor 8 of the image forming apparatus 1 and the operation time of the fixing device 23 (see FIG. 11).

  Reference numeral 95 denotes a serial interface. Information from sensor groups such as the recording paper passage detection sensor 21 (see FIG. 11) and the recording paper trailing edge detection sensor 28 (see FIG. 11) and the output of the power supply monitoring unit 44 (see FIG. 11) are not shown. Is converted into a serial signal having a predetermined cycle and received by the serial interface 95. The serial signal received by the serial interface 95 is converted into a parallel signal and then read by the engine control CPU 91 via the bus 99.

  On the other hand, control for an actuator group 96 such as an electromagnetic clutch (not shown) for controlling the starting and stopping of the paper feed roller 18 and the drive source 38 (both see FIG. 11) and the driving force transmission to the paper feed roller 18 (see FIG. 11). Signals and control signals for the high voltage power supply control unit 97 that manages potential settings such as development bias, transfer bias, and charging potential are sent to the serial interface 95 as parallel signals. The serial interface 95 converts the parallel signal into a serial signal and outputs it to the actuator group 96 and the high voltage power supply control unit 97. As described above, in the embodiment, sensor inputs and actuator control signals that do not need to be detected at high speed are all output via the serial interface 95. On the other hand, for example, a control signal for driving / stopping the registration roller 19 that requires a certain high speed is directly connected to the output terminal of the engine control CPU 42.

  An operation panel 98 is connected to the serial interface 95. The instruction given to the operation panel 98 by the user is recognized by the engine control CPU 91 via the serial interface 95. In the embodiment, an operation panel is provided as an instruction input means for inputting a user instruction. Based on the input to the operation panel, the amount of light of the organic electroluminescence element 110 constituting the exposure apparatus 13 is measured, and the amount of light is calculated. I am trying to correct it. This instruction can of course be given from an external computer or the like via the controller 41. As a specific usage mode, for example, when the user discovers density unevenness on the printing surface when performing a large amount of printing, the user forcibly corrects the amount of light to ensure image quality. Is assumed. If the image forming apparatus 1 is on standby, the user can instruct the execution of forced light amount correction at any time, and even during image formation, the image forming apparatus 1 is shifted to offline to temporarily form an image. Thus, the user can instruct execution of light amount correction.

  In any case, when a light quantity correction request is input from the operation panel 98 or the like as an instruction unit, the engine control CPU 91 starts driving the components of the image forming apparatus 1 as described in <Initialization Operation>. , A request to create dummy image information for light amount correction is output to the controller 41. Based on this request, the controller CPU 83 mounted on the controller 41 generates dummy image information for light amount correction, and based on this, the organic electroluminescence element 110 constituting the exposure apparatus 13 is controlled to be lit. At this time, the light detection element 57 provided in the above-described exposure apparatus 13 detects the light quantity of each organic electroluminescence element 110, and the light quantity of each organic electroluminescence element 110 is approximately based on the detection result of this light quantity. The amount of light is corrected so as to be equal.

  Next, the operation when measuring the amount of light of the organic electroluminescence element 110 will be described in detail with reference to FIGS. 11, 15 and 16 in FIG.

  As described above, the correction of the light amount is performed at the timing specified by the user using the operation panel 98 or the like after initialization of the image forming apparatus 1, immediately before starting printing, before printing, between sheets, after printing starts, but for the sake of simplicity. Next, a case where the light amount measurement is executed at the time of initialization operation of the image forming apparatus 1 will be described. Further, the image forming apparatus 1 according to the embodiment is configured to be capable of forming a full-color image, and has exposure apparatuses 13Y to 13K (see FIG. 11) corresponding to four colors as already described. For the sake of simplicity, only the operation for one color will be described and described as an exposure apparatus 13. Further, in the situation shown below, for example, the drive source 38 (see FIG. 11), the developing station 2 (see FIG. 12), and the like are already activated as already described in detail in <Initialization Operation>.

  Since the image forming operation is managed by the engine control unit 42 in the image forming apparatus 1, the light quantity correction sequence is started by the engine control CPU 91 of the engine control unit 42. First, the engine control CPU 91 outputs to the controller 41 a request for creating dummy image information that is different from the regular binary image data related to image formation.

The engine control unit 42 and the controller 41 are connected by a bidirectional serial interface (not shown), and can exchange a request command (request) and an acknowledgment (response information) with respect to each other. The dummy image information creation request issued by the engine control CPU 91 is output from the controller interface 90 to the controller 41 via the bus 99 using this bidirectional serial interface (not shown).
Based on this request, the controller CPU 83 mounted on the controller 41 directly creates dummy image information, that is, binary image data used for light quantity measurement, in the image memory 65. Further, the controller CPU 83 stores “the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 110 in the initial state” stored in the first area (see FIG. 11) of the light amount correction data memory 66. “Setting value” DD [n] (n: 0 to 5119) is read, and this is multiplied by a constant k (for example, 0.5) smaller than 1, so that the amount of light of the organic electroluminescence element 110 is lower than that during normal image formation. Set. This value is written in a predetermined area of the image memory 65. When these processes are completed, the controller CPU 83 outputs response information to the engine control unit 42 via the printer interface 87.

  The value of the constant k for setting the amount of light of the organic electroluminescence element 110 when measuring the amount of light is limited to 0.5 (that is, the amount of light when measuring the amount of light is halved at the time of image formation). is not. Since the object of the present invention is to solve the problem caused by exposing the photosensitive member 8 by light emission of the organic electroluminescence element 110 when measuring the amount of light and making it visible, this object is achieved. If so, any value may be set as the value of the constant k. As the constant k is decreased, the amount of light emitted from the organic electroluminescence element 110 is decreased, and accordingly, the potential potential of the latent image formed on the photoreceptor 8 is also decreased. Therefore, it becomes difficult to develop. However, since the value detected by the light detection element 57 is also small, it is disadvantageous in terms of the SN ratio when measuring the light amount. In actual application, the value of the constant k needs to be determined in consideration of “difficult to develop” and “S / N ratio when measuring the amount of light”.

  The value of the constant k is preferably changed according to the environment and situation where the image forming apparatus 1 is placed. In particular, the image forming apparatus 1 to which the electrophotographic system is applied changes the development characteristics depending on the environment (temperature, humidity), deterioration with time of the photoconductor 8, and the like, and therefore, for example, a temperature / humidity sensor (not shown) or the nonvolatile memory already described. It is desirable to change the value of k based on the information about the lifetime stored in 94. Further, since the SN ratio at the time of measurement can be substantially improved by extending the charge accumulation time by the processing circuit 59 (see FIG. 14) already described, for example, the temperature inside the image forming apparatus 1 is increased. When the number of organic electroluminescent elements 110 that are light quantity measurement targets can be reduced between the sheets, the constant k can be set smaller, and the selection range of the constant k is expanded.

  The engine control CPU 91 of the engine control unit 42 that has received the response information immediately sets a write timing for the exposure apparatus 13. That is, the engine control CPU 91 sets the timing for writing the electrostatic latent image by the exposure device 13 to a timer, which is hardware (not shown), and starts the operation of the timer as soon as response information is received (this function is originally provided with a plurality of exposure devices). This is to determine the start timing for each color of 13. Such a strict timing setting is not necessary in the measurement of the light quantity, and for example, 0 may be set in the timer). Each timer outputs an image data transfer request to the controller 41 when a preset time has elapsed. The controller 41 that has received the image data transfer request transfers the binary image data to the exposure device 13 in synchronization with the timing signal (clock signal, line synchronization signal, etc.) generated by the timing generator 67 via the controller interface 90. . At the same time, the “light quantity set value set lower than that during normal image formation” already written in the image memory 65 is also transferred to the exposure device 13 in synchronization with the timing signal. It should be noted that the light amount correction data (ND [n] already described) is replaced by the same transfer path instead of the “light amount setting value set lower than that at the time of normal image formation” during normal image formation, not during light amount measurement. It is supplied to the exposure device 13.

  The binary image data transferred in synchronization with the timing signal in this manner is input to the TFT circuit 62 of the exposure apparatus 13, and at the same time, the light amount setting value is input to the source driver 61 of the exposure apparatus 13. The exposure device 13 controls lighting and extinguishing of the corresponding organic electroluminescence element 110 based on the input binary image data, that is, ON / OFF information. The light quantity of the organic electroluminescence element 110 at this time is based on the set value of the light quantity and emits light with a light quantity lower than that for normal image formation. At this time, the amount of light of each organic electroluminescence element 110 is measured by the light detection element 57.

  The lighting of the organic electroluminescence element 110 is controlled so as to prevent crosstalk, and the light amount is measured by the light detection element 57. The output (analog current value) of the light detection element 57 is converted into a voltage by the charge accumulation method in the processing circuit 59, amplified with a predetermined amplification factor, and then subjected to analog-digital conversion to obtain 8-bit light quantity measurement data (digital). Data) from the processing circuit 59.

  The light quantity measurement data output from the processing circuit 59 is transferred from the engine control unit 42 to the controller 41 via the controller interface 90 and received by the controller CPU 83 of the controller 41. As described with reference to FIGS. 15 and 16, the controller CPU 83 generates light amount correction data ND [n] using PD [n] in (Equation 2) as described above.

  FIG. 18 is a circuit diagram of exposure apparatus 13 in image forming apparatus 1 according to the embodiment of the present invention. Hereinafter, the lighting control by the TFT circuit 62 and the source driver 61 will be described in more detail with reference to FIG.

  The TFT circuit 62 is roughly divided into a pixel circuit 69 and a gate controller 68. One pixel circuit 69 is provided for each organic electroluminescence element 110, and N groups are provided on the glass substrate 100 with M pixels of the organic electroluminescence element 110 as one group.

  In the embodiment, one group is 8 pixels (that is, M = 8), and this group is 640. Therefore, the total number of pixels is 8 × 640 = 5120 pixels. Each pixel circuit 69 supplies a current to the organic electroluminescent element 110 to drive the driver unit 70, and a current value supplied by the driver to control the lighting of the organic electroluminescent element 110 (that is, a driving current value of the organic electroluminescent element 110). ) Is stored in an internal capacitor, so that the organic electroluminescence element 110 can be driven at a constant current according to a drive current value programmed in advance at a predetermined timing.

  The gate controller 68 includes a shift register that sequentially shifts input binary image data, a latch unit that is provided in parallel with the shift register and collectively holds the input after a predetermined number of pixels have been input to the shift register, It consists of a control part which controls these operation timings (both not shown). The gate controller 68 is supplied with binary image data (image information converted by the controller 41 at the time of image formation and dummy image information converted by the controller 41 at the time of light quantity measurement) from the controller 41, and this binary image data, that is, ON. The SCAN_A and SCAN_B signals are output based on the / OFF information, and thereby the timing of turning on / off the organic electroluminescence element 110 connected to the pixel circuit 69 and the timing of the current program period for setting the drive current are controlled. .

  On the other hand, the source driver 61 has a number of D / A converters 72 (640 in the embodiment) corresponding to the number N of groups of the organic electroluminescence elements 110 inside. The source driver 61 multiplies the 8-bit light quantity correction data supplied via the FPC 60 (ND [n] shown in FIG. 11 when forming an image, DD [n] shown in FIG. 11 when measuring the light quantity and a constant k smaller than 1). The driving current for each organic electroluminescence element 110 is set based on the above value. With this configuration, the light amount of each organic electroluminescence element 110 is uniformly controlled by the light amount correction data ND [n] already described during image formation, and the light amount is lower than the light amount during normal image formation during light amount measurement. Thus, the light amount of the organic electroluminescence element 110 is controlled.

  FIG. 19 is an explanatory diagram showing a current program period and a lighting period of the organic electroluminescence element 110 related to the exposure apparatus 13 in the image forming apparatus 1 according to the embodiment of the present invention. Hereinafter, the lighting control according to the embodiment will be described in more detail with reference to FIG. In order to simplify the description, one pixel group consisting of 8 pixels (for example, “pixel number in the main scanning direction” = 1 to 8 in FIG. 19) will be described.

  In the embodiment, one line period (raster period) of the exposure apparatus 13 is set to 350 μs, and 1/8 (43.77 μs) of the one line period is driven with respect to the capacitor formed in the current program unit 71. It is used as the program period for setting the current value.

  First, the gate controller 68 (see FIG. 18) sets the program period by turning on the SCAN_A signal and turning off the SCAN_B signal for the pixel of pixel number = 1. During the program period, 8-bit light amount correction data is supplied to the D / A converter 72 built in the source driver 61 (see FIG. 18), and current is supplied by an analog level signal obtained by D / A converting the supplied digital data. The capacitor of the program unit 71 (see FIG. 18) is charged. This program period is executed regardless of ON / OFF of the binary image data input to the gate controller 68. Thus, the capacitor formed in the current program unit 71 has 8-bit light quantity correction data (ND [n] shown in FIG. 16 at the time of image formation, and DD [n] shown in FIG. An analog value based on (multiplied by k) is written every time one line period. That is, the accumulated charge of the capacitor formed in the current program unit 71 is always refreshed, and the driving current of the organic electroluminescence element 110 determined based on this is always kept constant.

  When the program period is completed, the gate controller 68 (see FIG. 18) immediately sets the lighting period by switching the SCAN_A signal to OFF and the SCAN_B signal to ON. As described above, the binary image data is supplied to the gate controller 68 (see FIG. 18) according to the time of image formation and the measurement of the amount of light. If the image data is OFF even during the lighting period, the organic electroluminescence is provided. The element 110 is not lit. On the other hand, when the image data is ON, the organic electroluminescence element 110 continues to be lit for the remaining 306.25 μs (350 μs−43.75 μs) (actually, the light emission time is slightly shortened because there is a control signal switching time). ). As described above, in the above embodiment, when measuring the light amount of the organic electroluminescence element 110, a measurement period of 30 ms is assumed, so that the number of times of lighting at the time of light amount measurement is, for example, 100 times (that is, 100 lines). As described above, the dummy image information is generated by the controller 41.

  On the other hand, when the program period for the pixel circuit 69 (see FIG. 18) with the pixel number = 1 shown in FIG. 19 ends, the gate controller 68 (see FIG. 18) immediately applies to the pixel circuit 69 with pixel number = 8 (see FIG. 19). Sets the current program period. Thereafter, as in the procedure for the pixel circuit having the pixel number 1, as soon as the program period for the pixel circuit having the pixel number 8 is completed, the process proceeds to the lighting period of the organic electroluminescence element 110 having the pixel number (see FIG. 18).

  In this way, the gate controller 68 (see FIG. 18) sets the pixel number in the main scanning direction = “1 → 8 → 2 → 7 → 3 → 6 → 4 → 5 → 1. Will be set. By adopting such a lighting order, the lighting timing of the nearest pixel is adjacent in time between adjacent pixel groups, so that the image step at the time of forming one line can be made inconspicuous.

  Here, the value set in the pixel circuit 69 (see FIG. 18) in the current program period is, for example, 8-bit light amount correction data as described above. Since the organic electroluminescence element 110 (see FIG. 18) is formed by a coating process such as spin coating, the adjacent pixel correlation is extremely high. Due to this effect, the emission luminance of the organic electroluminescence element 110 (see FIG. 19) in the vicinity of the specific organic electroluminescence element 110 (see FIG. 18) becomes almost the same. Accordingly, since the correlation between the light amount correction data with respect to these adjacent organic electroluminescence elements 110 (see FIG. 18) is very high, for example, the light amount correction data with pixel number = 1 and the light amount correction data with pixel number = 8 do not change greatly. .

  In the current program period controlled by the gate controller 68 (see FIG. 18), a current value according to the light amount correction data is supplied to the pixel circuit 69 (see FIG. 18), and the capacitance in the pixel circuit 69 (see FIG. 18). The element (capacitor) 140 is charged with a so-called constant current source, and the time required for charging is (Equation 3).

  According to (Equation 3), the charging time is proportional to the capacitance, and if the capacitance C increases due to the increase in the wiring capacitance accompanying wiring routing, the charging time increases. In the embodiment, in order to dispose the source driver on the extended line of the light emitting element array and at the end in the long side direction of the glass substrate 100, in the pixel group farthest from the source driver 61 (see FIG. 18), Normally, there is a concern about charging delay due to wiring capacity.

  However, in the embodiment, the light amount correction data is supplied by the source driver 61 (see FIG. 18). Since the light amount correction data has the same value in one pixel group as described above, the same amount is obtained. Within the pixel group, V in (Equation 3) hardly changes. After all, in the current programming process, the difference in V between sequentially selected pixel numbers dominates the charging time, but the difference in V between originally selected pixel numbers is very small, so the charging time is very short. It becomes. Therefore, the shortage of the current program period due to the increase in the wiring length from the source driver 61 (see FIG. 19) is almost no problem in the embodiment, and the source driver 61 has been described so far. The distance between the pixel circuit 69 (see FIG. 19) and the pixel circuit 69 (see FIG. 19) can be greatly separated.

  This situation is greatly different from a display that uses a current programming method to set a drive current for each pixel unit and reproduces multiple gradations such as 64 gradations and 256 gradations for each pixel unit. It can be said that this is a merit unique to the exposure apparatus 13 that can control lighting / extinction based on image data and set a drive current by a current programming method based on multi-value light quantity correction data.

  In the embodiment, the description has been made on the assumption that the light amount of the organic electroluminescent element 110 is controlled by changing the current value while keeping the lighting time of the organic electroluminescent element 110 constituting the exposure apparatus 13 constant. The present invention can also be easily applied to a so-called PWM method in which the driving current value of a light emitting element such as the organic electroluminescence element 110 is fixedly set, and the light amount of the light emitting element is controlled by changing the lighting time. In this case, the contents of the first area described with reference to FIG. 11 may be replaced with “setting value of driving time for equalizing latent image cross-sectional areas”.

  Also, depending on the exposure apparatus, there are a plurality of light emitting element arrays composed of organic electroluminescence elements, etc., and a latent image is formed by performing multiple exposures at substantially the same position with respect to the rotation direction of the photosensitive member. Is also known. Even in such an exposure apparatus, it is possible to apply the technical idea of the present invention by setting the light amount and the PWM time so that a latent image formed by a plurality of exposures does not contribute to development. . In such an exposure apparatus, a single light emitting element array does not form a latent image that contributes to development. For example, a sequence in which the amount of light is measured in units of lines between sheets can be considered.

  In the embodiment, the light quantity of the organic electroluminescence element 110 is measured using the light detection element arranged on the end face of the glass substrate 100 of the exposure apparatus 13, but the technical idea of the present invention is limited to this. is not. Since the light transmittance of, for example, low-temperature polysilicon that can constitute the TFT circuit 62 is relatively high, even in the so-called bottom emission configuration in which exposure light is extracted from the glass substrate 100 side described in the embodiment, individual organic electroluminescence The light detection element corresponding to each organic electroluminescence element 110 can be embedded in the element 110. In this case, the light detection element may be formed, for example, on the entire surface immediately below the light emitting surface of each organic electroluminescence element 110 or may be formed corresponding to a part thereof.

  As described above, the image forming apparatus to which the electrophotographic method is applied has been described in the embodiment, but the present invention is not limited to the electrophotographic method. Since an RGB light source can be easily realized by an organic electroluminescence element, for example, a plurality of exposure apparatuses each having an R light source, a G light source, and a B light source are arranged as exposure light sources, and photographic paper is directly applied based on image data of each RGB color. Needless to say, the present invention can also be easily applied to an image forming apparatus that exposes the light.

Although the optical head has been described in the above embodiments, the substrate is not partially limited to the optical head, and the substrate has been partially glass-sealed so far, such as an optical module used in a display device or an optical transmission device. It is applicable to such applications.
In particular, in display devices such as displays, the display area is sure to expand in the future, but the sealing area in such a large-screen display device will be enormous, and glass materials will be used here as in the past It is not realistic to perform sealing in view of material cost, manufacturing cost, and the like. On the other hand, the sealing material described in this embodiment can be mass-produced in a roll shape, for example. As a result, the material cost can be reduced, and the handling during the manufacturing can be facilitated, which can contribute to the reduction of the manufacturing cost.

(Embodiment 5)
As another embodiment of the organic electroluminescence element of the present invention, a metal material 64 may be formed in contact with the cathode 113 as shown in FIG. Other configurations are the same as those of the above-described embodiment, and the same portions are denoted by the same reference numerals. In this case, an electrode can be easily taken out by forming an opening in the passivation film 117 so that a part of the cathode is exposed and contacting the cathode with the metal material 64.

(Embodiment 6)
As another embodiment of the organic electroluminescence element of the present invention, as shown in FIG. 21, a polyimide resin film 64a is applied and formed on the inner surface side of the metal material 64, and this is adhered to the adhesive 63. Yes. Other configurations are the same as those of the above-described embodiment, and the same portions are denoted by the same reference numerals.
Since the polyimide resin has good adhesion to the adhesive and improves the mechanical strength of the metal material, it can be made thinner. Also, moisture resistance is improved.
Furthermore, since the inner surface side is constituted by the insulating polyimide resin film 64a in this way, the passivation film 117 can be omitted as compared with the structure of the fifth embodiment.

  In addition, since the sealing material includes a metal material, the metal material is grounded in the process of sealing the display region of the display device, thereby preventing electrostatic breakdown of the light emitting element in the manufacturing process. be able to. Furthermore, it is extremely easy to directly ground the sealing material after the sealing is completed. By sealing with this sealing material, including the driver IC chip that drives the display device, etc., it becomes possible to perform electrical shielding including these electronic components, yield in manufacturing, and post-manufacturing This can greatly contribute to the improvement of noise resistance performance.

  Although various embodiments of the present invention have been described, the present invention is not limited to the matters shown in the above-described embodiments, and those skilled in the art can make modifications and applications based on the description and well-known techniques. This is also the scope of the present invention, and is included in the scope of seeking protection.

As described above, the optical head and the image forming apparatus according to the present invention can prevent waste of toner, particularly in an electrophotographic apparatus, and can effectively prevent contamination by toner on the back surface of the recording paper. It can be used for copying machines, facsimile machines, photo printers, and the like. Further, the present invention can be applied to other optical modules and display devices (displays).

Schematic diagram showing the organic electroluminescence element described in the first embodiment of the present invention The top view and cross-sectional schematic diagram which show the optical head main-body part using the organic electroluminescent element of Embodiment 2 of this invention Sectional outline figure which shows the manufacturing process of the optical head main-body part as described in Embodiment 2 of this invention. FIG. 7 is a plan view showing a manufacturing process of the optical head main body according to the second embodiment of the present invention. The top view which shows the manufacturing process of the optical head main-body part as described in the modification of Embodiment 2 of this invention. Sectional drawing of the electroluminescent element 110 which comprises the optical head of Embodiment 3 of this invention, and its periphery Plane configuration explanatory diagram showing the configuration in the vicinity of the light detection element of the optical head described in the third embodiment of the present invention Equivalent circuit diagram of the light amount detection circuit of the optical head according to the third embodiment of the present invention The figure which shows the characteristic of the photon detection element of the optical head as described in Embodiment 3 of this invention. The figure which shows the light quantity detection flow of the optical head as described in Embodiment 3 of this invention. Configuration of an image forming apparatus according to a fourth embodiment of the present invention The block diagram which shows the periphery of the developing station in the image forming apparatus of the embodiment Configuration diagram of exposure apparatus in image forming apparatus of the embodiment (A) is a top view of the glass substrate according to the exposure apparatus in the image forming apparatus of the embodiment, (b) is an enlarged view of the main part. Block configuration diagram showing the configuration of the controller in the image forming apparatus of the embodiment Explanatory drawing which shows the content of the light quantity correction data memory in the image forming apparatus of the embodiment Block configuration diagram showing a configuration of an engine control unit in the image forming apparatus of the embodiment Circuit diagram of exposure apparatus in image forming apparatus of the embodiment Explanatory drawing which shows the electric current program period and the lighting period of an organic electroluminescent element which concern on the exposure apparatus in the image forming apparatus of the embodiment Schematic which shows the organic electroluminescent element of Embodiment 5 of this invention Schematic which shows the organic electroluminescent element as described in Embodiment 6 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2, 2Y, 2M, 2C, 2K Developing station 3 Recording paper 4 Paper feed tray 5 Recording paper conveyance path 6 Developer 8, 8Y, 8M, 8C, 8K Photoconductor 10 Developing sleeve 13, 13Y, 13M, 13C, 13K Exposure device 19 Registration roller 20 Pinch roller 21 Recording paper passage detection sensor 41 Controller 42 Engine control unit 43 Power supply unit 51 Lens array 57 Photodetection element 59 Processing circuit 61 Source driver 62 TFT circuit 63 Adhesive 64 Metal for sealing Film 65 Image memory 66 Light amount correction data memory 67 Timing generation unit 68 Gate controller 69 Pixel circuit 70 Driver unit 71 Current program unit 72 D / A converter 80 Computer 83 Controller CPU
87 Printer interface 90 Controller interface 91 Engine control CPU
98 Operation panel 100 Glass substrate 110 Organic electroluminescence element 117 Passivation film 120 Photodetection element 130 Thin film transistor

Claims (21)

An organic semiconductor device in which an organic semiconductor element formed on a substrate is sealed with a metal material,
The metal material is composed of a flexible metal material,
An organic semiconductor device fixed to the substrate via an adhesive. The organic semiconductor device according to claim 1,
The metal material is an organic semiconductor device having a thermal expansion coefficient of 10 ⁻⁵ or less. The organic semiconductor device according to claim 1,
The metal material is an organic semiconductor device having a film thickness of 0.3 mm or less. The organic semiconductor device according to claim 1,
The said metal material is an organic-semiconductor device which comprises a laminated body with a resin layer. The organic semiconductor device according to claim 1,
The adhesive is formed on the substrate so as to surround the organic semiconductor element,
An organic semiconductor device in which the metal material is fixed to the substrate only in a region where the adhesive is formed via the adhesive. The organic semiconductor device according to claim 1,
The substrate is a glass substrate, and includes an adhesive formed on the glass substrate so as to surround the organic semiconductor element,
An organic semiconductor device in which the metal material is fixed to the glass substrate only in a region where the adhesive is formed via the adhesive. An organic semiconductor device according to any one of claims 1 to 6,
An organic semiconductor device in which the metal material is nickel or a nickel alloy. An organic semiconductor device according to any one of claims 1 to 6,
An organic semiconductor device in which the metal material is iron or an iron alloy. An organic semiconductor device according to any one of claims 1 to 6,
The organic semiconductor device whose said metal material is a nickel iron chromium alloy. An organic semiconductor device according to any one of claims 1 to 6,
An organic semiconductor device in which the metal material is aluminum or an aluminum alloy. An organic semiconductor device according to any one of claims 4 to 9,
The organic resin device, wherein the resin layer is a coating film formed on the metal material. An organic semiconductor device according to any one of claims 1 to 11,
An organic semiconductor device in which the organic semiconductor element is covered with a sealing resin, and a metal material is disposed outside the sealing resin. An organic semiconductor device according to any one of claims 6 to 12,
The organic semiconductor element is formed on the glass substrate,
An organic semiconductor device which is an organic electroluminescent element comprising first and second electrodes and a functional layer including a layer having a light emitting function interposed between the first and second electrodes. An organic semiconductor device according to any one of claims 6 to 12,
An organic semiconductor device comprising: a light quantity detection element formed on the glass substrate; and an organic electroluminescent element laminated on the light quantity detection element. An organic semiconductor device according to claim 13,
An organic electroluminescent device;
A light amount detection circuit for detecting light output from the organic electroluminescent element,
The light amount detection circuit includes a photodetection element, a capacitive element connected in parallel to the photodetection element, and a switching thin film transistor connected to the capacitive element and controlling reading of the capacitive element, It is configured to detect the amount of light from the luminescent element,
An organic semiconductor device in which at least the light detection element and the organic electroluminescent element are sealed with the metal material to constitute an optical head. An organic semiconductor device according to claim 15,
The organic electroluminescent element is an organic semiconductor device formed in a line shape at a predetermined distance from an end face of the glass substrate. An organic semiconductor device according to claim 15,
The glass substrate comprises regions exposed from the metal material at both ends of the element row of the organic electroluminescent element,
An organic semiconductor device having inspection terminals disposed in the region. An organic semiconductor device according to claim 17,
An organic semiconductor device configured such that the element array is fed from both ends of the element array via jumper wires. An organic semiconductor device according to claim 17,
An organic semiconductor device in which a driving IC chip for driving the light emitting element is mounted in a region exposed from the metal material on one side opposite to one side of the glass substrate.   An optical head composed of the organic semiconductor device according to claim 1.   An image forming apparatus using the optical head according to claim 20 as exposure means for image formation.

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