JP4314578B2 - Line head, manufacturing method thereof, and image forming apparatus - Google Patents

Description

  The present invention relates to a line head used as exposure means in an image forming apparatus, a method for manufacturing the same, and an image forming apparatus including the line head.

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

  Incidentally, a light emitting diode or the like is generally used as the light emitting element of the printer head as described above. However, this has a problem that it is extremely difficult to arrange thousands of light emitting points with high accuracy. Therefore, in recent years, an image forming apparatus including a light emitting element array using an organic electroluminescent element (organic EL element) capable of accurately forming a light emitting point as a light emitting element as an exposure unit has been proposed (for example, Patent Documents). 1).

  Further, in the electrophotographic line printer as described above, the radiated light from the printer head (line head) is usually applied to the SELFOC (registered trademark) lens array (trade name of Nippon Sheet Glass; hereinafter referred to as SELFOC (registered trademark)). A system in which an image is formed on a photosensitive drum by passing through a lens (SL) and a SELFOC (registered trademark) lens array is referred to as an SL array) is exposed. The SL array is a cylindrical lens element, and allows a wide range of images to be formed by arranging a large number of SL elements for erecting an equal magnification.

By the way, an image formed by the SL array is formed by overlapping images formed by one SL element, and the SL element has a light quantity distribution as if football is halved. Therefore, in the SL array, periodic unevenness in the amount of light occurs with the arrangement pitch of each SL element.
However, if there is such a periodic unevenness in the amount of light, when the printer head (line head) and the SL array are combined, the light intensity in the main scanning direction is uniform due to the unevenness in the amount of light in the SL array. The print quality obtained by the deterioration of the exposure and the exposure accuracy is deteriorated.

Against this background, a technique has been proposed in which the thickness of the light emitting layer of the edge light emitting element is changed so as to eliminate unevenness in the light intensity period of the SL array, particularly when the edge light emitting element and the SL array are combined. (For example, refer to Patent Document 2).
JP 11-198433 A JP-A-5-330135

  However, in the case of a printer head (line head) having a general EL element that emits light from the substrate surface, such as bottom emission type or top emission type, instead of edge emission, the periodic light intensity unevenness of the SL array is eliminated. Such a technology has not been established, and therefore it is desired to provide such a technology.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for eliminating the periodic light amount unevenness of the SL array in a line head including a general EL element. An object of the present invention is to provide an image forming apparatus provided with a line head.

A line head according to the present invention is a line head configured to irradiate light to an exposed portion through a lens array in which lens elements are arranged, and to expose the portion.
A plurality of EL elements each having a functional layer that emits light and emitting light from the functional layer toward the lens array are arranged on a substrate to form a light emitting element array, and the light emitting element array is formed on the substrate. A driving element for driving the EL element is formed on the base side of the EL element which is the light emitting side of the EL element,
A light amount correction layer made of a non-translucent insulating material that corrects unevenness of the light amount of the lens array is integrally formed on the base side of the drive element on the substrate, and the drive element is formed on the light amount correction layer. It is characterized by forming directly .

  According to this line head, since the light amount correction layer for correcting the light amount unevenness of the lens array is formed, it is possible to eliminate the periodic light amount unevenness of the lens array and correct it. It is possible to prevent exposure unevenness and printing unevenness due to the above. In addition, since the light quantity correction layer is formed integrally, the positional accuracy of the light quantity correction layer with respect to the light emitting element row is improved by keeping alignment with the light emitting element row when forming the layer. Therefore, it is possible to correct the periodic light amount unevenness of the lens array with good accuracy.

In the line head, it is preferable that a driving element for driving the EL element is formed on the substrate, and the light amount correction layer is formed on a base side of the driving element.
In this way, this line head is effective when it is a so-called bottom emission type that emits light emitted from the EL element, particularly from the substrate side in the process of forming the driving element. In addition, since it is formed on the base side of the drive element, it is possible to form a light quantity correction layer on a flat substrate surface without being affected by irregularities due to the formation of the drive element. The correction layer can be accurately formed in a desired pattern.

In the line head, it is preferable that the light amount correction layer is formed outside a transparent electrode provided on one side of the functional layer in the EL element. In this case, it is preferable that a transparent sealing substrate is provided outside the transparent electrode so as to cover the transparent electrode, and the light quantity correction layer is formed on the transparent sealing substrate.
In this way, this line head is effective when the so-called top emission type that emits light emitted from the EL element, for example, on the side of the transparent sealing substrate that covers the transparent electrode.
In particular, if the light amount correction layer is formed on the transparent sealing substrate, it is possible to form the light amount correction layer on the flat transparent sealing substrate separately from the manufacturing process of the EL elements constituting the light emitting element array. Therefore, the light amount correction layer can be freely formed in a desired pattern with high accuracy and without any restrictions. The transparent electrode referred to here may be an anode. In this case, it is preferable that the drive element is first formed on the element substrate side, then the light amount correction layer is formed, and a transparent anode such as ITO is formed thereon.

The method for manufacturing a line head according to the present invention includes a plurality of EL elements on a substrate, each having a functional layer that emits light, and emitting light from the functional layer toward a lens array in which lens elements are arranged. A method of manufacturing a line head by arranging a light emitting element array, comprising:
Forming a light quantity correction layer for correcting the light amount unevenness of the lens array on the substrate,
Directly forming a driving element for driving the EL element on the light amount correction layer ,
In the step of forming the light amount correction layer, a physical mask having an opening pattern formed corresponding to the period of unevenness of the light amount of the lens array is separated from the formation surface of the light amount correction layer by a predetermined distance, and in this state, the light non-transparent A light amount correction layer that corrects unevenness in the light amount of the lens array is formed on the substrate by forming the insulating material by vapor deposition .

  According to this method for manufacturing a line head, the physical mask on which the opening pattern is formed corresponding to the period of unevenness of the light amount of the lens array is separated from the formation surface of the light amount correction layer by a predetermined distance, and in this state, the non-translucent material Is formed by a vapor phase film forming method to form a light amount correction layer for correcting the unevenness of the light amount of the lens array on the formation surface of the light amount correction layer. By having the correction layer, as described above, uneven exposure due to uneven light quantity and uneven printing are prevented. In particular, since the light quantity correction layer is integrally formed, the positional accuracy of the light quantity correction layer with respect to the light emitting element array can be improved by maintaining alignment with the light emitting element array.

Moreover, in the manufacturing method of the said line head, it is preferable that a non-light-transmissive material is a metal.
In this way, it is possible to form the light quantity correction layer with a relatively thin film thickness.
Moreover, in the manufacturing method of the said line head, it is preferable that a non-light-transmissive material is an insulating material.
In this way, for example, when the light quantity correction layer is formed on the base side of the drive element, the light quantity correction layer is made of an insulating material, so that the drive element can be directly formed on the light quantity correction layer. Become.

The image forming apparatus of the present invention is characterized in that the above-mentioned line head or the line head obtained by the above-described manufacturing method is provided as an exposure unit.
According to this image forming apparatus, as described above, since the line head forms the light amount correction layer for correcting the light amount unevenness of the lens array, the periodic light amount unevenness of the lens array is eliminated and corrected. Therefore, it is possible to prevent exposure unevenness due to unevenness in the amount of light and further unevenness in printing. In addition, since the line head is formed integrally with the light amount correction layer, it is possible to correct the periodic uneven light amount of the lens array with good accuracy by performing the alignment between them in advance. Become.

Hereinafter, the present invention will be described in detail.
First, the line head of the present invention will be described. FIG. 1 is a diagram schematically showing an embodiment of a line head according to the present invention, and reference numeral 1 in FIG. 1 denotes a line head. This line head 1 is used as an exposure unit of an image forming apparatus described later. As shown in FIG. 1, a plurality of organic EL (electroluminescence) elements 3 are arranged on a long and thin rectangular element substrate 2. A light emitting element array 3A, a driving element group including driving elements 4 for driving the organic EL elements 3, and a control circuit group 5 for controlling the driving of these driving elements 4 (driving element groups). It is. Further, a sealing substrate (not shown) is stuck on the element substrate 2 with an adhesive in a state where the organic EL element 3 is sealed.

Power source lines 7 and 8 are connected to the driving element 4, and a voltage is applied to the driving element 4 from a power source (not shown) via the power source lines 7 and 8. The drive element 4 (drive element group), the control circuit group 5, and the power supply lines 7 and 8 constitute drive control means. Based on such a configuration, the light emitting operation of the organic EL element 3 is controlled by the drive control means.
Here, the line head 1 of the present embodiment is a so-called bottom emission type that emits light emitted from the organic EL element 3 from the element substrate 2 side, and a light amount correction layer is formed on the element substrate 2. It is.

The configurations of the organic EL element 3 and the driving element 4 in the line head 1 will be described in detail with reference to FIGS. 2 (a) and 2 (b).
As shown in FIG. 2A, when the element substrate 2 is a bottom emission type in which light emitted from the light emitting layer 60 is emitted from the pixel electrode 23 side, the emitted light is extracted from the element substrate 2 side. Therefore, transparent or translucent ones are adopted. For example, glass, quartz, resin (plastic, plastic film) and the like can be mentioned, and a glass substrate is particularly preferably used.

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

  On the element substrate 2, a light amount correction layer 9 for correcting unevenness of light amount of an SL array (lens array) described later is integrally formed. The light quantity correction layer 9 is formed of a non-translucent material made of a metal having high heat resistance such as Ti, Cr, Ni, Mo, W, or a colored insulating material such as silicon nitride (SiN). Specifically, as shown in FIG. 3A, the non-translucent material is formed on the element substrate 2 through the physical mask 35.

The physical mask 35 has an opening pattern 36 corresponding to a period of unevenness of light amount of an SL array (lens array) described later, that is, an opening pattern 36 in which slits (openings) 36a having a predetermined width are arranged at predetermined intervals. . Here, the predetermined interval is an interval that substantially coincides with the period of unevenness of the light amount of the target SL array (lens array).
Then, this physical mask 35 is arranged at a predetermined distance from the surface on which the light quantity correction layer of the element substrate 2 is formed, and in this state, the non-translucent material is deposited by sputtering, vapor deposition, ion plating, CVD, or the like. By forming the film by the phase film formation method, the light quantity correction layer 9 as shown in FIG. 3B is formed. The light quantity correction layer 9 obtained in this way has a thick portion 9a and a thin portion made of a non-translucent material along the arrangement direction of the light emitting element row 3A made of the organic EL element 3 shown in FIG. (Almost no part) 9b is periodically changed from a thick part 9a to a thin part (absent part) 9b and from a thin part (absent part) 9b to a thick part 9a continuously It becomes.

  Therefore, the light quantity correction layer 9 including the thick portion 9a and the thin portion 9b of the film made of the non-translucent material as described above allows the element substrate 2 to transmit light less in the thick portion 9a of the light quantity correction layer 9. Therefore, the transmittance is low, and the thin portion 9b transmits a lot of light, and thus the transmittance is high. Note that the interval between the thick portion 9a and the thin portion 9b, that is, the cycle of the transmittance unevenness substantially coincides with the interval between the slits 36a, 36a in the physical mask 35, and this transmittance unevenness is the SL array (lens array) as it is. It comes to coincide with the period of unevenness of the amount of light. However, as will be described later, the phase is reversed from the unevenness of the light amount. Further, the degree of transmittance of each part in the light amount correction layer 9 can be adjusted by the width of the slit 36a, the type of the non-translucent material, the conditions at the time of film formation, and the like. Therefore, by determining the conditions appropriately through experiments and simulations in advance, the light amount correction layer 9 can be formed so as to cancel out the unevenness of the light amount of the SL array (lens array) and correct it appropriately. .

  For example, when the light amount unevenness of the SL array is ± 5% with respect to the average value, the intensity (light emission amount) of the light emitted from the light amount correction layer 9 is ± 5% with respect to the average value. In addition, by forming the thick portion 9a and the thin portion 9b, it is possible to obtain the light amount correction layer 9 that eliminates unevenness of the light amount of the SL array (lens array) and corrects it well.

  On the element substrate 2 on which such a light quantity correction layer 9 is formed, a circuit unit 11 including a driving TFT 123 (drive element 4) connected to the pixel electrode 23 is formed on the light quantity correction layer 9. The organic EL element 3 is provided thereon. The organic EL element 3 includes a pixel electrode 23 functioning as an anode, a hole transport layer 70 for injecting / transporting holes from the pixel electrode 23, a light emitting layer 60 made of an organic EL material, and a cathode 50 in this order. It is configured by being formed. In the present embodiment, the hole transport layer 70 and the light emitting layer 60 form the functional layer of the present invention.

Here, when the organic EL element 3 and the driving TFT 123 (driving element 4) are shown in a schematic view corresponding to FIG. 1A, it is as shown in FIG. 2B. In FIG. 2B, the power line 7 is connected to the source / drain electrode of the drive element 4, and the power line 8 is connected to the cathode 50 of the organic EL element 3.
In the organic EL element 3 having such a configuration, the holes injected from the hole transport layer 70 and the electrons from the cathode 50 are combined in the light emitting layer 60 as shown in FIG. By doing so, it emits light.

In this embodiment, which is a bottom emission type, the pixel electrode 23 that functions as an anode is formed of a transparent conductive material, and specifically, ITO is preferably used. Note that the light amount correction layer of the present embodiment can produce the same effect even if it is disposed between the interlayer insulating film on the drive element and the ITO anode instead of the base of the drive element. In this case, a conductive member can be used as the light amount correction layer by forming the light amount correction layer only inside the pixel.
As a material for forming the hole transport layer 70, in particular, a dispersion of 3,4-polyethylenediosithiophene / polystyrene sulfonic acid (PEDOT / PSS), that is, 3,4-polyethylenedioxy in polystyrene sulfonic acid as a dispersion medium. A dispersion in which thiophene is dispersed and further dispersed in water is preferably used.
In addition, as a forming material of the positive hole transport layer 70, various things can be used, without being limited to the said thing. For example, a material obtained by dispersing polystyrene, polypyrrole, polyaniline, polyacetylene or a derivative thereof in an appropriate dispersion medium such as the aforementioned polystyrene sulfonic acid can be used.

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

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

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

In addition, the circuit unit 11 is provided below the organic EL element 3 as described above. The circuit unit 11 is formed on the light amount correction layer 9. That is, a base protective layer 281 made of an insulating material such as SiO ₂ is formed on the surface of the light quantity correction layer 9 as a base, and a silicon layer 241 is formed thereon. A gate insulating layer 282 mainly composed of SiO ₂ and / or SiN is formed on the surface of the silicon layer 241.

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

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

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

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

  On the surface of the planarization film 284 on which the pixel electrode 23 is formed, the pixel electrode 23 and the above-described inorganic partition wall 25 are formed, and on the inorganic partition wall 25, an organic partition wall 221 is formed. On the pixel electrode 23, the hole transport layer 70 and the light emitting layer 60 are formed inside the opening 25 a formed in the inorganic partition wall 25 and the opening 221 a formed in the organic partition wall 221, that is, in the pixel region. Are stacked in this order from the pixel electrode 23 side, thereby forming a functional layer.

  In order to manufacture the line head 1 having such a configuration, first, as shown in FIG. 3A, a physical mask 35 is disposed on the inner surface side of the element substrate 2 with a predetermined distance from the light amount correction layer 9. In that state, a non-light-transmitting material, for example, the above-described metal or insulating material is deposited by a vapor deposition method such as a sputtering method. As a result, the non-translucent material scattered on the element substrate 2 side, in particular, the material scattered at the position of the slit 36a passes therethrough and is deposited on the element substrate 2, while it is scattered on the position between the slits 36a and 36a. What has been cut off by the physical mask 35 is deposited on the physical mask 35 as it is. Here, in particular, since the physical mask 35 is separated from the light amount correction layer 9 by a predetermined distance, the material that has passed through the slit 36 a diffuses until it is deposited on the element substrate 2, and is deposited on the element substrate 2 as it is.

  Therefore, the non-translucent material deposited on the element substrate 2 is diffused particularly in the arrangement direction of the slits 36a, so that the concentration of the non-translucent material is high in the central portion of the slits 36a in the arrangement direction. The concentration of the non-translucent material decreases as the distance from the center portion increases. By depositing the non-translucent material and forming the film in this way, the light quantity correction layer 9 is thin as the thick portion 9a made of the non-translucent material as shown in FIG. 3B. The portion (the almost non-existing portion) 9b is periodically changed from a thick portion to a thin portion (the non-existing portion) or vice versa. Therefore, the light amount correction layer 9 eliminates unevenness in the light amount of a later-described SL array (lens array) and corrects it.

When the light amount correction layer 9 is formed in this way, a base protective layer 281 is formed on the light amount correction layer 9, and a polysilicon layer or the like is further formed on the base protective layer 281. The circuit unit 11 is formed.
Then, the pixel electrode 23, the hole transport layer 70 as a functional layer, the light emitting layer 60, and the cathode 50 are formed in this order on the circuit portion 11, and further sealed using a sealing substrate (not shown). By doing so, the bottom emission type line head 1 is obtained.

Next, the usage pattern of the line head 1 obtained in this way will be described.
FIG. 4 is a diagram illustrating a usage pattern of the line head 1 in an image forming apparatus described later. As shown in FIG. 4, the line head 1 irradiates and forms an image by irradiating light onto the photosensitive drum 32 as an exposed portion in the present invention via the SL array 31 as the lens array in the present invention. It is a thing. Here, the line head 1 and the SL array 31 are assembled together in a head case (not shown). At that time, alignment between these is performed, and the periodic unevenness of the light amount of the SL array 31 is eliminated by the line head 1 and corrected as described later.

The SL array 31 includes a large number of cylindrical lens elements (SL elements) 31a as shown in FIG. 5A arranged as shown in FIG. 5B. It has come to produce. That is, each SL element (imaging element) 31a has a light quantity distribution as if football is halved as shown in FIG. As shown in FIG. 5B, the array 31 has a periodic light amount unevenness associated with the arrangement pitch of the SL elements (imaging elements) 31a. Here, the light amount unevenness ΔE of the SL array 31 is expressed by the following equation.
ΔE = {(imax−imin) / imin} × 100 (%)
(For imax and imin, see FIG. 5B)

This light amount unevenness ΔE differs depending on the degree of image overlap between the adjacent SLs 31a and 31a and the number of rows of the SL array 31. The pitch of unevenness in the amount of light can be expressed. Also, in the figure, the transmitted light amount has a distribution (unevenness) as shown in FIG. 6A with respect to the position of the SL array 31 in the column direction.
For example, if the SL array 20 made of Nippon Sheet Glass is used as the SL array 31, the lens period of the SL array 31, that is, the period of unevenness in the amount of light is 0.56 mm. In addition, when the SL array 31 is arranged in a zigzag pattern in two rows, the lens period (period of unevenness in the amount of light) is half, that is, 0.28 mm.

  Therefore, in such a line head 1 that irradiates light to the SL array 31, a thick portion of the film in the light amount correction layer 9 so as to cancel out the lens period (period of unevenness in light amount) and correct it. It is assumed that the period of 9a (or the thin part 9b of the film) coincides with the period of unevenness in the amount of light, and the phase thereof is reversed to the unevenness of the amount of light. That is, as shown in FIG. 6B, the head position corresponding to the portion where the light amount transmitted (guided) through the SL array 31 is small, that is, the position of the light amount correction layer 9 has a film thickness made of a non-transmissive material. The head position (position of the light amount correction layer 9) corresponding to the portion where the light amount is thin and thus the transmitted light amount (transmittance) is high and the SL array 31 transmits (leads) a large amount of light is opposite. Therefore, the transmitted light amount (transmittance) is made low. As a result, the intensity (light emission amount) of light emitted from the line head 1 toward the SL array 31 becomes the same curve as in FIG. 6B, as shown in FIG. 6C.

  In this way, the intensity (light emission amount) of the light emitted from the line head 1 is periodically changed so as to eliminate unevenness (unevenness in light amount) transmitted (guided) by the SL array 31. The light irradiated from the line head 1 and further transmitted through the SL array 31 becomes a uniform light amount (image forming light amount) at all image forming positions as shown in FIG. Therefore, the image is uniformly and uniformly formed on the photosensitive drum 32.

  The SL array 20 made of Nippon Sheet Glass is used as the SL array 31, and the correction period of the line head 1 is adjusted so as to correct 0.56 mm, which is the lens period of the SL array 31 (period of unevenness in the amount of light). Using the light quantity correction layer 9 adjusted to 0.56 mm and adjusted so that the intensity (light emission amount) of the emitted light is ± 5% of the average value, the photosensitive drum 32 is exposed and printed. As a result, the density variation was ± 1% or less. For comparison, when the same printing was performed using a line head in which the light amount correction layer 9 was not formed, the density variation was about ± 5%. Therefore, it was found that the line head 1 of the present embodiment can satisfactorily prevent exposure unevenness due to light amount unevenness of the SL array 31 and print unevenness, and improve the quality of the obtained print.

Thus, in the line head 1 of the present embodiment, the light amount correction layer 9 for correcting the light amount unevenness of the SL array 31 is formed. Thus, it is possible to prevent exposure unevenness due to light amount unevenness and print unevenness, and to improve the quality of the obtained print.
In particular, since the light quantity correction layer 9 is formed directly on the element substrate 2 and integrated with the light emitting element row 3A (organic EL element 3), the light emitting element row 3A is formed when the light quantity correction layer 9 is formed. , The positional accuracy of the light amount correction layer 9 with respect to the light emitting element array 3A can be made favorable. Therefore, the periodic light amount unevenness correction of the SL array 31 can be performed with good accuracy by simply aligning the SL array 31 and the line head 1.

  In the above embodiment, the base protective layer 281 is formed on the light quantity correction layer 9 and the driving TFT 123 (drive element 4) is formed thereon. In particular, the light quantity correction layer 9 is made of an insulating material. In this case, since the light quantity correction layer 9 itself becomes an insulating layer, the formation of the base protective layer 281 is omitted, and the driving TFT 123 (drive element 4) is formed directly on the light quantity correction layer 9. May be.

  FIG. 7 is a view schematically showing another embodiment of the line head of the present invention, and reference numeral 20 in FIG. 7 denotes a line head. The line head 20 is different from the line head 1 in that the emitted light is emitted, that is, the line head 1 is a bottom emission type, whereas the line head 20 adopts a top emission type. And the formation position of the light quantity correction layer 9 is changed in accordance with the adoption of this emission method (top emission type).

  As shown in FIG. 7, in the line head 20, a cathode 50 is formed of a transparent conductive material, for example, ITO, a sealing resin layer 40 is formed on the cathode 50, and a passivation film (not shown) is further formed as necessary. Z). Next, the light quantity correction layer 9 is formed on the sealing resin layer 40 or the passivation film by the method shown in FIG. At this time, as a film forming method for forming the light quantity correction layer 9, it is particularly preferable to use a low damage ion plating method so that the sealing resin layer 40 and the cathode 50 which is the base thereof are not damaged. . Thereafter, a transparent sealing substrate 30 made of glass or the like is attached so as to cover the light quantity correction layer 9.

Even in the line head 20 obtained in this way, in use, the sealing substrate 30 side is aligned toward the SL array 31, and in that state, the SL array 31 is assembled to a head case (not shown). And keep it together. As for the alignment of the line head 20 with respect to the SL array 31, as in the case of the line head 1, the periodic light amount unevenness of the SL array 31 is erased by the light amount correction layer 9 and is adjusted to a position where it can be corrected. Do that.
Then, as shown in FIG. 4, light is irradiated from the line head 20, and the light is imaged on the photosensitive drum 32 through the SL array 31 and exposed.

As described above, even in the line head 20 of the present embodiment, the periodic light amount unevenness of the SL array 31 can be eliminated by the light amount correction layer 9 and can be corrected. Therefore, the exposure unevenness caused by the light amount unevenness can be corrected. Further, uneven printing can be prevented, and the quality of the obtained print can be improved.
In particular, since the light quantity correction layer 9 is formed directly on the element substrate 2 so as to be integrated with the light emitting element array 3A (organic EL element 3), the cycle of the SL array 31 is similar to that of the line head 1. The correction of the uneven light quantity can be performed with good accuracy by simply aligning the SL array 31 and the line head 20.

In the above-described embodiment, the light quantity correction layer 9 is formed on the sealing resin layer 40 or the passivation film to realize the top emission type emission method. For example, the light quantity correction layer 9 may be formed on the inner surface side of the transparent sealing substrate 30 without being limited to the structure.
In this way, the light quantity correction layer 9 is formed on the flat transparent sealing substrate 30 separately from the manufacturing process of the EL elements 3 constituting the light emitting element array 3A. In addition, it can be freely formed with high accuracy and without being subject to conditional restrictions due to the presence of the EL element 3 or the like.

In the line heads 1 and 20 of the above embodiment, the light emitting element row 3A is formed by one row of organic EL elements 3. However, the present invention is not limited to this. For example, the organic EL elements 3 are arranged in two rows. These may be arranged in a staggered manner to form the light emitting element array 3A.
Moreover, in the said embodiment, although the example using an organic EL element was shown as an EL element formed in the line head 1 of this invention, it is needless to say that an inorganic EL element may be used instead. .
Furthermore, in the embodiment, an example in which the driving element 4 such as a TFT is formed on the element substrate 2 as an element for driving the EL element has been described, but the driving element 4 is not formed on the element substrate 2. The drive element 4 may be externally attached. Specifically, the driver IC may be COG mounted on the terminal area of the EL element substrate, or a flexible circuit board on which the driver IC is mounted may be mounted on the EL element substrate.

  Next, an image forming apparatus provided with the line head 1 of the present invention will be described. FIG. 8 is a view showing a first embodiment of the image forming apparatus of the present invention, and reference numeral 80 in FIG. 8 denotes the image forming apparatus. This image forming apparatus 80 includes organic EL array line heads 101K, 101C, 101M, and 101Y, which are examples of the line head of the present invention, and four corresponding photosensitive drums (image carriers) 41K, These are arranged in 41C, 41M, and 41Y exposure apparatuses, respectively, and are configured as a tandem system.

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

  Here, K, C, M, and Y in the symbols mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are for black, cyan, magenta, and yellow, respectively. The meanings of these symbols (K, C, M, Y) are the same for the other members. The photosensitive drums 41K, 41C, 41M, and 41Y are driven to rotate in the arrow direction (clockwise) in FIG. 8 in synchronization with the driving of the intermediate transfer belt 90.

Around each photosensitive drum 41 (K, C, M, Y), charging means (corona charger) 42 for uniformly charging the outer peripheral surface of the photosensitive drum 41 (K, C, M, Y), respectively. (K, C, M, Y) and rotation of the photosensitive drum 41 (K, C, M, Y) on the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y) The organic EL array line head 101 (K, C, M, Y) of the present invention that sequentially scans the line in synchronization with each other is provided.
Here, an SL array (not shown) is disposed between the organic EL array line head 101 (K, C, M, Y) and the photosensitive drum 41 (K, C, M, Y). . As described above, the organic EL array line head 101 (K, C, M, Y) is one in which the light amount correction layer 9 is integrally formed so as to eliminate the uneven light amount of the SL array and correct it.

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

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

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

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

  In FIG. 8, reference numeral 63 is a paper feed cassette in which a large number of recording media P are stacked and held, 64 is a pickup roller for feeding the recording media P from the paper feed cassette 63 one by one, and 65 is a secondary transfer. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion of the roller 66; a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 90; A cleaning blade 67 serves as a cleaning unit that removes toner remaining on the surface of the intermediate transfer belt 90 after the secondary transfer.

  Next, a second embodiment of the image forming apparatus according to the present invention will be described. FIG. 9 is a vertical side view of a four-cycle image forming apparatus. In FIG. 9, an image forming apparatus 160 is provided with a developing device 161 having a rotary configuration, a photosensitive drum 165 that functions as an image carrier, the SL array, and a line head (organic EL array line head) as main components. An image writing unit (exposure unit) 167, an intermediate transfer belt 169, a sheet conveyance path 174, a fixing unit heating roller 172, and a sheet feeding tray 178 are provided.

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

  In FIG. 9, reference numeral 165 denotes a photosensitive drum that functions as an image carrier as described above, 166 a primary transfer member, and 168 a charger. Reference numeral 167 denotes image writing means serving as exposure means in the present invention, which comprises the line head of the present invention and an SL array. The photosensitive drum 165 is rotationally driven in the direction of arrow D, which is the direction opposite to the developing roller 162a, by a drive motor (not shown), for example, a step motor. The line head constituting the image writing unit 167 is disposed in a state where the alignment (optical axis alignment) is performed between the line head and a lens element (not shown) or the photosensitive drum 165.

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

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

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

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

  In the state shown in FIG. 9, a yellow (Y) electrostatic latent image is formed on the photosensitive drum 165, and a high voltage is applied to the developing roller 162a, whereby a yellow image is formed on the photosensitive drum 165. Is done. When the yellow back side and front side images are all carried on the intermediate transfer belt 169, the development rotary 161a rotates 90 degrees in the direction of arrow A.

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

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

In the image forming apparatuses 80 and 160 shown in FIGS. 8 and 9, the line head (organic EL array line head) of the present invention as shown in FIG. 1 is provided as an exposure unit.
Therefore, in these image forming apparatuses 80 and 160, as described above, it is possible to prevent exposure unevenness due to light amount unevenness of the SL array and print unevenness, and improve the quality of the obtained print.
The image forming apparatus including the line head of the present invention is not limited to the above-described embodiment, and various modifications can be made.

The schematic diagram which shows one Embodiment of the line head of this invention. (A) is a principal part sectional side view of a line head, (b) is a schematic diagram. (A) is explanatory drawing of the formation method of a light quantity correction layer, (b) is a principal part top view of a light quantity correction layer. The schematic diagram for demonstrating the usage pattern of a line head. (A), (b) is explanatory drawing of SL array and its light quantity nonuniformity. (A)-(d) is a graph for demonstrating the effect | action of the line head of this invention. The principal part sectional side view which shows other embodiment of the line head of this invention. 1 is a schematic configuration diagram showing a first embodiment of an image forming apparatus of the present invention. It is a schematic block diagram which shows 2nd Embodiment of the image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,20 ... Line head, 2 ... Element board | substrate (board | substrate), 3 ... Organic EL element (EL element),
3A ... Light emitting element row, 4 ... Drive element (123 ... Driving TFT), 9 ... Light quantity correction layer,
30 ... Sealing substrate, 31 ... SL array (lens array), 31a ... Lens element (SL),
32 ... photosensitive drum (exposed part), 60 ... light emitting layer, 70 ... hole transport layer,
80, 160 ... Image forming apparatus

Claims (3)

A line head configured to irradiate and expose light to an exposed portion through a lens array in which lens elements are arranged,
A plurality of EL elements each having a functional layer that emits light and emitting light from the functional layer toward the lens array are arranged on a substrate to form a light emitting element array, and the light emitting element array is formed on the substrate. A driving element for driving the EL element is formed on the base side of the EL element which is the light emitting side of the EL element,
A light amount correction layer made of a non-translucent insulating material that corrects unevenness of the light amount of the lens array is integrally formed on the base side of the drive element on the substrate, and the drive element is formed on the light amount correction layer. A line head characterized by forming directly . A plurality of EL elements having a functional layer that emits light and emitting light toward a lens array in which lens elements are arranged from the functional layer are formed on a substrate to form a light emitting element array, A method of manufacturing a line head comprising:
Forming a light quantity correction layer for correcting the light amount unevenness of the lens array on the substrate,
Directly forming a driving element for driving the EL element on the light amount correction layer ,
In the step of forming the light amount correction layer, a physical mask having an opening pattern formed corresponding to the period of unevenness of the light amount of the lens array is separated from the formation surface of the light amount correction layer by a predetermined distance, and in this state, the light non-transparent A method of manufacturing a line head, comprising: forming a light amount correction layer for correcting unevenness of the light amount of the lens array on the substrate by depositing the insulating material by a vapor deposition method. As an exposure unit, an image forming apparatus comprising the line head obtained by the manufacturing method of claims 1 Symbol placement of the line head or claim 2 Symbol placement.

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