JP2006102966A - Printer head and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong a life of a printer head and to stabilize an image quality in an image forming apparatus. <P>SOLUTION: The printer head is equipped with both an element substrate (10) and a plurality of light emitting elements (11) arranged on the element substrate so as to expose a photoreceptor. An inside sealing means (21 and 22) is set to be in contact with at least a plurality of the light emitting elements of the element substrate. An element region where the plurality of light emitting elements are formed on the element substrate is directly sealed. An outside sealing means (31) is set to cover an outer surface of the inside sealing means, whereby the element region is indirectly sealed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printer head or line such as an organic EL (Electro-luminescence) printer head used to form an electrostatic latent image by exposing a photosensitive member in an image forming apparatus such as a printer, a copy, and a facsimile. The present invention relates to a technical field of a head and an image forming apparatus including the head.

  In this type of organic EL printer head, lighting / non-lighting according to a data signal in a plurality of organic EL light emitting elements arranged in a line is sequentially performed at a timing according to a line scanning signal.

  Incidentally, the organic EL light emitting element is a current driving type element, and generates heat by a driving current. When oxygen or moisture is present around the element, this heat promotes oxidation and deteriorates the element. For this reason, various ideas have been made for the sealing structure of the organic EL element. Known sealing structures include can sealing (see Patent Document 1), solid sealing (see Patent Document 2), thin film sealing (see Patent Document 3), and the like.

Japanese Patent No. 2800813 JP-A-9-274990 JP-A-5-182759

  However, when an organic EL light emitting element is to be applied to a printer head or line head of an image forming apparatus, the environment in the printer is extremely strict compared to the case of a display or the like, and it is difficult to prevent deterioration with a normal sealing structure. There is a technical problem.

  That is, in the printer, for example, since the toner is fixed on the paper surface by heating with a fixing device, a great amount of heat and moisture contained in the paper are released from the fixing device. For this reason, the organic EL light emitting element of the printer head is in a high temperature and high humidity environment that is not comparable to the organic EL light emitting element of the display.

  Furthermore, since the organic EL printer head has an elongated shape with the arrangement direction of the organic EL light emitting elements as the longitudinal direction, the element substrate is likely to be bent or twisted due to thermal expansion or the like. However, even if the printer head is slightly displaced, for example, the distance from the optical system for image projection and the photosensitive member may vary, and in the case of a color printer, the dot position may deviate from other colors. Therefore, the tolerance of displacement error in the printer head is quite small. For this reason, there is a technical problem that the quality of a printed image is deteriorated unless bending and twisting are sufficiently suppressed.

  The present invention has been made in view of the above problems, for example, and an object of the present invention is to provide a printer head and an image forming apparatus including the printer head that can extend the life and stabilize the image quality.

  In order to solve the above problems, a printer head according to the present invention includes an element substrate, a plurality of light emitting elements arranged on the element substrate for exposing a photosensitive member, and at least the plurality of the element substrates. An inner sealing means that is provided in contact with the light emitting element and directly seals an element region in which the plurality of light emitting elements are formed on the element substrate, and is provided so as to cover an outer surface of the inner sealing means. And an outer sealing means for indirectly sealing the element region.

  According to the printer head of the present invention, by supplying a drive current to each of the light emitting elements such as the organic EL light emitting elements, it is possible to emit line-shaped light from the light emitting element array to the photoconductor.

  Such a printer head is used to form an electrostatic latent image by exposing a photosensitive member in an image forming apparatus such as a printer, a copy, or a facsimile. During the driving, the electrostatic latent image formed on the photoreceptor is developed, and a toner image is formed by toner adhesion. The toner image is transferred onto a recording medium such as copy paper and is fixed on the recording medium by being heated by a fixing device. At that time, in the image forming apparatus, a great amount of heat and moisture contained in the paper are released from the fixing device or the like.

  For this reason, the light emitting element of the printer head is exposed to a high temperature and high humidity environment that is unique to the image forming apparatus and cannot be compared with the light emitting element of the display. In particular, it has been empirically known that elements containing organic materials such as organic EL light-emitting elements, the faster the temperature, the faster the deterioration due to oxygen and moisture. Can be said. Even if the light emitting element of the printer head is sealed to the same extent as the light emitting element applied to a display or the like, the deterioration of the printer head is sufficiently progressed because there is a large amount of oxygen and moisture that permeate the sealing member. There is a possibility that it cannot be suppressed.

  On the other hand, in the printer head of the present invention, the element region on the element substrate is directly sealed by the inner sealing means, and further indirectly by the outer sealing means provided so as to cover the inner sealing means from the outside. Sealed.

  Each sealing means is made of a member having a sealing function to block oxygen and moisture contained in the outside air from the element region, for example, a glass substrate with a countersink for can sealing, or for solid sealing A glass substrate, a thin film or film material having a moisture-proof effect, and the like. The outer sealing means may be any one of such sealing members, but may be provided in multiple by using a plurality of the same or different kinds of sealing members. And the inner side sealing means which contact | connects a light emitting element is provided in the innermost side. These sealing means are provided for the purpose of sealing the element region on the substrate. For example, the sealing means seals to other regions on the substrate, such as a region where various wirings and driving circuits are mounted. It may be. In particular, it is preferable to provide the outer sealing means so as to cover the entire element substrate for reasons such as that the structure can be reliably sealed.

  Since the light emitting element in this case is sealed in multiples, for example, double or triple, the oxygen or moisture in the outside air is not contained in the element even though it is arranged in a high temperature and high humidity environment. Intrusion is prevented very well, and deterioration can be sufficiently suppressed.

  In addition, since such a printer head has two or more sealing members mounted on the element substrate, the rigidity of the printer head increases. In general, the printer head may vary in distance from the SLA (Selfoc Lens Array (registered trademark)) and the photosensitive member even with a slight displacement, or in the case of a color printer, the electrostatic latent image formed on the photosensitive member of each color. Since a relative shift occurs in the dot position, the allowable range of displacement error is quite small.

  In contrast, since the printer head of the present invention has high rigidity, even if bending or twisting due to thermal expansion or the like is about to occur, it can be sufficiently suppressed, and the image quality of the printed image due to such deformation is reduced. It can be avoided.

  As a result of the above, according to the printer head of the present invention, it is possible to extend the service life, and it is possible to provide a printed image with stable image quality.

  In one aspect of the printer head of the present invention, the inner sealing means is made of a sealing material and is made of a sealing film disposed on the element substrate so as to cover the plurality of light emitting elements.

  According to this aspect, the sealing film that covers the light emitting element is provided on the element substrate as the inner sealing means. The sealing film is made of a sealing material that hardly transmits oxygen or moisture, and takes a form of a thin film formed on the light emitting element by vacuum vapor deposition or a film attached to the light emitting element, for example. In other words, the so-called “thin film sealing” is performed on the light emitting element by the sealing film.

  Here, the “sealing material” in the present invention means a material having a function of blocking substances that adversely affect the light emitting element such as oxygen and moisture. Examples of such a sealing material include organic polymers such as polybutadiene, Teflon (registered trademark), polystyrene, hydrocarbons, and long chain fatty acids applied in the form of a deposited film or film, aluminum oxide, and aluminum nitride. In addition, materials such as silicon oxide, silicon nitride, and inorganic materials such as substrate glass that are difficult to transmit moisture and oxygen, so-called water-resistant and water-absorbing materials, materials having low oxygen permeability, and the like.

  This sealing film can be more reliably sealed structurally by being in close contact with the light emitting element. In addition, since it is in close contact with the light emitting element, it occupies a small space area, which is advantageous for a multiple sealing structure with an outer sealing means.

  In another aspect of the printer head of the present invention, the inner sealing means is composed of a sealing material, and is disposed opposite to the element substrate, the first sealing substrate, and the first sealing substrate An adhesive layer is provided between the element substrate and the first sealing substrate is attached to the element substrate.

  According to this aspect, as the inner sealing means on the element substrate, the first sealing substrate disposed to face the element substrate, and the adhesive layer filled between the first sealing substrate and the plurality of light emitting elements. And are provided. The first sealing substrate is made of a sealing material such as glass, and covers the light emitting element with an adhesive layer interposed therebetween. The adhesive layer adheres to the light emitting element in a solid shape, and acts to prevent oxygen and moisture from entering the gap between the first sealing substrate and the light emitting element. That is, the light emitting element is so-called “solid sealing” by the first sealing substrate and the adhesive layer. In addition, an adhesive layer consists of curable adhesives etc., for example, and the presence or absence of sealing capability is not specifically limited.

  In this case, the first sealing substrate can be more reliably sealed structurally by being bonded to the light emitting element by the adhesive layer. In addition, since it is bonded to the light emitting element, it occupies a small space area, which is advantageous for taking a multiple sealing structure by an outer sealing means.

  In addition, in this aspect, the light emitting element is sandwiched between the element substrate and the first sealing substrate. Therefore, the heat generated in the light emitting element during driving is conducted almost uniformly to these two substrates. For this reason, there exists an advantage that the heat dissipation effect is high. That is, since the heat dissipation efficiency is high, the deterioration of the element due to heat is prevented, which contributes to a long life.

  Also, if the first sealing substrate is not provided, most of the heat generated in the light emitting element is conducted to the element substrate, so that a displacement difference due to thermal expansion occurs between the element substrate and the outer sealing means, and the printer. The head will bend and twist. On the other hand, in this embodiment, the heat generated from the light emitting element is uniformly conducted both above and below the light emitting element, so that the displacement difference as described above hardly occurs and the printer head is not easily bent or twisted. As described above, the displacement error range of the printer head allowed by the image forming apparatus is considerably small, and the deformation thereof needs to be suppressed as much as possible. However, here, the above configuration can suppress bending and twisting. Therefore, according to this printer head, it is possible to provide a print image with stable image quality.

  In another aspect of the printer head of the present invention, the outer sealing means is made of a sealing material and has a recess on one side, and covers the plurality of light emitting elements with a space interposed in the recess. As described above, the second sealing substrate is disposed on the element substrate.

  According to this aspect, the second sealing substrate is provided on the element substrate as the outer sealing means. The second sealing substrate is made of a sealing material such as a glass substrate, for example, and covers the light emitting element with a space in the recess. That is, so-called “can sealing” is performed on the light emitting element by the second sealing substrate.

  The second sealing substrate can provide a certain amount of space between the second sealing substrate and the light emitting element according to the depth of the recess. Therefore, it is relatively easy to secure a space for providing the inner sealing means and the other outer sealing means therein, which is advantageous for taking a multiple sealing structure.

  In an aspect in which can sealing is performed by the outer sealing means, at least one of a dehydrating agent and an oxygen scavenger may be sealed in the space.

  In this case, even if oxygen or moisture enters the recess of the second sealing substrate, it is absorbed by the dehydrating agent or oxygen scavenger, so that the oxygen concentration and humidity are reduced. Therefore, it is possible to more effectively prevent oxygen and moisture from entering the light emitting element.

  In another aspect of the printer head of the present invention, the outer sealing means is made of a sealing material, and is arranged to face the element substrate. The third sealing substrate, An adhesive layer is provided between the element substrate and the third sealing substrate is attached to the element substrate.

  According to this aspect, as the outer sealing means on the element substrate, the third sealing substrate disposed to face the element substrate, and the adhesive layer filled between the third sealing substrate and the plurality of light emitting elements. And are provided. That is, the light emitting element is so-called “solid sealing”. That is, the third sealing substrate and the adhesive layer are made of, for example, the same material as that of the first sealing substrate and the adhesive layer described above, and perform sealing in the same manner.

  The third sealing substrate can provide a certain amount of space between the light emitting element and the third sealing substrate depending on the thickness of the adhesive layer. Therefore, it is relatively easy to secure a space for providing the inner sealing means and the other outer sealing means therein, which is advantageous for taking a multiple sealing structure.

  In another aspect of the printer head of the present invention, the element substrate, the element substrate, the inner sealing unit, and the outer sealing unit are prevented from being deformed due to a difference in coefficient of thermal expansion between the element substrate, the inner sealing unit, and the outer sealing unit. The thermal expansion coefficients of at least two of the inner sealing means and the outer sealing means are aligned with each other.

  According to this aspect, even if the element substrate, the inner sealing unit, and the outer sealing unit in the printer head are thermally expanded due to heat generated in the image forming apparatus during driving, at least two of them are heated. Since there is little or no difference in expansion rate, the deformation of the printer head is suppressed. The element substrate, the inner sealing means, and the outer sealing means preferably have the same thermal expansion coefficient as much as possible, and in that sense, are preferably made of the same material. For example, when the sealing means is a substrate, the inner sealing substrate and the outer sealing substrate, or one or both of them and the element substrate may be the same glass substrate.

  As described above, the displacement error range of the printer head allowed by the image forming apparatus is quite small, and its deformation needs to be suppressed as much as possible. On the other hand, in a relatively high-temperature image forming apparatus, thermal expansion is considered to be the main deformation factor of the printer head. Therefore, if the coefficient of thermal expansion of the main member is controlled in this way, the deflection and twist of the printer head are effective. As a result, it is possible to avoid deterioration in the image quality of the printed image due to deformation or the like.

  According to another aspect of the printer head of the present invention, the element substrate and the inner sealing means are arranged so that the amount of displacement due to heat falls within a displacement error range of the printer head allowed in the mounted image forming apparatus. And at least one of the outer sealing means is made of a hardly deformable material.

  According to this aspect, since at least one of the element substrate, the inner sealing unit, and the outer sealing unit in the printer head is made of a material that is not easily deformed, it is assumed that they are thermally expanded by the heat in the image forming apparatus. Even if stress is generated according to the difference in thermal expansion coefficient, deformation due to stress and propagation of stress are suppressed. Therefore, it is possible to effectively suppress the bending and twisting of the printer head, and as a result, it is possible to avoid a decrease in the image quality of the printed image due to deformation or the like.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a printer head according to the present invention described above (including various aspects thereof), the photoconductor, and the photoconductor by exposure with the printer head. Developing means for developing a visible image by developing the formed electrostatic latent image, transfer means for transferring the formed visible image onto a recording medium, and recording the transferred visible image on the recording medium Fixing means for fixing on the medium.

  According to the image forming apparatus of the present invention, since the printer head according to the present invention described above is provided, the life of the apparatus can be extended. Even if the fixing device means is a fixing device that performs fixing by, for example, highly versatile heating, image quality deterioration due to deformation of the printer head caused by the heat generation or the like is avoided, so printing with stable image quality is possible. An image can be provided.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the following embodiments, a printer head equipped with an organic EL light emitting element which is an example of a light emitting element will be described as an example.

<First Embodiment>
The configuration of the printer head according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating a configuration of a printer head according to the present embodiment. FIG. 2 is a perspective view showing the appearance of the main body of the printer head. FIG. 3 shows a circuit configuration of the printer head body shown in FIG. FIG. 1 is a cross section of the printer head in the short direction, and corresponds to the cross section of the main body shown in FIG. Moreover, in FIG. 1 and FIG. 2, the scale of each member is different in order to make each member a size that can be recognized on the drawing.

  In FIG. 1, the printer head 1 has a main body 2 that is double-sealed by sealing substrates 21 and 31. For example, the main body 2 is configured in the same manner as a normal printer head.

  In FIG. 2, the main body 2 includes an organic EL light emitting element 11 arranged in a line, a pixel circuit 15 for driving a current through the organic EL light emitting element 11, and a driving unit 20 mounted on the element substrate 10. Being done.

  The element substrate 10 includes a strip-shaped glass substrate, a quartz substrate, a semiconductor substrate, and the like whose longitudinal direction is the left-right direction in the drawing. The element substrate 10 has a length of 20 cm to 30 cm so that it can be printed on, for example, A-size printing paper, and has a length of 10 mm, for example, in its short direction.

  The organic EL light emitting element 11 as an example of the “light emitting element” of the present invention is formed in the element region 11 a on the element substrate 10 together with the corresponding drive control pixel circuit 15.

  The configuration of the drive unit 20 is not particularly limited. For example, the drive unit 20 drives the external circuit connection terminal 12 to which a data signal is supplied, the plurality of data lines 13 connected to the external circuit connection terminal 12, and the light emitting unit 11. And a line scanning circuit 14 for this purpose. Data signals are respectively supplied from the data signal source to the data lines 13 via the external circuit connection terminals 12. The line scanning circuit 14 is configured to supply each pixel circuit 15 with a line scanning signal for controlling the light emission timing. In addition, the area | region 31 'shown with the oblique line in the figure is an area | region where the sealing substrate 31 is joined.

  3, the pixel circuit 15 includes, for example, transistors TR1 and TR2 whose driving states are controlled by line scanning signals S1, S2,... Sn and data signals, and a cathode 5a and an anode 5b for passing a current through the organic EL light emitting element 11. And is configured to control the binary state of light emission / non-light emission of the corresponding organic EL light emitting element 11. The pixel circuit 15 is driven by various methods such as a voltage program method and a current program method.

  An image forming apparatus such as a printer can be used for the main body 2 mounted with such an organic EL light-emitting element 11 if no measures are taken and if a moisture-proof measure similar to that of an organic EL display is taken. If arranged inside, the element may be relatively easily deteriorated. That is, the humidity in the image forming apparatus is considerably higher than that of a display or the like due to moisture released from a paper medium such as copy paper. In addition, not only the element itself generates heat due to the drive current, but also the heat released from other components such as the fixing device, and therefore the environmental temperature is high. For this reason, a printer head equipped with an organic EL light-emitting element needs to be sealed with much higher reliability than an organic EL display.

  Therefore, in the printer head 1 of the present embodiment, the sealing region 10a including the element region 11a and the region where the driving unit 20 is mounted on the element substrate 10 is sealed by the sealing substrates 21 and 31. (See FIG. 1). Here, not only the element region 11a but also all the components on the element substrate 10 are collectively sealed. If the substrate is partially sealed, the reliability with respect to airtightness may be reduced. This is because the manufacturing efficiency may be reduced due to the necessity of alignment. However, of course, such a sealing method may be appropriately adopted depending on the structure of the printer head, for example, when the drive circuit is externally attached later.

  As an example of the “first sealing substrate” of the present invention, the sealing substrate 21 is disposed to face the sealing region 10 a and is attached to the element substrate 10 with the adhesive layer 22. That is, the sealing substrate 21 is made of a material having a sealing property that hardly causes bending or twisting, such as a quartz substrate or a glass substrate, and covers the sealing region 10a with the adhesive layer 22 interposed therebetween. ing. The adhesive layer 22 is in close contact with the sealing region 10 a in a solid shape and acts to prevent oxygen and moisture from entering the gap between the sealing substrate 21 and the organic EL light emitting element 11. In this case, the adhesive layer 22 is made of, for example, a photocurable adhesive.

  Thus, since the sealing substrate 21 is directly bonded to the organic EL light emitting element 11, more reliable sealing is possible in structure. Further, by directly adhering to the organic EL light emitting element 11, it is possible to reduce the thickness necessary for sealing, which is advantageous for taking a multiple sealing structure with the sealing substrate 31.

  As an example of the “second sealing substrate” in the present invention, the sealing substrate 31 is disposed so as to cover the outer surface of the sealing substrate 21, and the element region 10 a can be sealed. The sealing substrate 31 is made of a material that is difficult to be bent and twisted, such as a quartz substrate or a glass substrate, and has a sealing ability, and a recess 31a is formed on one side by inserting a countersink. . And in this recessed part 31a, the sealing area | region 10a is covered through the space 31b. Here, the element substrate 10 and the sealing substrates 21 and 31 are made of the same material. That is, these substrates have the same thermal expansion coefficient. The operation and effect will be described later.

  The sealing substrate 31 can be provided with a space 31b having a certain size according to the depth of the recess 31a. Therefore, it is relatively easy to secure a space for providing the sealing substrate 21 therein, which is advantageous for taking a multiple sealing structure.

  Further, a dehydrating agent 32 and an oxygen scavenger 33 are sealed in the space 31b. Therefore, even if oxygen or moisture enters the recess 31a, the oxygen concentration and the humidity can be kept extremely low by absorbing them into the dehydrating agent 32 and the deoxidizing agent 33. Therefore, it is possible to prevent oxygen and moisture from entering the organic EL light emitting element 11 more effectively.

  As described above, in the printer head 1 according to the present embodiment, the sealing region 10a, that is, the plurality of organic EL light emitting elements 11 are double-sealed. Even in the case of being arranged in this environment, intrusion of oxygen or moisture in the outside air into the organic EL light emitting element 11 is extremely well prevented, and deterioration thereof can be sufficiently suppressed. Therefore, the life can be extended.

  Further, in the printer head 1, the organic EL light emitting element 11 is sandwiched between the element substrate 10 and the sealing substrate 21. Therefore, the heat generated in the organic EL light emitting element 11 during driving can be conducted substantially uniformly to these two substrates. Therefore, the printer head 1 has a high heat dissipation effect and can prevent element deterioration due to heat. This contributes to a longer life.

  Next, a specific configuration when the printer head 1 is mounted on the image forming apparatus will be described with reference to FIGS. FIG. 4 is a perspective view showing an external configuration of a printer head integrated with an optical system, and FIG. 5 is a sectional view thereof. 4 and 5 are shown upside down. Further, in FIGS. 4 and 5, the scale of each member is appropriately changed so that each member has a size that can be recognized on the drawing.

  4 and 5, the printer head 1 and the optical system 60 are integrally supported by a support member 70. In an image forming apparatus described later, the printer head 1 is mounted in this state. The printer head 1 is gripped by the support member 70 at the end of the element substrate 10 in a non-contact state on both sides. The optical system 60 is a lens system such as SLA (Selfoc Lens Array: registered trademark), for example, and forms an image formed on the organic EL light emitting element 11 in the element region 11a on the surface of the photoreceptor of the image forming apparatus. It is arranged at such a position.

  Due to these optical requirements, the printer head is generally not allowed to be deformed. However, unlike the display or the like, the printer head 1 or the element substrate 10 has a characteristic long and narrow shape, and thus is easily bent or twisted. In addition, if the element substrate 10 or the sealing substrate thermally expands due to a temperature rise in the image forming apparatus during driving, the printer head 1 is likely to be bent or twisted due to a difference in the amount of displacement. .

  Such deformation of the printer head 1 is difficult to sufficiently suppress even if the element substrate 10 is strongly fixed by the support member 70. Therefore, it is necessary to make the printer head 1 itself have a structure that does not bend or twist.

  On the other hand, since the two sealing substrates 21 and 31 are joined to the element substrate 10 (see FIG. 1), the printer head 1 is structurally high enough to suppress the occurrence of bending and twisting. Stiffness is given.

  In addition, due to the structure in which the two sealing substrates are bonded to the element substrate 10, heat generated from the organic EL light emitting element 11 during driving is generated above and below the organic EL light emitting element 11 (that is, the sealing substrate 21 side and the element substrate 10. Side). Therefore, a difference in displacement due to thermal expansion hardly occurs between the sealing substrate 31 and the element substrate 10 further above the sealing substrate 21. Furthermore, here, the element substrate 10 and the sealing substrates 21 and 31 have basically the same coefficient of thermal expansion as described above, and thus basically thermally expand uniformly. Therefore, even if thermal expansion is taken into consideration, the printer head 1 is hardly bent or twisted in practice.

  As a result, according to the printer head 1 of the present embodiment, the bending and twisting can be structurally suppressed, and the displacement can be sufficiently within the displacement error range allowed by the image forming apparatus. Therefore, by using this printer head 1 for an image forming apparatus, it is possible to stably supply a print image with good image quality.

Second Embodiment
Next, the configuration of the printer head according to the second embodiment will be described with reference to FIG. FIG. 6 is a cross-sectional view schematically showing the overall configuration of the printer head. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  The printer head 3 in the present embodiment is provided with a sealing film 23 instead of the sealing substrate 21 in the first embodiment. The sealing film 23 may be, for example, a single layer film or a multilayer film that is directly formed on the sealing region 10a with a material having low water permeability or oxygen permeability, or is directly attached to the sealing region 10a. It may be a single-layer or laminated sealing film. The sealing film 23 can be reliably sealed structurally by being in close contact with the organic EL light emitting element 11. Further, since the sealing film 23 is in close contact with the organic EL light emitting element 11, the occupied space area is small, which is advantageous for taking a multiple sealing structure with the sealing substrate 31.

  As described above, in the printer head 3 of the present embodiment as well, since the plurality of organic EL light emitting elements 11 are double-sealed, they are disposed in a high-temperature and high-humidity environment unique to an image forming apparatus such as a printer. Even in such a case, oxygen and moisture in the outside air can be prevented from entering the organic EL light emitting element 11 very well, and the life can be extended.

  Also in this case, the sealing substrate 31 is bonded to the element substrate 10, and the printer head 3 is given high rigidity so as to suppress the occurrence of bending and twisting. Furthermore, the element substrate 10 and the sealing substrate 31 have the same thermal expansion coefficient. Therefore, also in the present embodiment, bending and twisting of the printer head 3 are suppressed, and by using this printer head 3 for an image forming apparatus, it is possible to stably supply a print image with good image quality.

<Third Embodiment>
Next, the configuration of the printer head according to the second embodiment will be described with reference to FIG. FIG. 7 is a cross-sectional view schematically showing the overall configuration of the printer head.

  In the printer head 4 according to the present embodiment, the sealing region 10 a on the element substrate 10 is double-sealed by the sealing film 23 and the sealing substrate 41. As an example of the “third sealing substrate” of the present invention, the sealing substrate 41 is disposed to face the sealing region 10 a and is attached to the element substrate 10 with an adhesive layer 42. That is, the sealing substrate 41 is made of a material that is difficult to be bent and twisted and has a sealing ability, such as a quartz substrate or a glass substrate, and is sealed with the adhesive layer 42 and the sealing film 23 interposed therebetween. The stop area 10a is covered. Here, a substrate made of the same material as the element substrate 10 is used for the sealing substrate 41. The adhesive layer 42 is in close contact with the outer surface of the sealing film 23 so as to prevent oxygen and moisture from entering the gap between the sealing substrate 41 and the organic EL light emitting element 11. The adhesive layer 42 is made of, for example, a photocurable adhesive.

  Depending on the thickness of the adhesive layer 42, the sealing substrate 41 can provide a certain amount of space between the sealing substrate 41 and the organic EL light emitting element 11. Therefore, it is relatively easy to secure a space for providing the sealing film 23 therein, which is advantageous for taking a multiple sealing structure.

  As described above, in the printer head 4 of the present embodiment as well, since the plurality of organic EL light emitting elements 11 are double-sealed, they are disposed in a high-temperature and high-humidity environment unique to an image forming apparatus such as a printer. Even in such a case, oxygen and moisture in the outside air can be prevented from entering the organic EL light emitting element 11 very well, and the life can be extended.

  In this case, the sealing substrate 41 is bonded to the element substrate 10, and the printer head 4 is given high rigidity so as to suppress the occurrence of bending and twisting in terms of structure. Furthermore, the element substrate 10 and the sealing substrate 41 are made of the same material, so that their thermal expansion coefficients are uniform. Therefore, also in the present embodiment, bending and twisting of the printer head 4 are suppressed, and by using this printer head 4 for an image forming apparatus, it is possible to stably supply a print image with good image quality.

<Embodiment of Printer>
Next, with reference to FIG. 8, an embodiment according to a printer including the printer head of the above embodiment will be described. FIG. 8 is a schematic cross-sectional view showing the main configuration of the printer according to the present embodiment. In the following embodiment, a color printer having four printer heads for YMCK will be described as an example.

  In FIG. 8, the printer includes four image forming units 1001Y, 1001M, 100C, and 1001K for YMCK, each of which includes a photosensitive drum 1002 that is an example of the “photosensitive member” according to the present invention, and a surrounding area thereof. A cleaner 1011, a charger 1012, a printer head according to the above-described embodiment, a developing device 1013 that is an example of a “developing unit” according to the present invention, and a fixing unit 1040 that is an example of a “fixing unit” according to the present invention. Configured.

  Next, the configuration of the printer of this embodiment will be described along with its operation.

  In FIG. 8, after the toner remaining on the surface of the photosensitive drum 1002 in the previous cycle is removed by the cleaner 1011, the surface of the photosensitive drum 1002 is charged by corona discharge or the like by the charger 1012 for the current cycle. . Subsequently, an electrostatic latent image corresponding to the data signal is formed on the surface of the photosensitive drum 1002 by exposure according to the data signal by the printer head of the above-described embodiment. Subsequently, by using toner of a color corresponding to each unit among Y (yellow), M (magenta), C (cyan), and K (black), development is performed by the developing unit 1013, and the photosensitive drum 1002 is developed. A toner image that is a visible image by toner adhesion is formed on the surface. On the other hand, the transfer belt 1020 is rotated by rollers 1021, 1022, and the like. The toner image on the photosensitive drum 1002 is transferred onto the transfer belt 1020 while being pressed from the back side by the transfer roller 1014 at the transfer position facing each photosensitive drum 1002. The transferred toner image is further transferred onto a sheet 1050 such as a copy sheet conveyed by the conveying device 1030. That is, here, the transfer roller 1014, the transfer belt 1020, the conveying device 1030, and the like constitute an example of the “transfer means” of the present invention. Subsequently, the toner image transferred onto the sheet 1050 is fixed by being heated and pressed by the fixing device 1040. The fixing device 1040 includes a fixing roller 140 having a heat source and a pressure roller 240 pressed against the fixing roller 140. Then, the image-formed paper 1050 is discharged onto the discharge tray.

  The inside of the printer during this operation is considerably hot and humid as compared to a display or the like due to heat released from the fixing device 1040 and the like and moisture released from the paper 1050 heated by the fixing device 1040. For this reason, in a normal printer head, deterioration due to moisture is accelerated by heat, and its life is relatively short. However, since the double-sealed printer head according to the above-described embodiment is provided here, the deterioration can be sufficiently suppressed even under such a severe environment.

  In addition, even if each component of the printer head is thermally expanded due to an increase in ambient temperature, heat generation from the organic EL light emitting element 11, etc., as described in the above embodiment, the main members are made of a material that is not easily bent or twisted. The thermal expansion coefficient is uniform, the printer head is structurally rigid, and in the first embodiment, the heat from the organic EL light emitting element 11 is evenly distributed in the vertical direction. Due to conduction or the like, the printer head is hardly or practically not bent or twisted.

  For this reason, variations in the distance between the printer head and the optical system 60 or the photosensitive drum 1002 caused by the deformation of the printer head and the dot position deviation of the formed image between the image forming units can be prevented. Degradation of image quality is prevented.

  The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. A printer provided with this is also included in the technical scope of the present invention.

1 is a cross-sectional view illustrating a configuration of a printer head according to a first embodiment of the present invention. 1 is a perspective view illustrating an external configuration of a printer head according to a first embodiment. It is a block diagram which shows the electrical connection aspect in the printer head of 1st Embodiment. It is a perspective view showing a mode that the printer head of 1st Embodiment was integrated with the optical system by the supporting member. FIG. 5 is a cross-sectional view of the support member in a state where the printer head and the optical system shown in FIG. 4 are supported. It is sectional drawing which shows the structure of the printer head of 2nd Embodiment. It is sectional drawing which shows the structure of the printer head of 3rd Embodiment. 1 is a schematic cross-sectional view showing a main configuration of a printer according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3, 4 ... Printer head, 2 ... Main-body part, 10 ... Element board | substrate, 10a ... Sealing area | region, 11 ... Organic EL light emitting element, 11a ... Element area | region, 12 ... External circuit connection terminal, 13 ... Data line, 14 DESCRIPTION OF SYMBOLS ... Line scanning circuit, 15 ... Pixel circuit, 20 ... Drive part, 21, 31, 41 ... Sealing substrate, 22, 42 ... Adhesive layer, 23 ... Sealing film, 31a ... Concave part (of sealing substrate 31), 31b ... Space part, 1001Y, 1001M, 1001C, 1001K ... Image forming unit, 1002 ... Photosensitive drum, 1012 ... Charger, 1013 ... Developer, 1020 ... Transfer belt, 1030 ... Conveyor, 1040 ... Fixing device, 1050 ... Paper.

Claims (9)

An element substrate;
A plurality of light emitting elements arranged on the element substrate for exposing the photoreceptor;
An inner sealing means which is provided so as to be in contact with at least the plurality of light emitting elements of the element substrate and directly seals an element region where the plurality of light emitting elements are formed on the element substrate;
An outer sealing means provided so as to cover the outer surface of the inner sealing means and indirectly sealing the element region.   2. The printer according to claim 1, wherein the inner sealing unit is formed of a sealing material and includes a sealing film disposed on the element substrate so as to cover the plurality of light emitting elements. head.   The inner sealing means is made of a sealing material, and is filled between the first sealing substrate and the element substrate, the first sealing substrate being disposed to face the element substrate, and The printer head according to claim 1, further comprising an adhesive layer that affixes the first sealing substrate to the element substrate.   The outer sealing means is made of a sealing material and has a recess on one side, and is disposed on the element substrate so as to cover the plurality of light emitting elements with a space interposed in the recess. The printer head according to claim 1, comprising a second sealing substrate.   The printer head according to claim 4, wherein at least one of a dehydrating agent and an oxygen scavenger is sealed in the space.   The outer sealing means is made of a sealing material, and is filled between the third sealing substrate and the element substrate, and is filled between the third sealing substrate and the element substrate. 4. The printer head according to claim 1, further comprising an adhesive layer that affixes a third sealing substrate to the element substrate. 5.   The element substrate, the inner sealing means, and the outer sealing means are prevented from being deformed due to a difference in thermal expansion coefficient between the element substrate, the inner sealing means, and the outer sealing means. 7. The printer head according to claim 1, wherein at least two of them have the same thermal expansion coefficient.   At least one of the element substrate, the inner sealing unit, and the outer sealing unit is set so that a displacement amount due to heat falls within a displacement error range of a printer head allowed in the mounted image forming apparatus. The printer head according to any one of claims 1 to 7, wherein the printer head is made of a hardly deformable material. A printer head according to any one of claims 1 to 8,
The photoreceptor;
Developing means for forming a visible image by developing an electrostatic latent image formed on the photoreceptor by exposure by the printer head;
Transfer means for transferring the formed visible image onto a recording medium;
An image forming apparatus comprising: a fixing unit that fixes the transferred visible image on the recording medium.

Images