JP4281795B2 - Electro-optical device, image forming apparatus, and electro-optical device manufacturing method - Google Patents

Description

  The present invention relates to an electro-optical device including an electro-optical panel in which electro-optical elements such as light-emitting elements or light valve elements are arranged, an image forming apparatus using the electro-optical device, and a method for manufacturing the electro-optical device.

  In order to write an electrostatic latent image on an image carrier (for example, a photosensitive drum) of an electrophotographic image forming apparatus, a technique using an array of electroluminescent elements (hereinafter referred to as “EL elements”) has been developed. ing. In such a technique, a converging lens array is generally disposed between the EL element array and the image carrier. In such an arrangement, in order to reduce the loss of light emitted from the EL element, a technique of arranging a light transmissive spacer between the EL element array and the converging lens array is disclosed in Patent Document 1. Yes.

  FIG. 1 is a perspective view schematically showing a part of a conventional image forming apparatus. In this image forming apparatus, a converging lens array 40 is disposed between the light emitting panel 20 provided with the EL element array and the photosensitive drum 110, and the light transmissive lens 20 is disposed between the light emitting panel 20 and the converging lens array 40. A spacer 70 is disposed. As the converging lens array 40, for example, there is SLA (Selfoc Lens Array) available from Nippon Sheet Glass Co., Ltd. (Selfoc \ SELFOC is a registered trademark of Nippon Sheet Glass Co., Ltd.).

  FIG. 2 is a perspective view schematically showing the converging lens array 40. The converging lens array 40 includes a plurality of gradient index lenses 41 arranged in one direction in a two-row zigzag pattern. Each of the gradient index lenses 41 is a graded index optical fiber formed such that the refractive index at the central axis is low and the refractive index increases as the distance from the central axis increases. An erect image with respect to the image on the light emitting panel 20 can be formed on the photosensitive drum 110 by being transmitted. The images obtained by the plurality of gradient index lenses 41 constitute one continuous image on the photosensitive drum 110.

FIG. 3 is a cross-sectional view of the converging lens array 40 taken along a plane orthogonal to the arrangement direction of the gradient index lenses 41 (hereinafter referred to as “X direction”). As shown in this figure, the optical distance of the converging lens array 40 includes an object-side working distance (Lo), an image-side working distance (Li), and a conjugate length (TC). In order to sufficiently increase the optical characteristics (for example, sharpness) of the imaging, the photosensitive drum 110 and the converging lens array 40 are provided with the imaging surface P of the photosensitive drum 110 and the light exit surface S1 of the converging lens array 40. The light emitting panel 20 and the converging lens array 40 are arranged such that the distance (Di) between the light emitting panel 20 and the converging lens array 40 is equal to the distance between the light emitting surface Q in the light emitting panel 20 and the light incident surface S2 of the converging lens array 40 (see FIG. Do) is arranged to match Lo.
JP 2006-218848 A

  FIG. 4 is a side view schematically showing a part of a conventional image forming apparatus. As shown in this figure, Li and Lo of the converging lens array 40 usually vary in the X direction. For example, when attention is paid to the first position (x1), the second position (x2), and the third position (x3) arranged in order in the X direction, Li [x1], Li [x2], and Li [x3] at each position are They are different from each other, and Lo [x1], Lo [x2] and Lo [x3] at each position are also different from each other. Specifically, Li [x1] <Li [x3] << Li [x2] and Lo [x1] <Lo [x3] << Lo [x2].

  As is clear from the above-described example, variations in Li and Lo in the X direction can be nonlinear. On the other hand, the imaging plane P, the light emitting surface S1, the light incident surface S2, and the light emitting surface Q are each flat in the X direction. Therefore, the photosensitive drum 110 and the converging lens array 40 are arranged so that Di and Li coincide with each other with high accuracy over the entire length of the converging lens array 40, and Do and Lo are the total length of the converging lens array 40. It is difficult to arrange the light emitting panel 20 and the converging lens array 40 so as to match with high accuracy over a wide range. For this reason, in the conventional image forming apparatus, there is a possibility that the optical characteristics of image formation vary greatly in the X direction.

  FIG. 5 is a graph showing the characteristic of the imaging diameter R with respect to Di in the conventional image forming apparatus. The imaging diameter R is the diameter of the EL element image connected to the imaging plane P. The smaller the imaging diameter R, the higher the optical characteristics of imaging. A characteristic line C1 indicates a characteristic at a position (position in the X direction) where the difference between the ideal distance (Bo) matching Do and Lo is zero. When a half of the maximum difference between Lo and Bo is a (a> 0), the characteristic line C2 indicates the characteristic at the position where the difference between Do and Bo is a (position in the X direction). A line C3 indicates a characteristic at a position where the difference between Do and Bo is twice as large as a (position in the X direction).

  From the relative position of the characteristic lines C1 to C3, it can be seen that the smaller the difference between Do and Bo, the smaller the imaging diameter R. Further, it can be seen from the shape of each of the characteristic lines C1 to C3 that the imaging diameter R becomes smaller as the difference between the ideal distance (Bi) matching Di and Li becomes smaller. For example, in the characteristic line C1, when the difference between Di and Bi is 0 (point T1), the imaging diameter R (r1) is when the difference between Di and Bi is b (each point T2). R2 is smaller than R (r2), and r2 is smaller than the imaging diameter R (r3) when the difference between Di and Bi is twice b (each point T3). However, b> 0.

  When ½ of the maximum value of the difference between Li and Bi is b, the maximum fluctuation width (W1) of the imaging diameter R in the conventional image forming apparatus is the difference between r1 and r4. r4 is the imaging diameter R of the point T4 where the difference between Di and Bi is twice b and the difference between Do and Bo is twice a. The reason why the optical characteristics of image formation in the conventional image forming apparatus may vary greatly in the X direction is that W1 is too large.

  The present invention has been made in view of the above-described circumstances, and an electro-optical device capable of reducing variations in optical characteristics of imaging in the arrangement direction of the gradient index lens, and an image using the electro-optical device A forming apparatus and a method of manufacturing an electro-optical device are provided.

The electro-optical device according to the present invention includes a plurality of electro-optical elements whose light emission characteristics or light transmission characteristics are changed by given electric energy, and emits light from each of the plurality of electro-optical elements. A plurality of gradient index lenses arranged in one direction, and a plurality of gradient index lenses capable of forming an erect image with respect to an image on the electro optic panel by transmitting light traveling from the electro optic panel; A converging lens array in which an image obtained by a lens forms one continuous image; and a spacer that is sandwiched between the electro-optical panel and the converging lens array and transmits light traveling from the electro-optical panel. The spacer has a refractive index distribution part in which a plurality of members having different refractive indexes are continuous in the one direction.
According to this electro-optical device, since the spacer has a refractive index distribution portion in which a plurality of members having different refractive indexes are continuous in the arrangement direction of the gradient index lens, in the arrangement direction of the gradient index lens, Even if the distance between the electro-optical panel and the converging lens array is uniform, the optical distance between the electro-optical panel and the converging lens array can be made different. Therefore, according to this electro-optical device, the arrangement of the plurality of members in the refractive index distribution portion and the refractive index of each member are appropriately determined, so that the variation in the optical characteristics of the imaging in the arrangement direction of the gradient index lenses is reduced. Can be small.

  In the above electro-optical device, the spacer is a layer that crosses the optical axis of the gradient index lens, and the refractive index distribution part is included in the one layer. The spacer includes a plurality of layers crossing the optical axis of the gradient index lens, and the refractive index distribution part is included in at least one of the plurality of layers. . The latter embodiment includes an embodiment in which one or both of the light transmitting spacer body and the electro-optical panel and between the spacer body and the converging lens array are filled with a light transmitting adhesive.

In the above electro-optical device, the spacer includes a plurality of layers crossing the optical axis of the gradient index lens and at least two of the refractive index distribution portions, and the refractive index distribution portions each include the plurality of refractive index distribution portions. A refractive index distribution in the refractive index distribution portion included in each of at least two of the layers and included in one of the at least two layers; The refractive index distributions in the refractive index distribution portion included in one layer may be different from each other.
In this aspect, the optical distance between the electro-optical panel and the converging lens array is determined by the refractive index distribution in the refractive index distribution portion included in one of at least two layers sandwiched between them. This is in accordance with the refractive index distribution in the refractive index distribution portion included in another one of the at least two layers. Therefore, according to this aspect, the optical distance between the electro-optic panel and the converging lens array is diversified in the arrangement direction of the gradient index lens even if the number of types of members used for the gradient index portion is small. be able to. This is an advantage that contributes to further reducing variation in optical characteristics of imaging in the arrangement direction of the gradient index lenses.

The image forming apparatus according to the present invention includes an image carrier, a charger that charges the image carrier, and light that travels from the electro-optical panel and passes through the converging lens array. The electro-optical device or the electro-optical device according to each of the above aspects that forms a latent image by irradiating the surface, and development that forms a visible image on the image carrier by attaching toner to the latent image And a transfer device for transferring the visible image from the image carrier to another object.
According to the image forming apparatus, since the electro-optical device described above or the electro-optical device according to each aspect described above is provided, a high-quality image can be formed.

The method of manufacturing an electro-optical device according to the present invention includes a plurality of electro-optical elements whose light emission characteristics or light transmission characteristics change according to applied electric energy, and emits light from each of the plurality of electro-optical elements. A plurality of refractive index distribution type lenses arranged in one direction, and a plurality of refractive index distribution lenses capable of forming an erect image with respect to an image on the electro-optical panel by transmitting light traveling from the electro-optical panel. A converging lens array in which an image obtained by a rate distribution lens forms one continuous image, and a spacer that is sandwiched between the electro-optical panel and the converging lens array and transmits light traveling from the electro-optical panel A measuring step of measuring working distances on the object side of the converging lens array at a plurality of positions aligned in the one direction, and the measuring step An intervening step of interposing the spacer in which the refractive index is distributed according to the distribution of the working distance measured in the one direction between the electro-optical panel and the converging lens array. And
According to this manufacturing method, the spacer in which the refractive index is distributed according to the distribution of the working distance on the object side of the converging lens array in the arrangement direction of the gradient index lens is used as the electro-optical panel and the converging lens array. An electro-optical device interposed between the two can be manufactured. According to this electro-optical device, even if the distance between the electro-optical panel and the converging lens array is uniform in the arrangement direction of the gradient index lenses, the optical optical panel and the converging lens array are optically separated. The distance can be made different according to the distribution of the working distance on the object side of the converging lens array. Therefore, according to this electro-optical device, it is possible to reduce variations in optical characteristics of image formation in the arrangement direction of the gradient index lenses.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The scope of the present invention includes modifications obtained by modifying the embodiment. In the drawings, the ratio of dimensions of each part is appropriately changed from the actual one. In addition, the electro-optical device according to each embodiment of the present invention is provided on the image plane P of the image carrier (for example, the photosensitive drum 110 as shown in FIG. 1) in the image forming apparatus using the electrophotographic method. Used as a line-type optical head for writing a latent image.

<Electro-optical device>
<First Embodiment>
First, the electro-optical device 1A according to the first embodiment of the invention will be described. In the electro-optical device 1A, the spacer is one layer that crosses the optical axis of the gradient index lens, and the refractive index distribution portion is included in this layer. Details will be described below.

<Configuration>
First, the configuration of the electro-optical device 1A will be described.
FIG. 6 is a plan view of the electro-optical device 1A, and FIG. 7 is a side view (elevated view) of the electro-optical device 1A. The electro-optical device 1 </ b> A includes a light-emitting panel (electro-optical panel) 20, a converging lens array 40, and a light-transmitting spacer 80 sandwiched between the light-emitting panel and the converging lens array 40. The light-emitting panel 20 includes a light-transmissive element substrate 22, a plurality of EL elements 21 formed on the element substrate 22, and a sealing body 23 that covers these EL elements 21. The light from each is emitted from the light emitting surface S3 on the element substrate 22 side.

  Each EL element 21 is an electro-optical element whose light emission characteristics are changed by applied electric energy. Specifically, the EL element 21 is sandwiched between a light emitting layer that emits light when excited by recombination of injected carriers. The organic EL element has a pair of electrodes and emits light according to a voltage applied between the pair of electrodes. Of the pair of electrodes, the electrode on the element substrate 22 side is a transparent electrode such as ITO (Indium Tin Oxide). The light emitting panel 20 is provided with wiring for applying a driving voltage to each EL element 21. The light emitting panel 20 may be provided with a circuit element (for example, a TFT (Thin Film Transistor)) for applying a driving voltage to each EL element 21.

  The element substrate 22 is a flat plate made of a light transmissive material such as glass or transparent plastic, and its refractive index is n2. The EL elements 21 are arranged in two rows and staggered on the element substrate 22, and a plane passing through these EL elements 21 is a light emitting surface Q. The sealing body 23 is attached to the element substrate 22, and cooperates with the element substrate 22 to isolate the EL element 21 from the outside air, particularly moisture and oxygen, and suppress deterioration thereof.

  The converging lens array 40 transmits a part of the light incident on the light incident surface S2 and emits the light from the light emitting surface S1, and transmits the light traveling from the light emitting panel 20 so as to pass through the light emitting surface Q. A plurality of gradient index lenses 41 capable of forming an erect image with respect to an image (an image on the light emitting panel 20) are provided. The light incident surface S2 and the light emitting surface S3 of the light emitting panel 20 face each other, and the distance (Do) between the light emitting surface Q and the light emitting surface S3 is approximately the sum of the thickness of the element substrate 22 and the thickness of the spacer 80. Match. The electro-optical device 1 </ b> A is arranged so that the distance (Di) between the light emitting surface S <b> 1 and the imaging plane P matches the working distance (Li) on the image side of the converging lens array 40.

  Each gradient index lens 41 is arranged in two rows and zigzag in the X direction, and overlaps the region of the light emitting panel 20 where the EL elements 21 are formed. The images obtained by the plurality of gradient index lenses 41 constitute one continuous image. The arrangement pattern of the EL element 21 and the gradient index lens 41 is not limited to the illustrated form, and may be a single row or three or more rows, or may be arranged in another appropriate pattern.

  The spacer 80 is a layer of equal thickness that is filled between the light-emitting panel 20 and the converging lens array 40 to make the distance between them uniform, and extends across the optical axis of each gradient index lens 41. It is composed of a plurality of rectangular parallelepiped members 81 to 83 made of glass or transparent plastic, and transmits light traveling from the light emitting panel 20. Of the surface of the spacer 80, the entire surface on the light emitting panel 20 side is in contact with the light emitting surface S3 of the light emitting panel 20, and the entire surface of the light incident surface S2 of the converging lens array 40 is on the surface on the converging lens array 40 side. It touches.

  Each of the plurality of members 81 to 83 is in contact with the light emitting surface S3 of the light emitting panel 20 and the light incident surface S2 of the converging lens array 40. The refractive index of the member 82 is n3, and the refractive indexes of the member 81 and the member 83 sandwiching the member 82 are both n1. That is, the spacer 80 has a refractive index distribution portion in which members having different refractive indexes are continuous in the X direction. For this reason, the optical distance between the light emitting surface Q and the light incident surface S2 varies in the X direction.

n1 to n3, the thickness of the spacer 80, and the region occupied by each member 81 to 83 in the X direction (occupied region of each member 81 to 83) depends on the working distance (Lo) on the object side of the converging lens array 40. , So as to satisfy the formula (1). In the formula (1), m is the number of layers between the light emitting surface Q and the light incident surface S2. In the present embodiment, each of the spacer 80 and the element substrate 22 is counted as one. ni and di are the refractive index and thickness of the i-th layer.

  Usually, the refractive index (n2) of the element substrate 22 is determined according to the specifications that the light-emitting panel 20 should satisfy. The thickness of the spacer 80 is uniform in the X direction. Therefore, what is determined in accordance with the position in the X direction is the refractive index (n3) of the member 81 and the member 83, the refractive index (n1) of the member 82, and the occupied regions of the members 81 to 83. Specifically, as shown in FIG. 7, a member 81 made of a material having a relatively high refractive index (n1) occupies the vicinity of the first position (x1), and the vicinity of the third position (x3), as shown in FIG. Is formed by a member 83 formed of a material having a relatively high refractive index (n1), and a part 82 formed by a material having a relatively low refractive index (n3) is occupied in the vicinity of the second position (x2). It has been established. Therefore, as apparent from a comparison between FIG. 4 and FIG. 7, the deviation between the light emitting surface Q and the surface of the converging lens array 40 that is separated from the light incident surface S2 by an ideal distance (Bo) matching Lo is small. It is suppressed. Bo is the distance between the light emitting surface Q and the light incident surface S2 when the optical distance between the light emitting surface Q and the light incident surface S2 matches Lo.

  FIG. 8 is a graph showing characteristics of the imaging diameter R with respect to Di in an image forming apparatus using the electro-optical device 1A as an optical head. The imaging diameter R is the diameter of the EL element image connected to the imaging plane P. The smaller the imaging diameter R, the higher the optical characteristics of imaging. Among the characteristic lines C1 to C6, the characteristic lines C1 to C3 are the same as those shown in FIG. 4, and the characteristic lines C4 to C6 indicate the characteristics related to the electro-optical device 1A.

  The characteristic line C4 indicates the characteristic at the position where the difference between Do and Bo is 0 (position in the X direction), and the characteristic line C5 indicates that ½ of the maximum value of the difference between Lo and Bo is g. (G> 0), the difference between Do and Bo indicates the characteristic at the position of g (position in the X direction), and the characteristic line C6 indicates that 1/2 of the maximum value of the difference between Lo and Bo is g In this case, the difference between Do and Bo shows a characteristic at a position (position in the X direction) that is twice g. The characteristic line C4 is completely coincident with the characteristic line C1.

  As described above, in the electro-optical device 1A, the deviation between the light emitting surface Q and the surface separated from the light incident surface S2 of the converging lens array 40 by Bo is suppressed. Therefore, the maximum difference between Do and Bo is smaller than that in the conventional image forming apparatus. That is, g <a. For this reason, as shown in FIG. 8, the density of the characteristic lines C4 to C6 is higher than the density of the characteristic lines C1 to C3, and the imaging diameter R of the image forming apparatus using the electro-optical device 1A as an optical head. The maximum fluctuation range (W2) is smaller than W1. W2 is the difference between r1 and r5, and r5 is the imaging diameter at point T5 where the difference between Di and Bi is twice b and the difference between Do and Bo is twice g. R.

  As described above, the electro-optical device 1 </ b> A includes the light-emitting panel 20 and the gradient index lens 41 that transmits the light traveling from the light-emitting panel 20 and can form an upright image with respect to the image on the light-emitting panel 20. A plurality of light emitting panels arranged in a direction and sandwiched between a converging lens array 40 in which an image obtained by a plurality of gradient index lenses 41 forms one continuous image, and the light emitting panel 20 and the converging lens array 40. And a spacer 80 that transmits the light traveling from 20. The spacer 80 has a refractive index distribution portion in which a plurality of members (member 81 and member 82 or member 82 and member 83) having different refractive indexes are continuous in the X direction. Therefore, according to the electro-optical device 1A, the optical distance between the light emitting panel 20 and the converging lens array 40 is uniform even though the distance between the light emitting panel 20 and the converging lens array 40 is uniform in the X direction. Can be different. In the electro-optical device 1 </ b> A, the arrangement of the members 81 to 83 and the refractive index of each member are appropriately determined according to the Lo of the converging lens array 40. Therefore, according to the electro-optical device 1A, it is possible to reduce variation in optical characteristics of image formation in the X direction.

<Manufacturing method>
Next, a method for manufacturing the electro-optical device 1A will be described. Various methods are conceivable as a method of manufacturing the electro-optical device 1A. Here, manufacturing method 1 and manufacturing method 2 are illustrated.
<Manufacturing method 1>
In the manufacturing method 1, first, the light emitting panel 20 and the spacer 80 are manufactured. In the manufacture of the light-emitting panel 20, a light-transmitting flat plate having a refractive index of n2 is used as the element substrate 22, and the EL elements 21 are arranged in two rows and staggered on the flat plate. In manufacturing the spacer 80, first, Lo of the converging lens array 40 is measured. In this measurement, for example, only air is interposed between the light source and the converging lens array 40, and the relative position between the light source and the converging lens array 40 is variable. In a system in which the relative position is fixed, an operation is performed in which the distance between the light emitting surface and the converging lens array 40 is Lo when the diameter of the image formed by the light emitted from the light source and transmitted through the converging lens array 40 is minimized. This is repeated over the entire length of the converging lens array 40.

  In manufacturing the spacer 80, next, the refractive indexes, dimensions, and arrangements of the members 81 to 83 are determined according to the measured Lo, and then the members 81 to 83 are joined. Specifically, when the refractive index of the member 81 and the component 83 is set to n1, the refractive index of the member 82 is set to n3, and the occupied areas of the members 81 to 83 are joined in one direction when the members 81 to 83 are joined. When the member 82 is interposed between the member 81 and the member 83 and the one direction coincides with the X direction, the member 81 occupies the vicinity of the first position (x1), and the member 82 occupies the second position (x2). And the member 83 is determined to occupy the vicinity of the third position (x3).

  Next, as shown in FIG. 9, a spacer 80 is bonded to the light emitting panel 20. In this bonding, the entire area of one widest surface of the spacer 80 is in contact with the light emitting surface S3 of the light emitting panel 20, and the entire area of the light emitting panel 20 where the EL elements 21 are formed overlaps the widest surface. This is performed so that the arrangement direction of the EL elements 21 matches. Next, as shown in FIG. 10, the converging lens array 40 is bonded to the spacer 80. In this joining, the entire region of the light incident surface S2 of the converging lens array 40 is in contact with the other widest surface of the spacer 80, and the arrangement direction (X direction) of the gradient index lens 41 of the converging lens array 40 and the one direction described above. Are matched so that each gradient index lens 41 overlaps the region where the EL element 21 of the light emitting panel 20 is formed.

  Next, the relative positions of the light emitting panel 20, the spacer 80, and the converging lens array 40 are fixed. The fixing method is arbitrary. For example, the side surface of the spacer 80 may be bonded to the light emitting panel 20 and the converging lens array 40, or the light emitting panel 20 and the converging lens array 40 are biased toward the spacer 80. The light emitting panel 20, the spacer 80, and the converging lens array 40 may be accommodated in a case.

<Manufacturing method 2>
In the manufacturing method 2, first, the light emitting panel 20 and the member 82 are manufactured. In the manufacture of the member 82, first, Lo of the converging lens array 40 is measured, and then the refractive index, size, and arrangement of each of the members 81 to 83 are determined according to the measured Lo to form the member 82. To do.

  Next, as shown in FIG. 11, the spacer 80 is bonded to the light emitting panel 20, and the converging lens array 40 is bonded to the spacer 80. Next, as shown in FIG. 12, a transparent adhesive having a refractive index n1 is injected between the light emitting panel 20 and the converging lens array 40, and this is cured to form members 81 and 83. In addition, you may use a guide frame so that the outflow of the adhesive agent with fluidity before hardening may be prevented and the adhesive agent may be solidified into a desired shape.

<Second Embodiment>
Next, an electro-optical device 1B according to a second embodiment of the invention will be described. In the electro-optical device 1B, the spacer has a plurality of layers crossing the optical axis of the gradient index lens, and at least two of these layers each include a refractive index distribution portion. Hereinafter, differences from the electro-optical device 1A will be described in detail.

<Configuration>
First, the configuration of the electro-optical device 1B will be described.
FIG. 13 is a side view (elevated view) of the electro-optical device 1B. The electro-optical device 1B is different from the electro-optical device 1A in that a spacer 90 is provided instead of the spacer 80. The spacer 90 is a component that is filled between the light-emitting panel 20 and the converging lens array 40 so that the distance between the two is uniform, and the light transmission property that extends across the optical axis of each gradient index lens 41. The plurality of layers 91 to 93 are configured to transmit light traveling from the light emitting panel 20.

  The layer 91 is a spacer body having an equal thickness sandwiched between the layers 92 and 93, and is made of glass or transparent plastic. The refractive index of the layer 91 is n1. The entire surface of the layer 91 on the light emitting panel 20 side is bonded to the entire surface of the layer 92 on the converging lens array 40 side, and the entire surface of the layer 91 on the converging lens array 40 side is bonded to the layer 93. It is joined to the entire surface on the light emitting panel 20 side.

  The layer 92 is an adhesive layer having an equal thickness sandwiched between the layer 91 and the light emitting panel 20, and includes a plurality of rectangular parallelepiped members 921 to 923 that are continuous in the X direction. The member 922 is formed of a transparent adhesive having a refractive index of n6, and the member 921 and the member 923 are each formed of a transparent adhesive having a refractive index of n5. That is, the layer 92 includes a refractive index distribution portion in which members having different refractive indexes are continuous in the X direction.

  The layer 93 is an adhesive layer having an equal thickness sandwiched between the layer 91 and the converging lens array 40, and includes a plurality of rectangular parallelepiped members 931 to 933. The member 931 is formed of a transparent adhesive having a refractive index of n5, and the member 932 is formed of a transparent adhesive having a refractive index of n6. That is, the layer 93 is also a refractive index distribution portion in which members having different refractive indexes are continuous in the X direction. The refractive index distribution in the refractive index distribution portion does not completely match the refractive index distribution in the refractive index distribution portion included in the layer 92. That is, both distributions are different from each other.

  The regions occupied by the members 921 to 923 and 931 to 932 in the X direction and the thicknesses of the layers n2 and n4 to n6 and the layers 91 to 93 (occupied regions of the members 921 to 923 and 931 to 932) Is determined so as to satisfy the expression (1). n2 is normally determined according to the specifications to be satisfied by the light-emitting panel 20, and since the refractive index (n4) of the layer 91 and the thicknesses of the layers 91 to 93 are uniform in the X direction, depending on the position in the X direction. Are defined by n5 and n6, and the occupied areas of the members 921 to 923 and 931 to 932.

  As is clear from the above description, the electro-optical device 1B has the same effects as the electro-optical device 1A. When either one of the layer 92 and the layer 93 is not present, the optical distance between the light emitting surface Q and the light incident surface S2 can be varied using a member having a refractive index of n5 and a member having a refractive index of n6. However, in the electro-optical device 1B, the spacer 90 has a layer 92 that includes a refractive index distribution portion and a layer 93 that is a different refractive index distribution portion. Since the refractive index distribution in the refractive index distribution portion included in the layer 92 and the refractive index distribution in the layer 93 are different from each other, more types of optical distances can be obtained. This is an advantage that contributes to further reducing variation in optical characteristics of imaging in the X direction.

<Manufacturing method>
Next, a method for manufacturing the electro-optical device 1B will be described. Various methods are conceivable as a method of manufacturing the electro-optical device 1B. Here, one manufacturing method is illustrated.
First, the light emitting panel 20 and the layer 91 are manufactured. In manufacturing the layer 91, first, Lo of the converging lens array 40 is measured, and then the refractive index and thickness of the layer 91 and the refraction of each member 921 to 923, 931, 932 are measured according to the measured Lo. The rate and occupied area are determined, and then a layer 91 having a refractive index of n4 is formed.

  Next, as shown in FIG. 14, an area occupied by the member 922 on the light emitting surface S3 of the light emitting panel 20 is coated with a transparent adhesive having a refractive index of n6, and this adhesive is applied to the light emitting panel 20 and the layer. It compresses until it becomes the thickness defined by 91, and it makes it harden | cure in that state. That is, the layer 91 is bonded to the light emitting panel 20. The cured adhesive becomes a member 922. Next, as shown in FIG. 15, a transparent adhesive having a refractive index of n5 is injected between the light emitting panel 20 and the layer 91, and is cured. The cured adhesive becomes member 921 and member 923.

  Next, as shown in FIG. 16, the occupied area of the member 932 on the surface of the layer 91 on the side of the converging lens array 40 is coated with a transparent adhesive having a refractive index of n6, and this adhesive is applied to the layer 91. And the converging lens array 40 are compressed to a predetermined thickness and cured in that state. That is, the converging lens array 40 is bonded to the layer 91. The cured adhesive becomes a member 932. Next, as shown in FIG. 17, a transparent adhesive having a refractive index of n5 is injected between the layer 91 and the converging lens array 40 and cured. The cured adhesive becomes a member 931.

  In the step of coating or injecting the adhesive, a guide frame may be used so as to prevent the flowable adhesive from flowing out before curing and to solidify the adhesive into a desired shape. Further, in order to ensure that the thickness of the compressed adhesive is appropriate, a solid gap securing material may be included in the compressed adhesive. As the gap securing material, a material having optical transparency, a ball shape, and a refractive index substantially equal to the surrounding adhesive is preferable.

<Image forming apparatus>
Each of the electro-optical devices according to the embodiments of the present invention can be used as a line-type optical head for writing a latent image on an image carrier in an image forming apparatus using an electrophotographic system. Examples of the image forming apparatus include a printer, a printing part of a copying machine, and a printing part of a facsimile.

  FIG. 18 is a longitudinal sectional view of the image forming apparatus according to the embodiment of the present invention. This image forming apparatus is a tandem type full color image forming apparatus using a belt intermediate transfer body system. In this image forming apparatus, four optical heads 10K, 10C, 10M, and 10Y having the same configuration are exposed positions of four photosensitive drums (image carriers) 110K, 110C, 110M, and 110Y having the same configuration. Respectively. Optical heads 10K, 10C, 10M, and 10Y are electro-optical devices according to embodiments of the present invention.

  As shown in the figure, this image forming apparatus is provided with a driving roller 121 and a driven roller 122. An endless intermediate transfer belt 120 is wound around these rollers 121 and 122, as indicated by arrows. Are rotated around the rollers 121 and 122. Although not shown, tension applying means such as a tension roller that applies tension to the intermediate transfer belt 120 may be provided.

  Around the intermediate transfer belt 120, photosensitive drums 110K, 110C, 110M, and 110Y having photosensitive layers on four outer peripheral surfaces are arranged at predetermined intervals. The subscripts K, C, M, and Y mean that they are used to form black, cyan, magenta, and yellow visible images, respectively. The same applies to other members. The photosensitive drums 110K, 110C, 110M, and 110Y are rotationally driven in synchronization with the driving of the intermediate transfer belt 120.

  Around each photosensitive drum 110 (K, C, M, Y), there is a corona charger 111 (K, C, M, Y), an optical head 10 (K, C, M, Y), and a developing unit. 114 (K, C, M, Y) are arranged. The corona charger 111 (K, C, M, Y) uniformly charges the outer peripheral surface of the corresponding photosensitive drum 110 (K, C, M, Y). The optical head 10 (K, C, M, Y) writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum. Each optical head 10 (K, C, M, Y) is installed such that the arrangement direction of the plurality of EL elements 21 is along the bus (main scanning direction) of the photosensitive drum 110 (K, C, M, Y). The The electrostatic latent image is written by irradiating the photosensitive drum with light by the plurality of EL elements 21 described above. The developing device 114 (K, C, M, Y) forms a visible image, ie, a visible image, on the photosensitive drum by attaching toner as a developer to the electrostatic latent image.

  The black, cyan, magenta, and yellow developed images formed by the four-color single-color image forming station are sequentially transferred onto the intermediate transfer belt 120 to be superimposed on the intermediate transfer belt 120. As a result, a full-color visible image is obtained. Four primary transfer corotrons (transfer devices) 112 (K, C, M, Y) are arranged inside the intermediate transfer belt 120. The primary transfer corotron 112 (K, C, M, Y) is disposed in the vicinity of the photosensitive drum 110 (K, C, M, Y), and the photosensitive drum 110 (K, C, M, Y). The electrostatic image is electrostatically attracted from the toner image to transfer the visible image to the intermediate transfer belt 120 passing between the photosensitive drum and the primary transfer corotron.

  A sheet 102 as an object on which an image is to be finally formed is fed one by one from the sheet feeding cassette 101 by the pickup roller 103, and between the intermediate transfer belt 120 and the secondary transfer roller 126 in contact with the driving roller 121. Sent to the nip. The full-color visible image on the intermediate transfer belt 120 is secondarily transferred to one side of the sheet 102 by the secondary transfer roller 126 and fixed on the sheet 102 by passing through a fixing roller pair 127 as a fixing unit. . Thereafter, the sheet 102 is discharged onto a paper discharge cassette formed in the upper part of the apparatus by a paper discharge roller pair 128.

  FIG. 19 is a longitudinal sectional view of another image forming apparatus according to the embodiment of the present invention. This image forming apparatus is a rotary developing type full-color image forming apparatus using a belt intermediate transfer body system. In the image forming apparatus shown in FIG. 19, a corona charger 168, a rotary developing unit 161, an optical head 167, and an intermediate transfer belt 169 are provided around a photosensitive drum (image carrier) 165. The optical head 167 is an electro-optical device according to an embodiment of the present invention.

  The corona charger 168 uniformly charges the outer peripheral surface of the photosensitive drum 165. The optical head 167 writes an electrostatic latent image on the charged outer peripheral surface of the photosensitive drum 165. The optical head 167 is an electro-optical device or an electro-optical device according to a modification thereof, and is installed such that the arrangement direction of the plurality of EL elements 21 is along the bus line (main scanning direction) of the photosensitive drum 165. The electrostatic latent image is written by irradiating the photosensitive drum with light by the plurality of EL elements 21 described above.

  The developing unit 161 is a drum in which four developing units 163Y, 163C, 163M, and 163K are arranged at an angular interval of 90 °, and can rotate counterclockwise about the shaft 161a. The developing units 163Y, 163C, 163M, and 163K supply yellow, cyan, magenta, and black toners to the photosensitive drum 165, respectively, and attach the toner as a developer to the electrostatic latent image, thereby the photosensitive drum 165. A visible image, that is, a visible image is formed.

  The endless intermediate transfer belt 169 is wound around a driving roller 170a, a driven roller 170b, a primary transfer roller 166, and a tension roller, and is rotated around these rollers in a direction indicated by an arrow. The primary transfer roller 166 transfers the visible image to the intermediate transfer belt 169 that passes between the photosensitive drum and the primary transfer roller 166 by electrostatically attracting the visible image from the photosensitive drum 165.

  Specifically, in the first rotation of the photosensitive drum 165, an electrostatic latent image for a yellow (Y) image is written by the optical head 167, and a developed image of the same color is formed by the developing device 163Y. The image is transferred to the transfer belt 169. Further, in the next rotation, an electrostatic latent image for a cyan (C) image is written by the optical head 167, and a developed image of the same color is formed by the developing device 163C, and an intermediate transfer is performed so as to overlap the yellow developed image. Transferred to the belt 169. Then, during the four rotations of the photosensitive drum 9, the yellow, cyan, magenta, and black visible images are sequentially superimposed on the intermediate transfer belt 169. As a result, a full-color visible image is formed on the transfer belt 169. It is formed. When images are finally formed on both sides of a sheet as an object on which an image is to be formed, the same color images of the front and back surfaces are transferred to the intermediate transfer belt 169, and then the front and back surfaces are transferred to the intermediate transfer belt 169. A full-color visible image is obtained on the intermediate transfer belt 169 by transferring the visible image of the next color.

  The image forming apparatus is provided with a sheet conveyance path 174 through which a sheet passes. The sheets are picked up one by one from the paper feed cassette 178 by the pick-up roller 179, advanced through the sheet transport path 174 by the transport roller, and between the intermediate transfer belt 169 and the secondary transfer roller 171 in contact with the drive roller 170a. Pass through the nip. The secondary transfer roller 171 transfers the developed image to one side of the sheet by electrostatically attracting a full-color developed image from the intermediate transfer belt 169 collectively. The secondary transfer roller 171 can be moved closer to and away from the intermediate transfer belt 169 by a clutch (not shown). The secondary transfer roller 171 is brought into contact with the intermediate transfer belt 169 when a full-color visible image is transferred onto the sheet, and is separated from the secondary transfer roller 171 while the visible image is superimposed on the intermediate transfer belt 169.

The sheet on which the image has been transferred as described above is conveyed to the fixing device 172 and is passed between the heating roller 172a and the pressure roller 172b of the fixing device 172, whereby the visible image on the sheet is fixed. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the direction of arrow F. In the case of double-sided printing, after most of the sheet passes through the paper discharge roller pair 176, the paper discharge roller pair 176 is rotated in the reverse direction and introduced into the double-sided printing conveyance path 175 as indicated by an arrow G. The Then, the visible image is transferred to the other surface of the sheet by the secondary transfer roller 171, the fixing process is performed again by the fixing device 172, and then the sheet is discharged by the discharge roller pair 176.
According to each image forming apparatus described above, since the electro-optical device according to the embodiment of the present invention is used as the optical head, a high-quality image can be formed.

  The image forming apparatus to which any of the electro-optical devices according to the embodiments of the invention can be applied has been described above, but the electro-optical device according to the embodiments of the invention can be applied to other electrophotographic image forming apparatuses. Any of the apparatuses can be applied, and such an image forming apparatus is within the scope of the present invention. For example, an image forming apparatus of a type that directly transfers a visible image from a photosensitive drum to a sheet without using an intermediate transfer belt, or an image forming apparatus that forms a monochrome image.

<Other variations>
In the second embodiment described above, the layer 92 and the layer 93 each have a refractive index distribution portion, but this is modified, and only one of the layer 92 and the layer 93 has a refractive index distribution portion. It is good also as a form. In addition, the first embodiment described above may be modified so that the spacer 80 includes a member that does not constitute the refractive index distribution portion. Similarly, the second embodiment described above may be modified so that at least one of the layer 92 and the layer 93 includes a member that does not constitute the refractive index distribution portion. Furthermore, the embodiment described above may be modified so that the spacer includes three or more layers each having a refractive index distribution portion.

  In each of the above-described embodiments, the bottom emission type light emitting panel 20 in which the light emitted from each EL element 21 passes through the element substrate 22 and is emitted from the light emitting panel 20 is used. A top emission type light emitting panel that emits light in the direction may be used. That is, the object that transmits the light traveling from the plurality of electro-optical elements may be a sealing body. In this case, the light transmittance of each part is determined so that the light emitted from each EL element and traveling to the sealing body side is not blocked.

  In each of the above-described embodiments, the organic EL elements that require excitation by recombination of carriers are employed as the plurality of electro-optical elements whose light emission characteristics or light transmission characteristics change depending on the applied electric energy. , A light-emitting element that does not require carrier recombination (for example, an inorganic EL element), a light-emitting element that does not require excitation (for example, an inorganic LED), or a light valve element whose light transmission characteristics change depending on applied electric energy (for example, A liquid crystal element) may be employed.

It is a perspective view which shows the outline of a part of conventional image forming apparatus. 2 is a perspective view showing an outline of a converging lens array 40. FIG. 3 is a cross-sectional view of a converging lens array 40. FIG. It is a side view which shows the outline of a part of conventional image forming apparatus. It is a graph which shows the characteristic of the imaging diameter R in the conventional image forming apparatus. 1 is a plan view of an electro-optical device 1A according to a first embodiment of the present invention. It is a side view (elevated view) of the electro-optical device 1A. 6 is a graph showing characteristics of an imaging diameter R in an image forming apparatus using the electro-optical device 1A as an optical head. It is a figure which shows the first process of manufacture of the electro-optical apparatus 1A (manufacturing method 1). FIG. 10 is a diagram showing a step subsequent to that in FIG. 9. It is a figure which shows the first process of manufacture of the electro-optical apparatus 1A (manufacturing method 2). FIG. 12 is a diagram showing a step subsequent to FIG. 11. It is a side view (elevated view) of an electro-optical device 1B according to a second embodiment of the present invention. It is a figure which shows the first process of manufacture of the electro-optical apparatus 1B. It is a figure which shows the next process of FIG. FIG. 16 is a diagram showing a step subsequent to that in FIG. 15. FIG. 17 is a diagram showing a step subsequent to that in FIG. 16. 1 is a longitudinal sectional view illustrating an example of an image forming apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the other example of the image forming apparatus which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1A, 1B ... Electro-optical device, 20 ... Light emission panel (electro-optical panel), 21 ... EL element (electro-optical element), 22 ... Element substrate, 23 ... Sealing body, 40 ... Converging lens array, 41 ... Refractive index Distributed lens, 80 ... spacer (refractive index distribution part), 90 ... spacer, 91 ... layer, 92, 93 ... layer (refractive index distribution part), 110, 165 ... photosensitive drum (image carrier), 111, 168 ... corona charger (charger), 114,163 ... developer, 112 ... primary transfer corotron (transfer device), 166 ... primary transfer roller (transfer device), 10K, 10C, 10M, 10Y, 167 ... optical head (electric) Optical device).

Claims (5)

An electro-optical panel having a plurality of electro-optical elements whose light emission characteristics or light transmission characteristics are changed by given electric energy, and emitting light from each of the plurality of electro-optical elements;
A plurality of gradient index lenses that transmit light traveling from the electro-optic panel and can form an erect image with respect to the image on the electro-optic panel are arranged in one direction, and are obtained by the plurality of gradient index lenses. A converging lens array in which the captured images constitute one continuous image;
A spacer that is sandwiched between the electro-optical panel and the converging lens array and transmits light traveling from the electro-optical panel;
The spacer has a refractive index distribution portion in which a plurality of members having different refractive indexes are continuous in the one direction.
An electro-optical device. The spacer has a plurality of layers crossing the optical axis of the gradient index lens,
The refractive index distribution part is included in at least one of the plurality of layers.
The electro-optical device according to claim 1. The spacer has a plurality of layers crossing the optical axis of the gradient index lens and at least two of the gradient index portions,
Each of the refractive index distribution portions is included in each of at least two layers of the plurality of layers,
The refractive index distribution in the refractive index distribution portion included in one of the at least two layers, and the refractive index distribution portion included in another one of the at least two layers. The refractive index distributions are different from each other.
The electro-optical device according to claim 1. An image carrier;
A charger for charging the image carrier;
4. The latent image is formed by irradiating a charged surface of the image carrier with light that travels from the electro-optical panel and passes through the converging lens array. 5. An electro-optic device;
A developing unit that forms a visible image on the image carrier by attaching toner to the latent image; and
A transfer device for transferring the visible image from the image carrier to another object;
An image forming apparatus comprising: An electro-optical panel having a plurality of electro-optical elements whose light emission characteristics or light transmission characteristics are changed by given electric energy, and emitting light from each of the plurality of electro-optical elements;
A plurality of gradient index lenses that transmit light traveling from the electro-optic panel and can form an erect image with respect to the image on the electro-optic panel are arranged in one direction, and are obtained by the plurality of gradient index lenses. A converging lens array in which the captured images constitute one continuous image;
A method of manufacturing an electro-optical device comprising a spacer that is sandwiched between the electro-optical panel and the converging lens array and transmits light traveling from the electro-optical panel,
A measurement step of measuring the working distance on the object side of the converging lens array at a plurality of positions aligned in the one direction;
An intervening step of interposing the spacer in which the refractive index is distributed according to the distribution in the one direction of the working distance measured in the measuring step between the electro-optic panel and the converging lens array;
A method for manufacturing an electro-optical device.

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