JP2006119606A - Exposure head and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize exposure density in spite of a fluctuation in the distance between an exposure head consisting of light emitting element arrays and a photosensitive material in an exposure device of performing vertical scanning by relatively moving the exposure head and the photosensitive material. <P>SOLUTION: The exposure head 1 is equipped with the light emitting element arrays 6R, 6G, and 6B consisting of a plurality of light emitting elements installed adjacently to each other in at least one direction apart spacing from each other, and an imaging lens 7a for forming the images by these light emitting elements on a photosensitive material, wherein the exposure head satisfies the relation 0.6≤B×C<SP>2</SP>/A when the maximum pixel area of the photosensitive material arranged in the focal position of an imaging lens 7a, the light emitting areas of the light emitting elements, and the magnification of the imaging lens are respectively defined as A, B and C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure head using a light emitting element array, and an exposure apparatus that exposes a photosensitive material using the exposure head.

  Conventionally, as disclosed in, for example, Patent Document 1 and Patent Document 2, color exposure using an exposure head composed of a plurality of line-shaped light emitting element arrays each emitting light in different wavelength regions such as red, green, and blue. Devices for exposing materials are known.

  The line-shaped light emitting element array includes a plurality of light emitting elements such as organic EL (electroluminescence) light emitting elements arranged in a line. In the exposure head, a plurality of line-shaped light emitting element arrays that emit light of different colors are arranged in parallel to each other in a direction substantially perpendicular to the direction in which the light emitting elements are arranged. An imaging lens that forms an image on the material is provided.

An exposure apparatus using such an exposure head holds a color photosensitive material at a position where light emitted from the exposure head is irradiated, and the photosensitive material and the exposure head are arranged in an alignment direction of the linear light emitting element array ( In other words, sub-scanning means for relatively moving in the direction substantially perpendicular to the direction in which the light emitting elements are arranged in each array is further provided.
JP-A-5-92622 JP 2000-13571 A

  By the way, in the above-described light emitting element array, it is practically impossible to arrange a plurality of light emitting elements such as organic EL light emitting elements without gaps, and these light emitting elements are arranged at intervals. ing. Therefore, in an exposure apparatus that performs image exposure using the light emitting element array having such a structure, it is difficult to expose the photosensitive material without any gap in the main scanning direction (light emitting element arrangement direction). That is, the pixels formed on the photosensitive material by this exposure are discrete without being in close contact with each other.

  On the other hand, when the photosensitive material and the exposure head are moved relative to each other by the sub-scanning means described above to expose a two-dimensional image on the photosensitive material, the distance between the photosensitive material and the exposure head is associated with the relative movement. May fluctuate. As described above, when the pixels formed on the photosensitive material are discrete from each other, if the distance between the photosensitive material and the exposure head changes in this manner, the exposure area on the photosensitive material changes. If so, the density obtained with the same exposure amount fluctuates and the exposure density becomes unstable.

  In particular, when a photosensitive material is sub-scanned and a sheet-like instant film is used as the photosensitive material, the distance between the photosensitive material and the exposure head varies due to variations in the sub-scanning mechanism, film thickness deviation in the sheet, etc. For this reason, the density unevenness occurs, and the print quality is deteriorated. Since the visibility limit of density unevenness on a general instant film is about 0.06, in order to maintain good print quality, the density change is required to be approximately 0.06 or less.

  In view of the above circumstances, an object of the present invention is to provide an exposure apparatus capable of suppressing print density fluctuation and avoiding deterioration in print quality even when the distance between the photosensitive material and the exposure head varies.

  Another object of the present invention is to provide an exposure head that realizes the exposure apparatus as described above.

As described above, the exposure head according to the present invention forms a light-emitting element array composed of a plurality of light-emitting elements arranged in parallel at least in one direction at an interval and an image formed by these light-emitting elements on a photosensitive material. In an exposure head including an imaging lens, when the maximum pixel area, the light emitting area of the light emitting element, and the magnification of the imaging lens are A, B, and C, respectively, in the photosensitive material arranged at the focal position of the imaging lens 0.6 ≦ B × C ² / A.

  Here, the maximum pixel area means that when a plurality of rectangular pixels (which may be square or rectangular) are arranged on the photosensitive material in the main scanning direction, that is, the arrangement direction of the light spots by the light emitting elements, they are mutually connected. It means the area of pixels that are closely aligned without overlapping and without a gap between them.

  In the exposure head having the above-described configuration, it is preferable to use an equal magnification lens as the imaging lens.

  An exposure apparatus according to the present invention includes the above-described exposure head according to the present invention, and sub-scanning means for relatively moving the exposure head and the photosensitive material in a direction substantially perpendicular to the one direction. .

Tables 1 to 7 below show the results of evaluating the print density stability when the value of B × C ² / A (numbers in each column) is variously changed. The evaluation is based on the density difference with respect to the print density at the focal position when the photosensitive material is present at the focal position of the original imaging lens, when moved by 200 μm from the focal position, and when moved by 400 μm from the focal position. Based on what happens. In addition, as described above, the case of moving by 200 μm and 400 μm was evaluated because the movement of about 200 μm can occur due to the flatness of the photosensitive material, and the movement of about 200 μm can further occur due to the position variation of the sub-scanning mechanism. This is because of this. The evaluation results indicated by ◯, Δ, and X in each column are approximately 0.06 (over 0.05 when the difference from the print density at the focal position is less than 0.05 in any gradation region. Less than 0.07), it is 0.07 or more, and it is larger than that.

As shown in the area within the thick frame line in these tables, in all cases where the relationship of 0.6 ≦ B × C ² / A is satisfied, the evaluation of ◯ that the print density difference is less than 0.05, Or the evaluation of (triangle | delta) that this print density difference is about 0.06 (more than 0.05 and less than 0.07) is obtained. Thus, it is clear that the exposure density can be stabilized even if the distance between the photosensitive material and the exposure head varies if the relationship of 0.6 ≦ B × C ² / A is satisfied. In addition, especially when the relationship of 0.7 ≦ B × C ² / A is satisfied, since the above print density difference is evaluated as ◯ that is less than 0.05, the exposure density is particularly good. In order to stabilize, it is desirable to satisfy the relationship of 0.7 ≦ B × C ² / A.

  Note that, in the exposure head of the present invention, particularly when an equal magnification lens (C = 1) is used as the imaging lens, the image area of the light emitting element in the photosensitive material arranged at the focal position of the imaging lens is: Since it becomes equal to the light emitting area of the light emitting element, this image area is considered as B, and the relationship of 0.6 ≦ B / A may be satisfied.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a partially broken front shape of an exposure apparatus according to an embodiment of the present invention, and FIG. 2 shows a partially broken side shape of the exposure apparatus. As shown in the drawing, this exposure apparatus conveys the exposure head 1 and the color photosensitive material 3 held at the position where the exposure light 2 emitted from the exposure head 1 is irradiated at a constant speed in the direction of arrow Y in FIG. For example, a sub-scanning means 4 composed of a nip roller or the like is provided.

  The exposure head 1 is arranged at a position where the organic EL panel 6 and the exposure light 2 emitted from the organic EL panel 6 are received, and an image formed by the exposure light 2 is formed on the color photosensitive material 3 at the same magnification. And a holding means 8 (not shown in FIG. 2) for holding the lens array 7 and the organic EL panel 6.

  As shown in detail in FIG. 3 which is a plan view of the gradient index lens array 7 which is an equal magnification lens array, a minute gradient index lens 7a for condensing the exposure light 2 is set in the sub-scanning direction Y. A total of two lens rows are arranged in parallel in the orthogonal main scanning direction (arrow X direction). In the gradient index lens array 7, the gradient index lenses 7a are arranged in a staggered manner. That is, the plurality of gradient index lenses 7a constituting one lens row are arranged so as to be positioned between the plurality of gradient index lenses 7a constituting the other lens row. Specifically, as such a gradient index lens array 7, a SELFOC lens (registered trademark) array SLA-12E manufactured by Nippon Sheet Glass Co., Ltd. can be suitably used.

  The exposure apparatus of this embodiment exposes a color image to the color photosensitive material 3 which is a full-color negative type silver salt photographic photosensitive material as an example, and the organic EL panel 6 constituting the exposure head 1 is arranged in the sub-scanning direction Y. A red line light emitting element array 6R, a green line light emitting element array 6G, and a blue line light emitting element array 6B arranged side by side are provided. Each of the line-shaped light emitting element arrays 6R, 6G, and 6B includes a large number of red organic EL light emitting elements, green organic EL light emitting elements, and blue organic EL light emitting elements arranged in parallel in the main scanning direction X.

  In FIG. 1 and FIG. 2, one of the light emitting elements is typically shown as an organic EL light emitting element 20. Each organic EL light emitting element 20 is formed by sequentially laminating a transparent anode 21, an organic compound layer 22 including a light emitting layer, and a metal cathode 23 on a transparent substrate 10 made of glass or the like. Then, red light emitting elements, green light emitting elements, and blue light emitting elements are respectively applied as the light emitting layers, thereby forming red organic EL light emitting elements, green organic EL light emitting elements, and blue organic EL light emitting elements, respectively.

  The line-shaped light emitting element arrays 6R, 6G, and 6B are driven by the drive circuit 30 shown in FIG. In other words, the drive circuit 30 sets the cathode cathode which is the scanning electrode to be sequentially turned on in a predetermined cycle and the transparent anode 21 which is the signal electrode to be turned on based on the image data D indicating a full color image. The line-shaped light emitting element arrays 6R, 6G and 6B are driven by a so-called passive matrix line sequential selection driving method. The operation of the drive circuit 30 is controlled by a control unit 31 that outputs the image data D.

  Elements constituting each organic EL light emitting element 20 are disposed in a sealing member 25 made of, for example, a glass can. That is, the edge of the sealing member 25 and the transparent substrate 10 are bonded, and the organic EL light emitting element 20 is sealed in the sealing member 25 filled with dry nitrogen gas.

  In the organic EL light emitting device 20 having the above configuration, when a predetermined voltage is applied between the metal cathode 23 and the transparent anode 21 extending across the metal cathode 23, an organic compound is formed at each intersection of the electrodes to which the voltage is applied. A current flows through the layer 22, and the light emitting layer contained therein emits light. The emitted light passes through the transparent anode 21 and the transparent substrate 10 and is emitted as exposure light 2 to the outside of the device.

  Here, the transparent anode 21 preferably has a light transmittance of at least 50% or more, preferably 70% or more in the visible light wavelength region of 400 nm to 700 nm. As the material of the transparent anode 21, conventionally known compounds such as tin oxide, indium tin oxide (ITO), and zinc indium oxide can be used as appropriate, but other metals having a high work function such as gold and platinum. You may use the thin film which consists of. In addition, organic compounds such as polyaniline, polythiophene, polypyrrole, or derivatives thereof can also be used. Supervised by Yutaka Sawada, “New Development of Transparent Conductive Film”, published by CMC Co., Ltd. (1999), there is a detailed description of the transparent conductive film, and what is shown there can be applied to the present invention It is. The transparent anode 21 can be formed on the transparent substrate 10 by a vacuum deposition method, a sputtering method, an ion plating method, or the like.

  On the other hand, the organic compound layer 22 may have a single-layer structure composed of only a light emitting layer, or other layers such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer in addition to the light emitting layer. A stacked structure may be used as appropriate. Specific layer structures of the organic compound layer 22 and the electrode include an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode structure, and an anode / light emitting layer / electron transport layer / cathode, anode. / Hole transport layer / light-emitting layer / electron transport layer / cathode and the like. A plurality of light emitting layers, hole transport layers, hole injection layers, and electron injection layers may be provided.

  The metal cathode 23 is formed of a metal material such as an alkali metal such as Li or K having a low work function, an alkaline earth metal such as Mg or Ca, and an alloy or a mixture of these metals with Ag or Al. Is preferred. In order to achieve both storage stability and electron injectability at the cathode, the electrode formed of the above material may be further coated with Ag, Al, Au, or the like having a high work function and high conductivity. Note that, similarly to the transparent anode 21, the metal cathode 23 can also be formed by a known method such as a vacuum deposition method, a sputtering method, or an ion plating method.

  The operation of the exposure apparatus having the above configuration will be described below. Here, the number of pixels in the main scanning direction of the line-shaped light emitting element arrays 6R, 6G, and 6B, that is, the number of the transparent anodes 21 arranged in parallel is assumed to be n. When the color photosensitive material 3 is subjected to image exposure, the color photosensitive material 3 is conveyed by the sub-scanning means 4 at a constant speed in the arrow Y direction. In synchronism with the conveyance of the color photosensitive material 3, one of the three metal cathodes 23 is sequentially turned on by the cathode driver of the drive circuit 30 described above.

  In this manner, the anode driver of the drive circuit 30 is in the first, second, third,... Within the period when the first metal cathode 23, that is, the metal cathode 23 constituting the red line light emitting element array 6R is selected. The n transparent anodes 21 are connected to a constant current source for a time corresponding to the image data indicating the red density of the first, second, third,..., Nth pixels of the first main scanning line. Thereby, a current having a pulse width corresponding to the image data flows through the organic compound layer 22 (see FIG. 1) between the transparent anode 21 and the metal cathode 23, and red light is emitted from the organic compound layer 22.

  Thus, the exposure light 2 which is red light emitted from the red line-shaped light emitting element array 6R is condensed on the color photosensitive material 3 by the lens array 7, and thereby the first main scanning line is formed on the color photosensitive material 3. The first, second, third,..., N-th pixels that are configured are exposed to red light, and are colored red.

  When the passive matrix line sequential selection driving method is applied as in the present embodiment, the conveyance speed (sub-scanning speed) of the color photosensitive material 3 by the sub-scanning means 4 and the light emission time of the organic EL light-emitting element 20 are substantially equal. The color photosensitive material 3 is set so as to be in the same state as the exposure light 2 is irradiated with the color photosensitive material 3 stopped.

  Next, within the period when the second metal cathode 23, that is, the metal cathode 23 constituting the green line-shaped light emitting element array 6G is selected, the anode driver of the drive circuit 30 is the first, second, third,. Are connected to a constant current source for a time corresponding to image data indicating the green density of the first, second, third,..., Nth pixels of the first main scanning line. As a result, a current having a pulse width corresponding to the image data flows through the organic compound layer 22 between the transparent anode 21 and the metal cathode 23, and green light is emitted from the organic compound layer 22.

  Thus, the exposure light 2 which is green light emitted from the green line-shaped light emitting element array 6G is condensed on the color photosensitive material 3 by the lens array 7, and thereby the first main scanning line is formed on the color photosensitive material 3. The first, second, third,..., Nth pixels constituting the layer are exposed to green light, and develop a green color. Since the color photosensitive material 3 is conveyed at a constant speed as described above, the green light is irradiated onto a portion of the color photosensitive material 3 that has already been exposed to red light.

  Next, within the period when the third metal cathode 23, that is, the metal cathode 23 constituting the blue line-shaped light emitting element array 6B is selected, the anode driver of the drive circuit 30 is the first, second, third. The transparent anodes 21 are connected to a constant current source for a time corresponding to image data indicating the blue density of the first, second, third,..., Nth pixels of the first main scanning line. As a result, a current having a pulse width corresponding to the image data flows through the organic compound layer 22 between the transparent anode 21 and the metal cathode 23, and blue light is emitted from the organic compound layer 22.

  Thus, the exposure light 2 which is blue light emitted from the blue line-shaped light emitting element array 6B is condensed on the color photosensitive material 3 by the lens array 7, and thereby the first main scanning line is formed on the color photosensitive material 3. The first, second, third,..., N-th pixels that are configured are exposed to blue light and develop blue. Since the color photosensitive material 3 is conveyed at a constant speed as described above, the blue light is irradiated onto the portion of the color photosensitive material 3 that has already been exposed to red light and green light. Through the above steps, the first full-color main scanning line is exposed and recorded on the color photosensitive material 3.

  Next, the line sequential selection of the metal cathodes returns to the first metal cathode 23, and within the period when the first metal cathode 23, that is, the metal cathode 23 constituting the red line light emitting element array 6R is selected. The anode driver of the drive circuit 30 displays the red density of the first, second, third... N transparent pixels 21 and the red density of the first, second, third. Connect to a constant current source for a time corresponding to. As a result, a current having a pulse width corresponding to the image data flows through the organic compound layer 22 between the transparent anode 21 and the metal cathode 23, and red light is emitted from the organic compound layer 22.

  Thus, the exposure light 2 which is red light emitted from the red line-shaped light emitting element array 6R is condensed on the color photosensitive material 3 by the lens array 7, and thereby the second main scanning line is formed on the color photosensitive material 3. The first, second, third,..., N-th pixels that are configured are exposed to red light, and are colored red.

  In the following, the same operation is repeated to expose the second full-color main scanning line. Further, such color main scanning lines are successively exposed in the sub-scanning direction Y, and a large number of color main scanning lines 3 are exposed on the color photosensitive material 3. A two-dimensional color image consisting of main scanning lines is exposed. In the present embodiment, as described above, each color exposure light is subjected to pulse width modulation, and the amount of emitted light is controlled corresponding to the image data, whereby a color gradation image is exposed.

  In the present embodiment, the red line light emitting element array 6R, the green line light emitting element array 6G, and the blue line light emitting element array 6B are arranged one by one in the sub-scanning direction. The parallel arrangement number and the arrangement order are not limited to those in the present embodiment, and can be set as appropriate.

  Next, a configuration for suppressing the above-described variation in print density of the photosensitive material will be described in detail. In this embodiment, the target resolution on the color photosensitive material 3 is 254 dpi (dots per inch) in both the main scanning direction and the sub-scanning direction, and the maximum pixel size on the color photosensitive material 3 for realizing this is In the case of a square pixel, it is 100 μm × 100 μm. On the other hand, the size of the organic EL light emitting elements 20 constituting the red line light emitting element array 6R, the green line light emitting element array 6G, and the blue line light emitting element array 6B is set to 100 μm × 70 μm. Further, the arrangement pitch of the organic EL light emitting elements 20 in the main scanning direction is 100 μm, and the arrangement pitch in the sub scanning direction of the red line light emitting element array 6R, the green line light emitting element array 6G and the blue line light emitting element array 6B is 130 μm. .

  In the present embodiment, as described above, since the equal magnification imaging lens array is used as the gradient index lens array 7, the size of the image of the organic EL light emitting element 20 on the color photosensitive material 3 is the refractive index. If the color photosensitive material 3 is correctly arranged at the focal position of the distributed lens array 7, the element size is 100 μm × 70 μm as it is. FIG. 4 shows the arrangement of the organic EL light emitting element image 20P on the color photosensitive material 3 together with the maximum pixel size. In the figure, the vertical size of the image 20P of the organic EL light-emitting element (that is, the size of the organic EL light-emitting element 20), that is, the sub-scanning direction size is a, the horizontal size is b, and the main scanning direction arrangement pitch is c.

In the present embodiment, the magnification C of the gradient index lens array 7 is 1, and the maximum pixel area A is 100 μm × 100 μm = 10000 μm ^2. On the other hand, the organic EL at the focal position of the gradient index lens array 7 is used. The image area B of the light emitting element 20 is 100 μm × 70 μm = 7000 μm ² , and therefore B × C ² /A=0.7.

  For the exposure apparatus of the present embodiment having the above-described configuration, the print density fluctuation was evaluated by the method described above. That is, when the color photosensitive material 3 is present at the focal position of the gradient index lens array 7, the relationship between the exposure amount and the print density when moving 200 μm from the focal position and when moving 400 μm from the focal position. Asked. The relationship is shown in FIG. 5. As shown here, in this embodiment, the print density difference is less than 0.05 in all the gradation regions in any case. Accordingly, in this exposure apparatus, even if the color photosensitive material 3 moves to some extent in the direction in which the distance from the exposure head 1 changes as the sub-scan feeds, the print density difference is 0.05 with respect to the same exposure amount. It was confirmed that the density fluctuation of the photosensitive material could be suppressed.

  In addition, the evaluation result of this embodiment is shown by the center column of the lowest row of Table 1 mentioned above, and evaluation is (circle) naturally.

As a comparative example for the present invention, an exposure apparatus in which the size of the organic EL light emitting element 20 was set to 70 μm × 70 μm and other points were set in the same manner as in the above-described embodiment was produced, and the same evaluation was performed. In this example, B × C ² /A=0.49. FIG. 6 shows the arrangement of the images 20P of the organic EL light emitting elements in this case. FIG. 7 shows the results of obtaining the relationship between the exposure amount and the print density in this case for the same three cases as in the above embodiment. As shown in FIG. 7, in this comparative example, the relationship between the exposure amount and the print density changes greatly, and there is a gradation region where the print density difference exceeds approximately 0.06. Therefore, the color photosensitive material 3 is sub-scanned. It is considered that if the movement to some extent in the direction in which the distance from the exposure head 1 is changed along with the feeding, the density fluctuation cannot be suppressed for the same exposure amount, and density unevenness exceeding the visual recognition limit occurs.

  The evaluation result of this comparative example is shown in the center column of the third row from the top of Table 1 described above, and the evaluation is x.

Table 1 also shows evaluation results in the case where the size of the organic EL light emitting element 20 is variously changed in addition to the embodiment and the comparative example. Tables 2, 3 and 4 show the evaluation results when the size of the organic EL light emitting element 20 is variously changed when the target resolution is 300 dpi, 400 dpi and 508 dpi in both the main scanning direction and the sub-scanning direction. It is shown. Further, Tables 5 to 7 show the evaluation results when the magnification C of the gradient index lens array 7 is 0.9, 1.1, and 1.2, respectively, and the other points are the same as those in Table 1. It is shown. As shown in Tables 1 to 7, if the relationship of 0.6 ≦ B × C ² / A is satisfied, the print density can be stabilized even if the distance between the color photosensitive material 3 and the exposure head 1 varies. It is clear that

  As described above, the exposure head generates three colors of light of red light, green light, and blue light, and the light exposure layer exposes the red color developing layer, the green color developing layer, and the blue color developing layer of the color photosensitive material 3, respectively. Although the applied embodiment has been described, the present invention is also applicable to an exposure apparatus that targets a color photosensitive material having a color-developing layer that emits other colors, and an exposure apparatus that exposes a monochrome image. In this case, the same effect can be obtained.

  In the case of a color photosensitive material, the photosensitive material is not limited to the above-described full-color negative type silver salt photographic photosensitive material, and the exposure apparatus of the present invention exposes an image to other color photosensitive materials. It is also possible to form as. However, since silver salt photographic light-sensitive materials such as silver halide light-sensitive materials have high sensitivity to the exposure amount, the effects of the present invention are particularly high when they are used.

  The driving method of the light emitting element array is not limited to the passive matrix driving method described above, and other driving methods such as an active matrix driving method can be applied as appropriate. On the other hand, the modulation method of exposure light for density gradation expression is not limited to the above-described pulse width modulation, and other modulation methods such as light emission intensity modulation and pulse number modulation can be applied singly or in combination as appropriate.

  Furthermore, although the said embodiment uses an organic electroluminescent light emitting element as a light emitting element which comprises a linear light emitting element array, this invention changes a line light emitting element from other light emitting elements, such as a light emitting diode and an inorganic EL light emitting element, for example. The present invention can also be applied to the case of configuring an array, and is not limited to a self-luminous light emitting element such as an organic EL light emitting element, or an element composed of a combination of a light control element such as liquid crystal or PLZT and a light source, or a plurality The present invention can also be applied to a case where a line-shaped light emitting element array is configured by using a light emitting element in which the light sources and elements are combined. In this case, the same effect can be obtained.

  Further, when the color photosensitive material is exposed by the light emitted from the light emitting element array as in the above-described embodiment, the spectral sensitivity characteristics of the color photosensitive material are more suitable between each light emitting element array and the color photosensitive material. A color selection filter for selecting the wavelength of the exposure light may be provided.

1 is a partially cutaway front view of an exposure apparatus according to an embodiment of the present invention. Partially broken side view of the above exposure apparatus Partial plan view showing a line-shaped light-emitting element array and an equal magnification lens array in the exposure apparatus Schematic showing the arrangement state of light emitting element images in the exposure apparatus Graph showing the relationship between exposure amount and print density in the exposure apparatus Schematic which shows the arrangement state of the light emitting element image in the exposure apparatus of the comparative example with respect to this invention Graph showing the relationship between exposure amount and print density in the exposure apparatus of the comparative example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure head 2 Exposure light 3 Color photosensitive material 4 Subscanning means 6 Organic EL panel 6R Red line light emitting element array 6G Green line light emitting element array 6B Blue line light emitting element array 7 Refractive index distribution type lens array 7a Refractive index distribution Type lens
20 Organic EL light emitting device
Image of 20P organic EL light emitting device
30 Drive circuit
31 Control unit

Claims (3)

In an exposure head comprising a light emitting element array composed of a plurality of light emitting elements arranged in parallel in at least one direction at an interval, and an imaging lens for forming an image by these light emitting elements on a photosensitive material,
When the maximum pixel area, the light emitting area of the light emitting element, and the magnification of the imaging lens in the photosensitive material arranged at the focal position of the imaging lens are A, B, and C, respectively, 0.6 ≦ B × C ² / A An exposure head characterized by that.   The exposure head according to claim 1, wherein the imaging lens is an equal magnification lens. An exposure head according to any one of claims 1 to 2,
An exposure apparatus comprising sub-scanning means for relatively moving the exposure head and the photosensitive material in a direction substantially perpendicular to the one direction.

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