JP2006015641A - Exposure head and exposure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a color exposure head in which variation in the quantity of exposure light passed through a unit magnification lens array does not cause a significant unevenness of density. <P>SOLUTION: The exposure head comprises a plurality of linear light emitting element arrays 6R, 6G and 6B emitting light of different colors juxtaposed in the direction substantially perpendicularly to the arranging direction of light emitting elements constituting each array, and one unit magnification lens array 7 arranged, in zigzag, with a plurality of lenses 7a for condensing light emitted from the linear light emitting element arrays 6R, 6G and 6B substantially in parallel with the arranging direction of the light emitting elements and condensing each color light onto a color photosensitive material. Out of the plurality of linear light emitting element arrays 6R, 6G and 6B, the linear light emitting element array 6G emitting light for sensitizing a coloring layer of highest relative luminous efficiency of the color photosensitive material is arranged closest to the long axis L of the unit magnification lens array 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure head using a plurality of types of line-shaped light emitting element arrays that emit light of different colors.

  The present invention also relates to an exposure apparatus that exposes a color photosensitive material using the exposure head as described above.

  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 that emit light of the same color arranged in a line. The exposure head includes a plurality of line-shaped light emitting element arrays that emit light of different colors arranged in a direction substantially perpendicular to the direction of arrangement of the light emitting elements, and the light emitted from each array is a color photosensitive material. An equal-magnification lens array for condensing light is provided on the top.

The 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 color photosensitive material and the exposure head are combined with a plurality of line-shaped light emitting element arrays. Sub-scanning means for relatively moving in the arrangement direction is further provided.
JP-A-5-92622 JP 2000-13571 A

  In the above-described equal-magnification lens array, a plurality of gradient index lenses that collect light emitted from the line-shaped light-emitting element array are substantially parallel to the longitudinal direction of the line-shaped light-emitting element array (the arrangement direction of the light-emitting elements). In many cases, the lens arrays are arranged in a line, but this type of lens array is quite expensive. The exposure head shown in Patent Document 1 has a high cost because such a total magnification lens array of three is provided for each of the three color line-shaped light emitting element arrays. In addition, when the same-size lens arrays are provided as many as the plurality of line-shaped light-emitting element arrays in this way, the width of the exposure head is increased because of the plurality of equal-size lens arrays that are usually wider than the line-shaped light-emitting element arrays. This becomes an obstacle to downsizing the exposure apparatus.

  On the other hand, Patent Document 2 discloses an exposure head in which light emitted from each of a plurality of line-shaped light emitting element arrays is combined by a dichroic mirror so as to enter a common one-magnification lens array. ing. However, although such an exposure head requires only one equal-magnification lens array, many other optical components are required, so there is still room for improvement in terms of cost and miniaturization.

  Therefore, it is also conceivable to directly combine one single-magnification lens array common to the three-color line-shaped light-emitting element array without performing the above-described multiplexing. However, in that case, there arises a problem that the amount of exposure light that has passed through the equal-magnification lens array varies greatly along the longitudinal direction of the lens array. Hereinafter, this point will be described in detail.

  The above-mentioned equal-magnification lens array is usually formed by arranging a plurality of lens rows in which a plurality of lenses such as a gradient index lens are arranged in parallel in one direction and in a direction perpendicular to the lens arrangement direction. The adjacent lens rows are arranged in a state where the lenses of another lens row enter the space between the lenses of one lens row. That is, as a whole, the lenses are in a staggered arrangement. When the light emitted from the line-shaped light emitting element array is passed through such an equal-magnification lens array, the amount of exposure light that has passed through the major axis of the equal-magnification lens array (the central position of the lens array in the lens arrangement direction The lens arrangement pitch varies along the axis).

  With respect to the line-shaped light emitting element array arranged in alignment with the long axis of the 1 × lens array, that is, in a state where the optical axis of each light emitting element intersects with the long axis, The variation in the exposure amount is not so serious because the variation in the amount of light is canceled out by the lens in which the lens is located. However, the effect of such cancellation is greater in the line-shaped light emitting element array arranged farther away from the long axis. Therefore, the fluctuation of the exposure amount becomes serious. If the exposure amount varies in this manner, naturally density unevenness occurs in the image exposed to the color photosensitive material. As described above, in an exposure apparatus that performs sub-scanning by relatively moving the color photosensitive material and the exposure head in the arrangement direction of the plurality of line-shaped light emitting element arrays, if such density unevenness exists, the sub-scanning is thereby performed. Streaks extending in the direction occur, and the quality of the exposure image is greatly impaired.

  In the above, the problem in the exposure head using the array of organic EL light emitting elements has been described. However, a combination of a self-luminous light emitting element other than the organic EL light emitting element or a light control element such as liquid crystal or PLZT and a light source. Of course, the same problem may occur in an exposure head using an array of elements. In the present specification, an element composed of a combination of the above light control element and a light source is also referred to as a “light emitting element” in the sense of an element that emits exposure light.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a color exposure head and an exposure apparatus that do not generate large density unevenness due to fluctuations in the amount of exposure light that has passed through the equal-magnification lens array.

The exposure head according to the present invention makes it difficult to visually recognize density unevenness caused by fluctuations in the amount of exposure light by setting the arrangement state of the plurality of line-shaped light emitting element arrays to a special state. Is
As described above, a plurality of line-shaped light-emitting element arrays that emit light of different colors, in which the light-emitting elements are arranged in a row, and are arranged in a direction substantially perpendicular to the arrangement direction of the light-emitting elements. When,
A plurality of lenses for condensing light emitted from these line-shaped light emitting element arrays are assembled in a staggered arrangement so as to be arranged substantially in parallel with the arrangement direction of the light emitting elements, and the light of each color is converted into the color light. In an exposure head having one equal-magnification lens array that focuses light on a photosensitive material,
Among the plurality of line-shaped light-emitting element arrays, the line-shaped light-emitting element array that emits light for sensitizing the color-developing layer having the highest relative visibility of the color photosensitive material is in a state closest to the long axis of the equal-magnification lens array. It is characterized by being arranged.

In the exposure head of the present invention having the above configuration,
Among the plurality of line-shaped light-emitting element arrays, the line-shaped light-emitting element array that emits light that sensitizes the second colorimetric layer having the highest relative visibility is the light that sensitizes the colorimetric layer that has the highest relative visibility. It is arranged next to the line-shaped light emitting element array that emits,
When viewed from a direction parallel to the optical axis of the lens, the two adjacent line-shaped light emitting element arrays are arranged by placing the long axis of the equal-magnification lens array between the two line-shaped light emitting element arrays. It is desirable that

In the exposure head of the present invention,
When the highest specific visibility and the second highest specific visibility are k ₁ and k ₂ respectively,
A line-shaped light emitting element array that emits light that exposes the coloring layer having the highest relative visibility when viewed from a direction parallel to the optical axis of the lens, and light that exposes the coloring layer having the second highest visibility. It is desirable that the ratio of the sorting distance from the long axis of the equal-magnification lens array of the line-shaped light emitting element array emitting light is approximately (1 / k ₁ ) :( 1 / k ₂ ).

In the exposure head of the present invention,
A plurality of line-shaped light emitting element arrays emitting light of different colors emit light in the red, green and blue wavelength regions,
It is desirable that the line-shaped light emitting element array that emits light in the green wavelength region is arranged in a state closest to the long axis of the equal-magnification lens array among the three line-shaped light emitting element arrays.

  Further, in the exposure head of the present invention, as the plurality of line-shaped light emitting element arrays that emit light of different colors, those composed of organic EL light emitting elements can be suitably used.

On the other hand, an exposure apparatus according to the present invention comprises:
An exposure head according to the invention as described above;
Sub-scanning means for holding a color photosensitive material at a position to which light emitted from the exposure head is irradiated, and relatively moving the color photosensitive material and the exposure head in the direction in which the plurality of line-shaped light emitting element arrays are arranged; It is characterized by comprising.

  A color light-sensitive material is provided with a plurality of color developing layers. The higher the relative visibility among these color developing layers, the more conspicuous the density unevenness caused by the fluctuation in the amount of exposure light. In addition, due to the effect of canceling the light amount fluctuation of the equal magnification lens array described above, the light amount fluctuation is smaller as the light emitted from the linear light emitting element array arranged near the major axis of the equal magnification lens array and reaches the color photosensitive material. As the light emitted from the line-shaped light emitting element array arranged far from the long axis reaches the color photosensitive material, the light amount fluctuation increases.

  In the exposure head of the present invention, paying attention to the above points, a line-shaped light emitting element array that emits light for sensitizing a color-developing layer (that is, a color-developing layer where density unevenness is most conspicuous) of a color photosensitive material. Is arranged in the state closest to the long axis of the 1 × lens array, it is possible to suppress the variation in exposure amount and to suppress the occurrence of density unevenness in the color developing layer. Since the other line-shaped light emitting element arrays are arranged farther from the major axis of the equal-magnification lens array, the light emitted from these line-shaped light emitting element arrays and reaching the color photosensitive material has a larger amount of light fluctuation. However, since the color-developing layer that is sensitive to these lights has a lower specific visibility, density unevenness due to exposure amount fluctuations in the color-developing layer is difficult to visually recognize.

  In particular, among the exposure heads of the present invention, as described above, among the plurality of line-shaped light-emitting element arrays, a line-shaped light-emitting element array that emits light that sensitizes the coloring layer having the second highest visual sensitivity among the color photosensitive materials. Is arranged next to a line-shaped light-emitting element array that emits light that sensitizes the color-developing layer having the highest relative visibility, and the two adjacent line-shaped light-emitting elements as viewed from a direction parallel to the optical axis of the lens. In the exposure head in which the element array is arranged with the major axis of the equal-magnification lens array in between, the density in the coloring layer having the second highest visual sensitivity (that is, the coloring layer having the second highest density unevenness). Occurrence of unevenness can be reduced.

Further, when the highest specific luminous sensitivity and the second highest specific luminous sensitivity are respectively k ₁ : k ₂ , the coloring layer having the highest specific luminous sensitivity when viewed from the direction parallel to the optical axis of the lens. The ratio of the sorting distance from the long axis of the 1 × lens array is approximately the same between the line-shaped light-emitting element array that emits light that sensitizes the light and the line-shaped light-emitting element array that emits light that sensitizes the coloring layer having the second highest visual sensitivity. In the exposure head of (1 / k ₁ ) :( 1 / k ₂ ), the degree of visibility of density unevenness in the coloring layer having the highest specific visibility and the second coloring layer having the second highest visual sensitivity is high. , They will be held to the same extent as each other.

  Further, since the exposure apparatus of the present invention uses the exposure head having the above-described effects, it is possible to expose a high-quality image in which the occurrence of density unevenness due to fluctuations in the amount of exposure light is suppressed.

  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 the first 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.

  The exposure apparatus of this embodiment exposes a color image to the color photosensitive material 3 which is a full color positive 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 arranged in a sealing member 25 made of, for example, a stainless steel 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.

  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.

  Next, a configuration for preventing the occurrence of density unevenness due to the above-described fluctuation in the amount of exposure light will be described in detail. In the present embodiment, the diameter of each gradient index lens 7a of the gradient index lens array 7 is 295 μm. As shown in FIG. 3, the green line-shaped light emitting element array 6G is directly above the major axis L of the gradient index lens array 7 (the axis extending from the center position of the two lens rows in the direction in which the lenses 7a are arranged). The red line light emitting element array 6R and the blue line light emitting element array 6B are arranged at intervals of 100 μm in the sub scanning direction Y.

  In general, the human relative luminous sensitivity for the three primary colors R, G, and B is 610 nm, 560 nm, and 470 nm as shown in the standard relative luminous sensitivity characteristics of CIE (International Commission on Illumination). Then, it is about 3: 6: 1. FIG. 4 shows the CIE standard relative luminous sensitivity characteristics. In the figure, the density unevenness generated in the full-color image formed on the color photosensitive material 3 is a stripe unevenness extending in the sub-scanning direction because the color photosensitive material 3 is sub-scanning moved in this example. appear. The visibility of the stripe unevenness is proportional to the specific visual sensitivity. Specifically, the B color is difficult to be visually recognized even if there is a slight density difference, but the G color is easily visually recognized as unevenness even with a small density difference. In other words, the ratio of the permissible values of the light quantity deviations of the R, G, and B colors is the ratio of the reciprocal of the relative luminous sensitivity. If the permissible value of the light quantity deviation of the G color is 1, R: G: B = 2: 1. : 6. Therefore, when the G light amount deviation is within the allowable value, the R and B color light amount deviations are allowed to be twice and six times the G light amount deviation, respectively.

  Here, as described above, when the exposure light 2 emitted from the line-shaped light emitting element arrays 6R, 6G, and 6B is passed through the refractive index distribution type lens array 7, the light quantity of the passed exposure light 2 is changed to the refractive index distribution. Along the long axis L of the mold lens array 7, the arrangement pitch of the lenses 7 a varies as a cycle. Such light quantity fluctuations cause the above-described density unevenness. The period deviation of the exposure light 2 changes according to the distance from the long axis L of the line-shaped light emitting element array 6R, 6G, or 6B, as shown in the curve of the actual measurement result in FIG. The distance is a distance when viewed from a direction parallel to the optical axis of the lens 7a (hereinafter the same), and is referred to as an “optical axis offset”.

  With respect to the direction of the optical axis offset, if the downward direction from the major axis L is defined as + and the upward direction is defined as − in FIG. 3, the optical axis offsets of the line-shaped light emitting element arrays 6R, 6G and 6B are as shown in FIG. Become. That is, as apparent from the above description, the optical axis offset of the green line light emitting element array 6G is 0 (zero), and the optical axis offsets of the red line light emitting element array 6R and the blue line light emitting element array 6B are respectively −100 μm and +100 μm. When the optical axis offset is such a value, the light amount period deviations of the R, G, and B color exposure lights 2 are R = 0.94%, G = 0.52%, and B = 0.94%. A value of 0.52% of the light amount period deviation of the G-color exposure light 2 is a preferable value as it does not normally cause density unevenness to be visually recognized. Further, when the ratio of these light quantity period deviations is obtained, R: G: B = 1.8: 1: 1.8, and the light quantity period deviation of the exposure light 2 of R color and B color is the G light quantity deviation. The above-mentioned conditions of 2 times and 6 times are satisfied.

  As described above, in the present embodiment, the green line-shaped light emitting element array 6G that emits the exposure light 2 that generates the G color that is most conspicuous in density unevenness is positioned at the optical axis offset = 0 where the light amount period deviation is minimum, that is, By arranging it at a position aligned with the long axis L of the gradient index lens array 7, the visibility of the density unevenness of the G color is minimized, while the line-shaped light emitting element arrays 6R and 6B are placed at the above positions. By arranging it, the visibility of the density unevenness of the R color and the B color can be suppressed to a very low level.

  Next, an exposure apparatus according to the second embodiment of the present invention will be described. The exposure apparatus of the second embodiment differs from the exposure apparatus of the first embodiment in the relative positional relationship between the linear light emitting element arrays 6R, 6G, and 6B and the gradient index lens array 7, and the other The dots are basically formed in the same manner.

  FIG. 6 is a plan view showing the relative positional relationship between the linear light emitting element arrays 6R, 6G, and 6B and the gradient index lens array 7 in the exposure apparatus of the third embodiment. As shown here, in this embodiment, the order in which the line-shaped light-emitting element arrays 6R, 6G, and 6B are arranged is the same as that of the first embodiment, and the central green-line light-emitting element array 6G is the first embodiment. Similarly to the first embodiment, the arrangement of the three linear light emitting element arrays 6R, 6G, and 6B in the sub-scanning direction Y is arranged at a position aligned with the major axis L of the gradient index lens array 7. Unlike the form, it is 160 μm. The diameter of each gradient index lens 7a of the gradient index lens array 7 is 295 μm.

  FIG. 7 shows the light amount period deviation characteristic of the exposure light 2 similar to that shown in FIG. 5 together with the optical axis offsets of the line-shaped light emitting element arrays 6R, 6G, and 6B in the present embodiment. When the optical axis offset is the value of this embodiment, the light amount period deviations of the R, G, and B color exposure lights 2 are R = 1.87%, G = 0.52%, and B = 1.87%. . Here again, the light amount period deviation of the G-color exposure light 2 is suppressed to 0.52%, which is preferable from the viewpoint that density unevenness is not normally visible. As described above, also in the present embodiment, the green line-shaped light emitting element array 6G that emits the exposure light 2 that generates the G color that is most conspicuous in density unevenness is arranged at a position aligned with the long axis L of the gradient index lens array 7. As a result, the visibility of the density unevenness of the G color is kept very low.

  However, when the ratio of the light quantity period deviations of the R, G, and B color exposure lights 2 is obtained, R: G: B = 3.6: 1: 3.6, and for the B color, 6 times the G light quantity deviation. The above-mentioned condition is satisfied, but the condition of up to twice the light amount deviation of the G color is not satisfied for the R color. This problem can be solved by a third embodiment described below.

  Hereinafter, an exposure apparatus according to the third embodiment of the present invention having such a configuration will be described. The exposure apparatus of the third embodiment is different from the exposure apparatus of the second embodiment in the relative positional relationship between the linear light emitting element arrays 6R, 6G and 6B and the gradient index lens array 7, and other points. Is basically formed in the same manner.

  FIG. 8 is a plan view showing the relative positional relationship between the line-shaped light emitting element arrays 6R, 6G and 6B and the gradient index lens array 7 in the exposure apparatus of the third embodiment. As shown here, in the present embodiment, the order in which the line-shaped light-emitting element arrays 6R, 6G, and 6B are arranged is the same as in the second embodiment, and the sub-scanning direction of the three line-shaped light-emitting element arrays 6R, 6G, and 6B. Similarly, the arrangement interval of Y is 160 μm, but the central green line-shaped light emitting element array 6G is not located directly above the long axis L of the gradient index lens array 7, but is arranged at a position of +60 μm therefrom. The diameter of each gradient index lens 7a of the gradient index lens array 7 is 295 μm.

  FIG. 9 shows the periodic deviation characteristics of the exposure light 2 similar to that shown in FIG. 5 together with the optical axis offsets of the line-shaped light emitting element arrays 6R, 6G, and 6B in the present embodiment. When the optical axis offset is the value of this embodiment, the light amount period deviations of the R, G, and B color exposure lights 2 are R = 0.94%, G = 0.68%, and B = 3.20%. . When these ratios are obtained, R: G: B = 1.4: 1: 4.7, and the light amount period deviation of the R color and B color exposure light 2 is 2 times and 6 times the light amount deviation of G color, respectively. It satisfies the above-mentioned conditions.

  As described above, in the present embodiment, the green line-shaped light emitting element array 6G that emits the exposure light 2 that generates the G color that is most conspicuous in density unevenness is positioned closest to the long axis L of the gradient index lens array 7, that is, A red line-shaped light emitting element array 6R that emits exposure light 2 that emits an R color that is second most prominent in density unevenness is disposed at a position separated by 60 μm, and is 100 μm from the long axis L of the gradient index lens array 7. By disposing at a distant position, the visibility of the density unevenness of the G color and the R color is both kept low. On the other hand, by arranging the blue line-shaped light emitting element array 6B at the above position, the density unevenness of the B color is reduced. Visibility is also kept low.

  In each of the embodiments described above, the relationship between the optical axis offset of the linear light emitting element arrays 6R, 6G, and 6B with respect to the long axis L of the gradient index lens array 7 and the light amount period deviation of the exposure light 2 is known in advance. It is assumed that However, when the characteristics of the same-magnification lens array used and the intervals between multiple line-shaped light-emitting element arrays differ for each model of exposure apparatus, the relationship between the optical axis offset and the light amount period deviation is measured for each model. Doing so is laborious and unrealistic.

  Therefore, it is assumed that the increase in the light amount deviation is linear in the range from the major axis L of the gradient index lens array 7 to the same distance as the diameter of the lens 7a, and the green line light emitting element array 6G from the major axis L is assumed. In addition, by setting each distance to the red line-shaped light emitting element array 6R to a value that is inversely proportional to the relative visibility of the G color and the R color, density unevenness of both the G color and the R color can be reduced.

More specifically, when the specific luminous sensitivity of the G color is k ₁ and the specific luminous sensitivity of the R color is k ₂ , the ratio is k ₁ : k ₂ = 6: 3, and the reciprocal ratio thereof. Becomes 1: 2. Therefore, when the distance between the green line light emitting element array 6G and the red line light emitting element array 6R is 160 μm, the distance from the long axis L of the gradient index lens array 7 to the green line light emitting element array 6G is 53 μm. In addition, the distance from the long axis L to the red line-shaped light emitting element array 6R may be set to 107 μm. The density unevenness of the G color and the R color in this case is measured based on the relationship between the optical axis offset of the line-shaped light emitting element arrays 6R and 6G and the light amount deviation of the exposure light. It is only slightly different from the density unevenness when the optical axis offset of the light emitting element arrays 6R and 6G is determined.

  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 develops colors in other colors, and in that case also has the same effect It is.

  In each of the embodiments described above, the gradient index lens array 7 having a gradient index lens 7a diameter of 295 μm is used. However, the diameter of the equal magnification lens array is not limited to that value. Of course, the interval between the plurality of line-shaped light-emitting elements, the long axis of the line-shaped light-emitting element array that emits light that sensitizes the color-developing layer having the highest relative visibility of the color photosensitive material, and the same magnification lens array Is also not limited to the value in each embodiment described above.

  Moreover, 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 is a case where a linear light emitting element array is comprised from other light emitting elements, such as a light emitting diode, for example. Further, the present invention is not limited to a self-luminous light emitting element such as an organic EL light emitting element, and a linear light emitting element array using an element composed of a combination of a light control element such as liquid crystal or PLZT and a light source. The present invention can also be applied to the configuration of the above-described configuration, and the same effect can be achieved in that case.

  Further, the exposure apparatus of the above embodiment exposes an image to the color photosensitive material 3 that is a full-color positive type silver salt photographic photosensitive material, but the exposure apparatus of the present invention exposes an image to other color photosensitive materials. It is also possible to form as.

1 is a partially broken front view of an exposure apparatus according to a first 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 A graph showing the standard relative luminous sensitivity characteristics of the CIE (International Commission on Illumination) The graph which shows the relationship between the position of the linear light emitting element array in the said exposure apparatus, and an exposure amount deviation characteristic FIG. 7 is a partial plan view showing a line-shaped light emitting element array and an equal magnification lens array in an exposure apparatus according to a second embodiment of the present invention. The graph which shows the relationship between the position of the linear light emitting element array in the exposure apparatus by the said 2nd Embodiment, and an exposure amount deviation characteristic. FIG. 9 is a partial plan view showing a line-shaped light emitting element array and an equal magnification lens array in an exposure apparatus according to a third embodiment of the present invention. The graph which shows the relationship between the position of the linear light emitting element array in the exposure apparatus by the said 3rd Embodiment, and an exposure amount deviation characteristic.

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
21 Transparent anode
22 Organic compound layer
23 Metal cathode
30 Drive circuit
31 Control unit

Claims (6)

A plurality of line-shaped light emitting element arrays that emit light of different colors, in which light emitting elements are juxtaposed in a row, and are arranged in a direction substantially perpendicular to the direction in which the light emitting elements are arranged;
A plurality of lenses that collect the light emitted from these line-shaped light emitting element arrays are gathered in a staggered arrangement so as to be arranged in substantially parallel to the arrangement direction of the light emitting elements, and the light of each color is color-sensitized. In an exposure head having one lens array for condensing light on a material,
Among the plurality of line-shaped light-emitting element arrays, the line-shaped light-emitting element array that emits light for sensitizing the color-developing layer having the highest relative visibility of the color photosensitive material is in a state closest to the long axis of the equal-magnification lens array. An exposure head characterized by being arranged. Of the plurality of line-shaped light-emitting element arrays, the line-shaped light-emitting element array that emits light for sensitizing the color-sensitive material having the second highest relative visibility of the color photosensitive material is sensitive to the color-sensitive layer having the highest relative visibility. It is arranged next to the line-shaped light emitting element array that emits light,
When viewed from a direction parallel to the optical axis of the lens, the two adjacent linear light emitting element arrays are distributed with the long axis of the equal-magnification lens array placed between the two linear light emitting element arrays. 2. The exposure head according to claim 1, wherein the exposure head is arranged. When the highest specific visibility and the second highest specific visibility are k ₁ and k ₂ , respectively.
A line-shaped light emitting element array that emits light for sensitizing the coloring layer having the highest relative visibility in a state viewed from a direction parallel to the optical axis of the lens, and the second coloring layer having the highest relative visibility. The ratio of the distance of the line-shaped light emitting element array emitting the light to be emitted from the long axis of the equal-magnification lens array is approximately (1 / k ₁ ) :( 1 / k ₂ ). The exposure head described. The plurality of line-shaped light emitting element arrays that emit light of different colors emit light in the red, green, and blue wavelength regions, respectively.
The line-shaped light-emitting element array that emits light in the green wavelength region is arranged in a state closest to the major axis of the equal-magnification lens array among the three line-shaped light-emitting element arrays. The exposure head according to any one of 1 to 3.   5. The exposure head according to claim 1, wherein the plurality of line-shaped light emitting element arrays that emit light of different colors are composed of organic EL light emitting elements. An exposure head according to any one of claims 1 to 4,
Sub-scanning means for holding a color photosensitive material at a position where light emitted from the exposure head is irradiated, and relatively moving the color photosensitive material and the exposure head in the direction in which the plurality of line-shaped light emitting element arrays are arranged. An exposure apparatus comprising:

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