JP2006159455A - Optical writing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical writing device in which deterioration in image quality due to relative positional relation between a light emitting element and a rod lens is prevented. <P>SOLUTION: Difference like spots 5, 6 appears in the spreading profile of a light beam due to relative positional relation between a light emitting element 2 and a rod lens 4. A light emitting element arranged closely to an adjacent rod lens, as shown on Fig. (b), is reduced in size, as shown on Fig. (c) by number 11, in order to correct the spreading profile of a light beam. Profile of spot in this case is similar to the profile of spot 5 by the light emitting element 2 as shown on Fig. (d). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical writing device that prevents image streaks from occurring due to fluctuations in the imaging area.

  In an image forming apparatus that performs optical writing, a method of providing a scanning optical system as an exposure device and a method of using a light emitting element array are known. For example, Patent Document 1 describes an example using a light emitting element array in which light emitting elements are integrated on a single substrate. In this example, a connection type LED element is used as the light emitting element.

JP 11-138899 A

  When an optical system such as a light emitting element array is used, an equal-magnification optical system using a rod lens array having a rod lens is generally used as an imaging optical system for the line head. FIG. 6 is an explanatory diagram showing an example using such a line head (optical writing device). In FIG. 6A, the line head 30 uses a gradient index rod lens array (SLA). Reference numeral 2 denotes a light emitting element, 3 denotes a light emitting element line in which a plurality of light emitting elements 2 are arranged in the main scanning direction, and 4 denotes a rod lens.

  C. L is the center line of the SLA, and D is the diameter of the rod lens 4. As shown in FIG. 6B, the light emitted from the light emitting element 2 forms an image in the shape of spots 5 and 6 on an irradiated surface such as an image carrier through a rod lens 4. Here, the spot 5 has a normal shape with a diameter d, and the spot 6 has a shape with a diameter enlarged to d + a in the main scanning direction. The spot 5 corresponds to the irradiated surface by the light emitting element arranged at a position away from the adjacent rod lens, and the spot 6 corresponds to the irradiated surface by the light emitting element arranged at a position near the boundary of the adjacent rod lens. Corresponds. Thus, even if the light emitting element 2 is the same size, the relative positional relationship between the light emitting element 2 and the rod lens 4 in the main scanning direction, that is, the position of the rod lens through which the light emitted from the light emitting element 2 is transmitted. Thus, the spot shape in the main scanning direction is different.

  The reason why the shapes of the spots 5 and 6 are different depending on the relative positional relationship between the light emitting element 2 and the rod lens 4 as shown in FIG. 6 will be described with reference to the characteristic diagram of FIG. In FIG. 7A, the horizontal axis indicates the distance x, and the vertical axis indicates the width s of the spot in the main scanning direction. D is the diameter of the rod lens 4 as described in FIG. 6 and corresponds to the period of the characteristic G.

  As shown in FIG. 7B, the spot 5 has a diameter d in the valley portion of the characteristic G. Further, at the peak portion of the characteristic G, the diameter of the spot 6 is enlarged to d + a. That is, the spot shape (light beam spreading shape) varies with the pitch of the diameter of the rod lens 4. As described above, when the light spreading shape is different depending on the relative positional relationship between the light emitting element 2 and the rod lens 4, the imaging area is uneven and appears as an image streak, and the image quality deteriorates. was there. There is also a problem that the spot shape (light beam spreading shape) may differ depending on the radius pitch of the rod lens 4.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is that the imaging area is uneven due to the relative positional relationship between the light emitting element and the rod lens in the main scanning direction. An object of the present invention is to provide an optical writing device that prevents image quality from deteriorating.

  In order to achieve the above object, an optical writing apparatus of the present invention forms an image on a surface to be irradiated with a transparent substrate on which a plurality of light emitting elements are arranged in the main scanning direction and formed with light emitting element lines. An optical writing device including a lens array to be operated, wherein the size of the light emitting element is made different according to a relative position of the light emitting element in the main scanning direction with respect to the lens array. . According to this configuration, the relative positional relationship between the light emitting element and the rod lens in the main scanning direction suppresses the occurrence of a situation where the light spreading shape is different on the irradiated surface, resulting in uneven imaging area. It is possible to prevent image quality deterioration due to appearance as an image streak.

  The optical writing device of the present invention is characterized in that the size of the light emitting element is varied depending on the pitch of the diameters of the lenses arranged in the lens array. According to this configuration, as described with reference to FIG. 1, the spread of light rays by the light emitting elements arranged in the vicinity of adjacent lenses at a pitch of the diameter of the lens in the main scanning direction is suppressed, resulting in uneven imaging area. Image quality deterioration can be prevented.

  The optical writing device of the present invention is characterized in that the size of the light emitting element is made different at a 1/2 pitch of the diameter of the lenses arranged in the lens array. According to this configuration, as described with reference to FIG. 2, the spread of light rays by the light emitting elements arranged in the vicinity of adjacent lenses at a pitch of ½ of the diameter of the lens in the main scanning direction is suppressed, thereby forming an image. It is possible to prevent image quality deterioration due to the unevenness of the area.

  In the optical writing device of the present invention, the size of the light emitting element is smaller than that of a normal light emitting element. As described above, since the light emitting element smaller than the normal light emitting element is provided, when the light emitted from the light emitting element passes through the lens array at the position where the lenses are adjacent to each other, the connection of the irradiated surface is performed. The image area is reduced and formed to have the same size as the image formation area by the light emitting element having a normal size. Therefore, it is possible to prevent image quality deterioration due to unevenness of the imaging area.

  The optical writing device of the present invention is characterized in that the light emitting element lines are formed in one column in the sub-scanning direction. According to this configuration, as described with reference to FIGS. 1 and 2, the optical writing device in which the light emitting element lines are formed in one row in the sub-scanning direction and the lens array is formed in one or two rows in the sub-scanning direction. In this case, it is possible to prevent image quality deterioration caused by unevenness of the imaging area.

  The optical writing device of the present invention is characterized in that the light emitting element lines are formed in two rows in the sub-scanning direction. According to this configuration, in the optical writing apparatus in which the light emitting element lines are formed in two rows in the sub-scanning direction and the lens array is formed in two rows in the sub-scanning direction as described in FIG. The resulting image quality degradation can be prevented. As described in the modification of FIG. 3, the same effect can be obtained in the optical writing device in which the light emitting element lines are formed in two rows in the sub-scanning direction and the lens array is formed in one row in the sub-scanning direction. It is done.

  The optical writing device of the present invention is characterized in that the lens array is formed in one row in the sub-scanning direction. This configuration corresponds to the modified embodiment of FIGS. 1 and 3. When one lens array is formed in the sub-scanning direction, any optical writing device in which the light-emitting element lines are formed in one or two rows in the sub-scanning direction can degrade image quality due to uneven imaging area. Can be prevented.

  The optical writing device of the present invention is characterized in that the lens array is formed in two rows in the sub-scanning direction. This configuration corresponds to the embodiment of FIGS. When the lens array is formed in two rows in the sub-scanning direction, in any optical writing device in which the light emitting element lines are formed in one or two rows in the sub-scanning direction, image quality deterioration due to uneven imaging area is reduced. Can be prevented.

  The optical writing device of the present invention is characterized in that the light emitting element lines are formed in three or more columns in the sub-scanning direction. According to this configuration, there is an advantage that the optical writing device can be applied to various uses.

  In the optical writing device of the present invention, the light emitting element is an organic EL element. According to this configuration, since the organic EL element that can be manufactured with good linearity in the process is used as the light emitting element, there is an advantage that the light amount unevenness of the light emitting element itself is smaller than the transmitted light amount unevenness of the lens array.

  In the optical writing device of the present invention, the light emitting element has a double ring structure. According to this configuration, in an optical writing device using a light emitting element having a double ring structure, unevenness in the imaging area can be reduced and image quality can be improved. In this case, it can be arbitrarily selected whether the number of arrangements of the light emitting element lines and the lens arrays in the sub-scanning direction is one column or two columns. It is also possible to arrange three or more light emitting element lines in the sub-scanning direction.

  According to the optical writing device of the present invention, the size of the light emitting element is varied depending on the relative positional relationship between the light emitting element and the lens array in the main scanning direction. With such a configuration, occurrence of a situation in which the light spreading shape is different on the irradiated surface is suppressed, so that unevenness in the imaging area can be reduced to prevent image streaks and improve image quality.

  The present invention will be described below with reference to the drawings. FIG. 5 is a schematic perspective view showing the optical writing device 50 in an enlarged manner. In FIG. 5, details of the optical writing device 50 are shown. The organic EL element array 61 is held in a long housing 60. The positioning pins 69 provided at both ends of the long housing 60 are fitted into the opposing positioning holes of the case, and the fixing screws are screwed into the screw holes of the case through the screw insertion holes 68 provided at both ends of the long housing 60. By fixing, the optical writing device 50 is fixed at a predetermined position.

  In the optical writing device 50, the light emitting unit 63 of the organic EL element array 61 is placed on a glass substrate (transparent substrate) 62, and is driven by a TFT 71 formed on the same glass substrate 62. The light emitting part 63 is covered with a sealing member (not shown). A gradient index rod lens array (SLA) 65 constitutes an imaging optical system, and has a gradient index rod lens 66 arranged in front of the light emitting unit 63. Reference numeral 60 denotes a housing, and 67 denotes a fixed leaf spring.

  The housing 60 covers the periphery of the glass substrate 62, and the side facing the image carrier is open. In this way, light is emitted from the gradient index rod lens 66 to the image carrier. Therefore, the gradient index rod lens 66 functions as means for imaging the light emitted from the light emitting element on the irradiated surface. A light-absorbing member (paint) is provided on the surface of the housing 60 that faces the end surface of the glass substrate 62.

  FIG. 1 is an explanatory diagram showing an embodiment of the present invention. 1 (a) and 1 (b) correspond to FIGS. 6 (a) and 6 (b). The same parts as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 1A, in this example, the light emitting element lines 3 are arranged in one column in the sub-scanning direction, and the SLA is arranged in one column in the sub-scanning direction. As described with reference to FIG. 6, depending on the relative positional relationship between the light emitting element 2 and the rod lens 4 in the main scanning direction, the spread shape of light rays such as the spots 5 and 6 is different on the irradiated surface, and the imaging area is increased. There will be a difference.

  FIG.1 (c) has shown the example which changed the shape of the light emitting element by this invention. That is, as shown in FIG. 1B, a light emitting element arranged at a position close to the position of the rod lens adjacent in the main scanning direction at the pitch of the diameter of the lens is indicated by the reference numeral 11 in FIG. As shown, the size of the light beam is reduced to correct the shape of the light beam. The spot shape in this case is the same as the shape of the spot 5 by the light emitting element 2 as shown in FIG.

  As shown in FIG. 1C, a light emitting element 11 having a size smaller than that of the normal light emitting element 2 is provided. For this reason, when the light emitted from the light emitting element 11 passes through the lens array at a position where the lenses are adjacent to each other in the main scanning direction, the imaging area of the irradiated surface is reduced and the light emitting element having a normal size. 2 is formed in the same size as the image formation area. Therefore, it is possible to prevent image quality deterioration due to unevenness of the imaging area.

  FIG. 2 is an explanatory view showing another embodiment of the present invention. In FIG. 2, the light emitting element lines 3 are arranged in one column in the sub-scanning direction, and the SLA is arranged in two columns in the sub-scanning direction. 4 and 14 are rod lenses of each SLA. In the example of FIG. 2, the shape of the spot 6 is different from the shape of the spot 5 at a pitch of the radius (1/2) D of the rod lens.

  In this case, as shown in FIG. 2C, the shape of the light emitting elements 11 arranged at a position close to the position of the rod lens adjacent to the main scanning direction at a pitch of 1/2 of the lens diameter is emitted. The shape of the light beam at the imaging position is corrected by making it smaller than the shape of the element 2. For this reason, as shown in FIG. 2D, the shape of the spot by the light emitting element 11 is the same as the shape of the spot 5 by the light emitting element 2.

  FIG. 3 is an explanatory view showing another embodiment of the present invention. As shown in FIG. 3A, the light emitting element lines 3 are arranged in two rows in the sub-scanning direction, and the SLA is arranged in two rows in the sub-scanning direction. FIG. 3B is a partially enlarged view of the light emitting element. In the example of FIG. 3, the shape of the light emitting element 11 is made smaller than the shape of the light emitting element 2 at a pitch of the radius (1/2) D of the rod lens as in the example of FIG. 2. Therefore, as described in the example of FIG. 2, the shape of the image formation area spread by the light emitting element at a position close to the rod lens adjacent in the main scanning direction can be corrected in the example of FIG.

  In the configuration shown in FIG. 3, two rows of SLA are arranged in the sub-scanning direction, but one row of SLA may be arranged in the sub-scanning direction. In this case, the light emitting element lines 3 are arranged in two rows in the sub-scanning direction, and the SLA is arranged in one row in the sub-scanning direction. Therefore, as described with reference to FIG. 1, the shape of the light emitting element 11 is different from the shape of the light emitting element 2 at the pitch of the diameter D of the rod lens.

  FIG. 4 is an explanatory view showing another embodiment of the present invention. In FIG. 4, the light emitting element lines 3 are arranged in one column in the sub-scanning direction, and the SLA is arranged in two columns in the sub-scanning direction. FIG. 4B is a partially enlarged view of the light-emitting element, and the light-emitting elements 12 and 13 have a double ring structure. In the example of FIG. 4, the shape of the light emitting element 12 is made smaller than the shape of the light emitting element 13 at a pitch of the radius (1/2) D of the rod lens as in the example of FIG. Also in this case, it is possible to correct the shape of the spread of the imaging area by the light emitting element at a position close to the rod lens adjacent in the main scanning direction.

  In the configuration of FIG. 4, the light emitting element lines 3 are arranged in one row in the sub-scanning direction and the SLA is arranged in two rows in the sub-scanning direction. However, the light emitting element lines 3 may be arranged in two rows in the sub-scanning direction. . Further, as described with reference to FIG. 1, the light emitting element lines 3 may be arranged in one row in the sub-scanning direction, and the SLA may be arranged in one row in the sub-scanning direction.

  Furthermore, as described in the modification of FIG. 3, the light emitting element lines 3 may be arranged in two rows in the sub-scanning direction, and the SLA may be arranged in one row in the sub-scanning direction. In the case where the SLA is arranged in one line in the sub-scanning direction, the shape of the light emitting element 12 is different from the shape of the light emitting element 13 at a pitch of the diameter D of the rod lens. It is also possible to arrange three or more light emitting element lines in the sub-scanning direction.

  Thus, in the optical writing device of the present invention, the light emitting element lines are arranged in one or two rows in the sub-scanning direction. SLA is also arranged in one or two rows in the sub-scanning direction. The combination of the number of light emitting element lines and the number of SLA columns can be arbitrarily selected. It is also possible to arrange light emitting element lines in three or more rows in the sub-scanning direction and to apply to uses such as multiple exposure. When three or more light emitting element lines are arranged in the sub-scanning direction, it is possible to appropriately select the SLA to be arranged in one or two rows in the sub-scanning direction.

  When an organic EL element is used for the light-emitting portion of the optical writing device, the light-emitting pixel column is manufactured on a single substrate using a semiconductor process, so its linearity is much higher than that of a conventional LED. It is possible to configure with high accuracy. Furthermore, there is an advantage that the unevenness of the light amount of the light emitting element is smaller than the unevenness of the transmitted light amount of the lens array. Note that the alignment of the center of the light emitting element line and the center line of the lens array can be easily performed.

  The optical writing apparatus of the present invention has been described based on some embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.

It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is a perspective view of an optical writing device. It is explanatory drawing which shows a spot shape. It is explanatory drawing which shows the example which a spot shape changes periodically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a-1c ... Optical writing apparatus, 2, 11-13 ... Light emitting element, 3 ... Light emitting element line, 4, 14 ... Refractive index distribution type rod lens array (SLA), 5 ... Spot shape, 6 ... Spot shape,
DESCRIPTION OF SYMBOLS 50 ... Optical writing apparatus, 61 ... Organic EL element array, 62 ... Glass substrate (transparent substrate), 63 ... Light emission part, 64 ... Cover glass, 65 ... Refractive index distribution Type rod lens array (SLA), 66... Refractive index distribution type rod lens

Claims (11)

An optical writing apparatus comprising: a transparent substrate on which a plurality of light emitting elements are arranged in a main scanning direction; and a lens array that forms an image of light emitted from the light emitting elements on an irradiated surface. An optical writing apparatus, wherein the size of the light emitting element is varied according to the relative position of the light emitting element in the main scanning direction with respect to the array. The optical writing device according to claim 1, wherein the size of the light emitting element is varied with a pitch of diameters of lenses arranged in the lens array. 2. The optical writing device according to claim 1, wherein the size of the light emitting element is made different at a pitch of 1/2 of the diameter of the lenses arranged in the lens array.   4. The optical writing device according to claim 1, wherein the size of the light emitting element is smaller than that of a normal light emitting element. 5. The optical writing device according to claim 1, wherein the light emitting element lines are formed in one line in the sub-scanning direction. 5. The optical writing device according to claim 1, wherein the light emitting element lines are formed in two rows in the sub-scanning direction. The optical writing device according to claim 5, wherein the lens array is formed in one row in the sub-scanning direction. The optical writing device according to claim 5, wherein the lens array is formed in two rows in the sub-scanning direction. 9. The optical writing device according to claim 7, wherein the light emitting element lines are formed in three or more rows in the sub-scanning direction. The optical writing device according to claim 1, wherein the light emitting element is an organic EL element. 11. The optical writing device according to claim 1, wherein the light emitting element has a double ring structure.

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