JP4552629B2 - Optical writing apparatus and position adjustment method thereof - Google Patents

Description

  The present invention relates to an optical writing device that detects a positional deviation between a center line of a rod lens and a center of a light emitting element line and aligns a transparent substrate, and a position adjusting method thereof.

  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. In the method using the light emitting element array, it is necessary to align the light emitting element and the lens. For example, Patent Document 1 describes an example in which a mark for indicating the center position of a lens is provided on a lens holder for positioning an image array having a plurality of light emitters and a monocular lens.

JP-A-7-186444

  When an optical system such as a light emitting element array is used, the line head imaging optical system is an equal-magnification optical system using a rod lens array having two rows of rod lenses as shown in FIG. Generally used. In FIG. 13, 84 and 84 are rod lenses arranged in two rows. In this rod lens array, the center line of the rod lens array parallel to the main scanning direction needs to coincide with the position of the light emitting element in the sub scanning direction, but this position may be shifted.

  In FIG. L is the center line of the rod lens array, and A is the position of the light emitting element. An example in which the position of the light emitting element is shifted from the center line C.I. An example of deviation from L by 0.2 mm is shown. As described above, when the position of the light emitting element is deviated from the center line of the rod lens array, the light amount varies. FIG. 14A is a characteristic diagram showing the light amount variation in the main scanning direction, and FIG. 14B is a characteristic diagram showing the light amount distribution data in the sub-scanning direction. As shown in FIG. 14B, the variation in the amount of light when the position of the light emitting element is shifted in the sub-scanning direction occurs symmetrically with respect to the shift amount.

  In the example of FIG. 13, the diameter of the rod lens is 0.56 mm. In this case, the variation in the amount of light in the main scanning direction in FIG. 14A is that if the deviation between the position of the light emitting element and the center line of the rod lens array is 0, the unevenness of the amount of light as in the characteristic Da is the diameter of the rod lens. It is 0.28 of 1/2. When the amount of deviation between the two is 0.1 mm, the light amount unevenness period is a sum of 0.28 mm which is ½ of the diameter of the rod lens and 0.56 mm of the diameter. In this case, the light amount unevenness cycle is twice as long as the deviation amount is zero. When the amount of deviation between the two is 0.2 mm, the period of unevenness in the amount of light is 0.56 mm in diameter of the rod lens.

  As described above, when the position of the light emitting element deviates from the center line of the rod lens array, the following problem occurs. (1) The period of unevenness in the amount of light passing through the rod lens is doubled, making it easy to recognize the unevenness in the amount of light and making the deterioration of the image quality clear. (2) Unevenness in the amount of light passing through the rod lens increases. (3) The amount of light passing through the rod lens decreases. (4) The imaging performance deteriorates, and the spot diameter increases or varies.

  In a line head using LEDs as described in Patent Document 1 as a conventional light emitting element, an image array is mounted on a substrate to constitute a line head. For this reason, the pixel column of the light emitting unit does not become a straight line due to a mounting error, and it is difficult to align the center line of the lens array for all the light emitting pixels. Further, the light amount unevenness of the light emitting unit itself is larger than the transmitted light amount unevenness of the lens array, and in order to correct this, the light amount correction control is performed for each light emitting element based on the light amount after passing through the head. It was necessary to correct both the unevenness in the amount of light of the unit itself and the unevenness in the amount of transmitted light of the lens array. There is also a problem that the spot diameter cannot be corrected.

  In a line head formed of a plurality of light emitting elements, as described above, there is a problem in accurately aligning the center of the light emitting element and the center of the lens. However, there are various problems as described above. It was. As described above, in a line head using LEDs described in Patent Document 1, a method of providing a marking for indicating a center detection position for each light emitting element array and a center position for each lens has been proposed.

  In the method of providing such a marking, the center of the array and the center of the substrate are detected, and the individual lens positions are adjusted so that these centers coincide with the centers of the lenses. However, the method described in Patent Document 1 has a problem in that when a lens in which a plurality of lenses are arranged in an array is used, adjustment for each lens cannot be performed. Further, in this method, since the center position is detected by the shape of the electrode, there is a problem that the shape of the electrode is restricted.

  The present invention has been made in view of such problems of the prior art, and its purpose is to detect misalignment between the center line of the rod lens and the center of the light emitting element line, and to easily align them. It is an object of the present invention to provide an optical writing device and a position adjusting method thereof performed by such means.

The position adjustment method of the optical writing device of the present invention includes:
(1) a step of holding a transparency substrate having a common electrode having a light emitting element and a first reflectivity arranged plurality in the main scanning direction, the holding means having a second reflectivity,
(2) fixing the lens array to the support member;
(3) attaching the holding means to the support member;
(4) imaging the transparent substrate through the lens array by a detection means, and recognizing the position of the common electrode and the position of the lens array;
(5) calculating a positional deviation of the lens array against the light emitting element,
(6) a step wherein the support member is moved in the sub-scanning direction by adjusting the positional deviation, to align the lens array b against the light emitting element,
(7) and having a, and fixing the retaining means to the support member. According to this configuration, the position of the center line of the lens array can be adjusted by a simple method with reference to the center of the light emitting part formed on the transparent substrate.

  In the optical writing device of the present invention, the width of the common electrode in the sub-scanning direction is set wider than the width of the lens array. According to this configuration, since one side edge portion of the common electrode is used as a reference for detecting the positional deviation in the sub-scanning direction, the process of calculating the positional deviation between the center line of the lens array and the center of the light emitting element line can be easily performed. Yes.

  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, it is possible to accurately detect the positional deviation between the lens array and the light emitting unit.

  According to the present invention, since the reflectance of the transparent substrate holding means and the common electrode are set to different values, it is possible to easily confirm the position of the common electrode and the lens array. Therefore, it is possible to easily adjust the position of the center line of the lens array with reference to the center of the light emitting element line formed on the transparent substrate. As described above, since it is possible to prevent the occurrence of the positional deviation from the center of the light emitting portion due to the mounting error of the lens array, it is possible to improve the imaging performance and obtain a high quality image.

  The present invention will be described below with reference to the drawings. FIG. 9 is an enlarged perspective view schematically showing the optical writing device 23 applied to the present invention. FIG. 9 shows details of the optical writing device 23. 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, each optical writing device 23 is fixed at a predetermined position.

  In the optical writing device 23, 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 gradient index rod lens array 65 constitutes an imaging optical system, and a gradient index rod lens 84 disposed in front of the light emitting unit 63 is stacked. Reference numeral 60 denotes a housing, 66 denotes a cover, 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 20 is open. In this way, light is emitted from the gradient index rod lens 84 to the image carrier 20. Therefore, the gradient index rod lens 84 functions as means for imaging the emitted light of 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.

  10 is a sectional view of the optical writing device 23 shown in FIG. 9 in the sub-scanning direction. The optical writing device 23 includes an organic EL element array 61 mounted facing the rear surface of the gradient index rod lens array 65 in the housing 60, and an organic EL light emitting element array in the organic EL element array 61 from the rear surface of the housing 60. An opaque cover 66 that shields 61 is provided. Further, the cover 66 is pressed against the back surface of the housing 60 by the fixed plate spring 67 to seal the inside of the housing 60 in a light-tight manner. That is, the glass substrate 62 is optically sealed with the housing 60 by the fixed plate spring 67. A plurality of fixed leaf springs 67 are provided in the longitudinal direction of the housing 60. Reference numeral 91 denotes an image surface (irradiated surface) formed on the image carrier.

  If a black paint that absorbs ultraviolet rays is applied to the inner surface of the case, the ultraviolet shielding effect on the organic EL element array 61 can be more reliably performed, and deterioration of the organic EL light emitting elements can be prevented. The housing 60 of the optical writing means 23 is formed of an opaque member, and the back surface thereof is covered with an opaque cover 66. For this reason, the fluorescent lamp and the ultraviolet rays from the sun incident on the back surface of the organic EL element array 61 are prevented from reaching the light emitting part 63 of the organic EL element array 61. Reference numeral 83 denotes an adhesive for fixing the glass substrate 62 to the housing 60.

  11 is a cross-sectional view of the optical writing device 23 shown in FIG. 9 in the main scanning direction. The glass substrate 62 covers the light emitting unit 63 using an organic EL element with a cover glass 64. Such a glass substrate 62 is fixed to the housing 60. At this time, the glass substrate 62 is positioned between the light emitting portion 63 and the center of the rod lens array 65. The glass substrate 62 is covered with the cover 66 and the cover 66 is fixed with a leaf spring 67.

12 is a cross-sectional view showing a configuration example in the vicinity of the light emitting portion 63 of the organic EL light emitting element array 61 shown in FIG. The organic EL light emitting element array 61 includes, for example, two rows of TFTs (thin film transistors) 71 made of polysilicon having a thickness of 50 nm for controlling the light emission of each light emitting portion 63 on a glass substrate 62 having a thickness of 0.5 mm. Corresponding to each of the light emitting portions 63, the outer margin is provided. An insulating film 72 made of SiO ₂ having a thickness of about 100 nm is formed on the glass substrate 62 excluding the contact hole on the TFT 71, and is thick at the position of the light emitting portion 63 so as to be connected to the TFT 71 through the contact hole. An anode 73 made of ITO having a thickness of 150 nm is formed.

Then, another insulating film 74 made of SiO ₂ having a thickness of about 120nm in a portion corresponding to the position other than the light emitting portion 63 is deposited, the thickness of 2μm was formed a hole 76 corresponding to the light emitting unit 63 thereon A partition wall 75 made of polyimide is provided. A hole injection layer 77 having a thickness of 50 nm and a light emitting layer 78 having a thickness of 50 nm are formed in order from the anode 73 side in the hole 76 of the partition wall 75, and the upper surface of the light emitting layer 78, the inner surface of the hole 76, and the partition wall. A cathode first layer 79a made of Cu having a thickness of 100 nm and a cathode second layer 79b made of Al having a thickness of 200 nm are sequentially formed so as to cover the outer surface of 75.

  Then, the light emitting portion 63 of the organic EL light emitting element array 61 is configured by being covered with a cover glass 64 having a thickness of about 1 mm via an inert gas 80 such as nitrogen gas. Light emission from the light emitting unit 63 is performed on the glass substrate 62 side. Various known materials can be used as the material used for the light emitting layer 78 and the material used for the hole injection layer 77, and detailed description thereof is omitted. Such an organic EL light emitting element can be easily manufactured on a glass substrate, and thus the manufacturing cost can be reduced.

  FIG. 1 is a cross-sectional view in the sub-scanning direction of the optical writing device according to the embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a glass substrate (corresponding to reference numeral 62 in FIG. 10), on which a plurality of light-emitting elements (not shown) and a cathode as a common electrode of each light-emitting element are formed. 2 is a substrate holder for holding the glass substrate 1 (corresponding to numeral 66 in FIG. 10), 3 is an SLA (corresponding to numeral 65 in FIG. 10), and 4 is a support member for SLA3 (indicated numeral 60 in FIG. 10). 10 is a CCD camera. The reflectance of the cathode formed on the glass substrate 1 (first reflectance) and the reflectance of the substrate holder 2 (second reflectance) are set to different values.

  2A and 2B are partial views of FIG. 1, in which FIG. 2A is a sectional view in the main scanning direction, and FIG. 2B is a plan view. Next, the positioning procedure will be described with reference to FIGS. (1) The glass substrate 1 is held on the substrate holder 2 by an appropriate means such as an adhesive. The substrate holder 2 functions as a holding means for the glass substrate 1 (transparent substrate). (2) The SLA 3 is inserted into the opening 4x of the support member 4 and placed on the step 4y and fixed. (3) The substrate holder 2 is inserted into the opening 4a of the support member 4, and is fixedly attached to the step 4b. At this time, a slight gap exists in the sub-scanning direction between the substrate holder 2 and the support member 4.

  (4) The glass substrate 1 is imaged through the SLA 3 by the CCD camera 10. A state where the glass substrate 1 is observed from the CCD camera 10 is as shown in FIG. (5) As described above, the reflectance of the cathode (common electrode) formed on the glass substrate 1 and the reflectance of the substrate holder 2 are set to different values. For this reason, the intensity | strength of the reflected light from the substrate holder 2 which permeate | transmits the glass substrate 1 differs from the reflected light from a cathode. Therefore, the cathode position and the position of the rod lens can be easily recognized by the CCD camera 10. The CCD camera 10 functions as a position detection unit for the common electrode and the lens array.

  (6) The positional relationship between the width of the cathode in the sub-scanning direction and the center of the light emitting element line is stored in advance in the storage means of the control unit. Therefore, when the width of the cathode in the sub-scanning direction is imaged by the CCD camera 10, the position shift of the center line of the SLA 3 with respect to the center of the light emitting element line can be calculated. The misregistration between the two is calculated by the control unit shown in FIG. (7) The support member 4 is moved in the sub-scanning direction (X direction) to adjust the positional deviation, and the center line of the SLA 3 is aligned with the center of the light emitting element line. In this example, the support member 4 functions as an adjustment unit that aligns the center line of the lens array and the center of the light emitting element line. (8) The substrate holder 2 is fixed to the support member 4 with an adhesive or the like. (9) The support member 4 is attached to the case of the head (optical writing head). Thus, in the embodiment of the present invention, the alignment of the center line of the SLA is performed based on the center of the light emitting unit. For this reason, it is possible to prevent the occurrence of a positional deviation from the center of the light emitting part due to an SLA attachment error, and to suppress a decrease in imaging performance.

  FIG. 3 is a block diagram showing a schematic configuration of the control unit of the position adjusting means. In FIG. 3, 101 is a control unit, 102 is a misregistration detection unit of the optical writing apparatus, 103 is a memory, 104 is a control circuit, and 105 is a drive circuit. The displacement detection unit 102 uses a sensor such as the CCD camera 10 shown in FIG.

  Reference numeral 100 denotes a main body controller. The position shift detection unit 102 images the rod lens and the common electrode (cathode) formed on the glass substrate as described above. The memory 103 stores the positional relationship between the common electrode and the center of the light emitting unit.

  The control circuit 104 reads out data on the positional relationship between the common electrode and the center of the light emitting unit from the memory 103 and compares the data of the center of the light emitting unit with the SLA by comparing with the data on the common electrode detected by the misalignment detecting unit 102. The positional deviation from the center line is calculated. The control circuit 104 sends a signal to the drive circuit 105 to control the position of the support member.

  FIG. 4 is an explanatory view showing an example of the cathode formed on the glass substrate 1. In FIG. 4, the illustration of the substrate holder described in FIG. 1 is omitted. The width (length in the sub-scanning direction) Wa of the cathode 6 (corresponding to the reference numerals 79a and 79b in FIG. 12) as a common electrode for a plurality of light emitting elements is formed narrower than the width Wb of the glass substrate 1. . For this reason, the reflected light from the substrate holder passes through the portion of the glass substrate 1 where the cathode 6 is not formed.

  Further, the edge portions on both sides of the cathode 6 are detected by the CCD camera. As described above, since the reflectance of the cathode and the reflectance of the substrate holder 2 are set to different values, the cathode and SLA can be easily detected by the CCD camera. Based on the detection result, the control unit can calculate the positional deviation between the position of the center line of the SLA and the light emitting element line (not shown). Therefore, as described with reference to FIG. 1, the position of the center line of the SLA and the center position of the light emitting element line can be aligned by adjusting the holding member of the SLA.

  FIG. 5 is an explanatory view showing another embodiment of the present invention. In FIG. 5, the width of the cathode 7 is set substantially equal to the width of the glass substrate 1. Further, the length of the cathode 7 in the main scanning direction is shorter than the length of the glass substrate 1. In this example, it is possible to detect the reflected light from the substrate holder by the CCD camera with the light transmitted through both side ends (portions where the cathode 7 is not formed) of the glass substrate 1. The cathode 7 is also detected by the CCD camera. Also in the example of FIG. 5, it is possible to calculate the positional deviation between the position of the center line of the SLA and the light emitting element line, and to align the position of the center line of the SLA and the center position of the light emitting element line.

  FIG. 6 is an explanatory view showing another embodiment of the present invention. In FIG. 6, the width of the cathode 8 is the same as the width of the rod lens 11. In the example of FIG. 6, the width of the rod lens 11 is also detected by detecting both side edges of the cathode 8 with a CCD camera. In this case, ½ of the width dimension of the cathode 8 becomes the center line of the SLA, so that the process of calculating the positional shift between the position of the center line of the SLA and the light emitting element line is simplified.

  FIG. 7 is an explanatory view showing another embodiment of the present invention. In FIG. 7, the width of the cathode 9 is narrower than the width of the rod lenses 11a and 11b. Only a part of the glass substrate 1 is displayed. Reference numerals 21 and 22 denote light emitting element lines in which a plurality of light emitting portions (light emitting elements) are arranged in the main scanning direction. Y1 is the length between one side edge of the cathode 9 and the outer tangent line of the rod lens 11a, and Y2 is the length between the other side edge of the cathode 9 and the outer tangent line of the rod lens 11b.

  By detecting Y1 and Y2 with a CCD camera, it is possible to detect a positional shift between the center line CL of the SLA and the cathode 9. Since the lengths from both side edges of the cathode 9 to the centers of the light emitting element lines 21 and 22 are preset and known, the positions of the center line CL of the SLA and the centers of the light emitting element lines 21 and 22 are known. The deviation can be calculated. In the configuration of FIG. 7, since the light emitting element lines 21 and 22 are arranged in a plurality of rows in the sub-scanning direction, the optical writing device can be applied to various uses such as multiple exposure. In addition, in embodiment of this invention, it is applied also when a light emitting element line forms one line in a glass substrate.

  FIG. 8 is an explanatory view showing another embodiment of the present invention. In FIG. 8, the cathode 12 is formed wider than the rod lenses 11a and 11b. Y3 is the length between one side edge 12a of the cathode 12 and the circumscribing line of the rod lens 11b. The length from one side edge 12a of the cathode 12 to the center of each light emitting element line 21, 22 is preset and known.

  In the example of FIG. 8, by detecting the length of Y3, that is, the length between the side edges 12a of the cathode 12 from the outer tangent of one rod lens 11b in the rod lenses arranged in two lines. The centers of the light emitting element lines 21 and 22 can be detected. For this reason, the positional deviation between the center line CL of the SLA and the centers of the light emitting element lines 21 and 22 can be calculated. In the example of FIG. 8, the one side edge portion 12a of the cathode 12 is used as a reference for detecting the positional deviation in the sub-scanning direction, so the positional deviation between the center line CL of the SLA and the centers of the light emitting element lines 21 and 22 is calculated. Processing is easy.

  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. As described above, in the embodiment of the present invention, the center of the light emitting unit is different from the optical writing device 23 in which a plurality of organic EL elements that can be manufactured with good linearity in the process are arranged in one line to form the light emitting unit. Is used to detect the SLA misalignment. For this reason, it is possible to accurately detect the misalignment between the light emitting unit and the SLA and accurately align the SLA.

  Furthermore, the organic EL element has a smaller light amount unevenness of the light emitting element itself than the transmitted light amount unevenness of the lens array, and if the center line of the lens array and the light emitting element array can be positioned with high accuracy, the light amount can be made uniform without light amount correction. And the spot diameter is uniform. Therefore, an optical writing device with high image quality can be configured. The present invention focuses on the characteristics of such organic EL elements to detect misalignment of the optical writing device and adjust alignment.

  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 sectional drawing in the subscanning direction of the optical writing apparatus of this invention. It is a figure which shows FIG. 1 partially. It is a block diagram which shows the control part 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 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 sectional drawing of the subscanning direction of an optical writing device. It is sectional drawing of the main scanning direction of an optical writing device. It is sectional drawing which shows the structural example of the light emission part vicinity. It is explanatory drawing which shows the example of the position shift of a light emission part. It is a characteristic view which shows light quantity variation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass substrate (transparent substrate), 2 ... Substrate holder, 3 ... Gradient index rod lens array (SLA), 4 ... Support member,
6 to 9, 12 ... cathode (common electrode), 10 ... CCD camera, 11 ... rod lens, 21, 22 ... light emitting element line, 23 ... optical writing device, 61 ... Organic EL element array, 62: glass substrate (transparent substrate), 63: light emitting section, 64: cover glass, 65: gradient index rod lens array (SLA), 84: refractive index Distributed rod lens, 100... Body controller, 101... Control unit, 102... Misregistration detection unit, 103.

Claims (1)

(1) Transparent in which a plurality of light emitting elements arranged in the main scanning direction and a common electrode having a first reflectance are formed
Holding the substrate on a holding means having a second reflectivity;
(2) fixing the lens array to the support member;
(3) attaching the holding means to the support member;
(4) The transparent substrate is imaged through the lens array by a detecting means, and the common electrode
Recognizing the position and the position of the lens array;
(5) calculating a displacement of the lens array with respect to the light emitting element;
(6) The support member is moved in the sub-scanning direction to adjust the positional deviation, and
Aligning the lens array to be
(7) fixing the holding means to the support member;
A method for adjusting the position of an optical writing device, comprising:

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