JP4595511B2 - Optical writing device - 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.

  In a tandem or rotary image forming apparatus, 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 a 1 × optical system using a rod lens array having two rows of rod lenses as shown in FIG. Generally used. In FIG. 14, 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. 15A is a characteristic diagram showing the light amount variation in the main scanning direction, and FIG. 15B is a characteristic diagram showing the light amount distribution data in the sub-scanning direction. As shown in FIG. 15B, the variation in the amount of light when the position of the light emitting element is shifted in the sub-scanning direction occurs in a symmetrical manner with respect to the shift amount.

  In the example of FIG. 14, the diameter of the rod lens is 0.56 mm. In this case, when 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 light amount 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, its object is to the center line of the rod lens, and can detect the positional deviation of the center of the light-emitting element lines, the position of the transparent substrate An object of the present invention is to provide an optical writing apparatus that performs alignment by simple means.

In order to achieve the above object, an optical writing device of the present invention comprises:
A plurality of light emitting elements arranged in a line in the main scanning direction;
A transparent substrate on which a common electrode of the plurality of light emitting elements is formed;
A rod lens array that is disposed at a position facing the light emitting element and forms an image of light emitted from the light emitting element on an irradiated surface;
The length of the transparent substrate in the main scanning direction is longer than the length of the common electrode, and the position of the center line in the rod lens array and the center line of the light emitting element line composed of the light emitting elements arranged in the line shape An adjustment means for performing the alignment is provided.
According to this configuration, light transmitted through the two side portions of the transparent substrate, the position of the center line of the rod lens array to can be easily detected by the detecting means, and the center line of the rod lens array, the light emitting element It is possible to prevent a decrease in imaging performance due to a positional deviation from the center of the line.

Further, the optical writing device of the present invention is characterized in that the width of the common electrode in the sub-scanning direction is set narrower than the width of the transparent substrate . According to this configuration, the amount of light that passes through the transparent substrate without being blocked by the common electrode is increased, so that there is an advantage that the center line of the rod lens array can be easily detected.

In the optical writing device of the invention, the width of the common electrode in the sub-scanning direction is set equal to the width of the rod lens array. According to this configuration, the width of the rod lens array is also detected by detecting both side edges of the common electrode, and the positional deviation between the position of the center line of the rod lens array and the center of the light emitting element line is detected. Easy detection.

In the optical writing device of the present invention, the width of the common electrode in the sub-scanning direction is set to be narrower than the width of the rod lens array. According to this configuration, from the side edges on both sides of the common electrode and the length in the sub-scanning direction between the circumscribing lines of each rod lens array, the position of the center line of the rod lens array and the center of the light emitting element line are calculated. The position deviation can be calculated.

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 rod lens array. According to this configuration, since one side edge portion of the common electrode is used as a reference for detecting the displacement in the sub-scanning direction, the process of calculating the displacement between the center line of the rod lens array and the center of the light emitting element line is simple. Can be done.

  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.

  In the optical writing device of the present invention, the light emitting element lines are arranged in a plurality of columns in the sub-scanning direction. According to this configuration, the optical writing device can be applied to various uses.

According to the optical writing apparatus of the present invention, since the transparent substrate is provided, the position of the rod lens array can be confirmed through the transparent substrate. For this reason, the position of the rod lens can be easily confirmed by setting the common electrode width of the light emitting elements to be equal to or smaller than the width of the rod lens array. Therefore, the position of the substrate can be adjusted by simple means, and the imaging performance can be improved to obtain a high-quality image.

  The present invention will be described below with reference to the drawings. FIG. 6 is a schematic perspective view showing the optical writing device 23 in an enlarged manner. FIG. 6 shows details of the optical writing device 23. The organic EL element array 61 is held in a long housing 60. Positioning pins 69 provided at both ends of the long housing 60 are fitted into opposing positioning holes of the case 50, and fixing screws are screwed into the screw holes of the case 50 through screw insertion holes 68 provided at both ends of the long housing 60. Each image writing means 23 is fixed at a predetermined position by screwing and fixing.

  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.

  FIG. 7 is a sectional view of the optical writing device 23 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 image 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.

  FIG. 8 is a cross-sectional view of the optical writing device 23 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.

FIG. 9 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. 10 is an explanatory diagram showing a process for positioning the optical writing device. In FIG. 10A, the rod lens array 65 is inserted into the opening 60a formed at the center of the housing 60, and the tip of the rod lens array 65 is locked by the stepped portion 60x provided in the opening 60a. Then, it is fixed to the housing 60. In (b), the light emitting portion (not shown) mounted on the glass substrate 62 is sealed with a cover glass 64, the glass substrate 62 is inserted into the housing 60, and mounted on the stepped portion 60 y formed inside the housing 60. Put.

  In this state, the CCD camera 90 causes the position of the light emitting portion mounted on the glass substrate 62 and the center line C.D. A positional deviation from L is detected, and the glass substrate 62 is positioned by a position adjusting means described later. At this time, the glass substrate 62 is moved in the arrow X direction (sub-scanning direction) for positioning. When the positioning is completed, (c) the glass substrate 62 is fixed to the housing 60 with the adhesive 83. Next, (d) the cover 66 is attached, the cover 66 is pressed by the fixed plate spring 67, and the flange portion 67a formed at the tip of the fixed plate spring 67 is locked to the stepped portion 60z formed outside the housing 60. Fix it. The housing 60 functions as a holding unit for the rod lens array 65.

  FIG. 11 is a cross-sectional view illustrating a specific example of misregistration detection. FIG. 11 corresponds to FIG. In FIG. 11, the rod lens array 65 is held in the housing 60, and the glass substrate 62 is fixed to the housing 60 with an adhesive 83 after adjusting the positional deviation. The center line of the rod lens array is C.I. When L is assumed, the center position of the light emitting portion 63 formed on the glass substrate 62 is shifted by ΔL from the center line of the rod lens array. This displacement is detected by the CCD camera 90. La is an optical path of the CCD camera 90. The amount of positional deviation detected by the CCD camera 90 is stored in the memory 103 shown in FIG.

  FIG. 12 is a plan view showing an example of position adjustment of the optical writing device 23 of the present invention. Screw fixing holes 68 a and 68 b are provided at both ends of the base 89 of the optical writing device 23 in order to fix it to the case on the image forming apparatus main body side. In the example of FIG. 12, the gradient index rod lenses 84 are arranged in two rows in the sub-scanning direction.

  An opening 89a is formed at the center of the base 89, and the glass substrate 62 is inserted into the opening 89a. Leaf springs 85a and 85b are provided on one side edge in the longitudinal direction of the opening 89a. One side edge in the longitudinal direction of the glass substrate 62 is pressed by the leaf springs 85a and 85b. Then, the center line of the rod lens array is observed with the CCD camera 90 described with reference to FIG. 10B, and the glass substrate 62 is moved in the sub-scanning direction while adjusting with the adjusting screws 86a and 86b. Positioning with the center line.

  At this time, the amount of positional deviation between the light emitting unit 63 and the center line of the rod lens array can be detected by the CCD camera 90, and data for correcting the amount of light can be acquired. When performing light amount correction, without adjusting the position of the glass substrate 62 as shown in FIG. 12, the voltage or current of the light emitting unit is controlled by the control means as shown in the block diagram of FIG. The amount of light is corrected by electrical means.

  As described above, in the embodiment shown in FIG. 12, a plurality of organic EL elements that can be manufactured with good linearity in the process are arranged in one line, and the light writing unit 63 is used as the light writing unit 63. A positional deviation is detected with reference to the center line of the rod lens array with a small mounting error. For this reason, it is possible to accurately detect the positional deviation between the light emitting unit 63 and the rod lens array, and to accurately align the glass substrate.

  Further, in the embodiment of the present invention, the detection of the positional deviation between the rod lens array and the glass substrate, that is, the light emitting unit is performed from the rear side of the glass substrate (the side opposite to the irradiation side of the output light of the organic EL element) from the rod. This is done by observing the lens array. For this reason, since the positions of the rod lens array and the glass substrate can be observed without being affected by the output light of the organic EL element, it is possible to easily detect the displacement between the two with high accuracy.

  FIG. 13 is a block diagram illustrating a schematic configuration of a control unit of the optical writing device. In FIG. 13, 101 is a control unit of the line head, 102 is a misregistration detection unit, 103 is a memory, 104 is a control circuit, and 105 is a drive circuit comprising TFTs. Reference numeral 106 denotes a light emitting unit in which a plurality of light emitting elements are arranged in one line (main scanning direction).

  Reference numeral 100 denotes a main body controller. The main body controller 100 forms print data and transmits it to the control unit 101 of the line head. The positional deviation detection unit 102 detects a positional deviation between the cathode and the center line of the rod lens. The memory 103 stores the amount of misalignment detected by the misalignment detection unit 102.

  The control circuit 104 reads out the characteristic of the positional deviation amount detected by the positional deviation detection unit 102 from the memory 103 and calculates the positional deviation between the center of the light emitting unit 106 and the center line of the rod lens. In addition, the control circuit 104 sends a signal to the drive circuit 104 to control the applied voltage or drive current of the light emitting unit 106.

  FIG. 1 is an explanatory diagram showing an embodiment of the present invention. In FIG. 1, the rod lens 84 is observed through the glass substrate 62 by the CCD camera 90 described in FIG. The width (length in the sub-scanning direction) Wa of the cathode 1 (corresponding to the reference numerals 79a and 79b in FIG. 9) as a common electrode for a plurality of light emitting elements is formed narrower than the width Wb of the glass substrate 62. . For this reason, since the light quantity which permeate | transmits the glass substrate (transparent substrate) 62, without interrupting | blocking by the cathode 1, increases, there exists an advantage that the detection of the centerline of a rod lens array becomes easy.

  At this time, since the edge portions on both sides of the cathode 1 are also detected by the CCD camera 90, the controller calculates the positional deviation between the position of the center line of the rod lens array and the light emitting element line (not shown). can do. Therefore, the position of the glass substrate 62 in the sub-scanning direction is adjusted using the adjusting screws 86a and 86b and the adjusting springs 85a and 85b described in FIG. 12, and the position of the center line of the rod lens array and the center position of the light emitting element line are adjusted. Can be aligned.

  FIG. 2 is an explanatory view showing another embodiment of the present invention. In FIG. 2, the width of the cathode 2 is substantially equal to the width of the glass substrate 62, and the one side edge 2 a overlaps the side edge of the glass substrate 62. The length of the cathode 2 in the main scanning direction is shorter than the length of the glass substrate 62. In this example, the position of the center line of the rod lens array can be detected by the CCD camera 90 with the light transmitted through both side ends of the glass substrate 62.

  The cathode 2 is also detected by the CCD camera 90. In the example of FIG. 2 as well, the positional deviation between the center line position of the rod lens array and the light emitting element line is calculated, and the center line position of the rod lens array and the center position of the light emitting element line are calculated using the mechanism of FIG. Can be aligned.

  FIG. 3 is an explanatory view showing another embodiment of the present invention. In FIG. 3, the width of the cathode 3 is the same as the width of the rod lens 84. In the example of FIG. 3, the width of the rod lens 84 is also detected by detecting both side edges of the cathode 3 with the CCD camera 90. In this case, since 1/2 of the width dimension of the cathode 3 becomes the center line of the rod lens array, the process of calculating the positional deviation between the position of the center line of the rod lens array and the light emitting element line is simplified. The

  FIG. 4 is an explanatory view showing another embodiment of the present invention. In FIG. 4, the width of the cathode 4 is narrower than the width of the rod lenses 84a and 84b. Only a part of the glass substrate 62 is displayed. Reference numerals 10 and 11 denote light emitting element lines in which a plurality of light emitting portions (light emitting elements) 63 are arranged in the main scanning direction. Y1 is the length between one side edge of the cathode 4 and the outer tangent line of the rod lens 84a, and Y2 is the length between the other side edge of the cathode 4 and the outer tangent line of the rod lens 84b.

  By detecting Y1 and Y2 with the CCD camera 90, it is possible to detect a positional shift between the center line CL of the rod lens array and the cathode 4. Since the lengths from both side edges of the cathode 4 to the centers of the light emitting element lines 10 and 11 are preset and known, the center line CL of the rod lens array and the centers of the light emitting element lines 10 and 11 Can be calculated. In the configuration of FIG. 4, since the light emitting element lines 10 and 11 are arranged in a plurality of columns 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. 5 is an explanatory view showing another embodiment of the present invention. In FIG. 5, the width of the cathode 5 is formed wider than the width of the rod lens 84. Y3 is the length between one side edge 5a of the cathode 5 and the circumscribing line of the rod lens 84b. The length from one side edge 5a of the cathode 5 to the center of each light emitting element line 10, 11 is preset and known.

In the example of FIG. 5, by detecting the length of Y3, that is, the length between the side edges 5a of the cathode 5 from the outer tangent of one rod lens 84b in the rod lenses arranged in two lines. In other words, the positional deviation of the light emitting element lines 10 and 11 is detected. For this reason, it is possible to detect a positional shift between the center line CL of the rod lens array and the centers of the light emitting element lines 10 and 11. In the example of FIG. 5, the one side edge portion 5a of the cathode 5 is used as a reference for detecting the positional deviation in the sub-scanning direction. The calculation process can be performed easily.

  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, the light amount unevenness of the light emitting element itself is also smaller than the transmitted light amount unevenness of the lens array, and if the center line of the lens array and the light emitting element row can be positioned with high accuracy, the light amount can be made uniform without light amount correction, The spot diameter is also uniform. For this reason, a high-quality line head can be configured. The present invention detects misalignment of an optical writing device by paying attention to the characteristics of such an organic EL element.

  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 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 positioning of a glass substrate. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of alignment. It is a block diagram which shows the control part of this invention. 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 1-5 ... Cathode (common electrode) 10, 11 ... Light emitting element line, 23 ... Optical writing apparatus, 61 ... Organic EL element array, 62 ... Glass substrate (transparent substrate) , 63 ... Light emitting part, 64 ... Cover glass, 65 ... Refractive index distribution type rod lens array (SLA), 84 ... Refractive index distribution type rod lens, 85a, 85b ... Leaf spring, 86a, 86b ... Adjustment screw, 88 ... Drive circuit, 90 ... CCD camera, 100 ... Main body controller, 101 ... Control unit, 102 ... Position detection unit, 103 ... Memory , 104... Control circuit, 105... Drive circuit, 106.

Claims (7)

A plurality of light emitting elements arranged in a line in the main scanning direction;
A transparent substrate on which a common electrode of the plurality of light emitting elements is formed;
A rod lens array that is disposed at a position facing the light emitting element and forms an image of the emitted light of the light emitting element on an irradiated surface;
An adjusting means for forming the length of the transparent substrate in the main scanning direction longer than the length of the common electrode and aligning the center line of the rod lens array with the center line of the light emitting elements arranged in a line shape An optical writing device, comprising:
2. The optical writing device according to claim 1, wherein the width of the common electrode in the sub-scanning direction is set narrower than the width of the transparent substrate.
3. The optical writing device according to claim 1, wherein the width of the common electrode in the sub-scanning direction is set equal to the width of the rod lens array .
3. The optical writing device according to claim 1, wherein a width of the common electrode in the sub-scanning direction is set to be narrower than a width of the rod lens array .
3. The optical writing device according to claim 1, wherein a width of the common electrode in the sub-scanning direction is set wider than a width of the rod lens array .
The optical writing apparatus according to claim 1, wherein the light emitting element is an organic EL element.
  The optical writing device according to claim 1, wherein the light emitting element lines are arranged in a plurality of columns in the sub-scanning direction.

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