JP2006062221A - Luminous energy correction method of line head and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminous energy correction method of a line head which detects the displacement of a light emission section on the basis of a lens array and corrects luminous energy, and an image forming device. <P>SOLUTION: A displacement detection section 102 detects a displacement between a light emission section 106 and the center line of a rod lens. A memory 103 stores the displacement detected by the displacement detection section 102. A control circuit 104 reads the characteristics of the displacement detected by the displacement detection section 102 from the memory 103 and computes corrected luminous energy with respect to a reference luminous energy. On the basis of the result of computation, the driving circuit 104 sends a signal, controls the applied voltage of the light emission section 106, and the driving current for correcting luminous energy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light amount correction method and an image forming apparatus for a line head, in which a light amount is corrected by detecting a positional deviation of the light emitting element with respect to an optical system in a line head using an organic EL light emitting element.

  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

  In the case of using such an optical system, the imaging optical system of the line head is generally an equal-magnification optical system using a rod lens array having two rows of rod lenses as shown in the explanatory diagram of FIG. Used. In FIG. 30, 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. 31A is a characteristic diagram showing light amount variation in the main scanning direction, and FIG. 31B is a characteristic diagram showing light amount distribution data in the sub-scanning direction. As shown in FIG. 31B, when the position of the light emitting element is shifted in the sub-scanning direction, the variation in the light amount occurs symmetrically with respect to the shift amount.

  In FIG. 30, the diameter of the rod lens is 0.56 mm. If the deviation between the position of the light emitting element and the center line of the rod lens array is zero, the unevenness of the light amount in the main scanning direction in FIG. 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.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to detect a positional deviation of a light emitting unit with reference to a lens array and correct a light amount and an image correction method for a line head. It is to provide a forming apparatus.

  In order to achieve the above object, a light amount correction method for a line head according to the present invention includes a light emitting section in which a plurality of light emitting elements formed on a transparent single substrate are arranged, and a lens array holding means. The method includes: a step of detecting a positional deviation of the light emitting unit on the basis of the position of the lens array; and a step of correcting the light amount of the light emitting unit based on the detected positional deviation. As described above, the positional deviation of the light emitting portion is detected with respect to the line head having a small mounting error with respect to the line head in which a plurality of light emitting elements are arranged to form the light emitting portion. And the light quantity of the light emission part is correct | amended based on the detected position shift. For this reason, it is possible to correct both the light amount unevenness of the light emitting unit itself and the transmitted light amount unevenness of the lens array, and it is also possible to correct the spot diameter.

  In the light amount correction method for a line head according to the present invention, the positional deviation is detected from the side opposite to the output light irradiation side of the transparent substrate. As described above, since the positions of the rod lens array and the glass substrate can be observed without being affected by the output light of the light emitting element, the positional deviation between the two can be easily and highly accurately caused by the positional deviation. The variation in the amount of light to be corrected can be corrected.

  In the line head light amount correction method of the present invention, the length of the lens array in the main scanning direction is longer than the length of the sealing member that seals the light emitting portion. For this reason, it becomes possible to provide the said position shift detection means on the outer side of a sealing part, and it can detect position shift, without passing through a sealing part. Therefore, the positional deviation detection process can be simplified.

  In the line head light amount correction method of the present invention, the detection of the positional deviation is performed by means formed outside and / or inside the image forming area. When the misregistration detection means is provided outside the image forming area, it is possible to form an image without being disturbed by the misregistration detection means. For this reason, image quality can be improved. In addition, when the misregistration detection means is formed in the image forming area, the space for forming the misregistration detection means at both ends of the transparent substrate becomes unnecessary, so the length of the transparent substrate in the main scanning direction is shortened. Can do.

  The line head light amount correction method of the present invention is characterized in that a plurality of the positional deviation detection means are formed on the transparent substrate. As described above, by forming a plurality of positional deviation detection means, it is possible to improve the accuracy of positional deviation detection between the transparent substrate and the lens array.

  In the light amount correction method for a line head according to the present invention, the misregistration detection means is formed at both ends of the transparent substrate or at both ends and the center of the transparent substrate. When the misregistration detection means is formed at both ends of the transparent substrate, even if the length of the transparent substrate in the main scanning direction is increased, the detection of misregistration between the transparent substrate and the lens array in the sub scanning direction is an error. Can be done without. In addition, when the misalignment detection means is formed at both ends and the center of the transparent substrate, even if the lens array is deformed due to an error during manufacturing, the light emitting unit and the lens array are not deteriorated. Can be detected.

  In the line head light amount correction method of the present invention, the positional deviation is detected by detecting an alignment mark formed on the transparent substrate. In this way, for a line head in which a plurality of light emitting elements are arranged to form a light emitting portion, a positional deviation is detected using an alignment mark based on a lens array with a small mounting error. For this reason, it is possible to accurately detect the misalignment between the light emitting unit and the lens array, and it is possible to accurately correct the light amount of the line head.

  In the line head light amount correction method of the present invention, the alignment mark is a tangent line parallel to the main scanning direction of the lens array and in contact with the outer shape of the lens. Thus, since the alignment mark is formed in parallel with the center line of the rod lens array, it is possible to detect the positional deviation from the light emitting portion with high accuracy. In addition, it is possible to detect a positional deviation only in the sub-scanning direction with respect to the rod lens array, and a different reference can be used for the positional deviation detection in the main scanning direction.

  In the light amount correction method for a line head according to the present invention, the alignment mark has the same shape as the lens. For this reason, it is easy to detect the positional deviation between the alignment mark and the lens, and as a result, it is possible to accurately detect the positional deviation between the light emitting unit and the center line of the rod lens array. Further, it is possible to detect a positional shift in both the main scanning direction and the sub-scanning direction with respect to the lens array.

  In the line head light amount correction method according to the present invention, the misregistration detection is performed by detecting a module formed on the transparent substrate. As described above, since the existing module is used as the positional deviation detection means, a separate member is not required for the positional deviation detection, and the cost can be reduced.

  In the line head light amount correction method of the present invention, the module is a wiring connected to a drive circuit. As described above, since the wiring connected to the drive circuit is used as the positional deviation detecting means, the positional deviation between the lens array and the light emitting unit can be detected with high accuracy. Further, it is possible to detect a positional deviation only in the sub-scanning direction with respect to the lens array, and another standard can be used for the positional deviation detection in the main scanning direction.

  In the line head light amount correction method of the present invention, the positional deviation detection means is performed in the same step as the formation of the light emission pattern of the light emitting section. For this reason, it is possible to increase the relative accuracy between the light emitting unit and the positional deviation detection means.

  In the light amount correction method for a line head according to the present invention, the module is a cathode used for forming a light emitting part or a partition used when the light emitting element is formed on the transparent substrate. The cathode or the partition of the light emitting part is performed in the same process as the formation of the light emitting pattern of the light emitting part. For this reason, it is possible to increase the relative accuracy between the light emitting unit and the cathode or the partition which is a module for detecting displacement.

  In the light amount correction method for a line head according to the present invention, the light emitting element is an organic EL element. Thus, since the organic EL element which can manufacture the linearity satisfactorily in the process is used as the light emitting element, the positional deviation between the lens array and the light emitting unit can be detected with high accuracy.

  An image forming apparatus according to a first embodiment of the present invention includes a charging unit around an image carrier, a line head in which light amount unevenness based on positional deviation is corrected by any of the methods described above, a developing unit, and a transfer unit. And at least two image forming stations provided with the respective image forming units, and the image is formed in a tandem manner when the transfer medium passes through each station. With this configuration, in the line head used in the tandem type image forming apparatus, the positional deviation detection accuracy of the light emitting element with respect to the optical system can be improved, and light amount unevenness can be reduced by correcting the light amount.

  In addition, an image forming apparatus according to the second embodiment of the present invention includes an image carrier configured to carry an electrostatic latent image, a rotary developing unit, and a light amount unevenness based on misalignment by any of the methods described above. The rotary developing unit carries toner accommodated in a plurality of toner cartridges on its surface, and sequentially carries the image of different colors by rotating in a predetermined rotation direction. The toner is transferred from the rotary development unit to the image carrier by applying a development bias between the image carrier and the rotary development unit. The latent image is visualized to form a toner image. For this reason, in the line head used in the rotary type image forming apparatus, the positional deviation detection accuracy of the light emitting element with respect to the optical system can be improved and the amount of light unevenness can be reduced by correcting the amount of light.

  In addition, the image forming apparatus of the present invention includes an intermediate transfer member. For this reason, in a line head used for an image forming apparatus provided with an intermediate transfer member, it is possible to improve the accuracy of detecting the positional deviation of the light emitting element with respect to the optical system and reduce the amount of light unevenness by correcting the light amount.

  According to the light amount correction method and the image forming apparatus of the line head of the present invention, it is possible to accurately detect the positional deviation of the light emitting unit with reference to the lens array, and the light amount is corrected based on the detection result. For this reason, the amount of light can be made uniform, and the spot diameter becomes uniform. Therefore, it can be set as the structure which obtains a high quality image.

  The present invention will be described below with reference to the drawings. When an organic EL element is used for the light emitting part of the line head, the light emitting pixel column is manufactured using a semiconductor process on a single substrate, and therefore its linearity is extremely high compared to conventional LEDs. It becomes possible to comprise. 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 focuses on the characteristics of such an organic EL element and detects a positional deviation of the line head to correct the light amount.

  FIG. 23 is a vertical side view of an image forming apparatus using a line head whose position is adjusted according to the present invention. In this embodiment, an intermediate transfer belt is used as the transfer belt. In FIG. 23, the image forming apparatus 1 of the present embodiment is mounted on the housing body 2, the first opening / closing member 3 that can be opened and closed on the front surface of the housing body 2, and on the upper surface of the housing body 2. And a second opening / closing member 4 (also serving as a paper discharge tray). Further, the first opening / closing member 3 is provided with an opening / closing lid 3 ′ attached to the front surface of the housing body 2 so as to be freely opened and closed.

  In the housing body 2, an electrical component box 5 containing a power circuit board and a control circuit board, an image forming unit 6, a blower fan 7, a transfer belt unit 9, and a paper feeding unit 10 are disposed. In addition, a secondary transfer unit 11, a fixing unit 12, and a recording medium transport unit 13 are disposed in the first opening / closing member 3.

  The transfer belt unit 9 is disposed below the housing body 2 and is driven to rotate by a drive source (not shown), a driven roller 15 disposed obliquely above the drive roller 14, and the two rollers. An intermediate transfer belt 16 that is stretched between 14 and 15 and driven to circulate in the direction of the arrow shown in the figure, and a cleaning means 17 that comes into contact with and separates from the surface of the intermediate transfer belt 16.

  A primary transfer member 21 composed of a leaf spring electrode is brought into contact with the image carrier 20 of each image forming station Y, M, C, K by its elastic force, and a transfer bias is applied to the primary transfer member 21. ing. A test pattern sensor 18 is installed in the transfer belt unit 9 in the vicinity of the drive roller 14. The image forming unit 6 includes a plurality (four in this embodiment) of image forming stations Y (for yellow), M (for magenta), C (for cyan), and K (for black) that form images of different colors. Each of the image forming stations Y, M, C, and K includes an image carrier 20 including a photosensitive drum, and a charging unit 22 and an image writing unit (line head) disposed around the image carrier 20. ) 23 and developing means 24.

  The image carrier 20 is rotationally driven in the conveyance direction of the intermediate transfer belt 16 as indicated by the arrows in the figure. The charging means 22 is composed of a conductive brush roller connected to a high voltage generation source, and the outer periphery of the brush is opposite to the image bearing member 20 as a photosensitive member at a peripheral speed of 2 to 3 times. The surface of the image carrier 20 is uniformly charged by contact rotation.

  The image writing means 23 uses an organic EL element array in which organic EL elements are arranged in a line in the axial direction of the image carrier 20. The line head using the organic EL element array has an advantage that the optical path length is shorter and more compact than the laser scanning optical system, can be disposed close to the image carrier 20, and the entire apparatus can be downsized. . In the present embodiment, the image carrier 20, the charging unit 22, and the image writing unit 23 of each image forming station Y, M, C, and K are unitized as one image carrier unit 25.

  Next, details of the developing unit 24 will be described on behalf of the image forming station K. The developing unit 24 includes a toner storage container 26 that stores toner (hatched portion in the drawing), a toner storage part 27 formed in the toner storage container 26, and a toner stirring member disposed in the toner storage part 27. 29, and a partition member 30 that is partitioned and formed on the upper portion of the toner storage portion 27. Further, the toner supply roller 31 disposed above the partition member 30, the blade 32 provided on the partition member 30 and in contact with the toner supply roller 31, and the toner supply roller 31 and the image carrier 20 are in contact with each other. And a regulating blade 34 that is in contact with the developing roller 33.

  The paper feed unit 10 includes a paper feed unit including a paper feed cassette 35 in which the recording media P are stacked and held, and a pickup roller 36 that feeds the recording media P from the paper feed cassette 35 one by one. In the first opening / closing member 3, a registration roller pair 37 that regulates the feeding timing of the recording medium P to the secondary transfer portion, and a secondary transfer unit that is pressed against the drive roller 14 and the intermediate transfer belt 16. A secondary transfer unit 11, a fixing unit 12, a recording medium conveyance unit 13, a paper discharge roller pair 39, and a duplex printing conveyance path 40 are provided.

  The fixing unit 12 includes a heating roller 45 that includes a heating element such as a halogen heater and is rotatable, a pressure roller 46 that presses and biases the heating roller 45, and is swingable on the pressure roller 46. A belt tension member 47 and a heat-resistant belt 49 stretched between the pressure roller 45 and the belt tension member 47. The color image secondarily transferred to the recording medium is fixed to the recording medium at a predetermined temperature at a nip formed by the heating roller 45 and the heat-resistant belt 49.

  FIG. 24 is a partial cross-sectional view of the vicinity of the image carrier 20 shown in FIG. The image carrier unit 25 includes four images of image forming stations Y, M, C, and K that are spaced apart from each other in parallel in a case 50 made of an opaque metal plate or the like that is open on the side in contact with the intermediate transfer belt 16. A carrier (photosensitive drum) 20 is rotatably supported. The conductive brush roller of the charging unit 22 is supported so as to rotate in contact with each image carrier 20 at a predetermined position, and an image writing unit 23 including an organic EL array exposure head is provided on the downstream side of the charging unit 22. Each image carrier 20 is positioned and supported in parallel therewith.

  On the wall surface of the case 50 on the downstream side of the image writing unit 23, an opening 51 is provided to contact the developing roller 33 of the developing unit 24 corresponding to each image carrier 20. A shielding part 52 of the case 50 is left between each opening 51 and the image writing means 23, and a shielding part 53 of the case 50 is left between the charging means 22 and the image writing means 23. Yes.

  The shielding portions 52, 53, particularly the shielding portion 52 between the opening 51 and the image writing means 23, prevent ultraviolet rays from reaching the light emitting portion made of the organic EL material in the image writing means 23 from the outside. Reference numeral 82 denotes a cleaning pad for wiping off the gradient index rod lens array 65 (SLA) covering the organic EL element array 61 from the front surface. The cleaning pad 82 is reciprocated by a handle (not shown).

  FIG. 25 is a schematic perspective view showing the image writing unit 23 in an enlarged manner. In FIG. 25, details of the image writing means 23 are shown. A mechanism for accurately positioning the image writing means 23 with respect to each image carrier (photosensitive drum) 20 attached to the image carrier unit 25 is shown. 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.

  The image writing unit 23 mounts the light emitting portion 63 of the organic EL element array 61 on the glass substrate 62 and is driven by the 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. 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. 26 is a cross-sectional view of the image writing unit 23 in the sub-scanning direction. The image writing means 23 includes an organic EL element array 61 attached facing the rear surface of the gradient index rod lens array 65 in the housing 60, and an organic EL light emitting element array 61 in the housing 60 from the rear surface. And an opaque cover 66 for shielding the light. 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 formed on the image carrier.

  If a black paint that absorbs ultraviolet rays is applied to the inner surface of the case 50, 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. 27 is an explanatory diagram showing a process for positioning the line head. In FIG. 27A, 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 observes an alignment mark, which will be described later, while the position of the light emitting portion mounted on the glass substrate 62 and the center line C.D. Position with L. At this time, the glass substrate 62 is moved in the arrow X 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. 28 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.

Next, another insulating film 74 made of SiO ₂ having a thickness of about 120 nm is formed in a portion corresponding to a position other than the light emitting portion 63, and a hole 76 corresponding to the light emitting portion 63 is formed thereon, and the thickness is 2 μm. 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 Ca 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.

  Next, another embodiment of the image forming apparatus according to the present invention will be described. FIG. 28 is a vertical side view of the image forming apparatus. In FIG. 28, the image forming apparatus 160 includes, as main constituent members, a rotary developing device 161, a photosensitive drum 165 that functions as an image carrier, a line head 167 provided with an organic EL element, an intermediate transfer belt 169, A paper conveyance path 174, a fixing roller heating roller 172, and a paper feed tray 178 are provided. In the developing device 161, the developing rotary 161a rotates in the arrow A direction about the shaft 161b. The inside of the development rotary 161a is divided into four, and image forming units for four colors of yellow (Y), cyan (C), magenta (M), and black (K) are provided. Reference numerals 162a to 162d are arranged in the image forming units for the four colors. The developing rollers rotate in the arrow B direction, and the toner supply rollers 163a to 163d rotate in the arrow C direction. Reference numerals 164a to 164d are regulating blades that regulate the toner to a predetermined thickness.

  165 is a photosensitive drum that functions as an image carrier as described above, 166 is a primary transfer member, 168 is a charger, and 167 is an image writing means that is a line head using an organic EL element. The photosensitive drum 165 is driven in the direction of arrow D opposite to the developing roller 162a by a drive motor (not shown), for example, a step motor. The intermediate transfer belt 169 is stretched between the driven roller 170b and the drive roller 170a, and the drive roller 170a is connected to the drive motor of the photosensitive drum 165 to transmit power to the intermediate transfer belt. By driving the drive motor, the drive roller 170 a of the intermediate transfer belt 169 is rotated in the arrow E direction opposite to the photosensitive drum 165.

  The paper conveyance path 174 is provided with a plurality of conveyance rollers, a pair of paper discharge rollers 176, and the like, and conveys the paper. An image (toner image) on one side carried on the intermediate transfer belt 169 is transferred to one side of the paper at the position of the secondary transfer roller 171. The secondary transfer roller 171 is separated from and brought into contact with the intermediate transfer belt 169 by a clutch, and is brought into contact with the intermediate transfer belt 169 when the clutch is turned on, so that an image is transferred onto the sheet.

  The paper on which the image has been transferred as described above is then subjected to a fixing process by a fixing device. The fixing device is provided with a heating roller 172 and a pressure roller 173. The sheet after the fixing process is drawn into the discharge roller pair 176 and proceeds in the arrow F direction. When the paper discharge roller pair 176 rotates in the opposite direction from this state, the paper reverses its direction and advances in the double-sided printing conveyance path 175 in the arrow G direction. 177 is an electrical component box, 178 is a paper feed tray for storing paper, and 179 is a pickup roller provided at the outlet of the paper feed tray 178.

  For carrying four color images, the intermediate transfer belt 169 rotates four times, and then the rotation position is further controlled to transfer the image onto the sheet at the position of the secondary transfer roller 171. The paper fed from the paper feed tray 178 is transported by the transport path 174, and the color image is transferred to one side of the paper at the position of the secondary transfer roller 171. The sheet on which the image is transferred on one side is reversed by the discharge roller pair 176 as described above, and stands by on the conveyance path. Thereafter, the sheet is conveyed to the position of the secondary transfer roller 171 at an appropriate timing, and the color image is transferred to the other side. The housing 180 is provided with an exhaust fan 181.

  FIG. 4 is a plan view showing a glass substrate 62 used in the line head of the present invention. A light emitting unit 63 using an organic EL element is formed on the glass substrate 62, and each light emitting unit 63 is connected to a driving circuit 88 formed of a TFT or the like by a lead wire 92. Positioning marks (alignment marks) 87 a and 87 b are formed on both ends of the glass substrate 62. The alignment marks 87a and 87b are performed in the same process as the formation of the light emission pattern of the light emitting unit 63. For this reason, the relative accuracy of the light emission part 63 and alignment mark 87a, 87b can be improved.

FIGS. 5A and 5B are views showing an example in which the glass substrate 62 of FIG. 4 is covered with a cover glass 64, where FIG. The cover glass 64 is
The light emitting unit 63, the drive circuit 88, and the lead wire 92 are covered. Alignment marks 87 a and 87 b formed on both ends of the glass substrate 62 are exposed from the cover glass 64.

  FIG. 6 is a cross-sectional view of the line head 23 in the main scanning direction. As described with reference to FIGS. 4 and 5, the glass substrate 62 covers the light emitting portion 63 using the organic EL element with the 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. 7 is a plan view showing an example of position adjustment of the line head (image writing means) 23 of the present invention. Screw fixing holes 68a and 68b are provided at both ends of the base 89 of the line head 23 to fix the case 50 on the image forming apparatus main body side. Positioning marks (alignment marks) 87a and 87b are formed on both ends of the glass substrate 62 as described above. The rod lenses 84 are arranged in two rows.

  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 alignment marks 87a and 87b are observed with the CCD camera 90 described in FIG. 17B, and the glass substrate 62 is moved in the sub-scanning direction while being adjusted with the adjusting screws 86a and 86b. Position 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 is detected by the CCD camera 90, and data for performing light amount correction is acquired. In this case, without adjusting the position of the glass substrate 62 as shown in FIG. 7, the voltage or current of the light emitting unit is controlled as will be described later, and the light amount is corrected by electrical means.

  As described above, in the embodiment of FIG. 7, a rod lens array in which a plurality of organic EL elements that can be manufactured with good linearity in the process are arranged to reduce the mounting error with respect to the line head 23 serving as the light emitting unit 63. Is used as a reference to detect misalignment using alignment marks 87a and 87b. For this reason, it is possible to accurately detect the positional deviation between the light emitting unit 63 and the rod lens array.

  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 portion is detected from the rear side of the glass substrate (the side opposite to the irradiation side of the output light of the organic EL element) We look at the lens array and alignment marks. 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.

  In the example of FIG. 7, the length of the rod lens array in the main scanning direction is longer than the length of the sealing member (cover glass 64) that seals the light emitting portion. For this reason, it becomes possible to provide the alignment marks 87a and 87b on the outer side of the sealing portion, and it is possible to detect misalignment without using the sealing portion. Therefore, the positional deviation detection process can be simplified.

  8-15 is explanatory drawing which shows the example of the position shift detection of the glass substrate by an alignment mark. In the example of FIG. 8, the position of the alignment mark 87a is formed so as to be parallel to the main scanning direction of the rod lens array and to the position of at least two outer tangents (outer tangents) of the rod lens 84. For this reason, the alignment mark 87a is the center line C.D. of the rod lens array. It is formed in parallel with L and can detect the positional deviation from the light emitting unit with high accuracy. Further, it is possible to detect a positional deviation only in the sub-scanning direction with respect to the rod lens array, and another reference can be used in the main scanning direction. This alignment mark 87 a is formed on one end of the glass substrate 62.

  In the example of FIG. 9, the position of the alignment mark 87x is formed at a position matching the tangent line of at least two outer circumferences on the lower side of the rod lens 84 arranged in two rows. The positions of the alignment marks 87y are formed according to the positions of at least two outer peripheral tangents on the upper side of the rod lenses 84 arranged in two rows. As described above, the positions of the alignment marks 87x and 87y are formed in accordance with the positions of at least two outer peripheral tangent lines on the upper and lower sides of the rod lenses 84 arranged in two rows. For this reason, even when there is variation in the diameter of the rod lens, it is possible to accurately detect the positional deviation from the light emitting unit. The alignment marks 87x and 87y are formed on one end or both ends of the glass substrate 62.

  In the example of FIG. 10, alignment marks 87 a and 87 b are formed on both ends of the glass substrate 62. The positions of the alignment marks are formed in accordance with the positions of at least two circumscribed lines of the rod lens 84 as described with reference to FIG. In the example of FIG. 10, since the alignment marks are formed at both ends of the glass substrate 62, the accuracy of the positional deviation detection is improved as compared with the configuration of FIG. Further, even when the length of the glass substrate 62 in the main scanning direction is increased, it is possible to detect the positional deviation in the sub scanning direction between the light emitting units arranged on the glass substrate 62 and the rod lens array without any error.

  In the example of FIG. 11, the alignment marks are formed at three locations 87 u and 87 w at both ends of the glass substrate 62 and 87 v at the center. The positions of the alignment marks are formed in accordance with the positions of at least two circumscribed lines on the upper side of the rod lenses 84 arranged in two rows. As described above, since the alignment marks are formed at both ends and the center of the glass substrate 62, even if the rod lens array is deformed due to an error during manufacturing, the position of the light emitting unit is not shifted without reducing accuracy. Detection can be performed.

  In the example of FIG. 12, the alignment marks 87 a and 87 b are provided at both ends of the glass substrate 62. However, the alignment marks 87 a and 87 b are particularly limited to be provided outside the image forming region R. As described above, since the alignment mark for detecting misalignment is provided outside the image forming region R, it is possible to form an image without being disturbed by the alignment mark. For this reason, image quality can be improved.

  In the example of FIG. 13, the alignment marks 87 c and 87 d are provided on both sides of the glass substrate 62, but the installation location is limited to the image forming region R. In this case, a space for forming alignment marks on both ends of the glass substrate 62 is not necessary, and thus the length of the glass substrate 62 in the main scanning direction can be shortened.

  In the example of FIG. 14, the alignment mark 87 e is formed in the same size as the outer periphery of the rod lens 84 and is provided at the end of the glass substrate 62. For this reason, the positional deviation between the alignment mark 87e and the rod lens 84 can be determined by observing the position where they overlap. Therefore, the positional deviation detection process is easy, and as a result, the center line C.D. The positional deviation from L can be detected with high accuracy. In addition, it is possible to detect the displacement of the rod lens array in both the main scanning direction and the sub-scanning direction. The alignment mark can be formed on one end or both ends of the glass substrate 62.

  In the example of FIG. 15, two alignment marks 87 e and 87 f are formed in the same size as the outer shape of the rod lens 84. For this reason, it is easy to detect misalignment between the alignment marks 87e and 87f and the rod lens 84, and the accuracy is improved. This alignment mark is not limited to two, and a plurality of alignment marks can be provided. An alignment mark having the same size as the outer shape of the rod lens 84 can be formed on one end or both ends of the glass substrate 62. Furthermore, as described with reference to FIG. 11, the alignment marks may be provided at both ends and the center of the glass substrate 62.

  The positional deviation between the light emitting unit 63 and the rod lens 84 can be detected by a module (component) formed on the glass substrate in addition to the detection of the alignment mark. Next, the positional deviation detection by such a module will be described. FIG. 16 is a plan view showing a glass substrate 62 used in the line head of the present invention. A light emitting unit 63 using an organic EL element is formed on the glass substrate 62, and each light emitting unit 63 is connected to a driving circuit 88 formed of a TFT or the like by a lead wire 92. At both ends of the glass substrate 62, a misalignment detection module, in this example, a wiring 93 connected to the drive circuit 88 is formed. The wiring 93 is performed in the same process as the formation of the light emission pattern of the light emitting unit 63. For this reason, the relative accuracy between the light emitting portion 63 and the wiring 93 can be increased.

  The wiring 93 is connected to the center line C.D. of the rod lens array. It is formed in parallel with L and can detect the positional deviation from the light emitting unit with high accuracy. Further, it is possible to detect a positional deviation only in the sub-scanning direction with respect to the rod lens array, and another reference can be used in the main scanning direction. The wiring 93 is formed at both ends of the glass substrate 62. However, as a module for detecting misalignment, the wiring 93 formed at one end or both ends of the glass substrate 62 can be used.

  FIG. 17 is an explanatory diagram showing a modification of FIG. In the example of FIG. 17, the wiring 93 c that matches the center line 63 </ b> L of the rod lens 84 is provided in the positioning wiring 93. As described above, since the wiring 93c that coincides with the center line 63L of the rod lens 84 is provided, the position shift detection process can be performed with high accuracy.

  FIG. 18 is a plan view showing an example of position adjustment of the line head (image writing means) 23. Screw fixing holes 68a and 68b are provided at both ends of the base 89 of the line head 23 to fix the case 50 on the image forming apparatus main body side. Positioning wirings 93a and 93b are formed at both ends of the glass substrate 62 as described above. The rod lenses 84 are arranged in two rows.

  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 CCD camera 90 described with reference to FIG. 12B observes the wirings 93a and 93b, which are modules for detecting misalignment, and moves the glass substrate 62 in the sub-scanning direction while adjusting with the adjusting screws 86a and 86b. Then, positioning with the center line of the rod lens array is performed. At this time, the amount of positional deviation between the light emitting unit 63 and the center line of the rod lens array is detected by the CCD camera 90, and data for performing light amount correction is acquired. In this case, the position of the glass substrate 62 as shown in FIG. 18 is not adjusted, and the light amount is corrected by electrical means by controlling the voltage or current of the light emitting unit as will be described later.

  As described above, in the embodiment shown in FIG. 18, a rod lens array having a small mounting error with respect to the line head 23 in which a plurality of organic EL elements that can be manufactured with good linearity in the process are arranged to form the light emitting unit 63. As a reference, misalignment detection is performed using the wirings 93a and 93b. Therefore, the light emitting unit 63 and the rod lens array can be positioned with high accuracy, and the line head can be installed so that the light amount is uniform and the spot diameter is uniform.

  In the embodiment of the present invention, the detection of the positional deviation between the rod lens array and the glass substrate 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 lens array and the wiring 93a. , 93b. 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.

  In the example of FIG. 18, the length of the rod lens array in the main scanning direction is longer than the length of the sealing member (cover glass 64) that seals the light emitting portion as described above. For this reason, it is possible to use a module for detecting misalignment, in this example, the wiring 93 provided outside the sealing portion, and it is possible to detect misalignment without using the sealing portion. Therefore, the positional deviation detection process of the line head can be simplified.

  19-22 is explanatory drawing which shows the example of the position shift detection of the glass substrate by a module. In the example of FIG. 19, the cathode 79 of the organic EL element described in FIG. 28 is used as a module for detecting displacement. Also in the example of FIG. 19, the cathode 79 is performed in the same process as the formation of the light emission pattern of the light emitting unit 63. For this reason, the relative accuracy between the light emitting portion 63 and the wiring 93 can be increased.

  The cathode 79 is not limited to the portion formed at the end portion of the glass substrate, but a portion in the image forming region at the center may be used for positioning. In this case, since there is no restriction on the position where the module for detecting misalignment is installed, the degree of freedom in installing the module can be increased. Furthermore, the part formed in the position of the both ends and center part of the glass substrate 62 of the cathode 79 can also be made into the module for alignment. In this case, even when the rod lens array is deformed due to an error during manufacture, it is possible to detect the positional deviation of the light emitting unit without reducing accuracy.

  In the example of FIG. 20, as described with reference to FIG. 28, the partition wall 75 used in forming the organic EL element is used as a module for detecting misalignment. In the example of FIG. 20, since the existing partition is used for the line head, it is not necessary to provide a new part for detecting the displacement, and the cost can be reduced. The partition walls 75 are formed at both ends of the glass substrate 62. However, as the displacement detection module, the partition walls 75 formed at one end or both ends of the glass substrate 62 can be used. Further, as in the cathode 79 of FIG. 19, the partition wall 75 may also use a portion in the central image forming area for detecting misalignment. Note that the partition walls 75 formed at both ends and the center of the glass substrate 62 can be used as a module for detecting misalignment.

  In the example of FIG. 21, the IC chip 94 connected to the wiring 93 is used as a module for detecting misalignment. The IC chip 94 may be provided at both ends of the glass substrate 62. In the example of FIG. 21, such an IC chip 94 provided at one or both ends of the glass substrate 62 is used as a module for detecting misalignment. For this reason, it is not necessary to newly provide a means for detecting misalignment. In the example of FIG. 21, the wiring 93 can be used as a module for detecting misalignment together with the IC chip 94. In this way, by setting a plurality of modules as modules for detecting displacement, it is possible to improve the accuracy of detecting the displacement of the glass substrate.

  In the example of FIG. 22, the positioning marks 96 a and 96 b of the flexible substrate 95 are also used as a module for detecting the displacement of the glass substrate 62. The positioning marks 97a and 97b provided on the flexible substrate 95 are overlapped with the positioning marks 96a and 96b provided on the end of the glass substrate 62, and both are joined. The positioning marks of the flexible substrate 95 are provided at both ends of the glass substrate 62, and the marks provided at one end of the glass substrate 62 or the marks at both ends are used as a module for detecting misalignment of the glass substrate 62. . In this example, since the positioning marks 96a and 96b of the flexible substrate 95 are also used as a module for detecting the displacement of the glass substrate 62, the alignment with the rod lens array can be performed rationally.

  In each of the above-described embodiments, when the misalignment detection modules provided at both ends of the glass substrate 62 are used, the positioning accuracy is improved as compared with the configuration using the module at one end. Further, even when the length of the glass substrate 62 in the main scanning direction is increased, it is possible to detect the positional deviation in the sub scanning direction between the light emitting units arranged on the glass substrate 62 and the rod lens array without any error.

  In the examples of FIGS. 16 to 22, a module provided outside the image forming area is used for detecting misalignment. As described above, when the module for detecting misregistration is provided outside the image forming area, it is possible to form an image without being disturbed by the module. For this reason, image quality can be improved.

  FIG. 1 is a block diagram illustrating a schematic configuration of the image forming apparatus. In FIG. 1, 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, which corresponds to the numeral 88 in FIG. Reference numeral 106 denotes a light emitting unit in which a plurality of light emitting elements are arranged in one line (main scanning direction), which corresponds to the numeral 63 in FIG. 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 light emitting unit 106 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 the misregistration amount characteristic detected by the misregistration detection unit 102 from the memory 103 and calculates a correction light amount with respect to the reference light amount. Based on the calculation result, a signal is sent to the drive circuit 104, and the applied voltage or drive current of the light emitting unit 106 is controlled to correct the light amount.

  FIG. 2 is a cross-sectional view showing a specific example of misregistration detection. FIG. 2 corresponds to FIG. In FIG. 2, 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. The center line of the rod lens is C.I. When L is assumed, the formation position of the light emitting portion 63 with respect to the glass substrate 62 is shifted by ΔL from the center line. This displacement is detected by the CCD 90. La is the optical path of the CCD 90. The amount of misalignment detected by the CCD 90 is stored in the memory 103 in FIG.

  FIG. 3 is a flowchart showing the processing procedure of the present invention. In FIG. 3, the processing program is started (step S1), and a positional deviation between the light emitting unit and the center line of the rod lens is detected (step S2). Next, the detected positional deviation amount is stored in a memory (step S3), and conversion processing to light amount correction data is performed (step S4). The light quantity correction data is transferred to the line head (step S5), and the processing program is terminated (step S6).

  As described above, the light amount correction method and the image forming apparatus of the line head according to the present invention have been described based on several embodiments. However, the present invention is not limited to these embodiments, and various modifications are possible.

It is a block diagram which shows the control part of this invention. It is sectional drawing which shows the example of a position shift detection. It is a flowchart which shows the process sequence of this invention. It is a top view of a glass substrate. It is a top view of the example which provided the cover glass in the glass substrate. It is sectional drawing of a line head. It is a top view of the line head applied to this invention. It is explanatory drawing of the example of the position shift detection by an alignment mark. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing of the example of a position shift detection. It is explanatory drawing which shows the example of the position shift detection by a module. It is explanatory drawing which shows the example of the position shift detection by a module. It is explanatory drawing which shows the example of the position shift detection by a module. It is explanatory drawing which shows the example of the position shift detection by a module. It is explanatory drawing which shows the example of the position shift detection by a module. It is explanatory drawing which shows the example of the position shift detection by a module. It is explanatory drawing which shows the example of the position shift detection by a module. 1 is a longitudinal side view of an image forming apparatus in which a line head of the present invention is used. FIG. 24 is a partial cross-sectional view in the vicinity of the image carrier shown in FIG. 23. It is a schematic perspective view which expands and shows an image writing means. It is sectional drawing which shows the example which fixed the glass substrate. It is explanatory drawing which shows the example of positioning of a glass substrate. It is sectional drawing which shows the structural example of the light emission part vicinity. It is a vertical side view of an image forming apparatus showing another embodiment of the present 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 ... Image forming apparatus, 16 ... Intermediate transfer belt, 20 ... Image carrier, 23 ... Image writing means (line head), 61 ... Organic EL element array, 62 ... Glass substrate 63... Light emitting part 64. Cover glass 65. Graded index rod lens array (SLA) 84. Graded index rod lens 85 a, 85 b Plate spring 86a, 86b ... adjustment screw, 87 ... alignment mark, 88 ... drive circuit, 90 ... CCD, 93 ... wiring, 94 ... IC chip, 95 ... flexible substrate, 96a, 96b ... flexible board alignment mark, 100 ... main body controller, 101 ... control unit, 102 ... misregistration detection unit, 103 ... memory, 104 ... control circuit, 105 ... Dynamic circuit, 106 ... light-emitting unit, 167 ... line head, 169 ... intermediate transfer belt.

Claims (17)

In a line head comprising a light emitting section in which a plurality of light emitting elements formed on a transparent single substrate are arranged and a lens array holding means, a positional deviation of the light emitting section is detected with reference to the position of the lens array. A line head light amount correction method comprising: a step; and a step of correcting the light amount of the light emitting unit based on the detected positional deviation. The method of correcting a light amount of a line head according to claim 1, wherein the detection of the positional deviation is performed from the side opposite to the irradiation side of the output light of the transparent substrate. 3. The light amount correction of the line head according to claim 1, wherein a length of the lens array in a main scanning direction is formed longer than a length of a sealing member that seals the light emitting unit. Method. 4. The method of correcting a light amount of a line head according to claim 1, wherein the detection of the displacement is performed by means formed outside / in the image forming area. 5. The line head light quantity correction method according to claim 1, wherein a plurality of the positional deviation detection means are formed on the transparent substrate. 6. The light amount correction method for a line head according to claim 1, wherein the displacement detecting means is formed at both ends of the transparent substrate, or at both ends and the center. The method for correcting a light amount of a line head according to any one of claims 1 to 6, wherein the detection of the displacement is performed by detecting an alignment mark formed on the transparent substrate. 8. The line head light amount correction method according to claim 7, wherein the alignment mark is a tangent line parallel to a main scanning direction of the lens array and in contact with an outer shape of the lens. The line head positioning method according to claim 7, wherein the alignment mark has the same shape as the lens. 7. The line head light amount correction method according to claim 1, wherein the detection of the displacement is performed by detecting a module formed on the transparent substrate. 11. The line head light amount correction method according to claim 10, wherein the module is a wiring connected to a driving circuit of the light emitting element. 12. The line head light quantity correction method according to claim 1, wherein the positional deviation detection means is performed in the same step as the formation of the light emission pattern of the light emitting section. The light amount correction of the line head according to claim 10, wherein the module is a cathode used when forming the cathode of the light emitting unit or the light emitting element on the transparent substrate. Method. 14. The line head light amount correction method according to claim 1, wherein the light emitting element is an organic EL element. 15. An image forming apparatus comprising a charging unit, a line head positioned by the method according to claim 1, a developing unit, and a transfer unit. An image forming apparatus, wherein at least two stations are provided, and a transfer medium passes through each station to form an image in a tandem manner. An image carrier configured to carry an electrostatic latent image, a rotary developing unit, and a line head positioned by the method according to claim 1, wherein the rotary developing unit includes: A plurality of toner cartridges carrying toner on their surfaces and rotating in a predetermined rotational direction to sequentially convey different color toners to a position facing the image carrier, A developing bias is applied between the rotary developing unit and the toner is moved from the rotary developing unit to the image carrier, whereby the electrostatic latent image is visualized to form a toner image. An image forming apparatus. The image forming apparatus according to claim 15, further comprising an intermediate transfer member.

Images