JP2007086466A - Photoreceptor cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoreceptor cartridge and an image forming apparatus where skew correction is easily performed. <P>SOLUTION: Reference pins 69a and 69b being the reference of a writing direction are provided at both ends of a line head 101. The photoreceptor cartridge 90 has: a positioning part 91 to which the reference pin 69b of the line head 101 is directly connected at its one end; and an auxiliary pin 93 and a positioning pin 92 for fitting and positioning the photoreceptor cartridge 90 in an image forming apparatus main body, and a bearing part supporting the rotary shaft 20a of a photoreceptor 20 at positions corresponding to both ends of the photoreceptor 20. The positioning part 91 is adjusted in a subscanning direction so that images written on the photoreceptor 20 by the line head 101 can be parallel with each other in a main scanning direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photoreceptor cartridge and an image forming apparatus.

  In general, an electrophotographic toner image forming unit includes a photosensitive member as an image bearing member having a photosensitive layer on an outer peripheral surface, a charging unit that uniformly charges the outer peripheral surface of the photosensitive member, and a uniform charging unit using the charging unit. An exposure unit that selectively exposes the outer peripheral surface charged to form an electrostatic latent image, and a toner as a developer is applied to the electrostatic latent image formed by the exposure unit to form a visible image ( Developing means for forming a toner image).

  As a tandem type image forming apparatus for forming a color image, a plurality (for example, four) of toner image forming means as described above are arranged on the intermediate transfer belt. The toner image on the photosensitive member by the single color toner image forming unit is sequentially transferred to the intermediate transfer belt, and the toner images of a plurality of colors (for example, yellow, cyan, magenta, and black (black)) are superimposed on the intermediate transfer belt. There is an intermediate transfer belt type that obtains a color image on an intermediate transfer belt.

  In the tandem type image forming apparatus as described above, a line head using an LED or an organic EL element as a light emitting element is known. When a detachable process cartridge is employed for a line head having such a configuration, it is difficult to position the photosensitive member shaft directly on the main body when the attaching / detaching direction is parallel to the axial direction of the photosensitive member. .

  When such a detachable process cartridge structure is employed, the parallelism of the axes of the photoconductors varies for each color cartridge. In a tandem color image forming apparatus, even if the scanning lines for writing are exactly parallel, if the axis of the photoconductor is inclined, the image written on the photoconductor is developed and transferred to the intermediate transfer medium. At a certain point in time, they are not parallel, i.e., skew occurs, resulting in color misregistration.

  Further, due to variations in the reference position for attaching the cartridge to the main body, an error is caused in the parallelism of each color cartridge. Due to such an error in parallelism, the parallelism of the photosensitive member attached to the cartridge is lost, and a skew occurs as described above. For this reason, since color misregistration occurs and image quality deteriorates, a measure for preventing skew is necessary.

  However, in a tandem color image forming apparatus using a line head, it is very difficult to keep the scanning lines transferred to the intermediate transfer medium parallel only by improving the mechanical accuracy of each part. In order to cope with such a problem, Patent Document 1 discloses a mechanism for adjusting the translational movement of the line head in the three-axis direction and the rotational movement about the three axes.

  Patent Document 2 discloses a method of electrically correcting the skew of each color by performing line head writing in several times and sequentially shifting the writing timing in a tandem color printer. Yes. Further, Patent Document 3 discloses a mechanism for adjusting the photosensitive member axis in a three-color or four-color integrated cartridge.

  In Patent Document 4, both ends of the line head are attached to the main body via a holding member provided corresponding to the line head, and one of the holding members can be moved in the sub-scanning direction. It describes that (skew) can be adjusted. In Patent Document 5, a line head is positioned on the photosensitive member holding member in the process cartridge, and a mechanism for adjusting the photosensitive member holding member in the sub-scanning direction is provided, and the line head and the photosensitive member are simultaneously sub-scanned. It is described that the angle of the direction can be adjusted.

Japanese Patent Laid-Open No. 04-166824 Japanese Patent Laid-Open No. 10-73980 Japanese Patent Laid-Open No. 2003-15378 JP 11-194573 A JP 09-174919 A

  Even if the mounting angle of the line head is precisely adjusted as in Patent Document 1 and Patent Document 4, if the rotation shafts of the photoreceptors housed in the process cartridge are individually tilted, the image inclinations of the respective colors are not the same. There was a problem that color misregistration occurred. Further, in Patent Document 3, four photoconductors for each color are attached to one photoconductor cartridge. Therefore, once the inclination of the photoconductor axis is adjusted, it does not relatively deviate. However, there arises a problem that an image is inclined due to a relative inclination with respect to the line head for writing.

  Further, as in Patent Document 2, it is possible to correct the inclination by skewing the writing timing electrically in accordance with the pixel position in the main scanning direction (skew correction control), but the correction is made based only on the initial value. In this case, since the initial value changes when the process cartridge or other members are replaced, it is necessary to correct the correction value. In order to avoid this, sensors are provided on both sides of the intermediate transfer medium, and the image position (tilt) of each color is detected and automatically corrected. However, sensors for this purpose are required at least at two locations on both ends, which increases costs.

  In the first place, in order to perform such correction control, a circuit of a considerable scale is required, such as changing the transfer order of image data, and there is a problem that the cost is excessive. Further, even when correction is performed, there is a problem that if the variation in image tilt (skew) is large, the correction control range increases and the amount of temporary storage memory for correction increases.

  In Patent Document 5, the line head is positioned at both ends of the photosensitive member supporting member in the cartridge, and one of the photosensitive member supporting members can be adjusted in the sub-scanning direction, thereby adjusting the inclination of the image of each color. is doing. However, even with this method, it is obvious that the parallelism of the images of the four colors cannot be ensured unless the parallelism of the shaft of the photosensitive member is secured when the cartridge is attached to the main body.

  Further, in any of the prior arts of Patent Documents 1, 3, 4, and 5, it is not clear what value or state is specifically measured to adjust the inclination of the image.

  The present invention has been made in view of such various problems of the prior art, and an object of the present invention is to provide a photosensitive cartridge and an image forming apparatus that are configured to easily perform skew adjustment. .

  In the photoconductor cartridge of the present invention that achieves the above object, the positioning member serving as a reference in the writing direction provided at both ends of the line head in the main scanning direction corresponds to the line head positioning portion to be directly inserted and both ends of the photoconductor A cartridge positioning portion for fitting and positioning the cartridge to the image forming apparatus main body at a position to be positioned, and a bearing portion for supporting the rotating shaft of the photoconductor, and an image written on the photoconductor by the line head The line head positioning unit is moved in the sub-scanning direction and adjusted in position so as to be parallel to each other in the main scanning direction on the intermediate transfer medium. To do. According to this configuration, by adjusting the positioning unit of the line head provided in the process cartridge, it is not necessary to perform skew correction control in which the writing timing in the sub-scanning direction is sequentially shifted in the main scanning direction. Simplification of the control circuit of the writing unit and cost reduction are facilitated.

The photoreceptor cartridge of the present invention is provided with a plurality of the line heads corresponding to the respective colors, and a plurality of cartridges for fixing the photoreceptors corresponding to the respective line heads. The line head positioning unit for each line head; It is characterized by having the cartridge positioning part for each cartridge and the bearing part for supporting the rotating shaft of each photoconductor. In the formation of a color image, in order to automatically correct the skew, at least two sensors for detecting the color misregistration of each color are required at both right and left ends of the image. However, according to this configuration, since automatic skew correction is not performed, it is only necessary to provide a sensor at one representative location such as the central portion, and further simplification of the structure and cost reduction are possible. .

  In the photoreceptor cartridge of the present invention, the positioning members at both ends of the line head are cylindrical pins, the line head positioning portion provided in the cartridge is a hole corresponding to the pin, and the line What is positioned at one end of the head positioning portion is formed on a member that can move in the sub-scanning direction. According to this configuration, the position adjustment in the sub-scanning direction can be performed with a simple configuration of the cylindrical pin and the hole engaged therewith.

  Further, the photoreceptor cartridge of the present invention is provided with a positioning member serving as a reference in the writing direction at both ends of the line head, and when the line head is manufactured, the reference line defined by the positioning member is The substrate is configured to be movable so that the rows formed by the imaging spots from the light emitting portions provided on the substrate of the line head are parallel to each other. According to this configuration, when the line head is assembled, the row of spots formed by the light source, that is, the scanning line is adjusted according to the reference of the positioning member. do not do. For this reason, readjustment becomes unnecessary.

  In the photoreceptor cartridge of the present invention, the light emitting element is an organic EL element provided with a number corresponding to a writing width of the substrate in the main scanning direction. Since the organic EL element can be controlled statically, the control system of the line head can be simplified.

  In the photoreceptor cartridge of the present invention, the substrate is a glass substrate. According to this configuration, the image carrier can be irradiated without impairing the light amount of the light emitting element.

  The photoreceptor cartridge of the present invention is characterized in that a plurality of LED array chips provided with a plurality of LED light emitting portions are mounted on the substrate in a line shape in the main scanning direction. According to this configuration, skew adjustment can be simply performed in a line head using LEDs as light emitting elements.

  According to another aspect of the present invention, there is provided a photosensitive cartridge including a detection unit that detects a positional deviation amount of the line head in the sub-scanning direction, a storage unit that stores the positional deviation amount, and a control that corrects the positional deviation in the light emitting element. And a control means for outputting a signal. According to this configuration, since the inclination of the scanning line due to the accuracy inside the line head is very small, there is an advantage that the skew correction control range becomes very small and the memory required for the skew correction can be reduced.

An image forming apparatus of the present invention includes a plurality of image carriers that record an image on an outer peripheral surface of a cylindrical surface that rotates about a rotation axis, and a plurality of photoreceptor cartridges that respectively hold the plurality of image carriers.
A plurality of charging means disposed around each of the image carriers, and a plurality of pixels that perform optical writing simultaneously on pixels arranged in a line corresponding to each of the plurality of image carriers described above. At least two or more image forming stations provided with image forming units each including a line head, a developing unit, and a transfer unit that transfers and superimposes a plurality of images formed on the plurality of image carriers are provided. ,
An image is formed by a tandem method when the transfer medium passes through each station. According to this configuration, skew adjustment can be easily performed in the tandem image forming apparatus.

  In addition, the image forming apparatus of the present invention includes an intermediate transfer member. Therefore, skew adjustment can be easily performed in an image forming apparatus including an intermediate transfer member.

  As described above, by adjusting the positioning unit of the line head provided in the process cartridge, it is not necessary to perform skew correction control in which the writing timing in the sub-scanning direction is sequentially shifted in the main scanning direction. This simplifies the control circuit and reduces the cost. Further, in order to automatically correct the skew, at least two sensors for detecting the color misregistration of each color are required at both the left and right ends of the image. Since the present invention does not perform such automatic skew correction, it is only necessary to provide a sensor at one representative location such as the central portion, so that the structure can be further simplified and the cost can be reduced.

  Also in the present invention, when the accuracy is insufficient, the skew correction control is unavoidable, but even in that case, the skew of the scanning line due to the accuracy inside the head is very small. The range becomes very small and less memory is required for correction. Furthermore, since both the angular error of the rotating shaft of the photosensitive member relative to the cartridge and the mounting angle error of the line head can be absorbed by adjustment at one place, adjustment is easy. By individually adjusting the process cartridges in this way, the accuracy of image tilt can be kept good even when the worn process cartridges are replaced.

  Note that, when the line head is assembled, the row of spots formed by the light source, that is, the scanning line is adjusted according to the reference of the positioning member, so that the inclination (skew) of the image hardly changes even if the line head is replaced. For this reason, readjustment becomes unnecessary.

  In the embodiment of the present invention, a tandem color printer that exposes four photoconductors with four line heads, simultaneously forms four color images, and transfers them onto one endless intermediate transfer belt (intermediate transfer medium). The target is a line head used in (image forming apparatus). FIG. 10 is a longitudinal side view showing an example of a tandem image forming apparatus using an organic EL element as a light emitting element. This image forming apparatus includes four organic EL element array exposure heads 101K, 101C, 101M, and 101Y having a similar configuration, and four corresponding photosensitive drums (image carriers) 41K, 41C, Arranged at the exposure positions 41M and 41Y, respectively, is configured as a tandem image forming apparatus.

  As shown in FIG. 10, this image forming apparatus is provided with a drive roller 51x, a driven roller 52, and a tension roller 53. The tension roller 53 applies tension to the image forming apparatus and stretches it in the direction indicated by the arrow (counterclockwise). ) Is circulated to the intermediate transfer belt (intermediate transfer medium) 50x. Photoconductors 41K, 41C, 41M, and 41Y having photosensitive layers are arranged on the outer peripheral surface as four image carriers arranged at predetermined intervals with respect to the intermediate transfer belt 50x.

  K, C, M, and Y added after the reference sign mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are black, cyan, magenta, and yellow, respectively. The same applies to other members. The photoreceptors 41K, 41C, 41M, and 41Y are rotationally driven in the direction indicated by the arrow (clockwise) in synchronization with the driving of the intermediate transfer belt 50x. Around each photoconductor 41 (K, C, M, Y), charging means (corona charger) 42 (K) for uniformly charging the outer peripheral surface of the photoconductor 41 (K, C, M, Y), respectively. , C, M, Y) and the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y) are synchronized with the rotation of the photoconductor 41 (K, C, M, Y). The organic EL element array exposure head (line head) 101 (K, C, M, Y) as described above according to the present invention is provided.

  Further, a developing device 44 (K) which applies toner as a developer to the electrostatic latent image formed by the organic EL element exposure head 101 (K, C, M, Y) to form a visible image (toner image). , C, M, Y) and a primary transfer roller 45 as transfer means for sequentially transferring the toner image developed by the developing device 44 (K, C, M, Y) to the intermediate transfer belt 50 as a primary transfer target. (K, C, M, Y) and a cleaning device 46 (K, C, Y) as a cleaning unit for removing the toner remaining on the surface of the photoreceptor 41 (K, C, M, Y) after being transferred. M, Y).

  Here, in each organic EL element array exposure head 101 (K, C, M, Y), the array direction of the organic EL element array exposure head 101 (K, C, M, Y) is the photosensitive drum 41 (K, C). , M, Y) along the bus. Then, the emission energy peak wavelength of each organic EL element array exposure head 101 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are set so as to substantially match. Has been.

  The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer, and the one-component developer is conveyed to the developing roller by a supply roller, for example, and adheres to the surface of the developing roller. The film thickness of the developed developer is regulated by a regulating blade, and the developing roller is brought into contact with or increased in thickness by the photosensitive body 41 (K, C, M, Y), whereby the photosensitive body 41 (K, C, M, Y). The toner is developed as a toner image by attaching a developer according to the potential level.

  The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). The toner image that is sequentially primary-transferred onto the transfer belt 50x and sequentially superposed on the intermediate transfer belt 50x to become a full color is secondarily transferred to the recording medium P such as paper by the secondary transfer roller 66x, and serves as a fixing unit. The toner is fixed on the recording medium P by passing through the fixing roller pair 61x, and is discharged onto a paper discharge tray 68x formed in the upper part of the apparatus by the paper discharge roller pair 62x.

  In FIG. 10, 63x is a paper feeding cassette in which a large number of recording media P are stacked and held, 64x is a pickup roller for feeding the recording media P one by one from the paper feeding cassette 63x, and 65x is a secondary transfer roller. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion 66x, 66x is a secondary transfer roller as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 50x, 67x Is a cleaning blade as a cleaning means for removing toner remaining on the surface of the intermediate transfer belt 50x after the secondary transfer.

  As shown in FIG. 10, in the image forming apparatus of the present invention, each color developer (toner) is attached to the electrostatic latent image written by the four line heads by the developing unit. The four-color toner images are superimposed and transferred. The process cartridge is a consumable item and is configured to be detachable by the user.

  FIG. 11 is a schematic perspective view showing the image writing unit 101 in an enlarged manner. In FIG. 11, the organic EL element array 61 is held in a long housing 60. The positioning pins 69 provided at both ends of the long housing 60 are fitted into the opposing positioning holes of the case, and the fixing screws are screwed into the screw holes of the case through the screw insertion holes 68 provided at both ends of the long housing 60. By fixing, each image writing means 23 is fixed at a predetermined position.

  The image writing unit 101 mounts a light emitting element (organic EL element) 63 of an organic EL element array 61 on a glass substrate 62, and is driven by a drive circuit 71 formed on the same glass substrate 62. A gradient index rod lens array (SLA) 65 constitutes an imaging optical system, and has a gradient index rod lens 84 arranged in front of the light emitting element 63. As the rod lens array 65, the “selfoc lens array” (abbreviated as SLA, trade name of Nippon Sheet Glass Co., Ltd.) as described above is frequently used.

  The light beam emitted from the organic EL element array 61 is formed on the surface to be scanned by the SLA 65 as an equal magnification erect image. Thus, since the organic EL elements 63 are arranged on the glass substrate 62, the image carrier can be irradiated without impairing the light amount of the light emitting elements. Further, since the organic EL element can be controlled statically, the control system of the line head can be simplified.

  Reference numeral 66 denotes a cover. The housing 60 covers the periphery of the glass substrate 62, and the side facing the image carrier 41 shown in FIG. In this way, light is emitted from the gradient index rod lens 84 to the image carrier 41 shown in FIG. A light-absorbing member (paint) is provided on the surface of the housing 60 that faces the end surface of the glass substrate 62. The housing 60 functions as a holder for fixing the SLA 65 at a position corresponding to the glass substrate 62. The number of organic EL elements 63 corresponding to the writing width of the glass substrate 62 in the main scanning direction is provided.

In each photoconductor, the transfer portion to the intermediate transfer medium and the writing portion by the line head are at positions that are substantially 180 ° opposite to each other. Accordingly, when the axis of the photosensitive member is inclined in the belt in-plane direction of the intermediate transfer belt, the inclination of the image is doubled.
The position of the photoconductor relative to the intermediate transfer medium may be arranged on the upper side or on the lower side. In any case, as described above, the transfer portion and the writing portion to the intermediate transfer medium are placed at positions that are substantially 180 ° opposite to the rotation of the photosensitive member. An arrangement in which the intermediate transfer medium is stretched in the vertical direction and four photoconductors are arranged in the vertical direction is also conceivable.

  In the image forming apparatus of the present invention, the process (photoreceptor) cartridge is a consumable item and is configured to be detachable by the user for replacement or inspection. Although there are devices in which the insertion / extraction direction for attaching / detaching the process cartridge to / from the main body is the vertical direction of the image forming apparatus, it is difficult to insert / extract when the photosensitive cartridge is arranged below the intermediate transfer medium. Even if not, a large space is required on the image forming apparatus.

  For this reason, a configuration in which the photoreceptor cartridge is inserted and removed in the axial direction of the photoreceptor is useful. However, in such a configuration, there is a problem that it is difficult to directly position both ends of the photosensitive member shaft on the printer body. Accordingly, the photoconductor is necessarily supported by the cartridge and then indirectly attached to the printer body.

  FIG. 4 is a schematic explanatory diagram showing an example in which the photosensitive cartridge according to the embodiment of the present invention is attached to the image forming apparatus main body. In FIG. 4, the photoconductor 20 is fixed to a photoconductor cartridge 90. A cartridge positioning pin 92 is provided at one end of the photosensitive cartridge 90. Further, an auxiliary pin (not shown) is provided at the other end of the photosensitive cartridge 90 (see FIGS. 1 and 2). The photosensitive cartridge 90 is inserted into the space 2 i of the main body case 2 from the opening 2 d of the main body case 2. At this time, the auxiliary pin is advanced in the arrow direction Ya and the cartridge positioning pin 92 is advanced in the arrow direction Yb, and is engaged with a hole in the side plate provided in the main body case 2 as described later. 2 h is a cover of the main body case 2.

  FIG. 2 is an explanatory diagram showing an example of positioning the line head 101 on the photosensitive member cartridge 90 according to the embodiment of the present invention. In FIG. 2, the line head 101 is provided with the SLA 65 and reference pins 69a and 69b at both ends in the main scanning direction. The light emitting element is not shown. The photoconductor 20 is fixed to the photoconductor cartridge 90. One end of the photoconductor 20 protrudes from the tip of the photoconductor shaft 20 a and is engaged with a hole in a side plate provided in the main body case 2. Although not shown, the photosensitive member cartridge 90 is provided with a bearing portion for the photosensitive member shaft 20a.

  Further, holes 94a and 95a into which the reference pins 69a and 69b of the line head are inserted are formed on the surface of the photosensitive cartridge 90. As will be described with reference to FIG. 1, one of the holes 94 a and 95 a is provided in the positioning member of the line head 101. By moving this positioning member, the line head can be moved in the sub-scanning direction. The cartridge positioning pin 92 is provided at one end of the photosensitive cartridge 90.

  The line head 101 is provided with reference pins 69a and 69b at both ends thereof, and the light beam emitted from the array-like light emitting portion is a lens such as a SELFOC lens array (SLA = Nippon Sheet Glass Co., Ltd.). An image column formed by the array 65, that is, a scanning line is assembled so as to be parallel to the reference pins 69a and 69b.

  On the photosensitive cartridge 90 side, holes 94a and 95a that fit into the reference pins 69a and 69b are provided, and the line head 101 is positioned. Note that it is difficult to insert and remove the photosensitive cartridge 90 in a state where the positioning pins 69a and 69b of the line head and the holes 94a and 95a of the photosensitive cartridge 90 are fitted. It is desirable to provide a mechanism for separating the line head 101 from the photosensitive cartridge 90.

  The photosensitive cartridge 90 is positioned with respect to the main body case by the auxiliary pin 93 and the photosensitive shaft 20a on the front end side in the insertion direction, and by the positioning pin 92 on the rear end side in the insertion direction. The parallelism of the reference line (line) defined by the positioning pin 92 and the auxiliary pin 93, and the line connecting the photoconductor shaft 20a and the positioning holes 94a and 95a for positioning the line head 101 is obtained. Otherwise, the parallelism of the images formed on the photoconductors 20 of the respective colors cannot be ensured.

  These three elements (the reference direction defined by the positioning pin 92 and the auxiliary pin 93, the photosensitive shaft 20a, and the line connecting the positioning holes 94a and 95a for positioning the line head 101) are all precisely processed and assembled. Adjustment is necessary because it is difficult. However, it is not necessary to be able to adjust all of the above three elements, and by adjusting any one of them, adjustment of the other two elements becomes unnecessary.

  In the embodiment of the present invention, reference holes 94a and 95a provided at positions corresponding to reference pins 69a and 69b provided at both ends of the line head 101 for positioning the line head 101 on the photosensitive cartridge 90 are provided. One of them is configured to be movable in the sub-scanning direction with respect to the photoconductor cartridge 90 main body.

  Thus, in order to adjust the photoreceptor cartridge 90 and adjust the tilt angle (skew) of the image, the dimensional accuracy of each element is measured, and the position of one element to be adjusted is calculated and adjusted. However, it is complicated to perform mechanical adjustment for all the photosensitive cartridges 90. Therefore, it is simpler and more accurate to adjust while observing the actual image shift at the transfer portion.

  Hereinafter, a configuration for adjusting the position of the photoconductor cartridge 90 will be described in detail with reference to FIG. In FIG. 1, the photosensitive member cartridge 90 is attached to the adjustment jig 51. A photosensitive member 20 (corresponding to the photosensitive members 41K, 41C, 41M, and 41Y shown in FIG. 10) is fixed to the photosensitive member cartridge 90. A photoconductor shaft 20a is provided at one end of the photoconductor 20, and rotates in the direction of arrow R. The adjustment jig 50 has a fixing hole corresponding to the photosensitive shaft 20a and the auxiliary pin 93 on the front end side of the photosensitive cartridge 90 and the positioning pin 92 of the photosensitive cartridge 90 located on the opposite end. Well established. A photoreceptor cartridge 90 whose position is to be adjusted is attached to the adjustment jig 50.

  A CCD camera 80 is provided in the vicinity of both ends of a position (lower surface in the drawing) corresponding to the transfer portion of the photoconductor cartridge 90, and an image formed on the photoconductor 20 is observed. Reference numeral 81 denotes an enlargement optical system of the CCD camera 80. Next, the line head 101 is attached to the photoreceptor cartridge 90.

  Cylindrical positioning pins 69a and 69b provided at both ends of the line head 101 are fitted into fixing holes 94 and 95 of the photosensitive cartridge. At this time, as described above, one fixing hole, in this example, the fixing hole 95 is provided in the positioning member 91 movably provided in the groove 96, and is sub-scanned with respect to the photosensitive cartridge 90. It can move in the direction (Xc). The positioning member 91 is movable even when the line head 101 is attached, and has a structure capable of screwing with a screw 97 in order to fix the position after the movement.

  In this embodiment, in order to adjust the position while viewing the images at both ends on the photosensitive member 20 with the CCD cameras 80 and 80, it is necessary to actually develop the image. When the developing unit and the charging unit are integrally provided in the photosensitive cartridge 90, they may be used as they are. However, when the developing unit and the charging unit are separate parts, a developing unit for position adjustment is used. Prepare a charging unit.

The image formed on the photoconductor 20 may be any image as long as the positional deviation in the sub-scanning direction can be compared, but a linear pattern substantially parallel to the photoconductor axis 20a at a constant interval is preferable. The thickness and length of this pattern may be appropriately selected according to the characteristics of the CCD camera and sensor used for detection.
The image of the line taken by the CCD camera is displayed on the monitor, and the head positioning member is moved so that it matches the index position displayed on the monitor, and the screw is tightened. Fix the adjustment position.

  When using the CCD cameras 80 and 80, if the measurement is difficult due to the rotation of the photosensitive member 20, the image formed by the rotation is stopped when the measurement is difficult. Also good. In this case, since the rotation / stop operation is repeated in the adjustment process, workability is slightly inferior. Further, since the normal CCD camera 80 has a low image magnification and is difficult to adjust, it is desirable to use the magnifying optical system 81.

  Note that the index position serving as a reference for the images taken by the CCD cameras 80 and 80 is calibrated by photographing a target provided in a jig cartridge inserted instead of the photosensitive cartridge 90 and recording the position. In the line head used for position adjustment, the parallelism between the reference line formed by the line connecting the positioning pins 69a and 69b provided at both ends of the line head and the writing spot row (that is, the scanning line) is ensured. Need to be. Therefore, even if a line head adjusted with very high accuracy is used, or a light emitting element of the line head is made to emit light, and its imaging position is measured with reference to a positioning pin, a thing with good parallelism is selected. Good.

  In this way, by adjusting the position using the CCD cameras 80 and 80, even if the direction of the photosensitive member axis 20a is not parallel to the reference mounting direction of the photosensitive member cartridge 90, the line head 101 is attached in a form that compensates for it. The angle is adjusted. For this reason, even when the photosensitive member cartridge is replaced, the parallelism of the image is kept constant.

  In the above embodiment, the image on the photoconductor 20 is observed with the CCD cameras 80 and 80, but a line image sensor may be used. Alternatively, a photosensor that can observe the amount of light in a narrow spot-like area can detect the pattern as the strength of the signal. Compare the changes over time with an oscilloscope, etc. Can be measured. In the formation of a color image, in order to automatically correct the skew, at least two sensors for detecting the color misregistration of each color are required at both right and left ends of the image. However, according to this configuration, since automatic skew correction is not performed, it is only necessary to provide a sensor at one representative location such as the central portion, and further simplification of the structure and cost reduction are possible. .

  When these sensors are used, the photoconductor 20 must be rotated whenever an image on the photoconductor 20 is observed. Therefore, a stationary jig such as the CCD camera 80 cannot be used to calibrate the positions of the two sensors at both ends of the line head. Therefore, instead of the photoconductor 20, it is necessary to use a reference drum on which patterns are accurately engraved or printed on both ends.

  The configuration for positioning the line head 101 and the photosensitive cartridge 90 described above is merely an example. As another embodiment, for example, a hole may be provided in the line head 101, and a reference pin that fits into the hole may be provided in the photosensitive cartridge 90, or the hole into which the reference pin is fitted may be a V groove. In addition, the positioning region of the photoconductor cartridge 90 may be a simple plane, and the line head 101 may be pressed in a direction perpendicular to the surface.

  For the line head 101, by adjusting the inclination of the image formation spot position (scanning line) with respect to the reference pins 69a and 69b, the parallelism of the four color images does not change even if the line head 101 is replaced. . By configuring the entire printer in this way, the relative difference (skew) of the inclinations of the four color images can be made extremely small, and the amount of change in accuracy is small even when the photosensitive cartridge 90 and the line head 101 are replaced.

  By adopting the structure or the adjustment method described above, the angle error due to the three factors of the line head 101, the photoconductor 20, and the printer (image forming apparatus) main body with respect to the photoconductor cartridge 90 can be extremely reduced. On the other hand, in the main body case to which the photosensitive cartridge 90 is attached, four holes (in the case of four colors) into which the positioning pins of the photosensitive cartridge are fitted are formed in the side plates on both sides of the main body at the same time. The parallelism of the cartridge can be secured.

  FIG. 3 is an explanatory diagram illustrating a configuration of a side plate of the main body case. In FIG. 3, one side plate 2b is provided with a hole 2f into which the photoreceptor shaft 20a is inserted and a hole 2g into which the auxiliary pin 93 of the photoreceptor cartridge 90 is inserted for four colors. The other side plate 2c is provided with holes 2e into which the positioning pins 92 of the photosensitive cartridge 90 are inserted for four colors. Reference numeral 2d denotes an opening for inserting and removing the photosensitive cartridge 90.

  Next, the substrate position adjustment of the line head applied to the photoconductor cartridge in the present invention will be described. FIG. 5 is a cross-sectional view in the sub-scanning direction of the line head according to the embodiment of the present invention. In FIG. 5, a plurality of light emitting elements (organic EL elements) (not shown) are formed on the glass substrate 62. Observation with the CCD camera 80 so that the line connecting the reference pins 69a and 69b provided at both ends in the main scanning direction of the line head is parallel to the scanning line connecting the arrangement of the imaging spots by operating the organic EL element. Then, the glass substrate 62 is moved and adjusted in the arrow X direction (sub-scanning direction). Reference numeral 50 denotes a substrate holder for holding the glass substrate 62, 65 denotes an SLA, and 60 denotes a holder (corresponding to the housing in FIG. 11). When the substrate holder 50 is provided, the glass substrate 62 can be stably attached to the holder 60.

  6A and 6B are partial views of FIG. 5, where FIG. 6A is a cross-sectional view in the main scanning direction, and FIG. 6B is a plan view. Next, the positioning procedure will be described with reference to FIGS. (1) The substrate holder 50 and the glass substrate 62 are fixed with an adhesive or the like. (2) Insert the SLA 65 into the opening 60x of the holder 60, and place and fix it on the stepped portion 60y. (3) The substrate holding base 50 is inserted into the opening 60a of the holder 60, and is fixedly attached to the stepped portion 60b. At this time, there is a slight gap in the sub-scanning direction between the substrate holder 50 and the holder 60.

  (4) The glass substrate 62 is imaged through the SLA 65 by the CCD camera 80. The state of observing the glass substrate 62 from the CCD camera 80 is as shown in the plan view of FIG. (5) When the organic EL element is caused to emit light and the glass substrate 62 is imaged by the CCD camera 80, the position of the scanning line connecting the arrangement of the imaging spots and the line connecting the reference pins 69a and 69b provided at both ends of the line head A shift is observed.

  (6) The substrate holder 50 or the holder 60 is moved in the sub-scanning direction (X direction) to adjust the positional deviation, and the scanning line connecting the array of imaging spots is connected to both ends of the line head in the main scanning direction. Positioning is performed so that the lines connecting the provided reference pins 69a and 69b are parallel to each other. (7) The substrate holding table 50 is fixed to the holder 60 by an appropriate means such as an adhesive. (8) The holder 60 is attached to the case of the line head.

  Next, a specific example of the skew adjustment of the line head according to the embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a schematic exploded perspective view of the writing means (line head) 101 described in FIG. In FIG. 7, a glass substrate 62 is provided with a plurality of light emitting elements (organic EL elements) 63. The plurality of organic EL elements 63 are arranged in the main scanning direction of the glass substrate 62 to form a line head having a predetermined length. Note that the substrate holder 50 shown in FIG. 5 is not shown for simplicity. Both ends of the glass substrate 62 are moved in the directions of the arrows Za and Zb and are held by the holder 60. Both ends of the glass substrate 62 or the holder 60 are rotatable in the arrow Xa and Xb directions (sub-scanning direction).

  At both ends in the main scanning direction of the holder 60 holding the SLA 65, reference pins 69a and 69b used as a reference when adjusting the position of the line head 101 are provided. Reference numeral 84 denotes an SLA lens (rod lens). Reference numeral 80 denotes a CCD camera, which is arranged at both upper ends of the line head in the main scanning direction, and observes the scanning line when the position of the line head is adjusted in the sub scanning direction. Reference numeral 81 denotes an enlargement optical system of the CCD camera 80.

  FIG. 8 is a schematic perspective view showing a state in which the line head 101 in which the SLA 65 and the glass substrate 62 are fixed to the holder 60 of FIG. Reference numeral 86 denotes a base of the adjustment jig 85, and reference numerals 87 denote fixing portions provided on both sides of the adjustment jig in the main scanning direction, which are configured in an inverted L shape and fix the line head 101.

  Openings 88 are formed in the fixing portions 87 provided on both sides of the adjustment jig 85 in the main scanning direction, and the reference pins (positioning pins) 69a of the line head 101 shown in FIG. 69b are inserted. In this embodiment, the line head 101 is attached to the adjustment jig 85 and the glass substrate 62 and the holder 60 can be integrated to adjust the position at the same time. Therefore, it is necessary to separately adjust the position of the glass substrate 62 with respect to the holder 60. Absent.

  In the present invention, when the line head is assembled as described above, the position adjustment is performed so that the line connecting the reference pins 69a and 69b is parallel to the scanning line formed by arranging the imaging spots. Next, an example of this position adjustment will be described. The line head 101 is attached to the adjustment jig 85, the organic EL elements (reference pixels) at both ends are turned on, and the image formation position is enlarged and photographed by the CCD camera 80. The photographed image is observed on the monitor screen, and the position of the line head 101 is adjusted by moving the glass substrate 62 left and right in the sub-scanning direction so that the position of the imaged pixel becomes a predetermined position. Such position adjustment of the line head in the sub-scanning direction corresponds to the processing described with reference to FIGS.

  As described above, in the embodiment of the present invention, the position of the imaging head after passing through the rod lens array is observed and the position of the line head is adjusted. It can be done by adjusting it together. When the size of the light emitting portions of the organic EL element is larger than the pitch, the light emitting portions are arranged in a staggered pattern in two rows in the sub-scanning direction. In this case, the position adjustment is performed so that the center lines of the two rows of light emitting units are parallel to the line connecting the reference pins at both ends.

  After the position adjustment of the line head 101, the glass substrate 62 may be screwed to the holder 60, or may be bonded with a UV adhesive or the like. Note that the position adjustment by the CCD camera 80 may be performed while looking at the monitor screen, and superimpose with a scale line or the like indicating the position where the pixel imaged on the monitor screen should be adjusted. The calibration of the scale line may be performed by setting a reference target on the adjustment jig 85 instead of the line head, photographing the target with the CCD camera 80, and aligning the scale line.

  Such an adjustment jig 85 may be one in which a reference pin is attached to a glass mask with a tool microscope or the like with high accuracy, or a metal material processed with high accuracy. As described above, in the embodiment of the present invention, the line of spots formed by the light source when the line head is assembled, that is, the scanning line is adjusted according to the reference of the positioning member. (Skew) hardly changes. For this reason, readjustment becomes unnecessary.

  In the present invention, since the rod lens array is an erecting optical system, the imaging position is not shifted or curved due to the displacement or the curvature of the rod lens array in the sub-scanning direction. However, if the rod lens array is twisted, the imaging position is also shifted accordingly, and the scanning line is inclined. In the present invention, since adjustment is performed by looking at the actual image forming position, errors due to twisting of the rod lens array can be combined and absorbed by the position adjustment described above.

  The parallelism between the reference mounting surface of the rod lens array and the reference line formed by connecting the positioning pins 69a and 69b is processed with extremely high accuracy. For this reason, even if the position of the board | substrate 62 in which the light emission part was mounted is adjusted on the basis of the positioning pins 69a and 69b as mentioned above, the relative accuracy of a light emission part and a rod lens array is ensured as a result. As the light emitting element, an LED may be used instead of the organic EL element. In this case, for example, a plurality of LED array chips provided with a plurality of LED light emitting units are mounted in a line shape in the main scanning direction of the substrate.

  In the present invention, the skew correction control as described in the section of the prior art can be abolished. Alternatively, even if the skew correction control cannot be abolished, the amount of data to be shifted in the sub-scanning direction for correction is small, and the amount of memory for temporarily storing data can be small. Next, an example in which a skew correction circuit is supplementarily used in order to improve the accuracy of skew correction will be described.

  FIG. 9 is a block diagram illustrating a schematic configuration of a control unit of the skew correction unit. In FIG. 9, reference numeral 110 denotes a control unit, 102 denotes a line head misalignment detection unit, 103 denotes a memory, 104 denotes a control circuit, and 105 denotes a drive circuit. The misregistration detection unit 102 uses a photo sensor that can detect a light amount change in a narrow range so that a pattern for image misalignment measurement formed on the intermediate transfer medium can be detected.

  Reference numeral 100 denotes a main body controller. Prior to skew correction, a measurement pattern for each color is formed on the intermediate transfer medium, and the amount of positional deviation in the sub-scanning direction for each color is measured by the detection unit 102. The left-right difference of the positional deviation amount obtained in this way is the skew amount. This misregistration amount is stored in the memory 103 for each color. Such a measurement operation is appropriately performed as necessary, such as when the apparatus is shipped, when the apparatus is installed, when power is turned on, or when consumables are replaced.

  The control circuit 104 reads the data from the memory 103 and calculates a positional deviation amount of the difference. The control circuit 104 sends a signal to the drive circuit 105 to control the drive circuit 105 so as to correct the positional deviation amount, that is, to perform skew correction. When such a control unit 110 is used, since the inclination of the scanning line due to the accuracy inside the line head is very small, the skew correction control range becomes small, and the capacity of the memory 103 necessary for skew correction is reduced. There may be less.

  As described above, the photosensitive member cartridge and the image forming apparatus of the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.

It is a disassembled perspective view which shows embodiment of this invention. It is a perspective view of a line head and a photosensitive member cartridge. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing concerning this invention. It is sectional drawing of the subscanning direction of the line head concerning this invention. It is sectional drawing of the main scanning direction of the line head concerning this invention. It is explanatory drawing of the line head concerning this invention. It is explanatory drawing of the line head concerning this invention. It is a block diagram which shows embodiment of this invention. 1 is a longitudinal side view of an image forming apparatus showing an embodiment of the present invention. It is a perspective view which shows FIG. 10 partially.

Explanation of symbols

  41 (K, C, M, Y) ... photosensitive drum (image carrier), 42 (K, C, M, Y) ... charging means (corona charger), 44 (K, C, M) Y) ... developing device, 45 (K, C, M, Y) ... primary transfer roller, 50x ... intermediate transfer belt, 51 ... adjustment jig, 60 ... housing ( Holder), 61 ... organic EL element array, 62 ... glass substrate, 63 ... light emitting element (organic EL element), 65 ... gradient index rod lens array (SLA), 66x ... Secondary transfer roller, 69a, 69b ... positioning pins (reference pins), 80 ... CCD camera, 81 ... magnifying optical system, 84 ... gradient index rod lens, 90 ... photoconductor Cartridge, 91 ... positioning member, 92 ... cartridge positioning pin, 93 Auxiliary pins, 94 and 95 ... line head fixing hole, 101 ... image writer (line head), 104 ... control circuit

Claims (10)

Positioning members that serve as references in the writing direction provided at both ends of the main scanning direction of the line head are positioned by fitting the cartridge into the image forming apparatus main body at positions corresponding to the line head positioning portion to be directly inserted and both ends of the photosensitive member. And a bearing portion for supporting the rotating shaft of the photosensitive member, and images written on the photosensitive member by the line head are parallel to each other in the main scanning direction on the intermediate transfer medium. Thus, the photosensitive member cartridge is characterized in that one of the line head positioning portions located at one end is moved and adjusted in the sub-scanning direction. A plurality of line heads are provided for each color, and a plurality of cartridges are provided for fixing a photosensitive member corresponding to each line head. The line head positioning unit for each line head, the cartridge positioning unit for each cartridge, The photoconductor cartridge according to claim 1, further comprising the bearing portion that supports a rotation shaft of each photoconductor. The positioning members at both ends of the line head are cylindrical pins, the line head positioning portion provided in the cartridge is a hole corresponding to the pin, and is positioned at one end of the line head positioning portion. 3. The photosensitive member cartridge according to claim 1, wherein the photosensitive member cartridge is formed on a member movable in the sub-scanning direction. Positioning members that serve as a reference in the writing direction are provided at both ends of the line head, and at the time of manufacturing the line head, from a light emitting unit provided on the substrate of the line head with respect to a reference line defined by the positioning member 4. The photosensitive member cartridge according to claim 1, wherein the substrate is configured to be movable so that rows formed by the imaging spots are parallel to each other. 5. The organic EL element according to claim 1, wherein the light emitting element of the light emitting unit is an organic EL element provided with a number corresponding to a writing width of the substrate in a main scanning direction. Photoconductor cartridge. The photoconductor cartridge according to claim 5, wherein the substrate is a glass substrate. 5. The photosensitive cartridge according to claim 1, wherein a plurality of LED array chips each provided with a plurality of LED light emitting portions are mounted on the substrate in a main scanning direction. A detecting unit that detects a positional deviation amount of the line head in the sub-scanning direction; a storage unit that stores the positional deviation amount; and a control unit that outputs a control signal for correcting the positional deviation to the light emitting element. The line head according to any one of claims 1 to 7, wherein A plurality of image carriers that record images on the outer peripheral surface of a cylindrical surface that rotates about a rotation axis; and a plurality of photosensitive cartridges that respectively hold the plurality of image carriers.
9. A charging unit disposed around each of the image carriers, and pixels arranged in a line corresponding to each of the plurality of image carriers according to any one of claims 2 to 8. Image formation comprising a plurality of line heads that simultaneously perform optical writing, a developing unit, and a transfer unit that transfers and superimposes a plurality of images formed on the plurality of image carriers. An image forming apparatus, wherein at least two stations are provided, and an image is formed by a tandem method when the transfer medium passes through each station. The image forming apparatus according to claim 9, further comprising an intermediate transfer member.

Images