JP2006334871A - Line head and image forming apparatus using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line head which enables the easy creation of a pattern for detecting the inclination of the line head, and an image forming apparatus using it. <P>SOLUTION: A light source (light emitting part) 63 for forming an image, which is constituted as a dot light source, is formed on a glass substrate 62, and a plurality of light emitting parts 63 are arranged in a main scanning direction, so that a light-emitting-element line can be formed. The light emitting part 63 is driven by a TFT driving circuit 72. A plurality of light emitting elements 74 and 75 for forming the pattern for detecting the inclination of the line head are provided at both the main-scanning-direction ends of the glass substrate 62. The light emitting elements 74 and 75 are formed in the same shape as that of the dot light source. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a line head that can easily detect the inclination of the line head and an image forming apparatus using the line head.

  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.

  There is also known a color image forming apparatus including an image carrier configured to carry an electrostatic latent image, a rotary developing unit, and a line head. In this image forming apparatus, the rotary developing unit carries toner stored in a plurality of toner cartridges on the surface thereof, and rotates in a predetermined rotation direction so that different color toners are sequentially opposed to the image carrier. Transport to position. A developing bias is applied between the image carrier and the rotary developing unit to move the toner from the rotary developing unit to the image carrier. By such processing, the electrostatic latent image is visualized to form a toner image.

  In the tandem or rotary 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. In some cases, the line head having such a configuration is attached to be inclined with respect to a reference position in the main scanning direction. FIG. 13 is an explanatory diagram illustrating an example in which the line head is attached to be inclined with respect to the reference position in the main scanning direction. In FIG. 13, (a) is a state in which the line head is at a reference attachment position (regular main scanning line formation position), (b) is a state in which the line head is attached with an inclination of several dots upward in the figure, (c) ) Shows a state in which it is attached tilted several dots downward in the figure.

  As described above, when the line head is mounted with an inclination with respect to the reference position in the main scanning direction, density unevenness occurs and image quality deteriorates. Further, in the case of forming a color image, there arises a problem that a color shift occurs and a desired color cannot be reproduced. In order to prevent such image deterioration due to the inclination of the line head, various proposals for detecting the inclination of the line head have been made. For example, in Patent Document 1, a pattern image signal generating unit for forming a measurement pattern image for each color is provided on a transfer belt, and the pattern is detected by a detection unit.

JP-A 63-278074

  In the technique described in Patent Document 1, a measurement pattern is created and input to the image forming apparatus from the outside. In addition, it is necessary to store the measurement pattern as stored data in a control device provided in the image forming apparatus. For this reason, there is a problem that it takes time and effort to create a measurement pattern, and the configuration of the control device in the image forming apparatus becomes complicated, making it difficult to detect the inclination of the line head.

  The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a line head capable of easily detecting the inclination of the line head and an image forming apparatus using the same. It is in.

  The line head of the present invention that achieves the above object has a light emitting element line in which a plurality of light emitting elements composed of dot light sources for image printing are arranged on a substrate, and a drive circuit that drives each of the light emitting elements, A plurality of other light emitting elements for forming a line head inclination detection pattern on a substrate are provided on the same line in the main scanning direction with a dot light source having the same shape as the dot light source for image printing. . Thus, the line head of the present invention has a simple configuration in which a plurality of other light emitting elements for forming a tilt detection pattern is provided on the substrate, and it is not necessary to separately create a tilt detection pattern outside. The process for reducing the cost and correcting the inclination of the line head is also simplified. In addition, a plurality of other light-emitting elements that form the inclination detection pattern are formed with a dot light source having the same shape as the dot light source for image printing, and can be manufactured and manufactured in the same process as the dot light source for image printing. Is simple and can reduce the cost.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are provided at positions different from the light emitting element lines of the substrate in the sub-scanning direction. With such a configuration, the board space can be effectively used.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are provided on the same line as the light emitting element lines in the main scanning direction. With such a configuration, a plurality of other light emitting elements that form the line head inclination detection pattern can be formed on the substrate in the same process as the plurality of light emitting elements including the dot light source.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are provided at both ends of the substrate, respectively. With such a configuration, it is possible to effectively use the empty space of the substrate.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are provided in a printing area. With such a configuration, the degree of freedom can be increased without being restricted by the position of the substrate on which a plurality of other light emitting elements for forming the line head inclination detection pattern is provided.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are also used as light emitting elements for image printing. As described above, since the light-emitting element forming the line head inclination detection pattern is also used as the light-emitting element for image printing, the utilization efficiency of the light-emitting element can be improved.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are provided outside the printing area. With such a configuration, it is possible to form a line head inclination detection pattern without hindering image formation.

  The line head of the present invention is characterized in that a plurality of light-emitting elements composed of the dot light source for image printing and the plurality of other light-emitting elements are formed of organic EL elements. By adopting such a configuration, the organic EL element can be controlled statically, so that the control system for the line head can be simplified.

  The line head according to the present invention is characterized in that the drive circuit is formed of a TFT drive circuit. With such a configuration, the drive circuit can be formed on the substrate in the same process as the plurality of light emitting elements including the dot light source, so that the cost for generating the drive circuit can be reduced.

  The line head of the present invention is characterized in that a plurality of light emitting elements composed of the dot light source for image printing and the plurality of other light emitting elements are commonly driven by the drive circuit. By adopting such a configuration, a plurality of light emitting elements composed of dot light sources and a plurality of other light emitting elements forming an inclination detection pattern are driven by a single driving circuit. Can be planned. Further, the space of the line head can be saved and the size can be reduced.

  The line head according to the present invention is characterized in that the drive circuit is provided with switching means for switching between driving of a light emitting element for image printing and driving of a light emitting element for forming an inclination detection pattern. By adopting such a configuration, it is possible to prevent erroneous operations of image printing and tilt pattern formation.

  The line head of the present invention is characterized in that the plurality of other light emitting elements are driven at the same timing when the tilt detection pattern is formed by the drive circuit. With such a configuration, the control of the inclination detection pattern formation is simplified.

  The line head according to the present invention further comprises a detecting means for detecting the inclination detection pattern of the line head, means for calculating the inclination data of the line head based on the detection result of the detecting means, and means for storing the inclination data. It is characterized by having. As described above, since the tilt data of the line head is stored, it is easy to create tilt correction data, and image quality deterioration due to the tilt of the line head can be prevented.

  Further, the image forming apparatus of the present invention is provided with at least two or more image forming stations in which each of the image forming units of the charging unit, any of the line heads, the developing unit, and the transfer unit is arranged around the image carrier, An image is formed by a tandem method by passing the transfer medium through each station. Therefore, in the tandem image forming apparatus, it is possible to easily create a line head inclination detection pattern and perform inclination correction using the inclination data.

  The image forming apparatus of the present invention includes an image carrier configured to carry an electrostatic latent image, a rotary developing unit, and any one of the line heads, and the rotary developing unit includes a plurality of toners. The toner stored in the cartridge is carried on the surface thereof, and the toners of different colors are sequentially conveyed to a position facing the image carrier by rotating in a predetermined rotation direction, and the image carrier and the rotary developing unit And a developing bias is applied between the rotary developing unit and the image bearing member to develop the electrostatic latent image to form a toner image. For this reason, in an image forming apparatus provided with a rotary developing unit, it is possible to easily create a line head tilt detection pattern and perform tilt correction using tilt data.

  In addition, the image forming apparatus of the present invention includes an intermediate transfer member. For this reason, in an image forming apparatus provided with an intermediate transfer member, it is possible to easily create a line head inclination detection pattern and to perform inclination correction using inclination data.

  As described above, according to the present invention, the light emitting elements for creating the line head inclination detection pattern are formed on the same substrate as the plurality of light emitting elements of the dot light source. It can be simplified. In addition, tilt correction can be easily performed using the tilt data. In addition, a plurality of other light-emitting elements that form the inclination detection pattern are formed by a dot light source having the same shape as the dot light source for image printing, and can be manufactured and manufactured in the same process as the dot light source for image printing. Is simple and can reduce the cost.

  FIG. 9 is a vertical side view of an image forming apparatus in which the line head of the present invention is used. In this embodiment, an organic EL element is used as a light emitting element. In this image forming apparatus, four organic EL array exposure heads having the same configuration are respectively arranged at the exposure positions of four corresponding photosensitive drums (image carriers) having the same configuration. It is configured as a system image forming apparatus. The image forming apparatus 1 according to the present embodiment shown in FIG. 9 includes a housing body 2, a first opening / closing member 3 that can be opened and closed on the front surface of the housing body 2, and an upper surface that can be opened and closed. And a second opening / closing member 4 (which also serves 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. The opening / closing lid 3 ′ is interlocked with or independent of the first opening / closing member 3. It can be 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 feed unit 10 are disposed, and a first opening / closing member In FIG. 3, a secondary transfer unit 11, a fixing unit 12, and a recording medium conveying means 13 are arranged. The consumables in the image forming unit 6 and the paper feeding unit 10 are configured to be detachable from the main body. In this case, the configuration including the transfer belt unit 9 can be removed and repaired or replaced. It has become.

  A first opening / closing member 3 is mounted on the housing body 2 so as to be openable and closable on both sides of the lower front surface of the housing body 2 via a rotating shaft 3b. In this embodiment, each unit can be attached and detached by accessing only from the front surface of the apparatus, so that the apparatus can be installed in the room in a compact manner. 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. The driving roller 14 and the driven roller 15 are rotatably supported by the support frame 9a, and a rotating portion 9b is formed at the lower end of the supporting frame 9a. The rotating portion 9b is a rotation provided on the housing body 2. The support frame 9a is fitted to the housing body 2 so as to be rotatable.

  A lock lever 9c is rotatably provided at the upper end of the support frame 9a, and the lock lever 9c can be locked to a locking shaft 2c provided in the housing body 2. The drive roller 14 also serves as a backup roller for the secondary transfer roller 19 constituting the secondary transfer unit 11. The driven roller 15 is also used as a backup roller for the cleaning means 17. The cleaning means 17 is provided on the belt surface 16a side facing down in the transport direction.

  A primary transfer member 21 made of a leaf spring electrode is opposed to an image carrier 20 of each of the image forming stations Y, M, C, and K, which will be described later, on the back surface of the belt surface 16a facing downward in the conveyance direction of the intermediate transfer belt 16. The transfer force is applied to the primary transfer member 21 by contact with the elastic force. A test pattern sensor 18 is installed on the support frame 9 a of the transfer belt unit 9 in the vicinity of the drive roller 14. This test pattern sensor 18 is a sensor for positioning each color toner image on the intermediate transfer belt 16, detecting the density of each color toner image, and correcting the color shift and image density of each color image. It should be noted that a line head inclination detection pattern detecting means to be described later can be provided at an arbitrary position on the surface of the intermediate transfer belt 16.

  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. Note that the charging unit 22, the image writing unit 23, and the developing unit 24 give the figure numbers only to the image forming station Y, and the other image forming stations have the same configuration, and thus the drawing numbers are omitted. Further, the arrangement order of the image forming stations Y, M, C, and K is arbitrary. Then, the image carrier 20 of each image forming station Y, M, C, K is brought into contact with the belt surface 16a facing downward in the transport direction of the intermediate transfer belt 16, and as a result, each image forming station Y, M , C and K are also arranged in a direction inclined to the left in the drawing with respect to the drive roller 14. 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.

  As will be described later, the image writing unit 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 this 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. These units can be replaced with a support frame 9 a together with the transfer belt unit 9. When the image carrier unit 25 is replaced, the members including the line head are replaced.

  Next, details of the developing unit 24 will be described on behalf of the image forming station K. In the present embodiment, the image stations Y, M, C, and K are disposed in an oblique direction, and the image carrier 20 is in contact with the belt surface 16a facing downward in the conveyance direction of the intermediate transfer belt 16. The toner storage container 26 is disposed obliquely downward. Therefore, a special configuration is adopted as the developing unit 24. That is, the developing unit 24 includes a toner storage container 26 that stores toner (hatched part in the drawing), a toner storage part 27 formed in the toner storage container 26, and a toner disposed in the toner storage part 27. It has a stirring member 29 and a partition member 30 that is partitioned and formed above the toner reservoir 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 image carrier 20 is rotated in the conveyance direction of the intermediate transfer belt 16, and the developing roller 33 and the supply roller 31 are rotationally driven in a direction opposite to the rotation direction of the image carrier 20, as shown by the arrows in the figure. The stirring member 29 is driven to rotate in the direction opposite to the direction of rotation of the supply roller 31.

  Further, 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. Yes. In the first opening / closing member 3, a registration roller pair 37 that defines the timing of feeding the recording medium P to the secondary transfer unit, 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. In the example of FIG. 9, in the tandem image forming apparatus, it is possible to easily create a tilt detection pattern for the line head and to correct tilt using the tilt data as will be described later.

  FIG. 10 is a schematic perspective view showing the image writing means 23 in an enlarged manner. In FIG. 10, 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 means 23 is mounted on the glass substrate 62 with the light emitting portion 63 of the organic EL element array 61 and is driven by a TFT drive circuit 72 formed on the same glass substrate 62. The TFT drive circuit 72 drives the light emitting element by an active matrix method. The gradient index rod lens array 65 constitutes an imaging optical system, and has a gradient index rod lens 65 ′ arranged in front of the light emitting unit 63. Reference numeral 60 denotes a housing, and 66 denotes a cover. 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 65 ′ 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.

  As shown in FIG. 10, the line head of the present invention has a light emitting element formed on a substrate and a TFT drive circuit for driving the light emitting element by an active matrix method. The light emitting element is basically configured to perform gradation control by pulse width control (PWM control). When the line head having such a configuration is installed inclined with respect to the reference position in the main scanning line direction as described above, the correction is performed by pulse width control.

  FIG. 12 is an explanatory diagram showing the principle of detecting the inclination of the line head according to the present invention. When FIG. 13 is made to correspond to FIG. 12, FIG. 12A is an example in which the line head is normally attached, FIG. 12B is an example in which the line head is attached to be tilted by Dx in the upward direction in the figure, FIG. 12C shows an example in which the line head is attached with an inclination of Dy in the downward-rightward direction.

  Here, the inclination of the line head can be determined by detecting whether the detection pattern is parallel or inclined with respect to the reference line as described in the conventional example. In the example of FIG. 12, the inclination of the line head can be detected by detecting the direction of a straight line connecting points A and B2. In the present invention, based on such knowledge, a plurality of light emitting elements for creating a detection pattern on the substrate are provided on the same line in the main scanning direction, which corresponds to A and B of FIG. 12 of the image carrier. A detection pattern is formed at the position. This detection pattern is detected by detection means such as an optical sensor, and the control unit obtains the direction of a straight line connecting points A and B2. Next, the inclination of the line head can be detected by calculating the difference between the reference line and the direction of the straight line connecting the points A and B.

  FIG. 1 is an explanatory diagram showing an embodiment of the present invention. In FIG. 1, a light source (light emitting unit) 63 for image printing configured as a dot light source is formed on a glass substrate 62. A plurality of light emitting portions 63 are arranged on the same line in the main scanning direction to form light emitting element lines. Reference numeral 72 denotes a TFT drive circuit that drives the light emitting unit 63. The long direction X of the glass substrate 62 is the main scanning direction, and the short direction Y is the sub-scanning direction.

  At both ends of the glass substrate 62 in the main scanning direction, a plurality of light emitting elements 74 and 75 for forming a line head inclination detection pattern are provided. The light emitting elements 74 and 75 are formed by dot light sources having the same shape as the dot light source for image printing on the same line in the main scanning direction. Reference numerals 74a and 75a denote lead wires of the light emitting elements 74 and 75. In the example of FIG. 1, a plurality of light emitting elements 74 and 75 that form four inclination detection patterns are provided at the same timing by the TFT drive circuit 72. Driven. For this reason, the control of the inclination detection pattern formation is simplified. In this way, the plurality of other light emitting elements 74 and 75 that form the inclination detection pattern are formed by a dot light source having the same shape as the dot light source 63 for image printing, and thus the light emission that forms the inclination detection pattern. An element having a different shape from the dot light source 63 for image printing is not required. That is, the light emitting element for forming the tilt detection pattern can be manufactured in the same process as the dot light source for image printing. In addition, since a plurality of dot light sources are simultaneously driven to form the inclination detection pattern with a predetermined length, the inclination pattern can be easily detected.

  In the example of FIG. 1, the plurality of light emitting elements 74 and 75 forming the line head inclination detection pattern are provided on the same line as the light emitting element line in the main scanning direction. For this reason, since the light emitting elements 74 and 75 can be formed in the same process as the light emitting element line, the operation is simplified. The light emitting elements 74 and 75 are provided in the print area, but the inclination detection pattern is not transferred to the recording paper. Thus, since the light emitting elements 74 and 75 can be provided in the printing region, the degree of freedom in arranging the light emitting elements for forming the inclination detection pattern can be increased.

  In the example of FIG. 1, the drive circuit 72 drives a plurality of light emitting elements 74 and 75 that form a light emitting element line and an inclination detection pattern in common. As will be described later, the drive circuit 72 is configured to be able to switch and control the light emitting element to be driven during the inclination detection pattern formation and the image formation. For this reason, it is not necessary to provide a separate drive circuit, so that the cost can be reduced. In FIG. 1, the light emitting elements 74 and 75 that form the inclination detection pattern may be driven by a drive circuit different from the dot light source 63 for image printing.

  The light emitting elements 74 and 75 are connected to the drive circuit 72 by lead wires 74a and 75a. For this reason, by controlling the operation sequence, the light emitting elements 74 and 75 can be driven at an arbitrary timing to form an inclination detection pattern. The timing for forming the inclination detection pattern can be set as appropriate, such as when the image forming apparatus is activated, when the temperature rises, after a certain number of copies are printed, during printing, after cartridge replacement, and the like.

  As described above, in the embodiment of the present invention, a plurality of light emitting elements for forming a line head inclination detection pattern is provided on a glass substrate on which a light emitting element for image printing is formed. For this reason, it is not necessary to input an inclination detection pattern from the outside. Further, since it is not necessary to store the detection pattern as stored data inside the control device, the configuration of the control device is simplified.

  FIG. 2 is an explanatory view showing another embodiment of the present invention. In FIG. 2, the same parts as those in FIG. In this embodiment, the light emitting elements 74 and 75 that form the inclination detection pattern are disposed at both ends of the glass substrate 62 in the main scanning direction, that is, outside the printing area. In this case, a tilt detection pattern can be formed without hindering image printing. Further, the space at both ends of the glass substrate 62 in the main scanning direction can be used effectively.

  FIG. 3 is an explanatory view showing another embodiment of the present invention. The light emitting elements 74 and 75 that form the inclination detection pattern in FIG. 3 are provided on the glass substrate 62 at positions different from the light emitting element lines in the sub-scanning direction. For this reason, the space of the glass substrate 62 in the sub-scanning direction can be effectively used. Further, since the light emitting elements 74 and 75 are provided outside the printing area at both ends of the glass substrate 62, image printing is not hindered even if the inclination detection pattern is formed.

  FIG. 4 is an explanatory view showing another embodiment of the present invention. In FIG. 4, the light emitting elements 76 and 77 forming the inclination detection pattern are formed of dot light sources having the same shape as the dot light source 63 for image printing on the same line in the main scanning direction as in FIG. . Further, the light emitting elements 76 and 77 that are connected to the drive circuit 72 by the lead wires 76a and 77b and form four inclination detection patterns formed on the both ends of the drive circuit 72 of the glass substrate 62 are simultaneously driven. The

  In the example of FIG. 4, as will be described with reference to FIG. 8, switching means for switching between driving of a light emitting element for image printing and driving of a light emitting element for forming an inclination detection pattern is provided. With such a configuration, the light emitting element for forming the inclination detection pattern can also be used as the light emitting element for image printing, so that the light emitting element can be effectively used. Further, it is possible to prevent erroneous operation of image printing and tilt pattern formation.

  FIG. 5 is a flowchart showing the processing procedure of the present invention. In FIG. 5, a drive signal is generated at the predetermined timing to cause the light emitting elements 74, 75 (FIGS. 1 to 3) or 76, 77 (FIG. 4) to emit light, and the inclination detection pattern is displayed for each color line head. Printing is performed every time (S1). Next, the printed inclination detection pattern is detected using a detection sensor. At this time, the timing at which the detection pattern of each color is detected by the detection sensor is compared between the left and right (both ends) of the line head, and the timing difference is stored as inclination data (S2).

  The line head inclination data is compared with a reference line (absolute reference or a line head of a certain color), and the amount of inclination of the line head is calculated (S3). In this case, including a line head of a certain color as a standard. The inclination amount of the line head is zero. Further, it is calculated how many times the line width is one line width, and this value is input to the line head control circuit as inclination correction data (S4).

  FIG. 6 is a block diagram illustrating a control unit that performs the processing of the present invention. The main body controller 47 is constituted by a computer, for example, and forms image data. In addition, the control device 40 provided in the image forming apparatus is provided with a tilt detection unit 42, a memory 43, a control circuit 44 including a CPU, and a drive circuit 45, and is formed by a light emitting unit 63. One light emitting element line is controlled. The tilt detector 42 detects the tilt of the line head by detecting the tilt detection pattern as described above, and this tilt information is stored in the memory 43. The control circuit 44 forms a gradation signal for inclination correction based on the inclination information stored in the memory 43. The drive circuit 45 drives the light emitting elements arranged in the line head so that the inclination is corrected.

  In FIG. 6, the processing and control of the inclination detection unit 42, the memory 43, and the drive circuit 45 are performed by the control circuit 44 using a CPU or the like, but the present invention is not limited to such a form. In another embodiment, the main body controller 47 can directly process and control the tilt detection unit 42, the memory 43, and the drive circuit 45. In this case, the configuration of the control system of the image forming apparatus is simplified.

  In the present invention, an organic EL element can be used as the light emitting element. In addition to the organic EL element, for example, an LED (Light Emitting Diode) can be used. Since the organic EL element can be controlled statically, the control system for correcting the inclination of the line head can be simplified. Further, when the light emitting element is composed of LEDs, the light emitting element can be easily manufactured in the configuration in which the inclination of the line head is corrected.

  In some cases, the light emitting element is an organic EL element, and the control transistor of the light emitting element and the drive transistor are formed on the same substrate by a TFT (Thin Film Transistor). In this case, since these transistors and the light-emitting element can be manufactured in the same manufacturing process, manufacturing cost can be reduced. It also saves space. 1 to 4, since the light-transmissive glass substrate 62 is used, it is possible to irradiate the image carrier without impairing the light amount of the light emitting element made of the organic EL element.

  As described above, since the image forming apparatus of FIG. 9 uses the line head provided with the organic EL element as the writing means, the apparatus can be reduced in size as compared with the case where the laser scanning optical system is used. In addition, in the tandem image forming apparatus, it is possible to easily correct the inclination of the line head.

  In the present invention, the line head is naturally applied to the tandem color printer and the 4-cycle color printer in addition to the monochrome printer. Next, an embodiment in which a four-cycle color printer is used as the image forming apparatus according to the present invention will be described. FIG. 11 is a longitudinal side view of the image forming apparatus. In FIG. 11, an 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. It should be noted that the above-described line head inclination detection pattern detection means can be provided at any position on the surface of the intermediate transfer belt 169.

  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.

  In the state shown in the drawing, a yellow (Y) electrostatic latent image is formed on the photosensitive drum 165, and a high voltage is applied to the developing roller 62a, whereby a yellow image is formed on the photosensitive drum 165. When all of the yellow back side and front side images are carried on the intermediate transfer belt 169, the development rotary 161a rotates 90 degrees in the direction of arrow A.

  The intermediate transfer belt 169 rotates once and returns to the position of the photosensitive drum 165. Next, two images of cyan (C) are formed on the photosensitive drum 165, and this image is carried on the yellow image carried on the intermediate transfer belt 169. Thereafter, the 90-degree rotation of the development rotary 161 and the one-rotation process after the image is carried on the intermediate transfer belt 169 are repeated in the same manner.

  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. In this example, in a rotary image forming apparatus, it is possible to easily create a line head inclination detection pattern and perform inclination correction using inclination data. Further, as shown in FIGS. 9 and 11, in an image forming apparatus having an intermediate transfer member, it is possible to easily create a line head inclination detection pattern and to perform inclination correction using inclination data.

  FIG. 7 is a circuit diagram showing the configuration of the control unit of the present invention, and corresponds to the configuration of FIGS. In FIG. 7, reference numeral 92 denotes a peripheral circuit that is connected to a controller on the main body side and transmits and receives control data, 94 is a scan line, 95 is a data line, 96 is a supply line (anode side power line), 97 is a cathode side The power source line is connected in common to the dot light source 63 for image formation and the cathode of the light emitting element 75 for tilt detection pattern formation. A shift register 98 transfers control data.

  The dot light sources 63 are controlled by individually connected TFT circuits 72, and the light emitting elements 75 forming the line head inclination detection pattern are controlled by the leftmost TFT circuit 72a. Although not shown, in FIGS. 1 to 3, the light emitting element 74 that forms the inclination detection pattern of the line head formed on the right side of the glass substrate 62 is also used for image formation. A TFT circuit different from the TFT circuit 72 for driving the dot light source 63 is provided.

  The light-emitting elements 74 and 75 that form the line head tilt detection pattern are driven at the predetermined timing (when the image forming apparatus is started, when the temperature rises, after a certain number of copies are printed, during printing, after cartridge replacement, etc. ). At this time, control data different from image printing is output from the peripheral circuit 92 to the shift register 98.

  When an organic EL element is used for the light emitting part of the line head, the light amount unevenness of the light emitting element itself is 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, Even without correction of light quantity, the light quantity can be made uniform and the spot diameter can be made uniform. For this reason, a high-quality line head can be configured.

  In the example of FIG. 7, control data formed by the controller on the main body side is input to the peripheral circuit 92 and output from the peripheral circuit 92 to the shift register 98. The shift register 98 selects the scan line 94 based on the control data. The scan line 94 is connected to each of the TFT circuits 72, and the scan line 94 selected by the shift register 98 forms each connected TFT circuit 72 for driving a dot light source, or an inclination detection pattern. A control signal is applied to the TFT circuit 72a for driving the light emitting element 75.

  The peripheral circuit 92 is connected to the data line 95 and the supply line 96, the TFT circuit 72 to which the control signal is applied from the scan line 94 is activated, and the corresponding dot light source 63 is turned on. At this time, when the TFT circuit 72a is activated, the light emitting element 75 forming the line head inclination detection pattern is turned on.

  FIG. 8 is a circuit diagram showing another embodiment of the present invention and corresponds to FIG. A different point from FIG. 7 is demonstrated. In the example of FIG. 8, a dot light source driving switch Sa is provided on the supply line 96. The light emitting element 77 forming the inclination detection pattern is connected to one power source via the switch Sb, the lead wire 77a, and the supply line 96.

  The switch Sa is turned on and the switch Sb is turned off to form a print image. Further, the inclination detection pattern is formed by turning on the switch Sb and turning off the switch Sa. Since the switches Sa and Sb as such switching means are provided, the light emitting element can be used for both the print image formation and the inclination detection pattern formation. Further, it is possible to operate without error in image printing and tilt detection pattern formation. Note that the switches Sa and Sb can be formed of electronic switches such as TFTs.

  The line head of the present invention and the image forming apparatus using the same 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 explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is a flowchart which shows embodiment of this invention. It is a block diagram which shows embodiment of this invention. It is a circuit diagram showing an embodiment of the present invention. It is a circuit diagram showing an embodiment of the present invention. 1 is a longitudinal side view showing a schematic configuration of a tandem image forming apparatus according to the present invention. FIG. 10 is a perspective view partially showing FIG. 9. It is a vertical side view of an image forming apparatus showing another embodiment of the present invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows the inclination of a line head.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 6 ... Image forming unit, 9 ... Transfer belt unit, 10 ... Paper feed unit, 11 ... Secondary transfer unit, 12 ... Fixing unit, 13 ... Recording medium conveyance means, 16 ... Intermediate transfer belt, 17 DESCRIPTION OF SYMBOLS Cleaning means, 20 ... Image carrier, 21 ... Primary transfer member, 22 ... Charging means, 23 ... Image writing means (line head), 24 ... Development means, 25 ... Image carrier unit (image carrier cartridge), DESCRIPTION OF SYMBOLS 33 ... Development roller, 40 ... Control apparatus, 42 ... Tilt detection part, 43 ... Memory, 44 ... Control circuit, 45 ... Drive circuit, 47 ... Main body controller, 60 ... Housing, 61 ... Organic EL element array, 62 ... Glass substrate , 63... Light emitting section, 65. Turn of the light emitting element, 161 ... developing device, 165 ... photoconductor drum, 167 ... line head, 169 ... intermediate transfer belt, 171 ... secondary transfer roller

Claims (16)

The substrate has a light emitting element line in which a plurality of light emitting elements composed of dot light sources for image printing are arranged, and a drive circuit for driving each light emitting element, and a line head inclination detection pattern is formed on the substrate. A line head comprising a plurality of other light emitting elements arranged on the same line in the main scanning direction with a dot light source having the same shape as the dot light source for image printing. The line head according to claim 1, wherein the plurality of other light emitting elements are provided at positions different from the light emitting element lines of the substrate in a sub-scanning direction. The line head according to claim 1, wherein the plurality of other light emitting elements are provided on the same line as the light emitting element lines in a main scanning direction. 4. The line head according to claim 1, wherein the plurality of other light emitting elements are provided at both ends of the substrate, respectively. The line head according to claim 1, wherein the plurality of other light emitting elements are provided in a printing region. 6. The line head according to claim 1, wherein the plurality of other light emitting elements are also used as light emitting elements for image printing. The line head according to claim 1, wherein the plurality of other light emitting elements are provided outside a printing area. The line head according to claim 1, wherein the plurality of light emitting elements including the dot light source for image printing and the plurality of other light emitting elements are formed of organic EL elements. . The line head according to claim 1, wherein the drive circuit is formed of a TFT drive circuit. 10. The drive circuit according to claim 1, wherein a plurality of light emitting elements including the dot light source for image printing and the plurality of other light emitting elements are driven in common by the drive circuit. The line head described. 11. The line head according to claim 10, wherein the drive circuit is provided with switching means for switching between driving of a light emitting element for image printing and driving of a light emitting element for forming an inclination detection pattern. 12. The line head according to claim 1, wherein the plurality of other light emitting elements are driven at the same timing when the inclination detection pattern is formed by the driving circuit. The line head inclination detection pattern detection means is provided, and comprises means for calculating line head inclination data based on a detection result of the detection means, and means for storing the inclination data. The line head according to any one of claims 1 to 12. 14. At least two image forming stations in which image forming units including a charging unit, a line head according to claim 1, a developing unit, and a transfer unit are arranged around an image carrier. An image forming apparatus provided as described above, wherein a transfer medium passes through each station and forms an image by a tandem method. An image carrier configured to carry an electrostatic latent image, a rotary developing unit, and the line head according to claim 1, wherein the rotary developing unit includes a plurality of toner cartridges. The toner stored in the toner is carried on the surface, and toners of different colors are sequentially conveyed to a position facing the image carrier by rotating in a predetermined rotation direction, and the image carrier, the rotary developing unit, An image forming method characterized in that a developing bias is applied between the toner and the toner is moved from the rotary developing unit to the image carrier to visualize the electrostatic latent image to form a toner image. apparatus. The image forming apparatus according to claim 14, further comprising an intermediate transfer member.

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