JP2010091909A - Led optical element, image forming apparatus, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED optical element capable of improving imaging blur of an electrostatic latent image on a photoreceptor and producing a high-definition electrophotographic image, and to provide an image forming apparatus and an image forming method. <P>SOLUTION: The LED optical element includes a plurality of LEDs linearly arranged on a substrate and supported by an optical system supporting member, and imaging elements converging light from the LEDs and imaging, wherein the imaging element includes a plurality of lenses on the optical path from the LED and has at least a combination of a rod lens in the upstream side of the optical path and a concave lens in the downstream side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an LED (light emitting diode) optical element, an image forming apparatus, and an image forming method used in an electrophotographic image forming apparatus used in the field of copying machines and printers.

  2. Description of the Related Art A method using an LED (light emitting diode) array is known as an image writing device for a photoreceptor of an image forming apparatus. In this method, modulated light from an LED array arranged at a high density is guided onto a photoconductor by a converging rod lens array to form an image. The number of LED light emitting elements corresponding to the resolution is arranged in a row or a staggered pattern. Since the optical scanning mechanism is arranged side by side, the optical scanning system can be downsized.

  However, in general, an LED writing head (hereinafter referred to as an LED head) in which a converging rod lens array is used has a shallow focal depth of the rod lens (about 50 to 100 μm). The image exposure from the LED incident on the rod lens forms a blurred image, leading to degradation of image quality. For this reason, in an image forming apparatus equipped with an LED head, it is necessary to prevent the distance between the LED head and the photoconductor from deviating from the reference position. For example, if there is eccentricity of the drum-shaped photoconductor or misalignment of the drum support mechanism, partial image blurring occurs in the electrostatic latent image formed on the photoconductor, and if the toner is developed, the image will be unclear. There is a case. Even if a solution to such a problem is made from the viewpoint of machine accuracy, there is a limit to improvement in machine dimensional tolerance and assembly accuracy, and the cost also increases.

  As a solution to this problem, Patent Document 1 discloses a method of detecting the surface displacement of a photosensitive member and changing the positions of the light emitting means and the imaging element. Patent Document 2 discloses a method of positioning the LED head by providing reference positions at both ends of the LED head, measuring the distance between the reference position and the photosensitive member with a displacement sensor or the like, and finely moving the LED head. Yes.

Further, in Patent Document 3, peripheral surface displacement information for one rotation of the rotating photosensitive member is measured by a displacement sensor, and based on the displacement information, the LED head is advanced and retracted relative to the peripheral surface of the photosensitive member. An image forming apparatus is shown in which the distance from the peripheral surface of the photosensitive member is constant.
JP-A 62-250466 Japanese Patent Laid-Open No. 04-246668 JP 2006-187929 A

  However, the improvement in the method for positioning the imaging position of the LED light or the like shown in the above cited reference is an improvement in increasing the accuracy of the gap between the photosensitive member and the LED optical element, and an improvement from such an approach. The method alone is still insufficient for improving the partial blurring of the electrostatic latent image on the photosensitive member due to the eccentricity of the drum-shaped photosensitive member or the misalignment of the drum support mechanism. It was.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and it is still impossible to improve the accuracy of the gap between the conventional photoconductor and the LED optical element. An object of the present invention is to provide an LED optical element, an image forming apparatus, and an image forming method that can further improve blurring and can produce a high-definition electrophotographic image.

  As a result of intensive studies on the above-mentioned problems, the conventional image blurring is remarkably improved and the cost is not greatly increased only by slightly changing the lens configuration of the convergent lot lens array of the LED optical element. Thus, the inventors have found that these problems can be solved, and achieved the present invention.

  That is, the present invention is achieved by an LED optical element having the following configuration and an image forming apparatus using the optical element.

  1. In an LED optical element having a plurality of LEDs arranged in a line on a substrate and having an LED supported by an optical system support member and an imaging element for converging light from the LED to form an image, the coupling An LED optical element, wherein the element has a plurality of lenses on an optical path from the LED, and has a combination of at least a rod-shaped lens on the upstream side of the optical path and a concave lens on the downstream side.

  2. A plurality of LEDs are linearly arranged on the substrate, and the LEDs supported by the optical system support member and the light from the LEDs are imaged on the surface of the electrophotographic photosensitive member, and electrostatically formed on the electrophotographic photosensitive member. In an image forming apparatus having an LED optical element in which an imaging element for forming a latent image is arranged, a coupling element of the LED optical element has a plurality of lenses on an optical path from the LED, and at least the upstream side of the optical path is a lot lens An image forming apparatus having a concave lens combination on the downstream side.

  3. 3. The image forming apparatus as described in 2 above, wherein the electrophotographic photosensitive member is a cylindrical electrophotographic photosensitive member.

  4). 4. The image forming apparatus as described in 3 above, wherein the electrophotographic photosensitive member has a cylindricity of 5 to 40 μm.

  5. An image forming method, comprising: forming an electrophotographic image using the image forming apparatus according to any one of 2 to 4 above.

  By using the LED optical element of the present invention and an image forming apparatus using the LED optical element, image blur due to image exposure using the LED, image defects due to toner contamination on the LED optical element, and the like are improved. An image forming apparatus and the like capable of forming a clear electrophotographic image matching the above are provided.

  Hereinafter, a detailed description of the present invention will be described.

  First, the LED optical element according to 1 of the present invention will be described.

  Hereinafter, the structure of the LED optical element 120 will be described with reference to FIGS.

  1 is a perspective view of the LED optical element 120, FIG. 2 is a perspective view of a substrate 123a on which an LED (light emitting diode) 121 is disposed, and FIG. 3 is an enlarged cross-sectional view of the LED optical element 120.

  The LED optical element 120 includes a plurality of LEDs 121 and an image forming element 122 formed of a lens array corresponding to the LEDs. In FIG. 4, the plurality of LEDs 121 of the LED optical element 120 and the imaging element 122 including a lens array are linearly arranged in the axial direction of the electrophotographic photosensitive member 21.

  As shown in FIGS. 1 and 3, the LED optical element 120 includes a substrate 123 a on which a plurality of LEDs 121 arranged in the axial direction of the electrophotographic photosensitive member 21, an LED driving IC 126, and a temperature sensor 127 are arranged, and an imaging element 122. Is attached to a holding member (optical system cover) 124 that holds the LED, is configured as a unit, is provided outside the electrophotographic photosensitive member 21, and is attached to an optical system support member 200 that fixes and holds the LED optical element 120. The image signals of the respective colors stored in the image forming memory are sequentially read out from the memory and input to the LED optical element 120 as electrical signals through the connector 129. Further, in FIG. 1, the substrate 123 a of the LED 121 is fixed to the holding member 124 with an adhesive 128 indicated by oblique lines.

  As shown in FIG. 2, the LED 121 is a light emitting diode array in which light emission wavelengths are arranged in a linear shape in the range of 350 to 900 nm. The LED 121 is formed on a substrate 123a using, for example, Pyrex (registered trademark) glass.

  The coupling element 122 according to the present invention has a structure in which a plurality of lenses are provided on the optical path from the LED, and at least the optical path upstream side is a rod-shaped lens and the downstream side is a concave lens.

  When the coupling element has this configuration, the depth of focus becomes deep, and image exposure from the LED array forms a sharp image at a focal position such as the surface of the electrophotographic photosensitive member. Can provide an improved electrophotographic image. In addition, since the apparent focal length that has passed through a plurality of lenses becomes longer, the distance L0 between the outer peripheral surface of the electrophotographic photosensitive member 21 and the end face of the imaging element 122 of the LED optical element 120 is used for the conventional LED optical element. The lens surface of the coupling element (rod lens array) can be less contaminated (contamination contamination of the toner fine powder and contaminants on the photosensitive member). .

  FIG. 4 is a cross-sectional view showing the configuration of one coupling element of the LED optical element of the present invention.

  In FIG. 4, a rod-shaped lens 122a is disposed upstream of the optical path a for image exposure emitted from the LED 121 on the substrate 123a, and a concave lens 122b is disposed on the downstream side. The LED light transmitted through the concave lens with respect to the incident distance L1 from the LED. The focal length L2 is large, and the focal length is longer than the conventional L2 / L1 equal-magnification rod lens configuration.

  The rod-shaped lens of the present application is a conventional lot lens, and a lot lens array of a refractive index dispersion type in which the refractive index is changed from the outside in the radial direction of the column to the center is widely marketed. .

  The concave lens is a general lens in which the vicinity of the center of the optical axis is thinner than the peripheral portion, but may be a refractive index dispersion type lens in which the refractive index is changed from the outer side in the lens radial direction to the central direction. As the concave lens, it is preferable to use an integrated concave lens array linearly integrated on the base 123b as shown in FIG. By combining the integrated concave lens array thus integrated with the rod lens array, it is possible to improve the installation accuracy of the lot lens and the concave lens.

  Next, the application of the LED optical element of the present invention to an electrophotographic image forming apparatus and an image forming method will be described.

  An image forming apparatus 1 shown in FIG. 6 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. Yes.

  An automatic document feeder that automatically conveys the document is provided above the image reading unit A. The document placed on the document table 11 is separated and conveyed by the document conveyance roller 12 to the reading position 13a. The image is read. The document after the document reading is completed is discharged onto the document discharge tray 14 by the document transport roller 12.

  On the other hand, the image of the original when placed on the platen glass 13 is read at a speed v of the first mirror unit 15 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by the movement of the second mirror unit 16 including the two mirrors and the third mirror in the same direction at the speed v / 2.

  The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal) and then A / D converted, and the image processing unit B performs processing such as density conversion and filter processing. Then, the image data is temporarily stored in the memory.

  In the image forming unit C, as an image forming unit, a drum-shaped photoconductor 21 as an image carrier, a charging unit (charging step) 22 for charging the photoconductor 21 on the outer periphery thereof, and image exposure on the charged photoconductor. Image exposing means 30, developing means (developing process) 23, transfer conveying belt device 45 as transfer means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light neutralizing means (light grading process). PCL (precharge lamps) 27 are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. As the photosensitive member 21, the organic photosensitive member according to the present invention is used, and the photosensitive member 21 is driven and rotated in the clockwise direction shown in the drawing.

  After the rotating photosensitive member 21 is uniformly charged by the charging unit 22, the LED optical element of the present invention is used as the image exposure unit (image exposure step) 30, and is called from the memory of the image processing unit B. Image exposure based on the image signal is performed. The image exposure means 30 which is a writing means uses the LED optical element of the present invention, and image exposure is performed on the photoreceptor 21, and an electrostatic latent image is formed by rotation (sub-scanning) of the photoreceptor 21. The In one example of the present embodiment, the character portion is exposed to form an electrostatic latent image.

  In the image forming apparatus of the present invention, a light emitting diode having an oscillation wavelength of 350 to 900 nm is used as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. Using these image exposure light sources, the exposure dot diameter in the writing direction is narrowed down to 10 to 100 μm, and digital exposure is performed on the organic photoreceptor, so that it is 200 dpi (dpi: the number of dots per 2.54 cm) or more. A high-resolution electrophotographic image of 2500 dpi can be obtained.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction (Ld: measured at the maximum length) in a region where the intensity of the exposure beam is 1 / e ² or more of the peak intensity.

  The electrostatic latent image on the photoconductor 21 is reversely developed by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21. In the image forming method of the present invention, it is preferable to use a polymerized toner as a developer used in the developing means. By using a polymer toner having a uniform shape and particle size distribution in combination with the organic photoreceptor according to the present invention, an electrophotographic image with better sharpness can be obtained.

  The electrostatic latent image formed on the organic photoreceptor of the present invention is visualized as a toner image by development. The toner used for development may be a pulverized toner or a polymerized toner, but the toner according to the present invention is preferably a polymerized toner that can be prepared by a polymerization method from the viewpoint of obtaining a stable particle size distribution.

  The term “polymerized toner” means a toner in which a toner binder resin is formed and the toner shape is formed by polymerization of a raw material monomer of the binder resin and, if necessary, subsequent chemical treatment. More specifically, it means a toner formed through a polymerization reaction such as suspension polymerization or emulsion polymerization, and if necessary, a step of fusing particles between them.

  The volume average particle diameter of the toner, that is, the 50% volume particle diameter (Dv50) is desirably 2 to 9 μm, more preferably 3 to 7 μm. Such a toner having a small particle diameter is advantageous in forming a high-definition image of an electrophotographic image. On the other hand, the toner is likely to be scattered around the electrophotographic photosensitive member, and the coupling element of the LED optical element. (Lot lens array) is easily contaminated. However, by using the LED optical element of the present invention, the gap between the photoconductor and the LED optical element can be increased, and the contamination of the lens surface due to such toner scattering and the resulting electrophotographic image defects can be reduced. can do.

  The 50% volume particle size (Dv50) indicates a particle size distribution measured in the range of 2.0 to 40 μm using a Coulter multisizer and an aperture diameter = 100 μm.

  The toner according to the present invention may be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means for storing transfer paper P of different sizes. Further, a manual paper feeding unit 42 for manually feeding paper is provided on the side, and the transfer paper P selected from any of them is fed along the transport path 40 by the guide roller 43 and fed. The transfer paper P is temporarily stopped by a pair of paper feed registration rollers 44 that correct the inclination and bias of the transfer paper P to be transferred, and then fed again. The transport path 40, the pre-transfer roller 43a, and the paper feed path 46 The toner image on the photosensitive member 21 is transferred to the transfer paper P while being transferred to the transfer conveyance belt 454 of the transfer conveyance belt device 45 by the transfer electrode 24 and the separation electrode 25 at the transfer position Bo. Is, transfer sheet P is separated from the photosensitive member 21 surface, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the toner is fixed by heating and pressing. After the toner image has been fixed, the transfer paper P is discharged onto the paper discharge tray 64.

  The above describes the state in which image formation is performed on one side of the transfer paper. However, in the case of double-sided copying, the paper discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.

  Further, the transfer paper P is transported downward by the transport mechanism 178 and switched back by the transfer paper reversing unit 179, and the rear end portion of the transfer paper P becomes the leading end portion and transported into the duplex copying paper supply unit 130. The

  The transfer paper P is moved in a paper feed direction by a conveyance guide 131 provided in the double-sided copy paper supply unit 130, the transfer paper P is re-fed by the paper supply roller 132, and the transfer paper P is guided to the conveyance path 40. .

  Again, as described above, the transfer paper P is conveyed in the direction of the photosensitive member 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged onto the paper discharge tray 64.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Also good. In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device together with a photosensitive member, and a single unit that is detachable from the apparatus main body. It is good also as a structure which can be attached or detached using guide means, such as a rail of an apparatus body.

  The image forming apparatus of the present invention uses the above-described LED optical element for image exposure of an electrophotographic photosensitive member. In order to improve the image exposure imaging effect of the LED optical element, It is more preferable to suppress blurring on the image plane.

  In order to improve the blurring of the imaging surface of the electrophotographic photosensitive member, that is, in order to keep the gap distance from the lens surface of the LED optical element to the surface of the electrophotographic photosensitive member constant, the cylindrical electron In a photographic photoreceptor, it is necessary to reduce the cylindrical geometric distortion. Therefore, in the cylindrical electrophotographic photosensitive member according to the present invention, it is preferable to suppress the cylindricity of the cylindrical support of the electrophotographic photosensitive member within a range of 5 to 40 μm.

  In order to make the cylindricity within this range, it is necessary to improve the dimensional accuracy of the metal of the photoreceptor support. For example, in the case of an aluminum support, a high-precision can with an aluminum cutting tube is preferable. Furthermore, it is necessary to increase the uniformity of the thickness of the aluminum drawn tube before cutting, and to increase the roundness and straightness.

  The cylindricity of the present invention is based on JIS standard (B0621-1984). That is, when the cylindrical substrate is sandwiched between two coaxial geometric cylinders, it is represented by the difference in radius at the position where the distance between the two coaxial cylinders is minimum. In the present invention, the difference in radius is represented by μm.

  The cylindrical base of the present invention has a cylindricity of 5 to 40 μm, preferably 7 to 30 μm, and more preferably 7 to 27 μm. If it is smaller than 5 μm, the yield is deteriorated and disadvantageous in cost.

  The cylindricity of the electrophotographic photosensitive member of the present invention is preferably in the same range as described above. However, the cylindricity of the electrophotographic photosensitive member substantially means the cylindricity of the area where image formation is performed, and excludes the fluctuation area of the photosensitive layer thickness at both ends where image formation is not performed.

  The method for measuring cylindricity according to the present invention measures and determines the roundness of a total of 7 points, that is, 2 points 10 mm on both ends of the cylindrical substrate, 4 points of the center part, and 4 points obtained by equally dividing the distance between the ends. The measuring device used was a non-contact universal roll diameter measuring machine (manufactured by Mitutoyo Corporation).

  The cylindricity according to the present invention can be adjusted by cutting a cylindrical substrate. For example, while rotating the cylindrical substrate, the cutting tool is brought into contact with the cutting tool and moved to adjust the cylindricity of the surface.

  In the present invention, a more preferable effect can be obtained by using an electrophotographic photosensitive member in which an organic or inorganic photosensitive layer is formed on a cylindrical substrate having a cylindricity of 5 to 40 μm.

  In order to confirm the effect of the present invention, an image forming apparatus according to an example shown below (hereinafter simply referred to as an example) and an image forming apparatus according to a comparative example (hereinafter simply referred to as a comparative example) were compared. It was.

Example 1
In the LED optical element of the present invention, as shown in FIG. 3, the light of each LED 121 is condensed on the light receiving surface 21 </ b> B of the photoreceptor 21 via the coupling element 122. At this time, the configuration of the coupling element 122 is configured by a pair of a rod-shaped lens (incident distance L1 = 2 mm) and a concave lens as shown in FIG. 4, and the ratio L2 / L1 is 2.0. Such an LED optical element (an LED optical element having a 300 mm wide LED array in which LEDs are arranged at intervals of 63 μm and a lens array) is mounted as an exposure apparatus of an image forming apparatus (bizhub C350 remodeling machine). A photosensitive member is used in which a uniform organic photosensitive layer having a film thickness of 25 μm is formed on a cylindrical substrate having an outer diameter of 30 mmφ, a length of 352 mm, and a cylindricity of 28 μm. The developer is 50% volume of toner. A two-component developer using a toner having a particle size (Dv50) of 6.2 μm was used. As a result, the depth of focus becomes deep, and even if the light receiving surface 21B is displaced in the optical axis direction (arrow Z direction) from the ideal image plane position, uneven image density is less likely to occur. In addition, when the ratio L2 / L1 is 2.0, the distance L0 (approximately equal to the focal length L2) between the coupling element 122 and the light receiving surface 21B can be made twice as long as the conventional LED lot lens array. Lens contamination from the photoreceptor surface could be reduced.

Examples 2-8
When the concave lens was changed, L2 / L1 was changed as shown in Table 1, and images were taken out with various photoreceptors having different degrees of cylindricality, the images were similarly evaluated. The results are shown in Table 1.

Example 9
The image was formed in the same manner as in Example 1 except that the shape of the concave lens was as shown in FIG. 7 and a member in which concave lenses of six light sources were integrally formed was used. The results are shown in Table 1.

Comparative Example 1
Image extraction was performed in the same manner as in Example 1 except that the concave lens was removed from the imaging element 122 of Example 1.

Comparative Example 2
Image extraction was performed in the same manner as in Example 8 except that the concave lens was removed from the imaging element 122 of Example 8.

Evaluation Method Bokeh Evaluation Image blur evaluation method is a halftone A4 image of 1 dot ON-2 dots OFF, divided into 25 equal screens of 5 equal vertical and 5 equal horizontal, and the maximum density and minimum in each section The density was measured, and the average of the maximum density 25 data and the average of the minimum density 25 data of each section were measured.

  If dot bleeding occurs partially, the image of the image density at that portion becomes higher or lower than the surrounding area, and a uniform density cannot be obtained.

  As for the average value, the difference between the maximum and minimum density needs to be 0.2 or less (◯), and preferably 0.1 or less (（). If the difference is larger than 0.2, partial image unevenness can be recognized by general users, and the image quality is significantly reduced (x).

  In addition, the said density | concentration measurement was measured by the reflection density using Macbeth RD-918. The reflection density was evaluated by a relative density (the density of A4 paper not printed is 0.000).

Lens dirt Ten thousand test images with a printing density of 5% were photographed in an environment of 30 ° C. and 85% RH, the optical system was removed, and the transmittance of the lens at a wavelength of 500 nm was measured. If it is 95% or more in this evaluation, it can be used at a level with almost no problem under the actual shooting conditions in practical use, but it is preferably 98% or more depending on the use environment of the model.

Transmittance (T%): 98% ≦ T ○
95% ≦ T <98% △
T <95% ×
The evaluation results are shown in Table 1 below.

  As is clear from Table 1, in all of the examples, image blur due to defocusing did not occur and a uniform and good image layer was obtained, whereas in the comparative example, partial blur occurred. The uniformity of the image could not be obtained.

  Further, when the toner particle size (Dv50) is small, it is particularly susceptible to toner scattering, and it is expected that the deterioration of the image quality of the lens stain due to toner scattering can be suppressed by using the optical system of the present configuration. The

The perspective view of an exposure optical system. The perspective view of the board | substrate which has arrange | positioned the light emitting element. The expanded sectional view of an exposure optical system. It is sectional drawing which showed the structure of one coupling element of the LED optical element of this invention. It is a figure of an integrated concave lens array. 1 is a schematic view in which functions of an image forming apparatus of the present invention are incorporated.

Explanation of symbols

21 Photosensitive drum (image forming body)
21A Substrate 120 LED optical element 121 Light emitting element (light emitting light source, line light emitting means, LED array)
122 Imaging element (refractive index distribution type lens array)
123a, 123b Substrate 124 Holding member (optical system cover)
125 Positioning spacer 126 Driving IC
127 Temperature sensor 128 Adhesive 129 Connector 200 Optical system support member

Claims (5)

In an LED optical element having a plurality of LEDs arranged in a line on a substrate and having an LED supported by an optical system support member and an imaging element for converging light from the LED to form an image, the coupling An LED optical element, wherein the element has a plurality of lenses on an optical path from the LED, and has a combination of at least a rod-shaped lens on the upstream side of the optical path and a concave lens on the downstream side. A plurality of LEDs are linearly arranged on the substrate, and the LEDs supported by the optical system support member and the light from the LEDs are imaged on the surface of the electrophotographic photosensitive member, and electrostatically formed on the electrophotographic photosensitive member. In an image forming apparatus having an LED optical element in which an imaging element for forming a latent image is arranged, a coupling element of the LED optical element has a plurality of lenses on an optical path from the LED, and at least the upstream side of the optical path is a lot lens An image forming apparatus having a concave lens combination on the downstream side. The image forming apparatus according to claim 2, wherein the electrophotographic photosensitive member is a cylindrical electrophotographic photosensitive member. The image forming apparatus according to claim 3, wherein the support of the electrophotographic photosensitive member has a cylindricity of 5 to 40 μm. An image forming method, comprising: forming an electrophotographic image using the image forming apparatus according to claim 2.

Images