JP5209869B2 - Image reading apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an image reading apparatus that scans an original with light from a plurality of point light sources arranged in the main scanning direction and reads an image with a photoelectric conversion element, and an image forming apparatus such as a copying machine, a printer, and a facsimile equipped with the image reading apparatus It is about.

  In an image forming apparatus such as a copying machine or a laser beam printer that employs an electrophotographic system, an image reading device that scans an original placed on a contact glass by optical scanning is provided. Based on the obtained image data, an image is formed on a recording material such as paper by an image forming means. Here, the image forming unit includes various process devices such as a photosensitive drum, a developing device, a transfer device, and a fixing device.

  Incidentally, the image reading apparatus further reflects the transparent contact glass on which the document is placed, the light source that emits light toward the document placed on the contact glass, and the reflected light reflected on the document surface. The lens includes a plurality of mirrors that change the direction, a lens that collects the reflected light, and a light receiving element such as a CCD sensor that reads the reflected light collected by the lens.

  The light source of such an image forming apparatus is configured by arranging a plurality of point light source packages each holding a point light source such as an LED on the light source substrate in the main scanning direction. Here, the light distribution in the sub-scanning direction of one point light source is shown in FIG.

  In FIG. 7, the horizontal axis represents the distance [mm] in the sub-scanning direction, the vertical axis represents the ratio of the light amount, and the light amount of the point light source changes from the image reading position (center) to the sub-scanning direction as illustrated. It can be seen that the amount of light changes greatly parabolically.

  Accordingly, the position of the point light source in the sub-scanning direction is very important in the light distribution on the document surface, and the illuminance on the document surface changes greatly due to a slight displacement of the point light source in the sub-scanning direction. In addition, when individual point light sources are displaced in the sub-scanning direction, unevenness in illuminance also occurs and adversely affects the image. For example, FIG. 8 shows the light distribution in the sub-scanning direction of three adjacent (n, n−1, n + 1th (n is an integer)) point light sources whose positions in the sub-scanning direction are shifted from each other. The light distribution in the sub-scanning direction varies depending on the position of the light source. When the light is focused using a lens or the like to irradiate the original surface, the displacement of each point light source in the sub-scanning direction causes a larger light amount difference.

Therefore, in Patent Document 1, in order to maintain a good illuminance distribution on the original surface in a reading optical system in which point light sources are arranged in the main scanning direction, point light sources having different light distribution characteristics are arranged or supplied to the point light sources. Proposals have been made such as adjusting the current value and narrowing the arrangement pitch of the point light sources toward the ends.
JP 2004-177851 A

  However, Patent Document 1 does not clearly disclose the alignment accuracy of point light sources in the sub-scanning direction. When a plurality of point light sources arranged in the main scanning direction are used as the light source, the deviation of the individual point light sources in the sub-scanning direction causes an illuminance difference on the document surface, and the illuminance distribution on the document surface is uneven. Therefore, there arises a problem that the image quality is deteriorated.

  The present invention has been made in view of the above problems, and the object of the present invention is to stably position a high quality image by positioning a plurality of point light sources with high accuracy in the sub-scanning direction and mounting them on a light source substrate. And an image forming apparatus provided with the image reading apparatus.

In order to achieve the above object, the invention described in claim 1 comprises a light source formed by arranging a plurality of point light source packages each holding a point light source in a main scanning direction on a light source substrate, and the light source is arranged on the document surface. In an image reading apparatus that scans a document surface with light emitted toward it and reads a document image, the light source substrate is attached to the lower surface of the upper wall of the positioning member, and protrudes from the end surface of the upper wall of the positioning member of the light source substrate The point light source package is mounted on the upper surface of the portion to be mounted in a state where the end surface of the point light source package is positioned in contact with the end surface of the positioning member, thereby positioning the point light source package in at least one direction. And

  According to a second aspect of the present invention, in the first aspect of the present invention, the positioning direction of the point light source package by the positioning member is a reading sub-scanning direction.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the surface of the positioning member is subjected to an antireflection treatment.

  A fourth aspect of the invention is characterized in that, in the invention of any one of the first to third aspects, the positioning member is detachably fastened to the scanning frame body together with the light source.

  A fifth aspect of the invention includes the image reading apparatus according to any one of the first to fourth aspects and an image forming unit that forms an image on a recording material based on image data read by the image reading apparatus. The image forming apparatus is configured as described above.

  According to the first and second aspects of the present invention, since the end portions of the plurality of point light source packages are brought into contact with the positioning member to position the point light source packages in at least one direction, the point light source packages are held. The read point light source can be read and positioned with high accuracy in the sub-scanning direction and mounted on the light source substrate, and the illuminance distribution on the original surface can be made uniform to stably obtain a high-quality image.

  According to the third aspect of the present invention, since the antireflection treatment is performed on the surface of the positioning member, the positioning member hardly reflects light from the light source, and flare is prevented.

  According to the fourth aspect of the present invention, since the positioning member is detachably fastened to the scanning frame together with the light source, when the point light source is replaced, the lighting performance is obtained by exchanging the positioning member and the light source together as a set. The light source can be easily replaced without degrading the light.

  According to the fifth aspect of the present invention, a high quality image can be stably obtained based on image data read with high accuracy by the image reading apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Image forming apparatus]
FIG. 1 is a front sectional view of a color copying machine as an embodiment of an image forming apparatus according to the present invention. The illustrated color copying machine includes an image reading device 20 according to the present invention at an upper portion of a main body 100, and the main body 100. The magenta image forming unit 1M, the cyan image forming unit 1C, the yellow image forming unit 1Y, and the black image forming unit 1BK constituting the image forming unit are arranged in a line at regular intervals in the inner central portion.

  The image forming units 1M, 1C, 1Y, and 1BK, which are image forming units, have drum type electrophotographic photosensitive members (hereinafter referred to as “photosensitive drums”) 2a, 2b, 2c, and 2d as image carriers. is set up. Around the photosensitive drums 2a to 2d, there are primary chargers 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d as primary transfer means, and drums. Cleaning devices 6a, 6b, 6c and 6d are arranged, respectively.

  The photosensitive drums 2a to 2d are drum-shaped amorphous silicon (α-Si) photosensitive members, and are rotated at a predetermined process speed in a direction indicated by an arrow (counterclockwise in FIG. 1) by a driving device (not shown). The

  The primary chargers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing devices 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (BK) toner, respectively, and are formed on the photosensitive drums 2a to 2d. The toner of each color is attached to each electrostatic latent image to develop each electrostatic latent image as a toner image of each color (visualization), and the toner is consumed and the developing devices 4a to 4d When a toner replenishment signal is issued because the remaining amount of toner is less than a certain value, toner of each color is replenished from the toner replenishing devices 7a, 7b, 7c and 7d to the developing devices 4a to 4d. The toner replenishing devices 7 a to 7 d are configured as cartridges that can be attached to and detached from the copying machine main body 100.

  The transfer rollers 5a to 5d as primary transfer means are arranged so as to be in contact with the photosensitive drums 2a to 2d via an endless intermediate transfer belt 8 at each primary transfer portion (primary transfer nip portion). ing. Here, the intermediate transfer belt 8 constitutes a second image carrier, and is stretched between the secondary transfer counter roller 9 and the tension roller 10 and travels to the upper surface side of each of the photosensitive drums 2a to 2d. Arranged to be possible. The secondary transfer counter roller 9 is disposed so as to be in contact with the secondary transfer roller 11 via the intermediate transfer belt 8 in the secondary transfer portion (secondary transfer nip portion). As the material of the intermediate transfer belt 8, for example, a dielectric resin such as polycarbonate, polyethylene terephthalate (PET), polyvinylidene fluoride (PVdF), or the like is selected. Although not shown, a belt cleaning device for removing residual toner remaining on the surface of the intermediate transfer belt 8 is installed outside the intermediate transfer belt 8 and in the vicinity of the tension roller 10. Yes.

  On the other hand, a laser scanner unit 40 is arranged below each image forming unit 1M, 1C, 1Y, 1BK inside the copying machine main body 100, and a paper feed cassette 50 is detachably installed at the bottom of the main body 100 below the image forming units 1M, 1C, 1Y, 1BK. In this paper feed cassette 50, a plurality of recording materials P are stacked and stored. In the vicinity of the paper feed cassette 50, a pickup roller 13 for feeding the recording material P from the paper feed cassette 50 to the transport path 12 one by one is provided.

  Further, the conveyance path 12 arranged in the vertical direction on one side of the copying machine main body 100 extends to a paper discharge tray 14 provided on the upper surface of the main body 100, and in the middle thereof, a pair of paper feed rollers 15. A registration roller pair 16, a fixing device 17 having a fixing roller 17a and a pressure roller 17b, and a paper discharge roller pair 18 are provided.

  Next, an image forming operation by the color copying machine having the above configuration will be described.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate in the direction of the arrow in FIG. 1 at a predetermined process speed in each of the image forming units 1M, 1C, 1Y, and 1BK, and these photosensitive drums 2a to 2d. Are uniformly charged positively by the primary chargers 3a to 3d. The laser scanner unit 40 emits a laser beam modulated by a color image signal for each color of the original image read by the image reading device 20 from a laser output unit 41, and the laser beam is emitted from a lens 42 and a plurality of mirrors. 43 and the lens 44, and are projected onto the surfaces of the photosensitive drums 2a to 2d, and electrostatic latent images corresponding to the color image signals of the respective colors are formed on the photosensitive drums 2a to 2d, respectively.

  First, magenta toner is adhered to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charged polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. The magenta toner image is rotationally driven in the direction indicated by the arrow in the primary transfer portion between the photosensitive drum 2a and the transfer roller 5a by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied. Primary transfer is performed on the intermediate transfer belt 8.

  The intermediate transfer belt 8 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred onto the magenta toner image on the intermediate transfer belt 8 at the primary transfer portion in the same manner as described above.

  Similarly, the yellow and black toner images formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1BK are respectively formed on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 8. In each primary transfer portion, the images are sequentially overlapped, and a full-color toner image is formed on the intermediate transfer belt 8. The transfer residual toner that is not transferred onto the intermediate transfer belt 8 and remains on the photosensitive drums 2a to 2d is removed by the drum cleaning devices 6a to 6d, and is transferred by a waste toner transfer means (not shown) to be transferred to each toner. The toner is collected as waste toner in a toner collecting container formed integrally with the supply devices 7a to 7d.

  On the other hand, one sheet of recording material P is fed from the sheet feeding cassette 50 to the transport path 12 by the pickup roller 13 and the pair of sheet feeding rollers 15, and this recording material P is the leading edge of the full color toner image on the intermediate transfer belt 8. Is conveyed to the secondary transfer portion by the registration roller pair 16 in accordance with the timing of reaching the secondary transfer portion between the secondary transfer counter roller 9 and the secondary transfer roller 11.

  Then, a full color toner image is transferred to the intermediate transfer belt by the action of the transfer electric field formed by the secondary transfer roller 11 to which the secondary transfer bias having the opposite polarity to the toner is applied to the recording material P conveyed to the secondary transfer unit. The secondary transfer is performed on the recording material P from 8 at the same time.

  Thus, the recording material P onto which the full-color toner image has been transferred is subjected to charge removal processing and electrostatically separated from the intermediate transfer belt 8, and then conveyed to the fixing device 17. In the fixing device 17, a full-color toner image is heated and pressed at the fixing nip portion between the fixing roller 17 a and the pressure roller 17 b to be thermally fixed on the surface of the recording material P, and the toner image is fixed. A series of image forming operations is completed when the recording material P is discharged onto the discharge tray 14 by the discharge roller pair 18. The secondary transfer residual toner that is not transferred onto the recording material P but remains on the intermediate transfer belt 8 is removed by a belt cleaning device (not shown), and is transported by a waste toner transport means (not shown) to be shown. It is collected as waste toner in a collection container.

  Although the present invention has been described with respect to an embodiment in which the present invention is applied particularly to a color copying machine, the present invention is applicable to any other image forming apparatus such as a printer or a facsimile.

[Image reading device]
Next, details of the configuration of the image reading apparatus 20 according to the present invention will be described with reference to the accompanying drawings.

  2 is a front sectional view of the image reading apparatus according to the present invention, FIG. 3 is a plan view of the image reading apparatus, and the illustrated image reading apparatus 20 includes a transparent contact glass 21 on which an unillustrated document is placed. A light source 22 that emits light toward an image reading position X (see FIG. 2) for reading an image of the document G placed on the contact glass 21, and a reflected light reflected at the image reading position X is further reflected. And a plurality of mirrors 23, 24, and 25 that change their directions, a lens 26 that collects the reflected light, and a CCD sensor 27 that is a light receiving element that reads the reflected light collected by the lens 26. Has been. Here, the light source 22 and the mirror 23 are supported by a first scanning frame body 28, and the mirrors 24 and 25 are supported by a second scanning frame body, and these first and second scanning frame bodies. Reference numerals 28 and 29 optically scan the document G placed on the contact glass 21 by moving below the contact glass 21 in the left-right direction (sub-scanning direction) in FIGS.

  Thus, as shown in FIG. 3, the light source 22 has a plurality of rectangular plate-shaped point light source packages 31 each having a point light source 30 such as an LED held in the center on a long light source substrate 32 in the main scanning direction ( Although the arrangement is arranged at appropriate intervals in the vertical direction of FIG. 3, the mounting structure will be described below with reference to FIGS. 4 to 6.

  4 is a side view of the first scanning frame showing the light source mounting structure, FIG. 5 is a side view of the positioning member, and FIG. 6 is a view in the direction of arrow A in FIG.

As shown in FIG. 4, on the first scanning frame 28, a positioning member 33 having a substantially U-shaped cross section that is long in the main scanning direction (the direction perpendicular to the plane of FIG. 4) has a plurality of screws 34 (FIGS. 4 and 4). Only one is shown in FIG. The positioning member 33 is attached to the first scanning frame 28 in a state where the positioning member 33 is positioned with high accuracy by a pin, a positioning protrusion (half-pressed) or the like (not shown). Further, the surface of the positioning member 33 is subjected to antireflection treatment.
A reflective plate mounting member 35 is mounted on the first scanning frame 28 at a position facing the positioning member 33, and the light emitted from the light source 22 is image-read on the reflective plate mounting member 35. A reflection plate 36 for condensing light at the position X is attached.

Incidentally, the light source substrate 32 is attached to the lower surface of the obliquely inclined upper wall 33a of the positioning member 33 with three screws 37 (see FIG. 6) that are inserted obliquely from below. Then, each point light source package 31 is brought into contact with the end surface 33 a-1 of the positioning member 33 on the upper surface of the portion of the light source substrate 32 protruding from the end surface 33 a-1 of the positioning member 33. It is mounted in a state positioned in the direction . Therefore, all the point light sources 30 held by these point light source packages 31 are positioned with high accuracy in the sub-scanning direction (left-right direction in FIG. 6) on the light source substrate 32 and are subjected to main scanning, as shown in FIG. Thus, the illuminance distribution on the document surface that receives the light emitted from these point light sources 30 is made uniform. As a result, the image of the original G placed on the contact glass 21 is read with high accuracy by the image reading device X, and a high-quality image is obtained by the color copying machine shown in FIG. 1 based on the read image data. Is stably formed.

  In the present embodiment, since the antireflection treatment is performed on the surface of the positioning member 33, the positioning member 33 hardly reflects the light from the light source 22, and the occurrence of flare is prevented.

  Further, in the present embodiment, the positioning member 33 and the light source 22 are detachably fastened to the first scanning frame body 28 with screws 34. Therefore, when the point light source 30 is replaced, the positioning member 33 and the light source 22 are replaced. Can be exchanged easily without deteriorating the illumination performance.

  In the present embodiment, the light source packages 31 are mounted on the light source substrate 32 one by one. However, a method of mounting a plurality of light source packages 31 previously positioned in the sub-scanning direction on the light source substrate 32. May be adopted.

1 is a front sectional view of an image forming apparatus (color copying machine) according to the present invention. 1 is a front sectional view of an image reading apparatus according to the present invention. 1 is a plan view of an image reading apparatus according to the present invention. It is a side view of the 1st scanning frame which shows the attachment structure of the light source of the image reader which concerns on this invention. It is a side view of the positioning member of the image reading apparatus according to the present invention. It is a figure of the arrow A direction of FIG. It is a figure which shows the light distribution of the subscanning direction of one point light source. It is a figure which shows the light distribution in the subscanning direction of three adjacent point light sources.

Explanation of symbols

1M, 1C, 1Y, 1BK Image forming unit (image forming means)
2a, 2b, 2c, 2d Photosensitive drums 3a, 3b, 3c, 3d Primary chargers 4a, 4b, 4c, 4d Developing devices 5a, 5b, 5c, 5d Transfer rollers 6a, 6b, 6c, 6d Drum cleaning devices 7a, 7b , 7c, 7d Toner supply device 8 Intermediate transfer belt 9 Secondary transfer counter roller 10 Tension roller 11 Secondary transfer roller 12 Conveyance path 13 Pickup roller 14 Paper discharge tray 15 Paper feed roller pair 16 Registration roller pair 17 Fixing device 17a Fixing roller 17b Pressure roller 18 Discharge roller pair 20 Image reading device 21 Contact glass 22 Light source 23, 24, 25 Mirror 26 Lens 27 CCD sensor 28 First scanning frame 29 Second operation frame 30 Point light source 31 Point light source package 32 Light source Substrate 33 Positioning member 33a Positioning member The upper wall 33a-1 end face 34 bis 35 reflector mounting member 36 reflecting plate 37 bis 40 laser scanner unit 50 the paper feed cassette 100 copier main body G document P recording material X image reading position of the positioning member

Claims (5)

A document image is provided by scanning a document surface with light emitted from the light source toward the document surface by arranging a plurality of point light source packages each holding a point light source on a light source substrate in a main scanning direction. In an image reading apparatus for reading
The light source substrate is attached to the lower surface of the upper wall of the positioning member, the point light source packages are placed on the upper surface of the portion of the light source substrate that protrudes from the end surface of the upper wall of the positioning member, and the end surface is the end surface of the positioning member. An image reading apparatus , wherein the point light source package is positioned in at least one direction by being mounted in a contacted and positioned state .
  The image reading apparatus according to claim 1, wherein a positioning direction of the point light source package by the positioning member is a reading sub-scanning direction.   The image reading apparatus according to claim 1, wherein an antireflection treatment is applied to a surface of the positioning member.   The image reading apparatus according to claim 1, wherein the positioning member is detachably fastened to the scanning frame together with the light source.   An image forming apparatus comprising: the image reading apparatus according to claim 1; and an image forming unit that forms an image on a recording material based on image data read by the image reading apparatus. .

Images