KR100327241B1 - Device for detecting position of photosensitive belt of image forming apparatus - Google Patents

Abstract

PURPOSE: A device for detecting the position of a photosensitive belt of an image forming apparatus is provided to prevent an erroneous operation of a steering device due to a local defect at the edge of the photosensitive belt. CONSTITUTION: A device for detecting the position of a photosensitive belt(10) of an image forming apparatus includes a base(51), a guide(53), a lever(57), an elastic biasing member, and a detector. The guide has a guide face coming into contact with one side of the photosensitive belt and rotates according to displacement of the photosensitive belt in the direction of the width of the photosensitive belt. Both ends of the lever are respectively hinge-connected with the guide and the base such that the guide rotates with respect to the base. The elastic biasing member elastically biases the guide to contact with one side of the photosensitive belt. The detector senses the quantity of movement of the guide to detect the displacement of the photosensitive belt in the direction of the width of the belt.

Description

Photosensitive belt position sensing device for image forming device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive belt position detecting device for an image forming apparatus that detects a change in position of a photosensitive belt traveling in a sub-scanning direction in a main scanning direction, and in detail, is not affected by local defects of a photosensitive belt edge. A photosensitive belt position detecting device for an image forming apparatus is improved in structure.

In general, an image forming apparatus such as a laser printer or a copying machine forms a latent electrostatic image by scanning a laser beam on a photosensitive medium, develops it with a toner of a predetermined color using a developing unit, and transfers it onto printing paper for printing. Device.

Referring to FIG. 1, a general image forming apparatus includes a photosensitive belt 10 wound around a driving roller 12, a transfer backup roller 14, and a steering roller 31 installed in a main body thereof to rotate a predetermined track.

And around the photosensitive belt 10, an erasing lamp 15 for erasing the surface potential formed on the photosensitive belt 10, a charger 17 for charging the photosensitive belt 10 whose surface potential is reset to a predetermined potential, and a photosensitive member. A plurality of laser scanning units (LSUs) 20 for scanning the laser beam on the belt 10 to form an electrostatic latent image corresponding to each color and a plurality of developing units 19 for developing a portion where the electrostatic latent image is formed are installed. do.

In the image forming apparatus provided as described above, the photosensitive belt 10 is wound around each of the rollers 12, 14 and 31, so that the lengths of the rollers 12, 14 and 31 are changed. It meanders in the main scanning direction of the LSU 18. Therefore, the image forming apparatus employing the photosensitive belt 10 includes a photosensitive belt steering apparatus 30 for correcting the meandering of the photosensitive belt 10, and a scanning timing for detecting the meandering and image area of the LSU 20. It includes a photosensitive belt position detection device 40 for determining.

Referring to FIG. 2, the conventional photosensitive belt position sensing device causes the light scanned by the laser scanning unit 20 to travel past the edge of the photosensitive belt 10 in the main scanning direction so that the main injected light is directly applied to the photosensitive belt. It is designed to detect the change of position in the main scanning direction. Here, the laser scanning unit 20 includes a light source 21 for irradiating laser light to a photosensitive belt edge portion and an area corresponding to an electrostatic latent image, and a beam deflector 23 such as a rotating face mirror for deflecting the irradiated light. And a lens element 25 for adjusting the line width of the scanning beam and correcting the aberration, and a reflecting mirror 27 for causing the scanned light to be incident substantially perpendicular to the plane of the photosensitive belt 10.

The light scanned by the laser scanning unit 20 is scanned through the edge of the photosensitive belt 10 to one side of the non-image area 10b and the image area 10a.

The photosensitive belt position detecting means 40 includes a refractive prism 41 for refracting the scanning light directed toward the edge of the photosensitive belt 10 to be incident almost perpendicularly to the edge portion of the photosensitive belt 10. It is disposed on the rear surface includes a photodetector 43 that is refracted through the refractive prism 41 and receives the incident light passing through one side of the edge of the photosensitive belt 10 to sense the position of the photosensitive belt 10.

When there is no defect in the edge portion of the photosensitive belt 10, the photosensitive belt position detecting means 40 configured as described above is directed toward the main scanning direction of the photosensitive belt 10 according to the amount of light received by the photodetector 43. The position change of can be detected normally. Accordingly, when the meandering occurs in the main scanning direction, the steering apparatus 30 may be operated to correct the meandering.

On the other hand, the photosensitive belt 10 has local defects D1 and D2 at the edges as shown in FIG. 3A due to contact between peripheral components in manufacturing and use. In this case, even when the photosensitive belt 10 is traveling in a normal orbit without meandering, as shown in FIG. 3B, when the optical scanning is performed at the local defect D1 position of the edge, the photosensitive belt 10 is left of the drawing. Detected as meandering. Accordingly, the steering device 30 is an arrow There is a problem of meandering correction in the direction.

In addition, the start position of the photosensitive belt 10 image region 10a after a predetermined time from the time when the light scanned by the laser scanning unit 20 and received by the photodetector 43 is shielded by the photosensitive belt 10. (SP). This effective starting position SP is a boundary between the image region 10a and the non-image region 10b, and in a normal case, forms a straight line in the sub-scanning direction. On the other hand, in the case where there is a local defect D1 at the edge of the photosensitive belt 10 as described above, the start position SP1 is changed to cause an image tip deformation.

Accordingly, the present invention has been made in view of the above problems, and is intended for an image forming apparatus in which the meander correction of the photosensitive belt due to local defects of the photosensitive belt edge and the image leading deformation of the effective light scanning start position are not caused. It is an object of the present invention to provide a photosensitive belt position sensing device.

1 is a schematic view showing a general image forming apparatus.

Figure 2 is a schematic perspective view showing a laser scanning unit and a photosensitive belt position detection device of a conventional image forming apparatus.

3A and 3B are schematic diagrams for explaining image tip deformation due to local defects of the photosensitive belt edge when the conventional photosensitive belt position sensing device is employed.

Figure 4 is a schematic perspective view showing a photosensitive belt position detection device for an image forming apparatus according to an embodiment of the present invention.

5 is a schematic view showing an operating state of a photosensitive belt position detecting device for an image forming apparatus according to an embodiment of the present invention.

Figure 6 is a schematic perspective view showing a photosensitive belt position detection device for an image forming apparatus according to another embodiment of the present invention.

7 is a schematic plan view showing an example of the lever rotation angle sensor shown in FIG.

<Explanation of symbols for the main parts of the drawings>

10 ... Photosensitive belt 20 ... Laser injection unit 30 ... Steering device

51, 71 Base 53, 73 Guide member 53a Guide groove

53b ... guide surface 55 ... sensing protrusion 57,77 ... lever member

58,78 Torsion spring 60 Photodetector 80 Angle of rotation sensor

81 ... first electrode 83 ... resistor 85 ... second electrode

In order to achieve the above object, the present invention, in order to determine the width of the meandering direction of the photosensitive belt wound around the plurality of rollers and pivoted in the sub-scanning direction and / or the scanning timing of the light scanned by the laser scanning unit, A photosensitive belt position detecting device for an image forming apparatus, the position detecting device comprising: a base; A guide member having a guide surface in contact with one side of the photosensitive belt and rotated according to the widthwise displacement of the photosensitive belt; A lever member hinged to both ends of the base and the guide member so that the guide member is rotated with respect to the base; Elastic bias means for elastically biasing the guide member to be in contact with one side of the photosensitive belt; And sensing means for sensing the displacement of the photosensitive belt by sensing the movement amount of the guide member.

Hereinafter, exemplary embodiments of the photosensitive belt position detecting apparatus for an image forming apparatus according to the present invention will be described in detail.

4 and 5, the photosensitive belt position detecting apparatus for an image forming apparatus according to an embodiment of the present invention includes a base 51 and a guide member 53 rotated according to the widthwise displacement of the photosensitive belt 10. ), An elastic bias that elastically biases the lever member 57 to rotate the guide member 53 with respect to the base 51, and the guide member 53 to be in contact with one side of the photosensitive belt 10. And means for sensing the displacement of the photosensitive belt 10 by sensing the movement amount of the guide member 53.

The photosensitive belt 10 is wound around a plurality of rollers (12, 14, 31 of FIG. 1) and is turned in the sub scanning direction, and the main scanning direction of the light scanned by the laser scanning unit (20 of FIG. 1), that is, the photosensitive belt ( 10) meander in the width direction.

The guide member 53 includes a guide groove 53a formed to be inserted so that the side portion of the photosensitive belt 10 is fitted. The inner surface of the guide groove 53a is a guide surface 53b in contact with one side of the photosensitive belt 10. Since the guide surface 53b is in linear contact with the edge of the photosensitive belt 10, even if there are local defects D1 and D2 at the edge, the guide surface 53b is not affected by the local defect.

Both ends of the lever member 57 are hinged to each of the base 51 and the guide member 53 so that the guide member 53 is rotated according to the widthwise displacement of the photosensitive belt 10.

The elastic bias means elastically biases the guide member 53 such that the guide member 53 is rotated while being in contact with one side of the photosensitive belt 10. To this end, as the elastic bias means, a torsion spring 58 installed to be caught by the stoppers 51a and 77a formed on the base 51 and the lever member 57 may be employed. In addition, a tension spring, a compression spring, or the like may be adopted as the elastic bias means.

The sensing means detects the displacement of the photosensitive belt 10 by sensing the movement amount of the guide member 53. To this end, the sensing means includes a sensing protrusion 55 and a photodetector 60 formed on one side of the guide member 53. The sensing protrusion 55 is formed at one side of the guide member 53 and moved together with the guide member 53. As illustrated, the sensing protrusion 55 blocks the light L scanned by the laser scanning unit 20 according to the widthwise displacement of the photosensitive belt 10. In addition, the sensing protrusion 55 may be configured to reflect the incident light L by further including a reflective coating or a reflective member on a surface opposite to the light L. The photodetector 60 is fixedly installed on the sensing protrusion 55, and partially blocked by the sensing protrusion 55 of the incident light L to receive light incident through the periphery thereof. . Here, the widthwise displacement of the photosensitive belt 10 may be known according to the amount of light received through the photodetector 60. When detecting the widthwise displacement of the photosensitive belt 10 using the light reflected from one surface of the sensing protrusion 55, the photodetector 60 is fixedly installed under the sensing protrusion.

As described above, the configured photosensitive belt position detecting device is a local coupling in which the edge of the photosensitive belt 10 is drawn locally when the photosensitive belt 10 is not meandered in the width direction, as shown by the solid line of FIG. 5. Even when including (D1, D2), the guide member 53 is not rotated. Therefore, the amount of light received by the photodetector 60 is not changed and the light scanning start position SP with respect to the image area 10a of the photosensitive belt 10 does not change. Therefore, the straightness of the front end position SP of the scanning line in the sub-scanning direction can be greatly improved.

On the other hand, when the photosensitive belt 10 meanders as shown by the dotted line of FIG. 5, the guide member 53 is rotated to correspond to the meandering degree of the photosensitive belt 10 to receive the photodetector 60. The amount of light to be changed. In this case, the steering device (30 in Fig. 1) is operated to indicate the meandering correction direction indicated by the dashed-dotted line. Correct it with

6 and 7, the photosensitive belt position detecting apparatus for an image forming apparatus according to another exemplary embodiment of the present invention includes a base 71 and a guide member 73 rotated according to the widthwise displacement of the photosensitive belt 10. ), An elastic bias that elastically biases the lever member 77 to rotate the guide member 73 with respect to the base 71, and the guide member 73 to be in contact with one side of the photosensitive belt 10. And means for sensing the displacement of the photosensitive belt 10 by sensing the movement amount of the guide member 73. Here, the base 71, the guide member 73, the lever member 77, and the elastic bias means include the base 51, the guide member 53, described above with reference to FIGS. 4 and 5. Since the lever member 57 and the elastic bias means are substantially the same, their detailed description is omitted.

The present embodiment is characterized in that the structure of the sensing means is changed. That is, the sensing means according to the present embodiment includes a lever rotation angle detection sensor 80 for detecting the rotation angle of the lever member 77 according to the rotation of the guide member 73.

The lever rotation angle sensor 80 detects a rotation angle of the lever member 77 with respect to the base 71, and calculates a widthwise displacement of the photosensitive belt 10 therefrom.

As an example of the lever rotation angle sensor 80 may be used a variable resistor as shown in FIG. The variable resistor has a fixed first electrode 81, a second electrode 85 provided to move in conjunction with the rotation of the projection (77a) protruding at one end of the lever member 77, and the first and The resistor 83 is positioned between the second electrodes 81 and 85. Here, the contact position of the second electrode 85 and the resistor 83 is different depending on the rotation angle of the lever member 77. Therefore, the resistance value between the first electrode 81 and the second electrode 85 is varied, and the voltage value therebetween ( v _o ) Changes. On the other hand, the variable resistor is only one example of the lever rotation angle detection sensor 80, the lever rotation angle detection sensor 80 as a conventional photoelectric rotation angle sensor, a semiconductor sensor using a hall IC, rotation A pressure sensor using a pressure change according to the angle may be employed.

As described above, the photosensitive belt position sensing device for an image forming apparatus according to the present invention configured to accurately detect edges by employing a guide member movably mounted in the widthwise movement of the photosensitive belt while being in line contact with one side of the photosensitive belt. Therefore, even if there is a local defect at the edge of the photosensitive belt, it is possible to prevent the malfunction of the steering apparatus and the deformation of the image leading start position due to the local defect.

Claims (3)

An image forming apparatus for sensing the widthwise meandering degree of the photosensitive belt wound around the plurality of rollers and turning in the sub-scanning direction and / or the timing of scanning the light scanned by the laser scanning unit. In the photosensitive belt position detection device for A base; A guide member having a guide surface in contact with one side of the photosensitive belt and rotated according to the widthwise displacement of the photosensitive belt; A lever member hinged to both ends of the base and the guide member so that the guide member is rotated with respect to the base; Elastic bias means for elastically biasing the guide member to be in contact with one side of the photosensitive belt; And detecting means for detecting a displacement in the width direction of the photosensitive belt by sensing a movement amount of the guide member. The method of claim 1, wherein the sensing means, A sensing protrusion formed on one side of the guide member and moved together with the guide member; A photodetector fixedly installed around the sensing protrusion, the photodetector scanning at the laser scanning unit and receiving light partially reflected by the sensing protrusion and / or light incident through the sensing protrusion periphery; A photosensitive belt position detecting device for an image forming apparatus, characterized in that. The method of claim 1, wherein the sensing means, And a lever rotation angle detection sensor for detecting a rotation angle of the lever member according to the rotation of the guide member.