JP3455637B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital PPC or the like having a reading unit above a writing unit that performs image exposure on a photosensitive member by deflecting a beam by a deflector. The present invention relates to an image forming apparatus. 2. Description of the Related Art The configuration of a digital copying machine will be described as an example of an image forming apparatus. The digital copying machine shown in FIG. 1 includes an image reading device 11, a printer unit 12 having a laser beam scanning device, and an automatic document feeder 13. Although not shown in detail, the automatic document feeder 13 conveys the set documents one by one, sets them on the contact glass 14, and discharges the documents on the contact glass 14 after copying is completed. ing. As shown in FIG. 2, a document reading apparatus 11 includes a first carriage A equipped with a light source including an illumination lamp 15 and a reflecting mirror 16 and a first mirror 17, a second mirror 18 and a third mirror. And a second carriage B equipped with the first carriage 19. When reading the original, the first carriage A
Moves forward at a constant speed, and the second carriage B moves forward following the first carriage A at half the speed of the first carriage A, thereby optically moving the original on the contact glass 14. The first mirror 17, the second mirror 18 and the first mirror 17 scan the reflected light image obtained by scanning the original on the contact glass 14 by the illumination lamp 15 and the reflecting mirror 16.
An image is formed on the CCD sensor 22 by the lens 21 via the third mirror 19 and the color filter 20. CCD sensor 2
Reference numeral 2 photoelectrically converts the reflected light image of the formed document and outputs an analog image signal, whereby the document is read. Then, after the image reading is completed, the first carriage A and the second carriage B return to the home position. It is also possible to read a color original by using a three-line CCD having R (red), G (green), and B (blue) filters as the CCD sensor. An analog image signal from the CCD sensor 22 is converted into a digital image signal by an analog / digital converter, and various image processing (binarization, multi-level conversion, gradation processing, conversion) is performed by an image processing board 23. Doubling processing, editing processing, etc.). In the printer section 12, an image carrier (hereinafter referred to as a photosensitive drum) 25 composed of a photoreceptor is rotated by a driving section during a copying operation and is uniformly charged by a charging device 26. The digital image signal subjected to the image processing is sent to a semiconductor drive plate (not shown), and the image exposure using the digital signal is performed by the laser beam scanning device 27 to form an electrostatic latent image. Then, the electrostatic latent image formed on the photosensitive drum 25 is developed by the developing device 28. The paper feeders 33 to 35 feed the transfer paper from a selected one of them to the registration roller 36, and the transfer paper is sent out by the registration roller 36 in synchronization with the image on the photosensitive drum 25. The visible image formed on the photosensitive drum 25 is transferred onto the transfer paper by the transfer device 30. The transfer paper is then separated from the photosensitive drum 25 by the separation device 31, conveyed by the conveyance device 37, and fixed on the image by the fixing device 38, and then discharged onto the tray 39 as a copy. Also, the photosensitive drum 2
5 is cleaned by the cleaning device 32 after the transfer paper is separated to remove residual toner. As shown in FIG. 3, a laser beam scanning device 27 serving as a writing unit converts a laser beam emitted from a semiconductor laser in a semiconductor laser unit 40 into a parallel light beam by a collimating lens in the semiconductor laser unit 40. The light beam is changed and passed through an aperture provided in the semiconductor laser unit 40 to be shaped into a light beam having a predetermined shape. This light beam is compressed in the sub-scanning direction by the cylindrical lens 41 and enters the polygon mirror 42. The polygon mirror 42 has an accurate polygonal shape, and is driven by a polygon motor 43 to rotate in a certain direction at a certain speed. Polygon mirror 42
Are the rotation speed of the photosensitive drum 25, the writing density of the laser beam scanning device 27, and the polygon mirror 4.
2 is determined by the number of surfaces. Cylindrical lens 41
From the polygon mirror 42 is deflected by the reflection surface of the polygon mirror and is incident on a lens group 44 such as an fθ lens. The lens group 44 applies the scanning light having a constant angular velocity from the polygon mirror 42 to the photosensitive drum 25.
The laser beam from the lens group 44 is imaged on the photosensitive drum 25 via the reflecting mirror 45 and the dust-proof glass 46. The lens group 44 also has a surface tilt correction function. Also, lens group 4
The laser beam having passed through 4 is reflected by the synchronization detection mirror 47 outside the image area and guided to the synchronization detection sensor 48, and the detection output of the synchronization detection sensor 48 provides a synchronization signal serving as a reference for cueing in the main scanning direction. Can be [0008] The laser beam scanning device 27, which is a writing unit, is usually hermetically sealed so as not to be contaminated by dust, gas or the like. For this purpose, a dedicated cover is generally installed. In this case, the elements (polygon motor 42,
When a serviceman tries to access the inside of the laser beam scanning device 27 at a user site for trouble replacement of the semiconductor laser in the semiconductor laser unit 40, the synchronization detection sensor 48, etc.), cleaning of dirt on the optical system, and the like. It is necessary to remove the laser beam scanning device 27 from the main body of the image forming apparatus and then open the above-mentioned cover. However, the laser beam scanning device 2 which is a writing unit
Removing 7 from the image forming apparatus main body is a relatively troublesome operation, and a solution has been desired. Further, when the inside of the writing unit is accessed, a safety switch is provided to prevent a maintenance person from inadvertently seeing the laser beam with the eyes or directly viewing the laser beams with the eyes. Or a cautionary decal is stuck. However, it is also conceivable that a malfunction of the safety switch may occur, and it is not possible to completely guarantee that the maintenance person will definitely turn off the safety switch or take necessary actions by visually checking the decals. However, there is no possibility that the user will be injured by touching the polygon mirror rotating at high speed, and a solution to this point has been desired. The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus capable of accessing and maintaining the inside of the writing unit without removing the writing unit from the image forming apparatus main body. And Further, according to the present invention, the laser unit is inevitably stopped when an attempt is made to access the writing unit, even if there is carelessness of a maintenance person such as the presence or absence of a safety switch, malfunction when the safety switch is present, and forgetting to switch off. It is an object of the present invention to provide an image forming apparatus capable of reliably preventing injuries and the like. According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a light source; and a rotating device for deflecting a beam emitted from the light source. A polygon mirror, a lens for correcting the beam deflected and scanned by the rotary polygon mirror and forming an image on a photoconductor, and a position corresponding to the lens while accommodating the light source, the rotary polygon mirror, and the lens there Ri Do from the housing is at least open, and writing means you exposure scans on the photosensitive member, a position for mounting said housing of said writing means, corresponding to the part that the opening of the housing A device body having a portion provided with an opening at a position, attached to the device body on the side opposite to the writing means, and closing the opening of the device body. And a bracket to which a control board for controlling the driving of the rotary polygon mirror of the writing means is mounted. Embodiments of the present invention will be described below with reference to the drawings. In the following, portions common to the related art will be denoted by the same reference numerals, and redundant description will be omitted. FIG. 4 is an exploded perspective view showing an enlarged main part of the image forming apparatus according to one embodiment of the present invention, and FIG. 5 is a front sectional view of the same. In the writing unit 1 of the present embodiment, each of the above-described optical elements is accurately held in a writing unit housing 2 having an open top. Reference numeral 3 in the figure denotes a synchronization detection plate for obtaining a signal for performing cueing in the main scanning direction of an image. The upper cover of the writing unit 1 is the scanner unit base 4 of the document reading device 11.
And an opening 5 for maintenance of the writing unit 1.
Is provided at a position corresponding to the lens group 44 in the writing unit housing 2. A bracket 7 for mounting the control board 6 is screwed and fixed to the opening 5 from the side opposite to the writing unit housing 2 (upper side in the figure), and together with the scanner unit base 4 of the document reading device 11, the writing unit 1 The writing unit housing 2 also serves as a cover. Of course, the bracket 7 completely covers the opening 5 in a state where the bracket 7 is fixed to the scanner unit base 4 with screws. If the seal member is interposed between the bracket 7 and the scanner unit base 4, the dustproofness is further improved. Although not shown in FIG. 4, the control board 6 and the polygon motor driver 8 are connected by a harness 9. The harness 9 is connected to the control board 6 by a connector 9a on one end side, is guided into the writing unit housing 2 through the opening 5, and when the bracket 7 is fixed to the scanner unit base 4 by screws, the bracket 7 and the scanner unit are connected. It is sandwiched between the base 4. The connector 9b on the other end of the harness 9 is connected to the driver of the polygon motor driver 8 in the writing unit housing 2. The polygon motor driver 8 drives the polygon motor 40 by receiving information on the number of rotations and ON / OFF of the polygon mirror 42 from the control board 6. When the above-mentioned connection of the harness 9 is disconnected, the circuit configuration of the polygon motor 42 is stopped. Therefore, the length of the harness 9 is not allowed to have much margin. That is, at the time of maintenance, it is not necessary to remove the writing unit 1 from the apparatus main body. If the control board 6 and the cover 7 are removed while being attached to the scanner unit base 4, the inside of the writing unit 1 can be accessed through the opening 5, The maintenance work becomes very easy for the operator. However, if the bracket 7 is to be removed from the scanner unit base 4 without removing the connector 9a connected to the control board 6, the harness 9 will be stretched, making it difficult to remove the bracket 7 as it is. Therefore, when the worker removes the bracket 7 for maintenance in the writing unit housing 2, the harness 9 must be removed from the control board 6 without fail, and the polygon mirror 42 must be stopped.
It means that the access, are so late can advance to and reliably prevented from such a serious injury by touching erroneously the polygon mirror 42 rotating at a high speed during maintenance. Of course, since the writing unit 1 does not have a dedicated upper cover, the number of parts and the cost can be reduced. If the layout is such that the fastening members (such as screws) for removing the bracket 7 are hidden by the harness 9, the operator must be able to control the control board even if the length of the harness 9 is not too short. 6 can be detached. Normally, various control boards such as an image processing board, a scanner control board, a laser control board, and a polygon motor control board are installed inside the document reading apparatus 11, and therefore, these control boards are installed. A bracket is also required inside the document reading device 11. The above embodiment is an example in which the bracket for mounting the polygon motor control board is used. Although not shown, a control board and a harness connected to the semiconductor laser unit 40 may be adopted instead of the control board and the harness connected to the polygon motor driver 8 as in the above configuration. In this way, the worker was exposed to laser light during maintenance .
It is possible to prevent the eyes from being disturbed by looking at the eyes. Of course, in combination with the above-described embodiment, both an accident due to rotation of the polygon mirror and an obstacle due to exposure to laser light can be prevented. As described above, in the image forming apparatus according to the first aspect, the cover of the housing of the writing unit is replaced by a part of the main body of the apparatus and does not have a dedicated housing cover. Therefore, it is possible to access the inside of the writing unit from the opening of the apparatus main body without removing the writing unit from the main body, and there is an effect that the operation becomes very easy. Also, by using the bracket of the control board as a cover of the housing of the writing unit, the number of components can be reduced, and the cost can be reduced and the layout in the height direction can be saved. [0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view conceptually showing a digital copying machine as an example of an image forming apparatus. FIG. 2 is an enlarged sectional view conceptually showing an image reading device of the digital copying machine of FIG. FIG. 3 is a perspective view conceptually showing a laser beam scanning device which is a writing unit of the digital copying machine shown in FIG. FIG. 4 is an exploded perspective view showing an enlarged main part of the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a front sectional view of the same. [Description of Signs] 1 Writing unit 2 Writing unit housing 3 Synchronous detection plate 4 Scanner unit base 5 Opening 6 Control board 7 Bracket 8 Polygon motor driver 9 Harness 9a Connector 9b Connector 40 Semiconductor laser unit 42 Polygon mirror 44 Lens group 45 Reflecting mirror 46 dustproof glass

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/00 550 G03G 21/16-21/18 G03G 15/00 107 G03G 15/04-15/04 120 B41J 3/00 G02B 26/10

Claims (1)

(57) [Claim 1] A light source, a rotary polygon mirror for deflecting a beam emitted from the light source, and a beam deflected and scanned by the rotary polygon mirror is corrected on a photosensitive member. exposure and lens for imaging, the light source, Ri Do from the housing position corresponding to the lens is at least open while housing the rotary polygon mirror and the lens, on the photoreceptor
Writing means you scan, a position for mounting said housing of said writing means, at a position corresponding to a part that the opening of the housing, an apparatus body having a portion provided with an opening, to the device body And a bracket attached to the opposite side of the writing means to close the opening of the device body and to which a control board for controlling the driving of the rotary polygon mirror of the writing means is mounted. Image forming device.