JP4476047B2 - Optical writing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical writing device and an image forming apparatus including the optical writing device.

  For example, an electrophotographic image forming apparatus such as a laser printer, a digital copying machine, or a laser fax machine irradiates the surface of a photoconductor with a laser beam (light beam) and scans the laser beam on the photoconductor. An optical writing device for forming an electrostatic latent image is provided. In such an optical writing device, a laser beam emitted from a laser light source (light source) is deflected by a rotating polygon mirror and scanned on the photosensitive member, and usually in the middle of the optical path of the laser light. A plate-like glass formed long along the scanning direction is arranged. The glass is disposed at an angle α in the cross section. By changing the angle α or changing the thickness of the glass, the amount of curve of the scanning line (laser scanning line) by the laser beam on the photoreceptor is changed. Is adjusted (see, for example, Patent Document 1).

  Further, Patent Document 2 discloses an optical writing device that adjusts the amount of curvature of a scanning line by bending a long plastic lens in the sub-scanning direction.

JP-A-11-287966 JP 2002-182145 A

  However, in the case of the optical writing device disclosed in Patent Document 1, as described above, the inclination angle of the glass provided in the middle of the optical path between the polygon mirror and the photosensitive member and the thickness dimension of the glass are changed. The amount of curve of the scanning line can be adjusted with this, but since the glass as described above is provided in the scanning optical system in the optical housing, there is a problem that the light use efficiency is reduced by that amount, and the inclination of the glass is reduced. Since a mechanical mechanism for adjustment is required, there is a problem that the cost increases accordingly.

  In the optical writing device disclosed in Patent Document 2, the amount of curvature of the scanning line is adjusted by bending a long plastic lens in the sub-scanning direction. When the lenses are integrated into one sheet, it is difficult to bend the lens.

  An object of the present invention is to make it easy to adjust the amount of curvature of a scanning line by a light beam emitted from a light source.

According to a first aspect of the present invention, there is provided an optical writing apparatus in which a plurality of optical members for irradiating a corresponding photosensitive member with scanning lines formed by light beams emitted from a plurality of light sources are disposed in an optical housing. A holding member that holds a reflecting mirror that is one of the optical members arranged on the optical path of the beam, and a substantially central portion along the longitudinal direction of the reflecting mirror are provided to adjust the deflection amount of the reflecting mirror. A scanning line curve adjusting unit, and the scanning line curve adjusting unit pressurizes the reflecting mirror so as to bend initially in one of a concave or convex direction with respect to an incident direction of the light beam. The pressurizing means and the reflecting mirror are deflected in a convex direction when the deflection due to the pressurization of the initial pressurizing means is concave, and the concave direction when the deflection due to the pressurization of the initial pressurizing means is convex. Adjust to bend Further comprising a pressure adjusting means for, to feature.

According to a second aspect of the present invention, an electrostatic latent image written by irradiating a photosensitive member with a light beam by an optical writing device is developed to form a toner image, and the formed toner image is transferred to a recording medium. in forming apparatus, wherein the optical writing device is an optical writing device according to claim 1 Symbol placement.

According to the first aspect of the present invention, the reflection mirror held by the holding member is converted into a light beam incident on the reflection mirror by the scanning line curve adjusting means provided at a substantially central portion along the longitudinal direction of the reflection mirror. By adjusting the amount of deflection of the reflecting mirror so as to bend in a concavo-convex shape with respect to the incident direction, the amount of curvature of the scanning line can be adjusted. The adjustment of the amount of curvature of the scanning line is performed by bending a reflection mirror which is an existing optical member as an optical writing device and can be easily bent. An increase in cost and an increase in the size of the optical writing apparatus can be minimized, and the adjustment can be easily performed in any direction of unevenness by operating one scanning line curve adjusting means.
Further, the scanning line curve adjusting means can be realized with a simple configuration.

According to the second aspect of the present invention, it is possible to achieve the same effect as the invention of claim 1 Symbol placement.

  An embodiment of the present invention will be described with reference to the drawings. 1 is a longitudinal side view schematically showing a color printer as an image forming apparatus, FIG. 2 is a plan view showing an internal structure of the optical writing apparatus, FIG. 3 is a longitudinal side view showing the optical writing apparatus, and FIG. FIG. 5 is an exploded perspective view showing the scanning line curve adjusting means, FIG. 6 is a longitudinal side view for explaining the action of the initial pressurizing means in the scanning line curve adjusting means, and FIG. It is a longitudinal cross-sectional side view explaining the effect | action of the pressurization adjustment means in a linear curve adjustment means.

  As shown in FIG. 1, four printer engines 3 (3Y, 3C, 3M, and 3K) emit light beams at a substantially central portion inside a main body case 2 of a color printer 1 that is an image forming apparatus. An optical writing device 4 for irradiating a later-described photoconductor with a scanning line is provided, an intermediate transfer belt 5 and the like. Each printer engine 3 is a portion for forming a toner image, and is formed in the same structure. Each printer engine 3 uses a different color toner to form a different color toner image. In the description of the present specification and drawings relating to the printer engine 3 and the components of the printer engine 3, the subscripts Y, C, M, and K indicate yellow, cyan, magenta, and black, respectively. These subscripts are omitted as necessary.

  The mechanical structures of the four printer engines 3Y, 3C, 3M, and 3K are the same. Each printer engine 3 includes a photosensitive member 6 that is driven to rotate in the direction of an arrow, a charging unit 7 that is disposed around the photosensitive member 6, The developing unit 8 and the cleaning unit 9 are configured.

  The photoreceptor 6 is formed in a cylindrical shape and is rotationally driven by a drive motor (not shown), and a photosensitive layer is provided on the outer peripheral surface. By irradiating the outer peripheral surface of the photosensitive member 6 with the light beam emitted from the optical writing device 4, an electrostatic latent image corresponding to image data is written on the outer peripheral surface of the photosensitive member 6.

  The charging unit 7 is a conductive roller member formed in a roller shape, and a charging bias voltage is supplied to the charging unit 7 from a power supply device (not shown) so that the outer peripheral surface of the photoreceptor 6 is uniform. Charged.

  The developing unit 8 supplies toner to the photoreceptor 6. The supplied toner adheres to the electrostatic latent image written on the outer peripheral surface of the photoreceptor 6, whereby the electrostatic latent image on the photoreceptor 6 is visualized as a toner image.

  The cleaning unit 9 cleans residual toner adhering to the outer peripheral surface of the photoconductor 6 after the toner image formed on the photoconductor 6 is transferred to the intermediate transfer belt 5.

  The intermediate transfer belt 5 is a loop belt formed using a resin film or rubber as a base, and a toner image formed on the photoreceptor 6 is transferred to the intermediate transfer belt 5. This intermediate transfer belt 5 is supported by rollers 10, 11, 12 and is driven to rotate in the direction of the arrow. On the inner peripheral surface side (inside the loop) of the intermediate transfer belt 5, four transfer rollers 13 that transfer the toner image on each photoconductor 6 onto the intermediate transfer belt 5 are arranged. The toner images formed on the respective photoreceptors 6 are sequentially transferred onto the intermediate transfer belt 5 so that a color toner image is carried on the intermediate transfer belt 5. On the outer peripheral surface side (outside the loop) of the intermediate transfer belt 5, a cleaning unit 14 that cleans residual toner, paper dust, and the like attached to the outer peripheral surface of the intermediate transfer belt 5 is disposed.

  Below the four printer engines 3 and the optical writing device 4 in the main body case 2, a paper feeding cassette 15 in which the recording medium P is stacked and held is disposed. The recording media P stacked and held in the paper feed cassette 15 are separately fed by the paper feed roller 16 in order from the highest one.

  In the main body case 2, a transport path 17 is formed through which the recording medium P separated and fed from the paper feed cassette 15 is transported. On the conveyance path 17, a registration roller 18, a transfer roller 19, a fixing unit 20, a paper discharge roller 21, and the like are arranged.

  The registration roller 18 is a roller that is rotationally driven intermittently at a predetermined timing. By intermittently driving the registration roller 18, the recording medium P that has been transported to the position of the registration roller 18 and stopped is sent to a transfer position sandwiched between the intermediate transfer belt 5 and the transfer roller 19. The toner image on the intermediate transfer belt 5 is transferred to the recording medium P in the process in which the recording medium P passes this transfer position.

  The fixing unit 20 is a part that applies heat and pressure to the recording medium P to which the toner image has been transferred to melt the toner and fix the toner image on the recording medium P. The recording medium P on which the toner image is fixed by passing through the fixing unit 20 is discharged onto a paper discharge tray 22 formed on the upper surface of the main body case 2 by a paper discharge roller 21.

  Next, the optical writing device 4 will be described. The optical writing device 4 has an optical housing 23 in which an upper cover 23b is fixed to a lower case 23a, and light corresponding to image data of different colors (Y, C, M, K) is contained in the optical housing 23. A light source unit 24 (24Y, 24C, 24M, 24K), which is a light source that emits a beam (laser light), and various optical members for irradiating the photoconductor 6 with scanning lines by the light beam are accommodated. The optical member accommodated in the optical housing 23 includes an aperture 25 for tilt correction, a cylinder lens 26, a mirror 27, a polygon mirror 28, an imaging lens 29, and reflecting mirrors 30 and 31 (30Y, 31Y, 30C, 31C, 30M, 31M, 30K, 31K), a synchronization detection mirror 32, an imaging lens 33, a photoelectric element 35 mounted on the circuit board 34, and the like. The light source unit 24 includes a semiconductor laser that emits divergent light, a collimator lens that substantially collimates the divergent light emitted from the semiconductor laser, a semiconductor laser driving circuit board, and the like. The polygon mirror 28 is connected to a polygon motor 36 and rotates at high speed. The number of rotations of the polygon mirror 28 varies, but there are, for example, those exceeding 30000 rpm.

  In this color printer 1, image data input from a document reading device (scanner) or an image data output device (a personal computer, a word processor, a facsimile receiving unit, etc.) (not shown) is color-separated, and the color-separated image data of each color is obtained. Is converted into a signal for driving each light source unit 24, and a light beam is emitted from each light source unit 24 in accordance with the signal. The light beam emitted from each light source unit 24 is transmitted to the polygon mirror 28 via the surface tilt correction aperture 25, the cylinder lens 26, and the mirror 27 (however, only for the light beams emitted from the light source units 24Y and 24K). Finally, the polygon mirror 28 deflects and scans two light beams in two symmetrical directions.

  The light beams deflected and scanned in two symmetrical directions by the polygon mirror 28 pass through the imaging lens 29, are turned back by the two reflecting mirrors 30 and 31, and travel toward the photoreceptor 6 of each printer engine 3. To do. Then, the light beam that has traveled toward the photoconductor 6 is irradiated on the outer peripheral surface of the photoconductor 6 as a scanning line, whereby an electrostatic latent image is written on the outer peripheral surface of the photoconductor 6.

  The upper cover 23b of the optical housing 23 is formed with an opening 37 that is positioned at a position facing the photoconductor 6 of each printer engine 3 and that is elongated along the center line direction of the photoconductor 6. . A light-transmitting dustproof member 38 that allows the light beam to pass therethrough and prevents dust from entering the optical housing 23 is attached to these openings 37, and the light beam directed toward the photoreceptor 6 is transmitted through the light-transmitting dustproof member. Proceed through 38. As the translucent dustproof member 38, for example, flat glass is used.

  Of the light beam that has passed through the imaging lens 29, the light beam that has passed through both ends of the imaging lens 29 is folded back by the synchronization detection mirror 32, passes through the imaging lens 33, and is received by the photoelectric element 35. When the photoelectric element 35 receives light, a scanning start synchronization signal is output from the photoelectric element 35. Here, since the original meaning of the synchronization detection is to take a scanning timing, it is sufficient that the photoelectric element 35 is installed at a position where the light beam is received prior to the scanning. In order to detect a change in (or time), a photoelectric element 35 may be provided on the rear end side of the scan. In the present embodiment, a configuration is shown in which the synchronization detection mirror 32 and the photoelectric element 35 are arranged on both ends of the imaging lens 29 to synchronize before and after scanning.

  Next, the scanning line curve adjusting means 50 which is a characteristic part of the present invention will be described. The scanning line curve adjusting means 50 is a mechanism for adjusting the amount of curve of the scanning line on the photosensitive member 6, and is provided in the reflection mirrors 30Y, 31C, and 31M located on the Y, C, and M optical paths. Yes. In the present embodiment, the scanning mirror curvature adjusting means is not provided in the reflection mirror on the optical path of K serving as the reference color when matching the curvature of the scanning line of each color (Y, C, M, K). The configuration is such that the amount of curvature of the Y, C, and M scanning lines is adjusted to match the curvature of the K scanning lines. The structure of the scanning line curve adjusting means 50 provided in each of the reflection mirrors 30Y, 31C, 31M is the same. In FIGS. 4 to 7, the scanning line curve adjusting means 50 provided in the reflection mirror 31C is taken as an example. I will explain.

  The reflection mirror 31C is held by a mirror holder 51, which is a long holding member having a substantially U-shaped cross section. A holding bracket 52 and a leaf spring 53 are caulked to both ends of the mirror holder 51 in the longitudinal direction. The holding bracket 52 is a substantially U-shaped member, and claw portions 52a are formed at both ends. The leaf spring 53 is elastically brought into contact with one surface of the reflection mirror 31C, and the upper and lower ends of the other surface of the reflection mirror 31C are pressed against the claw portion 52a by this contact force, whereby the reflection mirror 31C is It is held by the mirror holder 51.

  The scanning line curve adjusting means 50 includes a pressure leaf spring 54 that is an initial pressure means positioned at a substantially central portion in the longitudinal direction of the mirror holder 51, and a pressure adjusting means 55.

  The pressure plate spring 54 has a substantially U-shaped cross-section, and claw portions 54a are formed at both upper and lower ends. The claw portions 54a are engaged with both upper and lower ends of the surface of the reflection mirror 31C where the light beam is incident. Thus, the substantially central portion in the longitudinal direction of the reflecting mirror 31C is pressurized in the direction of arrow A shown in FIGS. By this pressurization, the reflection mirror 31C is initially bent in a direction that is concave with respect to the direction of incidence of the light beam on the reflection mirror 31.

  The pressure adjusting means 55 is a mechanism for adjusting the pressure of the reflecting mirror 31C so as to bend the reflecting mirror 31C in the direction opposite to the direction of bending due to the pressing of the pressing plate spring 54, and is a pressure formed in a substantially M shape. The adjusting plate spring 55a, the plate nut 55b, and the adjusting screw 55c are used. The adjustment screw 55c passes through the mirror holder 51 and the pressure adjustment plate spring 55a and is screwed to the plate nut 55b. When the adjustment screw 55c is rotated, the plate nut 55b screwed to the adjustment screw 55c moves up and down along the adjustment screw 55c.

  Here, in the state shown by the solid lines in FIGS. 6 and 7, only the pressure of the pressure leaf spring 54 acts on the reflection mirror 31C, and the pressure of the pressure adjusting means 55 acts on the reflection mirror 31C. It shows a case that is not. When only the pressing force of the pressure leaf spring 54 acts on the reflection mirror 31, the reflection mirror 31C is concave with respect to the incident direction of the light beam to the reflection mirror 31C, that is, at both ends of the reflection mirror 31C. On the other hand, the central portion of the reflecting mirror 31C is initially maintained in a state where it is bent to a position that is retracted with respect to the incident direction of the light beam. In this case, the pressurizing adjustment leaf spring 55a is separated from the reflection mirror 31C as indicated by a solid line.

  When adjusting the curve amount of the scanning line, the adjustment screw 55c is turned from the state shown by the solid line in FIGS. 6 and 7, and the plate nut 55b screwed to the adjustment screw 55c is raised. Then, the pressurizing adjustment leaf spring 55a bends so that the central portion protrudes toward the reflecting mirror 31C, and eventually comes into contact with the reflecting mirror 31C as shown by the phantom line in FIG. 7, and in the longitudinal direction of the reflecting mirror 31C. The substantially central portion is pressed in the direction of arrow B. Thereby, the reflecting mirror 31C can be bent in a direction opposite to the bending direction by the pressing of the pressing plate spring 54 (a direction that is convex with respect to the incident direction of the light beam with respect to the reflecting mirror 31C). Then, the amount of deflection of the reflecting mirror 31C can be adjusted by adjusting the amount by which the adjusting screw 55c is turned and changing the raised position of the nut 55b, and the amount of bending of the scanning line can be adjusted.

  Therefore, the scanning line curve adjusting means 50 can bend the reflecting mirror 31C in any direction that is uneven with respect to the incident direction of the light beam incident on the reflecting mirror 31C. Then, by deflecting the reflecting mirror 31C in a direction that is concave or convex with respect to the incident direction of the light beam incident on the reflecting mirror 31C, the direction and amount of the scanning line curve on the photosensitive member 6 by the light beam. Can be adjusted arbitrarily.

  Here, the reflection mirror 31C that is bent to adjust the amount of curvature of the scanning line is an existing member as an optical member constituting the optical writing device 4, and a mirror holder as a member for bending the reflection mirror 31C. It is only necessary to add 51 and the scanning line curve adjusting means 50, and the cost increase accompanying the increase in the number of parts and the enlargement of the optical writing apparatus can be minimized. Further, it is possible to prevent the optical writing device 4 from increasing in size as the number of parts increases. Further, the reflection mirror 31C is a plate-like member that can be easily bent, and can easily adjust the amount of curvature of the scanning line.

  Since the reflection mirror 31C and the scanning line curve adjusting means 50 are held by the same mirror holder 51, even if the optical housing 23 is deformed or distorted with time, the reflection mirror 31C and the scanning line curve adjusting means 50 The relative position can be stably maintained over a long period of time. For this reason, the curve adjustment of the scanning line can be stably performed with time.

  In the present embodiment, the curvature of the scanning line of each color can be adjusted by matching the curvature of the scanning line of the other color (Y, C, M) with the curvature of the scanning line of the reference color (K). By eliminating the need for the scanning line curve adjusting means for adjusting the curve of the color scanning line, the cost of components can be reduced.

  It should be noted that scanning line curve adjusting means may be provided on the optical paths of the light beams of all colors (Y, C, M, K), and the amount of curve may be adjusted so that the scanning lines of all colors are linear. .

  Two reflecting mirrors 30 and 31 are arranged on the optical path of each light beam, and one of the reflecting mirrors (second reflecting mirrors 31Y, 30C, 30M, and 31K) has an inclination of the entire scanning line. A scanning line inclination adjusting means (not shown) for adjusting the above is provided. Although this scanning line inclination adjusting means is well known and is not shown, for example, a holder for holding the second reflecting mirrors 31Y, 30C, 30M, and 31K, and a second reflecting mirror 31Y provided on the holder. , 30C, 30M, and 31K can be configured by adjusting screws that adjust the height positions of both ends in the longitudinal direction. Then, the inclination of the reflection mirrors 31Y, 30C, 30M, and 31K can be adjusted by turning the adjusting screw, and thereby the inclination of the scanning line can be adjusted.

  Here, regarding the adjustment of the amount of curvature of the scanning line and the adjustment of the inclination of the scanning line by the Y, C, M light beams, the scanning mirror curvature adjusting means 50 for adjusting the amount of curvature is provided in the reflection mirrors 30Y, 31C, 31M, Since the scanning line inclination adjusting means is provided in the second reflecting mirrors 31Y, 30C, and 30M located on the optical path of each light beam, the scanning line curve adjustment and inclination adjustment are highly accurate without affecting each other. Can be done.

1 is a longitudinal side view schematically showing a color printer which is an image forming apparatus according to an embodiment of the present invention. It is a top view which shows the internal structure of an optical writing device. It is a vertical side view which shows an optical writing device. It is a top view which shows a scanning line curve adjustment means. It is a disassembled perspective view which shows a scanning line curve adjustment means. It is a vertical side view explaining the effect | action of the initial pressurization means in a scanning line curve adjustment means. It is a vertical section side view explaining the operation of the pressurizing adjusting means in the scanning line curve adjusting means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Optical writing apparatus 6 Photoconductor 23 Optical housing 24 Light source 30Y, 31C, 31M Reflective mirror, optical member 31Y, 30C, 30M, 31K 2nd reflective mirror, optical member 50 Scan line curve adjustment means 51 Holding Member 53 Initial pressurizing means 55 Pressure adjusting means

Claims (2)

In an optical writing apparatus in which a plurality of optical members for irradiating a corresponding photosensitive member with scanning lines by light beams emitted from a plurality of light sources are arranged in an optical housing,
A holding member that holds a reflecting mirror that is one of the optical members disposed on the optical path of each light beam;
Provided substantially central portion along the longitudinal direction of the reflection mirror, and a scanning line curvature adjusting means for adjusting the deflection amount of the previous SL reflecting mirror,
Have
The scanning line curve adjusting unit includes an initial pressurizing unit that pressurizes the reflective mirror so that the reflective mirror is initially bent in a concave or convex direction with respect to an incident direction of the light beam, and the reflective mirror, Pressurization adjusting means for adjusting the initial pressurizing means to bend in the convex direction when the pressurization is concave, and adjusting the initial pressurizing means to bend in the concave direction when the initial pressurizing means is deflected. With
An optical writing device. In an image forming apparatus that develops an electrostatic latent image written by irradiating a photosensitive member with a light beam by an optical writing device to form a toner image, and transfers the formed toner image to a recording medium.
Image forming apparatus, wherein the optical writing device is an optical writing device according to claim 1 Symbol placement.

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