JP5151899B2 - Scanning apparatus and image forming apparatus - Google Patents

Description

The present invention relates to a scanning device that performs writing with light on a surface to be scanned of an image carrier, and an image forming apparatus such as a digital copying machine, a laser printer, and a laser FAX using the device.

  In recent years, image forming apparatuses of the above type are required to perform high-speed printing and high-density writing. In order to satisfy such demands, there are laser scanners that have a high speed rotary polygon mirror and multi-beams that use an LDA (laser diode array) having a plurality of light emitting points. These means are effective means for achieving high-speed printing and high-density writing, but at the same time, the amount of heat generation increases in proportion to the increase in duty.

  Further, a scanning optical system using a plastic lens is currently the most mainstream in the optical system. Advantages include a lower cost and higher moldability than glass lenses. However, since the thermal expansion is higher than that of glass, the scanning line bends or tilts due to heat, and the main scanning magnification is liable to change, resulting in a deterioration in image quality.

  In order to solve such a problem, Patent Document 1 discloses that a rotating polygon mirror is installed in an air flow path formed by one round of an inner wall of a resin optical box, and heat is circulated by an air flow generated from the rotating polygon mirror. A configuration to be made is proposed. Although this method can reduce the heat generation of the entire optical box with an inexpensive structure, it is not suitable for high speed and high density because the thermal expansion of the resin optical box is large and the arrangement of each optical element varies. There is a drawback.

  Patent Document 2 discloses that an imaging optical element and a rotating polygon mirror are made of resin in order to reduce scanning line bending and fluctuation due to uneven temperature rise of the optical element due to heat generated with the rotation of the rotating polygon mirror. There has been proposed a configuration in which at least one of the imaging optical systems is held in a casing and disposed in the casing via a heat insulating sheet.

  However, this method is also unsuitable for high speed and high density as in the above-mentioned Patent Document 1, and further, there is a problem that the cost is increased because a heat insulating member is used.

  Furthermore, Patent Document 3 discloses a configuration in which a gap is provided between a case member that covers the rotary polygon mirror and a storage chamber that stores the case member, and air flows in and out through the ventilation means. Yes.

  In the apparatus of Patent Document 3, heat generated from the rotary polygon mirror can be radiated, but as a heat generation source of the scanning device, there are a light source, a control board of the rotary polygon mirror, and the like, without considering these heat generations. It is difficult to obtain effective heat dissipation only by heat radiation with the rotating polygon mirror alone. In addition, a drive system such as a fan is used as the ventilation means, and if air is allowed to flow into the storage chamber by the fan, dust or dust may adhere to the optical member, leading to image abnormalities. It was necessary to take measures to prevent cleaning and intrusion.

Furthermore, in Patent Document 4, in order to provide a laser scanning device capable of efficiently cooling the inside of the apparatus, the rotary reflection member control means rotates the rotary reflection member away from the rotary reflection member as viewed from the transmission lens side. Arranged on the side. And the structure which has the airflow reflection means which reflects the airflow which generate | occur | produced by rotation of a rotation reflection member in the direction of a rotation reflection member control means, and cools a control means with the airflow. However, when it is sufficiently driven in the sealed space, the temperature in the sealed space rises to a certain temperature, and there is a possibility that the image quality is deteriorated due to the thermal expansion of the plastic optical element.
JP 2000-267037 A JP 2008-70681 A Japanese Patent Laid-Open No. 2005-24894 JP 2008-168472 A

  SUMMARY An advantage of some aspects of the invention is that it provides a scanning device and an image forming apparatus capable of reducing deterioration in image quality due to heat.

To achieve the above object, the present invention includes a light source unit equipped with a light source, a deflecting unit having a rotary polygon mirror for deflecting and scanning the light emitted from said light source unit, control for controlling the driving of the rotary polygon mirror In a scanning device having a substrate and an optical housing that supports these members, heat from the light source unit, which is a heat source, the deflecting means, and the control substrate for the rotary polygon mirror along the outer surface side of the optical housing. A heat dissipating duct device in which a plurality of air flow passages for radiating heat are formed from the deflecting means side toward the light source side is provided, and the heat dissipating duct device is disposed downstream of one inlet into which the air flow enters. The air flow channel is divided into three air flow channels by partition fins erected on the outer surface of the optical housing, and the three air flow channels are the heat source, the light source, the deflecting means, and the air flow channel, respectively. Wherein is a straight outer control board a channel through which air flows, proposes a scanning device, wherein each including a radiating fins other than the partition wall fin.

In the present invention, it is advantageous that the height of the fin is high in the vicinity of the heat source.

In order to achieve the above object, the present invention provides an image forming apparatus that forms an electrostatic latent image on the surface to be scanned of an image carrier by the scanning device according to claim 1 or 2. suggest.

  According to the present invention, each heat source is cooled from the back side of the optical housing to increase heat dissipation efficiency, thereby suppressing thermal expansion of optical elements such as plastic lenses, and image fluctuations such as scanning line bending, inclination, and magnification fluctuation. Can be suppressed. In addition, high-speed printing and high-density writing can be achieved while suppressing image fluctuations.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a vertical sectional view showing an example of an image forming apparatus. The image forming apparatus shown in FIG. 1 has an image forming unit provided at substantially the center of the apparatus main body 1, and an original from which original information is read. A reading unit 2 and a sheet feeding unit 3 for feeding a recording material are arranged below.

  The image forming unit is provided with an image carrier 4 configured as a drum-shaped photosensitive member, and the image carrier 4 is rotated in the clockwise direction in FIG. The surface of the carrier is uniformly charged to a predetermined polarity. The charged portion is irradiated with laser light L of a signal that is optically modulated in accordance with image information read by the document reading device 2 from the laser scanning device 6. As a result, an electrostatic latent image is formed on the image carrier 4. This electrostatic latent image is visualized as a toner image by the developing device 7.

  On the other hand, the paper feed unit 3 is provided with a plurality of paper feed devices 20, and in the illustrated example, four paper feed devices are arranged. The paper feeding device 20 includes a paper feeding tray 21 that accommodates a recording material P made of transfer paper or a resin film, and a paper feeding roller 22, and one of the plurality of paper feeding devices 20 has a paper feeding device. The paper feed roller 22 is in contact with the uppermost recording material P of the recording material P selected and loaded on the paper feed tray 21 of the selected paper feeding device, and rotates, thereby rotating the uppermost recording material P. Is fed out from the paper feed tray.

  The fed recording material P is conveyed upward in FIG. 1 and further fed to the registration roller pair 24 by the feeding action of the conveyance roller 23. The recording material P hits the registration roller pair 24 and temporarily stops. Next, when the registration roller pair 24 starts rotating at a predetermined timing, the recording material P is conveyed toward the image carrier 4, and the toner image on the image carrier 4 is transferred to the recording material P by the transfer device 8. Is done. As described above, the registration device serves to send the recording material P to the image carrier at a predetermined timing so that the toner image formed on the image carrier is transferred to the recording material P.

  The transfer device 8 serves to transfer the toner image formed on the image carrier 4 to the recording material P sent out by the registration roller pair 24. Although various types of devices can be used as the transfer device 8, the illustrated transfer device 24 includes a plurality of support rollers and a transfer belt that is wound around these support rollers and driven to travel.

  The transfer residual toner remaining on the image carrier 4 after the transfer of the toner image is removed by the cleaning device 9, and the potential on the surface of the image carrier is initialized by a static eliminator (not shown).

  The recording material P conveyed to the transfer belt then passes through the fixing device 10, and at this time, the toner image transferred to the recording material P is fixed to the recording material P. The recording material P that has passed through the fixing device 10 is discharged to the discharge unit 11 and stacked there.

  As described above, the recording material P on which an image is formed on one side can be obtained. However, the illustrated image forming apparatus forms a toner image on the other side of the recording material P and the image on both sides. However, since the image formation on both sides is not the gist of the present invention, the description thereof will be omitted.

FIG. 2 is a cross-sectional view of the laser scanning device 6 according to the present invention as viewed from above.
In FIG. 2, reference numeral 30 denotes an optical housing, and reference numeral 31 denotes a laser diode unit (hereinafter referred to as an LD unit). The optical housing 30 is made of aluminum die-cast having good thermal conductivity. As shown in FIGS. 3 and 4, the LD unit 31 is an LD array 32a, 32b having at least one light emitting point as a light source, a collimating lens 33 having a function of converting divergent light into parallel light, and lighting control. An LD control board 34 (hereinafter referred to as LDB) is provided. The LD unit 31 is made by assembling these components, and is adjusted and completed as a submodule (FIG. 4). The light beams emitted from the LD arrays 32a and 32b pass through the collimating lens 33, and the aperture 35A cuts out the light beams in order to obtain a desired beam diameter on the surface to be scanned. The cut light beam is narrowed by the cylindrical lens 35B having power only in the sub-scanning direction. The narrowed light beam enters the rotary polygon mirror 37 of the deflecting means 36 through the incident mirror. As shown in FIG. 5, the deflection means 36 has a rotary polygon mirror 37 mounted on a motor drive board 38 and a polygon cover 39 covering the rotary polygon mirror 37. The rotation polygon mirror 37 is driven by a motor drive board. It is rotated by a motor (not shown) provided at 38. The motor for driving the rotary polygon mirror 37 is controlled by a control board 40 assembled to the optical housing 30 separately from the deflection means 36. The control board 40 in this example is an iron board, that is, the base part of the control board 40 is made of iron. However, the control board 40 may be made of a metal board such as aluminum or copper having good thermal conductivity. . However, iron is advantageous in that it is less expensive than aluminum or copper.

  The light beam deflected and scanned by the rotary polygon mirror 37 passes through the Fθ lens 41 having a function of scanning the surface to be scanned at a constant speed. The light beam that has passed through the Fθ lens 41 passes through the curved axis type toroidal lens 42 having a function of correcting the beam position in the sub-scanning direction, and forms an image on the surface to be scanned through the folding mirror and dust-proof glass. The material of the Fθ lens 41 and the curved axis type toroidal lens 42 is arbitrary, but in the present embodiment, it is a plastic lens. These optical elements are all assembled in the optical housing 30 described above.

  In the laser scanning device 6 configured as described above, three members serving as heat sources are the LD unit 31, the deflection unit 36 having the rotary polygon mirror 37, and the control substrate 40 that controls the rotation of the rotary polygon mirror 37.

  The present invention efficiently dissipates heat generated from the above three points, suppresses problems such as bending or inclination of the scanning line due to heat, and fluctuations in main scanning magnification, and lowering image quality. The preferred embodiment will be described below.

FIG. 6 is a perspective view showing the laser scanning device 6 of the present invention, and FIG. 7 is an explanatory view of the laser scanning device 6 viewed from the back side.
6 and 7, the laser scanning device 6 is provided with a heat radiating duct device 50 in which an air flow channel 54 through which an air flow from a fan 43 provided in the device main body 1 flows is formed. This heat radiating duct device 50 is provided so as to cover the LD unit 31, the deflecting means 36, the control board 40 and the optical housing 30 supporting the optical member described above (the lower surface side in FIG. 1). Is formed approximately at the center of one side in the longitudinal direction of the laser scanning device 6. Further, the outlet 52 of the heat radiating duct device 50 is provided on one side in the short direction on the side where the LD unit 31 of the laser scanning device 6 is provided.

  The heat dissipating duct device 50 has one inflow port 51 into which the airflow from the fan 43 enters, but the airflow passages formed therein have three airflow passages as shown by different tones in FIG. 54 a, 54 b, 54 c, and the air flows that have passed through the respective air flow passages 54 a, 54 b, 54 c are exhausted from the respective outlets 52 a, 52 b, 52 c. Further, the outlet 52 is shifted by 90 ° with respect to the airflow inflow direction of the inlet 51 of the heat radiating duct device 50, and therefore the three airflow channels 54a, 54b, 54c are changed in direction by approximately 90 ° in the middle thereof. . By bending the airflow passage in this way, it is possible to suppress cost increase due to enlargement of the image forming apparatus and improve the layout margin. Furthermore, if the bent shape is an R shape as shown in FIG. 6, the generation of vortices can be eliminated, the energy loss of fluid can be suppressed, and the reduction of heat dissipation efficiency can be suppressed.

  The three air flow paths 54 a, 54 b and 54 c are formed by partitioning with partition fins 55 that are formed integrally with the optical housing 30, that is, are erected on the back side of the optical housing 30. The three air flow paths 54a, 54b, 54c are arranged so as to radiate heat individually from the LD unit 31, the deflecting means 36, and the control board 40. In other words, the air flow channel 54a is arranged to pass directly under the LD unit 31, the air flow channel 54b of the deflecting unit 36, and the air flow channel 54c of the control board 36. The control board 40 is configured to dissipate heat individually.

  Since the laser scanning device 6 configured in this manner is provided with the individual air flow channels 54a, 54b, and 54c for the three heat sources, the fresh air is supplied to each heat source, so that each heat source Can be efficiently cooled. Further, since each air flow channel 54 a, 54 b, 54 c is formed by an aluminum die-cast partition fin 55 that is integral with the optical housing 30 and has good thermal conductivity, heat radiation from the partition fin 55 can be obtained. Further, in each of the air flow channels 54a, 54b, 54c, some heat radiating fins 56 formed integrally with the optical housing 30 other than the partition walls are provided, so that the cooling efficiency is further improved. Furthermore, as shown in FIG. 9, the partition fins 55 and the heat radiating fins 56 are formed so as to increase the height H of the fins in the vicinity of the heat source. With this configuration, the air flow contact in the vicinity of the heat source is achieved. The area can be increased and the cooling effect can be further enhanced.

  Thus, since the laser scanning device 6 of the present invention can efficiently cool the generated heat, the heat dissipation efficiency is increased, the thermal expansion of the optical element such as a plastic lens is suppressed, and the scanning line bends, tilts, magnification fluctuations, and other images. Variation can be suppressed. Furthermore, even a multi-beam scanning device that simultaneously scans a surface to be scanned with a plurality of light beams can achieve high-speed printing and high-density writing while suppressing image fluctuations.

  Although the image forming apparatus described in the above embodiment is for monochrome use, the present invention can naturally be applied to a color image forming apparatus. In this case, the laser scanning apparatus is a single casing known per se. A device capable of writing on four image carriers may be used.

1 is a vertical sectional view showing an example of an image forming apparatus according to the present invention. It is a lineblock diagram of a laser scanning device showing one embodiment of the present invention. It is a disassembled perspective view which shows LD unit of the laser scanning apparatus. It is a completion perspective view of LD unit. It is a disassembled perspective view which shows the deflection | deviation means of a laser scanning apparatus. It is a perspective view which shows the laser scanning apparatus provided with the thermal radiation duct apparatus. It is explanatory drawing which looked at the laser scanning device from the back side. It is explanatory drawing which shows the airflow flow path of a heat radiating duct apparatus. It is a side view which shows the fin of a heat radiating duct apparatus.

Explanation of symbols

4 Image carrier 6 Laser scanning device 30 Optical housing 31 LD unit 36 Deflection means 37 Rotating polygon mirror 40 Control board 50 Radiation duct device 54a, 54b, 54c Air flow channel 55 Bulkhead fin 56 Radiation fin

Claims (3)

A light source unit equipped with a light source, an optical housing supporting the deflection means having a rotary polygon mirror for deflecting and scanning the light emitted from said light source unit, a control board for controlling the drive of the rotary polygon mirror, these members A scanning device having:
A plurality of air flow paths for radiating heat from the light source unit, which is a heat source, the deflecting unit, and the control substrate for the rotary polygon mirror are directed from the deflecting unit side to the light source side along the outer surface side of the optical housing. radiator duct system is provided which is formed Te,
The heat dissipating duct device is divided into three air flow channels downstream of one inlet into which the air flow enters, and the plurality of air flow channels are separated by partition fins erected on the outer surface of the optical housing,
Each of the three air flow channels is a channel through which air flows directly outside the light source, the deflecting unit, and the control board, which are heat sources, and each includes a radiation fin other than the partition fins. In the scanning device of claim 1, a scanning device, characterized in that the height of the fins are formed taller at the heat source near. Image forming apparatus and forming an electrostatic latent image by scanning apparatus according to claim 1 or 2 in the surface to be scanned on the image bearing member.