Optical scanner and image forming apparatus

Abstract

To provide an optical scanner with which good dust resistance can be obtained, and an image forming apparatus.SOLUTION: An optical scanner is provided with a light source, a polygon scanner 33 such as a deflector that deflects and scans light from the light source, and an opening and closing member 90 that opens and closes an emission port 39 for emitting light from a housing 37 that houses optical elements arranged on an optical path of the light. During an exposure operation, the optical scanner opens the emission port 39 to allow emission of light to a photoreceptor, and releases heat inside the housing from the emission port 39 to prevent an increase in the temperature inside the housing. While the emission port 39 is opened, the optical scanner generates an air flow around the emission port 39 to inhibit entry of dust into the housing from the emission port 39.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an optical scanning device and an image forming apparatus. [Background technology]

[0002] Conventionally, an optical scanning device has been known that contains a light source, a deflector that deflects and scans light from the light source, and an optical element arranged on the optical path of the light, and that includes a housing having a cooling opening for cooling the inside, and an opening / closing member that opens and closes the cooling opening.

[0003] Patent Document 1 describes an optical scanning device in which a folding mirror that folds back light deflected and scanned by a deflector is used as an opening / closing member that opens and closes a cooling opening in a housing. When a latent image is written, the folding mirror closes the cooling opening, and when a non-latent image is written, the folding mirror opens the cooling opening, allowing heat inside the housing to escape through the cooling opening, thereby cooling the inside of the housing. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there was a problem with dust resistance. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides an optical scanning device comprising a housing that houses a light source, a deflector that deflects and scans light from the light source, and optical elements arranged on the optical path of the light, and has a cooling opening for cooling the interior, and an opening / closing member that opens and closes the cooling opening, characterized in that when the cooling opening is open, the device is provided with an airflow generating means that generates an airflow around the cooling opening to prevent dust from entering the housing through the cooling opening. [Effects of the Invention]

[0006] According to the present invention, good dust resistance can be obtained. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a copying machine as an image forming apparatus according to an embodiment of the present invention. [Figure 2] Hardware configuration diagram of a copier. [Figure 3] Schematic diagram of an exposure device. [Figure 4] FIG. 2 is a diagram illustrating a characteristic part of the exposure apparatus. [Figure 5] FIG. 3 is a schematic diagram of the exposure apparatus during exposure. [Figure 6] 10A and 10B are diagrams illustrating how airflow prevents dust from entering the housing through the emission port. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 4 is a plan view showing the airflow generating device when the exposure apparatus is not performing exposure operation. [Figure 10] FIG. 1 is a schematic diagram of an exposure apparatus provided with a temperature sensor that detects the temperature inside the housing. [Figure 11] FIG. 6 is a control flow diagram of the opening and closing control of the opening and closing member based on the temperature inside the housing detected by the temperature sensor. [Figure 12] FIG. 10 is a control flow diagram of the fan of the airflow generating device based on the detection result of the temperature sensor. [Figure 13] FIG. 10 is a schematic diagram of an exposure apparatus according to a first modified example. [Figure 14] FIG. 14 is an enlarged schematic view taken in the direction of arrow A in FIG. 13. [Figure 15] FIG. 10 is a schematic diagram of an exposure apparatus according to a second modification. [Figure 16] FIG. 1 is a schematic diagram illustrating an example of a full-color image forming apparatus. [Figure 17] 17 is a schematic diagram of a multi-color exposure device that exposes a Y-color photosensitive drum and an M-color photosensitive drum in the full-color image forming apparatus shown in FIG. 16. DETAILED DESCRIPTION OF THE INVENTION

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. Note that a person skilled in the art can easily modify or alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are included within the scope of the claims. The following description is an example of the best mode for carrying out the present invention and does not limit the scope of the claims.

[0009] FIG. 1 is a schematic diagram showing the general configuration of a copying machine as an image forming apparatus according to this embodiment. This copier 100 has a printer unit 110. The printer unit 110 has a photosensitive drum 1 as an image carrier, a charging device 2 that charges the surface of this photosensitive drum 1, and an exposure device 30 that is an optical scanning device that writes an electrostatic latent image on the charged surface of the photosensitive drum 1. It also has a developing device 17 that develops the electrostatic latent image with a developer to form a toner image on the photosensitive drum 1, a transfer device 9 that transfers the toner image on the photosensitive drum surface to transfer paper P as a transfer material, a separation claw 6, and a fixing device 40 that fixes the toner image transferred to the transfer paper P. It also has a photosensitive drum cleaning device 5 that cleans the surface of the photosensitive drum after the toner image has been transferred to the transfer paper P.

[0010] An original reading device 50 is disposed above the printer section 110. An original placed on a contact glass 52 of the original reading device 50 is illuminated by a light source 53 that moves rightward in FIG.

[0011] The reflected light image is reflected by a first mirror 54 which moves to the right together with the light source 53, and then reflected by a second mirror 55 and a third mirror 56 which move to the right at half the speed of the light source 53, before being incident on an image sensor 57. The image sensor 57 has an image sensor, such as a CCD, for reading the reflected light image from the original, and an imaging lens which forms the light image on the sensor.

[0012] The image signal read by this imaging element 57 is sent to the exposure device 30. Then, a light beam L optically modulated in accordance with the image signal read by the imaging element 57 is irradiated onto the surface of the photosensitive drum 1, and an electrostatic latent image corresponding to the image original is formed on the surface of the photosensitive drum.

[0013] The developing device 17 has a developing case 24 containing developer and a developing roller 12 rotatably supported therein, and carries and transports the developer on the circumferential surface of the developing roller 12 as it is rotated, and visualizes the electrostatic latent image formed on the photosensitive drum 1 by the developer as a toner image.

[0014] Although the developing device 17 uses a powdery two-component developer containing toner and carrier as the developer, a one-component developer not containing carrier can also be used.

[0015] On the other hand, one of the transfer sheets P stored in the plurality of paper feed cassettes 61, 62, and 63 is selected and fed in the direction of arrow A (here, it is assumed that the transfer sheet P in the paper feed cassette 61 is selected).

[0016] This transfer paper P is fed to the transfer device 9 by a pair of registration rollers 7. The transfer device 9 is equipped with a drive roller 9b around which a transfer belt 9a is wound, a driven roller 9c, a transfer roller 9d, etc. The transfer belt 9a is wound around the drive roller 9b, the driven roller 9c, and the transfer roller 9d so as to move in the direction of arrow B, and abuts against the surface of the photosensitive drum 1 at a transfer position S.

[0017] When the transfer paper P passes through the transfer position S, an electric field of a polarity opposite to the charge polarity of the toner is applied to the transfer roller 9d by a high voltage power supply. When a voltage is applied to the transfer roller 9d, a current flows from the transfer roller 9d through the transfer belt 9a to the drive roller 9b and driven roller 9c, and further through the transfer paper P to the photosensitive drum 1.

[0018] The applied voltage at this time is controlled so that a predetermined transfer current flows through the photosensitive drum 1. The transfer belt 9a is temporarily charged by the transfer roller 9d to which a voltage is applied, but the charge is removed by the drive roller 9b.

[0019] The transfer paper P sent out by the pair of registration rollers 7 is carried and transported on the transfer belt 9a, and passes through the transfer position S between the transfer belt 9a and the photosensitive drum 1 at a timing when it aligns with the toner image on the photosensitive drum 1.

[0020] At this time, a voltage of the opposite polarity to the charged polarity of the toner on the photosensitive drum 1 is applied to the transfer roller 9d arranged on the back side of the transfer belt 9a, and the toner image on the photosensitive drum 1 is electrostatically transferred to the surface of the transfer paper P. The transfer paper P onto which the toner image has been transferred is then carried and conveyed by the transfer belt 9a via the separation claw 6, and is then fed to the fixing device 40 after leaving the transfer belt 9a.

[0021] In the fixing device 40, the transfer paper P passes between the heating roller 40a and the pressure roller 40b, and the toner image is fixed onto the transfer paper P by the action of heat and pressure. The transfer paper P is then discharged onto the paper discharge tray 80 as a copy paper by a pair of paper discharge rollers 70. On the other hand, any untransferred toner remaining on the surface of the photosensitive drum after the toner image has been transferred is removed from the surface of the photosensitive drum by a cleaning device 5 .

[0022] The cleaning device 5 has a cleaning brush roller 3, a cleaning blade 4, a flicker 25, a cleaning case 26, and a toner discharge screw 27, which is a toner discharge member disposed at the bottom of the cleaning case 26.

[0023] Untransferred toner on the surface of the photosensitive drum is scraped off by the cleaning brush roller 3 and cleaning blade 4, which are rotated in the direction of the arrow in the cleaning device 5, and is collected in a cleaning case 26 of the cleaning device 5. A flicker 25 is disposed so as to come into contact with the cleaning brush roller 3 on the side opposite the photosensitive drum, and as the cleaning brush roller 3 rotates, the toner adhering to the cleaning brush roller 3 is knocked off by the flicker 25. The toner collected in the cleaning case 26 is transported to a waste toner path by a toner discharge screw 27, and is transported to a waste toner container through a waste toner container.

[0024] After cleaning, the surface of the photosensitive drum is initialized by being neutralized by the neutralization device, and is then uniformly charged by the charging device 2. The above-mentioned operation is then carried out, and the toner image newly formed on the surface of the photosensitive drum is transferred onto the next transfer paper P.

[0025] Furthermore, some of the background toner on the surface of the photosensitive drum is transferred and adheres to the surface of the transfer belt 9a, and if this is left unattended, the toner will adhere to the back surface of the transfer paper P sent onto the transfer belt 9a, staining the transfer paper P. The toner adhering to the surface of the transfer belt 9a is removed by the belt cleaning device 8.

[0026] The developing device 17 includes a developing case 24 which includes therein a developing roller 12, a paddle 13, a developer stirring member 14, a doctor blade 11 which is a regulating member, and the like.

[0027] A two-component developer is stored in the developing device 17, and the developer is supplied to the developing roller 12 while being stirred by a developer stirring member 14 and a paddle 13. The amount of developer on the surface of the developing roller is kept constant by a doctor blade 11 that regulates the amount of developer.

[0028] FIG. 2 is a diagram showing the hardware configuration of the copier 100. As shown in FIG. As shown in FIG. 2, the copying machine 100 includes a controller 910, a short-range communication circuit 920, an engine control unit 930, an operation panel 940, and a network I / F 950.

[0029] The controller 910 controls the entire copying machine 100, for example, controlling drawing, communication, input from the operation panel 940, and the like. The controller 910 has a CPU 901, which is the main part of the computer, a system memory (MEM-P) 902, a north bridge (NB) 903, a south bridge (SB) 904, an ASIC (Application Specific Integrated Circuit) 906, a local memory (MEM-C) 907, which is a storage unit, an HDD controller 908, and an HD 909, which is also a storage unit. The NB 903 and the ASIC 906 are connected by an AGP (Accelerated Graphics Port) bus 921.

[0030] The CPU 901 is a control unit that performs overall control of the copier 100. The NB 903 is a bridge that connects the CPU 901 with the MEM-P 902, the SB 904, and the AGP bus 921, and includes a memory controller that controls reading and writing to the MEM-P 902, a PCI (Peripheral Component Interconnect) master, and an AGP target.

[0031] The MEM-P 902 comprises a ROM 902a, which is memory for storing programs and data that realize the functions of the controller 910, and a RAM 902b, which is used for expanding the programs and data and as a drawing memory during memory printing. The programs stored in the RAM 902b may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, CD-R, or DVD.

[0032] The SB 904 is a bridge for connecting the NB 903 with PCI devices and peripheral devices. The ASIC 906 is an integrated circuit (IC) for image processing applications that has hardware elements for image processing and serves as a bridge connecting the AGP bus 921, PCI bus 922, HDD controller 908, and MEM-C 907. The ASIC 906 includes a PCI target and AGP master, an arbiter (ARB) that forms the core of the ASIC 906, a memory controller that controls the MEM-C 907, multiple direct memory access controllers (DMACs) that perform image data rotation using hardware logic, and a PCI unit that transfers data between the printer unit 110 and the ASIC 906 via the PCI bus 922. A Universal Serial Bus (USB) interface or an Institute of Electrical and Electronics Engineers 1394 (IEEE 1394) interface may also be connected to the ASIC 906.

[0033] The MEM-C907 is a local memory used as an image buffer for copying and a code buffer. The HD909 is a storage for storing image data, font data used during printing, and forms. The HD909 controls the reading and writing of data from and to the HD909 under the control of the CPU901. The AGP bus 921 is a bus interface for a graphics accelerator card proposed to speed up graphics processing. By directly accessing the MEM-P902 at high throughput, the graphics accelerator card can be made faster. Further, the short-distance communication circuit 920 includes a short-distance communication circuit 920a. The short-distance communication circuit 920 is a communication circuit such as NFC or Bluetooth (registered trademark).

[0034] The engine control unit 930 controls the image forming operation by controlling the printer unit 110. The printer unit 110 includes various devices for forming an image on the transfer paper P, such as a drive unit that rotates the photosensitive drum 1, a developing device 17, and an exposure device 30. The printer unit 110 also includes an image processing unit that performs error diffusion, gamma conversion, etc.

[0035] The operation panel 940, which serves as an operation input unit, includes a panel display unit 940a and an operation unit 940b. The panel display unit 940a displays current setting values, selection screens, etc., and is configured with a touch panel or the like that receives input from the operator. The operation unit 940b includes a numeric keypad that receives setting values ​​for image formation conditions such as density setting conditions, and a start key that receives a copy start instruction.

[0036] Copier 100 can sequentially switch between the document box function, printer function, and facsimile function using the application switching key on operation panel 940. When the document box function is selected, the mode switches to document box mode, when the printer function is selected, the mode switches to printer mode, and when the facsimile mode is selected, the mode switches to facsimile mode.

[0037] The network I / F 950 is an interface for performing data communication using a communication network. The short-range communication circuit 920 and the network I / F 950 are electrically connected to the ASIC 906 via a PCI bus 922.

[0038] FIG. 3 is a schematic diagram of an exposure apparatus 30. As shown in FIG. The exposure device 30 includes a light source 31, an incident optical system 32, a polygon scanner 33, a first scanning lens 34, a second scanning lens 35, and a folding mirror 36. These are housed in a housing 37. The housing 37 has a box-like shape with an open top, and the top is covered with a cover member 38 to prevent dust from entering the housing. The incident optical system 32 includes a collimator lens that converts a diverging light beam into a parallel light beam, an aperture that shapes the parallel light beam, and a cylindrical lens that focuses the shaped light beam.

[0039] The polygon scanner 33 as a deflector includes a polygon mirror 33 a which is a rotary polygonal mirror having a regular polygonal prism shape, a polygon motor 33 b which rotates and drives the polygon mirror 33 a, and the like, and is attached to a bottom wall 37 a of the housing 37 .

[0040] A light beam emitted from the light source 31 passes through an incident optical system 32 and then enters a rotating polygon mirror 33a. The light beam L that enters the polygon mirror 33a is deflected in the main scanning direction (a direction corresponding to the axial direction on the surface of the photosensitive drum) while being reflected by the reflecting mirror of the polygon mirror 33a. Next, the light beam L that has been deflected in the main scanning direction by the polygon mirror 33a at a constant angular velocity passes through a first scanning lens 34 and a second scanning lens 35 and enters a folding mirror 36. The light beam L that has been folded by the folding mirror 36 then exits from an exit port 39 provided in the bottom wall of a housing 37 and is scanned at a constant speed on the surface of the photosensitive drum 1.

[0041] During operation of the polygon scanner 33, the polygon mirror 33a rotates at high speed, generating heat at the bearing of the polygon scanner 33 that supports the rotation axis 5c of the polygon mirror. Conventionally, the light beam exit port 39, through which the light beam is emitted from the housing 37 toward the photosensitive drum 1, is sealed with dustproof glass, creating a sealed interior of the housing 37. Because the housing is sealed, there is no escape route for heat during operation of the polygon scanner 33, causing the temperature inside the housing 37 to rise. This temperature rise causes thermal expansion of the housing 37 and other components, changing the orientation of optical elements held within the housing, such as the light source 31, the incident optical system 32, and the scanning lens. This can result in image defects due to misalignment of the scanning position of the light beam L on the photosensitive drum 1. Furthermore, the temperature rise inside the housing can also cause malfunctions of the polygon scanner 33. Therefore, it is necessary to prevent image defects or operational defects caused by temperature rises inside the housing by slowing down the rotation speed of the polygon mirror 33a or by stopping the exposure operation until the temperature inside the housing drops when the temperature inside the housing exceeds a predetermined temperature, which may result in reduced productivity.

[0042] Therefore, in this embodiment, the emission opening 39 of the housing 37 is made openable so that heat inside the housing can be released through the emission opening 39. Hereinafter, the characteristic features of this embodiment will be described with reference to the drawings.

[0043] Fig. 4 is a diagram illustrating the characteristic parts of the exposure device 30. Fig. 4 shows a non-exposure state where the polygon mirror is not rotationally driven and the polygon scanner is not in operation.

[0044] In this embodiment, a light beam emitting portion 37b protruding diagonally downward and to the right in the drawing is provided at the end (the right end in the drawing) of the bottom wall portion 37a of the housing 37 opposite to the side where the polygon scanner 33 is arranged. An exit port 39a serving as a cooling opening is formed at the tip of this light beam emitting portion 37b.

[0045] In this embodiment, an opening / closing member 90 is provided to open and close the exit port 39. The opening / closing member 90 is provided with an air receiving portion 90a that extends from the exit port 39 and receives airflow that flows along a bottom wall portion 37a of the housing 37, which will be described later. As shown in Fig. 4, when the polygon scanner 33 is not operating, i.e., during non-exposure, the opening / closing member 90 closes the exit port 39 by the biasing force of a torsion spring or the like. Because the exit port 39 is closed by the opening / closing member 90 during non-exposure, it is possible to prevent dust from entering through the exit port 39 and to prevent dust from adhering to optical elements such as the incident optical system 32 and the scanning lens.

[0046] FIG. 5 is a schematic diagram of the exposure apparatus showing the exposure time when the polygon scanner is operating. As shown in Figure 5, during exposure, an airflow generating device 120 (see Figure 7), which will be described later, generates an airflow along the outer surface of the bottom wall 37a of the housing 37. The airflow along the outer surface of the bottom wall 37a of the housing 37 flows from the polygon scanner side end of the housing 37 toward the light beam emitting portion 37b. When the airflow reaches the light beam emitting portion 37b, the direction of the flow is changed by the light beam emitting portion 37b, and the airflow flows along the outer surface of the light beam emitting portion 37b. As the airflow flows along the outer surface of the light beam emitting portion 37b, the airflow flows in the same direction as the emission direction of the light beam L emitted from the emission port 39.

[0047] The airflow flowing in the emission direction along the outer surface of the light beam emission portion 37b hits the air receiving portion 90a of the open / close member 90, and the wind pressure of the airflow causes the open / close member 90 to rotate from a closed position, in which the emission port 39 is closed, as shown by the dashed line in the figure, to an open position, as shown by the solid line in the figure. This opens the emission port 39, allowing the light beam L to be emitted from the emission port 39 toward the photosensitive drum 1. The open / close member 90, which has moved to the open position, is held in the open position by the wind pressure of the airflow flowing in the emission direction around the emission port 39, and the light beam L emitted from the emission port 39 is not blocked by the open / close member 90 during the exposure operation.

[0048] Furthermore, by opening the exit port 39, heat generated inside the housing due to the high-speed rotation of the polygon mirror 33a can be released through the exit port 39, suppressing a rise in temperature inside the housing. This suppresses thermal expansion of the housing and other components due to a rise in temperature inside the housing, suppresses changes in the attitudes of optical elements such as the light source 31, incident optical system 32, and scanning lens, and suppresses image defects due to misalignment of the scanning position, etc. Furthermore, malfunction of the polygon scanner 33 due to a rise in temperature inside the housing can be suppressed.

[0049] Unlike this embodiment, in which the housing is open to release heat when the polygon scanner 33 is not operating (i.e., not in exposure mode), the housing is sealed during exposure, when the temperature inside the housing rises, and the temperature rise inside the housing is not suppressed. In particular, during continuous printing, the sealed state inside the housing continues, and there is a risk that the temperature inside the housing will become high.

[0050] In contrast, in this embodiment, the housing is opened to release heat during exposure operation, which is the operation of the polygon scanner 33 when the temperature inside the housing rises. Therefore, compared to systems that open the housing to release heat during non-exposure operation, the temperature inside the housing can be suppressed, and the inside of the housing can be prevented from becoming too high even during continuous printing. This makes it possible to suppress image defects and malfunctions of the polygon scanner due to thermal expansion of the housing, compared to systems that open the housing during non-exposure operation to release heat after the temperature inside the housing rises.

[0051] Furthermore, during exposure, the polygon mirror 33a rotates at high speed, generating noise such as wind noise. In this embodiment, the exit port 39a, located at the end of the housing 37 opposite the side where the polygon scanner 33 is located (the right end in the figure), is used as a cooling opening, and the cooling opening is located a predetermined distance away from the polygon scanner 33. This makes it possible to suppress the operating noise of the polygon scanner leaking from the open exit port 39. Furthermore, the exit port 39 used as a cooling opening is located at the tip of the light beam exit portion 37b, which protrudes diagonally downward and to the right in the figure, from the bottom wall portion 37a. This configuration also makes it possible to suppress the operating noise of the polygon scanner from leaking from the open exit port 39. Furthermore, a soundproof wall may be provided in the housing 37 to suppress the operating noise of the polygon scanner from leaking from the exit port 39.

[0052] In this embodiment, as shown in FIG. 5, the airflow flows along the bottom wall 37a of the housing 37 to which the polygon scanner 33 is attached. This airflow cools the bottom wall 37a of the housing 37, and the heat from the polygon scanner 33 is efficiently dissipated to the outside of the housing via the bottom wall 37a of the housing 37. As a result, the temperature rise inside the housing can be effectively suppressed. As described above, the airflow flows along the bottom wall 37a of the housing 37, and then flows in the emission direction along the light beam emission portion 37b. This flow of air in the emission direction prevents dust D from entering the housing through the open emission port 39, as shown in FIG. 6.

[0053] When the exposure operation is completed, the air flow along the bottom wall 37a of the housing 37 is stopped. As a result, the opening / closing member 90 is rotated by a means for positioning the opening / closing member 90 in the closed position, such as a torsion spring, to close the light outlet 39. This makes it possible to prevent dust from entering through the light outlet 39 when the exposure operation is not in progress.

[0054] In this embodiment, the open / close member 90 is opened and closed by airflow, but it may also be opened and closed by a driving means such as a solenoid or a motor. Opening and closing the open / close member 90 by a driving means such as a solenoid or a motor allows the open / close member 90 to be positioned in the open position more stably during exposure operations than when the open / close member 90 is opened and closed by airflow. This has the advantage of reliably preventing the light beam L from being blocked by the open / close member 90. On the other hand, opening and closing the open / close member 90 by airflow has the advantage of reducing the number of parts and making the device less expensive than when the open / close member 90 is opened and closed by a driving means.

[0055] Next, the airflow generating device 120, which is an airflow generating means for generating an airflow that flows along the bottom wall portion 37a of the housing, will be described. FIG. 7 is a schematic plan view of the airflow generating device 120. As shown in FIG. The airflow generating device 120 has a fan 121 and a duct 122. The fan 121 is provided on the rear side of the copying machine 500 as shown in Fig. 8, and is provided so as to take air from the outside of the machine into the inside of the machine.

[0056] 7, duct 122 has a first duct portion 122a for directing airflow to exposure device 30, a second duct portion 122b for directing airflow to fixing device 40, and a relay duct portion 122c for directing air taken in by fan 121 to second duct portion 122b. Airflow generating device 120 also has a shutter member 123 for blocking the flow of air to first duct portion 122a.

[0057] 7 shows the airflow generating device 120 during exposure operation, during which the shutter member 123 is located in the retracted position. Therefore, part of the outside air that flows from the fan 121 to the duct 122 passes through the first duct portion 122a and is blown out from the outlet of the first duct portion 122a towards the exposure device 30. The airflow blown out from the outlet of the first duct portion 122a flows along the bottom wall portion 37a of the exposure device 30, as shown in FIG.

[0058] Meanwhile, the remainder of the outside air that flows from fan 121 to duct 122 passes through relay duct portion 122c and flows to second duct portion 122b, and is blown out from the outlet of second duct portion 122b toward fixing device 40. This causes fixing device 40 to be air-cooled.

[0059] FIG. 9 is a plan view showing the airflow generating device 120 when the exposure device 30 is in a non-exposure operation. When the exposure operation of the exposure device 30 is completed, the shutter member 123 is driven to move from the retracted position shown in Fig. 7 to the blocking position shown in Fig. 9. This blocks the flow of air into the first duct portion 122a, and stops the air flow through the exposure device 30.

[0060] On the other hand, even after the exposure operation of the exposure device 30 is completed, the fan 121 continues to rotate to cool the fixing device 40, and air continues to be blown out from the outlet of the second duct portion 122b toward the fixing device 40. Then, when the temperature of the fixing device 40 becomes equal to or lower than a specified temperature, the rotation of the fan 121 is stopped.

[0061] As shown in FIG. 10, it is preferable to control the timing at which the opening / closing member 90 is moved to the closed position based on the temperature inside the housing detected by a temperature sensor 93 provided inside the housing.

[0062] FIG. 11 is a control flow diagram of the opening and closing control of the opening and closing member based on the temperature inside the housing detected by the temperature sensor 93. 11, upon receiving a print command, the engine control unit 930, which is a control means, rotates the fan 121 and moves the shutter member 123 from the closed position to the retracted position. This generates an airflow along the outer surface of the bottom wall 37a of the housing 37 via the first duct portion 122a, and the wind pressure of the airflow moves the opening / closing member 90 from the closed position to the open position (S1).

[0063] When the exposure operation is completed (YES in S2), the temperature sensor 93 detects the temperature inside the housing. If the temperature inside the housing is equal to or lower than threshold A (YES in S3), there is no need to release heat inside the housing, so the shutter member 123 is moved from the retracted position to the closed position. This stops the inflow of air into the first duct portion 122a, and stops the airflow along the outer surface of the bottom wall portion 37a of the housing 37. As a result, the opening / closing member 90 moves from the open position to the closed position, and the emission port 39 is closed (S4).

[0064] On the other hand, if the temperature inside the housing exceeds threshold A (YES in S3), the opening / closing member 90 is moved to the closed position after a specified time has elapsed. Specifically, after a specified time has elapsed since the exposure operation ended, the shutter member 123 is moved from the retracted position to the blocking position, and the air flow to the exposure device is stopped.

[0065] In this way, when the temperature inside the housing exceeds threshold A, air continues to flow along the outer surface of bottom wall 37a of housing 37 for a specified time even after the end of exposure, and opening / closing member 90 remains in the open position even after the end of exposure, releasing heat inside the housing through outlet 39. This effectively reduces the temperature inside the housing. Furthermore, even after the end of exposure, the airflow along the outer surface of bottom wall 37a of the housing cools bottom wall 37a of the housing, allowing heat from polygon scanner 33 to be efficiently dissipated from bottom wall 37a of the housing.

[0066] The specified time may be set to a uniform value regardless of the temperature inside the housing detected by the temperature sensor 93, or may be set based on the difference between the temperature inside the housing and the threshold value A. After the exposure operation, the temperature inside the housing may be constantly monitored by the temperature sensor 93, and when the temperature sensor 93 detects that the temperature inside the housing is equal to or lower than the threshold value A, the shutter member 123 may be moved from the retracted position to the shielding position.

[0067] Furthermore, the rotation speed of the fan 121 of the airflow generating device 120 may be controlled based on the detection result of the temperature sensor 93 to control the flow rate of the airflow that flows along the outer surface of the bottom wall portion 37a of the housing 37.

[0068] FIG. 12 is a control flow diagram for controlling the rotation speed of the fan 121 of the airflow generating device 120 based on the detection result of the temperature sensor 93. When the engine control unit 930 receives a print command, it starts rotating the fan 121 (S11). It also moves the shutter member 123 from the closed position to the retracted position, generating an airflow along the outer surface of the bottom wall 37a of the housing 37, and the wind pressure of the airflow moves the opening / closing member 90 from the closed position to the open position.

[0069] If the temperature inside the housing detected by the temperature sensor 93 exceeds threshold B (NO in S12), the rotation speed of the fan 121 is increased by a predetermined value (S14). Increasing the rotation speed of the fan 121 increases the flow rate and wind pressure of the airflow along the outer surface of the bottom wall 37a of the housing 37. This improves the cooling efficiency of the bottom wall 37a of the housing 37 by the airflow, allowing heat from the polygon scanner to be efficiently dissipated from the bottom wall 37a, and suppressing a rise in temperature inside the housing. Furthermore, increasing the wind pressure of the airflow allows the opening / closing member 90 to be opened more widely, thereby increasing the aperture ratio of the radiation outlet 39. This allows heat inside the housing to be efficiently released through the radiation outlet 39, effectively suppressing a rise in temperature inside the housing.

[0070] On the other hand, if the temperature inside the housing detected by the temperature sensor 93 is equal to or lower than threshold B (YES in S12), the fan 121 is rotated at a specified rotation speed (S13). This specified number is set to be equal to or higher than the rotation speed at which the wind pressure of the airflow along the outer surface of the bottom wall 37a of the housing 37 can position the open / close member 90 in the open position. When the temperature inside the housing is equal to or lower than threshold B, the rotation speed of the fan 121 is reduced compared to when the temperature exceeds threshold B, thereby achieving power savings compared to when the fan 121 is always rotated at a high rotation speed. In addition, wind noise from the fan 121 can be reduced, resulting in a quieter device. Then, when the exposure operation is completed and the temperature of the fixing device becomes equal to or lower than the specified value (YES in S14, YES in S15), the rotation of the fan 121 is stopped.

[0071] In the above description, the rotation speed of the fan is controlled to adjust the flow rate of the air flowing along the outer surface of the bottom wall portion 37a of the housing 37, but the amount of shielding of the first duct portion 122a of the shutter member 123 may also be adjusted to adjust the flow rate of the air flowing along the outer surface of the bottom wall portion 37a of the housing 37.

[0072] Next, a modification of this embodiment will be described.

[0073] [Variation 1] FIG. 13 is a schematic diagram of exposure apparatus 30A of Modification 1, and FIG. 14 is an enlarged schematic diagram seen from the direction of arrow A in FIG. In this first modification, a pair of airflow guide plates 92 are provided as airflow guide means around the mounting location of the polygon scanner 33 on the outer surface of the bottom wall portion 37a of the housing 37.

[0074] 14, each airflow guide plate 92 is composed of an inclined portion 92a inclined with respect to the airflow direction and a parallel portion 92b parallel to the airflow direction, with the inclined portion 92a located upstream of the parallel portion 92b in the airflow direction. The inclined portion 92a is inclined so that the distance between it and the inclined portion of the other airflow guide plate becomes narrower as it goes downstream in the airflow direction.

[0075] The airflow (see FIG. 7) blown out from the outlet of the first duct portion 122a of the airflow generating device 120 is guided by the inclined portions 92a of the pair of airflow guide plates 92 to the polygon scanner attachment location on the bottom wall portion 37a of the housing 37. This allows the airflow blown out from the outlet of the first duct portion 122a of the airflow generating device 120 to efficiently flow to the polygon scanner attachment location on the bottom wall portion 37a of the housing 37. This allows the polygon scanner attachment location on the bottom wall portion 37a to be efficiently air-cooled, and the heat from the polygon scanner 33 to be efficiently dissipated via the bottom wall portion 37a. This effectively suppresses temperature increases inside the housing.

[0076] [Variation 2] FIG. 15 is a schematic diagram of an exposure apparatus 30B according to the second modification. In Modification 2 shown in Fig. 15, the opening / closing member 90 is made of an elastic material such as rubber. In this Modification 2, as shown in Fig. 14, the opening / closing member 90 is elastically deformed by the wind pressure of the air flow, thereby opening the outlet 39. In this Modification 2, if the end of the opening / closing member 90 made of an elastic material on the side of the air receiving portion 90a and the end opposite to the end are fixed to the housing 37, the opening / closing member 90 can be opened and closed by the wind pressure of the air flow. This eliminates the need for a support shaft that rotatably supports the opening / closing member 90, or a means such as a torsion spring for positioning the opening / closing member 90 in the closed position, thereby reducing the number of parts and enabling the device to be constructed at low cost.

[0077] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise specifically limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as set forth in the claims.

[0078] For example, the present invention can be applied to multi-color exposure devices 300a and 300b mounted on a full-color image forming apparatus as shown in Fig. 16. Fig. 17 is a schematic diagram of multi-color exposure device 300 that exposes Y-color photosensitive drum 1Y and M-color photosensitive drum in the full-color image forming apparatus shown in Fig. 16.

[0079] 17, the bottom surface of the housing has an outlet 39M through which the M light beam LM is emitted and an outlet 39Y through which the Y light beam LY is emitted. Of the two outlets 39M, 39Y, the M light beam LM, which is located farther from the polygon scanner 33, is fitted with a dustproof glass 95, which closes the outlet 39M. On the other hand, the Y light beam LM, which is located closer to the polygon scanner 33, is provided with an opening / closing member 90.

[0080] As in the present embodiment, during exposure operation, airflow generating device 120 generates airflow along the outer surface of bottom wall 37a of housing 37 from the polygon scanner side of housing 37, and the wind pressure of the airflow rotates open / close member 90 to the open position shown by the dashed line in the figure. This opens up the interior of the housing, allowing heat to escape from the housing, and this airflow also prevents dust from entering the housing through outlet 39Y.

[0081] In the above description, the exit port from which the light beam is emitted is used as a cooling opening for dissipating heat inside the housing, but a cooling opening may be provided separately from the exit port.

[0082] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In an optical scanning device such as an exposure device 30, which contains a light source 31, a deflector such as a polygon scanner 33 that deflects and scans the light from the light source 31, and optical elements (scanning lenses 34, 35, a folding mirror 36, etc.) arranged on the optical path of the light, and which includes a housing 37 having a cooling opening such as an outlet 39 for cooling the interior, and an opening / closing member 90 that opens and closes the cooling opening, the device is provided with an airflow generating means that generates an airflow around the cooling opening when the cooling opening is open, which prevents dust from entering the housing from the cooling opening. In Patent Document 1, there is a risk of dust entering through the cooling opening when the cooling opening is open, and there is a problem with dust prevention. In contrast, in aspect 1, the air flow prevents dust from entering the housing through the cooling opening when the cooling opening is open, and good dust resistance can be achieved even when the cooling opening is open.

[0083] (Aspect 2) In the first embodiment, the opening / closing member 90 opens the cooling opening such as the exit port 39 when a deflector such as a polygon scanner is in operation, and closes the cooling opening when the deflector is not in operation. According to this, as explained in the embodiment, by opening the cooling openings such as the outlet 39 when the deflector is operating, which causes the temperature inside the housing to rise, the heat inside the housing can be released through the cooling openings when the deflector is operating. This makes it possible to suppress the temperature rise inside the housing compared to Patent Document 1, in which the cooling openings are closed when the deflector is operating. Furthermore, because the cooling openings are closed when the deflector is not operating, it is possible to suppress the intrusion of dust into the housing through the cooling openings when the deflector is not operating.

[0084] (Aspect 3) In the second embodiment, a deflector such as the polygon scanner 33 is disposed at one end of the housing, and a cooling opening such as the exit port 39 is provided at the other end of the housing. As a result, as explained in the embodiment, when a cooling opening such as the exit port 39 is opened during operation of a deflector such as a polygon scanner, the operating noise of the deflector leaking from the cooling opening can be reduced compared to when a cooling opening is provided on one end side of the housing where the deflector is located, thereby suppressing noise.

[0085] (Aspect 4) In any of the first to third aspects, the opening / closing member 90 is placed in an open position where the cooling opening such as the outlet 39 is opened by the airflow. This allows for a reduction in the number of parts and a reduction in cost of the device compared to the case where the opening / closing member 90 is positioned at the open position by a driving means such as a drive motor or solenoid, as explained in the embodiment.

[0086] (Aspect 5) In the fourth embodiment, the opening and closing member 90 is an elastic member. According to this, as explained in Modification 2, the opening / closing member 90 is elastically deformed by the wind pressure of the air flow, and the cooling openings such as the outlet 39 can be positioned in an open position. When the air flow is stopped, the restoring force of the opening / closing member 90 can close the cooling openings. This eliminates the need for a torsion spring or other member for moving the opening / closing member 90 to the closed position when the air flow is stopped. This makes it possible to reduce the number of parts and lower the cost of the device.

[0087] (Aspect 6) In any of the first to fifth aspects, the airflow generating means generates an airflow that flows along a wall portion such as the bottom wall portion 37a of the housing to which a deflector such as the polygon scanner 33 is attached. As described in the embodiment, this allows the wall to be air-cooled by the airflow that flows along the wall, such as the bottom wall 37a, to which a deflector such as the polygon scanner 33 is attached. This allows the heat of the deflector to be efficiently dissipated via this wall, and prevents the temperature inside the housing from rising.

[0088] (Aspect 7) In embodiment 6, a wall portion such as the bottom wall portion 37a on which a deflector such as the housing's polygon scanner 33 is attached is provided with an airflow guide means such as an airflow guide plate 92 that guides the airflow flowing along the wall portion to the deflector attachment point on the wall. This increases the amount of air flowing through the deflector attachment portion of the wall, such as bottom wall 37a, and effectively cools the deflector attachment portion of the wall, as described in Modification 1. This effectively dissipates heat from the deflector through the wall, and prevents the temperature inside the housing from rising.

[0089] (Aspect 8) In the sixth or seventh embodiment, the flow rate of the air flow is adjusted based on the detection result of a temperature detection means such as the temperature sensor 93 that detects the temperature inside the housing. As explained in the embodiment, this makes it possible to increase the airflow rate and improve the cooling efficiency of the wall, such as bottom wall 37a, to which a deflector, such as polygon scanner 33, is attached, when the temperature inside the housing detected by temperature detection means, such as temperature sensor 93, is high. This allows the heat from the polygon scanner to be efficiently dissipated via the wall, preventing the inside of the housing from becoming too hot.

[0090] (Aspect 9) In any of the first to eighth aspects, a control means such as an engine control unit 930 is provided that controls the timing of closing the opening / closing member 90 based on the detection result of a temperature detection means such as a temperature sensor 93 that detects the temperature inside the housing. As described in the embodiment, this allows the open / close member 90 to be positioned in the open position until the temperature inside the housing detected by a temperature detection means such as the temperature sensor 93 falls below the threshold A, allowing the heat inside the housing to escape through the cooling openings such as the outlet 39. This effectively prevents the inside of the housing from becoming too hot.

[0091] (Aspect 10) In an image forming apparatus that forms an image by forming a latent image on the surface of a latent image carrier such as a photosensitive drum 1 by irradiating the surface of the latent image carrier with light using an optical scanning means such as an exposure device 30, and finally transferring the image obtained by developing the latent image onto a recording material, an optical scanning device of any of aspects 1 to 9 is used as the optical scanning means. This allows good latent images to be formed and high quality images to be obtained even during continuous image formation. [Explanation of symbols]

[0092] 1: Photosensitive drum 30: Exposure equipment 31:Light source 32:Incidence optical system 33: Polygon scanner 33a: Polygon mirror 33b: Polygon motor 34: First scanning lens 35: Second scanning lens 36: Folding mirror 37: Housing 37a: Bottom wall part 37b: Light beam emitting part 38: Cover member 39: Exit port 40: Fixing device 90: Opening and closing member 90a: Air receiving part 92: Airflow guide plate 92a: Inclined part 92b: Parallel part 93: Temperature sensor 95: Dustproof glass 100: Copy machine 110: Printer section 120: Airflow generator 121: Fan 122: Duct 122a: First duct section 122b: Second duct section 122c: Relay duct section 123: Shutter parts 300: Multicolor exposure device 300a: Multicolor exposure device 500: Copier D:Dust L: Light beam [Prior art documents] [Patent documents]

[0093] [Patent Document 1] Patent No. 4035316

Claims

1. a housing that houses a light source, a deflector that deflects and scans light from the light source, and an optical element that is arranged on an optical path of the light, and that has a cooling opening for cooling the inside; an optical scanning device including an opening / closing member that opens and closes the cooling opening, An optical scanning device characterized by comprising an airflow generating means for generating an airflow around the cooling opening when the cooling opening is open, which prevents dust from entering the housing through the cooling opening.

2. 2. The optical scanning device according to claim 1, The optical scanning device according to claim 1, wherein the opening and closing member opens the cooling opening when the deflector is in operation, and closes the cooling opening when the deflector is not in operation.

3. 3. The optical scanning device according to claim 2, An optical scanning device, characterized in that the deflector is disposed at one end of the housing, and the cooling opening is provided at the other end of the housing.

4. 2. The optical scanning device according to claim 1, an optical scanning device, characterized in that the air flow causes the opening / closing member to be positioned at an open position where the cooling opening is opened;

5. 5. The optical scanning device according to claim 4, The optical scanning device is characterized in that the opening and closing member is an elastic member.

6. 2. The optical scanning device according to claim 1, The optical scanning device, wherein the airflow generating means generates an airflow that flows along a wall portion of the housing to which the deflector is attached.

7. 7. The optical scanning device according to claim 6, An optical scanning device characterized in that an air flow guide means is provided on the wall portion of the housing where the deflector is attached, for guiding the air flow flowing along the wall portion so that it flows to the deflector attachment point on the wall portion.

8. 7. The optical scanning device according to claim 6, An optical scanning device, characterized in that the flow rate of the air flow is adjusted based on the detection result of temperature detection means that detects the temperature inside the housing.

9. 2. The optical scanning device according to claim 1, a control means for controlling the timing of closing the opening / closing member based on the result of detection by a temperature detection means for detecting the temperature inside the housing;

10. An image forming apparatus in which a latent image is formed on the surface of a latent image carrier by irradiating the surface of the latent image carrier with light using an optical scanning means, and the image obtained by developing the latent image is finally transferred onto a recording material to form an image, 10. An image forming apparatus using the optical scanning device according to claim 1 as the optical scanning means.

Images