JP2004191477A - Image forming apparatus and print head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that eliminates the need to clean a light irradiation face to the end of the life of a machine. <P>SOLUTION: An exposure means which focuses beams emitted from a light emitting element array having a plurality of light emitting elements onto a photoreceptor by using a lens array is provided with a ventilation path that guides an air current from a blowing means to the aperture of the exposure means. In the aperture, an opening/closing member is disposed for opening the aperture when the blowing means is operated and closing the aperture when the blowing means is not operated. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a printer, and more particularly, to an image forming apparatus having a print head for exposing a photosensitive member.
[0002]
[Prior art]
2. Description of the Related Art An image forming apparatus such as a copying machine or a printer using an electrophotographic method uniformly charges a photosensitive member configured in a drum shape, for example, and exposes the photosensitive member with light controlled based on image information. An electrostatic latent image is formed on a photoreceptor, this electrostatic latent image is made a visible image with a developer (toner), and this visible image is transferred to recording paper and fixed to form an image. ing.
In recent years, in order to reduce the size of an image forming apparatus, an LED print head (LPH) using an LED array in which a large number of LEDs are arranged as an exposure unit has been developed. Since this LPH is arranged near the developing device, the light irradiation surface of the LPH is easily stained with dust such as toner and dust. Therefore, in order to prevent image unevenness caused by such dirt, a mechanism for preventing dust from adhering to the light irradiation surface may be provided.
[0003]
Here, as a conventional technique for preventing dust from adhering to the light irradiation surface of the LPH, a ventilation hole is provided from the lower air supply port of the cover surrounding the periphery of the LPH to the upper surface, and air sucked from the air supply port is supplied to the LPH. (Patent Document 1). In addition, an air supply hole and an exhaust hole are formed near the lens surface of the self-focusing lens, a ventilation path is provided inside the LPH head case, and dust is blown from the exhaust hole to the self-focusing lens, so that dust is removed from the lens surface. There is a technique for preventing the adhesive from adhering to the surface (for example, see Patent Document 2).
[0004]
[Patent Document 1]
Japanese Utility Model Laid-Open No. 2-112441 (page 5-6, FIG. 1)
[Patent Document 2]
JP-A-5-177864 (page 2, FIG. 1)
[0005]
[Problems to be solved by the invention]
As described above, since the opening on the light irradiation surface side of the LPH housing is always opened from the necessity for image exposure, the air blowing means for generating the air flow including the stop of the apparatus is always operated. To prevent dust from adhering. However, in such a configuration, it is not possible to prevent dust from adhering to the light irradiation surface in a state where there is no airflow in which the blowing means is stopped, and when the blowing means is operated even while the apparatus is stopped in order to prevent it, However, there was a technical problem that it was not possible to suppress the noise and power consumption by the blowing means.
[0006]
The techniques described in Patent Literature 1 and Patent Literature 2 do not disclose an effective technique for preventing dust from adhering when there is no airflow.
[0007]
Therefore, the present invention has been made based on such a technical problem, and an object of the present invention is to suppress the adhesion of dust to the light irradiation surface even when the blowing means is stopped. Another object is to eliminate the necessity of cleaning the light irradiation surface up to the machine life. Still another object is to provide an image forming apparatus capable of suppressing noise and power consumption by a blowing unit.
[0008]
[Means for Solving the Problems]
With this object in mind, the image forming apparatus of the present invention exposes an air flow from a blowing unit to an exposure unit that forms a beam emitted from a light emitting element array including a plurality of light emitting elements on a photoconductor by a lens array. A ventilation path is provided to the opening of the means, and an opening and closing member that opens the opening when the blowing means operates and shuts off the opening when the blowing means is not operating is arranged in the opening, so that the air flow that stops the blowing means is provided. This makes it possible to prevent dust from adhering to the light-irradiated surface of the exposure means even in the absence of the light.
[0009]
That is, the image forming apparatus of the present invention includes a photoconductor, an exposure unit that exposes the photoconductor, and a blowing unit that supplies an airflow to the exposure unit, and the exposure unit includes an opening that irradiates the photoconductor with exposure light. And an opening / closing member that opens the opening when the blowing means operates and shuts off the opening when the blowing means is not operating, and a ventilation path that guides the air flow from the blowing means to the opening. Here, the blowing means operates during image formation and does not operate during non-image formation. The exposure means may include a light-emitting element array including a plurality of light-emitting elements, and a lens array that forms a beam emitted from the light-emitting element array on a photoconductor.
[0010]
Further, a plurality of the opening / closing members may be arranged along the opening. Further, the opening and closing member may be characterized in that the opening is opened by the air pressure of the blowing means. In this case, the opening / closing member may be made of an elastic body. Further, the opening / closing member may swing about a rotation axis.
On the other hand, the ventilation path can be characterized by having a rectifying member.
[0011]
Further, the print head of the present invention includes a light irradiating unit for irradiating the photosensitive member with exposure light, and a shielding unit for shielding the light irradiating unit, and the shielding unit irradiates the photosensitive member with exposure light from the light irradiating unit. Opening, an air passage for forming an air flow to the opening, and an opening that is opened in synchronization with the passage of the air flow through the air passage, and shuts off when the air flow in the ventilation passage stops. And an opening / closing member. Here, it is possible to have a feature that a blowing means for supplying an air flow to the ventilation path is provided.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
◎ Embodiment 1
FIG. 1 is a diagram illustrating an image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 includes a charger 11 that uniformly charges the photosensitive drum 10 around a photosensitive drum 10 that rotates at a constant speed in the direction of arrow A, based on image information. An LED print head (LPH) 12 for exposing a controlled light; a developing device 13 for developing a latent image formed on the photosensitive drum 10; a transfer roller 14 for transferring a toner image to a recording paper 20; In addition to a cleaner 15 for removing the transfer residual toner from above, a fixing device 16 for fixing the toner image on the recording paper 20 is provided.
[0013]
The charger 11 is formed of two charging rollers 11a and 11b each formed by laminating a conductive rubber or a conductive sponge and a conductive rubber, and is connected to a power supply (not shown) and supplied with a voltage. ing. Then, the surface of the photosensitive drum 10 is uniformly charged at a constant voltage. The LPH 12 is connected to the LPH drive unit 21. Then, the LPH 12 irradiates light controlled by the LPH drive unit 21 based on image data from the host computer (HOST) 30 to form a latent image on the photosensitive drum 10.
[0014]
The developing device 13 includes a developing housing 22 and a developing roller 23. The developing roller 23 carries the toner stored in the developing housing 22, supplies the toner to the photosensitive drum 10 while rotating in the direction of arrow B, and forms a toner image in which the latent image is visualized. The transfer roller 14 is formed by laminating a conductive rubber or a conductive sponge and a conductive rubber, and is connected to a power supply (not shown) and supplied with a voltage. Then, the toner image is transferred onto the recording paper 20 conveyed by the paper feed roller 31.
[0015]
The fixing device 16 includes a pair of rollers including a heating roller 16a and a pressure roller 16b. The recording paper 20 onto which the toner image has been transferred is conveyed to the fixing device 16, and when passing through the fixing device 16, the toner image is heated and fixed to the recording paper 20. On the other hand, the cleaner 15 includes a cleaning blade 24 and a cleaner housing 25. The cleaning blade 24 abuts in the counter direction with respect to the rotation direction A of the photoconductor drum 10, scrapes off the transfer residual toner remaining on the photoconductor drum 10 at the time of transfer, and stores it in the cleaner housing 25.
[0016]
Next, the LPH 12 according to the present embodiment will be described in detail.
FIG. 2 is a cross-sectional view illustrating the configuration of the LPH 12. In FIG. 2, an LPH 12 is an LPH housing 40 as a support, an LED array 41 that emits light controlled based on image information, and a selfoc lens that forms light from the LED array 41 on the surface of the photosensitive drum 10. An array (SLA) 42, a head cover 43 that covers the LPH housing 40 and the SLA 42 and forms a ventilation path 44, and an air duct 45 that supplies air to the ventilation path 44 are provided.
[0017]
The LPH housing 40 is formed of a block or sheet metal of aluminum, SUS, or the like, and supports the LED array 41 and the SLA 42 such that the light emitting point of the LED array 41 and the focal point of the SLA 42 match. The housing seal 46 is disposed so as to seal the LED array 41. Therefore, dust does not adhere to the LED array 41.
The LPH housing 40 is integrated with the LED array 41 and the SLA 42 so as to be movable in the optical axis direction of the SLA 42 by adjusting screws (not shown). Adjusted to be located on top.
[0018]
In the LED array 41, a plurality of LED chips are arranged on the chip substrate in a row in high precision with parallel to the axial direction of the photosensitive drum 10. Then, the image information from the HOST 30 is converted into a signal controlled by the LPH drive unit 21, and the LED chip emits light based on the signal. In the SLA 42, self-focusing fibers are arranged in a line with high precision in parallel with the axial direction of the photosensitive drum 10. Then, light from the LED chip is imaged on the surface of the photosensitive drum 10 to form a latent image.
[0019]
Next, the head cover 43 will be described. FIG. 3 is an exploded perspective view of the head cover 43, the LPH housing 40, and the SLA 42. As shown in FIGS. 2 and 3, the head cover 43 is attached to the side of the LPH housing 40 and is configured to shield the SLA 42 from the outside. The head cover 43 is attached with a gap between the head cover 43 and the LPH housing 40 so as to form an air passage 44 between the head cover 43 and the LPH housing 40. Further, in the head cover 43, an opening 47 is provided at a position facing the light irradiation surface 42a of the SLA 42 in parallel with the axial direction of the photosensitive drum 10, and a shutter valve 48 for opening and closing the opening 47 is provided.
The opening 47 has an opening width enough to secure a sufficient amount of light to irradiate the photosensitive drum 10 with light from the light irradiation surface 42a of the SLA 42.
[0020]
Next, the air duct 45 will be described. FIG. 4 is a diagram illustrating the structure of the air duct 45. FIG. 4A is a front view of the air duct 45, and FIG. 4B is a bottom view of the air duct 45. As shown in FIG. 4, the air duct 45 is configured such that the inlet 49 is narrower than the width of the SLA 42, and forms the outlet 50 so that the air flow is expanded to the width of the SLA 42. A rectifying rib 51 is arranged inside the air duct 45. The rectifying ribs 51 can make the air flow uniform from the suction port 49 to the discharge port 50, and at the same time, prevent a backflow of the air flow that occurs partially, thereby forming a stable and uniform air flow. It becomes possible.
[0021]
Further, as shown in FIG. 5, the air duct 45 is arranged such that the outlet 50 is connected to the air passage 44 between the head cover 43 and the LPH housing 40. The air flow supplied from the fan 60 to the suction port 49 of the air duct 45 is made uniform by the rectifying ribs 51 while passing through the inside of the air duct 45, and is stabilized from the discharge port 50 of the air duct 45 to the ventilation path 44. And a uniform air flow is supplied. The airflow from the fan 60 is configured to pass through a filter 61 for removing fine dust and the like. As a result, clean air is supplied to the ventilation path 44, so that the light irradiation surface 42a of the SLA 42 is not contaminated by the airflow.
Although the fan 60 is disposed in the main body of the image forming apparatus 1, the LPH 12 and the fan 60 may be integrally formed by attaching the fan 60 to the suction port 49 of the air duct 45.
[0022]
Next, the shutter valve 48 provided in the opening 47 of the head cover 43 will be described. FIG. 6 is a partially enlarged view showing a light irradiation unit of the LPH 12. As shown in FIG. 6, the shutter valve 48 is made of an elastic member such as resin, rubber, or thin metal, and has one end fixed to the head cover 43 and the other end rotatably around a rotation center 48a. It is configured.
The shutter valve 48 is urged by the elastic deformation force of the shutter valve 48 so that the end portion 48b of the shutter valve 48 comes into contact with a stopper 47a formed in the opening 47 when the airflow is not supplied to the ventilation path 44. The shutter valve 48 is configured to shut off the opening 47. Note that the shutter valve 48 does not move into the head cover 43 from a predetermined position by the stopper 47a. Further, a configuration in which the stopper 47a is provided in the LPH housing 40 or the SLA 42 is also possible.
On the other hand, in a state where the airflow is supplied to the ventilation passage 44, the shutter valve 48 rotates around the rotation center portion 48a by the pressure of the airflow until the shutter valve 48 hits the surface 47b of the opening 47 facing the stopper 47a. , The opening 47 is opened.
[0023]
Here, in the present embodiment, the fan 60 that supplies the airflow to the ventilation path 44 is operated in synchronization with image formation. That is, the air is supplied by rotating the fan 60 during image formation, and the air is not supplied by stopping the fan 60 during non-image formation. Therefore, the shutter valve 48 opens to open the opening 47 during image formation, and closes to close the opening 47 during non-image formation.
[0024]
Hereinafter, the operation of the shutter valve 48 during image formation and during non-formation will be described in detail. FIG. 7A illustrates a state of the shutter valve 48 during image formation, and FIG. 7B illustrates a state of the shutter valve 48 during non-image formation. When the image forming apparatus 1 has received an image signal from the HOST 30 and is in an image forming state, the switch of the fan 60 is turned on to operate the fan 60 and supply the airflow to the ventilation path 44. In this case, as shown in FIG. 7A, the air flow is supplied to the ventilation path 44, and the pressure of the air flow causes the shutter valve 48 to rotate against the elastic deformation force of the shutter valve 48. , The opening 47 is opened. In this state, the LED array 41 irradiates a light beam to form a latent image on the photosensitive drum 10. The pressure of the air flow for rotating the shutter valve 48 is set to 2 to 10 mmAq (0.196 to 0.981 hPa) or more as the air outlet pressure of the opening 47.
In this state, since the airflow blows out from the opening 47, dust such as toner cloud generated from the vicinity of the photosensitive drum 10 or the developing device 13 or dust from the outside passes through the opening 47 and the light irradiation surface 42a of the SLA 42. Does not adhere to
[0025]
When the image forming apparatus 1 does not receive an image signal from the HOST 30 during an image non-forming period, the fan 60 is turned off to stop the fan 60 and supply no airflow to the ventilation path 44. In this case, as shown in FIG. 7B, since the air flow is not supplied to the ventilation path 44, the shutter valve 48 is urged by the elastic deformation force so that the end 48b of the shutter valve 48 contacts the stopper 47a. , The shutter valve 48 blocks the opening 47.
In this state, since the light irradiation surface 42a of the SLA 42 and the photosensitive drum 10 are shut off by the shutter valve 48, dust such as toner cloud generated from the vicinity of the photosensitive drum 10 or the developing device 13 or dust from the outside is generated. Does not adhere to the light irradiation surface 42a of the SLA 42.
With this configuration, the fan 60 can be stopped during non-image formation, so that noise and power consumption due to rotation of the fan 60 can be suppressed.
[0026]
Here, the configuration of the shutter valve 48 will be described. FIG. 8 is a diagram illustrating a cross-sectional configuration of the shutter valve 48. As shown in FIG. 8 (a), the shutter valve 48 is made of an elastic member such as resin, rubber, and thin metal, and the thickness of the rotation center portion 48a is made thinner than other portions, so that the shutter valve 48 is made thinner. 48 is obtained by adjusting the elastic deformation force. As described above, by setting the thickness of the rotation center portion 48a in relation to the air outlet pressure of the opening 47, the opening / closing force of the shutter valve 48 can be freely adjusted, and the shutter valve 48 that opens by the pressure of the air flow. Can be configured.
As shown in FIG. 8B, the rotation center 48a of the shutter valve 48 is configured as a rotation shaft rotatably fixed to the LPH housing 40 or the head cover 43, and the shutter valve 48 is rotated about the rotation center. It is also possible to mount it rotatably about the part 48a. Further, a leaf spring 70 is attached to the shutter valve 48 so as to bias the shutter valve 48 in the direction of the stopper 47a. Here, as the urging means, an elastic body such as rubber can be used in addition to a leaf spring. The opening and closing force of the shutter valve 48 can be freely adjusted by appropriately setting the elastic coefficient of a spring, rubber, or the like.
[0027]
FIG. 9 is a perspective view showing another configuration of the shutter valve 48 having the rotation center 48a as a rotation axis. FIG. 9A shows a spiral spring in which a shutter valve 48 is rotatably mounted about a rotation shaft 73 fixed to the head cover 43, and the shutter valve 48 is biased in the direction of a stopper 47a. 71 is attached. 9B, the shutter valve 48 is rotatably mounted around a rotation shaft 73 fixed to the head cover 43, and is opposite to the stopper 47a of the shutter valve 48 with the rotation shaft 73 interposed therebetween. The balance weight 72 is provided on the side, and the shutter valve 48 is biased in the direction of the stopper 47a. With this configuration, the opening / closing force of the shutter valve 48 can be freely adjusted by appropriately setting the number of windings of the spiral spring 71, the thickness of the wire, and the weight of the balance weight 72. An open shutter valve 48 can be configured.
In the present embodiment, the configuration in which the entire opening 47 is opened and closed by one shutter valve 48 has been described. However, a configuration in which a plurality of shutter valves 48 are arranged in the longitudinal direction of the opening 47 is also possible.
[0028]
◎ Embodiment 2
In the first embodiment, the image forming apparatus 1 including the LPH 12 configured to supply the airflow to the ventilation path 44 by operating the fan 60 in synchronization with the image formation and to open the shutter valve 48 by the air pressure. explained. In the second embodiment, an image forming apparatus 1 including an LPH 12 configured to operate a fan 60 in synchronization with image formation and mechanically open and close a shutter valve 48 will be described. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted here.
[0029]
FIG. 10 is a diagram illustrating the LPH 12 according to the present embodiment. As shown in FIG. 10, a shutter 80 that opens and closes the opening 47 is disposed on the head cover 43 of the LPH 12. The shutter 80 is configured to be slidable in a direction perpendicular to the longitudinal direction of the opening 47, and is slid by electromagnetic driving means or driving means such as a motor.
When the image forming apparatus 1 receives the image signal from the HOST 30 and the image forming apparatus 1 is at the time of forming an image, the image forming apparatus 1 turns on the fan 60 to operate the fan 60 and supplies the airflow to the air passage 44 at the same time. The shutter 80 slides so as to open the opening 47. On the other hand, when the image forming apparatus 1 has completed the image formation and is not forming an image, the switch of the fan 60 is turned off to stop the fan 60, and at the same time, the shutter 80 slides so as to block the opening 47. .
With the configuration as in the second embodiment, dust can be prevented from adhering to the light irradiation surface 42a of the SLA 42 as in the first embodiment, and the fan 60 is stopped when an image is not formed. I can put it.
[0030]
As described above, according to the present embodiment, it is possible to prevent dust from adhering to the light irradiation surface 42a even in a state where there is no airflow when the fan 60 is stopped, and it is not necessary to clean the light irradiation surface 42a until machine life. In addition, it is possible to provide an image forming apparatus capable of suppressing noise and power consumption by the fan 60.
[0031]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an image forming apparatus that does not require cleaning of a light irradiation surface until machine life.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view illustrating an image forming apparatus according to a first embodiment.
FIG. 2 is a cross-sectional view illustrating a configuration of an LPH.
FIG. 3 is an exploded perspective view of a head cover, an LPH housing, and an SLA.
4A and 4B are diagrams illustrating a structure of an air duct, wherein FIG. 4A is a front view of the air duct, and FIG. 4B is a bottom view of the air duct.
FIG. 5 is a front view of the LPH.
FIG. 6 is a partially enlarged view showing a light irradiation section of the LPH.
7A is a diagram illustrating a state of a shutter valve when an image is formed, and FIG. 7B is a diagram illustrating a state of the shutter valve when an image is not formed.
FIG. 8 is a diagram illustrating a cross-sectional configuration of a shutter valve.
FIG. 9 is a perspective view showing another configuration of the shutter valve.
FIG. 10 is a diagram illustrating an LPH according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Photoreceptor drum, 11 ... Charging device, 11a, 11b ... Charging roller, 12 ... LPH, 13 ... Developing device, 14 ... Transfer roller, 15 ... Cleaner, 16 ... Fixing device, 16a ... Heating Roller, 16b Pressure roller, 20 Recording paper, 21 LPH drive unit, 22 Development housing, 23 Development roller, 24 Cleaning blade, 25 Cleaner housing, 30 Host computer (HOST), 31 Supply Paper roller, 40: LPH housing, 41: LED array, 42: Selfoc lens array (SLA), 42a: Light irradiation surface, 43: Head cover, 44: Ventilation path, 45: Air duct, 46: Housing seal, 47: Opening 47a Stopper 47b Opposing surface 48 Shutter valve 48a Rotating center 48b Shutter End, 49 ... inlet, 50 ... outlet, 51 ... rectifying ribs, 60 ... Fan, 61 ... Filter, 70 ... plate spring, 71 ... spiral spring, 72 ... balance weight, 73 ... rotary shaft, 80 ... shutter

Claims (10)

A photoreceptor,
Exposure means for exposing the photoconductor,
Blower means for supplying an air flow to the exposure means,
The exposing means,
An opening for irradiating the photoconductor with exposure light,
A ventilation path for guiding the airflow from the blowing means to the opening,
An opening / closing member that opens the opening when the blower is operating and blocks the opening when the blower is not operating. The image forming apparatus according to claim 1, wherein the blowing unit operates during image formation and does not operate during non-image formation. 2. The image according to claim 1, wherein the exposure unit includes a light emitting element array including a plurality of light emitting elements, and a lens array that forms a beam emitted from the light emitting element array on the photoconductor. 3. Forming equipment. The image forming apparatus according to claim 1, wherein a plurality of the opening and closing members are arranged along the opening. The image forming apparatus according to claim 1, wherein the opening / closing member opens the opening by air pressure from the blowing unit. The image forming apparatus according to claim 5, wherein the opening / closing member is made of an elastic body. The image forming apparatus according to claim 5, wherein the opening and closing member swings about a rotation axis. The image forming apparatus according to claim 1, wherein the ventilation path has a rectifying member. Light irradiation means for irradiating the photosensitive member with exposure light,
Shielding means for shielding the light irradiation means,
The shielding means,
An opening for irradiating the photoconductor with exposure light from the light irradiation unit,
A ventilation path for forming an airflow to the opening;
An opening / closing member that opens the opening in synchronization with the passage of the airflow through the ventilation path and shuts off the opening in synchronization with the stoppage of the airflow in the ventilation path. head. The print head according to claim 9, further comprising a blower that supplies an airflow to the ventilation path.

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