Image forming apparatus

Abstract

The invention provides an image forming apparatus. This optical scanning device is provided with a light source unit, a polyhedral rotating mirror, a scanning lens, a housing, and a temperature sensor. The light source unit emits laser light. The polyhedral rotating mirror rotates around a rotation axis extending in the vertical direction, reflects the laser light emitted from the light source unit, and scans the peripheral surface of the image carrier in the main scanning direction. The scanning lens images the laser light reflected by the polyhedral rotating mirror on the peripheral surface of the image carrier. The housing accommodates the light source unit, the polyhedral rotating mirror, and the scanning lens. The temperature sensor detects a temperature within the housing. The temperature sensor detects a temperature of the developing device.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine thereof, which is provided with an optical scanning device that forms a latent image on a scanned surface by exposure scanning. Background Art

[0002] Conventional image forming devices include an optical scanning device. The optical scanning device includes a light source, a polygon mirror, a scanning lens, a housing, and a temperature sensor. The light source emits laser light. The polygon mirror rotates around a rotation axis extending in the up-down direction, reflects the laser light emitted from the light source, and causes the laser light to scan the peripheral surface of the image carrier along the main scanning direction. The scanning lens forms an image of the laser light reflected by the polygon mirror on the peripheral surface of the image carrier. The housing accommodates the light source, the polygon mirror, and the scanning lens. The temperature sensor detects the temperature inside the housing.

[0003] When the conventional technology is used, there is a problem that the toner image formed on the image carrier may have image defects due to the increase in the temperature of the developing device. Summary of the invention

[0004] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus capable of suppressing an increase in manufacturing cost and suppressing the occurrence of image defects.

[0005] In order to achieve the above-mentioned purpose, the first structure of the present invention is an image forming device having an optical scanning device, an image carrier, a charging device, a developing device and a control unit. The optical scanning device has a light source unit, a polygon mirror, a scanning lens, a housing and a temperature sensor. The light source unit emits laser light. The polygon mirror rotates around a rotation axis extending in the up-down direction, reflects the laser light emitted from the light source unit, and causes the laser light to scan the peripheral surface of the image carrier along the main scanning direction. The scanning lens forms an image of the laser light reflected by the polygon mirror on the peripheral surface of the image carrier. The housing accommodates the light source unit, the polygon mirror and the scanning lens. The temperature sensor detects the temperature in the housing. There are more than one image carrier, and a photosensitive layer is formed on the surface. The charging device charges the image carrier to a predetermined surface potential. The developing device is arranged opposite to the image carrier, has a developer carrier that carries a developer, applies a predetermined development voltage to the developer carrier, and causes the toner to adhere to the electrostatic latent image formed on the image carrier to form a toner image. The control unit controls the optical scanning device and the developing device. The temperature sensor detects the temperature of the developing device. The control section controls the light scanning device according to the temperature in the housing detected by the temperature sensor, and controls the developing device according to the temperature of the developing device detected by the temperature sensor.

[0006] According to the first aspect of the present invention, it is possible to provide an image forming apparatus capable of suppressing an increase in manufacturing cost and suppressing the occurrence of image defects.

[0007] Still other objects of the present invention and specific advantages obtainable by the present invention will become more apparent from the description of the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic cross-sectional view showing the overall structure of an image forming apparatus 100 equipped with the optical scanning device 5 of the present invention. Figure 2 It is a perspective view of the optical scanning device 5 according to one embodiment of the present invention. Figure 3 It is a perspective view of the optical scanning device 5 according to one embodiment of the present invention. Figure 4 yes Figure 2 AA cross-section diagram in. Figure 5 This is an explanatory diagram showing an enlarged view of the vicinity of the circuit board 90 of the optical scanning device 5 of the present invention. DETAILED DESCRIPTION

[0009] [1. Structure of image forming apparatus] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 1 is a schematic cross-sectional view showing the overall structure of an image forming apparatus 100 equipped with the optical scanning device 5 of the present invention. Figure 1 In the state shown in FIG. 1 , the vertical direction is defined as the up-down direction (Z1-Z2 direction). Figure 1 The front-to-back direction (Y1-Y2 direction) is defined with the front side of the image forming apparatus 100 shown in the drawing as the front side (front). In addition, the left-right direction (X1-X2 direction) is defined with the front side of the image forming apparatus 100 in the set state as a reference. In the present embodiment, the left-right direction (X1-X2 direction) is orthogonal to the up-down direction (Z1-Z2 direction) and the front-to-back direction (Y1-Y2 direction).

[0010] The image forming apparatus 100 includes an optical scanning device 5 , photosensitive drums (image carriers) 1 a to 1 d , charging devices 2 a to 2 d , developing devices 3 a to 3 d , primary transfer rollers 6 a to 6 d , a secondary transfer roller 9 , a paper feed cassette 16 , a fixing unit 13 , and a control unit 50 .

[0011] Specifically, the image forming apparatus 100 is a tandem color printer. The image forming apparatus 100 includes rotatable photosensitive drums 1a to 1d as image carriers. The photosensitive drums 1a to 1d use an organic photosensitive body (OPC photosensitive body) having an organic photosensitive layer formed thereon or an amorphous silicon photosensitive body having an amorphous silicon photosensitive layer formed thereon. The photosensitive drums 1a to 1d are arranged in tandem corresponding to the respective colors of yellow, cyan, magenta, and black.

[0012] A developing device 3a, a charging device 2a, and a cleaning device 7a are arranged around the photosensitive drum (image carrier) 1a. Similarly, developing devices 3b to 3d, charging devices 2b to 2d, and cleaning devices 7b to 7d are arranged around each of the photosensitive drums 1b to 1d. In addition, an optical scanning device 5 is arranged above Z1 of the developing devices 3a to 3d.

[0013] The developing devices 3a to 3d are respectively arranged at the right side X1 of the photosensitive drums 1a to 1d. The developing devices 3a to 3d are arranged opposite to the photosensitive drums (image carriers) 1a to 1d, and have developing rollers (developer carriers) 21a to 21d. The developing devices 3a to 3d apply a predetermined developing voltage to the developing rollers (developer carriers) 21a to 21d to make the toner adhere to the electrostatic latent image formed on the photosensitive drums (image carriers) 1a to 1d, thereby forming a toner image. The developing devices 3a to 3d are respectively opposite to the photosensitive drums 1a to 1d, and supply the toner to the photosensitive drums 1a to 1d. The developing devices 3a to 3d have containers 4a to 4d, which contain the toners of various colors, namely magenta, cyan, yellow and black.

[0014] The charging devices 2a to 2d are arranged on the upstream side of the developing devices 3a to 3d in the rotation direction of the photosensitive drums 1a to 1d, and face the surfaces of the photosensitive drums 1a to 1d, respectively. The charging devices 2a to 2d charge the surfaces of the photosensitive drums 1a to 1d in the same manner. That is, the charging devices 2a to 2d charge the photosensitive drums (image carriers) 1a to 1d to a predetermined surface potential.

[0015] In this embodiment, the optical scanning device 5 is arranged adjacent to the developing devices 3a to 3d at Z1 above the developing devices 3a to 3d. The optical scanning device 5 irradiates light (optical scanning) to the surfaces of the photosensitive drums 1a to 1d which are similarly charged by the charging devices 2a to 2d, based on image data such as text and patterns input from a personal computer or the like to the image input unit. Thus, an electrostatic latent image is formed on the surfaces of the photosensitive drums 1a to 1d.

[0016] The housing 48 of the optical scanning device 5 is a resin molded product, and includes a housing portion 481 with an opening on one surface (the upper surface in this embodiment), and a cover portion 482 covering the opening (see FIG. 4 ). Figure 4 ). The housing portion 481 houses the scanning optical system therein.

[0017] Lasers D1 to D4 are irradiated onto the surfaces of the photosensitive drums 1a to 1d from the downstream side of the charging devices 2a to 2d in the rotation direction of the photosensitive drums 1a to 1d, respectively. Electrostatic latent images are thereby formed on the surfaces of the photosensitive drums 1a to 1d. These electrostatic latent images are developed into toner images by the developing devices 3a to 3d.

[0018] The endless intermediate transfer belt 8 is stretched between a driving roller 10 and a driven roller 11. The driving roller 10 is rotated by a motor (not shown), thereby driving the intermediate transfer belt 8 to Figure 1 Cycle in clockwise direction.

[0019] The photosensitive drums 1a to 1d are arranged adjacent to each other along the conveyance direction above Z1 of the intermediate transfer belt 8. The photosensitive drums 1a to 1d are in contact with the intermediate transfer belt 8, respectively.

[0020] The primary transfer rollers 6a to 6d face the photosensitive drums 1a to 1d respectively via the intermediate transfer belt 8. The primary transfer rollers 6a to 6d are pressed against the intermediate transfer belt 8 and form primary transfer sections together with the photosensitive drums 1a to 1d. In these primary transfer sections, the toner images are transferred to the intermediate transfer belt 8.

[0021] Specifically, by applying a primary transfer voltage to the primary transfer rollers 6a to 6d, the toner images on the photosensitive drums 1a to 1d are sequentially transferred to the intermediate transfer belt 8 at a predetermined timing. As a result, a full-color toner image is formed on the surface of the intermediate transfer belt 8, in which the four color toner images of magenta, cyan, yellow, and black are superimposed in a predetermined positional relationship.

[0022] The secondary transfer roller 9 faces the driving roller 10 across the intermediate transfer belt 8. The secondary transfer roller 9 is pressed against the intermediate transfer belt 8 and forms a secondary transfer section together with the driving roller 10. In the secondary transfer section, a secondary transfer voltage is applied to the secondary transfer roller 9, so that the toner image on the surface of the intermediate transfer belt 8 is transferred to the paper S. After the toner image is transferred, a belt cleaning device (not shown) cleans the toner remaining on the intermediate transfer belt 8.

[0023] A paper feed cassette 16 is disposed at the lower portion of the image forming apparatus 100 . The paper feed cassette 16 can store a plurality of sheets of paper S. A paper conveyance path 19 is disposed to the right X1 of the paper feed cassette 16 .

[0024] The paper conveying path 19 conveys the paper S fed from the paper feeding cassette 16 to the secondary transfer unit. The fixing unit 13 and the paper conveying path 20 are arranged at the upper right of the image forming apparatus 100. The fixing unit 13 performs a fixing process on the paper S on which the image is formed. The paper conveying path 20 conveys the paper S after the fixing process to the paper discharge unit 17.

[0025] The sheets S stored in the sheet feeding cassette 16 are fed one by one to the sheet conveying path 19 by the pickup roller 12 a .

[0026] The registration roller pair 12b grasps the timing of the image forming operation on the intermediate transfer belt 8 and the paper feeding operation to the secondary transfer section, and conveys the paper S to the secondary transfer section. The full-color toner image on the intermediate transfer belt 8 is secondarily transferred to the paper S conveyed to the secondary transfer section by the secondary transfer roller 9 to which the secondary transfer voltage is applied. The paper S to which the full-color toner image is transferred is conveyed to the fixing section 13.

[0027] The fixing section 13 includes a fixing belt heated by a heater, a fixing roller connected to the fixing belt, and a pressure roller pressed against the fixing roller via the fixing belt. The fixing section 13 heats and presses the paper S to which the toner image is transferred. Thus, a fixing process is performed. The paper S to which the toner image is fixed in the fixing section 13 is turned over on the front and back sides in the paper conveying passage 18 as needed. Thereafter, after the paper S is conveyed to the secondary transfer section again with the aid of the registration roller pair 12b, a new toner image is secondarily transferred on the back side of the paper S by the secondary transfer roller 9 and fixed by the fixing section 13. The paper S to which the toner image is fixed is discharged to the paper discharge section 17 through the paper conveying passage 20.

[0028] In addition, a control unit 50 is disposed inside the image forming apparatus 100. The control unit 50 controls the image forming apparatus 100 in a unified manner. Specifically, the control unit 50 controls the image forming unit. The image forming unit includes an optical scanning device 5, photosensitive drums (image carriers) 1a to 1d, charging devices 2a to 2d, and developing devices 3a to 3d. That is, the control unit 50 controls the optical scanning device 5 and the developing devices 3a to 3d.

[0029] [2. Structure of optical scanning device] Figure 2 , Figure 3 is a perspective view of the optical scanning device 5, Figure 3 Indicates a state where the cover portion 482 is removed. Figure 4 yes Figure 2 AA cross-section diagram in. Figure 4 The part of the schematic diagram shows the structure of each component, and does not strictly show the shape and positional relationship of each component. Figure 4 The scanning lens 41 and the scanning lens 42 are not shown.

[0030] In the following description, the main scanning direction (Y1-Y2 direction) is the long side direction of the reflection mirrors 49a to 49c. In addition, the main scanning direction (Y1-Y2 direction) is consistent with the direction in which the rotation axis of the photosensitive drums 1a to 1d extends and the front-back direction of the image forming device 100. The sub-scanning direction (Z1-Z2 direction) is a direction parallel to the rotation axis J of the polygon mirror 45 and is consistent with the up-down direction of the image forming device 100. In addition, the left-right direction (X1-X2 direction) is a direction orthogonal to the main scanning direction (Y1-Y2 direction) and the sub-scanning direction (Z1-Z2 direction), and is consistent with the arrangement direction of the reflection mirrors 49a to 49c.

[0031] The optical scanning device 5 outputs (irradiates) multiple types (four types in this embodiment) of laser light D1 to D4 modulated according to image signals to the photosensitive drums 1a to 1d, thereby exposing the surfaces of the photosensitive drums 1a to 1d to form electrostatic latent images for attenuating charging.

[0032] The optical scanning device 5 includes a light source unit 46 , a polygon mirror 45 , a pair of scanning lenses 41 , a pair of scanning lenses 42 , a pair of reflection mirrors 49 a , 49 b , and 49 c , a housing 48 , and a circuit board 90 .

[0033] The housing 48 includes a housing portion 481 and a cover portion 482. The housing portion 481 is formed in a substantially quadrilateral shape in a plan view and houses the light source portion 46, the polygon mirror 45, the pair of scanning lenses 41, the pair of scanning lenses 42, the pair of reflection mirrors 49a, 49b, 49c, and the circuit board 90.

[0034] The storage portion 481 includes a bottom wall portion 481a and a peripheral wall portion 481b. The bottom wall portion 481a extends in a direction perpendicular to the rotation axis J of the polygon mirror 45. The bottom wall portion 481a is formed with emission ports 483a to 483d (see FIG. Figure 4 ). The ejection ports 483a to 483d extend along the main scanning direction (Y1-Y2 direction). The lasers D1 to D4 emitted from the scanning optical system are emitted to the outside of the housing 48 through the ejection ports 483a to 483d, and are respectively injected into the corresponding photosensitive drums 1a to 1d. The ejection ports 483a to 483d are respectively covered by dustproof glasses 70a to 70d. This prevents dust from entering the housing 48.

[0035] The bottom wall portion 481a is formed with an opening portion 483e (see Figure 5). In the present embodiment, the opening 483e is arranged at the rear (Y2 side) of the light source section 46, and is open to the photosensitive drums (image carriers) 1a to 1d and the developing devices 3a to 3d. In addition, in the housing 48, a temperature sensor (thermistor) 91 described later is arranged facing the opening 483e. Thus, the temperature sensor 91 can detect the temperature of the developing devices 3a to 3d with high accuracy from the inside of the housing 48. For example, the temperature sensor 91 can detect the temperature of the developing rollers (developer carriers) 21a to 21d of the developing devices 3a to 3d with high accuracy.

[0036] The peripheral wall portion 481b extends upward from the outer periphery of the bottom wall portion 481a, and surrounds the light source portion 46, the polygon mirror 45, the pair of scanning lenses 41, the pair of scanning lenses 42, the pair of reflection mirrors 49a, 49b, 49c, and the circuit board 90 from the side.

[0037] The cover 482 includes a top surface 482a and a peripheral surface 482b. The top surface 482a covers the upper surface of the opening of the housing 481. The peripheral surface 482b extends downward from the outer periphery of the top surface 482a and covers a part of the peripheral wall 481b from the outside.

[0038] The light source unit 46 includes a plurality of light emitting modules 46a for emitting laser light. The light emitting modules output laser light D1 to D4 corresponding to the respective colors of Y (yellow), C (cyan), M (magenta), and K (black). The laser light D1 to D4 emitted from the light emitting modules 46a are irradiated toward the polygon mirror 45. The laser light D1 to D4 form a line image near the deflection surface of the polygon mirror 45.

[0039] In this embodiment, the circuit board 90 is arranged behind the light source unit 46 (Y2 side), and is held in the storage unit 481 (see Figure 3 A temperature sensor 91 and an IC (Integrated Circuit) driver 92, which will be described later, are mounted on the circuit board 90. The circuit board 90 will be described in detail later.

[0040] The polygon mirror 45 rotates around a rotation axis J extending in the vertical direction (Z1-Z2 direction) to reflect the laser beams D1-D4 emitted from the light source 46 so as to scan the peripheral surfaces of the photosensitive drums (image carriers) 1a-1d in the main scanning direction.

[0041] The polygon mirror 45 is composed of a plurality of reflecting surfaces. In the present embodiment, the polygon mirror 45 is a polygon mirror formed in a quadrangular prism shape. The laser light D1 and D2 incident on the polygon mirror 45 are deflected by any reflecting surface of the rotating polygon mirror 45 and used for scanning. Specifically, they are reflected by the reflecting surface toward the left direction (X2 direction) and guided to the scanning lens 41 and the scanning lens 42. On the other hand, the laser light D3 and D4 incident on the polygon mirror 45 are deflected and scanned by any reflecting surface driven by the rotating polygon mirror 45, reflected by the reflecting surface of the polygon mirror 45 toward the right direction (X1 direction), and guided to the scanning lens 41 and the scanning lens 42 (see FIG. Figure 4 ).

[0042] The scanning lens 42 is arranged on the downstream side of the optical path of the laser beams D1 to D4 relative to the scanning lens 41 .

[0043] The scanning lens 41 is a lens having distortion (fθ characteristics) and is a long lens extending in the main scanning direction (Y1-Y2 direction) and focuses the laser beams D1 to D4 reflected by the deflection surface of the polygon mirror 45 .

[0044] The scanning lens 42 is a lens having distortion (fθ characteristics) similar to the scanning lens 41, and is a long lens extending along the main scanning direction (Y1-Y2 direction). The scanning lens 42 focuses the laser light D1 to D4 that has passed through the scanning lens 41, and forms images on the scanned surfaces of the photosensitive drums 1a to 1d, respectively.

[0045] The pair of reflecting mirrors 49a reflects the laser beams D1 and D4, respectively. The pair of reflecting mirrors 49b and the pair of reflecting mirrors 49c reflect the laser beams D2 and D3, respectively.

[0046] The scanning lenses 41 and 42 form images of the laser beams D1 to D4 reflected by the polygon mirror 45 on the scanned surfaces (circumferential surfaces) of the photosensitive drums (image carriers) 1 a to 1 d .

[0047] The laser beams D1 to D4 reflected and deflected by the polygon mirror 45 are respectively focused on the scanned surfaces of the photosensitive drums 1a to 1d through the scanning lenses 41 and 42. Thus, beam spots are formed on the scanned surfaces of the photosensitive drums 1a to 1d. In addition, the laser beams D1 to D4 focused on the scanned surfaces of the photosensitive drums 1a to 1d are scanned at a constant speed on the scanned surfaces of the photosensitive drums 1a to 1d.

[0048] At this time, the lasers D1 to D4 scan the scanned surfaces (peripheral surfaces) of the photosensitive drums (image carriers) 1a to 1d along the main scanning direction (Y1-Y2 direction) by the rotation of the polygon mirror 45. In addition, the lasers D1 to D4 scan along the sub-scanning direction (Z1-Z2 direction) by the rotation of the photosensitive drums 1a to 1d, and form electrostatic latent images on the surfaces of the photosensitive drums 1a to 1d.

[0049] [3. Structure of circuit board] Figure 5 90 is an enlarged explanatory diagram showing the vicinity of the circuit substrate 90. In the present embodiment, the circuit substrate 90 is arranged behind the light source unit 46 (Y2 side), and is held in the storage unit 481 (see FIG. 1 ) in a state of being perpendicular to the main scanning direction (Y1-Y2 direction) and standing upright. Figure 3 A temperature sensor 91 and an IC driver 92 are mounted on the circuit board 90. The temperature sensor 91 is arranged on the opposite side of the IC driver 92 across the external connection terminal 93 on the circuit board 90. The temperature sensor 91 detects the temperature inside the housing 48 and detects the temperature of the developing devices 3a to 3d.

[0050] In this embodiment, the temperature sensor 91 is disposed at the lower end of the circuit board 90 and faces the opening 483e. Thus, the temperature sensor 91 can detect the temperature of the developing devices 3a to 3d from inside the housing 48 with high accuracy.

[0051] In addition, a duct 80 is disposed between the optical scanning device 5 and the developing devices 3a to 3d. The duct 80 covers the end of the developing devices 3a to 3d on the rear side (Y2 side) in the main scanning direction (Y1-Y2 direction) from the upper side, and guides the heat of the developing devices 3a to 3d to the temperature sensor 91 side. In addition, the internal flow path 80a of the duct 80 becomes narrower as it goes toward the temperature sensor 91 (upper side Z1 direction). As a result, the temperature sensor 91 can detect the temperature of the developing devices 3a to 3d from the inside of the housing 48 with higher accuracy.

[0052] The IC driver 92 is connected to the control unit 50. The IC driver 92 is connected to the light source unit 46 and the temperature sensor 91. The control unit 50 sends a signal to the light source unit 46 through the IC driver (control unit) 92 according to the temperature in the housing 48 detected by the temperature sensor 91. Thus, the control unit 50 controls the timing (light emission timing) of starting scanning of the laser light D1 to D4 emitted from the light source unit 46. Therefore, color deviation can be corrected and image defects can be suppressed.

[0053] In addition, the control unit 50 can also control the rotation of the polygon mirror 45 according to the temperature in the housing 48 detected by the temperature sensor 91. By controlling the light emission timing of the light source unit 46 according to the temperature in the housing 48 detected by the temperature sensor 91 and controlling the rotation of the polygon mirror 45, color deviation can be corrected and image defects can be further suppressed.

[0054] Although the IC driver 92 generates heat during operation, the temperature sensor 91 is arranged on the opposite side of the IC driver 92 across the external connection terminal 93 on the circuit board 90, and is therefore less likely to be affected by the heat generated by the IC driver 92. Thus, the light emission timing of the light source unit 46 can be controlled with high accuracy based on the temperature detected by the temperature sensor 91.

[0055] Furthermore, the control unit 50 is connected to the developing devices 3a to 3d, and the control unit 50 can control the developing devices 3a to 3d based on the temperature of the developing devices 3a to 3d detected by the temperature sensor 91. By sharing the temperature sensor 91 for detecting the temperature in the housing 48 and the temperature sensor 91 for detecting the temperature of the developing devices 3a to 3d, it is possible to provide an image forming apparatus 100 that can suppress an increase in manufacturing cost and suppress the occurrence of image defects.

[0056] Specifically, the control unit 50 controls the magnitude of the developing voltage according to the temperature of the developing devices 3a to 3d detected by the temperature sensor 91. By controlling the magnitude of the developing voltage, the image density of the toner image can be adjusted. In addition, when the temperature of the developing devices 3a to 3d detected by the temperature sensor 91 exceeds a predetermined threshold, the control unit 50 stops the driving of the developing devices 3a to 3d. Thus, for example, the driving of the developing devices 3a to 3d can be stopped in advance before a failure occurs due to the aggregation of the toner or the like in the developing devices 3a to 3d or a change in characteristics, thereby preventing the occurrence of poor development before it occurs.

[0057] In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

[0058] The present invention can be applied to an optical scanning device that forms a latent image on a scanned surface by exposure scanning.

Claims

1. An image forming device, characterized in that: have: The optical scanning device comprises: a light source unit emitting laser light; a polygon mirror rotating around a rotation axis extending in the up-down direction to reflect the laser light emitted from the light source unit so that the laser light scans the peripheral surface of an image carrier along a main scanning direction; a scanning lens to form an image of the laser light reflected by the polygon mirror on the peripheral surface of the image carrier; a housing to accommodate the light source unit, the polygon mirror and the scanning lens; and a temperature sensor to detect the temperature inside the housing; One or more of the image carriers has a photosensitive layer formed on the surface; A charging device for charging the image carrier to a predetermined surface potential; A developing device, arranged opposite to the image carrier, having a developer carrier for carrying a developer, applying a predetermined development voltage to the developer carrier to cause the toner to adhere to the electrostatic latent image formed on the image carrier, thereby forming a toner image; as well as a control unit that controls the optical scanning device and the developing device, The temperature sensor detects the temperature of the developing device. The control section controls the light scanning device according to the temperature in the housing detected by the temperature sensor, and controls the developing device according to the temperature of the developing device detected by the temperature sensor.

2. The image forming apparatus according to claim 1, wherein: Also available: An IC driver controls the light source unit; and A circuit board, on which the IC driver is mounted, is housed in the housing. The temperature sensor is mounted on the circuit substrate and is arranged on the opposite side of the IC driver across the external connection terminal on the circuit substrate.

3. The image forming apparatus according to claim 1 or 2, characterized in that: The housing has an opening facing the developing device. The temperature sensor is arranged in the housing so as to face the opening.

4. The image forming apparatus according to claim 1 or 2, wherein: The optical scanning device is arranged adjacent to the upper side of the developing device. The image forming apparatus further includes a duct disposed between the optical scanning device and the developing device and guiding heat of the developing device toward the temperature sensor.

5. The image forming apparatus according to claim 4, wherein: The inner flow passage of the pipe narrows toward the temperature sensor.

6. The image forming apparatus according to claim 5, wherein: The control unit controls the magnitude of the developing voltage according to the temperature of the developing device detected by the temperature sensor.

7. The image forming apparatus according to claim 6, wherein: The control unit stops driving the developing device when the temperature of the developing device detected by the temperature sensor exceeds a predetermined threshold value.

Images