JP2001227595A - Gear device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear device and an image forming device which can improve the durability of a gear without increasing the inertia moment of the gear, or while suppressing the increase of the inertia moment thereof. SOLUTION: Tooth flanks at four development position corresponding engagement positions A and one home position corresponding engagement position B at which the load is large and the wear is easy to generate in a revolver gear 294 are induction hardened to improve the wear resistance. A drive gear is also engaged with non-hardened tooth flanks and the wear thereof can be reduced in comparison with a case in which all tooth flanks of the revolver gear are surface-treated and hardened. In addition, the weight of the revolver gear is kept unchanged, and the inertia moment is not increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear device and an image forming apparatus used for an electrophotographic dry copying machine, a printer, a facsimile, and the like, and more particularly, to a driven gear, a drive gear, and a predetermined gear in the driven gear. The present invention relates to a gear device having a driving unit for stopping the driven gear at a rotational position, and an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses include:
A photosensitive drum as a latent image carrier on which a latent image is formed by irradiating image light with a laser beam or the like, and developing the latent image formed on the photosensitive drum with a plurality of color toners For this purpose, there is a printer having a rotatable revolver developing device having a plurality of developing devices for each color. In this type of image forming apparatus, in order to realize high-speed color switching and obtain the stop position accuracy of the revolver developing device, the number of teeth of the drive side gear is reduced (for example, the number of teeth is 14).
It is known that the number of teeth of a revolver developing device side gear (hereinafter referred to as “revolver gear”) is increased (for example, the number of teeth is 168) to increase the reduction ratio.

[0003]

In the image forming apparatus, the revolver developing device is started and stopped because the plurality of developing devices are sequentially stopped at predetermined rotation positions corresponding to the developing position with the photosensitive drum. Is repeated, so that a load is applied to the driving gear and the revolver gear. In particular, in a high-speed and high-durability image forming apparatus, a large load is applied to the driving side gear and the revolver gear during the revolving operation of the revolver developing device in order to increase the rigidity of the revolver developing device and increase the capacity of the developer. Is hanging. For this reason,
With respect to a large load, the durability of each of the gears is an issue. In particular, the driving gear having a small number of teeth is severe in durability.

Conventionally, in order to improve the wear resistance of each of the above-mentioned gears to improve the durability, high frequency hardening treatment has been applied to all the tooth surfaces of each of the gears. However, if high-frequency hardening is applied to all the tooth surfaces of the revolver gear having a large number of teeth, the durability of the drive-side gear may be reduced because the number of teeth of the drive-side gear is smaller than the number of teeth of the revolver gear. there were. In addition, since the revolver gear has a large diameter (for example, an outer diameter of φ140 mm), a decrease in tooth profile accuracy due to thermal distortion after quenching is likely to occur. further,
After quenching, the surface of the revolver gear is hardened and has a large number of teeth, which may make it difficult to perform tooth surface polishing for correcting the tooth profile. It is also conceivable to apply a surface treatment such as nitriding to the revolver gear instead of quenching.However, the nitriding treatment has a small decrease in tooth profile accuracy, but the hardening depth is smaller than that of the quenching treatment, so the wear resistance is inferior. It will be.

In order to solve the above-mentioned problem, it is conceivable to increase the tooth width of the driving gear and the revolver gear so as to disperse the load on the tooth surface. However, the revolver gear has a large diameter, and particularly when a metal material is used, an increase in the tooth width at a position away from the center increases the moment of inertia. Therefore, an increase in the moment of inertia of the revolver developing device may be caused, which may hinder speeding up of color switching.

[0006] The above-mentioned problems can occur similarly even if the rotating unit is other than the revolver developing device. It can also occur in gear devices.

The present invention has been made in view of the above background, and has as its object to improve the durability of a gear without increasing the moment of inertia of the gear or while minimizing the increase. It is an object of the present invention to provide a gear device and an image forming apparatus that can be operated.

[0008]

In order to achieve the above object, an object of the present invention is to provide a driven gear, a driving gear, a driving gear for rotating the driven gear, and a driving gear for rotating the driven gear at a predetermined rotational position. And a drive unit for stopping the
Of all the tooth surfaces of the driven gear, the tooth surface of the driven gear at the meshing position between the driven gear and the drive gear when the driven gear is stopped at the predetermined rotation position, and the front and rear of the meshing position The toothed surface of the driven gear to which a load is applied at the time of starting or stopping is subjected to a local surface treatment and cured.

In order to achieve the above object, a second aspect of the present invention provides a rotary unit rotatable with respect to an apparatus main body, and a drive unit for rotating the rotary unit to perform stop control to a predetermined rotary position. In the image forming apparatus having a driven gear provided on the rotating unit and a driving gear provided on the driving unit meshing to transmit driving and stopping the rotating unit at a predetermined rotation position, Of all the tooth surfaces of the driven gear, the tooth surface of the driven gear at the meshing position between the driven gear and the driving gear when the rotary unit is stopped at a predetermined rotation position, and the start and end of the driven gear before and after the meshing position The toothed surface of the driven gear to which a load is applied at the time of stop or stop is locally subjected to a surface treatment to be hardened.

The durability of the gear was evaluated using a revolver developing device as the rotating unit. In the image forming apparatus subjected to the durability evaluation, as shown in FIG. 6, a motor gear 296, which is a drive gear on the drive motor 295 side, and a revolver gear 294 on the revolver developing device 230 mesh with each other. The tooth surface of the motor gear 296 was subjected to induction hardening, and the tooth surface of the revolver gear 294 was subjected to nitriding. In the image forming apparatus having this configuration, 20,000 full-color images were formed, and the durability was evaluated. As a result, as shown in FIG.
It has been found that the revolver gear 294 has significantly worn tooth surfaces with two or three teeth (four locations at position A in the figure) in front and rear of the revolver gear 294 around the position where the revolver gear is in the development position and engaged with the motor gear 296. This is because a large driving load is applied when the developing device is stopped at the developing position and when the developing device is separated from the developing position, and an impact when the other gears that transmit the drive from the apparatus main body to the revolver developing device are engaged with the revolving drive. It is thought to be for. In addition, these four locations A
In addition to the above, at the home position where the developing sleeves 284 of the respective color developing units 231 are retracted from the developing position with the photoreceptor 200 after the end of the image formation, the wear progressed slightly even at the position B where the motor gear 296 is engaged. . Claim 1
In the gear device of (1) and the image forming apparatus of (2), since the tooth surface of a portion of the driven gear where a large load is likely to be worn is subjected to a surface treatment and hardened, it is possible to prevent the driven gear from being worn due to rotational driving. Can be. Further, the drive gear meshes with the non-hardened tooth surface as compared with the case where all tooth surfaces of the driven gear are subjected to surface treatment and hardened, so that wear can be reduced. Further, since the tooth surface of the driven gear is subjected to a surface treatment and hardened, the weight of the driven gear does not change and the moment of inertia does not increase.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, there is provided a latent image carrier having a latent image formed on a surface thereof, and the rotating unit is formed on the latent image carrier. A rotary developing device having a plurality of developing units for each color to develop a latent image with toners of a plurality of colors, wherein a developing unit of a predetermined color among the plurality of developing units faces the latent image carrier. The rotary developing device is rotationally driven to stop at the developing position,
Of all the tooth surfaces of the driven gear, among the tooth surfaces of the driven gear at the meshing position of the driven gear and the driving gear when stopped at the developing position, and at the time of starting or stopping before and after the meshing position. A hardening process is locally applied to the tooth surface of the driven gear to which a load is applied.

In the image forming apparatus according to the third aspect, since the tooth surface of the portion where the driven gear is liable to wear is subjected to the quenching process and hardened, compared to the case where the quenching process is applied to all the tooth surfaces. Thus, a decrease in tooth profile accuracy due to thermal distortion can be reduced.

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, the driving unit stops the rotary developing device at a predetermined rotational position so as to retract the plurality of developing units from the developing position. The tooth surface of the driven gear at the meshing position between the driven gear and the drive gear when stopped at the predetermined rotational position, and the toothed surface of the driven gear to which a load is applied at the time of starting or stopping before and after the meshing position. The present invention is characterized in that a quenching treatment is locally applied to the tooth surface.

As described in the first and second aspects, the revolver gear 294 is in the home position where the developing sleeves 284 of the respective color developing units 231 are retracted from the developing position with the photosensitive member 200 after the image formation is completed. At a position B (see FIG. 7) in which the motor gear 296 is engaged, the wear was slightly advanced. In the image forming apparatus according to the third aspect, the driven gear tooth surface at the meshing position between the driven gear and the drive gear when the rotary developing device is stopped at a predetermined retracted position, and before and after the meshing position Since the quenching process is performed on the tooth surface of the driven gear to which a load is applied at the time of the start and stop of the gear, wear of the driven gear can be further prevented.

According to another aspect of the present invention, there is provided a driven gear, a driving gear, and driving means for driving the driven gear to rotate and stopping the driven gear at a predetermined rotational position. In the gear device having, the tooth width of the driven gear at the meshing position between the driven gear and the drive gear when the driven gear is stopped at the predetermined rotation position, among the tooth surfaces of the driven gear, The tooth width of the driven gear to which a load is applied at the time of starting or stopping before and after the meshing position is made wider than the tooth width of other parts, and the tooth width of the driving gear is set to the tooth width of the driven gear. It is characterized in that it is wider than the tooth width of a narrow portion other than the wide portion.

In order to achieve the above object, according to a sixth aspect of the present invention, there is provided a rotary unit rotatable with respect to an apparatus main body, and a drive unit for rotating the rotary unit to perform stop control to a predetermined rotary position. An image forming apparatus having a driven gear provided on the rotary unit and a drive gear provided on the drive unit meshing and transmitting drive, wherein the rotary unit stops at the predetermined rotation position. The tooth width of the driven gear at the meshing position of the driven gear and the drive gear when the driven gear is engaged, and the tooth width of the driven gear that is loaded at the time of starting or stopping before and after the meshing position, The tooth width of the drive gear is wider than the width of the driven gear, and the tooth width of the driven gear is wider than the tooth width of a narrow portion other than the wide portion of the driven gear.

In the gear device according to the fifth aspect and the image forming apparatus according to the sixth aspect, the tooth width of a portion of the driven gear where a load is large and wear tends to occur is wider than the tooth width of other portions. The load on the tooth surface is dispersed when meshing with the drive gear. Thus, the wear of the driven gear and the drive gear due to the rotation can be reduced. In addition, an increase in the moment of inertia of the driven gear can be suppressed smaller than when the entire tooth width of the driven gear is widened.

According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, a portion having a narrow tooth width other than a portion having a wide tooth width of the driven gear is different from each other in a rotation axis center direction of the driven gear. It is characterized by being arranged at a position.

In the image forming apparatus according to the present invention, when the driving gear rotates, the position where the tooth surface of the narrow portion of the driven gear contacts the tooth surface of the driving gear is determined by the rotation of the driven gear. It changes in the axial direction. This disperses the portion of the drive gear that applies a load to the tooth surface within the tooth width of the drive gear, thereby preventing uneven wear of the drive gear. The same applies to a driven gear having a continuously increasing tooth width.

According to an eighth aspect of the present invention, in the image forming apparatus of the sixth or seventh aspect, the driven gear is made of a resin material.

In the image forming apparatus according to the present invention, by forming the driven gear from a resin material, the weight can be generally reduced as compared with the case where the driven gear is formed from a metal material. As a result, the inertia moment of the driven gear can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic color copying machine (hereinafter, referred to as a color copying machine) as an image forming apparatus will be described. First, the schematic configuration and operation of the color copying machine according to the present embodiment will be described with reference to FIG. This color copier includes a color image reading device (hereinafter, referred to as a color scanner) 1,
Color image recording device (hereinafter referred to as color printer)
2, a paper feed bank 3 and the like.

The color scanner 1 forms an image of the original 4 on the contact glass 101 on a color sensor 105 via an illumination lamp 102, mirror groups 103a, 103b, 103c, and a lens 104, and outputs a color image of the original 4. Image information is, for example, Red: red, Green: green, Bl
ue: Read for each color separation light of blue (hereinafter, referred to as R, G, and B, respectively) and convert it into an electric image signal. In this example, the color sensor 105 is composed of R, G, and B color separation means and a photoelectric conversion element such as a CCD in this example, and simultaneously reads three color images obtained by performing color separation on the image of the document 4. . And R obtained by this color scanner 1
Based on the G and B color separation image signal intensity levels, a color conversion process is performed by an image processing unit (not shown), and Black: black (hereinafter, referred to as Bk), Cyan: cyan (hereinafter, referred to as C), and Magenta: Magenta (hereinafter, referred to as M), Yellow: yellow (hereinafter, referred to as Y) color image data is obtained.

The operation of the color scanner 1 for obtaining the Bk, C, M, Y color image data is as follows. Upon receiving a scanner start signal that is timed with the operation of the color printer 2 described later, the optical system including the illumination lamp 102 and the mirror groups 103a, 103b, 103c scans the document 4 in the left direction of the arrow, and performs once. 1 for every scan of
Obtain color image data of a color. By repeating this operation four times in total, color image data of four colors is sequentially obtained. Then, each time the color printer 2 sequentially visualizes and superimposes the images to form a final four-color full-color image.

The color printer 2 includes a photosensitive drum 200 as an image carrier, a writing optical unit 220,
It comprises a revolver developing unit 230, an intermediate transfer device 260, a fixing device 270 and the like.

The photosensitive drum 200 rotates counterclockwise as indicated by the arrow, and the photosensitive drum cleaning device 2
01, static elimination lamp 202, charger 203, potential sensor 2
04, selected developing unit of the revolver developing unit 230, developing density pattern detector 205, intermediate transfer device 26
No. 0 intermediate transfer belt 261 and the like are arranged.

The writing optical unit 220
Converts the color image data from the color scanner 1 into an optical signal, performs optical writing corresponding to the image of the document 4, and forms an electrostatic latent image on the photosensitive drum 200. The writing optical unit 220 includes a semiconductor laser 221 as a light source, a laser emission drive control unit (not shown), a polygon mirror 222 and a rotation motor 223, an f / θ lens 224, a reflection mirror 225, and the like.

The revolver developing unit 230
Is composed of a Bk developing unit 231K, a C developing unit 231C, an M developing unit 231M, a Y developing unit 231Y, and a revolver rotation drive unit which rotates each developing unit in a counterclockwise direction indicated by an arrow. Each developing device includes a developing sleeve that rotates by contacting a spike of developer with the surface of the photosensitive drum 200 to develop an electrostatic latent image, and a developer that rotates to pump and agitate the developer. It is composed of paddles. The toner in each developing unit 231 is negatively charged by stirring with the ferrite carrier, and a developing bias in which an AC voltage Vac is superimposed on a negative DC voltage Vdc by a developing bias power supply (not shown) is applied to each developing sleeve. Is applied, and the developing sleeve is biased to a predetermined potential with respect to the metal base layer of the photosensitive drum 200. In a standby state of the copying machine main body, the revolver developing unit 230 is a Bk developing device 231.
K is set at the development position, and when the copy operation is started, the color scanner 1 starts the Bk operation from a predetermined timing.
The reading of the color image data starts, and the optical writing by the laser beam and the formation of the electrostatic latent image start based on the color image data (hereinafter, the electrostatic latent image based on the Bk image data is referred to as a Bk latent image; C, M, Y). The same applies to This B
Before the front end of the electrostatic latent image reaches the Bk development position so as to enable development from the front end of the k electrostatic latent image, the Bk development sleeve is started to rotate and the Bk electrostatic latent image is filled with Bk toner. develop.
Then, the developing operation of the Bk electrostatic latent image area is continued,
When the trailing end of the electrostatic latent image passes the Bk developing position, the revolver developing unit 230 rotates until the developing device for the next color comes to the developing position immediately. This is completed at least before the leading end of the electrostatic latent image based on the next image data arrives. The revolver developing unit 230 will be described later in detail.

The intermediate transfer device 260 includes an intermediate transfer belt 261, a belt cleaning device 262, a paper transfer corona discharger (hereinafter, referred to as a paper transfer device) 263, and the like. The intermediate transfer belt 261 is driven by the driving roller 2
64a, a transfer opposing roller 264b, a cleaning opposing roller 264c, and a group of driven rollers, which are driven and controlled by a drive motor (not shown). Further, the belt cleaning device 262 includes an inlet seal, a rubber blade,
It is composed of a discharge coil, an entrance seal, a rubber blade contacting / separating mechanism, and the like. The second, third, and fourth color images after the first color Bk image is transferred to the intermediate transfer belt 261 are transferred to the belt. During the operation, the intermediate transfer belt 261 is moved by the contact / separation mechanism.
Separate the entrance seal and blade from the surface. The paper transfer unit 263 applies an AC voltage + DC voltage or a DC voltage by a corona discharge method, and collectively transfers the superimposed toner image on the intermediate transfer belt 261 to the transfer paper 5.

The transfer paper cassette 207 in the color printer 2 and the transfer paper cassette 300 in the paper supply bank 3 are also provided.
Transfer papers 5 of various sizes are stored in a, 300b, and 300c, and paper feed rollers 208, 301a, 301b, and 301c are transferred from a cassette of transfer paper of a specified size.
Is fed and conveyed in the direction of the registration roller pair 209. On the right side of the printer 2, a manual feed tray 210 for manually feeding OHP paper or thick paper is provided.

When the image forming cycle is started in the above-described color copying machine, first, the photosensitive drum 200 is moved counterclockwise as indicated by an arrow, and the intermediate transfer belt 261 is driven clockwise as indicated by an arrow. Rotated. Formation of a Bk toner image as the intermediate transfer belt 261 rotates,
C toner image formation, M toner image formation, and Y toner image formation are performed, and finally a toner image is formed on the intermediate transfer belt 261 in the order of Bk, C, M, and Y.

The formation of the Bk toner image is performed as follows. The charger 203 uniformly charges the photosensitive drum 200 with a negative charge to about -700 V by corona discharge. Then, the semiconductor laser 221 performs raster exposure based on the Bk color image signal. When this raster image is exposed,
In the exposed portion of the photosensitive drum 200 that is initially uniformly charged, the charge proportional to the amount of exposure light disappears, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the Bk developing sleeve comes into contact with the Bk electrostatic latent image,
The toner does not adhere to the portion of the photosensitive drum 200 where the charge remains, and the Bk toner is adsorbed to the portion having no charge, that is, the exposed portion, and a Bk toner image similar to the electrostatic latent image is formed. . Then, the Bk toner image formed on the photosensitive drum 200 is transferred to the surface of the intermediate transfer belt 261 which is driven at a constant speed in contact with the photosensitive drum 200 by the belt transfer device 263 (hereinafter, photosensitive). The transfer of the toner image from the body drum 200 to the intermediate transfer belt 261 is called belt transfer).

Some untransferred residual toner on the photosensitive drum 200 is cleaned by the photosensitive member cleaning device 201 in preparation for reuse of the photosensitive drum 200. The collected toner is stored in a waste toner tank (not shown) via a collection pipe.

On the photosensitive drum 200 side, the process proceeds to the C image forming process after the Bk image forming process, and C image data reading by the color scanner 1 starts at a predetermined timing.
The formation of a C electrostatic latent image is performed by laser light writing based on the C image data. Then, after the rear end of the previous Bk electrostatic latent image has passed and before the front end of the C electrostatic latent image has reached, the rotating operation of the revolver developing unit 230 is performed,
The C developing device 231C is set at the developing position, and the C electrostatic latent image is developed with the C toner. Thereafter, the development of the C electrostatic latent image area is continued, but when the rear end of the C electrostatic latent image passes, the revolver developing unit 230 rotates as in the case of the Bk developing device 231B. Next M developing device 231
M is moved to the development position. This is also completed before the leading end of the next M electrostatic latent image reaches the developing position. Regarding the M and Y image forming processes, the operations of reading the color image data, forming the electrostatic latent image, and developing are the same as those of the above-described processes of BK and C, and thus the description is omitted.

The Bk, C, M, and Y toner images sequentially formed on the photosensitive drum 200 are sequentially aligned on the same surface of the intermediate transfer belt 261 to form a four-color superimposed toner image. In the next transfer step, the four color toner images are collectively transferred to transfer paper by the belt transfer device 263.

At the time when the image forming operation is started, the transfer paper is fed from either the transfer paper cassette or the manual feed tray, and stands by at the nip of the registration roller pair 209. Then, the intermediate transfer belt 2 is supplied to the paper transfer device 263.
When the leading end of the toner image on the sheet 61 is approaching, the registration roller pair 209 is driven so that the leading end of the transfer paper coincides with the leading end of the toner image, and registration of the transfer paper and the toner image is performed. Then, the transfer paper is superimposed on the toner image on the intermediate transfer belt 261 and passes over the paper transfer device 263 having a positive potential. At this time, the transfer paper is charged with a positive charge by the corona discharge current, and most of the toner image is transferred onto the transfer paper. Subsequently, when the paper passes through a portion opposite to a separating and neutralizing device by an AC + DC corona (not shown) disposed on the left side of the paper transferring device 263, the transfer paper is neutralized, peels off from the intermediate transfer belt 261 and moves to the transport belt 211.

The transfer paper on which the four-color superimposed toner image has been collectively transferred from the surface of the intermediate transfer belt 261 is conveyed to a fixing device 270 by a paper conveyance belt 211, and is heated by a fixing roller 271 controlled to a predetermined temperature. The toner image is fused and fixed at the nip portion of the pressure roller 272, sent out of the apparatus main body by the discharge roller pair 212, and stacked face up on a copy tray (not shown) to obtain a full color copy.

On the other hand, the photosensitive drum 200 after belt transfer
The surface of the photoconductor cleaning device 201 (brush brush)
, Rubber blade), and the static elimination lamp 2
02, the charge is uniformly removed. The surface of the intermediate transfer belt 261 after the transfer of the toner image onto the transfer paper 5 is cleaned by pressing the blade of the belt cleaning device 262 again by the blade contacting / separating mechanism.

Next, the revolver developing unit 230 will be described. FIG. 2 shows each of the developing devices 231K and 231.
FIG. 3 is a cross-sectional view showing the internal structure of the revolver developing unit 230 in which C, 231M, and 231Y are integrated, and FIG. 3 is a schematic perspective view showing the appearance of the revolver developing unit 230.
Each developing device 231K of the revolver developing unit 230,
The 231C, 231M and 231Y are respectively supported by hollow square tubular stay members 282 provided between the substantially disk-shaped front and rear end plates 230a and 230b as shown in FIG. Further, each developing unit 231K, 231C, 231
M and 231Y are the same type of developing device casing 2 respectively.
83, 283C, 283M and 283Y. Each of these developing device casing portions 283, 283C, 283
M and 283Y respectively contain a carrier as a developer and a two-component developer composed of toner of each color. In the illustrated example, the black developing device 2 containing the black toner and the carrier is located at the developing position facing the photosensitive drum 200.
At 31K, a yellow developing device 231Y containing yellow toner and a carrier, a magenta developing device 231M containing magenta toner and a carrier, and a cyan developing device 231C containing cyan toner and a carrier are arranged in a counterclockwise direction in the drawing.
It has become.

Since the internal structure of each of the four developing units is exactly the same, the internal structure of the black developing unit 231K at the developing position will be described below with reference to FIG. Regarding the structure, as the reference numerals of the corresponding members, the same numerals as the reference numerals of the black developing units are used to distinguish the yellow, magenta, and cyan developing units from each other.
Reference numerals with subscripts of M and C are shown in the figure, and the description thereof is omitted.

In the black developing device 231K at the developing position in the figure, the photosensitive drum 20 is mounted on the developing device casing 283.
The developing roller 284 is provided as a developer carrying member including a developing sleeve in which a magnet is disposed inside a developing device casing so that a part thereof is exposed through the opening. ing. In the developing device casing, the photosensitive drum 2 supported by the developing roller 284 is provided.
A doctor blade 285 that regulates the amount of the developer conveyed to the portion opposed to the fixing member 00, and a part of the developer regulated by the doctor blade 285 and pressed into the developing device casing is disposed along the central axis direction. A first transport screw 286 that transports the developer before and a second transport screw 286 that transports the developer in a direction opposite to the first transport screw 286 along the center axis direction.
A transfer screw 291 is provided. A toner concentration sensor 292 for detecting the toner concentration of the developer accommodated in the developing device casing 283 is provided in the developing device casing 283 below the second transport screw 291.
Is installed.

FIG. 4 is a longitudinal sectional view of a plane including the central axis of the first and second conveying screws 286 and 291 of the black developing device 231K. In FIG. 4, the first and second transfer screws 286 and 291 rotate in predetermined directions, respectively, so that the developer accommodated in the developing device casing 283 is stirred inside the developing device casing 283 while being stirred. It is circulated and transported. The developer circulated and conveyed is carried and conveyed on the sleeve by the rotation of the sleeve of the developing roller 284, and is thinned by the doctor blade 285.
Supply toner toward.

This revolver developing unit 230 is similar to that shown in FIG.
And the front and rear end plates 230a, 230 as shown in FIG.
b mounted on the revolver support bearings 293a, 293
It is rotatably supported by 3b. Then, the revolver gear 294 disposed on the rear end plate 230b is driven by the motor gear 296 disposed on the tip of the rotating shaft of the revolver motor 295, so that each developing device 23
1K, 231Y, 231M, and 231C are moved to predetermined developing positions, respectively, and stopped. When the developing device 231 is moved to the predetermined developing position and stopped, the developing driving gear 297a and the toner replenishing driving gear 298a are moved to the developing driving idler gear 297b and the toner replenishing driving idler gear 298b at the stopped position. The meshing enables the developing operation and the toner replenishing operation.

Next, the configuration of the revolver gear 294 and the motor gear 296, which are characteristic parts of this embodiment, will be described. FIG. 5 is a top view of the vicinity of the revolver motor 295. FIG. 6 is a view showing a state in which the revolver gear 294 and the motor gear 296 are engaged as described above.

As shown in FIG. 5, the revolver motor 295 has a motor mount 29 interposed between a motor bracket 28 screwed to a rear plate 26 of the apparatus main body and a bearing holder 27 into which a revolver support bearing 293b is press-fitted. Attached through. In order to regulate the position of the revolver motor 295 and prevent the motor gear 296 from skipping, the holding bracket 31 is attached to the motor bracket 28. Also, the revolver motor 2
At the rear end of the rotation shaft 95, a mechanical damper 30 for suppressing vibration and improving high-speed performance is provided.

As the revolver motor 295, a stepping motor can be used. The revolver motor 295 is operated in a cycle of an acceleration operation, a constant speed operation, and a deceleration operation when the revolver developing unit 230 revolves 90 degrees at the time of color switching.

As described above, the revolver gear 294 has a tooth surface at four positions A (hereinafter referred to as "developing position-corresponding meshing positions A") which engage with the motor gear 296 when each color developing device is at the developing position in FIG. Wear is remarkable. Therefore, the revolver gear 29 according to the present embodiment
In No. 4, only high-frequency quenching treatment was performed on only the tooth surface at the meshing position A corresponding to the developing position among the tooth surfaces of the revolver gear 294 to improve wear resistance. More specifically, for example, a metal material of SMF4040 (JIS) is used and a revolver gear 294 having 168 teeth is provided.
High frequency quenching treatment was performed on the tooth surface having six teeth per location at the meshing position A corresponding to the developing position. Also,
Using a metal material of SMF4040, high-frequency hardening treatment was applied to all the tooth faces of the motor gear 296 having 14 teeth. In addition, the induction hardening treatment of both gears has an effective hardening depth of 0.5 mm or more and a total hardening depth of 3 mm.
Less than, surface hardness (Hv) 500 or more, limit hardness (H
v) was 350 or more.

With the above configuration, the revolver gear 294
The revolver gear 294 is prevented from being worn by applying a high frequency hardening process only to the tooth surface at the meshing position A corresponding to the developing position where a large load is applied due to the driving of the revolver developing unit 230 and is easily worn out. be able to. In addition, since the motor gear 296 meshes with the uncured tooth surface of the revolver gear 294, wear can be reduced and durability can be improved as compared with a case where all tooth surfaces are hardened. Further, it is possible to prevent a decrease in tooth profile accuracy due to thermal distortion after the quenching process, and it is necessary to polish the tooth surface, as compared with a case where induction hardening is performed on all the tooth surfaces of the revolver gear 294. Since the number of parts is small, productivity can be improved.

As described above, the revolver gear 29
Reference numeral 4 denotes a developing sleeve 2 of each color developing device 231 after image formation.
When the position 84 is at the home position retracted from the developing position with the photoconductor 200, the tooth surface at the position B meshing with the motor gear 296 (hereinafter referred to as the "meshing position B corresponding to the home position") is also easily worn. Therefore, the high-frequency hardening process is also performed on the tooth surface at the mesh position B corresponding to the home position, so that the revolver gear 294 is formed.
Can be further prevented, and the durability can be improved.

[Second Embodiment] In the first embodiment, high frequency quenching is applied only to the tooth surface of the revolver gear 294 where a large load is applied, thereby preventing wear of the revolver gear 294 and the motor gear 296. However, a configuration in which the tooth width of a portion where a large load is applied is widened may be adopted. FIG. 8 is a diagram showing a configuration in which the tooth width of the revolver gear 294 at a position corresponding to the meshing position A corresponding to the developing position shown in FIG. 7 is locally widened. In FIGS. 8 to 10, an ear-shaped mounting portion for mounting the revolver gear 294 to the revolver developing unit 230 is omitted.

If the entire tooth width of the revolver gear 294 is increased, the load on the tooth surface is dispersed, so that the durability is improved.
Since the moment of inertia increases, it is disadvantageous in increasing the speed of the revolver developing unit 230. Therefore, only the tooth width of the portion of the revolver gear 294 to which a large load is applied, that is, the tooth width of the meshing position A corresponding to the developing position is widened, and the tooth width of the motor gear 296 (not shown) is wider than the tooth width of the narrow portion of the revolver gear 294. Configured. For example, the portion of the revolver gear 294 having a small tooth width has a tooth width of 10 mm, the wide portion has a tooth width of 30 mm, and the motor gear 296 has a tooth width of 30 mm.

With the above configuration, the load on the tooth surface is dispersed in the portion where the tooth width of the revolver gear 294 is wide, and wear of the revolver gear 294 and the motor gear 296 can be prevented to improve durability. Further, as compared with a case where all the tooth widths of the revolver gear 294 are widened, an increase in weight can be suppressed and an increase in moment of inertia can be suppressed as much as possible.

If the shape of the tooth width is gradually increased as shown in FIG. 9 in accordance with the change in the load applied to the tooth surface of the revolver gear 294, the weight of the revolver gear 294 can be further reduced, and the moment of inertia can be reduced. Can be kept smaller.

Further, as shown in FIG. 10, the portion of the revolver gear 294 having a narrower tooth width may be alternately arranged so that the overlap portion is reduced as much as possible. By adopting such a shape, the portion of the tooth surface of the motor gear 296 that is subjected to a load is dispersed within the tooth width, and uneven wear of the motor gear 296 can be prevented, so that the durability of the motor gear 296 can be improved. In the example shown in the figure, narrow portions are arranged in the upper and lower two stages, but may be arranged in, for example, four stages in accordance with the rate of change in the revolving load.

The revolver gear 29 according to the present embodiment
The material of No. 4 is not limited to a metal material such as the SMF4040 (JIS), but may be a resin material such as polycarbonate containing 30% glass fiber. Since the resin material is generally lighter in weight than the metal material, it is possible to reduce the moment of inertia of the revolver gear 294 even if the tooth width is increased only in a portion where a large load is applied.

In the above embodiment, the rotary unit is a developing unit. However, the present invention is applicable to any rotary unit that is driven and stopped by a motor and can cause gear wear due to some inertia. The present invention can be applied to a case other than the developing unit. Further, the present invention can be applied to a gear device having a driving gear and a driven gear.

[0057]

According to the first to eighth aspects of the present invention, an excellent effect that the durability of the gear can be improved without increasing the inertia moment of the gear or while minimizing the increase. There is.

In particular, according to the first to fourth aspects of the present invention, in the driven gear, a surface treatment is locally performed only on a tooth surface of a portion of the entire tooth surface where the load on the tooth surface is large and wear is likely to occur. Since it is hardened, there is an excellent effect that wear of the driven gear and the drive gear can be prevented and durability can be improved. Further, even if the tooth surface of the driven gear is subjected to a surface treatment, the weight does not change, so that the inertia moment does not increase.

In particular, according to the third and fourth aspects of the present invention, it is possible to reduce the number of portions that require precision control of the tooth profile after the quenching process as compared with the case where the quenching process is performed on all the tooth surfaces of the driven gear. At the same time, it is possible to reduce the number of portions requiring tooth surface polishing. Thereby, there is an excellent effect that the productivity of the driven gear can be improved.

In particular, according to the invention of claims 6 to 8, in the driven gear, a portion having a large load on the tooth surface is formed to have a wider tooth width than other portions, and the tooth width of the drive gear is reduced. It is wider than the tooth width of the narrow part other than the tooth width of the wide part. Thus, there is an excellent effect that it is possible to suppress the increase in the moment of inertia due to the increase in the weight of the driven gear as much as possible while ensuring the durability of each gear.

In particular, according to the invention of claim 7, the portion of the drive gear which is loaded on the tooth surface within the tooth width of the drive gear is dispersed, and uneven wear of the drive gear can be prevented, and the durability is further improved. There is an excellent effect that it can be performed.

In particular, according to the invention of claim 8, it is possible to suppress an increase in the moment of inertia of the driven gear by forming the driven gear from a resin material as compared with a case where the driven gear is formed from a metal material. Has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of a color copying machine according to an embodiment of the present invention.

FIG. 2 is a sectional view of a revolver developing unit of the color copying machine.

FIG. 3 is a schematic perspective view of the revolver developing unit.

FIG. 4 is a schematic plan view of a toner conveying unit and a driving unit of the revolver developing unit.

FIG. 5 is a diagram showing a schematic configuration near a revolver motor of the revolver developing unit.

FIG. 6 is a front view of a drive system of the revolver developing unit.

FIG. 7 is a diagram illustrating a portion where the load of the revolver gear is large.

FIG. 8 is a perspective view of a revolver gear in which a tooth width of a portion having a large load is widened.

FIG. 9 is a perspective view of a revolver gear in which a tooth width of a portion having a large load is widened and an increase in weight is reduced.

FIG. 10 is a perspective view of a revolver gear having a shape in which portions having narrow tooth widths are alternately arranged so that the overlap portion is reduced as much as possible.

[Explanation of symbols]

2 Color Printer 28 Motor Bracket 29 Motor Mount 30 Mechanical Damper 31 Press Bracket 200 Photoconductor Drum 230 Revolver Developing Units 231K, 231C, 231M, 231Y Developing Devices 284, 284C, 284M, 284Y Developing Rollers 284a Developing Roller Shaft 294 Revolver Gear 295 Revolver Motor 296 Motor gear

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 506 G03G 15/08 506A 507 C21D 9/32 A // C21D 9/32 G03G 15/08 507H

Claims (8)

[Claims] 1. A gear device having a driven gear, a driving gear, and driving means for driving the driven gear to rotate and stopping the driven gear at a predetermined rotation position, wherein all tooth surfaces of the driven gear are provided. The tooth surface of the driven gear at the meshing position between the driven gear and the drive gear when the driven gear is stopped at the predetermined rotational position, and a load at the time of starting or stopping before and after the meshing position. A gear device characterized in that a tooth surface of the driven gear to which a gear is applied is locally surface-treated and hardened. 2. A driven gear, comprising: a rotary unit rotatable with respect to the apparatus main body; and a drive unit for driving the rotary unit to rotate and performing stop control to a predetermined rotation position. And an image forming apparatus in which a drive gear provided in the drive unit meshes and transmits drive to stop the rotation unit at a predetermined rotation position. In the image forming apparatus, among the tooth surfaces of the driven gear, the rotation unit is Tooth surface of the driven gear at the meshing position between the driven gear and the driving gear when stopped at a predetermined rotation position, and tooth surface of the driven gear to which a load is applied when starting or stopping before and after the meshing position An image forming apparatus characterized in that a surface treatment is locally applied to the composition and cured. 3. The image forming apparatus according to claim 2, further comprising a latent image carrier on which a latent image is formed on the surface, wherein the rotating unit is configured to convert the latent image formed on the latent image carrier into a plurality of colors. Is a rotary developing device provided with a plurality of developing units for each color in order to develop with the toner of the type described above, wherein a developing unit of a predetermined color among the plurality of developing units is stopped at a developing position facing the latent image carrier. The rotary developing device is rotationally driven as described above, and among all the tooth surfaces of the driven gear, the tooth surface of the driven gear at the meshing position between the driven gear and the driving gear when stopped at the developing position,
And an image forming apparatus in which a quenching process is locally performed on the tooth surface of the driven gear to which a load is applied when starting or stopping before and after the meshing position. 4. The image forming apparatus according to claim 3, wherein said drive unit stops said rotary developing device at a predetermined rotational position so as to retract said plurality of developing units from said developing position. The tooth surface of the driven gear at the meshing position of the driven gear and the driving gear when stopped at the position, and the tooth surface of the driven gear to which a load is applied at the time of starting or stopping around the meshing position. An image forming apparatus characterized in that a quenching process is performed on the image. 5. A gear system comprising a driven gear, a driving gear, and driving means for rotating and driving the driven gear and stopping the driven gear at a predetermined rotation position, wherein all tooth surfaces of the driven gear are provided. The tooth width of the driven gear at the meshing position of the driven gear and the driving gear when the driven gear is stopped at the predetermined rotational position, and the load at the time of starting or stopping before and after the meshing position. , The tooth width of the driven gear is wider than the tooth width of the other part, and the tooth width of the drive gear is the tooth width of the narrow part other than the wide part of the driven gear. A gear device characterized by being wider than that. 6. A rotating unit rotatably movable with respect to the apparatus main body, and a driving unit for driving the rotating unit to rotate and performing stop control to a predetermined rotation position, wherein the driven unit is provided on the rotating unit. In an image forming apparatus in which a gear meshes with a drive gear provided in the drive unit to transmit driving, meshing between the driven gear and the drive gear when the rotation unit is stopped at the predetermined rotation position The tooth width of the driven gear at the position, and the tooth width of the driven gear to which a load is applied at the time of starting or stopping before and after the meshing position are made wider than the tooth width of other parts, and An image forming apparatus characterized in that the tooth width is wider than the tooth width of a portion of the driven gear having a small tooth width other than the portion having a wide tooth width. 7. The image forming apparatus according to claim 6, wherein a portion of the driven gear having a narrow tooth width other than a portion of the driven gear having a large tooth width is arranged at a plurality of different positions in the rotation axis direction of the driven gear. An image forming apparatus. 8. The image forming apparatus according to claim 6, wherein
An image forming apparatus, wherein the driven gear is made of a resin material.