Drive device and image forming apparatus

Abstract

To make it possible to generate a force which suppresses a thrust force acting during rotation without using a removal prevention member.SOLUTION: In a drive gear 82, a tooth part 822 formed by helical teeth each having a tooth muscle which is oblique to an outer peripheral surface of a gear body 821 is provided over an entire periphery. A thrust force which acts toward a tip along an axial direction of a drive shaft 76 is exerted on the drive gear 82 during rotation. The gear body 821 of the drive gear 82 is provided with: protruding parts which form parts of a removal prevention part so as to allow movement of the drive shaft 76 in a circumferential direction; and an opening 826 which is one example of the removal prevention part which moves in the circumferential direction to contact with a part of a rotary shaft 76 and thereby prevent movement in the axial direction.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] This invention is Drive unit and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, techniques relating to drive devices used in image forming apparatuses have already been proposed, for example, as disclosed in Patent Documents 1 to 3.

[0003] In Patent Document 1, the driving force transmission device is provided with a snap fit portion that fits into a groove portion of the fixed shaft via a gap and prevents the driving force transmission device from coming loose, and the driving force transmission device is configured so that the thrust force acting when the device rotates is directed toward the abutment member, and the dimensions are set so that a gap is formed between the snap fit portion of the driving force transmission device and the groove portion of the fixed shaft when the end of the driving force transmission device is in contact with the abutment member.

[0004] In Patent Document 2, the drive output member receives a first force from the driven member in a direction away from the rotation shaft when driving the driven member, and receives a second force from the drive transmission member in a direction opposite to the first force when driven by the drive output member, and the second force is configured to be the same as or greater than the first force.

[0005] Patent Document 3 discloses a driving force transmission member provided across the outside and inside of a developer container, which receives driving force from the device main body via a helical gear provided on the outside of the developer container and transmits it to an agitator inside the developer container; a locking portion provided on the inside of the developer container, which abuts against the inner wall of the developer container to prevent the driving force transmission member from slipping out of the developer container; a thrust receiving portion provided on the developer container; and an abutting portion provided on the driving force transmission member, which abuts against the thrust receiving portion to regulate the position of the driving force transmission member when the driving force is transmitted to the helical gear and the thrust force of the helical gear causes the locking portion to move away from the inner wall of the developer container, and the abutting portion is configured so that the distance K1 between the abutting portion and the locking portion is greater than the distance K2 from the thrust receiving portion to the inner wall (K1>K2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-226439 [Patent Document 2] Japanese Patent Application Publication No. 2019-139162 [Patent Document 3] Patent No. 3352328 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to make it possible to generate a force that suppresses the thrust force acting during rotation without using a retaining member. [Means for solving the problem]

[0008] The invention described in claim 1 is A drive shaft; Gears and Equipped with The gear is The aforementioned a gear body having teeth that are oblique to the axial direction and that is attached to an end of the drive shaft along the axial direction; a retaining portion provided on the gear body to allow movement in a circumferential direction relative to the drive shaft, the retaining portion moving in the circumferential direction to come into contact with a part of the drive shaft and prevent movement in an axial direction; With death, The retaining portion is composed of an opening through which a double D-cut portion having two D-cut surfaces provided via a cylindrical portion at the end of the drive shaft can be inserted, The gear is inserted into the double D-cut portion of the drive shaft through the opening, and by rotating the drive shaft in the circumferential direction, the opening abuts against the inner end surface of the double D-cut portion of the drive shaft along the axial direction, thereby preventing it from coming off. is.

[0009] The invention described in claim 2 is characterized in that the drive shaft is formed at an end along the axial direction. double D-cut portion and the double The part just before the tip of the D-cut section double 2. The cylindrical portion according to claim 1, having an outer diameter equal to or smaller than the D-cut portion. Drive unit is.

[0010] The invention described in claim 3 is characterized in that the retaining portion is capable of inserting the drive shaft therethrough, and allows the drive shaft to move in the circumferential direction while retaining the drive shaft. double 3. The method according to claim 2, further comprising: Drive unit is.

[0011] The invention described in claim 4 is double 4. The drive shaft according to claim 2, wherein the D-cut portion is a double D-cut portion having two D-cut surfaces facing each other parallel to the central axis at an end portion along the axial direction of the drive shaft. Drive unit is.

[0012] In the invention described in claim 5, the retaining portion has an opening at a base end along the insertion direction of the insertion hole, through which the tip of the drive shaft can be inserted. Claim 3 Described in Drive unit is.

[0013] The invention described in claim 6 is the invention described in claim 5, wherein the opening is formed in the same shape as the tip of the drive shaft. Drive unit is.

[0014] The invention described in claim 7 is The gear is The aforementioned an insertion portion through which the drive shaft is inserted in the axial direction; a tooth portion having a tooth trace oblique to the drive shaft; a permitting portion provided in the insertion portion and permitting movement of the drive shaft in a circumferential direction while the drive shaft is inserted into the insertion portion; A shaft is disposed in the axial direction of the allowable portion to prevent movement in the axial direction. The aforementioned A retaining portion; Equipped with 7. The drive device according to claim 1. is.

[0016] Claim 8 The invention described in the item (1) comprises an image forming means for forming an image, a driving means for driving the image forming means; Equipped with As the driving means Any of claims 1 to 7 2 is an image forming apparatus using the driving device described in [Effects of the Invention]

[0017] According to the invention described in claim 1, it is possible to generate a force that suppresses the thrust force that acts during rotation without using a retaining member.

[0018] According to the invention described in claim 2, the D-cut portion on the tip side of the cylindrical portion can function as a retaining portion, compared to when the drive shaft does not have a cylindrical portion with an outer diameter smaller than that of the D-cut portion just before the tip of the D-cut portion.

[0019] According to the invention described in claim 3, the retaining portion can be configured by utilizing the insertion hole, which allows the drive shaft to be inserted therethrough, compared to a case where the retaining portion does not have an insertion hole that abuts against the D-cut portion while allowing the drive shaft to move circumferentially.

[0020] According to the invention described in claim 4, the D-cut portion can transmit the torque of the drive shaft to the gear body more reliably than when the D-cut portion has only one D-cut surface formed parallel to the central axis at the end along the axial direction of the drive shaft.

[0021] According to the invention described in claim 5, the configuration of the anti-slip portion can be simplified compared to when the anti-slip portion does not have an opening at the base end along the insertion direction of the insertion hole through which the tip of the drive shaft can be inserted.

[0022] According to the invention described in claim 6, the structure of the retaining portion can be simplified compared to when the opening is not formed in the same shape as the tip of the drive shaft.

[0023] According to the seventh aspect of the invention, it is possible to generate a force that suppresses the thrust force that acts during rotation without using a retaining member.

[0025] Claim 8 According to the invention described in Any of claims 1 to 7 The configuration of the drive device can be simplified compared to when the drive device described above is not used. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus to which a drive device according to a first embodiment of the present invention is applied. [Figure 2] 1 is a cross-sectional view showing the configuration of an image forming device of an image forming apparatus according to a first embodiment of the present invention; [Figure 3] 1 is a perspective view showing the configuration of an imaging device according to a first embodiment of the present invention; [Figure 4] 1 is a cross-sectional view showing the configuration of an imaging device according to a first embodiment of the present invention. [Figure 5] 1 is a cross-sectional view showing the configuration of a main part of an image forming apparatus to which an image forming device according to a first embodiment of the present invention is applied. [Figure 6] 1 is a perspective view showing the configuration of a main part of an imaging device according to a first embodiment of the present invention; [Figure 7] FIG. 2 is a perspective view showing a drive shaft. [Figure 8] FIG. [Figure 9] 1 is a perspective configuration diagram showing a gear according to a first embodiment of the present invention. [Figure 10] 1 is a perspective configuration diagram showing a gear according to a first embodiment of the present invention. [Figure 11] 1 is a front configuration view showing a gear according to a first embodiment of the present invention. [Figure 12] FIG. 4 is a cross-sectional view showing a state in which a drive gear is attached to a drive shaft. [Figure 13] FIG. 10 is a cross-sectional view showing a state in which a drive gear is attached to a drive shaft during driving. [Figure 14] FIG. 10 is a cross-sectional view showing the state in which the drive gear is attached to the drive shaft during assembly. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0028] [Embodiment 1] 1 shows an image forming apparatus to which the gears and drive device according to embodiment 1 are applied. In the figure, the width direction along the horizontal direction of the image forming apparatus is the X direction, the depth direction along the horizontal direction of the image forming apparatus is the Y direction, and the height direction along the vertical direction of the image forming apparatus is the Z direction.

[0029] <Overall configuration of image forming apparatus> The image forming apparatus 1 according to the first embodiment is configured as, for example, a color printer. The size of the device body 1a along the X direction of this image forming apparatus 1 is equivalent to that of a conventional full-color printer, and in addition to full-color images consisting of four colors, yellow (Y), magenta (M), cyan (C), and black (K), it is also possible to simultaneously form images of metallic colors such as gold (G) and silver (S), single colors such as red (R), green (G), and blue (B), corporate colors such as Mizuho Financial Group's Cosmic Blue and Horizon Red, and specific colors (hereinafter referred to as "spot colors") consisting of various hues such as transparency and white.

[0030] This image forming apparatus 1 includes a plurality of image creating devices 10 that form toner images developed with toner constituting a developer 4; an intermediate transfer device 20 that holds each toner image formed by the image creating devices 10 and transports it to a secondary transfer position where it is finally secondarily transferred onto a recording sheet 5 (an example of a recording medium); a paper feeder 50 that stores and transports the required recording sheet 5 to be supplied to the secondary transfer position of the intermediate transfer device 20; and a fixing device 40 that fixes the toner image on the recording sheet 5 that has been secondarily transferred by the intermediate transfer device 20. The plurality of image creating devices 10 and the intermediate transfer device 20 constitute an image forming section 2 that forms an image on the recording sheet 5. The device body 1a of the image forming apparatus 1 is formed by supporting structural members, an exterior cover, etc. The two-dot chain line in the figure indicates the main transport path along which the recording sheet 5 is transported within the device body 1a.

[0031] The imaging device 10 is composed of four imaging devices 10Y, 10M, 10C, and 10K, each dedicated to forming a toner image of four colors—yellow (Y), magenta (M), cyan (C), and black (K)—and an imaging device 10S, which forms a toner image of a special color (S). These five imaging devices 10 (S, Y, M, C, and K) are arranged in a line along the X direction in the internal space of the device main body 1a. In the illustrated embodiment, the special color imaging device 10S is arranged most upstream in the direction of movement of the intermediate transfer belt 21 of the intermediate transfer device 20, and the yellow (Y), magenta (M), cyan (C), and black (K) imaging devices 10 (Y, M, C, and K) are arranged sequentially along the direction of movement of the intermediate transfer belt. However, the placement of the special color image forming device 10S is not limited to this, and it may be placed at the most downstream side along the direction of movement of the intermediate transfer belt, or it may be placed between the yellow (Y), magenta (M), cyan (C) and black (K) image forming devices 10 (Y, M, C, K).

[0032] Each of the image forming devices 10 (S, Y, M, C, K) has the same configuration except for the color of the image to be formed. Each of the image forming devices 10 (S, Y, M, C, K) has a rotating photosensitive drum 11 as an example of an image carrier (image forming means). Around the photosensitive drum 11, the following devices as examples of image forming means are mainly arranged. The main devices are a charging device 12 that charges the peripheral surface (image bearing surface) of the photosensitive drum 11, on which an image can be formed, to a required potential; an exposure device 13 that irradiates the charged peripheral surface of the photosensitive drum 11 with light based on image information (signal) to form an electrostatic latent image (for each color) with a potential difference; developing devices 14 (S, Y, M, C, K) that develop the electrostatic latent image with toner of the developer 4 of the corresponding color (S, Y, M, C, K) to form a toner image; primary transfer devices 15 (S, Y, M, C, K) that transfer each toner image to an intermediate transfer device 20; and drum cleaning devices 16 (S, Y, M, C, K) that remove and clean any toner and other deposits that remain on the image bearing surface of the photosensitive drum 11 after the primary transfer.

[0033] The photoreceptor drum 11 has an image bearing surface formed on the circumferential surface of a grounded cylindrical or columnar substrate, which has a photoconductive layer (photosensitive layer) made of a photosensitive material. The photoreceptor drum 11 is supported so that it rotates in the direction indicated by arrow A by power transmitted from a drive device (not shown).

[0034] The charging device 12 is composed of a contact-type charging roll 121 that is placed in contact with the photosensitive drum 11. A cleaning roll 122 that cleans the circumferential surface of the charging roll 121 is placed on the back side of the charging roll 121. A charging voltage is supplied to the charging device 12. If the developing device 14 performs reversal development, the charging voltage supplied is a voltage or current of the same polarity as the charging polarity of the toner supplied from the developing device 14. Note that the charging device 12 may also be a non-contact charging device such as a scorotron that is placed in a non-contact state on the surface of the photosensitive drum 11.

[0035] The exposure device 13 is an LED print head that forms an electrostatic latent image by irradiating the photosensitive drum 11 with light corresponding to image information using LEDs (Light Emitting Diodes) as a plurality of light-emitting elements arranged along the axial direction of the photosensitive drum 11. Note that the exposure device 13 may also be one that deflects and scans laser light configured according to the image information along the axial direction of the photosensitive drum 11.

[0036] 2, each of the developing devices 14 (S, Y, M, C, K) is configured by arranging, inside a housing 140 formed with an opening and a chamber for storing developer 4, a developing roll 141 as an example of a developer holder that holds developer 4 and transports it to a development area facing the photosensitive drum 11, a supply auger 142 as an example of agitation and supply means that agitates the developer 4 and transports it so that it passes through the developing roll 141, an admix auger 143 as an example of agitation and transport means that agitates the developer 4 and transports it to the supply auger 142, a counter auger 144 that transports the developer 4 peeled from the developing roll 141 in a direction opposite to the transport direction of the admix auger 143, and a layer thickness regulating member 145 that regulates the amount (layer thickness) of developer held on the developing roll 141. In this developing device 14, a development voltage is supplied between the developing roll 141 and the photosensitive drum 11 from a power supply device (not shown). The developing roll 141, supply auger 142, and admix auger 143 rotate in the required direction by power transmitted from a drive device described later. Furthermore, two-component developers containing non-magnetic toner and magnetic carrier are used as the five color developers 4 (S, Y, M, C, and K). The configuration of the developing device 14 will be described in detail later.

[0037] The developing devices 14 (S, Y, M, C, K), particularly the spot color developing device 14S, are configured to be detachable from the device main body 1a of the image forming device 1. The developing devices 14 (S, Y, M, C, K) can be replaced by a user with a new developing device 14 (Y, M, C, K) or a developing device 14S of another spot color.

[0038] The primary transfer device 15 (S, Y, M, C, K) is a contact-type transfer device equipped with a primary transfer roll that rotates in contact with the periphery of the photosensitive drum 11 via the intermediate transfer belt 21 and is supplied with a primary transfer voltage. As the primary transfer voltage, a DC voltage showing a polarity opposite to the charge polarity of the toner is supplied from a power supply device (not shown).

[0039] The drum cleaning device 16 is composed of a container-shaped main body 160 with a portion open, a cleaning plate 161 that is arranged so as to come into contact with the peripheral surface of the photosensitive drum 11 after primary transfer with a required pressure to remove and clean any adhering matter such as residual toner, and a delivery member 162 such as a screw auger that collects the adhering matter such as toner removed by the cleaning plate 161 and transports it to a recovery system (not shown). The cleaning plate 161 is a plate-shaped member (for example, a blade) made of a material such as rubber.

[0040] 1, the intermediate transfer device 20 is disposed below each of the image forming devices 10 (S, Y, M, C, K) in the Z direction. The intermediate transfer device 20 is mainly composed of an intermediate transfer belt 21 that rotates in the direction indicated by arrow B while passing through a primary transfer position between the photosensitive drum 11 and the primary transfer device 15 (primary transfer roll), a plurality of belt support rolls 22-25 that rotatably support the intermediate transfer belt 21 while maintaining a desired state from its inner surface, a secondary transfer device 30 as an example of secondary transfer means that is disposed on the outer peripheral surface (image bearing surface) of the intermediate transfer belt 21 supported by the belt support roll 25 and performs a second transfer of the toner image on the intermediate transfer belt 21 to the recording paper 5, and a belt cleaning device 26 that removes and cleans toner, paper dust, and other deposits that remain on the outer peripheral surface of the intermediate transfer belt 21 after passing through the secondary transfer device 30.

[0041] An endless belt made of a material in which a resistance adjuster such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin is used as the intermediate transfer belt 21. The belt support roll 22 is configured as a drive roll that is rotated by a drive unit (not shown) and also serves as an opposing roll for the belt cleaning device 26, the belt support roll 23 is configured as a surface finishing roll that forms the image forming surface of the intermediate transfer belt 21, the belt support roll 24 is configured as a tension applying roll that applies tension to the intermediate transfer belt 21, and the belt support roll 25 is configured as an opposing roll that faces the secondary transfer device 30.

[0042] 1, the secondary transfer device 30 is a contact-type transfer device that includes a secondary transfer roll 31 that rotates in contact with the circumferential surface of the intermediate transfer belt 21 and is supplied with a secondary transfer voltage at a secondary transfer position, which is the outer circumferential surface of the intermediate transfer belt 21 supported by the belt support roll 25 of the intermediate transfer device 20. A DC voltage having the same polarity as or opposite to the charge polarity of the toner is supplied as the secondary transfer voltage from a power supply device (not shown) to the secondary transfer roll 31 or the belt support roll 25 of the intermediate transfer device 20.

[0043] The fixing device 40 is configured so that, inside a housing (not shown) in which an inlet and an outlet for the recording paper 5 are formed, a heating belt 41 that rotates in the direction indicated by the arrow and is heated by a heating means so that the surface temperature is maintained at a predetermined temperature, and a pressure roll 42 that rotates in contact with the heating belt 41 at a predetermined pressure and is driven to rotate substantially along the axial direction of the heating belt 41, are arranged. In this fixing device 40, the contact area where the heating belt 41 and the pressure roll 42 come into contact is a fixing processing section that performs the required fixing process (heating and pressurizing).

[0044] The paper feeder 50 is disposed below the intermediate transfer device 20 in the Z direction. This paper feeder 50 is mainly composed of one (or more) paper containers 51 that contain stacks of recording paper 5 of desired sizes and types, and feeders 52, 53 that feed the recording paper 5 one sheet at a time from the paper container 51. The paper container 51 is attached so that it can be pulled out, for example, from the front side of the device main body 1a (the side that the user faces during operation).

[0045] Examples of the recording paper 5 include plain paper used in electrophotographic copiers, printers, etc., thin paper such as tracing paper, and overhead projector sheets. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper 5 is as smooth as possible, and for example, coated paper in which the surface of plain paper is coated with a resin or the like, or so-called thick paper with a relatively large basis weight such as art paper for printing, can also be suitably used.

[0046] Between the paper feed device 50 and the secondary transfer device 30, there is provided a paper feed transport path 56 which is composed of one or more paper transport roll pairs 54, 55 and a transport guide (not shown) that transport the recording paper 5 fed from the paper feed device 50 to the secondary transfer position. The paper transport roll pair 55, which is located immediately before the secondary transfer position in the paper feed transport path 56, is configured as, for example, a roll (registration roll) that adjusts the transport timing of the recording paper 5. Between the secondary transfer device 30 and the fixing device 40, there is provided a transport belt 57 for transporting the recording paper 5 fed from the secondary transfer device 30 after the secondary transfer to the fixing device 40. Further, downstream of the fixing device 40, there is provided a curl correction device 58 that corrects curls in the recording paper 5 that has been fixed by the fixing device 40. Near a paper discharge port formed in the device main body 1a of the image forming apparatus 1, there is provided a discharge transport path 60 which includes a paper discharge roll pair 59 for discharging the fixed recording paper 5 fed by the curl correction device 58 to a paper discharge section (not shown) provided on one side of the device main body 1a.

[0047] On the upstream side of the discharge conveyance path 60 in the conveyance direction of the recording paper 5, there is provided a branch conveyance path 62 equipped with a paper conveyance roll pair 61 that branches the conveyance direction of the recording paper 5 sent out by the curl correction device 58 diagonally downward. Below the branch conveyance path 62, there is arranged a reversing conveyance path 64 equipped with a reversing roll pair 63 that reverses the front and back of the recording paper 5. Above the reversing conveyance path 64, there are formed branching paths into a discharge conveyance path 66 equipped with a paper discharge roll pair 65 for discharging the recording paper 5 that has been reversed by the reversing conveyance path 64 to a paper discharge section (not shown), and a duplex conveyance path 68 equipped with a duplex conveyance roll pair 67 for forming an image on the back side of the recording paper 5 that has been reversed by the reversing conveyance path 64.

[0048] 1, reference numeral 200 indicates a control device that comprehensively controls the operation of the image forming apparatus 1. The control device 200 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), or a bus connecting the CPU, ROM, etc., a communication interface, etc. (not shown).

[0049] <Operation of image forming device> The basic image forming operation of the image forming apparatus 1 will be described below.

[0050] Here, we will explain the operation in the special color + full color mode, which uses the five image creating devices 10 (S, Y, M, C, K) to form a full color image composed of a combination of four color (Y, M, C, K) toner images, and a special color (S) image.

[0051] When the image forming apparatus 1 receives image information and command information requesting a full-color image forming operation (printing) from a personal computer (not shown) or an image reading device, etc., via a communication unit (not shown), the control device 200 starts the five image forming devices 10 (S, Y, M, C, K), the intermediate transfer device 20, the secondary transfer device 30, the fixing device 40, etc.

[0052] 1, in each imaging device 10 (S, Y, M, C, K), first, each photosensitive drum 11 rotates in the direction indicated by arrow A, and each charging device 12 charges the surface of each photosensitive drum 11 to a required polarity (negative polarity in the first embodiment) and potential. Next, exposure device 13 irradiates the surface of the charged photosensitive drum 11 with light emitted based on image information obtained by converting image information input to image forming device 1 into each color component (S, Y, M, C, K), and forms electrostatic latent images of each color component composed of a required potential difference on the surface.

[0053] Next, each image forming device 10 (S, Y, M, C, K) supplies toner of the corresponding color (S, Y, M, C, K) charged to the required polarity (negative polarity) from the developing roll 141 to electrostatically adhere to the electrostatic latent image of each color component formed on the photosensitive drum 11, thereby developing it. Through this development, the electrostatic latent image of each color component formed on each photosensitive drum 11 is visualized as a toner image of five colors (S, Y, M, C, K) developed with the toner of the corresponding color.

[0054] Next, when the toner images of each color formed on the photosensitive drum 11 of each image creating device 10 (S, Y, M, C, K) are transported to the primary transfer position, the primary transfer device 15 (S, Y, M, C, K) performs primary transfer of the toner images of each color in a state where they are superimposed in order onto the intermediate transfer belt 21 rotating in the direction indicated by arrow B of the intermediate transfer device 20.

[0055] Furthermore, in each imaging device 10 (S, Y, M, C, K) where the primary transfer has been completed, the drum cleaning device 16 scrapes off any adhering matter to clean the surface of the photosensitive drum 11. This makes each imaging device 10 (S, Y, M, C, K) ready for the next image formation operation.

[0056] Next, the intermediate transfer device 20 holds the primarily transferred toner image and transports it to the secondary transfer position by the rotation of the intermediate transfer belt 21. Meanwhile, the paper feeder 50 sends out the required recording paper 5 to a paper feed path 56 in accordance with the image creation operation. In the paper feed path 56, a pair of paper transport rolls 55, which act as registration rolls, feeds and supplies the recording paper 5 to the secondary transfer position in accordance with the transfer timing.

[0057] At the secondary transfer position, the secondary transfer device 30 performs secondary transfer of the toner images on the intermediate transfer belt 21 all at once onto the recording paper 5. After the secondary transfer is completed in the intermediate transfer device 20, the belt cleaning device 26 removes and cleans the surface of the intermediate transfer belt 21 to remove any toner or other adhering matter remaining thereon after the secondary transfer.

[0058] Next, the recording paper 5 onto which the toner image has been secondarily transferred is peeled off from the intermediate transfer belt 21 and then transported to the fixing device 40 via a transport belt 57. In the fixing device 40, the recording paper 5 after the second transfer is introduced into the contact area between the rotating heating belt 41 and pressure roll 42 and passed through, thereby performing the necessary fixing process (heating and pressurizing) to fix the unfixed toner image onto the recording paper 5. Finally, the recording paper 5 after fixing is straightened by a curl straightening device 58, and is then discharged by a paper discharge roll pair 59 to a paper discharge section (not shown) installed, for example, on one side of the device main body 1a.

[0059] Furthermore, when an image is formed on both sides of the recording paper 5, the recording paper 5 with an image formed on one side is not discharged to a paper discharge section (not shown), but is transported again to the secondary transfer device 30 via a reversing transport path 64 that turns the recording paper 5 over and a double-sided transport path 68, and a toner image is transferred to the back side of the recording paper 5. The recording paper 5 with the toner image transferred to the back side is transported by a transport belt 57 to the fixing device 40, where it is subjected to a fixing process (heating and pressure), and then discharged by a paper discharge roll pair 59 to a paper discharge section (not shown) installed on the side of the image forming apparatus 1.

[0060] By the above operation, a recording sheet 5 is output on one or both sides of which an image in a special color is formed in addition to a full-color image formed by combining five color toner images.

[0061] <Driver configuration> 3 and 4 are configuration diagrams showing the main part of a drive device applied to the image forming apparatus according to the first embodiment.

[0062] 1, the drive device 70 drives the developing devices 14 of the image forming devices 10 (S, Y, M, C, K) for the special colors (S), yellow (Y), magenta (M), cyan (C), and black (K). The drive devices 70 are respectively arranged corresponding to the developing devices 14 of the image forming devices 10 (S, Y, M, C, K).

[0063] 3 and 4, the drive device 70 includes first to third support frames 71 to 73 made of sheet metal or the like and arranged at a required distance from one another. As shown in FIG. 5, an auger motor 74 is attached to the third support frame 73 as an example of a drive source that rotates and drives the supply auger 142 and admix auger 143 of the developing device 14.

[0064] Note that Figure 4 is a structural diagram of the drive device showing the state in which the developing device 14 is removed from the device main body 1a of the image forming device 1, and Figure 5 is a structural diagram of the drive device showing the state in which the developing device 14 is attached to the device main body 1a of the image forming device 1.

[0065] As shown in FIG. 6, a drive pulley 75 is fixedly attached to a drive shaft 741 of the auger motor 74. A timing belt 78 is wound around the drive pulley 75 and a driven pulley 77 attached to the drive shaft 76. As shown in FIG. 5, the drive shaft 76 is disposed at a position corresponding to the rear end of the supply auger 142 of the developing device 14 in the axial direction. As shown in FIG. 4, the base end of the drive shaft 76 in the axial direction is rotatably supported by the third support frame 73 via a bearing member 79, and the tip end of the drive shaft 76 in the axial direction is rotatably supported by a support housing 80 disposed between the first support frame 71 and the second support frame 72 via a bearing member 81.

[0066] A drive gear 82, which is an example of a gear according to the present embodiment 1, is attached to the tip of the drive shaft 76. The drive gear 82 holds in a connected state a coupling member 83 that transmits a rotational drive force to the supply auger 142 of the developing device 14 in a releasable manner, and also transmits the rotational drive force of the auger motor 74 to the admix auger 143 of the developing device 14 and the like.

[0067] 7 and 8, the drive shaft 76 is configured as a substantially cylindrical member made of metal such as stainless steel. The drive shaft 76 includes a first cylindrical portion 761 at its base end along the axial direction and rotatably supported by a bearing member 79, a first D-cut portion 762 for attaching the driven pulley 77 to the inside of the first cylindrical portion 761 along the axial direction in a non-rotational state, a second cylindrical portion 763 formed in its central portion along the axial direction and having a larger outer diameter than the first cylindrical portion 761, a third cylindrical portion 764 provided at the tip end along the axial direction of the second cylindrical portion 763 and having a smaller outer diameter than the second cylindrical portion 763 and rotatably supported by a bearing member 81, a second D-cut portion 765 formed at the tip end along the axial direction, and a fourth cylindrical portion 766 located just before a tip 765a of the second D-cut portion 765 and having an outer diameter equal to or smaller than that of the second D-cut portion 765. In this first embodiment, the outer diameter of the fourth cylindrical portion 766 is set to a value equal to the distance between the two D-cut surfaces 765 b, 765 b of the second D-cut portion 765.

[0068] The second D-cut portion 765 of the drive shaft 76 is configured as a double D-cut portion having two D-cut surfaces 765b, 765b facing each other parallel to the central axis at the axial end of the drive shaft 76. Like the second D-cut portion 765, the first D-cut portion 762 is also configured as a double D-cut portion having two D-cut surfaces 762a, 762a facing each other parallel to the central axis at the axial end of the drive shaft 76. The first and second D-cut portions 762, 765 may also be configured as D-cut portions having a single D-cut surface formed parallel to the central axis at the axial end of the drive shaft 76. However, the second D-cut portion 765 can more reliably transmit the torque of the drive shaft 76 to the drive gear 82 than a D-cut portion having only a single D-cut surface formed parallel to the central axis at the axial end of the drive shaft 76.

[0069] The second D-cut portion 765 of the drive shaft 76 has a tip 765a formed in the same shape as the cross-sectional shape of the second D-cut portion 765. In other words, the tip 765a of the second D-cut portion 765 is separated from the second D-cut portion 765 by the fourth cylindrical portion 766. As described above, the second D-cut portion 765 has a fourth cylindrical portion 766 having an outer diameter equal to or smaller than that of the second D-cut portion 765, disposed between the tip 765a and the fourth cylindrical portion 766. The length along the axial direction of the tip 765a of the second D-cut portion 765, i.e., thickness T, is arbitrary, but it is sufficient that the tip 765a has enough mechanical strength to prevent the drive gear 82 from coming off when it abuts against the drive gear 82.

[0070] As shown in FIGS. 4 and 5 , a support shaft 84 is disposed parallel to the drive shaft 76, at a position corresponding to the rear end of the admix auger 143 of the developing device 14 in the axial direction. The support shaft 84 has its axial base end supported by the second support frame 72 in a rotation-preventing manner, and its axial tip end supported by the support housing 80. A driven gear 85 is rotatably mounted on the support shaft 84 at its axial tip end, to which the drive gear 82 engages to transmit driving force. The tip end of the support shaft 84 is formed in a cylindrical shape with an outer diameter smaller than that of the center portion, and a step is provided between the tip end and the center portion against which the driven gear 85 abuts. The driven gear 85 may be fixed to the support shaft 84 by rotatably supporting the support shaft 84 on the second support frame 72 and the support housing 80. The driven gear 85 holds, in a connected state, a coupling member 86 that transmits a rotational driving force to the admix auger 143 of the developing device 14 so as to be capable of contacting and releasably engaging with the admix auger 143 .

[0071] As shown in FIGS. 9 and 10 , the drive gear 82 includes a gear body 821 formed in a short cylindrical shape along the axial direction. One side surface 821a located on the rear side along the Y direction is closed, and the other side surface 821b located on the front side along the Y direction is open except for the toothed portion 822. The drive gear 82 has a toothed portion 822 consisting of helical teeth with tooth traces oblique to the axial direction provided around the entire outer periphery of the gear body 821. Because the drive gear 82 is a helical gear, when the drive gear 82 rotates together with the drive shaft 76 and transmits driving force to the driven gear 85, a thrust force determined by the rotation direction and the inclination direction of the toothed portion 822 acts between the drive gear 82 and the driven gear 85. In the first embodiment, the drive gear 82 is configured so that, during rotation, a thrust force acts on the drive gear 82 toward the tip end of the drive shaft 76 along the axial direction, i.e., a thrust force acts in a direction in which the drive gear 82 disengages from the drive shaft 76. For this reason, as will be described later, the drive gear 82 is provided with a retaining mechanism to prevent it from coming off the drive shaft 76 during rotation. On the other hand, a thrust force acts on the driven gear 85 in the opposite direction (retaining direction) from the tip end along the axial direction of the support shaft 84 as a reaction force due to the engagement with the drive gear 82. The drive gear 82 and driven gear 85 are integrally formed by injection molding or the like using synthetic resin.

[0072] Drive gear 82 is provided with an insertion portion 824 as an example of a cylindrical retaining portion at the center along the axial direction, having an insertion hole 823 for mounting drive gear 82 so as to receive driving force from drive shaft 76 while allowing circumferential movement relative to drive shaft 76 along the axial direction at the center of gear body 821. Insertion hole 823 has an inner diameter that corresponds to the outer diameter of second D-cut portion 765 of drive shaft 76 so that second D-cut portion 765 can be inserted therein.

[0073] As shown in FIGS. 9 and 10 , the drive gear 82 is provided with a protrusion 825 on the inner circumferential surface of the insertion hole 823. The protrusion 825 is an example of a permissive portion that allows circumferential movement with respect to the drive shaft 76 and receives drive torque from the drive shaft 76. As shown in FIG. 11 , the protrusion 825 is formed in a mountain shape that is a substantially isosceles triangle in cross section, with both side surfaces 825a, 825a formed so that the apex angle is an angle θ that is less than 180 degrees. The protrusions 825 are provided at positions 180 degrees apart on the inner circumferential surface of the insertion hole 823. When the second D-cut portion 765 of the drive shaft 76 is inserted, the protrusion 825 transmits drive torque while allowing circumferential movement with respect to the drive shaft 76 (rotation through a limited angle) when the second D-cut portion 765 abuts against the protrusion 825, as compared to when the apex is formed flat at an angle of 180 degrees rather than a mountain shape.

[0074] 9 and 10 , the insertion portion 824 of the drive gear 82 has abutment walls 827, 827 formed at its axial end to close the insertion hole 823, leaving an opening 826 as an example of a retaining portion formed in the same cross-sectional shape as the tip 765a of the drive shaft 76. The thickness of the abutment wall 827 is set to be smaller than the length of the fourth cylindrical portion 766 of the drive shaft 76. The abutment wall 827 is provided at the axial end of the insertion portion 824, and the position of the abutment wall 827 is such that, when the drive shaft 76 is inserted into the insertion hole 823 of the drive gear 82, the side surface 765c of the second D-cut portion 765 abuts against the axial end surface of the protrusion 825 of the drive gear 82, and the position of the abutment wall 827 corresponds to the fourth cylindrical portion 766 of the drive shaft 76, as shown in FIG. In other words, when the drive gear 82 is attached to the drive shaft 76, the opening 826 allows the second D-cut portion 765 of the drive shaft 76 to move circumferentially until it abuts against the convex portion 825 of the drive gear 82 without abutting against the inner circumference of the opening 826.

[0075] Furthermore, as shown in Figure 13, when the second D-cut portion 765 of the drive shaft 76 abuts against the convex portion 825 of the drive gear 82, the position of the tip 825a of the second D-cut portion 765 along the circumferential direction shifts, and when a thrust force toward the tip of the drive gear 82 acts on the drive shaft 76, the tip 825a of the second D-cut portion 765 abuts against the outer peripheral surface of the opening 826, preventing it from coming loose.

[0076] 9, the drive gear 82 has internal teeth 828 made of a spur gear on the inner circumferential surface of the toothed portion 822 for holding the drive gear 82 in a state of meshing with the coupling member 83. The tip end of the internal teeth 828 along the axial direction is tapered to make it easier to mesh with the coupling member 83.

[0077] When assembling the drive unit 70, the drive gear 82 is attached to the drive shaft 76 by simply inserting the insertion hole 824 of the gear body 821 into the second D-cut portion 765 provided at the tip of the drive shaft 76, as shown in Figure 14.

[0078] 4, the driven gear 85 is configured similarly to the drive gear 82, except that the insertion portion of the gear body is cylindrical and does not have a retaining portion. When the driven gear 85 rotates, a thrust force acts in the opposite direction to that of the drive gear 82, and the driven gear 85 comes into contact with the side surface of the stepped portion of the support shaft 84 and stops.

[0079] The coupling members 83, 84 are configured to transmit the driving force from the drive unit 70 to the developing device 14 by engaging with the secondary coupling portions 142a, 143a provided at the axial ends of the supply auger 142 and admix auger 143 of the developing device 14, and to be able to separate and release the coupling state when the developing device 14 is removed from the device main body 1a of the image forming apparatus 1.

[0080] The coupling members 83 and 84 have the same configuration. To explain the coupling member 83, it is formed in a substantially cylindrical shape as shown in Figures 4 and 6. The coupling member has a first spur gear portion 831 formed on the outer periphery of its base end portion, which is coupled in a state of meshing with the internal gear of the drive gear 82.

[0081] In addition, the coupling member 83 has a second spur gear portion 832 formed on its outer periphery so as to mesh with a secondary coupling portion 142a provided at the end along the axial direction of the supply auger 142 of the developing device 14 at its base end.

[0082] The coupling member 83 has a tapered portion 834 whose outer diameter expands toward the base end side via an intermediate cylindrical portion 833, and an annular flange portion 835 protruding radially outward is provided at the end of the tapered portion 834.

[0083] <Operation of the drive unit> The drive device according to the first embodiment is able to generate a force that suppresses the thrust force that acts during rotation without using a retaining member, as follows.

[0084] That is, in the image forming apparatus 1 to which the drive device 70 according to this embodiment 1 is applied, as shown in FIG. 1, in the five image forming devices 10 (S, Y, M, C, K) of spot color (S), yellow (Y), magenta (M), cyan (C) and black (K), the developing devices 14 are configured to be replaceable by being detached from the apparatus main body 1a, and in particular, by replacing the developing device 14S of the spot color (S), it is possible to form an image of the desired spot color (S).

[0085] After the developing device 14 is released from the fixed state by a fixing means (not shown), it is removed from the device main body 1a by pulling it forward in the Y direction relative to the device main body 1a of the image forming apparatus 1. At this time, the secondary coupling is separated from the coupling member of the drive device, so that the transmission of driving force to the developing device 14 is cut off and the developing device 14 can be removed.

[0086] On the other hand, by attaching the developing device 14 to the device main body 1a of the image forming device 1, the secondary coupling provided at the end on the rear side of the developing device 14 is connected to the coupling member of the drive device 70, and the driving force is transmitted from the drive device 70 to the developing device 14.

[0087] As shown in FIG. 5, the drive device 70 is provided with a drive gear 82 made of a helical gear at the tip of the drive shaft 76, and a driven gear 85, also made of a helical gear, that meshes with the drive gear 82, in order to transmit the rotational driving force of the auger motor 74 to the supply auger 142 and admix auger 143 of the developing device 14, etc., to rotate them.

[0088] The drive gear 82 is attached to the tip of the drive shaft 76 and connected to the coupling member 82, so it is difficult to use a conventional anti-slip means such as an E-ring to prevent it from coming off the drive shaft 76.

[0089] 9 and 10, the drive gear 82 according to this first embodiment is provided with a protrusion 825 inside an insertion hole 823 of a gear body 821 to allow movement in the circumferential direction relative to the drive shaft 76. Furthermore, the insertion portion 824 of the drive gear 82 is provided with an opening 826 at the end along the axial direction of the insertion hole 823, into which a tip 825a of the second D-cut portion 765 of the drive shaft 76 can be inserted.

[0090] Therefore, when the rotational driving force of the auger motor 74 is transmitted and the drive shaft 76 begins to rotate, the drive gear 82 is allowed to move slightly circumferentially relative to the drive shaft 76 until the second D-cut portion 765 of the drive shaft 76 abuts against the convex portion 825 of the drive gear 82.

[0091] When the second D-cut portion 765 of the drive shaft 76 abuts against the convex portion 825 of the drive gear 82 and begins to rotate together with the drive shaft 76, a thrust force acts on the drive gear 82 due to engagement with the driven gear 85, causing the drive gear 82 to move toward the tip along the axial direction of the drive shaft 76.

[0092] As a result, as shown in Figure 13, while the drive gear 82 moves circumferentially relative to the drive shaft 76, the circumferential positional relationship between the tip 765a of the second D-cut portion 765 of the drive shaft 76 and the opening 826 of the drive gear 82 shifts, and when a thrust force acts and the drive gear 82 attempts to move toward the tip along the axial direction, the outer periphery of the opening 826 of the drive gear 82 abuts against the tip 765a of the second D-cut portion 765, preventing it from coming loose.

[0093] Therefore, the drive gear 82 according to this embodiment 1 can generate a force that suppresses the thrust force acting during rotation without using a conventional anti-slip member such as an E-ring, thereby preventing the drive gear 82 from coming off the drive shaft 76.

[0094] The drive gear 82 according to this embodiment 1 only needs to have a retaining portion on the gear body 821, so it is possible to avoid using other components and making the retaining structure larger and more complex.

[0095] In the above embodiment, the image forming apparatus is described as an image forming apparatus that forms a full-color image, but it goes without saying that the image forming apparatus may also be a monochrome image forming apparatus.

[0096] Furthermore, in the above embodiment, the gear is described as being applied to a drive device for driving the supply auger of a developing device, etc., but this is not limited to this, and it goes without saying that the gear may also be used to drive other components of the developing device or image forming means other than the developing device.

[0097] Furthermore, although the present invention has been described using an electrophotographic image forming apparatus, it is not limited to electrophotographic image forming apparatuses, and can also be applied to, for example, an inkjet image forming apparatus that contacts a transported sheet of paper holding an image of an undried ink layer (an unfixed ink image) and fixes the unfixed ink image onto the sheet of paper. [Explanation of symbols]

[0098] 1...Image forming device 1a...Device body 14...Developing device 142...Supply Auger 143...Admix Auger 74...Auger motor 76...Drive shaft 82...Drive gear 821...Gear body 823...Through hole 824...Passage part 825...Convex part 826...Opening

Claims

1. A drive shaft, Gears and Equipped with The gear is a gear body having teeth that are oblique to the axial direction and that is attached to an end of the drive shaft along the axial direction; a retaining portion provided on the gear body to allow movement in a circumferential direction relative to the drive shaft, the retaining portion moving in the circumferential direction to come into contact with a part of the drive shaft and prevent movement in an axial direction; and the retaining portion is an opening through which a double D-cut portion having two D-cut surfaces can be inserted, the double D-cut portion being provided at the end of the drive shaft via a cylindrical portion, The gear is inserted through the opening into the double D-cut portion of the drive shaft, and by rotating the drive shaft in a circumferential direction, the opening abuts against the inner end face of the double D-cut portion of the drive shaft along the axial direction, thereby preventing it from coming loose.

2. The drive unit according to claim 1, wherein the drive shaft has a double D-cut portion formed at an end along the axial direction, and a cylindrical portion just before the tip of the double D-cut portion, the cylindrical portion having an outer diameter smaller than that of the double D-cut portion.

3. The drive unit according to claim 2 , wherein the retaining portion has an insertion hole through which the drive shaft can be inserted and which abuts against the double D-cut portion while allowing the drive shaft to move in the circumferential direction.

4. 4. The drive unit according to claim 2, wherein the double D-cut portion comprises a double D-cut portion having two D-cut surfaces facing each other parallel to the central axis at an end along the axial direction of the drive shaft.

5. The drive unit according to claim 3 , wherein the retaining portion has an opening at a base end along the insertion direction of the insertion hole, through which the tip of the drive shaft can be inserted.

6. The drive device according to claim 5 , wherein the opening is formed in the same shape as the tip of the drive shaft.

7. The gear is an insertion portion through which the drive shaft is inserted in the axial direction; a tooth portion having a tooth trace oblique to the drive shaft; a permitting portion provided in the insertion portion and permitting movement of the drive shaft in a circumferential direction while the drive shaft is inserted into the insertion portion; the retaining portion is disposed in the axial direction of the allowing portion and prevents the allowing portion from moving in the axial direction; The drive device according to any one of claims 1 to 6, comprising:

8. an image forming means for forming an image; a driving means for driving the image forming means; Equipped with 8. An image forming apparatus using the driving device according to claim 1 as the driving means.

Images