Image-forming device

Abstract

To provide an image-forming device capable of withstanding a temporary increase in a load by a low-load motor.SOLUTION: An image-forming device 10 comprises: a K development unit 59; color development units 41, 47, and 53; a first motor; a first transmission section for transmitting turning force from the first motor to the K development unit 59 and a drive roller; a second motor; a second transmission section 22 for transmitting turning force from the second motor to the color development units 41, 47, and 53; a transmission mechanism for transmitting the turning force of the first motor from the first transmission section to the second transmission section; and a control section for controlling the first motor and the second motor. The transmission mechanism includes first and second assist gears for connecting the first transmission section and the second transmission section, and a torque limiter for transmitting turning force from the first transmission section to the second transmission section when a difference in rotary torque between the second transmission section and the first transmission section is equal to or more than a predetermined value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] Conventionally, an image forming apparatus in which a single motor drives multiple developing rollers is disclosed, for example, in Japanese Patent Laid-Open Publication No. 2007-65632 (Patent Document 1). According to this publication, a first motor drives photosensitive drums for colors Y (yellow), M (magenta), and C (cyan), and a second motor drives a K (black) photosensitive drum, a K developing roller, and developing rollers other than K.

[0003] Fig. 9 is a perspective view showing the positional relationship between a drive motor gear and drive gears for photoconductors, etc., in a conventional image forming apparatus in which a single motor drives multiple developing rollers. Referring to Fig. 9, a color drive motor gear 181, driven by a color drive motor (not shown), drives a Y photoconductor drive gear 183, an M photoconductor drive gear 185, a C photoconductor drive gear 187, a Y developing unit drive gear 189, an M developing unit drive gear 191, and a C developing unit drive gear 193. Meanwhile, a K drive motor gear 195, driven by a K drive motor (not shown), drives a K photoconductor drive gear 197 and a K developing unit drive gear 199. The photoconductors and developing units rotate in the directions indicated by the arrows in the figure.

[0004] The Y photoconductor drive gear 183, M photoconductor drive gear 185, C photoconductor drive gear 187, and K photoconductor drive gear 197 have gears provided on the outer periphery of the tip of the shaft, while the Y developing unit drive gear 189, M developing unit drive gear 191, C developing unit drive gear 193, and K developing unit drive gear 199 have gears provided on the inner periphery of the shaft.

[0005] As described above, conventionally, the Y, M, and C photosensitive elements are driven by one color drive motor, and the K photosensitive element having a developing roller and the belt drive roller that drives the intermediate transfer belt are driven by one K drive motor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-65632 Summary of the Invention [Problem to be solved by the invention]

[0007] Conventionally, multiple developing rollers, each with its own stirring screw, were driven by a single motor, which meant that a motor with a large output had to be selected to be able to drive the rollers sufficiently even when the fluidity of the developer deteriorated in a high-humidity environment (when the starting torque jumped to about 1.5 times the normal torque).

[0008] As a result, they had no choice but to select a motor with a higher wattage so that it could withstand the temporary high load that occurs when the developer aggregates.

[0009] Next, the problems of the conventional system will be explained in detail. Table 1 shows the units driven by the color drive motor and the monochrome K drive motor, and the reduction ratios for each unit. Table 2 shows the loads on the motors that drive the K photoconductor and color (hereinafter sometimes abbreviated as "CL") photoconductors in the conventional drive system during normal operation (when the developer has good fluidity), and Table 3 shows the loads on the motors that drive the K photoconductor and color photoconductors in the conventional drive system during development aggregation (when the developer has high humidity), and the operating conditions of each element during image formation.

[0010] [Table 1]

[0011] [Table 2]

[0012] Referring to the shaft load item in Table 2, the motor shaft load during normal operation is 67.5 mNm in the case of K (DM_K in Table 2) and 91.8 mNm in the case of CL (DM_CL in Table 2).

[0013] Therefore, if this is driven by a 30W motor, the efficiency is 54% for K and 73% for CL, as shown in Table 2. If this is driven by a 30W motor, the efficiency is 34% for K and 46% for CL.

[0014] The motor can be used at 80% or less of its rated capacity, so there is no problem under normal circumstances.

[0015] [Table 3]

[0016] Referring to the item on the shaft load in Table 3, the load on the motor shaft during development and aggregation is 65.3 mNm for K and 119.2 mNm for CL.

[0017] Therefore, when this is driven by a 30W motor, the efficiency is 52% for K and 95% for CL, as shown in Table 3. When this is driven by a 40W motor, the efficiency is 33% for K and 60% for CL. Since the motor cannot be used unless it is at 80% or less of its rated power, a 30W motor will cause problems during developer aggregation.

[0018] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an image forming apparatus that can withstand a temporary increase in load even when using a motor with a low load. [Means for solving the problem]

[0019] The image forming apparatus according to the present disclosure includes a first image forming unit including one image carrier, a second image forming unit having multiple image carriers, an intermediate transfer belt onto which toner images formed on the image carriers of the first image forming unit and the second image forming unit are transferred and which is moved by a drive roller, a first drive source, a first transmission unit that transmits a rotational force from the first drive source to the first image forming unit and the drive roller, a second drive source, a second transmission unit that transmits the rotational force from the second drive source to the second image forming unit, a transmission mechanism that transmits the rotational force of the first drive source from the first transmission unit to the second transmission unit, and a control unit that controls the first drive source and the second drive source. The transmission mechanism includes an assist gear arranged to connect the first transmission unit and the second transmission unit, and a torque limiter that transmits the rotational force from the first transmission unit to the second transmission unit when a difference in rotational torque between the second transmission unit and the first transmission unit is equal to or greater than a predetermined value.

[0020] Preferably, the control unit has a current detection unit that detects the current value when the second drive source is being driven and controlled, and performs a first control in which, when the detection value of the current detection unit is greater than a predetermined threshold, the drive speed of the first drive source is rotated faster than a predetermined speed, and when the detection value falls below the threshold, the drive speed of the first drive source is controlled to return to the predetermined speed.

[0021] More preferably, the image forming apparatus includes an environmental sensor capable of detecting temperature and humidity, and the control unit includes a determination unit that determines whether to perform the first control based on the environmental conditions detected by the environmental sensor.

[0022] Each image carrier may be provided with a cleaning blade that removes any deposits adhering to the image carrier. [Effects of the Invention]

[0023] According to the present disclosure, a torque limiter is provided as an assist mechanism that transmits rotational force from the first transmission unit to the second transmission unit when the difference in rotational torque between the second transmission unit and the first transmission unit is equal to or greater than a predetermined value, thereby providing an image forming device that can withstand temporary increases in load using a low-load motor.

[0024] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view illustrating an internal configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2A] FIG. 2 is a perspective view showing the mounting state of each photosensitive member driving gear in the image forming apparatus shown in FIG. 1 and each development unit driven thereby, and is a diagram showing the configuration when the driving force is assisted from the K development unit when the color development unit is started in the first embodiment. [Figure 2B] FIG. 2B is a top view of the drive gears shown in FIG. 2A. [Figure 3A] FIG. 2 is a front view of the first assist gear and the second assist gear as viewed from their axial direction. [Figure 3B] 3B is a cross-sectional view of the portion indicated by arrow 3B-3B in FIG. 3A. [Figure 3C] FIG. 3B is a perspective view of the part shown in FIG. 3A as seen from the rear side. [Figure 3D] FIG. 3D is an exploded perspective view of the configuration shown in FIG. 3C. [Figure 4] 2B is a perspective view showing a state in which a color development unit is attached to each development unit shown in FIG. 2A. FIG. [Figure 5A] FIG. 2 is a diagram illustrating the state of an intermediate transfer belt and each photosensitive member in a basic state. [Figure 5B] FIG. 4 is a diagram showing the state of an intermediate transfer belt and each photosensitive member in a color mode. [Figure 5C] FIG. 4 is a diagram illustrating the state of an intermediate transfer belt and each photosensitive member in a monochrome mode. [Figure 6] 10 is a flowchart showing an assist operation performed by a control unit of the image forming apparatus as a color mode startup assistance in the first embodiment. [Figure 7] FIG. 2 is a block diagram showing a configuration of a control unit of the image forming apparatus. [Figure 8A]FIG. 4 is a perspective view of the second embodiment corresponding to FIG. 3C of the first embodiment. [Figure 8B] FIG. 10 is a perspective view of a relay gear that contacts a first assist gear and a K motor gear. [Figure 8C] 8C is a view of the relay gear shown in FIG. 8B as viewed from the direction of arrow 8C in FIG. 8B. [Figure 8D] FIG. 8D is a side view of the relay gear shown in FIG. 8C. [Figure 9] FIG. 10 is a perspective view showing the positional relationship between a motor drive gear and drive gears for photosensitive members and the like in a conventional image forming apparatus in which a single motor drives a plurality of developing rollers. DETAILED DESCRIPTION OF THE INVENTION

[0026] An embodiment of the present disclosure will be described in detail below with reference to the drawings. Fig. 1 is a cross-sectional view showing the internal configuration of an image forming apparatus 10 according to an embodiment of the present disclosure. Referring to Fig. 1, the image forming apparatus 10 includes an apparatus main body 111, an imaging unit 133 provided in the center of the apparatus main body 111, an original reading unit 129 provided in the upper part of the apparatus main body 111, and a paper feed conveying device 147 provided in the lower part of the apparatus main body 111 and supplying paper (not shown) to the imaging unit 133.

[0027] The image forming unit 133 includes an intermediate transfer belt 18, and a Y developing unit 41, an M developing unit 47, a C developing unit 53, and a K developing unit 59, each of which includes a photosensitive element for each of the four colors Y, M, C, and K, arranged along the intermediate transfer belt 18. In FIG. 1, the front side is the front side (F) of the image forming apparatus 10, and the back side is the rear side (R) of the image forming apparatus 10.

[0028] [First embodiment] In the present disclosure, during development aggregation, the K drive system that drives the K development unit 59, etc. is transferred to the CL drive system that drives the Y development unit 41, etc., so that the motor of the K drive system can assist in the lack of driving force of the CL drive system.

[0029] When this assist mechanism is used, the motor load is as shown in Table 4, and the motor shaft load is kept below 80% of the rated load.

[0030] [Table 4]

[0031] Next, a specific configuration of image forming apparatus 10 in the first embodiment will be described. Fig. 2A is a perspective view showing the attachment state of each photoconductor drive gear and each development unit driven thereby in image forming apparatus 10 shown in Fig. 1, and Fig. 2B is a view of each drive gear shown in Fig. 2A as seen from below (as seen from the direction indicated by arrow 2B-2B in Fig. 2A).

[0032] In the first embodiment of the present disclosure, when the CL development units (Y development unit, M development unit, and C development unit) are started up, the driving force is assisted from the K development unit.

[0033] Referring to Figures 2A and 2B, the drive units for each component in this embodiment include a first transmission unit (first image forming unit) 20 shown surrounded by a pentagon on the right side of Figure 2A, a second transmission unit 22 (second image forming unit) shown surrounded by a pentagon on the left side of Figure 2A, and a transmission mechanism 16 shown surrounded by a circle in the center of Figure 2A.

[0034] The first transmission section 20 includes a K drive motor (first motor) 12 (see FIG. 2B), a K drive motor gear 79 driven by the K drive motor 12, and a K photosensitive member drive gear 81, a K developing unit drive gear 83, and an intermediate transfer belt drive gear 91, which are driven via relay gears 80, 80a, etc. that engage with the K drive motor gear 79. The K photosensitive member drive gear 81 and the intermediate transfer belt drive gear 91 have gears provided on the outer periphery of the tip of their shafts, and the K developing unit drive gear 83 has a gear provided on the inner periphery of their shafts.

[0035] The intermediate transfer belt drive gear 91 is engaged with a drive roller 93 (see FIG. 5A, etc.) that drives the intermediate transfer belt.

[0036] The K photoconductor drive gear 81 is connected to the K photoconductor 60 (one image carrier, see FIG. 5A), which will be described later, and therefore the first transmission unit 20 including the K photoconductor constitutes the first image forming unit.

[0037] The second transmission unit 22 includes a color drive motor (second motor) 14 (see FIG. 2B), a color drive motor gear 70 driven by the color drive motor 14, and a Y photoconductor drive gear 71, an M photoconductor drive gear 72, a C photoconductor drive gear 73, a Y developing unit drive gear 75, an M developing unit drive gear 76, and a C developing unit drive gear 77, which are driven via relay gears 75a and 75b engaged with the color drive motor gear 70. A photoconductor is connected to each of the Y photoconductor drive gears 71, etc. The Y photoconductor drive gear 71, the M photoconductor drive gear 72, and the C photoconductor drive gear 73 have gears provided on the outer periphery of the tip of their shafts, and the Y developing unit drive gear 75, the M developing unit drive gear 76, and the C developing unit drive gear 77 have gears provided on the inner periphery of their shafts.

[0038] The Y photosensitive member drive gear 71, the M photosensitive member drive gear 72, and the C photosensitive member drive gear 73 that constitute the second transmission unit 22 are connected to multiple image carriers, namely the Y photosensitive member (image carrier), the M photosensitive member (image carrier), and the C photosensitive member (image carrier), which will be described later, and therefore constitute the second image forming unit.

[0039] The transmission mechanism 16 includes a first assist gear 88 and a second assist gear 89. As will be described later, the second assist gear 89 incorporates a torque limiter.

[0040] As shown in FIG. 2A, the gears that make up the first transmission part 20, the second transmission part 22, and the transmission mechanism 16 each rotate in the direction shown in the figure.

[0041] When the first motor 12 (see FIG. 2) rotates quickly, the driving force is transmitted to the second transmission section 22 by the action of a torque limiter, which will be described later, and is then transmitted to the collar drive system.

[0042] Next, a specific configuration of the transmission mechanism 16 shown in Figures 2A and 2B will be described. Figures 3A to 3D are views showing the configuration near the first assist gear 88 and the second assist gear 89 that constitute the transmission mechanism 16. Figure 3A is a front view of the first assist gear 88 and the second assist gear 89 as seen in their axial direction (as seen from the direction shown in Figure 2A), and also shows the C developing unit drive gear 77 included in the second transmission part 22. Figure 3B is a cross-sectional view of the portion indicated by arrow 3B-3B in Figure 3A, Figure 3C is a perspective view of the portion shown in Figure 3A as seen from its rear side, and Figure 3D is an exploded perspective view of the configuration shown in Figure 3C.

[0043] As shown in Fig. 3B, the second assist gear 89 is composed of a second assist gear 89a inserted onto a support shaft 89c via a torque limiter, a second assist gear 89b inserted directly onto the support shaft 89c, and the support shaft 89c described above. The second assist gear 89b engages with a large-diameter relay gear 78 provided on the outer periphery of the support shaft of the C developing unit drive gear 77. As shown in Figs. 3C and 3D, the second assist gear 89a, which is provided adjacent to the second assist gear 89b in the direction of the support shaft 89c, is integral with the second assist gear 89b and has a torque limiter engagement portion 90 extending along the support shaft 89c. The annular torque limiter 32 is fitted into this torque limiter engagement portion 90, and the annular second assist gear 89a is provided on the outer periphery of the torque limiter 32.

[0044] The dimension from the center of the support shaft 89c to the outer periphery of the second assist gear 89a is approximately equal to the dimension from the center of the support shaft 89c to the outer periphery of the second assist gear 89b, and the second assist gear 89b and the second assist gear 89a are integrally formed.

[0045] The first assist gear 88 rotates while engaging with the outer periphery of a relay gear 80 (see FIG. 2A), and the relay gear 80 is engaged with a K drive motor gear 79 (see FIG. 2A). The second assist gear 89b is engaged with the color drive motor gear 70 via a C developing unit drive gear 77, a relay gear 76a, an M developing unit drive gear 76, and a relay gear 75a.

[0046] As a result, the first assist gear 88 receives rotational force from the first motor 12 and rotates. Meanwhile, the second assist gear 89b receives rotational force from the second motor 14 and rotates, and engages with the first assist gear 88 via the torque limiter 32.

[0047] When the load on the second motor 14 is heavy and the rotational speed of the first assist gear 88 is higher than the rotational speed of the second assist gear 89b, if there is a predetermined torque difference, the torque limiter 32 transmits the rotational force from the first motor 12 to the second motor 14 side, and if the torque difference becomes smaller than a predetermined value, the torque limiter 32 no longer transmits the rotational force from the first motor 12.

[0048] The reason for using torque limiter 32 here is that the torque limiter (approximately 0.5 USD) is cheaper than the motor price difference (1.7 USD). As a result, even an inexpensive motor such as a 30W motor can withstand the temporary load increase of color development units (Y development unit, M development unit, and C development unit) 41, 47, and 53.

[0049] Next, the state of attaching the color developing units 41, 47, and 53 to the first and second motors 12 and 14 shown in Figure 2B will be described. Figure 4 is a perspective view showing the state of attaching the color developing units to the developing units shown in Figure 2A. Referring to Figure 4, this shows the state immediately before the Y developing unit 41 is attached to the Y developing unit drive gear 75 (see Figure 2A) and the C developing unit 53 is attached to the C developing unit drive gear 77.

[0050] As described above, the Y developing unit drive gear 75 and the C developing unit drive gear 77 have gears mounted on the inner circumference of the shaft, and the Y developing unit 41 and the C developing unit 53 are provided with engagement portions (not shown) that engage with these gears.

[0051] 2A and their components are indicated by the dotted ovals, but only the reference numerals are used and their explanations are omitted. Furthermore, the front side (indicated by F in the figure) and the rear side (indicated by R in the figure) of the image forming apparatus 10 are also shown.

[0052] Next, an operation performed by the control unit 34 (see FIG. 7) of the image forming apparatus 10 in the first embodiment will be described. FIGS. 5A to 5C are diagrams showing a specific configuration of the image forming unit 133 of the image forming apparatus 10 shown in FIG. 1. FIG. 5A is a diagram showing the state of the intermediate transfer belt and each photoconductor in the basic state (neutral state), and shows a state in which all of the Y, M, C, and K photoconductors 42, 48, 54, and 60 of all of the Y, M, C, and K developing units 41, 47, 53, and 59 are separated from the intermediate transfer belt 18.

[0053] 5A, intermediate transfer belt 18 is driven by drive roller 93 in contact with transfer roller 68. Below intermediate transfer belt 18, in this order from left to right, there are provided Y developing unit 41, M developing unit 47, C developing unit 53, K developing unit 59, and image sensor 66. Y developing unit 41 includes a Y photoconductor (image carrier) 42, a Y developing unit 43, an exposure unit 44, a fixing unit 45, a cleaning unit (cleaning blade) 45a, and intermediate transfer roller 46.

[0054] The M developing unit 47 includes an M photoconductor (image carrier) 48, an M developing unit 49, an exposure unit 50, a fixing unit 51, a cleaning unit (cleaning blade) 51a, and an intermediate transfer roller 52. The C developing unit 53 includes a C photoconductor (image carrier) 54, a C developing unit 55, an exposure unit 56, a fixing unit 57, a cleaning unit (cleaning blade) 57a, and an intermediate transfer roller 58. The K developing unit 59 includes a K photoconductor (image carrier) 60, a K developing unit 61, an exposure unit 62, a fixing unit 63, a cleaning unit (cleaning blade) 63a, and an intermediate transfer roller 64.

[0055] Fig. 5B is a diagram showing the state of the intermediate transfer belt 18 and each photoconductor in color mode, showing a state in which all photoconductors 42, 48, 54, and 60 are in contact with the intermediate transfer belt 18, and Fig. 5C is a diagram showing the state of the intermediate transfer belt 18 and each photoconductor in monochrome mode, showing a state in which only the K photoconductor 60 is in contact with the intermediate transfer belt 18. Since the components in Figs. 5B to 5C are the same as those in Fig. 5A, the same reference numerals are used and their description will be omitted.

[0056] 6 is a flowchart showing the operation of assisting the start-up of the color mode in the first embodiment, performed by the control unit 34 (see FIG. 7) of the image forming apparatus 10 shown in FIG. 1. Referring to FIG. 6, in assisting the color mode, it is first determined whether the conditions for the assist are met (step S11; steps are omitted below). At this stage, the imaging unit 133 of the image forming apparatus 10 is in the basic state shown in FIG. 5A.

[0057] In S11, it is determined whether the following target conditions exist, and if the target conditions exist (YES in S11), the first motor 12 starts to be driven at V1 (first speed) and the second motor 14 starts to be driven at V2 (second speed) (S12), where the second speed = first speed x 1.2.

[0058] If the target condition is not met in S11 (NO in S11), the process proceeds to S16.

[0059] Next, the current I2 of the second motor 14 is checked (S13). It is determined whether the current I2 of the second motor 14 is equal to or greater than a predetermined value R (for example, R=1.7 A) (S14).

[0060] If the current I2 of the second motor 14 is equal to or greater than the predetermined value R in S14 (YES in S14), the process returns to S12. If the current I2 of the second motor 14 is less than the predetermined value R in S14 (NO in S14), the first motor 12 continues to be driven at V1 (first speed) (S15), and the intermediate transfer belt 18 is brought into contact with all of the photoconductors 42, 48, 54, and 60 (S16). This state is the state in which the image forming apparatus 10 is in the color mode, as shown in FIG. 5B.

[0061] The target conditions are determined by the environment or the time left standing, as shown in Table 5. The environment is determined by whether the temperature and humidity are H / H or not, based on the environment table below. The time left standing is determined by whether the product has been left standing for, for example, 8 hours or more.

[0062] [Table 5]

[0063] Next, the contents shown in FIG. 6 will be described. During rotation of the color photoconductors, the second motor 14 is subjected to a load equivalent to three blades in the development units of the photoconductors 42, 48, and 54, resulting in a slight torque shortage. This can cause stepping motors to lose synchronization if used as drive motors, or can prevent continuous rotation if used as DC motors. Therefore, in this embodiment, the current detection unit 36 ​​(see FIG. 7) monitors the current value I2 of the second motor 14. If the current value I2 is higher than normal, it is determined to be a high-load state. The first motor 12, which is under a smaller drive load than the second motor 14 and has sufficient torque, is rotated faster than a predetermined speed. This provides auxiliary torque to the color drive gear train (the second transmission unit described above) via the torque limiter 32, allowing the second motor 14 to start rotating at the first speed V1 (overcoming static torque and achieving stable rotation).

[0064] This assistance by the first motor 12 is necessary to exceed the static torque at the beginning of rotation. Once rotation begins, the rotational torque is lower than the static torque, so even if the speed of the second motor 14 is slowed down and the assistance is stopped, the second motor 14 alone can continue to rotate the color photosensitive members 42, 48, and 54.

[0065] The torque limiter 32 does not transmit any rotational force and spins idly when the torque difference becomes smaller than a predetermined value, so when the first motor 12 and the second motor 14 are rotating stably at the first speed V1, no rotational force is transmitted.

[0066] Next, the control unit of the image forming apparatus will be described. Fig. 7 is a block diagram showing the configuration of the control unit 34 of the image forming apparatus 10. The main components of the control unit 34 are shown enclosed in a box on the left side, and specific components of the image forming apparatus 10 connected to the main components are shown on the right side. Referring to Fig. 7, the control unit 34 includes a reception process determination unit 113, an image processing unit 115, a storage unit 117, an image formation control unit 119, a drive control unit 121, a second drive source current determination unit 123, and a separation / contact control unit 125.

[0067] The reception process determination unit 113 is connected to the communication unit 127. The image processing unit 115 is connected to the document reading unit 129. The storage unit 117 is connected to the operation unit 131. The image creation control unit 119 is connected to the image creation unit 133.

[0068] The image forming unit 133 includes a charging device 135, an exposure device 137 (exposure unit 44, exposure unit 50, exposure unit 56, exposure unit 62), a developing device 139 (Y developing unit 43, M developing unit 49, C developing unit 55, K developing unit 61), a transfer device 141 (intermediate transfer rollers 46, 52, 58, 64), a discharge device 143, a cleaning device 145 (cleaning units 45a, 51a, 57a, 63a), a paper feed conveying device 147, an environmental sensor 38, and a judgment unit 40 that judges whether to perform first control to return the driving speed of the first motor 12 to a predetermined speed based on the environmental conditions detected by the environmental sensor 38.

[0069] The drive control unit 121 is connected to the first motor 12 and the second motor 14.

[0070] The second drive source current determination unit 123 is connected to the second motor 14 and includes a current detection unit 36 ​​that detects the current of the second motor 14. The contact / separation control unit 125 includes an intermediate transfer belt contact / separation device 149. The control unit 34 is connected to a display unit 150.

[0071] Here, image processing unit 115 converts image data read by communication unit 127 or document reading unit 129 into data necessary for image formation by image creation unit 133. Image creation control unit 119 controls image creation unit 133 based on this data.

[0072] [Second embodiment] Next, a second embodiment of the present disclosure will be described. In the second embodiment, both the first motor and the second motor are always driven at V1 without making the environmental determination determined under the target conditions described in Fig. 6. At this time, as will be described later, the speed is increased by the relay gear, so that rotational force is supplied from the first motor to the drive gear train of the collar. However, when the torque difference becomes smaller than a predetermined difference due to the torque limiter, the motor will spin freely and will not transmit the rotational force.

[0073] Figures 8A to 8D are figures showing the vicinity of the first and second assist gears 88, 89 in the second embodiment, Figure 8A is an oblique view of the second embodiment corresponding to Figure 3C of the first embodiment, Figure 8B is an oblique view of the relay gear 105 that abuts the first assist gear 88 and the K drive motor gear 79, Figure 8C is a view of the relay gear 105 shown in Figure 8B as seen from the direction of arrow 8C in Figure 8B, and Figure 8D is a side view of the relay gear 105 shown in Figure 8C.

[0074] In the first embodiment, the relay gear 80 is used as the relay gear, but in the second embodiment, the relay gear has a different configuration and will be described as a relay gear 105.

[0075] 8A, the second assist gear 89 has a second assist gear 89a sandwiching the torque limiter 32 therebetween and a second assist gear 89b engaging with a relay gear 78 provided on the outer periphery of the C developing unit drive gear 77, and the second assist gear 89b engages with the first assist gear 88. The first assist gear 88 engages with a relay gear 105. Here, the relay gear 80 has two stages for increasing speed.

[0076] That is, as shown in Figures 8B to 8D, the relay gear 105 includes a relay gear 105a with 51 teeth provided on the front side of a support shaft (not shown) and a relay gear 105b with 50 teeth provided on the rear side, and the relay gear 105a engages with the first assist gear 88, and the relay gear 105b engages with the K drive motor gear 79.

[0077] Further, the relay gear 105b engages with a relay gear 106 provided on the outer periphery of the K developing unit drive gear 83, causing the K developing unit drive gear 83 to rotate.

[0078] 8A to 8D, the configuration around the torque limiter 32 in the second embodiment is basically the same as that in the first embodiment shown in Figures 3A to 3D. That is, the color drive motor gear 70 (see Figure 2A) driven by the second motor 14 (see Figure 2B) drives the C developing unit drive gear 77, and drives second assist gears 89a, 89b via the torque limiter 32. On the other hand, the K drive motor gear 79 driven by the first motor 12 (see Figure 2B) drives the first assist gear 88 and the K developing unit drive gear 83 via the relay gear 105a.

[0079] As described above, the second embodiment differs from the first embodiment only in that the relay gear 105 has two stages for speed increase. Since the other points are the same as those in the first embodiment, the same elements as in the first embodiment are given the same reference numerals and their description will be omitted.

[0080] The present disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely examples and should not be interpreted as being limited. All modifications and variations within the scope of the claims of the present disclosure are within the scope of the present disclosure. [Industrial Applicability]

[0081] According to the present disclosure, an image forming apparatus that can withstand a temporary increase in load using a low-load motor can be provided, and is therefore useful as an image forming apparatus. [Explanation of symbols]

[0082] 10 Image forming device 12K drive motor (first motor, first drive source) 14 Color drive motor (second motor, second drive source) 16 Transmission Mechanism 18 Intermediate transfer belt 20 First transmission unit (first image forming unit) 22 Second transmission unit (second image forming unit) 32 Torque limiter 34 Control Unit 36 Current detection section 38 Environmental Sensors 40 Judgment Department 41 Y developing unit 42 Y photoconductor (image bearing part) 43 Y Development Unit 44 Exposure section 45 Fixing section 45a Cleaning part (cleaning blade) 46 Intermediate transfer roller 47 M Development Unit 48 M photoconductor (image bearing part) 49 M developing section 50 Exposure section 51 Fixing section 51a Cleaning unit (cleaning blade) 52 Intermediate transfer roller 53 C Development Unit 54 C Photoconductor (image bearing part) 55 C developing section 56 Exposure section 57 Fixing section 57a Cleaning unit (cleaning blade) 58 Intermediate transfer roller 59 K Development Unit 60K photoconductor (image bearing part) 61 K Development Unit 62 Exposure section 63 Fixing section 63a Cleaning unit (cleaning blade) 64 Intermediate transfer roller 66 Image Sensor 68 Transfer roller 70 Color drive motor gear 71 Y photoconductor drive gear 72 M photoconductor drive gear 73 C Photoconductor drive gear 75 Y developing unit drive gear 76 M Development unit drive gear 77 C development unit drive gear 79 K drive motor gear 75a, 76a, 78, 80, 80a, 105, 106 Relay gear 81 K photoconductor drive gear 83 K Development unit drive gear 88 1st assist gear 89a, 89b 2nd assist gear 91 Intermediate transfer belt drive gear 93 Drive roller 111 Device body 113 Reception processing determination unit 115 Image processing section 117 Memory section 119 Imaging control unit 121 Drive control unit 123 Second drive source current determination unit 125 Connection / Disconnection Control Unit 127 Communications Department 129 Document reading unit 131 Operation section 133 Image creation section 135 Charging device 137 Exposure equipment 139 Developing device 141 Transcription device 143 Static eliminator 145 Cleaning equipment 147 Paper feeder 149 Intermediate transfer belt separation device 150 Display section

Claims

1. a first image forming unit including one image carrier; a second image forming unit having a plurality of image carriers; an intermediate transfer belt onto which the toner images formed on the image carriers of the first image forming unit and the second image forming unit are transferred and which is moved by a drive roller; a first driving source; and a first transmission unit that transmits a rotational force from the first driving source to the first image forming unit and the drive roller; a second driving source; and a second transmission unit that transmits a rotational force from the second driving source to the second image forming unit; a transmission mechanism that transmits a rotational force of the first drive source from the first transmission unit to the second transmission unit; a control unit that controls the first driving source and the second driving source, An image forming apparatus characterized in that the transmission mechanism includes an assist gear arranged to connect the first transmission unit and the second transmission unit, and a torque limiter that transmits rotational force from the first transmission unit to the second transmission unit when the difference in rotational torque between the second transmission unit and the first transmission unit is equal to or greater than a predetermined value.

2. the control unit has a current detection unit that detects a current value when driving and controlling the second drive source, When the detection value of the current detection unit is greater than a predetermined threshold value, the drive speed of the first drive source is increased to a value greater than a predetermined speed; 2. The image forming apparatus according to claim 1, wherein a first control is performed to control the drive speed of the first drive source to return to a predetermined speed when the detected value falls below the threshold value.

3. The image forming apparatus is provided with an environmental sensor capable of detecting temperature and humidity, The control unit, based on the environmental condition detected by the environmental sensor, 3. The image forming apparatus according to claim 2, further comprising a determination unit that determines whether or not the first control is to be performed.

4. 2. The image forming apparatus according to claim 1, wherein each of the image carriers is provided with a cleaning blade for removing deposits adhering to the image carrier.

Images