JP2005240957A - Driving force transmission device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force transmission device restraining generation of elastic deformation of a belt for highly accurate transmission of a driving force even if starting and stopping operations are often performed, and an image forming device therewith. <P>SOLUTION: While load is being applied using a brake device 150, a drive motor 160 is driven to apply a reverse driving force in excess of a static friction force between flat belts 101, 102 and pulleys 111 to 117, 121, 122 to the flat belts 101, 102 in the opposite direction to a circulation traveling direction, so that a protrusion 140 of each of the pulleys 111 to 117, 121, 122 releases such a tensile state as pressed against one end in a through hole 130 in each of the flat belts 101, 102. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a driving force transmission device used in an image forming apparatus such as an electrophotographic printer, a facsimile machine, and a copying machine, and an image forming apparatus provided with the driving force transmission device.

  Conventionally, a toner image is carried on an image carrier that rotates in a predetermined direction, and the toner image is finally transferred and fixed on a recording medium, thereby forming an image composed of a fixed toner image on the recording medium. An image forming apparatus is known. Among such image forming apparatuses, full-color image forming apparatuses composed of toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (K) are widely used. In such a color image forming apparatus, single color development is performed by one image carrier (photoreceptor), the obtained toner image is transferred to a transfer drum, and then the next color image is formed on the same photoreceptor. A color image forming apparatus employing a “single method” that repeats the process is known. However, an image forming apparatus employing this “single method” has a problem that it is necessary to repeat the process four times in order to obtain a full-color image, and therefore lacks productivity.

  In view of this, an image forming apparatus employing a “tandem method” that uses a plurality of photoconductors corresponding to toner colors to form a color image in synchronism with the transfer belt feed and superimpose the color on the transfer belt has been proposed. At present, image forming apparatuses adopting the “tandem method” are mainly used. In an image forming apparatus employing the “tandem method”, image formation is completed by rotating the photosensitive member once, that is, a single process is required to obtain a full color image. Although there is an advantage that the image forming speed (printing speed) is about four times that of the apparatus, the speed control of the transfer belt and the photosensitive member is required to have higher accuracy. In general, since the transfer belt and the photosensitive member are driven by gears, speed unevenness due to gear meshing and eccentricity becomes a problem. If a large number of transfer belts, photoconductors, and the like are driven by a single motor for cost reduction, the number of gears increases, and speed fluctuations due to meshing and eccentricity are superimposed. It is difficult to solve them, and a great deal of time is required for design and development.

Here, a technique based on so-called perforation belt driving is known in which a flat belt having one or a plurality of through holes (hereinafter referred to as a belt with holes) is driven by a pulley in which steel balls are embedded. This technique has the advantage of having a smooth belt drive and being more load resistant than a normal belt. However, since stress is structurally concentrated at the hole end which is one end in the through hole of the holed belt, the hole end may be broken or broken. Therefore, by changing the shape of the through-hole, increasing the number of through-holes, or overlapping two belts with holes, damage to the through-hole is prevented and durability is increased. As a result, the driven body A technique for stably transmitting a driving force to (pulley) has been proposed (see Patent Document 1).
JP 2003-90396 A

  However, in the case of the technique of overlapping the two belts with holes proposed in Patent Document 1 described above, although there is an advantage that there is little deformation even if stress is concentrated on the hole ends, the entire belt becomes thick, Familiarity with small-diameter pulleys is poor, and therefore it is difficult to introduce into small printers. Further, when the number of through holes is increased, although the effect of dispersing the stress at the hole ends is reduced, the frictional force between the belt and the pulley is reduced, and therefore the belt strength is reduced.

  Therefore, it is conceivable to improve other than the belt. For example, it is conceivable to improve durability by applying a pressing member to a belt. The perforation belt drive is driven by the action of meshing the multiple through holes provided in the belt with holes and the protrusions (steel balls) of the pulley, and the friction force acting between the belt with holes and the pulley. The damage to the belt with holes, which is the cause of the deterioration of the property, is due to the stress concentration at the hole ends when engaged with the pulley protrusions. Therefore, the frictional force is increased and the stress at the hole ends when engaged with the protrusions. By easing the concentration, it is possible to prevent the holed belt from being damaged. As a result, plastic deformation at the hole end portion of the holed belt can be prevented, and durability can be improved. Here, in order to increase the frictional force, it is conceivable to press the belt with a pressing member to increase the vertical drag. However, it is difficult to obtain sufficient durability in applications in which starting and stopping are frequently repeated. Such applications include printers installed in convenience stores and the like. Since such a printer is generally used for an unspecified number of visitors, the number of prints for each job is not so large, but the print frequency is very high. In this printer, since start and stop are frequently repeated, the hole end of the belt is destroyed (plastic deformation) due to the impact force generated at the time of start and stop, and there is a problem that sufficient durability cannot be obtained. To do. Hereinafter, the reason why the end of the hole of the belt is destroyed due to the impact force and sufficient durability cannot be obtained will be described.

  The impact force acting by starting and stopping is sufficiently smaller than the impact force due to elastic deformation of a general metal material such as stainless steel used for the belt with a hole. Therefore, an impact force that exceeds elastic deformation acts and the hole end of the belt is not destroyed (plastic deformation), but the force below the elastic limit is repeatedly applied to cause plastic deformation of the belt hole end. To do.

  In the perforation belt drive, the drive is transmitted by the friction force between the belt and the pulley, and the drive force generated by the engagement of the belt hole end and the pulley protrusion. In this case, the load is withstood by elastic deformation of the hole end portion of the belt. When a constant load is continuously applied, the amount of elastic deformation at the hole end is constant. However, it is conceivable that the elastic deformation amount of the hole end portion changes due to the following two causes.

  The first cause is due to load fluctuation. Compared to continuous printing, when printing intermittently, the load increases due to the impact force at the time of starting, and when the frictional force is exceeded, the amount of elastic deformation at the hole end of the belt becomes larger.

  The second cause is due to the displacement of the joint portion. The perforation belt is made endless by welding a strip-shaped metal belt. The perforation belt drive is driven by regularly arranged through-holes of the belt with holes and the protrusions of the pulleys. Occur. This misalignment appears as an elastic deformation of the hole end of the belt.

  In such a case, even if the belt with holes is stopped, the deformation of the hole end is not eliminated, and the elastic deformation of the hole end is increased due to the first cause by further driving in that state. In this case, the maximum deformation state is maintained. Further, when the hole end is elastically deformed due to the second cause, the deformation is accumulated and increased. When the hole end is plastically deformed due to accumulation, it is difficult to perform high-precision driving, which is a feature of perforation belt driving.

  In view of the above circumstances, the present invention provides a driving force transmission device capable of transmitting a driving force with high accuracy while suppressing the amount of elastic deformation of the belt even when starting and stopping are frequently performed. An object is to provide an image forming apparatus.

The first driving force transmission device of the present invention that achieves the above object includes an endless flat belt having a plurality of through holes arranged in a predetermined circulating movement direction, and a driving force applied to the flat belt. A plurality of pulleys in which protrusions penetrating into the through-holes of the flat belt are arranged in the rotational direction and spanned by the flat belt, including a driving pulley that gives a driving force and a driven pulley that receives a driving force from the flat belt, Driving force transmission for transmitting driving force by a first driving force caused by friction between the flat belt and the pulley and a second driving force acting between the through hole of the flat belt and the protrusion of the pulley. In the device
When the flat belt is stopped, a reverse driving force exceeding the static friction force between the flat belt and the pulley is applied to the flat belt in a direction opposite to the circulating movement direction. A tension state releasing device for releasing a tension state in which the protrusion is pressed against one end in the through hole of the flat belt is provided.

  When the flat belt is stopped, the first driving force transmission device of the present invention reversely drives the flat belt to exceed the static friction force between the flat belt and the pulley in the direction opposite to the circulating movement direction. Therefore, even if a tension state occurs when the pulley protrusion is pressed against one end of the through hole of the flat belt, the static friction force and the pulley protrusion are By overcoming the force pressed against one end in the through hole of the flat belt, the tension state can be released. Therefore, the amount of elastic deformation of the flat belt can be kept small, and the driving force can be transmitted with high accuracy.

  Here, when the tension state release device in the first driving force transmission device of the present invention releases the tension state, a brake device that applies a load to the reverse driving force to the flat belt is provided. Is preferred.

  In this way, since acceleration is applied to the drive device for applying the reverse drive force that exceeds the static friction force between the pulley and the flat belt, the time for releasing the tension state can be shortened. .

The second driving force transmission device of the present invention that achieves the above object includes an endless flat belt having a plurality of through holes arranged in a predetermined circulating movement direction, and the flat belt. A plurality of pulleys in which protrusions penetrating into the through-holes of the flat belt are arranged in the rotation direction and spanned by the flat belt, including a driving pulley that applies driving force and a driven pulley that receives driving force from the flat belt Drive that transmits a driving force by a first driving force caused by friction between the flat belt and the pulley and a second driving force that acts between the through hole of the flat belt and the protrusion of the pulley. In the force transmission device,
A tensioner that applies tension to the flat belt is provided, and the tensioner has a function of reducing tension applied to the flat belt when the flat belt is stopped.

  In the second driving force transmission device of the present invention, the tensioner that applies tension to the flat belt has a function of reducing the tension applied to the flat belt when the flat belt is stopped. The normal drag of the belt is reduced, so that the static friction force between the flat belt and the pulley is reduced. When the static frictional force is reduced, the deformation remaining at one end in the through hole of the flat belt even when stopped can be eliminated by the repulsive force at one end in the through hole.

  Here, it is preferable that the tensioner in the second driving force transmission device of the present invention is provided independently of the driven pulley.

  In this case, compared to the case where the tensioner that applies tension to the flat belt is also used as the driven pulley, the occurrence of hole jump (tooth jump) in the through hole of the flat belt can be suppressed to a small value.

Further, the first image forming apparatus of the present invention that achieves the above object carries a toner image on an image carrier that rotates in a predetermined direction, and finally the toner image is placed on a recording medium. In an image forming apparatus for forming an image consisting of a fixed toner image on the recording medium by transferring and fixing to the recording medium,
An endless flat belt having a plurality of through holes arranged in a predetermined circulating movement direction, a driving pulley for applying a driving force to the flat belt, and a driving force received from the flat belt to transmit the driving force to the image carrier And a plurality of pulleys on which the flat belt is stretched, the protrusions penetrating into the through-holes of the flat belt including the driven pulley, and a plurality of pulleys around which the flat belt is stretched. A driving force transmission device that transmits the driving force by a driving force of 1 and a second driving force acting between the through hole of the flat belt and the protrusion of the pulley;
When the flat belt is stopped, the driving force transmission device applies a reverse driving force that exceeds the static friction force between the flat belt and the pulley in a direction opposite to the circulating movement direction with respect to the flat belt. By providing, the tension | pulling state cancellation | release apparatus which cancels | releases the tension | tensile_strength state by which the projection part of the said pulley was pressed by one end in the through-hole of the said flat belt was provided.

  Since the first image forming apparatus according to the present invention includes the first driving force transmission device according to the present invention, the protrusion of the pulley is pressed against one end in the through hole of the flat belt. Even if a tension state occurs, the tension state can be released. Accordingly, the amount of elastic deformation of the flat belt can be suppressed to a small level, so that the driving force can be transmitted with high accuracy, and the density unevenness of the output image caused by the rotation unevenness can be suppressed to a low level.

A second image forming apparatus of the present invention that achieves the above object carries a toner image on an image carrier that rotates in a predetermined direction, and finally the toner image is placed on a recording medium. In an image forming apparatus for forming an image consisting of a fixed toner image on the recording medium by transferring and fixing to the recording medium,
An endless flat belt having a plurality of through holes arranged in a predetermined circulating movement direction, a driving pulley for applying a driving force to the flat belt, and a driving force received from the flat belt to transmit the driving force to the image carrier And a plurality of pulleys on which the flat belt is stretched, the protrusions penetrating into the through-holes of the flat belt including the driven pulley, and a plurality of pulleys around which the flat belt is stretched. A driving force transmission device that transmits the driving force by a driving force of 1 and a second driving force acting between the through hole of the flat belt and the protrusion of the pulley;
The driving force transmission device includes a tensioner that applies tension to the flat belt, and the tensioner has a function of reducing tension applied to the flat belt when the flat belt is stopped.

  Since the second image forming apparatus of the present invention includes the second driving force transmission device of the present invention, the static frictional force between the flat belt and the pulley is reduced, and the flat belt penetrates. The deformation that remains even if one end of the hole is stopped can be eliminated by the repulsive force of the one end in the through hole. Accordingly, the amount of elastic deformation of the flat belt can be suppressed to a small level, so that the driving force can be transmitted with high accuracy, and the density unevenness of the output image caused by the rotation unevenness can be suppressed to a low level.

  According to the driving force transmission device of the present invention, even when starting and stopping are complicated, the amount of elastic deformation of the belt can be suppressed to be small and the driving force can be transmitted with high accuracy. Further, according to the image forming apparatus, since the driving force transmission device is provided, it is possible to suppress the density unevenness of the output image caused by the rotation unevenness.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus to which the first driving force transmission device of the present invention is applied.

  With reference to FIG. 1, the configuration of a color copying machine 80 as an image forming apparatus will be described separately for an image input system, an image forming system, and a sheet conveying system.

  The image input system includes a document placement table 70 on which a document is placed, a document reading device 71 that reads a document on the document placement table 70, an image processing device 72 that processes image information read by the document reading device 71, and the like. Is provided.

  The image forming system includes image forming stations 10K, 10Y, 10M, and 10C corresponding to the colors K (black), Y (yellow), M (magenta), and C (cyan). The surfaces of the photosensitive drums 11K, 11Y, 11M, and 11C provided in the image forming stations 10K, 10Y, 10M, and 10C are based on the image data IK, IY, IM, and IC from the image processing device 72, respectively. Exposure apparatuses 13K, 13Y, 13M, and 13C for exposure, two first intermediate transfer drums 31a and 31b to which toner images formed by the image forming stations 10K, 10Y, 10M, and 10C are sequentially transferred, and one A second intermediate transfer drum 32 is provided. In addition, a drive control device 73 that performs drive control of a drive motor 160 (see FIG. 2) that drives the second intermediate transfer drum 32 is also provided.

  The image forming stations 10K, 10Y, 10M, and 10C include photosensitive drums 11K, 11Y, 11M, and 11C, and charging devices 12K, 12Y, 12M, and 12C that charge the photosensitive drums 11K, 11Y, 11M, and 11C, respectively. Developing devices 14K and 14Y for developing toner images by developing the electrostatic latent images written by the exposure devices 13K, 13Y, 13Y, and 13C on the charged photosensitive drums 11K, 11Y, 11M, and 11C with the respective color toners. , 14Y, 14C, etc. are provided.

  Note that a primary transfer portion (not shown) is provided at a portion where each of the photosensitive drums 11K, 11Y, 11M, and 11C and the first intermediate transfer drums 31a and 31b face each other, and the first intermediate transfer drums 31a and 31b. Secondary transfer portions (not shown) are respectively formed at portions facing the second intermediate transfer drum 32.

  In the sheet conveyance system, a sheet tray 40 on which recording sheets S such as paper are stacked, a pickup roll 41 that feeds the recording sheets S in the sheet tray 40 one by one, and the fed recording sheets S are positioned at predetermined positions. A resist roll 42, a tertiary transfer roll 43 for transferring an image on the second intermediate transfer drum 32 to the recording sheet S, a fixing roll 44 for fixing the image transferred on the recording sheet S, and the discharged recording sheet S are accommodated. A discharge tray 45 and the like are provided.

  Next, a copying process by the color copying machine 80 will be described.

  First, when a user places a document on the document table 70 and gives a copy instruction through a user interface (not shown), the image reading device 71 optically reads the document and converts it into an electrical signal (image data). . The image data is color-separated into black, yellow, magenta, and cyan colors by the image processing device 72, and image processing such as applying predetermined weighting coefficients to the image data IK, IY, IM, and IC of these colors is performed. After being applied, each color is sent to the exposure apparatus 13K, 13Y, 13M, 13C.

  On the other hand, each of the photosensitive drums 11K, 11Y, 11M, and 11C in each of the image forming stations 10K, 10Y, 10M, and 10C is driven in the direction of the arrow in the drawing by a driving force transmission device 100 (see FIGS. 2 and 3) described later. Driven by rotation. The surfaces of the photosensitive drums 11K, 11Y, 11M, and 11C are charged to a uniform predetermined potential by the charging devices 12K, 12Y, 12M, and 12C. Then, the exposure apparatuses 13K, 13Y, 13M, and 13C irradiate the surfaces of the photosensitive drums 11K, 11Y, 11M, and 11C with exposure light corresponding to the image data IK, IY, IM, and IC, respectively, at a predetermined timing. As a result, electrostatic latent images due to potential differences are formed on the surfaces of the photosensitive drums 11K, 11Y, 11M, and 11C. To the formed electrostatic latent image, toner is electrostatically attached by the developing devices 14K, 14Y, 14M, and 14C, and toner images TK, TY, TM, and TC of K, Y, M, and C are respectively obtained. It is formed.

  On the other hand, the first intermediate transfer drums 31a and 31b and the second intermediate transfer drum 32 are also rotationally driven in the direction of the arrow in the drawing by the driving force transmission device 100 described later, like the photosensitive drums 11K, 11Y, 11M, and 11C. . The toner images TK and TY are transferred from the photosensitive drums 11K and 11Y to the first intermediate transfer drum 31a, and the toner images TM and TC are transferred from the photosensitive drums 11M and 11C to the first intermediate transfer drum 31b. Primary transfer is electrostatically performed. At that time, the toner images TK and TY are superimposed on the surface of the first intermediate transfer drum 31a, and the toner images TM and TC are superimposed on the surface of the first intermediate transfer drum 31b.

  The toner images TK and TY superimposed on the first intermediate transfer drum 31a are transferred to the second intermediate transfer drum 32 in the secondary transfer portion, and similarly, the toner images TM and TC superimposed on the first intermediate transfer drum 31b are also converted. Secondary transfer is electrostatically performed on the second intermediate transfer drum 32. At this time, the toner images TK and TY and the toner images TM and TC are superimposed on the surface of the second intermediate transfer drum 32 to form a full-color toner image.

  As described above, while the full-color toner image is formed, in the sheet conveyance system, one recording sheet S in the sheet tray 40 is taken out by the pickup roll 41 and conveyed to the registration roll 42. Here, when the registration roll 42 starts rotating at a predetermined timing from the stopped state, the timing at which the full color toner image on the second intermediate transfer drum 32 reaches the nip portion with the tertiary transfer roll 43, and the recording sheet S By matching the timing to reach the nip portion, the full-color toner image on the second intermediate transfer drum 32 is electrostatically transferred to the recording sheet S by the tertiary transfer roll 43.

  Thereafter, when the recording sheet S carrying the full-color toner image on the surface passes through the nip portion of the fixing roll 44, the full-color toner image is fixed on the surface of the recording sheet S by the action of heat and pressure from the fixing roll 44, The paper is discharged to a discharge tray 45 outside the color copying machine 80.

  The copying process described above is set as one cycle, and this is continuously executed, so that full-color images are successively copied.

  In such a color copying machine 80, it is necessary to transmit the driving force stably and with high accuracy even when the start and stop are frequently performed. Therefore, the color copying machine 80 is provided with a driving force transmission device 100 which is an embodiment of the first driving force transmission device of the present invention shown in FIGS.

  FIG. 2 is a perspective view showing the configuration of the driving force transmission device as viewed from the back side of the color copying machine shown in FIG. 1, and FIG. 3 is a plan view showing the driving force transmission device shown in FIG.

  The driving force transmission device 100 drives each of the photosensitive drums 11K, 11Y, 11M, and 11C, the first intermediate transfer drums 31a and 31b, and the second intermediate transfer drum 32, and in a predetermined circulation movement direction. Endless flat belts 101 and 102 having a plurality of through-holes arranged and various pulleys on which the flat belts 101 and 102 are stretched are provided. Here, as the pulleys, driven pulleys 111, 11B, 11Y, 11M, 11C, first intermediate transfer drums 31a, 31b, and second intermediate transfer drums 32, which are attached to one end side of the respective rotation shafts, 112, 113, 114, driven pulleys 115, 116, and drive pulley 117 are provided. Moreover, tension pulleys 121 and 122 for tensioning the flat belts 101 and 102 are also provided. In this embodiment, the drive pulley 117 attached to the second intermediate transfer drum 32 has two-stage belt spanning surfaces on which the flat belts 101 and 102 are spanned.

  The flat belt 101 is attached to a tension pulley 121, driven pulleys 111, 112, 113, and 114 attached to the shafts of the photosensitive drums 11K, 11Y, 11M, and 11C, and the shaft of the second intermediate transfer drum 32. The drive pulley 117 is stretched over. On the other hand, the flat belt 102 includes a tension pulley 122, driven pulleys 115 and 116 attached to the shafts of the first intermediate transfer drums 31a and 31b, and a drive pulley 117 attached to the shaft of the second intermediate transfer drum 32. It is being handed over. In addition, pulley shafts (not shown) provided in the pulleys 111 to 117, 121, and 122 are respectively supported by slide bearings provided on the side surfaces of the color copying machine 80, and the pulleys 111 to 117, 121, 122 is configured to be rotatable.

  The driving force transmission device 100 is provided with a driving motor 160 that drives the second intermediate transfer drum 32. Here, it is preferable to employ a configuration in which the output from the drive motor 160 is applied to a pulley shaft having a large winding angle between the flat belts 101 and 102 and the pulleys 111 to 117, 121, and 122. Although the driving force from the driving motor 160 is set to the shaft of the intermediate transfer drum 32, the driving force from the driving motor 160 may be applied to the other pulley shaft.

  The flat belts 101 and 102 may be made of resin, but it is preferable to use a metal such as stainless steel, nickel, titanium, etc. in terms of durability, processing accuracy, etc. It is particularly preferable to use stainless steel from the viewpoints of property and mechanical strength. Similarly, a resin material can be used for each pulley, but it is preferable to use a metal such as stainless steel, aluminum, or carbon steel from the viewpoint of durability and processing accuracy. In particular, metal pulleys generally have a larger moment of inertia than resin pulleys, and therefore, the effect of damping high-frequency vibrations such as meshing vibrations, which are regarded as problematic as causing image defects in output images in image forming apparatuses. From this point of view, the pulley is preferably made of metal. Among metals, it is particularly preferable to use stainless steel from the viewpoints of price, durability, and mechanical strength.

  A cleaner (not shown) is in contact with the first intermediate transfer drums 31a and 31b, and a larger load is applied as compared with other drums. Therefore, in this embodiment, the flat belts 101 and 102 are provided with a row of through holes 130 at the same pitch along the traveling direction A (circulation movement direction referred to in the present invention), and all the pulleys 111 to 117, 121, 122 are provided with a row of protrusions 140 corresponding to the through holes 130 of the flat belts 101, 102.

  A first driving force due to friction between the flat belts 101 and 102 and the pulleys 111 to 117, 121, and 122, and a through hole 130 of the flat belts 101 and 102 and a protrusion of the pulleys 111 to 117, 121, and 122 Stable driving is realized by the second driving force acting between the first driving force 140 and the second driving force 140. For example, a circular through hole is formed as the through hole 130, while a hemispherical protrusion is formed as the protrusion 140.

  Here, the pulley 117 is a driving pulley, and the pulleys 115 and 116 are driven pulleys to which a load is applied. In the drive pulley 117 shown in FIG. 3, the arrow B direction is forward rotation, and the direction opposite to the arrow B direction is reverse rotation. Since one drive pulley 117 pulls the two driven pulleys 115 and 116 to which a load is applied, the protrusion 140 of the drive pulley 117 has the greatest burden on the through hole 130 of the flat belt 101 and 102. It becomes the part to hang. The protrusion 140 of the drive pulley 117 that is rotating forward is pressed against one end (described as a belt hole end) in the through hole 130 of the flat belt 101 or 102. Here, the flat belts 101 and 102 withstand the load exceeding the static frictional force between the flat belts 101 and 102 and the drive pulley 117 by deforming the belt hole end.

  The driving force transmission device 100 is provided with a brake device 150. Here, the brake device 150, the drive motor 160, a clutch (not shown), and the drive control device 73 (see FIG. 1) correspond to an example of the tension state release device according to the present invention. This tension state releasing device applies a reverse direction driving force exceeding the static frictional force between the flat belts 101, 102 and the driving pulley 117 in the direction opposite to the arrow A direction to the flat belts 101, 102, This is a device for releasing the tension state in which the protrusion 140 of the drive pulley 117 is pressed against the end of the belt hole.

  The brake device 150 is a device that applies a load to the driving force applied to the flat belts 101 and 102 in the reverse direction when releasing the tension state. The clutch is a one-way clutch configured not to apply a load when the flat belts 101 and 102 move in the direction of arrow A. The brake device 150 and the clutch apply a load to the flat belts 101 and 102 only when the flat belts 101 and 102 move in the direction opposite to the arrow A direction.

Here, the acceleration when the load + drive motor 160 rotates in the reverse direction> the static friction force between the flat belts 101 and 102 and all the pulleys that stretch the flat belts 101 and 102 (Equation 1)
Must be established.

  The drive control device 73 (see FIG. 1) is a device having a profile that rotates the drive motor 160 as a drive source in the reverse direction at an acceleration that satisfies the above (Equation 1).

  Here, when the driving motor 160 is rotated in the reverse direction to cause the flat belts 101 and 102 to slip from the pulleys 111 to 117, 121, and 122, the protrusions 140 of the pulleys 111 to 117, 121, and 122 become the belt hole end. It is possible to make a transition from a state in which the protrusion 140 is in contact with the part to a state where the protrusion 140 does not contact the belt hole end.

  In the color copying machine 80 of this embodiment, after the work instructed by the operator is finished, that is, after the drive pulley 117 is finished rotating in the forward direction (in the direction of arrow B shown in FIG. 3) by the drive motor 160, the reverse rotation is made. Further, the brake device 150 attached to the driven pulley 116 operates. Thereby, the deformation | transformation of the flat belts 101 and 102 is prevented. Here, even when the drive pulley 117 rotates in the reverse direction, it is important to apply a load with the brake device 150. By doing so, since acceleration is applied to the drive motor 160, a relatively large reverse direction drive force exceeding the static friction force between the drive pulley 117 and the flat belts 101 and 102 is obtained. Therefore, the elimination of the deformation of the belt hole end can be completed in a short time.

  In this embodiment, the example in which the brake device 150 is attached to the driven pulley 116 has been described. However, the present invention is not limited to this example, and the brake device 150 can be used as the driven pulley 115 or the pulleys 111, 112, 113, and 114. It may be attached. The brake device 150 does not apply a load to the flat belts 101 and 102 when the flat belts 101 and 102 move in the circulating movement direction. A load is applied only when moving in the opposite direction. For this reason, the brake device 150 is powered on only when the flat belts 101 and 102 move in the opposite direction. Note that a one-wear clutch may be attached to the brake device 150, and a load may be applied only when the flat belts 101 and 102 move in the opposite direction due to mechanical behavior.

  FIG. 4 is a diagram showing the relationship between the force applied to the through hole of the flat belt and time.

  The horizontal axis in FIG. 4 indicates time (T), and the vertical axis in FIG. 4 indicates force (F) applied to the through hole. In a steady state in which the flat belts 101 and 102 move in the circulating movement direction, a force that can be withstood by the through holes acts in addition to the static frictional force between the flat belts 101 and 102 and each pulley. The protrusions of the pulleys contact the belt hole end, causing deformation of the belt hole end.

  Here, in order to obtain a relatively large reverse driving force exceeding the static frictional force between the driving pulley 117 and the flat belts 101 and 102, a load is applied by the brake device 150 and the driving pulley is driven by the driving motor 160. Rotate 117 reverse. By doing in this way, the time which eliminates a deformation | transformation of the through-hole 130 provided in the flat belts 101 and 102 can be shortened.

  FIG. 5 is a perspective view showing a configuration of an embodiment of the second driving force transmission device of the present invention.

  In addition, the same code | symbol is attached | subjected to the same component as the driving force transmission apparatus 100 shown in FIG. 2, and duplication description is abbreviate | omitted. 5 is incorporated in a color copying machine that is an image forming apparatus. The configuration of this color copying machine is the same as that of the color copying machine 80 shown in FIG.

  The driving force transmission apparatus 200 shown in FIG. 5 includes a tensioner 210 that applies tension to the flat belts 101 and 102. The tensioner 210 is provided independently of the tension pulley 122 that is a driven pulley, and has a function of reducing the tension applied to the flat belts 101 and 102 when the flat belts 101 and 102 are stopped.

  The tensioner 210 is fixed to a casing 211, a shaft member 212 fixed to the casing 211 and fitted to the tension pulley 122, a worm gear 213 attached to the casing 211, and a support plate (not shown). A rod member 214, a spring member 215 attached to the rod member 214 and biasing the housing 211, a drive motor 216, and a rail member 217 for moving the housing 211 in the left-right direction in FIG. Is provided.

  In this tensioner 210, the casing 211 moves left and right on the rail member 217 by moving the worm gear 212 to the left and right according to the forward and reverse rotation of the drive motor 216, and accordingly, the shaft member 212 also moves to the left and right. Thus, by moving the shaft member 212 to the left and right, the tension applied to the flat belts 101 and 102 when the flat belts 101 and 102 are stopped can be reduced. By reducing the tension, the vertical drag between the flat belts 101 and 102 and the pulleys 111 to 117, 121 and 122 can be reduced, and the static frictional force can be reduced. By reducing the static frictional force, the deformation remaining at the end of the belt hole even when stopped can be eliminated by the repulsive force of the end of the belt hole.

  Here, when the tension of the flat belts 101 and 102 is lowered, if the flat belts 101 and 102 themselves have only the spring property, there is a possibility that the hole jump (tooth jump) of the through hole 130 may occur. This can be prevented by the action of the urging force by the spring member 215. Although it is not necessary to move the flat belt 102 in the direction opposite to the circulating movement direction, a higher effect can be obtained by moving it in the opposite direction. Further, the tension of the flat belts 101 and 102 reduces the static frictional force between the pulleys 111 to 117, 121 and 122 and the flat belts 101 and 102, and the repulsive force at the belt hole end where elastic strain occurs. Therefore, it is preferable to reduce the elastic strain until the tension on the loose side becomes 1 kgf or less.

  Although the tensioner 210 in the driving force transmission device 200 of the present embodiment has been described as an example provided independently of the tension pulley 122 that is a driven pulley, the tensioner according to the present invention is also used as a driven pulley. May be.

1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus to which a first driving force transmission device of the present invention is applied. FIG. 2 is a perspective view showing a configuration of a driving force transmission device as viewed from the back side of the color copying machine shown in FIG. 1. It is a top view which shows the driving force transmission apparatus shown in FIG. It is a figure which shows the relationship between the force concerning the through-hole of a flat belt, and time. It is a perspective view which shows the structure of one Embodiment of the 2nd driving force transmission apparatus of this invention.

Explanation of symbols

10K, 10Y, 10M, 10C Image forming station 11K, 11Y, 11M, 11C Photosensitive drum 12K, 12Y, 12M, 12C Charging device 13K, 13Y, 13M, 13C Exposure device 14K, 14Y, 14Y, 14C Developing device 31a, 31b First intermediate transfer drum 32 Second intermediate transfer drum 32a, 105, 106, 109, 110 Gear 40 Sheet tray 41 Pickup roll 42 Registration roll 43 Tertiary transfer roll 44 Fixing roll 45 Ejection tray 70 Document placement table 71 Document reader 72 Image Processing device 73 Drive control device 80 Color copier 100,200 Driving force transmission device 101,102 Flat belt 111,112,113,114,115,116 Driven pulley 117 Drive pulley 121,122 Tension pulley 130 Through hole 140 Projection Part 150 braking system 160,216 drive motor 210 tensioner 211 housing 212 a shaft member 213 worm gear 214 bar member 215 spring member 217 rail member

Claims (6)

A through-hole in the flat belt, comprising: an endless flat belt having a plurality of through-holes arranged in a predetermined circulating movement direction; a driving pulley that applies driving force to the flat belt; and a driven pulley that receives driving force from the flat belt And a plurality of pulleys on which the flat belt is stretched in a rotation direction, and a first driving force due to friction between the flat belt and the pulley, and a through hole of the flat belt, In the driving force transmission device that transmits the driving force by the second driving force acting between the protrusions of the pulley,
When the flat belt is stopped, a reverse driving force exceeding the static friction force between the flat belt and the pulley is applied to the flat belt in a direction opposite to the circulating movement direction. A driving force transmission device comprising: a tension state releasing device that releases a tension state in which the protrusion is pressed against one end of the through hole of the flat belt.   The driving force transmission device according to claim 1, further comprising a brake device that applies a load on the reverse driving force to the flat belt when the tension state releasing device releases the tension state. A through-hole in the flat belt, comprising: an endless flat belt having a plurality of through-holes arranged in a predetermined circulating movement direction; a driving pulley that applies driving force to the flat belt; and a driven pulley that receives driving force from the flat belt And a plurality of pulleys on which the flat belt is stretched in a rotation direction, and a first driving force due to friction between the flat belt and the pulley, and a through hole of the flat belt, In the driving force transmission device that transmits the driving force by the second driving force acting between the protrusions of the pulley,
A driving force transmission device comprising: a tensioner that applies tension to the flat belt, and the tensioner has a function of reducing tension applied to the flat belt when the flat belt is stopped.   The driving force transmission device according to claim 3, wherein the tensioner is provided independently of the driven pulley. An image forming apparatus for forming a toner image on a recording medium by supporting the toner image on an image carrier that rotates in a predetermined direction and finally transferring and fixing the toner image on the recording medium. In
An endless flat belt having a plurality of through holes arranged in a predetermined circulating movement direction, a driving pulley for applying a driving force to the flat belt, and a driving force received from the flat belt to transmit the driving force to the image carrier And a plurality of pulleys on which the flat belt is stretched, the protrusions penetrating into the through-holes of the flat belt including the driven pulley, and a plurality of pulleys around which the flat belt is stretched are provided by friction between the flat belt and the pulley. A driving force transmission device that transmits the driving force by a driving force of 1 and a second driving force acting between the through hole of the flat belt and the protrusion of the pulley;
When the flat belt is stopped, the driving force transmission device applies a reverse driving force that exceeds the static friction force between the flat belt and the pulley in a direction opposite to the circulating movement direction with respect to the flat belt. An image forming apparatus comprising: a tension state releasing device that releases a tension state in which the protruding portion of the pulley is pressed against one end in the through hole of the flat belt. An image forming apparatus for forming a toner image on a recording medium by supporting the toner image on an image carrier that rotates in a predetermined direction and finally transferring and fixing the toner image on the recording medium. In
An endless flat belt having a plurality of through holes arranged in a predetermined circulating movement direction, a driving pulley for applying a driving force to the flat belt, and a driving force received from the flat belt to transmit the driving force to the image carrier And a plurality of pulleys on which the flat belt is stretched, the protrusions penetrating into the through-holes of the flat belt including the driven pulley, and a plurality of pulleys around which the flat belt is stretched are provided by friction between the flat belt and the pulley. A driving force transmission device that transmits the driving force by a driving force of 1 and a second driving force acting between the through hole of the flat belt and the protrusion of the pulley;
The driving force transmission device includes a tensioner that applies tension to the flat belt, and the tensioner has a function of reducing tension applied to the flat belt when the flat belt is stopped. .

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