JP2009023827A - Conveying state detector and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the conveying state while reducing damages on a conveying body without restriction of arrangement. <P>SOLUTION: A paper sheet conveying state detector 1 comprises a photo interrupter 12 in which the signal is changed to ON or OFF by blocking an optical path, and a gear 22 which has a shutter part for blocking the optical path of the photo interrupter 12 and a tooth 22a as a plurality of contact parts to be brought into contact with a paper sheet to be conveyed, and is rotated based on the contact state with the paper sheet, and the tooth 22a periodically blocks the optical path according to the rotation of the gear 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a conveyance state detection apparatus used in an image forming apparatus such as a copying machine or a printer, and an image forming apparatus using the same.

  FIG. 12 shows a conventional image forming apparatus 100. The image forming apparatus 100 includes an image forming unit 110 for forming a toner image, an LSU (laser scanner unit) 120 for drawing an electrostatic latent image on a photosensitive drum in the image forming unit 110, and an image forming unit 110. A transfer belt 130 to which the toner image is transferred, an image transfer unit 140 to transfer the toner image transferred to the transfer belt 130 to a sheet, and press the sheet having the toner image transferred thereto at a predetermined temperature to fix the image. The image fixing unit 150 and the image transfer unit 140 are provided with a sheet feeding device 160 for carrying a sheet as a conveying member and a manual feed tray 170.

  In the image forming apparatus 100, the image forming unit 110 forms a color toner image by superimposing toner images of four colors (black, magenta, yellow, and cyan) on the transfer belt 130, and the image transfer unit 140 A color image can be formed by transferring to a sheet.

  Next, FIG. 13 is a configuration diagram showing the vicinity of the image transfer unit 140 and the image fixing unit 150.

  Referring to FIG. 13, the image transfer unit 140 includes a pair of rollers 141 a and 141 b, and the sheet is guided between the roller 141 a and the transfer belt 130 wound around the roller 141 b, whereby the image on the transfer belt 130. The image is pressed against the paper and the color toner image is transferred.

  At this time, since the distance between the image transfer unit 140 and the image fixing unit 150 is shorter than the vertical dimension of the sheet (the size in the direction along the conveyance direction), the distance between the leading edge of the sheet on which the color toner image has been transferred. A part of the image is inserted into a nip formed by a pair of rollers 151a and 151b constituting a part of the image fixing unit 150 while the color toner image is transferred to the downstream portion of the sheet. The roller 151b is heated by heat from the heat transfer belt 153 heated by the heater 152, and the sheet is pressed while being heated between the rollers 151a and 151b, and the color toner image is fixed on the sheet. .

  In the image forming apparatus that performs the above operation, it is important to control the sheet conveyance speed between the image transfer unit 140 and the image fixing unit 150.

  The sheet conveyance speed is determined by a conveyance speed based on the image fixing unit 150 (hereinafter referred to as a fixing speed) and a conveyance speed in the image transfer unit 140 (hereinafter referred to as a transfer speed). If the speed is further increased, the sheet is pulled between the image transfer unit 140 and the image fixing unit 150, which causes color misregistration.

  Further, when the fixing speed is slower than the transfer speed, the paper is greatly bent between the image transfer unit 140 and the image fixing unit 150, which causes a conveyance failure. In particular, this problem becomes conspicuous when the distance between the image transfer unit 140 and the image fixing unit 150 is short, which is a problem in downsizing the image forming apparatus.

  As a technique for dealing with the above problems, as shown in FIG. 14, a technique is known in which a loop detection sensor 230 is provided between an image transfer unit and an image fixing unit to detect the degree of deflection of a sheet. (Patent Document 1).

  The image forming apparatus shown in FIG. 14 is provided with a loop detection sensor 230 between the roller 221 and the transfer belt 222 constituting the image transfer unit and the rollers 210a and 210b constituting the image fixing unit. Is detected. The loop detection sensor 230 includes an actuator 230a and a photo interrupter 230b whose signal is switched ON / OFF when the optical path is blocked by the behavior of the actuator 230a. Further, the fixing speed by the rollers 210a and 210b is always set to be several percent slower than the transfer speed by the roller 221 and the transfer belt 222, thereby preventing the paper from being pulled.

  When the transport speed is within the appropriate range, the paper transported from the transfer belt 222 continues to be transported with a certain tension after the leading edge is wound around the rollers 210a and 210b. The paper in this state is shown as paper 200a. In this state, the paper 200a does not come into contact with the actuator 230a (indicated by a solid line in the figure), and thus the signal output from the photo interrupter 230b does not change.

On the other hand, when the conveyance speed deviates from the appropriate range due to a decrease in the fixing speed of the rollers 210a and 210b, the sheet conveyed from the transfer belt 222 generates deflection. The state at this time is shown as a sheet 200b. In this state, the sheet 200b swells and the surface comes into contact with the actuator 230a (indicated by a dotted line in the figure) and rotates to block the optical path of the photo interrupter 230b. The photo interrupter 230b whose optical path is blocked changes the signal from ON to OFF (or OFF to ON), and a control unit (not shown) returns the paper state to the paper 200a based on the signal change from the photo interrupter 230b. Thus, control is performed to increase the fixing speed of the rollers 210a and 210b.
JP-A-10-097154

  However, the conventional image forming apparatus shown in FIG. 14 has the following problems. That is, the loop detection sensor 230 detects the deflection of the paper by using the physical contact between the actuator 230a and the paper as described above. However, since the actuator 230a is a large structure, Risk of damage.

  Further, in the paper 200a, the surface on which the color toner image is transferred is a surface on the side in contact with the actuator 230a. However, in this configuration, the color transferred to the paper by the physical contact of the actuator 230a is actually used. There is a great risk of damaging the toner image. Therefore, in practice, it is impossible to transfer the toner image to the side corresponding to the contact surface with the actuator 230a, which limits the arrangement of the sensors in the conveyance path.

  The present invention has been made in view of such a problem, and is provided with a transport state detection device capable of detecting a transport state without being restricted in arrangement and capable of detecting a transport state while reducing damage to the transport body. An object is to provide an image forming apparatus.

In order to achieve the above object, a first aspect of the present invention is a photo interrupter in which a signal is switched ON or OFF by shielding an optical path;
A shutter unit that shields the optical path of the photo interrupter, and a rotating member that has a plurality of contact parts that can contact the transported transport body and that rotates based on a contact state with the transport body,
The shutter unit is a conveyance state detection device that periodically shields the optical path according to the rotation of the rotating member.

Further, the second aspect of the present invention includes a distance variable unit that varies a distance between the shutter unit and the optical path of the photo interrupter according to a contact pressure between the transport body and the rotating member.
The distance variable unit maintains the distance at which the shutter unit does not shield the optical path of the photo interrupter when the transport body and the rotating member are not in contact with each other or when the pressure is below a specific contact pressure. 1 is a conveyance state detection device of the present invention.

Further, in the third aspect of the present invention, the distance varying unit is configured such that when the transport body and the rotating member are in contact with each other with a contact pressure larger than the specific contact pressure, the shutter unit is configured so that the shutter of the photo interrupter is Keep the distance to block the light path,
The shutter unit is the transport state detection device according to the second aspect of the present invention, wherein the period for shielding the optical path is varied according to the magnitude of the large contact pressure.

In the fourth aspect of the present invention, the rotating member is a gear,
The contact portion is the conveyance state detection device according to the first aspect of the present invention, which is a tooth of the gear.

  The fifth aspect of the present invention is the transport state detection device according to the fourth aspect of the present invention, wherein the shutter portion is the tooth of the gear.

According to a sixth aspect of the present invention, there is provided an image forming unit that forms an image on a transported transport body;
An image fixing unit for fixing the image formed on the transport body to the transport body;
A conveyance state detection device according to any one of the first to fifth aspects of the present invention, disposed between the image forming unit and the image fixing unit;
A speed control unit that controls a conveyance speed of the conveyance body from the image forming unit to the image fixing unit based on a change in ON or OFF of a signal of the photo interrupter of the conveyance state detection device. An image forming apparatus.

  According to the present invention as described above, a transport state detection device capable of detecting the transport state of a transport body without being restricted by arrangement and reducing damage to the transport body, and an image forming apparatus using the same Can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a side view schematically showing a main part of an image forming apparatus provided with a sheet conveyance state detection device 1 as a conveyance state detection device according to Embodiment 1 of the present invention. However, the same or corresponding parts as in FIG. Further, the sheet conveyance state detection device 1 is fixed to the wall surface of the conveyance path formed by the image transfer unit 140 and the image fixing unit 150, and has a layout in which a gear 22 (described later) protrudes inside the conveyance path. .

  FIG. 2 is a perspective view showing a configuration of the sheet conveyance state detection device 1 alone. As shown in FIG. 2, the sheet conveyance state detection device 1 includes a stationary part having a main body part 10 and a transmissive photointerrupter 12 and a movable part 22 including a gear 22 having teeth 22 a that can move with respect to the stationary part. It is roughly divided into departments.

  In the fixing portion, the main body portion 10 is means for fixing the position by engaging with the inner wall of the image forming apparatus (not shown) by the locking claws 11a and 11b. The photo interrupter has a light emitting part 12a that emits light and a light receiving part 12b that receives light emitted from the light emitting part 12a, and an emission hole 12a1 through which light is emitted is shown in the drawing. An optical path is formed between the light emitting unit 12a and the light receiving unit 12b.

  Next, the movable portion includes a shaft 23 that rotates the gear 22, a bearing 24 that fixes the shaft 23 so as to be rotatable, and a stage 20 that fixes the bearing 24 and moves relative to the fixed portion. A plate-like slide member 21 a is provided on the side surface of the stage 20, and the side surface of the slide member 21 a is fitted into a groove 11 c provided in the main body portion 10, so that the movable portion is in the groove 11 c with respect to the fixed portion. It can move along the stretching direction.

  FIG. 3 is a side view schematically showing a state in which the sheet conveyance state detection device 1 is mounted in the image forming apparatus. However, the same or corresponding parts as those in FIG.

  As shown in FIG. 3, in the sheet conveyance state detection device 1, the movable portion is fixed to the surface of the first inner wall 50 by the locking claws 11 a and 11 b of the main body portion 10 being locked to the first inner wall 50. On the other hand, in the movable part, the spring 25 coupled to the bearing 24 passes through the first inner wall 50 and is fixed to the surface 51 of the second inner wall located further on the flange of the first inner wall 50. Yes.

  With such a configuration, the movable part including the gear 22 is movable along the direction of the groove 11 c according to the elastic force of the spring 25 when viewed from the first inner wall 50.

  In the configuration of FIG. 3, the shapes of the first inner wall 50 and the surface 51 of the second inner wall are perpendicular to the paper conveyance state detection device 1, but this is for explanation, and in fact, FIG. According to the shape of the conveyance path shown in FIG.

  In the above configuration, the image transfer unit 140 corresponds to the image forming unit of the present invention, and the image fixing unit 150 corresponds to the image fixing unit of the present invention. The paper conveyance state detection device 1 corresponds to the conveyance state detection device of the present invention, the photo interrupter 12 corresponds to the photo interrupter of the present invention, and the gear 22 corresponds to the gear and the rotation member of the present invention. The teeth 22a correspond to the shutter portion and the contact portion of the present invention. The stage 20 and the spring 25 correspond to the distance variable portion of the present invention.

  The operation of the conveyance state detection apparatus of the present invention having the above configuration will be described below together with the operations of the image transfer unit 140 and the image fixing unit 150 with reference to FIG.

  First, as a basic operation, when the sheet on which the color toner image on the transfer belt 130 is transferred in the image transfer unit 140 is sent out from the rollers 141a and 141b, the leading end thereof is a pair of rollers 151a and 151a in the image fixing unit 150. The color toner image is fixed on the sheet by being inserted into the nip portion 151b and heated. On the other hand, the downstream portion of the sheet is sandwiched between rollers 141a and 141b of the image transfer unit 140, and the sheet is conveyed between the image transfer unit 140 and the image fixing unit 150 with a certain tension as a whole.

  In the above basic operation, the fixing speed by the rollers 151a and 151b is always set to be several percent slower than the transfer speed by the rollers 141a and 141b, thereby preventing the paper from being pulled. The sheet conveyance path in this state is illustrated as conveyance path A.

  The state of the paper transport state detection device 1 when the paper is in the transport path A is as shown in FIG. That is, the moving part maintains a state where it is pushed forward with respect to the fixed part by the elastic force of the spring 25 fixed to the surface 51 of the second inner wall. In FIG. 1, this is in the paper transport direction A.

  At this time, the gear 22 is arranged apart from the photo interrupter 12, and the optical path of the photo interrupter 12 is always secured, and outputs a signal indicating a steady state of ON or OFF.

  Next, if the fixing speed becomes higher than the transfer speed due to a decrease in the transfer speed in the image transfer section 140 or an increase in the rotation speed of the rollers 151a and 151b in the image fixing section 150, the sheet is imaged. A tension is generated between the transfer unit 140 and the image fixing unit 150 and is pulled rightward from the conveyance path A in the drawing. The sheet conveyance path in this state is illustrated as a conveyance path B.

  When the surface of the paper in the transport path B comes into contact with the teeth 22a of the gear 22 of the paper transport state detection device 1, the gear 22 starts to rotate along the paper transport direction.

  Further, when the entire gear 22 is pressed by the pulling of the paper, the moving portion moves relative to the fixed portion against the elasticity of the spring 25.

  Here, FIGS. 4 and 5 show the state of the paper transport state detection device 1 when the paper is in the transport path B. FIG.

  4 is a perspective view for comparison with FIG. 2, and FIG. 5 is a side view for comparison with FIG.

  As shown in FIG. 4, the spring 25 contracts when the paper contacts and presses, so the moving unit moves in a direction approaching the fixed unit.

  At this time, the gear 22 is inserted between the light emitting unit 12a and the light receiving unit 12b constituting the photo interrupter 12.

  As shown in FIG. 5, the gear 22 inserted into the photo interrupter 12 rotates as the paper is conveyed, so that the teeth 22 a pass through the optical path of the photo interrupter 12. When the position of the tooth 22a overlaps the injection hole 12a1, the optical path is blocked, but the optical path is not blocked between the teeth 22a. Therefore, the teeth 22 a periodically shield the optical path of the photo interrupter 12 according to the rotation of the gear 22.

  By periodically shielding the optical path, the signal output from the photo interrupter 12 periodically changes from ON to OFF from the steady state.

  Here, FIG. 6 is a diagram illustrating a change in a signal output from the photo interrupter 12. In the figure, a period T1 indicates a time when the sheet is conveyed along the conveyance path A, and a period T2 indicates a period when the sheet is conveyed along the conveyance path B. In FIG. 6, the state where the optical path is not shielded as shown in FIGS. 2 and 3 is set to ON, and the state where the optical path is shielded is set to OFF. However, the state where the optical path is not shielded is set to OFF, The shielded state may be ON.

  When an ON / OFF switching cycle occurs in the signal from the photo interrupter 12, control is performed to move the sheet to the transport path A, assuming that the sheet is not in the proper state.

  FIG. 7 is a diagram illustrating an example of a configuration for controlling the image fixing unit 150 based on the detection signal of the photo interrupter 12. When the periodically changing signal detected from the photo interrupter 12 is received by the control unit 30, the control unit 30 performs control to reduce the rotation speed of the motor 154 that drives the roller 151a. As the motor 154 rotates, the speed of the roller 151a decreases and the fixing speed of the image fixing unit 150 decreases, so that the tension of the sheet is relaxed and sagging occurs, and the conveyance path of the sheet changes from the conveyance path B to the conveyance path. Move to side A.

  Due to the change of the conveyance path, the gear 22 of the sheet conveyance state detection device 1 starts moving away from the fixed part while keeping in contact with the sheet moving along the path, but the conveyance path of the sheet is the conveyance path A. Is moved to the extent that it coincides with, the contact between the surface of the paper and the gear 22 is released.

  When the contact is released, the driven rotation of the gear 22 stops, and the periodic fluctuation of the signal from the photo interrupter 12 also stops. FIG. 6 illustrates a case where contact between the paper and the gear 22 is released in a state where the optical path is located between the teeth 22a, and this period is indicated as T3.

  As described above, in the paper transport state detection device 1 according to the first embodiment, the gear 22 rotates when the teeth 22a come into contact with the transported paper, thereby periodically shielding the optical path of the photo interrupter 12. As a result, the presence or absence of a change in the paper conveyance state is detected. At this time, the teeth 22a of the gear 22 that contacts the paper intermittently contact the paper surface as the gear 22 is driven. Further, the area of the tip of the tooth 22a is extremely small. Therefore, the physical influence on the surface of the paper is minimal, and damage can be reduced.

  As a result, as shown in FIG. 1, even when the surface side on which the color toner image is formed and the gear 22 are brought into contact with each other, a change in the paper conveyance state is detected while suppressing the influence on the color toner image. It becomes possible to do. On the other hand, in the conventional example shown in FIG. 14, the actuator 230a keeps in contact with the conveyed paper during the detection operation. Therefore, the contact portion always forms a surface regardless of the contact surface. The damage to will increase.

  Further, the sheet conveyance state detection device 1 may be brought into contact with the side on which the color toner image of the sheet is not formed, and therefore is disposed on the wall surface on the opposite side with respect to the arrangement shown in FIG. It can also be made.

  In this case, since the abnormality of the conveyance state is detected by detecting the deflection of the sheet, the relationship between the fixing speed of the image fixing unit 150 and the transfer speed of the image transfer unit 140 is as described above. Is the opposite. That is, the fixing speed by the rollers 151a and 151b is always set to be several percent faster than the transfer speed by the rollers 141a and 141b, thereby preventing the paper from sagging. In this case, the slack of the paper accompanying the printing is detected.

  As described above, according to the sheet conveyance state detection device 1 of the present embodiment, it is possible to detect the sheet conveyance state without being restricted by the arrangement and reducing damage to the sheet or image. Become.

  In the configuration of FIG. 7, the control unit 30 corresponds to the speed control unit of the present invention, and the motor 154 is included in the image fixing unit of the present invention, but the speed control unit controls the transfer speed of the image transfer unit 140. It is good also as composition to do.

(Embodiment 2)
As a second embodiment, another operation of the paper conveyance state detection apparatus according to the first embodiment of the present invention will be described below.

  The sheet conveyance state detection apparatus 1 according to the present embodiment can also detect the degree of change in the conveyance path in addition to the detection of the occurrence of the change in the conveyance path as the sheet conveyance state.

  That is, as described in the first embodiment, when the sheet 22 in the conveyance state is in contact with the gear 22, the sheet conveyance state detection device 1 moves the moving unit together with the gear 22 toward the fixed unit. The transport path can further change from the transport path B. At this time, the gear 22 is further movable in the direction to be inserted into the photo interrupter 12, but since the teeth 22a of the gear 22 have a tapered shape, the area for shielding the optical path changes with respect to the moving direction of the gear 22. To do.

  FIGS. 8A and 8B show changes in the shielding state of the optical path by the gear 22 in the sheet conveyance state detection apparatus 1 when the conveyance path moves. FIG. 8A shows a detection state of the paper conveyance state detection device 1 in a state where the contact pressure between the gear 22 and the paper is low, and FIG. 8B shows a state where the contact pressure between the gear 22 and the paper is high. The detection state of the paper conveyance state detection apparatus 1 is shown.

  In the case of FIG. 8A, the degree of insertion of the gear 22 into the photo interrupter 12 is shallow. At this time, the teeth 22a of the gear 22 cross the optical path 12c near the tip. Since the transverse distance R1 per tooth 22a is small and the distance between the teeth 22a is larger than the transverse distance R1, the cycle of the detection signal ON / OFF of the photo interrupter 12 is as shown in FIG. Further, the cycle becomes t1 in which the ON period is long and the OFF period is short.

  In the case of FIG. 8B, the degree of insertion of the gear 22 into the photo interrupter 12 becomes deep. At this time, the teeth 22a of the gear 22 cross the optical path 12c near the root. Since the transverse distance R2 per tooth 22a is larger than the transverse distance R1, and the interval between the roots of the teeth 22a is smaller than the distance between the tips, the period of the detection signal ON / OFF of the photo interrupter 12 is As shown in FIG. 9B, the cycle becomes t2 in which the ON period is short and the OFF period is long.

  When the control unit 30 shown in FIG. 7 acquires the periods t1 and t2 from the photo interrupter 12, based on the difference in the period, the ON period length, and the OFF period length, how much the sheet conveyance path is from the initial position. Whether the motor is moving can be calculated, and feedback control can be performed based on the calculated value so that the rotation number of the motor 154 becomes an optimum value.

  As described above, according to the sheet conveyance state detection apparatus 1 of the present embodiment, a change in the sheet conveyance state can be quantitatively detected by using only one apparatus, and the conveyance speed of the image forming apparatus is detected. It is possible to perform feedback control based on the above.

  In each of the above-described embodiments, the paper transport state detection device 1 uses the gear 22 having the tapered teeth 22a as shown in FIG. 10A, but the teeth 22a of the present invention are used. The gear 22 corresponds to the contact portion, and corresponds to the rotating member of the present invention.

  By using the gear 22 as the rotating member, the sheet conveyance state detection device 1 in the image forming apparatus can be used as a regulating device that regulates the sheet conveyance direction.

  In this case, the teeth 22a of the gear 22 are in continuous contact with the paper to be conveyed, so that the gear 22 is always rotated. However, as a regulating device, the paper and the gear 22 are in contact with each other with an appropriate pressure. The pressure of the spring 25 is adjusted so that the teeth 22a do not block the optical path of the photo interrupter 12. In this case, while the gear 22 is in contact with the sheet with an appropriate pressure and the conveying direction is restricted, the signal from the photo interrupter 12 is not switched ON / OFF.

  On the other hand, when sagging or excessive tension occurs in the paper and the gear 22 contacts the paper with a pressure higher than the appropriate pressure, the gear 22 moves toward the fixed portion, and the teeth 22a shield the optical path of the photo interrupter. As a result, ON / OFF switching occurs in the signal from the photo interrupter 12, so that a change in the transport state can be detected.

  Further, when the paper and the gear 22 are brought into contact with each other with an appropriate pressure as a regulating device, the teeth 22a shield the optical path of the photo interrupter 12, and the signal from the photo interrupter 12 generated at this time is transmitted. The ON / OFF switching cycle may be stored as an appropriate cycle.

  In this case, when a slack or excessive tension is generated on the paper and the gear 22 contacts the paper with a pressure higher than the appropriate pressure, the gear 22 moves closer to or away from the fixed portion. 9A and 9B, the ON / OFF switching cycle of the signal from the photo interrupter 12 changes from the appropriate cycle. By detecting this change, a change in the transport state can be detected.

  In addition to the above, the paper transport state detection device 1 can be used as a detection means for detecting the paper passage timing using an ON / OFF signal generated only when the paper passes.

  Note that the configuration of the contact portion and the rotating member in the paper conveyance state detection device of the present invention is not limited to the gear and its teeth. FIG. 10B shows an example in which a rectangular projection 41 is used as a configuration corresponding to the contact portion of the present invention, and a disk 40 provided with projections 41 on the edge at regular intervals is used as a configuration corresponding to a rotating member. FIG. The number of the protrusions 41 may be an arbitrary number as long as the disk 40 can be driven and rotated in contact with the conveyed paper. In the case of this configuration, since the projection 41 is rectangular, the shielding period of the optical path of the photo interrupter 12 does not change according to the movement of the disk 40, but the presence or absence of a change in the paper conveyance state is detected as in the first embodiment. be able to.

  FIG. 10C is a diagram showing an example in which a contact finger 42 extending directly from the rotation shaft 43 is used as a configuration corresponding to the contact portion of the present invention, and a rotary member 45 provided with the contact fingers 42 radially is used. It is. The rotating member can be reduced in weight, and the physical load applied to the paper can be further reduced.

  In each of the above embodiments, the tapered teeth 22a of the gear 22 correspond to the shutter portion of the present invention that is also used as the contact portion of the present invention. Another configuration may be used.

  Fig.11 (a) is a figure which shows the structure which used the gearwheel 60 which provided the tooth | gear 61 and the rectangular slit 62 opened radially as the rotating member of this invention. The teeth 61 are the contact portions of the present invention, while the shutter portion is realized by a part of the gear 60 that is separated from the teeth 61 by the slit 62 on the inner peripheral side. The optical path of the photo interrupter 12 is configured to pass through the slit 62 when the conveyance state is detected. In the case of the configuration shown in FIG. 11A, the number of slits 62 can be adjusted independently of the number of teeth of the gear 60, so that the ON / OFF cycle of the signal generated by the photo interrupter 12 can be adjusted. It is possible to generate a signal in accordance with the detection accuracy of the light receiving unit 12b of the interrupter.

  FIG. 11B is a diagram showing an example in which a triangular slit 72 is opened in the disk 40 of FIG. The disc 40 shown in FIG. 10B does not change the shielding period of the optical path of the photointerrupter 12 according to the movement thereof, but the shape of the slit 72 of the disc 70 changes along the radial direction. In the optical path crossing, the shielding period changes in accordance with the change in the position of the disk 70, and the same effect as described in the second embodiment can be obtained.

  In addition, in the image forming apparatus shown in FIG. 12, an image forming apparatus including the conveyance state detection device of the present invention between the image transfer unit 140 and the image fixing unit 150 is also included in the present invention. However, the conveyance state detection device of the present invention is not limited to the image transfer unit 140 and the image fixing unit 150, and is a place where it is necessary to detect the conveyance state of the paper, such as between the paper feeding device 160 and the image transfer unit 140. If so, it may be provided at an arbitrary location.

  Further, the conveyance state detection apparatus of the present invention may be used for a monochrome image forming apparatus in addition to a color image forming apparatus.

  In the above description, the paper used by the image forming apparatus has been described as an example of the transport body of the present invention. However, the transport body of the present invention is an image if it is used for detecting a slack or a pulled state or other transport state. The sheet is not limited to the paper used in the forming apparatus, and may be used for manufacturing a film such as a loom, a paper making apparatus, or a resin, in addition to the image forming apparatus, using a woven fabric, a film, or the like as a carrier.

  The present invention has an effect of being able to detect a conveyance state without being restricted by the arrangement and preventing damage to the conveyance body, and is useful in a conveyance state detection device and an image forming apparatus using the same.

1 is a side view schematically showing a main part of an image forming apparatus including a paper state detection device 1 according to a first embodiment of the present invention. It is a perspective view which shows the structure of the paper conveyance state detection apparatus 1 single-piece | unit of Embodiment 1 of this invention. FIG. 2 is a side view schematically showing a state in which the sheet conveyance state detection device 1 according to the first embodiment of the present invention is mounted in the image forming apparatus. It is a perspective view for demonstrating operation | movement of the paper conveyance state detection apparatus 1 of Embodiment 1 of this invention. It is a side view for demonstrating operation | movement of the paper conveyance state detection apparatus 1 of Embodiment 1 of this invention. It is a figure which shows the change of the signal which the photo interrupter 12 outputs. 3 is a diagram illustrating an example of a configuration for controlling an image fixing unit 150 based on a detection signal of a photo interrupter 12 in an image forming apparatus. FIG. (A) It is a figure which shows the shielding state of the optical path by the gearwheel 22 in the paper conveyance state detection apparatus 1 when a conveyance path | route moves. FIG. 5B is a diagram illustrating a light path shielding state by a gear 22 in the paper transport state detection apparatus 1 when the transport path moves. (A) It is a figure which shows the period of the detection signal of the photo interrupter 12 in the paper conveyance state detection apparatus 1 when a conveyance path | route moves. (B) It is a figure which shows the period of the detection signal of the photo interrupter 12 in the paper conveyance state detection apparatus 1 when a conveyance path | route moves. (A) It is a figure which shows an example of the rotation member of this invention. (B) It is a figure which shows an example of the rotation member of this invention. (C) It is a figure which shows an example of the rotation member of this invention. (A) It is a figure which shows an example of the rotation member of this invention. (B) It is a figure which shows an example of the rotation member of this invention. It is a figure which shows the structure of the image forming apparatus 100 by a prior art. It is a side view which shows typically the principal part of the image forming apparatus by a prior art. It is a side view which shows typically the principal part of the image forming apparatus using the loop detection sensor 230 by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper conveyance state detection apparatus 10 Main-body part 11a, 11b Locking claw 11c Groove 12 Photo interrupter 12a Light emission part 12a1 Injection hole 12b Light reception part 12c Optical path 20 Stage 21a Slide member 22 Gear 22a Tooth 23 Shaft 24 Bearing 25 Spring 100 Image forming apparatus 140 Image transfer unit 150 Image fixing unit

Claims (6)

A photo interrupter whose signal is switched ON or OFF by shielding the optical path;
A shutter unit that shields the optical path of the photo interrupter, and a rotating member that has a plurality of contact parts that can contact the transported transport body and that rotates based on a contact state with the transport body,
The said shutter part is a conveyance state detection apparatus which shields the said optical path periodically according to the said rotation of the said rotation member. In accordance with the contact pressure between the transport body and the rotating member, a distance variable unit that varies the distance between the shutter unit and the optical path of the photo interrupter,
The distance variable unit maintains the distance at which the shutter unit does not block the optical path of the photo interrupter when the carrier and the rotating member are not in contact with each other or when the distance is not more than a specific contact pressure. Item 2. The conveyance state detection device according to Item 1. The distance variable unit maintains the distance at which the shutter unit shields the optical path of the photo interrupter when the carrier and the rotating member are in contact with each other at a contact pressure larger than the specific contact pressure.
The conveyance state detection device according to claim 2, wherein the shutter unit varies a period of shielding the optical path in accordance with the magnitude of the large contact pressure. The rotating member is a gear;
The conveyance state detection device according to claim 1, wherein the contact portion is a tooth of the gear.   The conveyance state detection device according to claim 4, wherein the shutter portion is the tooth of the gear. An image forming unit that forms an image on the transported transport body;
An image fixing unit for fixing the image formed on the transport body to the transport body;
The conveyance state detection device according to claim 1, which is disposed between the image forming unit and the image fixing unit,
A speed control unit that controls a conveyance speed of the conveyance body from the image forming unit to the image fixing unit based on a change in ON or OFF of a signal of the photo interrupter of the conveyance state detection device. , Image forming apparatus.

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