JP2019055864A - Recording medium conveying device and image forming device - Google Patents

Abstract

To provide a recording medium conveying device and an image forming device, further reduced in size and cost, compared with a case in which a sensor for detecting presence or absence of a recording medium and a sensor for detecting a rotational speed of a roll are individually provided.SOLUTION: This device includes: a conveying part 58 which is provided with a driving rotating body 50 rotationally driven at a predetermined rotational speed and a follower rotating body 52 in pressure contact with the driving rotating body 50 at a pressure contact part N to follow, and holds a recording medium 9 between the driving rotating body and the follower rotating body to convey it; an extraction part 72 which is provided to the conveying part 58 to extract the rotational speed; and a detection part 70 which irradiates a position corresponding to the pressure contact part N with light to detect presence or absence of the recording medium 9 and further irradiates the extraction part 72 with light to detect the rotational speed.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a recording medium conveyance device and an image forming apparatus.

  Patent Document 1 discloses a transport device that holds a sheet-like object as a roll and conveys the sheet-like object, and is opposed to a drive roller that sends out the sheet-like object from the roll, and the drive roller and the sheet-like object sandwiched therebetween. A driven roller disposed at a position, a rotation detector for detecting the number of rotations of the driven roller, a roll rotating unit for rewinding the sheet-like material sent out by rotating the roll, and driving of the driving roller and the roll rotating unit A control unit that controls the rotation of the roll rotation unit when receiving an instruction to rewind the sheet-like material, and determines the rotation speed of the roll rotation unit based on the rotation speed. Is determined as the conveyance amount of the sheet-like material, and after starting the rotation of the roll rotation unit, the accumulated conveyance of the sheet-like material after the start of driving grasped by the detection value of the rotation detector Once but reaching the conveying amount determined, the transport apparatus is disclosed, characterized in that to start the deceleration of the roll rotation portion. In other words, the transport device according to Patent Document 1 detects the rotation of the roll and adjusts the paper transport speed based on the result.

JP2013-158912A

  The present invention provides a recording medium conveying apparatus and an image forming apparatus that are smaller and lower in cost than the case where a sensor that detects the presence or absence of a recording medium and a sensor that detects the rotational speed of a roll are provided separately. The purpose is to provide.

  In order to achieve the above object, a recording medium conveying apparatus according to claim 1 is a driven rotating body that is rotationally driven at a predetermined rotational speed, and a driven body that is pressed against and driven by the driving rotating body at a pressure contact portion. A conveying unit that includes a rotating body and conveys a recording medium sandwiched between the driving rotating body and the driven rotating body; an extracting unit that is provided in the conveying unit and extracts the rotation speed; and the press-contacting unit And a detection unit that detects the presence or absence of the recording medium by irradiating light to a position corresponding to 1 and detects the rotation speed by irradiating the extraction unit with light.

  According to a second aspect of the present invention, in the first aspect of the present invention, the detection unit includes a reflection type sensor including a light projecting unit and a light receiving unit, and the conveyance direction of the recording medium is predetermined. A light is emitted from the light projecting unit to a position corresponding to the pressure contact portion at an angle, and the light reflected from the recording medium is received by the light receiving unit to detect the presence or absence of the recording medium.

  According to a third aspect of the present invention, in the second aspect of the present invention, the extraction portion is a meshing portion between the driven rotator and the shaft of the driven rotator.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the meshing portion is provided on a predetermined first color convex portion provided on the shaft and the driven rotating body. And a second color fitting portion different from the predetermined color having a concave portion for fitting with the convex portion, and the detection portion is different from the first color and the second color. The rotational speed is detected by using the difference in reflectance due to.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the detection unit includes a transmissive sensor including a light projecting unit and a light receiving unit, and intersects the conveyance direction of the recording medium. A projection light is emitted from the light projecting unit to a position corresponding to the pressure contact part along the light receiving part, and the light projection light is received by the light receiving unit provided on the opposite side of the light projection part with respect to the pressure contact part. Thus, the presence or absence of the recording medium is detected.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the extraction section has a gap through which the projection light passes, and the connection section between the driven rotator and the shaft of the driven rotator. The detection unit detects the rotation speed using incident or non-incidence of light to the light receiving unit by the extraction unit.

  The invention according to claim 7 is the invention according to claim 6, wherein the connecting portion is a universal joint.

  The invention according to claim 8 is the invention according to claim 5, wherein the extraction section is provided on the side opposite to the side to which the shaft of the driven rotor is connected.

  The invention according to claim 9 is the invention according to claim 8, wherein the extraction unit is arranged diagonally with the rotation center of the driven rotating body as a center and shields the projection light. One or a plurality of light-shielding part pairs and a transmission part pair that is disposed between each of the plurality of light-shielding parts and transmits the projected light, and the detection unit is configured by the extraction unit. The rotational speed is detected by using incident or non-incident light on the light receiving unit.

  The invention according to a tenth aspect is the invention according to any one of the first to ninth aspects, wherein the drive rotating body and the recording medium are not transported in the transport section. The apparatus further includes a control unit that controls the detection unit to rotate the driven rotating body and irradiate the extraction unit with light to detect the rotation speed.

  In order to achieve the above object, an image forming apparatus according to an eleventh aspect includes a forming unit that forms an image on the recording medium, and a recording medium conveyance according to any one of the first to tenth aspects. And a device.

  According to the first and eleventh aspects of the present invention, as compared with the case where the sensor for detecting the presence or absence of the recording medium and the sensor for detecting the rotational speed of the roll are provided separately, the size and cost are reduced. There is an effect that a recording medium conveying apparatus and an image forming apparatus are provided.

  According to the second aspect of the present invention, it is unnecessary to arrange the light projecting unit and the light receiving unit at positions facing the paper, as compared with the case where the presence or absence of the recording medium is detected using the transmission type sensor. It has the effect of becoming.

  According to the third aspect of the present invention, there is an effect that it is not necessary to provide a dedicated rotational speed extraction unit as compared to the case where the extraction unit is other than the meshing unit.

  According to the fourth aspect of the invention, there is an effect that the detection of the paper and the detection of the rotation speed can be combined with one reflection type sensor.

  According to the fifth aspect of the present invention, compared to the case where the presence or absence of a recording medium is detected using a reflective sensor, the effect that the projection light is irradiated from a position corresponding to the position directly above the press contact portion is achieved. Play.

  According to the sixth aspect of the present invention, there is an effect that it is not necessary to provide a dedicated rotation speed extraction unit as compared with the case where the extraction unit is other than the connection portion between the driven rotor and the shaft.

  According to the seventh aspect of the present invention, there is an effect that the passage of the projection light becomes more reliable as compared with the case of using a connecting portion other than the universal joint.

  According to the invention described in claim 8, there is an effect that the arrangement position can be determined more easily as compared with the case where the extraction unit is provided on the side to which the shaft of the driven rotor is connected.

  According to the invention described in claim 9, there is an effect that the extraction unit is configured more easily than the case where the extraction unit is configured using a unit other than the light shielding unit pair and the transmission unit pair.

  According to the tenth aspect of the present invention, there is an effect that an improvement in the accuracy of detection of the rotational speed is expected as compared with the case where the control unit is not included.

1 is a diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment. (A) is a top view which shows an example of a structure of the recording medium conveyance apparatus which concerns on 1st Embodiment, (b) is the same side view, (c) is a figure explaining conveyance of the recording medium by a recording medium conveyance apparatus It is. It is a figure which shows an example of a structure of the rotational speed extraction part of the recording-medium conveying apparatus which concerns on 1st Embodiment. FIG. 4 is a diagram illustrating a relationship between a minimum width of a recording medium and a sensor position in the recording medium conveyance device according to the first embodiment. 6 is a timing chart for explaining the operation of the recording medium carrying device according to the first embodiment. It is a figure which shows an example of a structure of the rotational speed extraction part of the recording-medium conveying apparatus which concerns on 3rd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
With reference to FIGS. 1 to 5, a recording medium conveying apparatus and an image forming apparatus according to the present embodiment will be described. FIG. 1 shows an example of the configuration of an image forming apparatus to which a recording medium conveying apparatus according to the first embodiment of the invention is applied.

  As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment forms a toner image based on image information in a housing (not shown), and uses the toner image as a sheet-like recording medium. An image forming unit 10 to which the toner image is transferred, a fixing unit 20 that fixes the toner image by passing the paper 9 on which the toner image is transferred, and a paper feeding unit 30 that conveys and supplies the paper 9 to the image forming unit 10. And are mainly equipped. A reference numeral 25 in the drawing is a control unit that comprehensively controls the operation and the like of each component of the image forming apparatus 1, and an alternate long and short dash line with arrows indicates a main conveyance path of the sheet 9.

  The image forming unit 10 is a device that forms a toner image using a known electrophotographic method and transfers the toner image onto the paper 9. More specifically, a cylindrical photosensitive member 12 (image holding member) that rotates in the direction of the arrow is provided, and charging that charges the surface (image holding surface) of the photosensitive member 12 around the photosensitive member 12 is performed. Part 13, an exposure part 14 for forming an electrostatic latent image having a potential difference by irradiating the surface of the charged photoreceptor 12 with light based on image information (data signal), and a latent image on the photoreceptor 12 A developing unit 15 that visualizes a toner image by attaching toner as a developer, a transfer unit 16 that transfers the toner image to a sheet 9 supplied from a paper feeding unit 30, and a photoconductor 12 after transfer. A cleaning unit 17 that mainly removes toner remaining on the surface and cleans it is disposed.

  As the exposure unit 14, an LED array, a semiconductor laser scanning device, or the like is used.

  The fixing unit 20 is heated inside the casing 21 to a predetermined temperature and is rotated in the direction of the arrow, and has a heating rotator 22 such as a roll shape or a belt shape, and an axial direction of the heating rotator 22. Thus, a pressure member 23 having a roll shape, a belt shape, a pad shape, or the like that is brought into contact with a predetermined pressure is provided. In the fixing by the fixing unit 20, the sheet 9 on which the unfixed toner image is transferred is introduced into and passed through the pressure contact portion formed between the heating rotator 22 and the pressure member 23, and the toner image or the like. Is carried out by heating and pressurizing.

  The sheet feeding unit 30 includes a box-shaped accommodation cassette 31 that accommodates a plurality of sheets 9 of a predetermined size to be supplied to the image forming unit 10 on a support plate (not shown) in a stacked state. It mainly includes a sending unit 4 that feeds and conveys the sheets 9 to be stored one by one. A plurality of storage cassettes 31 are provided as necessary.

  The sending unit 4 in the paper feeding unit 30 includes a sending roll 41 and a recording medium transport device 80. The sending roll 41 is also called a pick-up roll, and is a roll that sends out the paper 9 while coming into contact with the surface of the uppermost paper 9 among the bundle of papers 9 stacked in the storage cassette 31. The recording medium conveyance device 80 according to the present embodiment includes a sensor 70 and a feed roll pair 58 (a driving roll 50 and a driven roll 52). Details of the recording medium conveyance device 80 will be described later.

  The paper feeding unit 30 conveys the paper 9 from the storage cassette 31 to the transfer unit (between the photosensitive member 12 and the transfer unit 16) of the image forming unit 10 and a plurality of paper conveyance roll pairs 33, 34, and 35. It is connected to a paper conveyance path composed of guide materials or the like (not shown). The paper transport roll pair 33 is also called a registration roll pair, and is configured as a transport timing adjustment roll pair for sending out when a predetermined feed timing arrives after temporarily stopping the leading end of the paper 9 being transported. ing. The sheet conveyance path is also provided between the image forming unit 10 and the fixing unit 20 and between the fixing unit 20 and a paper discharge unit (such as a tray) 39. For example, on the paper discharge side of the fixing unit 20, a discharge roll pair 36 for discharging and transporting the fixed paper 9 to the paper discharge unit 39 is installed.

  Next, the paper feeding unit 30 including the recording medium conveyance device 80 will be described in more detail with reference to FIG. FIG. 2 shows an example of the configuration of the recording medium transport apparatus 80 according to the present embodiment. As shown in FIGS. 2A and 2B, the recording medium transport device 80 includes a feed roll pair 58 and a sensor 70.

  The driving roll 50 (also referred to as “feed roll”) and the follower roll 52 (also referred to as “retard roll”) shown in FIGS. 2A and 2B are arranged side by side on the paper conveyance path and fed to the delivery roll 41. The sheet 9 has a function of carrying the sheet 9 on each leaf. A feed roll pair 58 is configured including the drive roll 50 and the driven roll 52. Further, the sheet transport roll pair 33 is disposed on the downstream side of the sheet transport path of the feed roll pair 58. Note that each of the drive roll 50, the driven roll 52, and the feed roll pair 58 corresponds to a "drive rotary body", a "driven rotary body", and a "conveying unit" according to the present invention.

  In transporting the paper 9, the feed roll pair 58 and the paper transport roll pair 33 operate as follows. That is, when the delivery roll 41 feeds the sheet 9 from the storage cassette 31, the feed roll 58 is stopped while rotating the drive roll 50 and the driven roll 52 reversely to each other. The paper 9 is transported toward the paper transport roll pair 33.

  Then, after correcting the skew of the sheet by causing the leading end of the sheet 9 to abut against the sheet conveying roll pair 33 and generating a bending loop in the sheet 9, the sheet conveying roll pair 33 corresponds to the operation timing of the image forming unit 10. At the same time, the rotation operation is started, and the sheet 9 is nipped and conveyed toward the image forming unit 10 on the downstream side. At this time, the sheet 9 is transported while being sandwiched between both the feed roll pair 58 and the sheet transport roll pair 33. Thereafter, the feed roll pair 58 stops rotating before the rear end of the sheet 9 passes through the feed roll pair 58 in order to prevent double feeding of the paper. Further, when the rear end of the sheet 9 passes through the sheet conveying roll pair 33, the sheet conveying roll pair 33 stops rotating in preparation for skew correction of the next sheet 9.

  2A and 2B show a state in which the drive roll 50 and the driven roll 52 that are the feed roll pair 58 are in pressure contact with each other. A drive source (motor or the like) is connected to the drive roll 50 via a shaft (drive shaft) (not shown) and is configured to be rotated by the drive source. A press-contact portion N (also referred to as a “nip portion”), which is a portion where the drive roll 50 and the driven roll 52 are press-contacted, is formed at a position shown in FIG. As shown in FIG. 2C, the sheet 9 is nipped by the press contact portion N and conveyed in the direction of the sheet conveying roll pair 33.

  As shown in FIGS. 2A and 2B, the recording medium transport device 80 further includes a sensor 70. The sensor 70 according to the present embodiment is a reflection type photosensor (photoreflector) in which a light projecting unit and a light receiving unit are disposed on substantially the same plane, and the detection object is detected by reflected light from the detection object (paper 9). Presence (presence / absence), position, etc. of the are detected. Further, the sensor 70 according to the present embodiment has a function of detecting the rotation speed of the driven roll 52 in addition to the function of detecting the paper 9. The sensor 70 corresponds to a “detection unit” according to the present invention.

  The detection of the sheet 9 by the sensor 70 is performed, for example, in order to detect the passage of the leading end and the trailing end of the sheet 9 sent out by the feed roll pair 58. Further, the rotation speed of the driven roll 52 is detected by the light projection light L from the light projecting section of the sensor 70 to the rotation speed extraction section 72 (rotation speed detection pattern) provided in the driven roll 52 so as to extract the rotation speed. , And the reflected light reflected by the rotation speed extraction unit 72 is used. The rotation speed extraction unit 72 corresponds to the “extraction unit” according to the present invention. The detection of the rotational speed of the driven roll 52 according to the present embodiment is performed, for example, to detect or estimate the wear of the drive roll 50 or the driven roll 52 constituting the feed roll pair 58. As described above, in the recording medium conveyance device 80 according to the present embodiment, the detection of the presence / absence of the sheet 9 and the detection of the rotational speed of the driven roll 52 are performed by one sensor 70. Compared to the case where the sensor is provided for detection, the recording medium conveyance device and the image forming apparatus are reduced in size and cost.

  With reference to FIG. 3, the rotational speed extraction part 72 which concerns on this Embodiment is demonstrated. As shown in FIG. 3A, in the present embodiment, a rotation speed extraction unit 72 is provided in the meshing unit 56 of the driven roll 52. The meshing portion 56 is a connecting portion between the driven roll 52 and the shaft 54 that transmits the blocking force to the driven roll 52. As shown in FIG. It is comprised so that the convex part provided in the side may fit. The meshing member 74 on the driven roll 52 side includes four convex pieces B as shown in FIG. 3B (see also FIG. 2B), and the gap between the convex piece B and the convex piece B is the above. A recess is formed.

  In the present embodiment, the convex piece B is formed of a member having a relatively bright color (hereinafter, “first color”), and the shaft 54 is darker than the convex piece B (hereinafter, “second color”). It is formed with a member. That is, the meshing portion 56 is in a state where the first color convex pieces B and the second color of the convex portion of the shaft viewed between the convex pieces B and B are alternately arranged. . Therefore, the projected light L from the sensor 70 is applied to the rotating meshing portion 56 and reflected light forms a light / dark pattern due to the difference in reflectance between the first color and the second color. This pattern reflects the rotational speed of the driven roll 52. The above is the extraction principle of the rotation speed extraction unit 72 according to the present embodiment.

  In the present embodiment, the mode in which the rotational speed of the driven roll 52 is detected using the meshing portion 56 on the driven roll 52 is described as an example. However, the present invention is not limited to this, and the meshing portion on the driving roll 50 side is used. It is good also as a form which detects the rotation speed of the driven roll 52. FIG. In the present embodiment, the convex piece B is formed in a relatively bright color and the shaft 54 is formed in a relatively dark color. However, of course, the color relationship may be reversed. . Thus, in the recording medium conveyance device 80 according to the present embodiment, the rotational speed of the driven roll 52 is detected without providing a dedicated rotational speed detection pattern, so that the cost is reduced.

Next, the operation of the sensor 70 will be described in more detail. As shown in FIG. 2B, in the present embodiment, the sensor 70 is inclined from the downstream side in the conveyance direction of the sheet 9 toward the meshing portion 56 (a direction that forms a predetermined angle with respect to the sheet conveyance direction). To the position corresponding to the press contact portion N, the projection light L is disposed at a position where it is irradiated. In other words, while the sheet 9 is not being conveyed, the light projection light L is applied to the meshing portion 56, and the reflected light is incident on the light receiving portion of the sensor 70 along the optical path of the light projection light L. The reflected light incident on the light receiving unit is converted into an electrical signal including a pulse corresponding to the brightness of the meshing unit 56. Thereby, the rotational speed of the feed roll pair 58 is detected. As shown in FIG. 2B, in the present embodiment, the meshing member 74 has four convex pieces B. Therefore, when the driven roll 52 makes one rotation, four pulses are generated. Here, in the present embodiment, a description will be given by exemplifying a mode in which the light projection light L from the light projecting unit is irradiated obliquely from the upper side. In the present invention, the “position corresponding to the pressure contact portion N” refers to a position on the pressure contact portion N or a position in the vicinity thereof, or a position on a straight line obtained by extending the linear pressure contact portion N or a position in the vicinity thereof. .

  By the way, as described above, the recording medium conveyance device 80 according to the present embodiment detects the rotational speed of the driven roll 52 and indirectly wears the feed roll pair 58 (the driving roll 50 and the driven roll 52). Uneven wear may be detected. That is, when the entire roll surface of the feed roll pair 58 is worn, the rotational speed of the driven roll 52 is increased, so that the interval between pulses is reduced as a whole. Further, when wear occurs on a part of one of the roll surfaces of the pair of feed rolls 58, the rotation speed is not uniform, so the pulse width changes. Based on this principle, the form and degree of wear of the feed roll pair 58 are grasped from the detection result of the rotational speed of the driven roll 52. In the present embodiment, the configuration in which four pulses are generated by one rotation of the roll can be said to be relatively low in terms of resolution, but it can be said to be sufficient for detecting changes in partial speed due to uneven wear of the driving roll 50 or the driven roll 52. . Further, it is predicted that the feed roll pair 58 needs to be replaced before a jam (a phenomenon such as a paper jam) occurs, and a warning is issued to the display unit of the image forming apparatus 1 as necessary.

  On the other hand, when the paper 9 is transported in the direction indicated by the paper transport direction D1, the projection light L is reflected by the paper 9 and enters the light receiving portion of the sensor 70 as shown in FIG. . As a result, the presence of the sheet 9 is detected. From the viewpoint of the detection accuracy of the presence / absence of the sheet 9, it is preferable that the light projection light L from the sensor 70 is irradiated to a position as close as possible to the press contact portion N.

  The position of the rotation speed extraction unit 72 will be described in more detail with reference to FIG. In general, there is a limit to the size of paper on which an image can be formed by an image forming apparatus. Also in the image forming apparatus 1, as shown in FIG. 4, the width of the sheet in the direction intersecting the sheet conveyance direction D1 is limited to the width Wmin. In this case, it is preferable that the rotation speed extraction unit 72 is inside the both ends of the width Wmin, and the recording medium conveyance device 80 according to the present embodiment is also arranged in this way. As a result, even when the paper 9 having the minimum width is conveyed, both the presence / absence of the paper 9 and the rotation speed of the feed roll pair 58 are detected.

  Next, the operation of the recording medium conveyance device 80 according to the present embodiment will be described with reference to the timing chart shown in FIG. FIG. 5A is a diagram showing the alternate of the first color and the second color of the rotation speed extraction unit 72 as “roll rotation”, and the high level (hereinafter “H”) is the first color. The low level (hereinafter, “L”) corresponds to the second color. A time T shown in FIG. 5A indicates a time required for one rotation of the driven roll 52. FIG. 5B shows the detection state of the paper 9 as “paper detection”, where L indicates the non-detection state and H indicates the detection state. The symbol “Pf” shown in FIG. 5B indicates the detection timing of the leading end portion Pf of the sheet 9, and the symbol “Pb” indicates the detection timing of the trailing end portion Pb of the sheet 9. The logic of H and L in the rotation of the roll shown in FIG. 5A and the detection of the paper shown in FIG. 5B may be reversed. FIG. 5C shows the output of the sensor 70 as “sensor output” when the rotation of the roll shown in FIG. 5A and the detection of the paper shown in FIG.

  The output of the sensor 70 becomes H when the first color is detected as the color of the rotation speed extraction unit 72 or when the paper 9 is detected. Accordingly, in FIG. 5C, the output of the sensor 70 becomes H due to the detection of the first color at time t1, and this H is maintained while the paper 9 is detected. Although the leading edge Pf of the paper 9 is detected at time t2, H at this time does not affect the output of the sensor 70. On the other hand, at time t4, the rear end portion Pb of the sheet 9 is detected, and the output of the sensor 70 becomes L. At time t3, the rotation of the roll becomes the second color and becomes L, but this L does not affect the output of the sensor 70. That is, the output of the sensor 70 is H when either roll rotation or paper detection is H, and is L when both roll rotation and paper detection are L. Since the rotation speed of the feed roll pair 58 is detected in a section where the sheet 9 is not detected by the sensor 70, in FIG. 5C, it is performed in a section other than the section from the time t1 to the time t4.

  As is apparent from FIGS. 5A and 5B, the detection of the paper 9 has an uncertainty of about half a pulse of the rotation of the roll. That is, in the case of detection of the leading end portion Pf of the paper 9 shown in FIG. 5B, it is unclear in which of the H rotation sections of the roll shown in FIG. Similarly, in the case of detection of the rear end portion Pb of the sheet 9 shown in FIG. 5B, when the detection is performed in the H section of the rotation of the roll shown in FIG. It is unclear whether it was detected by. However, this degree of uncertainty is not at a level that causes a problem in the conveyance control of the sheet 9. Further, in order to increase the temporal detection accuracy of the leading end portion Pf and the trailing end portion Pb of the paper 9, the pitch of the rotational speed extracting portion 72 can be made finer, that is, the number of convex pieces B of the meshing member 74 can be increased. That's fine.

[Second Embodiment]
The present embodiment is a mode in which operation control as an idle rotation mode in which the feed roll pair 58 is rotated without conveying paper to the feed roll pair 58 in the above embodiment is added. Accordingly, since the configurations of the recording medium conveyance device 80 and the image forming apparatus 1 are the same as those in the above-described embodiment, the illustration is omitted by referring to FIGS.

  As described above, in the recording medium conveyance device 80, the rotation speed is detected by rotating the drive roll 50 and rotating the feed roll pair 58 during a time period when the sheet 9 is not conveyed to the feed roll pair 58. Therefore, when the paper 9 is continuously conveyed, the rotation speed cannot be detected at the intended timing. Further, even if there is a time vacancy between the sheets 9 in the conveyance of the sheet 9, the time for one rotation of the feed roll pair 58 is not necessarily ensured. Therefore, in the present embodiment, an idling mode in which the feed roll pair 58 is intentionally rotated in order to detect the rotation speed in a time zone during which the sheet 9 is not conveyed is provided.

  Although the timing for executing the idling is not particularly limited, as an example, there is a timing for inserting and removing the storage cassette 31 for replenishing the paper 9. Immediately after the insertion and removal of the storage cassette 31 and before the paper 9 is lifted up, the paper is not conveyed even if it is idled. The operation in the idle rotation mode may be executed by, for example, performing a lift-down of the storage cassette 31 at regular intervals determined in advance by the control unit 25. Alternatively, the control unit 25 may execute the command when a user inputs a corresponding command from an operation unit (not shown) of the image forming apparatus 1.

  According to the recording medium conveyance device 80 and the image forming apparatus 1 according to the present embodiment having the idling mode, the rotation speed extraction unit 72 measures the rotation of the driven roll 52 for one rotation during the conveyance of the normal sheet 9. Even when the rotation is not performed, the rotation of the driven roll 52 is measured for one or more revolutions, and the detection accuracy of the rotation speed is expected to be improved as compared with the case where the idle rotation mode is not provided.

[Third Embodiment]
With reference to FIG. 6, the recording medium conveying apparatus and the image forming apparatus according to the present embodiment will be described. In the present embodiment, the recording medium conveyance device 80 in the above embodiment is replaced with a recording medium conveyance device 80A. Accordingly, the image forming apparatus on which the recording medium conveying apparatus 80A is mounted is the same as the image forming apparatus 1 described above. Therefore, if necessary, refer to FIG.

  As shown in FIG. 6A, the recording medium conveyance device 80A includes a feed roll pair 58A including a drive roll 50 and a driven roll 52, a sensor 70A, and a rotation speed extraction unit 72A.

  As shown in FIG. 6A, the sensor 70 </ b> A according to the present embodiment is a transmissive photosensor including a light projecting unit 76 and a light receiving unit 78. A transmissive photosensor, also called a photo interrupter, has a light projecting unit and a light receiving unit facing each other, and the presence or absence of a detection object is determined by whether or not the light projected from the light projecting unit reaches the light receiving unit. It is an optical switch to detect. That is, it detects that there is a detection object when the projection light is blocked by the detection object (paper 9) positioned between the light projection unit and the light reception unit and does not reach the light reception unit.

  As shown in FIG. 6A, in the present embodiment, the light projecting unit 76 and the light receiving unit 78 are disposed at a position orthogonal to (intersect) the paper transport direction D1, and the light projecting unit 76 disposed above. Is projected toward the light receiving part 78 disposed below. At that time, the sensor 70 </ b> A is configured such that the optical axis of the projection light L passes through a position corresponding to the pressure contact portion N between the drive roll 50 and the driven roll 52. Accordingly, the sensor 70A detects the presence or absence of the paper 9.

  Further, as shown in FIG. 6B, the sensor 70 </ b> A is arranged so that the optical axis of the projection light L also passes through the rotation speed extraction unit 72 </ b> A provided on the driven roll 52. As shown in FIG. 6B, the rotational speed extraction unit 72A according to the present embodiment is provided on a portion of the driven roll 52 opposite to the side to which the shaft 54 is connected. As shown in FIGS. 6A and 6B, the rotational speed extraction unit 72A includes four convex pieces B. When the projected light L from the light projecting unit 76 is blocked by the convex pieces B, the light receiving unit. If it passes between the convex piece B and the convex piece B without reaching 78, it reaches the light receiving part 78. As a result, the rotation speed of the feed roll pair 58A is detected. The convex piece B and the convex piece B arranged at a position diagonal to the convex piece B correspond to the “light-shielding part pair” according to the present invention, and between the convex piece B and the convex piece B, The space between the convex piece B and the convex piece B at the corner corresponds to the “transmission part pair” according to the present invention. In the present embodiment, the embodiment in which the projection light L is irradiated from the upper side to the lower side will be described as an example. However, the present invention is not limited to this. Irradiation from an oblique direction as shown in FIG.

  As described above, according to the recording medium conveyance device 80A according to the present embodiment, since the transmission type sensor is employed, there is an effect that the degree of freedom of the arrangement position of the sensor is increased. That is, as described above, it is preferable to arrange the sensor so that the projection light L is irradiated from the sensor at a position closer to the press contact portion N between the drive roll 50 and the driven roll 52. There is an effect that the sensor can be easily arranged by such a preferable position.

  Here, in the present embodiment, the embodiment in which the rotation speed extraction unit 72A is provided in the portion opposite to the side to which the shaft 54 of the driven roll 52 is connected has been described as an example. It is good also as a form provided in the part on the opposite side to the side to which 50 shafts are connected. Furthermore, it is not always necessary to provide the feed roll pair on the opposite side of the shaft, and if the connecting portion between the feed roll and the shaft has a gap for allowing light to pass, such as a universal joint (universal joint), The joint portion of the universal joint may be a rotational speed extraction unit.

  In each of the above embodiments, the recording medium conveying apparatus according to the present invention has been described as an example of applying the recording medium conveying apparatus to the recording medium conveying apparatus in the paper 9 feeding section. Is done. For example, the present invention may be applied to a recording medium conveyance device provided in an image reading device such as a scanner.

  Further, in the above-described embodiment, the embodiment in which the rotational speed is detected based on the difference in reflectance caused by the difference in the color of the reflected light at the meshing portion with respect to the light projected from the sensor has been described as an example. I can't. For example, it is good also as a form which provides the site | part which a reflection angle changes in two aspects with rotation in a meshing part, and detects a rotational speed by the difference in the light-receiving amount in the light-receiving part resulting from this difference in reflection angle. .

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Sending part 9 Paper 10 Image forming part 12 Photoconductor 13 Charging part 14 Exposure part 15 Developing part 16 Transfer part 17 Cleaning part 20 Fixing part 21 Case 22 Heating rotary body 23 Pressure member 25 Control part 30 Supply Paper section 31 Storage cassette 33, 34, 35 Paper transport roll pair 36 Discharge roll pair 39 Paper discharge section 41 Delivery roll 50 Drive roll 52 Driven roll 54 Shaft 56 Engagement section 58, 58A Feed roll pair 70, 70A Sensors 72, 72A Rotation Speed extraction unit 74 Intermeshing member 76 Light projecting unit 78 Light receiving unit 80, 80A Recording medium transport device B Convex piece D1 Paper transport direction L Light projecting light N Pressure contact portion Pf Front end portion Pb Rear end portion Wmin Width

Claims (11)

A drive rotator that is driven to rotate at a predetermined rotational speed, and a driven rotator that is pressed against and driven by the pressure contact portion of the drive rotator, and is sandwiched between the drive rotator and the driven rotator. A transport unit for transporting the recording medium
An extraction unit provided in the transport unit for extracting the rotation speed;
A recording medium conveying apparatus including: a detection unit configured to detect the presence or absence of the recording medium by irradiating light to a position corresponding to the pressure contact unit and detect the rotation speed by irradiating the extraction unit with light. The detection unit is composed of a reflection type sensor including a light projecting unit and a light receiving unit, and makes light from the light projecting unit at a position corresponding to the pressure contact unit at a predetermined angle with the conveyance direction of the recording medium. The recording medium conveying apparatus according to claim 1, wherein the recording medium conveying device detects the presence or absence of the recording medium by irradiating and receiving reflected light from the recording medium by the light receiving unit. The recording medium conveyance device according to claim 2, wherein the extraction unit is a meshing unit between the driven rotator and a shaft of the driven rotator. The meshing portion is different from the predetermined color having a predetermined first color convex portion provided on the shaft and a concave portion engaging with the convex portion provided on the driven rotating body. And a color fitting part,
The recording medium conveyance device according to claim 3, wherein the detection unit detects the rotation speed using a difference in reflectance due to a difference between the first color and the second color. The detection unit includes a transmissive sensor including a light projecting unit and a light receiving unit, and emits light from the light projecting unit at a position corresponding to the pressure contact unit along a direction intersecting the conveyance direction of the recording medium. The recording medium transport device according to claim 1, wherein the recording medium transport device is configured to detect the presence or absence of the recording medium by irradiating and receiving the projection light with the light receiving unit provided on the opposite side of the light projecting unit with respect to the pressure contact unit. . The extraction unit is a connection unit between the driven rotator and the shaft of the driven rotator, having a gap through which the projection light passes.
The recording medium conveyance device according to claim 5, wherein the detection unit detects the rotational speed by using whether light is incident or not incident on the light receiving unit by the extraction unit. The recording medium carrying device according to claim 6, wherein the connection portion is a universal joint. The recording medium conveyance device according to claim 5, wherein the extraction unit is provided on a side opposite to a side to which the shaft of the driven rotator is connected. The extraction unit is disposed diagonally with the rotation center of the driven rotating body as a center, and between one or a plurality of light shielding unit pairs that shield the projection light and each of the plurality of light shielding units. And a transmission portion pair that is disposed and transmits the projection light,
The recording medium conveyance device according to claim 8, wherein the detection unit detects the rotational speed using incident or non-incidence of light to the light receiving unit by the extraction unit. In a state where the recording medium is not conveyed by the conveying unit, the driving unit and the driven rotating unit are rotated, and the detection unit is configured to detect the rotation speed by irradiating the extraction unit with light. The recording medium conveying apparatus according to claim 1, further comprising a control unit that controls the recording medium. A forming unit for forming an image on the recording medium;
An image forming apparatus comprising: the recording medium conveyance device according to claim 1.