JP2007133080A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming an image on a long image forming medium without making the entire apparatus larger. <P>SOLUTION: A storing space part S for temporarily storing paper P is provided behind an exposure engine 7 for performing scanning exposure on the paper P. A take-up mechanism 8 for temporarily taking up the paper P longer than prescribed length is provided in the storing space part S. The take-up mechanism 8 is constituted to take up the paper P to a take-up drum 20 in such a state that the front side of the paper P in a conveying direction is held between the take-up drum 20 and a press-fit roller 21. The paper P is held between the take-up drum 20 and the press-fit roller 21 even while the scanning exposure is performed on the rear side of the paper P in the conveying direction by the exposure engine 7. It is desirable that the press-fit member 212 of the press-fit roller 21 is formed of an elastic member such as foaming material or its outer circumferential surface has low-friction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including an image recording unit that forms an image on an image forming surface while transporting an image forming medium by a transport mechanism.

  2. Description of the Related Art Conventionally, as an image forming apparatus used for developing a photograph or the like, an apparatus that performs image exposure on paper (e.g., corresponding to an image forming medium such as photographic paper) with a laser beam is known. A configuration example of such an apparatus is shown in FIG. This apparatus reads image data of frame images formed on a developed negative film and image data stored in various storage media, and prints and exposes an image on the emulsion surface of paper based on these image data. It is configured as follows.

  In FIG. 13, the paper magazine 100 stores the paper in a rolled state. The paper drawn out from the paper magazine 100 is transported along the transport path, and is cut into a predetermined print size by the paper cutter 101. The cut paper P is transported toward the image recording unit 103 by the transport unit 102. The image recording unit 103 feeds and scans laser light in the main scanning direction (a direction perpendicular to the sub-scanning direction, which is the transport direction) while transporting the paper P at a predetermined speed while the paper P is sandwiched between the transport rollers 104 for exposure. By doing so, an image (latent image) is exposed and formed on the surface of the paper P. Two units of the exposure transport roller 104 are arranged along the transport direction, and a scanning position by a laser beam is set between the upstream transport roller 104 and the downstream transport roller 104. The paper P on which the image has been printed and exposed is then transferred to other transport units 105 and 106 disposed on the downstream side of the image recording unit 103 and sent to the development processing unit.

  Here, when scanning exposure is performed with laser light as described above, if a large vibration or load fluctuation occurs on the paper P during image exposure, exposure unevenness or the like occurs, which adversely affects the image quality of the printed image. . Therefore, as disclosed in Patent Document 1, for example, a so-called post-exposure buffer having a long conveyance path is provided on the downstream side of the image recording unit 103 to suppress the occurrence of exposure unevenness.

Further, as shown in FIG. 13, an accommodation space portion 107 as a post-exposure buffer that temporarily accommodates the paper P is provided on the downstream side of the image recording portion 103, and the paper P is fed into the accommodation space portion 107. What was done is also known. In this apparatus, when the image exposure in the image recording unit 103 is completed, the paper P accommodated in the accommodation space 107 is conveyed by the conveyance units 105 and 106 and conveyed to the development processing unit. By providing such a storage space 107, a large load is not applied to the paper P, and image exposure is performed in a stable load state.
JP-A-10-325983

  By the way, in the image forming apparatus as shown in FIG. 13, since scanning exposure is performed based on the read image data, it is possible to perform printing in a longer size than in the past. Since it is necessary to provide a post-exposure buffer corresponding to the print size, there is a problem in that the conveyance path becomes longer and the accommodating space 107 becomes larger, leading to an increase in the size of the entire image forming apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of forming an image on a long image forming medium without increasing the size of the entire apparatus. There is to do.

  In order to achieve the above object, in the image forming apparatus according to the present invention, the front end side in the transport direction of the image forming medium on which image formation is performed is sandwiched by a pair of sandwiching members for changing the transport direction. In a narrow space, it is possible to easily change or store the conveyance direction of the image forming medium after image formation.

  Specifically, the invention of claim 1 is directed to an image forming apparatus including an image recording unit that forms an image on an image forming surface while transporting an image forming medium by a transport mechanism. A pair of sandwiching members that are disposed downstream of the image recording unit and sandwich the image forming medium and change the transport direction, and a front end side in the transport direction of the image forming medium is located between the sandwiching members. It is assumed that there is provided an insertion determining means for determining whether or not a predetermined amount has been inserted, and a clamping interval changing means for changing the interval between the clamping members.

  Further, when the image recording unit is performing image formation on an image forming medium having a predetermined length or more, the pair of sandwiching members is inserted between the sandwiching members by a predetermined amount or more between the front ends in the transport direction of the image forming medium. The holding interval changing means narrows the interval between the holding members when the insertion determining means determines that the image forming medium has been inserted between the holding members. It is assumed that the front end side in the conveyance direction of the image forming medium is sandwiched.

  With the above configuration, even when an image is formed by the image recording unit on a part of the image forming medium having a predetermined length or more, the front end side in the transport direction of the image forming medium is a pair of sandwiches for changing the transport direction. For example, the image forming medium is stored in a narrow space such as changing the conveyance direction of the image forming medium in a narrow space or winding the image forming medium on a roller. It becomes possible to do. In other words, it is possible to provide a post-exposure buffer that can sufficiently prevent the occurrence of uneven exposure of a long image forming medium without increasing the size of the entire apparatus.

  In addition, when the front end in the conveyance direction of the image forming medium is inserted into the clamping member by a predetermined amount or more, the gap between the clamping members is narrowed so that the image forming medium is conveyed between the clamping members. The insertion at the front end in the direction is facilitated, and the image forming medium can be clamped more easily and reliably.

  The predetermined length refers to the length in the conveyance direction of the image forming medium that the conveyance direction must be changed in order to secure a sufficient post-exposure buffer. The predetermined amount is an insertion amount so that the front end side of the image forming medium in the conveying direction can be securely sandwiched by a pair of sandwiching members, and the front end side of the image forming medium inserted between the sandwiching members serves as another constituent member. It means an amount that does not contact. In this way, by preventing the front end of the image forming medium inserted between the sandwiching members from hitting other components, vibration and load fluctuations occur when inserting the image forming medium, resulting in uneven exposure. Can be reliably prevented.

  In the above-described configuration, at least one of the pair of clamping members is provided with a buffering means for buffering an impact when gripping the front end side in the conveyance direction of the image forming medium (claim). Item 2). Thereby, since the impact when the front end side in the conveyance direction of the image forming medium is clamped by the pair of clamping members is buffered, it is possible to prevent a large vibration or load fluctuation from acting on the image forming medium during clamping. it can. In other words, even when the image forming medium is transported on the front end side in the conveyance direction by the pair of clamping members as in the first aspect of the present invention, uneven exposure occurs when the image forming medium is sandwiched. Can be prevented.

  It is preferable that the buffer means is an outer peripheral portion of a clamping member constituted by an elastic member (invention of claim 3). In this case, when the front end side in the conveyance direction of the image forming medium is sandwiched between the pair of sandwiching members, the surface of the sandwiching member is elastically deformed, so that large vibration and load fluctuations act on the image forming medium when sandwiched. Can be prevented, and the occurrence of uneven exposure can be prevented.

  The elastic material is preferably a foamed material (the invention of claim 4). As described above, if the outer peripheral portion of the sandwiching member is made of a foam material, the surface of the sandwiching member is easily elastically deformed, so that vibrations and load fluctuations acting on the image forming medium can be further reduced. Thus, the occurrence of uneven exposure can be prevented more reliably.

  Furthermore, the buffer means may be a surface of a clamping member in a predetermined low friction state (invention of claim 5). Here, the predetermined low friction state means a state where the static friction coefficient between the clamping member and the image forming medium is 0.5 or less. In this way, when the image forming medium is sandwiched between the pair of sandwiching members, it is possible to prevent the image forming medium from being subjected to vibration and load fluctuation due to friction with the surface of the sandwiching member. Can be prevented.

  As described above, according to the image forming apparatus of the present invention, the pair of sandwiching members provided on the downstream side of the conveyance from the image recording unit can convey the image forming medium even when the image is formed on the image forming medium. It is configured to hold the front end side in the direction, and it is possible to change the transport direction in a narrow space, store it, etc., so that long printing with little exposure unevenness can be performed without increasing the size of the entire apparatus become.

  Further, by providing a buffering means on at least one of the pair of clamping members, vibrations and load fluctuations acting on the image forming medium when the image forming medium is clamped can be reduced. Can be prevented. In particular, if the outer peripheral side of the clamping member is made of a foam material, vibrations and load fluctuations when clamping the image forming medium can be reduced more effectively, and the occurrence of uneven exposure can be more reliably prevented. it can.

  Furthermore, even when the surface of the clamping member is in a low friction state, the frictional resistance when clamping the image forming medium is reduced, and vibration and load fluctuations can be effectively reduced. Can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

<Overall configuration of photo processing system>
FIG. 1 is a partial cross-sectional view showing a configuration of a photographic processing system provided with an image forming apparatus A according to the present invention. The photographic processing system shown in FIG. 1 acquires image data, prints and exposes an image on an emulsion surface (corresponding to an image forming surface) of paper (corresponding to an image forming medium) based on the image data, and prints a photographic print. Has the ability to create. This photographic processing system scans frame images formed on developed photographic film and uses it for film scanners (not shown) for acquiring image data, storage media for digital cameras, and other recording media. A media reading unit (not shown) for reading stored image data is provided.

  The paper magazines 3 and 3 shown in FIG. 1 respectively accommodate rolls of long paper wound in a roll shape, and the paper magazines 3 and 3 can be attached to and detached from the main body of the image forming apparatus A. Is attached. Of the two paper magazines 3 and 3 attached to the main body of the image forming apparatus A, one paper magazine 3 is selected according to the print size and the like, and is drawn out from the selected paper magazine 3. The paper P is transported along a predetermined transport path. That is, the direction of the paper drawn out from the paper magazine 3 is changed by the advance roller unit 4 and cut into a predetermined print size by the paper cutter 5. The cut paper P is transported by the transport unit 6 to an exposure engine 7 (corresponding to an image recording unit) located on the downstream side.

  The exposure engine 7 is provided with an upstream exposure transport roller 9a and a downstream exposure transport roller 9b (which correspond to a transport mechanism). Between these exposure transport rollers 9a and 9b, an exposure position for exposing the paper P with laser light is set. A paper detection sensor 10 is provided on the upstream side of the exposure conveyance roller 9. When the paper P is fed in, the front end (front end) portion is detected and a signal is output. The paper detection sensor 10 includes a light emitting element that outputs infrared light and a light receiving element that receives the light. By detecting the position of the paper P by the paper detection sensor 10, the exposure start timing at the exposure position can be determined.

  The exposure engine 7 has a known structure, optically modulates laser light output from a laser light source (laser diode or the like) based on image data, and irradiates the paper P with the light-modulated laser light. Thus, image exposure is performed. When performing image exposure, the paper P is transported at a predetermined speed (constant speed) while being sandwiched between the exposure transport rollers 9a and 9b. Since the laser beam is scanned in the main scanning direction orthogonal to the transport direction (sub-scanning direction) of the paper P, an image (latent image) is printed and exposed on the paper P for each line.

  Then, while the image exposure as described above is performed, the paper P is sent to the downstream side of the exposure position by the downstream exposure transport roller 9b. A first transport unit 11 is provided on the downstream side of the exposure engine 7. As will be described in detail later, the first transport unit 11 is provided so as to be rotatable around a predetermined rotation axis, and the second transport unit 12 further receives the paper P delivered by the downstream exposure transport roller 9b. It has a function to pass to. The second transport unit 12 includes a plurality of nipping and transporting roller pairs 12a arranged along the transport path, and a guide plate 12b for forming the transport path, and the transport roller pair 12a is not shown. It is configured to be driven by a mechanism.

  An accommodation space S for temporarily accommodating the paper P is provided on the downstream side of the exposure engine 7 (left side of the exposure engine 7 in FIG. 1). That is, if the length of the paper P is longer than the distance from the exposure position to the development processing unit, the paper P enters the development processing unit during exposure, and the vibration generated by the processing in the development processing unit Since it is transmitted to the exposed portion of P and causes uneven exposure, the paper P is accommodated in the accommodating space S so that the occurrence of uneven exposure is reliably prevented.

  In addition, as will be described in detail later, the method of accommodating the paper P in the accommodating space S differs depending on the length of the paper P in the transport direction. In the following embodiment, a case where the length in the transport direction of the paper P is a predetermined value (for example, 594.1 mm) or more will be described.

  In the accommodation space S, a winding drum 20 (clamping member) for winding the paper P and a pressure roller 21 (clamping member) for pressing and holding the paper P on the outer peripheral surface of the winding drum 20 ) And are arranged. As will be described in detail later, the take-up drum 20 and the pressure roller 21 sandwich the front end side in the transport direction of the paper P and function as the take-up mechanism 8.

  A sag detection sensor 22 for detecting the sag of the paper P accommodated in the accommodation space S is provided below the winding drum 20 in the accommodation space S. The sag detection sensor 22 includes a light emitting element 22a and a light receiving element 22b. When light irradiated from the light emitting element 22a is blocked by the paper P, it is determined that the sag amount is greater than a predetermined amount. The Here, the line connecting the light emitting element 22a and the light receiving element 22b is set to be inclined with respect to the horizontal line as shown in FIG.

<Constitution of accommodation space>
Next, the structure in the accommodation space part S in FIG. 1 is demonstrated based on FIG. The first transport unit 11 is disposed further downstream of the downstream exposure transport roller 9b, and includes a sandwiching transport roller pair 11a and a guide plate 11b. The position in the height direction of the pair of nipping and conveying rollers 11a is set to be the same height position as that of the exposure and conveying roller 9, and an opening 11c is formed at the upstream end of the guide plate 11b. Therefore, the paper P can be easily received.

  The first transport unit 11 is configured to be able to rotate 90 ° around a predetermined rotation axis (see FIG. 12), and in the state rotated 90 °, the paper P can be delivered to the second transport unit 12. It can be done. As described above, the second transport unit 12 includes a plurality of transport roller pairs 12a and guide plates 12b, and plays a role of feeding the paper P received from the first transport unit 11 to a development processing unit (not shown). Fulfill.

  The take-up drum 20 is configured to be rotatable around the rotation axis 20a. Before the winding of the paper P by the winding drum 20 is started, the outer peripheral surface of the winding drum 20 and the surface of the pressure roller 21 are separated from each other and a gap is formed. Thereby, the conveyed paper P can be easily inserted into the gap between the winding drum 20 and the pressure roller 21.

  The receiving height of the paper P by the winding drum 20 is set to be the same as the height of the conveyance surface by the exposure conveyance roller 9 and the conveyance surface before the rotation of the first conveyance unit 11. Yes. Thereby, the paper P sent out by the exposure transport roller 9 can be smoothly received on the winding drum 20 side. In the state shown in FIG. 2, the shaft core of the pressure roller 21 is located just above the shaft core of the winding drum 20.

  Further, a winding movement mechanism 13 for moving the winding mechanism 8 in the vertical direction is provided in the accommodation space S, and the entire winding mechanism 8 is exposed to the exposure engine 7 by the winding movement mechanism 13. It is possible to move from an upper first position (position in FIG. 2) close to the exposure position to a lower second position (position in FIG. 9) far from the exposure position. Specifically, the take-up moving mechanism 13 includes a guide member 13a extending in the vertical direction and a timing belt 13b for moving the take-up mechanism 8 along the guide member 13a. A support 15 for supporting the take-up mechanism 8 is fixed, and the take-up mechanism 8 can be moved up and down by driving the timing belt 13b by a motor (not shown). . The support 15 is mounted with drum driving means (such as a motor and a speed reduction mechanism) for driving the winding drum 20 to rotate.

  Here, the storage space S is adjacent to the development processing unit and is partitioned by the wall surface 14. However, when the paper P is moved up and down on the winding drum 20, the paper P is It is preferable not to rub the wall surface 14. On the other hand, if the accommodating space S is made larger, the rubbing between the wall surface 14 and the paper P can be eliminated, but there is a problem that the entire apparatus becomes larger. Therefore, the take-up moving mechanism 13 is configured such that the take-up mechanism 8 moves obliquely downward as shown in FIG. Specifically, the winding movement mechanism 13 is configured to move in a direction away from the wall surface 14 as the winding mechanism 8 is lowered. Thereby, the winding mechanism 8 can move downward in the accommodation space S without the paper P rubbing the wall surface 14.

  In addition, although mentioned later in detail, after the said winding mechanism 8 is moved below by the winding movement mechanism 13, when the paper P has more than a predetermined sag, the paper P is removed by the winding mechanism 8. I'm trying to wind it up. In this way, by providing a certain degree of slack, the paper P can be taken up without transmitting large vibrations or load fluctuations to the exposed portion of the paper P, thereby preventing uneven exposure. can do.

  By providing the accommodation space S and the winding mechanism 8 configured as described above, the following effects can be obtained. Image exposure by the exposure engine 7 is performed while the paper P is conveyed at a predetermined speed by the exposure conveyance roller 9. When this scanning exposure is performed, for example, development processing or the like is performed on the front side in the conveyance direction. If done, large vibrations and load fluctuations will occur in the paper P, or the latent image progression time cannot be secured sufficiently, and the image quality of the image formed on the paper P will deteriorate. On the other hand, as described above, the paper P sent out by the exposure transport roller 9b is temporarily accommodated in the accommodation space S until the exposure is completed, so that the paper P does not undergo large vibration or load fluctuation. And sufficient time for the latent image to travel.

  Moreover, when a long paper having a long length in the transport direction is to be stored in the storage space portion S, a large storage space is required. However, the winding mechanism 8 as described above is provided to wind the paper P. As a result, the space of the accommodation space portion S can be reduced, and an increase in the size of the entire apparatus can be prevented.

<Configuration of winding mechanism>
Next, a detailed configuration of the winding drum 20 and the pressure roller 21 constituting the winding mechanism 8 will be described with reference to FIG. FIG. 4 shows a cam mechanism (corresponding to a roller interval changing means) for moving the pressure roller 21 in the pressure direction.

  The take-up drum 20 is configured to be rotatable around a fixed shaft 200. The winding drum 20 is made of resin, and the paper P is wound on the outer peripheral surface thereof. Both ends in the axial direction of the winding drum 20 are provided with circumferential grooves 202 for engaging the coil springs 24 that urge the pressing roller 21 in the pressing direction. A connection gear 201 for rotating the take-up drum 20 is provided on the end side of the circumferential groove 202 at one end.

  The pressure roller 21 includes a roller support shaft 210 disposed substantially parallel to the axis of the take-up drum 20, and a resin product provided in a plurality in the axial direction so as to cover the outer peripheral surface of the roller support shaft 210. .., And crimping members 212, 212,... Described later (corresponding to the outer peripheral portion) respectively attached to the surface of each of the support shafts 211. The roller support shaft 210 is fitted with an E-ring 213 for preventing the support shafts 211, 211,... From moving in the axial direction with respect to the roller support shaft 210.

  Grooves 214 and 214 for engaging the coil spring 24 are formed at both ends of the roller support shaft 210 in the axial direction. Further, cam connecting shafts 215 and 215 are provided at both axial ends of the roller support shaft 210 and inside the groove portions 214 and 214, respectively. The cam connecting shafts 215 are cam mechanisms which will be described later. By moving up and down according to the shape of the cam surface 203a, the pressure roller 21 can be moved in the pressure bonding direction or the non-pressure bonding direction. According to the mechanism shown in FIG. 3, when the take-up drum 20 rotates, the pressure roller 21 also rotates and moves along the outer peripheral direction of the take-up drum 20 (rotates around the fixed shaft 200) in conjunction with the rotation. Can do. The pressure roller 21 itself is pivotally supported so as to be freely rotatable about the roller support shaft 210 as a rotation center.

  Next, a cam mechanism for moving the pressure roller 21 in the pressure bonding direction will be described with reference to FIG. FIG. 4 shows a cross-sectional view of the winding mechanism 8 shown in FIG. 3 cut along a plane perpendicular to the fixed shaft 200 at a portion where a cam is formed. As shown in FIG. 4, the cam member 203 is coupled to the fixed shaft 200 via the clutch member 204. The cam member 203 has a cam surface 203a, and the tip 215a of the cam coupling shaft 215 is always in contact with the cam surface 203a by the biasing force of the coil spring 24 described above.

  As shown in FIG. 4, the cam surface 203 a is formed in a range of θ = 210 ° on the outer peripheral surface of the cam member 203, so that the cam connecting shaft 215 (the pressure roller 21) is in contact with the cam member 203. The range that can be rotated is also 210 °. A first wall surface 203b and a second wall surface 203c are formed at both circumferential ends of the cam surface 203a. When the cam connecting shaft 215 moves relative to the cam surface 203a, the cam connecting shaft 215 Are positioned in contact with the wall surfaces 203b and 203c.

  4A is a diagram showing an initial state in which a gap is formed between the pressure roller 21 and the take-up drum 20, and FIG. 4B shows a state where the pressure roller 21 rotates 210 ° and the pressure roller 21 is rotated. It is a figure which shows the state by which the paper P was crimped | bonded by. Thus, when the take-up drum 20 is rotated 210 °, the state shown in FIG. 4B is obtained, but when the take-up drum 20 is further rotated, the cam coupling shaft 215 comes into contact with the second wall surface 203c, The cam member 203 is forcibly rotated around the fixed shaft 200 together. At this time, the frictional slip is generated in the clutch member 204. That is, by providing the clutch member 204, the pressure roller 21 can be rotated beyond a range (210 °) regulated by the cam member 203.

<Crimping member>
Next, the material of the crimping member 212 which is one of the characteristic portions of the present invention will be described in detail below. That is, the crimping member 212 is formed of an elastic foamed member (for example, foamed urethane) such as a sponge, and can be easily used when the paper P is sandwiched between the outer peripheral surface of the winding drum 20. Elastic deformation is generated. Thereby, when the paper P is sandwiched between the take-up drum 20 and the pressure roller 21, it is possible to prevent the paper P from being subjected to large vibrations and load fluctuations. Therefore, even when the leading end side in the transport direction of the paper P is sandwiched between the winding drum 20 and the pressure roller 21 during the exposure process, a large vibration or load fluctuation acts on the paper P to cause uneven exposure. Can be prevented.

  Here, as described above, the pressure roller 21 is configured to be pressure-bonded to the take-up drum 20 by the coil springs 24 hung on both ends in the axial direction. There is a case where deformation occurs in an arcuate shape and floats without receiving a force in the crimping direction at the central portion in the axial direction. On the other hand, if the pressure roller 21 is made of an elastic material as described above, both end portions in the axial direction of the pressure roller 21 are largely elastically deformed and do not float at the central portion in the axial direction. P can be securely held between the winding drum 20 and the pressure roller 21. As a result, when the paper P is sandwiched between the winding drum 20 and the pressure roller 21, it is possible to prevent the paper P from being wrinkled or subjected to load fluctuations, and to ensure that uneven exposure is generated. Can be prevented.

  In the case described above, the distribution of the pressure bonding force between the winding drum 20 and the pressure roller 21 is different in the axial direction, but in this embodiment, a paper is interposed between the winding drum 20 and the pressure roller 21. The paper P is merely sandwiched, and the paper P is not transported by the take-up drum 20 and the pressure roller 21. Therefore, there is no problem such that the paper P meanders due to imbalance of the pressure.

  The crimp member 212 is not limited to a foam member, and any material that elastically deforms so as not to give vibration or load fluctuation to the paper P when the paper P is sandwiched, such as a rubber material, for example. It may be anything.

  The outer peripheral surface of the crimping member 212 is preferably in a low friction state in order to reduce resistance when the paper P is sandwiched between the winding drum 20 and the outer peripheral surface. By doing so, when the paper P is sandwiched between the take-up drum 20 and the pressure roller 21, the frictional resistance between the pressure roller 21 and the paper P is reduced. Variation can be effectively reduced.

  Here, the low friction state means that the friction coefficient with respect to the paper P is 0.5 or less. Note that the value of this friction coefficient is the maximum frictional force and vertical drag when a rectangular parallelepiped member made of the same material as the crimping member 212 is slid in a substantially horizontal direction on the paper in the atmosphere at an ambient temperature of 25 ° C. It is required from the relationship. Specifically, each maximum frictional force when the vertical drag was changed was measured, and the friction coefficients calculated from those values were averaged.

<Control block diagram>
Next, the control block configuration of the image forming apparatus A will be described with reference to FIG. In FIG. 5, the paper leading edge detection means 30 detects the leading edge (front edge) of the paper P by the output signal from the paper detection sensor 10 and detects the arrival of the paper P. Further, it is also possible to recognize at which position the paper P is present on the downstream side based on the timing at which the leading edge of the paper P is detected. The roller driving unit 31 is configured by a driving mechanism, a driving circuit, and the like for driving the exposure conveyance roller 9. Further, the transport amount detection unit 32 is configured to detect the transport amount of the paper P by detecting the rotation amount of the exposure transport roller 9. That is, since the exposure transport roller 9 is controlled to rotate at a constant speed, the transport amount can be monitored by an encoder or the like.

  The paper position detection unit 33 is configured to detect various positions of the paper P based on the front end position of the paper P detected by the paper front end detection unit 30 and the transport amount of the paper P detected by the transport amount detection unit 32. It has the function which calculates | requires and calculates | requires. Specifically, the paper position detection unit 33 includes an exposure start timing detection unit 33a, a paper rear end escape detection unit 33b, and an insertion detection unit 33c (insertion determination unit).

  The exposure start timing detection means 33a is configured to detect the exposure start timing by the laser beam based on the leading edge position of the paper P detected by the paper leading edge detection means 30. That is, since the position of the paper detection sensor 10 and the exposure position by the laser beam are determined by design, if the leading end position of the paper P is known, the exposure start timing detection means 33a calculates the exposure start timing at the exposure position. Can do. The paper rear end escape detecting means 33b is for detecting that the rear end of the paper P on which image printing exposure has been completed has escaped from the exposure position. The insertion detection means 33c is for detecting that the front end of the paper P is inserted into the gap between the winding drum 20 and the pressure roller 21. The amount of insertion into this gap is usually about 20 mm, but this amount of insertion can be set as appropriate.

  The exposure control unit 34 is configured to start image exposure with laser light based on the calculation result of the exposure timing by the exposure start timing detection unit 33a. Thus, the latent image can be formed by scanning the emulsion surface of the paper P with the laser beam light-modulated by the image data.

  The first transport unit driving unit 35 has a mechanism for driving the first transport unit 11. Specifically, the first transport unit driving unit 35 rotates the entire first transport unit 11 by 90 ° with the crimp driving means 35a for switching the transport roller pair 11a between the crimping state and the non-crimping state. Unit rotation means 35b for switching between the horizontal state and the vertical state, and roller drive means 35c for rotationally driving the conveyance roller pair 11a are provided. Here, when the exposure engine 7 is performing image exposure, the pressure-bonding driving unit 35a places the transport roller pair 11a in a non-pressure-bonded state so that no load is applied to the paper P.

  The second transport unit driving unit 36 has a mechanism for driving the second transport unit 12, and includes a roller driving unit 36a that rotationally drives the transport roller pair 12a.

  The transport unit drive control means 37 is configured to perform drive control of the first transport unit 11 and the second transport unit 12. For example, when the paper position detection unit 33 detects that the rear end of the paper P has escaped from the exposure position, the transport roller pair 11a is switched to the press-bonded state.

  In the print size setting means 40, print size data of the paper P subjected to image exposure is set and stored. Then, based on the print size data stored in the print size setting means 40, the winding movement mechanism 13 and the winding drum 20 are controlled. For example, when the length of the paper P is shorter than a predetermined length (430.1 mm in this embodiment), the paper P is not pressed and wound by the winding mechanism 8.

  The sag amount detecting means 41 is configured to detect whether the sag amount is equal to or larger than a predetermined amount based on an output signal from the sag detection sensor 22. The drum driving unit 42 includes a mechanism for driving the winding drum 20 to rotate. The rotation amount detection means 43 is configured to detect the rotation amount of the winding drum 20. For example, the amount of rotation can be monitored by an encoder that rotates in conjunction with the winding drum 20.

  The drum rotation control means 44 has a function of performing rotation drive control of the winding drum 20. The drum rotation control unit 44 detects the leading end of the paper P by the insertion detection unit 33c, and print size data stored and set in the print size setting unit 40. Perform stop control.

  The winding control means 45 performs drive control of the winding movement mechanism 13. For example, when the rotation amount detecting means 43 detects that the pressure bonding operation by the pressure roller 21 is completed (θ = 210 ° rotation), the winding drum 20 is controlled to move from the first position to the second position. In the case of the paper P having a short length, since the winding operation by the winding mechanism 8 is not performed, the winding drum 20 is allowed to escape to the lowermost second position. In the case of the paper P having an intermediate length, the paper P is crimped by the winding mechanism 8 but the amount of sag is not detected by the sag detection sensor 22, so that the winding drum 20 is set to the first position. Control is performed to move to an intermediate position (third position) of the second position. Thus, the winding control means 45 is configured to change the control of the winding moving mechanism 13 in accordance with the length of the paper P in the transport direction. Information regarding the length dimension of the paper P can be obtained from the print size setting means 40.

  Here, the control block shown in FIG. 5 can be constructed by the function of computer software or hardware. Which function is realized by software and which function is realized by hardware can be appropriately determined according to the paper processing capability and the like.

<Operation of winding mechanism>
Next, the operation from the image exposure to the paper P until it is sent to the development processing unit will be described with reference to the flowcharts of FIGS. 6A and 6B and FIGS. 2 and 7 to 12. It is assumed that the print size setting means 40 is set with a print size having a length that requires the winding mechanism 8 to be lowered to the second position.

  First, the leading edge of the paper P cut to a predetermined print size is detected by the paper detection sensor 10 and the paper leading edge detection means 30 (step ST1). A predetermined timing elapses after the leading edge of the paper P is detected, and the exposure start timing detection means 33a detects that the exposure start timing is reached, and then the exposure control unit 34 applies laser to the emulsion surface of the paper P. The light is scanned and exposed to form an image (step ST2).

  While performing scanning exposure with laser light in this way, the paper P is transported toward the downstream side by the exposure transport roller 9, and the leading end of the paper P passes through the guide plate 11 b of the first transport unit 11. At this time, since the pair of transport rollers 11a of the first transport unit 11 is in a state where the pressure bonding is released, the paper P passes through the position of the first transport unit 11 without applying a large load to the paper P. Can do.

  Since the take-up drum 20 is set in the first position as shown in FIG. 2 in advance, the paper P that has passed through the first transport unit 11 as described above is directly between the take-up drum 20 and the pressure roller 21. It is conveyed toward the gap between them. The leading end position of the paper P is calculated by the paper position detection unit 33 based on the detection result by the paper detection sensor 10 and the transport amount of the paper P, and the leading end of the paper P is wound by the insertion detection unit 33c from the calculation result. It is determined whether or not it has been inserted into the gap between the take-up drum 20 and the pressure roller 21 (step ST3). In the present embodiment, the front end of the paper P is detected by the paper detection sensor 10 provided before the exposure position, and the front end position of the paper P is determined based on the detection result and the transport amount of the paper P. Is calculated to detect that the leading end of the paper P is inserted between the winding drum 20 and the pressure roller 21, but this is not restrictive, and the winding drum 20 and the pressure roller 21 are detected. A sensor or the like may be provided so that the amount of insertion between the two can be directly detected.

  When it is detected by the insertion detection means 33c that the leading end of the paper P is inserted into the gap between the winding drum 20 and the pressure roller 21 (YES in step ST3), the rotation of the winding drum 20 Is started (step ST4). FIG. 2 shows a state immediately after the leading end of the paper P is inserted into the gap. Then, the take-up drum 20 rotates counterclockwise in FIG. 2, and the pressure roller 21 similarly rotates around the rotation axis 20a. Thereafter, the pressure roller 21 is moved in the pressure-bonding direction by the above-described cam mechanism so that the gap between the pressure roller 21 and the winding drum 20 is gradually narrowed.

  At this time, scanning exposure with laser light is performed on the rear side in the transport direction of the paper P. That is, the leading end side in the transport direction of the paper P being exposed is sandwiched between the winding drum 20 and the pressure roller 21. In this way, even during exposure, by sandwiching the front side of the long paper P in the conveyance direction, the conveyance direction of the paper P can be easily changed or wound around the take-up drum 20 even in a narrow space. Therefore, it is possible to secure a post-exposure buffer that can sufficiently prevent the occurrence of uneven exposure without increasing the accommodation space S according to the length of the paper P. Therefore, it is possible to perform long printing while preventing an increase in the size of the entire apparatus.

  Then, it is determined whether or not the winding drum 20 has rotated a predetermined amount (210 ° in the example in the figure) (step ST5). If it is determined that the winding drum 20 has rotated by a predetermined amount (YES in step ST5), the winding drum 20 is wound. The rotation of the take-up drum 20 is stopped (step ST6). The rotation amount is detected by the rotation amount detection means 43. FIG. 7 is a view showing a state immediately after the rotation of the winding drum 20 is stopped. Here, the rotational speed of the take-up drum 20 is set so that the peripheral speed thereof is substantially the same as the feeding speed of the paper P by the exposure transport roller 9. By setting the rotation speed of the take-up drum 20 in this way, the paper P can be taken up at a speed as fast as possible without large load fluctuations acting on the paper P. If the rotation of the take-up drum 20 is made slightly slower than the feed speed of the paper P, the take-up can be performed with a slight slack. Can be prevented.

  After the rotation of the take-up drum 20 is stopped in step ST6, the take-up movement mechanism 13 is driven by the take-up control means 45 to lower the take-up mechanism 8 from the first position to the second position (step ST7). ). Steps ST6 and ST7 may be performed almost simultaneously. For example, the downward movement of the winding mechanism 8 may be started immediately before the winding drum 20 stops.

  Here, it is preferable that the downward movement of the winding mechanism 8 as described above is set to be slower than the speed at which the paper P is fed into the accommodation space S. Thereby, it is not necessary to give a large load fluctuation to the paper P. FIG. 8 shows a state in which the take-up drum 20 has moved to an intermediate position (third position) between the first position and the second position. In FIG. 8, since the lowering speed of the take-up drum 20 is slow, sagging begins to occur in the paper P portion between the take-up drum 20 and the first transport unit 11. FIG. 9 shows a state where the take-up drum 20 has been lowered to the second position.

  Even after the rotation of the take-up drum 20 is stopped and the take-up drum 20 is moved to the second position as described above, the paper P is fed into the accommodation space S by the exposure transport roller 9. At this time, it is determined by the paper trailing edge escape detection means 33b whether or not the trailing edge of the paper P has reached the first transport unit 11 (step ST8). If it is determined that the trailing edge of the paper P has arrived (YES in step ST8), the process proceeds to step ST15. On the other hand, if it is determined in step ST8 that the rear end has not reached (in the case of NO), since the paper P is fed in, the sag gradually increases. As shown in FIG. The light is blocked by the slack of the paper P (step ST9). At this time, even if the sagging increases, the winding drum 20 moves obliquely downward, that is, in a direction away from the wall surface 14, so that the paper P is sagged without rubbing the wall surface 14.

  Here, the state in which the rear end of the paper P reaches the first transport unit 11 is defined as a state in which the rear end of the paper P slightly protrudes upstream from the nipping and transporting roller pair 11a. About this protrusion amount, it can set suitably.

  In the state shown in FIG. 10, the sag amount detecting means 41 determines that a sag of a predetermined amount or more has occurred (in the case of YES at step ST9), and the winding drum 20 is rotated again (step ST10). The winding drum 20 is rotated at a higher speed than the rotational driving in the previous step ST4. This is for eliminating the sag that has become too large at an early stage. When it is determined that the light blocking state of the light emitting element 22a is eliminated by the rotation of the winding drum 20 and the amount of sag is less than a predetermined amount (YES in step ST11), the winding drum 20 is stopped again. (Step ST12). Thereafter, the process returns to step ST8, and it is determined whether or not the rear end of the paper P has reached the first transport unit 11.

  If the amount of sag is not less than the predetermined amount (NO in step ST11), the process proceeds to step ST13 and the same determination as in step ST8 is performed. If the trailing edge of the paper has not reached the first transport unit 11 (NO in step ST13), the winding drum 20 continues to rotate and returns to step ST11 to monitor the sag amount again. On the other hand, if the trailing edge of the paper has reached the first transport unit 11 (YES in step ST13), the rotation of the take-up drum 20 is stopped (step ST14). FIG. 11 shows a state in which the take-up drum 20 is further rotated from the state of FIG. 10, but the clutch roller 214 is slipping because the pressure roller 21 is rotated by 210 ° or more.

  Control of rotation and stop of the take-up drum 20 as described above is performed based on the function of the drum rotation control means 44. Then, by detecting the amount of sag by the sag detection sensor 22 and performing rotation control of the winding drum 20 based on the amount of sag, the winding drum 20 is subjected to intermittent drive control that repeats rotation and stop. Become. The number of times this rotation and stop are repeated depends on the print size.

  When the rear end of the paper P reaches the first transport unit 11 and the rotation of the take-up drum 20 stops, the pair of nipping and transporting rollers 11a of the first transport unit 11 is brought into a pressure-bonded state from a non-pressure-bonded state by the pressure-bonding driving means 35a. (Step ST15). Then, as shown in FIG. 12, the first transport unit 11 is rotated 90 ° by the unit rotating means 35b to assume a vertical posture (step ST16). At this time, the transport surface of the first transport unit 11 and the transport surface of the second transport unit 12 are in a line. Next, the conveyance roller pair 11a is rotationally driven to convey the paper P toward the second conveyance unit 12, and deliver it (step ST17). At this time, the take-up drum 20 is rotated in the reverse direction (clockwise).

  As a result, the paper P sandwiched by the second transport unit 12 is transported upward, sent to a development processing section (not shown), and subjected to development processing. That is, the paper P is transported in a state where the front end side and the rear end side in the transport direction are switched between before the paper P is wound by the winding mechanism 8 and when it is transported by the second transport unit 12. Will be.

  When the delivery of the paper P to the second transport unit 12 as described above is completed, the paper P is set to an initial state to receive the next paper P. That is, the take-up drum mechanism 8 is raised from the second position to the first position, and the pressure roller 21 is also returned to the initial position so that the next paper P can be received. Further, the first transport unit 11 is also returned to the horizontal state, and the transport roller pair 11a is set in a non-pressing state.

  Here, in the above description, the transport method in the case where the length of the paper P in the transport direction is a print size equal to or larger than a predetermined value (for example, 594.1 mm, the first length) has been described. Is less than the predetermined value, the following two operations are performed according to the length.

  That is, when the transport direction length of the paper P is shorter than a predetermined length as in the service size (for example, when the length is shorter than 430.1 mm, the second length), the paper P is wound up by the winding drum 20. Since there is no need, the winding mechanism 8 is moved from the beginning to the second position. As a result, the paper P subjected to image exposure by the exposure engine 7 is immediately changed in direction by the first transport unit 11 and transferred to the second transport unit 12. As a result, the load applied to the paper P can be reduced more reliably.

  On the other hand, when the length of the paper P is a third length intermediate between the first length and the second length (430.1 to 594.1 mm in the example of the present embodiment), the winding mechanism 8 Only the winding operation by, and the movement of the winding mechanism 8 to the intermediate position (third position) between the first position and the second position are performed. That is, in step ST7 of FIG. 6A, the winding drum 20 is lowered to the intermediate position. At this time, in the case of the paper P of the third length, since there is no need to detect sag by the sag detection sensor 22, sag detection is not performed. Therefore, in FIG. 6A and FIG. 6B, the operation | movement except the step regarding a sagging detection is performed.

  As described above, according to the present embodiment, it is not necessary to provide a large space or a long conveyance path for the post-exposure buffer by providing the winding mechanism 8 for winding the paper P downstream of the exposure position from the exposure position. Therefore, it is possible to secure a post-exposure buffer that can sufficiently prevent exposure unevenness while reducing the size of the entire apparatus. And since the said winding mechanism 8 was comprised by the winding drum 20 and the press roller 21, and the conveyance direction front end side of the exposed paper P was clamped between both, long size (for example, 430.). Even when printing 1 mm or more), the long paper P can be taken up by the take-up drum 20 in a narrower space. Therefore, it is possible to perform long size printing without increasing the size of the entire apparatus.

  Further, if the pressure roller 21 is formed of an elastic material such as a foam material, when the paper P is sandwiched between the pressure roller 21 and the take-up drum 20, the pressure roller 21 is elastically deformed to form the paper P. The applied vibration and load fluctuation can be reduced. In particular, if it is made of a foam material such as urethane foam, it easily undergoes elastic deformation and the weight of the pressure roller 21 is reduced, so that the pressure roller has a great resistance against the paper P being conveyed. Therefore, vibrations and load fluctuations applied to the paper P can be greatly reduced.

  Furthermore, if the surface of the pressure roller is made low in friction, the resistance of the pressure roller relative to the paper P being conveyed is further reduced, so that vibrations and load fluctuations applied to the paper P can be further reduced. The occurrence of uneven exposure can be prevented more reliably.

(Other embodiments)
The configuration of the present invention is not limited to the above embodiment, and includes various other configurations. That is, in the above-described embodiment, in the case of a long paper, the paper P after exposure is wound up by the winding mechanism 8 including the winding drum 20 and the pressure roller 21, but not limited thereto. Only the transport direction of the paper P may be changed by sandwiching the front end side in the transport direction of the paper P between the winding drum 20 and the pressure roller 21.

  In the embodiment, the front end side in the transport direction of the paper P is sandwiched between the winding drum 20 and the pressure roller 21. However, the present invention is not limited to this, and the transport direction of the paper P during the exposure of the paper P is not limited thereto. Any structure other than the roller may be used as long as the front end side is sandwiched.

  In the above-described embodiment, the exposure engine using laser light as the image recording unit has been described. However, the present invention is not limited to this. For example, image exposure using a liquid crystal shutter or an inkjet printer may be used. Therefore, the image forming medium may also be paper made of not only a photographic material but also other materials.

  Furthermore, in the above-described embodiment, the paper trailing edge escape detection means 33b determines that the trailing edge of the paper P has escaped from the exposure position and has reached the first transport unit 11 based on the output signal from the paper detection sensor 10. However, the present invention is not limited to this, and a dedicated sensor may be provided in the first transport unit 11.

  As described above, the image forming apparatus according to the present invention has a sufficient post-exposure without enlarging the entire apparatus by sandwiching the leading end side of the paper in the conveyance direction with a pair of rollers for changing the conveyance direction. Since the buffer can be secured, it is particularly useful for an image forming apparatus for performing long printing, for example.

It is a fragmentary sectional view which shows the structure of the photographic processing system provided with the image forming apparatus. It is a figure which shows the structure of a storage space part. It is a detailed perspective view which shows the structure of a winding mechanism. It is sectional drawing which shows the cam mechanism which moves a pressurizing roller. FIG. 3 is a diagram illustrating a control block configuration of the image forming apparatus. 3 is a flowchart (first half) showing an operation of the image forming apparatus. 6 is a flowchart (second half) illustrating the operation of the image forming apparatus. FIG. 6 is a diagram illustrating an operation (part 1) of the image forming apparatus. FIG. 10 is a diagram illustrating an operation (No. 2) of the image forming apparatus. FIG. 10 is a diagram illustrating an operation (part 3) of the image forming apparatus. FIG. 10 is a diagram illustrating an operation (part 4) of the image forming apparatus. FIG. 10 is a diagram illustrating an operation (No. 5) of the image forming apparatus. FIG. 10 is a diagram illustrating an operation (No. 6) of the image forming apparatus. It is a figure which shows the structure of the image forming apparatus which concerns on a prior art.

Explanation of symbols

A Image forming apparatus S Accommodating space P Paper (image forming medium)
7 Exposure engine (image recording unit)
8 Winding mechanism 9a, 9b Exposure conveyance roller (conveyance mechanism)
11 First transport unit 12 Second transport unit 13 Winding movement mechanism 20 Winding drum (clamping member)
21 Pressure roller (clamping member)
33c Insertion detecting means 203 Cam member (clamping interval changing means)
203a Cam surface 210 Roller support shaft 211 Support shaft 212 Crimping member 215 Cam connecting shaft (clamping interval changing means)

Claims (5)

An image forming apparatus including an image recording unit that forms an image on an image forming surface while transporting an image forming medium by a transport mechanism,
A pair of sandwiching members disposed downstream of the image recording unit and sandwiching the image forming medium to change the transport direction;
An insertion determination means for determining that the front end side in the conveyance direction of the image forming medium is inserted a predetermined amount or more between the clamping members;
A clamping interval changing means for changing the interval between the clamping members,
The pair of sandwiching members are inserted a predetermined amount or more between the sandwiching members on the front end side in the transport direction of the image forming medium when an image is formed on an image forming medium having a predetermined length or more by the image recording unit. It is arranged in such a position,
When the insertion determining unit determines that the image forming medium has been inserted between the sandwiching members, the sandwiching interval changing unit narrows the interval between the sandwiching members so as to sandwich the front end side in the transport direction of the image forming medium. An image forming apparatus comprising: In claim 1,
An image forming apparatus characterized in that at least one of the pair of clamping members is provided with a buffering means for buffering an impact when gripping the front end side in the conveyance direction of the image forming medium. In claim 2,
The image forming apparatus characterized in that the buffer means is an outer peripheral portion of a clamping member made of an elastic member. In claim 3,
The image forming apparatus, wherein the elastic material is a foam material. In claim 2,
The image forming apparatus characterized in that the buffer means is a surface of a clamping member in a predetermined low friction state.

Images