ROLL PAPER UNIT AND IMAGE FORMATION APPARATUS

Abstract: When a roll paper unit 200 is incorporated into an image formation apparatus, a second outlet guide member 92 is turned around a pivot 92a in the direction of an arrow G, i.e., moved from a position of solid lines to a position of two-dot chain lines, a rear end portion 92b of this second outlet guide member 92 pressing down a front end portion 80c of a guide member 80 to cause the guide member 80 to be turned around a central shaft 80d in the direction of an arrow H, i.e., moved from a position of solid lines to a position of two-dot chain line. Consequently, a path extending in the direction of an arrow C is closed, while a path extending in the direction of an arrow F is opened, the roll paper 72 being transferred in the paper feed direction. When the roll paper unit 200 is drawn out, the second outlet guide member 92 and the guide member 80 are tuned in the directions opposite to those mentioned above. Consequently, the path extending in the direction of the arrow F is closed, while the path extending in the direction of the arrow C is opened, the roll paper 72 being transferred in the paper discharge direction.

Description: TECHNICAL FIELD The present invention relates to a roll paper unit for holding a roll of paper, and an image formation apparatus equipped with the roll paper unit. BACKGROUND TECHNIQUE Ink-jet type image formation apparatuses for forming images by ink ejection on a printing medium, and electrophotography type image formation apparatuses for forming images by use of a developer on a printing medium are known as the output device of computers and workstations. Some of the image formation apparatuses are of the type which uses selectively cut paper sheets or roll paper as the printing medium. Some of them are of the type which uses roll paper only. An image formation apparatus which uses roll paper is usually equipped with a roll paper unit. The roll paper is cut in a prescribed size by a cutter provided in the roll paper unit, and the cut paper sheets are delivered to the image formation section in the apparatus to form images. This roll paper unit has several problems (inconveniences). A first problem is explained below. In formation of an image on the roll paper, the front end portion of the roll paper can be placed obliquely or be cut irregularly. To prevent the delivery failure or the defective image formation by the irregularity, after exchange of the paper roll or treatment of paper jamming, the front end portion of the roll paper is usually cut off and removed, and the front end of the roll paper is registered to be at the prescribed position. This operation is called precutting. After this precutting, the cut sheet of the roll paper is delivered to the image formation section to form an image on the paper sheet. Therefore, the roll paper unit has a paper discharge path for discharging the unnecessary precut paper piece, and a paper feed path for feeding the roll paper to the image formation section. The paper path is switched selectively for paper discharge or for paper feed, as necessary. The switching mechanism has a complicated construction owing to the necessary parts such as a solenoid. The image formation apparatus having the roll paper unit mounted in a demountable manner requires the operations of mounting the roll paper unit, precutting of the front end portion of the roll paper, and switching of the paper path for paper discharge or for paper feed, which are not simple. Additionally, a mechanism is necessary for removing the precut unnecessary paper piece from the paper discharge path. Thus, the structure is complicated. This is the first problem. As described above, the conventional roll paper unit has several problems. US 4218135 (Olympus Optical Co.) shows a roll paper unit or cassette loading apparatus in which a paper roll is presented to an image forming apparatus. The roll sheet cassette includes a front end portion in which a leading edge of the paper roll is mounted, and a leading edge precut to ensure appropriate presentation to the image forming machine. The roll sheet cassette loading apparatus described in US 4218135 (Olympus Optical Co.) suffers in particular the first two problems as outlined above. DISCLOSURE OF INVENTION In view of the above situations, the present invention intends to provide a paper roll unit and an image formation apparatus having a relatively simple structure and is readily handleable. A first embodiment of the roll paper unit of the present invention for solving the aforementioned first problem constitutes an image formation apparatus which has an image formation section for forming an image on roll paper, conducts precutting of a front end portion of the roll paper, and feeds the roll paper having been cut at the front end portion in a prescribed feed direction to the image formation section, the roll paper unit (1) being incorporated demountably into the image formation apparatus, and (2) having a switching member for switching a paper delivery path to a direction for discharging the roll paper when the unit is demounted whereby precutting of the front of the front end portion is conducted in use, and switching the paper delivery path to another direction for feeding the roll paper when the unit is incorporated into the image formation apparatus whereby that roll paper can be presented to the image formation section. The roll paper unit may have (3) a constitution such that the front end portion of the roll paper to be precut is drawn out of the image formation apparatus when the roll paper unit is incorporated into the image formation apparatus. Further, the roll paper unit may have (4) a cutter for precutting the roll paper at the prescribed paper discharge path when the roll paper unit is incorporated into the image formation apparatus. The switching member may have (5) a plate-shaped guide member which switches over a roll paper guiding face to a front side or to a reverse side corresponding to the demounted state or the incorporated state of the roll paper unit. The plate-shaped guide member may have (6) a protrusion for guiding the roll paper on at least one of the front face and the reverse face. A first embodiment of the image formation apparatus of the present invention is characterised by (7) the roll paper unit described in the above items (1) to (6), (8) the roll paper unit having a roll paper cover for covering the roll paper unit, and (9) a slit formed between an outside cover and the roll paper cover for discharging the precut front end portion of the roll paper. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an outside appearance of a copying machine equipped with a roll paper unit of one embodiment of the present invention. Fig. 2 is a schematic drawing of showing roughly the internal structure of the copying machine shown in Fig. 1. Fig. 3 is a schematic drawing of a roll paper unit demounted from the main body of the copying machine shown in Fig. 1. Fig. 4 is a schematic drawing of a roll paper unit incorporated into the main body of the copying machine shown in Fig. 1. Fig. 5 is a perspective view of a press roller separated from a paper feed roller. Fig. 6 is an enlarged schematic drawing of a part of the roll paper unit. Fig. 7 is a perspective view of a part of the upper face of a guide plate. BEST MODE FOR PRACTICING THE INVENTION The modes of practicing the present invention is described by reference to drawings. Fig. 1 is a perspective external view of a copying machine having an embodiment of a roll paper unit incorporated therein. On the top face of copying machine 10 (an example of the image formation apparatus in the present invention), there is placed an openable document table cover 12. The document table cover 12 also serves as a document feeder (DF) for feeding a source document to the document table. At the front side of the top face, operation panel 14 is placed for inputting the number of reproduced copies, and so forth. This copying machine 10 is capable of forming an image selectively either on a cut paper sheet or on roll paper. This copying machine has four cassettes 16,18,20,22 which store respectively cut paper sheets and are demountable from the main body of copying machine 10. Additionally, the copying machine has roll paper unit 70 which is demountable from copying machine 70. Further, copying machine 10 has manual feed tray 23 for feeding a smaller size of recording paper such as a post card. The copying machine has discharged-paper tray 25 also for holding recording paper sheets after image formation. The process for formation of an image with copying machine 10 of Fig. 1 is explained below by reference to Fig. 2. Fig. 2 is a schematic drawing showing roughly the internal structure of copying machine 10. Document-supporting glass plate 24 is placed under document table cover 12 (see Fig. 1). A light-exposure optical system is provided below document-supporting glass plate 24 to illuminate the source document to obtain signal carrying image information. This light-exposure optical system includes light source 26, lens 28, mirrors 30,32,34,36,38,40. A source document placed on document-supporting glass plate 24 is exposed to light from light source 26, and reflected light 42 from the source document is projected as image signals through lens 28, and mirrors 30,32,34,36,38,40 to photosensitive drum 44 placed below the light-exposure optical system. Photosensitive drum 44 has a rotation shaft 44a in the direction vertical to the drawing paper face, rotating in the direction shown by an arrow A. A primary electrifier 46 is provided on the upstream side, in the rotation direction, of photosensitive drum 44 from the position of projection of light reflected by the source document to electrify uniformly photosensitive drum 44. After photosensitive drum 44 is electrified uniformly by primary electrifier 46 to form an electrification face, an electrostatic latent image is formed by illumination of reflected light 42 from the source document. Development device 48 is provided on the downstream side of the above illumination position in the rotation direction of photosensitive drum 44 to develop the electrostatic latent image. The region where photosensitive drum 44 and development 48 device are counterposed is the development region for developing the electrostatic latent image. On arrival of the electrostatic latent image at the development region with rotation of photosensitive drum 44, the electrostatic latent image is developed by development device 48 to form a toner image (developed image). Transfer electrifier 50 is provided on the downstream side of the development region in the rotation direction of photosensitive drum 44 to transfer the toner image onto a recording paper. The region where photosensitive drum 44 and transfer electrifier 50 are counterposed is a transfer region for transferring the toner image onto the recording paper sheet. On arrival of the toner image at the transfer region by rotation of photosensitive drum 44, the toner image is transferred onto the recording paper sheet delivered to the transfer region. The recording paper is delivered from cassette 16,18,20,22 or roll paper unit 70 to the transfer region. For delivery of the recording paper to the transfer region, for example, a cut paper sheet is sent out from cassette 16 by paper feed roller 16b, and the front end of the cut paper sheet 16a is kept in contact with registration rollers 54a,54b to form a loop. The recording paper sheet is delivered to meet the timing of arrival of the toner image at the transfer region. Cut paper sheet 18a stored in cassette 18 is delivered by paper feed roller 18b, and a pair of delivery rollers 53a,53b to registration rollers 54a,54b. Cut paper sheet 20a stored in cassette 20 is delivered by paper feed roller 20b, a pair of delivery rollers 20c,20d, and a pair of delivery rollers 53a,53b to registration rollers 54a,54b. Cut paper sheet 22a stored in cassette 22 is delivered by paper feed roller 22b, a pair of delivery rollers 22c,22d, a pair of delivery rollers 20c,20d, and a pair of delivery rollers 53a,53b to registration rollers 54a,54b. The recording paper sheet having received the transferred toner image is separated by separation electrifier 56 from photosensitive drum 44, and is delivered by delivery belt 58 rotating in the arrow-B direction to fixation device 60. By this fixation device 60, the toner image is fixed on the recording paper sheet. After the toner image fixation, the recording paper sheet is discharged through a paper outlet (not shown in the drawing) onto discharged paper tray 25. The toner remaining on photosensitive drum 44 after the image transfer is removed by cleaning device 64 from photosensitive drum 44. The residual electric charge remaining on photosensitive drum 44 is eliminated by a destaticizing lamp (not shown in the drawing). Thus the photosensitive drum 44 is ready for next image formation. Roll paper unit 70 is explained by reference to Figs. 3, 4, and 5. Fig. 3 is a schematic drawing of roll paper unit 70 demounted from the main body of copying machine 10. Fig. 4 is a schematic view of roll paper unit 70 incorporated into the main body of copying machine 10. In these drawings, the same symbols are used as in Fig. 2 for the corresponding constitution elements. Roll paper 72 set on spool 74 is placed in roll unit 70 with the both ends of the spool held rotatably by spool holder 76. As shown in Fig. 3, in a state of roll paper unit 70 demounted from the main body of copying machine 10 (an example of a demounted state), roll paper 72 is guided by cutter lower blade guide 78, face 80a (see Fig. 6) of guide plate 80 (an example of the plate-shaped guide member in the present invention), and upper stay 82 to the paper discharge direction (shown by an arrow C) which are provided above roll paper 72. In this state, press roller 84 and paper feed roller (driving roller) 86 for delivering roll paper 72 are kept apart from each other. Also in this state, guide plate 66 in the main body is opened, and delivery rollers 53a,53b which deliver cut paper 18a, or the like from cassette 18, 20, or 22 (cassettes 20 and 22 are not shown in Fig. 3) are apart from each other. For setting roll paper 72 in roll paper unit 70, firstly roll paper cover 106 is opened, and spool 74 carrying roll paper 72 is fit to spool holder 76. Then paper pressing lever 120 is pulled to move press roller 84 upward for release to give an insertion space for inserting the front end of roll paper 72. The front end of the roll paper 72 is inserted into this insertion space and is delivered through surface 80a of guide plate 80 to top of upper stay 82. Then roll paper 72 is registered to prevent oblique movement thereof. Specifically, the front end portion of roll paper 72 is pulled out in a length of about 300 mm, and the right and left edges of roll paper 72 are put on the both ends of the guide plate. After this registration, the paper pressing lever 120 is restored to press the roll paper 72 by press roller 84 against paper feed roller 86 to fix the position of roll paper 72. The front end portion of the roll paper pulled out for the registration is brought outside, and roll cover 106 is closed. Protrusion 106e is provided on roll paper cover 106 to ensure restoration of paper pressing lever and to prevent failure of deliver of roll paper by press roller 84 and paper feed roller 86. Accordingly, if roll cover 106 is closed without restoring paper pressing lever 120, protrusion 106e pushes paper pressing lever 120 to restore it. In such a manner, roll paper unit 70 with roll paper cover 106 closed is incorporated into the main body of copying machine 10. Usually, the thickness of roll paper 72 is less than 0.5 mm. Therefore, the front portion of roll paper 72 can be discharged through the slit formed in a size of about 1 mm between roll cover 106 and outer cover 10a, so that a separate opening need not be provided additionally for discharging the font end portion of roll paper 72. When precut sensor 101 fixed on stay 10b of copying machine 10 detects roll paper 72 brought to the position on upper stay 82 (an example of the paper discharge path in the present invention), a cutter-driving motor (not shown in the drawing) is turned on to drive cutter 100 to cut roll paper by crossing the roll paper. The end of the cut portion of roll paper 72 (precut paper piece), which is outside the main body of copying machine 10, can readily be removed by the operator. Therefore, a precut paper discharge mechanism need not be provided in copying machine 10, thereby the structure being made simpler. Press roller 84 is explained regarding its operation and construction. Fig. 5 is a perspective view of press roller 84 separated from paper feed roller 86. Paper feed roller 86 is fixed rotatably to the main body of roll paper unit 70, and is driven by a motor (not shown in the drawing). Paper feed roller 86 is fixed to expose a part of the roller through opening 110a of guide plate 110 for guiding roll paper 72 upward to a lateral direction (toward the image formation section). On the other hand, press roller 84 is supported rotatably by plate spring 114. This plate spring 114 is fixed at the other end by upper guide plate 116 fixed above lower cutter blade guide 78. Therefore, press roller 84 is normally pressed by plate spring 114 against paper feed roller 86. Plate spring 114 has hook 114a rising upward from the upper face thereof. The tip portion of this hook 114a is folded. Onto the upper face of upper guide plate 116, turn plate 122 is fixed such that the tip portion 122a thereof turns vertically by operation of paper feed press lever 120. The tip portion 122a has an opening 122b, through which the tip of hook 114a protrudes. At the rear end portion of turn plate 122, plural nail-shaped protrusions 122c are formed. On the upper face of upper guide plate 116, holes 116a are formed for insertion of protrusions 122c. By insertion of protrusions 122c into holes 116a, turn plate 122 is made turnable around the rear end portion thereof. Paper pressing lever 120 is fixed to be turnable around pivot 120a. At a portion of paper pressing lever 120 near pivot 120a, plate-shaped contact portion 120b is provided. This contact portion 120b is positioned at the rear bottom side of turn plate 122. When paper pressing lever 120 is at position 120' shown by a solid line, turn plate 122 takes the position shown by the solid line by gravity. When the paper pressing lever is turned around pivot 120a to the position indicted by the two-dot chain line 120 to release press roller 84, the contact portion 120b is also turned to allow turn plate 122 to turn around protrusions 122c at the rear end. When turn plate 122 is turned to lift tip portion 122a of turn plate 122, hook 114a of plate spring 114 is caught around opening 122b to lift hook 114a. With the upward movement of hook 114 lifted, plate spring 114 is also lifted to lift press roller 84 to the position of press roll 84' indicated by the two-dot chain line. Thereby, press roller 84 is disengaged from paper feed roller 86. As mentioned above, press roller 84 and paper feed roller 86 are readily disengaged by turning the paper pressing lever 120 with a simple constitution with high operability at a low cost. In Fig. 5, the two-dot chain line C indicates the path of delivery of roll paper 72 to be precut. On the other hand, when roll paper unit 70 of Fig. 3 is pushed in the arrow-D direction incorporation into the main body of copying machine 10 as shown in Fig. 4 (an example of the incorporation state in the present invention), guide plate 66 of the main body is turned around pivot 66a in the arrow-E direction for closure. At the top end portion of main body guide plate 66, first outlet guide plate 67 is provided which extends obliquely downward and outward. As described later by reference to Fig. 6, on incorporation of roll paper unit 70 into the main body of copying machine 10, second outlet guide plate 92 is forced to turn by contact with first outlet guide plate 67, and guide plate 80 also is also turned thereby. Consequently, roll paper 72 is lead through cutter lower blade guide 78 placed above roll paper 72, back face 80b of guide plate 80 (see Fig. 6), and swing guide 87 in a paper delivery direction (arrow-F direction) to be held between press roller 88 and curl-taking roller (driving roller) 90. Press roller 88 is made of a metal, and curl-taking roller 90 has a peripheral face made of a sponge. In this state of incorporation, press roller 84 and paper feed roller 86 (driving roller) for delivering roll paper 72 are in contact with each other, and by driving paper feed roller 86 and curl-taking roller 90, roll paper 72 is delivered in the paper feed direction. The movement and function of guide plate 80 is explained by reference to Fig. 6. Fig. 6 is an enlarged schematic drawing of a part of roll paper unit 70, in which the same symbols and numerals are used as in Figs. 3 and 4 for the corresponding constitution elements. Since the respective constituting elements are shown schematically with enlargement in Fig. 6, some of the constituting elements are shown in somewhat different shape from Figs. 3 and 4. When roll paper unit 70 is incorporated into the main body of copying machine 10, main body guide plate 66 is closed, and first outlet guide plate 67 and second outlet guide plate 92 are in contact with each other. Thereby, second outlet guide plate 92 is forced to turn around pivot 92a in the arrow-G direction to the position shown by two-dot chain line. Second outlet guide plate 92 presses down, by rear end portion 92b thereof, tip portion 80c of guide plate 80, whereby guide plate 80 at the position shown by a solid line is turned around central shaft 80d in the arrow-H direction to the position shown by the two-dot chain line. Thus the path shown by the arrow C is closed, and the path shown by the arrow F is opened to deliver roll paper 72 in the paper feed direction. Second outlet guide plate 92 is energized by a coil spring (not shown in the drawing) to turn counterclockwise in the drawing paper face of Fig. 6. Guide plate 80 is also energized by a coil spring (not shown in the drawing) to turn clockwise in the drawing paper face of Fig. 6. Thereby, when roll paper unit 70 is demounted from the main body of copying machine 10, second outlet guide plate 92 and guide plate 80 turn in the direction reverse to that mentioned above to close the path of the arrow-F direction and to open the path of the arrow-C direction, whereby roll paper 72 is delivered to the discharge direction. In this embodiment, guide plate 80 and second outlet guide plate 92 constitute the switching member as called in the present invention. In the state in which the path in the arrow-F direction is open, protrusion 92c of second outlet guide plate 92 is actually in contact with guide plate 80. In Fig. 6, however, protrusion 92c is shown to be apart from guide plate 80 to demonstrate clearly the movement of guide plate 80 and second outlet guide plate 92. Cutter 100 is provided for cutting roll paper 72 near cutter lower blade guide 78 in the downstream side thereof. This cutter 100 is ordinarily placed in a waiting position apart from the both ends in the breadth direction of roll paper 72 not to hinder the passage of roll paper 72. In roll paper unit 70, cutter 100 is constituted to move in the direction perpendicular to the drawing paper face of Fig. 6 to cut roll paper 72 when roll unit 70 is incorporated into copying machine 10 with roll paper 72 extending in the paper discharge direction (arrow-C direction). The position of movement of cutter 100 is the prescribed cutting position in the present invention. The font end portion of roll paper 72 having been cut by cutter 100 is discharged through discharge outlet 102 as shown in Fig. 4. The shape of the surface 80a of guide plate 80 is explained by reference to Fig. 7. Fig. 7 is a perspective view of a part of upper face 80a of guide plate 80. Guide plate 80 has many protrusions 81 at a prescribed intervals on the face 80a from the middle portion to the front side (downstream side in paper discharge direction). Face 80a of guide plate 80 is in a wave shape. This guide plate 80 guides roll paper 72 in the paper discharge direction to the tops of protrusions 81. Thereby, the delivery direction can be switched selectively to the paper discharge direction or to the paper feed direction at a smaller turning angle of guide plate 80. The smaller turning angle of the guide plate saves the space. Instead of protrusions 81, guide plate 80 may made thicker. POSSIBILITY IN INDUSTRIAL APPLICATION As described above, in the first embodiment of the roll paper unit of the present invention, the switching member switches the roll paper delivery path to the paper discharge direction or to the paper feed direction in correspondence with the state of the roll paper unit, demounted or incorporated. Thus, the roll paper delivery direction is switched corresponding to the state of the roll paper unit. Therefore, the roll paper unit is simple in construction, and is easy in handling. In the roll paper unit incorporated into the image formation apparatus, in which the front end portion of the roll paper is led out of the image formation apparatus, the front end portion of the roll paper can be removed readily. This type of roll paper unit is more readily handleable. In the roll paper unit incorporated into the image formation apparatus, in which a cutter for precutting roll paper is provided, the roll paper is precut automatically when the roll paper is lead to paper discharge path, the roll paper is precut automatically. This type of roll paper unit is less laborious in operation. Further, in the roll paper unit in which the switching member turns in prescribed directions corresponding to the state of the unit, demounted or incorporated, to change the roll paper guiding face of the plate-shaped guide member to the front face side or to the reverse face side, the roll paper guiding face is changed only by turning the guide member, whereby the construction is simplified. The protrusions formed on at least one of the front face and the reverse face of the plate-shaped guide member for guiding the roll paper enables smaller the thickness of the plate-shaped member. The first embodiment of the image formation apparatus of the present invention has the above roll paper unit comprising a roll paper cover. Through a slit provided between the roll paper cover and the outside cover of the image formation apparatus, the precut portion of the front end of the roll paper is discharged without providing an additional outlet opening for paper discharge.

Claims: A roll paper unit (70) constituting an image formation apparatus (10) which has an image formation section for forming an image on roll paper (72), conducts precutting of a front end portion of the roll paper (72), and feeds the roll paper (72) having been cut at the front end portion in a prescribed feed direction to the image formation section, the roll paper unit (70) being incorporated demountably into the image formation apparatus (10), and characterised in that a switching member (80) is provided for switching a paper delivery path to a direction for discharging the roll paper (72) when the roll paper unit (70) is demounted whereby precutting of the front end portion is conducted in use, and switching the paper delivery path to another direction for feeding the roll paper (72) when the roll paper unit (70) is incorporated into the image formation apparatus (10) whereby that roll paper can be presented to the image formation section. The roll paper unit according to claim 1, wherein the front end portion of the roll paper to be precut is drawn out of the image formation apparatus (70) when the roll paper unit (70) is incorporated into the image formation apparatus (10). The roll paper unit according to claim 1 or 2, wherein the roll paper unit (70) has a cutter for precutting the roll paper (72) at a prescribed paper discharge path when the roll paper unit (70) is incorporated into the image formation apparatus (10). The roll paper unit according to claim 1 or 2, wherein the switching member (80) has a plate-shape guide member which switches over a roll paper (72) guiding face to a front side or to a reverse side corresponding to the demounted state or the incorporated state of the roll paper unit (70). The roll paper unit according to any of claim 1 to 4, wherein the plate-shaped guide member (80) has a protrusion for guiding the roll paper (72) on at least one of the front face (80a) and the reverse face (80b) thereof. An image formation apparatus 10 comprising the roll paper unit 70 set forth in any of claims 1 to 5, the roll paper unit 70 having a roll paper cover 106 for covering the roll paper unit 70, and a slit being formed between an outside cover 12 and the roll paper cover 106 for discharging the precut front end portion of the roll paper 72.

Inventors: SAWADA YASUSHI, SAWADA, YASUSHI
Applicants: CANON FINETECH INC, CANON FINETECH INC.
Application year: 1998
Main classification: B65H16
IPC codes: B41J13, B65H23, B41J11, B65H16, G03G15, B41J15