Sheet guide mechanism for use in an imaging device

Abstract: In an apparatus utilizing a continuous-form material (10) having a plurality of perforations at predeter­ mined intervals of length, are provided a plate member (11) for guiding the material (10) discharged from the apparatus upwardly and connecting members (12, 14) on the plate member (11), as well as the apparatus, both adapted to be brought into and out of engagement with each other. Thus, the continuous-form material (10) discharged from the apparatus is bent at the perfora­ tions, falls beyond the plate member (11) and is neatly folded.

Description: The present invention relates to a sheet guide mechanism according to the generic part of claim 1. Recently widely used are imaging devices, such as laser printers in which the laser beam modulated in accordance with graphics, characters, and other image information scans a surface of an electrically charged sensitized body (for example, a photoconductive drum) for exposure to form electrostatic latent images which are then developed to a visible image which is then transferred and fixed to a duplication process (by the so-called electrophotographic process), to thereby obtain a hard copy of the image information on the continuous-form sheet. Especially small and less expensive apparatus using semiconductor lasers are vigorously commercialized. While such laser printers or similar image information apparatus sometimes use cut-sheet type recording material having a certain size, continuous-form material capable of being folded at predetermined intervals of length, so-called fan-folded sheet, are more often used to produce hard copies with image information consecutively at a high speed. The fan-folded sheet is used as such continuous-form material. The fan-folded sheet has sprocket holes provided along its length at certain intervals on both edges of the sheet width, with a widthwise extending perforation at each folding line spaced by a certain interval of length from each other. When using the continuous-form material such as fan-folded sheet, it is heated and pressed, i.e., thermally pressed by heat rollers as pat of a fixing unit of the imaging device. Thus folding lines at the perforations tend to disappear making folding operations difficult. Since the folding lines of the continuous-form material are thus eliminated by thermal pressing in the fixing process, which causes troubles in folding operations, the continuous-form material that should have been stacked in a neatly folded state after being discharged from the imaging device, is likely to be placed in a sort of mess around a discharge outlet. From GB-A-1 147 773 a sheet guide mechanism is known, which can also be used for an imaging device. This sheet guide mechanism guides a continuous form in such a way that the continuous form is stacked in front of the printing station. This enables an operator to reach the continuous form comfortably. The known device uses a back plate and a front plate to guide the continuous form. The continuous form is moved upwards through these two plates, turned over by a bent top portion in such a way that the continuous form is stacked folded. The two plates are necessary so that the continuous form can be held in an orderly manner. The top portion serves to trigger the folding process when the advanced continuous form touches the bent part of the top portion. Further, a sheet guide mechanism is known from US-A-2 534 391 where a continuous form, after passing over a platen of a typewriter, is refolded and deposited on an upper shelf. The front end of the continuous form is fed aroud the platen and is gripped between a bent-up portion of the shelf and the bent-in portion of a rear wall. In this manner the continuous form should automatically be folded on the shelf. From GB-A-1 530 046 there is known a fanfold paper transport of a thermal printer wherein the fanfold paper is confined with the sheets horizontal in a receptacle through the base of which a strip of paper is progressively withdrawn from the pack by a feed roll. The strip is directed upwardly through a first guide to a second guide that deflects the strip backwardly and downwardly into said receptacle, such that the strip automatically resumes the fanfolded configuration. The first guide extends vertically from a feed roll. The first guide is formed by a back plate and a front plate between which the paper strip is guided. From US-A-2,337,548 there is known a recording apparatus with a strip separator for optionally segregating one or more selected copies of a manifolded record assembly. At the sheet outlet of the recorder a guide being of arcuate shape is attached in order to guide the strip or a part of the strip to a locked storage compartment under the recorder. The guide consists of two interconnected relatively spaced members between which the strip is guided. It is an object of the invention to provide an improved sheet guide mechanism having a function capable of easily and reliably folding a continuous-form material after being discharged from the thermal pressure process of an imaging device. This problem is solved by the features of claim 1. The present invention is now described with reference to the accompanying drawings. Fig.1 is a side elevational view showing a general configuration of a laser printer incorporating one preferred embodiment of a sheet guide mechanism according to the invention, Fig. 2 is a partial perspective view showing a discharge operation of a continuous-form in the laser printer shown in Fig. 1; Fig. 3(A) is a disassembled perspective view of another emodiment; Fig. 3(B) is a vertical sectional view when the guide mechanism is mounted; Fig. 4(A) is an illustrative view of another embodiment; and Fig. 4(B) is a sectional view taken along a line IV-IV of Fig. 4(A), Fig. 1 is a side elevational view showing the general configuration of a laser printer incorporating one preferred embodiment of a sheet guide mechanism according to the invention, and Fig. 2 is a partial perspective view showing a discharge operation of a continuous-form sheet in the laser printer shown in Fig. 1. This laser printer prints out information, characters, numerals and the like corresponding to the codes stored in a host computer or the like on a continuous-form sheet 10 by means of the so-called electrophotographic process. Around a photoconductive drum 1 are situated a toner-cleaning station 2, a dc's charging station 3, a charging station 4, an optical scanning system 5 for leading a laser beam modulated according to the input information onto the circumferential surface of the photoconductive drum 1, a developing station 6 and a transferring station 7 arranged in the aforementioned order in the rotational direction of the photoconductive drum 1 (as indicated by an arrow C). A fixing station 8 is located in a predetermined position in the feeding direction of the continuous-form material 10. In the feed path for the continuous-form material 10 from the photoconductive drum 1 to the fixing station 8 is provided an inner guide mechanism 9 for guiding the continuous-form material 10 in a predetermined direction with a resisting force applied to both ends of the continuous-form sheet 10 to appropriately control its transporting operation. The surface of the photoconductive drum 1 is scanned by the laser beam emitted from the optical scanning system 5 in the longitudinal direction thereof (main scanning). While this main scanning is repeated, the photoconductive drum 1 is rotated in the direction indicated by the arrow C so that the surface thereof is scanned in the direction opposite to the rotation of the photoconductive drum (auxiliary scanning). In this arrangement, the photoconductive drum 1 has on its surface a latent image which is then developed to a visible image or toner image at the developing station 6. Formation of a latent image and development thereof is thus accomplished by the so-called electrophotographic process. The aforementioned toner image is then transferred from the photoconductive drum 1 to the surface of the continuous-form material 10. After fixing the transferred toner image at the fixing station 8, the continuous-form sheet 10 is now discharged through the sheet outlet P. The surface of the photoconductive drum 1 is cleaned at the toner-cleaning station 2 prior to such scanning (latent image formation) to remove the residual toner of the previous process, and is then electrically charged at the charge station 4 across the whole area thereof. The continuous-form material 10 is in continuous form to be folded at a predetermined interval of length, with consecutive sprocket holes formed on both edges of the sheet at a certain pitch. The folding line at which the material is folded at a predetermined interval has perforations to facilitate separating one section from another. The paper sections are thus torn apart after continuous printing in order to be put into a record file. Around the sheet outlet P for continuous-form material 10 a guide tray 11 is provided for controlling the direction in which material 10 is discharged. The guide tray 11 has a width slightly greater than the width of the material 10 with its both sides 11a and 11b bent in the same direction. The bent portions of the sides 11a and 11b are arranged opposite the sheet outlet P. One end of the tray is fixedly engaged with the underside of the outlet P so that the tray rises from the sheet outlet P obliquely toward some remote point. In this arrangement, due to the guide tray's 11 rising from the underside of the sheet outlet P toward some remote upper point, the continuous-form material 10 discharged from the sheet outlet P is guided toward some remote upper point and at a point where it leaves the top edge of the guide tray 11, it is bent downward by its weight at the perforation with a folding line to be folded at a certain interval. Thus, it falls upon a place beyond the tray 11 in a neatly folded state. To be more precise, due to the fact that the continuous-form material 10 is weaker at its perforations than at other parts, when guided by the upwardly projecting tray yields to its own weight so as to be always bent at the perforations. Even when the folding line at the perforation is eliminated by the heat press in the fixing process with the fixing station 8 making folding at the perforated line difficult, a lower rigidity at the perforation than in other parts is maintained anyway, so that the material is always bent at the perforations. This allows the material to fall on a place beyond the guide tray 11 in a neatly folded condition. The continuous-form material 10 is vibrated when it falls, as described above, beyond the guide tray 11. This vibration propagates to the sheet section of continuous-form material 10 already fallen beyond the guide tray 11. Such vibration of the continuous-form material 10 fallen beyond the guide tray 11 promotes its folding operation to further help it to be neatly folded. The continuous-form material 10 thus is always bent at the perforation and neatly folded by means of a simple structure only with a guide tray 11 provided at the paper outlet P. Another embodiment of the guide tray 11 will be described below with reference to Fig. 3 and Fig. 4. The guide tray 11 is, as shown in Fig. 3(A), provided at each side portion 11a or 11b with which it is mounted on the laser beam printer with a mounting projection 12 having a predetermined width, which has integrally formed therewith an engagement projection 12a at an outer leading end thereof. The bottom edge of the guide tray 11 extends downward to provide an engagement hook 13. The opening portion for installation, i.e., (the sheet outlet P), through which the guide tray 11 is mounted on the laser beam printer has at each of its lateral edges an engagement section 14 formed to allow engagement with the engagement projection 12a by a resilient deformation of the mounting projection 12. The hook 13 of the guide tray 11 is inserted into the opening portion (sheet outlet P) and is hooked on its bottom edge, with the engagement projection 12 pushed into the opening portion through the engagement section 14. The mounting projection 12 then yields to be deformed, allowing the engagement projection 12a to be entirely placed in the printer body. Thereafter, the mounting projection 12 is restored from its deformation, whereby the guide tray 11 is engaged and put into position as shown in Fig. 3(B). According to this arrangement, when an excessive force is inadvertently applied to the upwardly projecting guide tray 11 in an arrow-indicated direction, the guide tray 11 is slipped out of engagement, with no damage to the guide tray 11 itself. Illustrated in Fig. 4 is an opening portion 11b formed on the bottom of the guide tray 11 and a plurality of rib portions 11c formed on the inside surface of the guide tray 11 (the surface along which the continuous-form material 10 discharged from the printer body is guided in contact therewith). The continuous-form material 10 is thus guided along the top edges of the ribs 11c. In this arrangement, the continuous-form material 10 heated to a high temperature for thermal fixing in the fixing station 8 is rapidly cooled by the air flowing in the direction indicated by an arrow in the drawing, to thereby quickly finish the fixing process (cooling the continuous-form material 10 and solidifying a toner to be fixed on the surface of the continuous-form material 10) while also preventing curling of the continuous-form material 10.

Claims: Sheet guide mechanism for an imaging device utilizing a continuous form (10) having a plurality of perforations at predetermined intervals of length in the longitudinal direction of said continuous form (10), said guide mechanism comprising a plate member (11) arranged at an outlet side with a sheet outlet (P) of said imaging device to guide the continuous form (10) discharged from said device in an upward direction in such a way that, after leaving said plate member (11), it falls underneath said plate member in a fanfolded configuration, characterized in that the continuous form (10) is guided exclusively by the plate member (11) which extends obliquely to the vertical axis of gravity in such a way that the continuous form (10), after leaving the plate member (11), falls beyond the plate member (11) in said fanfolded configuration. Sheet guide mechanism according to claim 1 which further comprises an installing member including a first connecting member (12) provided on said plate member (11) and a second connecting member (14) provided on said device, both being adapted to be brought into and out of engagement with each other. Sheet guide mechanism according to claim 2 wherein said first connecting member (12) comprises mounting projections (12a) being provided at predetermined positions on the side edges (11a) of said plate member (11), and having projection portions integrally formed therewith and hook portions (13) formed at the bottom edge of said plate member (11), and wherein said second connecting member (14) comprises engagement portions provided on said device being adapted to be brought into and out of engagement with said projection portions (12a) and said hook portion. Sheet guide mechanism according to anyone of claims 1 to 3 which further comprises a plurality of hollow portions provided on said plate member (11). Sheet guide mechanism according to claim 4 wherein said hollow portions are provided in a predetermined area of the bottom side edge of said plate member (11). Sheet guide mechanism according to anyone of the foregoing claims wherein said plate member (11) includes a plurality of rib portions (11c) formed on a surface on which said continuous form (10) is travelled. Sheet guide mechanism according to claim 6 wherein said rib portions (11c) are arranged in parallel to a direction in which said continuous form (10) is travelled.

Inventors: KITA MASAHIRO, NEGISHI KIYOSHI, NEGNRO IKUO, KITA, MASAHIRO, NEGISHI, KIYOSHI, NEGORO, IKUO
Applicants: ASAHI OPTICAL CO LTD, ASAHI KOGAKU KOGYO KABUSHIKI KAISHA
Application year: 1989
Main classification: B65H23
IPC codes: B65H23