Manual sheet feed apparatus

Abstract: The sheet- receiving plate (2) slides in a forward-backward direction upon pivotal movement of the sheet feed plate (1). The sheet-receiving plate includes a separating member (12) which is brought into contact with a cassette pickup roller (10) to sepa­ rate a sheet of paper (5) picked up by a manual feed pickup roller (6) upon forward movement of the sheet-receiving plate, and a slip piece (13) which slips into a space below the cas­ sette pickup roller. The separating member is constituted by an elastic member.

Description: The present invention relates to a manual by operable paper feed apparatus incorporated in an image forming apparatus such as an electrophotographic copying machine. In a copy paper feeding device for an electrophotographic copying machine which can be used alternatively for automatic feeding of paper sheets from a cassette store in the machine or for manually feeding paper sheets it is known (US-A-4 579 328) to use a leaf spring for retaining the paper sheets in the cassette as long as paper sheets are manually fed as substrates for developed toner images. In a known electrophotographic copying machine as a typical image forming apparatus, cassettes loaded in the apparatus each store a plurality of recording sheets of different sizes. A document image is recorded on a recording sheet having a size selected by a user, or a recording sheet which is automatically selected in accordance with the document size. Another known copying machine can record a document image on a recording sheet having a size different from the sizes of recording sheets stored in a cassette. In this copying machine, a recording sheet having a desired size can be manually inserted from a predetermined insertion port without exchanging cassettes, and a document image can be recorded on the inserted recording sheet. An apparatus used for such an operation is called a manual by operable paper feed apparatus. Figs. 1 to 3 show a conventional known manual by operable paper feed apparatus (JP-A-61-174 049, which corresponds to the preamble of claim 1). Fig. 1 shows the state wherein a sheet of paper is fed from a cassette. Fig. 2 shows the state wherein a sheet of paper is manually fed. Referring to Figs. 1 and 2, a pivotal paper feed plate 1 and a paper-receiving plate 2 designed to slide in a front-rear direction upon pivotal movement of the pivotal paper feed plate 1 are provided. When the pivotal paper feed plate 1 is pivoted up on a support shaft 3, a proximal hook portion 2a is locked by a lock portion 1a of the plate 1, and the paper-receiving plate 2 is moved backward, as shown in Fig. 1. When the pivotal paper feed plate 1 is pivoted down, as shown in Fig. 2, the paper-receiving plate 2 is pushed by a press portion 1b and is moved forward. During this forward movement, the paper-receiving plate 2 and the pivotal paper feed plate 1 constitute a continuous inclined surface. With a paper end regulating step 4 the leading end of a manually-fed sheet 5 is brought into contact. When the paper-receiving plate 2 is moved forward, the step 4 is moved to a position under a manual feed pickup roller 6 (for paper to be manually fed). A push-up plate 7 urges the manually-fed sheet 5 stacked on the paper-receiving plate 2 against the pickup roller 6 via a through hole 2b. During the forward movement of the paper-receiving plate 2, the push-up plate 7 protrudes from the upper surface of the plate 2 via the through hole 2b. During the backward movement of the paper-receiving plate 2, the push-up plate 7 retreats below the plate 2. The apparatus comprises a paper feed cassette 8, a stack 9 of sheets of paper in the cassette 8, a cassette pickup roller 10 for paper to be fed from the cassette 8, a push-up plate 11 for urging the stack 9 against the pickup roller 10, a separating member 12 which is brought into contact with the pickup roller 10 upon forward movement of the paper-receiving plate 2, a slip piece 13 which slips under the pickup roller 10, a separating roller unit 14 and a second pickup roller pair 15. In the above-described arrangement, when the pivotal paper feed plate 1 is in a vertical position as shown in Fig. 1, the sheets of the stack 9 in the paper feed cassette 8 are pushed up by the push-up plate 11 and are picked up by the pickup roller 10 which is in contact therewith. The sheets are separated by the separating roller unit 14, which is located at a front position, one by one so as to be fed to the second pickup roller pair 15. When the pivotal paper feed plate 1 is pivoted down, and the paper-receiving plate 2 is moved forward, as shown in Fig. 2, the separating member 12 is brought into contact with the pickup roller 10, and the slip piece 13 slips into a space below the pickup roller 10. With this movement, the pickup roller 10 is insulated from the sheets of the stack 9 in the cassette. Therefore, if the manually-fed sheet 5 is set on the paper-receiving plate 2, the sheet 5 is picked up by the pickup roller 6. The sheet 5 is preliminarily separated by the pickup roller 10 and the separating member 12 and is finally separated by the separating roller unit 14 so as to be fed to the second pickup roller pair 15. In the above-described manual paper feed apparatus, however, the separating member 12 is formed by directly bonding a friction member (e.g., a rubber material) to the upper surface of the paper-receiving plate 2. Therefore, when the paper feed cassette 8 is loaded, a large push-up force (arrow A) is applied to the slip piece 13 by the push-up plate 11 as shown in Fig. 3. As a result, the separating member 12 is urged against the pickup roller 10 with excessive pressure (arrow B), and manual paper feed may not be performed. The present invention has been made to solve the above-described problem, and has as its object to provide a manual by operable paper feed apparatus which can prevent a separating member from being urged against a cassette pickup roller with excessive pressure even if a large push-up force is applied to a slip piece under the pickup roller by a push-up plate while a paper feed cassette is loaded. In order to achieve the above object, according to the present invention, there is provided a manual by operable sheet feed apparatus, comprising a pivotal sheet feed plate and a sheet-receiving plate which slides in a forward-backward direction upon pivotal movement of the sheet feed plate, the sheet-receiving plate including a separating member which is brought into contact with a cassette pickup roller to separate a sheet of paper to be picked up by a manual feed pickup roller upon forward movement of the sheet-receiving plate, and a slip piece which slips into a space below the cassette pickup roller, wherein the separating member is an elastic leaf spring member which is fixed to the sheet-receiving plate and which is flexibly bendable upon coming in contact with the cassette pickup roller. With this arrangement, the urging force generated between the separating member and the cassette pickup roller can be reduced without degrading the separating performance. In the drawings Fig. 1 is a schematic view showing the main part of a conventional manual by operable paper feed apparatus with a sheet of paper being fed from its cassette, Fig. 2 is a schematic view showing the main part of the conventional manual by operable paper feed apparatus of Fig. 1 with a sheet of paper being manually fed, Fig. 3 is an enlarged sectional view showing the separating member of the conventional manual by operable paper feed apparatus of Fig. 1, Fig. 4 is a perspective view showing the main part of an embodiment of a separating mechanism for manual paper feed in a manual by operable paper feed apparatus of the present invention, Fig. 5 is an exploded perspective view of the main part of the separating mechanism shown in Fig. 4, Fig. 6 is an enlarged sectional view showing the state when the separating member is urged against a cassette pickup roller in the manual by operable paper feed apparatus of the present invention, Fig. 7 is a sectional view for explaining the manual paper feed operation of the manual by operable paper feed apparatus of the present invention, Fig. 8 is a perspective view showing the main part of another embodiment of the separating mechanism for manual paper feed in the manual by operable paper feed apparatus of the present invention, and Fig. 9 is a perspective view showing the main part of still another embodiment of the separating mechanism used for the manual by operable paper feed apparatus of the present invention. Embodiments of the present invention will be described below. Figs. 4 and 5 show a separating mechanism for manual paper feed in a manual paper feed apparatus according to an embodiment of the present invention. In this embodiment, a separating member 12 is constituted by a leaf spring member 21 and a friction member 22 bonded to its upper surface. The leaf spring member 21 can be realized by a stainless steel (SUS) plate or a phosphor bronze plate. However, the present invention is not limited to this. A proximal end portion 21a of the leaf spring member 21 is attached to a crossbar portion 201 crossing a through hole 2b of a paper-receiving plate 2. A free end side 21a' of the leaf spring member 21 can easily deform elastically in the through hole 2b. The leaf spring member 21 may be detachably mounted or integrally fixed on the paper-receiving plate 2. In the former case (detachable mounting), as shown in Figs. 4 and 5, a U-shaped portion is formed on the proximal end portion 21a of the leaf spring member 21 so as to be fitted on the rear edge portion of the crossbar portion 201 of the paper-receiving plate 2. At the same time, lock pawls 21b and 21c extending forward from both sides of the proximal end portion 21a are respectively locked in receiving holes 202 and 203 formed in the crossbar portion 201. In addition, as shown in Fig. 8, both side portions of the proximal end portion of the leaf spring member 21 may be fixed to the crossbar portion 201 of the paper-receiving plate 2 by screws 204, so that the leaf spring member 21 can be detached from the paper-receiving plate 2 by unfastening the screws 204. In the latter case (integral fixing), as shown in Fig. 9, the proximal end portion 21a of the leaf spring member 21 may be fixed to the crossbar portion 201 of the paper-receiving plate 2 by using a metal adhesive agent, brazing, or other means (e.g., a mechanical coupling means). The friction member 22 is formed by mixing cork particles with urethane rubber. However, a friction member may be selected from other friction materials having high friction coefficients. The friction member 22 is normally bonded to the leaf spring member 21 by using an adhesive agent. However, the friction member 22 may be molded/bonded to the leaf spring member 21 by insert molding. In addition, other proper methods may be employed. When the pivotal paper feed plate 1 is pivoted down to advance the paper-receiving plate 2, and the paper end regulating step 4 of the paper-receiving plate 2 is moved to a position under the manual feed pickup roller 6, the slip piece 13 at the distal end of the paper-receiving plate 2 slips into a space below the cassette pickup roller 10 so as to insulate the pickup roller 10 from the stack 9 of sheets in the cassette 8 and to urge the separating member 12 against the pickup roller 10. If the paper feed cassette 8 is loaded and a large push-up force A is applied to the slip piece 13 under the pickup roller 10 in the above-described state, the separating member 12 is urged against the pickup roller 10 with a large force. In this case, however, since the push-up force A is divided into forces C and D (Fig. 7) due to the effect of the leaf spring member 21 having the proximal end portion fixed to the crossbar portion 201 of the paper-receiving plate 2 while a sheet 5 to be manually inserted is separated, the separating member 12 is free from a state wherein paper feed cannot be performed. As has been described above, according to the present invention, the separating member, which is arranged in contact with the pickup roller so as to separate sheets of paper picked up by the manual feed pickup roller 6, is constituted by an elastic member. With this arrangement, a proper separating pressure can always be obtained without excessively increasing the urging pressure between the separating member and the cassette pickup roller 10 during a paper separating operation.

Claims: Manually operable sheet feed apparatus, comprising a pivotal sheet feed plate (1) and a sheet-receiving plate (2) which slides in a forward-backward direction upon pivotal movement of said sheet feed plate (1), said sheet-receiving plate (2) including a separating member which is brought into contact with a cassette pickup roller (10) to separate a sheet (5) of paper to be picked up by a manual feed pickup roller (6) upon forward movement of said sheet-receiving plate (2), and a slip piece (13) which slips into a space below the cassette pickup roller (10), characterized in that the separating member is an elastic leaf spring member (21) which is fixed to the sheet-receiving plate (2) and which is flexibly bendable upon coming in contact with the cassette pickup roller (10). Apparatus as claimed in claim 1, characterized in that a friction member (22) is mounted on the leaf spring member (21). Apparatus as claimed in claim 1 or 2, characterized in that the leaf spring member (21) is detachably mounted on the sheet-receiving plate (2). Apparatus as claimed in one of claims 1 to 3, characterized in that the leaf spring member (21) is a plate made of stainless steel. Apparatus as claimed in claim 2, characterized in that the friction member (22) is made of a mixture of cork particles with urethane rubber. Apparatus as claimed in claim 2 or 5, characterized in that the friction member (22) is bonded to the leaf spring member (21) by insert molding.

Inventors: OKAYAMA KENICHI C O KONICA COR, SHIBATA AKIHIRO C O KONICA COR, OKAYAMA, KENICHI, C/O KONICA CORPORATION, SHIBATA, AKIHIRO, C/O KONICA CORPORATION
Applicants: KONISHIROKU PHOTO IND, KONICA CORPORATION
Application year: 1990
Main classification: B65H3
IPC codes: B65H5