GB2129404A - Sliding drawer assembly - Google Patents

Abstract

A drawer assembly includes a drawer (1) slideably mounted on a frame, and a locating tab (61) for positively locating the drawer in its home position. The locating tab is preferably kite-shaped, having narrower leading and trailing portions (62, 63) and a wider intermediate portion (64), and extends rearwardly from the drawer in the direction of sliding movement of the drawer. A tab-receiving arrangement on the drawer frame comprises two rollers that are spring-urged towards one another, and sensing means operated by the tab to supply a signal to indicate that the drawer is in its home position. Once the intermediate portion (64) of the tab has passed the rollers of the tab-receiving arrangement, the drawer is positively pulled into its home position. The assembly is particularly applicable for copy sheet trays in a xerographic copier. <IMAGE>

Description

SPECIFICATION Drawer assembly This invention relates to a drawer assembly, and is particularly, although not exclusively, concerned with a drawer assembly in which the drawer is a paper tray in a xerographic copying machine.

One of the problems which arises with paper trays in xerographic copying machines is that the tray must be fully home before any paper sheets are fed from the tray, otherwise misfeeding may occur, with a resulting paper jam.

The present invention is intended to overcome this problem by providing a drawer assembly which includes means for ensuring that the drawer assembly is fully home.

According to the present invention, there is provided a drawer assembly including a drawer slideably mounted on a frame, and a device for positively locating the drawer in its home position, said device comprising a locating tab, having narrower leading and trailing portions and a wider intermediate portion, extending rearwardly from the drawer in the direction of sliding movement of the drawer, a tab-receiving arrangement on the drawer frame comprising two members that are spring-urged towards one another, and sensing means operated by the tab to supply a signal to indicate that the drawer is in its home position.

According to another aspect of the invention, there is provided a capstan device including a body which comprises a cylindrical winding drum portion and a wider cylindrical flange portion, a cover adapted to contain the body and to be a close fit over the flange portion, and an anchor pin secured to the flange portion for anchoring the cable and for anchoring an annular insert with one face adjacent the flange portion, the insert having a helical face away from the flange portion, the helical face being such as to move th'e cable away from the flange portion during the first revolution of the capstan in the take-up direction.

A drawer assembly in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side elevation of the essential elements which form the sheet path of paper sheets fed through a xerographic copying machine which incorporates a drawer assembly according to the invention; Figure 2 is an exploded perspective view of the sheet tray assemblies of the copying machine, together with their carriage; Figure 3 is a partial perspective view of the rear portion of the carriage; Figure 4 is an underside plan view of a paper tray showing a locating tab used in the present invention; Figure 5 is a perspective view of part of the rear of the tray carriage, showing a receiving arrangement for the locating tab shown in Figure 4; and Figures 6 and 7 are detail perspective views of part of the rear of the tray carriage, showing a capstan device.

Referring to Figure 1, the main components of the paper supply sub-system of a xerographic copying machine are, as indicated diagrammatically, the main paper tray 1, the auxiliary paper tray 2, the paper feeder 3, the outer guide 4, the pre-fuser transport 5, and the output guides 6. Paper sheets are fed from either one of the paper trays 1, 2 by means of a common paper feeder 3 of the friction retard type. The feeder is stationary, and the selected tray is moved into a sheet-feeding position.

Paper is fed from either the main tray 1 or the auxiliary tray 2. The auxiliary tray is of larger size than the main tray, enabling a wider choice of paper sizes and types to be fed from it. The trays are physically located in the lower part of the machine below the photoreceptor drum 7.

Having been fed from a tray, the sheet is moved around the outer guide, which turns the sheet over and stops its leading edge at a registration position. When the sheet is called for to receive the toner image from the photoreceptor drum 7, it is fed into contact with the drum. After it has received the toner images, the sheet is fed by the pre-fuser transport 5, which is a vacuum belt transport arrangement, to the fuser 8. From the fuser, the sheet is delivered through the output guides 6 to a catch tray 9.

The paper trays will now be described in more detail with reference to Figures 2 and 3. The paper trays, indicated generally as a main tray 1 and an auxiliary tray 2, are mounted on a tray carriage 10.

As indicated by the broken lines on Figure 2, the main tray 1 is the upper tray and the auxiliary tray 2 is the lower tray.

The tray carriage 10 is supported entirely by means of vertical ball slides 11, the moving parts only of which are shown in Figure 2, the cooperating, fixed, parts being mounted on the rear frame of the machine. The ball slides 11 allow the tray carriage to move vertically up and down as will be described in more detail later (with reference to Figure 3).

The tray carriage 10 consists of a vertical rear plate 12, a left-hand side plate 13, and a righthand side plate 14. The left-hand side plate 13 carries a box-like container 1 5 along the upper part of the tray carriage 10, for housing electrical components, including an electric motor. An upper left-hand slide rail 16 and a lower left-hand slide rail 1 7 are mounted below the container 15, and extend from front to rear of the ieft-hand side plate 13.

The right-hand side plate 14 carries an inner right-hand slide rail 1 8 and an outer right-hand slide rail 1 9 which both extend from front to rear of the right-hand side plate 14, and are both at the same height as the lower left-hand slide rail 1 7.

The main tray 1 comprises a main tray subframe 20 and a main paper tray 21. The main paper tray 21 is mounted for left-to-right sliding movement over the main tray sub-frame 20 by means of a ball slide 22 at the front of the tray, the rear part of the paper tray 21 sliding over nylon studs (not shown) in the sub-frame 20. The sub frame 20 carries, on a downward extension of its left-hand edge, a left-hand slide 23, for cooperation with the upper left-hand rail 1 6 of the tray carriage 10, and a right-hand slide 24, for cooperation with the outer right-hand rail 1 9.

Since the outer right-hand rail 1 9 is lower than the upper left-hand rail 16, a support plate 25 is provided for the right-hand slide 24, mounted below the base plate 26 of the main tray sub frame 20 by means of extension pieces 27.

The main paper tray 21 , which feeds paper to the right, has an upstanding front wall 28 and a left-hand side wall 29. A movable corner piece 30 is mounted for left to right sliding movement on a slide 31. On the left-hand side wall 29, an elongated catch member 32 is formed, with an upstanding outer portion that extends from about the mid-portion to the rear end portion of the side wall 29. The upstanding outer portion of the catch member 32 is for engagement with a notch 33 in a rack 34 that is mounted for sliding left-to-right movements in the container 1 5. The rack is engaged by a pinion that is driven by a motor 35.

When the main tray 1 is in the 'home' position in the tray carriage 10, i.e. when it has been slid to the rear of the carriage 10 as far as it will go, the upstanding outer portion of catch member 32 engages in notch 33, enabling the motor 35 to drive the paper tray 21 to the left or the right.

In order to prevent the main paper tray 21 from moving to the right other than when it is in its 'home' position, a groove 44 is formed along the right hand vertical side of the container 1 5.

Groove 44 extends from the front of the container 15 to a point approximately mid-way between the front and rear of container 1 5, terminating just in front of the rack 34. The upstanding portion of catch member 32 and the groove 44 are arranged such that during withdrawal and re-insertion of the main tray 1, catch member 32 and groove 44 are slidingly interlocked. Once the main tray 1 is fully home, however, catch member 32 has passed completely through groove 44, and is engaged only by notch 33 of rack,34.

The auxiliary tray 2 includes a platform 36 for supporting copy paper sheets between upstanding front plates 37 and a slideable corner piece 38.

Corner piece 38 is arranged for left-to-right sliding on slide 39. A left-hand slide 40 is carried by a downwardly extending side plate 41 at the lefthand edge of the platform 36, and a right-hand slide 42 is carried by a downwardly extending plate 43 mounted inwardly of the right-hand edge of platform 36. Left-hand slide 40 cooperates with the lower left-hand rail 17 of the tray carriage 10, and right-hand slide 42 cooperates with the inner right-hand rail 1 8 of carriage 10.

Referring to Figure 3, the vertical slides 11 cooperate with rails 50 that are secured by angled members 51 to the rear frame 52 of the machine.

Mounted on the rear panel 12 of the carriage 1 0 are a capstan 53, driven by a motor (not shown) on the front side of rear panel 12, and two pulleys 54, 55. A cable 56 is secured at one end by an anchorage 57 on the machine frame, generally vertically above the highest point reached by the pulley 54. The cable passes around pulley 54, is wound around capstan 53, passes around pulley 53, and is anchored to the machine frame in the same way as the other end. On energising the motor to turn capstan 53, the carriage 10 is elevated or lowered as the cable winds onto or off the capstan.

Copy paper sheets can be fed out from either tray at the choice of the operator. If sheets are to be fed from the main tray, the main paper tray 21 is moved to the right over the main tray sub-frame 20 by means of motor 35. The tray carriage 10 is elevated to bring the top right-hand edge of the stack of sheets in the main paper tray 21 into the feeding position relative to the paper feeder 3, i.e.

into the position indicated diagrammatically in Figure 1. If sheets are to be fed from the auxiliary tray, the main tray 21 is moved to the left over the main tray sub-frame 20, and the tray carriage 10 is elevated to bring the top right-hand edge of the stack of sheets in the auxiliary paper tray 2 into the feeding position. In order to change back to the main tray, the tray carriage 10 is lowered, the main tray is moved again to the right, and the tray carriage 10 is elevated again.

When replenishment of either tray is required, the tray in question may be simply pulled out, on its slides, to the front of the machine. This is only permitted once the main tray 21 has been moved fully to the left and the trays have been lowered from the feed position. In order to load paper, the operator will open the front door, which will break the machine interlock and send a signal by way of the machine logic to the motor which elevates and lowers the tray carriage 10. Energisation of the motor will cause the cable 56 to unwind, allowing the trays to descend under gravity until the tray carriage 10 actuates a down limit switch. When this limit switch is actuated, a signal is sent to the motor 35, causing the main tray 21 to be moved fully to the left. The trays then come to rest, and either one of them can be withdrawn by the operator.The operator will load paper towards the front right-hand corner of the required tray, and set the inboard corner piece 30 or 38 to lock the paper in position. In the front right-hand corner of each tray, there is a registration corner piece, which is moved out of the way whenever the tray is inserted into the machine.

On closing the front door of the machine, the interlock is remade, and on selection of a paper tray, the required tray is moved into the feed position. When the machine is in the standby mode, it is always set to feed paper from the main tray. This is achieved by a time-out feature that resets the machine to the main tray mode if no copies are made within 90 seconds of completing the previous job.

A tray interlock system (not shown) is provided to prevent the operator from pulling the trays out of the machine unless they are in the proper position (as described above), or from pulling out both trays together when they are in the proper position.

Referring now to Figure 4, a locating tab 61 is located on the rear wall of the main paper tray 1, for engagement with the receiving arrangement mounted on the tray carriage 10 and shown in Figure 5. The locating tab 61, which may be for example of a plastics material such as Nylon, is generally kite-shaped, but can be of any similar configuration which includes a narrower leading and trailing portions 62 and 63 respectively, and a wider intermediate portion 64. The locating tab 61 is arranged to be received by the receiving arrangement shown in Figure 5, which includes an aperture 65 between two vertically mounted rollers 66. The rollers are mounted on shafts (not shown) that have their upper and lower ends linked by springs which pull them towards one another. As the tab 61 is inserted into aperture 65, the sides of tab 61 engage the rollers and push them apart.Once the tray has been pushed sufficiently far towards its home position for the wider intermediate portion 64 of the tab 61 to have passed the rollers 66, the force of the springs acting between the rollers causes the tray to be positively pulled into its home position, by virtue of the tab narrowing towards its trailing portion 63.

As the tab locates to its home position, it activates a microswitch 67 by way of an actuating arm 68.

Although only the main tray locating arrangement has been described, a similar arrangement is used on the auxiliary tray, with its locating tab engaging its own pair of rollers 69 on either side of an aperture 70, the aperture 70 being directly below the aperture 65. A microswitch 71 is actuated by a second actuating arm 72 when the auxiliary tray tab is in its home position.

Referring now to Figures 6 and 7, the capstan device 53 for raising the trays is shown in more detail. As mentioned above, the capstan 53 is mounted on the rear plate 12 of the tray carriage, and is arranged to wind in the cable 56 when it is driven by the motor mounted on the tray carriage.

The capstan includes a body 81 which comprises a cylindrical winding-drum portion 82 and a wider cylindrical flange portion 83 (Fig. 7). An anchor pin 84 is secured to the flange portion 83, and anchors the cable 56. Pin 84 also anchors an annular insert 85 which has a plane annular face adjacent the flange portion 83, but a helical face 86 away from the flange portion. The helical face is widest at the end of the insert which is fixed over the pin 84, and tapers around the capstan, so that as the capstan makes its first revolution in the take-up direction (anti-clockwise as shown) the cable moves away from the flange portion.

A cover 87 (Fig. 6) encloses the capstan, being a close sliding fit over the perimeter of flange portion 83. Apertures 88, 89 are provided in the cover to allow the cable 56 into the capstan.

The capstan described operates smoothly and efficiently without any tendency to tangle the cable.

Claims (4)

1. A drawer assembly including a drawer slideably mounted on a frame, and a device for positively locating the drawer in its home position, said device comprising a locating tab, having narrower leading and trailing portions and a wider intermediate portion, extending rearwardly from the drawer in the direction of sliding movement of the drawer, a tab-receiving arrangement on the drawer frame comprising two members that are spring-urged towards one another, and sensing means operated by the tab to supply a signal to indicate that the drawer is in its home position.

2. The drawer assembly of claim 1, wherein said spring-urged members comprise rollers mounted on shafts, the shafts being generally parallel with one another and being pulled towards one another by springes.

3. An electrostatographic apparatus including at least one paper supply tray which comprises a drawer assembly according to claim 1 or claim 2, the apparatus being responsive to said signal to prevent the apparatus from being operated unless the, or each, paper supply tray is in its home position.

4. Capstan device including a body which comprises a cylindrical winding drum portion and a wider cylindrical flange portion, a cover adapted to contain the body and to be a close fit over the flange portion, and an anchor pin secured to the flange portion for anchoring the cable and for anchoring an annular insert with one face adjacent the flange portion, the insert having a helical face away from the flange portion, the helical face being such as to move the cable away from the flange portion during the first revolution of the capstan in the take-up direction.