EP1197450B1 - Control for a pulsed air knife for a suction belt feed mechanism - Google Patents

Description

The present invention relates to the field of printers and copiers, and more particularly to a receiver sheet feeding and feeding apparatus comprising a suction belt feeding mechanism in which the top sheet of a stack is corrugated, and a positive pressure air separating apparatus provided in such printers and copying machines. This invention is useful for the device used in the US 5,344,133 is described. The cited patent relates to a vacuum air supply, a first positive pressure air supply and a second positive pressure air supply. The first and second positive pressure air supplies are used simultaneously and collectively referred to herein as air knives.

In typical reproduction devices, such as copiers or printers, the information is reproduced on individually cut recording material sheets, such as white paper or transparencies. Such recording sheets are stored in a stack and fed individually when copies are to be made. The sheet feeder for the reproduction machine must be able to handle a large number of sheet types and sizes reliably and without damage. The sheets must be fed individually and without incorrect or multiple feeds.

In the suction belt feeding mechanism disclosed in the above-mentioned patent, in which the uppermost sheet of a stack is corrugated, both the negative pressure air and the positive pressure air are controlled by means of valves. During the intake cycle, the relief air valve is always open. The vacuum air valve is opened to grab the top sheet from the stack. After about 220 milliseconds (at a feed rate of 110 sheets per minute), a clutch is actuated which drives the suction belts so that the sheet is fed into the transport rollers, which rotate constantly. After the leading edge of the sheet has reached the transport rollers and before the trailing edge of the sheet reaches the edge of the openings in the vacuum air chamber, the vacuum air is deactivated and the clutch is turned off.

The air flow and the air flow velocity of the air knife must be sufficiently strong during the gripping phase, so that the stack is loosened and the top sheet is preliminarily lifted. During the transport phase, the air flow of the air knife must be strong enough to create the air cushion between the fed bow and the rest of the stack. However, excessive airflow during the transportation phase has several undesirable effects. For example, if the airflow is too strong, there is a greater likelihood that the bows located under the topmost bow will be blown away from the front edge to the back. This is particularly problematic for sheets that have no continuous rear edge. In addition, the air may deform the leading edge of sheets that have low stiffness, particularly with downward curl (leading edge away from the suction bands), which may result in paper damage or paper jam. The air flow must not be so strong that sheets under the sheet being fed are raised above the mechanical stopper fingers located along the edge of the paper tray, or the second sheet comes into contact with the first if it is transported away from the stack. In addition, if the air flow is too strong, it may cause the trailing edge of the sheet being fed to flutter violently, which in turn may contact the underlying sheet, which may also cause it to move forward becomes.

Typically, the minimum air flow of the air knife is determined by the gripping and separation requirements, while the maximum air flow of the air knife is limited by the transport phase. What is desired is an operating method that optimizes the utility of the air knife during the picking and separation phases while minimizing the disadvantages of the air knife during the transportation phase.

EP-A-0 598 272 describes a method for operating a Saugbandvorschubmechanismus in which the top sheet of a stack (1) is corrugated, with a positive pressure air separation device during a feed cycle (SHEET), wherein the vacuum air and the positive pressure air are controlled by means of a vacuum air valve and a positive pressure air valve, wherein the paper with the help of at least one belt is activated, which is activated when a supply clutch is operated, wherein the negative pressure air (FAN 12) is activated when the intake cycle starts, and deactivated when the supply clutch is disconnected (DRIVE OFF), the method is the step pulsing the positive pressure air separation device (NOZZLE 19, ql) by activating and deactivating the positive pressure air separation device during the intake cycle.

US 5,344,133 describes pulsing a positive pressure air separation device by activating and deactivating the positive pressure air separation device during a pull-in cycle.

The invention provides a method according to claim 1 and an apparatus according to claim 4. Further features of the invention are contained in the subclaims.

The invention will be described below with reference to the drawings based on preferred embodiments.

FIG. 1

eine Seitenansicht eines Aufnahmebogenzufuhr- und -einzugsapparates;

FIG. 2

eine Draufsicht des Aufnahmebogenzufuhr- und -einzugsapparates aus Fig. 1, wobei Teile entfernt oder weggelassen sind, um die Ansicht zu ermöglichen;

FIG. 3

eine Seitenansicht eines Querschnitts eines Aufnahmebogenzufuhr- und - einzugsapparates entlang der Linien 3-3 aus Fig. 2;

FIG. 4

eine seitliche Querschnittsansicht eines Teils eines Aufnahmebogenzufuhr- und -einzugsapparates;

FIG. 5

eine Stirnansicht eines Teils des Aufnahmebogenzufuhr- und - einzugsapparates entlang der Linien 5-5 aus Fig. 3;

FIG. 6

eine Stimansicht eines Teils des Aufnahmebogenzufuhr- und - einzugsapparates entlang der Linien 6-6 aus Fig. 3.

In the drawings show:

FIG. 1

a side view of a receiving sheet supply and -einzugsapparates;

FIG. 2

a plan view of the receiving sheet supply and -einzugsapparates from Fig. 1 with parts removed or omitted to allow the view;

FIG. 3

a side view of a cross section of a receiving sheet feed and --zugsapparates along lines 3-3 Fig. 2 ;

FIG. 4

a side cross-sectional view of a portion of a receiving sheet supply and -einzugsapparates;

FIG. 5

an end view of a portion of the receiving sheet feed and --zugsapparates along lines 5-5 Fig. 3 ;

FIG. 6

an end view of a portion of the receiving sheet feed and --zugsapparates along the lines 6-6 Fig. 3 ,

The US 5,344,133 describes a device that uses both vacuum and positive air to separate and grasp the top sheet of a feed stack. In this invention, both the negative pressure air line and the positive pressure air line pass through valves used to control the negative pressure air flow and the positive pressure air flow. During normal operation of a printer or copier that is in the US 5,344,133 used device described, both the vacuum air valve and the positive pressure air valve is open during the feed cycle, and they are closed when the printer or the copying machine is not being supplied by the respective supply device.

The following is a detailed description of the drawings, which in the US 5,344,133 described Saugbandvorschubmechanismus with the positive pressure air separation device, in which the uppermost sheet of a stack is corrugated. Although this system is described in detail, the present invention is not limited to use in this particular system. The present invention can be used in any printer or copier that uses a combination of vacuum air and positive air to lift and separate the top sheet from a feed stack.

The detailed description refers to a suction belt feed mechanism in which the topmost sheet of a stack is corrugated and which provides a supply from above, however, the present invention can also be used for a suction belt feed mechanism in which the topmost sheet of a stack is corrugated and at which a supply is provided from below. In the latter case, the vacuum air together with the air knife would separate the lowermost sheet instead of the uppermost sheet.

Various features of the invention are in Figures 1-6 shown, which are not drawn to scale and in which the same elements are provided with the same Bezugsnummem. In Figures 1-2 a receiving sheet feeding and feeding apparatus is shown. The receiving sheet feeding and feeding apparatus, generally designated by numeral 10, includes an open magazine 12 and a lifting platform 14 which supports a stack of sheets. A sheet stack 15 carried by the lifting platform 14 contains individual sheets that can serve as a record sheet on which reproductions are made in a copier or printer.

The sheet stack supporting platform 14 is held in the magazine 12 by a lifting mechanism that performs a substantially vertical lifting movement. The lift mechanism serves to raise the lift platform 14 to a height such that the topmost bow of the stack is maintained at a predetermined level during operation. The topmost bow is determined by means of a bow detection switch 80 (see Fig. 5 ) or by means of a plurality of switches at the predetermined level, wherein the switch controls a motor for actuating the lifting mechanism, by which the platform is raised until one or more switches are activated.

A sheet feeder head assembly 30 is disposed in communication with the magazine 12 so as to extend above a portion of the lift table 14 in spaced relation to a stack of sheets 15 supported by the lift table 14. The sheet feeder head assembly 30 includes an apertured chamber 32 connected by a vacuum air valve 38 to a vacuum air source 31 and an air knife 40 connected to a positive pressure air source 41. A positive pressure air nozzle of the air knife 40 raises the uppermost arc of the supported sheet stack 15. Through the chamber openings 33, the vacuum air acts on the chamber 32 such that the topmost raised sheet of the stack is then taken to the separation of the sheet stack 15 to the chamber 32. Additional positive pressure air nozzles of the air knife 40 ensure that subsequent sheets are separated from the uppermost arc.

A vacuum air valve 38 (see Fig. 5 ) is used to control the operation of the vacuum air and to limit the vacuum air level. Therefore, the valve is open during a draw cycle to raise the top sheet of the stack. In a preferred method of operation, the opening and closing of the vacuum air valve is timed, however, the valve operation may also be controlled by other methods, such as a pressure switch or a mechanically operated switch. For example, at the chamber 32 a Switch is located, which detects the time when an arc has been taken. A signal that is output from the switch when the gripping of a sheet is detected may be used to control a plurality of components of the sheet feeder head assembly 30, such as the timing of actuation or adjustment of airflow intensities, to perform the operation for a particular type of sheet (Sheet size) to be supplied from the receiving sheet feeding and feeding apparatus 10 to optimize. By "activated" vacuum air, it is meant that the vacuum air valve 38 is open. By "deactivated" vacuum air, it is meant that the vacuum air valve 38 is closed.

The belts 36 are selectively driven by operating a feed clutch (not shown) in a direction such that the gripped sheet is removed from the area above the sheet pile 15 and conveyed in the feed direction via a conveying path to a downstream transport device, e.g. B. to a driven nip roller pair 50. The pair of rollers 50 is driven by a motor. A gear 52 is rotatably mounted on a shaft (not shown) on which a roller of the roller pair 50 is mounted. A clutch 56 is selectively activated to couple the gear 52 to the shaft 54 to rotate with the shaft. An intermediate gear 58 engages the gear 52 and a gear (not shown) coupled to one of the band rollers 39. Accordingly, when the clutch 56 is engaged, the belts 36 are driven to feed a gripped sheet such that the gripped sheet is removed from the sheet stack 15 and subsequently available for further processing, for example, to receive a sheet Reproduction from a copier or printer.

The air knife 40 includes a first air jet assembly 42 and a second air jet assembly 44. The first air jet assembly includes a single nozzle 43 which is connected for fluid contact with a positive pressure air source 41 which, in certain embodiments, provides an air pressure in the range of, for example, 1,000 to 2,500 Pa. The chambers, which are part of the first air jet assembly 42 and the second air jet assembly 44, may be separate chambers, or they may be grouped into a larger chamber. The nozzle 43 directs a positive pressure air flow on the sheet stack, in the middle of the leading edge, to loosen the top sheets of the stack and bring the top sheet into contact with the sheet feeder head assembly 30, where it can be detected by the vacuum air at the chamber 32.

The second air jet assembly 44 includes a plurality of nozzles 46 connected to the positive pressure air source 41 for fluid communication. The nozzles 46 are aligned slightly downstream relative to the target point of the first air nozzle 43. The task of the second air jet assembly 44 is to separate sheets adhering to the uppermost sheet gripped by the sheet feeder head assembly 30.

A positive pressure air valve 60 is used to control the positive pressure air flow passing through the air knife 40. When the positive pressure air separation device 40 is activated, it means that the positive pressure air valve 60 is opened. When the positive pressure air separation device 40 is deactivated, it means that the positive pressure air valve 60 is closed. However, if the positive pressure air valve 60 is closed, it does not necessarily mean that there is no overpressure airflow. In a preferred embodiment, the positive pressure air valve 60, even when closed, passes some airflow (it does not completely close). A conventionally used valve construction, in the "closed" state, allows about one third of the air flow to pass through an open valve.

A conventional method for operating a positive pressure air separation suction belt feed mechanism in which the top sheet of a stack is corrugated during a draw cycle is to activate the vacuum air valve 38 and the positive air separation device 40 at the beginning of the draw cycle and to deactivate the vacuum air valve 38 when the feed clutch is disconnected, but to leave the positive pressure air separation device 40 in the activated state during the entire intake cycle.

According to one aspect of the invention, this method is improved by pulsing the positive pressure air separation device 40 by activating and deactivating the positive pressure air separation device 40 during the pull-in cycle.

In the invention, the positive pressure air separation device 40 is activated when the vacuum air is activated and deactivated before the feed clutch 56 is engaged. According to this feature of the invention, the positive pressure air separation device is activated during the gripping phase and deactivated during the transport phase.

In another preferred embodiment, the positive pressure air separation device 40 is activated when the vacuum air is activated and deactivated about 50 milliseconds before the feed clutch 56 is actuated. This period of time can be optimized for different feed speeds, for example, it may be necessary that it is lower at higher feed speeds. By pulsing the positive pressure air separation device 40, the overpressure achieved can be higher and the negative pressure (air flow with "closed" overpressure air valve 60) can be lower. This means that a higher air pressure is available during the gripping phase, where the overpressure is needed to separate the sheets from each other. During the transportation phase, when a higher air pressure causes problems, the air pressure is lower because the positive air separation device 40 is deactivated. As a result, the take-up sheet feed and feed apparatus 10 is made to work better on heavier paper because a higher air pressure is available during gripping. Furthermore, it is achieved that the receiving sheet feed and intake sheet feeder 10 works better with lighter paper types, since there is a lower air pressure during transport. Thus, by this invention, the operating window of the receiving sheet supply and -einzugsapparates 10 is opened. This control allows the level of overpressure to be increased by a factor of two without significantly affecting the pull-in performance of light paper.

In copiers or printers having multiple sheet feeders, this invention further allows a smaller blower to do the same job since the positive pressure air separation device 40 is not activated during the entire pick cycle.

In one aspect, a method of operating a suction belt advance mechanism in which the top sheet of a stack is corrugated with positive air separation device 40 during a draw cycle, opening the vacuum air valve 38 and the positive pressure air valve 60, closing the positive pressure air valve 60, operating the feed clutch 56 on Bändereinzug, disconnecting the feed clutch 56 and the closing of the vacuum air valve 38th

LIST OF REFERENCE NUMBERS

10

Receiving sheet feeding and feeding apparatus

12

magazine

14

lifting platform

15

sheet pile

30

Sheet feed head assembly

31

Pressurized air source

32

chamber

33

chamber openings

36

tape

38

Pressurized air valve

39

bands roles

40

Air knife or overpressure air separation device

41

About compressed air source

42

first air jet arrangement

43

single nozzle

44

second air jet arrangement

46

Variety of nozzles

50

Nip roll pair

52

gear

54

wave

56

feed clutch

58

intermediate gear

60

About Air Valve

80

Sheet detection switch

Claims (4)

1. Method of operating a vacuum belt feeder mechanism in which the first sheet of a stack is corrugated with a positive air pressure separator (40) during a feed cycle, wherein said vacuum and said positive air pressure are controlled by a vacuum valve (38) and by a positive air pressure valve (60), wherein the paper is taken away by at least one belt (36) which is actuated when a feed clutch (56) is energized, wherein the vacuum is actuated at the start of the feed cycle and is de-actuated when the feed clutch (56) is de-energized, wherein the positive air pressure separator (40) is pulsed by actuation and de-actuation of the positive air pressure separator (40) during the feed cycle, and wherein the positive air pressure separator (40) is actuated when the vacuum is actuated and the positive air pressure is de-actuated before the feed clutch (56) is energized.
2. The method of Claim 1 wherein, when the feed rate is 110 pages per minute, the positive air pressure separator (40) is actuated when the vacuum is actuated, and the positive air pressure is de-actuated approximately 50 milliseconds before the feed clutch (56) is energized.
3. The method of Claim 1 wherein, when the feed rate is 110 pages per minute, the positive air pressure valve (60) is closed approximately 50 milliseconds prior to the clutch (56) being energized.
4. Device with a vacuum belt feeder mechanism in which the first sheet of a stack is corrugated with a positive air pressure separator (40), said vacuum and said positive air pressure being controlled by a vacuum valve (38) and a positive air pressure valve (60) during a feed cycle in accordance with the method of one of Claims 1 to 3, with the paper being taken away by at least one belt (36) which is actuated when a feed clutch (56) is energized, and the vacuum being actuated at the start of the feed cycle and being de-actuated when the feed clutch (56) is de-energized.

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