JPH03288731A - Paper feeding device - Google Patents

Abstract

PURPOSE:To prevent the deformation of a roller by keeping a bottom plate at an automatic paper feeding position up to a paper feed enabled timing in printing operation and lowering the bottom plate when a paper feed start signal is not supplied and releasing the press contact with a pick-up roller in waiting, keeping the speed at the maximum value. CONSTITUTION:When a paper feed start signal is inputted, a bottom plate 6 is raised, and if the paper sheet reaches an automatic paper feeding position, the paper sheet 5 is supplied by a pick-up roller 1 and a feed roller 2, and after a certain time, the bottom plate lowers and reaches an intermediate position, and the double feed with the next paper sheet is prevented. The bottom plate is raised again in the timing in which the paper sheet 5 separates from the feed roller 2, and the existence of the paper sheet is judged by a paper end sensor 8. Then, the bottom plate 6 is kept at an automatic paper feeding position up to the paper feed enabled timing. The next paper feed start signal is checked, and if the existence is confirmed, the next paper feed operation is carried out, while if the signal is not confimrmd, the bottom plate 6 is lowered. Accordingly, the printing speed is kept at the max., and when no paper sheet is supplied, contact with the roller 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a paper feeding device for recording paper in an image forming apparatus such as a printer or a copying machine.

(Prior art) Fig. 9 shows F RR (Feed And Reverse).
An example of a paper feeding mechanism of the Roller type is shown in Fig.
) shows the operating state of each mechanical section at the automatic paper feeding position, and (2) in the same figure shows the operating state of each mechanism at the intermediate position.

To explain this paper feeding process, when the paper cassette 7 is set in the cassette holder, this is detected and the lever 4 linked to the lifting mechanism of the bottom plate 6 moves the top surface of the paper 5 to the proper paper feeding position (automatic paper feeding position). 1)) and is controlled to maintain that position. When there is a paper feed signal, the motor for transporting the paper begins to rotate, and when power is transmitted by a paper feed clutch (not shown), the feed roller 2 and pickup roller 1 are driven to rotate clockwise, and the paper moves in the direction of arrow A in the figure. sent to the left.

Place the paper on the foot roller 2. After a set time sufficient to feed the paper into the nip between the reverse rollers 3, the bottom plate 6 is lowered to an intermediate position (2) lower than the automatic paper feeding position, and the pressure contact between the pickup roller 1 and the paper surface is released.

After that, when the paper 5 passes through the feed roller 2, the bottom plate 6
is raised, and it is determined whether there is a sheet to be fed next at the automatic sheet feeding position (1). Note that a paper end sensor 8 made of a photo interrupter or the like is used to determine the presence or absence of paper.

(Problem to be Solved by the Invention) As mentioned above, during printing standby, the bottom plate 4 was held at the automatic paper feeding position (1), so pressure was always applied to the pickup roller 1, and it remained in this pressed state for a long time. If printing is not performed, the pickup roller 1 will be deformed. For this reason, the strength of the pressure contact between the pickup roller 1 and the paper 5 during paper feeding may vary, and there is a risk of non-feeding.

In view of the above circumstances, it is an object of the present invention to provide a low-cost paper feeding device that maintains the continuous printing speed at the maximum, lowers the bottom plate during printing standby, and prevents deformation of the pickup roller.

(Means for Solving the Problems) In order to achieve the above object, the invention as set forth in claim (1) lifts the bottom plate of a paper feed cassette to an automatic paper feed position and transfers the paper on the bottom plate to a pickup roller. In an FRR type paper feeding device that presses the bottom plate from below, separates the paper one by one with the pickup roller, and automatically feeds the paper with the feed roller, the bottom plate is automatically fed at the timing when the paper comes out from the feed roller after paper feeding starts. A paper presence/absence detecting means raises the bottom plate to a position and determines the presence or absence of the next paper, and the height of the bottom plate is maintained from the timing of paper presence/absence judgment until the next paper feeding possible timing, and a paper feeding start signal is output at the paper feeding possible timing. If there is a paper feed start signal, the next paper feed will be started, and if there is no paper feed start signal, the bottom plate will be lowered to an intermediate position lower than the automatic paper feed position, and the bottom plate will be held at the intermediate position until a paper feed start signal is received, and paper feeding will begin. The present invention is characterized in that it includes a bottom plate elevating means that raises the bottom plate and enters the next paper feeding operation only after receiving a signal.

Further, the invention described in claim (2) lifts the bottom plate of the paper feed cassette to the automatic paper feed position, presses the paper on the bottom plate against a pickup roller from below, and separates the paper sheets one by one with the pickup roller. In a paper feeding device having a plurality of FRR type paper feeding means that automatically feeds paper using a foot roller, the bottom plate is raised to the automatic paper feeding position at the timing when the paper comes off from the feed roller after paper feeding starts, and the next paper is detected. There is a paper presence/absence detection means that determines if there is no paper, a paper feed selection means that allows selection of the paper feed method for each print, and a paper feed selection means that continues to maintain the height of the bottom plate even after detecting the presence of paper, and there is no paper feed start signal.
At the timing when the motor stops and the printing operation ends, the bottom plates of all paper feeding means are lowered to the intermediate position lower than the automatic paper feeding position, and the bottom plates are held at the intermediate position until the next paper feeding start signal is received. The present invention is characterized in that it includes a bottom plate elevating means that raises the bottom plate and enters the next paper feeding operation only after receiving a paper feeding start signal.

(Function) The invention described in claim (1) maintains the bottom plate at the automatic paper feeding position until the next paper feeding possible timing during printing, and lowers the bottom plate if there is no paper feeding start signal at this paper feeding possible timing. . For this reason, while maintaining the continuous printing speed at the maximum, a gap is created between the pink up roller and the paper during printing standby to release the pressure contact with the pickup roller, and it is also possible to manually feed paper using the top surface of paper string cassettes 1 to 3. Paper feeding can also be achieved at low cost.

The invention described in claim (2) has a plurality of paper feeding means, and even if the paper feeding means can be selected one by one, after the paper feeding signal is lost, all printing operations are completed, and the motor is stopped,
Lower the bottom plates of all paper feeding means. In this way, even if multiple paper feeding means are randomly selected, the continuous printing speed will not be reduced. In addition, during printing standby, the bottom plate can be lowered to create a gap between the pickup roller and the paper, thereby releasing pressure against the pickup roller.

(Example) The invention according to claim (1) of the present invention will be described in detail. 1 and 2 are timing charts of the paper feeding means in response to the paper feeding start signal (A), and FIGS. 3 and 4 are flowcharts of the overall operation and paper feeding control operation of the image forming apparatus. Now, the FRR type paper feeding mechanism in which the present invention is implemented is the one shown in FIG. 9 above.

When the power of the image forming apparatus main body is turned on (Fig. 3 81)
The initial settings of the main body of the apparatus are made (S,), and a print request is determined (S3). If there is a print request, paper feed control is performed (S4) and printing operation begins (S,
).

This paper feeding control is carried out in the flowchart of Fig. 4, Fig. 1, and Fig. 2.
This is done according to the timing chart shown in the figure.

That is, when there is a paper feeding start signal (A) in FIGS. 1 and 2, the lifting mechanism for the bottom plate 6 operates, and when the bottom plate 6 rises and reaches the automatic paper feeding position (FIG. 9 (1)), At time t), the paper feed clutch is ONL, the pickup roller 1 and the feed roller 2
The paper 5 is fed (see FIG. 4).

S4□). After a certain period of time, the bottom plate descends (542) and waits at an intermediate position (FIG. 9 (2)) to prevent the next sheet from being fed in duplicate. Then, at the timing T,+t when the paper 5 passes through the feed roller (S43), the bottom plate is raised again (S,...) to determine the presence or absence of paper, and the paper end sensor 8 determines the presence or absence of paper (8.5 ). After that, the bottom plate is kept at the automatic paper feeding position until paper feeding timing T7+t, and the next paper feeding start signal (A) is checked at T2+t (
S46).

Then, if there is a paper feeding start signal (A), the paper feeding clutch is turned on and the next paper feeding operation begins (S4).

Further, if there is no next paper feeding start signal (A), the bottom plate is lowered (S, g) and is placed on standby at an intermediate position (FIG. 9 (2)).

In this way, in the case of continuous printing where there is the next paper feed start signal (A) before the paper feed is possible, the speed to printer 1 is kept at maximum, and if there is no paper feed start signal, the pickup roller 1 and the paper A gap can be provided between the rollers 5 and 5, so that the pickup roller does not come into pressure contact when the paper is not fed.

Next, the invention according to claim (2) will be explained in detail. FIG. 5 is a timing chart of the paper feeding means in response to paper feeding start signals (C) and (D), FIG. 6 is a flowchart of the overall operation of the image forming apparatus, and FIG. 7 is a detailed paper feeding control operation in FIG. 6. Flowchart, FIG. 8 - FIG. 8 is a detailed flowchart of the printing end operation of FIG. 6, and is intended for an FRR type paper feeding mechanism having a plurality of paper feeding means, and there are a plurality of paper feeding mechanisms of FIG. 9.

Regarding the points different from the invention described in claim (1), the paper feed control (S4) in FIG. 6 is performed by processing 8 as shown in FIG.
41 to S45, and the printing end operation (S6) is added with processes S61 to S6□ as shown in FIG.

Here, an image forming apparatus that has a lower paper feeder and a lower paper feeder as a paper feeding means, and in which the lower paper feeder and the lower paper feeder can be selected for each print will be described as an example. First, when there is a paper feed start signal (C) from the lower paper feed, the bottom plate lifting mechanism operates, and when the bottom plate 6 rises and reaches the automatic paper feed position (Fig. 9 (1)), the lower paper feed starts (1). The paper clutch is turned on and the pickup roller 1 and feed roller 2
The paper 5 is fed (ts4□ in FIG. 7). After a certain period of time, the bottom plate descends to the intermediate position (Fig. 9 (2)).
) to prevent the next paper from being fed multiple times. Then, the timing Tl +t (
In S43), the bottom plate is raised again to determine the presence or absence of paper (S4.), and the paper end sensor 8 determines the presence or absence of paper (S, j).

Then, the bottom plate of the upper sheet feeder is held as it is at the automatic sheet feeding position and waits for the next sheet feeding start signal.

After that, since there is a paper feed start signal (D) from the lower paper feed, paper feeding is started from the lower paper feed at the paper feeding possible timing (T, +t) of the lower paper feed. Then, at the timing (T, +t) when the paper passes through the feed roller, the bottom plate rises again to determine the presence or absence of paper. The bottom plate of the lower paper feeder is held at the automatic paper feed position and waits for the next paper feed start signal. These operation flowcharts include processes 84□ to S, 1. ; is carried out.

Next, when there is a paper feeding start signal (C) from the top paper feed, paper feeding from the top paper feed is performed at the timing when paper feeding from the top paper is possible (2xr2+t). After that, when the printing operation for all paper is finished (S,,,), the main motor stops (S,...).
, , , ), "The bottom plates of the second paper feed and the bottom paper feed descend (5c2) and wait at the intermediate position.

Here, if after feeding the first sheet of paper (top paper), you switch to bottom paper feeding, ] - If you lower the bottom plate of the paper feed, 3
When the feeding of the 1st sheet of paper (upper paper) starts, the print speed is delayed by the amount of time the bottom plate rises. For this reason, after the paper feed signal is lost and all printing operations are completed and the motors have stopped, the bottom plates of all the paper feed means are lowered to randomly select the paper feed means in an image forming apparatus that has multiple paper feed means. A feature of the present invention is that the bottom plate can be lowered during standby without reducing the continuous printing speed even when the printer is on standby.

In the case of an image forming apparatus having only one paper feeding means, the bottom plate may be lowered at the timing shown in the embodiment of the invention described in claim (1), but As shown in the embodiment, it is also possible to set the timing to stop the motor.

(Effects of the Invention) As explained above, the invention according to claim (1) of the present invention maintains the bottom plate at the automatic paper feeding position until the next paper feeding possible timing during printing, and feeds paper at the paper feeding possible timing 11. Since the bottom plate is lowered when there is no start signal, the continuous printing speed is maintained at the maximum and the pressure contact with the pickup roller is released during printing standby.

Further, the invention described in claim (2) has a plurality of paper feeding means, and even when the paper feeding means can be selected for each sheet, the continuous printing speed can be maintained at the maximum, and the pressure contact with the pickup roller during standby of the pudding mill can be maintained. unlock.

[Brief explanation of the drawing]

1 to 4 are drawings according to the invention as set forth in claim (1) of the present invention, FIGS. 1 and 2 are operation timing charts of the embodiment, and FIGS. 3 and 4 are diagrams of the embodiment. It is an operation flowchart. 5 to 8 are drawings according to the invention as set forth in claim (2) of the present invention, FIG. 5 is an operation timing chart of the embodiment, and FIGS. 6 to 8 are operation flowcharts of the embodiment. be. FIG. 9 shows an example of an FRR type paper feeding mechanism in which the present invention is implemented, and FIG. 9(1) shows an automatic paper feeding position, and FIG. 12-(2) shows an intermediate position. 1...Pickup roller, 2...Feed roller, 3...Reverse roller, 4...Lever, 5...Paper, 6...Bottom plate, 7...
Paper feed cassette, 8...Paper end sensor.

Claims (2)

[Claims] (1) FRR in which the bottom plate of the paper feed cassette is lifted to the automatic paper feed position, the paper on the bottom plate is pressed against the pickup roller from below, the pickup roller separates the paper one by one, and the feed roller automatically feeds the paper. In the method paper feeding device, the bottom plate is raised to the automatic paper feeding position at the timing when the paper comes out from the feed roller after paper feeding starts, and a paper presence/absence detection means determines the presence or absence of the next paper; The height of the bottom plate is maintained until the next paper feeding timing is possible, and if there is a paper feeding start signal at the paper feeding timing, the next paper feeding is started, and if there is no paper feeding start signal, the bottom plate is moved from the automatic paper feeding position. The bottom plate is lowered to a lower intermediate position, held at the intermediate position until a paper feed start signal is received, and raised and lowered to enter the next paper feed operation only after receiving the paper feed start signal. Characteristic paper feeding device. (2) Lift the bottom plate of the paper feed cassette to the automatic paper feeding position, press the paper on the bottom plate against the pickup roller from below, separate the sheets one by one with the pickup roller, and automatically feed the paper with the feed roller. In a paper feeding device having an FRR type paper feeding means, the paper presence/absence detection means raises the bottom plate to an automatic paper feeding position at the timing when the paper comes off the feed roller after paper feeding starts, and determines whether or not the next paper is present. , a paper feed selection means that allows you to select the paper feed method for each print, and the bottom plate continues to maintain the height even after detecting the presence of paper, and if there is no paper feed start signal, the motor stops and the printing operation ends. The bottom plates of all paper feeding means are lowered to an intermediate position lower than the automatic paper feeding position at the appropriate timing, and the bottom plates are held at the intermediate position until the next paper feeding start signal is received, and the bottom plates are raised only after receiving the paper feeding start signal. A paper feeding device characterized in that it is equipped with a bottom plate elevating means for entering the next paper feeding operation.