JP3678289B2 - Paper feeding method and recording apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording apparatus such as a printer, and in particular, in a scooping-out skewing system that reverses and discharges a transport roller that bites a certain length of paper to correct skew, the feed roller and the transport roller are independent. The present invention relates to a sheet feeding method and a recording apparatus that suppress a variation in the amount of biting of a conveying roller when a motor is used and at least a DC motor is used as a conveying roller driving system.
[0002]
[Prior art]
Conventional paper feeders generally employ a system in which a plurality of sheets stacked on a hopper are fed one by one from the topmost sheet, and a separation pad that contacts the paper feed roller is fed to the feed path. And the sheets are fed one by one using the friction between the separation pad and the paper.
In the method of feeding sheets one by one from the hopper, a so-called skew that is sent obliquely with respect to the feeding path is likely to occur. If the paper is fed in a skewed state, the paper is likely to be jammed, and a problem such as the fact that printing is not performed at a predetermined position of the paper occurs. As a countermeasure, skew removal is performed before recording. For skew removal, the leading end of the paper is abutted against the stopped conveying roller, and the feeding roller is rotated for a short time in that state. The conveying roller is bitten by the conveying roller and the feeding roller is stopped. There is a biting discharge system that reverses the discharge and discharges.
[0003]
The conventional paper feeding device is configured to drive both the paper feeding roller and the conveying roller by a stepping motor, prepare a paper feeding speed according to the paper type in advance as a paper feeding mode, and select a paper feeding mode suitable for the paper. To choose. For example, FIG. 14 shows a skew removal flow after paper detection, and FIG. 15 shows a paper feed timing chart.
In FIG. 14, when the skew removal is started, the ASF motor and the PF motor (conveying roller motor) are simultaneously started, and the paper feeding roller is normally rotated by n2 steps, and the conveying roller is normally rotated by m1 steps. Here, the sheet feed amount of the sheet feeding roller by n2 steps forward rotation is equal to the sheet feed amount of the transport roller by m1 steps forward rotation. After letting the paper feed the transport roller for a certain length of time, with the paper feed roller stopped, the transport roller is reversed by m1 steps to eject the paper and correct the skew.
For cueing after skew removal, the feed roller and transport roller are simultaneously rotated to perform a reset operation to make the paper feed roller stand by at a predetermined rotation position, and the transport roller is rotated forward by m3 steps to perform cueing. Do.
[0004]
[Problems to be solved by the invention]
The conventional paper feed system employs stepping motors having the same characteristics as the ASF motor and PF motor, so that the start-up characteristic (acceleration curve characteristic) from stop to constant speed rotation and decelerate and stop from constant speed rotation. Since there is no difference in the fall characteristic (deceleration curve characteristic) between the two motors, there is no particular problem in the paper feed performance even if the start / stop timing is the same.
[0005]
In recent years, there has been a great interest in the noise of equipment in order to improve the usage environment of offices and the like. In order to respond to such social needs, countermeasures for noise reduction have been taken in recording apparatuses. For example, when the PF motor is a DC motor, the rise characteristic (acceleration curve characteristic) and fall characteristic (deceleration curve characteristic) are different from those of the stepping motor that rotates the paper feed roller. In the paper feed control, a speed difference due to the motor characteristics occurs at the beginning and the end of paper feed, and the paper feed is affected. In particular, since the acceleration curve characteristic and the deceleration curve characteristic of the DC motor change due to load fluctuations, it is necessary to control the feeding speed differently between the high speed mode and the low speed mode.
[0006]
In the biting and discharging type skew removal, if the acceleration and deceleration stop of the DC motor are not stable, the amount of biting varies, and as a result, the accuracy of correcting the skew decreases. Further, the variation in the amount of biting is related to the sheet feeding speed, and the variation is large at a high speed, and the variation is small at a low speed. Further, if the amount of biting is large, the paper is scratched by subsequent discharge. If skew removal is not sufficiently performed due to such factors, printing is not performed at a predetermined position on the paper, and a problem such as a paper jam occurring at the time of paper discharge occurs.
[0007]
An object of the present invention is to use an independent motor drive system for the paper feed roller and the transport roller, and at least use a DC motor for the transport roller drive system to suppress variation in the amount of biting of the transport roller during skew removal and damage the paper. It is an object of the present invention to provide a paper feeding method and a recording apparatus that improve the accuracy of skew removal without giving them.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, a paper feed roller that is driven by a stepping motor, a transport roller that is driven by a DC motor, and a paper detection that is disposed in a transport path between the rollers and detects the paper to be fed. and a vessel, the paper feed roller forward the sheet to be fed so eating stick by forward rotation of the conveying roller by a, after being nipped by the feed roller and conveying roller, the paper feed roller and the transport the roller is stopped, further in the sheet feeding method for feeding and discharging reverses the conveying roller in a state of stopping the feed roller after skew of the sheet, the sheet paper detector fed by the paper feed roller before passing through the conveying roller is rotated forward to the constant speed, the said stepping motor and DC motor drives a number of steps that have been set for each, based on the sheet detection, based on the sheet detection The number of steps to drive the DC motor is determined by taking into account the deceleration curve characteristics of the DC motor from the number of steps when feeding at a constant speed the distance from the paper detector to the leading edge of the paper that has bitten on the transport roller for a fixed length. Thus, the correction step number obtained by subtracting several steps is set .
[0011]
According to the first aspect of the present invention, before the paper detection, the other motor of the conveying roller, for example, the DC motor is set at a constant speed, and when the paper passes the paper detector, the number of steps set by the paper detector is driven. As a result, the influence of the acceleration curve characteristic of the DC motor is eliminated, and the variation in the amount of biting is reduced.
Furthermore, by correcting the number of steps of the DC motor from the paper detector in consideration of the deceleration curve characteristics, it is possible to make the deceleration stop almost coincident with the deceleration stop of the paper feed roller, and to make the amount of biting highly accurate. be able to.
[0012]
According to a second aspect of the present invention, in the first aspect of the present invention, the paper feed roller and the transport roller are simultaneously activated by a paper feed command.
According to the second aspect of the present invention, the time until the paper feed roller actually picks up the paper varies depending on the amount of paper loaded on the hopper. However, by simultaneously starting with the paper feed roller, the time can be completely ignored and control is facilitated.
[0014]
According to a third aspect of the present invention, in the first or second aspect of the invention, the number of correction steps is set so as to enter a deceleration curve before the sheet is nipped by the conveyance roller.
According to the invention of claim 3 , if the amount of biting is increased, the paper is likely to be damaged, and if it is too small, it becomes impossible to correct the skew sufficiently. In particular, in the high speed mode, if the deceleration is started after the sheet is nipped by the conveyance roller, it cannot be stopped at the planned amount of biting, resulting in a variation in the amount of biting. Therefore, by starting the deceleration before the paper is nipped by the conveyance roller, the above-mentioned problem is eliminated and high-accuracy skew removal is performed.
[0015]
A fourth aspect of the invention is characterized in that, in the invention according to any one of the first to third aspects, the number of correction steps is set when the paper feed speed is in a high speed mode.
According to the fourth aspect of the present invention, since the transport roller is rotated by the number of correction steps corresponding to the paper feed speed, it is possible to obtain a high biting amount for each paper feed mode.
[0016]
According to a fifth aspect of the present invention, there is provided a recording apparatus that feeds a sheet by the paper feeding method according to any one of the first to fourth aspects, performs skewing of the sheet, and then feeds the sheet to the recording unit. It is characterized by sending and recording.
According to the invention of claim 5 , the print quality is improved by increasing the skew accuracy without damaging the paper.
[0017]
According to a sixth aspect of the present invention, in the fifth aspect of the present invention, from the number of steps when the distance from the paper detector to the leading edge of the paper bitten by the transport roller at a constant length is fed at a constant speed, the feed speed mode is changed. A correction step number obtained by subtracting the correction value in advance is provided in a table, and the correction step number is set according to the paper feed speed mode.
According to the invention of claim 6 , the software is simplified, and it becomes easy to cope with the specification change or the like.
[0018]
A seventh aspect of the invention is characterized in that, in the sixth aspect of the invention, different paper feed speed modes can be selected, and the correction step number is set when the paper feed speed is in the high speed mode.
According to the seventh aspect of the present invention, since the transport roller is rotated by the number of correction steps corresponding to the paper feed speed, it is possible to obtain a high biting amount for each paper feed mode.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing a main part of a recording apparatus according to the present invention.
First, an outline of paper feeding including skew removal and cueing will be described. The sheet feeding device ASF has a function of feeding a plurality of stacked sheets P one by one. As a main configuration, the hopper 1 that stacks and sets a plurality of sheets P, and the topmost hopper 1 are provided. A paper feed roller 2 that picks up and feeds the paper P one by one and a separation pad 3 that separates the paper that is double-fed together with the uppermost paper P are provided. The paper feed roller 2 has a side-view D shape having an arc portion 2a that contacts the paper P and a linear portion 2b that is separated from the paper P, and at least the surface thereof is made of a high friction material such as rubber. It is configured. One sheet P is fed to the transport roller 4 through the sheet guide 8 during one rotation while the arcuate portion 2a of the sheet feeding roller 2 is in contact with the separation pad. The paper guide 8 is provided with a paper detector PE that detects the leading edge of the paper P to be fed.
[0020]
The paper P is skewed by the cooperative action of the transport roller 4 and the driven roller 5. In FIG. 2, the skew removal is performed by causing the transport roller 4 to bite the paper P by a certain length L ₀ and then stopping the paper feed roller 2 so that the transport roller 4 is opposite to the illustrated direction, that is, the paper feed direction. A biting discharge method is employed in which the biting with the conveying roller 4 is canceled by rotating (reversing) in the direction. After the skew removal is completed, the paper feed roller 2 and the transport roller 4 are rotated to perform a cueing operation with a fixed length L, and then the paper P is sent to the area of the recording head 6 in accordance with the recording timing to perform recording. The recorded paper P is discharged by the discharge roller 7 shown in FIG.
[0021]
The cueing of the paper P after skewing is performed by setting the recording start position for the paper P, and is performed by controlling the rotation of the transport roller 4. In FIG. 3, when the cueing operation is started, both the paper feed roller 2 and the transport roller 4 rotate (forward rotation) in the paper feed direction, and the paper feed roller 2 makes the illustrated linear portion 2 b face the separation pad 3. The transport roller is stopped at a position (reset position), while the transport roller stops the paper P by feeding it a certain length L.
[0022]
An outline of sheet feeding in the recording apparatus of this embodiment will be described.
FIG. 4 is an explanatory diagram of the presence / absence detection of a sheet, FIG. 5 is an explanatory diagram of a biting operation at the time of skew removal applied to the recording apparatus of the present invention, and FIG. 6 is an explanatory diagram of an operation of skew removal applied to the recording apparatus of the present invention. FIG. 7 is an explanatory diagram of the cueing operation applied to the recording apparatus of the present invention, FIG. 8 is a paper feed control block diagram, and FIG. 9 is a flowchart of a paper detection routine in the recording apparatus of the present invention.
[0023]
First, paper feed control will be described with reference to FIG. The control unit 10 receives print information sent from the printer driver of the main control unit of the recording apparatus, determines the print information, and executes a paper feed sequence. The print information includes information on paper types (paper type information) such as plain paper, coated paper, OHP sheets, glossy paper, and glossy film, information on resolution (resolution information), and mode information on paper feed speed. The paper feed sequence includes an operation of rotating the paper feed roller 2 and the transport roller 4 at a normal paper feed speed, an operation of rotating the paper feed roller 2 at a paper feed speed (high speed mode) faster than the normal paper feed speed, It is configured by a combined operation such as an operation of rotating the roller 2 and the conveying roller 4 forward and backward at a normal sheet feeding speed.
[0024]
The control unit 10 controls the paper feed roller drive unit 11 and the transport roller drive unit 12 based on a paper feed sequence in response to a paper feed command from the main control unit of the recording apparatus. The paper feed roller drive unit 11 includes a stepping motor 13 (hereinafter referred to as an ASF motor), and drives the ASF motor 13 in a normal feed speed or high speed mode based on a drive signal from the control unit 10. The conveyance roller drive unit 12 is constituted by a DC motor 14 (hereinafter referred to as a PF motor), and records the paper P by the PF motor 14 at a normal feeding speed or high speed mode based on a drive signal from the control unit 10. Drive in the direction of the head 6 or drive in the opposite direction.
[0025]
The sheet feeding operation will be described with reference to the drawings. As for the rotation direction of the paper feed roller 2, the clockwise rotation shown in FIGS. 4 to 7 is referred to as “forward rotation”, and the rotation in the opposite direction is referred to as “reverse rotation”. As for the direction, clockwise rotation is referred to as “reverse rotation”, and rotation in the opposite direction is referred to as “forward rotation”. The rotation angle (ASF phase) of the paper feed roller 2 is detected by, for example, a phase detector including an encoder provided on the paper feed roller shaft. The phase detector outputs an open signal at the linear portion 2 b of the paper feed roller 2 and a close signal at the arc portion of the paper feed roller 2.
[0026]
For detection of the presence of paper, paper detection counters m and n are set (steps 100 and 101), the ASF motor 13 and the PF motor 14 are simultaneously activated, and the paper feed roller 2 and the transport roller 4 are rotated forward to feed the paper P. (Steps 102 and 103). It is determined whether or not the paper detector PE has detected the leading edge of the paper P. If there is no paper, the paper detection counter is incremented (m = m + 1, n = n + 1) (steps 104 and 105), and the paper detector is again detected. It is determined whether or not the PE has detected the leading edge of the paper P (step 106). When the paper P is not detected in the predetermined number (m1, n8) of paper detection, it is determined whether the paper jam or the hopper 1 is out of paper (steps 107 and 108). On the ASF motor 13 side, the ASF motor 13 is decelerated and stopped if there is no paper detection at the predetermined number of times n8 (step 109). On the other hand, on the PF motor 14 side, if there is no paper detection at the predetermined number of times m1, the PF motor 14 is decelerated and stopped. (Step 110). Thereafter, the process proceeds to the no-paper process (step 111).
When the presence of paper is detected in step 106, the ASF motor 13 and the PF motor 14 continue to rotate, and “next operation = normal” is set in the paper feeding device ASF (step 112). Move to the cue routine.
[0027]
Next, skew removal and cueing in the recording apparatus of the present invention will be described in detail.
FIG. 10 is a flowchart of skew removal, and FIG. 12 is a timing chart.
When the paper P fed in steps 100 to 106 in FIG. 9 passes through the paper detector PE, the constant speed state is maintained without stopping the ASF motor 13 and the PF motor 14 (step 200). When the leading edge of the paper P passes through the paper detector PE, the number of steps for driving each motor from the paper detector PE is set and controlled. That is, the ASF motor 13 is driven by n2 steps, while the PF motor 14 is driven by m1-a steps (steps 201 and 202). Number of steps of the motors from the paper detector PE corresponds to the distance from paper detector PE to the distal end of the sheet P which has stick length L ₀ eating the conveying roller 4.
[0028]
In this way, the PF motor 14 is set at a constant speed before paper detection, and the paper P is passed through the paper detector PE, so that the paper detection is temporarily stopped as in the conventional method, and then the ASF motor 13 and the PF motor 14 again. simultaneously start, there is no influence of the speed increasing curve characteristic of the PF motor than to drive a predetermined number of steps, the variation of the biting amount L ₀ becomes smaller.
[0029]
FIG. 13 shows the deceleration curve characteristics of each motor. If the PF motor 14 starts decelerating before the timing when the nip between the conveyance roller and the driven roller (the timing of biting) is caused by the deceleration curve characteristic of the PF motor 14, a distance difference ΔL is generated. In consideration of the distance difference ΔL, the number of correction steps (m1−a steps) obtained by subtracting several steps (a) from the number of steps (m1 steps) described above is set. Here, “a” is a correction value for subtracting several steps from the specified value m1 in accordance with the paper feed mode. FIG. 11 shows an example of correction values for the paper feed mode, and correction is performed by a1 steps in the high speed mode and a2 steps in the low speed mode.
In this way, by driving the PF motor 14 from the paper detector PE in m1-a steps, the paper feed amount of the transport roller 4 and the paper feed amount of the paper feed roller 2 can be made to coincide with each other with a certain length with high accuracy. L ₀ can be eaten.
[0030]
After biting the paper P, with the paper feed roller 2 stopped, the transport roller 4 is reversed by m2 steps, the paper P is discharged, and the skew is removed (step 203). Subsequently, the paper feed roller 2 is rotated to the reset position and waits. At the same time, the transport roller 4 is rotated forward in m3 steps to perform cueing (step 204).
The reset operation of the paper feed roller 2 will be described with reference to FIGS. 6 and 7. The paper feed roller 2 is rotated forward from the stopped state of FIG. 6 (step 205), and the phase detector in FIG. In response to the open signal of the phase detector when the straight line portion 2b faces the separation pad 3 (step 206), it is rotated forward by n1 steps to a standby position for making the rotation start position always constant (step 207).
[0031]
In the present invention, it is sufficient that the PF motor 14 is in a constant speed state before the leading edge of the paper P passes the paper detector PE, so that it is not necessary to simultaneously start the transport roller and the paper feed roller at the start of paper feeding. . In addition to the stepping motor, a DC motor can be used as the paper feed roller, and a stepping motor can be used as the conveyance roller in addition to the DC motor. These motors can be used in appropriate combinations.
[0032]
【The invention's effect】
According to the present invention, the speed of the DC motor is increased by driving the DC motor of the conveying roller at a constant speed before paper detection and driving the number of steps set by the paper detector when the paper passes the paper detector. There is no specific influence, the variation in the amount of biting is reduced, and the accuracy of skew removal is increased.
[Brief description of the drawings]
FIG. 1 is a side view showing a main part of a recording apparatus according to the present invention.
FIG. 2 is a schematic explanatory diagram of skew removal by a biting and discharging method.
FIG. 3 is a schematic explanatory diagram of cueing.
FIG. 4 is a schematic explanatory diagram of paper detection.
FIG. 5 is an explanatory diagram of a biting operation during skew removal in the paper feeding method of the present invention.
FIG. 6 is an explanatory diagram of skew removal in the paper feeding method of the present invention.
FIG. 7 is an explanatory diagram of cueing in the paper feeding method of the present invention.
FIG. 8 is a block diagram of paper feed control.
FIG. 9 is a flowchart of a paper detection routine in the paper feeding method of the present invention.
FIG. 10 is a flowchart of a skew removal routine in the paper feeding method of the present invention.
FIG. 11 is a diagram illustrating an example of a table representing a relationship between a paper feed mode and a driving step correction value of a PF motor.
FIG. 12 is a diagram illustrating a sheet feeding timing chart in the sheet feeding method of the present invention.
FIG. 13 is an explanatory diagram of deceleration curve characteristics of a stepping motor and a DC motor.
FIG. 14 is a flowchart of a skew removal / cueing routine in a conventional paper feeding method.
FIG. 15 is a diagram illustrating a sheet feeding timing chart in a conventional sheet feeding method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hopper 2 Paper feed roller 3 Separation pad 4 Carrying roller 5 Driven roller 6 Recording head 7 Discharge roller 8 Paper guide P Paper PE Paper detector ASF Paper feed device

Claims (7)

A paper feed roller driven by a stepping motor; a transport roller driven by a DC motor; and a paper detector disposed in a transport path between the rollers for detecting the paper to be fed. The paper fed by the forward rotation of the paper roller is bitten by the forward rotation of the transport roller, nipped by the paper feed roller and the transport roller, and then the paper feed roller and the transport roller are stopped. In the paper feeding method in which the feeding roller is reversed and discharged while the paper feeding roller is stopped to feed the paper after skewing,
Before the paper fed by the paper feed roller passes through the paper detector, the transport roller is rotated forward to a constant speed, and the stepping motor and the DC motor are respectively set based on the paper detection. to drive the number,
The number of steps for driving the DC motor set based on the paper detection is determined based on the number of steps for feeding the DC motor at a constant speed from the paper detector to the leading edge of the paper that has bitten on the conveyance roller at a constant speed. A sheet feeding method characterized by setting a correction step number obtained by subtracting several steps in consideration of a deceleration curve characteristic . Paper according to claim 1, characterized in that the simultaneous starting the feed roller and the conveying roller by the paper feed command. The number of steps of correction includes a sheet feeding method according to claim 1 or 2, characterized in that the paper is set to enter the deceleration curve before being nipped by the conveying roller. When the paper feed speed is in the high speed mode, the sheet feeding method according to any one of claims 1 to 3, characterized in that setting the number of the correction steps. A sheet is fed by the sheet feeding method according to any one of claims 1 to 4 , and the sheet is skewed and then cued and then fed to a recording unit for recording. Recording device. The table has a number of correction steps that is obtained by subtracting the correction value for each paper feed speed mode from the number of steps when feeding the distance from the paper detector to the leading edge of the paper bitten by the transport roller at a constant speed. 6. The recording apparatus according to claim 5, wherein the number of correction steps is set in accordance with a paper feed speed mode. 7. The recording apparatus according to claim 6 , wherein a different paper feed speed mode can be selected, and the number of correction steps is set when the paper feed speed is in the high speed mode.

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