JP2774572B2 - Drive control device for paper feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a sheet feeding device in a printing machine, a copying machine, and the like.

(Prior Art) A type of paper feeding device in a printing machine, a copying machine, or the like, a paper feeding device that feeds a sheet by rotating the top sheet of paper loaded on a sheet feeding table while contacting the peripheral surface thereof. Paper separating and conveying means for preventing double feeding of paper by a roller, a paper separating and conveying roller for conveying the paper fed by the paper feeding roller, and a friction separating plate elastically pressed against the peripheral surface of the paper separating and conveying roller And a registration roller configured to feed the paper separated and transported by the paper separating and transporting means to a paper processing unit (an impression cylinder in the case of a printing machine or a photoreceptor in the case of a copying machine) at a predetermined timing. Paper devices are known.

In addition, as a drive control device for controlling the driving of the paper feeding roller and the paper separating / conveying roller of this type of paper feeding device, a sensor for detecting the paper position is provided near the registration roller, and the sensor detects the paper position. At the time of the detection, the power supply to the drive motor such as the paper feed roller is stopped, or the drive transmission system of the clutch that transmits the rotation of the drive motor to the paper feed roller or the like is disconnected. Kimiaki
Japanese Patent Application Laid-Open No. 56-51977), or a sensor for forming a wide portion on a paper guide plate between the above-mentioned paper separating / conveying roller and the registration roller to allow bending of the paper, and detecting the bending of the paper in the wide portion. When the sensor detects the deflection of the sheet caused in the widened portion by being further conveyed in a state where the leading end of the sheet is in contact with the nip portion of the registration roller, the sheet separating and conveying roller is driven. A device for stopping (JP-B-62-157145) is known.

A paper feeder equipped with these conventional drive control devices, for example, combines a cam or a sector gear, or sets the amount of rotation of a paper feed roller or the like in advance by the number of rotations of a motor, etc. The paper can be transported more reliably than the paper feeding device that feeds the paper.

That is, in a paper feeding device such as a printing machine, a registration roller feeds a sheet toward an impression cylinder (a photoreceptor in a copying machine) at a predetermined timing. After the leading edge of the sheet reaches the nip portion of the roller, the sheet feeding roller and the sheet separating / conveying roller are driven for a short time to correct the skew during the sheet conveyance. Therefore,
In this type of sheet feeding device, the sheet is bent before the sheet is fed by the registration roller, and the nip of the registration roller at the leading end of the sheet is formed by the stiffness due to the bending of the sheet. The transfer force to the section can be obtained.

However, in a paper feeding device in which the paper transport distance is set to a fixed amount in advance, slippage occurs between the paper feed roller and the paper separation transport roller and the paper due to a variation in the friction coefficient between the papers, and the paper is transported. When the actual transport distance of the paper becomes shorter than the set transport distance, the driving of the paper feed roller and the like is stopped before the leading end of the paper reaches the nip portion of the registration roller, and a paper feed error occurs.

The drive control device stops the driving of the paper feed roller and the like after the sensor detects that the leading end of the sheet has reliably reached the nip portion of the registration roller, so that the above-described problem can be prevented.

(Problems to be Solved by the Invention) By the way, the drive control device of the conventional paper feeding device is provided with a paper feed roller or the like based on an output of a sensor for detecting the position of the leading end of the paper or a sensor for detecting the bending of the paper. Since the drive is controlled, it can be used only for a paper feeder with a substantially constant paper transport speed and thickness, so it can be applied to the paper feeder of a copying machine. There is a problem that it is unsuitable as a drive control device for a paper feeding device in which the transport speed and the thickness are variable.

That is, when this drive control device is provided in the paper feed device of a printing press, even if the driving of the paper feed roller or the like is stopped by the output of the sensor, the high speed of the paper is affected by the inertia of the roller drive system. A difference occurs in the transport distance of the paper after the rollers stop between printing and low-speed printing, and the deflection amount of the paper during high-speed printing is larger than the deflection amount of the paper during low-speed printing. However, there is a disadvantage that the sound generated by the expansion of the bent portion of the paper becomes noise at the time of high-speed printing. Further, when the thickness of the paper is large, it is difficult for the leading end of the paper to enter the nip portion of the registration roller under the same conditions as when the thin paper is conveyed, so that a paper feed error easily occurs. Here, if the roller drive time after the sensor detection is set long so that the thick paper is reliably transported, the transport amount for the thin paper becomes too large, and the leading end of the paper is likely to be broken or wrinkled. In addition, since thick paper has high rigidity and is unlikely to be bent, it is not possible to adopt a method in which the bent of the paper is detected by a sensor to control the driving of a paper feed roller or the like.

(Means for Solving the Problems) According to the present invention, in order to solve the above-mentioned problems, in the paper feeder, a sheet for detecting the leading edge and thickness of the sheet on a sheet conveying path upstream of the registration roller is provided. A paper feed unit and a paper separation / conveyance unit after the paper front / thickness detection unit detects the paper front end / thickness based on the output of the paper front / thickness detection unit and the paper conveyance speed. Is controlled by the sheet transport drive control means to an appropriate time required for the leading edge of the sheet to reach the nip of the registration roller.

(Operation) According to the present invention, the driving time of the paper feeding unit and the paper separating / conveying roller, that is, the paper transport amount, is determined based on the output of the paper leading edge / thickness detecting unit and the paper transport speed. It is controlled so as to be an appropriate amount according to the transport speed.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to a sheet feeding device of an offset printing press.

The sheet feeding device in the offset printing machine includes a sheet feeding unit 1, a sheet separating and conveying unit 2, a registration roller 3, a sheet guide plate 4, and the like.

The paper feeding unit 1 is provided with a paper P difficultly placed on a paper feeding table (not shown).
, A drive system for driving the paper feed roller 11, a paper elevating device for elevating and lowering the paper P loaded on the paper feed table, and the like.

The sheet separating and conveying means 2 includes a sheet separating and conveying roller 21 for conveying the sheet fed by the sheet feeding roller 11, and a friction separating plate 22 for elastically pressing the peripheral surface of the sheet separating and conveying roller 21.
And a drive system for the sheet separation / conveyance roller 21.

The drive system of the paper feed roller 11 in this paper feed device is configured to also serve as the drive system of the paper separation / conveyance roller 21.
It comprises a pulse motor 51, timing pulleys 52, 53, 54, 55, timing belts 56, 57 and the like.

The timing pulley 52 is connected to the output shaft 51a of the pulse motor 51.
It is fixed to. The timing pulley 53 is mounted on an end of the support shaft 21a of the sheet separating and conveying roller 21 via a one-way rotating clutch. Each of these timing pulleys 5
2,53 are connected by a timing belt 56,
When the pulse motor 51 is driven, the paper separating and conveying roller 21 is driven to rotate counterclockwise in FIG.
The other timing pulley 54 is mounted on the support shaft 21a in the vicinity of the sheet separating and conveying roller 21. Still another timing pulley 55 is mounted on the support shaft 11a of the paper feed roller 11. These timing pulleys 54 and 55 are connected by another timing belt 57, and the sheet separation and conveyance roller 21 is driven to rotate as described above, thereby driving the sheet feeding roller 11 to rotate in the same direction. Each spindle 11a,
21a is rotatably supported by a support member 58 (see FIG. 2) provided in the apparatus main body.

On the other hand, the registration roller 3 is composed of a pair of rollers, and these rollers have a support shaft 3a (see FIG. 2) rotatably mounted on a side plate of the apparatus main body by a driving means (not shown). By being driven at the timing,
In FIG. 1, they are driven in the directions of the arrows.

The paper guide plate 4 includes a paper separation / conveyance roller 21 and a friction separation plate.
22, a nip portion of the registration roller 3, and a contact portion between the blanket cylinder 5 and the impression cylinder 6 of the printing press.
Is formed by a pair of flat plates.

The drive control device according to the present invention includes a sheet leading end / thickness detecting unit 60 for detecting the leading end and thickness of the sheet P, and a sheet conveying drive controlling unit 70.

The paper leading edge / thickness detecting means 60 is disposed in the paper transport path A where the upstream of the registration roller 3 is located.
At the portion of the paper guide plate 4 where the upstream of the registration roller 3 is located,
A light source 60a disposed opposite to the paper transport path A
And a light-receiving element 60b. The sheet leading edge / thickness detecting means 60 (hereinafter simply referred to as a sheet sensor) may be constituted by a contact type angle sensor. The paper sensor 60 has a function of determining the presence or absence of the paper P and a function of determining the thickness of the paper P. Here, the determination of the presence or absence of the sheet P is performed based on whether or not the output value (generally, the resistance value) of the sheet sensor 60 has changed.
Is determined based on the magnitude of the output value of the paper sensor 60 (the magnitude of the change). The output of the paper sensor 60 is provided to a paper transport drive control means 70 (hereinafter simply referred to as a control means).

The control means 70 requires the drive time of the paper feeding means 1 and the paper separating and conveying means 2 based on the output of the paper sensor 60 and the conveying speed of the paper P for the leading edge of the paper to reach the nip portion of the registration roller 3. Control at appropriate time.

Here, when the transport speed of the paper P is normally set in advance at two speeds, high speed and low speed as in a printing press, the transport mode of the paper P is set to the high speed mode or the low speed mode. The mode may be specified, and the information may be input to the control means 70. Further, in the case of a printing machine or a copying machine which does not designate such a transport mode of the paper P, it is necessary for the paper sensor 60 to output the paper leading edge detection signal after the paper P feed start signal is output. The time may be measured by a timer built in the control means 70, and the transport speed of the sheet P may be calculated from the measured value. Therefore, this control means 70 controls whether the sheet P is a thin sheet and is being conveyed at a low speed (hereinafter referred to as a thin sheet low speed mode), and the sheet P is a thick sheet and is being conveyed at a low speed (hereinafter this is a thick sheet). Low-speed mode), paper P
Corresponds to either a mode in which the sheet P is thin paper and is conveyed at a high speed (hereinafter referred to as a thin paper high-speed mode) and a case where the sheet P is a thick paper and is conveyed at a high speed (hereinafter referred to as a cardboard high-speed mode). The sheet feeding unit 1 and the sheet separating / conveying unit 2 are driven for an appropriate driving time according to each mode, based on the output of the sheet sensor 60 and the conveying speed of the sheet P. The specific drive control of the paper feeding means 1 and the like is executed by giving an output preset in accordance with each of the above modes to the pulse motor 51.

That is, in FIG. 1, when the sheet feed start signal is output and the pulse motor 51 is driven, as described above,
At the same time as the paper feed roller 11 rotates counterclockwise via the drive system, the uppermost paper P stacked on the paper feed table is pressed against the peripheral surface of the paper feed roller 11 and the paper P is separated. The paper is fed toward the transport unit 2. The fed paper P is prevented from being fed multiple times by the rotation of the paper separation / conveyance roller 21 and the cooperation of the friction separation plate 22, and then the paper guide plate 4
Is conveyed toward the registration roller 3 along the path. When the leading end of the conveyed sheet P is detected by the sheet sensor 60, the control unit 70 determines the transfer mode of the sheet P based on the transfer speed and thickness of the sheet P as described above. . Here, for example, when the transport mode of the paper P is the thin paper high-speed mode, the power supply to the pulse motor 51 is stopped after a predetermined time, and the rotation of the paper feed roller 11 and the paper separation transport roller 21 is stopped. Here, the separation distance from the sheet detection position of the sheet sensor 60 to the nip portion of the registration roller 3 is determined by the sheet sensor 60 when the thinnest sheet P is transported at the highest speed (hereinafter referred to as a reference mode). The distance is set in advance so as to be equal to or slightly shorter than the distance that the sheet P is conveyed by the inertia of the drive system when the power supply to the pulse motor 51 is stopped at the same time that the leading end is detected.

The power supply stop timing of the pulse motor 51 in each of the above modes is determined to be an appropriate time set in advance based on the above-described reference mode. That is, in the thin paper high-speed mode, after the leading edge of the paper P reaches the nip portion of the registration roller 3, the paper P is slightly conveyed to cause a small bending. Since the rotation speed of the roller 3 also decreases, the deflection amount of the sheet P reaching the nip portion of the registration roller 3 becomes equal to or slightly larger than that in the thin paper high-speed mode, and in the thick paper high-speed mode. In this case, the sheet P is unlikely to bend, and the registration roller 3 at the leading end of the sheet is more likely to enter the nip portion. Therefore, in the thick paper low speed mode, the timing is slower than in the thin paper high speed mode. The power supply to the pulse motor 51 is delayed at the latest timing because the entry of the paper P into the nip portion of the registration roller 3 is most likely to be uncertain. Driving time is controlled by the control means 70 so as to stop.

The sheet P conveyed as described above waits in a state where the leading end of the sheet P has surely entered the nip portion of the registration roller 3. Then, as is well known, the registration roller 3 is driven at a predetermined timing so that the paper P is moved between the blanket cylinder 5 and the impression cylinder 6 (in the case of a copying machine, between the photosensitive member and the transfer device). ), The image formed on the peripheral surface of the blanket cylinder 5 by the plate cylinder 7 is printed on a sheet P, and then discharged onto the sheet discharge table 8.

In the above-described embodiment, the pulse motor 51 is used as a driving source for the paper feeding means 1 and the like. An electromagnetic clutch may be disposed between the units 1 and the like, and the electromagnetic clutch may be disconnected at the timing described above to control the driving time of the sheet feeding unit 1 and the like.

(Effects of the Invention) According to the present invention, noise generated due to the extension of the bent portion of the sheet when the registration roller is started is eliminated, and the occurrence of a sheet feeding error, a sheet break, and a wrinkle are prevented.

[Brief description of the drawings]

FIG. 1 is a schematic side view of an embodiment of the present invention, and FIG. 2 is a partial plan view of FIG. DESCRIPTION OF SYMBOLS 1 ... Paper feeding means, 2 ... Paper separation and conveyance means, 3 ... Registration rollers, 4 ... Paper guide plate, 60 ... Paper tip / thickness detection means, 70 ... Paper conveyance drive control means, A ... Paper transport path, P ... paper.

Claims (1)

(57) [Claims] A sheet feeding unit for feeding sheets stacked on a sheet feeding table; a sheet separating and conveying unit for preventing double feeding of the fed sheets; And a registration roller that feeds the sheet at the timing of (1).
Thickness detecting means, and the paper feeding means and the paper separating / conveying means after the paper leading / thickness detecting means detects the paper front end based on the output of the paper front / thickness detecting means and the paper conveying speed by the paper separating / conveying means. And a sheet transport drive control means for controlling the drive time of the sheet to an appropriate time required for the leading edge of the sheet to reach the nip portion of the registration roller.