JP2784675B2 - Automatic document feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an automatic document feeder in a recording apparatus such as an electrophotographic copying machine, and more particularly, to adjust a document discharge timing to each original size. The present invention relates to an automatic document feeder that automatically adjusts and efficiently performs an operation of discharging a document in combination with exposure.

[Conventional technology]

An automatic document feeder (hereinafter referred to as ADF) of a copier is a device that automatically conveys the document set on the document tray to the document table, makes the copier copy, and then discharges it to the output tray. It is. This apparatus is suitable for high-speed copying of a large number of sheet documents. In addition, especially in recent copying machines, the copy speed has been increased in order to improve the copying performance.
(0 to 1200 mm / sec), and if the document is discharged at this speed, there is a problem that the document is discharged irregularly onto the discharge tray or jumps out.

Various proposals have been made for these measures. For example, Japanese Patent Application Laid-Open No. 61-178363 (conventional example 1) has a paper sensor that detects the passage of a document immediately before a paper discharge roller, and rotates the paper discharge roller when the paper sensor detects the rear end of the document. It is characterized by having a discharge roller deceleration means for reducing the speed.

In Japanese Patent Application Laid-Open No. Sho 62-12564 (conventional example 2), the rotation of the document discharging means is controlled to a first discharging speed which is the same as the document conveying speed and a second discharging speed which is lower than the first discharging speed. Has switching means capable of switching between the two.

Japanese Patent Application Laid-Open No. 62-70159 (conventional example 3) discloses that a trailing end of a document to be discharged is detected by a sensor, and a discharging speed is reduced by a brake and a clutch. .

Further, Japanese Patent Application Laid-Open No. 62-111854 (conventional example 4) discloses that the conveying speed is reduced for a certain period of time after the trailing edge of a document is detected.

The above countermeasure is to slow down the output document,
OPM (ADF feeds per minute in ADF) and CPM (Copies per minute in copier)
To increase copy productivity.

From another viewpoint, it is conceivable to improve the copy productivity by efficiently feeding and discharging the original in combination with the exposure in a timely manner. Japanese Patent Application Laid-Open No. Sho 62-47 discloses these conventional examples.
Japanese Patent Application Publication No. 636 (Conventional Example 1) discloses a method in which two originals are automatically sent in sequence onto an original platen, and each original is conveyed by a detection unit for a set time and aligned with a predetermined mounting position. is there. Japanese Patent Application Laid-Open No. 60-36236 (Conventional Example 2) discloses a method in which the trailing end of a conveyed document is stopped in accordance with a document stop position, and paper feeding is started before the discharged document reaches a discharge roller. In addition, it is disclosed that when the next fed document stops at the reference position, the trailing end of the discharged document can reach the discharge roller, and the feeding / discharging process can be expedited. JP-A-61-32836 (conventional example 3)
Documents of various sizes are taken at appropriate intervals, transported in advance to the standby position in advance, and after the exposure of the previous document is completed,
Each original is conveyed at the same time and the next original in the standby state is moved to the copy position.The original can be conveyed sequentially with the minimum travel of the conveyor belt regardless of the size of the original. It is disclosed that copying can be performed efficiently.

These conventional ADF document exchange operations on the platen glass are methods in which the next document is sent out from the stack unit and stopped after the paper ejection sensor detects that the document on the platen has been ejected.

A method in which the previous document is discharged before the conveyance belt for conveying the document stops (the document is fed).

There is known a method in which a document passing path is switched back on a glass surface of a document table and a next document is passed through the glass surface while a previous document is being discharged from the glass surface.

However, and in the aforementioned copy productivity
Improving OPM / CPM has functional difficulties. Describing this, assuming that the copy speed of the copy is 45 sheets per minute and the linear speed of the drum is now 260 mm / sec, and the transport linear speed is calculated with the target of 100% copy productivity, (I) the ownership time of one copy Is 60/45 = 1.333sec, and (II) Exposure time (as A4 size) is 210mm / 260mm = 0.808sec. (III) Transportable time ... 1.333−0.808 = 0.525sec. However, i. Ii The distance from the glass end surface to the discharge port is 240 mm. (IV) Transport speed: (450 mm + 240 mm) /0.525 = 1.314 m / s. It can be seen that a high linear velocity of 1.3 m / sec or more is required even if not. It can be said that there is a considerably high speed at the beginning of this speed even if the speed of recent copying machines is increased to about 1.0 to 1.2 m / sec.

However, increasing the document conveying speed causes various problems such as an increase in the size of the motor, an increase in power consumption, an increase in the degree of document breakage, and a decrease in document separation performance.

In the case of (1), although the copy productivity is high, the two originals A and B are different between the original platen glass and the transport belt, that is, when the A original is discharged, the B original is inserted. It is considered that there is a drawback that a manuscript is protruded and a jam is easily caused by the manuscript. In addition, since the A original is discharged during the exposure after the B original is inserted, a clutch which turns off the driving of only the conveying belt or a dedicated conveying belt motor is required, resulting in a high cost.

Also, considering the size of the original to be copied,
Now, in the case of feeding a large size document A3 size in the longitudinal direction, and in the case of feeding a small size document A4 size in the short direction, insert the document from one end of the glass surface and use the ADF on the insertion side reference surface (stopper). Exchange time is the same. Since the exposure time is twice as long in A3 size as in A4 size, the CPM in A3 size is about 60% of that in A4 size.

Therefore, the copy productivity (OPM / CPM) of the large-size original A3 is higher than that of the small-size original. However, since the A4 size document is generally a normal size, unless the OPM close to the CPM of the electronic copying machine, that is, the OPM / CPM is high, the practical performance must be inferior.

[Problems to be solved by the invention]

The ADF takes in the document from one side of the automatic document feeder placed on the image exposing section of the copier and sends it out to the other side. The document reference surface (stopper position) is located at the entrance side. In ADF, where size documents are fed in the longitudinal direction and small size documents such as A4 size are fed short, especially in order to improve copy productivity of 210 mm (A4 size) or less small size documents, An object of the present invention is to provide an ADF that does not impair the practical performance of an electronic copying machine without particularly increasing the document conveying speed.

[Means for solving the problem]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problem in the automatic document feeder and to improve the number of copies to be processed.

The automatic document feeder of the present invention to achieve the above object is mounted on an image exposure unit of a copying machine, sequentially transports a plurality of sheet-shaped documents to the image exposure unit, stops the document at the exposure position,
An automatic document feeder that carries out scanning exposure by moving the optical system of the copying machine, and then carries out the document to a document discharge table.The document is loaded onto the image exposure unit by a paper feeding unit. The rear end of the document is stopped by aligning the rear end of the document with a stop provided at the end of the paper supply unit at the exposure position, and after scanning exposure is performed by the optical system of the copying machine, the document is transferred to the paper supply unit. In the automatic document feeder that discharges to the opposite side, if the length of the document in the feed direction exceeds half the maximum size that can be copied by the copier, When the distance from the trailing edge of the original to the trailing edge of the next original is constant, and when the unexposed next original stops at the exposure position, the conveyance is controlled so that the preceding original that has been scanned and exposed is discharged. And the length of the original in the feed direction is In the case of a document of 1/2 or smaller size, the distance from the leading edge of the preceding document to the trailing edge of the next document is constant regardless of the document size. Once the document is stopped at a position where it does not protrude from the outside device, the conveyance of the next document is started until the preceding document is temporarily stopped, and the scanning exposure of the next document is performed while the preceding document is temporarily stopped. It is characterized in that it is controlled so that:

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a document conveying path of the automatic document feeder according to the present invention, FIG. 2 is an external perspective view of a copier equipped with the automatic document feeder, and FIG. FIG. 4 is a schematic diagram of the entire drive system configuration of the present apparatus, FIG. 5 is a schematic diagram of a document conveying path at the time of duplex document copying, and FIG. 6 is a time chart of the present invention. It is.

First, the structure and operation of the automatic document feeder will be described with reference to FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG.

An automatic document feeder (ADF) according to the present invention is installed on a copying machine main body 1 and feeds a document from a bundle of documents placed on a document tray 11 onto a platen glass 2. A transport unit 20 for transporting the original fed from the original feed unit 10 to a predetermined position (image exposure scanning position) of the original platen glass 2 on the original platen; 20
And a document discharge section 30 for discharging the document sent out of the printer onto a discharge tray 39.

Now, FIGS. 3 and 4 will be described from the driving system.
In the center is a drive source motor M, and to the left of it is a paper feed unit 10,
A drive system for the transport unit 20 is provided at the center, and a document discharge unit 30 is provided at the right side.
The toothed pulleys P1 and P2 are rotated via the gears G0 and G1 using the motor M as a drive source, and are separated by the toothed belts B1 and B2 into the document feeder 10 and the document discharger 30, respectively. The feeding unit 10 includes these rollers of the separation belt roller 13A, the paper feeding roller 15, and the conveyance belt driving roller 23 as gears G2, G3, G.
4, driven by G5, G6.

A clutch K1 is built in the gear G6 at the shaft end of the separation belt roller 13A. The clutch G1 is free except during the sheet feeding rotation for separating and feeding only one document from the document bundle on the document tray 11. Similarly, the delivery reversing roller 31 has the gears G0, G1 and the pulleys P1, P4, P
5 Driven via gears G7 and G9, the gear G9 is provided with a one-way clutch K2, and the gear G7 is provided with a one-way clutch K3. As a result, the toothed belts B1 and B2 rotate in the directions indicated by the arrows, respectively.

In the schematic diagram of FIG. 5, the automatic document feeder of the present invention has a feature that double-sided copying of a double-sided document is also possible.
When the surface exposure (copying) is completed, the path of arrows S1 and S2 is taken, and the sheet is reversed without being discharged even after passing through the sheet discharge reversing roller 31 and the pinch rollers 32 and 33. For exposure (backside copying), the sheet is again fed back to the platen glass 2 and exposed (copied), again taking the path of arrows S1 and S2, and this time passing through the paper discharge reversing roller 31, pinch rollers 32 and 33, S3
This shows a state where the paper is discharged onto the paper discharge tray 39 by the paper discharge roller 35 through the path of FIG.

Next, a description will be given of automatic document feeding when the size of the document exceeds 1/2 of the maximum size in the automatic document feeding apparatus of the present invention.

A document tray 11 that is set to protrude to the left side of the copying machine body 1 has a document D that exceeds 1/2 of the maximum size.
Is set. When the copy button (not shown) of the document D is pressed, the sheet feeding solenoid SD1 is operated, the movable guide plate 12 jumps up, and the document D is pressed against the separating belt 13. Next, by the driving of the motor M, the separation belt 13 starts to rotate in the direction of the arrow connected to the drive source by the separation belt roller 13A, and only the uppermost original Dn is fed out in cooperation with the stop roller 14. When the leading edge of the document D reaches the nip exit of the sheet feeding roller 15 rotating in the direction of the arrow, the sheet feeding clutch K1 is turned off by the detection signal of the document size detection sensor PS1, and the driving force transmission of the separation belt 13 is stopped. After the cut, the document rotates free, but only the preceding document Dn is conveyed by the feed roller 15.

The original Dn conveyed by the paper feed roller 15 is an original
After passing above the stopper plate 3 for positioning the rear end of Dn, it reaches the pressure contact position between the document table glass 2 installed on the upper surface of the copying apparatus main body 1 and the transport belt 21 of the document transport section 20 and further rotates. It is transported by the frictional force of the transport belt 21. The transport belt 21 is stretched between a rotatable drive roller 23 and a driven roller 24 on bearing plates fixed to both side walls of the housing 22, and can be rotated forward and backward by a motor M. The lower running surface of the conveyor belt 21 is pressed against the platen glass 2 by pressing rollers 25, 26, 27, 28. When the size of the document Dn is automatically detected by passing the leading and trailing edges of the document Dn through the document size detection sensor PS1, the document size is determined at a predetermined position of the document after the trailing edge of the document passes through the stopper plate 3. , The motor M changes from forward rotation to reverse rotation, and moves the excessively original Dn backward to strike the rear end of the original against the stopper plate 3 to stop the movement. Thereafter, exposure (copy) is performed by optical scanning in the copying machine body 1.

After the exposure is completed, the motor M is turned on, and the document Dn is conveyed,
When the trailing end reaches the position where the document discharge detection sensor PS2 is installed, a suction timer is started so that the discharge unit solenoid SD2 is operated to suction, the time is up, the discharge unit solenoid SD2 is turned on, and the discharge roller 35 is rotated to rotate the document Dn. And is discharged by a discharge roller 35. These manuscripts Dn, Dn
The dimensional relationship of +1 is AL = b. Here, A is the distance from the stopper plate 3 to the paper discharge roller 35, L is the length of the document Dn in the longitudinal direction, and b is the distance between the documents. That is, the manuscript
When Dn + 1 stops at the exposure position, the preceding document Dn has been discharged onto the discharge tray 39 through the discharge rollers 35.

Next, a case where the size of a document to be copied is a small size document dn having a maximum size of 1/2 or less will be described with reference to FIGS. 7, 8, and 9. FIG.

For small-size originals dn that are 1/2 or less of the maximum size,
Since the original is sequentially exposed (copied) through the same process as n, the description is made from the point where the first original is conveyed to the platen glass 2 surface. Now, when the preceding original dn is conveyed and the trailing edge of the original collides with the stopper plate 3 to stop the movement, then exposure (copy) is performed by optical scanning inside the copying machine main body.

After the exposure is completed, the motor M is turned on, the discharge reversing roller 31 rotates, and the document dn is conveyed. In this case (when the size is 1/2 or less), the document dn is It is stopped on the conveyance path between the base glass 2 and the front of the paper discharge roller 35. Then, the next document is stopped so as to maintain the interval b with the next document dn to be stopped.
The feed clutch K1 is turned on to convey d _{n + 1,} and when the feed clutch K1 is reached, the feed clutch K1 is turned off, the length of the document is detected, and the separating belt 13 becomes free. d _{n + 1} is transported to the exposure position. When the original d _{n + 1} is further exposed (copied), the original is discharged by the transport belt 21 to the original discharge section.
The document dn that has been conveyed to and stopped earlier is conveyed, and when the trailing end reaches the position where the document discharge sensor PS2 is installed, a suction timer is started so that the discharge unit solenoid SD2 operates to suction, and the time is set. As soon as the paper ejection unit solenoid SD2 is turned on, the paper ejection roller 35 is rotated and the document d
n and is discharged by the discharge roller 35. Note that the dimensional relationship in this case is A-2L = b, and b is set in the range of these two expressions together with AL = b described above (for a document exceeding 1/2 of the maximum size). You can say what you need to do. When L (document size) is determined by these formulas, b (document interval) is determined. Therefore, when the document to be conveyed and inserted is detected as A4 size by the document size detection sensor PS1, b is determined. Is set, and the value of b for an A5-size document is set. This can be stored in a copying machine and used. Further, the range of the dimension A is desirably L + b <A <2L + b. That A is within the range of the above equation means that
This is necessary in order to prevent the front end of the preceding document from being protruded while being pressed by the paper discharge roller 35 during exposure (copying).

FIG. 10 is a table showing the availability of each size of the original according to the present invention.
A horizontal size and a B4 horizontal size are taken, and a horizontal item indicates whether or not each document size can be used. A column indicates that the document cannot be used, and a column indicates each usable document size.

〔The invention's effect〕

As described above, according to the automatic document feeder of the present invention, not only the document transport time can be shortened, but also the separation performance can be stabilized and the document transport can be smoothly performed due to the low-speed separation during document transport. This is effective in preventing the document from being damaged or the front end of the document being damaged.
In addition, the load on the motor can be reduced, power consumption can be reduced, and a small motor with low torque can be provided. In particular, document conveyance is based on the ADF start signal from the main body of the copying machine, which starts the motor, clutch, solenoid, and various timers, and is controlled by the passage detection means of the preceding document.
Advantageously, the control program is simple and clear, the number of malfunctions is small, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a document feed path of an automatic document feeder according to the present invention, FIG. 2 is an external perspective view of a copier equipped with the automatic document feeder, and FIG. FIG. 4 is a schematic diagram of the entire drive system configuration of the apparatus, FIG. 5 is a schematic diagram of a document conveying path at the time of duplex document copying, and FIG. FIGS. 7 and 8 are schematic diagrams showing a document conveying process of the present apparatus, FIG. 9 is a schematic diagram of a document interval dimension condition of the present apparatus, and FIG. 6 is a chart showing the availability of sizes. DESCRIPTION OF SYMBOLS 1 ... Copier main body, 2 ... Original platen glass 3 ... Stopper plate, 10 ... Supply section 11 ... Original tray, 12 ... Movable guide plate 13 ... Separating belt, 15 ... Supply roller 20 … Conveying unit, 21… Conveying belt 23… Drive roller, 24… Driving roller 30… Document discharge unit, 31… Discharge reversal roller 32,33… Pinch roller, 34… Crimping lever 35… … Discharge roller, D… Large size document G1 to G10… Gear, d… Small size document K1… Feeding clutch K2, K3… One-way clutch M …… Motor P1 to P7… Driving pulley PS1 Document size detection sensor PS2 Document discharge detection sensor SD1 Paper feeding solenoids SD2, SD3 Discharge solenoid S S. Forward arrow for double-sided document b. Interval, R. Backward arrow for double-sided document L ...... The length of the manuscript

Claims (1)

(57) [Claims] 1. A copying machine mounted on an image exposing section of a copying machine, a plurality of sheet-shaped originals are sequentially conveyed to the image exposing section, the original is stopped at an exposure position, and scanning is performed by moving an optical system of the copying machine. An automatic document feeder for discharging the document to a document discharge table after exposure is performed, wherein the document is loaded onto the image exposure unit by a paper supply unit, and an end on the paper supply unit side at the exposure position is provided. In the automatic document feeder, the document rear end is stopped by aligning the rear end of the document with the stop provided in the copying machine, and after scanning exposure is performed by the optical system of the copying machine, the document is discharged to the side opposite to the paper feeding unit. If the length of the original in the feed direction exceeds half the maximum size that can be copied by the copier, the length of the original from the trailing edge of the preceding original to the trailing edge of the next original regardless of the original size When the unexposed next document stops at the exposure position, the distance to In the case of a document whose size in the feeding direction of the document is equal to or less than 1/2 of the maximum size that can be copied by the copying machine, the conveyance is controlled so that the scanning-exposed preceding document is discharged. Regardless of the document size, the distance from the leading edge of the preceding document to the trailing edge of the next document is fixed, and the preceding document after scanning exposure is temporarily stopped at a position that does not protrude outside the apparatus on the downstream side in the transport direction from the exposure position. The automatic document feeder is characterized in that the conveyance of the next document is started before the preceding document is temporarily stopped, and the scanning and exposure of the next document are performed while the preceding document is temporarily stopped. apparatus.