JP2926416B2 - 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 document size. The present invention relates to an automatic document feeder that automatically adjusts an original and performs an operation of discharging an original 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 copying speed has been increased in order to improve the copying performance.
000-1200mm / sec).

In addition, to efficiently feed and discharge originals in a timely manner, and to improve copy productivity, which is the ratio of opm (number of original feeds per minute in ADF) to cpm (number of copies per minute in copier). Can be considered. Japanese Unexamined Patent Application Publication No. 62-47636 (Prior Art 1) discloses a conventional example in which two originals are automatically sent out sequentially to an original platen, and each original is conveyed for a set time by a detecting means. This is a method of matching a predetermined mounting position. Also, Japanese Patent Application Laid-Open
Japanese Patent No. 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. It is disclosed that when the document stops at the reference position, the trailing end of the discharged document can reach the discharge roller, and the supply / discharge process can be expedited. Japanese Unexamined Patent Publication No. 61-32836 (Conventional Example 3) discloses that even if originals of various sizes are set at appropriate intervals, they are sequentially conveyed to a standby position in advance, and each original is exposed after the exposure of the previous original is completed. To move the next document in the standby state to the copy position at the same time, so that the document can be transported sequentially with the minimum travel of the transport belt regardless of the size of the document, which improves efficiency. It is disclosed that copying can be performed.

In the conventional document exchange operation on the platen glass by the conventional ADF, the next document is sent out from the stack unit and stopped after the discharge sensor detects that the document on the platen has been discharged.

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

A method of switching back the document passing path on the platen glass surface, and passing the next document to the glass surface while the previous document is being ejected from the glass surface.

Etc. are known.

However, and in the aforementioned copy productivity
It is difficult to raise the opm / cpm in terms of functionality, and this can be described as follows. Assuming that the copy speed is 45 sheets per minute, the drum linear speed is now 260 mm / sec, and the copy productivity is 1
When the transport linear velocity is calculated with the target of 00%, (I) the required time for one copy is 60/45 = 1.333sec, and (II) the exposure time (as A4 size) is 210mm / 260mm = 0.808se
c (III) Possible transport time: 1.333-0.808 = 0.525 sec. However, i The length of the platen glass is 450 mm.

ii The distance from the glass end face to the discharge port is 240 mm.

(IV) Conveyance speed: (450mm + 240mm) /0.525=1.314m/s Therefore, 1.3m / s without considering the start-up and stop of the motor rotation and the margin due to switchback of the document.
It turns out that a high linear velocity of ec or more is required. It can be said that this speed is considerably high even if the speed of recent copiers 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, 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 folded original is generated and a jam is easily caused by the folded original. 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.

[Problems to be solved by the invention]

As described above, high copy productivity can be achieved without increasing the document conveyance speed particularly much, and the motor can be driven by one motor.
The present invention provides an ADF that can be used at any time and does not easily cause a jam even with a folded document.

[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.

To achieve the above object, the automatic document feeder of the present invention sequentially feeds a plurality of sheet-like originals to an image exposure unit, stops the original in the image exposure unit, performs scanning exposure, and scans the exposed original. In an automatic document feeder, which is carried out to a document discharge table by a document discharge means provided downstream of a document table glass in an image exposure section, the document discharge table is supplied from a document supply section via the image exposure section. A single drive motor is arranged in a transport mechanism for transporting the original up to the original, and the drive motor is connected to the paper feeder and the original discharger of the original feeder. (N-1) The distance to the rear end of the original is changed by recognizing the size of the original to be conveyed, and at least in the case of the minimum size original in the feed direction, from the stop position of the image exposure unit of the original. Document output position The following conditional expression (A / 2) −L <b <A−2L (where A is the distance from the rear end position of the document stopped at the image exposure unit to the discharge position) , L is the length of the document in the transport direction,
(b is the distance between the original and the preceding original), and the conveyance of the original is controlled so that the N-th original fed from the original feeder is exposed while the N-th original is being exposed. N-1) Stop the first document in the transport path,
(N-2) An automatic document feeder wherein the discharge of the first document is completed.

〔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 overall 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. The structure and operation of the automatic document feeder will be described with reference to these drawings.

The automatic document feeder (ADF) of the present invention is shown in FIGS.
As shown in the figure, a document feeder 10 which is grounded on the main body 1 of the copier and feeds one document from a bundle of documents placed on a document tray 11 onto the platen glass 2; A transport unit 20 for transporting the original fed from 10 to a predetermined position (image exposure scanning position) of the original table glass 2 on the original table, and discharging the original sent from the original transport unit 20 after the image exposure is completed. The document discharge section 30 is discharged onto a paper tray 39.

Now, FIGS. 3 and 4 will be described from the drive 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 with the motor M as a drive source, and are separated by the toothed belts B1 and B2 into the document discharge section 30 and the document feed section 10, respectively. The feeding unit 10 includes a separation belt roller 13A, a feeding roller 15, and a conveyance belt driving roller 23 from the paper feeding unit side in a gear train G6, G5, G.
4, driven by G2.

A clutch K1 is built in the gear G6 at the shaft end of the roller 13A for the separation belt, and is free except when the paper is rotated. On the other hand, the discharge reversing roller 31 of the document discharge section 30
Are driven through gears G0, G1 and pulleys P1, P4, P5 or gears G7, G9, a one-way clutch K2 is mounted on the gear G9, and a one-way clutch K3 is mounted on the gear G7. As a result, the belts B1 and B2 rotate in the directions indicated by the arrows.

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 copying is completed, the sheet takes the path indicated by arrows 1 and S2, is conveyed in reverse without being discharged even after passing through the sheet discharge reversing roller 31, and the pinch rollers 32 and 33, takes the path indicated by arrows R1 and R2, and exposes the second side (back side). For copying, the sheet is again fed back to the platen glass 2 and exposed (copied), and takes the paths of arrows S1 and S2 again. This time, the path of arrow S3 passes through the paper discharge reversing roller 31, the pinch rollers 32 and 33. This shows a state where the paper is discharged onto the paper discharge tray 39 by the paper discharge roller 35.

FIG. 6 shows a time chart of the document feeding and transporting process of the apparatus, which shows the operation described in FIGS. 1, 3 and 4 with the passage of time. In the left vertical column, the document size detection sensor, discharge detection sensor, drive motor, timer, paper feed clutch and other operating elements are arranged, and the ADF start signal (copy button) is pressed in the right horizontal column By the first manuscript (Dn
A diagram showing how the above-described operating elements correspond to the process in which copying starts from the first sheet and then (Dn + 1) and (Dn + 2) are copied over time. It is. Now, this will be described in detail with reference to FIG. 1, FIG. 2, and FIG.

An original D is set on an original tray 11 which is provided so as to protrude from the left side of the copying machine body 1. The original D is pressed by pressing a copy button (not shown).
The paper feed solenoid SD1 is activated, the movable guide plate 12 jumps up, and presses the document D against the separation belt 13. Next, by driving in the mode M, the separating belt 13 starts rotating in the direction of the arrow connected to the driving source by the 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 paper feed roller 15 rotating in the direction of the arrow, the document size sensor PS1
, The paper feed clutch K1 is turned off, and the driving force of the separation belt 13 is cut off. Then, the paper feed roller K starts free rotation, but only the preceding original Dn is conveyed by the paper 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. Now, when the size of the document Dn is automatically detected by notifying the document size detection sensor PS1 at the leading and trailing edges of the document Dn, the motor M converts from forward rotation to reverse rotation, and reverses the excessively moved document Dn to the The end abuts 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 turns on,
The paper discharge reversing roller 31 rotates to transport the document Dn, and stops at a position between the document table glass 2 and the paper discharge roller 35. Then, the next original Dn + 1 is maintained so as to keep the interval b from the original Dn to be stopped.
The paper feed clutch K1 is turned on and conveyed, and when the paper reaches the document size detection sensor PS1, the paper feed clutch K1 is turned off, and the length of the document is detected and the separating belt 13 becomes free, but the document Dn +
1 is transported to the optical scan position. Furthermore, the original Dn + 1
When the optical scan is completed (copy completed), the document output unit 30
The document Dn, which was previously conveyed and stopped, is conveyed, and when the trailing end reaches the document discharge detection sensor PS2 installation location, the discharge unit solenoid SD2 operates to suction.
The suction timer starts and the time is up,
This illustrates a state in which the discharge unit solenoid SD2 is turned on, the discharge roller 35 is rotated to hold the document Dn, and the discharge roller 35 discharges the paper. These originals Dn, Dn + 1 and the next original Dn + 2, Dn
The +3 movement is shown in FIG. 7 and FIG. In the present invention, even when the exposure (copying) of the final document is completed, it is necessary to drive the motor M until two documents are discharged from the contents described above.

Note that, when the interval b between the originals and the length L of the original are set, it is desirable that the dimensional relationship be 2L + b <A <2L + 2b. However, the transport path A is a distance from the stopper plate 3 to the paper discharge roller 35 as shown in the schematic diagram of FIG.
However, since the transport path A is actually constant, the document interval b is a variable as in the following example. Therefore, (A / 2) -L <b <A-2L is appropriate as a relational expression.

Now, for the dimensions of (2L + b), A = 450mm (length of platen glass), discharge path length = 240
If mm, b = 450 mm + 240 mm−210 mm (A4 size) × 2, and therefore b = 270 mm (interval). If the circumferential speed of the photosensitive drum is normally set to 0.525 sec, the document conveyance speed is 270 mm + 210 mm (A4 size) /0.525 sec ≒ 914 mm / sec.

However, in this case, if the rise and fall of the motor are not considered, the conventional speed is about 1.314 mm / S as standard, so it will not be 914 mm / S. That is, the transport speed can be reduced by as much as 30%. FIG. 9 shows this (2L + b) relationship.

Further, in the dimension of (2L + 2b), b = 135 mm, and the document conveyance speed is 135 mm + 210 mm (A4 size) /0.525≒65.
7mm / S That is, the transport speed can be reduced to 50%. The relationship of (2L + 2b) is shown in FIG. By providing the above relationship, it is possible to reduce the document conveyance speed, which is a great advantage in terms of functional performance as described later. When A is within the range of the above formula, it is necessary to prevent the unsightly appearance of the front end of the preceding document protruding while being pressed by the paper discharge roller 35 during optical scanning (exposure copying).

Also, the original size detection sensor PS1
Alternatively, a document D may be provided on the document tray 11 on the horizontal width regulating plate, and the amount of movement during setup of the document D may be detected by a sensor to recognize the document size of the document type. You may memorize by input.

〔The invention's effect〕

As described above, according to the automatic document feeder of the present invention, not only can the document feed speed be reduced, but also the separation performance can be improved and the document feed can be smoothly performed due to the low speed separation during document feed. 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. If the speed is not reduced, the copy productivity opm / cpm can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a document conveying path of an automatic document feeder according to the present invention, FIG. 2 is a perspective view of an external appearance 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, and FIGS. 9 and 10 are schematic diagrams for explaining the document interval size condition of the present apparatus. 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 rollers, D… Documents G1 to G10… Gears, K1… Paper feeding clutch K2, K3… One-way clutch M… Motor P1 to P7… Drive pulley PS1 …… Document size detection sensor PS2 … Document discharge detection sensor SD1… Feeding solenoids SD2, SD3… Discharge unit solenoids S… Forward arrow of double-sided document b… Interval R… Return arrow of double-sided document L… Document length

Continuation of front page (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/00 107 G03G 21/00 370-502 G03G 21/14

Claims (1)

(57) [Claims] An original is sequentially fed to an image exposing section, a plurality of sheet-form originals are stopped at the image exposing section, and scanning exposure is performed. In an automatic document feeder for unloading a document to a document discharge tray by a document discharge means provided downstream of the document, a transport mechanism for transporting a document from the document feed unit to the document discharge tray via the image exposure unit A driving motor is connected to the driving motor and a sheet feeding unit and a document discharging unit of the document feeding unit. The distance to the trailing edge of the document is
The document size is changed by recognizing the size of the document to be conveyed.In the case of a document of at least the minimum size in the feed direction, when the document is conveyed from the stop position of the image exposure unit to the discharge position to the document output table, (A / 2) -L <b <A-2L (where A is the distance from the rear end position of the original stopped at the image exposure unit to the discharge position, and L is the length of the original in the transport direction.) Well,
(b is the distance between the original and the preceding original), the original is controlled so as to satisfy the following condition. During the exposure of the N-th original fed from the original feeder, the exposure was completed before ( (N-1) An automatic document feeder, wherein the (N-2) th original is stopped in the transport path, and the (N-2) th original is discharged.