JPH08119468A - Automatic document feeding device - Google Patents

Abstract

PURPOSE: To provide an automatic document feeding device in which a time needed for raising a document loading table is reduced and also a document feed and process speed is reduced. CONSTITUTION: An automatic document feeding device is provided with a document loading table 1 on which documents are placed, a lifter which moves the document loading table 1 in vertical direction, a pickup roller 2 which feeds out the document loaded on the document loading table 1, and a separating part 7 which separates and feeds the document fed out by the pickup roller 2 one by one from the uppermost part. Then the waiting position of the document loading table 1 is set at any position within the vertical movable range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder for automatically feeding a document, and more particularly to an automatic document feeder provided in an image forming apparatus such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine is equipped with an automatic document feeder for automatically feeding a document.
Among the automatic document feeders, an apparatus in which the document placing table is movable is a circulating automatic document feeder having a switchback path and a closed loop path, which is described in Japanese Patent Laid-Open No. 3-147683. Further, when a sheet placed on the original placing table is detected, a lifter mechanism that raises to a position where the sheet and the pickup roller come into contact with each other and separates and conveys the sheet is widely known.

There are two possible methods for placing the document on the sheet mounting table, with the document surface facing up or down, but in consideration of the operability of the user, the document surface is oriented upward. Is preferred, and this method is often used. Further, as the paper feeding method, there are upper separation paper feeding and lower separation paper feeding, but when performing lower separation paper feeding with the document side facing up, and when performing double-sided copying of a single-sided original, it is necessary to detect the number of originals in advance. However, the work of counting the number of originals is performed by temporarily separating and feeding all the originals for this detection. In this method, it takes time to detect the number of originals, and as a result, the total copy speed is reduced. In particular, since the automatic document feeder having a large maximum number of sheets to be stacked is disadvantageous, the above problems have been solved by performing the upper separation feeding.

[0004]

However, in the above-mentioned prior art, as shown in FIG.
When the original 52 is placed on the sheet 51 and the copy start button is pressed, the original placing table 51 is raised until the uppermost sheet 52a is detected by the sensor 53, and the uppermost sheet 52a and the pickup roller 54 come into contact with each other. As a result, the uppermost sheet 52a is conveyed to the separating section 55 and separated and fed. However, the above document placing table
Since the document 51 stands by at the bottom of the movable range of the table before the document 52 is placed, if the maximum number of sheets to be loaded is increased, the document table will be fed when feeding a small number of documents. There is a drawback that it takes longer to raise 51 and lowers the total copy speed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic document feeder which shortens the time spent for raising the document table and can reduce the document feeding processing speed.

[0006]

A typical means for solving the above-mentioned problems of the prior art and applied to the embodiments described below is an original placing table on which an original is placed, and the original placing table in the vertical direction. Automatic document feeding having driving means for moving the document loaded on the document placing table, sending-out means for sending out the originals stacked on the original placing table, and separating means for separating and transporting the originals sent out by the sending-out means one by one from the top. The apparatus is characterized in that the standby position of the document placing table is set at an arbitrary position within a vertically movable range.

[0007]

According to the above means, the standby position of the document placing table is set to an arbitrary position within the vertical movable range, so that even when the maximum number of documents to be loaded is increased, a small number of documents can be fed. It is possible to shorten the time spent for raising the document placing table and lower the document placing table when feeding a large number of documents.

With this, it is possible to average the document feeding processing speeds which greatly differ depending on the number of originals. For example, by setting the standby position of the original placing table to an intermediate position of the vertical movable range, it varies depending on the number of originals. The total paper feed processing speed can be averaged most, and the total paper feed processing speed can be minimized in the long term by setting the standby position of the document placing table to the user's average number of documents.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic document feeder according to the present invention will be described below with reference to the drawings. In this embodiment, an automatic document feeder installed in a copying machine will be described. 1 is a sectional side view of the automatic document feeder, FIG. 2 is an explanatory view of the automatic document feeder when a small number of originals are stacked, and FIG. 3 is an explanatory view of setting the original document feeding position of the automatic document feeder, FIG. FIG. 6 is an explanatory view of the automatic document feeder when stacking a large number of documents.

First, the schematic structure of the automatic document feeder will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a vertically movable document table on which a document is placed, and stands by at an arbitrary position within the vertically movable range when no document is stacked. The document table 1 is moved in the vertical direction by a driving means such as a lifter (not shown). Reference numeral 2 denotes a pickup roller as a sending-out means for sending out the originals stacked on the original mounting table 1. The pickup roller 2 is located above the surface of the mounting table when no originals are stacked and is located at a position equal to or larger than the maximum stacking thickness. Is held. The pickup roller 2 is held by an arm 3 and is vertically moved by a solenoid 4 connected to the arm 3. Reference numeral 5 denotes a document thickness detection sensor installed to detect the thickness of the document stacked on the document mounting table 1, and detects the thickness of the document by detecting the position of the pickup roller 2.

Reference numeral 6 denotes a shutter as a matching means,
The leading edge of the original placed on the original placing table 1 is abutted and aligned, and the leading edge of the original is opened during the operation of feeding the original by the pickup roller 2. The shutter 6 is moved up and down by a solenoid (not shown), and has the effect of aligning the leading edge of the originals. Even if a large number of originals are stacked, the stack of originals can be pushed into the separation section, which can cause a paper feed failure. Is being prevented. Denoted at 7 is a separating section as a separating means, which is provided with a feed roller and a retard belt which rotate in mutually opposite directions, and separates and conveys the uppermost document fed by the pickup roller 2 one by one. Reference numeral 8 denotes a pair of conveying rollers that conveys the separated document to the reading position on the downstream side.

Next, the document feeding operation will be described. When documents are stacked on the document table 1 and the copy button is pressed,
The solenoid 4 is turned off, and the pickup roller 2 drops to the top of the document due to its own weight. At this time, a control unit (not shown) stores in advance a sensor position a at which the original feed position and the pickup roller 2 position are the same, and after the pickup roller 2 falls, the lifter is always adjusted to the sensor position a. Then, the document table 1 is moved up and down. When the pickup roller 2 reaches the sensor position a due to the elevation of the document placing table 1, the shutter 6 is opened and the pickup roller 2 is rotationally driven, so that the documents are conveyed to the separating portion 7 and separated and conveyed one by one. Further, in the document placing table 1, the drive of the lifter is controlled so that the document placing table 1 automatically moves to the lowermost part of the vertically movable range when the document is jammed.

Next, the document feeding operation when the number of documents loaded on the document table 1 is different will be described with reference to FIGS. FIG. 2 shows the automatic document feeder when a small number of originals are stacked. When the copy button is pressed, the solenoid 4 is turned off and the pickup roller 2
Falls to the top 9 of the document. At this time, the sensor position a of the document thickness detecting sensor 5 moves from a ₁ to a ₂ .
The document thickness detecting sensor 5 is composed of a slide resistor, and the resistance value a ₀ at the a ₀ position is electrically stored. When the resistance value is a ₂ lower than a ₀ , the document placing table is set. 1
And the resistance value reaches a ₀ , the drive of the lifter is stopped. Then, a solenoid (not shown) is turned off and the shutter 6 is opened. This state is shown in FIG. After that, the pickup roller 2 is rotationally driven, and the originals are conveyed to the separating portion 7 and separated and conveyed one by one from the uppermost portion 9 of the originals.

FIG. 4 shows an automatic document feeder for stacking a large number of originals. When the copy button is pressed, the solenoid 4 is turned off and the pickup roller 2 drops to the top 9 of the document. At this time, the sensor position a of the document thickness detection sensor 5 moves from a ₁ to a ₂ . As described above, the document thickness detecting sensor 5 is composed of the slide resistance, and the resistance value a ₂ is higher than a _0.
In the case of 1, the document table 1 is lowered and the drive of the lifter is stopped when the resistance value reaches a ₀ . Next, the solenoid (not shown) is turned off, the shutter 6 is opened, the pickup roller 2 is rotationally driven, and the originals are conveyed to the separating section 7 and separated and conveyed one by one from the uppermost original 9.

The document thickness detecting sensor 5 is not limited to the slide resistance, and other detecting sensors can be used.

According to the above construction, by setting the standby position of the document placing table 1 at an arbitrary position within the vertical movable range,
Since it is possible to shorten the lift-up time of the document placing table 1 when a small number of documents are stacked, even when the maximum document loading amount is increased, the document placing table 1 is lifted up when copying a few documents. It is possible to prevent a significant time loss.

[Other Embodiments] Next, another example of the automatic document feeder will be described with reference to FIGS. FIG. 5 is a sectional side view of the automatic document feeder, in which 10 is a vertically movable document table on which an original document is placed, which stands by at an intermediate position in the vertically movable range when no original document is loaded. ing. The original placing table 10 is moved in the vertical direction by a driving means such as a lifter (not shown). Reference numeral 11 denotes a pickup roller as a sending-out unit that sends out the documents stacked on the document mounting table 10.The pickup roller 11 is located above the platen surface when no documents are stacked, and is located at a position equal to or larger than the maximum stacking thickness. Is held. Above pickup roller
Reference numeral 11 is held by an arm 12, and a sensor plate 13 having a plurality of cutouts formed around the arm 12 is integrally attached to the arm 12. Reference numerals 14a and 14b denote photointerrupters as document thickness detecting means for detecting the thickness of the document. By detecting the notch of the sensor plate 13 which rotates according to the up and down movement of the pickup roller 11, the document is detected. To detect the thickness of.

Denoted at 15 is a separating section as a separating means, which is provided with a feed roller and a retard belt which rotate in mutually opposite directions, and separates and conveys the uppermost document fed by the pickup roller 11 one by one. Reference numeral 16 is a pair of conveyance rollers for conveying the separated document to the reading position on the downstream side.

Next, the document feeding operation will be described. When documents are stacked on the document table 1 and the copy button is pressed,
Turn off the solenoid (not shown) to pick up the roller.
11 drops to the top of the document due to its own weight. At this time, the state of the pickup roller 11 can be detected by detecting the notch of the sensor plate 13 by the photo interrupters 14a and 14b. After completion of the detection, the document placing table 1 is moved up and down by the lifter so that the uppermost part of the document is located at the document feeding position shown in FIG. The photo interrupter 14a is set so as to be positioned in the notch of the sensor plate 13 when the position of the original feeding position and the position of the pickup roller 11 are the same, and the top of the original is set by the photo interrupter 14b. It is determined whether the document table 1 is raised or lowered by detecting whether it is located above or below. When the top of the original reaches the original feeding position, the pickup roller 11 is driven to rotate, and the original is conveyed to the separating section 15 and separated and conveyed one by one. Further, in the document placing table 10, the drive of the lifter is controlled so that the document placing table 10 automatically moves to the lowermost part of the vertically movable range when the document is jammed.

Next, referring to FIGS. 6 to 8, the document feeding operation when the number of documents stacked on the document table 10 is different, that is, when the top of the document is located below or above the document feeding position explain. FIG. 6 shows an automatic document feeder when a small number of originals are stacked. When the copy button is pressed, a solenoid (not shown) is turned off, and the pickup roller 11 drops to the uppermost portion 17 of the original. At this time, the sensor plate 13 is in the state of the enlarged view of FIG. 6, the photo interrupter 14a is shielded from light, and the photo interrupter 14b is shielded.
Is open. The photo interrupter 14a
Is energized to a lifter lifter motor (not shown) when it is shielded from light, and is stopped when it is opened. The photo interrupter 14b is configured to rotate the motor in a direction to lower the document placing table 10 when it is shielded from light, and to rotate the motor in a direction to raise the document placing table 10 when it is opened. .

Therefore, in the state shown in FIG.
Increase 10 and continue to increase to the state shown in FIG. When the photo interrupter 14a is opened by the notch of the sensor plate 13 as shown in the enlarged view of FIG.
Is stopped and the pickup roller 11 is driven to rotate, so that the original is conveyed to the separating portion 15 and is fed from the uppermost portion 17 of the original.
Separately conveyed one by one.

FIG. 8 shows an automatic document feeder for feeding a large number of originals. When the copy button is pressed, a solenoid (not shown) is turned off and the pickup roller 11 drops to the top 17 of the original. At this time, the sensor plate 13 is in the state of the enlarged view of FIG. 9, and the photo interrupter 14a is shielded from light and the photo interrupter 14b is shielded from light. As described above, the original placing table 10 is lowered in the state of FIG. 8 and continues to be lowered until the state of FIG. Then, as shown in the enlarged view of FIG. 7, when the photo interrupter 14a is opened by the notch of the sensor plate 13, the original placing table 10 is stopped, and the pickup roller 11 is driven to rotate so that the original is conveyed to the separating portion 15 and the original is conveyed. Top
Separately conveyed from 17 sheets.

The document thickness detecting means is not limited to the sensor plate 13 and the photo interrupters 14a and 14b.
It can be implemented by other detection sensors.

According to the above construction, by setting the standby position of the document placing table 10 at the middle position of the vertical movable range, the total copy speed which varies depending on the number of documents can be averaged, and further, the document loading can be performed. By setting the standby position of the table 10 to the average number of original documents by the user, the total copy speed can be minimized for a long period of time.

Although the present embodiment has been described by using the copying machine equipped with the automatic document feeder, the present invention is not limited to this, and another device such as a facsimile device may be used.

[0026]

As described above, according to the present invention, the standby position of the document placing table is set to an arbitrary position within the vertical movable range, so that the lift-up time of the document placing table when a small number of documents are stacked is set. Since the length can be shortened, it is possible to prevent a significant time loss in lift-up of the document placing table when feeding a small number of documents even when the maximum stacking amount of documents is increased.

In particular, by setting the standby position of the document placing table at an intermediate position of the vertical movable range, the total sheet feeding processing speed which varies depending on the number of documents can be averaged most, and further, the document placing table of the document placing table is By setting the standby position to the user's average number of originals, it becomes possible to minimize the total paper feed processing speed for a long period of time.

[Brief description of drawings]

FIG. 1 is a side sectional view of an automatic document feeder.

FIG. 2 is an explanatory diagram when a small number of originals are stacked in the automatic original feeder.

FIG. 3 is an explanatory diagram when setting a document feeding position of the automatic document feeder.

FIG. 4 is an explanatory diagram when a large number of originals are stacked in the automatic original feeder.

FIG. 5 is a sectional side view of an automatic document feeder according to another example.

FIG. 6 is an explanatory diagram when a small number of originals are stacked in the automatic original feeder according to another example.

FIG. 7 is an explanatory diagram when setting a document feeding position of an automatic document feeder according to another example.

FIG. 8 is an explanatory diagram when a large number of originals are stacked in the automatic original feeder according to another example.

FIG. 9 is an explanatory diagram showing a problem of the conventional technique.

[Explanation of symbols]

 1, 10 ... Original placing table 2, 11 ... Pickup roller 3, 12 ... Arm 4 ... Solenoid 5 ... Original thickness detection sensor 6 ... Shutter 7,15 ... Separation section 8, 16 ... Conveying roller pair 9, 17 ... Original document Upper part 13 ... Solenoids 14a, 14b ... Photo interrupter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 1/00 108 F

Claims (4)

[Claims] 1. A document placing table on which a document is placed, a driving means for moving the document placing table in a vertical direction, a sending-out means for sending out a document stacked on the document placing table, and a sending-out means for sending out by the sending-out means. In an automatic document feeder having a separating means for separating and transporting the formed originals one by one from the top, the automatic original characterized in that the standby position of the original placing table is set to an arbitrary position within the vertical movable range. Feeder. 2. The automatic document feeder according to claim 1, wherein the standby position of the document placing table is set in the middle of a vertically movable range. 3. The automatic document feeder according to claim 1, wherein the document placing table automatically moves to a lowermost part of a vertically movable range when the document is jammed. 4. An original document thickness detecting means for detecting a thickness of an original document placed on the original document placing table, and a reference of the original document placing table by the driving means based on a detection signal of the original document thickness detecting means. 2. The automatic document feeder according to claim 1, wherein the vertical movement of the document is controlled.