JP3188318B2 - Automatic document feeder - Google Patents

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 used in a copying machine.

[0002]

2. Description of the Related Art As a conventional automatic document feeder (ADF) used in a copying machine, for example, a document set on a document set portion is called, separated one sheet at a time, fed, and conveyed. The document is guided to an image reading section, and the original after image reading is turned over before being discharged to a stacker.

[0003]

However, in the above-described conventional automatic document feeder, the factor of the length of the document cannot be read unless the entire length of the document is conveyed.
In other words, in order to know the size of the next document to be fed, it is necessary to prepare a transport path of a length equivalent to the total length of the next document to be sent from the setting section to just before the image processing section. was there. If this long conveyance path cannot be prepared, the determination of the document size is made only immediately before the image is set at the image processing position, so that the size of the corresponding transfer paper to be fed next is up to this time. Because it is not decided,
Only after the original is set, the corresponding transfer paper is sent out.As a result, the copy processing speed in the mixed mode is considerably slower than that in the same size original mode in which the transfer paper can be fed in advance. There was a disadvantage.

Further, in a conventional copying system without the mixed-size mode, when small and large originals having the same original width and different sizes are mixed in a large original bundle, for example, Was copied on a large-size transfer paper.

Accordingly, the present invention makes it possible to realize mixed-size mode processing in which copying can be performed at a processing speed equal to or close to that of the same size mode, and further copies a small-sized document to a large-sized transfer paper. Such miscopying is intended to be reduced.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a document setting section for setting a document, a sheet feeding section for feeding the document to one sheet, and a conveyance of the document to an image reading section. In an automatic document feeder having a transport unit for reading an image and a discharge unit for restacking the read documents, a document width detecting unit detects a document width.
1 detecting means and 2nd detecting means for detecting the leading and trailing edges of a document
And an encoder for measuring the time between the leading edge and the trailing edge of the document. The document size is limited to two sizes having the same width and different lengths based on the document width detected by the first detecting means .
2 The time from the leading edge of the document detected by the detection means
Measurement from the rear edge of the small-size document
In the period up to the trailing edge of the document, the second detecting means
A control function for outputting a signal to feed a large-sized transfer sheet before detecting the trailing edge of the document is provided.

It is preferable that the control function is executed only when the mixed-size mode is selected.

In addition, a size signal is output each time in a mode other than the mixed size mode, and when the previously detected original size is different from the immediately detected original size, copying is temporarily inhibited and the copy is temporarily inhibited. It may be configured to have a function of performing a status display.

[0009]

When it is determined that the document is not of a small size even while the document is being conveyed , a signal of a large size is output, so that the transfer paper can be selected and sent out at an early stage.

Furthermore, even if the mixed-size mode is not set, if the size of the front and rear documents is different, copying is temporarily prohibited, thereby preventing erroneous copying.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show one embodiment of the present invention.
The document 2 set on the document setting unit 1 is called by a call roller 3, separated by a sheet feeding unit 6 including a separation belt 4 and a sheet feeding roller 5, and fed by a pair of pull-out rollers 7. Contact glass 9 by conveyor belt 8
An image is read by the image reading unit 10, and the document 2 after the image reading is transferred to the reversing switching claw 11 via the unloading unit 14.
In the automatic document feeder configured to be inverted and then discharged to the stacker 13 by the discharge roller 12 serving as a discharge unit, the width of the document 2 (the length in the direction perpendicular to the feeding direction) is detected. A first detecting means and a detecting means (sensor) 16 as a second detecting means for detecting the leading and trailing edges of the document 2 are provided at a position immediately before the transport section 8 and the document 2
An encoder 15 for measuring the time between the front and rear ends of the pull-out roller 7 is provided coaxially with one of the pull-out rollers 7, and the detection means 16 detects the time.
Limit the document size 2 size is different length width the same on the basis of the knowledge the document width, the original destination detecting means 16 detects
The time from the end is measured by encoder 15 and small
Between the trailing edge of the original and the trailing edge of the large original
Before the means 16 detects the trailing edge of the large document,
And a control function for outputting a signal for feeding the transfer paper . Reference numeral 17 denotes a document pressing unit.

It is preferable that the control function is executed only when the mixed size mode is selected.

Further, when a size signal is output each time in a mode other than the mixed size mode, and a state is detected in which the previously detected original size is different from the immediately detected original size,
A function of temporarily prohibiting copying and displaying a status is provided.

Next, the operation will be described. Here, in order to make the operation easy to understand, an example of a mixed original of A3 portrait and A4 landscape is shown.

A bundle of originals to be fed (A3.
(It is assumed that 10 sheets are stacked) is set in the document setting unit 1 and separated and sent to the sheet by the sheet feeding unit 6. When the leading edge of the document reaches the detection unit 16, the ADF can determine the size of the document as A4 landscape or A3. Further, the original 2 is conveyed, and immediately after the half of the paper has passed by the measurement of the encoder 15, the detecting means 1
At step 6, the ADF sends a size signal A3 to the main body of the copying machine, and the main body feeds A3 transfer paper. A3
The remaining nine sheets are also fed in the same manner. Next, when the A4 landscape document is fed, the document size is similarly determined to be A4 landscape or A3, and the presence or absence of paper is checked at the same time as A3, and it is determined that there is no paper. A size signal is sent to the main unit.

Also, even when the mixed size mode is not provided in the main body, if a sheet of a different document size is erroneously loaded on the ADF (for example, when A4 width is mixed in A3 length bundle), By transmitting the signal to the main body when the ADF detects A4, the main body side can temporarily suspend copying or display that the document size is different.

The present invention is not limited to only the above-described embodiment. For example, detecting means for detecting the width and the leading and trailing edges of a document may be separately provided, and other departures from the gist of the present invention may be made. Of course, various changes can be made within a range not to be performed.

[0018]

As described above, according to the automatic document feeder of the present invention, the size of the document can be detected earlier, so that the transfer paper can be selected and fed out earlier. It is possible to speed up the copying operation of the original, and to prevent a problem that a small-sized original is copied onto a large-sized transfer paper even if the mixed size mode is not set (or the reverse case). It has excellent effects such as

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of an automatic document feeder according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 document setting section 2 document 6 paper feed section 8 transport belt 10 image reading section 12 discharge roller (conveyance section) 15 encoder 16 detecting means (first detecting means, second detecting means)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-77143 (JP, A) JP-A-63-235229 (JP, A) JP-A-2-23128 (JP, A) JP-A 58-78 187921 (JP, A) JP-A-63-285533 (JP, A) JP-A-5-186089 (JP, A) JP-A-4-179657 (JP, A) JP-A-2-204253 (JP, A) Actual Opening 63-157057 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 107 G03G 21/00 370-500 G03G 21/14 G03B 27/58-27 / 64 G01B 11/24 B65H 1/00-3/64 B65H 7/00-7/20

Claims (3)

(57) [Claims] An original setting section for setting an original; a paper supply section for feeding the original to one sheet; a conveying section for conveying the original to an image reading section to read an image; In the automatic document feeder having a discharge unit for restacking a later document , a first document width detecting unit detects a document width.
Detecting means, second detecting means for detecting the leading and trailing edges of the document,
An encoder for measuring the time between the leading and trailing edges of the document,
Based on the document width detected by the first detecting means, the document size is limited to two sizes having the same width and different lengths, and the second detection is performed.
The encoder detects the time from the leading edge of the document detected by the informing means.
Measured from the rear edge of a small-sized document
In the period up to the trailing edge, the second detecting unit detects a large-size document.
An automatic document feeder having a control function of outputting a signal for feeding a large-size transfer sheet before detecting a trailing edge . 2. The automatic document feeder according to claim 1, wherein the control function is executed only when the mixed size mode is selected. 3. A size signal is output each time in a mode other than the mixed size mode, and when a size of a previously detected document differs from a size of a document detected immediately thereafter,
2. The automatic document feeder according to claim 1, further comprising a function of temporarily prohibiting copying and displaying a status thereof.