JPH05127462A - Document feeder - Google Patents

Abstract

PURPOSE:To shorten document recirculating feeding time and to efficiently improve a copying speed by switching a document recirculating speed to a high speed in accordance with the length of a document. CONSTITUTION:In a single copying mode, the size of the document P inserted from an insertion port 60 is detected by a document width detecting means 62 and a document length detecting means 63, and the document P is fed to an exposing position 7. In this mode, a front edge detecting means 80 is ineffectual. The image of the document P is optically scanned by passing the exposing position 7, and a copied image in accordance with an image is formed and transferred on a transfer material in accordance with the size of the document and copying magnification. Next, when the trailing edge of the document P passes the exposing position 7, the passage thereof is detected by a trailing edge detecting means 90, which outputs a detection signal to a control part. The control part switches the driving device of driving rollers 10-40 to the high speed in accordance with the detection, and the document after exosure is fed at high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder such as a copying machine or a printer, and more particularly to a document feeder capable of repeatedly circulating a document through an exposure position a specified number of times.

[0002]

2. Description of the Related Art In this type of document feeder, for example, as disclosed in U.S. Pat. No. 3,770,348, the circulation path of the document is composed of a plurality of small-sized sheet conveying bodies connected in series. A device is known in which several long and short circulation paths can be formed by appropriately combining the bodies, and one of them is selected so as to have the shortest circulation path according to the size of the document to be circulated. Since such a device can obtain the shortest circulation path according to the document size, it has an advantage that the document can be circulated in the shortest time according to each size.

[0003]

However, in such a conventional apparatus, a plurality of small path carriers and a plurality of operable fingers for selectively combining them are provided.
Alternatively, it requires means for operating such fingers, complicating the construction of the device.

Therefore, it is an object of the present invention to provide a document feeder which has a simple structure and can be made compact.

[0005]

In order to solve the above-mentioned problems, the document conveying apparatus according to the present invention makes it possible to change the conveying speed of the document in the path, and after the rear end of the document has passed the exposure position, the document is moved. Process at high speed.

That is, the document conveying apparatus according to the present invention has a path for conveying an inserted document through the exposure position, a variable document conveying means arranged along the path, and a rear end of the document. And a means for detecting that the document has passed the exposure position, and when the detecting means detects the passage of the trailing edge of the document, the document conveying speed of the conveying means is switched to a high speed.

Furthermore, a circulation path for repeatedly circulating the inserted original document through the exposure position a specified number of times, a variable-speed original conveying means arranged along the circulation path, and the inserted original document. In the circulation mode, when the detection unit detects that the length of the document is shorter than a predetermined length, the trailing edge of the document passes the exposure position. After that, the document transport speed of the transport means is switched to a high speed until the leading edge of the document reaches before the exposure position.

[0008]

According to such means, the original is discharged at a high speed after the exposure of the original during the single exposure mode or the final exposure in the circulation mode. In the circulation mode, when the document to be circulated is shorter than the predetermined length, the period in which the document is not involved in exposure, that is, the trailing edge of the document passes through the exposure position and its leading edge is exposed for the next exposure. Since the document is conveyed at a high speed until it reaches the front, the time required for circulating the document can be effectively shortened.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a document circulating device such as a copying machine or a printer. The document circulation path 1 is roughly divided into an upper conveyance path 2, a lower conveyance path 3, and U-turn paths 4 and 5, and has a perimeter longer than at least the maximum copyable document size. The lower conveyance path 3 is continuous with the document insertion path 6 and forms a path for guiding the document P inserted through the insertion path 6 to the exposure position 7.

Driving rollers 10, 20, 30, 40 for conveying the originals are arranged in the upper conveying path 2 and the lower conveying path 3 so as to allow a part of the peripheral surface to be seen, and each of the driving rollers is provided. Upper driven rollers 11, 21, 31,
41 and the lower driven rollers 12, 22, 32, 42 are arranged so as to come into contact with each other with an appropriate pressure, and the driving roller 1
Follow 0-40. The drive rollers 10 to 40 are connected to a variable-speed drive source, and are controlled so that an original can be conveyed at at least two speeds, a constant speed for exposure and a high speed higher than the constant speed. ing. Switching between these speeds can be performed by using a synchronous motor or by using a known means such as a variable speed gear train.

A drive roller 10 located on the side of the document insertion path 6
Adjacent to the above, a finger 50 is provided movably in the vertical direction so as to project and retract with respect to the upper transport path 2. The finger 50 has a circular arc-shaped guide surface in the vicinity of the drive roller 10, and forms a U-turn path 5 with the peripheral surface of the drive roller 10. As shown in FIG. 1, the finger 50 is normally located at a position recessed from the upper transport path 2 and moves upward by a suitable drive means such as an electromagnetic solenoid during the circulation mode, which will be described later, and moves upward. To project across.

The original P inserted from the original insertion path 6 is conveyed by the driving rollers 10 to 30 and the lower driven rollers 11 to 32 through the lower conveyance path 3 so as to cross the original exposure position 7. The document exposure position 7 is generally made of a transparent glass plate, and the document P is conveyed (scanned) along the upper surface thereof with the image surface facing downward. The image of the original P is exposed by the exposure lamp 71, and its optical image is formed on the photosensitive drum 73 via the lens 72, and the charger 74, the developing device 75, and the transfer device 76 arranged around the photosensitive drum 73. A well-known electrophotographic image forming means such as the above forms a copy image according to the original image.

The exposed original P is U-turned by the driving roller 40, the driven rollers 42, 41 and the guide 43, and is guided to the upper conveying path 2. Prior to the insertion of the original, the machine operator sets the number of copies, and the original conveying device is operated in the single copy mode when the number of copies is one, and in the circulation mode when the number of copies is plural.
In the single-copy mode, the finger 50 is in the upper transport path 2
Therefore, the document P advances straight along the upper conveyance path 2 and is ejected to the outside of the machine through the space between the ejection roller 51 and the guide 52. In the circulation mode, the fingers 50 are urged to move across the inside of the upper transport path 2, thereby forming a document circulation path. The document is exposed by being circulated through this circulation path a set number of times, and when the final exposure is completed, the finger 5
0 moves downward to open the upper conveyance path 2 and directs the document toward the discharge roller 51.

The insertion path 6 is provided near the entrance 60 of the document insertion path 6.
A gate 61 capable of projecting is arranged so as to cross the sheet, and a document width detecting means 62 is provided upstream of the gate 61. When the preceding document still exists in the document circulation path 1, the gate 61 closes the insertion path 67 and waits for the next document until the document in the circulation path 1 is discharged.

The document width detecting means 62 includes a plurality of document presence / absence detecting sensors a to d and a ', such as photosensors, which are arranged in a line in a direction facing the insertion path 6 and transverse to the document traveling direction. ˜d ′. Sensor a
d and a'-d 'are provided at left and right symmetrical positions, and the original P is inserted so that the center lines thereof are substantially aligned with each other. In the figure, sensors a and a ′ are arranged at positions slightly inside the lateral width of an A1 size document, and similarly sensors b and b ′ are A2 size documents and a sensor c and
c ′ is an A3 size document, and sensors d and d ′ are located slightly inside the lateral width of an A4 size document. When the presence / absence of the document is detected by the sensors a and a ′ based on the detection result of the presence / absence of the document by these sensors, the document is determined to be A1 size, and the sensor a / a ′ indicates that the document is absent and the sensor b. , B ′ detect the presence of a document, the document is determined to be either A2 size vertical feed or A3 size horizontal feed. Similarly, the sensors c and c ′ perform A3 size vertical feed or A4 size horizontal feed, and the sensors d and d ′ use A feed.
Determine the 4 size vertical feed. Here, for the sensors a, a ′ and d, d ′, the document size is determined to be one from the detection results, but for the sensors b, b ′, c, c ′,
Two types of sizes are assumed depending on the document feed direction (longitudinal feed, horizontal feed) and are not determined. Therefore, the document length detecting means 63 is arranged facing the insertion path 6.

In the illustrated example, the document length detecting means 63 is arranged at a position downstream of the document insertion path 6 of the document width detecting means 62, but it is not limited to this position. The document length detecting means 63 is composed of, for example, a photo sensor, detects the passage of the front and rear ends of the moving document P, and sends the detection result to the control unit. The control unit counts the time from the passage of the leading edge of the document P to the trailing edge of the document P and compares the time with the data of the vertical and horizontal lengths of each size stored in advance to determine whether the transported document is vertically fed. Determine if it is a feed. The detection result from the document width detection means 62 is also input to the control section, and the size and the feeding direction of the inserted document are determined by this. In accordance with this confirmation, a transfer material that matches the original size and the copy magnification is selected and supplied to the transfer device 76 of the image forming unit, and the image is transferred.

In order to detect the position of the document moving in the document circulation path, a document front edge detecting means 80 and a rear edge detecting means 90 such as a photo sensor are arranged before and after the exposure position 7.
The front end of the original 80 detects that the front end of the original has arrived before the exposure position 7, and the rear end detection unit 90 detects that the rear end of the original is at the exposure position 7.
Passages are detected and the detection results are sent to the control unit.

In such a structure, the document P is conveyed as follows. In the single copy mode, the size of the document P inserted from the insertion port 60 is detected by the document width detection means 62 and the document length detection means 63,
It is conveyed to the exposure position 7. In this mode, the leading edge detecting means 80 is invalid. The image of the original P is at the exposure position 7
Is optically scanned by the passage of the sheet to form a copy image corresponding to the image, and the copy image is transferred onto a transfer material according to the document size and the copy magnification. Next, when the trailing edge of the document P passes through the exposure position 7, the trailing edge detection means 90 detects this passage and sends the detection signal to the control section. The control unit follows this detection,
The driving devices of the driving rollers 10 to 40 are switched at high speed, whereby the exposed original is conveyed at high speed. In the single copy mode, since the fingers 50 open the upper transport path 2 as described above, the original document is directly ejected by the ejection roller 51 to the outside of the apparatus.

On the other hand, in the circulation mode, the fingers 5
0 projects to the upper conveyance path 2 to form a document circulation path. As a result, the exposed document is conveyed again to the lower conveyance path 3 through the U-turn path 5 and is again exposed for copying. If the original is smaller than the circumference of the circulation path,
The time from when the trailing edge of the document passes the exposure position until the leading edge of the document reaches the exposure position again is not effective. Therefore, in the circulation mode, when the document length detection unit 63 detects that the document to be circulated is shorter than the predetermined length, when the document trailing edge is detected by the trailing edge detection unit 90, the document driving roller 10 is detected. The document conveying speed of ˜40 is switched to a higher speed than the exposure speed, and the original is circulated at a high speed. This high-speed operation is performed until the leading edge of the circulated document is detected by the leading edge detecting unit 80, and when the leading edge detecting unit 80 detects the leading edge, the document conveying speed returns to the exposure speed again. After the final exposure for the set number of copies,
The finger 50 moves downward to open the upper passage 2.
The document after the final exposure is conveyed at a high speed by the trailing edge of the document passing through the trailing edge detecting means 90, goes straight through the upper conveyance path 2 and is ejected outside the apparatus by the ejection roller 51.

As described above, according to the present invention, since the document circulation speed is switched to a high speed according to the length of the document, the circulation transportation time of the document, which was not effective in the past, can be shortened. Therefore, the copying speed can be efficiently improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a document feeder according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Document transport device 2 Upper transport path 3 Lower transport path 10-40 Drive roller 50 Finger 63 Document length detection means 80 Front edge detection means 90 Rear edge detection means

Claims (2)

[Claims] 1. A path for transporting an inserted document through an exposure position, a variable-speed document transport unit arranged along the route, and a trailing edge of the document having passed through the exposure position. And a means for detecting that the original conveying apparatus switches the original conveying speed of the conveying means to a high speed when the detecting means detects the passage of the trailing edge of the original. 2. A circulation path for repeatedly circulating an inserted document through an exposure position a specified number of times, a variable-speed document conveying means arranged along the circulation path, and a length of the inserted document. In the circulation mode, when the detection unit detects that the length of the document is shorter than a predetermined length, after the rear end of the document passes the exposure position. A document transporting device, wherein the document transporting speed of the transporting means is switched to a high speed until the leading edge of the document reaches before the exposure position.