JPS5934897Y2 - Original detection control device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a document detection control device for a copying machine, particularly a diazo copying machine.

A diazo copying machine overlaps an original with photosensitive paper and prints an image of the original onto the photosensitive paper.

Therefore, the operator is required to superimpose the original and photosensitive paper and feed them into the machine, which is extremely troublesome when making a large number of copies.

An automatic document feeder is a solution to this problem.

This device automatically separates originals stacked on the document tray and feeds them into the copying machine, one by one, and separates them from the photosensitive paper stored separately inside the machine. It has become so.

One of the automatic document feeders is a paper feed roller that feeds out the stacked documents on the document loading table, a normal roller that rotates in the document feeding direction, and a forward rotation roller that rotates in the opposite direction to the document feeding direction. Some types include a pair of double-feed prevention rollers consisting of a reversing roller that rotates, and a pair of document transport rollers that rotate in the document feeding direction.

According to this device, even if the original is relatively thin and stiff, it can be reliably separated into individual sheets and sent to the copying machine.

Incidentally, in an automatic document feeder, it is necessary to detect a fed document at a proper location for registration with photosensitive paper and paper jam detection.

Conventionally, there has been a method for detecting a document that includes a microswitch and a document detection actuator that works in conjunction with the microswitch.

The originals used in diazo copying machines are relatively thin and fragile, so the method of mechanically detecting the originals as described above tends to damage the originals and cause paper jams. Another disadvantage is that the response of the microswitch varies widely.

The present invention has been developed in view of the above, and provides a document detection control device in an automatic document feeder that detects this and controls smooth document conveyance without interfering with the document conveyance in any way. The purpose is to

The purpose of the present invention is to provide a feed roller that feeds out the originals stacked on the original document mounting table, a normal roller that rotates in the feeding direction of the originals, and a reverse roller that rotates in the opposite direction to the feeding direction of the originals. In an automatic document feeder comprising a pair of double-feed prevention rollers and a pair of document transport rollers that rotate in the document feeding direction, a light-emitting element disposed immediately after the double-feed prevention roller pair in the document feeding direction. and a light-receiving element, and a second document detection means comprising a light-emitting element and a light-receiving element, which are arranged immediately after the pair of document transport rollers in the document feeding direction, and the second document detection means includes a light-emitting element and a light-receiving element, While the first document detection means detects the document, transmission of driving force to the paper feed roller is cut off, and while the second document detection means detects the document, the transmission of drive force to the normal rotation roller is cut off. It is distantly related to the document detection control device characterized by the following.

According to the present invention, since a photoelectric detection means that does not obstruct the passage of the original is used as the original detection means, the original can be conveyed smoothly.

Furthermore, in the event that a document fed into a copying machine jams in the automatic document feeder, the present invention can prevent jamming or damage to the document fed subsequently. Explain.

In FIG. 1, reference numeral 1 denotes an original plate on which stacked original sheets are placed to be sent to a diazo copying machine (not shown), and 2 separates the original sheets one by one and moves them in the direction of the arrow. Reference numeral 3 indicates a pair of double-feed prevention rollers, and reference numeral 4 indicates a pair of document transport rollers.

The double-feed prevention roller pair 3 consists of a normal roller 3a that rotates in the document feeding direction and a reverse rotation roller 3b that rotates in the opposite direction to the document feeding direction, and the friction coefficient of the roller 3a is The coefficient of friction of the roller 3b is set to be larger than that of the originals.

Further, a plurality of normal rotation rollers 3a and a plurality of reverse rotation rollers 3b are arranged alternately in the axial direction.

The pair of transport rollers 4 are composed of rollers 4a and 4b that are in pressure contact with each other and rotate in the document feeding direction, and rotate while the automatic document feeder is turned on. (See Figure 2).

Further, a light emitting element 5a is provided behind the pair of double feeding prevention rollers 3.
A switch S1 is disposed as a first document detection means, which includes a light receiving element 5b and a light receiving element 5b.

This switch S1 is a normally closed switch, and opens a part of the drive control circuit for the paper feed roller 2. When a document enters between the elements and the switch is opened, the paper feed roller 2 is closed. The driving force to 2 is cut off.

Behind the pair of document transport rollers 4, a switch S2 is arranged as a second document detection means, which includes a light emitting element 6a and a light receiving element 6b.

This switch S2 is a normally closed switch, and is a part of the drive control circuit for the normal rotation roller 3a of the pair of rollers 3, and the switch S2 is closed when a document enters between the elements. When opened, the driving force to the normal rotation roller 3a is cut off.

The distance between the pair of double-feed prevention rollers 3 and the document and the pair of transport rollers, and the distance between switch S1 and switch S2 are determined in the feeding direction of the minimum allowable size of the document used in the device. It is set smaller than the length.

The operation of the device of the present invention that has been stolen as described above will be explained based on FIG.

When the main switch, which also serves as a paper feed button, is pressed to turn on the power, the paper feed roller 2 rotates and feeds out the first document.

This first document is fed into a pair of rotating double-feed prevention rollers 3, is fed by the feeding force of the normal rotation roller 3a, and when its tip ■ is detected by switch Sl,
The switch is opened and the driving force to the paper feed roller 2 is cut off.

During this stop time of the paper feed roller 2, the original is switched to switch S1.
When the rear end ■ is released from the switch during the period in which the paper feed roller 2 is released, the paper feed roller 2 rotates again and feeds out the next document.

When the first document is held in the pair of document transport rollers 4 that are rotating at the same time as the power is turned on, and the leading edge of the document is detected by the switch S2, the switch S2 switches the forward rotation roller 3
Cut off the driving force to a.

Then, when the trailing edge (■) of the original is removed from the switch S2, the normal rotation roller 3a rotates again.

In summary, when the switch S1 detects that the document fed out by the paper feed roller 2 is caught between the pair of double-feed prevention rollers 3, the paper feeding operation of the roller 2 is stopped, and the document is The conveyance force to the normal rotation roller 3a depends on the forward rotation roller 3a, and when the switch S2 detects that the document advances further and is gripped by a pair of normally rotating document conveyance rollers 4, the drive to the forward rotation roller 3a is performed. The force is turned off and the document is fed by the pair of rollers 4.

When the trailing edge of the document passes switch S1, the paper feed roller 2 is rotated to send out the next document. At this time, if the trailing edge of the preceding document passes switch S2,
Since the normal rotation roller 3a, whose driving force has been cut off until now, rotates, it feeds the next document by holding it in its mouth.

Therefore, the document sent out by the paper feed roller 2 is sent to the switch S! and switch S2.

For example, if the document being fed is
If for some reason there is a jam in the document transport path between the paper feed rollers 4 and 4, the switch S1 will be released and the drive force transmitted to the paper feed rollers 2 will remain cut off. This eliminates the need to send the next document and minimizes the number of documents that are damaged due to jamming.

Incidentally, since the document used in the diazo copying machine is thin and transmits light, it is preferable to change the amount of light emitted from the light emitting elements 5a and 6a for documents with high transparency.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention, and FIG. 2 is a time chart of the same. 2...Paper feed roller 3a...Forward rotation roller 3b...Reverse rotation roller 4...
A pair of document transport rollers.

Claims (1)

[Scope of utility model registration request] A pair of double-feed prevention rollers consisting of a paper feed roller that sends out the documents stacked on the document loading table, a forward rotation roller that rotates in the document feeding direction, and a reverse rotation roller that rotates in the opposite direction to the document feeding direction. , in an automatic document feeder consisting of a pair of document transport rollers that rotate in the document feeding direction,
a first document detection means comprising a light-emitting element and a light-receiving element disposed immediately after the pair of double-feed prevention rollers in the document feeding direction; and immediately after the pair of document transport rollers in the document feeding direction; The second document detecting means includes a light-emitting element and a light-receiving element arranged at the top of the paper feed roller. A document detection control device characterized in that the drive force transmission to the normal rotation roller is cut off while the second document detection means is detecting the document.