JPS6331772B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to paper feeding interval switching means in an automatic document feeder. When making multiple copies of the same original using a diazo copying machine, the original is automatically circulated through the copying machine a preset number of times, and photosensitive paper is automatically fed and overlaid each time for each circulation to create the required number of copies. It is known to attach an automatic photosensitive paper feeder and an automatic document repeat mechanism to a copying machine so that it can make as many copies as possible. This has considerably improved the efficiency of copying work, but when there are a large number of originals, manually inserting them requires a considerable amount of labor and is cumbersome. Therefore, the work efficiency can be further improved by adding an automatic document feeder capable of automatically feeding documents to the above-described copying machine. An example of an automatic document feeder that has been proposed in the past and an outline of its operation will be explained with reference to FIG. A bundle of O sheets is placed on top of which a paper feed fan 22 and a clutch are placed.
A paper feed roller 23 is provided which is driven via MCa. A pair of double-feed prevention rollers consisting of a normal rotation roller 24a and a stop roller 24b is provided in front of the roller.
A second document detection switch SWb is provided. The above-described connection and disconnection of the clutch MCa is performed by paper detection signals from the two document detection switches SWa and SWb. The front edge of the document is pinched by the pinch roller 25.
When the document is detected by the second document detection switch SWb, the clutch MCa is disengaged, the feed roller 23 and the normal rotation roller 24a are stopped, and the document is transferred only by the conveyance force of the pinch roller 25. Then, it is conveyed toward the copying machine main body 1. and,
When the trailing edge of the document is detected by the first document detection switch SWa, the detection signal causes the clutch to
MCa is inserted, paper feed roller 23 and normal rotation roller 2
4a resumes rotation and sends out the next original. Therefore, the distance between the rear edge of the previous document and the front edge of the next document corresponds to the distance l between the first document detection switch SWa and the front edge of the document placed on the paper feed tray 21. You can create an interval. In this way, the original documents are automatically and sequentially fed into the copying machine main body 1 at constant intervals. In the unlikely event that the paper feed fan 22 sucks two documents at the same time and they are fed together by the paper feed roller 23, only the top one will be sent out to the conveyance path due to friction with the normal rotation roller 24a. The lower document is prevented from advancing due to friction with the stop roller 24b, and double-sheet feeding is prevented. (The paper feeding interval at this time is the length shown by l' in Figure 1.) The document fed into the copying machine 1 is temporarily stopped by a timing claw provided in the middle of the conveyance path so that it can move forward and backward. When it is detected that the photosensitive paper fed in synchronization with the insertion of the original into the copying machine has reached a predetermined position, the timing pawl is retracted from the original transport path and the original resumes its forward movement. The front edge of the photosensitive paper and the front edge of the photosensitive paper reach the polymerization point at the same time, and the leading edges are aligned, polymerized, and sent to the exposure section. Now, the interval between the documents sent out from the automatic document feeder 2 does not always have to be the same, and needs to be changed as necessary. The reason for this is explained below. In the case of "repeat mode" which circulates multiple copies of the same original within the copying machine body, for example, three copies of an A4-sized original or two copies of a B4-sized original can be placed in the circulation path within the copying machine at the same time. If circulation is possible, if you repeat three A4-sized documents, the speed of the documents will become uneven due to friction with the conveyance path and other causes, depending on the paper quality of the documents, etc. As a result, errors in the spacing between documents accumulate, and eventually a so-called "catch-up phenomenon" occurs in which the front edge of a later document catches up with the rear edge of the previous document, resulting in poor document passage detection and malfunction. Therefore, it is necessary to feed the documents from the automatic document feeder with the feeding interval as wide as possible within the repeat path. By the way, when feeding a B4 size (vertical feed) document from the automatic document feeder, the distance from the first document detection switch SWa of the automatic document feeder to the position of the above-mentioned timing claw for aligning the leading edge with the photosensitive paper is Because the length of the conveyance path is shorter than the length of the original, the interval between originals when they are completely fed out of the automatic document feeder is that while the next original is waiting with the timing claw, As the original is fed, the feeding interval becomes wider than the originally determined by the first original detection switch SWa, so the transport distance during the above original waiting time is longer than the original interval when feeding an A4 size (horizontal) original. There is no problem even if it is sent at short intervals. In addition, "One copy" is used to make one copy from one original.
In the case of "Two-One Mode", the document is exposed once and separated from the photosensitive paper and then ejected outside the machine, so even if there is some unevenness in the conveyance speed, the catch-up phenomenon will not occur, so the processing To improve your ability,
Regardless of the document size, it is better to make the document spacing as narrow as possible (as long as the document detection switch can respond). SUMMARY OF THE INVENTION In order to meet the above-mentioned demands, it is an object of the present invention to provide means for switching the document feeding interval of an automatic document feeder according to the copy mode and document size. Hereinafter, the present invention will be described in detail based on drawings showing embodiments thereof. In the embodiment shown in FIG. 2, a paper feed fan box 22 is provided on a paper feed table 21 in an automatic document feeder 2, and rear paper feed rollers 23a are provided at the front and rear thereof, respectively, and driven via a clutch MC1. and front paper feed roller 2 driven via clutch MC2.
3f is provided. In front of this, there is provided a double feed prevention roller consisting of a normal rotation roller 24a and a stop roller 24b, which are driven via the clutch MC2. In the document conveyance path continuing in front of the document conveyance path, two paper detection switches S1 and S2 are provided in order at intervals in the conveyance direction, then a pinch roller 25 is provided, and immediately after that, a paper detection switch S3 is provided. is connected to the document insertion section. This automatic document feeder is capable of feeding two types of document sizes, A4 and B4, and the rear paper feed roller 23a, which is driven via the clutch MC1, is especially suitable for feeding B4 size documents. The main paper feeding means, which is an auxiliary paper feeding means provided to facilitate conveyance, consists of a front paper feeding roller 23f and a normal rotation roller 24a, which are driven via a clutch MC2. The document front edge or rear edge detection signal from the paper detection switches S1, S2, and S3 is sent to the clutch MC1 by a changeover switch that is switched in conjunction with a copy mode selection switch on the copying machine and a document size discrimination switch operated by the document cassette. ，
Switch MC2 as shown in the table below to connect.

【table】

Claims (1)

[Scope of Claims] 1. A paper feeding means for a document placed on a paper feed tray, a first document detection means sequentially provided on a document conveyance path,
It has a pinch roller and a second original detection means, and stops the operation of the main paper feeding means in response to a detection signal detected by the second original detection means when the front edge of the original sent out onto the original transport path by the paper feeding means is detected. In the automatic document feeder, the operation of the paper feeding means is restarted in response to a detection signal detected by the first document detection means when the trailing edge of the document has passed, and the paper is fed at a predetermined paper feeding interval. The first document detecting means is composed of a plurality of paper detecting means disposed directly or indirectly at appropriate intervals in the document conveying direction, and the paper feeding means is switched to operate the paper feeding means. A paper feeding interval switching means characterized in that the paper interval is switched. 2. According to claim 1, the plurality of paper detecting means constituting the first document detecting means are switched in conjunction with a copy mode selection switch and a document size determination switch. paper feeding interval switching means.