JPS6342767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document size detection method in a copying machine.

In conventional copying machines, the operator selects one paper feed cartridge with the appropriate paper feed size and manually sets it, or the operator sets multiple paper feed cartridges and uses a lever to manually set the paper feed size to the appropriate size. There is a method for selecting paper feed cartridges. Furthermore, in the former case, there are many mistakes such as forgetting to replace the paper feed cartridge, and in the latter case, there are many mistakes such as forgetting to operate the lever to select the paper feed cartridge.

In addition, in a copying machine, Nesa Glass is applied to the glass surface of the document table, and the size of the document set between them is detected from the conduction state between Nesa Glass and conductive rubber, and the paper feed cartridge is selected based on the output. A method has been proposed. This method eliminates the need for the operator to select the paper feed cartridge and eliminates the above-mentioned mistakes, but since Nesa Glass is applied to the glass surface of the document table, it affects the copied image, and for book-type originals, Nesa Glass This makes it difficult to detect the document size because the conductive rubber cannot be electrically conductive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a document size detection method that can eliminate the operator's paper feed size selection operation, does not affect copied images, and can detect the document size even for book-type documents.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the invention. In a copying machine, an original 2 is set on the original platen glass 1 at a predetermined position depending on its size, and the original holding cover 3 is placed over it. With this original setting method, the difference in each original size is This is a method that appears as a difference in length in the scanning direction, and the left edge of each size of document is at a different position. When the copy start switch is turned on by an operator, scanning of the original is performed, and this scanning of the original is performed by keeping the original platen glass 1 fixed and moving the optical system to the left from the initial position. At the same time, the optical sensor 4 is moved and scanned at a constant speed from the initial position to the right by the drive system, emits infrared light toward the document table glass 1, and receives the reflected light. Additionally, the flip-flop 5 is reset by the count start signal from the control section, and its output is used to control the amplifier 6.
is enabled, and the output of the photosensor 4 is input to the reset input terminal R of the flip-flop 5 via the amplifier 6. Furthermore, a basic clock of a suitable constant frequency from the control section is passed through the AND circuit 7 by the output of the flip-flop 5 and is then input to the counter 8.
is counted. The optical sensor 4 scans the original holding cover 3 and the original 2 on a straight line parallel to the original scanning direction in a direction opposite to the original scanning direction, and an output as shown in FIG. 2 is obtained. This output is an edge signal a for the left edge portion of the original 2 and an image signal b for the image on the original 2.
The edge signal a is first obtained and the flip-flop 5 is reset. Then, the reset of the flip-flop 5 causes the amplifier 6 to become inoperable, the AND circuit 7 to fail, and the counter 8 to stop. Therefore, the contents of the counter 8 indicate the position of the left edge of the original 2, that is, the original size. The output of the flip-flop 5 is also sent to the control section to inform it that the document size has been measured as the value of the counter 8. The control unit reads the value of the counter 8 after measuring it, and uses the value to control the paper feed cartridge selection means to select the paper feed cartridge with the paper feed size that corresponds to the document size from among the plurality of set paper feed cartridges. Let them use it. Here, since the optical sensor 4 only needs to detect the left edge of the original 2, the scanning speed may be faster than the original scanning speed. Also, Figure 3 shows B5, A4,
Although the positions where B4 and A3 size originals are set are shown, the optical sensor 4 may be placed so as to scan a position C within a range l where all originals are placed. If the original size deviates significantly from the specified size, a second optical sensor that scans a position d outside the above range l is provided to detect the length of the original in a direction perpendicular to the scanning direction and select the paper feed size. You can also do that. That is, the control unit can detect whether the document is A or B based on the output of the second photosensor, detect the document size based on this and the value of the counter 8, and select the paper feed size.

As described above, the document size detection method according to the present invention automatically detects the document size, thereby eliminating the need for the operator to select the paper feed size.Furthermore, the edge of the document is detected by an optical sensor. Since the original size is detected, it does not affect the copied image, and the original size can be detected even for book-type originals. Furthermore, if the optical sensor scans in the same direction as the original scanning direction, it is necessary to distinguish between edge signals and image signals from the output of the optical sensor, but in the present invention, the optical sensor is scanned in the opposite direction to the original scanning direction, so the optical The first signal from the sensor becomes an edge signal and is easy to distinguish.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure is a waveform diagram showing the optical sensor output of the same embodiment, and FIG. 3 is a diagram for explaining the present invention. 1... Original table glass, 2... Original, 3... Original holding cover, 4... Light sensor, 5... Flip-flop, 6... Amplifier, 7... AND circuit, 8
……counter.

Claims (1)

[Claims] 1. In a copying machine that detects the original size and selects the paper feed size by setting the original on the original table so that the difference in each original size appears as a difference in length in the document scanning direction, the original on the original table An optical sensor is provided that irradiates light from the opposite side of the document and detects the reflected light.The optical sensor is scanned from the initial position in the opposite direction to the document scanning direction, and the output signal of this optical sensor is detected. A document size detection method characterized in that the optical sensor detects the document size by detecting that the optical sensor reaches the foremost edge of the document from an area outside the document on the document table.