JPH0221588B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improvement in a document size detection method in a copying machine that detects the size of a document placed on a document table. Conventionally, a copying machine that feeds sheet-like recording paper or roll-like recording paper of an appropriate size according to the size of the original placed on the document table, or cuts it, has been developed, for example, by Japanese Patent Laid-Open Publication No. It is known from Publication No. 11242/1983. The document size detection device in such a copying machine is provided with a light projector and a photoelectric conversion device arranged in parallel on the platen cover and the lower surface of the document table along the diagonal direction of the document table so that they face each other. This method detects the document size based on the size information of the output of the device. However, in such a document size detection device, a light projector or a photoelectric conversion device must be installed on the platen cover, which makes the device complicated due to processing and wiring of the platen cover, and the need for parallel photoelectric conversion devices. The output of the above-mentioned detection device may vary slightly due to variations in sensitivity, variations in the emission intensity of the light projector, and even external light entering through the gap in the platen cover, which may cause malfunctions in the selection of the recording paper size. There is a risk that this may occur. Therefore, as a detection device that improves the drawbacks of the document size detection device as described above, for example, a light retroreflection layer is provided on the document side of the document table cover, and the reflected light from the reflective layer is reflected by the light reflected from the document table cover. A device for detecting the size of a document by detecting it with a document size sensor is known, for example, from Japanese Patent Application Laid-Open No. 56-22424. According to such a device, the document size can be detected without providing a light projection device or a photoelectric conversion device on the platen cover. Furthermore, by utilizing the characteristics of the light receiving section made up of a detection element that can obtain a signal proportional to the wavelength regardless of the strength of the incident light, it detects reflected light or transmitted light from the colored portion that is not blocked by the document, A detection device that detects the document size based on the above-mentioned detection information of parallel detection elements is also disclosed in Japanese Patent Laid-Open No. 1983-1999.
It is known from Publication No. 22424. Proposed.
According to such a detection device, as mentioned above, there is extremely little risk of malfunctions caused by variations in sensitivity in the light receiving section, variations in emission intensity, and external light with a low intensity fraction of a specific wavelength. It has characteristics. However, the method of detecting the document size using the above-mentioned detection device requires, for example, applying a special reflective layer or coloring to the platen cover to detect the document size, or using a color sensor or the like as a detection member. Therefore, a complicated detection circuit must be used, making the device itself complicated, and it cannot be said to be advantageous in terms of cost. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the need for a platen cover to have a special light-receiving section or a colored surface for detecting the document size in a copying machine that places a document on a document table, and to replace the platen cover with a normal white surface. It is an object of the present invention to provide a document size detection method capable of accurately detecting the document size using a simple, inexpensive document size detection device that can be used. As a result of various studies to address the above-mentioned problems, the inventors of the present invention have provided a platen cover for covering a document on a document table, which has no coloring or other processing applied to the surface on the document table side to detect the size of the document; A light projector installed below the document table that emits light towards the document table surface, and a light projector installed below the document table that receives the light emitted by the projector and reflected on the document surface and generates a document signal. In the copying machine, the platen cover is equipped with a document size detecting means comprising a document presence/absence detecting means provided on the document table and a means for determining the size of the document on the document table based on a signal from the document presence/absence detecting means. It has been found that the above object can be achieved by a copying machine characterized in that it is provided with a switch that generates a signal for detecting the size of the document by the document size detection means while the copying machine is being closed. That is, according to the detection method of the present invention, the size of the document placed on the document table can be detected with the platen cover half open, so even if there is outside light, it is blocked to some extent, so that the outside light is blocked to some extent. The light from the light source is not reflected where there is no document, and is reflected only where the document is, so the document size can be detected reliably, and the platen cover can be colored or a color sensor can be used. Since there is no need to provide a complicated circuit for this purpose, an inexpensive reflective sensor can be used, and cost reduction can be expected. Furthermore, since the document size detection according to the present invention is performed at the stage of setting the document and closing the cover, it is possible to shorten the copying time without taking extra time for pre-scanning for size detection. The present invention will be explained below based on the embodiments shown in the drawings.
FIG. 1 is a partial perspective view of a copying apparatus according to the present invention. In the figure, 1 is the platen cover, 2 is the original platen, and 3 is the platen cover.
Detection members A, 3B, and 3C each include a reflective sensor provided on the lower surface side of the document table 2. As shown in FIG. As the detection members 3A, 3B, and 3C, reflective sensors having a light emitting source and a light variable element are used. These detection members are interlocked with the scanning optical system by an appropriate mechanism in order to avoid the optical path during copying.
That is, the detection members 3A and 3C occupy the positions shown in the figure before the optical system starts scanning, but they retreat to the left at the same time as the scanning starts. The detection member 3B similarly rotates around the shaft 4 and retreats. The detection member 3A is used to determine the type of size of the document placed on the document table 2, that is, whether it is A series or B series.
It is arranged at the end of the side edge of the document table 2 closest to the scanning start position of the optical system. Further, the detection member 3B is for detecting the full size and half size of the document, and is arranged at a position slightly away from the scanning start position of the optical system in the center of the document table 2. Furthermore, the detection member 3C detects the presence or absence of a document on the document table 2, and detects the presence or absence of a document on the document table 2.
It is located approximately in the center of the side edge of the When a document is placed at a predetermined position on the document table 2, which has the detection members 3A, 3B, and 3C arranged on the bottom side as described above, and the platen cover 1 is closed, a circuit is activated and the document is placed in the A series. If so, the detection member 3
A outputs an H signal due to the light reflected from the original, and B
If it is a series, the detection member 3A outputs an L signal since there is no reflected light from the original. Similarly, when the placed original is full size, the detection member 3B outputs an H signal due to the reflected light from the original, and when it is half size, there is no reflection from the original.
The detection member 3B outputs a signal. In the document size detection method of the present invention, the size of the document placed on the document table can be determined by various combinations of output signals from the detection members 3A and 3B as shown in Table 1 below. According to the detection method of the present invention, paper corresponding to the size of the original can be sent and fed based on the output signal from the original.

[Table] Next, the document size detection method of the present invention will be explained in more detail with reference to the embodiments shown in FIGS. 2 and 3. FIG. 2 illustrates the proper arrangement position of the sensing members according to the present invention. In the present invention, there are four original sizes, A3, B4, A4, and B5, and these can be applied to a copying machine placed in the position shown in FIG. Therefore, the detection members 3A and 3B are composed of reflective sensors.
and 3C are respectively arranged at positions on the lower surface of the document table suitable for detecting the size of the document placed on the document table and the presence or absence of the document. That is, in the figure, the detection member 3A is provided at a position suitable for determining whether the original is A-series or B-series, 3B is for determining the size of the original, and 3C is for determining the presence or absence of the original on the original table. ing. Naturally, in the case of copying machines in which the original document placement position is specified differently, the positions of the respective detection members are also changed accordingly. FIG. 3 is a circuit diagram for detecting the type, size, and presence or absence of a document using each of the detection members shown in FIG. That is, FIG. 3 shows a circuit for generating a document size signal based on information from detection members 3A and 3B for detecting the document size, a detection member 3C for detecting the presence or absence of a document, a platen cover switch, and a copy switch. The detection member 3A includes light emitting diodes 10 and 11, phototransistors that detect light emitted from the diodes and reflected by the original, and 42 a comparator that turns HIGH when the phototransistor 11 receives light.
become. Although the description of the detection members 3B and 3C has been omitted, they also have a similar configuration. The platen cover switch 20 is a switch that is turned on when the platen cover is placed on the sheet document. Specifically, the platen cover switch 20 is turned ON when the platen cover is placed on the sheet document.
Can generate an ON signal. One copy switch 21 is a switch that is turned on when copying. In the case of a sheet original, copying is performed by first covering the platen cover and then turning on the copy switch 21, but the platen cover switch 20 is turned on while the platen cover is completely covered.
At this point, the one-shot multi 23 generates a pulse via the OR circuit 22, sets the D-flip, flops 24, 25, and 26, and detects the signals from the detection members 3A, 3B, and 3C. Load. Next, the copy button switch 21 is turned on, but in this case, the output of the OR circuit 22 remains unchanged. In this manner, in the case of copying a sheet original, the original size is read while the platen cover is being closed, that is, while the platen cover is not completely closed and is still open. Further, when copying a thick original such as a book, the copying may be performed without the platen cover switch 20 being turned on. That is, the copy button switch 21 may be turned on while the platen cover switch 20 is not turned on. In this case, by turning on switch 21,
Since the OR circuit 22 is in the HIGH state, signals from the detection members 3A, 3B, and 3C are read in the same manner as described above. The AND circuits 27, 28, 29, and 30 detect the original depending on the output mode of the detection members 3A, 3B, and 3C.
This is a logic circuit that outputs a signal indicating whether it is A3, B4, A4, or B5. The operating mode of this logic circuit is as shown in Table 1, which will be explained shortly. For example, in the case of an A3 size document, the detection member 3A,
3B, 3C In other words, flip-flop 24,
Since the outputs of 25 and 26 are all HIGH, 27
The output of is HIGH, the output of 28, 29, 30 is
becomes LOW. Also, if there is no manuscript, 27,2
Outputs 8, 29, and 30 all become LOW, and the presence or absence of a document is also detected. Furthermore, if the document is not set correctly, for example, a B5 document may be placed on the detection member 3B.
If only 3A and 3C are set to the position where they are detected and not detected, the Q of flip-flop 24 is
LOW is HIGH, Q of 25 is HIGH, but
LOW, Q of 26 becomes HIGH, and the outputs of AND circuits 27, 28, 29, and 30 all become
It becomes LOW, indicating that the original is not set correctly. Note that it is of course possible to construct a circuit so as to output different signals depending on whether there is no original or when the original is not set correctly. Of course, the signal processing from the sensing member can be performed by a microcomputer. It is well known to feed copy paper that matches the original size from a paper feeder loaded with copy paper of various sizes based on an original size detection signal, and the original size detection device of the present invention It can be used in such automatic paper feeding devices. Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited thereto, and various modifications are possible. For example, the detection members 3A and 3B placed at the end of the document table may be attached to a scanning optical system. Further, in a copying machine with a movable document table, the detection member can be placed outside the exposure path, so the detection member may be fixedly installed without being moved as described above. As described above, according to the apparatus of the present invention, the switch is turned on while the platen cover is closed and the document size is detected accordingly, so it is not necessary to perform special processing on the platen cover to detect the document size. Document size detection can be performed with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of a copying apparatus according to the present invention, FIG. 2 is a plan view showing the arrangement of a detection member in the same apparatus, and FIG. 3 is a partial perspective view of a copying apparatus according to the present invention. It is a diagram showing a circuit. 1...Platen cover, 2...Original table, 3A,
3B and 3C...detection member, 20...platen cover switch, 21...copy button switch.

Claims (1)

[Claims] 1. A platen cover that covers the document on the document table, whose surface on the document table side has not been colored or processed to detect the document size, and a platen cover below the document table that irradiates light toward the document table surface. A light projecting device provided, a document presence detecting means provided below a document platen for detecting the presence of a document by light irradiated by the light projecting device and reflected from the surface of the document, and a signal from the document presence detecting device. In a copying machine equipped with a document size detecting means for determining the size of the document on the document table based on the size of the document on the document table, a signal for detecting the document size by the document size detecting means is sent while the platen cover is being closed. A copying machine characterized by being equipped with a switch that generates a signal.