JPH0451815B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Technical Field> The present invention relates to a document size detection device for detecting the size of a document placed on a document table of a copying machine. <Prior art> In order to detect the size of the original placed on the original table provided at the top of the copying machine, multiple sensors consisting of light-emitting elements and light-receiving elements are arranged at appropriate locations depending on the original size. are doing. For example, according to Japanese Patent Application Laid-Open No. 53-110837, by forming an uneven surface on the surface of the document cover facing the document table and scanning the placed document, the document and the document cover can be distinguished. The original size is being detected. Further, according to Japanese Patent Application Laid-open No. 56-62274, a colored portion is provided in a part of the document cover, and the size of the document is detected by detecting the state in which the colored portion is covered by the document. <Problems to be Solved by the Invention> As described above, according to the conventional document size detection device, the document size cannot be detected unless the reflective member formed directly on the document cover is placed on the document table. It won't happen. Therefore, if the original is thick, the reflective member will float on the original, and the position of the reflective member will change, making it impossible to detect the original, resulting in erroneous detection. Moreover, in order to distinguish between the original and the original cover, it is necessary to provide the original cover with a colored part or an uneven surface different from the white part. Therefore, when copying onto a sheet of paper larger than the original, a black image is copied due to specular reflection of the colored portion or the uneven surface, making the copy extremely difficult to see. Moreover, if the color of the document is the same as the color of the colored portion, for example, it cannot be detected, resulting in erroneous detection. Also, the side of the document cover that faces the document table is
Since it is made of a material that can be deformed to match the placed document, the angle of reflection due to the uneven surface or colored portion changes greatly, making normal detection impossible. In view of the above-mentioned problems, the present invention solves the drawbacks of the conventional document size detection device, ensures the presence or absence of a document, and accurately detects the size regardless of whether the document is thick or colored. It provides equipment. <Means for Solving the Problems> The document size detection device of the present invention detects the size of the document placed on the document table provided at the top of the main body of the copying machine. A plurality of sensors each consisting of a light receiving means are arranged at appropriate positions on the main body of the copying machine, and the light receiving means from the light emitting means is placed in the middle of the optical path in which the light from the light emitting means is irradiated to the light receiving means via the document on the document table. A document size detection device is provided with a reflector that reflects the light to the document and detects the size of the document according to the light receiving state of the light receiving means, and the reflector is opened and closed separately from a document cover that covers the document table. The light emitting means and the light receiving means of the sensor are arranged in a positional relationship such that when the reflecting plate is opened, the light from the light emitting means is irradiated onto the light receiving means via the document table to form an optical path. It is characterized by <Function> According to the document size detection device of the present invention, the reflective plate is provided so as to be openable and closable, and when the reflective plate is opened, an optical path is established through the document table by the light emitting means and the light receiving means constituting the sensor. be done. In this state, if the original is placed on the original table, the state for detecting the original size is completed. Therefore, the presence or absence of a document is detected by a sensor, and the light from the light emitting means is reflected by the reflecting plate and is received or not received by the light receiving means, depending on the presence state of the document.
In this case, even if the original is black, the light from the light emitting means will be blocked by the original, regardless of its color, and the light will be reliably received by the light receiving means depending on the state of the original. . The document size can be determined according to the light receiving state by this light receiving means. <Example> FIG. 1 is a side view of a copying machine in a document placement section showing a detection device of the present invention, and FIG. 2 is a perspective view of the copying machine shown in FIG. 1 with the document cover opened. In the figure, 1 is a document table made of a transparent glass plate provided on the top of the copying machine body, 2 is a document cover that is pivotally supported on one side of the copying machine body and can be opened and closed with respect to the document table 1, and 3 Reference numeral 4 indicates a document placed on the document table 1, and 4 a sensor for detecting the document size. The sensor 4 is a light emitting element 41 (for example, a light emitting diode, etc.) that has directivity to the extent that crosstalk does not occur.
and a light receiving element 42 (for example, a photodiode, etc.)
It is composed of. The document cover 2 is provided with a reflection plate 5 that is interlocked with opening and closing operations. Reflector plate 5 is provided separately from document cover 2, reflects light from light emitting element 41, and is formed in a size that does not cover document table 1. Further, the reflector 5 is configured to be opened and closed in accordance with the opening and closing of the document cover 2, so that if it is opened at an angle of θ or more, it is maintained at the angle θ even if the document cover 2 is opened at an angle greater than that. It has a structure that opens and closes in conjunction with the document table 1. When the document cover 2 is closed, the reflector 5 maintains the angle θ until the document cover 2 reaches a certain angle, and thereafter closes as the document cover 2 closes. Sensors 4 are provided with respect to the reflecting plate 5 at positions unrelated to optical scanning during image exposure, corresponding to the size of each original placed on the original platen 1. In the sensor 4, light from a light emitting element 41 passes through the document table 1 and is reflected by the reflecting plate 5, and a light receiving element 42 is disposed at a position to receive the reflected light. Each of the sensors 4a, 4b, and 4c, especially the sensor 4a, is provided in a position corresponding to, for example, an _A4 size document, so that light from the light emitting element 41 is blocked for a document of that size. Further, the sensor 4b is arranged to correspond to a _B4 size original, and the sensor 4c is arranged to correspond to an _A3 size original. The light-receiving element 42 of the sensor 4 is provided at a position away from the document table 1 of the main body of the copying machine and at a position to receive the light reflected by the reflection plate 5. In the above-described configuration, the principle of detecting the presence or absence of the document 3 in each sensor 4 will be explained. As shown in FIG. 1, the light emitting element of the sensor 4 is driven while the original 3 is placed on the original table 1 and the original cover 2 is closed. That is, after opening the document cover 2 and placing the document 3 on the document table 1, the sensor 4 is driven in response to the closing operation of the document cover 2. At this time, the reflection plate 5 is opened at an angle θ, and in this state, the sensor 4 is driven. The light from the driven light emitting element 41 is irradiated onto the original 3 via the original platen 1, but is absorbed and reflected by the presence of the original 3, and is not reflected by the reflection plate 5. However, if the document 3 is not present, the light from the light emitting element 41 is not blocked, and is mostly reflected by the reflecting plate 5 and directed toward the light receiving element 42, as shown in FIG. Therefore, there is a large difference in the light reception signal by the light receiving element between the state where the document 3 is present and the state where the document 3 is not present, and the presence or absence of the document can be detected reliably. This is completely unaffected by the color of the document 3. Here, if the light emitting element 41 has a certain degree of spread of luminous flux, light can be reflected to the light receiving element 42 within a certain width of the angle θ of the reflecting plate 5. FIG. 3 is a circuit diagram showing a specific example for detecting whether or not a document 3 is placed corresponding to each of the above-mentioned sensors 4a to 4c. sensor 4
The light emitting diode 41 is driven to emit light according to the generation cycle of the pulse signal from the signal generator 6. Further, the photodiode 42 of the sensor 4 applies the received light signal to the amplifier 8 via the differentiating circuit 7. The amplifier 8 inputs its output to the compared input terminal of the comparator 9. A voltage obtained by dividing the power supply +Vc.c. is supplied to the reference input terminal of the comparator 9. In this circuit, the light from the light emitting diode 41 is
If the document 3 is not placed, the light is incident on the photodiode 42. As a result, the light reception signal is amplified via the amplifier 8, and this amplified voltage becomes higher than the reference voltage of the comparator 9. Therefore, the output of the comparator 9 becomes "H". Conversely, if there is original document 3, the light reception signal of photodiode 42 is very small, and since the reference voltage input terminal of comparator 9 is higher, the output signal becomes "L". Therefore, while the document cover 2 is closing, the reflector 5
By driving the light emitting diode 41 at a constant cycle in a state where the angle is θ, the presence or absence of a document can be detected according to the output state of the comparator 9. Then, the document size can be detected according to the output state from each comparator 9 depending on the document size. The reference voltage of the comparator 9 is set so that when there is no document, the voltage from the amplifier 8 that amplifies the light reception signal is higher. Here, if the original 3 is black, the emitted light is not received by the light receiving element 42, so that the same output as if the original 3 were present can be obtained. Therefore, manuscript 3
Reliable detection is possible regardless of color etc. Furthermore, even if the document cover 2 is deformed or shakes, since the reflector 5 is constructed separately from the document cover, the reflector 5 will not be affected by the deformation of the document cover 2, etc. In the open state, an optical path between the light emitting element 41 and the light receiving element 42 can be established in a normal state, allowing accurate detection. As described above, the presence or absence of the document 3 is detected by each of the sensors 4a to 4c, and the presence or absence of the document 3 can be accurately detected regardless of the color of the document 3, such as black. Therefore, each of the above-mentioned sensors 4a to 4c
The document size can be detected as shown in the table below according to the detection state of the document.

[Table] As shown in the table above, when a _B4 size document 3 is placed on the document table 1, the light from the light emitting elements 41 of the sensors 4a and 4b is blocked and is not received by the light receiving element 42. The outputs from the sensors 4a and 4b are "L", and the output from the sensor 4c is "H". As a result, it is detected that the _B4 size document 3 is placed. FIG. 4 is a logic circuit diagram for detecting the size according to the output state from the comparator 9 detected by each of the sensors 4a to 4c. In the figure, the output from each sensor 4a-4c is applied to three-input AND gates Aa-Ac either directly or via inverters Ia-Ic. AND gate Aa outputs a detection signal indicating the size less than A ₄ , Ab is A ₄ , Ac is B ₄ ,
Ad outputs a detection signal indicating _A3 . The size detection signals from each of the AND gates Aa to Ad are used, for example, as a signal for selecting and automatically feeding paper according to the document size. For example, multiple paper sizes in the cassette installed in the copying machine are detected, a match is made with the above-mentioned original size detection signal, and the matching signal selects the paper according to the original size and automatically feeds the paper. . Also,
When performing variable-magnification copying, it is also used as a signal to select a paper size according to the magnification ratio of the original size, or to set a magnification determined by the original size and paper size. <Effects> As explained above, according to the document size detection device of the present invention, a reflection plate that is opened and closed separately from the document cover is provided in the optical path of the light from the light emitting device until it is received by the light emitting device. As a result, the optical path is established with the reflecting plate open, and the document size can be detected. Therefore, if there is no document, the light from the light emitting device is received by the light receiving device, and the presence or absence of the document can be detected regardless of the color of the document, even if the document is thick, and the size of the document can be accurately detected. In addition, the purpose of the reflector is only to reflect light, and there is no need to distinguish it from the document cover, and since it is provided separately from the document cover, it is not affected by deformation of the document cover, etc. When the plate is opened, an optical path between the light emitting means and the light receiving means can be established, allowing accurate detection of the document size.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a document placement section of a copying machine showing a specific example of the document size detection device of the present invention, FIG. 2 is a perspective view of FIG. 1, and FIG. FIG. 4 is a circuit diagram showing an example of an electric circuit. FIG. 4 is a logic circuit diagram for detecting the size of a document. 1...Original table, 2...Original cover, 3...Original, 4, 4a, 4b, 4c...Sensor, 5...
Reflector plate, 41, 41a, 41b, 41c... Light emitting element, 42, 42a, 42b, 42c... Light receiving element, 9... Comparator, Aa to Ad... AND gate that outputs each original size signal.

Claims (1)

[Scope of Claims] 1. In order to detect the size of the original placed on the original table provided at the top of the copying machine main body, a plurality of sensors consisting of light emitting and light receiving means are installed in the copying machine main body according to the original size. A reflecting plate is disposed at an appropriate position on the side of the document table, and a reflecting plate is provided in the middle of the optical path in which the light from the light emitting means is irradiated to the light receiving means via the document on the document table, and reflecting the light from the light emitting means to the light receiving means. The document size detection device detects the size of the document placed on the document table according to the light receiving state of the light receiving means, and the reflector plate can be opened and closed separately from the document cover that covers the document table. The light emitting means and the light receiving means of the sensor are arranged in a positional relationship to form an optical path so that the light from the light emitting means is irradiated onto the light receiving means via the document table when the reflecting plate is opened. Copy machine original size detection device.