JPH02256042A - Original size detecting device for copying machine - Google Patents

Abstract

PURPOSE:To accurately detect the size of an original by providing a reflecter which is opened and closed separately from an original cover on an optical path where light from a light emitting means is received by a light receiving means. CONSTITUTION:In order to detect the size of the original 3 placed on an original platen 1 which is provided on the upper part of a copying machine main body, plural sensors 4 consisting of the light emitting and the light receiving means 41 and 42 are arranged according to the size of the original at proper positions on the copying machine main body side. The reflecter 5 for reflecting the light from the light emitting means 41 to the light receiving means 42 is provided on the way of the optical path where the light from the light emitting means 41 irradiates the light receiving means 42 through the original 3 on the original platen 1, and the size of the original 3 is detected in accordance with the light receiving state of the light receiving means 42. Namely, the light from the light emitting means 41 is reflected by the reflecter 5 to be received or not to be received by the light receiving means 42 in accordance with the existing state of the original 3. Thus, the size of the original is accurately detected regardless of thickness or color.

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 Unexamined Patent Application Publication No. 53-110837, an uneven surface is formed on the surface of the document cover facing the document table, and a placed document is scanned to distinguish the document from the document cover. The original size is being detected.

Further, according to Japanese Patent 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 may float on the original.
If the position of the reflective member changes, it may not be possible 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.

In addition, the surface of the document cover that faces the document table is made of a material that can be deformed to fit the document placed on it. Detection becomes 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 consisting of light receiving means are arranged at appropriate positions on the copying machine main body side, and the light from the light emitting means is received 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 toward the light receiving means, and detects the size of the document according to the light receiving state of the light receiving means, and the reflector is separate 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 the light-emitting means is provided so as to be openable and closable, and the light-emitting means and the light-receiving means of the sensor are arranged 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. 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, the light path passing through the document table by the light emitting means and the light receiving means constituting the sensor is changed. Established. 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 is blocked by the original, regardless of its color, and the light is surely 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.

<Embodiment> 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, reference numeral 1 refers to a document platen made of a transparent glass plate provided at the top of the copying machine body, and reference numeral 2 refers to a document cover 3, which is pivotally supported on one side of the copying machine body and can be opened and closed with respect to the document platen L. 4 is a sensor for detecting the size of the document placed on the document table ■; the sensor 4 includes a light-emitting element 41 (for example, a light-emitting diode, etc.) with directivity to the extent that crosstalk does not occur; Light receiving element 42 (
For example, it is composed of a photodiode, etc.).

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 l.

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 according to the closing operation of the document cover 2.

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.

The sensor 4 transmits light from the light emitting element 41 to the document table 1.
A light receiving element 42 is arranged at a position where the light is transmitted through the light and reflected by the reflecting plate 5, and receives this reflected light.

Each of the sensors 4aI, 4b, and 4C1, particularly 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 by 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 A 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. In other words,
After opening the document cover 2 and placing the document 3 on the document table L,
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 l, but is absorbed and reflected by the presence of the original 3 and is not reflected by the reflecting plate 5. However, if the original 3 does not exist, the light from the light emitting element 41 will not be blocked, and as shown in FIG.
Most of the light is reflected by the light receiving element 42 . 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 an example of a device for detecting whether or not a document 3 is placed corresponding to each of the above-mentioned sensors 4a to 4c. Light emitting diode 41 of sensor 4
is driven to emit light according to the generation cycle of the pulse signal from the signal generator 6. Also, the photodiode 42 of the sensor 4
The received light signal is applied to an amplifier 8 via a differentiating circuit 7. The amplifier 8 inputs its output to the compared input terminal of the comparator 9. The reference input terminal of comparator 9 is connected to the power supply +V.
A voltage obtained by dividing CC is supplied. In this circuit, light from the light emitting diode 41 is incident on the photodiode 42 if no document 3 is placed. As a result, the received light signal is amplified via the amplifier 8,
This amplified voltage becomes higher than the reference voltage of comparator 9. Therefore, the output of the comparator 9 becomes "H". On the other hand, if there is a document 3, the light reception signal of the photodiode 42 is very small (and since the reference voltage input terminal of the comparator 9 is higher, the output signal becomes "L").

Therefore, while the document cover 2 is closing, the reflector 5 is rotated at an angle of θ.
In this state, the presence or absence of a document can be detected according to the output state of the comparator 9 by driving the light emitting diode 41 at a constant cycle. And each comparator 9 according to the original size
The document size can be detected according to the output status. 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, reliable detection is possible regardless of the color etc. of the original 3.

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, each sensor 4a to 4cll: detects the presence or absence of II3, and the presence or absence of the document 3 can be accurately detected regardless of whether the document 3 is in a color such as black. The document size can be detected as shown in the table below according to the detection state of the document by 4a to 4C.

As shown in the above table, when the original 3 of size B is placed on the original platen 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 become "L", and the output from the sensor 4C becomes "H".Thereby, it is detected that the B4 size document 3 is placed.

Figure 4 shows a comparison 'a' detected by each sensor 4a to 4c.
9 is a logic circuit diagram for performing size detection according to the output state from 9. FIG. In the figure, the outputs from the respective sensors 4a-4C are applied to the three-person gates Aa-Ac either directly or via inverters 1a-Ic. anime)
Aa outputs a detection signal indicating a size smaller than A4;
B outputs detection signals indicating A4+Ac and A, respectively.

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, by detecting multiple paper sizes in the cassette installed in the copier,
A match is made with the original size detection signal, and based on this matching signal, paper corresponding to the original size is selected and automatically fed. In addition, when performing a variable size copy, it is also used as a signal to select a paper size according to the variable magnification of the original size, or to set a magnification determined by the original size and paper size.

Effect> 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 receiving device. By providing this, 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.
In addition, since it is provided separately from the document cover, it is not affected by deformation of the document cover, and when the reflector is opened, an optical path between the light emitting means and the light receiving means can be established, so that the size of the document can be accurately detected.

[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 31 Original 4 (4a, 4
b, 4c); Sensor 5: Reflector plate 41 (41a, 41b, 41c); Light emitting element 42
(42a, 42b, 42c); Light-receiving element 9; Comparators Aa to Ad, and an AND gate that outputs each document size signal. Agent: Patent attorney Takeshi Sugiyama (1 other person)

Claims (1)

[Claims] 1. In order to detect the size of a document placed on a document table provided at the top of the copying machine main body, a copying machine is provided with a plurality of sensors consisting of light emitting and light receiving means according to the document size. A reflecting plate is disposed at an appropriate position on the main body side and reflects the light from the light emitting means to the light receiving means 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 configured to detect the size of a document placed on a document table according to the light receiving state of the light receiving means,
The reflective plate is provided so as to be openable and closable separately from the document cover that covers the document table, and when the reflector is opened, forms an optical path so that the light from the light emitting device is irradiated onto the light receiving device via the document table. A document size detecting device for a copying machine, comprising a light emitting means and a light receiving means of the sensor arranged in a positional relationship for the purpose of detecting the size of a document.