JPH0792592B2 - Document detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document detection device provided with a determination means for optically detecting a document placed on a document table and determining the presence or absence thereof.

<Prior Art> It has been conventionally performed to optically detect a document placed on a document table to detect the presence or absence of the document and the size thereof. 5 and 2 show an example of the document size detecting device.

As shown in FIG. 2, an original table 2 is provided on the upper surface of the copying machine main body 1, and an original cover 3 is provided above the original table.
Is attached so that it can be opened and closed. The document 4 is placed with the corner of the document aligned with the corner C of the document table 2.

FIG. 3 shows the upper surface of the copying machine shown in FIG. 2 with the original cover open. In the figure, 6 is a circuit board provided in the main body of the copying machine, and a plurality of light emitting elements 7a to 7g and a plurality of light receiving elements 8a to 8g are attached to the circuit board in pairs. The area indicated by A in the figure represents the position where the reflector 10 opposes when the document cover is closed, and the light emitted from each light emitting element passes through the document table end portion of this area A, The light is reflected by the reflector 10 provided on the document cover, is transmitted again through the end portion of the document table, and is guided to each light receiving element.

FIG. 5 is a partial sectional view showing an optical path between the light emitting element 7 and the light receiving element 8. The figure shows a state in which the original cover 3 is closed on the upper side of the original table 2. The original cover mat 11 is attached to almost the entire inner surface of the original cover 3, and the reflection tape 10 is attached to the end portion. There is. A reflection plate 9 is attached below an end portion indicated by the area A of the document table, and light emitted from the light emitting element 7 is reflected by the reflection plate 9 and transmitted through the document table 2 to form a reflector 10. And then reaches the light receiving element 8 again. The optical path is formed in this way. Therefore, as shown by (4) in the drawing, when the end portion of the document exists in this optical path at a position where the end portion of the document is blocked, the light is blocked in the middle and the light is not guided to the light receiving element 8.

By analyzing the output voltage of the light receiving element 8 that appears as described above, the presence or absence of the document and its size can be detected.

<Problems to be Solved by the Invention> In such a conventional document detecting apparatus, the forward path and the return path of the optical path are set to the same path as shown in FIG. On the other hand, it was necessary to set the optical path vertically. For this reason, of the light emitted from the light emitting element 7, a part of the light reflected on both end surfaces of the table glass is
The light is incident on the light receiving element 8 through the return path, and the difference in incident light depending on the presence or absence of the original document becomes small, so that an erroneous detection is performed despite the original document being placed. This is because the light emitting and light receiving elements are arranged on the same surface side, and when the light emitting and light receiving elements are arranged on different surface sides, such a problem does not occur. On the other hand, by arranging the light emitting and light receiving elements on the same surface side, since the respective elements can be arranged on the same substrate, it is possible not only to reduce the arrangement space, but also to adjust the arrangement of the light emitting and light receiving elements on the same surface side. It is very convenient because it can be done. However, when they are provided on the same side, the above-mentioned problem cannot be solved.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and makes it possible to reliably detect the presence or absence of a document and its size in a copying machine in which a corner of a document is placed in alignment with a specific corner of a document table. It is an object of the present invention to provide a document detection device that has been used.

<Means for Solving Problems> A document detecting apparatus according to the present invention includes a transparent document table provided on the apparatus body for placing a corner of a document in alignment with a specific corner, and the apparatus body. A manuscript cover that is openably openable and covers the manuscript table, and a surface of the manuscript cover that faces the manuscript table in a state where the manuscript cover is closed. A reflector provided at a position corresponding to the non-image area apart from the document table surface and reflecting light, and one side end of the document table from a light emission start point on the non-image area side in a state where the document cover is closed. Is arranged in the non-image area of the one side end of the lower part of the document table in the forward light path that passes through to the reflector, and is reflected by the reflector and passes through the one side end of the document table again. The first light path and the original placed on the original table A first reflecting plate that reflects the light from the light emission starting point to the reflector so that the second returning path reflected by the first reflecting plate deviates from the second returning path; A second reflecting plate disposed on one end side, which reflects the light of the first return path without reflecting the light of the second return path and reflects the light toward the light emission start point side of the forward path; At least one set of a light emitting element and a light receiving element are arranged at a start point position and an end point position on the non-image area side which is an end point when the light on the first return path is reflected by the second reflecting plate. It is characterized by further comprising: a detection unit for detecting the presence or absence of the original document, and a determination unit for determining the presence or absence of the original document according to the light receiving state of the light receiving element of the detection unit.

<Operation> According to the document detecting apparatus of the present invention, when the document cover is closed, the light path of the light emission and the light receiving element of the document detecting means, that is, the light from the light emitting element causes one side edge of the non-image area of the transparent document table. An optical path is formed through which light is transmitted, reflected by a reflector located above the original table surface facing the non-image area, and received by the light receiving element.

At this time, if the document is placed on the document table, it is reflected by the placed document in the middle of the optical path, that is, without being reflected by the reflector. The second return path, which is the reflected light path, is largely displaced from the first return path reflected by the reflector even if the reflection direction is the same. Therefore, the first
The light passing through the returning path is reliably guided to the light receiving element by the second reflecting plate. However, the light on the second return path reflected by the original is hardly reflected by the second reflector and is not guided to the light receiving element.

From the above, the amount of light from the light emitting element guided to the light receiving element is completely different depending on whether the document is present or not, so that the presence or absence of the document can be reliably detected. Moreover, the optical means arranged to form the above-mentioned optical path can be arranged corresponding to the area where no image is formed. This is
The first reflector and the second reflector do not interfere with the projection of the image, and the image is not formed.

<Embodiment> FIG. 2 is a schematic view showing the outer appearance of a copying machine using an original detecting device according to an embodiment of the present invention. As shown in the figure, an original table 2 is provided on the upper surface of the copying machine main body 1, and an original cover 3 is attached to the upper side of the original table so as to be openable and closable. The document 4 is placed with the corner of the document aligned with the corner C of the document table 2.

FIG. 3 shows the upper surface of the copying machine shown in FIG. 2 with the original cover open. In the figure, reference numeral 6 is a circuit board provided in the main body of the copying machine, and a plurality of light emitting elements 7a to 7g and a plurality of light receiving elements 8a to 8g are attached to the circuit board in pairs. The area indicated by A in the figure represents the position where the reflectors face each other when the document cover is closed, and the light emitted from each light-emitting element 7 is transmitted through the document table end portion of this area and is provided on the document cover. Each of the light receiving elements 8 is reflected by the reflected reflector and again passes through the edge of the document table.
Be led to.

FIG. 1 is a partial sectional view showing an optical path between the light emitting element 7 and the light receiving element 8. The figure shows a state in which the document cover is closed on the top of the document table, and the document cover mat 11 is attached to almost the entire inner surface of the document cover 3. A reflection plate 9 is attached below the end portion indicated by the area A of the document table, and the light emitted from the light emitting element 7 is reflected by the reflection plate 9, transmitted through the document table 2, and reflected by the reflector 10. The light is reflected, transmitted again through the document table 2, and then reflected by another reflecting plate 9a attached below the reflecting plate 9 to reach the light receiving element 8.

At this time, the light reflected by the upper surface and the lower surface of the original table 2 passes through an optical path different from the light reflected by the reflector 10 and is not irradiated on the reflecting plate 9a, and therefore does not enter the light receiving element 8.

As described above, the light-emitting element 7 is the starting point of the optical path, the light-emitting element 7 → reflector 9 → the reflector 10 is the outward path, and the light-receiving element 8 is the end point of the optical path. The configuration in which the return path of 8 is different, that is, the forward path (outgoing light path) is the reflector 10
The forward light path and the backward light path are formed by arranging the reflection plate 9 which is an optical means so as not to be in the same direction as the backward path (return light path) reflected by. The optical paths of the forward path and the backward path are formed differently by the optical means including the reflector 9, the reflector 10 and the reflector 9a, and the light emitting element 7 is formed on the same circuit board 6 as the start point and the end point of the forward path and the return path. The light receiving element 8 is appropriately arranged and electrically wired. Here, as shown in FIG. 1, the reflector 10 provided on the document cover 3 and facing the document table 2 is provided in a state of being largely separated from the document table surface. This is because the original 4 does not exist in contrast to the reflection optical path (second returning path) in which the light from the light emitting element 7 is transmitted through the original table 2 through the optical means and reflected by the original 4 placed. Optical path that passes through 2 and is reflected by the reflector 10 (first return path)
Is largely deviated.

Therefore, the light in the first optical path reflected by the reflector 10 and the light in the second optical path reflected by the original are distinguished from each other, and particularly the first optical path is reflected.
It is possible to easily form an optical path in which only the reflected light in the returning path is reflected by the reflecting plate 9a which is the optical means and is guided to the light receiving element 8.
In particular, the reflector 9a can be easily arranged at a position where the light in the second return path is not reflected but the light in the second return path is distinguished and reflected.

As described above, in FIG. 1, when the document (4) is placed at the reference position on the document table 2, the light from the light emitting element 7 is reflected by the reflector 9 and the document 4 on the document table 2 is reflected. It becomes the optical path O ₁ reflected at. Further, a part of the light reflected by the lower end surface of the document table 2 is reflected as shown by the optical path O ₂ . These optical paths
O ₁ and O ₂ are not guided by the reflection plate 9a and do not reach the light receiving element 8. On the other hand, if the original 4 is not provided (including originals that do not block the optical paths of the light emitting and receiving elements 7 and 9, such as small originals), the light emitting element 7 → reflector 9 → the outward path of the reflector 10 and the reflector 10. → Reflector 9a → Light is incident on the light receiving element 8 through the return path of the light receiving element 8.

Here, an optical path is formed at the end of the original table 2, and the image of the end of the original that interrupts the optical path is not guided to the photoconductor and is not copied. However, since this part originally peels the paper from the photoconductor, Since it corresponds to the void area of, the copyable range does not become narrow. Corresponding to the void area, that is, the area (non-image area) A where an image is not formed, as shown in FIG. 1, the optical means such as the reflector 10 and the reflection plates 9 and 9a and each optical path are formed. Therefore, at the time of image formation,
The reflectors 9 and 9a and the like do not interfere, and the reflectors 9 and 9a and the like can be arranged in the area.

FIG. 4 shows a circuit of a document detecting device using the light emitting element 7 and the light receiving element 8.

The CPU 12 operates according to a program written in advance in a program area in the memory 14, and detects the document size at a necessary timing such as when the operation panel 13 is operated. CPU12 is provided with a plurality of output terminals and a plurality of analog input terminals, and of which represents about one output terminal O _n and one analog input terminal AN _n in FIG. 7 represents a light-emitting diode (light emitting element) is connected to the output terminal O _n of the CPU through a resistor R1 and an inverter I. Therefore, when the CPU _{sets On} to "L" level, the output of the inverter I becomes "H" level and the light emitting diode 7
Emits light. Reference numeral 8 represents a photodiode (light receiving element), to which a reverse bias voltage is applied via a resistor R2.
OP represents an operational amplifier, and the voltage signal at the connection point between the anode of the photodiode 8 and the resistor R2 is the capacitor C1 and the resistor R3.
After the direct current component is cut off by, it is input to the non-inverting input of the operational amplifier OP. This op amp OP has resistors R6 and R4
A feedback circuit is formed by and performs amplification at an amplification factor determined by these resistance values. The output signal of the operational amplifier OP is input to the analog input terminal AN _n of the CPU 12 via the resistor R5. The CPU reads the voltage of AN _n and compares it with a predetermined reference value to determine the light receiving level of the light receiving element 8. The circuit shown in the figure shows only a pair of a light emitting element and a light receiving element, but in reality, only the required pairs of light emitting elements and light receiving elements are provided, and the light receiving level of each light receiving element is determined. The size of the original can be detected as well as the presence or absence of the original.

For example, it is possible to determine whether or not a document is placed on the document table 2 according to the light receiving level of the light receiving element 8, and in response to the light receiving levels of the plurality of light receiving elements 8, the size of the placed document is determined. It will be possible to determine.

<Effects> As described above, according to the document detecting apparatus of the present invention, the light from the light emitting element can be surely guided to the light receiving element when the document is not placed, and the document is placed. Thus, the optical path can be easily set so that the light does not enter the light receiving element, and the presence or absence of the original can be accurately detected. As a result, an accurate and stable document size can be detected by the light receiving states of the plurality of light receiving elements.

In addition, since each reflection plate that forms each optical path for detecting a document can be arranged corresponding to the same surface side where an image is not formed, the reflection plate does not get in the way during image formation and can be easily placed in the area. It is very convenient because not only the reflector can be placed on the side, but also the placement space can be reduced and the optical path can be adjusted on the same side.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a copy showing an optical path of a document size detecting apparatus according to an embodiment of the present invention, FIG. 2 is a schematic external view of a copying machine using the document detecting apparatus, and FIG. 3 is the same copying machine. FIG. 4 is a top view of the original document cover in the opened state, FIG. 4 is a circuit diagram of the original document detection device, and FIG. 5 is a partial sectional view showing an optical path of the conventional original document detection device. 2: Original plate, 3: Original cover, 4: Original, 7: Light emitting diode (light emitting element), 8: Photo diode (light receiving element), 9: Reflector, 9a: Reflector, 10: Reflector

Claims (2)

[Claims] 1. A transparent manuscript table which is provided on the main body of the apparatus for placing a corner of a manuscript in alignment with a specific corner, and a manuscript which is provided on the main body of the apparatus and can be opened and closed to cover the manuscript table. A cover and a surface of the document cover facing the document table, with the document cover closed, separated from the document table surface at a position corresponding to a non-image area at one end of a particular corner of the document table; And a reflector that reflects light, and in the forward light path from the light emission start point on the non-image area side through one side edge of the document table to the reflector with the document cover closed. And a first light-returning path that is disposed in the non-image area at the one side end of the lower part of the document table, is reflected by the reflector, and again passes through the one side end of the document table, and is placed on the document table. Light is emitted so that it deviates from the second return path reflected by the original. A first reflecting plate formed by reflecting light from a point to the reflector, and a first reflecting plate, which is arranged on the one end side of the lower part of the document table, like the first reflecting plate, and which reflects light from the second returning path. A second reflection plate that reflects the light on the first return path without reflecting it toward the emission start point side of the forward path, the start point position of the forward path, and the light on the first return path Detecting means for detecting the presence or absence of a document, in which at least one set of light emitting element and light receiving element is arranged at the end point position on the non-image area side which is the end point when reflected by the second reflecting plate; An original detection device comprising: a determination unit that determines the presence or absence of an original according to the light receiving state of a light receiving element. 2. The document detecting apparatus according to claim 1, wherein the discriminating means discriminates the document size according to the light receiving states of a plurality of light receiving elements of the detecting means.