JPH03175306A - Detecting apparatus for paper size or the like - Google Patents

Abstract

PURPOSE:To obtain high speed response by arranging each photodetecting element and an image forming optical system so that one of a plurality of photodetecting elements receives the regular reflection light from a paper to be detected and the other elements receive the reflecting diffusing light from the paper. CONSTITUTION:Photodetecting elements PDa, PDc, PDd among the four photodetecting elements PDa-PDd of a photodetecting array 23 are placed at such a position that they can detect the reflecting diffusing light from a document without receiving the regular reflection light from the surface of a glass plate 11. Moreover, the element PDb is placed where it can receive the regular reflection light from the glass plate 11 and the OHP document. In other words, the element PDb receives the regular reflection light having a reflecting angle theta equal to an angle of incidence theta of a beam spot Pb. The image forming lens 22 condenses the minute diffusing light from the document and forms an image of the reflecting diffusing light from each beam spot Pa, Pc, Pd onto the respective element PDa, PDc, PDd of the array 23. At the same time, the image forming lens 22 forms an image of the regular reflection light from the spot Pb onto the element PDb. In this manner, the apparatus becomes compact with the high-speed responding capability.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION Technical Field The present invention is typified by a document size determining device used in a copying machine. The present invention relates to a device for determining the size of paper, etc.

Prior Art and Its Problems Conventional document size determination devices installed in copying machines include a type that prescans using a photoelectric sensor as shown in Figure 14, and a type that uses a photoelectric sensor to prescan as shown in Figure 15, and a type that uses a photoelectric sensor to prescan as shown in Figure 15. There is a type that has a built-in proximity switch, etc.

In FIG. 14, a movable arm 53 is installed inside the copying machine 50.
is provided, and a large number of reflective optical sensors 54 are attached to this arm 53. Movable arm 5 before copying operation
3 moves, the original on the glass plate 51 is scanned by the photoelectric sensor 54 (prescan), and the size of the original is determined based on the output signal of the photoelectric sensor 54 at this time. This type of device has the advantage of being able to discriminate between a wide variety of document sizes, but the presence of movable parts makes the entire device large and its mechanism complicated. Since pre-scanning is required, the time involved becomes loss time, and there is a problem that prompt copying cannot be performed.

In FIG. 15, a plurality of proximity switches (for example, photomicro sensors, etc.) 55 are built into the upper M52 of the copying machine 50. As shown in FIG. When a document is placed on the glass plate 51 and the top lid 52 is closed, each proximity switch 55 detects the presence or absence of a document at the location where the proximity switch is installed, and the document size is determined based on the detection signals of the plurality of proximity switches 55. It will be judged. This type has an advantage over the prescan type shown in FIG. 14 in that it can save space. However, since the sensor is located on the top lid, the document size cannot be determined without the top lid.
This method cannot be applied to a copying machine with a liveFeed function, and if there is even a slight unevenness on the sensor, a suppression mark will be left on the original document. If the copy paper size is larger than the document size, there are problems such as the shadow of the sensor that is not hidden by the document appearing on the copy paper.

Furthermore, an overhead projector (over head projector) is used to project and enlarge one drawing, one diagram, etc. and display it on the screen.
Since an original (hereinafter referred to as an OHP original) is almost transparent, it is difficult for the above-mentioned conventional original size determination apparatus to detect this. In a copying machine that has a mode in which a copying operation is started only when the original size can be determined, if this mode is set, a problem arises in that the copying operation is not started in the case of an OHP original.

SUMMARY OF THE INVENTION OBJECTS OF THE INVENTION The present invention provides a size determining device for sheets, etc., which is small in size, has high-speed response, is capable of detection without a top cover, and is also capable of detecting the presence of an OHP document.

Structure 1 of the invention: Actions and effects A device for determining the size of paper, etc. according to the present invention is as follows.

A multi-beam light source that projects a plurality of light beams to different locations depending on the size of the paper to be discriminated; A light-receiving element and an imaging optical system that guides the plurality of reflected light beams to the corresponding light-receiving element are provided, and at least one of the plurality of light-receiving elements receives specularly reflected light from the paper to be discriminated.

The present invention is characterized in that the position of each light-receiving element and the arrangement of the imaging optical system are determined so that the other light-receiving elements receive the diffusely reflected light from the sheet of paper to be discriminated.

A plurality of light beams are projected onto different locations depending on the size of the paper to be discriminated, and diffusely reflected light from the paper is received by a plurality of corresponding light receiving elements. Although the intensity of the diffusely reflected light from normal paper is higher than that from the glass plate, if the output signals of the light receiving elements are discriminated at an appropriate threshold level, each light receiving element can detect the presence of paper. is possible. The combination of light-receiving elements that detect paper and light-receiving elements that do not detect paper changes depending on the size of the paper placed. Therefore, the size of the placed paper can be determined according to the combination of detection signals from the light receiving elements.

On the other hand, if an OHP original exists on the glass plate, the projected light beam is reflected by both the glass plate and the OHP original.

The amount of specularly reflected light reflected from both the glass plate and the OHP original is greater than the amount of specularly reflected light from the glass plate alone.
If the light that is specularly reflected by both the glass plate and the OHP original is received by a light receiving element, the presence of the OHP original can be detected based on the level of the output signal of this light receiving element, and in combination with the detection signals of other light receiving elements, the OHP It can be determined that it is a manuscript.

Since the apparatus for determining the size of paper or the like according to the present invention does not have a movable part, it can be made smaller.

Furthermore, since a pre-scan operation is not required, high-speed response is achieved.

Furthermore, when the discrimination device of the present invention is applied to a copying machine, there is no need to provide it on the top cover, so paper size can be determined without a top cover, and it can also be applied to copying machines with automatic paper feeding function. This is possible, and there is no problem of leaving pressure marks or shadows. The discrimination device according to this invention is
As mentioned above, it is also possible to detect OHP documents.

The multi-beam light source can be configured using one light emitting element and a grating that generates zero-order and high-order diffracted light from the light emitted from the light emitting element. This makes it possible to simplify the configuration of the multi-beam light source and reduce its size.

Further, the multi-beam light source is one light emitting element.

It can be constructed from an off-axis Fresnel lens φ array including a plurality of off-axis Fresnel lenses that divide the light emitted from the light emitting element into a plurality of parts and deflect them in different directions. With such a configuration, it is possible to downsize the multi-beam light source.

Furthermore, the multi-beam light source includes a plurality of light emitting elements,
It can be constructed from a projection lens that projects the light emitted from these light emitting elements in different directions. Since each of the plurality of projection light beams is emitted by a plurality of light emitting elements, the intensity of each projection light beam can be increased.
Therefore, since the intensity of the reflected light from the paper increases, the level of the received light signal becomes high and stable discrimination operation becomes possible.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to a document size determining device used in a copying machine will be described in detail.

In FIG. 1, a photosensor 20 for determining document size is placed at a suitable location inside a copying machine 10. As shown in FIG.

Copy a! The upper surface of 10 is covered with a glass plate 11, and two originals (white paper) 12 of various sizes or OHP originals 12A (see FIG. 8(C)) are placed at predetermined positions on this glass plate 11. It will be destroyed. The photosensors 20 are arranged at different positions p within the place where the original 12 on the glass plate lI is placed.
, p , p , p , by projecting a plurality (four in this embodiment) of light beams and receiving the reflected light from the glass plate 11 or the original 12 or the OHP original 12A. Size and OHP
Determine the existence of a manuscript. Or output a detection signal for discrimination.

An example of the configuration of the document size determination photosensor 20 is shown in FIG. The photosensor 20 has a case 29,
In this case 29, a multi-beam light source 21, an imaging lens 22, and a light receiving element array 23 are arranged and fixed. The multi-beam light source 21 includes one light-emitting element, for example, a light-emitting diode 24 that generates light including infrared light, and two light-emitting diodes arranged above the light-emitting diode 24. The multi-beam light source 21 divides the output light of the two light-emitting diodes 24 into four light beams, and collimates these light beams. and an off-axis micro Fresnel lens array 25 that projects images to different positions.

The light receiving element array 23 includes many light receiving elements.

In this embodiment, only four light receiving elements are used. Of course, it goes without saying that only the number of light receiving elements to be used may be arranged in the light receiving element array 23. Imaging lens 2
2, as will be described later, the projection light beam is mainly directed to the original 1.
Diffuse reflected light (diffuse reflected light) from 2 and OHP original 12
This is for forming an image of the specularly reflected light from A on the corresponding light receiving element. Visible light cut filters 28 and 27 are provided on the upper surface of the case 29 above the multi-beam light source 21 and the imaging lens 22, respectively. In this embodiment, infrared light is used to determine the document size.

Off-axis micro Fresnel lens array 2
A configuration example of No. 5 is shown in FIG. This lens array 25 includes a plurality of (four in this embodiment) off-axis micro Fresnel lenses (hereinafter referred to as off-axis MF).
(abbreviated as L) 25a.

25b, 25c, and 25d are arranged in a predetermined arrangement. The off-axis MFL is as shown in FIG.

It has the function of deflecting the incident light beam in a desired direction according to the shape of the unevenly spaced grating formed therein, and collimating the diffused light (also capable of condensing the collimated light). Such off-axis MFjs 25a to 25d have a grating pattern in which a portion of a micro Fresnel lens is cut out, as shown in FIG. 5, for example. Using the off-axis MFL array 25 shown in FIG. 3, the light beam emitted from one light emitting element 24 is divided into four parts and collimated, resulting in beam spots p arranged in a row as shown in FIG. , p
, p , p on the glass plate 11 a be
d can be made. Po indicates the position of the light emitting element 24.

FIGS. 7 to 11 show the principle of determining the document size and detecting an OHP document using the photosensor 20 described above.

As described above, the spreading light emitted from one light emitting element 24 is split into four light beams by the off-axis MFL array 25, collimated, and beam spots P to Pd of appropriate areas are placed on the glass plate 11 or original 12. Alternatively, the OHP original 12A is irradiated.

FIG. 8 shows how the projected light is reflected on the glass plate, the original, and the OHP original.

In FIG. 8(A), part of the projected light beam passes through the glass plate 11, the other part is specularly reflected on the front and back surfaces of the glass plate 11, and a small amount of light is diffusely reflected from the plate. . A curve A in FIG. 9 shows how the amount of light reflected from the glass plate 11 (the amount of light received by the light receiving element) changes with respect to the reflection angle. The angle α is the incident angle, and the amount of reflected light reaches its maximum value at the reflection angle α, which is equal to this angle.

In FIG. 8(B), when the original 12 is placed on the glass plate 11, most of the projected light is diffusely reflected by the original 12, and part of it is specularly reflected by the surface of the glass plate 11. Therefore, the amount of reflected light reaches its maximum value at a position where one reflection angle is equal to the incident angle α, as shown by curve B in FIG. 9, but the amount of reflected light is also at a considerably high level at other reflection angles.

In FIG. 8(C), an OHP original 1 is placed on a glass plate 11.
2A, most of the projected light is specularly reflected by the surface of the glass plate 11 and the OHP document 12A, and the other part is slightly transmitted or diffusely reflected. therefore,
The amount of reflected light in this case is as shown by curve C in FIG.
It shows a peak at a reflection angle α that is equal to the incidence angle α, and this peak value is higher than in the case of only the glass plate (curve A).
This is almost the same as when the original 12 exists. Further, at other reflection angles, the amount of reflected light becomes extremely small as in the case of only glass.

From the above, the following can be concluded.

Detects diffuse reflected light and calculates the amount of detected light (output of the light receiving element)
The presence of the original document 12 can be detected by discriminating the curve B using a threshold level Th1 that is slightly lower than that of the curve B.

The presence of the original 12 or the OHP original 12A can be detected by detecting the specularly reflected light and distinguishing the amount of detected light based on the level Th2 between the peak value of curve A and the peak values of curves B and C.

Note that in FIGS. 8(A) to 8(C), the arrows indicating one reflected light depart only from the bottom surface of the glass plate 11, but this is for convenience of illustration, and each arrow indicates the direction from the glass plate 11. This refers to all the light that is reflected from the top and bottom surfaces, the surface of the document, and the surface of the OHP document. The optical path of the reflected light differs when the height position of the reflecting surface differs, but this difference only depends on the thickness of the glass plate, so all of these reflected lights can be detected by each light receiving element described later, so there is no problem. do not have.

In FIG. 7, among the four light-receiving elements PD-PD in the light-receiving element array 23, the light-receiving element PDa.

PD and PDd are arranged at positions where they do not receive the specularly reflected light from the surface of the glass plate 11 but can detect the diffusely reflected light from the original 12. Other light receiving elements PD, glass plate 11 and O
It is placed at a position where it can receive specularly reflected light from the HP original 12A. That is, the light receiving element PDb receives specularly reflected light having a reflection angle θ equal to the incident angle θ of the beam spot Pb.

The imaging lens 22 collects the weak diffused light from the original 12 and separates each beam spot P, P, Pd or a.
The diffusely reflected light from C is imaged onto the corresponding light receiving elements PD, PD, PD of the light receiving element array 23.
C and functions to image the specularly reflected light from the beam spot Pb onto the light receiving element P D b.

In this example, three light beam spots P, P, Pd
Using the diffusely reflected light from the beam and the specularly reflected light from the pot Pb, A5°B5. B
5R, A4. It discriminates seven types of document sizes, A4R, B4, and A3, and detects the presence of an OHP document. The vertical and horizontal arrangement of B5R and A4R is reversed from that of the other A5 to A3. [Glass plate] 1, the positions on which the originals of each size are placed are determined in advance, so each beam spot P is adjusted in relation to the original position.
The multi-beam light source 21 is adjusted so that -Pd is formed at the position shown in FIG.

Since an OHP document is generally A4 size, the beam spot Pb is set at a position where it can detect A4 size paper.

Figure 11 shows the size of the placed original, the type of OHP original, and the diffuse reflection light from the original or the original or OHP original.
Photo-receiving element PD-PD that receives specularly reflected light from the original
This shows the relationship with the output of d. Photodetector PD
, PD, PD, and the received light C signals are level-discriminated by the above-mentioned threshold value T h l.

It is converted into a binary signal of L level or H level. The L level represents a state in which a document is not detected, and the H level represents a state in which a document is detected. In addition, the light receiving element P
The Db light reception signal is level-discriminated by the above-mentioned threshold value Th2 and converted into a binary signal of L level or H level. The L level represents a state in which an original or an OHP original is not detected, and the H level represents a state in which an original or an OHP original is detected. 4 light receiving elements PD ~ P
It is easy to understand that these document sizes are determined according to the combination of the levels of the output signals of Dd. Also,
For A4 size documents, the photodetectors PD and PDb
The output of A4 size OH is H level, while the output of A4 size OH
For P originals, only the output of the light receiving element PDb is at H level.

The presence of an OHP document can be reliably detected.

Such document discrimination processing and OHP document detection processing can be performed by a logic circuit or a CPU.

An A5 size original cannot be distinguished from the absence of an original by the output signal of the light receiving element FD-PD, but if there is no original, the lid of the copying machine cannot be closed, or if there is no original, copying cannot be performed. Since the button is not pressed, the A5 size can be determined in combination with the lid opening/closing detection signal or the copy execution button press signal.

By changing the positions of the beam spots P-Pd, it is possible to discriminate up to 16 different document sizes using four light beams. By increasing the number of beam spots, it becomes possible to discriminate more types of sizes. Of course, it is also possible to detect OHP originals.

The above-described off-axis MFL array 25 can be manufactured by various methods. for example.

A pattern of an off-axis MFL array is written on the electron beam resist using an electron beam writing method, and the electron beam resist is developed. Off-axis MFL array using the electron beam resist remaining film obtained in this way.
A standby is created from the pattern by electroforming, transfer, etc. Using this standber, it becomes possible to inexpensively reproduce a large number of off-axis MFL arrays by a resin molding method or the like.

FIG. 12 shows another example of a multi-beam light source. This multi-beam light source 21 is composed of a light emitting element array 31 and a projection lens 32 arranged above it. The light emitting element array 31 includes a plurality of (four in this embodiment) light emitting elements 31a to 31d. These light emitting elements are light emitting diodes or laser diodes. As the projection lens 32, a normal bulk convex lens is used. The projection lens 32 collimates the light emitted from each of the light emitting elements 31a to 31d to form spots p-pd on the surface of the glass plate 11, the original 12, or the OHP original 12A.

1 light emitting element 3 so that spots P - Pd are formed at positions where it is possible to determine the original size and detect OHP originals.
The arrangement of 1a to 31d, the light projection lens 32, etc. has been determined.

Since this embodiment uses a bulk convex lens as the light projecting lens 32, it has a feature that the efficiency of output light is higher than that of the above-mentioned off-axis MFL array. Also,
Since multiple light-emitting elements are provided, the brightness of the emitted beam is higher than when the output light from one light-emitting element is divided into multiple parts, and the level of the signal received by the light-receiving element is higher, allowing for stable detection. Operation can be ensured, and a high-output light source is not required. Furthermore, it is possible to integrally mold one light emitting element array and a light emitting lens.

This facilitates assembly.

FIG. 13 shows still another example of a multi-beam light source. The multi-beam light source 21 is composed of a light emitting element 24, a lens 35 for collimating the emitted light, and a grating 3B disposed above it. When the parallel light emitted from the lens 35 enters the grating 36, the grating emits ±1 in addition to the zero-order light.
Higher-order diffracted light such as second order, ±second order, etc. is generated. Therefore, the 0th order, ±
By using first-order and ±second-order diffracted light, the glass plate
Five spots can be formed on the top. In comparison with FIG. 10, -2nd order, -1st order, 0th order and +2nd order diffracted light become spots P, P, P, P. It is not necessary to use the +1st order diffracted light. If the period of the grating 36 is set appropriately, the grating 36
When the distance between the diffraction light spot and the glass plate 11 is set to 100 m1, it is easily possible to set the distance between each diffraction light spot to about 25 Am.

Such a multi-beam light source has a feature that its configuration is simple because its constituent elements are one light emitting element, a lens, and a grating.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing that a photosensor for determining document size is built into a copying machine. FIG. 2 is an enlarged perspective view, partially cut away, showing the configuration of a photosensor for determining document size. Figure 3 shows off-axis micro Fresnel lens.
FIG. 4 is a plan view showing the array; FIG. 4 is a diagram showing the projected light beam spot formed thereby; FIG. 5 is a diagram showing how an off-axis micro Fresnel lens is cut out from the micro Fresnel lens; FIG. FIG. 6 is a perspective view showing the function of an off-axis micro Fresnel lens. Figures 7 to 11 show the original size discrimination principle and OHP
Figure 7 shows the structure of the light emitting and receiving optical system, Figure 8 (A) shows the reflection from the glass surface, and Figure 8 (B) shows the glass surface and document surface. 8(C) is a diagram showing the state of reflection from the glass surface and OHP document surface, respectively. FIG. 9 is a graph showing the change in the amount of reflected light with respect to the reflection angle. is a diagram showing the relationship between the beam spot position and various document sizes. FIG. 11 shows the original size determination logic and OHP original detection logic based on the output signal of the light receiving element. FIG. 12 is a configuration diagram showing another example of a multi-beam light source. FIG. 13 is a configuration diagram showing still another example of a multi-beam light source. FIG. 14 and FIG. 15 are perspective views showing a conventional example. 10... Copy machine. 11...Glass plate. 12...Manuscript. 12A...OHP manuscript. 20...Full for document size determination 21...Multi-beam light source. Odo sensor. 22...Imaging lens. 23... Light receiving element array. 24, 31a to 31d - Light emitting elements. 25... Off-axis Φ Micro Fresnel ◆ Lens ◆ Array. 25a to 25d...Off axis φ micro Fresnel lens. 3I...Light emitting element array. 32... Light projection lens. PD - PDd... Light receiving element. p-pd... Projection light beam spot. Below

Claims (4)

[Claims] (1) A multi-beam light source that projects multiple light beams to different locations depending on the size of the paper to be discriminated, and for receiving the plurality of reflected light beams from the paper to be discriminated regarding the plurality of light beams. a plurality of light receiving elements, and an imaging optical system that guides the plurality of reflected light beams to the corresponding light receiving elements, such that at least one of the plurality of light receiving elements receives specularly reflected light from the paper to be discriminated. , wherein the position of each light-receiving element and the arrangement of the imaging optical system are determined so that the other light-receiving elements receive diffusely reflected light from the paper to be determined. (2) The multi-beam light source includes a light-emitting element and a grating that generates zero-order and higher-order diffracted light from the light emitted from the light-emitting element. Discrimination device. (3) The multi-beam light source is composed of a light emitting element and an off-axis Fresnel lens array including a plurality of off-axis Fresnel lenses that divide the light emitted from the light emitting element into a plurality of parts and deflect them in different directions. The device for determining the size of paper, etc., according to claim (1). (4) The size of the paper, etc. according to claim (1), wherein the multi-beam light source is composed of a plurality of light emitting elements and a projection lens that projects the emitted light of these light emitting elements in different directions. discrimination device.