JPS61232440A - Original discriminating device - Google Patents

Abstract

PURPOSE:To discriminate the size of an original securely by providing a photodetecting means which has a wavelength area where there is the peak of spectral sensitivity in the area of a pressure plate where a spectral reflection factor is low and a means which discriminates the size of the original and whether the original is present or not from the output of the photodetecting means. CONSTITUTION:The original 20 to be copied is placed on original platen glass 1 and the pressure plate 9 is mounted thereupon. Then a microswitch 13 is turned on and a copy start switch 15 is further turned on to start original size detecting operation. An original illuminating lamp 5 illuminates the original 20 while positioned in a no-image area to detect whether the original is present in an area (P' and P1-P5) or not. When the original 20 is placed, a high output value is obtained and when the pressure plate 9 is mounted, the peak of the spectral sensitivity of the photodetecting means is present in an area where its spectral reflection factor, so a low output value is obtained. This output value is converted into a binary value by a comparator C on the basis of a predetermined threshold value to detect which fixed form paper size the original corresponds to.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a document identification device for identifying the size and presence or absence of a document placed on a document table.

(Prior Art) As a conventional example, an electrophotographic apparatus having the above-mentioned document identification device will be explained. By identifying the size of the document, a multi-functional copying machine is realized as shown below. ing. In other words, the size of copy paper is automatically selected according to the size of the original to be copied, and the appropriate copy paper or copy paper is selected according to the magnification and the size of the original specified by the operator. By automatically selecting the loaded cassette and copying, the operator's effort during copying is reduced. In addition, when the operator specifies the size of the copy paper, some models automatically change the copy magnification depending on the size of the original to be copied, and copy the image information onto the copy paper at the appropriate magnification. This reduces labor and prevents copy errors caused by incorrect settings of magnification.

Such a document identification device uses, for example, a color sensor that uses a special color for the crimped surface of the document pressure plate that presses the document, and that outputs different colors based on the color difference between the color of the pressure bonded surface of the document pressure plate and the background color of the document. (Japanese Unexamined Patent Publication No. 56-114955) discloses a method of detecting the presence and size of a document by illuminating the document surface with the document pressure plate open to eliminate reflected light from parts other than the document. A method for detecting the size of a document by detecting the reflected light of
) has been proposed.

(Problem to be solved by the invention) However, in the case of such a conventional example, first of all,
The method proposed in No. 4955 has a problem in that an expensive color sensor is required to detect the reflected light from the original pressing surface of the original pressing plate. In addition, because the original crimping surface is colored, for example, if the original placed on the document table is placed out of position, a border, which is an image of the original crimping surface, will appear on the copied copy paper. There were also problems.

Furthermore, in the method proposed in JP-A-58-95367, the reflected light is detected with the document presser plate open, so there is a risk that the light detection means will malfunction due to outside light. There was a problem in that it caused Furthermore, the document pressure plate is generally a white diffuser plate in order to increase the reflection of the document during copying and to prevent black frames from appearing in the copied image. It is difficult to identify them using differences in intensity or the like. For this reason, a method is used to detect the document size just before the pressure plate is stacked on the document. However, if the document is in the form of a sheet, the document may move on the document table due to wind pressure when the pressure plate is stacked on top of the document. However, if the surface of the pressure plate is colored black or the pressure plate is made of a specular reflector, it will be easier to distinguish between the original and the pressure plate, but the black frame mentioned above There was also a problem that the image was easily recorded on the copied image.

The present invention has been made to solve these problems in the prior art, and it is an object of the present invention to provide a document identification device with a simple configuration that can reliably identify the document size.

(Means for Solving the Problems) Therefore, in order to achieve the above object, the document identification device according to the present invention has a spectral reflectance in a wavelength region shorter than the spectral reflectance in a wavelength region showing the peak of spectral sensitivity of an electrophotographic device. A document holding pressure plate with a low spectral reflectance, a light detection means whose wavelength range showing the peak of spectral sensitivity exists in a region of the pressure plate with a low spectral reflectance, and an output of the light detection means to determine the size of the document. It consists of a discriminating means for discriminating the presence or absence.

(Example) The present invention will be explained below based on the illustrated example. 1st
6 to 6 show the vicinity of the document table of an electrophotographic apparatus according to a first embodiment of the present invention.

Although not shown as an electrophotographic device, it is applied to an electrophotographic copying machine having a normal electrophotographic process, and automatically selects copy paper and a cassette according to the original and copy magnification, and selects the copy magnification according to the copy paper. It has the following functions.

In FIG. 1, reference numeral 1 denotes a document table made of transparent glass, which is attached to the upper opening of the housing 2. As shown in FIG. Inside the casing 2 on the lower surface side of the document table 1, a light source 5.8 for illuminating the surface of the document, and light detection means 3, 3, . It is set up.

In this embodiment, the storage position of the original is based on one side as shown in FIG. (in the Y direction in the figure), within A5 size (Pl) A5 size and B
Between 5 sizes (P2, B5 and A4 sizes)
P3), B4 between A5 size and B4 size (P4)
The width of the document is checked by detecting five locations between the size and A3 size (Pω).
is a scanning optical system consisting of a light source 5 for illuminating an original, a reflecting shade 6, and the like.

A notch 6a is provided in the reflective shade 6 as a light transmitting portion extending in a direction perpendicular to the scanning direction, and the light source 5 for document illumination is turned on at the stop position of the scanning optical system 4 before scanning, and the above-mentioned detection is performed through the notch 6a. Area P,, P2,..., P5
It is designed to irradiate. On the other hand, as shown in FIG. 2, the detection area Pt+P2. . . , photodetecting means 3. at positions corresponding to P5. ...is arranged. This light detection means 3 is composed of a lens 3a and a light receiving element 3b such as a solar cell or CaS.
a respectively corresponding detection areas P1. P2. ....

The reflected light from P5 is imaged onto the light receiving element 3b. Note that 7a, 7b, and 7C in FIG. 2 are mirrors constituting an optical system for projecting an original image onto an electrophotographic photoreceptor.

Next, identification in the length direction of the document (X direction in the figure) will be explained. As shown in Figure 4, in the length direction, A
The detection area is P'1 between the 5 size (vertical) and the B5 size (vertical).

As shown in Table 1, P'1 allows the distinction between B5 and B4 when the manuscript is placed vertically, the distinction between A4 and A3, the distinction between vertical and horizontal placement of B5, and the distinction between portrait and horizontal placement of A4. is attached, and the size and orientation of the standard paper document are specified.

The output of each light receiving element is applied to a comparator C to which a reference voltage from a reference signal source S is applied. In the comparator C, reflected light from the original is incident on the light receiving element.

When it is, it outputs a level L signal, and when it is not, it does not output.The output of each comparator is controlled by a microcomputer cp.
The CPU determines the size of the document according to the truth table shown in Table 1.

Table 1 Any combination other than the above will result in an error.

1: Large output of the light receiving element 3b (reflected light from the original) 0: Output wheel of the light receiving element 3b (reflected light from sources other than the original such as a pressure plate) In Fig. 3, 8 is a light source for detecting the original size; The detection area P'1 is irradiated with the light, and the reflected light is imaged onto the light receiving element 3b by the lens 3a.

In the housing 2, a document presser plate 9 has a support shaft (
(not shown), and on the top surface of the housing 2, there is a microswitch as an actuating means for actuating the light source 5.8 and the light detecting means 3, 3... 13 is provided, and this microswitch 13 is turned on and off by the pressure plate 9.

In the figure, 15 is a copy start switch.

Next, the operation of this embodiment will be explained.

In the above configuration, when the original 20 to be copied is placed on the original table glass 1 and the pressure plate 9 is placed on top of it, the microswitch 13 is turned on, and by further turning on the copy start switch 15 or the pressure plate 9 is Either by overlapping or by turning on the copy start switch 15,
The original size detection operation starts. That is, the original illumination lamp 5 and the original size detection lamp 8 are turned on,
The light detection means 3.3... move to the right to detect the document size. It is assumed that the document illumination lamp 5, including the scanning optical system 4, is located in the non-image area as clearly shown in FIG. Illumination light is emitted from the lamp 57, and the document illumination lamp 5 can illuminate the document 20 while being located in a non-image area. That is, the lamp 5.8 can illuminate the area (P1 to P5 and P'1) in FIG.
The presence or absence of the document 20 on the document table l in this area is detected by the light receiving elements 3b, 3b, . . . via the lenses 3a, 3a, .
As shown in FIG. 5, this detection operation is performed by lowering the spectral reflectance of the pressure plate surface in the region where the peak of the spectral sensitivity of the light receiving element exists, that is, by lowering the spectral reflectance of the pressure plate surface 9a. The spectral reflectance of the light receiving elements 3b, 3b...
This is done based on the wavelength range difference between the spectral sensitivity and the spectral sensitivity of . For this purpose, the document pressure plate is colored to have the spectral reflectance shown in FIG. The document illumination lamp 5 and the document size detection lamp 8 are halogen lamps or incandescent bulbs, and are assumed to cover the entire wavelength range shown in FIG.

Further, the reflectance of the blank paper original 20, which is a white diffusing surface, is different from the reflectance of the pressure plate surface 9a, and a significant reflectance is generally obtained even in the wavelength range of 400 to 500 nm. Therefore, by the above-described operation, it is possible to detect the presence or absence of a document in the areas (P'1 and P1 to P6) shown in FIG. That is, the output of each light detection means 3.3... shows a high output value when the original 20 is placed in the corresponding area (P'1 and P1 to Ps), and when the pressure plate 9 is placed, If the spectral reflectance is low, the peak of the spectral sensitivity of the photodetecting means exists in the area where the spectral reflectance is low, resulting in a low output value. By converting this output value into a binary value using a comparator C using a predetermined threshold value, it is possible to detect which size the document is converted to when converted to standard paper. If it is the area (P'1 and P1 to P5) in Figure 4, then the placed manuscript 2
It is possible to determine which of the standard sheets of paper the 0 area corresponds to.

After recognizing the standard size paper that satisfies the size of the original 20 in this way, the image forming optical The imaging magnification of the system (not shown) and the paper to be actually copied are selected, and then the electrophotographic process is performed. FIG. 6 shows a flow chart of the entire process described above. Here, the peak of the spectral sensitivity of the electrophotographic device can be expressed as the product of the spectral reflectance of the mirrors and lenses of the optical system that projects the original image onto the electrophotographic photoreceptor, the spectral transmittance of the mirror, and the spectral sensitivity of the electrophotographic photoreceptor. The spectral reflectance of the document pressure plate is high in the wavelength range where 1J is present.

The spectral reflectance of the original pressure plate can be expressed as the product of this spectral reflectance and the spectral sensitivity of the electrophotographic device.
If the overall sensitivity for general white paper is set to preferably 60% or more (in terms of integral value), the pressure plate 9 will remain almost white in the electrophotographic device, and when copying a sheet-like original, the original The surrounding area is treated as white.

On the other hand, the overall sensitivity, which can be expressed as the product of the spectral sensitivity of the light detection means and the spectral reflectance of the document pressure plate, can be expressed as the product of the spectral sensitivity of the light detection means and the spectral reflectance of ordinary white paper. The sensitivity is less than 50% of the total sensitivity (in terms of integral value), and therefore, the pressure plate 9 has a "black" color to the light detection means 3.

In the above embodiment, six photodetecting means 3 were used, but A
If you exclude the case where the long side of the 5th edition paper is placed in the X-axis direction and the determination of the document reference corner position, the number of light detection means is 4, and the truth table in that case is as shown in Table 2 below. It is.

Table 2 (All combinations other than the above will result in an error.) Also, Table 7
The figure shows an embodiment in which the light detection means is a photodiode array sensor such as a CCD. In this embodiment, the area in the Y-axis direction of the document table 1 is covered by the imaging lens 101.
The optical axis of the imaging lens 101 and the light detection means 102 is as follows.
It is assumed that the lens optical axis of the imaging lens 103 of the electrophotographic apparatus exists in the same plane within the XY plane. When a copying operation start switch is turned on in such an apparatus, the document size is detected and an electrophotographic process is performed according to the flow shown in FIG. That is, since the spectral sensitivity of the light detection means 102 made of COD or the like is generally determined according to the relative luminous efficiency, a blue filter 104 is provided on the optical axis leading to the light detection means 102 to increase the spectral sensitivity of the light detection means 102. The spectral sensitivity is made to be equivalent to the spectral sensitivity of the photodetecting means 3 shown in FIG. In such a case, the pressure plate surface 9a has the same transfer density as white for the electrophotographic apparatus, but it becomes black for the photodetector 102, as in the first embodiment. The size of the original 20 on the table 1 is determined by the light detection means 1.
By detecting the strength of each bit of 02 using a well-known method, it is possible to detect the presence or absence of the document 20 at the corresponding position, and as a result, the size of the document 20 can be known. Therefore, in the case of this embodiment, unlike the first embodiment,
It is possible to identify atypical document sizes.

(Effects of the Invention) The present invention has the above-described configuration and operation, and it is possible to reliably identify the size of a document by using the wavelength range difference between the spectral reflectance of the pressure plate and the spectral sensitivity of the light detection means. As well as being able to
Since the detection operation is performed with the pressure plate in close contact with the document, the size of the document can be accurately identified without being affected by external light.

Furthermore, since the color of the pressure plate in the electrophotographic apparatus is white, it is possible to prevent the edges of the document from being bordered in black on the transfer sheet.

[Brief explanation of drawings]

The drawing shows a document identification device according to the present invention.
Figures 6 through 6 show the first embodiment. FIG. 1 is a partially cutaway schematic perspective view of the vicinity of the document table, FIG. 2 is a schematic side view of the scanning optical system including the light detection means and document illumination lamp of the apparatus shown in FIG. 1, and FIG. FIG. 4 is a plan view showing the detection area of the document table of the apparatus shown in FIG. 1 by the light detection means, and FIG. A graph showing the spectral characteristics of each member of the apparatus, FIG. 6 is a flowchart showing the electrophotographic process of an electrophotographic apparatus incorporating the document identification device according to the present invention, and FIGS. 7 and 8 show the document identification device according to the present invention. A second embodiment of the apparatus is shown, FIG. 7 is a schematic side sectional view of an electrophotographic apparatus incorporating the document identification device, and FIG. 8 is a flowchart showing the electrophotographic process of the apparatus of FIG. Explanation of symbols 3...Light detecting means 5...Lamp for document illumination as a light source 6...Reflector shade 6a...Notch 8 as a light transmitting portion...Lamp for detecting document size as a light source 9...
pressure plate

Claims (3)

[Claims] (1) A document holding pressure plate whose spectral reflectance in a short wavelength region is lower than the spectral reflectance in a wavelength region showing the peak of spectral sensitivity of the electrophotographic device, and a spectral reflection of the pressure plate whose wavelength range shows the peak of spectral sensitivity. A document identification device comprising a light detection means existing in a region with a lower rate, and a determination means for determining the size and presence of a document based on the output of the light detection means. (2) The document identification device according to claim 1, characterized in that a light transmitting portion is provided in the reflective shade for illuminating the document as an illumination light source for detecting the size of the document and the presence or absence of the document. (3) The document identification device according to claim 1, wherein a photodiode array sensor is used as the light detection means.