JPS61155904A - Apparatus for detecting manuscript - Google Patents

Abstract

PURPOSE:To detect the accurate length of a manuscript, by setting an adjacent region length to a quantitative length when it is judged that a manuscript is present over all of adjacent regions within a plurality of regions and further correcting the detected quantity of light of a noticeable region by quantity of light detected in adjacent regions. CONSTITUTION:A manuscript M is placed on the side C of a manuscript reference position. The size of the manuscript has lengths dx, dy with respect to directions (x), (y) and the position thereof is set so as to be separated by (r) from the manuscript reference position in the direction (x). Detection operation is performed by outputs Ns, Ms, Rs of light detectors to a standard white plate plate when a scanning position is set to S, outputs Np, Mp, Rp to the manuscript when a scanning position is set to P and outputs Ne, Me, Re to a pressure contact plate when a scanning position is set to E and the detection of the length of the manuscript is performed by a controller including a signal processor. Each data at the position E is used as dark data and data subtracted from data at the positions P, S are used as the correction data of a standard value when it is assumed that the manuscript was placed over the entire length in the direction (y).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the position and size of a document in an electrophotographic device or the like.

As part of the multi-functionalization of electrophotographic equipment, Factor i IJ rack equipment, and office equipment that handles paper industry manuscripts,
It is equipped with a variable magnification optical system. An advantage of using a variable magnification optical system in an electrophotographic device is that, for example, when specifying the size of a filter paper to be copied, the imaging magnification can be reduced, 6 or enlarged according to the size of the original. The original image can be accurately copied onto the sheet of paper to be copied. To perform this task accurately, a device is required within the electrophotographic apparatus to recognize the size and, in some cases, the position of the document. In addition, an electrophotographic device that is equipped with a device that recognizes the size or position of the original is able to recognize the size and position of the original, and then select the appropriate sheet of paper to be copied. Conventionally, this type of device has been constructed as shown in Figure 1. That is, it is assumed that the original 1, the pressure bonding plate 3, and the original platen glass 2 are taken as one unit, and images are taken in the X direction relative to the other members. There are two cases in which A is moved mechanically, and there are cases where the reflecting mirror system up to the imaging lens 4 is mechanically moved, which is a so-called document table fixing method. The other components are the document illumination optical system 1
0, an imaging optical system 4, a photoreceptor 5 such as a photosensitive drum, a member 7 forming an electrophotographic process such as a developing machine, a next optical system 8 that recognizes the position and size of the document, a linear photodiode array 9, and The driver llt is shown. In this case, the method for recognizing the size and position of the original is to make the surface of the pressure bonding plate 30 a mirror surface, etc., and the pressure bonding plate is irradiated from a light source 1O, and the subsequent light is sent to the optical system 4 and the optical system for reading the position and size of the document. 8, and these optical systems function in such a way that only the diffused light beam from the surface of the document is incident on these optical systems. In other words, as A moves, the document position/size recognition device
It is possible to recognize the area where the document exists as shown in the figure. In the figure,
The shaded area indicates the area A where no original document exists.

That is, the photodiode array 9 can detect the light amount distribution along the length of A in the y direction.

Figure 3 shows this state.If the output P of the photodiode array 7 is at the threshold 1sKt-Koshiku9, the threshold value of the photodiode array 9 is exceeded and the area A corresponding to address 9 is JjK. It is possible to recognize that a manuscript exists. In the example of FIG. 3, it is shown that a document exists in the section from address 6 to address n-1. By sequentially performing this method iA as it moves in the X direction, the area of the document in A can be detected.

Although it is possible to detect w, the size of the document, and the position using the conventional method described above, it has the disadvantage that it is necessary to create an imaging light beam that reaches 9 in addition to the imaging light beam that reaches 4 from the original document. There is. Another drawback is that the signal processing must be performed equally for all addresses in the photodiode array 9, making the method complex.

In other words, the existence of the document is recognized and scanned at each address in the y direction.
However, it is also necessary to deal with movement in the X direction, which requires high-speed signal processing. Spatial resolution is determined by the total number of addresses in the photodiode array,
In order to achieve high resolution, a 7-otodiode array having many addresses is required, and the use of such a method has the drawback that the signal processing speed described above must be further increased. Furthermore, if the light source 10 is used as a flashlight, such as a fluorescent lamp, the intensity of the illumination light varies over time, resulting in poor detection accuracy.

The present invention eliminates the drawbacks of the above-mentioned conventional examples and enables means for recognizing the size or position of a document with high precision using a high-speed and simple signal processing method.

That is, it detects the amount of light in multiple fixed areas on the document table,
The document length and position are determined based on the light intensity in the plurality of areas.

More specifically, when it is determined that the document exists in all adjacent areas among multiple areas, the length of the adjacent area is set to a certain fixed amount, and the amount of friendly light detected in the adjacent area and the fixed amount are determined. The detected light amount of the area of interest is corrected using the length, thereby detecting the document length and position more accurately. Multiple pieces are arranged perpendicular to the paper surface in a container. t7t, t
z is a slit play corresponding to the photodetector 13, and 20 is a standard white board. FIG. 5 shows the relationship between the photodetector 12, the slit array 13, and A as seen from the direction W in FIG. 4, and will be explained next in an example in which there are three photodetectors.

That is, three photodetectors detect the light intensity on A,
The detection range is limited by the slit array 129, and the light in the area of AOM in the figure passes through the slit 12M.
The 3M photodetector detects light in the N area (Surin) 12Nt-
Through the 13N photodetector, the light in the R area is Surin)
Each of the photodetectors 13H detects the light intensity through 12R. It is assumed that the lengths of M and N in the y direction on A are tM and tN.

Further, R is a position where the original is always placed, and FIG. 5 shows an embodiment in which the original is placed along the 0 side of A. In addition, although the figure shows an example in which three slits are arranged on a 12-slit array, the range on A is shown in Figure 5 R, M, N as a slit and photodetector t-1 pair. Assuming that the brightness distribution on 0 and A is constant, the unit length in the y direction in each region of R, M, and H is It is assumed that the slit has a shape such that the amount of light enters the photodetector corresponding to each region with uniform intensity.

t 7'1m, 20 is a standard white board, which is a white board with uniform density that performs almost perfect diffusion.

A means for detecting the size and position of a document using the apparatus VC arranged as described above will be explained.

FIG. 6 shows a state in which an original ml is placed on the document table 2. As shown in FIG. In other words, the original 1 is placed pressed against the side C of the original reference position ()/touching part). The size of the manuscript is xy
dx for the direction.

It is assumed that the document has a length of ay and is located at a distance r from the document reference position in the X direction. Furthermore, this embodiment is an electrophotographic device, and the size of the document,
It is assumed that the position is detected by Ast-scanning before the actual electrophotographic process is performed.

The detection operation is performed using the scanning position t-S and the output N59M5. of each photodetector relative to the standard white board. R8, each output NP, MP, RP for a document whose scanning position is, for example, P, and outputs NE, ME, R, for a position where the scanning position is, for example, only the crimp plate of E, or nothing. , a controller 21 including a signal processing device such as a microco/viator detects the document length. The signal processing of No. 21 will be explained below.

Each data at position E is used as dark data to be subtracted from each data P and S, and each data at position S assumes that the original is placed at the entire length in the y direction. used as standard value correction data. That is, each detection data is Rs = N as shown in Fig. 6.
s 9M5-RP,NPlMP,RE,N,f! J.
ME, and subtract the data at position E from the data at positions S and P. Each result is defined as follows.

Nc; -Ns -NE MB2-M8-M.

RB’-BB-RE Nd-NP-N.

MP' -MP-ME RN -Rp -RE Here, it is assumed that the R data is reference data for each original density, and original density correction is performed on the N and M data. The result is defined as follows.

Ni-Nd/Rs MB2- M8’/Rg Nme Nze/aj Mi-M,,’/R,’ Here, Mi corresponds to tyi, and Ns' corresponds to tNK.

That is, referring to the data of Ns' and M8' from Np and Mi, the document lengths LM and LN corresponding to 13M and 13NK in P can be considered as follows.

LM -4×Mi / ``s LN -4X Ni / Ns Here, the length of the document in the y direction at the location P is LM''N
Although it is possible to do as follows, in order to further improve the accuracy. That is, it is determined whether LN is a significant value and LM is a value sufficiently close to -. If the above result is true, then use tyLt-sot as an expression.

See you again LP! With i as the correction value, do the following O Ld-tMXLN/LM That is, the document length d7 in the y direction at P is ay-4+L
, / can be done.

If the above result is negative, dy is set to d3'-'M. As described above, it is possible to detect the length of the document in the y direction at P, but in many cases, characters, photographs, etc. are printed or written on a general document. In other words, if the document density has a large distribution, errors often occur in the detected document length. Therefore, the position P in the X direction at which the document length is detected is the entire length of di, and a plurality of positions are detected during scanning of a portion of the length of di, and a selection is made from among them. That is, the presence or absence of a document in the X direction is detected by the change in the output of the photodetector 13H during scanning, and the scanning system performs RP within the document presence area.

MPTo or RP, MP, NP are close to the maximum value,
The above-mentioned document length detection calculation is performed using data at a location where the scanning position does not fluctuate widely. In other words, data on locations that appear white continuously in the document X direction is used. Alternatively, the average values of Rp, Mp, and Np at a plurality of locations are determined, and this is used to calculate the document length detection.

FIG. 7 shows the above signal processing as a flow chart. In this embodiment, the variable magnification optical system is controlled based on the nine document sizes dx and dy K obtained as described above.
Alternatively, select copy paper.

Figure 8 shows the area R observed by each of the photodetectors 13R and 13M.
, M do not overlap, and 7 is the expected area length tln of R in the embodiment. As a signal processing method, from BLNC in Figure 7' (taking into consideration the expected area length of 5R,
Carry out as shown in the diagram. That is, by considering the region R as an independent length, it is possible to further improve the accuracy of measuring the document length.

Further, Figure i@10 shows the Yumi tail side using four photodetectors 13t, and it is possible to detect the document length with a much higher resolution. In this case, the signal processing method can be as shown in Fig. 11 in the same way as in Fig. 9◇ Also, in Fig. 12, scanning is not performed over the entire area in the X direction,
The scanning range for detecting the y direction of the original is limited to Dx, and for the X direction of the original, one or more fixed positions in the A pair of so-called photo interrupters 4o (
1: )~aO(n)' is installed, and the position and size are determined depending on which photointerrupter changes. Here, 30 is a standard dark plate for obtaining dark data. It is assumed that the original 1 is placed along the original placement reference position tit Cx -Cy on the original table. The length of the document in the y direction ay ti can be detected by the same detection operation as described above. Also, the length dy of the document in the X direction is determined when the photo interrupter 40 is turned on.
With OFF, it is possible to determine from the installation location. By independently detecting the length of the document in the X and Y directions as in this embodiment, it is possible to set the distance Dx shorter than the scanning area document length for detecting the document size, and the detection speed is It has the advantage that it can be used as a speed control.

As explained above, in order to detect the size of the document and its position on the document table, the strength and weakness of the reflected light of the document are detected in a limited area, and from the detection results, it is possible to detect the size of the document and its position on the document table. If it can be determined that the JJX M is applied to the entire area, the length of the adjacent area must be constant, and by using means for correcting the detected light tt of the area of interest based on the amount of light incident on the adjacent area. , the detection accuracy is low and the document position and size can be detected easily.

[Brief explanation of drawings]

Figures 1 and 4 are functional diagrams mainly consisting of the optical system of the electrophotographic device, and Figure 2 is the original 4111! Fig. 3 is an illustration of the document detection level, the fifth factor, Fig. 6 is a layout diagram of the optical system for detecting the document size, a stand, 12 is a slit array,
Reference numeral 13 indicates a light quantity detector, reference numeral 13 indicates a standard white board, and 21 indicates a signal processing device such as a CPU.

Claims (1)

[Claims] A device that determines the size or position of a document placed on a document table, which detects the amount of light in multiple fixed areas on the document table, and determines the size or position of the document based on the light intensity in the multiple areas. A document detection device characterized by: