JPH0334765A - Picture input device - Google Patents

Abstract

PURPOSE:To prevent a black fringing region from being generated in picture information read even when an original is placed obliquely by using an original cover having a high spectral reflectance in an optical wavelength region corresponding to a high sensitivity region of a photodetector so as to cover the original and using the light of the light wavelength region with a low spectral reflectance of the original cover so as to sense the original size. CONSTITUTION:An original D is covered by an original cover 19 having a high spectral reflectance in an optical wavelength region corresponding to a high sensitivity region of an image sensor 27 and the light from the original D covered by the original cover 19 is photoelectric-converted by the image sensor 27 to obtain picture information and a photocoupler 20 having a sensitivity to a light of a light wavelength region corresponding to a low spectral reflectance of the original cover 19 is used to detect the presence of the original D and the original size is detected by a detection signal. Thus, the image sensor 27 detects both the original D and the original cover 19 as white color and the production of black fringe region to the read picture information is prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an image input device used in, for example, a digital copying machine, an image processing workstation, etc. The present invention relates to an image input device.

(Prior Art) In general, an image input device (image scanner) provided in a digital copying machine, facsimile machine, and various other image processing devices uses optical information from a document obtained by exposing and scanning the surface of the document. A CCD array known as a solid-state image sensor or an image sensor, or a photoelectric conversion type image reading element made of an array of photosensitive materials such as silicon, converts it into an electrical signal, and the image information converted to the electrical signal is stored in a memory. It is designed to accumulate in

Then, if necessary, the image is read out by an image processing device, subjected to various image processing and editing, and output to an image forming device such as a digital copier to make it visible, or transmitted to a remote location by a facsimile device, etc. Furthermore, the image information may be stored as image information in a storage means such as an optical disk and read out as necessary for display or printing.

Image input devices used for such purposes often automatically detect the size of the input document and record the image on recording paper of a size that corresponds to the detected document size, making it necessary to detect the document size. The quality is high.

By the way, one method of detecting the document size currently in use is to pass a sheet-like document under a photoelectric sensor when feeding it, and detect the document size by taking a total of 491 times for the document to pass through. There is something.

In addition, for originals that cannot be fed, such as books, the original cover should be black or have a total reflection surface (mirror surface) to eliminate the reflection of illumination light from the original cover, and the original size detection sensor can scan the original. When this is done, a method is used in which the area where the original is placed, that is, the size of the original, is detected using the fact that there is reflected light from the original but no opposite light from the original cover.

However, when the document cover is black or has a total reflection surface (mirror surface) as described above, the background part of the document (document cover) is input to the image sensor as "black". If the input information is output as is, the image will have a black border around the edges of the document.

Therefore, recently, methods have been developed to prevent the occurrence of bordered images by using image processing technology to invert the "black" input information in the area outside the document and output it as "white" according to the detected document size. is being developed.

However, as shown in FIG.
The document table 52 is tilted with respect to the image sensor 51, which is configured by arranging a large number of document size detection sensors 50 in a row.
When placed on top, the document area must be defined by a rectangular area with the largest horizontal and vertical flame of the document tray, so that
The hatched area in the figure is left as a black border area. In order to detect such diagonal areas, a large number of document size detection sensors 50 are required, which increases the cost, and the process is complicated if image processing technology is used to reverse the black and white areas of the black border area. This results in a decrease in processing speed and is not practical. Therefore, such an apparatus has the disadvantage that careful attention must be paid to how the document tray is placed.

This problem is caused by the fact that the document cover, which should originally be "white," is made "black" for the purpose of detecting the document size.

(Problems to be Solved by the Invention) This invention has been made in view of the above circumstances, and its purpose is to solve the problem that black border areas occur in the read image information even when the original is placed diagonally. An object of the present invention is to provide an image input device that can easily detect the size of a document without having to do so.

[Structure J of the Invention (Means for Solving the Problem) The image input device of the present invention is an image input device that inputs image information by photoelectrically converting optical information from a document covered with a document cover with a light receiving element. , a document cover having a high spectral reflectance in a light wavelength region corresponding to a high sensitivity region of the light receiving element, and a document cover having a high spectral reflectance in a light wavelength region corresponding to a high sensitivity region of the light-receiving element; The present invention is characterized by comprising a document detecting means for detecting the size of the document, and a document size detecting means for detecting the document size by detecting with the document detecting means and distinguishing between the document and the document size based on the presence or absence of the document. do.

(Function) The present invention utilizes the property that the spectral reflectance of the white area of the document (L2) is approximately constant in the LS wavelength range, and utilizes the property that the spectral reflectance of the white area of the document (L2) is approximately constant in the LS wavelength range, and the light wavelength range (L2) corresponding to the high sensitivity area of the light receiving element is The original is covered with a document cover that has a high spectral reflectance, and the light from the document covered by the document cover is photoelectrically converted by a light receiving element to obtain image information, and the spectral reflectance of the document cover is The document size is detected using light in the low 0 light wavelength region of It is possible to prevent the occurrence of border areas, and the document detection means is not sensitive to light in the light wavelength range where the spectral reflectance of the document cover is low, but only to the light reflected from the document. The document size can be easily detected.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

First of all, there is no problem even if the light that is not sensitive to the image sensor out of the reflected light from the document cover disappears, so by making the spectral reflectance of the document cover as close to the spectral sensitivity of the image sensor as possible, The spectral characteristics of the elements used, that is, the document cover and the image sensor, are adjusted to prevent adverse effects on the input level of the image sensor due to reflectance changes.

For example, when a CCD is used as an image sensor, its spectral sensitivity is 0.55, as shown by dotted line A in FIG.
It has a sensitivity distribution close to the specific luminous efficiency with a peak near μm. For such an image sensor, for example, the light reflected from a document cover having a spectral reflectance as shown by the solid line B in the figure is substantially the same as the light reflected from the white background of the document ( This is the same contribution as the solid line C) in the figure. In addition, the unit of spectral sensitivity and spectral reflectance in the figure is the peak "1".
” is displayed as a relative value.

A document cover having such a spectral reflectance may be made of polyvinyl chloride, unsaturated polyester, polyurethane, silicone resin, etc., mixed with a dye such as chrome green or copper phthalocyanine green at 1 to 8 if EQ percent. A molded product is used. Note that since the reflectance varies depending on the amount added, it is adjusted according to the sensitivity of the image sensor described above. To adjust the spectral anti-1.1 characteristic in other wavelength ranges, for example, in the blue region, use cobalt blue, ultramarine blue, copper phthalocyanine blue, oil blue, etc., and in the red region, use cadmium red, mercury red, etc. By mixing Pyrazone Red or the like, it is possible to select a material that provides appropriate spectral reflection characteristics. By mixing two or more of these pigments to adjust the color, finer adjustment is also possible. Further, the measurement results of the spectral reflectance of the white background of a document commonly used are shown by the solid line C in FIG. As shown in the figure, the white background of a document generally exhibits high light reflection characteristics from the visible region to the infrared region.

Next, an image input device that uses an image sensor having the characteristics described above, a document cover, and a document detection element described below will be described.

FIG. 1 is a sectional view showing the general configuration of a digital copying machine, which mainly consists of an image input device section 1 that photoelectrically converts an image on a document sheet and reads it as image information, and an image input device section 1 that records and outputs the input image information. and an electrophotographic printer section 2.

A photoreceptor 4 is rotatably supported within the electrophotographic printer section 2 and is rotated in the direction of the arrow shown in the figure. Around the photoreceptor 4, along the direction of rotation, a charging device 5, a laser exposure device 6 for electrostatic image formation, and a developing device 7 are arranged.
, a transfer device 8, and a cleaning device 9 are arranged. Also, on one end side of the interior of the housing, recording paper 10a of different sizes is provided.
.

A paper feed device 14 is arranged, which consists of a cassette 11.12, each containing a paper 10b, and paper feed rollers 13a, 13b. The recording sheets 10a and 10b housed in these cassettes 11 and 12 are fed by paper feed rollers 13a and 13, respectively.
By the rotational force of b, the sheets are taken out one by one from the cassettes 11 and 12 and supplied to an image transfer section formed by the photoreceptor 4 and the transfer device 8, where images are formed.

The paper feed device 14 is connected to the transfer device 8 and the paper discharge tray 15 attached to the other end of the housing by a conveyance path 16. Also, transfer V<'M8 and paper output tray 1
A fixing heat roller 17 is provided between the recording paper 5 and the recording paper, and heats and fixes the image transferred onto the recording paper, and discharges the recording paper out of the housing.

Also, inside the housing is a control circuit 23 that controls the entire device.
(Details will be described later).

On the other hand, the image input device 1 provided at the top of the digital copying machine is configured as follows. That is, a document mounting table 3 is provided on the upper surface of the image input device section 1 . As shown in FIG. 2, the document table 3 includes a document table 18 made of transparent glass or the like on which a document is placed;
It is comprised of a document cover 19 that can be opened and closed. The document cover 19 is made of the material and has the reflective characteristics as described above. A document tray having the above-mentioned reflection characteristics is interposed between the document table 18 and the document cover 19.

A document scanning section 25 for exposing and scanning the document tray and a photocoupler 20 integrally configured with the document scanning section 25 are provided below the document tray 3 so as to be able to reciprocate along the document tray 3. ing.

The photocoupler 20, which serves as a document-sized detection element, includes a light-emitting element 20a and a light-receiving element 20b. The light emitting element 20a is, for example, GaP, which can emit infrared to green light.

Light emitting diodes such as GaAs and GaAsP are used. Alternatively, an incandescent lamp may be used as the light emitting element 20a, and an optical filter may be used to limit the desired wavelength. On the other hand, the light receiving element 20b includes CdS, Se,
It consists of an SPD (silicon photodiode), etc., and is arranged at an adjusted angle so that it can detect the intensity of reflected light from an object near the document surface.

In this example, in order to obtain the characteristics shown in FIG. 5, a GaAs light emitting diode, Toshiba TLN-102, was used as the light emitting element 20a, and a Toshiba TPS614 phototransistor was used as the light receiving element 20b. The wavelength sensitive range (wavelength range used) of this photocoupler 20 has a steep sensitivity distribution with a peak around 0.95 μm, as shown by the dotted line in FIG. Due to the reflective characteristics of the document cover 19, the light reflected from the document cover 19 is hardly sensitive to the light reflected from the document cover 19. on the other hand,
With respect to the solid line C indicating the reflection characteristics of the original document, this is a wavelength range in which sufficient reflection intensity can be obtained.

The document scanning unit 25 also includes a fluorescent lamp 26 that illuminates the document tray, and an image sensor 27 that uses a fluorescent lamp 26 to illuminate the document tray, and an image sensor 27 that scans the reflected light from the document tray.
It is composed of a lens (rod-shaped lens array) 28 that forms an image thereon. As the image sensor 27, a Toshiba CCD TCD105C having the characteristics shown in FIG. 5 was used.

As shown in FIG.
The document scanning unit 25 integrally configured with the document mounting table 3
It moves forward along the line and starts scanning. That is, the fluorescent lamp 26 of the document scanning section 25 is turned on, and the reflected light from the document illuminated by the fluorescent lamp 26 is reflected by the lens 28.
The light is focused and imaged on the image sensor 27.

The image information photoelectrically converted by the image sensor 27 and extracted as electrical information is stored in a memory (not shown). After the image information stored in this memory has been subjected to necessary image processing such as editing, it is output as a recording signal to the laser exposure device 6, and the image information is outputted as a recording signal to the laser exposure device 6, and the image information is outputted as a recording signal to the above-mentioned laser exposure device 6. An electrostatic latent image is formed on the photoreceptor 4. The electrostatic latent image formed on the photoreceptor 4 is developed by a developing device 7 to form a powder image, which is rotated to a position of a transfer device 8 .

On the other hand, as shown in FIG. 4, the sensor output from the photocoupler 20 as the document detection circuit 24 is caused by the reflected light from the white background of the document tray between g and m, which is the area where the document tray exists. A sensor output that reaches near the dotted line H in the middle is obtained, and within this range, the output fluctuates in various ways as shown in the figure, depending on the characters and images written on the original. However, outside the original document area, there is almost no reflected light from the original cover 19, and the sensor output remains constant at a low value. This state remains the same even if the document cover 19 remains open.

In this way, the document area can be optically recognized from the difference in output between the document area and the outside area. Therefore, the length of the original document can be detected by measuring the output duration of the photocoupler 20 using, for example, a pulse counter.

That is, the two document size detection circuits detect the length of the document by counting the high level time of the sensor output using a pulse counter (not shown) provided therein.

On the other hand, the size in the width direction is detected, for example, by arranging a plurality of similar photocouplers in a direction perpendicular to the scanning direction and detecting the presence or absence of output. Note that the paper size may be configured to be detected from the output distribution of each sensor without having a large number of sensors fixedly arranged and scanned.

In this way, the size of the document detected by the two document size detection circuits is output to the comparison and verification circuit 31. In the comparison/verification circuit 31, the recording paper size detection circuit 30 detects the signal output from the cassette 1.1.12 in the paper feeder 14 set in advance, and the detected recording paper size signal and the above-mentioned original size detection circuit are used. A comparison is made with the original size signal detected by the two. Next, this comparison and verification circuit 3
1, a recording paper size selection signal is sent to the paper feeder drive circuit 32 via the switch 35.

On the other hand, the copy process control circuit 23 sends a signal to the paper feed timing control circuit 33, and the paper feed device drive circuit 32
operates the paper feed roller 13a or 13b to feed out the recording paper 10a or 10b of the size according to the selection signal.

The recording paper 10a or 10b selected in this way is conveyed through the conveyance path 16 and reaches an image transfer section, where the powder image formed on the photoreceptor 4 is transferred by the action of the transfer device 8. be done. Then, the recording paper 10a or 10b to which the powder image has been transferred is further transported along the transport path 16, fixed by a fixing heat roller 17, and placed on a paper discharge tray 15.
It is discharged to the top. On the other hand, the photoreceptor 4 on which the transfer of the powder image has been completed
is cleaned by the cleaning device 9 and returned to the initial state, and further,
It is charged by the charging device 5 and prepared for the next image recording.

Note that when recording on recording paper of a desired size regardless of the original size, by switching the switch 34 to the manual size selection circuit 34 side, the recording paper of the specified size is selected from the manual size selection circuit 34. It is now selected.

As described above, by utilizing the property that the spectral reflectance of the white area of the original document is approximately constant over a wide wavelength range, the original document has a high spectral reflectance in the light wavelength range corresponding to the high sensitivity area of the image sensor 27. A cover 19 covers the document tray, and the image sensor 27 photoelectrically converts the light from the document tray covered by the document cover 19 to obtain image information. Since the photocoupler 2o, which is sensitive to light, is used to detect the presence or absence of a document cover, and the document size is detected based on this detection signal, the image sensor 27 detects both the document cover and the document cover 19. The photocoupler 20 detects the image as white and can prevent the occurrence of a black border area in the read image information, and the photocoupler 20 is not sensitive to light in the light wavelength range where the spectral reflectance of the document cover 19 is low, and the photocoupler 20 detects the image information as white. Since it is sensitive only to reflected light, the original paper and original cover 19
The size of the document can be easily detected. With this configuration, the size of the original can be detected at the same time as the original is read, so that the corresponding recording paper can be automatically selected based on the original size information generated from the image input device.

In addition, since the sensor output from the document cover 19 area is configured to be low level (that is, there is no opposition) for detection, it is possible that the document cover may be lifted up by a thick book or the like, or if it is left open. Since the document area can be recognized without any problem when used, it can operate accurately in all conditions. Furthermore, unlike in conventional methods, the background (cover) of the document is no longer captured by the scanner as black information, so the phenomenon in which the background of the document appears black in the image output from this image input device is avoided. It can be prevented.

In the above embodiment, a COD was used as the image sensor, but the image sensor is not limited to this, and other amorphous silicon sensors may be used.In short, the document cover 19 should be adjusted according to the spectral sensitivity of the sensor. If you set the spectral reflectance of and the wavelength used by the photodetector as described above,
A similar effect can be obtained.

[Effects of the Invention] As described above, the present invention provides an image input device that does not generate black border areas in the read image information even when the original is placed diagonally, and can easily detect the size of the original. can be provided.

[Brief explanation of drawings]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a sectional view showing a schematic configuration of a digital copying machine to which an image input device of the present invention is applied, and FIG. 2 is a document copying machine. FIG. 3 is a cross-sectional view showing the schematic configuration of the mounting table, FIG. 3 is a diagram for explaining the operation, FIG. 4 is an output waveform diagram of the photocoupler, and FIG.
The figure is an explanatory diagram for explaining spectral sensitivity and spectral reflectance, and FIG. 6 is a diagram for explaining a conventional image input device. 1... Image input device, 2... Image forming device, 3...
・Document placement table, 18...Document table, 19...Document cover 20...Photo sensor (document detection means), 25...
・Document scanning unit, 26...Fluorescent lamp, 27...Image sensor (light receiving element) 8...Lens, 9...Document size detection circuit (document size detection means)

Claims (1)

[Scope of Claims] An image input device that inputs image information by photoelectrically converting optical information from a document covered by a document cover with a light receiving element, comprising: a light wavelength range corresponding to a high sensitivity region of the light receiving element; A document cover that has a high spectral reflectance, a document detection means that detects the presence or absence of a document by sensing the light in a light wavelength range where the spectral reflectance of the document cover is low, and the presence or absence of a document detected by the document detection means. An image input device comprising: a document size detection means for detecting the document size by identifying the document and the document cover.