JP3168666B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the size of an original in an image reading apparatus provided in an image forming apparatus such as an electronic copying machine or a printer, and more particularly, to an apparatus for detecting the size of an original set on a platen. The present invention relates to an image reading apparatus capable of performing detection using an image sensor and a longitudinal direction detection sensor.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, an original is placed on a platen, the original is scanned by an optical device, and scanning light of the image is transmitted to an image carrier through a mirror or a lens. For writing an image. In an image reading apparatus such as the electronic copying machine, in addition to a method of directly transmitting light obtained by scanning a document to an image carrier, a means for outputting scanning light of the document as a digital signal using a CCD image sensor or the like is provided. Sometimes used. As the image forming apparatus using the digital signal, a general laser printer, and those that are also applied to an image reading device connected to a computer, in addition to the case where information obtained by scanning a document is directly output as a copy, It is also used as a means for storing information of a document.

As described above, even when a digital image reading apparatus is used, it is necessary for an electronic copying machine or the like to accurately detect the size of a document and to select a sheet according to the size of the document. Therefore, in order to select a sheet of an appropriate size in accordance with the size of the document and information such as the selected scaling ratio, for example, Japanese Patent Application Laid-Open No. 61-20936
Document size detecting means as shown in Japanese Unexamined Patent Publication (Kokai) No. H10-26095 is used. In the conventional example, as shown in FIG.
A plurality of sensors A to F are arranged on the platen 2 so that the plurality of sensors can detect the size of a document set on the platen.

In the conventional example, a plurality of sensors are arranged in the width direction of the platen with respect to the document whose leading end is positioned on the leading end registration line Y set on the platen 2, and the movement of the scanning device is performed. Two sensors E and F for the direction
Are arranged at predetermined intervals. Then, detection information from these sensors is input to the control device to detect the document size. Therefore, in the above-described conventional example, the document size and the length can be easily detected by obtaining information on the width and length of the document with a center register type device that positions the document at the center of the platen. .

[0005]

However, as shown in the above-mentioned prior art, arranging a large number of sensors corresponding to the platen requires a complicated document size detecting mechanism, and requires a large number of sensors. However, there is a problem that a circuit required for transmission and reception of the signal and a mechanism of the control device become complicated.
Further, in addition to an increase in the manufacturing cost of the apparatus, there are many problems in maintenance, and there is a problem in that a signal of an erroneous detection is output if the position where the document is set on the platen is slightly changed. Therefore, a plurality of sensors are arranged in the scanning device, and a prescan operation is performed before scanning of the document to detect the document size. However, in the case of using the pre-scan method, there is a problem that the number of copies per unit time is reduced because the image reading operation cannot be performed immediately after the document is set on the platen.

As a means for solving the above-mentioned problem, in a digital image reading apparatus, before scanning of a document, the scanning device is moved to perform an operation of reading the size of the document so that the document size can be accurately determined. Means that allow detection may be used. However, even when using a CCD image sensor, it is necessary to perform a prescan operation using a scanning device, and the problem that the number of copies per unit time is limited remains.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problem of the document size detecting means in the above-mentioned conventional image reading apparatus. It is an object of the present invention to provide an apparatus capable of obtaining accurate document size information without affecting the number of documents read.

According to the present invention, there is provided a digital image reading method in which an original is set on a platen glass, and the light of an image obtained by scanning the original by a scanning device is converted into an electric signal using an image sensor to read the image. Related to the device. The invention according to claim 1 of the present invention is arranged such that a home position of the scanning device is provided at a predetermined interval from a leading end of the document in a moving direction of the scanning device, and light from the scanning device located at the home position is provided. Detecting means for detecting a document width based on the converted electric signal; detecting means including one or more photosensors for detecting the length of the document;
Using the information from the two types of detection means to determine the size of the document and the direction of the document, and move the scanning device toward the leading edge of the document after detecting the document width at the home position. Then, scanning for reading the document image is started. With the configuration described above, the configuration of the document size detection mechanism can be simplified, and the information on the document size can be output accurately. Then, it is not necessary to perform a pre-scan operation on the document by the scanning device, and it is possible to easily obtain the detection information of the document width.

According to a second aspect of the present invention, a scanning device is moved from a predetermined home position, and a pre-scan is performed only on the leading edge of the original to detect the width of the original. Detecting means provided with one or more photosensors for detecting the size of the document and the direction of the document using information from the two types of detecting means, After the document width is detected by the prescan, scanning for reading a document image is started. Therefore, in order to obtain information on the width of the document by pre-scanning only a very short section at the leading end of the document and obtain the length from the photo sensor, the size of the document is determined based on the two types of information. This can greatly reduce the influence on the number of sheets read per unit time and the like, and can improve the efficiency of reading.

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A document size detecting apparatus according to the present invention will be described with reference to the illustrated example. The embodiment of the present invention shown in FIG. 1 shows a configuration of a scanning device and a document size detecting mechanism in an image forming apparatus 1 such as an electronic copying machine. The configuration is the same as in the case of an image reading apparatus such as an electronic copying machine. That is, the document 21 is set on the platen glass 2 and is supported in a state where the document 21 is pressed by the platen cover 5 thereon.
The platen cover 5 is provided with a platen cushion 6 so that the image surface of the original can be uniformly pressed against the platen glass 2 even when the original is a thin book or the like. A leading edge registration guide 3 is provided at the leading end of the platen glass 2 in the moving and scanning direction of the document. When the leading end of the document is pressed against the leading edge registration guide 3, the size of the document relative to the document is reduced. Detection and scanning can be performed.

A scanning device 10 is disposed on the lower surface of the platen glass 2, and the scanning device 10 is a carriage member that reciprocates along the lower surface of the platen, similarly to a scanning system in a general electronic copying machine. (Not shown). In the scanning device 10, the platen 2
A lamp 11 for scanning the entire document 21 and a first mirror 12 are arranged on a document 21 placed on the second mirror. A second mirror 12 transmits light reflected by the mirror 12 to the CCD image sensor 16. 13 and a third mirror 14 are arranged, and the two mirrors 13 and 14 are driven synchronously at half the speed of the lamp movement. The scanning light of the image reflected by the plurality of mirrors 12 to 14 is imaged by the lens 15
The light is incident on the D image sensor 16, converted into an electric signal by the CCD image sensor 16, and output to a storage device such as a computer or a writing device in a laser printer or an electronic copier.

In the image reading apparatus 1 of the present invention configured as described above, a longitudinal direction detecting sensor 20 is provided to detect the size of the document 21 placed on the platen, and the sensor 20 is provided with a cover. It is attached to the member 17. Sensor 20 provided on cover member 17
As shown in FIG. 2, the document is arranged at a position slightly behind the detection position of the rear end detection position of the maximum size of the document which can be set on the platen in the horizontal direction. Then, the original 21 is positioned and set on the platen glass 2 with the leading end of the original 21 positioned at the leading end registration line Y and the side of the original positioned at the side registration line X, and the size of the original is detected. And image scanning.

For example, in the illustrated example, if the size of the platen is formed corresponding to the A3 vertical feed,
When the A4 size document Pd is fed horizontally, the sensor 20 is arranged at a position off the rear end of the document. Also,
In order to accurately detect the width of the original, the pressing surface of the cushion 6 of the platen cover 5 is formed of a colored sheet 7 so that the operation of determining the width of the white original can be performed accurately. The colored sheet 7
In order to separate the original from the white one,
Any color can be used.

Accordingly, A
Except for the case of the vertical feeding of 5 sizes, all the documents of the larger size than those of the vertical feeding are detected by the sensor 20. On the other hand, in the case of the document being fed horizontally, the A4 document having the maximum size due to the size of the platen is not detected by the sensor 20, and when the document is detected by the sensor 20, the document is not detected. It turns out that it is in the state of vertical feed. Further, in the apparatus of the present invention, in order to detect the width of the original, the scanning information of the leading end of the original by the CCD image sensor 16 is used. The document size can be determined by combining the document length detection information from the sensor 20 and the document width detection information from the CCD image sensor.

In the document size detecting means of the present invention provided with the above-described mechanism, the position of the home position in the scanning device is set within a range of several mm to several tens mm from the leading end of the document. When the start button of the image reading device is pressed, the width of the document is immediately detected by the scanning device, and then the carriage holding the lamp of the scanning device is returned to the scanning start end of the platen 2 to scan the document. According to the mode, scanning of the document is started. In addition, the portion where the width of the document is detected can be set within a range of several mm to several tens of mm from the leading end of the image area of the document, so that there is no problem in reading the image. . Then, based on the information on the length detected by the sensor 20 and the information on the width detected by the CCD image sensor 16, the document size and the setting direction are immediately determined, and the subsequent reading operation is controlled. To do.

Therefore, in the document size detecting device of the present invention, it is not necessary to perform a pre-scan operation on the document by the scanning device, so that the reading efficiency of the image reading device can be improved. When the image reading apparatus is applied to an electronic copying machine, the number of copies per unit time in the electronic copying machine can be increased, and the copying efficiency can be improved. When the image reading device is used by connecting it to a storage device such as a control device, the reading speed can be greatly improved.

In the apparatus of the present invention, as shown in FIG. 3, the sensor 20 can be provided on the platen cover 5. In the example shown in FIG. 3, the sensor 20 is disposed in a state of being embedded in the cushion 6 of the platen cover 5 so as to detect the length of the document. The coloring sheet 7 is provided on the lower surface of the platen cushion 6 so that the operation of detecting the width of the original by the CCD image sensor can be easily performed.

Further, in the present invention, it is also possible to use a plurality of sensors in accordance with the type of the document size to be detected and the like.
Even when ~ 3 sensors are used to detect the length of the original,
The number of sensors can be reduced as compared with the conventional document size detection mechanism, and the size detection mechanism is not particularly complicated.

As described above, the stop position of the scanning device is
In addition to using the means for setting the inside of the tip registration line Y, in the present invention, when the home position of the scanning device is set to a position deviated from the platen 2 and the switch of the image reading device is turned on. Alternatively, a method in which the scanning device is moved by a short distance to perform pre-scanning can be used. When performing pre-scan as described above,
Of course, the operation will slightly delay the start timing of reading, but the moving distance of the scanning device is
By limiting the width of the leading edge of the document to the minimum range that can be detected, the delay time can be extremely shortened. Therefore, even in the case of using the pre-scanning method as described above, it is possible to greatly improve the reading efficiency as compared with a method of scanning the entire original and determining the original size as in the conventional apparatus. it can.

The document size detecting means of the present invention configured as described above is not used only for an image reading apparatus connected to a computer.
It can be used as an image reading device of an electronic copier, or as a scanning device for other original images. By using a document length detecting means by one or a plurality of sensors and a document width detecting means by a CCD image sensor, the document size can be easily detected at the start of the reading operation, The subsequent reading operation can be easily controlled.

[0022]

The apparatus of the present invention uses the above-described scanning apparatus for detecting the width of the document and a sensor for detecting the length of the document, so that the structure of the detecting mechanism can be simplified. At the same time, it is possible to accurately output document size information. Further, the device of the present invention can reduce the number of sensors to be used, and can solve problems such as malfunction due to a reduction in the number of types of signals output to the control device. , The maintenance of the detection mechanism can be easily performed. According to the first aspect of the present invention, it is not necessary to perform a pre-scan operation on the document by the scanning device, and it is possible to easily obtain detection information of the width of the document. Claim 2
According to the invention, the width of the document is obtained by pre-scanning only a very short section at the leading end of the document by the scanning device, and the length is obtained from the photo sensor. You can decide the size of the original,
The influence on the number of sheets read per unit time or the like can be greatly reduced, and the reading efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an image reading device of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between an arrangement position of a sensor with respect to a platen and a document size.

FIG. 3 is an explanatory diagram showing another example of a method of arranging sensors.

FIG. 4 is an explanatory diagram showing a relationship between the arrangement of a conventional detection device and a document size.

[Explanation of symbols]

1 image reader, 2 platen glass, 5
Platen cover, 7 colored sheet, 10 scanning device, 11 light source, 12-14 mirror, 1
5 lenses, 16 CCD image sensors, 20
Sensor, 21 originals, Y tip line, X
Side cash register line.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/04-1/207

Claims (2)

(57) [Claims] 1. A digital image reading apparatus in which an original is set on a platen glass and light of an image obtained by scanning the original by a scanning device is converted into an electric signal using an image sensor to read the image. A home position of the scanning device is provided at a predetermined distance from a leading edge of the document in a moving direction of the scanning device, and the width of the document is detected by an electric signal obtained by converting light from the scanning device located at the home position. And a detecting unit having one or more photosensors for detecting the length of the document. The size of the document is determined by using information from the two types of detecting units. The direction of the document is determined, and after the document width is detected at the home position, the scanning device is moved toward the leading edge of the document to read the document image. Image reading apparatus characterized by starting the scan for. 2. A digital image reading apparatus in which a document is set on a platen glass and light of an image obtained by scanning the document by a scanning device is converted into an electric signal to read the image. Moving from a predetermined home position, prescanning is performed only on the leading edge of the document, and a detecting means for detecting the width of the document, and one or more photosensors for detecting the length of the document are provided. A detecting means provided with the detecting means, and using information from the two kinds of detecting means, the size of the document and the direction of the document are determined, and after the document width is detected by the prescan, the document image reading is performed. An image reading apparatus for starting scanning for reading.