JP2005164716A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically detect a document size without making a user feel dazzling in an image scanner. <P>SOLUTION: On the document-side surface of a platen cover which covers a platen, a light source is provided linearly in a horizontal scanning direction. When a document size is automatically detected, a carriage is moved to a position opposite to the cover-side light source. The size of the document is detected on the basis of the output of a linear image sensor when the carriage moves to the position opposite to the cover-side light source and the cover-side light source is lit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus having a function of reading an image of an original, such as an image scanner, a facsimile, a copying machine, and an MFP (Multi Function Peripheral).

  Automatically detects the size and orientation of the original placed on the platen to automatically select the paper size for copying the original image, set the copy magnification, and process the scanned image. There is known an image reading apparatus having a function to perform this function.

Japanese Patent Application Laid-Open No. 2004-228561 discloses an image reading apparatus that performs pre-scanning with a document cover opened in order to automatically detect the size of a document placed on a platen. In such an image reading apparatus, an exposure lamp that exposes a document in the main scan is also used for pre-scanning. When the document cover is closed, the light from the exposure lamp is reflected by the document placed on the platen or the document cover. Even when the document cover is opened, if the document is placed on the platen, the light from the exposure lamp is reflected at that portion. On the other hand, in a place where the platen original is not placed, the light from the exposure lamp is not reflected by the original cover or the original, but is transmitted through the platen glass and emitted as it is. For this reason, when the reflected light is imaged with the document cover opened, a bright value is obtained at a place where the platen document is placed and a dark value is obtained at a place where the platen document is not placed. By setting an appropriate threshold value for the output of the imaging means for imaging the reflected light, it is possible to distinguish between the place where the original on the platen is placed and the place where the original is not placed. It is possible to obtain a length from one end to the other end.
JP 7-177310 A

  However, as long as pre-scanning is performed with the document cover open, the user feels some glare from the light leaked from the place where the platen document is not placed.

  The present invention has been made to solve the above-described problems in the prior art, and provides an image reading apparatus capable of automatically detecting the size of a document without causing the user to feel dazzling. It is for the purpose.

  In order to achieve the above object, the present invention employs the following means.

  In the image reading apparatus of the present invention, the light source is linearly provided in the main scanning direction parallel to the scanning direction of the imaging unit on the surface of the platen cover that covers the platen on the document side. As the cover-side light source, a plurality of LEDs (Light Emitting Diodes) arranged linearly in the main scanning direction can be used. The control means performs control to move the carriage to a position facing the cover-side light source. The carriage can reciprocate in the sub-scanning direction perpendicular to the scanning direction of the image pickup means, and the optical system guides light incident from the platen on which the document is placed to the image pickup means using the carriage. When reflected light from the exposed document is guided to the image pickup means, an image of the document can be obtained. The size detection means detects the size of the document based on a captured image when the carriage is at a position facing the cover-side light source and the cover-side light source is turned on. If the cover side light source is provided, it is not necessary to detect the size of the document with the platen cover open. At the place where the original on the platen is placed, the light from the cover-side light source is blocked by the original and is not guided to the image pickup means even if the carriage is at a position facing the cover-side light source. On the other hand, in a portion where the platen original is not placed, if the carriage is at a position facing the cover-side light source, light from the cover-side light source is guided to the imaging means. For this reason, a dark value is obtained at a place where the original on the platen is placed, and a bright value is obtained at a place where the original is not placed. Thus, since the presence or absence of reflection is not used, the size of the document can be detected even when the platen cover is closed.

  The cover-side light source is preferably not disposed on the document side surface of the platen cover, but is disposed between the document side surface of the platen cover and the document mat covering the surface. Using a semi-transparent mat, light from an exposure light source that exposes an original is reflected and light from a cover-side light source is transmitted. Thereby, it is possible to avoid the cover side light source from affecting the read image of the document.

  Further, in order to confirm that the platen cover is closed, the image reading apparatus may be provided with an opening / closing detection means for detecting opening / closing of the platen cover. At this time, the cover-side light source lights up in a state where it is detected that the platen cover is closed.

  As described above, in the image reading apparatus of the present invention, the size of the document can be automatically detected with the platen cover closed, and the user can avoid feeling dazzled due to the detection.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In this embodiment, the image reading apparatus of the present invention is embodied as a digital copying machine. FIG. 1 shows the overall appearance of the digital copying machine.

  As shown in FIG. 1, the digital copying machine 100 includes a DF (Document Feeder) 101 on an upper side of an image reading unit 201 and an image forming unit 301 that forms an image of a placed document on a sheet. Prepared on the underside.

  As shown in FIG. 2, a glass platen 202 for placing a document is arranged on the upper surface of the image reading unit 201. When reading an image of a document using the image reading unit 201, the user places the document on the document tray 102 of the DF 101 or directly places it on the platen 202. The document placed on the document tray 102 is automatically fed onto the platen 202 by the DF 101.

  As shown in FIG. 3, an imaging unit 203 in which a plurality of imaging elements are arranged in a line is provided below the platen 202. The imaging means 203 can be a CCD (Charge Coupled Device) linear image sensor. When the optical image of the original is guided to the image pickup unit 203, an electric signal of the original image is obtained by photoelectric conversion of the image pickup unit 203. The image processing unit 204 processes the image data obtained by analog / digital conversion of the electrical signal by performing shading correction, pseudo gradation processing, and further, if necessary, image processing such as enlargement or reduction. The supplied data is supplied to the image forming unit 301. The image processing unit 204 can be realized by combining, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory) used for a work area, a non-volatile memory for holding programs and setting values, and the like. . An LSI (Large Scale Integration) or an ASIC (Application Specific Integrated Circuit) may be used. The image forming unit 301 copies a document image on a sheet based on the image data supplied from the image reading unit 201.

  The optical system 205 guides light incident from the platen 202 to the imaging unit 203 using a carriage 206 that can reciprocate in a sub-scanning direction perpendicular to the main scanning direction parallel to the scanning direction of the imaging unit 203. The carriage 206 is provided with an exposure light source 207 for exposing a document and a reflecting mirror 208 disposed at a position where reflected light from the exposed document is incident. For example, a fluorescent lamp is used as the exposure light source 207. The linear lamp is arranged in parallel to the main scanning direction. When the exposure light source 207 is turned on and the document is exposed through the platen 202, the light is reflected by the document on the platen 202. The reflected light is further reflected in the horizontal direction by the reflecting mirror 208 of the carriage 206 and guided to the condensing lens 211 by the mirrors 209 and 210 of the optical system 205 as shown in the optical path shown by the one-dot chain line in FIG. The condensing lens 211 forms the guided light image on the imaging unit 203.

  When an original is placed on the platen 202, the carriage 206 moves in the sub-scanning direction to mechanically scan the original. A two-dimensional image of the entire surface of the document can be obtained by a combination of this mechanical scanning and the scanning of the imaging means 203. When the document is placed on the document tray 102 of the DF 101, the carriage 206 does not move from the reading position, and mechanical scanning is performed as the document passes the reading position by feeding the DF 101.

  When an image of a document is obtained as described above, when external light enters the reflecting mirror 208 through the platen 202, the external light affects the image of the document. A platen cover that covers the platen 202 is used to prevent this and to hold down the document placed on the platen 202. As shown in FIG. 2, the DF 101 is attached to the rear end of the upper surface of the image reading unit 201 so as to be freely opened and closed. Here, the DF 101 is used as a platen cover. In an image reading apparatus that does not have the DF 101, a plate-like cover is used. A normal white original mat is mounted on the original side of the plate cover. In the DF 101, the white belt 103 used for feeding an original corresponds to the original mat. When the document is placed on the platen 202, the belt 103 does not move, and the portion exposed from the document-side surface 104 of the DF 101 has a mat shape.

  In this embodiment, as shown in FIG. 4, a light source 105 is linearly provided in the main scanning direction between the document-side surface 104 of the DF 101 and the belt 103. The cover side light source 105 is used instead of the exposure light source 207 to detect the size of the document in the main scanning direction.

  As the cover-side light source 105, a plurality of LEDs 106 arranged linearly in the main scanning direction can be used. These LEDs 106 may be provided at regular intervals, or when an A4, B5, or B4 size document is placed in the vertical or horizontal direction, the size in the main scanning direction can be distinguished for each case. They may be arranged at intervals. If necessary, a light source that emits light continuously in the main scanning direction may be used.

  In order to obtain the size of the document in the main scanning direction in various cases as described above, the size of the document placed on the platen 202 in the main scanning direction may be shorter than the length of the cover-side light source 105 in the main scanning direction. Arise. When a plurality of LEDs 106 are arranged, the size of the document placed on the platen 202 in the main scanning direction may be shorter than the length between the LEDs 106 at both ends.

  Therefore, it is preferable to provide the cover-side light source 105 between the document-side surface of the cover and the document mat even in the platen cover of the image reading apparatus that does not have the DF 101. Accordingly, when the cover-side light source 105 is exposed to the platen 202, when the size of the document placed on the platen 202 is shorter than the length of the cover-side light source 105 in the main scanning direction, It is avoided that not only the original but also a part of the cover-side light source 105 is imaged.

  Further, in order to detect the size of the document in the main scanning direction, the light from the cover-side light source 105 needs to reach the platen 202. Therefore, the light source is disposed between the document-side surface of the platen cover and the document mat or belt 103. When 105 is provided, a semi-translucent material is used for the original mat and the belt 103. It is preferable to use a mat or belt 103 that reflects light from the exposure light source 207 and transmits light from the cover-side light source 105.

  Here, for the sake of convenience, the CPU, RAM, and nonvolatile memory of the image processing unit 204 are used for controlling the lighting of the cover-side light source 105. In this case, the non-volatile memory stores various control programs in addition to the image processing program. The CPU reads a control program from the non-volatile memory into the RAM, and controls turning on (and turning off) the cover-side light source 105 and controlling the drive motor of the carriage 206 in accordance with an instruction of the control program. Hardware such as a CPU and RAM of a computer incorporated in the copying machine cooperates with the control program, so that an image reading apparatus having these functions can be realized. FIG. 5 shows a functional block diagram of the image reading apparatus.

  The image reading apparatus includes a control unit 212 and a size detection unit 213 as shown in FIG. 5 in addition to the imaging unit 203, the optical system 205, and the cover-side light source 105.

  The control unit 212 controls the drive motor 214 of the carriage 206 to move the carriage 205 to a position facing the cover-side light source 105. Here, the control unit 211 further controls lighting of the cover-side light source 105.

  The size detection unit 213 detects the size of the document in the main scanning direction based on a captured image when the carriage 206 is at a position facing the cover-side light source 105 and the cover-side light source 105 is turned on. Here, the captured image is configured by digital data output from a linear image sensor.

  The CPU described above performs calculation and input / output control in accordance with the instructions of the control program, whereby the computer hardware functions as the control means 212 and the size detection means 213.

  It is preferable that the image reading apparatus further includes an open / close detection unit 215. The opening / closing detection means 215 detects opening / closing of the platen cover, here the DF 101. As the opening / closing detection means 215, a push button switch 216 can be used as shown in FIG. When the DF 101 is closed, the push button switch 216 is pressed on the document side surface of the DF 101. Therefore, the opening / closing of the DF 101 can be detected by monitoring the on / off of the switch 215 by the CPU.

  When the image reading apparatus includes the open / close detection unit 215, the control unit 212 turns on the cover-side light source 105 after detecting that the platen cover is closed, and detects that the platen cover is open. In the state, the cover side light source 105 is turned off.

  When the user places a document on the platen 202 of such an image reading apparatus and closes the DF 101, the CPU executes a procedure as shown in FIG. 6 in accordance with an instruction of the control program.

  When the push button switch 215 is pressed by closing the DF 101, the signal from the push button switch 216 changes, and the CPU detects that the DF 101 is closed based on this change (S1).

  When it is detected that the DF 101 is closed, the CPU functions as the control unit 212 according to the instruction of the control program, and controls the drive motor 214 of the carriage 206 so that the carriage 206 faces the cover-side light source 105 from the standby position. (S2).

  When the carriage 206 moves to a position facing the cover-side light source 105, the CPU turns on the cover-side light source 105 that has been turned off (S3).

  When the cover 206 is turned on while the carriage 206 is moved to a position facing the cover-side light source 105, the light from the cover-side light source 105 is blocked by the document at the place where the document on the platen 202 is placed. . On the other hand, at the place where the document is not placed, the light from the cover-side light source 105 enters the reflecting mirror 208 of the carriage 206 as in the optical path shown by the dotted line in FIG. The light is guided to the imaging unit 203 through the mirrors 209 and 210 of the optical system 205 and the condenser lens 211 in the optical path indicated by the one-dot chain line.

  When the carriage 206 moves to a position facing the cover-side light source 105 and the output of the linear image sensor when the cover-side light source 105 is turned on in this way, the CPU functions as the size detection means 213, Based on the output, the size of the document placed on the platen 202 in the main scanning direction is detected (S4).

  As shown in FIG. 7, in the main scanning direction of the platen 202, the light from the cover-side light source 105 is blocked at the place R1 where the original is placed, so the output of the linear image sensor shows a dark value, and the original is Since most of the light from the cover-side light source 105 that has passed through the belt 103 is incident on the linear image sensor at the unplaced portion R2, the output of the linear image sensor shows a bright value.

  The CPU sets the position R1 where the original is placed and the original according to whether the output value of the linear image sensor at the position of the platen 202 in the main scanning direction is greater than or less than a preset threshold value TH. The location R2 that is not performed is specified.

  Both ends of the document in the main scanning direction are determined based on the specified location, and the size of the document in the main scanning direction is obtained based on the length between the both ends. When a value of a size in the main scanning direction corresponding to the prescribed size of the document or the document placement direction of the prescribed size is given in advance, the CPU detects the detected size from the obtained plural values. By selecting the value closest to, the size in the main scanning direction is determined.

  When the size of the document in the main scanning direction is detected in this way, the CPU turns off the cover-side light source 105 (S5). Thereafter, when the user presses the execution button 218 of the operation panel 217 provided in front of the image reading unit 201, the process shifts to reading control of the document image (S6), and the exposure light source 207 that has been turned off until then is turned on. In this state, the carriage 206 moves to scan the document. As a result, the image on the entire surface of the original is read, and the read image is copied onto the paper by the image forming unit 301.

  In the image reading apparatus in this embodiment, as described above, the size of the document in the main scanning direction can be detected by providing the cover-side light source 105 even when the platen cover is closed. Therefore, it is possible to avoid making the user feel dazzling.

  Furthermore, even if the platen cover is not completely closed, if the light from the cover-side light source 105 leaks from between the platen cover and the platen 202, most of It does not enter the user's eyes. Accordingly, even if the open / close detection unit 215 does not detect that the platen cover is closed as much as necessary, the glare felt by the user is significantly reduced as compared with the case where the exposure light source 207 is used for automatic document size detection. . In addition, when the push button switch 216 cannot detect that it is closed as much as necessary, a sensor that detects the opening / closing angle of the platen cover may be used instead of or in addition thereto.

  If the platen cover is closed by more than half, there is almost no fear of dazzling as described above. On the other hand, if the platen cover is opened by more than half, the direction of light from the cover-side light source 105 approaches the human eye. Therefore, the output of the opening / closing angle detection sensor is halved even though the user can explicitly instruct the automatic detection of the document size from the operation panel 217 or the push button switch 216 indicates that the cover is closed. The CPU or the control unit 212 may prohibit the lighting of the cover-side light source 105 based on the output of the opening / closing angle detection sensor in preparation for the case where the opening is indicated.

  Further, in the image reading apparatus in this embodiment, the image pickup means 203 and the optical system 205 for reading an image are also used for automatic detection of the document size. Therefore, it can contribute to the cost reduction of the image reading apparatus.

  This embodiment does not limit the technical scope of the present invention, and various modifications and applications can be made within the scope other than those already described. For example, as already described, the image reading apparatus can use a plate-like cover as the platen cover instead of the DF 101. At this time, it is preferable to provide the cover side light source 105 between the document side surface of the cover and the semi-transparent document mat. However, the present invention is not limited to this. A semi-transparent shielding member that shields the cover-side light source 105 may be provided separately from the original mat and the belt 103. Further, when the cover-side light source 105 is disposed in an exposed state, an image corresponding to the cover-side light source 105 is held in advance in a nonvolatile memory or the like, and a captured image of the document is corrected based on the image. The image processing may be performed.

  In the procedure of FIG. 6, the document size is automatically detected after the carriage 206 has moved to a position facing the cover-side light source 105. From the detection result of the position of the carriage 206, the carriage 206 detects the cover-side light source 105. It is unnecessary to move the carriage 206 when it is confirmed that the carriage 206 is already at a position opposite to. If the carriage 206 is at a position facing the cover-side light source 105 and the output of the linear image sensor when the cover-side light source 105 is turned on, the size of the document on the platen can be detected.

  Further, although the embodiment in which the belt 103 is used for conveying the document has been described, a configuration may be adopted in which the document is read by passing the document reading position by a roller without using a belt.

  Further, hardware and software that function as the control unit 211 and the size detection unit 212 may be provided separately from the image processing unit 204.

  Furthermore, the present invention can be applied not only to digital copying machines but also to image scanners, facsimiles, MFPs, and the like.

  The image reading apparatus of the present invention can automatically detect the document size without making the user feel dazzling, perform image processing with an image scanner, facsimile, digital copier, MFP, etc., select paper, This is useful for automatically setting the magnification.

The figure which shows the external appearance of the whole image processing apparatus in embodiment of this invention Perspective view of image reading unit The figure which shows the structure of an image reading part The figure for demonstrating the arrangement | positioning state of a cover side light source Functional block diagram of an image processing apparatus in an embodiment of the present invention Flow chart for explaining the procedure of automatic detection of document size The figure which shows the output example of the linear image sensor at the time of document size detection

Explanation of symbols

101 DF
102 Document tray 103 Belt 105 Cover side light source 106 LED
DESCRIPTION OF SYMBOLS 201 Image reading part 202 Platen 203 Imaging means 204 Image processing part 205 Optical system 206 Carriage 207 Exposure light source 208 Reflecting mirror 212 Control means 213 Size detection means 215 Open / close detection means 216 Pushbutton switch 301 Image formation part

Claims (6)

An image reading apparatus for reading an image of a document,
Imaging means;
An optical system that guides light incident from a platen on which a document is placed to an imaging unit using a carriage movable in the sub-scanning direction;
A cover-side light source linearly provided in the main scanning direction on the surface of the platen cover that covers the platen;
An image reading apparatus comprising: means for detecting a size of a document based on a captured image when the carriage is positioned to face the cover-side light source and the cover-side light source is turned on.   The image reading apparatus according to claim 1, further comprising means for controlling the carriage to move to a position facing the cover-side light source. A semi-transparent original mat is mounted on the original side of the platen cover,
The image reading apparatus according to claim 1, wherein the cover-side light source is disposed between a document-side surface of the platen cover and a document mat.   The image reading apparatus according to claim 1, wherein the cover-side light source includes a plurality of LEDs (Light Emitting Diodes) arranged linearly in the main scanning direction. Means for detecting opening and closing of the platen cover;
The image reading apparatus according to claim 1, wherein the cover side light source is turned on in a state where the platen cover is closed. An image reading apparatus for reading an image of a document,
A platen for placing the manuscript;
A platen cover that covers the platen;
A linear image sensor,
An exposure light source that exposes an original placed on the platen, a carriage that is disposed at a position where reflected light from the exposed original is incident, and a carriage that is movable in the sub-scanning direction;
An optical system that guides the light from the reflector to the linear image sensor;
A cover-side light source linearly provided in the main scanning direction on the surface of the platen cover that covers the platen;
Means for controlling the cover side light source to move the carriage to a position facing the reflecting mirror;
An image reading apparatus comprising: means for detecting a size of a document on the platen based on an output of a linear image sensor when the carriage moves to a position facing the cover side light source and the cover side light source is turned on.

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