JP2003316207A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct difference in front and back when a manuscript is to be set. <P>SOLUTION: When a document direction discrimination section 306 judges that there is no region information by using an automatic manuscript feed apparatus 142 that is capable of inversion feed of a manuscript, namely when the section 306 judges that the region information is blank, the automatic manuscript feed apparatus 142 in a controller 139 is controlled, the manuscript is automatically inverted inside out, and the direction of the manuscript is discriminated. When the section 306 judges that the region information is not blank, the image is formed as it is. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which processes image data read by a reading means such as a digital copying machine and prints it on a recording material.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus having a document orientation detecting function such as a digital copying machine, an apparatus having an automatic document feeding apparatus capable of reversing and feeding an original and capable of automatic double-sided printing has been used. .

[0003]

However, the image on one side of the original is read and printed on one side of the recording material. Single-sided mode and two originals are printed on both sides of one recording material. Single-sided. In the mode, there is a problem in that when the user of the apparatus makes a mistake in the front and back sides of the document when setting the document and the back side of the document, that is, the side without an image, is read, an output not intended by the user is obtained.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to use an automatic document feeder capable of reversing and feeding an original, and the document direction discriminating means does not have area information. If it is judged that it is a blank sheet, the document is automatically turned upside down and the document orientation is determined again.
An object of the present invention is to provide an image forming apparatus that can correct an error in front and back when setting a document by directly forming an image when it is determined that the sheet is not blank.

[0005]

A first aspect of the present invention is an automatic document feeder capable of reversing and feeding an original, and a document orientation determining means for determining an image area and a document orientation from image data in the original. And a control means of the automatic document feeder based on the determination result of the blank sheet determining means and the blank sheet determining means for determining whether the document is a blank sheet based on the determination result of the document orientation determining means.

A second invention according to the present invention is characterized in that, when the result of the determination by the blank sheet determining means is a blank sheet, the control means reverses the original and the blank sheet determining means determines a blank sheet.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view for explaining the structure of an image forming apparatus showing an embodiment of the present invention. Reference numeral 101 denotes a document table glass, which is an automatic document feeder 1 capable of reverse feeding.
The documents fed from 42 are sequentially placed at predetermined positions. Reference numeral 102 denotes a document illumination lamp composed of, for example, a halogen lamp, which exposes a document placed on the platen glass 101. Scanning mirrors 103, 104 and 105 are housed in an optical scanning unit (not shown) and guide the reflected light from the document to the CCD unit 106 while reciprocating. The CCD unit 106 is an imaging lens 107 that forms an image of reflected light from a document on the CCD, an image sensor 108 including, for example, a CCD, and a CC that drives the image sensor 108.
It is composed of a D driver 109 and the like. Image sensor 10
The image signal output from 8 is converted into 8-bit digital data, for example, and then input to the controller unit 139. Further, 110 is a photosensitive drum, and the pre-exposure lamp 112 removes electricity in preparation for image formation. Reference numeral 113 denotes a primary charger, which uniformly charges the photosensitive drum 110. Reference numeral 117 denotes an exposure unit, which is composed of, for example, a semiconductor laser or the like, exposes the photosensitive drum 110 based on image data processed by a controller unit 139 that performs image processing and control of the entire apparatus, and forms an electrostatic latent image. . Reference numeral 118 denotes a developing device, which contains a black developer (toner). Reference numerals 119 and 119 denote pre-transfer chargers for the photosensitive drum 110.
A high voltage is applied before the toner image developed above is transferred to the paper. 120, 122, and 124 are paper feeding units,
The transfer paper is fed into the apparatus by driving the paper feed rollers 121, 123, and 125, and is temporarily stopped at the position where the registration roller 126 is provided, and the writing timing with the image formed on the photosensitive drum 110 is set. Redelivered. 12
A transfer charger 7 transfers the toner image developed on the photosensitive drum 110 onto the transfer paper fed. Reference numeral 128 denotes a separation charger, which separates the transfer sheet after the transfer operation from the photosensitive drum 110. Photosensitive drum 11 without transfer
The toner remaining on the surface 0 is collected by the cleaner 111. Reference numeral 129 is a conveyor belt, which conveys the transfer sheet after the transfer process to the fixing device 130 and fixes the transfer sheet by, for example, heat. Reference numeral 131 denotes a flapper, which is used to feed a transfer sheet for which the fixing process has been completed to a staple sorter 132.
Alternatively, it is controlled to either the arrangement direction of the intermediate tray 137. The sheets discharged to the staple sorter 132 are sorted into bins, and the staple unit 141 performs stapling according to an instruction from the controller unit 139. 133-1
Reference numeral 36 denotes a feeding roller that feeds the transfer paper, which has once undergone the fixing process, to the intermediate tray 137 after reversing (multiplexing) or non-reversing (both sides). A re-feeding roller 138 conveys the transfer sheet placed on the intermediate tray 137 again to the position where the registration roller 126 is provided.

The controller unit 139 is provided with a microcomputer, an image processing unit, etc., which will be described later, and performs the above-mentioned image forming operation in accordance with an instruction from the operation panel 140.

FIG. 2 is a block diagram of the controller unit 139 in the image forming apparatus of the present invention.

Reference numeral 201 denotes C for controlling the entire image processing apparatus.
A PU, which sequentially reads and executes programs from a read-only memory (ROM) 203 that stores a control procedure (control program) of the apparatus body. The address bus and data bus of the CPU 201 are connected to each load via a bus driver circuit and an address decoder circuit 202. A random access memory (RAM) 204 is a main memory used as a storage area for input data, a work storage area, and the like. Reference numeral 205 denotes an I / O interface, which is used by an operator to input keys to display a device status and the like using a liquid crystal display and LEDs, and motors 207 for driving a paper feed system, a transport system, and an optical system. , Clutches 208, solenoids 209, and paper detection sensors 210 for detecting the conveyed paper, etc. are connected to respective loads of the apparatus. The developing device 118 is provided with a toner remaining detection sensor 211 for detecting the amount of toner in the developing device, and the output signal thereof is input to the I / O port 205. A high-voltage unit 215 outputs high voltage to the above-described primary charger 113, developing device 118, pre-transfer charger 119, transfer charger 127, and separation charger 128 in accordance with instructions from the CPU.

An image processing unit 206 receives the image signal output from the CCD unit 106, performs image processing to be described later, and executes laser processing according to the image data.
The control signal 17 is output. The laser light output from the laser unit 117 irradiates and exposes the photosensitive drum 110, and the light emission state is detected by the beam detection sensor 213 which is a light receiving sensor in the non-image area, and the output signal is output from the I / O port 205. Entered in.

FIG. 3 is a block diagram of the image processing unit 206 in the controller unit 139 in the image forming apparatus of the present invention.

The image signal converted into an electric signal by the CCD 108 is first corrected for variations between pixels by a shading circuit 301, and then a scaling circuit 302 performs data thinning processing during reduction copying to enlarge copying. When the data is interpolated. Next, in the edge emphasis circuit 303, for example, the second-order differentiation is performed in a 5 × 5 window to emphasize the edge of the image. Since this image data is luminance data, data conversion is performed by a table search in the γ conversion circuit 304 in order to convert it into density data to be output to the printer. The image data converted into the density data is input to the binarization processing unit 305. Here, multi-valued data is converted into binary data by the ED method, for example. Two
The image data converted into values is input to the synthesis circuit 307. The synthesizing circuit 307 selectively outputs the input image data and the image data in the image memory 310 composed of, for example, a DRAM, or outputs it by ORing. The read / write control for the image memory 310 is performed by the memory control unit 309, and when the image is rotated, it is performed by controlling the read address of the image data in the memory. These image data are input to the PWM circuit 308 to be converted into a signal of laser emission intensity, and a pulse width according to the density of the image is output to the laser unit. Further, the image output from the scaling circuit 302 is input to the document orientation determination unit 306, and the document orientation determination processing described below is performed.

Next, the document direction discriminating operation in the present invention will be described with reference to FIGS.

FIG. 4 is a block diagram of the inside of the document orientation discriminating unit 306.

The image data output from the scaling unit 302 is input to the CPU / memory unit 401 of the scanner unit 1,
The image data is temporarily saved and various controls are performed. The CPU 201 in the controller unit 139 is bus-connected by, for example, a dual port RAM (not shown), and transmits / receives data. Of course, serial communication may be used.

The character recognizing / orientation discriminating unit 402 pays attention to the fact that it is the character that most accurately represents the orientation of the document, and the several kinds of character areas in the document are represented by 0 °, 90 °, 180.
Character recognition is performed from the directions of 270 ° and 270 °, and the direction with the highest accuracy among the character recognition accuracies in each direction (confidence of character recognition: distance with respect to character feature distribution) is the document direction.

The area separation unit 403 performs rectangular processing of the character portion, the graphic portion, the natural image portion, the front portion, etc. from the document image data as a preprocessing for the character recognition / direction determination processing by the character recognition / direction determination unit 402. This is a block for performing processing for dividing the area into areas and adding the attribute (character portion, etc.) of each area.

The storage device 404 is composed of, for example, a hard disk or a magneto-optical disk, and is used to store various processing results (image data, area separation result, character recognition result, etc.). The I / F unit 405 is a SCSI
And RS232C, etc., and is provided for transmitting data to the outside. Computer 406
Information is obtained via the I / F unit 405, and data is obtained from a movable storage device such as a magneto-optical disk for use.

Next, an outline of the document direction automatic discrimination / correction and character recognition processing in this embodiment will be described with reference to the flowchart of FIG.

The input image data (multi-valued image) is first separated by the area separating unit 403 into rectangular areas according to attributes such as a character portion, a graphic portion, a natural image portion, and a front portion (steps S1 and S2). ). Here, the area information enclosed by the rectangle is actually created.

Next, the rectangle information of the character area is extracted from each attribute (step S3). Here, the character area includes a text part, a title part, characters in a table, a caption part of a figure, and the like. For example, in the case of the documents shown in FIGS. 6A and 6C,
Rectangular information of the character area as shown in FIGS. 6B and 6D is extracted. Then, the document orientation is discriminated by using several blocks among them (step S4). As a result, if the document direction is the forward direction, the character recognition process is continuously performed on the character block in the image (step S
7).

On the other hand, if the document direction is incorrect, the image data is rotated in the correct direction (step S5). Then, the rotation image is subjected to region separation, and the region separation information is corrected (step S6). This is to correct the difference in area separation information due to image rotation, and one method is to perform area separation processing again on all rotated image data. The other is to apply address translation to the area separation result. In the area separation processing, the image is generally assumed to be in the forward direction, and therefore the area separation processing performed in the initial stage and the area separation processing performed on the rotated image data often have different results. Therefore, it is desirable that the former method be adopted.

Next, in step S7, the character area block in the rotated image data is recognized by the character recognition processing system. As a result, the area separation information and the character recognition information are finally obtained in both cases of no rotation / with rotation (step S8).

The processing result is transmitted to the computer 406 via the I / F unit 405 and used by filing application software or the like on the computer 406. In addition, each image is transmitted to the CPU 201 in the controller unit 139.

Next, a method of discriminating a document direction using character recognition processing will be described.

[Region Separation Processing] The black pixels of the document image data are detected, and the rectangular frame of the black pixel block is created by the contour tracking or the labeling method. Next, character areas (titles, text, captions, etc.), graphic areas, natural image areas, table areas, etc. are determined based on the black pixel density in the rectangle, the presence or absence of adjacent rectangular blocks, the aspect ratio of the rectangle, etc. To determine. The rectangular area of the character area is discriminated from the processing result.

[Character Recognition Processing] One method of character recognition processing is a feature vector extraction and comparison method. For example, as shown in FIG. 7A, it is assumed that a character area including the character "book" is identified. As a first step, character cutting processing is performed on this character area (see FIG. 7B). This is a process of cutting out a rectangle of one character, and is obtained by detecting the state of black pixel continuity. In the second step, one character is cut out into m × n (for example, 64 × 64) pixel blocks (see FIG. 7C). Then, the distribution direction of the black pixels is extracted from that using a window of 3 × 3 pixels (direction vector information: see FIG. 7D).

FIG. 7D shows an example of a part of the direction vector information, and the window of 3 × 3 pixels is shifted to obtain dozens of direction vector information. This vector information becomes a character feature. Compare this feature vector with the contents of the character recognition dictionary stored in advance,
Characters are extracted in order from the character having the feature closest to the feature vector. In this case, the first candidate, the second candidate, ... The closeness of the feature to the feature vector is the closeness of the distance to the character, that is, the confidence level (accuracy) of character recognition.

[Character Orientation Discrimination Processing] In this way, the degree of confidence in character recognition is obtained. The character orientation discrimination processing based on the degree of confidence is used by using the sentence example "name of the present invention" shown in FIG. Explain.

FIG. 8A shows a forward sentence, and FIG. 8B shows 2 sentences.
It is a sentence rotated by 70 °. Focusing on the “book” here,
When determining the character direction, as shown in FIG. 8C, 0 °, 90 °, 180 for one character “book”
Let's try character recognition from 4 directions of ° and 270 °. For each rotation angle, the reading method of the character rectangular area may be changed, and the original need not be rotated. The character recognition result at each rotation angle is different from each other, as shown in FIG. It should be noted that FIG. 8C shows the temporary character recognition result and the degree of self-confidence for the purpose of explanation, and it is not always the case.

In FIG. 8 (c), when the character recognition is performed from the forward direction (0 °), it is correctly recognized as "book" and the confidence is 0.90, which is a high value. When the character recognition is performed from the direction rotated by 90 °, it is erroneously recognized as “town” and the confidence level is also reduced to 0.40. False recognition occurs like this,
The reason for the decrease in confidence is that the character recognition is performed based on the feature vector when viewed from the rotated direction. Similarly, when character recognition is performed from a direction rotated by 180 ° or 270 °, erroneous recognition occurs and confidence is also reduced. The difference in the degree of confidence in character recognition depending on the direction becomes more significant as the character is more complicated.

In the result of FIG. 8C, since the confidence degree is highest in the forward direction, it is determined that the document is likely to face in the forward direction. In order to improve the accuracy of character direction discrimination, character recognition is similarly performed from four directions for a plurality of characters in the same block. Furthermore, if the character direction is determined only by one block, the character direction may be erroneously determined for a special character string, so the same character recognition will be performed for a plurality of blocks. And
For each block, the average of confidence in each direction of each recognition target character in the block is calculated, and the average of the confidence in each direction of each block is calculated. Character direction is the highest direction (document direction)
Certify as.

As described above, the character direction is not determined by the confidence level of only one character, but the character direction is determined by the confidence levels of a plurality of characters in the same block, and further, a plurality of characters in the same block. It is possible to determine the (document) direction with high accuracy. However, it goes without saying that the character direction can be determined more accurately than before even if the character direction is determined based on the confidence level of only one character or the character direction is determined based on the confidence levels of a plurality of characters in the same block.

Next, if the result of discrimination of the character direction (document direction) is a direction other than the normal direction, the original image is rotated so that the character direction becomes the positive direction. This rotation is performed by the CPU of FIG.
/ It can be easily performed by a known technique using the memory unit 401, and a description thereof will be omitted.

By the above processing, the original image data shown in FIG. 9A, the area separation data shown in FIG. 9B, and the character recognition information shown in FIG. 9C can be obtained. . As described above, this information is stored in the controller unit 139.
To the CPU 201 and used for various image processing and various controls.

As shown in FIG. 9B, the format of the area separation data is "heade" indicating that it is the area separation data.
r "and the identifiers" rect1 "to" re "of the separated areas
The information of each area (block) distinguished by this identifier is the block number “orde”.
r ", block attribute (character part, graphic part, etc.)" ar
t ”, the upper left coordinate values“ x1 ”and“ y ”of the block
1 ", block width" w ", block height" h ", vertical or horizontal writing" direction ", ID of the block" selfID ", ID of parent block including the block. "UpperI
D ”, the attribute“ upperAtt ”of the parent block, and the reserve area“ reserve ”.

As shown in FIG. 9C, the character recognition information is "headeed" indicating that the character recognition information is the character recognition information.
The character recognition information “OCR1” having rJ, for example, for a single character such as “book”, and “blk” corresponding to the above “lectl” indicating a block including the character.
It is composed of combination information with "header".

Each character recognition information such as "OCR1" is "type" indicating whether it is a character or a blank.
e ”, the first to fifth candidate characters“ character 1 ”to“ character 5 ”according to the confidence level of the character recognition, the cutout positions“ x1 ”and“ y1 ”of the character, and the width“ w ”of the character. , The height of the character “h”, and the spare area “reserve”.

Next, the outline of the detailed operation of the image forming apparatus of the present invention will be described with reference to the flowchart of FIG.

When image data is input (step 1),
If the document direction determination unit (step 2) obtains the region separation information, and the document direction determination region separation unit determines that there is no region information, it can be determined from this result that the sheet is blank (step 3). When it is determined that the document is blank, the automatic document feeder 142 capable of reversal feeding shown in FIG. 1 is controlled to reverse the document (step 4). On the other hand, when it is determined that the blank sheet is not a blank sheet, printing is performed on the recording material. The character direction discriminating unit (step 5) again obtains the area separation information for the reversed original and determines whether or not it is a blank sheet (step 6). If it is a blank sheet, the recording material is not printed. (Step 7). If it is not a blank sheet, the recording material is printed (step 8). If both blank sheets are judged to be blank in the two blank sheet determinations, that is, if both sides of the document are blank sheets, the recording material is not printed.

[0043]

As described above, according to the present invention,
Read the image on one side of the original and print on one side of the recording material. In single-sided mode and when printing two originals on both sides of one recording material, in both-sided mode, set the front and back sides of the original when setting the original. There is an effect that it is possible to avoid the problem that the user of the apparatus obtains an unintended output when the wrong side, that is, the back side of the document, that is, the side without the image is read.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a block diagram of a controller unit in the image forming apparatus of the present invention.

FIG. 3 is a block diagram of an image processing unit in a controller unit in the image forming apparatus of the present invention.

FIG. 4 is a block diagram of a document orientation determination unit in FIG.

FIG. 5 is a flowchart showing a document orientation automatic discrimination and character recognition processing of the present invention.

FIG. 6 is a diagram showing a region separation state in automatic document orientation determination according to the present invention.

FIG. 7 is a diagram illustrating a process of character recognition processing.

FIG. 8 is a diagram for explaining a document (character) direction automatic determination process of the present invention.

FIG. 9 is a diagram showing a data format of area separation and character recognition information.

FIG. 10 is a flowchart showing a detailed operation of the image forming apparatus of the present invention.

[Explanation of symbols]

142 automatic document feeder 201 CPU 203 ROM 204 RAM

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/00 H04N 1/00 108K 5C072 1/04 106 1/04 106Z F term (reference) 2H027 DB01 DE02 ED11 EE07 EF06 2H076 BA14 BA42 BA55 BA71 BB10 3F048 AA01 AB02 BA06 EA11 3F100 AA03 BA06 DA00 5C062 AA05 AB02 AB30 AB32 AB41 AC04 AC07 AC09 AC11 AC58 AC71 BA00 5C072 AA05 BA20 NA01 NA07 RA01 RA05 RA06 UA13 WA02

Claims (2)

[Claims] 1. An automatic document feeder capable of reversing and feeding a document, a document direction discriminating means for discriminating a document direction from image data in the document, and whether the document is a blank sheet based on a result of the document direction discriminating means. An image forming apparatus comprising: a blank sheet determining unit for determining whether or not a blank sheet determining unit and a control unit for controlling an automatic document feeder based on a determination result of the blank sheet determining unit. 2. The image forming apparatus according to claim 1, wherein, when the result of the blank sheet determination means is a blank sheet, the control means inverts the document and the blank sheet determination means makes a blank sheet determination.