JP2925622B2 - Document reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading apparatus such as a copying machine, and more particularly to detection of a document position shift.

[Conventional technology]

Generally, in a copying machine, a document is placed on a fixed glass plate (document placing table), and the entire plate is read by mechanically scanning the glass plate itself or a reading optical system. In general, a range in which an image is read by a reading optical system disposed below a glass plate is predetermined, and it is necessary to accurately position a document at a predetermined position on the glass plate so as not to deviate from the range. If the positioning is inaccurate, the image may protrude, shift, tilt, etc. on the copy.

[Problems to be solved by the invention]

By the way, in an image reading apparatus such as a copying machine, when reading an original image, the original image is read in order to adhere the original to the reading surface, prevent the original from moving during reading, and fix the background reflectance of the original reading surface. It is necessary to press a relatively heavy plate called a pressure plate against the back surface (upper side). In the actual manual document positioning operation, first lift the pressure plate from the reading surface,
A document is placed on the reading surface, the pressure plate is lowered, and the document is pressed against the document.

By the way, when the pressure plate is pressed against the original, the original often moves. However, in this case, since the document is not visible to the operator, the position of the document cannot be known unless the copy is actually taken, and when the document position is out of the normal range, the position of the document is shifted. A perfect copy is formed. The misalignment of the document is unlikely to occur if the pressure plate is pressed carefully, but if the paper quality of the document is tracing paper and there are fold marks, correct the raised portion by pressing the raised portion with the pressure plate. Sometimes the paper is easy to move and it is difficult to prevent misalignment.

In a copier equipped with an automatic document feeder called an ADF, this type of misalignment is unlikely to occur if automatic document feeding is performed. However, in the case of a cut or pasted document or a thick document, automatic feeding is not possible, so the document feeding device is opened, the document is placed on the glass plate, and the document feeding device is closed. The document position shift is liable to occur.

In view of the above, it is an object of the present invention to enable an operator to confirm the presence / absence of a document position abnormality without opening the document feeder even when the document feeder is closed.

[Means for solving the problem]

In order to solve the above problems, the present invention provides a transparent document table (100) on which a document is placed; a document table (603) for placing a document;
0) a document feeder (101) including a transport belt (609) and a transport mechanism (605 to 607) for feeding and pressing to an exposure position on the upper surface, and capable of being opened and closed with respect to the document table (100); A document reading device including image reading means (102 to 106) for optically reading the upper surface of the document mounting table (100) from the lower surface side: a means (610) for detecting opening and closing of the document feeding device (101); Means for detecting the presence or absence of a document on the document table (603) (6
02); position detecting means (621) for detecting the position (Xmin, Ymin) of the document on the document table (100); and the document feeder (101) is closed and there is no document on the document table (603) The position (Xmin, Ymin) of the document is detected via the position detecting means (621) in response to the start key being turned on at the time of (1), and the position (Xmin, Ymin) is compared with a preset value. Identification means (402; Steps 1 and 2-11 in FIG. 8) for discriminating the presence / absence of a document position abnormality and for reporting the abnormality when the position is abnormal.
~ 16); In addition, in order to facilitate understanding, in the parentheses, reference numerals or corresponding items of the corresponding elements of the embodiment shown in the drawings and described later are added for reference.

[Action]

According to the present invention, when the document feeder (101) is closed and there is no document on the document table (603), the start key is normally turned on when a manually placed document is placed on the document table (100). Yes, the image reading instruction. In such a case, as described above, there is a possibility that the original is misaligned on the original placing table (100), but the original placing table (100)
Is closed, so that the user cannot confirm it by himself.

At this time, in the image reading apparatus of the present invention, the identification means (402;
Steps 1, 2-11 to 16) in FIG.
The position (Xmin, Ymin) of the original is detected via
min, Ymin) is compared with a preset value to identify the presence / absence of a document position error, and to notify the user that the position is abnormal, so that the user can easily recognize the document position error.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

〔Example〕

FIG. 1 shows a structure of a mechanism of a digital copying machine of one type embodying the present invention. Referring to FIG. 1, an ADF (document feeding device) 101 is provided above a contact glass 100 serving as a document placing table. The ADF101 is configured to be openable and closable with respect to the copier main body.
The document can be positioned on the contact glass 100 by manual operation.

An optical scanning system is provided below the contact glass 100. Therefore, the original is placed on the contact glass 100 with the image side facing down. Exposure lamp 102 for optical scanning system
The surface of the original is exposed, and the reflected light from the original is transmitted through various mirrors 103 and lenses 104 to a CCD (image sensor) 1.
An image is formed on the reading surface 05. CCD105 has many read cells.
This is a one-dimensional reading device arranged in a row, and can read one line of image information in a main scanning direction (a direction perpendicular to the paper surface). The optical scanning system is reciprocally driven and scanned mechanically in the sub-scanning direction (horizontal direction in FIG. 1), and sequentially forms light images from different reading positions on the CCD 105. Therefore, the CCD 105 can read two-dimensional document image information on the contact glass 100.

The image information read by the CCD 105 is converted to an image processing device
After being input to 106 and undergoing various processing, the semiconductor laser 1
The signal is input to 07 as a modulation signal and converted into an optical signal. The light emitted from the semiconductor laser 107 is formed as a writing image on the surface of the photosensitive drum 113 via the polygon mirror 108, the lens 109, and the mirror 110.

The photosensitive drum 113 is made of an organic semiconductor and is responsive to laser light, and rotates clockwise in FIG. 1 when recording an image. Photoconductor drum
The surface of the main charger 111 receives the writing image after the surface is uniformly charged by the discharge of the main charger 111, so that the surface of the main charger 111 has a potential distribution corresponding to the density distribution of the writing image, that is, the static distribution. An electrostatic latent image is formed. This electrostatic latent image is visualized by toner attached when passing through the vicinity of the developing device 114. On the other hand, the transfer paper fed from the paper feed cassette 116 is fed onto the photosensitive drum 113, and overlaps the toner image formed on the photosensitive drum 113, and the transfer charger
By 115, the toner image is transferred onto the transfer paper. The transfer paper on which the toner image has been transferred is separated from the photosensitive drum 113, then conveyed, and discharged through the fixing device 117.

FIG. 2 shows a specific configuration of the mechanical unit of the ADF 101. This will be described with reference to FIG. Documents are stacked and placed on a document table 603. Paper feed port, ie, document table 60
A pinch roller 606 and a call roller 607 are arranged at the left end position of 3, and the leading end of the document is inserted between them. A document sensor 602 disposed at the paper feed port can detect whether a document is set at the paper feed port. When the call roller 607 is driven, the separation belt 604 is
Only one document separated by the separation roller 605 is sent out onto the contact glass 100 through the space between them. This document is further transported on the contact glass by the transport belt 609, and when the document reaches a predetermined reading position, the transport belt 609 stops and the document is positioned there. When the reading of the document image (copy operation) is completed, the next document is fed, and at the same time, the document that has been read by the driving of the conveyor belt 609 is automatically sent to a predetermined discharge path.

In FIG. 2, reference numeral 608 denotes a sensor for registration detection and document width detection, and 611 denotes a stop claw. Reference numeral 610 denotes a lift-up detection sensor for detecting whether the ADF is open or closed (whether the ADF is lifted).

In general, the transport belt of the ADF is white. In this example, however, it is necessary to optically identify the boundary between the original sheet on the contact glass 100 and the rear surface thereof.
Nine surfaces are colored with a special yellow paint.
However, since the light reflectance of the surface of the conveyance belt 609 is relatively large and does not greatly differ from the surface of the original (normal paper), in this example, by limiting the wavelength detected by the optical filter, the conveyance belt and the original are separated. It is easy to identify.

Further, in this example, since the CCD 105 for reading an image is commonly used for detecting the presence / absence of a document and the position of the document, it is necessary to insert and retreat the optical filter with respect to the optical path of the optical scanning system. The mechanism for that is shown in FIG.

Referring to FIG. 3, the optical filter 301 is blue-violet and has a characteristic of blocking light having a yellow wavelength. The filter 301 is mounted on the CCD 10 in an upright state as shown in FIG.
It is arranged in front of the detection surface of No. 5 and deviates from the optical path of the detection surface of the CCD 105 when defeated. A solenoid 301 and a spring 303 are coupled to the filter 301. By controlling the on / off of the bias of the solenoid 302, each part moves in the direction of the arrow in the drawing to turn on the insertion of the filter 301 into the optical path. / Off can be switched.

That is, when detecting the presence or absence of a document and the position of the document, the filter 301 is set up as shown in FIG.
5, the density difference (actually, the color difference) between the document and the background (transport belt) can be clearly identified. Further, when reading the original image, it is possible to prevent the filter 301 from adversely affecting the read image by tilting the filter 301.

FIG. 4 shows a schematic configuration of the image reading system. Referring to FIG. 4, the image information read by the CCD (105) passes through the image reading plate 401, is included in the image processing device 405, and is transmitted to the IPU.
(Image processing unit) 402, an optical control board 403 and a main control board 404 are applied to an LD control board 406. LD control board 40
6 energizes the semiconductor laser according to the input information.

FIG. 5 shows a specific configuration of the IPU 402 in FIG. Referring to FIG. 5, this unit includes 501, 502, 503, 50
There are various blocks, including 4 and 505. The configuration of the block 503 is shown in more detail in FIG.

Referring to Figure 6, this block, the document size detection circuit 6 2 1, the matrix circuit 6 2 2, line memory I / O
Control circuit 6 2 3, smoothing circuit 6 2 4, MTF correction circuit 6 2 5 etc. are provided. Smoothing circuit 6 2 4 and MT
For F correction circuit 6 2 5, a component provided in the image processing unit conventionally, specially new configuration does not have. However, the document size detection circuit 6 2 1 shown in FIG. 6 is a new circuit provided specially. The structure of this circuit is shown in detail in FIG.

The size detection circuit shown in FIG. 7 determines the position of the boundary between the document sheet and its background (that is, the conveyor belt 609) based on the image data read by the CCD 105 in the Y direction (main scanning direction) and the X direction (sub scanning direction). (Scanning direction). When performing this position detection, the optical filter 301 is inserted into the optical path, so that the density of the detected image data differs greatly between the original sheet and the background.
Therefore, the boundary position is detected by identifying the density difference.

More specifically, the image data input to the circuit of FIG. 7 shows a numerical value substantially proportional to the intensity of the incident light.
This is bit density data, and the numerical value is large for the document surface and small for the background. This image data is applied to the input terminal of group A of the digital comparator 701, and the threshold value RF is applied to the input terminal of group B by a system control unit (not shown). The threshold value RF is an intermediate value between a normal density value obtained by reading the document surface and a background density value.

Normally, when the scanning surface is scanned, data corresponding to the background area first appears in the image data, followed by data corresponding to the document area, and after the end of the document area, data corresponding to the background again appears. Appear. This applies to both the main scanning direction and the sub-scanning direction. For example, looking at the position of the sub-scanning axis passing near the center in the main scanning direction (the portion where the document exists), as the sub-scan progresses,
The level of the output terminal (A> B) of the comparator 701 changes to L (low level), H (high level), and L.

The detection of the boundary position is performed by the counters 703 to 706. Counters 703 and 704 for detecting the position in the sub-scanning direction
, A line synchronization signal Lsync appearing for each scanning line is applied as a counting pulse, and counters 705 and 706 for detecting the position in the main scanning direction receive a clock pulse CLK appearing at the timing of each pixel in the main scanning direction as a counting pulse. Applied. The counting period of the counters 703 and 704 is controlled by a signal output from the flip-flop 710.

That is, the flip-flop 710 sets the output of the comparator 701 in synchronization with the signal Yc that goes high only at the timing of scanning the central portion in the main scanning direction.
Is L in a portion where there is no original in the sub-scanning direction, and is H in a portion where the original exists. Therefore, the counter 703 whose counting is permitted by this signal counts Lsync from the scanning start position to the boundary between the background and the leading edge of the document, and outputs the starting position Xmin of the document in the sub-scanning direction. Further, the counter 704 to which the inverted signal of the flip-flop 710 is applied,
Since Lsync is counted during scanning from the leading edge to the trailing edge of the document, the length Xmax of the document is output.

On the other hand, in the boundary detection in the main scanning direction, it is necessary to perform detection after the position in the sub-scanning direction enters the area where the document exists, so the signal output from the flip-flop 710 is delayed by the delay circuit 711. Has been generated. In order to synchronize the signal with the main scanning start position, the flip-flop 712 sets the output signal of the delay circuit in synchronization with Lsync. The counter 705 counts from the time when the output of the flip-flop 712 is set to L to the time when the output of the comparator 701 becomes H (until detecting one end in the width direction of the document). Position of Ymin
The value of is output. Also, the flip-flop 713 is set at the same time when the counting of the counter 705 is permitted, and thereafter, when the position in the main scanning direction reaches one end of the document, the counter is set.
The counting of 706 is permitted, and counting is continued until the comparator 701 detects the background again, that is, until the other end of the document is reached. Accordingly, the counter 706 outputs a value Ymax corresponding to the length of the document area in the main scanning direction, that is, the width of the document.

When the count of the counter 706 is permitted, the flip-flop 716 is set, and when the output of the comparator 701 becomes L, the output of the gate 717 becomes H.
The output of 14 becomes H, the counting of the counter 705 is prohibited,
Also, since the flip-flop 713 is cleared and the counting of the counter 706 is prohibited, the counters 705 and 706 count only for one line in the main scanning direction.

The information on the position and size of the document obtained by the counters 703 to 706 is respectively supplied to the parallel / serial converter of the next stage.
After being latched at a predetermined timing by the 707, the XYS is synchronized with a predetermined clock pulse SZCLK in the form of serial data.
It is sent to the system control unit as an IZE signal.

The system control unit takes in the signal XYSIZE and uses it for controlling the entire copying machine. FIG. 8 shows a part of the processing of the system control unit. Hereinafter, the contents of the control will be described with reference to FIG.

In step 1 of FIG. 8, the signal output from the lift-up detection sensor 610 provided in the ADF 101 is checked to determine whether the state of the ADF 101 is open or closed. Do nothing in the "open" state. If it is "closed", proceed to step 2.

In step 2, the document sensor 602 provided on the ADF 101
Of the ADF 101 to determine whether or not a document is set on the document table 603 of the ADF 101. If there is no original and the start key (not shown) on the operation board is off, nothing is done. When a document is set on the document table 603, step 3 is executed.

In step 3, the optical filter 301 shown in FIG. 3 is raised and inserted into the optical path, and the optical scanning system is driven in that state, and the image reading surface, that is, the contact glass
The image reading of 100 is performed over the entire scanning range. At this time, information on the position and size of the document is detected by the document size detection circuit 601 described above, and the information is taken. Note that once step 3 is executed, the prescan executed flag is set, and this flag is retained until the copy process is executed or the ADF is opened / closed. However, if the flag is set, the prescan is executed. Since it is omitted, there is no possibility that unnecessary pre-scans are repeated many times.

In step 4, the presence or absence of the document is identified by using the position information of the document obtained by the reading in step 3. That is, since this step is executed when a document is set on the document table 603, it is considered that the operator is preparing for the next copy. Therefore, if a document is present on the contact glass 100 in this state, it may be considered that the document has been left behind. Actually, when the position information Xmin detected by the document size detection circuit 601 is equal to or smaller than a predetermined value, the document is identified as being on the contact glass, and it is detected that the document has been forgotten.

If it is determined in step 4 that the document has been forgotten, the process proceeds to step 5 where the lamp of display 1 (not shown) near the document table 603 on the ADF is turned on to notify the operator that the document has been forgotten. If the document is not forgotten, the process proceeds to step 6, where the lamp of display 1 is turned off.

In step 7, ON / OFF of the start key on the operation board is checked. When the operator presses the start key to start the copy operation, the process proceeds to step S8.

In step 8, it is checked again whether the original is left behind (similar to step 4). If it is detected in step 8 that the document has been forgotten, the lamp of the display 2 (not shown) located near the start key on the operation board of the copying machine main body is turned on to notify the operator of the misplacement of the document. . In this case, no copy process is performed.

If it is determined in step 8 that the original is not forgotten, the process proceeds to step 10. In step 10, the lamp of display 2 is turned off, the ADF 101 is instructed to start the automatic document feeding operation, and the copying process of the copying machine is started.

When the document is manually positioned on the contact glass 100, the document is not set on the document table 603 of the ADF. When the positioning of the document is completed and the operator presses the start key, the process proceeds from step 11 to step 12.

In step 12, the optical filter 301 shown in FIG. 3 is raised and inserted into the optical path, and the optical scanning system is driven in that state, and the image reading surface, that is, the contact glass
The image reading of 100 is performed over the entire scanning range. At this time, since the position and size information of the document is detected by the document size detection circuit 6 2 1 described above, taking in the information. That is, the same process as in step 3 is performed.

In steps 13 and 14, the position information Xmin and the boundary information of the boundary between the original and the background obtained in the processing in step 12 are respectively obtained.
Check Ymin. That is, in step 13, it is checked whether or not there is a value of Xmin of ± Δx with respect to the reference position of the starting end of the document in the sub-scanning direction. In step 14, ± Δy is relative to the reference position of one end of the document in the main scanning direction. Check if the value of Ymin is within the range.

As a result of the checks in steps 13 and 14, when it is confirmed that the document exists within the predetermined range, the process proceeds to step 15, where the lamp of display 3 is turned off and the copy process is started. In this case, the ADF 101 does not operate because the operation mode is the operation mode for manually positioning the original.

If any of steps 13 and 14 detects that the original position is out of the predetermined range, it is determined that the original position is misaligned, and the display 3 lamp on the operation board is turned on, and the original position deviation is detected. Alert the operator of the occurrence. The copy process does not start.

Therefore, in the mode for manually positioning the original, if the original position is deviated from the specified position due to the operator's own positioning error, wind pressure when closing the ADF, or force at the time of contact between the belt and the original, Anomalies are automatically detected and reported, so that a misaligned copy can be prevented from occurring, and the operator can check whether the original position is correct without opening the pressure plate (ADF). it can.

The information of the original size which is output from the document size detection circuit 6 2 1 (Xmax, Ymax) is the case of automatic selection of transfer sheet size according to the original size and the copy magnification (automatic paper selection mode) or document size This is used when the copy magnification is automatically selected according to the transfer paper size (automatic scaling mode).

〔The invention's effect〕

As described above, according to the present invention, with the ADF closed,
The operator can surely recognize whether or not the document has shifted from the predetermined reading position. Therefore especially AD
Under the condition in which the original is easy to move when closing the F, the frequency of occurrence of useless copies with displacement or the like is greatly reduced, and a great effect is obtained economically.

[Brief description of the drawings]

FIG. 1 is a front view showing the structure of a mechanism of a type of copying machine embodying the present invention. FIG. 2 is an enlarged vertical sectional view showing the configuration of the ADF in FIG. 1 in detail. FIG. 3 is a perspective view showing a filter provided in the optical scanning system of FIG. 1 and a mechanism for driving the filter. FIG. 4 is a block diagram showing the flow of an image signal, FIG. 5 is a block diagram showing the IPU of FIG. 4 in detail, FIG. 6 is a block diagram showing the block 503 of FIG. 5 in detail, and FIG. it is a block diagram showing a document size detection circuit 6 2 1 of FIG. 6 in detail. FIG. 8 is a flowchart showing a part of the processing of the system control unit for controlling the entire copying machine of FIG. 100: contact glass (document mounting table) 101: document feeder, 102: exposure lamp 103: mirror, 104: lens 105: image sensor (image reading means), 106: image processing device 301: optical filter, 302: solenoid 303: spring 6 2 1: document size detection circuit (position detection means) 602: document sensor, 603: document table 604: separation belts, 605: separation roller 606: pinch roller, 607: up roller 609: transport belt, 610: lift Up detection sensor 701: Digital comparator, 703 to 706: Counter 710, 712, 713, 716: Flip-flop

Claims (2)

(57) [Claims] 1. A transparent document table on which a document is placed; a document table on which the document is placed; a transport belt and a transport for feeding and pressing the document on the document table to an exposure position on the upper surface of the document table; In a document reading device including a mechanism and a document feeding device that can be opened and closed with respect to the document mounting table; and an image reading unit that optically reads the upper surface of the document mounting table from the lower surface side: opening and closing of the document feeding device Means for detecting the presence of a document on the document table; position detecting means for detecting the position of the document on the document table; and starting when the document feeder is closed and there is no document on the document table. In response to the turning on of the key, the position of the document is detected through the position detecting means, and the position is compared with a preset value to identify the presence or absence of a document position abnormality and to notify the user of the position abnormality when the position is abnormal. Identification means; Document reading apparatus comprising. A surface of the conveyor belt pressing the document against the document table has a light reflection characteristic different from that of the document; and a position detecting unit detects the surface of the conveyor belt on the image read by the image reading unit. 2. The document reading apparatus according to claim 1, wherein a position of a boundary between the document and the surface of the transport belt, which is caused by a difference from the light reflection characteristic of the document, is detected.