JP2925623B2 - 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 being left behind in a reading apparatus having an automatic document feeding mechanism.

2. Description of the Related Art Generally, in a copying machine, a document is placed on a fixed glass plate (document reading table), and the document is scanned mechanically by the glass plate itself or a reading optical system arranged below. Read the entire image. Usually, the original is positioned on the reading table manually.However, in a copier equipped with an automatic document feeder called ADF, a large number of originals are placed on the original If you start the copy operation,
Documents are sequentially fed out one by one, and each document is automatically positioned on a document reading table.

Also, in copiers equipped with ADF, irregular
In order to handle thick originals, book originals, and the like, manual positioning of originals is possible. In other words, the entire ADF is mounted on the top of the copier so that it can be opened and closed freely.
Open F to position the original. Also, in this case, in order to realize the same function as the normal pressure plate, the ADF is closed after positioning the document, and the document is pressed onto the document reading table by the ADF.

When the document is manually positioned, the document is not automatically ejected, so the operator needs to remove the document after copying is completed. If the next document is automatically fed by the ADF while the previous document remains on the reading table, the previous document is also transported to the paper discharge path by the ADF belt.
If the previous document is not normal paper (for example, thin paper, thick paper, cut and pasted paper, etc.), the document may be jammed in the mechanism and the document may be damaged.

To prevent this type of document from being damaged, when the document is manually positioned, it is checked whether the ADF is open or closed after copying, and before the ADF is opened, that is, the document is removed from the reading table. When the next original is set on the original platen on the ADF, a display warning that the original is left behind is activated.

[Problem to be Solved by the Invention] In the conventional apparatus, even if the previous document actually exists on the reading table, it may not be detected in some cases.
For example, if a document is placed on the document platen on the ADF and another document is manually positioned on the reading surface and copied,
If the user manually positions the document on the reading surface and forgets it without making a copy, the document on the reading surface cannot be detected.

For this reason, the conventional apparatus cannot reliably prevent damage due to misplacement of the original on the reading surface.

Therefore, in the present invention, even if a document is misplaced under any circumstances, it is reliably detected,
It is an object to prevent a document from being damaged.

[Means for solving the problem]

(1) A document reading apparatus according to the present invention includes: a transparent document reading table (100) on which a document is placed; an operation position for positioning a document on the document reading table; Automatic document feeding means (101) for feeding a document from a predetermined document table at an operation position and positioning the document at a predetermined position on the document reading table; determining whether the automatic document feeding means is at the operation position; Position detecting means for detecting (610); a platen document detecting means for detecting whether there is a document on the document table (602); image reading means for reading an image of a document on the document reading table (105); Reading platen document detecting means (601) for detecting the presence or absence of an upper document; detecting that the position detecting means is at the operation position;
When the detection of the presence of a document by the table document detecting means is simultaneously established, the detection of the presence or absence of a document on the document reading table by the reading sheet document detecting means is started. Document forgetting detection means (system control unit) for generating a forgetting signal; and means for displaying the document forgetting signal (display 1 and 2 lamps). 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.

(2) When the switch (start key) for instructing the image reading unit to start reading is operated when the document forgotten signal is not generated, the document forgotten document detecting unit is configured to output the document by the automatic document feeding unit. Feeding is started, and when the document forgetting signal is generated, the document feeding is suspended.

(3) The automatic document feeder feeds a document from a predetermined document table and positions the document at a predetermined position on the document reading table. The reading board document detecting means identifies a difference in light reflection characteristics between the document on the document reading board and the transport belt, and detects the presence or absence of a document.

[Action]

According to the above (1), when the automatic document feeder (101) is in the operation position and a document is set on the document table, the presence or absence of the document is detected by the reading platen document detector, and the document is detected. When there is, a document forget signal is generated and notified.

The misplacement of a document is identified by detecting the presence or absence of a document on the actual document reading table. Therefore, when the operator performs a special operation that is different from normal operation or when the main power supply is interrupted halfway, Also, the misplacement of the original is reliably detected.

According to the above (2), when the switch for instructing the start of reading of the image reading means is operated, if the forgotten document signal is generated, the document feeding is suspended, so that the document is reliably prevented from being damaged. .

According to the above (3), since the transport belt has a light reflection characteristic different from that of the original, if a predetermined position on the original reading table is read using, for example, an image sensor for reading and reading the original image, the original is placed at that position. Can be identified based on the density difference between the document and the conveyance belt.

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 (automatic document feeder) 101 is provided above a document reading table, that is, above a contact glass 100. The ADF 101 is configured to be openable and closable with respect to the main body of the copying machine. By opening the ADF 101, the original 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 mechanically reciprocally driven and scanned 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 is irradiated with 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, a 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 by the paper feed cassette 116 is fed onto the photosensitive drum 113, and overlaps with the toner image formed on the photosensitive drum 113.
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).

Generally, the transport belt of the ADF is white, but in this example, since it is necessary to optically identify the boundary between the original sheet on the contact glass 100 and the background, the transport belt 60 is used.
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. This filter 301
As shown in FIG. 3, the CCD 105 is placed in front of the detection surface of the CCD 105 in an upright state, and deviates from the optical path of the detection surface of the CCD 105 when tilted. 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 schematically shows the configuration of the image reading system. Referring to FIG. 4, image information read by the CCD (105) passes through an image reading 401, and includes an IPU (image processing unit) 402, an optical control plate 403, and a main control plate 404 included in the image processing device 405.
And applied to the LD control plate 406. The LD control plate 406 activates the semiconductor laser according to the input information.

FIG. 5 shows a specific configuration of the IPU 402 in FIG. Fifth
Referring to the figure, this unit is provided with various blocks including 501, 502, 503, 504 and 505. The configuration of the block 503 is shown in more detail in FIG.

Referring to FIG. 6, this block includes a document size detection circuit 601, a matrix circuit 602, a line memory I / O control circuit 603, a smoothing circuit 604, an MTF correction circuit 605, and the like. The smoothing circuit 604 and the MTF correction circuit 605 are components conventionally provided in the image processing unit, and do not have a special new configuration. However, the original size detection circuit 601 shown in FIG. 6 is a specially provided new circuit. 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 the value of the normal density obtained by calling the document surface and the value of the background density.

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 by the 707 at a predetermined timing, the XYS is synchronized with the predetermined crop 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, 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. Once step 3 is executed, the pre-scan execution completed flag is set. This flag is retained until the copy process is executed or the ADF is opened and closed, but if the flag is set, the pre-scan 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 whether the document has been forgotten is detected.

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, 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. 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, Xmin is within ± Δx with respect to the reference position of the starting end of the document in the sub-scanning direction.
In step 14, it is checked whether or not there is a value of Ymin within a range of ± Δy with respect to a reference position of one end of the document in the main scanning direction.

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 it is detected in any of steps 13 and 14 that the document position is out of the predetermined range, it is determined that there is a document position shift,
The lamp of display 3 on the operation board is turned on to warn the operator of the occurrence of the document position shift. 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.

Note that the document size information (Xmax, Ymax) output from the document size detection circuit 601 is used when the transfer paper size is automatically selected according to the document size and copy magnification (automatic paper selection mode) or when the document size and transfer It is used when the copy magnification is automatically selected according to the paper size (automatic scaling mode).

[Effects] As described above, according to the present invention, in an image reading apparatus such as a copier equipped with an ADF, if a document is left behind when the document is manually positioned, the notification is made and the next document is automatically set. Since the feeding is prevented, the misplaced document can be prevented from being damaged. The misplacement of a document is identified by detecting the presence or absence of the document on the actual reading table (contact glass). Therefore, when the operator performs a special operation that is different from the normal operation or when the main power supply is interrupted halfway. However, it is possible to reliably detect the misplacement of the original.

[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. FIG. 7 is a block diagram showing a document size detection circuit 601 in 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 reading means) 101: automatic document feeder (automatic document feeding means) 102: exposure lamp, 103: mirror 104: lens 105: image sensor (image reading means) 106: image processing device, 301: Optical filter 302: Solenoid, 303: Spring 601: Document size detection circuit (document detection means) 602: Document sensor, 603: Document table 604: Separation belt, 605: Separation roller 606: Pinch roller, 607: Caller roller 609: Conveyor belt 610: Lift-up detection sensor 701: Digital comparator 703-706: Counter 710, 712, 713, 716: Flip-flop

Claims (3)

(57) [Claims] A transparent document reading table on which a document is placed; an operation position for positioning the document on the document reading table; and a retractable position, which is configured to be openable and closable or advanceable and retractable. Automatic document feeding means for feeding a document and positioning the document at a predetermined position on the document reading table; position detecting means for detecting whether the automatic document feeding means is in the operating position; Document reading means for reading an image of a document on the document reading board; reading board document detecting means for detecting the presence of a document on the document reading board; operation of the position detecting means When the detection of the presence of the document and the detection of the presence of the document by the placing table document detecting means are simultaneously established, the detection of the presence or absence of the document on the document reading table by the reading table document detecting means is started, and the reading table document detecting means is started. Upon detection of the original chromatic, it generates an original forgetting signal, the original forgetting detection means; and means for notifying the original forgetting signal; document reading device comprising a. 2. The automatic document feeder according to claim 1, wherein the switch for instructing the image reading unit to start reading is operated when the document forgetting signal is not generated. 2. The document reading apparatus according to claim 1, wherein the document feeding is suspended when the document forgetting signal is generated. 3. A conveyance belt having a light reflection characteristic different from that of a document for feeding a document from a predetermined document table and positioning the document at a predetermined position on the document reading table. The document according to claim 1, wherein the document detection unit detects a difference in light reflection characteristics between the document on the document reading table and the transport belt to detect the presence or absence of the document. 4. Reader.