JP2002262041A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that monitors a state of an exposure lamp in the midst of original reading in the case other than a shading operation so as to cope with a fault. SOLUTION: In the case that originals are continuously carried by a sheet- through type automatic draft feeder, shading is executed for a 1st original to monitor an exposed lamp luminous quantity and even when no shading is performed for 2nd and succeeding originals, the exposed lamp luminous quantity is monitored and on the occurrence of a fault, an FGATE signal to capture original data is produced on the occurrence of the fault. Furthermore, shading data are updated only when the reference white board is read.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital copying machine,
The present invention relates to an image reading apparatus mounted on a scanner, a facsimile or the like, and more particularly, to an image reading apparatus having a function of monitoring a lighting state of an exposure lamp of the image reading apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 6, an image reading apparatus 1 such as a digital copier applies light from a light source including an exposure (fluorescent) lamp 3 to a document placed on a contact glass 2 in a first and a second direction. There is provided a device for irradiating the second carriages 4 and 5 while scanning them, forming an image of reflected light from an original image by a lens 6, and reading the image by an image sensor (CCD) 7. In such an apparatus, a reference white plate 8 set as a white reference is first read immediately before reading a document as a white to be a reference of image density when reading the document, and shading data (step 701) as shown in FIG. ) Is generated, and thereafter, the read image data and the shading data are calculated to perform shading correction (step 702), and thereafter, each image processing is performed and output. In FIG. 6, reference numeral 9 denotes an original scale, 10 denotes an SBU (Scanner Board Unit) on which the CCD 7 is mounted, and the first carriage 4 and the second carriage 5 are driven by a scanner motor 11. In this specification, the scanner refers to the first carriage 4 and the second carriage 5.

In reading an original, the exposure lamp 3 is turned on based on a start command of the scanner, and the first and fourth carriages 4 and 5 are driven at a preset speed. After the start of driving, first, as a timing for reading the reference white plate 8, a SHGATE signal is generated, and in synchronization with this, white data of the reference white plate (hereinafter also referred to as white plate data) is read, and the first carriage 4 is moved to the document reading start position. Upon arrival, an FGATE signal is generated, and the original data is read in synchronization with the FGATE signal. After reading the document, the first and second carriages 4 and 5 return to their original positions, and stop at the designated original positions.

[0004] Due to the above operation, even when shading data becomes abnormal due to some influence, a series of document reading and image processing are performed, and eventually, an abnormal image is output. is there. One of the causes of the shading abnormality is a problem of rising light quantity. That is, when a rare gas fluorescent lamp with a small light quantity fluctuation is used as a reading light source (exposure lamp 3),
If the lamp is not used for a long time, the rise time of the lamp light amount becomes longer than usual. For this reason, a state occurs in which the light amount has not yet risen when the white data is read at the reference white plate position. Further, in the case of being left in the dark, such a problem of the amount of light appears more remarkably.

On the other hand, this type of image reading apparatus is disclosed in Japanese Patent Application Laid-Open Nos. 10-2540074, 11-261816, 10-276325, and 10-200711. The invention made is known.

Japanese Patent Application Laid-Open No. Hei 10-254074 discloses an image reading apparatus using a fluorescent lamp as a document illumination lamp. Since the starting characteristics appear remarkably, the ordinary lamp O
It is disclosed that lighting is performed for a short time of about one second separately from the N trigger signal.

Japanese Unexamined Patent Application Publication No. 11-261816 discloses a vertical streak in an output image due to dust or dirt attached to a mirror or lens, dust or dirt attached to a reference white plate, or an image abnormality due to a defective image sensor. It is disclosed that a shading correction defect such as the following is prevented.

Japanese Patent Laid-Open No. Hei 10-276325 discloses a digital shading correction device capable of eliminating data that does not exist when the entire document is read and realizing a smooth gradation.

Further, Japanese Patent Application Laid-Open No. 10-200711 discloses a method for obtaining an image in which a density difference does not appear even when reading a document fixed on a document table or moving the document on the document table. The disclosed image reading device is disclosed.

[0010]

In the conventional example described above, a document fixed scanner is very effective. However, in a document moving (sheet-through) type reading apparatus having a high reading productivity, it is always effective. Since shading could not be performed for each document, it was not possible to detect an exposure lamp abnormality during reading.

Accordingly, a first object of the present invention is to provide an image reading apparatus capable of monitoring the state of an exposure lamp during reading of a document and responding to an abnormal condition, in addition to the shading operation.

In addition, in the above-described conventional example, an abnormality of the exposure lamp could be detected by detecting the density of the member on the side of conveying the original at the end of the original reading, other than the shading operation. However, with respect to the uniquely determined reference value for abnormality determination, variations in the density of the member that conveys the original, contamination of the member that conveys the original due to rubbing with the original, or a decrease in the light amount of the exposure lamp. In some cases, erroneous detection may occur due to a variation in read data of a member that conveys a document.

Accordingly, a second object of the present invention is to provide an image reading apparatus which is capable of detecting an exposure lamp abnormality corresponding to these variations.

[0014]

In order to achieve the above object, the present invention has a scanner mechanism which can operate along a document table, and fixes the scanner at a fixed position when reading a document (document). Scanning position), an original is moved by a sheet-through type automatic original feeding apparatus, an optical system for forming an image on an image sensor, and a reference white plate for shading correction are provided at positions other than the original reading position.
An optical system for causing a scanner to move to the reference white plate position during shading and forming an image of the reference white plate on the image sensor; and an A / D converter for converting an analog output of the image sensor into a digital signal. When the reference whiteboard data acquired during shading correction performed before reading the document does not satisfy the specified value, the document reading device determines that the exposure lamp is abnormal and does not process the document data. When a document is continuously fed by the automatic document feeder, a shading operation is performed on the first document to monitor the light intensity of the exposure lamp, and even when the second and subsequent sheets are not to be shaded, Monitor the light intensity of the exposure lamp, and do not generate an FGATE signal to capture the original data in the event of an error. It was.

In this case, the monitor of the light amount of the exposure lamp for the second and subsequent sheets generates a signal corresponding to the time interval between the sequentially sent originals, and performs the same operation as the shading operation based on this signal. The density of the member that conveys the document is read and monitored. At that time, a judgment reference value for the reading value of the reference white board and a judgment reference value for the detection density of the member that conveys the document are individually provided.
Signals are not generated, and updating of shading data is performed only when a reference white board is read, and data obtained by a shading operation performed between sheets is not updated as shading data.

Further, according to the present invention, the criterion value for the reading value of the reference white plate and the criterion value for the detected density of the member for transporting the document are set at the time of shipment from the factory. , And these values are stored as default values, and the reference value at the time of normal reading operation is automatically set to the reference white plate and the side for conveying the document every time the reading device is turned on. The determination reference value is set based on the detected value of the density of the member.

At this time, every time the power of the reading device is turned on, the density of the reference white plate and the member on the side for transporting the document are automatically detected and the determination reference value is set. In the state (open / closed), if the density value of the member on the side where the document is conveyed varies greatly, a value prepared as a default value is used as a reference determination value. Further, in an operation of intermittently performing shading for n-sheet reading in sheet-through reading, a transition of a reading value of a reference white plate is detected, and a determination reference value for a detected density of a member on the side of conveying a document is detected. Make corrections.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a diagram showing an image reading apparatus and a reading operation timing according to an embodiment of the present invention. It is an example equipped. In this embodiment, two types of reading operations, ie, original fixing and original moving, are possible. FIG. 2 is a functional block diagram showing a control system of the image reading apparatus according to the first embodiment of the present invention.
7 is a timing chart showing output timing of each signal when reading by sheet-through.

The image reading apparatus itself is the same as in FIG. However, the reading unit 12 is provided on the upstream side in the scanner movement direction for reading the image of the reference white plate 8, that is, on the left side in the figure, in order to read the document by sheet-through.

A sheet-through type automatic document feeder (hereinafter, referred to as ADF) 100 includes a document tray 101, a pickup roller 102, a transport drum 103, a transport roller 104, a paper discharge roller 105, and a paper discharge tray 106, and performs reading. It is attached to the upper surface of the device 1 so that it can be opened and closed. An original bundle before reading is placed on the original tray 101, and when the reading operation is started, the originals are picked up one by one from the upper surface of the original bundle by the pickup roller 102 and sent to the transport drum 103 side. A document is placed between a plurality of pairs of transport rollers 104,
And the conveying path 107 is sent to the reading unit 12 side, and is read by the reading unit.
The paper is discharged from a paper discharge roller 105 onto a paper discharge tray 106.

As shown in FIG. 2, the image reading device 1
Functionally, the image processing unit 201, the reading device unit 202,
And a sub-scan timing generator 203. The image processing unit 201 further includes a shading data generation / update unit 2011, a shading correction unit 2012, and an image data processing unit 2013. Further, the reading device section 202 is provided with a main scanning timing generation section 2021.

The state in which the original is fixed to the contact glass 2 is the same as that described with reference to FIG. In the following description, asserting means starting a process by raising a signal, and negating means terminating the process by restoring a rising signal. The fact that the read white board data is normal means that the 8-bit image data is 255 on the white side and 0 on the black side.
This is a value close to 5.

Upon receiving the reading start information, the sub-scanning timing generator 203 resets the abnormality flag, turns on the exposure lamp 3 for reading, and sets the scanner motor 1
1, the scanner (first and second carriages 4,
5) is driven. When the first carriage 4 reaches the position where the reference white plate 8 is read, the SLEAD signal is asserted. While the SLEAD signal is asserted, the scanner reads the white data of the reference white plate 8 area and
, The white data 2011 read from the reference white plate 8 is transmitted, and the generation of shading data starts.

When the first carriage 4 comes out of the area of the reference white board 8 and comes to a position where the SLEAD signal is negated, the SLEAD signal is negated, and the sub-scan timing generator 203 takes in the white board data. If the captured white board data indicates a value close to white, the image reading process is continued as it is. When the scanner (the first carriage 4) comes to a position where the document is read, the SSCAN signal is asserted and the normal reading is performed. continue processing. If the captured white board data indicates a value that is not close to white, the SSCAN signal (FGATE signal) is not generated so that the processing of reading the original data is not performed.
This prevents abnormal image data from flowing to the image processing unit 201 and prevents output of an abnormal image.

Further, if the white board data taken in as described above indicates a value that is not close to white and the abnormal flag is not set, that is, if the operation is to read the white board for the first time, the abnormal flag is set. To stop the scanner. Next, the scanner is returned to the home position before reading the reference white plate 8, and when the scanner returns to the home position, driving of the scanner is resumed. On the other hand, when the abnormality flag is set, that is, when the abnormality is detected in the first operation of reading the reference white plate 8 and the operation of reading the white plate again is performed, the abnormality is detected again. Since there is an error in the scanner, the scanner system is notified by notifying the user of a scanner system error notification and the scanner system is stopped.

If there is an error in the reference whiteboard data when the reference whiteboard data is read in this way, not only the reading of the original document is stopped, but also the reading process is performed again. The cause of the abnormality is clarified.

In the case of moving the original, the original is set on the original tray 101 of the ADF 100 and the reading is started.
First, in order to perform shading, the first carriage 4 is driven to read the reference white plate 8 and returns to the reading position 12 for sheet-through again. After returning, Document Tray 1
01 is conveyed, and the original is read at the reading position 12. Shading correction is performed on the read data.

FIG. 2 shows a signal flow. Upon receiving the reading start information, the sub-scanning timing generation unit 204 drives the scanner motor 11 and outputs an SLEAD signal in the reference whiteboard reading area to the reading unit 202.
In response to this assertion, a signal corresponding to the actual whiteboard reading position is output to the image processing unit 201 as SHGATE with line synchronization. The image processing unit 201 reads the density of the reference white board 8 in the SHGATE signal section and generates shading data. When the shading operation is completed, the scanner returns to the sheet-through reading position.

Next, the ADF 100 receives the document transport start information, and starts transporting the document set on the document tray 101. When the document reaches reading position 12
Output SSCAN signal. In the reading unit 202, the SSC
FGATE is output to the image processing unit 201 in line synchronization with the AN signal. The DFEND signal is negated when the trailing edge of the document has passed the reading position 12 after passing the document reading area. A * SHGT signal is generated for this edge and ANDed with SHGT. By doing this,
The reading unit 202 can detect the density of the member on the side where the document is conveyed until the next document (between the sheets) after the rear end of the document has passed. This member is constituted by a white transport drum or a guide plate (not shown, but a guide plate for bringing a document into close contact with a glass window at a reading position) and capable of sufficiently detecting the density. With such a control, an operation is performed as if a shading operation was performed just after the trailing edge of the document.
It only monitors the density of the member that conveys the document and does not update the shading data. In this control,
The signal is reset by the assertion of the SLEAD signal, a signal that performs a preset operation by the DFEND signal is generated, and the shading data is updated based on this signal.

The monitoring of the exposure lamp 3 for the first sheet is performed by a shading operation, and for the second and subsequent sheets, the document is conveyed as if the shading operation was performed just after the trailing edge of the document as described above. The state of the exposure lamp 3 is monitored by detecting the density of the member on the side. If the result of the monitoring indicates that there is an error, the ERROR information is passed to the sub-scan timing generator 203 and the ADF 100 so that the reading unit 202 does not output the SSCAN signal. As a result, it is possible to minimize the output of abnormal image data.

If a reference value for the reading value of the reference white plate 8 and a reference value for the detected density of the member (the above-described guide plate) on the side of transporting the original are individually provided, and one of them does not satisfy the reference, Do not generate the FGATE signal that captures the original data. At this time, since the density of the reference white plate 8 and the density of the guide plate are not necessarily the same, it is possible to determine an appropriate exposure lamp abnormality by providing a determination reference value for each of them in advance and making a determination for each.

Updating of the shading data is performed only when the reference white plate 8 is read, and data obtained by the shading operation performed between sheets is not updated as shading data. The light amount monitoring of the lamp 3 is performed by forcibly executing the shading operation. However, it is necessary to prohibit the use of the shading data generated by the shading operation for the second and subsequent sheets for correcting the document. As the control signal, a signal (or an information flag) for performing a preset operation by the assertion of the SLEAD signal and performing a preset operation by the DFEND signal is generated, and based on this, the shading data is updated and prohibited.

<Second Embodiment> This second embodiment is different from the first embodiment in that a reference value for the reading value of the reference white plate 8 and a member on the side for transporting the document (in the above embodiment, , The guide plate) is detected by detecting the density of each of the reference white plate 8 and the member on the side of conveying the original document at the time of shipment from the factory, storing these values as default values, and performing the normal reading operation. Is set based on a value obtained by detecting the density of the reference white plate 8 and the member that conveys the document each time the power of the reading apparatus 1 is turned on. Are configured in the same manner as in the first embodiment. Hereinafter, the same components will be described with the same reference numerals.

That is, as shown in FIG.
The default value of the whiteboard data is written in the nonvolatile RAM in advance in the shading data generation / update unit 2011 at the time of shipment from the factory. Then, in the case described below, the density determination is performed using the default value.

Also in this embodiment, in the above configuration, the monitoring of the exposure lamp 3 for the first sheet is performed by a shading operation, and for the second and subsequent sheets, the shading is performed as if the sheet passed the trailing edge of the original as described above. By performing the operation, the state of the exposure lamp is monitored by detecting the density of a member (for example, a guide plate) on the side that conveys the document.
The method of deriving the determination value of the detection value is as follows.
The same operation as the above-mentioned shading is performed as the operation for reading the density of the reference white board, and the density of the reference white plate is read. Further, the density of the member on the side for transporting the original at the sheet through reading position 12 is detected. From each of the data, a margin is provided on the data side on the black side to determine a determination reference value. These values are
The data is stored in the nonvolatile RAM of the shading data generation / update unit 2011. Therefore, when data on the black side is detected with respect to these values, a process of not taking in the document data is performed as a lamp abnormality.

Each time the power of the reading apparatus is turned on, the density of the reference white plate 8 and the member on the side for transporting the document are automatically detected and a determination reference value is set. When the ADF 100 is set (open / closed), the document is transported. In the case where the density value of the member on the side to be dispersed greatly varies, erroneous detection is prevented by using the value prepared as a default value at the time of factory shipment as the reference determination value. That is, when the power is turned on, the density of the reference white plate 8 and the density of the member on the side of transporting the original are detected. When the density of the reference white plate 8 and the density of the member on the side of transporting the original are detected, the ADF 100 is completely turned off. If it is in the closed state, it can take accurate values. However, if the document is slightly floating or is in an open state, the density of the member on the side of conveying the document cannot be detected. So, once,
If the result of detecting the density of the member that conveys the original exceeds the predetermined reference range from the judgment reference value that has the default value and is a black value as an abnormal value, When the density of the reference white plate 8 is detected first and a value equivalent to the previous value is detected, the exposure lamp 3
Is regarded as normal, and the value obtained by detecting the density of the member that conveys the preceding document is determined to be the setting failure of the ADF 100, and the determination reference value (data on the nonvolatile RAM) used until the previous time is used. . This makes it possible to prevent erroneous detection of the exposure lamp determination.

In an operation of intermittently performing shading for n-sheet reading in sheet-through reading, a change in the read value of the reference white plate 8 is detected, and the detected density is compared with the detected density of the member that conveys the document. When correcting the judgment reference value, when performing intermittent shading,
If the time of the intermittent operation is long, the density reading value of the member that conveys the document decreases due to a decrease in the light intensity of the lamp. In this case, as shown in FIG. 5, the amount of change between the reference white plate density value obtained at the time of the next shading and the previous density value is calculated (for example, calculated in%), and this change amount is calculated from the next original document. By correcting the density reading value of the member on the side that transports the image, the determination criterion can be accurately determined.

Other parts which are not particularly described are the same as those described in the first embodiment.
And the operation is the same.

[0040]

As described above, according to the present invention, when the reference whiteboard data obtained during shading correction performed before reading the original does not satisfy the specified value, it is determined that the exposure lamp is abnormal and the original data is determined. When a document is continuously transported by a sheet-through type automatic document feeder in a document reading apparatus that does not process the original document, a shading operation is performed on the first document to monitor the light intensity of the exposure lamp. Even when shading is not performed after the first sheet, the amount of the exposure lamp is monitored and the FGATE signal that captures the original data is not generated in the event of an abnormality. Can be detected, and the output of an abnormal image can be minimized.

Further, according to the present invention, the monitor of the exposure lamp light quantity for the second and subsequent sheets generates a signal corresponding to the interval between the sequentially sent originals, and performs shading operation based on this signal. By performing the same operation and monitoring by reading the density of the member that conveys the document, the reference whiteboard data capture at the time of shading and the data capture of the member that transports the document at the rear end of the document, This can be realized using the same shading function, and abnormality detection can always be performed at no cost.

According to the present invention, a judgment reference value for the reading value of the reference white board and a judgment reference value for the detection density of the member on the side of conveying the original are individually provided. , FGATE to capture original data
Since no signal is generated, an accurate determination can be made by separately providing the determination reference value of the reference whiteboard data and the determination reference value of the member that conveys the document.

Further, according to the present invention, the control means individually has a judgment reference value for a reading value of a reference white plate and a judgment reference value for a detection density of a member on the side of conveying a document.
If any one of the criteria is not satisfied, the document data is not captured, so that the reference whiteboard data capture during shading and the data capture of the member conveying the document can be realized using the same shading function. Abnormality detection is always possible without increasing the cost.

Further, according to the present invention, the judgment reference value for the reading value of the reference white plate and the judgment reference value for the detected density of the member for conveying the original are set at the time of shipment from the factory. The density of each member is detected, these values are stored as default values, and the reference value at the time of normal reading operation is automatically set to the reference white plate and the document every time the reading device is turned on. Since the determination reference value is set based on the value detected for the density of the member on the side to be conveyed, the determination is made based on the reference value including the variation factor of each apparatus, and thereby it is possible to accurately detect the abnormality of the exposure lamp. Thus, erroneous detection can be prevented.

Further, according to the present invention, when there is a large variation in the density value of the member that conveys the document during a normal reading operation, the value prepared as the default value is used as the determination reference value. Therefore, it is possible to prevent erroneous setting when determining the reference value, thereby making it possible to accurately detect the abnormality of the exposure lamp and prevent erroneous detection.

Further, according to the present invention, the reference value for the detected density of the member on the side of transporting the document is corrected from the transition of the read value of the reference white plate during a normal reading operation. It is possible to set a criterion value corresponding to a change with time, thereby making it possible to accurately detect an abnormality of the exposure lamp and prevent erroneous detection.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an entire image reading apparatus according to an embodiment of the present invention and a timing of reading a document.

FIG. 2 is a block diagram showing a schematic configuration of the image reading apparatus according to the first embodiment of the present invention and a signal output state;

FIG. 3 is a timing chart showing the output timing of the signal of FIG. 2;

FIG. 4 is a block diagram showing a schematic configuration of an image reading apparatus according to a second embodiment of the present invention, showing a signal output state;

FIG. 5 is a timing chart showing the output timing of the signal of FIG. 4;

FIG. 6 is a diagram illustrating a schematic configuration of a conventionally implemented image reading apparatus and a timing of reading a document.

FIG. 7 is an explanatory diagram showing a conventional data flow.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image reading device 3 exposure lamp 4 first carriage 5 second carriage 7 CCD 8 reference white plate 11 scanner motor 12 reading position 100 sheet-through automatic document feeder (ADF) 201 image processing unit 2011 shading data generation / update unit 2012 shading correction Unit 2013 image data processing unit 202 reading unit 2021 main scanning timing generation unit 203 sub-scanning timing generation unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B047 AA01 BA02 BB02 CA19 CB04 DA04 5C072 AA01 AA05 BA08 CA02 CA14 FB12 LA15 NA01 RA16 UA03 XA01 5C077 LL11 LL13 MM14 MM27 PP06 PP72 PQ22 SS01 TT06

Claims (7)

[Claims] 1. A scanner movable along a platen, a scanner fixed at a predetermined position, a function of moving and reading an original, and a reference white plate provided at a position different from the predetermined position for shading correction. An optical system having a function of reading the reference white plate by moving the scanner to the reference white plate position, and control means for controlling the scanner and performing shading correction based on the read data of the reference white plate,
In the image reading apparatus, when the document is continuously conveyed by the sheet-through type automatic document feeder, the control unit performs a shading operation on the first document to monitor the exposure lamp light amount. An image reading apparatus characterized in that the light quantity of an exposure lamp is monitored even when shading is not performed on the second and subsequent documents, and the document data is not taken in when an abnormality occurs. 2. The control device according to claim 1, wherein the control unit performs the same operation as the shading operation on the second and subsequent originals based on a signal generated in accordance with a time interval between the sequentially transmitted originals. 2. The document reading apparatus according to claim 1, wherein the density of the member on the side to be conveyed is read and the light amount of the exposure lamp is monitored. 3. The image reading apparatus according to claim 1, wherein the control unit updates the shading data only when a reference white plate is read. 4. A control device according to claim 1, wherein said control means individually has a judgment reference value for a reading value of a reference white plate and a judgment reference value for a detected density of a member on the side of conveying the document. 3. The image reading apparatus according to claim 2, wherein document data is not taken in. 5. A determination reference value for a reading value of a reference white plate and a determination reference value for a detected density of a member on the side of transporting a document are determined by determining the densities of the reference white plate and a member on the side of transporting the document at the time of factory shipment. Detected values are stored as default values, and the determination reference value at the time of a normal reading operation is the detected value of the density of the reference white plate and the member that conveys the document each time the power of the reading device is turned on. 5. The image reading device according to claim 4, wherein the determination reference value is set based on the following. 6. The method according to claim 1, wherein, when the density of the member on the side of transporting the document during the normal reading operation varies greatly, a value prepared as a default value is used as a determination reference value. The image reading device according to claim 5. 7. The image according to claim 5, wherein a judgment reference value for a detected density of a member on the side of conveying the document is corrected based on a transition of a reading value of the reference white plate during the normal reading operation. Reader.