JP7192495B2 - Image reading system, image reading method, and computer program. - Google Patents

Description

The present disclosure relates to an image reading system, an image reading method, and a computer program.

As image reading systems, a flatbed (FB) type image reading system and an automatic document feeder (ADF) type image reading system are known.

There is also known a digital copier that automatically changes the compression rate of the read image data to a compression rate that is one step higher and reads the document again when an overflow occurs in the memory that stores the read image data. (See Patent Document 1, for example).

JP-A-8-65474

However, with the technique of changing the compression rate step by step and re-reading each time a memory overflow occurs, there is a possibility that the overflow cannot be resolved without re-reading a plurality of times.

An automatic document feeder (ADF) type image reading system repeats the operation of reading the document in the main scanning direction while conveying the document in the sub-scanning direction, thereby reading the entire document. Therefore, in the ADF type image reading system, it is possible to read a document that is longer in the sub-scanning direction than a standard size document such as A4.

However, when the length of the document to be read in the sub-scanning direction deviates greatly from the standard size, the amount of read image data that can be reduced even by changing the compression ratio by one step is not sufficient. , a memory overflow may occur.

Therefore, according to one aspect of the present disclosure, it is desirable to provide a technique that enables appropriate re-reading of a document according to the length of the document.

According to one aspect of the present disclosure, an image reading system is provided. The image reading system includes a reading section, a conveying section, a control section, and a storage section. The reading unit is configured to read a document in a first direction. The transport unit is configured to transport the document in a second direction that intersects with the first direction.

The control unit is configured to perform processing for controlling the reading unit and the transport unit. The processing is to cause the reading unit to repeatedly perform the reading operation of reading the document in the first direction and generating the read image data of the document while causing the conveying unit to perform the conveying operation of conveying the document in the second direction. include. The storage unit is configured to sequentially store read image data generated for each reading operation.

Specifically, the control unit executes a first control process of controlling the reading unit and the conveying unit so that the document is read under the first reading conditions. The control unit further determines whether the total amount of read image data stored in the storage unit during the execution process of the first control process exceeds the threshold.

Further, on condition that it is determined that the total amount exceeds the threshold value, the control unit stops the first control process and causes the transport unit to execute the operation of discharging the document. The control unit further determines the length of the document in the second direction based on the amount of the document transported by the transport unit during the discharge operation.

Further, the control unit determines that the total amount of read image data when reading of the document is completed is equal to or less than the upper limit of data amount based on the determined length and the upper limit of data amount corresponding to the total amount of read image data that can be stored in the storage unit. A second reading condition that fits is determined.

The control unit further executes a second control process of controlling the reading unit and the conveying unit so that the document is read under the determined second reading conditions.

According to one aspect of the present disclosure, as described above, the length of the document in the second direction is determined based on the amount of transport of the document by the transport unit during the ejection operation. Then, a second reading condition is determined based on the determined length. Therefore, it is possible to appropriately change the reading conditions according to the length of the document and re-read the document.

According to one aspect of the present disclosure, an image reading method may be provided. The image reading method comprises a reading process of repeatedly executing a reading operation of reading a document in a first direction and generating read image data of the document while conveying the document in a second direction intersecting the first direction, It includes executing to read the document under the first reading condition.

The method further includes sequentially storing read image data generated for each reading operation in the storage unit. The method further includes determining whether the total amount of scanned image data in storage exceeds a threshold.

The method further includes aborting the reading process and ejecting the document upon determining that the total amount exceeds the threshold. The method further includes determining the length of the document in the second direction based on the amount of document transport during ejection.

Further, the above method further determines that the total amount of read image data when reading of the document is completed is equal to or less than the upper limit of data amount based on the determined length and the upper limit of data amount corresponding to the total amount of read image data that can be stored in the storage unit. Determining a second read condition that fits.

The method further includes re-performing the reading process to read the document under the determined second reading conditions. According to this image reading method, it is possible to appropriately change the reading conditions according to the length of the document and to read the document again.

According to one aspect of the disclosure, a computer program product may be provided. The computer program is processing including controlling the reading unit and the conveying unit, and reads the original in the first direction while causing the conveying unit to carry out the conveying operation of conveying the original in the second direction. a reading operation for generating the read image data is repeatedly executed by the reading unit so that the document is read under the first reading condition; sequentially storing, determining whether the total amount of read image data stored in the storage unit has exceeded the threshold, and, on the condition that it is determined that the total amount has exceeded the threshold, stopping the processing and executing the document ejection operation, determining the length of the document in the second direction based on the amount of document transport by the transport unit during the ejection operation, and storing the determined length in the storage unit. determining a second reading condition under which the total amount of read image data when reading of the document is completed is less than or equal to the data amount upper limit, based on the data amount upper limit corresponding to the total amount of read image data; It may be configured to cause the computer to re-execute the process so that the document is read under the two reading conditions.

This computer program has the same effect as the image reading system and image reading method described above.

1 is a cross-sectional view showing a schematic configuration of an image reading system; FIG. 2 is a schematic block diagram showing the electrical configuration of the image reading system; FIG. 4 is a flowchart showing document reading processing (part 1) executed by the main unit; 9 is a flow chart showing document reading processing (part 2) executed by the main unit;

Exemplary embodiments of the present disclosure are described below with reference to the drawings.
The image reading system 1 of this embodiment shown in FIG. 1 is configured as an automatic document feeder (ADF) type scanner device.

This image reading system 1 includes a document tray 10 and a discharge tray 15 . A document Q to be read is transported from the document tray 10 toward the discharge tray 15 in the sub-scanning direction. The image reading system 1 includes two line sensors 20 facing each other on the transport path of the document Q between the document tray 10 and the discharge tray 15 for double-sided reading. A document Q transported from the document tray 10 is read by these line sensors 20 in the main scanning direction orthogonal to the sub-scanning direction, and then discharged to the discharge tray 15 .

The image reading system 1 includes a separating mechanism 30 and a conveying mechanism 40 to convey the document Q. As shown in FIG. The separation mechanism 30 has a separation roller 31 and a reverse roller 32 at the lower end of the document tray 10 .

The separation roller 31 rotates by receiving power from the first motor 51 through the transmission mechanism 52 (see FIG. 2). The transmission mechanism 52 rotates the separation roller 31 in the direction in which the document Q is conveyed downstream in the sub-scanning direction when the first motor 51 rotates forward. By this rotation, the separation roller 31 separates the lowermost document Q placed on the document tray 10 and in contact with the separation roller 31, and conveys it downstream.

The reverse roller 32 is provided to face the separation roller 31, and rotates following the separation roller 31 when the separation roller 31 conveys the document Q downstream. The reverse roller 32 receives power from the second motor 55 through the transmission mechanism 56 (see FIG. 2) and rotates in the direction of retracting the document Q when the document Q needs to be retracted. At this time, the separation roller 31 is driven to rotate by the reverse roller 32 .

The transport mechanism 40 is arranged downstream of the separation mechanism 30 . The conveying mechanism 40 includes a conveying roller 41 and a driven roller 42 as a first roller pair, and a discharge roller 45 and a driven roller 46 as a second roller pair. These roller pairs are provided on the transport path of the document Q, and rotate to transport the document Q from the upstream to the downstream.

The transport roller 41 and the discharge roller 45 are rotated by receiving power from the second motor 55 through the transmission mechanism 56 when transporting the document Q downstream. When the second motor 55 rotates forward, the transmission mechanism 56 transmits power to the transport roller 41 and the paper discharge roller 45 to move the transport roller 41 and the paper discharge roller 45 in the direction in which the document Q is conveyed downstream in the sub-scanning direction. Roller 45 is rotated. When the second motor 55 rotates in the reverse direction, the transmission mechanism 56 transmits power to the reverse roller 32 to rotate the reverse roller 32 in the direction in which the document Q moves backward.

The two line sensors 20 are provided so as to face the transport path between the transport roller 41 and the discharge roller 45 in order to read both sides of the document Q transported by the transport mechanism 40 . These line sensors 20 are configured as CIS image sensors, for example.

The image reading system 1 further includes a plurality of sensors FS and RS for detecting the document Q on the transport path of the document Q between the document tray 10 and the discharge tray 15 . Specifically, the image reading system 1 includes a sensor FS for detecting the document Q placed on the document tray 10 at the lower end of the document tray 10 . Below, this sensor FS is expressed as a front sensor FS.

The image reading system 1 further includes a sensor RS for detecting the document Q from the document tray 10 downstream of the front sensor FS in the sub-scanning direction. Below, sensor RS is expressed as rear sensor RS.

According to FIG. 1, the rear sensor RS is provided at a point upstream of the conveying roller 41 in the sub-scanning direction, and detects the document Q passing through this point. As another example, the rear sensor RS may be provided at a point downstream of the transport roller 41 in the sub-scanning direction and upstream of the reading point of the document Q by the line sensor 20, and detects the document Q passing through this point. You may The rear sensors RS may be provided at a plurality of locations downstream of the front sensors FS in the sub-scanning direction.

The front sensor FS and the rear sensor RS output an ON signal when the document Q exists at the corresponding point, and output an OFF signal when the document Q does not exist.

As shown in FIG. 2 , the image reading system 1 further includes a main unit 60 , a reading control unit 70 , a motor control unit 80 , a user interface 90 and a communication interface 95 . The main unit 60 functions as a control section that controls the entire image reading system 1 .

The main unit 60 includes a CPU 61 , ROM 63 , RAM 65 and NVRAM 67 . CPU 61 executes processing according to a computer program stored in ROM 63 .

The RAM 65 is used as a work area when the CPU 61 executes processing. The NVRAM 67 is an electrically rewritable non-volatile memory and stores setting data and the like. Integrated control by main unit 60 is realized by CPU 61 executing processing according to a computer program stored in ROM 63 .

For example, when a reading command is input, the main unit 60 starts scanning processing in accordance with a computer program, separates the documents Q placed on the document tray 10 one by one, and reads the separated documents Q. control.

Specifically, the main unit 60 executes the document reading process (see FIG. 3) for each document Q until the document Q placed on the document tray 10 runs out, and reads each document Q. .

A read command is input from the user via the user interface 90 or from the external device 3 via the communication interface 95 . The user interface 90 is, for example, a touch panel display.

In the document reading process, the main unit 60 causes the transport mechanism 40 to transport the document Q in the sub-scanning direction, and causes the line sensor 20 to read the document Q in the main scanning direction line by line in line with the transport operation. It controls the reading control unit 70 and the motor control unit 80 to make it run.

The reading control unit 70 drives and controls the line sensor 20 based on a command from the main unit 60 so that the line sensor 20 performs the reading operation for each line in accordance with the document Q transport operation. The reading control unit 70 sequentially inputs the read image data for each line generated by the reading operation of the line sensor 20 to the main unit 60 . The read image data of each line represents the read image of the corresponding line in the document Q. FIG.

The motor control unit 80 controls the driving of the first motor 51 and the second motor 55 based on commands from the main unit 60 , thereby controlling the transport of the document Q from the document tray 10 to the discharge tray 15 . The first motor 51 and the second motor 55 provided in the image reading system 1 in this embodiment are stepping motors.

The main unit 60 sequentially stores the read image data for each line generated by the reading operation of the line sensor 20 in the RAM 65 . When the read image data for one page is stored in the RAM 65, the main unit 60 generates page image data in which the read image data for one page is collected, retrieves the page image data from the RAM 65, to the external device 3 via the

Next, the details of the document reading process executed by the main unit 60 for each document Q will be described with reference to FIGS. 3 and 4. FIG. When the document reading process is started, the main unit 60 sets the values of operation parameters related to document reading to values corresponding to the reading conditions specified by the reading command source (S110). That is, the main unit 60 sets operation parameters so that the document Q can be read under the designated reading conditions.

An operation parameter is a parameter that defines a processing operation related to document reading. The reading conditions include compression ratio, resolution, color, number of gradations, number of reading surfaces, and skew correction. Compression rate means the compression rate of image data. Resolution is defined by the number of pixels per unit length (DPI) in the main scanning direction and sub-scanning direction.

The color condition designates the presence or absence of color, in other words, either monochrome reading or color reading. However, it should be understood that "monochrome" as used herein includes monochrome two-gradation and grayscale. The number of gradations means the number of gradations per pixel. The condition regarding the number of reading sides specifies either single-sided reading (ie, number of reading sides 1) or double-sided reading (ie, number of reading sides 2).

After executing the process of S110, the main unit 60 sets the number of steps N to zero (S120). Further, the main unit 60 causes the motor control unit 80 to drive the first motor 51 and the second motor 55 so that the leading edge of the document Q to be read moves to the reading point of the line sensor 20, thereby causing the separation mechanism 30 to move. Then, the transport mechanism 40 is driven to cause the separation mechanism 30 and the transport mechanism 40 to transport the document Q downstream in the sub-scanning direction (S130).

After that, the main unit 60 waits until the input signal from the rear sensor RS switches from the OFF signal to the ON signal (S140) when the leading edge of the document Q passes the document detection point by the rear sensor RS. When the input signal switches from the OFF signal to the ON signal (Yes in S140), the step number N is started to count up (S150).

Specifically, the main unit 60 monitors the rotation of the second motor 55, which is a stepping motor, through the motor control unit 80, and detects the rotation of the second motor 55 after the input signal from the rear sensor RS switches from the off signal to the on signal. , a process of counting up the number of steps N according to the rotation of the second motor 55 is started (S150).

Further, the main unit 60 starts reading control processing when the leading edge of the document Q reaches the reading point of the line sensor 20 (S160). In the reading control process (S160), the main unit 60 causes the conveying mechanism 40 to carry out the conveying operation of conveying the document Q in the sub-scanning direction so that the document Q can be read under the reading conditions according to the operation parameters. The line sensor 20 is caused to repeatedly perform the reading operation of reading the document Q.

Specifically, the main unit 60 controls the transport mechanism 40 through the motor control unit 80 so that the document Q is transported at a constant speed in the sub-scanning direction at a speed corresponding to the sub-scanning direction resolution.

Further, the main unit 60 causes the line sensor 20 to read the document Q in the main scanning direction each time the document Q is transported by a distance corresponding to the resolution in the sub-scanning direction in the process of transporting the document by the transport mechanism 40 . , the line sensor 20 is controlled through the reading control unit 70 so as to cause the line sensor 20 to generate read image data corresponding to the resolution in the main scanning direction.

The main unit 60 further acquires the read image data generated by the line sensor 20 line by line through the read control unit 70 and stores them in the RAM 65 sequentially. The read image data generated by the line sensor 20 is input to the main unit 60 after being compressed at a specified compression ratio in the reading control unit 70 .

More specifically, the reading control process (S160) causes the two line sensors 20 to perform the reading operation when double-sided reading is designated as the reading condition. When single-sided reading is designated as the reading condition, one of the two line sensors 20 facing the reading target surface of the document Q is caused to perform the reading operation.

When color reading is specified as a color condition, the main unit 60 causes the line sensor 20 to read each color of red (R), green (G), and blue (B) as a reading operation in the main scanning direction. By executing the operation, color read image data that conforms to the reading conditions is acquired from the line sensor 20 through the reading control unit 70 .

When monochrome reading is specified as a color condition, the main unit 60 causes the line sensor 20 to read a single color, specifically green (G), as a reading operation in the main scanning direction. Monochromatic read image data is obtained from the sensor 20 through the reading control unit 70 . The read image data generated by the line sensor 20 is converted by the reading control unit 70 into monochrome read image data that conforms to the reading conditions, and is input to the main unit 60 .

The reading control process described above is continuously executed at least until the input signal from the rear sensor RS is switched to an OFF signal or until the reading stop condition is satisfied. During execution of the reading control process, the main unit 60 sequentially stores in the RAM 65 read image data for each line generated by repeated reading operations of the line sensor 20 .

After starting the reading control process, the main unit 60 repeatedly determines whether or not the input signal from the rear sensor RS has switched from the ON signal to the OFF signal (S170). The main unit 60 makes a negative determination in S170 when the input signal from the rear sensor RS is maintained as an ON signal. After that, it is determined whether or not the reading stop condition is satisfied (S180). The reading stop condition is set to stop the reading operation when the area of the RAM 65 for storing the read image data is likely to run short.

Specifically, when the total amount of read image data to be stored in the RAM 65 input from the line sensor 20 through the reading control unit 70 exceeds a predetermined threshold value M, the main unit 60 determines that the reading stop condition has been satisfied. (Yes in S180).

The threshold value M is set, for example, to a value that is smaller than the storage capacity of the read image data by a margin amount. The storage capacity referred to here is the size of the storage area of the read image data in the RAM 65 . That is, the threshold value M is set to a value smaller than the total amount of read image data that can be stored in the RAM 65 by a predetermined amount.

In S180, the main unit 60 may calculate the total amount of read image data based on the amount of transport of the document Q from the start of reading. That is, the main unit 60 may substitute the number of rotation steps of the second motor 55 from the start of the reading control process into a predetermined formula to calculate the total amount of read image data corresponding to the number of rotation steps. Then, when the calculated total amount exceeds the threshold value M, it may be determined that the reading stop condition is satisfied. The amount of read image data per line can be specified from the reading conditions. Furthermore, the number of reading lines can be specified from the number of rotation steps. Therefore, the above formula can be specified from the reading conditions.

As yet another example, the main unit 60 determines whether the reading stop condition is satisfied by determining whether the number of rotation steps of the second motor 55 from the start of the reading control process exceeds the threshold value. may That is, the reading stop condition may be that the number of rotation steps of the second motor 55 after the start of the reading control process exceeds the threshold value. The threshold value may be set to a value according to reading conditions.

When the main unit 60 determines that the reading stop condition is not satisfied (No in S180), the process proceeds to S170. Then, if the input signal from the rear sensor RS is switched to an OFF signal without satisfying the reading stop condition (Yes in S170), the reading control process is terminated as soon as the reading operation up to the trailing edge of the document Q is completed ( S190), and after causing the conveying mechanism 40 to execute the operation of discharging the document Q (S195), the document reading process is terminated.

In addition, when the main unit 60 determines that the reading stop condition is satisfied (Yes in S180), the main unit 60 stops document reading (S200). Specifically, the main unit 60 stops the reading control process, thereby stopping the reading operation by the line sensor 20, and further discards the read image data stored in the RAM 65 so far. However, the count-up operation for the number of steps N is not stopped.

After that, the main unit 60 drives the transport mechanism 40 through the motor control unit 80 so that the transport mechanism 40 discharges the document Q to the discharge tray 15 (S210). Even during the discharge operation by the transport mechanism 40, the count-up operation of the number of steps N is continued.

During the ejection operation, before the ejection of the document Q is completed, the trailing edge of the document Q passes the document detection point by the rear sensor RS, and the input signal from the rear sensor RS switches from the ON signal to the OFF signal.

After causing the transport mechanism 40 to start the discharge operation (S210), the main unit 60 waits until the input signal from the rear sensor RS switches from the ON signal to the OFF signal (S220). Then, when the input signal from the rear sensor RS switches from the ON signal to the OFF signal (Yes in S220), the document length L is calculated based on the number of steps N at the time of switching to the OFF signal (S230).

The document length L is the length of the document Q in the sub-scanning direction. The document length L can be calculated by multiplying the number of steps N by the document transport amount D per step (L=D·N). After calculating the document length L (S230), the main unit 60 determines rereading conditions (S240).

The re-reading condition is determined in consideration of the document length L so as not to cause a reading stop event when re-reading the same document Q. FIG. Specifically, the rereading conditions are determined by partially changing the current reading conditions.

When the reading width in the main scanning direction is W (millimeters), the total amount Z (bytes) of the read image data when reading the entire document Q whose document length is L (millimeters) is expressed by the following equation.
Z=A.C.(K/8).(W.Rx/25.4).(L.Ry/25.4).EN

The parameter A in the above formula represents the number of sides to be read, and is A=1 for single-sided reading and A=2 for double-sided reading. The parameter C represents the number of colors, C=3 for color reading, and C=1 for monochrome reading.

The parameter K represents the number of bits per pixel per color, in other words, the number of gradations per pixel per color in bit units. When there are 256 gradations, K=8. The parameter Rx represents the main scanning direction resolution (DPI) and the parameter Ry represents the sub scanning direction resolution (DPI).

A parameter EN represents the compression ratio of the image data. EN=1 when the compression rate is 100%, ie, no compression. As can be seen from the fact that 1 inch is 25.4 millimeters, the value 25.4 in the above equation acts to replace the resolutions Rx, Ry with pixels per millimeter.

The reread conditions can be determined by changing one or more of the parameters A, C, K, Rx, Ry, EN in the above equation from the current read conditions. A plurality of methods for determining the rereading condition in S240 will be described below. The example described below is an example of a rereading condition determination method based on the premise that the upper limit of the total amount of read image data for which the reading stop condition is not satisfied is M (bytes).

[First example]
In the first example, the reread condition is determined by changing the compression ratio EN.

In order to read the document Q again so that the reading stop condition is not satisfied, the compression rate EN should be obtained so that the total amount Z of the read image data when the entire document Q is read is equal to or less than the value M. Therefore, the rereading condition is a selectable compression It is determined by maximizing the rate EN.

That is, in the first example, fixed value B1=A·C·(K/8)·(W·Rx/25.4)·(L·Ry/25.4) according to fixed value M and current reading conditions. On the other hand, the maximum value of the compression rate EN that satisfies the conditional expression EN≤M/B1 is obtained. The changed reading conditions when the current reading conditions are changed so as to change the compression ratio EN to the obtained maximum value are determined as the re-reading conditions.

[Second example]
In the second example, re-reading conditions are determined by changing the resolution Rx in the main scanning direction and the resolution Ry in the sub-scanning direction. Specifically, the maximum selectable main component that satisfies the conditional expression M≧A·C·(K/8)·(W·Rx/25.4)·(L·Ry/25.4)·EN Re-reading conditions are determined by obtaining a combination of scanning direction resolution Rx and sub-scanning direction resolution Ry.

The minimum value of the resolution Rx in the main scanning direction that can be realized by the image reading system 1 is Rx0, and the minimum value of the resolution Ry in the sub-scanning direction is Ry0. In an environment where Ry is the lowest value Rx0 and H times Ry0 (where H is an integer greater than or equal to 1), a fixed value M and a fixed value B2 according to the current reading conditions = A·C·(K/8)·(W· Rx0/25.4)*(L*Ry0/25.4)*EN, the reread condition can be determined by finding the maximum value of the parameter H that satisfies the conditional expression H≤M/B2. .

That is, in the second example, the maximum value of the parameter H that satisfies the conditional expression H≤M/B2 is used to change the main scanning direction resolution Rx to H·Rx0 and the sub scanning direction resolution Ry to H·Ry0. , the changed reading conditions when the current reading conditions are changed are determined as re-reading conditions.

[Third example]
In the third example, when the current reading condition specifies color reading, the rereading condition is determined by changing color reading to monochrome reading and further changing the compression rate EN as necessary.

Specifically, when the number of colors C is changed from C=3 to C=1, the total amount of read image data Z=A·(K/8)·(W·Rx/25.4)·(L • Ry/25.4) • When EN is equal to or less than the value M, the current reading conditions are changed so as to change to monochrome reading, and re-reading conditions are determined.

When the calculated total amount Z exceeds the value M, the conditional expression M≧A·C·(K/8)·(W·Rx/25.4)·( The reread condition is determined by obtaining the maximum value of the compression rate EN that satisfies L·Ry/25.4)·EN.

That is, the current reading conditions are changed so that the compression rate EN is changed to the maximum value of the compression rate EN that satisfies the conditional expression EN≦M/B1, and furthermore, the color conditions are changed to monochrome reading. to determine the rereading conditions. In the third example, the rereading conditions may be determined by changing the resolutions Rx and Ry as in the second example instead of the compression rate EN.

[Fourth example]
In the fourth example, when the current reading conditions specify double-sided reading, the re-reading conditions are determined by changing double-sided reading to single-sided reading and further changing the compression ratio EN as necessary. .

Specifically, the total amount of read image data Z=C (K/8) (W Rx/25.4) ( When L·Ry/25.4)·EN is equal to or less than the value M, the current reading conditions are changed so as to change to single-sided reading, and re-reading conditions are determined.

When the calculated total amount Z exceeds the value M, the conditional expression M≧A·C·(K/8)·(W·Rx/25.4)·( The reread condition is determined by obtaining the maximum value of the compression rate EN that satisfies L·Ry/25.4)·EN.

That is, the current reading conditions are changed so that the compression rate EN is changed to the maximum value of the compression rate EN that satisfies the conditional expression EN≤M/B1, and furthermore, the condition regarding the number of sides to be read is changed to single-sided reading. Change to determine the reread condition. In the fourth example, the rereading conditions may be determined by changing the resolutions Rx and Ry as in the second example instead of the compression rate EN.

Four specific examples of determination of rereading conditions have been described above, but determination of rereading conditions is not limited to these examples. For example, the rereading condition may be determined by changing the number K of gradations. Alternatively, the rereading condition may be determined by changing the main scanning direction resolution Rx without changing the sub scanning direction resolution Ry. Alternatively, by adjusting the compression rate EN and the resolutions Rx and Ry step by step in a predetermined order, a combination of the compression rate EN and the resolutions Rx and Ry where the total amount Z is equal to or less than the value M is obtained, and the rereading conditions are determined. You may

After determining the rereading conditions in S240, the main unit 60 displays the details of the rereading conditions to the user through the user interface 90, thereby proposing rereading of the document Q under these reading conditions (S250).

In the process of S250, a message is sent to the user through the user interface 90 to prompt the user to rearrange the document Q to be read, which has been discharged to the discharge tray 15 through the process of S210, to the bottom layer of the document tray 10 for rereading. can be displayed in

After that, the main unit 60 waits until a rereading instruction to reread the document Q is input, or a cancel instruction indicating that rereading is not desired is input through the user interface 90 (S260). When the cancel instruction is input, the main unit 60 terminates the document reading process without executing the process for rereading the document Q. FIG.

On the other hand, when the rereading instruction is input (Yes in S260), the main unit 60 sets the value of the operation parameter related to document reading to the value corresponding to the rereading condition (S270). After that, the main unit 60 executes the processing from S120 onwards, and performs the reading operation by the line sensor 20 and the transport mechanism 40 through the reading control unit 70 and the motor control unit 80 so that the document Q can be read under the determined re-reading conditions. is controlled (S160).

Since the rereading condition is set so that the reading stop condition is not satisfied, normally, after the process of S270 proceeds to S120, the entire document Q is normally reread without making an affirmative determination in the process of S180. Then, the document reading process ends.

According to the image reading system 1 of the present embodiment described above, when the document Q to be read is long in the sub-scanning direction and the storage area in the RAM 65 for accumulating the read image data of the document Q becomes insufficient, By resetting appropriate reading conditions according to the document length L, it is possible to reread the document Q so as not to cause the shortage of the storage area again. For example, by adjusting the reading conditions related to the quality of the read image, such as the resolutions Rx and Ry and the compression rate EN, the document Q can be read again so as to suppress the total amount of read image data to the upper limit or less. .

Especially in this embodiment, the rotation operation of the second motor 55 related to document transport is monitored, and after the leading edge of the document Q enters the document detection point by the rear sensor RS, the trailing edge of the document Q passes the document detection point. The count-up operation of the number of steps N is performed until the number of steps is reached. As a result, the amount of rotation of the second motor 55 until the document Q passes the document detection point by the rear sensor RS from the leading edge to the trailing edge is measured. .

Characteristically, even after the reading of the document Q is stopped due to the shortage of the storage area of the read image data in the RAM 65, the operation of counting up the number of steps N is continued, and the feeding operation of the document Q before the reading is stopped is continued. The document length L is determined from the number of steps N corresponding to the sum of the amount of transport of the document Q in , and the amount of transport of the document Q in the discharging operation of the document Q.

Therefore, according to the present embodiment, when reading is stopped, an appropriate re-reading condition is set for a document Q whose document length L is unknown, and appropriate re-reading of the document Q corresponding to the document length L is realized. be able to.

It goes without saying that the present disclosure is not limited to the above-described embodiments, and can take various forms. The above embodiment is an example in which the technique of the present disclosure is applied to the image reading system 1 capable of reading both sides. However, the technique of the present disclosure may be applied to a single-sided image reading system that includes only one line sensor 20 .

In the above-described embodiment, the number of steps N is counted up before the discharge operation in S210 in order to determine the length L of the document. It may be executed only during the period until switching to the signal. Then, the number of steps N in this period, the reading length of the document Q in the sub-scanning direction derived from the value M and the reading conditions described above, the distance from the document detection point by the rear sensor RS to the reading point by the line sensor 20, The document length L may be determined based on.

In the above embodiment, a single rereading condition is determined and this rereading condition is presented to the user. However, a plurality of rereading conditions are presented to the user, and based on one rereading condition selected by the user from among the plurality of rereading conditions, processing related to rereading of the document Q is executed. The image reading system 1 may be configured.

In addition, the function of one component in the above embodiments may be distributed among a plurality of components. Functions possessed by multiple components may be integrated into one component. A part of the configuration of the above embodiment may be omitted. At least part of the configurations of the above embodiments may be added or replaced with respect to the configurations of other above embodiments. All aspects included in the technical ideas specified by the language in the claims are embodiments of the present disclosure.

DESCRIPTION OF SYMBOLS 1... Image reading system 3... External device 10... Document tray 15... Discharge tray 20... Line sensor 30... Separation mechanism 31... Separation roller 32... Reverse roller 40... Conveyance mechanism 41... Conveyance roller , 42... driven roller, 45... discharge roller, 46... driven roller, 51... first motor, 52... transmission mechanism, 55... second motor, 56... transmission mechanism, 60... main unit, 61... CPU, 63... ROM, 65... RAM, 67... NVRAM, 70... reading control unit, 80... motor control unit, 90... user interface, 95... communication interface, FS, RS... sensor.

Claims (8)

a reading unit configured to read a document in a first direction;
a conveying unit configured to convey the document in a second direction crossing the first direction;
A control unit configured to execute processing for controlling the reading unit and the conveying unit, wherein the processing includes causing the conveying unit to execute a conveying operation of conveying the document in the second direction. a control unit that causes the reading unit to repeatedly perform a reading operation of reading the document in the first direction and generating read image data of the document;
a storage unit configured to sequentially store the read image data generated for each reading operation;
with
The control unit
executing, as the processing, a first control processing for controlling the reading unit and the conveying unit so that the document is read under a first reading condition;
determining whether the total amount of the read image data stored in the storage unit in the course of executing the first control process exceeds a threshold;
on the condition that the total amount is determined to have exceeded the threshold, suspending the first control process and causing the transport unit to perform the operation of discharging the document;
determining the length of the document in the second direction based on the amount of transport of the document by the transport unit during the discharge operation;
Based on the determined length and a data amount upper limit corresponding to the total amount of the read image data storable by the storage unit, the total amount of the read image data when reading of the document is completed is equal to or less than the data amount upper limit. determine the second reading condition that fits in,
An image reading system configured to execute a second control process for controlling the reading section and the conveying section so that the document is read under the determined second reading condition. the transport unit includes a sensor configured to detect the document;
Based on the input signal from the sensor, the control unit measures the transport amount of the document by the transport unit during the transport operation and the discharge operation, and determines the length of the document in the second direction. 2. The image reading system according to claim 1. Based on the input signal from the sensor, the control unit controls, based on the input signal from the sensor, from when the leading edge of the document enters the detection point by the sensor due to the conveying operation to when the trailing edge of the document passes the detection point due to the discharge operation. 3. The image reading system according to claim 2, wherein said length is determined by measuring a transport amount of said document by said transport unit. 4. The image according to any one of claims 1 to 3 , wherein the second reading condition is determined by changing the value of at least one parameter related to the quality of the read image under the first reading condition. reading system. the first read condition and the second read condition are defined by at least one parameter;
4. The at least one parameter according to any one of claims 1 to 3 , wherein the at least one parameter includes at least one of compression rate, resolution, number of gradations, presence/absence of color, and number of reading surfaces of the read image. Image reading system. The control unit proposes the document reading under the second reading condition to the user through the user interface, and executes the second control process on condition that the document reading is instructed through the user interface. The image reading system according to any one of claims 1 to 5 . a reading process of repeatedly executing a reading operation of reading a document in a first direction and generating read image data of the document while conveying the document in a second direction intersecting the first direction; executing to read the document under one reading condition;
sequentially storing the read image data generated for each reading operation in a storage unit;
determining whether the total amount of the read image data in the storage unit exceeds a threshold;
stopping the reading process and discharging the document on condition that it is determined that the total amount exceeds the threshold;
Determining the length of the document in the second direction based on the amount of transport of the document at the time of ejection;
Based on the determined length and a data amount upper limit corresponding to the total amount of the read image data storable by the storage unit, the total amount of the read image data when reading of the document is completed is equal to or less than the data amount upper limit. determining a second reading condition that fits in;
re-executing the reading process so as to read the document under the determined second reading condition;
image reading method including controlling a reading unit configured to read a document in a first direction and a transport unit configured to transport the document in a second direction crossing the first direction; a reading operation of reading the document in the first direction to generate read image data of the document while causing the transport unit to perform a transport operation of transporting the document in the second direction; so that the document is read under a first reading condition;
sequentially storing the read image data generated for each reading operation in a storage unit;
determining whether the total amount of the read image data stored in the storage unit exceeds a threshold;
on condition that the total amount is determined to have exceeded the threshold value, stopping the processing and causing the transport unit to perform an operation of discharging the document;
Determining the length of the document in the second direction based on the transport amount of the document by the transport unit during the discharge operation;
Based on the determined length and a data amount upper limit corresponding to the total amount of the read image data storable by the storage unit, the total amount of the read image data when reading of the document is completed is equal to or less than the data amount upper limit. determining a second reading condition that fits in;
re-executing the process so that the document is read under the determined second reading condition;
A computer program that causes a computer to execute

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