JP2010141465A - Apparatus, program and method for reading image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable reading at high speed as much as possible with a simple configuration in an image reading apparatus including a sheet feeding device. <P>SOLUTION: The image reading apparatus determines whether an amount of image data read from an original which is stored in a buffer, exceeds a predetermined first threshold or not. When the amount of image data exceeds the first threshold, the image reading apparatus stops original reading, decelerates original transport and stops it, specifies a sheet feeding amount of an original in the deceleration, and in accordance with the specified sheet feeding amount, the image reading apparatus transports the original in a direction inverse to an original feeding direction in the original reading before the restart of original reading. Further, the image reading apparatus determines whether the amount of the image data stored in the buffer is less than a predetermined second threshold or not. When the amount of the image data is less than the second threshold, the image reading apparatus restarts the original transport and restarts original reading. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading technique using an ADF (Auto Document Feeder) function.

There is an image scanner (image reading apparatus) having an ADF (Auto Document Feeder) function. In such an image scanner, an image of the entire document is read by a stationary image sensor while moving the document at a constant speed (for example, Patent Document 1).

The image scanner temporarily stores the read image data in a buffer and sequentially transfers the data to a host such as a personal computer (PC). The transfer speed is determined according to the processing capability of the host computer. Therefore, the reading speed of the image scanner is adjusted to a low speed so that the buffer does not become full.

Japanese Patent Laid-Open No. 2006-20084

By the way, there is a need to increase the reading speed, but if the speed is increased, the buffer tends to become full. In this regard, a method of temporarily stopping the document feeding when the buffer approaches full can be considered.

However, if the paper feed roller of the paper feeding device is driven beyond a predetermined speed, it cannot be stopped suddenly due to the mechanical structure, and a deceleration step is required.

The conventional image scanner does not assume a case where a deceleration step occurs. If a deceleration step is provided, the read image is distorted.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a technique capable of reading as fast as possible with a simple configuration in an image reading apparatus including a paper feeding device.

A first aspect of the present invention for solving the above-described problem is an image reading apparatus having a paper feeding device, wherein the paper feeding means for controlling the conveyance of the original by the paper feeding device, and reading the original Reading means for outputting image data, a buffer for temporarily storing the image data, monitoring means for monitoring the amount of the image data stored in the buffer, and paper feed for specifying the paper feed amount of the original An amount specifying unit, and when the monitoring unit determines that the amount of the image data exceeds a predetermined first threshold, the reading unit stops reading the document, and the paper feeding unit , The conveyance of the original is decelerated and stopped, the paper feed amount specifying means specifies the paper feed amount of the original document being decelerated, and the paper feed means is in accordance with the specified paper feed amount, Before resuming the reading of the original, When the monitoring unit determines that the document is conveyed in a direction opposite to the conveyance direction in reading and the amount of the image data is less than a predetermined second threshold, the paper feeding unit resumes conveyance of the document. The reading means restarts reading the document.

According to a second aspect of the present invention for solving the above-described problem, an image in an image reading apparatus having a paper feeding device for conveying a document and a buffer for temporarily storing image data of the read document is provided. A method of reading, wherein the step of determining whether or not the amount of the image data stored in the buffer exceeds a predetermined first threshold, and the amount of the image data exceeds the first threshold In addition, the reading of the original is stopped, the conveyance of the original is decelerated and stopped, the paper feed amount of the original being decelerated is specified, and the reading of the original is resumed according to the specified paper feed amount. Until the document is transported in a direction opposite to the transport direction in reading;
Determining whether or not the amount of the image data stored in the buffer is less than a predetermined second threshold; and when the amount of the image data is less than the second threshold, And the step of resuming the reading of the original document.

According to a third aspect of the present invention for solving the above-described problem, an image reading apparatus including a paper feeding device that conveys a document and a buffer that temporarily stores image data of the read document is provided. Determining whether or not the amount of the image data stored in the buffer exceeds a predetermined first threshold, the program causing an image reading process to be performed;
When the amount of the image data exceeds the first threshold, the reading of the document is stopped, the conveyance of the document is decelerated and stopped, and the paper feed amount of the document being decelerated is specified and specified. In accordance with the paper feed amount, the step of transporting the document in a direction opposite to the transport direction in scanning until the reading of the document is resumed, and the amount of the image data stored in the buffer is a predetermined first Determining whether or not the threshold value is less than a threshold value of 2, and resuming the conveyance of the document and restarting reading of the document when the amount of the image data is less than the second threshold value; It is characterized by performing.

  Hereinafter, an embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of an image scanner 1 which is an example of an image reading apparatus of the present invention.

The image scanner 1 is a so-called flatbed image scanner having a document table on the top surface of a housing. The image scanner 1 is arranged on a document fixed on a document table having a transparent plate.
The image is read by applying light from below and scanning the image sensor 11.

The image scanner 1 includes an upward document table 50 for placing a document as a read medium;
A document placement surface (board surface) 51 of the document table 50 and a lid 52 that covers the image reading window 53 from above are provided. The lid 52 is coupled to the document table 50 via a hinge mechanism and can be opened and closed.

Further, a sheet feeding device (ADF) 40 is provided integrally with the lid 52 on the left side of the board surface 51 in the drawing (upstream side along the document flow), that is, on the upper side of the image reading window 53. The paper feed device 40 includes a paper feed tray 41, a transport roller (paper feed roller) 42, a paper discharge tray 43, and a drive motor (stepping motor) 44. The rotation of the transport roller 42 is controlled by a drive motor 44. The paper feeding device 40 can send the document placed on the paper feeding tray 41 by passing it to the upper surface of the image reading window 53.

Further, the image scanner 1 has a CCD color image sensor 11 below the document table 50.
Is mounted, a carriage drive mechanism 20 that controls the reciprocating movement of the carriage 10, and a main board 30 that controls the entire image scanner 1.

The carriage 10 carries the image sensor 11 in the sub-scanning direction. The carriage 10
It is slidably attached to a guide shaft or the like parallel to the platen surface 51 and the image reading window 53 of the document table 50, and is pulled and reciprocated by a belt rotated by the motor 21 of the carriage drive mechanism 20. When reading is performed while the document is being conveyed by the sheet feeding device 40, the carriage 10 is fixed at a predetermined position below the image reading window 53.

The carriage drive mechanism 20 includes a motor 21 for rotating a belt attached to the carriage 10 and an encoder 22 that outputs a pulse according to the rotation amount of the motor 21.

The main board 30 includes an A / D converter 31, a buffer 32, an output unit 33, and a control unit 34.
And have.

The A / D converter 31 converts an analog signal from the image sensor 11 into a digital signal.

The buffer 32 temporarily stores the data output from the A / D converter 31 in a first-in first-out FIFO format, and sends the data to the output unit 33 in order from the previously stored data. The buffer 32 stops accepting data when the stored data exceeds a predetermined data amount (near full). Then, only the transfer to the output unit 33 is performed, and a predetermined data amount (near empty)
The next data is not accepted until it becomes less than.

Here, the near full value and the near empty value, which are values related to the data amount of the buffer 32, will be described. Even after the control unit 34 issues a read operation stop command to the image sensor 11, the already read data is transferred to the buffer 32. The near full value is the maximum limit of the data amount that can accept the data being transferred without the buffer 32 becoming full. On the other hand, the read data is stored in the buffer 3 even after the read restart command is issued.
It takes time to reach 2. Therefore, if the data is completely empty, the data sent to the host computer 2 is interrupted and the throughput is reduced. The near empty value is a minimum limit of the data amount determined so that the data is not interrupted.

The output unit 33 sends the data in the buffer 32 to the host computer 2 (scanner control device) such as a personal computer at a transfer rate according to the processing capability of the host.

The control unit 34 controls the paper feeding device 40, the carriage driving mechanism 20, and the image sensor 11. Specifically, the control unit 34 includes a drive motor 44 for the conveyance roller 42 of the paper feeding device 40.
And the document on the paper feed tray 41 is conveyed to the right side (downstream along the document flow) in the drawing and is passed through the image reading window 53. Further, the rotation of the motor 21 of the carriage drive mechanism 20 is controlled, and the movement of the carriage 10 is controlled. Further, the position and moving speed of the carriage 10 are obtained from the output pulse of the encoder 22. In addition, the start and stop of the image reading operation of the image sensor 11 is controlled.

Further, the control unit 34 monitors the amount of data in the buffer 32. For example, when a predetermined near full value is exceeded, the control unit 34 stops the reading operation of the image sensor 11 and stops the paper feeding operation of the paper feeding device 40. As will be described in detail later, the driving motor 44 is controlled to reversely rotate the conveyance roller 42 (reverse to the rotation at the time of reading the document), and the document is set in a predetermined direction in the left direction (upstream along the document flow). Transport distance. When the data amount becomes less than the near empty value, the paper feeding operation of the paper feeding device 40 is resumed and the reading operation of the image sensor 11 is resumed.

The control unit 34 can be configured by a computer including a CPU that is a main control device, a ROM that stores programs and the like, and a RAM that temporarily stores data and the like as a main memory. In addition, ASIC (Application designed to perform each processing exclusively)
Specific Integrated Circuit).

Although the general configuration of the image scanner 1 has been described above, the main configuration has been described in describing the features of the present invention, and other configurations included in a general image scanner are not excluded.

  Next, a characteristic operation of the image scanner 1 configured as described above will be described.

FIG. 2 is a flowchart of the image reading process of the image scanner 1. This flow shows a case where image data for one page is read. When the control unit 34 receives a document reading request from the user, the control unit 34 starts this flow.

First, the control unit 34 determines a paper feed speed (high speed mode) (S10). Therefore, the control unit 34 has a table. Here, the table (motor control table 200) will be described. FIG. 3 shows a configuration example of the motor control table 200.

The motor control table 200 stores a plurality of entries that associate the mode 210, the acceleration control data 220, the deceleration control data 230, and the paper reverse feed control data 240.
Each entry is information corresponding to the paper feed speed mode.

In the figure, there are a high speed mode (A to C) and a low speed mode (D) as modes. In the high speed mode (A to C), in order to rotate the drive motor 44 of the transport roller 42 at high speed, it is necessary to control the acceleration step to reach the speed and control the deceleration step to stop. On the other hand, in the low speed mode (D), since it is a low speed rotation that does not require acceleration and deceleration,
Control of the acceleration step and the deceleration step is unnecessary. Note that the high-speed mode is prepared according to the reading resolution. Of course, a plurality of high-speed modes may be prepared for the same reading resolution.

  The mode 210 is information for specifying the paper feed speed mode.

The acceleration control data 220 is control information for accelerating the rotation of the drive motor 44 of the transport roller 42 to a constant speed. For example, the number of steps required for acceleration, timing information for supplying a current for increasing the speed for each step, and the like. As described above, the acceleration control data 220 is not set in the entry of the low speed mode (D) (shown as “−” in the figure).

The deceleration control data 230 is control information for decelerating and stopping the rotation of the drive motor 44 of the transport roller 42 from a constant speed. For example, the number of steps required for deceleration, timing information for supplying a current for decreasing the speed for each step, and the like. As described above, the deceleration control data 230 is not set in the entry of the low speed mode (D) (indicated by “−” in the figure).

The paper reverse feed control data 240 is control information for controlling the rotation of the drive motor 44 so that the document is conveyed by a predetermined distance in the direction opposite to the paper feed direction (sub-scanning direction). For example, the number of steps. Paper reverse feed is a low-speed rotation that does not require acceleration and deceleration, and does not require control of the acceleration step and the deceleration step. Of course, the paper reverse feed speed may be high-speed rotation that requires acceleration and deceleration.

Here, the distance for transporting the document in the direction opposite to the paper feed will be described. The control unit 34 stops the reading operation of the image sensor 11 and stops the paper feeding operation of the paper feeding device 40 when the data amount of the buffer 32 exceeds a predetermined near full value. Therefore, when the paper feeding operation is performed in the high speed mode, the original is moved by the deceleration step even after the reading operation of the image sensor 11 is stopped.

For example, as shown in FIG. 4, the point A (reading pause position) of the document when the reading operation of the image sensor 11 is stopped moves in the sub-scanning direction due to the movement of the document during the deceleration step. . Therefore, the control unit 34 reversely feeds the original so that the image between the points A before and after the movement can be read, and the image sensor 11 reads the point A (reading pause position) moved by the deceleration step. To the position where it stopped (deceleration step start position). Thus, the distance that the document is conveyed in the direction opposite to the paper feed is the distance that the document is moved in the deceleration step.

Based on the moving distance specified as described above, the paper reverse feed control data 240 corresponding to each speed is preset in the entry of the high speed mode (A to C). On the other hand, the low speed mode (D
) Is not set in the paper reverse feed control data 240 (indicated by “−” in the figure).

Of course, the configuration of the motor control table 200 is not limited to the above. For example, the number of high-speed modes and low-speed modes is not limited to the above.

Returning to FIG. 2, the description will be continued. In S10, specifically, the control unit 34 determines a paper feed speed in a predetermined high-speed mode (any of A to C) according to the reading resolution designated by the user.
Further, an entry corresponding to the determined paper feed speed is specified from the motor control table 200 described above. Then, the process proceeds to S20.

Then, the control unit 34 starts rotation of the drive motor 44 of the paper feeding device 40 and accelerates it to a certain speed (S20). Specifically, the control unit 34 reads the acceleration control data 220 of the entry in the high speed mode specified in S10, and controls the motor according to the number of acceleration steps and timing information. When the speed reaches a certain speed, the image sensor 11 is controlled to start reading a document (S30).

During reading of the document in the high speed mode, the control unit 34 monitors whether or not the data amount in the buffer 32 exceeds a predetermined near full value (S40). When the amount of data is less than the near full value (
S40: NO), monitoring is continued. On the other hand, when the amount of data exceeds the near full value (S40:
YES), the process proceeds to S50.

In S50, the control unit 34 stops the reading operation of the image sensor 11. Then, the control unit 34 decelerates the drive motor 44 of the paper feeding device 40 from a certain speed and stops it (S
60). Specifically, the control unit 34 reads the deceleration control data 230 of the entry in the high speed mode specified in S10, and controls the motor according to the number of deceleration steps and timing information. Then, the process proceeds to S70.

In S70, the control unit 34 reversely feeds the document by a predetermined distance. Specifically, the control unit 34.
Reads out the paper reverse feed control data 240 of the entry in the high speed mode specified in S10, and controls the drive motor 44 of the paper feeder 40 according to the data. That is, the document is conveyed in the direction opposite to the paper feed direction by the distance the document has been moved in the deceleration step.

While reading of the document is stopped, the control unit 34 monitors whether or not the data amount in the buffer 32 is less than a predetermined near empty value (S80). If the data amount is greater than or equal to the near empty value (S80: NO), monitoring is continued. On the other hand, when the data amount is less than the near empty value (S80: YES), the process proceeds to S90.

In S90, the control unit 34 determines the paper feed speed to the low speed mode. Then, the control unit 34
Controls the drive motor 44 of the paper feeding device 40 to rotate at the determined paper feeding speed, and controls the image sensor 11 to start a document reading operation (S100).

During reading of the document in the low speed mode, the control unit 34 determines whether or not reading of an image for one page is completed (S110). And when reading has not ended (S110: NO)
The process proceeds to S120. On the other hand, when the reading is finished (S110: YES), this flow is finished.

In S120, the control unit 34 monitors whether or not the data amount of the buffer 32 exceeds a predetermined near full value. If the data amount is less than or equal to the near full value (S120: NO), the process is S1.
Return to 10. On the other hand, if the amount of data exceeds the near full value (S120: YES), the process is S
Proceed to 130.

In S <b> 130, the control unit 34 controls the image sensor 11 to stop the document reading operation, and stops the rotation of the motor of the paper feeding device 40. Then, the process returns to S80.

As described above, higher-speed image reading is performed without causing distortion in the read image.

That is, as shown in FIG. 5B, the movement of the reading position of the document due to the deceleration step is corrected by the backward feeding of the document. Thereby, the original image in FIG. 5A is read without distortion, and the output image in FIG. 5C can be generated.

In addition, as shown in FIG. 6, image reading is performed in the high speed mode until the buffer is full (near full), and after the buffer is full (near full), the image is read in the low speed mode. Is done. This speeds up image reading per page.

Here, in order to clarify the advantages of the configuration of the image scanner 1 of the present embodiment,
An image scanner that does not reversely feed a document even if there is a deceleration step will be described.

For example, as shown in FIG. 7, the original point A (reading pause position) when the reading operation of the image sensor 11 is stopped moves in the sub-scanning direction due to the movement of the original during the deceleration step. . Therefore, when the document is not fed backward, the reading resume position of the document is point B, and the image between the points AB before and after the movement of the document cannot be read.

That is, as shown in FIG. 8B, the movement of the reading position of the document due to the deceleration step is not corrected. Therefore, distortion occurs when the original image of FIG. 8A is read, and FIG.
An output image as shown in (c) is generated. In order to prevent such distortion from occurring, the low-speed mode is always used, and the reading speed cannot be increased.

The embodiment of the present invention has been described above. According to the present embodiment, an image reading apparatus provided with a paper feeding device can perform high-speed reading with a simple configuration as much as possible.

The above-described embodiment of the present invention is intended to illustrate the gist and scope of the present invention and is not intended to be limiting. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

For example, the reverse feeding of the document does not have to be performed immediately after the drive motor 44 of the paper feeding device 40 is stopped. What is necessary is just to make it complete between the stop of the drive motor 44 and a start (FIG. 2: S60-S100).

In the above embodiment, when a plurality of pages are continuously read, reading may be started in the high speed mode for each page. Specifically, the flow of FIG. 2 is repeated for each page. When a plurality of pages are continuously read, the first page may be read in the high speed mode, and once the low speed mode is entered, the reading may be performed in the low speed mode until the last page. Specifically, in S110 of FIG. 2, it is determined whether or not all the pages have been read, and the processes in S80 to S130 are repeated until all the pages have been read.

In addition, an encoder that outputs a pulse according to the rotation amount of the conveyance roller 42 may be provided in the paper feeding device 40, and the control unit 34 may calculate the moving distance of the document based on this pulse.
In this way, the moving distance of the original in the deceleration step can be used as the moving distance of the reverse feed of the original, and it is not necessary to prepare the paper reverse feed control data 240 corresponding to the high speed mode in advance. That is, simpler control can be performed.

Further, the drive motor 44 of the sheet feeding device 40 is not limited to a stepping motor, and for example, D
A C motor or the like may be used.

The present invention can also be applied to a copier, a multifunction machine, and the like having an image scanner.

1 is a diagram illustrating a schematic configuration of an image scanner 1 which is an embodiment of an image reading apparatus of the present invention. 3 is a flowchart of image reading processing of the image scanner 1. FIG. 3 is a diagram illustrating a configuration example of a motor control table 200. FIG. It is a figure explaining the relationship between the movement of the original by a deceleration step, and a reading position. It is a figure explaining the range of the image read from a manuscript image. It is a figure explaining the relationship between a motor speed and a paper feed amount. FIG. 6 is a diagram for explaining a relationship between a movement of a document by a deceleration step and a reading position when the document is not reversely fed. FIG. 6 is a diagram for explaining a range of an image read from a document image when the document is not reversely fed.

Explanation of symbols

1: image scanner, 2: host computer, 10: carriage, 11: image sensor, 20: carriage drive mechanism, 21: motor, 22: encoder, 30: main board, 31: A / D converter, 32: buffer, 33: output unit, 34: control unit, 40: paper feeding device, 41: paper feeding tray, 42: transport roller, 43: paper ejection tray, 44: drive motor, 50:
Document table 51: Board surface 52: Lid 53: Image reading window 200: Motor control table
210: mode, 220: acceleration control data, 230: deceleration control data, 240: paper reverse feed control data

Claims (3)

An image reading apparatus having a paper feeding device,
Paper feeding means for controlling the conveyance of the document by the paper feeding device;
Reading means for reading the document and outputting image data;
A buffer for temporarily storing the image data;
Monitoring means for monitoring the amount of the image data stored in the buffer;
Paper feed amount specifying means for specifying the paper feed amount of the document,
When the monitoring means determines that the amount of the image data has exceeded a predetermined first threshold,
The reading unit stops reading the document;
The paper feeding means decelerates and stops the conveyance of the document,
The paper feed amount specifying means specifies the paper feed amount of the original document being decelerated,
The paper feeding means transports the document in a direction opposite to the transport direction in reading until the reading of the document is resumed according to the specified paper feed amount,
When the monitoring means determines that the amount of the image data is less than a predetermined second threshold,
The paper feeding means resumes transporting the document,
The reading means restarts reading the document;
An image reading apparatus. An image reading method in an image reading apparatus, comprising: a paper feeding device that conveys a document; and a buffer that temporarily stores image data of the read document.
Determining whether the amount of the image data stored in the buffer has exceeded a predetermined first threshold;
When the amount of the image data exceeds the first threshold, the reading of the document is stopped,
The conveyance of the original is decelerated and stopped, the paper feed amount of the original document being decelerated is specified, and the original is conveyed in reading until the reading of the original is resumed according to the specified paper feed amount. Conveying in a direction opposite to the direction;
Determining whether the amount of the image data stored in the buffer is less than a predetermined second threshold;
When the amount of the image data becomes less than the second threshold, the conveyance of the document is resumed,
Resuming reading of the document,
An image reading method characterized by the above. A program for causing an image reading apparatus having a paper feeding device for conveying a document and a buffer for temporarily storing image data of the read document to perform image reading processing,
In the image reading device,
Determining whether the amount of the image data stored in the buffer has exceeded a predetermined first threshold;
When the amount of the image data exceeds the first threshold, the reading of the document is stopped,
The conveyance of the original is decelerated and stopped, the paper feed amount of the original document being decelerated is specified, and the original is conveyed in reading until the reading of the original is resumed according to the specified paper feed amount. Conveying in a direction opposite to the direction;
Determining whether the amount of the image data stored in the buffer is less than a predetermined second threshold;
When the amount of the image data becomes less than the second threshold, the conveyance of the document is resumed,
Resuming the reading of the document, and
A program characterized by

Images