JP2003189066A - Image reader, image reading method, and control program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable image reading control in such a manner as to effectively use a memory for storage of image data while eliminating the need for modifying software. <P>SOLUTION: Image data is read out from an original document by scanning the document in its main scanning and sub-scanning directions; the read-out image data is stored in an image memory; the capacity of the memory is detected at the time of outputting the data to an external device; a free space in the memory is measured on the basis of the detected capacity of the memory, the amount of image data written in the memory an the amount of data read out therefrom; a sub-scanning speed is decreased when the measured free space is not larger than a first predetermined value; and the sub-scanning speed is increased when the free space is not smaller than a second predetermined value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sub-scanning control technique for an image reading device.

[0002]

2. Description of the Related Art Conventionally, an image is scanned in the main scanning direction using a line sensor or the like, and the main scanning position is moved in synchronism with the image reading in the main scanning direction to perform the sub-scanning. 2. Description of the Related Art Image reading devices that scan and read an image recorded on a disk are widely used.

As the sub-scanning method, there are known a method of fixing an original and moving the reading optical system in the sub-scanning direction, and a method of fixing the reading optical system and moving the original in the sub-scanning direction. However, the latter method is generally adopted in a small-sized image reading apparatus.

Generally, since the image data has a very large amount of information, when an image processing apparatus for inputting the image data read by the image reading apparatus cannot take in a large amount of image data at a time, the image data from the image reading apparatus is read. Transfer must be temporarily interrupted. In order to solve this problem, for example, an image reading apparatus having a large-capacity image memory capable of storing image data for one page has been realized.

However, in this case, since a large-capacity image memory is required, the memory cost becomes high,
There is a problem that it becomes an expensive image reading device.

Therefore, a method of mounting a line memory for a plurality of lines, interrupting the transfer of image data, and interrupting the reading operation of an original when the free space of the line memory becomes small is widely used.

Conventionally, a FIFO memory or an S-RAM has been used as the line memory because it is necessary to write and read image data at high speed.
Due to the increased speed of RAM, cheaper and larger capacity D-RAM is often used.

The D-RAM has a simple structure as compared with other memories, and in recent years, in particular, in recent years, a large capacity D-RA with a short cycle is used.
M has been developed and tends to replace small capacity D-RAM. Therefore, the D-RA used as the line memory
M was unable to obtain the capacity originally planned,
Larger capacity may be used.

Normally, the memory capacity set in each image reading device has a fixed value at the time of design written in software, and the D-RAM used as a line memory.
If the capacity of the is changed, the software needs to be changed.

If the software is not changed, D-
When only the capacity of the RAM becomes large, only the set capacity can be used.

[0011]

As described above, when the image data transfer is interrupted, when the reading of the original is once interrupted and then restarted, or when the sub-scanning speed is rapidly changed, etc. As compared with the case where a document image is read by a fast motion, mechanical blurring is likely to occur and the problem of image deterioration occurs.

Further, in order to keep the reading operation of the original as uninterrupted as possible and to suppress the acceleration / deceleration of the sub-scanning speed as much as possible, it is more advantageous that the memory for storing the image data is larger. You should use the full capacity.

The present invention has been made in view of such a problem, and an object thereof is to perform image reading control in such a manner that a memory for storing image data is effectively used without changing software. Is to be able to do.

[0014]

In order to solve the above problems, the present invention reads image data from a document by scanning the document in the main scan and sub-scan, and outputs the read image data after storing it in a memory. In the image reading device, a detection unit that detects the capacity of the memory, the capacity of the memory detected by the detection unit, the amount of image data written to the memory, and the amount of image data read from the memory. Measuring means for measuring the free space of the memory based on the above, and when the free space measured by the measuring means becomes equal to or lower than a first predetermined value, the sub-scanning speed is decelerated to set the free space to the second And a control means for accelerating the sub-scanning speed.

Further, according to the present invention, in the image reading method of reading the image data from the original by performing main scanning and sub-scanning of the original, storing the read image data in the memory, and outputting the image data, the capacity of the memory is detected. And a free capacity of the memory based on a capacity of the memory detected by the detecting step, a writing amount of image data to the memory, and a reading amount of image data from the memory. In the measuring step, if the free space measured in the measuring step becomes less than or equal to the first predetermined value, the sub-scanning speed is reduced, and if the free capacity becomes more than or equal to the second predetermined value, And a control step for accelerating the scanning speed.

Further, the present invention is a control program executed by an image reading apparatus for reading image data from a document by performing main scanning and sub-scanning of the document, storing the read image data in a memory, and outputting the image data. Detect the capacity of the memory, and measure the free capacity of the memory based on the detected capacity of the memory, the writing amount of image data to the memory, and the reading amount of image data from the memory. When the measured free space is less than or equal to the first predetermined value, the sub-scanning speed is decelerated, and when the free space is greater than or equal to the second predetermined value, the sub-scanning speed is accelerated. is doing.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the schematic arrangement of an image reading apparatus to which the present invention is applied.

In FIG. 1, a reading control unit 11 optically reads image information of a document and converts it into digital image data. The input / output control unit 12 performs control of writing image data in the memory 14 and control of reading image data from the memory 14, and the output control unit 13
The image data is output to the outside.

The memory 14 is a memory for storing image data, and in recent years, especially an SD-RAM (synchronous D-RAM) is often used because of its large capacity and easy control method. The memory capacity measuring unit 15 measures the capacity of the mounted memory 14, and is normally activated only when the power is turned on to measure the capacity of the mounted memory 14. The sub-scanning speed control unit 16 moves a document or a reading sensor in the sub-scanning direction in response to a signal from the control unit 17, and transmits a reading signal for starting reading of image data to the reading control unit 11. Is.

The control unit 17 controls the entire operation, and is generally a microcomputer. That is, although not shown, the control unit 17 includes a CPU and an RO.
It has an M and a RAM, and various control programs are stored in the ROM, and the CPU executes various control programs by executing the control programs. At this time, the CPU uses the RAM as a work area or the like.

[First Embodiment] First, when the power is turned on, the memory capacity measuring unit 15 measures the capacity of the memory 14 for storing image data. As a method of measuring the memory capacity, it is easy to write data in the memory 14 and read the data. However, in this method, as the memory capacity increases, the data is written and read in all areas of the memory. If you put it out, it will take a considerable amount of time.
Therefore, in the present embodiment, data is not written or read at all addresses of the memory 14, but data is written or read at addresses of powers of two. By doing this, even if the capacity of the installed memory is doubled, only 1
The memory capacity can be measured by adding read and write operations once.

The memory 14 is replaceable,
Particularly, a memory module used in a personal computer (hereinafter referred to as a PC) or the like is assumed. This memory module is equipped with an EEP-ROM in which information such as memory capacity and type has been written in advance,
By reading the information in the EEP-ROM, the capacity of the memory can be measured.

In this way, the capacity of the memory 14 measured by the memory capacity measuring unit 15 is sent to the control unit 17.

The reading control section 11 has a light source for irradiating the original and a line sensor, and synchronizes the main scanning image information of the image information of the original with the signal from the sub-scanning speed control section 16.
The image data read is read line by line.
It is converted into digital image data and sent to the input / output control unit 12.

The input / output control unit 12 transfers the digital image data sent from the reading control unit 11 to the memory 14, and controls the amount of image data written in the memory 14 by the control unit 17.
Send to. Further, the input / output control unit 12 reads image data from the memory 14 and transfers the image data to the output control unit 13 according to a request from the output control unit 13, and sends the image data amount read from the memory 14 to the control unit 17.

The output control unit 13 is an interface for outputting image data to an external device such as a PC, and has a SCSI or USB interface particularly when connected to a PC.

The control unit 17 uses the total capacity of the memory 14 sent from the memory capacity measuring unit 15 and the write image data amount and the read image data amount sent from the input / output control unit 12 to free the memory 14. The capacity is calculated as free capacity = total memory capacity− (write capacity−read capacity).

The control unit 17 controls the sub-scanning speed control unit 16 when the free space becomes equal to or less than the preset first predetermined value.
Is instructed to decelerate the sub-scanning speed, and when the free space becomes equal to or larger than the second predetermined value, the sub-scanning speed control unit 16 is instructed to accelerate the sub-scanning speed.

The sub-scanning speed control section 16 transmits a sub-scanning read signal to the reading control section 11 based on the signal from the control section 17. With this signal, acceleration / deceleration control of the reading speed in the sub-scanning direction is performed.

Next, the operation of the present invention will be described with reference to FIGS.

FIG. 2 is a diagram showing a transition example of the free space in the memory 14 of FIG. 1, and FIG. 3 is a diagram showing a change of the sub-scanning speed corresponding to the transition of the free space of FIG. is there.

In FIG. 2, the solid line indicates that the memory capacity is 20.
The transition of the free capacity in the case of, and the broken line shows the transition of the free capacity when the memory capacity is 10. In this example, the first predetermined value designed in advance is 6 and the second predetermined value is 8 and the memory 14 for storing image data is shown.
The ratio of writing to and reading from is the same for the case of the memory capacity 20 and the case of the memory capacity 10.

The upper limit of the sub-scanning speed is determined by the performance of the sensor, the light source and the transport system used in the apparatus.
In this example, as shown in FIG. 3, the upper limit is set to a predetermined MAX.
The speed is set and the lower limit is set to 0. It is also possible to set the upper limit value and the lower limit value of the sub-scanning speed from an operation unit or the like not shown in FIG.

In FIG. 2, when the memory capacity is 20,
At point A, the free space becomes less than or equal to the first predetermined value, and A in FIG.
The deceleration of the sub-scanning speed starts from the point, and after a lapse of a predetermined time, the sub-scanning is performed at the decelerated predetermined speed. Then B
At the point, the free space becomes equal to or larger than the second predetermined value, acceleration of the sub-scanning speed starts from point B in FIG. 3, and after a predetermined time has elapsed,
The sub-scan is performed at the set predetermined MAX speed.
In the case of the memory capacity 20, the free space changes after the free space at the point A becomes less than or equal to the first predetermined value, but does not become less than or equal to the first predetermined value. Is a constant speed at a predetermined MAX speed.

In the case of the memory capacity 10, first, a in FIG.
At the point, the free space becomes equal to or smaller than the first predetermined value, and the deceleration of the sub-scanning speed starts from the point a in FIG. Next, since the free space does not exceed the second predetermined value up to the point b in FIG. 2, the sub-scanning speed becomes 0 up to the point b in FIG. 3, and the acceleration of the sub-scanning speed starts from this point b. Furthermore, the free space is
2 again becomes less than the first predetermined value at point c, the deceleration of the sub-scanning speed starts at point c in FIG. 3, and the sub-scanning continues until point d in FIG. The speed acceleration does not start, and the sub-scanning speed becomes 0 up to point d in FIG.

As described above, in the case of the memory capacity 20, the deceleration acceleration of the sub-scanning speed is performed only once, whereas in the case of the memory capacity 10, the deceleration acceleration of the sub-scanning speed is performed twice. . Further, the period when the sub-scanning speed is constant is shorter in the case of the memory capacity 10 than in the case of the memory capacity 20.

Further, in the case of the memory capacity 20, the period of deceleration and acceleration is shorter than that in the case of the memory capacity 10, and the change in the sub-scanning speed can be set more gently.

As described above, the deterioration of the image is the least when the sub-scanning speed is constant, and when the memory capacity becomes small, not only the time required to read the image data of one original document becomes long, However, there is a problem that the image is apt to deteriorate.

The present invention has a function of measuring the capacity of the installed memory, and even if the capacity of the memory for storing image data is changed, it is installed without changing the software. It is possible to use the full capacity of the memory, keep the sub-scanning speed as constant as possible, and even if the deceleration of the sub-scanning speed is accelerated, the change can be made more gradual and the image can be displayed at high speed. It is possible to obtain image data without deterioration.

[Second Embodiment] Next, a second embodiment of the present invention will be described.

In the second embodiment, the control unit 17 shown in FIG.
It is assumed that the size, resolution, and reading mode of the document to be read are instructed from an operation unit (not shown) or the like.

In the control section 17, the capacity of the memory 14 is sent from the memory capacity measuring section 15, and the image data amount of the original is calculated from the size, resolution and mode information of the original to be read.

As a result of the calculation, the memory 1 for storing the image
When the capacity of 4 is equal to or more than the amount of image data to be read, the sub-scanning speed is not decelerated even if the free space of the memory 14 becomes equal to or less than the first predetermined value, and the sub-scanning speed remains constant. , Read the image information of the document.

Since the capacity of the memory 14 has a capacity for storing all the image data, it is not necessary to decelerate the sub-scanning speed even if the free capacity of the memory 14 becomes the first predetermined value or less. It is possible to store all image data. Further, since the sub-scanning speed is constant, it is possible to provide image data with little deterioration.

If the sub-scanning speed is less than the upper limit value, the sub-scanning speed can be accelerated to the upper limit value, and the image information of the original can be read at high speed.

[Third Embodiment] Next, a third embodiment of the present invention will be described.

FIG. 4 is a block diagram showing the schematic arrangement of an image reading apparatus according to the third embodiment. The same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 4, the document detecting section 41 detects the presence or absence of a document to be read, and also detects the leading and trailing ends of the document.

FIG. 5 is a view showing the schematic arrangement of the image reading section in the third embodiment.

In this example, the original is moved in the sub-scanning direction in order to read it in the sub-scanning direction.

In FIG. 5, a roller 51 is a carrying roller for carrying a document and has a function of carrying the document 54 in the arrow direction. The document detection sensor 52 is included in the document detection unit 41 shown in FIG. 4, and is a sensor for checking the presence or absence of a document and detecting the leading edge and the trailing edge of the document. The line sensor 53 is included in the reading control unit 11 of FIG. 4 and is for collectively reading the image information in the main scanning direction of the document. The image information read by the line sensor 53 is converted into digital image data. It is converted and sent to the input / output control unit 12 in FIG.

The document detecting sensor 52 is a line sensor 53.
It is located upstream of a predetermined distance from, and it is possible to detect the leading edge and the trailing edge of the document before the fixed time before the document is fed to the position where the line sensor 53 reads the document.

The signal for detecting the trailing edge of the document 54 is sent from the document detection section 41 to the control section 17. as mentioned above,
The trailing edge signal of the document 54 from the document detection unit 41 is a signal detected upstream of the position where the line sensor 53 in the reading control unit 11 reads the document. Therefore, the control unit 17 can calculate the amount of remaining image data to be read based on the document trailing edge signal from the document detection unit 41.

When the remaining image data amount is less than or equal to the free space of the memory 14, the control unit 17 does not slow down the sub-scanning speed even if the free space of the memory 14 becomes less than or equal to the first predetermined value. , The image information of the original is read at the same speed.

When the sub-scanning speed is less than the upper limit value, the sub-scanning speed can be accelerated to the upper limit value, and the image information of the original can be read at high speed.

As described above, by using the entire memory capacity for storing the mounted image data, it is possible to rapidly supply the image data without deterioration of the image information. Further, even if the memory capacity is changed, the entire memory capacity can be used without changing the software.

Further, when the amount of image data becomes less than the free space of the memory, the sub-scanning speed is not reduced, so that the image can be read at high speed and the deterioration of the image information can be suppressed. .

The present invention is not limited to the above embodiment, and for example, the first and second predetermined values (image memory free space) for accelerating and decelerating the sub-scanning speed are different set values. However, it is also possible to accelerate and decelerate the sub-scanning speed using the same set value.

Further, it is possible to set the second set value <the first set value without setting the first set value <the second set value.

[0061]

As described above, according to the present invention,
It is possible to perform image reading control in such a manner that the memory for storing image data is effectively used without changing software.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image reading apparatus according to first and second embodiments of the present invention.

FIG. 2 is a diagram showing an example of a change in free space in a memory.

FIG. 3 is a diagram showing a variation example of a sub-scanning speed corresponding to FIG.

FIG. 4 is a block diagram showing a schematic configuration of an image reading apparatus according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of an image reading unit according to a third embodiment of the present invention.

[Explanation of symbols]

11 ... Reading control unit 12 ... Input / output control unit 13 ... Output control unit 14 ... Memory 15 ... Memory capacity measuring unit 16 ... Sub-scanning speed control unit 17 ... Control unit 41 ... Document detection unit 52 ... Document detection sensor 53 ... Line sensor 54 ... manuscript

Claims (19)

[Claims] 1. An image reading apparatus for reading image data from a document by performing main scanning and sub-scanning of the document, storing the read image data in a memory, and then outputting the image data, and detecting means for detecting the capacity of the memory. Measuring means for measuring the free space of the memory based on the capacity of the memory detected by the detecting means, the writing amount of image data to the memory, and the reading amount of image data from the memory, When the free space measured by the measuring means is less than or equal to the first predetermined value, the sub-scanning speed is decelerated, and when the free space is greater than or equal to the second predetermined value, the sub-scanning speed is accelerated. An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein the memory is a removable memory. 3. The control means has setting means for setting an upper limit value and a lower limit value of the sub-scanning speed, and does not accelerate the sub-scanning speed above the upper limit value or decelerate below the lower limit value. The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. 4. The control means has a calculating means for calculating the image data amount for one page of the original document, and when the capacity of the memory is larger than the image data amount for one page of the original document. 4. The image reading apparatus according to claim 1, wherein the sub-scanning speed is not reduced even when the free space of the memory becomes equal to or less than the first predetermined value. 5. The control means has a calculating means for calculating the remaining image data amount of the document to be read, and when the remaining image data amount is less than or equal to the free space of the memory,
The image reading apparatus according to claim 1, wherein the sub-scanning speed is not reduced even when the free space of the memory becomes equal to or less than the first predetermined value. 6. The control means has setting means for setting an upper limit value and a lower limit value of the sub-scanning speed, and accelerates to the upper limit value when the sub-scanning speed is less than the upper limit value. The image reading device according to claim 4 or 5. 7. The image reading apparatus according to claim 1, wherein the first predetermined value is a value smaller than the second predetermined value. 8. The image reading apparatus according to claim 1, wherein the first predetermined value and the second predetermined value are equal values. 9. The image reading apparatus according to claim 1, wherein the first predetermined value is larger than the second predetermined value. 10. An image reading method in which image data is read from a document by main scanning and sub-scanning the document, and the read image data is stored in a memory and then output, and a detection step of detecting the capacity of the memory. A measuring step of measuring the free space of the memory based on the capacity of the memory detected by the detecting step, the writing amount of image data to the memory, and the reading amount of image data from the memory, When the free space measured in the measuring step is less than or equal to the first predetermined value, the sub-scanning speed is decelerated, and when the free space is greater than or equal to the second predetermined value, the sub-scanning speed is accelerated. An image reading method, comprising: 11. The image reading method according to claim 10, wherein the memory is a removable memory. 12. The control step has a setting step of setting an upper limit value and a lower limit value of the sub-scanning speed, and the sub-scanning speed is not accelerated above the upper limit value and is not decelerated below the lower limit value. The image reading method according to claim 10, wherein: 13. The control step includes a calculation step of calculating an image data amount for one page of the document, and when the memory capacity is larger than the image data amount for one page of the document. 13. The image reading method according to claim 10, wherein the sub-scanning speed is not reduced even when the free space of the memory becomes equal to or less than the first predetermined value. 14. The control step includes a calculation step of calculating a remaining image data amount of a document to be read, and when the remaining image data amount is less than or equal to a free space of the memory, 14. The image reading method according to claim 10, wherein the sub-scanning speed is not reduced even when the free space becomes equal to or less than the first predetermined value. 15. The control step includes a setting step of setting an upper limit value and a lower limit value of the sub-scanning speed, and if the sub-scanning speed is less than the upper limit value, accelerates to the upper limit value. The image reading method according to claim 13 or 14. 16. The method according to claim 10, wherein the first predetermined value is smaller than the second predetermined value.
5. The image reading method according to any one of 5 above. 17. The method according to claim 10, wherein the first predetermined value and the second predetermined value are equal values.
The image reading method according to any one of 1. 18. The method according to claim 10, wherein the first predetermined value is a value larger than the second predetermined value.
5. The image reading method according to any one of 5 above. 19. A control program executed by an image reading device for reading image data from a document by performing main scanning and sub-scanning of the document, storing the read image data in a memory, and outputting the image data. The capacity of
The free space of the memory is measured based on the detected capacity of the memory, the write amount of image data to the memory, and the read amount of image data from the memory, and the measured free space is the first predetermined value. A control program having a content of decelerating the sub-scanning speed when the value becomes less than or equal to a value, and accelerating the sub-scanning speed when the free space becomes equal to or more than a second predetermined value.