JP2002300353A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that controls a read rate of an original according to the performance of a transfer means. SOLUTION: The image reader including a read means that acquires image data from an original, a moving means that moves the original or the read means, a storage means that stores image data acquired by the read means, a transfer means that transfers the image data stored in the storage means to an external device, and a means that controls an image data acquisition speed of the read means according to the capacity of data stored in the storage means, is provided with a means that changes an image data acquisition rate of the read means in response to the data transfer rate of the transfer means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for acquiring image data from a document, and more particularly to an image reading apparatus for changing a reading speed according to a data transfer speed.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus has been used for an image input unit such as a scanner, a copier, and a facsimile. Generally, an image reading apparatus irradiates a document with light and converts the detected reflected light into an electric signal to generate image data from the document.

FIG. 14 shows a configuration example of a conventional image reading apparatus. The image reading device 500 includes a CPU 501, an R
AM 502, ROM 503, bus 504, image memory 5
05, a transfer unit 506, and an image reading unit 507. The CPU 501 controls each unit of the device based on a control program stored in the ROM 503 and data stored in the RAM 502. The RAM 502 stores setting conditions. The ROM 503 stores a control program. The bus 504 transmits an instruction from the CPU 501 to each unit via an intermediary. The image memory 505 stores the image data read by the image reading unit 507. Transfer unit 50
Reference numeral 6 transfers the image data to an external device or an output unit or storage unit (not shown). The image reading unit 507 includes a lamp, a mirror, a photodetector, a photoelectric element, and the like.
Acquire image data from a manuscript. Memory controller 5
08 monitors the amount of data in the image memory 505 and notifies the CPU 501 of the amount of data by an interrupt signal.

Next, the operation of the image reading apparatus 500 will be described. The image reading unit 507 reads a document in accordance with an instruction from the CPU 501 and generates image data. CP
U501 stores the generated image data in the image memory 505.
To memorize. Thereafter, the transfer unit 506 stores the image memory 50
5 is transferred.

In the above-described image reading apparatus, the document reading speed and the image data transfer speed are not always the same. For this reason, when the original reading speed is faster than the transfer speed of the image data, the image memory 505 becomes full,
Image data cannot be stored. To prevent this, the CPU 501 controls the image reading unit 507 to temporarily stop the reading operation of the document when the usage amount of the image memory 505 becomes equal to or more than the predetermined upper limit value.

[0006] When the usage amount of the image memory 505 exceeds a predetermined upper limit, the memory controller 508 determines whether or not the CP is used.
A stop request signal is transmitted to U501. Upon receiving the stop request signal, the CPU 501 causes the image reading unit 507 to temporarily stop the reading operation of the document. During this time, the transfer unit 50
6 continues the transfer of the image data. After the usage of the image memory 505 becomes equal to or less than a predetermined lower limit, the CPU 501
The document reading unit 507 restarts the document reading operation.

[0007]

However, when the reading operation of the document is temporarily stopped, mechanical vibration occurs when the reading operation is stopped and / or when the reading operation is restarted. This vibration causes image deterioration such as occurrence of a joint in the image data. Further, since the data transfer speed differs depending on the type of transfer means, the number of times the document reading operation is temporarily stopped differs even when reading the same document. For this reason, the quality of image data differs depending on the type of transfer means used.

The present invention has been made in view of such a problem, and has as its object to provide an image reading apparatus that controls a document reading speed according to a data transfer speed of a transfer unit. It is another object of the present invention to reduce a difference in quality of image data due to a difference in data transfer speed of a transfer unit.

[0009]

According to an aspect of the present invention, there is provided an image reading apparatus for reading an original, generating image data, storing the image data, and storing the image data. An image reading apparatus having a transfer unit that transfers image data to an external device, further comprising a speed setting unit that sets a document reading speed according to a data transfer speed of the transfer unit.

According to a second aspect of the present invention, there is provided an image reading apparatus for reading an original, generating image data, storing the image data, and transferring the image data stored in the storage means to an external device. An image reading apparatus comprising: means for setting a transfer means to be used; and speed setting means for setting a document reading speed according to a data transfer rate of the transfer means to be used. And

According to a third aspect of the present invention, there is provided the image reading apparatus according to the first or second aspect, wherein the speed setting means is provided when the data amount stored in the storage means is equal to or larger than a predetermined data amount.
The document reading speed is set to be equal to or lower than the data transfer speed.

According to a fourth aspect of the present invention, there is provided the image reading apparatus according to the first or second aspect, wherein the speed setting means reads the original so that the data amount of the image data stored in the storage means is equal to or less than a predetermined data amount. It is characterized by setting the speed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the configuration of the image reading apparatus according to the present embodiment. The image reading apparatus 100 according to the present embodiment includes a pressure plate 2, a contact glass 3, an irradiation lamp 4, mirrors 5 to 7, a condenser lens 8, a CCD (Char
ge Coupled Device) 9, traveling bodies 10 and 11, and traveling body motor 12.

The pressure plate 2 presses the original 1 against the contact glass 3. The contact glass 3 transmits the light of the irradiation lamp 4 to the document 1. The irradiation lamp 4 irradiates the document 1 via the contact glass 3 in a narrow band shape in the main scanning direction (B direction). Mirror 5, mirror 6, and mirror 7 change the direction of the reflected light from document 1. The condenser lens 8
Light reflected from the document 1 is collected and incident on the CCD 9. The CCD 9 converts the received light into an electric signal corresponding to the received light intensity. The traveling body motor 12 and the traveling body 11 are moved so that the traveling body 10 and the traveling body 11 can move in the sub-scanning direction (A direction).
Are connected by pulleys or wires. The traveling body motor 12 is, for example, a stepping motor.
The traveling body 11 is moved and scanned in the sub-scanning direction.

Next, an electrical system for controlling the image reading apparatus 100 will be described. FIG. 2 is a block diagram showing a configuration of an electrical system of the image reading apparatus 100. The electrical system of the image reading apparatus 100 includes a CPU 20, a CPU bus 21, an inverter 2
2, motor driver 23, image processing unit 24, image memory 25, memory controller 26, transfer unit 28, EEPR
OM 50, ROM 51, RAM 52, and display unit 60
Is included.

The CPU 20 controls the entire apparatus based on a control program stored in the ROM 51 and data stored in the EEPROM 50 and the RAM 52. CPU
The bus 21 transmits the command from the CPU 20 to each unit through the bus. The inverter 22 controls the light amount of the irradiation lamp 4. The motor driver 23 controls driving of the traveling body motor 12. The image processing unit 24 converts the analog signal acquired from the CCD 9 into a digital signal by performing gain adjustment and the like. Further, it performs image processing such as gamma correction and MTF correction, and outputs a video signal together with a page synchronization signal, a line synchronization signal, and an image clock. Image memory 25
Is image storage means for storing image data. The memory controller 26 monitors the amount of data in the image memory 25 and notifies the CPU 20 of the amount of data by an interrupt signal. The transfer unit 28 transfers the acquired image data to the external device 29.

An EEPROM (Electrically Erasable an
d Programmable ROM) 50 stores operation history information of each part of the image reading apparatus 100 such as the number of operations of the CCD 9 and adjustment setting values. The ROM 51 stores a control program of the image reading apparatus 100 and the like. The RAM 52 stores control data of the image reading device 100.

Next, the operation of the image reading apparatus 100 will be described. FIG. 3 shows a flow of the operation of the image reading apparatus 100. When the apparatus is started in response to a start instruction from the user, the CPU 20 controls the inverter 22 and the motor driver 23 to start reading a document on the CCD 9 (step S101). Thus, the image processing unit 24 generates image data. At this time, the CPU 20 controls the output clock to the motor driver 23 and
The original is read by the CCD 9 at a speed corresponding to the data transfer speed.

For example, when the normal reading speed is slower than the transfer speed, the CPU 20 operates at the normal reading speed at CC speed.
The document is read by D9. On the other hand, if the normal reading speed is higher than the transfer speed, the CPU 20 decelerates
The manuscript is read by CD9. The degree of deceleration is arbitrary as long as the document reading speed is equal to or higher than the transfer speed.

The CPU 20 causes the image memory 25 to store the image data generated by the image processing section 24. further,
The transfer unit 28 starts transferring the image data to the external device 29 (Step S102).

If the reading operation of the original is not completed (step S103 / No), the memory controller 26
Confirms the amount of data in the image memory 25 (step S
104). If the state is not the near full state (the state where the memory usage is equal to or more than the predetermined upper limit value) (step S104 / N
o), the process proceeds to step S103 and the image reading apparatus 100
The document reading operation and the transfer of image data are continued until the document reading operation is completed or the image memory 25 is in the near full state. The near full state indicates a case where the memory usage of the image memory 25 has become larger than a predetermined upper limit, and is a state in which the image memory 25 has almost no capacity for storing image data.

When the image memory 25 is in the near full state (step S104 / Yes), the memory controller 26 sends a stop request signal to the CPU 20. CPU
The motor driver 23 receives the stop request signal.
The reading operation of the original is stopped by stopping the output of the output clock to stop the traveling motor 12 (step S).
105). At this time, the CPU 20 controls the motor driver 23 so that the traveling body motor 12 stops after smoothly decelerating.
It is good to control the output to.

The transfer unit 28 transfers the image data to the external device 29 even after the reading operation is stopped. That is, the transfer unit 28 always transfers the image data to the external device 29 regardless of the reading operation. When the image memory 25 is in the empty state (the state where the memory usage is equal to or less than the predetermined lower limit) (step S106 / Yes), the memory controller 26 transmits a drive request signal to the CPU 20. The empty state indicates a case where the memory usage of the image memory 25 has become smaller than a predetermined lower limit, and is a state in which image data is hardly stored in the image memory 25.

When the CPU 20 receives the drive request signal,
The output to the motor driver 23 is controlled to restart the original reading operation (Step S107), and Step S10
Proceed to 3. Thereafter, the image reading apparatus 100 proceeds from step S103 to step S10 until reading of the original is completed.
7 is repeated. When the reading operation of the original is completed (Step S103 / Yes), the transfer unit 28 transfers all the image data remaining in the image memory 25 to the external device 29.
(Step S108 / Yes), and the process ends.

[Second Embodiment] Next, a description will be given of a second embodiment in which the image reading apparatus according to the present invention is suitably implemented.
Is the same as the image reading apparatus 100 according to the first embodiment shown in FIG.

Next, an electrical system for controlling the image reading apparatus 100 will be described. FIG. 4 is a block diagram showing a configuration of an electrical system of the image reading apparatus 100. The electrical system of the image reading apparatus 100 is almost the same as the electrical system of the first embodiment shown in FIG.
It has an SI controller 30 and a network controller 40. In the present embodiment, a case in which two types of transfer units are provided will be described as an example. However, the present invention is not limited to this, and three or more types of transfer units may be provided.

The SCSI controller 30 transfers the image data stored in the image memory 25 to the external device 31 based on the SCSI standard. Network controller 40
Transfers the image data stored in the image memory 25 to the external device 41 via the network.

Next, the fact that the amount of memory used in the image memory 25 when reading a document differs depending on the transfer means used will be described. Here, the memory capacity of the image memory 25 is 32 MB, the size of the image data is 200 MB, the document reading speed is 20 MB / s, and the SCSI controller 30
The data transfer speed of the network controller 40 is 10 MB / s, and the data transfer speed of the network controller 40 is 2 MB / s.

FIGS. 5 and 6 show the relationship between the time from the start of document reading and the memory usage under the above conditions. FIG. 5 shows the relationship between the time from the start of document reading and the amount of memory used when image data is transferred using the SCSI controller 30. FIG. 6 shows the relationship between the time from the start of document reading and the memory usage when image data is transferred using the network controller 40. The intermittent stop in the drawing indicates a state in which the reading operation of the document is temporarily stopped.

Under the above conditions, the transfer of image data is
Intermittent stoppage occurs three times when using the SI controller 30 and five times when using the network controller 40. As described above, when the reading operation of the document is temporarily stopped, mechanical vibration occurs when the traveling body motor 12 stops and when it is driven again. For this reason, a seam is generated in the image data and the image is deteriorated. Therefore, it is desirable that the number of intermittent stops be small, and under the above conditions, S
When the image data is transferred using the CSI controller 30, the deterioration of the image data is reduced.

FIG. 7 shows the relationship between the time from the start of document reading and the memory usage when the document reading speed is set to 6.8 MB / s when image data is transferred using the network controller 40. . The conditions other than the document reading speed are the same as described above. in this case,
The number of occurrences of the intermittent stop can be reduced from five to four. For this reason, the difference from the image quality when transferring image data using the SCSI controller 30 is reduced.

Next, the operation of the image reading apparatus 100 will be described. FIG. 8 shows a flow of the operation of the image reading apparatus 100. The CPU 20 sets a transfer unit for transferring image data (step S201). As a setting method of the transfer means, there is a method in which the user arbitrarily selects the transfer means, a method in which priorities are set in advance to the transfer means, and the like. Here, a case where the network controller 40 is set as the transfer unit will be described as an example. The CPU 20 sets the document reading speed according to the set transfer means (step S202). Here, the document reading speed is set to 6.8 MB / s.

Next, the CPU 20 controls the inverter 22 and the motor driver 23 to start reading the original by the CCD 9 (step S203). Thus, the image processing unit 24 generates image data. At this time, CPU2
0 is the reading speed set in step S202 (6.
The original is read by the CCD 9 at 8 MB / s). Also,
The CPU 20 causes the image memory 25 to store the image data generated by the image processing unit 24. Further, the SCSI controller 30 starts transferring the image data to the external device 31 (step S204). The following step S20
Operations from 5 to S210 are the same as steps S103 to S108 of the operation of the first embodiment shown in FIG.

FIG. 9 shows a flow of processing for setting the document reading speed. This is a process corresponding to step S202 in FIG. The CPU 20 determines that the set transfer means is SC
It is confirmed whether or not it is the SI controller 30 (step S2021). If the set transfer means is the SCSI controller 30 (step S2021 / Ye)
s), the CPU 20 sets the document reading speed to 20 MB / s
(Step S2022). On the other hand, when the set transfer unit is the network controller 40 (step S2021 / No), the CPU 20 sets the document reading speed to 6.8 MB / s (step S20).
23). By setting the document reading speed in this way, differences in image quality due to differences in transfer means can be corrected.

[Third Embodiment] Next, a description will be given of a third embodiment in which the image reading apparatus according to the present invention is suitably implemented. The image reading device according to the present embodiment is the same as the image reading device 100 according to the first embodiment shown in FIG. The electrical system for controlling the image reading apparatus 100 is the image reading apparatus 1 according to the second embodiment shown in FIG.
00 is the same as the electrical system.

FIG. 10 shows an example of the relationship between the time from the start of document reading and the memory usage of the image memory 25. At this time, the network controller 40 is used as the transfer means. The reading conditions are as follows: the memory capacity of the image memory 25 is 32 MB;
The document reading speed is 0 MB, the document reading speed is 6.8 MB / s, the data transfer speed of the network controller 40 is 2 MB / s, and the document reading speed during deceleration is 1 MB / s.

As shown in the drawing, under this condition, even if the used amount of the image memory 25 becomes nearly full, the CPU 20 does not stop the reading operation of the original, but continues at a reduced speed. Therefore, unlike the case where the document reading operation is temporarily stopped, there is no mechanical vibration caused by stopping and re-driving the traveling body motor 12. In the present embodiment, by controlling the document reading speed in this way, the deterioration of image data when reading a document is reduced.

Next, the operation of the image reading apparatus 100 will be described. FIG. 11 is a flowchart showing the flow of the operation of the image reading apparatus 100. The CPU 20 sets the transfer means used for transferring the image data (step S30).
1). Here, the network controller 4 is used as the transfer means.
The case where 0 is set is taken as an example. As a method of setting the transfer means, there is a method in which the user arbitrarily selects the transfer means, a method in which priorities are set in advance to the transfer means, and the like. The CPU 20 sets the document reading speed according to the set transfer means (step S302). Here, the reading speed is set to 6.8 MB / s.

Next, the CPU 20 controls the inverter 22 and the motor driver 23 to start reading the original by the CCD 9 (step S303). Thus, the image processing unit 24 generates image data. At this time, CPU2
0 is the reading speed set in step S302 (6.
The original is read by the CCD 9 at 8 MB / s). Also,
The CPU 20 causes the image memory 25 to store the image data generated by the image processing unit 24. Further, the network controller 40 starts transferring the image data to the external device 41 (Step S304).

If the document reading operation has not been completed (step S305 / No), the memory controller 26
Confirms the amount of data in the image memory 25 (step S
306). If the state is not near full (step S30)
6 / No), the process proceeds to step S305, and the image reading apparatus 10
0 indicates whether the reading operation of the original is completed or not.
The reading operation of the document and the transfer of the image data are continued until the state becomes near full.

When the image memory 25 is in the near full state (step S306 / Yes), the memory controller 26 sends a deceleration request signal to the CPU 20. CPU
20 receives the interrupt signal, the motor driver 23
Then, the document reading speed is reduced to 1 MB / s by lowering the output clock to 1 MB / s by lowering the speed of the traveling motor 12 (step S307).

The network controller 40 continuously transfers the image data to the external device 41 even after the reading speed is reduced. When the image memory 25 is in the empty state (step S308 / Yes), the memory controller 2
6 transmits a speed return signal to the CPU 20. CPU2
When the speed recovery signal is received, control of the output to the motor driver 23 returns the original reading speed to the original speed (step S309), and the process proceeds to step S303. Thereafter, the image reading apparatus 100 repeatedly executes Steps S305 to S309 until the reading operation of the document is completed. If the reading operation of the original is completed (step S305 / Yes), the network controller 40 transfers all the image data remaining in the image memory 25 to the external device 41 (step S310 / Ye).
s), end the process.

[Fourth Embodiment] Next, a description will be given of a fourth embodiment in which the image reading apparatus according to the present invention is suitably implemented. The image reading device according to the present embodiment is the same as the image reading device 100 according to the first embodiment shown in FIG. The electrical system for controlling the image reading apparatus 100 is the image reading apparatus 1 according to the second embodiment shown in FIG.
00 is the same as the electrical system.

FIG. 12 shows the relationship between the time from the start of document reading and the amount of memory used in the image memory 25. here,
The memory capacity of the image memory 25 is 32 MB, the size of image data is 200 MB, the data transfer speed of the SCSI controller 30 is 10 MB / s, and the data transfer speed of the network controller 40 is 2 MB / s. The original reading speed is 1 when the SCSI controller 30 is used.
1.91 MB / s, and 2.38 MB / s when the network controller 40 is used.

As shown in the figure, if the original is read under such conditions, the image memory 25 does not become near full regardless of which of the SCSI controller 30 and the network controller 40 is set as the transfer means. For this reason,
Intermittent stop can be prevented from occurring. In the present embodiment, by controlling the document reading speed in this way, the deterioration of image data when reading a document is reduced.

Next, the operation of the image reading apparatus 100 will be described. FIG. 13 shows a flow of the operation of the image reading apparatus 100. The CPU 20 sets the transfer means for either the SCSI controller 30 or the network controller 40 based on the user's input (step S401).
When the user sets the SCSI controller 30 as the transfer unit (step S402 / Yes), the CPU 20 sets the document reading speed to 10.33 MB / s (step S403). On the other hand, the network controller 40
Is set as the transfer means (step S402 / N
o), the CPU 20 sets the document reading speed to 2.38 MB /
s (Step S404). Here, the case where the network controller 40 is set as the transfer unit will be described as an example. Therefore, the reading speed is 2.38 MB.
/ S.

Next, the CPU 20 controls the inverter 22 and the motor driver 23 to cause the CCD 9 to start reading the original. As a result, the image processing unit 24 generates image data (Step S405). At this time, CPU2
0 is the previously set reading speed (2.38 MB / s)
Causes the CCD 9 to read the original. The CPU 20
Causes the image memory 25 to store the image data generated by the image processing unit 24. Further, the network controller 40 starts transferring the image data to the external device 41 (Step S406). When the original reading operation is completed (step S407 / Yes), the network controller 40 transfers all the image data remaining in the image memory 25 to the external device 41 (step S408 / Y).
es), the process ends.

[0048]

As is clear from the above description, the image reading apparatus according to the first aspect can change the document reading speed of the reading means in accordance with the data transfer speed of the transfer means. For this reason, the number of intermittent stops occurring during the document reading operation can be reduced. Thus, it is possible to reduce the deterioration of the image data due to the mechanical vibration at the time of resuming the original reading.

The image reading apparatus according to the second aspect has a plurality of types of transfer means, and can change the original reading speed in accordance with the data transfer speed of the transfer means used. For this reason, it is possible to correct a difference in quality of image data due to a difference in transfer means used. Further, since the number of intermittent stops during the document reading operation can be reduced, deterioration of image data can be reduced.

According to a third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the original reading speed is set to be lower than the data transfer speed of the transfer unit when the storage unit is in a near full state. it can. This can prevent the occurrence of intermittent stop during the document reading operation. For this reason, it is possible to prevent the image data from deteriorating due to the mechanical vibration at the time of resuming the original reading in the intermittent stop.

According to a fourth aspect of the present invention, in the image reading apparatus according to the first or second aspect, the original reading speed can be set so that the storage means does not become in the near full state. For this reason, the image reading apparatus can read the original at a constant speed from the start to the end of the original reading to generate the image data. As a result, it is possible to eliminate the deterioration of the image data due to the change in the document reading speed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an image reading apparatus according to a first embodiment to which the present invention has been applied.

FIG. 2 is a block diagram illustrating a configuration of an electrical system of the image reading apparatus according to the first embodiment.

FIG. 3 is a flowchart illustrating a flow of an operation of the image reading apparatus according to the first embodiment.

FIG. 4 is a block diagram illustrating a configuration of an electrical system of an image reading apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating the relationship between the time from the start of document reading and the amount of image memory used when a SCSI controller is set as a transfer unit.

FIG. 6 is a diagram illustrating the relationship between the time from the start of document reading and the amount of image memory used when a network controller is set as a transfer unit.

FIG. 7 is a diagram illustrating the relationship between the time from the start of reading and the amount of image memory used when the reading speed is set to 6.8 MB / s when the network controller is set as the transfer unit.

FIG. 8 is a flowchart illustrating a flow of an operation of the image reading apparatus according to the second embodiment.

FIG. 9 is a flowchart illustrating an example of a document reading speed setting operation according to the second embodiment.

FIG. 10 is a diagram showing the relationship between the time from the start of document reading and the amount of image memory used in the image reading apparatus according to the third embodiment to which the present invention is applied.

FIG. 11 is a flowchart illustrating a flow of an operation of the image reading apparatus according to the third embodiment.

FIG. 12 is a diagram showing the relationship between the time from the start of document reading and the amount of image data memory used in the image reading apparatus according to the fourth embodiment to which the present invention is applied.

FIG. 13 is a flowchart illustrating a flow of an operation of the image reading apparatus according to the fourth embodiment.

FIG. 14 is a block diagram illustrating a configuration example of an image reading apparatus according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original 2 Pressure plate 3 Contact glass 4 Irradiation lamp 5, 6, 7 Mirror 8 Condensing lens 9 CCD 10, 11 Traveling body 12 Traveling body motor 20 CPU 21 CPU bus 22 Inverter 23 Motor driver 24 Image processing unit 25 Image memory 26 Memory Controller 28 Transfer unit 29, 31, 41 External device 30 SCSI controller 40 Network controller 50 EEPROM 51 ROM 52 RAM 60 Display unit

Claims (4)

[Claims] 1. An image reading apparatus comprising: means for reading a document to generate image data; storage means for storing the image data; and transfer means for transferring the image data stored in the storage means to an external device. An image reading apparatus, further comprising a speed setting unit that sets a document reading speed according to a data transfer speed of the transfer unit. 2. An image comprising: means for reading an original to generate image data; storage means for storing the image data; and at least two transfer means for transferring the image data stored in the storage means to an external device. An image reading apparatus, further comprising: means for setting the transfer means to be used; and speed setting means for setting a document reading speed in accordance with a data transfer rate of the transfer means to be used. Reader. 3. The method according to claim 2, wherein the speed setting unit is configured to determine whether the data amount stored in the storage unit is equal to or more than a predetermined data amount.
3. The image reading apparatus according to claim 1, wherein the document reading speed is set to be equal to or lower than the data transfer speed. 4. The apparatus according to claim 1, wherein said speed setting means sets said document reading speed such that a data amount of said image data stored in said storage means is equal to or less than a predetermined data amount. The image reading device according to claim 1.