JP2000032244A - Image reader and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of improving throughput with an inexpensive configuration. SOLUTION: The image data of both front and back surfaces obtained by read scanning by both surface read means 11 and 23 are respectively temporarily stored in two image storage means 39 and 48 as a general rule. In this case, in the case that the total data amount of the image data of both front and back surfaces obtained by a data amount obtaining means is equal to or less than the total storage capacity of the two image storage means 39 and 48 and the data amount of one image data exceeds the storage capacity of one corresponding image storage means 39, the storage destination of the excess of the image data is switched to the other image storage means 48 by a storage destination switching means 50 and the excess of the image data is stored in the other image storage means 48. Thus, since the need of intermittently performing the read scanning is eliminated, the throughput is improved with a inexpensive configuration.

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 capable of reading both sides of a document image, and an image forming apparatus such as an image scanner, a digital copier and a digital facsimile apparatus having the image reading apparatus.

[0002]

2. Description of the Related Art Generally, when an image reading apparatus of this type is provided with a double-sided simultaneous reading function, a DRA which is a dedicated storage means for each of read images on both sides of a read original is provided.
Many have an image memory such as M.

In this case, the amount of image data obtained by scanning the original is not increased beyond the memory capacity of the image memory.
A SIBC (Scanner Image Buffer Controller) causes the image reading apparatus to execute an intermittent operation for intermittently performing the reading scanning process while detecting the amount of image data during reading scanning of the document. For example, if the memory capacity of the image memory is 2
In the case of Mbyte, the image data amount is 2 during image reading.
When it is about to exceed Mbyte, the reading scanning process is temporarily stopped. Here, a stepping motor is generally used as a drive motor of this type of image reading apparatus, and cannot be stopped instantaneously due to the nature of the motor. A control method of gradually lowering the speed and stopping the operation is adopted. Therefore, instead of temporarily stopping after the image data amount has completely reached 2 Mbytes, the image data is temporarily stopped at a near full point (near full point) with some margin in the memory capacity of the image memory. Further, after the suspension, when the memory capacity of the image memory has a margin (near-full release point) when the image data is transferred to the external device, the driving of the motor is resumed by releasing the suspension, An intermittent operation of the reading scanning process is performed. Since the motor cannot be moved instantaneously due to the nature of the motor, a control method called "through-up" is employed to gradually increase the speed and restart the scanning process.

[0004]

By the way, as the storage capacity of each image memory for each of the front and back sides is larger, the above-described intermittent operation is less likely to occur, and the throughput as the image reading apparatus is improved.

[0005] However, increasing the storage capacity of each image memory increases the production cost and the price of the apparatus.

An object of the present invention is to provide an image reading apparatus capable of improving the throughput with a low-cost configuration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus having an image reading apparatus capable of improving the throughput with an inexpensive configuration.

[0008]

According to the first aspect of the present invention, there is provided an image reading apparatus which reads and scans both a front surface image and a back surface image of a document to obtain image data of both sides, respectively. Two image storage means for temporarily storing the image data on the front and back sides obtained by the double-side reading means, and storage destination switching means for switching the storage destination of the image data on the front and back sides stored in these two image storage means. A data amount acquiring unit for acquiring the data amount of the image data on both the front and back sides; a total data amount of the image data on the front and back surfaces acquired by the data amount acquiring unit; and a total storage capacity of the two image storage units. And a total storage capacity of the two image storage units, wherein the total data amount of the image data on the front and back surfaces acquired by the data amount acquisition unit is two. Below, when the data amount of one image data exceeds the storage capacity of the corresponding one image storage unit, the storage destination for the excess of the one image data is stored in another image storage unit by the storage destination switching unit. Storage control means for switching to and storing the image data; and data transfer means for sequentially transferring each image data stored in the two image storage means to an external device.

Therefore, the image data on the front and back sides obtained by the reading scan by the double-side reading means is temporarily stored in each of the two image storage means in principle. Here, the total data amount of the image data on the front and back sides acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units, and the data amount of one image data corresponds to one image storage unit When the storage capacity of the image data exceeds the storage capacity, the storage destination of the excess of the one image data is switched to another image storage means by the storage destination switching means, and the excess of the one image data is stored in the other image storage means. Is stored. Accordingly, provided that the total data amount of the image data on the front and back sides acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units, the data amount of one image data corresponds to Even if the storage capacity of the image storage means is exceeded, the storage destination is switched to another image storage means, so that it is not necessary to intermittently perform the scanning by the double-sided reading means.

According to a second aspect of the present invention, there is provided an image reading apparatus which reads and scans both a document front side image and a document back side image to obtain image data of both front and back sides, and an image reading apparatus obtained by the both side reading section. Two image storage means for temporarily storing the image data on the front and back sides, storage destination switching means for switching the storage destination of the image data on the front and back sides stored in these two image storage means, and the image on the front and back sides Data amount acquiring means for acquiring the data amount of data, and comparing means for comparing the total data amount of the image data on the front and back surfaces acquired by the data amount acquiring means with the total storage capacity of the two image storage means. Wherein the total data amount of the image data on the front and back surfaces acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units; When the data amount of the image data exceeds the storage capacity of the corresponding one image storage unit, the total of the two image storage units is adjusted according to the ratio of the data amount of one image data to the data amount of the other image data. Storage control means for distributing a storage capacity, switching the storage destination of the excess of one image data to a storage area of one image data distributed to another image storage means by the storage destination switching means, Data transfer means for sequentially transferring each image data stored in the two image storage means to an external device.

Therefore, the image data of the front and back sides obtained by the reading scan by the both-side reading means is temporarily stored in each of the two image storage means in principle. Here, the total data amount of the image data on the front and back sides acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units, and the data amount of one image data corresponds to one image storage unit If the storage capacity exceeds the storage capacity of one image data, the total storage capacity of the two image storage means is distributed according to the ratio of the data amount of one image data to the data amount of the other image data. Is switched to another image storage means by the storage destination switching means, and the excess of one image data is stored in the storage area of one image data distributed to the other image storage means. . Accordingly, provided that the total data amount of the image data on the front and back sides acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units, the data amount of one image data corresponds to Even if the storage capacity of the image storage means is exceeded, the one image data of the other image storage means distributed according to the ratio of the data amount of one image data to the data amount of the other image data Since the storage destination is switched to the storage area, there is no need to intermittently perform scanning by the double-sided scanning unit.

The invention described in claim 3 is the first or second invention.
In the image reading device described above, when the total data amount of the image data on the front and back surfaces acquired by the data amount acquisition unit is equal to or greater than the total storage capacity of the two image storage units, the storage capacity of each image storage unit is A two-division means for switching storage destinations by the storage destination switching means so as to have a storage capacity corresponding to a capacity obtained by dividing the total storage capacity of the two image storage means into two, and a total storage capacity corresponding to a half-divided capacity Intermittent reading means for intermittently repeating the double-side reading means so that the storage capacity of each image storage means does not become full,
Is provided.

Therefore, if the total data amount of the image data on the front and back sides obtained by the data amount obtaining means is equal to or larger than the total storage capacity of the two image storage means, the storage capacity of each image storage means becomes two images. The storage destination is switched by the storage destination switching unit so that the total storage capacity of the storage unit becomes a storage capacity corresponding to the divided capacity of two, and the storage capacity of each image storage unit corresponding to the divided capacity of the total storage capacity of the storage means The reading scan by the double-sided reading means is intermittently repeated so that is not full. Thereby, for example, when the storage capacity of one image storage unit is small and the storage capacity of the other image storage unit is large, the storage capacity is determined based on the storage capacity corresponding to the divided storage capacity of the two image storage units. Since the intermittent operation occurs, the frequency of the intermittent operation is less than that of the intermittent operation based on the storage capacity of one image storage unit having a small storage capacity.

According to a fourth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to third aspects, and an image corresponding to the image data transmitted from the image reading apparatus is subjected to an electrophotographic process. And an image printing device for printing.

Therefore, under the condition that the total data amount of the image data on the front and back sides acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units, reading scanning and data transfer by the double-side reading unit are performed. Since the data transfer by the means is continuously executed, the printing operation is executed without waste.

[0016]

FIG. 1 shows a first embodiment of the present invention.
A description will be given based on FIG. The present embodiment is applied to a scanner of a digital copying machine which is an image forming apparatus as an image reading apparatus.

FIG. 1 is a front view schematically showing the structure of the scanner unit 1. As shown in FIG. As shown in FIG. 1, a scanner unit 1 includes an ADF (Automatic Document Feeder) 2, and a front-side reading unit 3 that allows a user to select between a fixed document mode and a document transport mode, and a back-side reading unit provided in the ADF 2. 4
, And both sides can be read simultaneously in the document transport mode.

First, the configuration of the front side reading unit 3 will be described. The front surface reading unit 3 has a contact glass G on which a document to be read is placed, and a first traveling body on which a reflecting mirror 5 and a light source 6 are mounted is provided at a position facing the contact glass G from below. 7 is provided movably in the sub-scanning direction A. In the reflected light path of the first traveling body 7, a second traveling body 9 whose optical path is turned by two reflecting mirrors 8 is provided movably in the sub-scanning direction A. Is a CCD (Charge Coupled Device) 1 functioning as a part of double-sided reading means via an imaging lens 10.
1 is provided.

A traveling body motor 12 composed of a stepping motor is connected to the first traveling body 7 and the second traveling body 9 by a pulley, a wire, or the like. It is movable. By moving the two traveling bodies 7 and 9 in this manner, the read image of the read original placed on the contact glass G is read and scanned by the CCD 11.

The scanning of the original to be read by the front surface reading unit 3 is executed under the setting of the book mode which is the original fixed mode. The ADF mode is also set as an operation mode so as to be switchable on an operation panel P (see FIG. 2) described later. Under the setting of the ADF mode, as shown by a broken line at the right end of the drawing, the two traveling bodies 7 and 9 are moved to the front stop reading position 1 as the home position.
The reading image is read and scanned by the CCD 11 by sequentially transporting the reading document by the ADF 2 in the state of being set to 3.

The ADF 2 includes a document tray 14, a pickup roller 15, a pair of registration rollers 16, a transport drum 17, a pair of transport rollers 18, a pair of discharge rollers 19, and the like. The read original is sequentially conveyed in the sub-scanning direction A so as to pass through, and is discharged to the discharge tray 20. The paper discharge tray 20 includes a document pressure plate 21.
The original pressure plate 21 is openable and closable with respect to the contact glass G. The pickup roller 15, the registration roller 16, the transport drum 17, the transport roller 18, and the paper discharge roller 19 of the ADF 2 have a paper feed motor 33 composed of a stepping motor (see FIG. 2).
Are connected by a gear train or the like.

An operation panel P having a keyboard and a display is provided on the outer surface of the front surface reading unit 3 (see FIG. 2).
Is provided. The keyboard of the operation panel P is provided with an operation mode key, a start key, an abort key, and other various keys (not shown), as well as a document size designation key k (see FIG. 2) for designating the size of the read document. I have. The document size designation key k is used to designate not only the size of the read document but also its image density.

Next, the configuration of the back side reading section 4 will be described. The back-side reading unit 4 includes a contact-type image sensor 23 functioning as a part of a two-sided reading unit and a white image at a back-side reading position 22 set downstream of the conveyance drum 17 of the ADF 2 in the document conveyance direction and in front of the conveyance roller 18. Roller 2
4 are arranged to face each other across the transport path. Here, the contact image sensor 23 is
It reads the original surface (back surface) opposite to the CD 11 side, and is provided downward on the upper side of the transport path, and integrates a lamp that irradiates the original surface, a 1 × imaging lens array, and a sensor array. This is a unit-size photoelectric conversion element configured by: White roller 24 located on the opposite side of the transport path
Is also used as a white member for shading correction at the time of reading by the contact image sensor 23.

Further, a reading control unit 25 which is a substrate which includes a microcomputer 29 (see FIG. 2) for electrically controlling each unit and which is a component of an electric system is provided below the inside of the scanner unit 1. Next, the electrical connection of each unit built in the scanner unit 1 will be described below with reference to FIG. A microcomputer 29 mainly including a CPU 26 for centrally controlling each unit, a ROM 27 for storing fixed data such as a control program, and a RAM 28 for rewritably storing various data.
Controls the operation timing of the light source 6 and the traveling body motor 12 through the SDU (Scanner Driving Unit) 30 by drive pulse control. Further, when various keys on the operation panel P are pressed, the microcomputer 29 detects the pressing of the keys via the SDU 30 and outputs a signal corresponding to the keys. Further, an ADU (ADF Driving Unit) 32 connected to an MBU (Mother Board Unit) 31 has a function of relaying the power supply of electrical components used for the ADF 2, and this ADF
The microcomputer 29 controls the operation timing of the sheet feeding motor 33 of the ADF 2 through the DU 32 by drive pulse control.

The light source 6 is supplied by power supply from the SDU 30.
And the traveling body motor 12 to drive the SBU
(Sensor Board Unit) Reflected light from the surface of the read original which is incident on the CCD 11 on the CCD 34 is converted into analog image data having a voltage value corresponding to the light intensity in the CCD 11, and converted into odd-numbered bits and even-numbered bits. The output is split into two. This analog signal is sequentially output to the MBU 31,
The dark potential portion is removed by an AHP (Analog data Handling Peripheral) 35, the odd bits and the even bits are combined, the gain is adjusted to a predetermined amplitude, and then input to the A / D converter 36 to be converted into a digital signal. . This M
The surface image data digitized by the BU31 is stored in the CPU.
26, ROM 27, and RAM 28 are mounted on the SCU (Sc
After the shading correction, the gamma correction, the MTF correction, and the like are performed by the NIPU 38 on the inner control unit 37, the binarization processing is performed. The binarized image data is output as a video signal together with a page synchronization signal, a line synchronization signal, and an image clock.

The video signal output from the NIPU 38 is a SIBC (Sc) which is a surface reading memory controller for managing a DRAM (Dynamic Random Access Memory) 39 which is a surface image memory functioning as image storage means.
Anner Image Buffer Controller) 40 is stored in the DRAM 39 in principle as surface image data. Here, the memory capacity of the DRAM 39 is 2 Mbytes, and the capacity is set in the SIBC 40 as a storable capacity. The SIBC 40 is a DRAM that stores surface image data associated with the scanning of the surface of the document to be read by the CCD 11.
The amount of data stored in the memory 39 is determined by the storage capacity of the DRAM 39 set in the SIBC 40 (initial setting is 2
Mbyte). Then, the surface image data stored in the DRAM 39 is transferred from the SIBC 40 to a printer unit (image printing device) 42 of a digital copying machine, which is an external device, via a SCSI controller 41 functioning as a data transfer unit.

On the other hand, the analog image signal on the back side of the read original, which has been photoelectrically converted by the contact type image sensor 23, is RSBU.
(Reverse Sensor Board Unit) 43 is converted into a digital image signal by AHP 44 and A / D converter 45. The back side image data digitized by the RSBU 43 is binarized by the NIPU 47 on the RCU 46 and output as a video signal.

The video signal output from the NIPU 47 is input to an SIBC 49 which is a memory controller for reading the back side which manages a DRAM 48 which is a back side image memory functioning as an image storage means.
8 is stored as backside image data. Where DRA
The memory capacity of M48 is 8 Mbytes, and the capacity is set in the SIBC 49 as a storable capacity. Here, the SIBC 49 is the DR of the back side image data accompanying the reading scan of the back side of the read document by the contact image sensor 23.
The amount of data stored in the AM 48 is monitored based on the storable capacity of the DRAM 48 set in the SIBC 49 (the initial setting is 8 Mbytes). And DRAM4
8 from SIBC49 to S
The data is transferred to a printer (image printing device) 42 of the digital copying machine via the CSI controller 41.

The SIBC 40 and the DRAM 48 and the SIBC 49 and the DRAM 39 are connected by a memory path 50 functioning as a storage destination switching means, so that transmission and reception of front side image data and back side image data can be selectively performed. It is possible to switch. This memory path 5
The switching of 0 is performed by a port operation of the CPU 26.

Next, the control program stored in the ROM 27 causes the microcomputer 29 to execute the SIBC 40 and the SIB 40
The memory control function with C49 will be described. Here, FIG. 3 is a flowchart schematically showing the flow of the memory control process.

First, each data amount of the front side image data and the back side image data is obtained based on the size of the read original and the image density designated by pressing the original size designation key k on the operation panel P (step S1). . here,
The function of the data amount acquisition means is executed. For example, the surface image data amount when scanning the front image of an A3-size read original at an image density of 400 dpi is acquired as 297 mm × 420 mm = 4677 dots × 6614 dots = 4 Mbyte, and the half of the A3-size original is read. The back side image data amount when the back side image is read and scanned at an image density of 400 dpi is obtained as 297 mm × 210 mm = 4677 dots × 3307 dots = 2 Mbytes.

Next, the total image data amount is calculated based on the acquired front image data amount and back image data amount (step S2).

The calculated total image data amount (4 Mbytes + 2
(Mbyte = 6Mbyte) is a DRAM which is a surface image memory
This is compared with the total memory capacity which is the sum of the DRAM 39 and the back side image memory (step S3). Here, the function of the comparing means is executed. In this case, the total memory capacity is 10 Mbyte (2 Mbyte + 8 Mbyte = 10 Mby
te), it is determined that “total image data amount ≦ total memory capacity” (Y in step S3), and the process proceeds to step S4.

In step S4, the scanning of the front and back sides of the read original image is performed by the CCD 11 and the contact type image sensor 23.
And the read front side image data and back side image data are stored in the corresponding image memories.

In step S5, it is determined whether the front side image data or the back side image data is near full point during the reading scan. For example, the storage capacity of the DRAM 39 that is the surface image memory is 2
When Mbyte worth of front side image data is stored in the DRAM 39, it is determined that the point is near full (Y in step S5), and the storage destination of the front side image data is switched to the DRAM 48 which is the back side image memory, and the front side image is stored. The data is stored in the back side image memory via the memory path 50.
It is stored in M48 (step S6). In these steps S4 to S6, the function of the storage control means is executed.

The processing of steps S4 to S6 is repeated until it is determined that reading of each image data has been completed (Y in step S7).

On the other hand, in step S3, it may not be determined that “total image data amount ≦ total memory capacity” (N in step S3). For example, the front image data amount is 297 mm × 420 mm = 7016 dot × 9921 dot = 8.7 Mbyte in order to scan and scan the front image of an A3-size read original at an image density of 600 dpi, and the back image data amount is A3 In this case, 297 mm × 420 mm = 7016 dots × 9921 dots = 8.7 Mbytes in order to read and scan the back side image of the read document of the size at an image density of 600 dpi.

When it is not determined that “total image data amount ≦ total memory capacity” (N in step S3), the process proceeds to step S8.

In step S8, the storable capacity of each image data is １ ／ (10 Mbyte ÷ 2 = 5 M) of the total memory capacity.
image memory with a small storage capacity (in this case, the surface image memory DR
If the image data amount (in this case, the front image data amount) exceeds the storage capacity of the AM 39), the front image data is transferred via the memory path 50 to the DRA which is the back image memory.
It is stored in M48. Here, the function of the dividing means is executed.

Thereafter, in step S9, the scanning of the front and back sides of the read original image is performed by the CCD 11 and the contact image sensor 23, and the read front side image data and back side image data are stored in the corresponding image memories. You.

In step S10, it is determined whether the front side image data or the back side image data is near full point during the scanning. For example, 2 Mby, which is the storage capacity of the DRAM 39 as the surface image memory,
When 3 Mbytes (5 Mbytes-2 Mbytes), which is the storage capacity of the front side image data of the DRAM 48 as the back side image memory by switching the storage destination, is stored, it is determined that the near full point is reached ( In step S10, the scanning is temporarily stopped (step S11).

Thereafter, when the memory capacity of the DRAM 39 and the DRAM 48 has a margin (near-full release point) due to the transfer processing of the image data to the printer unit 42 (Y in step S12), the temporary stop is released. (Step S13), the driving of the motor is restarted, and the intermittent operation of the reading scan is executed.

The processes in steps S9 to S13 are performed until it is determined that reading of each image data is completed (step S1).
Y of 4) is repeated. These steps S9 to S14
In, the function of the intermittent reading means is executed.

Here, the image data on the front and back sides obtained by the reading scan by the double-side reading means is basically stored in the DRAM 39.
And the DRAM 48, respectively. here,
When the total data amount of the image data on the front and back sides acquired by the data amount acquisition means is equal to or less than the total storage capacity of the DRAM 39 and the DRAM 48, and the surface image data amount exceeds the storage capacity of the DRAM 39 which is the surface image memory. Is
The storage destination of the excess of the surface image data is the memory path 50.
Is switched to the DRAM 48 as the back side image memory, and the excess of the front side image data is stored in the DRAM 48. This eliminates the need to intermittently perform the reading scan, so that the throughput can be improved with an inexpensive configuration.

On the other hand, the total data amount of the image data on the front and back sides acquired by the data amount acquisition means is equal to the DRAM 39 and D
If the total storage capacity of the RAM 48 or more is exceeded, the DRA
Each storage capacity of M39 and DRAM 48 is DRA
The storage destination is switched by the memory path 50 so that the storage capacity is equivalent to the storage capacity obtained by dividing the total storage capacity of the M39 and the DRAM 48 into two.
The reading scan is intermittently repeated so that the respective storage capacities of the above do not become full. Accordingly, for example, when the storage capacity of the DRAM 39 as the front image memory is small and the storage capacity of the DRAM 48 as the back image memory is large, the storage capacity is equivalent to the storage capacity obtained by dividing the total storage capacity of the DRAM 39 and the DRAM 48 into two. Since the intermittent operation occurs on the basis of the intermittent operation, the frequency of the intermittent operation is less than that of the intermittent operation based on the storage capacity of the DRAM 39 which is a surface image memory having a small storage capacity.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The scanner unit of the present embodiment and the scanner unit 1 of the first embodiment
Only the memory control function of the SIBC 40 and the SIBC 49 that the control program stored in the M27 causes the microcomputer 29 to execute is different.

FIG. 4 is a flowchart schematically showing the flow of the memory control process. First, the data amounts of the front side image data and the back side image data are obtained based on the size of the read original and the image density specified by pressing the original size designation key k on the operation panel P (step S21). Here, the function of the data amount obtaining means is executed. For example, the surface image data amount when scanning the front image of an A3-size read original at an image density of 400 dpi is acquired as 297 mm × 420 mm = 4677 dots × 6614 dots = 4 Mbyte, and the half of the A3-size original is read. The back side image data amount when the back side image is read and scanned at an image density of 400 dpi is acquired as 297 mm × 210 mm = 4677 dots × 3307 dots = 2 Mbytes.

Next, the total image data amount is calculated based on the acquired front side image data amount and back side image data amount (step S22).

The calculated total image data amount (4 Mbytes)
+2 Mbyte = 6 Mbyte) is DR which is a surface image memory
This is compared with the total memory capacity, which is the sum of the AM 39 and the DRAM 48 as the back side image memory (step S23).
Here, the function of the comparing means is executed. In this case,
The total memory capacity is 10 Mbyte (2 Mbyte + 8 Mbyte = 10
Mbyte), it is determined that “total image data amount ≦ total memory capacity” (Y in step S23), and the process proceeds to step S24.

In step S24, the storable capacity of each image data is set to an amount obtained by distributing the total memory capacity in accordance with the ratio of each image data amount, and one of the image memories (in this case, the surface image memory is used. DRAM3
If the image data amount (in this case, front image data amount) exceeds the storage capacity of 9), the image data (front image data) is transferred to another image memory (in this case, back image memory) via the memory path 50. Is stored in the DRAM 48). In this case, the surface image data amount is 4 Mby
te, the back side image data amount is 2 Mbytes, and the total memory capacity is 10 Mbytes. Therefore, the storage capacity of the front side image data is set to 10 × 4 / (4 + 2) = 6.7 Mbytes, and the back side image data is stored. As the possible capacity, 10 × 2 / (4 + 2) = 3.3 Mbytes is set.

Thereafter, in step S25, scanning of both sides of the read original image is performed by the CCD 11 and the contact image sensor 23, and the read front side image data and the back side image data are stored in the corresponding image memories. You.

In step S26, it is determined whether the front side image data or the back side image data is near full point during the scanning. For example, when 2 Mbytes of surface image data, which is the storage capacity of the DRAM 39 serving as the surface image memory, is stored in the DRAM 39, it is determined that the near full point is reached (Y in step S26), and the storage destination of the surface image data is determined. Is switched to the DRAM 48 as the backside image memory, and the front side image data is transferred to the DRAM 48 as the backside image memory via the memory path 50.
The data is stored using 4.7 Mbytes of the RAM 48 (step S27). In these steps S24 to S27, the function of the storage control means is executed.

The processes in steps S25 to S27 are performed until it is determined that reading of each image data is completed (step S25).
28, Y), is repeated.

On the other hand, in step S23, it may not be determined that “total image data amount ≦ total memory capacity” (N in step S23). For example, a front image of an A3-size read original having a front image data amount of 600 dpi
297mm × 420mm = 7016dot × 9921dot = 8.7Mbyte, and the amount of backside image data is to scan and scan the backside image of the A3 size read document at an image density of 600 dpi. 297 mm × 420 mm = 7016 dots × 9921 dots = 8.7 Mbytes.

If it is not determined that “total image data amount ≦ total memory capacity” (N in step S23), the process proceeds to step S29.

In step S29, the storable capacity of each image data is １ ／ of the total memory capacity (10 Mbyte ÷ 2 = 5
Mbyte), which is set to a capacity corresponding to an image memory having a small storage capacity (in this case, the surface image memory D
When the image data amount (in this case, the front surface image data amount) exceeds the storage capacity of the RAM 39), the front surface image data is transferred to the rear surface image memory DR via the memory path 50.
It is stored in AM48. Here, the function of the dividing means is executed.

Thereafter, in step S30, the reading scan of the front and back sides of the read original image is executed by the CCD 11 and the contact type image sensor 23, and the read front side image data and back side image data are stored in the corresponding image memories. You.

In step S31, it is determined whether the front side image data or the back side image data is near full point during the reading scan. For example, 2 Mby, which is the storage capacity of the DRAM 39 as the surface image memory,
When 3 Mbytes (5 Mbytes-2 Mbytes), which is the storage capacity of the front side image data of the DRAM 48 as the back side image memory by switching the storage destination, is stored, it is determined that the near full point is reached ( In step S31, the scanning is temporarily stopped (step S32).

Thereafter, when the memory capacity of the DRAM 39 and the DRAM 48 has a margin (near-full release point) when the image data is transferred to the printer unit 42 (Y in step S33), the suspension is released. (Step S34), the driving of the motor is restarted, and the intermittent operation of the reading scan is performed.

The processes in steps S30 to S34 are performed until it is determined that reading of each image data is completed (step S30).
35Y) is repeated. These steps S30 to S
At 35, the function of the intermittent reading means is executed.

Here, the image data on the front and back sides obtained by the reading scan by the both-side reading means is basically stored in the DRAM 39.
And the DRAM 48, respectively. here,
When the total data amount of the image data on the front and back sides acquired by the data amount acquisition means is equal to or less than the total storage capacity of the DRAM 39 and the DRAM 48, and the surface image data amount exceeds the storage capacity of the DRAM 39 which is the surface image memory. Is
The total storage capacity of the DRAM 39 and the DRAM 48 is distributed according to the ratio of the data amount of the front side image data to the data amount of the back side image data. And the excess of the front side image data is stored in the storage area of the front side image data distributed to the DRAM 48 which is the back side image memory. This eliminates the need to intermittently perform the reading scan, so that the throughput can be improved with an inexpensive configuration.

On the other hand, the total data amount of the image data on both the front and back sides obtained by the data amount obtaining means is equal to the DRAM 39 and D
If the total storage capacity of the RAM 48 or more is exceeded, the DRA
Each storage capacity of M39 and DRAM 48 is DRA
The storage destination is switched by the memory path 50 so that the storage capacity is equivalent to the storage capacity obtained by dividing the total storage capacity of the M39 and the DRAM 48 into two.
The reading scan is intermittently repeated so that the respective storage capacities of the above do not become full. Accordingly, for example, when the storage capacity of the DRAM 39 as the front image memory is small and the storage capacity of the DRAM 48 as the back image memory is large, the storage capacity is equivalent to the storage capacity obtained by dividing the total storage capacity of the DRAM 39 and the DRAM 48 into two. Since the intermittent operation occurs on the basis of the intermittent operation, the frequency of the intermittent operation is less than that of the intermittent operation based on the storage capacity of the DRAM 39 which is a surface image memory having a small storage capacity.

The image reading apparatus of each embodiment is applied to the scanner section 1 of the digital copying machine which is an image forming apparatus, and the external apparatus is applied to the printer section 42 of the digital copying machine. Instead, the present invention may be applied to a digital facsimile machine or the like. Further, an image scanner may be applied as an image reading device and output to an external device such as a personal computer.

Further, in each embodiment, each data amount of the front side image data and the back side image data is determined based on the size of the read original designated by pressing the original size designation key k of the operation panel P and its image density. Although the acquisition is performed, the present invention is not limited to this, and the size of the read original may be detected by a sensor or the like.

[0065]

According to the image reading apparatus of the first aspect of the present invention, the image data on the front and back sides obtained by the reading scan is temporarily stored in each of the two image storage means in principle.
The total data amount of the image data on the front and back sides acquired by the data amount acquisition unit is equal to or less than the total storage capacity of the two image storage units, and the storage amount of one image storage unit corresponding to the data amount of one image data Is exceeded, the storage destination of the excess of the one image data is switched to another image storage means, and the excess of the one image data is stored in the other image storage means, so that the reading scan is performed. Since it is not necessary to perform the operation intermittently, the throughput can be improved with an inexpensive configuration.

According to the image reading apparatus of the second aspect, the image data on both the front and back sides obtained by the reading scan is temporarily stored in the two image storage units in principle, but are obtained by the data amount obtaining unit. If the total amount of image data on the front and back sides is less than the total storage capacity of the two image storage units, and the data amount of one image data exceeds the storage capacity of the corresponding one image storage unit, Distribute the total storage capacity of the two image storage means according to the ratio of the data amount of the image data and the data amount of the other image data,
By switching the storage destination of the excess of the one image data to another image storage means and storing the excess of the one image data in the storage area of the one image data distributed to the other image storage means, Since it is not necessary to perform the reading scan intermittently, the throughput can be improved with an inexpensive configuration.

According to the third aspect of the present invention, in the image reading apparatus according to the first or second aspect, the total data amount of the image data on both the front and back sides acquired by the data amount acquiring unit is equal to the total data amount of the two image storage units. If it is over the storage capacity,
The storage destination is switched so that the storage capacity of each image storage means becomes a storage capacity corresponding to a capacity obtained by dividing the total storage capacity of the two image storage means into two, and reading is performed so that the storage capacity of each image storage means does not become full. By intermittently repeating the scanning, for example, when the storage capacity of one image storage unit is small and the storage capacity of the other image storage unit is large, the total storage capacity of the two image storage units is reduced to two. Since the intermittent operation is generated based on the corresponding storage capacity, the frequency of the intermittent operation can be reduced as compared with the occurrence of the intermittent operation based on the storage capacity of one image storage unit having a small storage capacity.

According to the image forming apparatus of the present invention, the total amount of the image data on the front and back sides acquired by the data amount acquiring unit is not more than the total storage capacity of the two image storage units. Below, the reading scan and the data transfer can be executed continuously, so that the printing operation can be executed without waste.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a structure of a scanner unit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing electrical connections of each unit.

FIG. 3 is a flowchart schematically showing a flow of a memory control process.

FIG. 4 is a flowchart schematically showing a flow of a memory control process according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus 11,23 Double-sided reading means 39,48 Image storage means 41 Data transfer means 42 Image printing apparatus 50 Storage destination switching means

Claims (4)

[Claims] 1. A double-sided reading means for reading and scanning both a document front side image and a document back side image to obtain image data on both sides, respectively, and temporarily storing the image data on both front and back sides obtained by the both side reading means. Two image storage means, storage destination switching means for switching storage destinations of the image data on the front and back surfaces stored in the two image storage means, and a data amount for acquiring the data amount of the image data on both the front and back sides Acquiring means; comparing means for comparing the total data amount of the image data on the front and back surfaces acquired by the data amount acquiring means with the total storage capacities of the two image storage means; The total data amount of the image data on both the front and back sides is less than or equal to the total storage capacity of the two image storage means, and the data amount of one image data corresponds to When the storage capacity of the image storage means is exceeded, storage control means for switching the storage destination of the excess of the one image data to another image storage means by the storage destination switching means and storing the two image storage means A data transfer unit for sequentially transferring each image data stored in the unit to an external device. 2. A double-sided reading means for reading and scanning both a document front-side image and a document back-side image to obtain image data on both front and back sides, respectively, and temporarily storing the image data on both front and back sides obtained by the both-side reading means. Two image storage means, storage destination switching means for switching storage destinations of the image data on the front and back surfaces stored in the two image storage means, and a data amount for acquiring the data amount of the image data on both the front and back sides Acquiring means; comparing means for comparing the total data amount of the image data on the front and back surfaces acquired by the data amount acquiring means with the total storage capacities of the two image storage means; The total data amount of the image data on both the front and back sides is less than or equal to the total storage capacity of the two image storage means, and the data amount of one image data corresponds to If the storage capacity of the image storage means is exceeded, the total storage capacity of the two image storage means is distributed according to the ratio of the data amount of one image data to the data amount of the other image data. Storage control means for switching the storage destination of the excess image data to a storage area of one image data distributed to another image storage means by the storage destination switching means and storing the image data; And a data transfer unit for sequentially transferring each image data to an external device. 3. When the total data amount of the image data on the front and back sides acquired by the data amount acquisition means is equal to or greater than the total storage capacity of the two image storage means, the storage capacity of each image storage means is two. Two-division means for switching storage destinations by the storage destination switching means so as to have a storage capacity equivalent to a capacity obtained by dividing the total storage capacity of the image storage means into two; 2. An intermittent reading unit that intermittently repeats the double-sided reading unit so that the storage capacity of the image storage unit does not become full.
Or the image reading device according to 2. 4. An image comprising: the image reading device according to claim 1; and an image printing device that prints an image corresponding to the image data transmitted from the image reading device according to an electrophotographic process. Forming equipment.