JPH1146295A - Digital image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital image reader with improved image quality by changing a subscanning speed in the image data transfer mode, so as reduce a stoppage operation. SOLUTION: A CPU 25 receives a synchronization data transfer message sent from a host via a connector and synchronously transfers image data according to a set transfer unit. A controller 24 is prepared with a register to set the transfer unit, and the CPU 25 writes a value to the register to set the transfer unit. Furthermore, a synchronous/asynchronous mode is set depending on the contents of a synchronous data transfer message at the some time. Digitized image data are given to an SIP 3 in line units, and the period of the line of the received image data is constant regardless of the read density. In the case that the content of the synchronous data transfer message indicates an asynchronous mode, a subscanning read speed is decreased for attaining stable image reading.

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, and more particularly, to an SCS1 (SmalI Computer).
The present invention relates to an image reading apparatus that includes a system interface and transfers image data to an external device.

[0002]

2. Description of the Related Art In a conventional image reading apparatus which reads a document image and transfers the image data to an external device by SCSI, the reading speed of the document is uniquely determined by a preset reading density. In addition, when image data is received, the transfer speed of image data to and from an external device is also fixed by the processing speed of the external device. Therefore, when a predetermined number of image data determined by the reading density and the reading area is transferred from the image reading device to the external device, if the image data transfer speed is higher than the reading speed of the original, the image data is transferred without delay. If the image data transfer speed is lower than the speed at which the original is read, a memory is provided in the image reading device, the image data is temporarily stored in the memory, and the stored image data is transferred to an external device. The transfer was to match the speed.

[0003]

Generally, image data transfer from an image reading device to an external device is performed in the following procedure. (1) The image data read by the image reading device is stored in a memory such as a DRAM.
(2) Transfer image data from a memory such as a DRAM to an external device. The processes (1) and (2) are performed simultaneously. However, there is a difference between the speed at which data is stored in the memory and the speed at which data is transferred. When data is read at a low transfer speed or at a high density, the data is gradually accumulated in the memory. Due to the limited amount of memory, reading must be paused at some point. The stepper motor is often used for motor control of the reading device, and cannot be stopped instantaneously due to the nature of the motor. A method of gradually reducing the speed called a through-down is used. Further, the image data stored in the memory gradually decreases, and if the reading operation is restarted at a certain point, the image cannot be instantaneously moved due to the nature of the motor. A method of gradually increasing the speed called "through-up" is used.

In the case where the transfer speed is relatively faster than the storage speed in the memory, the through-down and through-up operations may occur many times during one reading operation. The image quality is worse when scanning at a constant speed than when scanning through and down.

Accordingly, a first object of the present invention is to provide a digital image reading apparatus in which the temporary reading stop operation is reduced and the image quality is improved by changing the sub-scanning speed in the image data transfer mode. . A second object of the present invention is to provide a digital image reading apparatus which can be connected to many external devices by using a general-purpose interface. Third of the present invention
It is an object of the present invention to provide a digital image reading apparatus in which the use of a synchronous data transfer request message as an image data transfer mode arbitration means reduces temporary reading stop operations and improves image quality. A fourth object of the present invention is to provide a digital image reading apparatus in which temporary reading stop operation is reduced and image quality is improved by using asynchronous transfer or synchronous transfer as an image data transfer mode. A fifth object of the present invention is to provide a digital image reading apparatus in which the temporary scanning stop operation is reduced and the image quality is improved by lowering the sub-scanning speed in asynchronous transfer than in synchronous transfer. .

[0006]

According to the first aspect of the present invention, there is provided a reading means for reading a document image, a transferring means for transmitting and receiving image data read by the reading means to and from an external device; A sub-scanning speed setting unit that can arbitrarily set a reading speed in the sub-scanning direction; and an image data transfer mode arbitration unit that determines an image data transfer mode through communication with an external device. The first object is achieved by setting the reading speed in the sub-scanning direction by the sub-scanning speed setting means according to the set image data transfer mode.

According to a second aspect of the present invention, in the digital image reading apparatus according to the first aspect, the transfer means is an SC.
The second object is achieved by being SI. According to a third aspect of the present invention, in the digital image reading apparatus according to the first or second aspect, the third image data transfer mode arbitration means uses a synchronous data transfer request message sent from a host computer.
Achieve the objectives.

According to a fourth aspect of the present invention, in the digital image reading apparatus according to the first or second aspect, the transfer mode set by the image data transfer mode arbitration unit uses asynchronous transfer and synchronous transfer. Achieve the fourth objective. According to a fifth aspect of the present invention, in the digital image reading apparatus according to the fourth aspect, there is provided an image data transfer speed setting unit which can arbitrarily set an image data transfer speed of the transfer unit to an external device. The fifth object is achieved by reducing the reading speed in the sub-scanning direction of the asynchronous transfer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to FIGS. FIG.
1 is an overall configuration diagram of an image reading device according to the present embodiment.
The original placed on the platen glass 1 is illuminated by an illumination lamp 3 integrally formed with the first mirror 2, and its reflected light is reflected by the first mirror 2, the second mirror 4 integrally formed, and the second mirror 4. Scanning is performed by three mirrors 5. Thereafter, the reflected light is converged by a lens 38 and is irradiated on a CCD (photoelectric conversion element) 6 to be photoelectrically converted. The first mirror 2, the illumination lamp 3, the second mirror 4, and the third mirror 5
Can be moved in the direction A by using as a drive source. The originals stacked on the original tray 8 pass through a reading position B by a big roller 9, a pair of registration rollers 10, a conveying drum 11 and a conveying roller 12, and then reach a pair of discharge rollers 1.
3 and 14 and are discharged onto a discharge tray 15.

When the document passes through the reading position B, the original is illuminated by the illumination lamp 3 moved to the vicinity of the reading position B, and the reflected light thereof is reflected by the first mirror 2 and the second mirror 4 integrally formed. Are scanned by the third mirror 5. Thereafter, the reflected light is converged by the lens 38, irradiated on the CCD 6, and photoelectrically converted. The pickup roller 9 and the registration roller pair 10 are driven by a paper feed motor (not shown), and the transport drum 11, the transport roller 12, and the discharge roller pairs 13 and 14 are driven by a transport motor 16.

FIG. 2 is a block diagram of the image reading apparatus according to the present embodiment. SBU (Sensor Board Unit) 17
The reflected light of the original that has entered the upper CCD 6 is converted into an analog signal having a voltage value corresponding to the light intensity in the CCD 6. The analog signal is divided into odd bits and even bits and output. The analog image signal is an MBU (Mothe
r Board Unit) 18 AHP (Analogue data Handlin
g Peripheral) 19, the dark potential portion is removed, the odd bits and the even bits are combined, the gain is adjusted to a predetermined amplitude, and then input to an A / D (analog / digital) converter to be converted into a digital signal. The digitized image signal is subjected to shading correction, gamma correction, MTF correction, and the like by an SIP 3 (Scanner Imaging Peripheral 3) 21 on an SCU (Scanner Control Unit) 20, and then binarized. , Line sync signal,
It is output as a video signal together with the image clock.

The video signal output from the SIP 3 (21) is transmitted through an IEU (Image Enhance Uni
t) 28. The video signal output to the IEU 28 is subjected to predetermined image processing in the IEU 28,
It is input to the SCU 20 again. And again SCU20
The video signal input to is input to the selector 30. The other input of the selector 30 is SIP3 (21)
The video signal output from the IEU 28 has a configuration in which it is possible to select whether or not to perform the image processing in the IEU 28.

The output of the selector 30 is input to the selector 31. The other input of this selector 31 is RC
It is a video signal from a U (Reverse side Control Unit) 32 and has a configuration in which a reading surface of a document can be selected. The RCU 32 is a unit that controls reading of the back side of the document when reading both sides of the document at the same time.
The RCU 32 is a CPU (central processing unit) in the SCU 20
25 is controlled by serial communication, and the read back side image data is used as a video signal by the SCU 2 via the MBU 18.
Transfer to 0. The video signal output from the selector 31 is
It is connected to a selector 32 and a connector 33. The other input of the selector 32 is a video signal from the video adapter 39. With the above configuration, the video adapter 39 can be connected to the end of the connector 33.

The video signal output of the selector 32 is SBC
22. Through the above route, SIP3 (2
The video signal output from 1) is input to the SBC 22 that manages the DRAM, and the SIMM (Single Inline Memory) is input.
y Module) 23 are stored in an image memory composed of a DRAM. The image data stored in the image memory is connected to the selector 34 and the connector 35. The connector 35 has a DCU (Data Compression Uni
t) 36 is connected, and the DCU 36 compresses the input image data. The image data compressed by the DCU 36 is input to the other input of the selector 34, so that it is possible to select whether to compress the image data or not. The image data output of the selector 34 is sent to the host computer via the SCSI controller 24.

On the SCU 20, a CPU 25 and a ROM
(Read only memory) 26, RAM (random
Access memory 27 is mounted and controls the SCSI controller 24 to communicate with the host computer. In addition, the CPU 25 also controls the timing of the traveling body motor 7, a sheet feeding motor, and the transport motor 16, which are stepping motors. ADU (Adf D
The riving unit 37 has a function of relaying the power supply of electrical components used in the automatic document feeder (ADF) unit.

Next, SCSI asynchronous / synchronous transfer and synchronous data transfer messages will be described. SCSI
In the data transfer method above, in terms of transfer speed,
It can be classified into basic asynchronous transfer and synchronous transfer that can be speeded up. Asynchronous transfer is a basic method, and information transfer (message, status) other than data transfer is also sent by this method. More specifically, handshaking by REQ / ACK is performed. In this transfer mode, transfer of about 1.5 Mbytes / sec is possible. In the asynchronous transfer, information transfer (message, status) other than data transfer is also transmitted by this method. Specifically, it depends on the handshake by REQ / ACK. About 1.5 in this transfer mode
Transfer of about M bytes / sec is possible.

On the other hand, synchronous transfer can be used only in the data phase. That is, the mode is intended for high-speed data transfer. In order to use this synchronous transfer mode for data transfer, agreement between target initiators is required. This consent is Synchronous Data
"REQ / ACK offset value" by exchanging the message "Transfer Request"
And "minimum transfer synchronization". In this transfer mode, transfer up to 10 Mbytes / sec is possible.

Next, the operation of this embodiment will be described. The CPU 25 controls the SCSI controller 24 and receives a synchronous data transfer message transmitted from the host computer via the connector. Then, synchronous transfer of image data is performed in accordance with the set transfer unit (Transfer period). A register for setting a transfer unit is provided on the SCSI controller 24, and the CPU 25 can set the transfer unit by writing a value to the register. At the same time, the synchronous / asynchronous mode can be set according to the content of the synchronous data transfer message. That is, the image data transfer speed setting means refers to a means (CPU 25) for determining a transfer unit according to a synchronous data transfer message.
The transfer unit here means the image data transfer speed. Digitized image data is converted to SIP3 data in line units.
Input to (21). The line cycle of the input image data is constant regardless of the reading density. At this time, if the content of the synchronous data transfer message is in the asynchronous mode, the sub-scanning reading speed is reduced, and stable image reading becomes possible. SCS as image data transfer speed detection means
Since the synchronous data transfer request message in I.I is used, SC which is a representative communication means for the image reading apparatus is used.
In SI, the above-described effects can be obtained without adding a special configuration.

[0019]

According to the first aspect of the present invention, the sub-scanning speed setting unit sets the sub-scanning speed according to the image data transfer mode determined by the image data transfer mode arbitrating unit, thereby temporarily stopping the reading operation. And the image quality can be improved. According to the second aspect of the present invention, since the SCSI that is a general-purpose interface is used for communication with the external device, the temporary reading stop operation is reduced and the image quality is improved without newly developing an external device interface. be able to.
According to the third aspect of the invention, the use of the synchronous data transfer request message as the image data transfer mode arbitration means can reduce the temporary reading stop operation and improve the image quality.

According to the fourth aspect of the present invention, by using asynchronous transfer or synchronous transfer as the image data transfer mode, the temporary reading stop operation can be reduced and the image quality can be improved. According to the fifth aspect of the present invention, the sub-scanning speed of the asynchronous transfer is made slower than that of the synchronous transfer,
The temporary reading stop operation is reduced, and the image quality can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image reading apparatus according to an embodiment.

FIG. 2 is a block diagram of the image reading apparatus according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 platen glass 3 illumination lamp 6 CCD 17 SBU (Sensor Board Unit) 18 MBU (Mother Board Unit) 19 AHP (Analogue data Handling Peripheral) 20 SCU (Scanner Control Unit) 21 SIP3 (Scanner Imaging Peripheral 3) 29 connector 28 IEU (Image Enhance Unit) 30, 31 Selector 32 RCU (Reverse Side Control Unit) 25 CPU 24 SCSI Controller 37 ADU (Adf Driving Unit) 38 Lens

Claims (5)

[Claims] A reading means for reading an original image; a transfer means for transmitting and receiving image data read by the reading means to and from an external device; and a sub-scanning means for setting a reading speed of the reading means in a sub-scanning direction. Scanning speed setting means, and image data transfer mode arbitration means for determining an image data transfer mode through communication with an external device, wherein the sub-scanning is performed in accordance with the image data transfer mode determined by the image data transfer mode arbitration means. A digital image reading apparatus, wherein a reading speed in the sub-scanning direction is set by speed setting means. 2. The digital image reading apparatus according to claim 1, wherein said transfer means is SCSI. 3. The image data transfer mode arbitration means,
3. The digital image reading apparatus according to claim 1, wherein a synchronous data transfer request message sent from a host computer is used. 4. The digital image reading apparatus according to claim 1, wherein asynchronous transfer and synchronous transfer are used in a transfer mode set by said image data transfer mode arbitration means. 5. An image data transfer speed setting unit which can arbitrarily set an image data transfer speed to an external device by said transfer unit, and makes a reading speed in the sub-scanning direction of asynchronous transfer slower than synchronous transfer. The digital image reading device according to claim 1 or 2, wherein