JP2002190921A - Image reading device - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To maximize the throughput of a device by changing the reading speed in the sub-scanning direction according to the performance of a selected interface and a host device to prevent occurrence of intermittent operation. Provided is an image reading device that can obtain a good image while exhibiting the same. SOLUTION: In an image reading apparatus for performing line-by-line reading by a line sensor in synchronization with a clock pulse of a sub-scanning step motor, a memory control unit (35) stores image data read by the line sensor in an image memory. At the same time, the remaining capacity of the image memory is monitored.
The PU (37) includes a plurality of interface controllers 16, 36 for controlling input / output of image data with an external device.
The reading speed in the sub-scanning direction is reduced for the selected interface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading apparatus having an interface with a host apparatus, such as an image scanner, a digital copying machine, and a digital facsimile apparatus.

[0002]

2. Description of the Related Art In an image reading apparatus for transferring image data to an external device while reading an image, if an image data transfer speed to the external device is lower than a reading speed of an original, the image reading device stores the image in the image reading device. By providing a memory, data transfer is performed in accordance with the transfer speed of the external device.

In such a case, if the difference between the speed at which the image data is stored in the image memory and the data transfer speed to an external device is large, or if the reading density is high and the image data is large, the image data is not read during the reading. Memory may be full. Therefore, in such a case,
The reading operation is stopped by performing the through-down control of the step motor, and when the memory becomes empty due to the data transfer to the external device, the step motor is restarted by the through-up control and the reading is resumed.
A series of image reading is executed by the intermittent operation.

However, it is known that the read image is generally degraded at the time of the step-up / through-down operation of the stepping motor during the intermittent reading operation due to the vibration caused by the start and stop of the motor. For example, in an image reading device such as a scanner, when the reading speed is different from the transfer speed to an external device, or when the reading density is high and the image data is large, the intermittent operation is performed several to several tens of times in one reading operation. Occurs.

[0005] Such intermittent operation can be prevented by making the image memory capacity larger than the document image data amount or making the data transfer speed to the external device faster than the image reading speed. It is. However, it is difficult to mount a large-capacity image memory that supports all original images, and it is difficult to increase the data transfer speed to the external device than the image reading speed depending on the connected interface. It is difficult because it is decided.

Generally, in order to reduce the frequency of the above-described intermittent operation, the reading speed of the image reading device is varied during reading at a high resolution, for example, by lowering the reading speed in the sub-scanning direction. By doing so, the frequency of occurrence of intermittent operation is reduced, and image deterioration is prevented. In recent years, interfaces for transferring data to and from external devices have been diversified.
SCSI for parallel I / F, US for serial I / F
B, IEEE1394, network, etc. are typical interfaces. In order to cope with various interfaces, there are models equipped with a plurality of interfaces as standard or options as image reading devices, and models which are simultaneously connected to a plurality of host devices are increasing.

Until now, in this type of image reading apparatus, the most general-purpose SCSI (Small Computer System) has been used as an interface with an external device.
m Interface) is implemented as a standard in most cases. For example, the SCSI2 standard has a transfer method of asynchronous transfer and synchronous transfer, and has the following maximum transfer speed. -Asynchronous transfer: 5M (Byte / s)-Synchronous transfer: 10M (Byte / s)

Devices having SCSI and IEEE 1394 interfaces as interfaces with external devices are currently standardized, IEEE 139.
Maximum transfer speed of 4 interfaces is 50M (Byte
/ S), in an environment where data transfer can be performed at the maximum transfer rate of each interface, the reading operation performed using the SCSI2 synchronous transfer is not compatible with the IEEE operation.
In a reading operation using the E1394 interface, the frequency of occurrence of the intermittent operation can be the same even when reading is performed at a reading speed five times faster.

[0009]

From the viewpoint of preventing the occurrence of intermittent operation while exhibiting the throughput of the image reading device, it is the most effective reading speed to make the transfer speed and the image reading speed the same.

However, the data transfer from the image reading device is usually divided (block) to complete the transfer of one frame of image data by transferring a predetermined amount of data between the host device and the image reading device a plurality of times.
Since the transfer method is used, depending on the performance of the host device, even if the maximum transfer speed of various interfaces is instantaneously achieved as the transfer speed of one block, data development and storage in the host device can be performed. Since the time until the reception of the next block becomes possible is determined by the processing time, the time between block transfers becomes longer in a low-speed host device. Therefore, it is considered as the average time of the image transfer time of one frame. In this case, the transfer speed is lower than the maximum transfer speed of the interface, and there is a problem that the probability of occurrence of the intermittent reading operation increases.

An object of the present invention is to firstly solve the problem of the prior art. Specifically, the reading speed in the sub-scanning direction is adjusted according to the selected interface and the performance of the host device. In other words, an object of the present invention is to provide an image reading apparatus capable of obtaining a good image while maximizing the throughput of the device by preventing the occurrence of the intermittent operation.

It is a second object of the present invention to enable the initial reading speed of each interface to be changed by the user's selection so that the initial reading speed can be set in accordance with the performance of the host device used by the user. I do. Further, when the reading mode of the image reading device is changed, the storage time of data stored in the image memory of the image reading device changes. With the change, the occurrence state of the intermittent operation also changes, and the data amount decreases. When the mode is changed from a mode with a large number to a mode with a small number, reading is performed at a slower sub-scanning reading speed than the actual value of the device. Therefore, a third object is to avoid this problem by setting the sub-scanning reading speed to an initial value when changing the reading mode.

[0013]

According to a first aspect of the present invention, there is provided a line sensor for reading a document image line by line in accordance with a line synchronization signal, and a step motor for moving the line sensor. A step motor for moving a read original, reading control means for performing line-by-line reading by the line sensor in synchronization with a clock pulse of the step motor, an image memory for storing image data read by the line sensor, and an external device And a plurality of interface controllers for controlling the input and output of image data to and from the image reading apparatus, the reading speed in the sub-scanning direction can be changed according to the performance of the selected interface and the performance of the connected host device. It was configured.

[0014] According to the second aspect of the present invention, the first aspect is provided.
In the described invention, the configuration is such that the initial reading speed of each interface can be set via operation means or communication means. According to the third aspect of the present invention, in the first aspect of the present invention, when the reading condition is changed,
The reading speed in the sub-scanning direction is set as an initial value.

[0015]

Embodiments of the present invention will be described below. FIG. 1 is an overall configuration diagram of an image reading apparatus according to the present invention. Document table glass (1)
The original placed on top is illuminated by the illumination lamp (3),
The reflected light is divided into a first mirror (2), a second mirror (4),
The light reflected by the third mirror (5) and the like is then focused by the lens (38), irradiated to the CCD (6), and 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 the traveling body motor (7) as a drive source. I have. This is a mode in which an image is read by moving the traveling body, and is referred to as a Book mode.

On the other hand, the originals stacked on the original tray (8) are picked up by a pickup roller (9), a pair of registration rollers (10), a transport drum (11), and a transport roller (12).
Through the reading position B, to the transport roller pair (13) and the paper discharge roller pair (14), and to the paper discharge tray (1).
5) Discharged up. When the document passes the reading position B, the illumination lamp (3) is moved to the vicinity of the reading position B.
And the reflected light is applied to the first mirror (2), the second mirror (4), and the third mirror (5) integrally formed.
Is scanned. Thereafter, the reflected light is converged by a lens (38), irradiated to a CCD (6), and photoelectrically converted.

The pickup roller (9) and the pair of registration rollers (10) are driven by a paper feed motor (not shown), and are provided with a transport drum (11), a transport roller (12), a transport roller pair (13), and a discharge roller pair ( 14) is driven by a transport motor (not shown). In this mode, the image is read by moving the document to be read.
It is called ADF mode.

FIG. 2 is a block diagram showing an image reading apparatus according to each embodiment of the present invention. As an example of the configuration of the image reading device, a case will be described in which SCSI and IEEE1394 are provided as external device interfaces. However, an external device interface other than the above may be provided, and the number of interfaces is arbitrary.

In FIG. 2, the CCD on the SBU (17)
(6) The reflected light of the original light entering (see FIG. 1)
In (6), the signal is converted into an analog signal having a voltage value corresponding to the light intensity. The analog signal is divided into an odd pixel signal and an even pixel signal and output. From the analog image signal, the dark potential portion is removed by an analog processing circuit (not shown) on the SBU (17), the odd pixel signal and the even pixel signal are combined, and the gain is adjusted to a predetermined amplitude.
The signal is input to a / D converter and converted into a digital signal.

The digitized image signal is SCU (2
0) Shading correction, gamma correction, MTF correction, etc. are performed by the NIPU (33), and then binarized.
It 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 (33) is output to the option IPU (26) via the connector (34). The video signal output to the option IPU (26) is subjected to predetermined image processing in the option IPU (26),
Input to CU (20).

The video signal again input to the SCU (20) is input to a selector (not shown). The other input of the selector is a video signal output from the NIPU (33), and has a configuration in which the option IPU (26) can select whether or not to perform image processing.
The video signal output from the selector is supplied to a memory control unit (3) for managing data transmission / reception with image data storage means (DRAM) and various I / F controllers.
5), the image data is stored in an image memory composed of a DRAM, and the image data stored in the image memory is stored in a SCSI controller (36) or an IEEE 13
The data is sent to the 94LINK controller (16) by the DMA control method and transferred to an external device such as a personal computer.

On the SCU (20), a CPU (37),
ROM (18) and RAM (39) are mounted.
The PU (37) is a SCSI controller (36) or
It controls the IEEE1394 LINK controller (16) to communicate with an external device such as a personal computer. Also, CP
U (37) also controls the timing of the traveling body motor (7), which is a stepping motor, the sheet feeding motor, and the transport motor. The ADU (30) has an automatic document feed mechanism (A
It has a function of relaying the power supply of electrical components used in the DF) section. An input port connected to the CPU (37) on the SCU (20) is connected to the main body operation panel (28) via the IOB (24).

Hereinafter, a first embodiment of the present invention will be described. First, according to FIG. 3, a basic reading density of 400 when connected to a plurality of interface controllers.
An example of dpi reading will be described.

The image reading apparatus of the embodiment has a SCSI controller (3
6) SCSI I / F controlled by IEEE 13
94LINK controller (16) and IEEE139
IEEE controlled by 4PHY controller (19)
It has an E1394 I / F. The image data transmitted from the NIPU (33) is stored in an image memory composed of a DRAM (23) by the SIBC (22), and the image data stored in the image memory is a SIBC
It is transmitted from (22) to the interface circuit (21).

In this embodiment, the transfer of data between each interface controller and the interface circuit (21) is performed by DMA. Generally, in DMA control, a DREQ (data request) signal is actively output from a data request device. When the device requested for data is ready for data transmission, the DAC
At the same time as the active output of the K (data acknowledge) signal, the data is output to the data request device, and the data request device takes in the data from the timing of the DACK signal. Then, the data transfer is completed by repeating the above control until the data requesting device finishes capturing the required amount of data. The data request device in this embodiment is the SCSI controller (36) or
The IEEE 1394 LINK controller (16) receives the data request from the interface circuit (2).
A memory control unit (35) having 1). D
Even if the MA control method is the same, the control timing and the data transfer rate are limited by the DMA controller built in the device to be used, and the SCSI controller (36 ), Usually cannot control the IEEE 1394 controller (16),
Control is possible as long as it is designed in advance with exactly the same control and timing. In the above case, the same SI
Control is possible with the BC (22) and the DRAM (23).

As described above, in this embodiment, the control corresponding to a plurality of interface controllers is performed by switching the DMA controller to be selected in accordance with the interface control device selected at the time of the image reading operation in the interface circuit (21). Becomes possible. According to the SCSI protocol, SC
The SI bus phase has four types of states, a bus free phase, an arbitration phase, a selection phase, and an information transfer phase. When the SCSI bus is selected, the image is read by shifting to the information transfer phase via each phase. The device and an external host device (not shown) enter a data transfer enabled state.

In the information transfer phase, when a read command is transferred from the host device, the read command data is stored in the FIFO in the SCSI controller (36), and at the same time, an interrupt occurs to the CPU (37) (IN).
The CPU (37) recognizes a read command from the host device by reading the register of the SCSI controller (36). After the instruction is recognized, the interface circuit (21)
U (37) selects a DMA controller for the SCSI controller (36), and performs image data transfer with the SCSI controller (36) by DMA.

On the other hand, according to the IEEE 1394 protocol, the root node, the isochronous manager, the bus initialization, the tree identification, and the self identification are performed.
The cycle master and the bus manager are determined, and the arbitration can be performed.

After the above-described phase, when the image reading apparatus wins the arbitration, the
By acquiring the right to use the 94 bus, the image reading device and the host device are ready for data transfer. When a read command is transferred from the host device, IE
At the same time that the read command data is stored in the FIFO in the EE1394 controller (16), an interrupt occurs to the CPU (37) (issue of the INT1394 signal).
(37) is an IEEE1394 LINK controller (1
By reading the register of 6), a read command from the host device is recognized.

After recognizing the instruction, the CPU (37) in the interface circuit (21) uses the IEEE1.
The DMA controller for the 394 LINK controller (16) is selected, and image data transfer with the IEEE 1394 LINK controller (16) is performed by DMA. For example, when reading by SCSI is selected in the above, 100 mm / s is selected as the initial reading speed in the sub-scanning direction. In addition, IEEE 1394
If reading by interface is selected,
500 mm / s is selected as the initial reading speed in the sub-scanning direction. The above set values can be arbitrarily set within a range in which the image reading device can operate as the sub-scanning speed.

FIGS. 4A and 4B show the relationship between the motor clock of the traveling motor 7 in the image reading apparatus of this embodiment and the reading operation timing in line units (Book mode). Operation). (A)
Is a case of a reading speed of 500 mm / s, and (b) is a case of a reading speed of 100 mm / s. In both cases, a reading timing pulse is made effective every three clock pulses of the traveling motor (7), and at that timing, By reading one line, the number of read data with respect to the moving distance of the traveling body is made equal.

For example, assuming that the traveling body advances by 0.02117 mm per one cycle of the motor clock, an image of 400 dpi can be captured even though the reading speed is different from 500 mm / s and 100 mm / s according to the following formula. It becomes possible. (Expression) 0.02117 × 3 = 0.0635 mm / pixel (400 dpi) In the ADF mode, there is a relationship between the transport motor clock and the read operation timing in line units.

The operation during the intermittent operation of this embodiment will be described below with reference to the operation flowchart shown in FIG. In this embodiment, the DRAM (23) in the memory control unit (35) (FIG.
The remaining memory capacity is checked and if it becomes less than a predetermined value (memory near full), the SIBC (22)
An interrupt signal is output from the CPU to the CPU (37), and the CPU recognizing the interrupt signal stops the reading operation halfway, and after the free memory capacity of the DRAM (23) exceeds a predetermined value (memory near full release). Then, the image reading is restarted. The memory capacity value of the memory near full and the memory near full cancellation can be set to any value in the register of the SIBC (22).

First, image reading is started (S50).
1) The CPU (37) determines whether or not an intermittent operation has occurred due to memory near full from that time to the end of image reading.
Monitoring is performed using an interrupt signal XINTSIBC signal from the BC (22) (No in S502, No in S504, S5
02), when an intermittent operation occurs (Yes in S502),
The intermittent occurrence flag is set to "1" (S503). And
After the image reading is completed (Yes in S504), if the intermittent occurrence flag is 1 (Yes in S505), the CPU (37)
Is changed so that the sub-scanning reading speed becomes slower (S5).
06). On the other hand, when the intermittent occurrence flag = 0 (No in S505), the sub-scanning reading speed is not changed.

Thereafter, the intermittent occurrence flag is reset to "0" (S507), and the reading operation of the image reading apparatus is completed. The change in the sub-scanning reading speed in (S506) is changed in the direction of decreasing the reading speed when the intermittent operation occurs, and this sub-scanning reading speed is reflected from the next document reading. The sub-scanning reading speed change value can be arbitrarily set within the operable speed range of the image reading apparatus.

In the second embodiment of the present invention, the initial reading speed of each interface can be set by the user via the operation means or the communication means. An arbitrary value is set within the operable speed range of the image reading apparatus by an input operation using the key SW on the main body operation panel (28) or by transmitting a reading speed selection command from an external device. Thus, in this embodiment, the user can set the initial reading speed in accordance with the performance of the host device.

Further, in the third embodiment of the present invention, when the reading condition is changed, the reading speed in the sub-scanning direction is set to the initial value. The CPU (37) informs that the reading mode has been changed by a command from each interface.
Is recognized, the CPU (37) sets the reading speed in the sub-scanning direction to an initial value corresponding to each interface before starting reading (S501) in the flowchart shown in FIG. If the occurrence of intermittent operation changes and the mode is changed from a mode with a large amount of data to a mode with a small amount of data, reading will be performed at a slower sub-scanning reading speed than the actual value of the device. In the example, when the reading mode is changed, the above problem can be avoided by setting the sub-scanning reading speed to the initial value.

[0039]

As described above, according to the present invention,
According to the first aspect of the present invention, the reading speed in the sub-scanning direction can be changed according to the performance of the selected interface and the performance of the connected host device. In addition, it is possible to obtain a good image while maximizing the throughput of the device. According to the second aspect of the invention, in the first aspect of the invention, the user can set the initial reading speed of each interface, so that the initial reading speed can be set according to the performance of the host device used by the user. Becomes

Further, according to the third aspect of the present invention, the first aspect is provided.
In the described invention, when the reading conditions are changed,
Since the reading speed in the sub-scanning direction is set to the initial value, the occurrence of intermittent operation changes with the reading mode change,
When the mode is changed from a mode having a large amount of data to a mode having a small amount of data, it is possible to avoid a problem that reading is performed at a slow sub-scanning reading speed with respect to the ability value of the device.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image reading apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an image reading apparatus according to each embodiment of the present invention.

FIG. 3 is a block diagram of the image reading apparatus according to the first embodiment of the present invention.

FIG. 4 is a timing chart of a main part of the image reading apparatus according to the first embodiment of the present invention.

FIG. 5 is an operation flowchart of the image reading apparatus according to the first embodiment of the present invention.

[Explanation of symbols]

 16 IEEE1394 LINK controller 17 SBU 19 IEEE1394PHY controller 20 SCU 21 Interface circuit 22 SIBC 23 DRAM 28 Main body operation panel 33 NIPU 35 Memory control unit 36 SCSI controller 37 CPU

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/107

Claims (3)

[Claims] 1. A line sensor for reading a document image line by line in accordance with a line synchronization signal, a step motor for moving the line sensor, a step motor for moving a read document, and a step motor for reading line by line by the line sensor. An image reading apparatus comprising: reading control means for performing synchronization with a clock pulse; an image memory for storing image data read by the line sensor; and a plurality of interface controllers for controlling input and output of image data with an external device. 3. The image reading apparatus according to claim 1, wherein the reading speed in the sub-scanning direction can be changed according to the performance of the selected interface and the performance of the connected host device. 2. The image reading apparatus according to claim 1, wherein an initial reading speed of each interface can be set via operation means or communication means. 3. The image reading apparatus according to claim 1, wherein when the reading condition is changed, the reading speed in the sub-scanning direction is set to an initial value.