JPH02291763A - Scanner device - Google Patents

Abstract

PURPOSE:To increase the processing speed by providing a subscanning control means which can control the subscanning speed to plural stages and a speed detecting means which detects the image data taking-in average speed of a host device and setting a maximum subscanning speed in such range based on this image data taking-in average speed that a buffer memory does not overflow. CONSTITUTION:A transfer speed detecting circuit 30 outputs a detected transfer speed to a CPU 31, and the CPU 31 sets the subscanning speed based on this transfer speed so that image data taken into a buffer memory 27 and image data read out from the buffer memory 27 are balanced, and the rotating speed of a subscanning motor 32 is controlled based on the set subscanning speed. That is, the CPU 31 properly controls the rotating speed of the subscanning motor 32 in plural stages, and the rotating speed corresponding to the set subscanning speed is selected to control the subscanning speed. At the time of setting the subscanning speed, the CPU 31 sets such highest subscanning speed that the buffer memory 27 does not overflow.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a scanner device, and more particularly to a scanner device with improved sub-scanning speed control.

(Prior Art) A scanner device is connected to a host device such as a computer, and transfers main-scanned and sub-scanned image data to the host device. There are synchronous interfaces and asynchronous interfaces as interfaces with the host device, and they are generally used as general-purpose or semi-general-purpose interfaces on the host side, and are also used as host device C P
U (Central Processing Unit
) is suitable for importing image data, so asynchronous interfaces are often used.

However, when an asynchronous interface is adopted as the interface, the image data acquisition speed of the host device varies greatly depending on the type of host device and the type of application software, so the transfer timing of image data from the scanner device to the host device is It varies greatly depending on the conditions.

Therefore, in order to cope with changes in transfer timing while keeping the cost of the scanner device as low as possible, conventional scanner devices are equipped with a buffer memory of a predetermined capacity and change the sub-scanning speed based on the amount of image data in the buffer memory. ing. Such conventional scanner devices include:
For example, there is one shown in FIG.

In FIG. 7, the scanner device 1 includes a CCD (Charg
The image data photoelectrically converted in (Coupled Device) 2 is amplified in a video amplifier 3, subjected to shading correction in a shading correction circuit 4, and then digitized in an A/D conversion circuit 5. The image data digitally converted by the A/D conversion circuit 5 is stored as it is in the buffer memory 7 via the buffer I/F circuit 6 when in the multilevel readout mode, and is stored in the buffer memory 7 as it is via the buffer I/F circuit 6 when in the binary readout mode. After being binarized using a predetermined threshold value, the data is stored in a buffer memory 7 via a filter I/F circuit 6.

The buffer memory 7 generally has a capacity to store image data for several lines, or at most several tens of lines.
The image data stored in the buffer memory 7 is transferred to the bath sofa I.
The data is transferred to the host device 10 via the /F circuit 6 and the asynchronous r/F circuit 9. At this time, as shown in Figure 8,
Between the host device 10 and the asynchronous ■/F circuit 9, the STR
After exchanging the OBB signal, BUSY signal and DIRECTION signal, as shown in FIG. If there is valid image data, the STROBE signal is raised and 1 byte of image data is transferred to the host device 10.

When the host device IO receives the STROBE signal from the scanner device 1, it takes in the image data and continues to assert the BUSY signal until it becomes possible to accept the next image data. Therefore, the transfer speed of image data from the scanner device 1 to the host device 10 changes depending on the data capture speed of the host device 10. This image data transfer is performed using CPU (Central Processing).
ng Unit) 11, and C
P Ull monitors the amount of image data stored in the buffer memory 7 and controls the sub-scanning motor 12 based on the amount of image data stored in the buffer memory 7 . That is, in order to prevent the image data in the vanofer memory 7 from overflowing, the C P Ull uses the buffer memory 7
As the amount of image data in the buffer memory 7 increases, as shown in FIG. As the amount of image data decreases, the driving speed of the sub-scanning motor 12, that is, the sub-scanning speed, is increased.

The drive target of the sub-scanning motor 12 differs depending on the model of the scanner device 1, but in the case of a so-called book type scanner device 1, it is a type that moves a carriage body equipped with an optical system and reads a so-called cut sheet document. In the scanner device 1, a roller for conveying a document is rotated.

Further, the DI RECTI ON signal in FIG. 8 is a signal indicating the transfer direction of the bidirectional bus.

(Problem to be Solved by the Invention) However, in such conventional scanner devices, the speed of the sub-scanning motor is controlled based on the amount of image data stored in the buffer memory, so the speed of the sub-scanning motor is controlled based on the amount of image data stored in the buffer memory. The sub-scanning speed changes depending on the data acquisition speed. As a result, there is a problem in that jitter occurs in the image data due to variations in the sub-scanning speed, and image quality deteriorates.

One way to solve this problem is to increase the capacity of the Batza memory that stores image data, for example, to a size that can store image data for one page of a document. A new problem arises in that the memory becomes expensive and the cost of the scanner device increases.

(Object of the Invention) Therefore, the present invention provides a sub-scanning control means that can control the sub-scanning speed in a plurality of stages, and a speed detection means that detects the average speed at which image data is taken in by the host device. By setting the highest sub-scanning speed within the range that does not overflow the buffer memory based on the average data acquisition speed, sub-scanning can be performed at a constant speed that corresponds to the image data acquisition speed of the target host device, and at a high speed. The purpose is to improve the sub-scanning speed, improve the image quality of the output image data of the scanner device, and improve the processing speed while preventing the occurrence of irregularities in the image data.

(Structure of the Invention) To achieve the above object, the invention according to claim 1 reads a document by main scanning and sub-scanning, stores the read image data in a buffer memory, and then sends the read image data to a host via an asynchronous interface. In a scanner device that transfers image data to a device, a sub-scanning control means for controlling the sub-scanning speed in a stepwise manner, a data-intake speed detection means for detecting an average speed of image data acquisition speed of the host device, a sub-scanning speed setting means for setting the highest sub-scanning speed within the capacity range of the eight sofa memory based on the image data capture speed of the host device, and continuously performs sub-scanning at a sub-scanning speed corresponding to the image data acquisition speed of the host device. The invention according to claim 2 is characterized in that, when the host device captures image data in burst mode, the data capture speed detection means detects an average speed during continuous capture of image data; The sub-scanning speed setting means is characterized in that the sub-scanning speed setting means sets the sub-scanning speed based on the average capture speed.

Hereinafter, a detailed description will be given based on examples.

1 to 6 are diagrams showing an embodiment of the invention according to claims 1 and 2. FIG.

FIG. 1 is a block diagram of main parts of the scanner device 21, and the scanner device 21 has a CCD (Charge Coupon).
pled Device) 22, video amplifier 23, shading correction circuit 24, A/D conversion circuit 25, bath sofa (/F circuit 26, buffer memory 27, binarization circuit 28, asynchronous I/F circuit 29, transfer speed detection circuit 30) ，
CPU (Central Processin)
g Unit) 31, a sub-scanning motor 32, etc.

Reflected light irradiated onto a document by an optical system (not shown) is incident on the CCD 22, and the CCD 22 decomposes the incident light into a plurality of pixels and performs photoelectric conversion on each pixel. The CCD 22 outputs the photoelectric conversion result to the video amplifier 23 as analog image data, and the video amplifier 23 amplifies the input image data and outputs it to the shedding correction circuit 24. The shading correction circuit 24 performs shading correction on the image data and outputs it to the A/D conversion circuit 25, and the A/D conversion circuit 25 digitally converts the analog image data and outputs it as multivalued image data. The image data output from the A/D conversion circuit 25 is directly transferred to the buffer memory 27 via the buffer I/F circuit 26 in the multi-value readout mode.
In the binary read mode, the data is binarized by a binarization circuit 28 using a predetermined threshold value, and then stored in the bass interface I/F circuit 26. The amount of image data accumulated in the buffer ys/F circuit 26 is monitored by the CPυ31.

Further, the image data accumulated in the buffer memory 27 is sent to the host device 3 via the non-uniform 3t+1 I/F circuit 29.
Transferred to 3. Image data is transferred from the asynchronous 1/F circuit 29 to the host device 33 using the STRO
This is done asynchronously by exchanging the BE signal, BLISY signal and DIRECTION signal, and the image data transfer rate,
That is, the image data acquisition speed of the host device 33 varies depending on the type of the host device 33, the type of application software on the host device 33, and the like. This non-domestic I/F circuit 2
The transfer rate of the image data No. 9, that is, the image data capture rate of the host device 33 is detected by the transfer rate detection circuit 30, and the transfer rate detection circuit 30 functions as a data capture rate detection means. The transfer rate detection circuit 30 measures the intervals of the STROBE signal and the BUSY signal, and basically averages these intervals to detect the transfer rate (data acquisition rate). The transfer speed detection circuit 30 outputs the detected transfer speed to the CPU 31, and the CPU 3l balances the image data flowing into the buffer memory 27 and the image data read from the buffer memory 27 based on the transfer speed from the transfer speed detection circuit 30. , the sub-scanning speed is set, and the rotational speed of the sub-scanning motor 32 is controlled based on the set sub-scanning speed. That is, the CPU 31 can appropriately control the rotational speed of the sub-scanning motor 32 over a plurality of stages, and controls the sub-scanning speed by selecting the rotational speed corresponding to the set sub-scanning speed. Further, when setting the sub-scanning speed, the CPU 31 sets the highest sub-scanning speed within the capacity range of the buffer memory 27 at which the buffer memory 27 does not overflow. The sub-scanning motor 32 drives a carriage (not shown) on which the optical system of the scanner device 21 is mounted, and sub-scanning is performed by moving the carriage of this optical system in the sub-scanning direction. Note that the scanner device 21 is not limited to one that performs sub-scanning by moving such an optical system, but may also be one that performs sub-scanning by transporting a document. In this case as well, it is possible to deal with this by variablely controlling the rotational speed of the motor that transports the document in stages.

Next, the effect will be explained.

The scanner device of the present invention detects the average image data acquisition speed of the host device to which the scanner device is connected,
Its feature is that the sub-scanning speed is set based on the average speed. This sub-scanning speed setting process will be explained below.

The scanner device 21 detects the average image data acquisition speed of the host device 33 connected to the scanner device 21 before actually reading the document.

That is, as shown in FIG. 2, the scanner device 2l:
First, read one page of the manuscript (Stesob PI),
As described above, the read image data is once stored in the buffer memory 27 and then transferred to the host device 33 via the asynchronous I/F circuit 29. At this time, the host device 33
STROBE signals and BUSY signals are exchanged between the two, and image data is transferred based on these signals. Therefore, the scanner device 21 measures the interval between the STROBE signal and the BUSY signal using the transfer speed detection circuit 30, and basically averages the transfer time of one page of image data to determine the transfer speed (data acquisition speed) between the CPU 31 and the CPU 30.
(step p2).

That is, as shown in FIG. 3(c), the transfer of image data from the scanner device 2l to the host device 33 stops once a predetermined amount of image data has been transferred, and then image data is transferred. Therefore, the transfer speed detection circuit 30 calculates the average transfer speed based on the total time required for transfer (that is, the total time of transfer time and stop time) and the transfer speed during data transfer, and
Output to 31. Based on this average transfer speed, the CPU 31 calculates the rotational speed of the sub-scanning motor 32 that is as fast as possible in consideration of the capacity of the buffer memory 27, that is, the sub-scanning speed (sub-scanning upper limit speed) (step P). .

Once the sub-scanning speed is set, the main reading of the original is performed. In this case, the CPU 31 controls the rotation of the sub-scanning motor 32 at a set rotational speed, and sub-scanning is performed at the set sub-scanning speed. Image data read by the CCD 22 is temporarily stored in a buffer memory 27, and transferred to the host device 33 while monitoring the amount of image data in the buffer memory 27. Therefore, as shown in FIG. 3(C), the scanner device 2
1 to the host device 33, the amount of image data accumulated in the buffer memory 27 is as shown in FIG.
), the sub-scanning speed decreases and increases as the image data is transferred, but the sub-scanning speed remains constant as shown in FIG. 3(b). Therefore, it is possible to prevent jitter from occurring in sub-scanning, and to perform sub-scanning at a high speed, thereby improving the image quality of the scanner device 21 and improving the document reading speed. can.

In the above embodiment, a preliminary scan for setting the sub-scanning speed is performed before the main reading to set the sub-scanning speed, but this is not limited to this. For example, in the case of a document with multiple pages, , the first page of the document may be read, the sub-scanning speed may be set, and the second and subsequent pages may be sub-scanned at the set sub-scanning speed. In this case, it is conceivable that for the first page of the document, the sub-scanning speed may be variably controlled based on the amount of data stored in the buffer memory 27, as in the prior art.

In addition, in cases where the image data capture speed of the host device 33 changes significantly, one page of the document is divided into multiple blocks, as shown in FIG. 4, and each divided block is read. When this is done (step S,), the average transfer rate is set (step sg). Set the sub-scanning speed of the next block based on this set average transfer speed (step S3), scan the document while sub-scanning the next block at the set sub-scanning speed, and calculate the average transfer speed at that time. do. Based on this average transfer speed, the sub-scanning speed of the next block is further set. This operation is performed over one page of the document, and when all the blocks have been read (step S,), this flow ends. Therefore, it is possible to cope with cases where the data acquisition speed of the host device 33 varies greatly.

Furthermore, in each of the above embodiments, the sub-scanning speed is set based on the transfer speed when the actual document is read.
However, as shown in FIG.
), calculate the average transfer speed based on the transfer speed at this time (step qz) e Set the sub-scanning speed based on the average transfer speed calculated by sending out the test pattern.Step Q3), scan the original at the set sub-scanning speed Read. If a test pattern in this case is set in advance in the ROM or RAM in the CPU 31 and outputted from the CPU 31 via the non-uniform 1/F circuit 29 when setting the sub-scanning speed, the setting of the sub-scanning speed can be performed. can be fully automated.

Further, as shown in FIG. 6(a), the host device 33
One block worth of image data corresponding to the capacity of the internal memory is captured from the scanner device 21 and stored in the internal memory, and the capture of image data from the scanner device 21 is stopped and the image data in the internal memory is transferred to the attached magnetic Image data may be captured in a so-called burst mode, such as by transferring it to a disk device or the like. In such a case,
For the scanner device 2l, since the interval between image data transfers is long, sub-scanning is an intermittent movement.

In this case as well, if the average transfer time is calculated based on the total transfer time during transfer and stop, the sub-scanning speed will become slow as shown in FIG. 6(b). Therefore, in the scanner device 21, when the interval (stop time) from the time of transfer to the time of transfer becomes a predetermined time or more, this stop time is excluded from the transfer time, and the data is calculated based only on the time during which data is actually transferred. Calculate the average transfer time. therefore,
As shown in FIG. 6(C), the sub-scanning speed is set to a high speed, and the sub-scanning speed remains constant during burst transfer. As a result, it is possible to improve image quality and to improve document reading speed.

Further, in each of the embodiments described above, the CPU 31 constantly monitors the image data in the buffer memory 27, and when the amount of images in the buffer memory 27 exceeds a predetermined amount, controls the sub-scanning speed as in the conventional case to store the image data in the buffer memory 27. 27 overflow and underflow are prevented.

(Effects) According to the present invention, sub-scanning can be performed at a constant speed corresponding to the image data acquisition speed of the partner host device and at a high speed, while preventing jitter from occurring in the image data. , it is possible to improve the sub-scanning speed. As a result, it is possible to improve the image quality of the output image data of the scanner device, and also to improve the processing speed.

[Brief explanation of drawings]

1 to 6 are diagrams showing an embodiment of the scanner device of the present invention, and FIG. 1 is a block diagram of the scanner device,
Fig. 2 is a flowchart of the sub-scanning speed setting process, Figs. 3(a) to (C) are action explanatory diagrams of the sub-scanning speed setting process, and Fig. 4 is the sub-scanning speed setting process divided into blocks. Figure 5 is a flowchart when the sub-scanning speed setting process is performed using a test pattern, and Figures 6 (a) to (C) are flowcharts of the sub-scanning speed setting process when transferring in burst mode. It is an action explanatory diagram. 7 to 10 are diagrams showing examples of conventional scanner devices, FIG. 7 is a block diagram of the scanner device, and FIG. 8 is a diagram showing asynchronous transfer signals between the scanner device and the host device. , FIG. 9 is a timing chart showing the relationship between the control signal and the transfer of image data, and FIG. 10 is a diagram showing the relationship between the amount of data stored in the sofa memory and the sub-scanning speed. 21... Scanner device, 22... CCD, 27... Buffer memory, 29... Asynchronous 1/F circuit, 30... Transfer Speed detection circuit (data acquisition speed detection means), 31... CPU (sub-scanning control means, sub-scanning speed setting means), 32... sub-scanning motor, 33... -Host device. Fig.B.Fig.Fig.Fig.Fig.Fig.Fig.Fig.Fig.

Claims (2)

[Claims] (1) In a scanner device that scans a document in main scanning and sub-scanning, stores the scanned image data in a buffer memory, and then transfers it to the host device via an asynchronous interface, the sub-scanning speed is controlled in stages. a data acquisition speed detection means for detecting an average speed of image data acquisition speed of the host device; and a data acquisition speed detection means for detecting an average speed of image data acquisition speed of the host device; What is claimed is: 1. A scanner device comprising: sub-scanning speed setting means, and continuously performing sub-scanning at a sub-scanning speed corresponding to the image data capture speed of a host device. (2) When the host device captures image data in burst mode, the data capture speed detection means detects the average speed during continuous capture of image data, and the sub-scanning speed setting means detects the average speed during continuous capture of image data. 2. The scanner device according to claim 1, wherein the sub-scanning speed is set based on the scanning speed.