JPH0879470A - Image reading device - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents omission of data that occurs when a personal computer having a data reading (receiving) speed slower than the data transfer speed of the image reading device receives the image data from the image reading device. To do. [Structure] A CCD line sensor 11 slides and scans an original to read an image of the original and outputs an analog input image signal. The A / D converter 12 digitizes the analog input image signal and outputs digital image data A. The FIFO memory 13 writes the digital image data A therein as stored image data in response to a write timing signal (timing signal 1) corresponding to the data transfer speed of the scanner 10, and the stored image data is connected to the scanner 10. The read image data B is read in response to the read timing signal (timing signal 2) corresponding to the data reading speed of the personal computer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device (scanner) used as a graphic input device for a computer, and more particularly to an image reading device for a personal computer.

As is well known, an image reading device (scanner) is a device for inputting graphic data to a computer by converting reflected light from a drawing into an electric signal by a photoelectric conversion sensor. The image reading device has a feature that a handwritten figure can be read as it is and in a short time. There are the following three methods for photoelectrically converting graphic data.

A. Optical scanning method This method scans the drawing with a light source that is narrowed down and reads the reflected light with a sensor.
Examples include laser scanning and flying spots.

B. Self-scanning sensor system This system uses a self-scanning sensor with a large number of pixels to read figures on the drawing. As a self-scanning sensor, for example, C
Examples include CDs and photodiode arrays.

C. Mechanical scanning By moving the carriage equipped with the light source and the photo sensor,
Read the figure.

The image reading device can be structurally classified into the following six types. Flatbed scanner, platen moving scanner, drum scanner,
Document transport type scanner, camera type scanner, manual type scanner.

The present invention relates to a flat-bed scanner or a document-conveying scanner, which is a self-scanning sensor type photoelectric conversion system, structurally.

[0008]

2. Description of the Related Art An image reading apparatus of this type scans an original by sliding to read an image of the original, outputs a analog input image signal, and digitizes the analog input image signal. And an A / D converter that outputs digital image data. A CCD line sensor is generally used as the one-dimensional image sensor. Such an image reading device has a data transfer rate synchronized with the drive clock of the one-dimensional image sensor (CCD line sensor). The drive clock is supplied from the timing generation circuit.

There are cases where it is desired to use this image reading device as a figure input device for a personal computer. The personal computer has a data reading (receiving) speed for reading (receiving) data from the outside. The data reading (receiving) speed is defined by the operating speed of the CPU mounted therein. Generally, a personal computer using a low speed CPU reads (receives) data at a speed lower than the data transfer speed of the image reading device.
With speed. Moreover, even a personal computer equipped with the latest CPU (for example, a Pentium processor developed by Intel Corp. in the United States) uses an operating system that shares CPU time in a time sharing method.
A personal computer operated by a system (OS) (for example, Windows 3.1 or Windows NT developed by Microsoft Corporation, USA) has a data reading (receiving) speed slower than the data transfer speed of the image reading device.

Conventionally, when a personal computer having a data reading (receiving) speed slower than the data transfer speed of the image reading device receives the image data from the image reading device, the transfer speed in one line of the image reading device is constant. Due to this, data omission occurred.

[0011]

As described above, in the conventional image reading apparatus, the data transfer rate is in synchronism with the drive clock of the one-dimensional image sensor (CCD line sensor). It was difficult to transfer the image data from the image reading device to the personal computer in synchronization with the data reading (reception) speed of the slower personal computer.

A technical problem of the present invention is that a personal computer having a data read (reception) speed slower than the data transfer speed of an image reading device misses data generated when receiving image data from the image reading device. An object of the present invention is to provide an image reading device capable of preventing the above.

[0013]

SUMMARY OF THE INVENTION An image reading apparatus according to the present invention comprises a one-dimensional image sensor for slidingly scanning a document to read the image of the document and outputting an analog input image signal, and the analog input image. Digitize the signal,
In an image reading device provided with an A / D converter for outputting digital image data, the digital image data is stored therein in response to a write timing signal corresponding to the data transfer speed of the image reading device. And the stored image data in response to a read timing signal corresponding to the data reading speed of a personal computer to which the image reading device is connected,
It is characterized by having a buffer circuit for reading as read image data.

[0014]

Since the image reading device (scanner) is provided with the buffer circuit for converting the image data corresponding to the data transfer speed into the image data corresponding to the data reading (receiving) speed of the personal computer, the image reading device ( It is possible to prevent the omission of data in the personal computer connected to the scanner).

[0015]

The present invention will be described in detail with reference to the drawings.

The connection relationship between the image reading apparatus (scanner) according to the present invention and the personal computer connected thereto will be described with reference to FIGS. 3 and 4. As shown in FIGS. 3 and 4, the image reading device 10 is connected to a printer port 20 of a personal computer.
3 shows the connection relationship when the printer port 20 supports 8-bit bidirectional, and FIG. 4 shows the connection relationship when the printer port 20 does not support 8-bit bidirectional. In FIGS. 3 and 4, the arrow “→” indicates the direction of the signal.

As shown in FIG. 3, when the printer port 20 supports 8-bit bi-direction, the scanner 10
2 to 9 PIN are used as data output terminals D0 to D7 for transferring 8-bit data to the printer port 20, and the data terminals D0 to D7 are data input terminals PD which are 2 to 9 PIN of the printer port 20, respectively.
0 to PD7 are connected. Also, the scanner 10 15P
IN is transfer data transfer ready flag terminal DATA
Used as READY, 16 in printer port 20
It is connected to the error terminal ERROR which is a PIN. On the other hand, the 1PIN strobe terminal STROBE of the printer port 20 outputs a data reception completion signal, and is connected to the 1PIN affirmative response terminal ACK of the scanner 10. The automatic feed terminal AUTOFEED which is 14 PIN of the printer port 20 outputs the 1-line scanning start signal, and the scanning terminal SCAN which is 14 PIN of the scanner 10
Connected to. The printer terminal 20 16PIN initial setting terminal INIT outputs a power supply control signal, and the scanner 10 16PIN power supply control terminal PC.
Connected to NT. The printer port 20 17
The selection input terminal SLCTIN, which is a PIN, outputs a signal indicating the data line transfer direction, and 17PI of the scanner 10
It is connected to the selection input terminal SLCTIN which is N.

As shown in FIG. 4, the connection relationship when the printer port 20 does not support 8-bit bidirectional is the same except that the terminals used for data transfer are different.
It is similar to that shown in FIG. That is, the scanner 10
13 to 11 PIN are data output terminals NB0 to NB for transferring 4-bit data to the printer port 20.
Used as NB3, data output terminals NB0 to NB3
Are 13PIN and 12PI of the printer port 20, respectively.
Select terminals SL which are N, 10 PIN and 11 PIN
It is connected to the CT, the paper out terminal PE, the positive response terminal ACK, and the busy terminal BUSY.

The data transfer timing when the scanner 10 is connected to the printer port 20 of the personal computer as shown in FIGS. 3 and 4 will be described with reference to FIGS. 5 and 6. FIG. 5 shows the data transfer timing when the printer port 20 supports bidirectional transfer as shown in FIG. 3, and FIG. 6 shows that the printer port 20 does not support bidirectional transfer as shown in FIG. The data transfer timing in this case is shown.

First, the data transfer operation when the printer port 20 supports bidirectional transfer will be described with reference to FIG.

The personal computer supplies a signal indicating the data line transfer direction of the logic "L" level to the selection input terminal SLCTIN of the scanner 10 and turns on the power supply control signal supplied to the power supply control terminal PCNT of the scanner 10 (logic "H"). "Level), then scan terminal SCAN
When the 1-line scanning start signal to be supplied to (1) is sent (logic "L" level for a certain period of time), the scanner 10 performs a graphic reading operation. The scanner 10 turns on the transfer data transfer preparation completion flag terminal DATA READY (logic "H" level) and outputs the 1-byte (8-bit) attributes A1 and A2 from the data output terminals D0 to D7 to the data output terminals D0 to D7. Sent from. The personal computer sends a data reception completion signal to the acknowledge terminal ACK of the scanner 10.

The scanner 10 turns off the transfer data transfer preparation completion flag terminal DATA READY (logic "H").
1) from the data output terminals D0 to D7
Byte (8 bits) data D1, D2, D3, D4,
.. are transmitted from the data output terminals D0-7.

As shown in FIG. 6, when the printer port 20 does not support bidirectional transfer, the data transfer operation is basically the same except that one byte is divided into two and transferred. It is similar to that shown in FIG.

The personal computer supplies a signal indicating the data line transfer direction of the logic "H" level to the selection input terminal SLCTIN of the scanner 10 and turns on the power supply control signal supplied to the power supply control terminal PCNT of the scanner 10 (logic "H"). "Level), then scan terminal SCAN
When the 1-line scanning start signal to be supplied to (1) is sent (logic "L" level for a certain period of time), the scanner 10 performs a graphic reading operation. The scanner 10 turns on the transfer data transfer preparation completion flag terminal DATA READY (logic "H" level) and at the same time outputs 4-bit attributes AL1, AH1, AL from the data output terminals D0 to D7.
2 and AH2 are transmitted from the data output terminals NB0 to NB3. Here, the lower-order 4 bits AL1 and the higher-order 4 bits AH1 form one set to form a 1-byte attribute A1. The same applies hereinafter. The personal computer sends a data reception completion signal to the acknowledge terminal ACK of the scanner 10.

The scanner 10 turns off the transfer data transfer preparation completion flag terminal DATA READY (logic "H").
Level), data DL1, DH1, DL2, DH2, D each having 4 bits from the data output terminals NB0 to NB3.
L3, DH3, DL4, DH4, DL5, DH5, ... Are transmitted from the data output terminals NB0 to NB3.

An image reading apparatus according to an embodiment of the present invention will be described with reference to FIG. The illustrated image reading device (scanner) 10 is used as a figure input device for a personal computer, and is connected to a printer port 20 of the personal computer as shown in FIG. 3 or 4. The image reading device 10 has a data transfer rate Rdt, and the personal computer has a data reading (receiving) speed Rdr which is slower than the data transfer rate Rdt.

The illustrated image reading device 10 includes a CCD line sensor 11, an A / D converter 12, a FIFO memory 13, a timing generation circuit 14, an input / output interface controller 15, and an output interface 16.
It has and.

The CCD line sensor 11 performs a sliding scan on a document (not shown) in synchronization with the drive clock supplied from the timing generation circuit 14, reads the image of the document, and outputs an analog input image signal. Work as an original image sensor. The A / D converter 12 responds to the timing signal 1 supplied from the timing generation circuit 14 to digitize the analog input image signal and output digital image data A.

As shown in FIG. 2, the FIFO memory 1
In response to the timing signal 1 supplied from the timing generation circuit 14, 3 writes the digital image data A therein as stored image data. Further, the FIFO memory 13 includes an input / output interface controller 15
In response to the timing signal 2 supplied from, the stored image data is read and the read image data B is output. That is, the FIFO memory 13 uses the timing signal 1 and the timing signal 2 as a write timing signal and a read timing signal, respectively. Here, the timing signal 1 (writing timing signal) corresponds to the data transfer rate Rdt of the image reading device 10, and its cycle is fixed at about 1 μsec. On the other hand, timing signal 2
The (reading timing signal) corresponds to the data reading (receiving) speed Rdr of the personal computer, and its cycle is indefinite. However, the cycle of the timing signal 2 (read timing signal) is always longer than the cycle of the timing signal 1 (write timing signal).

Input / output interface controller 15
Supplies the timing signal 2 (reading timing signal) to the FIFO memory 13. The input / output interface controller 15 uses the positive response terminal A of the scanner 10.
CK (1 PIN), scan terminal SCAN (14 PIN),
Select input terminal SLCTIN (17PIN) and transfer data transfer ready flag terminal DATA READY
It is connected to (15 PIN). Select input terminal SLC
When the signal indicating the data line transfer direction supplied from TIN (17PIN) is at the logic "L" level, the connected printer port 20 supports 8-bit bidirectional, so the input / output interface controller 15
An output instruction for outputting image data in 8 bits is sent to the output interface 16. On the other hand, when the signal indicating the data line transfer direction supplied from the select input terminal SLCTIN (17PIN) is at the logic "H" level, the connected printer port 20 does not support 8-bit bidirectional, so the input / output interface The controller 15 sends an output instruction to the output interface 16 to output the image data in 4 bits.

The output interface 16 converts the read image data B from the FIFO memory 13 into image data corresponding to the printer port 20 based on the output instruction and outputs the image data.

As described above, the image reading apparatus (scanner) 10 of the present embodiment is provided with the FIFO memory 13 for data rate conversion, so it is possible to prevent the omission of data in the personal computer connected thereto. You can

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications and changes can be made without departing from the gist of the present invention. For example, in the above embodiment, the FIFO memory 13 is used as a buffer circuit for converting the image data corresponding to the data transfer rate Rdt of the image reading device 10 into the image data corresponding to the data reading (reception) rate Rdr of the personal computer. However, it goes without saying that it is not limited to this.

[0034]

As described above, according to the present invention, in the image reading device according to the present invention, the image data corresponding to the data transfer speed of the image reading device is converted into the image data corresponding to the data reading (receiving) speed of the personal computer. Since it incorporates a buffer circuit for conversion, data reading (reception) slower than the data transfer rate of the image reading device
It is possible to prevent omission of data that occurs when a high-speed personal computer receives image data from the image reading device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image reading apparatus (scanner) according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the FIFO memory in the image reading apparatus shown in FIG.

FIG. 3 is a diagram showing a connection relationship between an image reading apparatus (scanner) according to the present invention and a printer port of a personal computer when the printer port supports 8-bit bidirectional.

FIG. 4 is a diagram showing a connection relationship between an image reading apparatus (scanner) according to the present invention and a printer port of a personal computer when the printer port does not support 8-bit bidirectional.

5 is a time chart showing data transfer timing when the image reading device (scanner) is connected to the printer port of the personal computer as shown in FIG.

6 is a time chart showing data transfer timing when the image reading device (scanner) is connected to the printer port of the personal computer as shown in FIG.

[Explanation of symbols]

 10 image reading device (scanner) 11 CCD line sensor 12 A / D converter 13 FIFO memory 14 timing generation circuit 15 input / output interface controller 16 output interface 20 printer port of personal computer

Claims (2)

[Claims] 1. A one-dimensional image sensor for slidingly scanning a document to read an image of the document and outputting an analog input image signal, and A for digitizing the analog input image signal and outputting digital image data. In the image reading device provided with a / D converter, the digital image data is written as stored image data therein in response to a write timing signal corresponding to the data transfer rate of the image reading device, and the stored image data is stored. An image reading apparatus having a buffer circuit for reading as read image data in response to a read timing signal corresponding to a data reading speed of a personal computer to which the image reading apparatus is connected. 2. The image reading device according to claim 1, wherein the buffer circuit is a FIFO memory.