JPH11275311A - Picture reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture reader which can execute an enlargement processing in a main scanning direction with an arbitrary output resolution and can read an original picture at a high speed. SOLUTION: A solid state image pickup element for converting one line of an original picture into an electric signal at each picture element, a carriage which relatively moves to the auxiliary scanning direction of an original by a driving means, an A/D converter 12 for converting an analog signal output by a CCD line sensor 10 into a digital signal, a picture processing circuit 13 for enlarging and reducing the digital signal of the original picture which is read and a CPU 17 for controlling the moving speed of the carriage so that processing time of the original picture for one line is equal to time when picture data can be outputted and for adjusting the read speed of the picture are provided for a picture reader.

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 used for facsimile machines, digital copiers, scanners, etc., for reading a document image.

[0002]

2. Description of the Related Art In recent years, workstations, personal computers, and the like have been enhanced in function, and editing of images, character filing by electronic filing, OCR, and the like can be processed at high speed. Along with this, image scanners that can easily capture a document image with good reproducibility have become widespread, and this image scanner is also required to have higher resolution and faster image input.

Hereinafter, a conventional image reading apparatus will be described with reference to the drawings. 7 is a schematic diagram showing a conventional image reading device, FIG. 8 is a block diagram showing a circuit configuration of the image reading device of FIG. 7, and FIG. 9 is a schematic diagram of a CCD line sensor in the image reading device of FIG. FIG. 10 is a chart showing an operation, and FIG. 10 is a chart showing a schematic operation of a resolution conversion process in the image reading apparatus of FIG.

[0004] As shown in FIG.
A light source 7 of each color for irradiating light to the original 2 placed on the original glass 3 fitted on the upper part of the apparatus main body 1 and a reflection for guiding the reflected light (or transmitted light) from the original 2 to the imaging lens 9 1 of the original image formed by the mirror 8 and the image forming lens 9
It has a CCD line sensor (solid-state image sensor) 10 for converting a line into an electric signal for each pixel. And
The carriage 4 on which the light source 7, the reflection mirror 8, the imaging lens 9, and the CCD line sensor 10 are mounted is provided with a driving wire wound around a driving pulley 21 driven by a driving motor (driving means) 5 and a driven pulley 22. 6 fixed. Further, the carriage 4 is slidably fitted on a guide shaft (not shown) extending in the sub-scanning direction.
As a result, the carriage 4 is moved in the sub-scanning direction of the document 2. Note that the document 2 may be moved instead of the carriage 4.

A white reference member 20 for performing shading correction is attached to an end of the original glass 3.

[0008] As shown in FIG. 8, the image reading device comprises an analog processing circuit 1 for amplifying, sampling and holding an image signal obtained from the CCD line sensor 10.
1. an A / D converter (A / D conversion means) 12 for converting an analog signal of the analog processing circuit 11 into a digital signal;
An image processing circuit (image processing means) 13 for performing shading correction, filter processing, resolution conversion processing such as image enlargement / reduction on the converted digital signal, and temporarily performs image data processing when the image processing circuit 13 performs image processing. An interface (I) for exchanging data between the stored image processing memory 14, the image processing circuit 13 and the external device.
/ F) 15, a CCD line sensor 10, an analog processing circuit 11, a timing generation circuit 16 for controlling the operation timing of the A / D converter 12 and the image processing circuit 13, a CPU (control means) 17 for controlling the entire apparatus, It comprises a program ROM / CPU work memory 18 in which a control program for the CPU and a memory for work are stored, and a carriage drive control unit 19 for controlling the operation of the carriage.

Next, the operation of the image reading apparatus having such a configuration will be described. First, when a document reading command is issued, the carriage 4 moves to the position of the white reference member 20. When the carriage 4 stops at that position, the light source 7
Lights up. The luminous flux of the light source 7 is applied to the white reference member 20, and the reflected light is guided to the image forming lens 9, where the image is formed on the CCD line sensor 10 and photoelectrically converted. The output signal of the CCD line sensor 10 is amplified by the analog processing circuit 11, A / D converted by the A / D converter 12, and stored as bright correction data.

After the reading of the white reference member 20 is completed,
The reading operation in the dark is started. The output signal of the CCD line sensor 10 is similarly amplified by the analog processing circuit 11, input to the A / D converter 12, and stored as dark correction data.

[0009] Shading correction data is created from the light correction data and the dark correction data, and shading correction is performed on the subsequent document read data using the correction data.

After the shading correction data is obtained,
The light source 7 is turned on again to drive the carriage 4 at a constant speed. At this time, the moving speed of the carriage 4 is set according to the designation of the resolution in the sub-scanning direction set in advance by the host. For example, if the reading resolution in the sub-scanning direction is 60
If the accumulation time (corresponding to one line processing time) of the CCD line sensor 10 is 8 msec at 0 dpi, a moving speed of 5.25 mm / s is set. When the carriage 4 reaches the reading start point of the document 2, the image reading operation is started.

The reflection image of the read portion of the original 2 is formed on the CCD line sensor 10 in the same manner as when shading correction data is obtained, and is converted into digital data by the A / D converter 12. Then, shading correction is performed on the image data. The data after the correction operation is output to a host computer (not shown) through the interface 15 after a filtering operation and a resolution conversion process for enlargement / reduction are performed inside the image processing circuit 13.

Here, as in the previous example, it is assumed that the operation is performed with the reading resolution in the sub-scanning direction specified as 600 dpi.

As shown in FIG. 9, the CCD line sensor 1
When the accumulation time of 0 is generalized to δt, the signal read in the interval from t to t + δt in the sampling timing signal (pulse interval corresponds to the accumulation time) of the CCD line sensor 10 is the waveform of the CCD line sensor output data. As shown in (1), output is delayed by one line. Similarly, the signal read in the interval from t + δt to t + 2δt is output after being delayed by one line as shown in the waveform of the CCD line sensor output data.

The output data of the CCD line sensor 10 is
Amplified, sampled and held by the analog processing circuit 11,
A / D conversion is performed by the A / D converter 12. And FIG.
As shown in (1), the image data after the A / D conversion is input to the image processing circuit 13 on a line-by-line basis by designating an effective area of digital image data by an input vertical area effective signal / input horizontal area effective signal. The input vertical area effective signal is a signal for specifying an effective area in the vertical direction (sub-scanning direction) of the document image data, and has an L level in the effective area. The input horizontal area effective signal is a signal for specifying an effective area in the horizontal direction (main scanning direction) of the document image data, and has an L level in the effective area. In this way, the image data when the input vertical area valid signal and the input horizontal area valid signal are simultaneously at the L level are valid, and the sections α (1), α
(2) The image data between... Becomes valid.

A resolution conversion process is performed inside the image processing circuit 13, and when the resolution conversion process for enlarging in the main scanning direction is performed, as shown in the waveform of the output data in FIG. In order to store the data in the processing memory 14, the input data is output with a delay of one line. As shown in FIG. 10, when the enlargement process is performed, the effective section (corresponding to the L level section) of the output horizontal area effective signal increases because the amount of image data per line increases. Output data valid section β (1), β (2),... For 1), α (2),.
Becomes longer. On the other hand, when the reduction processing is performed in the main scanning direction, the effective area (corresponding to the L level) of the output horizontal area effective signal decreases because the image data amount per line decreases, and the input data effective area α (1 ), Α (2), ...
, The output data valid section γ (1), γ (2),.
・ Becomes shorter. However, in this case, it is assumed that the bandwidth and the transfer cycle of the image data input / output for the resolution conversion processing are equal.

[0016]

In such a conventional image reading apparatus, when the enlargement processing in the main scanning direction is performed by the resolution conversion processing inside the image processing circuit, the output resolution is limited. That is, when the effective section of the output data after the resolution conversion processing (L section of the output horizontal direction effective signal) is expanded to a data amount exceeding one line processing time (accumulation time δt), within one line processing time The image data cannot be output, and the conversion process can be performed only up to the output resolution such that the effective section of the output data after the resolution conversion process is within one line processing time.

On the other hand, when reducing in the main scanning direction by the resolution conversion processing, as shown in FIG. 10, the output data amount after the resolution conversion processing decreases, and the output data effective section (γ
(1), γ (2),...) Are considerably smaller than the one-line processing time. In this case, the reading time can be shortened by increasing the reading speed (decreasing the accumulation time), but in order to perform reading at a constant reading speed, an unnecessary reading time is required.

Further, when the enlargement processing in the sub-scanning direction is performed by the resolution conversion processing, it is necessary to store the image data over a plurality of lines.

Accordingly, an object of the present invention is to provide an image reading apparatus capable of performing an enlargement process at an arbitrary output resolution in the main scanning direction.

Further, according to the present invention, when performing a reduction process,
It is an object of the present invention to provide an image reading device capable of reading a document image at high speed.

A further object of the present invention is to provide an image reading apparatus capable of reducing the capacity of an image processing memory used for resolution conversion processing.

[0022]

In order to solve this problem, an image reading apparatus according to the present invention comprises a light source for irradiating a document, an image forming lens for forming an image of reflected light or transmitted light from the document, and an image forming lens. A solid-state imaging device for converting one line of the original image formed by the image lens into an electric signal for each pixel, a light source, an imaging lens, and a solid-state imaging device are mounted. A / D converter for converting an analog signal output from the solid-state image sensor into a digital signal, and image processing for enlarging and reducing the digital signal of the read original image in the main scanning direction Means for controlling the processing time for one line of the original image to be a time during which image data can be output during the enlargement processing and the reduction processing of the original image by the image processing means. By controlling the moving speed of the ridge is obtained by a configuration in which a control means for adjusting the reading speed of the image.

As a result, it is possible to perform the enlargement processing at an arbitrary output resolution in the main scanning direction, and it is possible to perform high-speed reading of a document image.

According to the image reading apparatus of the present invention, in the above-described image reading apparatus, the control means reduces the moving speed of the carriage by the driving means during the enlargement processing of the original image by reading the image. Since the speed is reduced and the image data can be output within one line processing time, the enlargement processing can be performed at an arbitrary output resolution in the main scanning direction.

According to the image reading apparatus of the present invention, in the above-described image reading apparatus, the control means increases the moving speed of the carriage by the driving means during the reduction processing of the document image as compared with the normal processing to reduce the image reading speed. Since the carriage movement speed is higher than in the normal reading mode, high-speed reading of a document image can be performed.

An image reading apparatus according to the present invention includes a light source for irradiating an original, an imaging lens for forming an image of reflected light or transmitted light from the original, and an image of the original image formed by the imaging lens.
A solid-state image sensor for converting an electric signal into an electric signal for each pixel with respect to a line, a carriage on which a light source, an imaging lens and a solid-state image sensor are mounted, and which is relatively moved in a sub-scanning direction of a document by a driving unit; A / D conversion means for converting an analog signal output from the digital signal into a digital signal, image processing means for reducing the digital signal of the read document image in the sub-scanning direction, and sub-scanning direction output by the image processing means. Control means for controlling the moving speed of the carriage so as to read the original image at a reading resolution higher than the output resolution. The capacity of the image processing memory used for the resolution conversion processing can be configured with only one line Therefore, the capacity of the image processing memory is reduced, and the cost of the memory can be reduced.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an image is formed by a light source for irradiating an original, an imaging lens for imaging reflected light or transmitted light from the original, and an imaging lens. A solid-state imaging device for converting one line of the original image into an electric signal for each pixel, a carriage mounted with a light source, an imaging lens and a solid-state imaging device, and relatively moved in a sub-scanning direction of the original by a driving unit; A / D conversion means for converting an analog signal output from a solid-state imaging device into a digital signal, image processing means for enlarging and reducing a digital signal of a read original image in the main scanning direction, and image processing means In the enlargement processing and reduction processing of the original image, the moving speed of the carriage is controlled so that the processing time for one line of the original image becomes a time in which image data can be output. An image reading apparatus having a control means for adjusting the reading speed of the image reading device, which can perform an enlargement process at an arbitrary output resolution in the main scanning direction, and can perform a high-speed reading of a document image. Have.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means reduces the moving speed of the carriage by the drive means during the enlargement processing of the original image, as compared with the normal processing. This is an image reading device that slows down the image reading speed, and can output image data within one line processing time, so that it is possible to perform enlargement processing at an arbitrary output resolution in the main scanning direction. Have.

According to a third aspect of the present invention, in the first aspect of the present invention, the control means increases the moving speed of the carriage by the driving means during the reduction processing of the original image as compared with the normal processing. This is an image reading apparatus that increases the reading speed of an image, and has a function of enabling high-speed reading of a document image because the carriage movement speed is higher than in the normal reading mode.

According to a fourth aspect of the present invention, there is provided a light source for irradiating an original, an imaging lens for imaging reflected light or transmitted light from the original, and one of the original images formed by the imaging lens. A solid-state image sensor for converting an electric signal into an electric signal for each pixel with respect to a line, a carriage on which a light source, an imaging lens and a solid-state image sensor are mounted, and which is relatively moved in a sub-scanning direction of a document by a driving unit; A / D conversion means for converting an analog signal output from the digital signal into a digital signal, image processing means for reducing the digital signal of the read document image in the sub-scanning direction, and sub-scanning direction output by the image processing means. Control means for controlling the moving speed of the carriage so as to read the original image at a reading resolution higher than the output resolution. Since the capacity of the image processing memory becomes configurable only one line to be used for the capacity of the memory for image processing is reduced with the effect that it is possible to reduce the cost of the memory.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a schematic diagram showing an image reading apparatus according to Embodiment 1 of the present invention, FIG. 2 is a block diagram showing a circuit configuration of the image reading apparatus of FIG. 1, and FIG. FIG. 4 is a chart showing a schematic operation of a resolution conversion process in a normal reading mode in the apparatus; FIG. 4 is a chart showing a schematic operation of a resolution conversion process in an enlarged reading mode in the image reading device of FIG. 1; FIG. 3 is a chart showing a schematic operation of a resolution conversion process in a reduced reading mode in the image reading apparatus of FIG. 1.

As shown in FIG. 1, the image reading device comprises:
A light source 7 of each color for irradiating light to the original 2 placed on the original glass 3 fitted on the upper part of the apparatus main body 1; a reflecting mirror 8 for guiding the reflected light from the original 2 to the imaging lens 9; CCD for converting an image formed by the image lens 9 into an electric signal
It has a line sensor 10. A carriage 4 on which a light source 7, a reflection mirror 8, an imaging lens 9, and a CCD line sensor (solid-state image sensor) 10 are mounted is hung on a drive pulley 21 driven by a drive motor (drive means) 5 and a driven pulley 22. It is fixed to the passed drive wire 6. Further, the carriage 4 is slidably fitted on a guide shaft (not shown) extending in the sub-scanning direction.
A white reference member 20 for performing shading correction is attached to an end of the original glass 3.

As shown in FIG. 2, the image reading device comprises an analog processing circuit 1 for amplifying, sampling and holding an image signal obtained from the CCD line sensor 10.
1. an A / D converter (A / D conversion means) 12 for converting an analog signal of the analog processing circuit 11 into a digital signal;
An image processing circuit (image processing means) 13 that performs shading correction, filter processing, image enlargement processing / reduction processing, and the like on the converted digital signal, and temporarily stores image data when the image processing circuit 13 performs image processing. An image processing memory 14, an interface (I / F) 1 for exchanging data between the image processing circuit 13 and an external device.
5, CCD line sensor 10, analog processing circuit 11,
A timing generation circuit 16 for controlling the operation timing of the A / D converter 12 and the image processing circuit 13, a CPU (control means) 17 for controlling the entire apparatus, a program ROM for storing a CPU control program and a work memory -It comprises a CPU work memory 18 and a carriage drive control unit 19 for controlling the operation of the carriage.

Next, the operation of the image reading apparatus having such a configuration will be described. In the operation of reading a document image by the scanner, first, when a document reading command is issued from an external host (not shown), the CPU 17 rotates the drive motor 5, whereby the carriage 4 moves to the position of the white reference member 20. I do. When detecting that the carriage 4 has reached that position, the CPU 17 stops the carriage 4 and turns on the light source 7. The light flux of the light source 7 is applied to the white reference member 20, and the reflected light is guided to the imaging lens 9 by the reflection mirror 8. And the CCD line sensor 1
An image is formed at 0 and photoelectrically converted. CCD line sensor 10
Is amplified by the analog processing circuit 11 and
/ D converter 12. The data A / D converted by the A / D converter is stored as bright correction data.

After the reading of the white reference member 20 is completed,
The CPU 17 turns off the light source 7 and starts a dark reading operation. The output signal of the CCD line sensor 10 is similarly amplified by the analog processing circuit 11 and input to the A / D converter 12. The A / D converted data is stored as dark correction data.

The shading correction data is created from the light correction data and the dark correction data. Then, the shading correction is performed on the subsequent document read data using the correction data.

After the shading correction data is obtained,
The light source 7 is turned on again to drive the carriage 4 at a constant speed. At this time, the moving speed of the carriage 4 is set according to the designation of the resolution in the sub-scanning direction set in advance by the host. For example, if the reading resolution in the sub-scanning direction is 60
If the accumulation time (corresponding to one line processing time) of the CCD line sensor 10 is 8 msec at 0 dpi, a moving speed of 5.25 mm / s is set. CP
When U17 detects that the carriage 4 has reached the reading start point of the document 2, it outputs an operation command to the timing generation circuit 16 to start the image reading operation. The reflected image of the read portion of the original 2 is formed on the CCD line sensor 10 in the same manner as when the shading correction data is obtained, and the A / A
The data is converted into digital data by the D converter 12. This image data is subjected to shading correction by the previously stored shading correction data. The data after the correction operation is subjected to a filter operation and a resolution conversion process for enlargement / reduction within the image processing circuit 13,
The data is output to a host computer (not shown) through the interface 15.

Here, the reading resolution in the sub-scanning direction is 6
It is assumed that the operation is performed by specifying 00 dpi.

As shown in FIG. 3, in the normal reading mode, the accumulation time of the CCD line sensor 10 is generalized to δ.
When t is set, the signal read in the section from t to t + δt in the sampling timing signal (pulse interval corresponds to the accumulation time) of the CCD line sensor 10 is the CCD signal.
As shown in the waveform of the line sensor output data, the output is delayed by one line.

The output data of the CCD line sensor 10 is amplified, sampled and held by an analog processing circuit 11 and A / D converted by an A / D converter 12. The image data after the A / D conversion is input to the image processing circuit 13 on a line-by-line basis by designating an effective area of digital image data by an input vertical area effective signal / input horizontal area effective signal.

The input vertical area effective signal is a signal for designating an effective area in the vertical direction (sub-scanning direction) of the original image data.
In the effective area, the level becomes L level. The input horizontal area effective signal is a signal for specifying an effective area in the horizontal direction (main scanning direction) of the document image data, and has an L level in the effective area. In this way, the image data when the input vertical area valid signal and the input horizontal area valid signal are simultaneously at the L level are valid, and in FIG. 3, during the sections a (1), a (2),. The image data becomes valid.

A resolution conversion process is performed inside the image processing circuit 13, and when a resolution conversion process for enlarging in the main scanning direction is performed, as shown in FIG. Is output with a delay of one line in order to store the data. When the enlargement process in the main scanning direction is performed in the normal reading mode, the effective section (corresponding to the L-level section) of the output horizontal effective signal increases because the amount of image data per line increases. The output data valid sections b (1), b (2),... Are longer than the data valid sections a (1), a (2),. Here, the output data valid section b (1), b (2),...
Is less than the accumulation time δt, the image data can be output within one line processing time.

On the other hand, in the enlarged reading mode shown in FIG. 4, the carriage moving speed is reduced by the CPU 17 to a predetermined speed, and the reading resolution in the sub-scanning direction is increased to six.
An operation chart in the case where the reading is performed with 00 dpi maintained is shown.

As shown in the figure, the accumulation time is δt ′ (δt ′> δt) due to the slower carriage moving speed.
> A (1), a (2),...). In the enlarged reading mode in which the carriage moving speed is slower than that in the normal reading mode, the amount of image data per line increases due to the enlargement processing in the main scanning direction, and one line processing time in the normal reading mode (equivalent to the accumulation time δt) This mode is set to increase the processing time of one line because image data cannot be output within the period. The carriage moving speed in this enlarged reading mode is
One or a plurality of types are set in advance in accordance with the output image data amount in the main scanning direction set in association with the enlargement processing.

As shown in FIG. 4, the CCD line sensor 1
In the 0 sampling timing signal (pulse interval corresponds to the accumulation time), the signal read between t ′ and t ′ + δt ′ is output with a delay of one line. The output data of the CCD line sensor 10 is amplified and sampled and held by the analog processing circuit 11, and the A / D
D conversion is performed. The image data after the A / D conversion is input to the image processing circuit 13 on a line-by-line basis by designating the effective area of the digital image data by the input vertical area effective signal and the input horizontal area effective signal as in the normal reading mode. You. Here, the input image data amount per line is the same as that in the normal reading mode. Therefore, the valid section of the input image data is a (1), a (2),
... is the same as

As described above, when the resolution conversion processing is performed inside the image processing circuit 13, the input image data is temporarily stored in the image processing memory 14 for the conversion processing, so that the output is delayed by one line. Is done. The enlargement process increases the image data amount per line, and the output data valid sections are c (1) and c (2) for the input data valid sections a (1), a (2),. , ... becomes longer. However, in the enlarged reading mode in which the carriage moving speed is slow, one line processing time (corresponding to the accumulation time)
Exceeds the output data valid section c (1), c (2),..., It is possible to output image data within one line processing time.

Next, in the reduced reading mode shown in FIG.
The moving speed of the carriage 4 is increased to a predetermined speed by the PU 17, and the reading resolution in the sub-scanning direction is increased to 60.
An operation chart in the case of reading with 0 dpi is shown.

As shown in the figure, the accumulation time δt ″ (a (1), a
(2),... <Δt ″ <δt) In the reduced reading mode in which the carriage moving speed is faster than the normal reading mode, the image data amount per line is reduced by the reduction processing in the main scanning direction. The carriage movement speed in the reduced reading mode is set in accordance with the output image data in the main scanning direction set in the reduction process. One or more types are set in advance according to the amount.

As shown in FIG. 5, the CCD line sensor 1
In a sampling timing signal of 0 (the pulse interval corresponds to the accumulation time), a signal read between t ″ and t ″ + δt ″ is output with a delay of one line. The output data of the CCD line sensor 10 is analog processed The signal is amplified and sampled and held by the circuit 11, and the A / D converter 12
D conversion is performed. The image data after the A / D conversion is input to the image processing circuit 13 on a line-by-line basis by designating the effective area of the digital image data by the input vertical area effective signal and the input horizontal area effective signal as in the normal reading mode. You. Here, the input image data amount per line is the same as that in the normal reading mode. Therefore, the valid section of the input image data is a (1), a (2),
... is the same as

As described above, inside the image processing circuit 13,
When the reduction process in the main scanning direction is performed by the resolution conversion process, the input image data is temporarily stored in the image processing memory 14 for the conversion process, and is output with a delay of one line. Then, the image data amount per line is reduced by the reduction process, and the input data valid sections a (1), a
(2),... The output data valid section is d
(1), d (2),... However,
Since the carriage movement speed is higher in the reduced reading mode than in the normal reading mode, the document image can be read at a higher speed.

The image processing circuit 13 only needs to be capable of performing at least one of enlargement processing and reduction processing in the main scanning direction on the digital signal of the read document image. It is not necessary that both processes can be performed.

(Embodiment 2) FIG. 6 is a chart showing a schematic operation of a resolution conversion process in the sub-scanning direction of an image reading apparatus according to Embodiment 2 of the present invention. In addition,
The structure and the circuit configuration of the image reading apparatus according to the present embodiment are the same as those shown in FIGS.
Is similar to that shown in FIG. Therefore, in the following description, the members corresponding to those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

The operation of the image reading apparatus according to this embodiment will be described with reference to FIG. The operation of reading a document image by the scanner is the same as that described in the first embodiment.

The moving speed of the carriage is set in advance so that the reading resolution in the sub-scanning direction is higher than the output resolution after the resolution conversion. That is, the moving speed of the carriage is set in advance so that the resolution conversion processing in the sub-scanning direction is always a reduction processing. If the output resolution in the sub-scanning direction is set by a user or the like, the carriage moving speed is determined by the CPU 17 from a plurality of preset types at which the document image can be read at a higher reading resolution. You.

Here, consider the operation in the case where the output resolution in the sub-scanning direction after the resolution conversion is designated as 300 dpi and the original image is read at a reading resolution of 600 dpi which is larger than that.

The output data of the CCD line sensor 10 is amplified, sampled and held by the analog processing circuit 11,
A / D conversion is performed by the / D converter 12. The image data after the A / D conversion is input to the image processing circuit 13 on a line-by-line basis by designating an effective area of digital image data by an input vertical area effective signal / input horizontal area effective signal.

The input vertical area effective signal is a signal for designating an effective area in the vertical direction (sub-scanning direction) of the original image data.
In the effective area, the level becomes L level. The input horizontal area effective signal is a signal for specifying an effective area in the horizontal direction (main scanning direction) of the document image data, and has an L level in the effective area. In this way, the image data when the input vertical area valid signal and the input horizontal area valid signal are simultaneously at the L level are valid, and the section a
The image data between (1), a (2),... Becomes valid.

First, when the image data of the first line is input, the image data is stored and held in the image processing memory 14. The sub-scanning insertion line in FIG. 6 is coordinate data representing the line position of the image data to be output with respect to the line of the input image data, and has a sub-scanning direction output resolution of 300 dpi and a sub-scanning direction reading resolution of 600 dpi.
In the case of i, by incrementing by 600 dpi / 300 dpi = 2, it changes as 1, 3, 5, 7,... (the initial value is 1). That is, the image data of the first, third, fifth, seventh,... Lines of the input image data are the line positions of the output image data with respect to the input image data. When the image data of the first line is input, the initial value remains at 1, and thereafter, the output horizontal direction valid signal is incremented at a transition point from L level to H level.

Next, when the image data of the second line is input, the image data of the first line is read from the image processing memory 14, and the input image data of the second line is written. In order to perform resolution conversion processing in the sub-scanning direction from the image data of the first and second lines, an operation using a generally used primary interpolation method is performed.

In the arithmetic processing by the primary interpolation method, the data of the first line and the data of the second line are proportionally distributed using the decimal part of the sub-scanning insertion line, and are used as output data. In this case, since the decimal part of the sub-scan insertion line is 0, the data of the first line is output as it is. The output vertical area valid signal is at L level in the second and subsequent lines, and the output horizontal area valid signal is low when the integer part of the sub-scan insertion line and the readout line of the image processing memory 14 are equal.
Level. In the case of the second line, since it is equal, the level becomes L level, and the sub-scanning insertion line is incremented to 3 at the change point from L level to H level.

Next, when the image data of the third line is input, the image data of the second line is read from the image processing memory 14, and the input image data of the third line is written. The resolution conversion processing in the sub-scanning direction is performed by primary interpolation from the image data of the second and third lines and the decimal part of the sub-scan insertion line. 0, so 2
The data of the line is output as it is. Since the integer part of the sub-scan insertion line and the read line of the image processing memory 14 are not equal to each other, the output horizontal area effective signal does not become L level, and the sub-scan insertion line is not incremented.

Next, when the image data of the fourth line is input, the image data of the third line is read from the image processing memory 14 and the input image data of the fourth line is written. Similarly, the resolution conversion processing in the sub-scanning direction is performed by the primary interpolation method from the image data of the third and fourth lines and the decimal part of the sub-scan insertion line. Since the value is 0, the image data of the third line is output as it is. The output horizontal area valid signal is L because the integer part of the sub-scanning insertion line is equal to the readout line of the image processing memory 14.
Level, and the sub-scanning insertion line is incremented to 5 at the change point from the L level to the H level.

After that, the same processing as the fifth, sixth,... Lines is performed to output the first, third, fifth,. 600 dpi → 300
A resolution conversion process in the sub-scanning direction of dpi can be performed.

As described above, reading is always performed at a reading resolution higher than the output resolution, and the resolution conversion processing in the sub-scanning direction is reduced, so that the capacity of the image processing memory 14 used for the resolution conversion processing is only one line. Therefore, the cost of the memory can be reduced.

[0065]

As described above, according to the present invention, there is obtained an effective effect that the enlargement process can be performed at an arbitrary output resolution in the main scanning direction.

Further, according to the present invention, an effective effect that high-speed reading of a document image can be obtained is obtained.

According to the present invention, the capacity of the image processing memory used for the resolution conversion processing can be constituted by only one line, so that the capacity of the image processing memory is reduced and the cost of the memory is reduced. An effective effect that it becomes possible is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an image reading device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of the image reading apparatus of FIG. 1;

FIG. 3 is a chart showing a schematic operation of a resolution conversion process in a normal reading mode in the image reading apparatus of FIG. 1;

FIG. 4 is a chart showing a schematic operation of a resolution conversion process in an enlarged reading mode in the image reading device of FIG. 1;

5 is a chart showing a schematic operation of a resolution conversion process in a reduced reading mode in the image reading apparatus of FIG. 1;

FIG. 6 is a chart illustrating a schematic operation of a resolution conversion process in a sub-scanning direction of the image reading device according to the second embodiment of the present invention.

FIG. 7 is a schematic diagram showing a conventional image reading apparatus.

FIG. 8 is a block diagram illustrating a circuit configuration of the image reading device of FIG. 7;

9 is a chart showing a schematic operation of a CCD line sensor in the image reading device of FIG. 7;

FIG. 10 is a chart showing a schematic operation of a resolution conversion process in the image reading apparatus of FIG. 7;

[Explanation of symbols]

 2 Document 4 Carriage 5 Drive motor (drive means) 7 Light source 9 Imaging lens 10 CCD line sensor (solid-state image sensor) 12 A / D converter (A / D conversion means) 13 Image processing circuit (image processing means) 17 CPU (Control means)

Claims (4)

[Claims] A light source for irradiating the original; an imaging lens for forming an image of reflected light or transmitted light from the original; and an electric source for each pixel of the original image formed by the imaging lens. A solid-state imaging device that converts the signal into a signal; a carriage on which the light source, the imaging lens and the solid-state imaging device are mounted, and which relatively moves in a sub-scanning direction of the document by a driving unit; and an analog signal from the solid-state imaging device. A / D conversion means for converting an output into a digital signal, image processing means for enlarging and reducing the read digital signal of the original image in the main scanning direction, and the original image in the image processing means The moving speed of the carriage is adjusted so that the processing time for one line of the original image becomes a time during which image data can be output during the enlargement processing and the reduction processing. Controlling the image reading apparatus characterized by a control means for adjusting the reading speed of the image. 2. The apparatus according to claim 1, wherein said control means reduces the moving speed of said carriage by said driving means during the enlargement processing of said document image as compared with a normal processing time to reduce the image reading speed. Item 2. The image reading device according to Item 1. 3. The image processing apparatus according to claim 1, wherein the control unit increases a moving speed of the carriage by the driving unit during a reduction process of the document image compared to a normal process to increase a reading speed of the image. Item 2. The image reading device according to Item 1. 4. A light source for irradiating a document, an image forming lens for forming an image of reflected light or transmitted light from the document, and an electric signal for each pixel for one line of the document image formed by the image forming lens. A solid-state imaging device that converts the signal into a signal; a carriage on which the light source, the imaging lens and the solid-state imaging device are mounted, and which relatively moves in a sub-scanning direction of the document by a driving unit; and an analog signal from the solid-state imaging device. A / D conversion means for converting an output into a digital signal; image processing means for reducing the digital signal of the read original image in a sub-scanning direction; output in the sub-scanning direction for outputting by the image processing means Control means for controlling a moving speed of the carriage so as to read the document image at a reading resolution larger than the resolution. Look-up device.