JP2001028669A - Scanner and image processing unit provided with the scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanner that reads an image with a plurality of resolutions, reads a range of resolution being an integer multiple or the reciprocal of an integer multiple of a basic resolution with high accuracy, enhances the accuracy of subscanning for thinning processing in the case of an intermediate resolution and enhances the read image quality. SOLUTION: A width W of subscanning one line in matching with a basic resolution is set equally to a value of (n) (integer) times the moving amount of one step of a stepping motor 2. When the stepping motor is driven, a 3-line CCD 11 is driven at a rate of once per n-steps to read an image with a basic resolution. By choosing the set value (n) of the basic resolution to have divisors, then the reading of the image with the basic resolution and a resolution being an integer multiple of the basic resolution can simply be changed in the case of changing the (n) to set magnification of the subscanning. Since the reading data are based on reading data with the resolution expressed in a simple numerical value, the line thinning at an equal interval can simply be attained and the reading accuracy of the intermediate resolution can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner used for reading a document, and more particularly to a scanner capable of reading a plurality of resolutions by changing its operation, and a document image such as a copying machine or a facsimile equipped with the scanner. The present invention relates to an image processing apparatus using data.

[0002]

2. Description of the Related Art Conventionally, a scanner has been used for reading a document image in a copying machine, a facsimile or the like. In reading an original by a scanner, a line-type CCD image sensor in which a plurality of photoelectric conversion elements (pixels) are arranged is used, and the image of the original read by the pixel rows is scanned in the line direction by pixels (referred to as “main scanning”). )
It is output as an image signal. The relationship between the sensor and the original when the original is read using the line-type sensor is such that the original is relatively moved in a direction intersecting the main scanning direction with respect to the sensor (referred to as “sub-scanning”), thereby reading the entire original. The reading method is adopted. According to this method, the reading resolution in the sub-scanning direction is determined by the moving amount in the sub-scanning direction per one line in the main scanning. Therefore, conventionally, a desired resolution is set in consideration of the relationship between the main and sub-scanning. The method has been adopted.

In implementing this method, the amount of movement of an original document which is sub-scanned by a stepping motor via a driving mechanism in N steps (N: an integer equal to or more than 1) is determined by a movement amount at which a target resolution can be obtained. By designing a stepping motor and a driving mechanism so as to match the amount, and performing one line of main scanning in a cycle of N steps (for the number of steps for obtaining a target resolution) for driving the stepping motor, It has been proposed to read the resolution.

[0004]

However, according to the above-mentioned proposal, if the reading by the main scanning is performed at a period of N steps, the reading of the target resolution can be performed, so that the apparatus is simplified. Although the reading accuracy is ensured, the technical problem of further switching the sub-scanning resolution or performing resolution conversion on the data after reading to obtain image data of different resolutions. Not a solution.
The present invention has been made in view of such a situation in the related art, and an object of the present invention is to further enable reading of a plurality of resolutions and to provide a plurality of resolutions in an integral multiple of the basic resolution or in a resolution area that is a multiple of an integer. And an image processing apparatus provided with the scanner, which makes it possible to perform reading at a high resolution with high accuracy, improves the accuracy of sub-scanning (line) thinning processing at the time of intermediate resolution, and improves reading image quality. It is in.

[0005]

According to a first aspect of the present invention, there is provided a line sensor for reading an original image, and a scanning carriage provided with means for scanning and inputting the original image to the line sensor, the scanning carriage being movable in a sub-scanning direction. , A scanning carriage driving device including a stepping motor and a transmission mechanism, wherein the scanning carriage and the line sensor are expressed by the following formula: W ≒ P × n, where W: width of one line of sub-scanning, P: stepping motor Moving amount of the scanning carriage when sending one step,
n: an integer, and the scanning is performed once every n steps of the stepping motor.
In a scanner for outputting a read image signal for a line, n has a plurality of divisors, and a plurality of resolutions are read according to each of the divisors by setting the plurality of divisors. Configure the scanner.

According to a second aspect of the present invention, there is provided a line sensor for reading an original image, a scanning carriage loaded with a means for scanning and inputting the original image to the line sensor and movable in the sub-scanning direction, a stepping motor, and a transmission. A scanning carriage driving device comprising a mechanism, wherein the scanning carriage and the line sensor have the following formula: P ≒ W × n, where W: width of one sub-scanning line, P: stepping motor sent by one step Movement amount of the scanning carriage at the time,
a plurality of values are set to n in a scanner configured to be driven in accordance with n: an integer and performing n-times scanning while the stepping motor performs one step and outputting a read image signal of n lines. Is used to read a plurality of resolutions corresponding to each value.

According to a third aspect of the present invention, in the scanner according to the first or second aspect, the output of the line sensor is thinned out at equal intervals.

According to a fourth aspect of the present invention, there is provided an image processing apparatus comprising the scanner according to any one of the first to third aspects.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanner according to the present invention will be described with reference to the following embodiments shown in the accompanying drawings. FIG. 1 is a schematic diagram illustrating a configuration of a scanner driving device according to the present embodiment. In FIG. 1, 1 is a scanning carriage, 2 is a stepping motor, 3 is a small gear, 4 is a large gear, 5, 6
Is a pulley, 7 is a belt, and 8 is a sensor. The configuration and operation of the scanner driving device shown in FIG. 1 will be described. A scanning carriage 1 for scanning a color document placed on a document table (not shown) is provided inside a scanning carriage 1 for illuminating a color document image. A lamp, an optical imaging system for reading a color original image, and a three-line CCD are provided (all not shown). A small gear 3 is attached to an output shaft of the stepping motor 2, and a large gear 4 meshing with its teeth is supported so as to rotate integrally with a pulley 5. A belt 7 is hung on the pulley 5 and the other end is hung on another pulley 6. The scanning carriage 1 is fixed to a part of the belt 7, and moves with the belt 7 driven by the small gear 3, the large gear 4, the pulley 5, and the belt 7 by the driving of the stepping motor 2. A sensor 8 is provided near one end of the belt 7, and detects the home position of the scanning carriage 1.

FIG. 2 is a control block diagram of the scanner according to the present embodiment. In FIG. 2, 9 is a control means, 10 is a lamp, 11 is a 3-line CCD, 12 is an image processing means, 1
Reference numeral 3 denotes an I / F (interface). The same elements as those in FIG. 1 are denoted by the same reference numerals. To explain the operation of this control block, the control means 9 starts the stepping motor 2 after the sensor 8 detects the scanning carriage 1 at the home position, and drives the stepping motor 2 at a timing corresponding to a predetermined set speed. A pulse is sent, and the scanning carriage 1 is caused to scan via a driving mechanism linked to the motor 2. When the scanning carriage 1 approaches the document reading position, the lamp 10 is turned on, and three lines C which are line-scanned at a predetermined timing are read.
The color original image is read by the CD 11. 3-line CCD
The image signal read at 11 is processed by the image processing means 12, and the processed image data is sent to an external image processing apparatus such as a copier, a printer, a facsimile, etc. through an I / F (interface).

In the present invention, as described above, the sub-scanning is performed by the scanner driving device, and the reading is performed by the main scanning of the three-line CCD 11 on the scanning carriage 1. The relative relationship between the main scanning and the sub-scanning at that time is as follows. It is assumed that the relationship represented by the following formula (1) or formula (2) is followed. W ≒ P × n ‥‥‥‥‥ Equation (1) where, W: width of one line of sub-scanning P: amount by which the scanning carriage 1 moves when the control means 9 sends one pulse (step) to the stepping motor 2 (Distance) n: an integer of 2 or more. The above expression (1) means the width W of one line in the sub-scanning direction.
Is the movement amount P of one step of the stepping motor by 2
, 3 times, and an integer multiple of 2 or more. Therefore, the CCD 11 scans once every n steps of the stepping motor, and
The operation of outputting the read image of the line is performed.

P {W × n} Equation (2) where, W: width of one line in the sub-scanning P: scanning carriage 1 moves when control means 9 sends one pulse (step) to stepping motor 2 Moving amount (distance) n: integer. The above equation (2) means that the stepping motor 2
Is set to be equal to a value obtained by multiplying the width W of one sub-scanning line by an integer. Therefore, while the stepping motor 2 moves by one step, the operation of scanning the CCD 11 n times and outputting a read image of n lines is performed.

In this embodiment, in addition to the conditions of the above equations (1) and (2), the moving amount P of the document sub-scanned by the stepping motor 2 via the driving mechanism is set to a target predetermined value. By selecting the stepping motor 2, the driving mechanism (the small gear 3, the large gear 4, and the pulley 5), and the setting condition of n in the above equation, the resolution is adjusted so that the resolution (basic resolution) can be obtained according to the moving amount. To make changes. Therefore, the above equations (1) and (2)
Examples 1 and 2 constructed in consideration of the condition given by the above and the matching condition to the basic resolution are shown below, and will be described in more detail.

<Embodiment 1> Here, the basic resolution is set to 40.
0 dpi. Therefore, the width of one line in the sub-scanning at 400 dpi is 0.0635 mm, and the left side W = 0.0635 of the equation (1) W ≒ P × n, and the right side P × n is set to 0.063.
5, the stepping motor 2, the small gear 3, the large gear 4, and the pulley 5 of the driving mechanism are set to n (having a divisor).
Design taking into account. -Step angle of the stepping motor: 0.72 °-Reduction ratio by gear: 3.96-Pitch circle diameter of the pulley: 10 mm-When n: 4 (having a divisor of 2, 1), P: The moving amount (distance) of one step of the stepping motor is P × n = 10 × π × 4 / (500 × 3.96) = 0.0
6347 That is, W (= 0.0635) ≒ P × n (= 0.06347) is satisfied, and the condition of Expression (1) is satisfied. When a reading operation is performed by the configuration of this embodiment, the control means 9 counts the number of motor drive pulses of the stepping motor 2, drives the three-line CCD 11 once every four pulses, and reads the image at 400 dpi. Can be read.

When the resolution is to be doubled, n: 2 and three lines CC at a rate of once every two pulses.
D11 is driven to read an image,
The image can be read with pi, and the sub-scanning magnification can be changed. In this way, if n = 4 and the basic resolution is set to 400 dpi, changing n = 1 to 1
The resolution becomes 600 dpi, and the resolution can be easily changed to a magnification (in this example, twice or four times) that takes an integer value corresponding to a divisor of n in the initial setting. In the case where the image data read as described above is subjected to the resolution decimation process at the reference resolution and a resolution that is an integral multiple of the reference resolution (that is, a simple numerical expression), for example, 400 dpi
In order to obtain a resolution of 387 dpi on the basis of, a process of thinning out one line for every 31 lines by a calculation of 400 / (400−387) ≒ 31 may be performed. According to this thinning-out processing, the calculation formula is simplified, the accuracy of the sub-scanning thinning-out processing at the intermediate resolution is improved, and the read image can be improved.

<Embodiment 2> Here, the basic resolution is 32
00 dpi. Accordingly, the width of one line of the sub-scanning at 3200 dpi is 0.0079375 mm, and the right side of the equation (2) P ≒ W × n W × n = 0.0079375 × n, and the right side P is made closer to 0.0079375 × n. The stepping motor 2, the small gear 3, the large gear 4, and the pulley 5 of the driving mechanism
Is designed taking into account n (integer). Step angle of stepping motor: 0.72 ° Reduction ratio by gear: 3.96 Pulley pitch circle diameter: 10 mm When n: 2, P: travel distance (distance) of one step of the stepping motor is P = 10 × π / (500 × 3.96) = 0.01587 That is, P (= 0.01587) ≒ W × n (= 0.0079937)
5 × 2 = 0.015875), which satisfies the condition of Expression (2). When the reading operation is performed by the configuration of this embodiment, the control means 9 determines the time interval between the motor driving pulses of the stepping motor 2 and
If the three-line CCD 11 is driven twice during the pulse and the image is read, the image can be read at 3200 dpi.

When the resolution is to be reduced to １ ／, the three-line CCD 11 is used once every one pulse.
1600 dpi by reading the image
To read an image, and enable sub-scanning magnification. As described above, if n = 2 and the basic resolution is set to 3200 dpi, by changing to n = 1, 160
0 dpi, and the resolution can be easily changed to 1 / n times the initial setting. Also, the reference resolution and 1 /
When the image data read in the above-described manner is subjected to the resolution thinning-out processing at a resolution of n times (that is, a simple numerical expression can be taken), for example, 3200
When trying to obtain a resolution of 3086 dpi based on dpi, 3200 / (3200-3086) ≒
By the calculation of 28, a process of thinning out one line every 28 lines may be performed. According to this thinning-out processing, the calculation formula is simplified, the accuracy of the sub-scanning thinning-out processing at the intermediate resolution is improved, and the read image can be improved.

[0017]

(1) According to the present invention, the width of one sub-scanning line is set to a value corresponding to the basic resolution, and the width of one step of the stepping motor is set when the basic resolution is set. By making the multiple n (integer) have a divisor and variably setting n, reading at the basic resolution and a resolution of an integral multiple thereof can be performed with high accuracy. Further, in the case of performing the decimation process of the determined resolution on the image data read as described above at the reference resolution and a resolution that is an integral multiple of the reference resolution (that is, a simple numerical expression), the calculation formula can be simplified. That is, it is possible to improve the accuracy of the sub-scanning (line) thinning-out process at the time of the intermediate resolution and improve the read image. (2) According to the present invention, the moving amount of one step of the stepping motor is made equal to an integer (n) times the width of one line in the sub-scanning, and n is variably set.
It is possible to accurately read a plurality of resolutions from the basic resolution to 1 / n times. Further, it is possible to improve the accuracy of the sub-scanning (line) thinning-out processing at the time of the intermediate resolution, and to improve the read image. (3) In the image processing apparatus provided with the scanner according to the present invention, reading at a plurality of resolutions can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a scanner driving device according to the present invention.

FIG. 2 is a block diagram showing a control circuit of the scanner of the present invention.

[Explanation of symbols]

1 scanning carriage, 2 stepping motor, 3 small gear, 4 large gear, 5 6 pulley, 7 belt
8. Sensor.

Claims (4)

[Claims] A line sensor for reading a document image, and a unit for scanning and inputting the document image to the line sensor;
A scanning carriage movably in the sub-scanning direction, and a scanning carriage driving device including a stepping motor and a transmission mechanism, wherein the scanning carriage and the line sensor are
W 次 P × n where W: width of one line in the sub-scanning, P: moving amount of the scanning carriage when the stepping motor is sent by one step,
n: an integer, and the scanning is performed once every n steps of the stepping motor.
In a scanner for outputting a read image signal for a line, n has a plurality of divisors, and a plurality of resolutions are read according to each of the divisors by setting the plurality of divisors. Scanner. 2. A scanning carriage comprising a line sensor for reading a document image, a means for scanning and inputting the document image to the line sensor, and movable in the sub-scanning direction, and a scanning carriage comprising a stepping motor and a transmission mechanism. The scanning carriage and the line sensor have the following formula: P ≒ W × n, where: W: width of one sub-scanning line, P: scanning carriage when the stepping motor is fed by one step. Amount of movement,
a plurality of values are set to n in a scanner configured to be driven in accordance with n: an integer and performing n-times scanning while the stepping motor performs one step and outputting a read image signal of n lines. A scanner that reads a plurality of resolutions corresponding to each value. 3. The scanner according to claim 1, wherein the output of the line sensor is thinned out at equal intervals. 4. An image processing apparatus comprising the scanner according to claim 1.