JP2001028668A - Scanner and image processing unit provided with the scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanner that can read an image with basic resolution and a resolution twice the basic resolution with high accuracy together with reading suitable for black/white or color image data, enhances the accuracy of subscanning for thinning processing in the case of intermediate resolution and improves the read image quality. SOLUTION: A width W for one line of subscanning in matching with a basic resolution of a black/white image is selected equally to a value being the 3n times (n: an integer) of a moving amount of one step of a stepping motor 2, and when the stepping motor is driven, a 3-line CCD 11 is driven at a rate once per 3n-step (3n mode) to read an image with the basic resolution. The CCD 11 is driven in the 1n mode to allow the CCD 11 to read the color image with the same resolution as that of the black/white image so that reading of the color image is switched into reading of the black/white image simply. The line interleaving at an equal interval is simplified on the basis of the basic resolution 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 an original in an image processing apparatus such as a copying machine or a facsimile using original image data. And a scanner capable of reading a color image.

[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.

When this method is carried out, a target resolution is set to a moving amount of N steps (N: an integer of 1 or more) of a scanning carriage (or a document) sub-scanned by a stepping motor via a driving mechanism. The stepping motor and the driving mechanism are designed so as to correspond to the movement amount obtained, and the main scanning of one line is performed at a period of N steps (for the number of steps for obtaining the target resolution) for driving the stepping motor. It has been proposed to read the intended resolution.

[0004]

However, according to the above-mentioned proposal, if the reading cycle of the main scanning is performed at a cycle of N steps, the reading of the target resolution can be performed. Although the reading accuracy is ensured, it is a solution to a further technical problem such as switching the sub-scanning resolution or performing resolution conversion on data after reading to obtain image data of different resolution. Absent. 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 provide a plurality of images in a resolution region of an integral multiple of the basic resolution, including performing reading suitable for monochrome or color image data. The present invention provides a scanner capable of accurately reading an image at a low resolution, improving the accuracy of sub-scanning thinning processing at an intermediate resolution, and improving the image quality of reading, and an image processing apparatus provided with the scanner. is there.

[0005]

According to a first aspect of the present invention, there is provided a scanning carriage loaded with a line sensor for reading a document image and means for scanning and inputting the document image to the line sensor, and being movable in the sub-scanning direction. And a scanning carriage driving device including a stepping motor and a transmission mechanism,
The scanning carriage and the line sensor are expressed by the following equation: W ≒ P × 2 × n, where W: width of one line of the sub-scan of the basic resolution, P: moving amount of the scanning carriage when the stepping motor is sent by one step. , N: an integer, and is set differently by performing one scan every 2n steps of the stepping motor and changing the setting and performing one scan every n steps. A scanner is characterized by outputting a one-line read image signal at a resolution.

According to a second aspect of the present invention, there is provided a line sensor for reading a document image, a scanning carriage loaded with a means for scanning and inputting the document 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 are expressed by the following equation: WB ≒ P × 3 × n, where WB: width of one line of sub-scanning at a basic resolution of a monochrome image,
P is configured to be driven according to the moving amount of the scanning carriage when the stepping motor is moved by one step, and n is an integer.
Scans and change the setting, 1 every 3n steps
By performing the scanning twice, one scan is performed at the set different resolution.
A scanner configured to output a line read image signal is configured.

According to a third aspect of the present invention, there is provided a line sensor for reading a document image, a scanning carriage loaded with a means for scanning and inputting the document 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 are expressed by the following formula: WB × P × 6 × n, where WB: width of one line of sub-scanning at the basic resolution of a monochrome image, P: The scanning carriage is configured to be driven in accordance with the moving amount of the scanning carriage when the stepping motor is fed by one step, n: an integer, performs one scan every 6n steps of the stepping motor, and changes the setting to 3n or By performing one scan every 2n or n steps, one line of read image signal is output at a set different resolution. Constitute the turbocharger Na.

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

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

[0010]

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. The operation of this control block will be described. The control unit 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. Is sent to the stepping motor 2, and the scanning carriage 1 is caused to travel along the document via a driving mechanism interlocked with the motor 2 to perform scanning. When the traveling scanning carriage 1 approaches the document reading position, the lamp 10 is turned on, and the color document image is read by the three-line CCD 11 that performs line scanning at a predetermined timing. 3 line CCD11
The image signal read by is processed by the image processing means 12, and the processed image data is sent to an external image processing apparatus such as a copying machine, a printer, a facsimile, etc. through an I / F (interface).

In the present invention, 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 as described above. Follows a relationship represented by the following formula (1), formula (2) or formula (3). W ≒ P × 2 × n ‥‥‥‥‥ Formula (1) where, W: width of one line of sub-scanning at the basic resolution P: scanning carriage when control means 9 sends one pulse (step) to stepping motor 2 The amount (distance) 1 moves n: integer. Equation (1) means that the sub-scan 1 at the basic resolution
Assuming that the line width W is a moving amount P of one step of the stepping motor, the line width W is set to be equal to twice, four times, six times ‥‥, and an integral multiple of two. Therefore, once every 2n steps of the stepping motor, C
When the operation of scanning the CD 11 and outputting a one-line read image is performed, reading at the basic resolution can be performed.

WB ≒ P × 3 × n ‥‥‥‥‥ Equation (2) where WB is the width of one line of sub-scanning at the basic resolution of the black and white image. P is one pulse (step) by the control means 9 to the stepping motor 2. The amount (distance) n the scanning carriage 1 moves when sent. N: integer. The meaning of the above equation (2) is that if the width WB of one line of the sub-scanning at the basic resolution of the black and white image is the moving amount P of one step of the stepping motor, it is three times, six times, nine times.
‥, and is to be equal to a value of an integer multiple of 3. Therefore, if the operation of scanning the CCD 11 once every 3n steps of the stepping motor and outputting a read image of one line is performed, the monochrome image basic resolution can be read.

WB {P × 6 × n} Equation (3) where WB is the width of one line of sub-scanning at the basic resolution of the black-and-white image. P: The control means 9 sends one pulse (step) to the stepping motor 2. The amount (distance) n the scanning carriage 1 moves when sent. N: integer. The meaning of the above equation (3) is that if the width WB of one line of sub-scanning at the basic resolution of a black and white image is the movement amount P of one step of the stepping motor, it is 6 times, 12 times, 18 times, and so on. That is, it should be equal to an integer multiple. Therefore, if the operation of scanning the CCD 11 once every 6n steps of the stepping motor and outputting the read image of one line is performed, the monochrome image basic resolution can be read.

In this embodiment, in addition to the conditions of the above-described 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. And the driving mechanism (small gear 3, large gear 4, pulley 5) and (2 × n), (3 × n) ), (6 × n) setting conditions are selected. Therefore, the above equation (1),
Embodiments 1, 2, and 3 configured in consideration of the conditions given by (2) and (3) and the matching conditions to the basic resolution
Is shown below and will be described in more detail.

<Embodiment 1> This embodiment is configured based on equation (1). Here, the basic resolution for reading a monochrome image is 600 dpi. Therefore, sub-scan 1 at 600 dpi
The width of the line is 0.04233 mm, and the left side of equation (1) W P × 2 × n W = 0.04233, and the right side P × 2 × n is set to 0.
The stepping motor 2, the small gear 3, the large gear 4, and the pulley 5 of the drive mechanism are designed in consideration of 2 × n so as to be close to 04233. -Step angle of the stepping motor: 0.72 °-Reduction ratio by gear: 8.9-Pitch circle diameter of the pulley: 10 mm-When n: 3, the moving amount (distance) of one step of the stepping motor: P The width of one line of sub-scanning derived from is: P × 2 × n = 10 × π × 2 × 3 / (500 × 3.96)
= 0.04236 That is, W (= 0.04233) ≒ P × 2 × n (= 0.0423)
6) and satisfies the condition of equation (1). 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 and calculates 2 × n
If the 3-line CCD 11 is driven once every 6 pulses, and the image is read, the image can be read at 600 dpi. In addition, when the resolution (sub-scanning magnification) is to be increased by a factor of two, and realized by changing the speed of the scanning carriage according to the resolution, WB ≒ P × n and n: 3. By driving the three-line CCD 11 once every three pulses and reading the image, the image can be read at 1200 dpi and the sub-scanning magnification can be changed. Thus, by setting the multiple 2 to 1, the resolution can be easily changed to twice the initial setting. In the case of performing the thinning process of the determined resolution on the image data read as described above at the basic resolution, for example, 574 based on 600 dpi
When trying to obtain a resolution of dpi, 600 / (6
00-574) By the calculation of ≒ 23, a process of thinning out one line every 23 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.

<Embodiment 2> This embodiment is configured based on the equation (2). Here, the basic resolution for reading a monochrome image is 600 dpi. Accordingly, the width of one line in the sub-scanning at the basic resolution of the monochrome image of 600 dpi: 0.04233 m
m, and the left side WB = 0.04233 of the equation (2) WB ≒ P × 3 × n, and the stepping motor 2 and the small gear 3 of the drive mechanism, large Gear 4 and pulley 5 are 3 ×
n is taken into account. Stepping motor step angle: 0.72 ° Gear reduction ratio: 8.9 Pulley pitch circle diameter: 10 mm If n: 2, the movement amount (distance) of one step of the stepping motor: P Black and white image basic resolution 600 derived from
The width of one sub-scan line at dpi is P × 3 × n = 10 × π × 3 × 2 / (500 × 3.96)
= 0.04236 That is, WB (= 0.04233) ≒ P × 3 × n (= 0.042
36), which satisfies the condition of Expression (2). 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 and calculates 3 × n
If the 3-line CCD 11 is driven once every 6 pulses, and the image is read, the image can be read at a monochrome image basic resolution of 600 dpi.

Here, when reading a color image at a color image reading basic resolution of 600 dpi, the linear velocity of the scanning carriage 1 at the color image reading basic resolution of 600 dpi is set to keep the light quantity constant for a color image.
Since the linear speed of the scanning carriage at the basic resolution of 600 dpi for reading a black-and-white image needs to be 1/3, the reading operation corresponding to this is performed. Therefore, by changing the speed of the scanning carriage to 1/3, the width of one line of the sub-scanning at the basic resolution of the color image of 600 dpi: WC = 0.0
Since 4233 × ＝= 0.01411 mm, an operation based on WC ≒ P × n is performed. Black and white image basic resolution 600dpi
The width of one line in the sub-scanning at the time is: P × n = 10 × π × 2 / (500 × 3.96) = 0.0
1412 That is, WC (= 0.01411) ≒ P × n (= 0.0141)
2) and satisfies the condition of the above equation. When the reading operation is performed by the configuration of this embodiment, by setting the multiple 3 to 1, the WC becomes an integer (n) times of P, and the motor drive pulse of the stepping motor 2 is counted, and once every n: 2 pulses By driving the three-line CCD 11 at a rate of 1 and reading the image, the image can be read at the color image basic resolution of 600 dpi, and the accuracy of the sub-scanning thinning process at the color intermediate resolution is improved to improve the read image. be able to.

<Embodiment 3> This embodiment is configured based on equation (3). Here, the basic resolution for reading a monochrome image is 600 dpi. Accordingly, the width of one line in the sub-scanning at the basic resolution of the monochrome image of 600 dpi: 0.04233 m
m, so that the left side WB = 0.04233 of the equation (3) WB ≒ P × 6 × n and the right side P × 6 × n approaches 0.04233, so that the stepping motor 2 and the small gear 3 of the driving mechanism Gear 4 and pulley 5 are 6 ×
n is taken into account. Stepping motor step angle: 0.72 ° Gear reduction ratio: 8.9 Pulley pitch circle diameter: 10 mm If n: 1, the amount of movement (distance) of one step of the stepping motor: P Black and white image basic resolution 600 derived from
The width of one sub-scanning line at dpi is: P × 6 × n = 10 × π × 6 / (500 × 3.96) =
0.04236 That is, WB (= 0.04233) ≒ P × 6 × n (= 0.042
36), which satisfies the condition of Expression (3). 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 and calculates 6 × n
If the 3-line CCD 11 is driven once every 6 pulses, and the image is read, the image can be read at a monochrome image basic resolution of 600 dpi.

When a color image is read at a basic color image reading resolution of 600 dpi, the linear velocity of the scanning carriage 1 at the basic color image reading resolution of 600 dpi is set in order to keep the light quantity constant for a color image.
Since the linear speed of the scanning carriage at the basic resolution of 600 dpi for reading a black-and-white image needs to be 1/3, the reading operation corresponding to this is performed. Therefore, by changing the speed of the scanning carriage to 1/3, the width of one line of the sub-scanning at the basic resolution of the color image of 600 dpi: WC = 0.0
Since 4233 × １ ／ = 0.01411 mm, an operation based on WC ≒ P × 2 × n is performed. Black and white image basic resolution 600dpi
The width of one line in the sub-scanning at the time is P × 2 × n = 10 × π × 2 / (500 × 3.96) =
0.01412 In other words, WC (= 0.01411) ≒ P × 2 × n (= 0.014
12) and satisfies the condition of the above equation. When the reading operation is performed by the configuration of this embodiment, by setting the multiple 6 to 2, the WC becomes an integer (2 × n) times of P, the motor drive pulse of the stepping motor 2 is counted, and once every two pulses. By driving the three-line CCD 11 at a rate of 1 and reading the image, the image can be read at the color image basic resolution of 600 dpi, and the accuracy of the sub-scanning thinning process at the color intermediate resolution is improved to improve the read image. be able to.

Further, the basic resolution for reading a black and white image is 1
A setting example when changing to 200 dpi is shown. Regarding the width of one line of sub-scanning at the basic resolution of 1200 dpi of black and white image (theoretical value: WB1200 = 0.02117 mm),
An operation based on WB ≒ P × 3 × n is performed by setting a multiple 6 of Expression (3) to 3. B & W image basic resolution 1200dp
The width of one line in the sub-scanning at the time of i is P × 3 × n = 10 × π × 3 / (500 × 3.96) =
0.02118 In other words, WB1200 (= 0.02117) ≒ P × 3 × n (=
0.02118), which satisfies the condition of the above equation. When changing the color image reading basic resolution to 1200 dpi, the multiple 6 of the equation (3) is set to 1 for the width (theoretical value: WC1200 = 0.0070556 mm) of one sub-scanning line at the color image basic resolution of 1200 dpi. The operation based on WB ≒ P × n is performed. Color image basic resolution 1200
The width of one sub-scanning line at dpi is P × n = 10 × π × 1 / (500 × 3.96) = 0.0
070598 In other words, WC1200 (= 0.0070556) ≒ P × n (=
0.0070598), which satisfies the condition of the above equation. As described above, according to the third embodiment, WC is an integral multiple of P, so that the accuracy of the sub-scanning thinning process at the color intermediate resolution can be improved, and the read image can be improved. Further, both the black and white image and the color image can set the reference resolution to 1200 dpi, so that they can be read with high accuracy.

[0021]

(1) According to the present invention, the scanning carriage is controlled so that the value of 2n (n: integer) times the moving amount of one step of the stepping motor is equal to the width of one line of the sub-scanning at the basic resolution. By changing the setting of the 2n-times mode for driving the sub-scanning and the main scanning of the line sensor to the 1n-times mode, it is possible to accurately read the basic resolution and twice the resolution. Further, since the accuracy of the sub-scanning (line) thinning process at the time of the intermediate resolution is improved, it is possible to improve the read image up to a resolution area twice the basic resolution including the intermediate resolution. (2) According to the present invention, the sub-scanning of the scanning carriage and the sub-scanning of the scanning carriage are performed so that the value of 3n (n: integer) times the moving amount of one step of the stepping motor is equal to the width of one sub-scanning line of the basic resolution of the black and white image. By changing the setting of the 3n mode for driving the main scanning of the line sensor to the 1n mode, it is possible to accurately read the color image basic resolution having the same resolution as the monochrome image basic resolution. In addition, since the accuracy of the sub-scanning (line) thinning process at the time of the intermediate resolution is improved, the read image including the color image can be improved. (3) According to the present invention, the sub-scanning of the scanning carriage and the sub-scanning of the scanning carriage are performed so that the value of 6n (n: an integer) times the moving amount of one step of the stepping motor is equal to the width of one sub-scanning line of the basic resolution of the monochrome image. By changing the setting of the 6n magnification mode for driving the main scanning of the line sensor to the 2n magnification mode, it is possible to accurately read the color image basic resolution having the same resolution as the black and white image basic resolution. By changing the setting to the double mode, it is possible to accurately read the resolution of twice the basic resolution with respect to the black-and-white image. Further, by changing the setting to the 1n mode, the reading of the double resolution is performed. A color image can be read with high accuracy. In addition, since the accuracy of the sub-scanning (line) thinning process at the time of the intermediate resolution is improved, it is possible to read an image including a color image with high accuracy. (4) 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 (5)

[Claims] 1. A scanning carriage loaded with a line sensor for reading a document image, a unit for scanning and inputting the document image to the line sensor and movable in the sub-scanning direction, and a scanning carriage including a stepping motor and a transmission mechanism. The scanning carriage and the line sensor have the following formula: W ≒ P × 2 × n, where W: width of one line of sub-scanning at the basic resolution, and P: one step of the stepping motor. The scanning carriage is driven in accordance with the amount of movement of the scanning carriage, n: an integer, and performs one scan every 2n steps of the stepping motor, and changes the setting to perform one scan every n steps. A scanner that outputs a one-line read image signal at different set resolutions. 2. A scanning carriage loaded with 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: WB ≒ P × 3 × n, where WB: width of one line of sub-scanning at a basic resolution of a monochrome image, P: one step of a stepping motor The scanning carriage is configured to be driven in accordance with the moving amount of the scanning carriage at the time of sending, n: an integer. The scanning is performed once every 3n steps of the stepping motor, and the setting is changed, and the scanning is performed once every n steps. A scanner which outputs one line of a read image signal at a set different resolution by performing scanning. 3. A scanning carriage comprising a line sensor for reading a document image, means for scanning and inputting the document image to the line sensor, the scanning carriage being 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: WB ≒ P × 6 × n, where WB: width of one line of sub-scanning at a basic resolution of a monochrome image, P: one step of a stepping motor The scanning carriage is configured to be driven in accordance with the moving amount of the scanning carriage at the time of sending, n: an integer. The scanning is performed once every 6n steps of the stepping motor, and the setting is changed to change every 3n, 2n, or n steps. A scanner that outputs a one-line read image signal at a set different resolution by performing one scan. 4. The scanner according to claim 1, wherein the output of the line sensor is thinned out at equal intervals. 5. An image processing apparatus comprising the scanner according to claim 1.