JP2002135543A - Image read controller, image reader, image read control method, image read method, storage medium and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive image reader that can express high gradation without bringing a sensor to an optical saturation state. SOLUTION: A line sensor 104 receiving a one-line read pulse captures image information of an original face as image data for a time t2 from a preceding read pulse until a read pulse this time. The captured image data are fed to an image controller 107 by each line, where image processing is conducted. The time t2 is shorter than a time t1. The original read position does not coincide with the image data by a difference between one line movement time and a one-line image read time of the line sensor 104, and as shown in Figure 5, lines where read images are in duplicate are aborted and thinned out to obtain an output image (image data).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, an image reading control device using a line sensor, an image reading device, an image reading control method, an image reading method, a storage medium, and a program.

[0002]

2. Description of the Related Art Conventionally, in order to prevent the CCD from becoming saturated when the amount of received light signal is large, an electronic shutter is used so that the CCD is not saturated at the maximum light source light amount, and an electric shutter is used. The accumulation time was variable.

[0003]

However, when a sensor having an electronic shutter is used, there is a problem that the cost of the product is increased because the sensor is expensive.

Accordingly, the present invention provides an image reading control device, an image reading device, an image reading control method, an image reading method, and an inexpensive high-gradation expression without causing a sensor to be in a light-saturated state.
It is intended to provide a storage medium and a program.

[0005]

In order to achieve the above object, an image reading control device according to the present invention is arranged such that the image reading means reads the subject image in units of lines, and the image reading control device controls the image signal according to the level of the image signal. The image processing apparatus further includes a control unit that causes the image reading unit to read the subject image asynchronously with displacement of a relative position between the image reading unit and the subject image.

Further, the image reading apparatus of the present invention comprises: an image reading means for reading an image in a main scanning direction; a moving means for moving an image reading position by the image reading means in a sub-scanning direction; A control unit for causing the image reading unit to read the image asynchronously with the movement of the moving unit in accordance with the brightness of the read image.

Further, according to the image reading control method of the present invention, a relative position between the image reading means and the subject image is determined in accordance with a level of an image signal obtained by reading the subject image in line units by the image reading means. A control step of causing the image reading means to read the subject image asynchronously with the displacement of the position.

Further, the present invention provides a storage medium for holding a program code for implementing the image reading control method,
And a program having the program code.

Further, according to the image reading method of the present invention, the image reading method is controlled so that the image of the original is read in the main scanning direction while moving the image reading position in the sub-scanning direction. And controlling to read the image asynchronously with the moving speed.

Further, the present invention is characterized by a storage medium holding a program code for realizing the above-described image reading method, and a program having the program code.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading control device, an image reading device, an image reading control method, an image reading method, a storage medium and a program according to the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a diagram schematically showing a configuration of an image reading apparatus according to a first embodiment. FIG. 2 is a block diagram illustrating an electrical configuration of the image reading apparatus. In the figure, reference numeral 102 denotes a flatbed type image scanner unit. Reference numeral 101 denotes an automatic document feeder (ADF).

Reference numeral 104 denotes a lamp 204, a mirror, a lens,
The CCD 207 is an integrated line sensor that reads an image of the document in the main scanning direction. Note that the CCD 207 may be a color sensor or a monochrome sensor. The lamp 204 is a rod-shaped light source such as a xenon lamp or a cold cathode tube.

Reference numeral 105 denotes a document set tray. 106
Denotes a document discharge tray. 107 is a line sensor 104
Is an image controller that performs A / D conversion on the image signal and performs image processing. Reference numeral 108 denotes a document feed roller. Reference numeral 109 denotes a white reference plate provided inside the flat bed so that the line sensor 104 can read the reference. 103
Denotes a transport control unit.

The ADF 101 is openable and closable from the flatbed type image scanner unit 102.
By opening 1, a glass platen appears on the upper surface of the flatbed type image scanner unit 102. By placing a document on this platen, it is possible to operate as a flatbed type image scanner.

When operated as a flatbed type scanner, the line sensor drive motor 202 conveys the line sensor 104 in the sub-scanning direction in accordance with an instruction from the conveyance control unit 103, and reads an image of the entire surface of a stationary original. At that time, the transport control unit 103 controls the lamp inverter 205 to turn on the lamp 204. The lamp inverter 205 can maintain the light amount of the lamp 204 constant by a control signal.

On the other hand, when reading a document using the ADF 101, the conveyance control unit 103 controls the motor drive circuit 203 to rotate the ADF drive motor 201, and the document feed roller 108 rotates. ADF drive motor 20
Reference numeral 1 denotes an image read by the line sensor 104 while bringing the original set on the original set tray 105 to the position of the line sensor 104 and conveying the original in the sub-scanning direction. The read image is transferred by the image controller 107 to the personal computer 210 or a printer (not shown) as image data.

FIG. 3 is a flowchart showing a reading mode determination processing procedure at the start of image reading. This processing program is stored in a ROM (not shown) in the image controller 107 and the transport control unit 103, respectively, and is executed by each CPU (not shown). First,
The transport control unit 103 sets the line sensor 104 to the white reference plate 10
9 (step S21), and an image serving as a white reference is read (step S22). The analog signal image read by the CCD 207 is converted into a digital image by the A / D converter 208 and sent to the image controller 107.

The image controller 107 determines whether or not there is a white image exceeding a specified value among all the pixels of the white reference image (step S23). The mode is set to "thinning-out reading mode" (step 24). On the other hand, when there is no white image exceeding the specified value, the “normal reading mode” is set.

Here, the specified value is set as a value smaller than the value at which the CCD 207 is saturated. A white image having a large amount of received light exceeding the prescribed value is a state in which the CCD 207 is saturated. Therefore, in order to avoid this saturation state, the reading mode is determined so that the charge signal generated in accordance with the received light amount of the white reference plate image can be read without saturation in all the images. When the “normal reading mode” is determined, the image is read at the timing shown in FIG.

FIG. 4 is a timing chart showing the relationship between motor drive and read image data in the "normal reading mode". In the figure, when the line sensor movement amount of the line sensor drive motor 202 by the conveyance control unit 103 is time t1 per line, the image controller 107 sends the line sensor 104 once per line sensor movement amount, ie, once. A one-line reading pulse is issued every time t1.

The line sensor 104 to which the one-line reading pulse is applied captures image information of the document surface as image data during a time t1 from the previous reading pulse to the current reading pulse. The captured image data is sent to the image controller 107 line by line via the A / D converter 208, and image processing is performed. on the other hand,
When the “thinning-out reading mode” is determined, the image is read at the timing of FIG.

FIG. 5 is a timing chart showing the relationship between motor drive and read image data in the "thinning-out reading mode". In the figure, the line sensor movement amount of the line sensor drive motor 202 by the transfer control unit 103 is set to time t1 for one line, and the image controller 107 instructs the line sensor 104 to change the line sensor movement amount by 1 every time t2 asynchronously with the line sensor movement amount. Issues a line read pulse.

The line sensor 104 to which the one-line reading pulse is applied captures image information of the document surface as image data during a time t2 from the previous reading pulse to the current reading pulse. The captured image data is sent to the image controller 107 line by line, and image processing is performed. Here, time t2 is shorter than time t1. Because the one line moving time of the line sensor 104 and the one line image reading time are different, the reading position of the document and the image data do not match. However, as shown in FIG. 5, the lines where the read images overlap are discarded as discarded images. Output image (image data). In other words, by invalidating the image signal of the predetermined line, only the reading speed can be increased, and the charge accumulation time by the light receiving unit 207 can be shortened. Therefore, when reading at time t1, the CCD 207 may be saturated, but when reading at time t2, the saturation of the CCD 207 does not occur. FIG. 5 shows an example in which an image for one line is discarded after an image for three lines is read.

[Second Embodiment] The configuration of an image reading apparatus according to a second embodiment is the same as that of the first embodiment, and therefore, only components different from those of the first embodiment will be described here. I do. The transport controller 103 can set the speed of the line sensor drive motor 202 to a high speed, and the image controller 107 can change the image reading time.

FIG. 6 is a flowchart showing a reading mode determination processing procedure at the start of image reading. This processing program is stored in a ROM (not shown) in the image controller 107 and the transport control unit 103, respectively, and is executed by each CPU (not shown). First,
The transport control unit 103 sets the line sensor 104 to the white reference plate 10
9 (step S11), and an image serving as a white reference is read (step S12).

The analog signal image read by the CCD 207 is converted into a digital image by the A / D converter 208 and sent to the image controller 107. Image controller 1
At 07, it is determined whether or not there is a white image exceeding a specified value among all the pixels of the white reference image (step S13). If there is a white image exceeding the specified value, the reading mode is set to the “high-speed reading mode”. The setting is performed (step S14), and the process ends. On the other hand, when there is no white image exceeding the specified value, the mode is set to the “normal reading mode” (step S15), and the process is terminated.

Here, the specified value is a value smaller than the maximum value of the white output of the CCD 207. The white image exceeding the specified value is a state in which the exposure amount of the CCD 207 is saturated. Therefore, the reading mode is determined so that all the pixels can read the white reference plate without saturation.

The reading mode is "normal reading mode"
7 is read at the timing of FIG. 4 described above, and when the “high-speed reading mode” is determined,
Read the image at the timing of. FIG. 7 is a timing chart showing the relationship between motor drive and read image data in the “high-speed read mode”.

In the figure, the amount of movement of the line sensor drive motor 202 by the line controller drive motor 202 by the transfer controller 103 is set to time t2 for one line, and the image controller 107 moves the line sensor 104 relative to the line sensor 104 so as to synchronize with this. Once per volume, ie time t
A one-line read pulse is issued every two. The line sensor 104 to which the one-line reading pulse is given takes a time t2 from the previous reading pulse to the current reading pulse.
During this time, the image information of the document surface is captured as image data.

The fetched image data is sent to the image controller 107 line by line, and image processing is performed.
Here, time t2 is shorter than time t1. As a result, the reading time of one line is shortened, and the CCD 2
07 becomes shorter. Therefore, time t1
When reading at time t1, the CCD 207 may be saturated, whereas reading at time t2 prevents saturation of the CCD 207.

[Third Embodiment] The configuration of an image reading apparatus according to a third embodiment is the same as that of the first embodiment.

FIG. 8 is a flow chart showing the light intensity change control processing procedure at the start of image reading. This processing program includes the image controller 107 and the transport control unit 103
Are respectively stored in a ROM (not shown) inside and are executed by each CPU (not shown). First, the transport control unit 103 moves the line sensor 104 directly below the white reference plate 109 (step S1), turns on the lamp 204 with the maximum amount of light (step S2), and reads an image serving as a white reference (white reference image). (Step S3).

The analog image signal read by the light receiving unit 207 is converted into a digital image by the A / D converter 208.
It is sent to the image controller 107. The image controller 107 determines whether there is a white image exceeding a specified value among all the pixels of the white reference image (step S4). If there is a white image exceeding the specified value, the light amount of the lamp 204 is reduced (step S4). Step S5), the process returns to step S3, and the white reference image is read again. This process is repeated, and when there is no white image exceeding the specified value, the present process is terminated.

Thereafter, the lamp 204 set in the above process is set.
The original is read using the amount of light. Here, the specified value is
This value is smaller than the value at which the CCD 207 saturates. The white image exceeding the specified value is a state where the CCD 207 is saturated. Therefore, the CCD 207 is used for all the pixels.
Is determined so that a signal due to light reception of the white reference plate image can be read without saturation. For example, assuming that the maximum value of the white output of the CCD 207 is 1.0 V, and the output beyond that is a range where the light-voltage conversion characteristics of the sensor cannot be guaranteed, the default value is set to 0.9 V with a margin of 0.1 V. . Here, when the signal output of the CCD 207 is 1.1 V, the light amount of the light source is reduced. Here, the light source can reduce the light amount in 5% units. As a guide for reducing the light amount, from 0.9V ÷ 1.1V = 0.82, the light source light amount is set to 80% (4 steps lower). The white image is read again and it is checked whether the value exceeds the default value of 0.9V. The reason why this reduction value is a standard is that it is not guaranteed whether or not the preceding 1.1 V is a voltage reflecting the light amount. If the output of the light receiving unit 207 exceeds the predetermined value as a result of the reconfirmation, the white image is read by setting the output to 75% (one step lower). In this way, it is possible to obtain a signal full of the predetermined value. By adjusting the light source light amount in this manner, individual differences between the devices can be absorbed, the signal amplitude can be maximized until just before saturation, and the image quality can be improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of these embodiments, and the functions described in the claims or the functions of the embodiments are described. Any configuration that can achieve the function of the configuration is applicable.

For example, in the above-described embodiment, the case where the line sensor 104 is transported in the sub-scanning direction to read the image of the original is shown. However, the line sensor 104 is fixed, and the original is transported by the automatic original feeder. It may be applied when reading the image. Further, the present invention is also applicable to a case in which an optical path for guiding reflected light from a document to a line sensor can be changed in the sub-scanning direction and the reading position in the sub-scanning direction is sequentially changed.

The image reading mechanism for determining the light amount may be performed by either the flatbed type image scanner unit 102 or the ADF 101.

In the above embodiment, the CCD is described. However, the present invention is not limited to this, and a MOS structure may be used.

Further, the means for reducing the light amount of the light source in the first embodiment is combined with the means for increasing the reading timing so as to synchronize with the movement of the line sensor in the second embodiment. Is also possible. Similarly, it is also possible to combine the means for reducing the light amount of the light source in the first embodiment with the means for speeding up the reading timing asynchronously with the movement of the line sensor and thinning out the read image.

The present invention can also be applied to a case where a recording medium storing software program codes for realizing the functions of the above-described embodiments is mounted on an image reading apparatus, and the program is supplied to achieve this. Needless to say. In this case, the program code itself read from the storage medium implements the novel function of the present invention, and the storage medium storing the program constitutes the present invention.

In the above embodiment, the program codes shown in the flowcharts of FIGS. 3, 6, and 8 are stored in the ROM serving as a storage medium. The storage medium for supplying the program code is not limited to the ROM, and may be a floppy (registered trademark) disk, a hard disk, a CD-RO, for example.
M, CD-R, DVD, magnetic tape, nonvolatile memory card, and the like can be used.

[0043]

According to the present invention, light saturation of the sensor can be prevented without using an expensive CCD with an electronic shutter, and the difference in signal amplitude between a white image and a black image can be increased. Therefore, it is possible to provide an inexpensive image reading device capable of expressing a high gradation without causing the sensor to be in a light saturated state.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of an image reading device according to a first embodiment.

FIG. 2 is a block diagram illustrating an electrical configuration of the image reading apparatus.

FIG. 3 is a flowchart illustrating a reading mode determination processing procedure at the start of image reading.

FIG. 4 is a timing chart showing a relationship between motor driving and read image data in a “normal reading mode”.

FIG. 5 is a timing chart illustrating a relationship between motor drive and read image data in a “thinning-out reading mode”.

FIG. 6 is a flowchart illustrating a light amount change control processing procedure at the start of image reading.

FIG. 7 is a timing chart showing a relationship between motor drive and read image data in a “high-speed read mode”.

FIG. 8 is a flowchart illustrating a reading mode determination processing procedure at the start of image reading.

[Explanation of symbols]

 102 Image Scanner Unit 103 Transport Control Unit 107 Image Controller 202 Line Sensor Driving Motor 204 Lamp 205 Lamp Inverter 207 CCD

Claims (16)

[Claims] 1. The image reading device according to claim 1, wherein said image reading unit is configured to read the subject image in a line unit and read the image asynchronously with displacement of a relative position between the image reading unit and the subject image. An image reading control device, comprising: a control unit that causes the unit to read the subject image. 2. The apparatus according to claim 1, wherein said control means performs predetermined image processing on said image signal so as to correspond to a relative position between said image reading means and said subject image. The image reading control device according to any one of the preceding claims. 3. The apparatus according to claim 2, wherein the predetermined image processing is processing for invalidating an image signal of a predetermined line. 4. The image reading apparatus according to claim 1, wherein the control unit executes the control when a level of an image signal read by the image reading unit exceeds a predetermined value. Control device. 5. An image reading means for reading an image in a main scanning direction, a moving means for moving an image reading position by the image reading means in a sub-scanning direction, and according to brightness of the image read by the image reading means. hand,
An image reading device comprising: a control unit that causes the image reading unit to read an image asynchronously with the movement by the moving unit. 6. The image reading apparatus according to claim 5, wherein the control unit thins out the read image so as to make the resolution of the read image uniform. 7. The image reading device according to claim 1, wherein said image reading unit reads the image of the subject in a line unit and asynchronously reads the image in synchronization with a displacement of a relative position between the image reading unit and the subject image. An image reading control method, comprising a control step of causing a unit to read the subject image. 8. The apparatus according to claim 7, wherein in the control step, predetermined image processing is performed on the image signal so as to correspond to a relative position between the image reading means and the subject image. The image reading control method described in the above. 9. The image reading control method according to claim 8, wherein the image processing is processing for invalidating an image signal of a predetermined line. 10. The control step, wherein the control is executed when the level of an image signal read by the image reading means exceeds a predetermined value.
10. The image reading control method according to any one of claims 9 to 9. 11. A storage medium storing a program code for implementing the image reading control method according to claim 7. Description: 12. A program having a program code for implementing the image reading control method according to claim 7. Description: 13. An image reading method for controlling an image of a document to be read in a main scanning direction while moving an image reading position in a sub-scanning direction, wherein the image reading method is asynchronous with the moving speed according to the brightness of the read image. And controlling the image to be read. 14. The image reading method according to claim 13, further comprising, in the controlling step, thinning out the read image so as to make the resolution of the read image uniform. 15. A storage medium storing a program code for realizing the image reading method according to claim 13. 16. A program having a program code for realizing the image reading method according to claim 13. Description: