JP2001127957A - Image reader and method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which can obtain read images of high quality, even if its image read operation is stopped temporarily. SOLUTION: When image read operation must be stopped temporarily, it is decided whether the current original feeding speed PMT is higher than a prescribed speed ΔPMT0. When the former speed is higher than latter one, it is decided that the speed PMT must be slowed down, and an original scanning speed setting part reads the slow-down data. A motor and a sensor drive circuit are controlled according to the slow-down data. The slow-down processing gradually slows down the motor speed and the image reading speed at time interval of t0' to t0. Thus, an original can be stopped gently at its positions Y0" to Y0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image scanner, a facsimile apparatus equipped with the image scanner, an image reading apparatus such as a multifunction printer, a method, and a storage medium.

[0002]

2. Description of the Related Art Conventionally, when an image scanner reads an image at a predetermined speed, depending on a data transfer rate, an image processing speed, and a memory capacity, the image reading operation is temporarily stopped to reduce the data transfer rate and the memory capacity. I was adjusting.

FIG. 13 is a diagram showing a configuration of a conventional image scanner. In the figure, reference numeral 310 denotes a light source for document illumination. 305 is a light source drive circuit. 306 is an amplifier circuit. Reference numeral 311 denotes a platen glass. Reference numeral 307 denotes a document to be read.

[0004] Reference numeral 308 denotes a rod lens array for condensing light reflected from a document. Reference numeral 309 denotes a photodiode array (photodiode) as an electro-optical element that converts an optical signal into an electric signal. Reference numeral 312 denotes a transport roller for transporting the original. 304 is a motor drive circuit. Three
Reference numeral 03 denotes a CPU in a control unit that controls the image reading device.

A CPU 303 communicates with a host computer (not shown), controls a motor drive circuit 304 based on an image reading start signal, drives a transport roller 312, and transports an original 307. Light source 310 for document illumination
When light is applied to the original 307 from the light source, the reflected light is transmitted to the photodiode 309 by the rod lens array 308.
Is collected.

[0006] The photodiode 309 converts the reflected light from the original into an electric signal, sends the converted electric signal to the amplifier circuit 306, and then transfers the electric signal to the CPU 303. Then, the CPU 303 transfers the image data subjected to the image processing to a host computer (not shown).

FIG. 14 is a timing chart showing a change over time in the document conveying speed and the document position. In the figure, the horizontal axis 403 indicates time, the vertical axis 401 indicates the document transport speed, and the vertical axis 402 indicates the document position. As shown in the figure, the document is conveyed and the image reading operation is performed at the document conveying speed (document reading speed) V0, and the operation is temporarily stopped from time t0 to time t1 to temporarily suspend the document reading operation. After that, the reading operation is started again.

[0008]

However, in the above-described conventional image reading apparatus, when the motor is stopped at time t0, the original 307 exceeds the stop target position Y0 and the position Y0 '.
Sometimes went too far. This is due to backlash of gears between the motor and the rollers, inertia, and the like.

As a result, a shift of Y0'-Y0 occurs in the read image, and this shift is accumulated each time the pause operation is repeated, resulting in image shrinkage or generation of unreadable lines. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus, method, and storage medium that can obtain a high-quality read image even when the image reading operation is temporarily stopped during the image reading operation.

[0011]

To achieve the above object, an image reading apparatus according to a first aspect of the present invention comprises a photoelectric conversion means for converting light from a document into an electric signal, and the photoelectric conversion means. And a document scanning means for relatively scanning the document, wherein the document scanning means changes the scanning speed when changing from the first document scanning state to the second document scanning state. When the difference is equal to or more than a predetermined value, the setting of the scanning speed is changed with time.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, when the document scanning unit suspends the image reading operation, the setting of the scanning speed is reduced with time. It is characterized by.

According to a third aspect of the present invention, in the image reading apparatus according to the first aspect, when the document scanning means resumes the image reading operation from a temporarily stopped state, the setting of the scanning speed is time-dependent. It is characterized in that it increases along with.

According to a fourth aspect of the present invention, in the image reading apparatus according to the first aspect, the original scanning means conveys the original to the fixed photoelectric conversion means, thereby causing the original to be conveyed. Is scanned.

According to a fifth aspect of the present invention, in the image reading apparatus according to the first aspect, the original scanning unit moves the photoelectric conversion unit with respect to the fixed original so that the original is scanned. Is scanned.

According to a sixth aspect of the present invention, in the image reading apparatus of the first aspect, the operation timing of the photoelectric conversion means is set according to a scanning speed set during an image reading operation. Features.

According to a seventh aspect of the present invention, there is provided the image reading apparatus according to the sixth aspect, further comprising an image signal transfer unit for sequentially transferring the electric signals converted by the photoelectric conversion unit, wherein the set scanning is performed. The transfer timing of the electric signal is set according to the speed.

According to an eighth aspect of the present invention, there is provided the image reading apparatus according to the sixth aspect, further comprising a storage unit having a storage capacity for at least image data corresponding to the set scanning speed. And

According to a ninth aspect of the present invention, in the image reading apparatus according to the sixth aspect, an illuminating means for illuminating the original and an amount of light illuminated on the original by the illuminating means are set to the set value. Light amount adjusting means for adjusting according to the scanning speed.

According to a tenth aspect of the present invention, in the image reading apparatus according to the ninth aspect, when the scanning of the original is stopped, the image reading operation is performed by turning on the illumination means for a predetermined time and stopped. Is performed.

An image reading method according to claim 11, wherein the image of the document is read by relatively scanning the document with respect to a photoelectric sensor for converting light from the document into an electric signal. And a step of changing the setting of the scanning speed with time when the difference between the scanning speeds is equal to or more than a predetermined value when changing from the first original scanning state to the second original scanning state.

According to a twelfth aspect of the present invention, the storage medium is executed by a computer that controls an image reading device that reads an image of a document, and stores the document relative to a photoelectric sensor that converts light from the document into an electric signal. In a storage medium storing a scanning program, when the scanning speed difference is equal to or greater than a predetermined value when changing from the first document scanning state to the second document scanning state, It is characterized by including a procedure of changing the setting with time.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the image reading apparatus, method and storage medium of the present invention will be described.

[First Embodiment] FIG. 1 is a diagram showing a configuration of an image reading apparatus according to a first embodiment. In the figure, reference numeral 101 denotes an image reading device. 116 is a host computer. 121 is an image reading unit. Some image reading units include a reduction optical system using a CCD, and others include a contact image sensor.
In the present embodiment, a contact image sensor (CIS: Co
ntact Image Scanner) is used. An image reading unit (CIS) 121 includes a light source 103 for illuminating a document represented by an LED, a halogen lamp, a cold-cathode tube, and the like, a platen glass 104, and a condenser lens array 1.
19 and a photoelectric conversion element 116.

Reference numeral 107 denotes a document to be read. Reference numeral 106 denotes a document feed roller, and reference numeral 109 denotes a pad that cooperates with the document feed roller 106 to separate the document 107 by friction. Reference numerals 105, 108, 102, and 118 denote rollers for document conveyance, and these rollers are driven by a motor 110.

Reference numeral 113 denotes a memory for storing data for black and white correction, image data for several pages, and the like. A document presence detection sensor 111 detects the presence or absence of a document. 114
Is a leading edge detection sensor for detecting the leading edge of the document.

Reference numeral 120 denotes a control unit which controls image reading operation, image processing, communication processing, and the like. A timing generator 126 generates a drive clock for the motor 110, a start signal for the CIS 121, and the like. An original scanning speed setting unit 112 sets the original conveying speed (original scanning speed). When changing the transport speed of the document, if the difference between the current transport speed and the transport speed to be changed is larger than a predetermined value, the original scanning speed setting unit 112 determines the appropriate transport speed from predetermined data as described later. Set to. An image processing unit 117 processes image data. Reference numeral 122 denotes a data transfer / communication unit that performs data communication with the host computer 116. 116 is a host computer.

Reference numeral 123 denotes a light amount adjusting circuit for adjusting the light amount of the document illuminating light source 103. Reference numeral 124 denotes a CIS drive circuit that sets the image reading timing of the photodiode array of the CIS 121, the data transfer timing, and the like according to the timing from the timing generation unit 126. The CIS drive circuit 124 includes an amplifier circuit that amplifies an input image signal (analog signal). 125
Is a motor drive circuit for driving the motor 110.

FIG. 2 is a timing chart showing a change over time in the document conveying speed and the document position. In the figure,
The horizontal axis 203 indicates time. The vertical axis 201 indicates the document transport speed (document reading speed), and the vertical axis 202 indicates the document 107
Indicates the position of.

FIG. 2 shows a case where the conveyance and the image reading operation are performed at the document conveying speed (document reading speed) V0, and the operation is temporarily stopped from time t0 to time t1. Further, the document transport speed (image reading speed) is gradually reduced from time t0 ′ to time t0, and
From time 1 to time t1 ', the document conveying speed (image reading speed) is gradually increased.
It has reached zero. Time t0 ', time t0 to t1, time t
The document positions at 1 ′ are Y0 ″, Y0, Y
0 '.

FIG. 3, FIG. 4, and FIG. 5 are flowcharts showing an image reading operation processing procedure. This processing program is stored in a ROM (not shown) in the control unit 120, and is also executed by a CPU (not shown) in the control unit 120. First, initial processing such as self-diagnosis processing, communication with a host computer, image correction processing using correction data, and automatic paper ejection is performed (step S1).

Waiting for a request to start reading an image from the host computer 116 or an operation panel (not shown) or the like (step S2). (Step S3). If there is no original to be read, a process for reading no original is performed (step S4), and the process returns to step S3.

On the other hand, if there is an original to be read in step S3, a read mode such as resolution, read image size, and gradation is set (step S5). Then, the clock period PMT of the motor 110 and the read start signal SP of the position line of the CIS 121 are sent to PMT1, PMT1, respectively.
SP1 is set (step S6). Here, the cycle of the read start signal SP is the read time of the position line. Read start signal SP and clock cycle PMT
Is set by the timing generator 126 in the controller 120. A value determined by the read speed according to the read mode set in step S5 is set in the clock cycle PMT and the read start signal SP.

Then, feeding and feeding of the document are started (step S7). The transport speed at this time is determined by the clock cycle PMT. The motor 110 is rotated (step S8), and the process waits until the leading edge of the document is detected (step S9). When the leading edge of the document is detected, after a lapse of a predetermined time, the image reading speed is determined by the reading start signal SP.
The image reading operation of the document is started (step S1).
0).

Thereafter, it is determined whether or not the trailing edge of the original is detected by a paper ejection sensor (not shown) (step S).
11). Instead of using the paper ejection sensor, it may be determined whether or not a predetermined time has elapsed since the leading edge of the document is detected by the document leading edge detection sensor 114. When the trailing end of the document is detected by the paper discharge sensor, the reading end processing for one page is performed (step S1).
2), it is determined whether there is a document of the next page (step S1).
3). If there is a document of the next page, the process returns to step S7 and the reading operation is performed again. On the other hand, if there is no original of the next page, post-processing is performed (step S14), and this image reading processing is terminated. In this image reading process, a paper jam of a document may be detected.

On the other hand, if the trailing edge of the original is not detected by the paper ejection sensor in step S11, the image reading operation is performed due to the transfer speed of the image data or the capacity of the image memory, or a request from the host computer 116 or the like. It is determined whether or not it is necessary to temporarily suspend (pause) (step S15). If there is no need to temporarily suspend, the process returns to step S10, and if there is a need to temporarily suspend, it is determined whether or not the current document transport speed PMT is higher than a predetermined speed ΔPMT0 (step S16).

The current document transport speed PMT is equal to a predetermined speed Δ
If it is larger than PMT0, it is determined that slowdown is necessary, and the document scanning speed setting unit 112 reads the slowdown data (step S17). Instead of reading, slowdown data may be generated.

Here, the slowdown data is stored in the register as an array for each step. In the processing from step S18 to step S23, the motor 110 and the CIS are stored based on the stored slowdown data.
121 is controlled. That is, the initial value N is set to the variable n (step S18), and the slowdown data DIMSLDMTR (n) and DIMSLDSP corresponding to the variable n are set.
(N) is substituted for the clock cycle PMT and the read start signal SP, respectively, to start the timer Timer (step S19), and to perform motor rotation and image reading (step S20). Step S20 is repeated until the timer Timer times out (step S20).
21) When timeout occurs, the variable n is decremented by 1 (step S22), and it is determined whether or not the variable n is 0 (step S23). If the value is not 0, the process returns to step S19. If the value is 0, the process returns to step S2.
The processing moves to the processing of step 4.

It should be noted that CI based on the read start signal SP
The setting of the operation timing in S121 is performed by changing the setting of the transfer timing of the electric signal converted by the CIS 121.

By the slowdown process, the motor speed and the image reading speed are gradually reduced from time t0 'to time t0 in FIG. As a result, the document positions Y0 "to Y0
, The document can be stopped gently.

Then, the motor 110 and the CIS 121
Is completely stopped (step S24). Thereafter, the stop state is secured for a predetermined time. That is, the timer Timer is started (step S2).
5) Wait until the timer Timer reaches a predetermined time TPAUSE (step S26). This is because if the slowdown data is small due to factors such as the capacity of the image memory, the motor control may cause a slight vibration and attenuate even if stopped, and if the slowdown data is sufficient. This process is not necessary if sufficient time is allowed for slowdown.

Then, the process waits until an image reading restart request is input (step S27). When a request for resuming image reading is input, step S28 to step S28 are performed.
The slow-up process up to 33 is performed. That is, in the case of resuming the image reading from the temporary stop, the slow-up process is always performed.

In the slow-up process, the variable n is set to an initial value M
Is set (step S28), and the slow-up data DI
MSLD (n) and DIMSLD (n) are substituted for the clock cycle PMT and the read start signal SP, respectively, to start the timer Timer (step S29), and to perform motor rotation, image reading and data transfer (step S30). The process of step S30 is repeated until the timer Timer times out (step S31). When the process times out, the variable n is decremented by 1 (step S32), and it is determined whether or not the variable n becomes 0 (step S33). If the value is not 0, step S29
When the value is 0, the process proceeds to step S34.

By this slow-up processing, the motor control (image reading operation) of the slow-up from time t1 to time t1 'in FIG.
The transport speed is gradually increased to 0 ', and finally the speed V
To reach zero. When the pause process is completed, the clock cycle (document transport speed) PMT and the document reading start signal SP are returned to their original values (step S3).
4), the process proceeds to step S10 and returns to the normal reading operation.

On the other hand, in step S16, the document transport speed PM
When it is determined that T is equal to or less than the predetermined speed ΔPMT0,
The motor 110 and the image reading operation are immediately stopped (step S35). At the time of this temporary stop, step S2
5, as in S26, the stop state is secured for a predetermined time (absorption time of relaxation oscillation) (steps S36, S3).
7). Then, the process waits for the input of the image reading restart request (step S38).
The process moves to step S34.

As described above, when the motor speed at the time of the temporary stop is equal to or higher than the predetermined value, the motor speed and the image reading operation are stopped by slowing down.
By restarting by slow-up, the influence on the read image of the document is reduced, and high-quality image reading at low cost is realized.

FIG. 6 is a timing chart showing a change over time in the document conveying speed and the document position when a stepping motor is used as the motor 110. In the stepping motor, since the excitation is switched in a stepwise manner, the speed is gradually reduced from the document conveying speed V0. As a result, the image reading speed is gradually decreased similarly to the motor speed, so that the same effect can be obtained by the same control as that shown in FIG.

It should be noted that only one of slow down and slow up may be controlled. Also, the first
In the embodiment, the case of the suspension is described as an example,
Even when the reading speed is changed midway, high-quality image reading can be performed similarly by performing slow down and slow up.

Further, in the case of an image scanner using a reduction optical system, the original is fixed and the reflection mirror and the like are moved. In this case, the motor speed is replaced by the movement speed of the reflection mirror. Is equally applicable.

[Second Embodiment] In the first embodiment, the case where the document conveying speed and the document reading speed are gradually reduced or increased stepwise has been described, but in the second embodiment, Further, a case will be described in which the light amount of the document illumination light source is also changed according to the document reading speed.

Since the electrical configuration of the image reading apparatus according to the second embodiment is the same as that of the first embodiment, the description thereof will be omitted, and only operations different from those of the first embodiment will be described.

FIG. 7 is a timing chart showing the change over time of the document conveying speed, the document position and the light amount in the second embodiment. The relationship between the document transport speed and the document position is the same as in the first embodiment. Further, in the second embodiment, the light amount of the light source for illuminating the original is gradually reduced as the original conveyance speed is reduced. This is to prevent a relatively large amount of light emitted per unit area of the document when the document conveyance speed is reduced. That is, the document transport speed (document reading speed)
The amount of light of the light source for illuminating the document is also reduced in accordance with the decrease in. At this time, the light amount of the light source for illuminating the original is represented by Expression (1).

L0 / V0 = L1 / V1 × α (1) where V0 is the original document conveying speed before the change, V1 is the original document conveying speed after the change, L0 is the light amount before the change, and L1 is the light amount after the change. The light quantity, α, is a constant.

Switching of these light amounts is performed by the light amount adjustment circuit 12.
3 is performed. The changed light amount L1 shown in FIG. 7 is obtained from time t0 to time t0 "after stopping at the document position Y0 in order to read an image at that position when the document is stopped at the document position Y0.
Time to continue. This is because the document is illuminated with a predetermined amount of light to read image data.

FIGS. 8, 9 and 10 are flowcharts showing the procedure of an image reading operation according to the second embodiment. The same step processes as those in the first embodiment are denoted by the same step numbers, and description thereof is omitted.

Step S17 in the second embodiment
In A, S19A, and S29A, slowdown and slowup data are set in the light amount LT in addition to the clock cycle (document conveyance speed) PMT of the motor 110 and the image reading start signal SP. Further, steps S26A and S26
At 35A, the light source 103 is turned off after the motor and the image reading operation are temporarily stopped. Step S6A,
In step S34A, the light amount LT of the light source is set to a value corresponding to the reading mode together with the motor cycle PMT and the image reading start signal SP.

As described above, when the document reading speed, that is, the document conveying speed is gradually reduced or increased, the amount of light of the document irradiating light source is also adjusted according to the speed change, thereby adjusting the integrated irradiation light amount to the document. . As a result, the image density can be kept uniform for each page or within one page. The present invention, like the first embodiment,
The present invention can be applied not only to the case where the reading is resumed from the pause but also to the case where the document conveying speed is switched, and the same effect can be obtained.

FIG. 11 is a timing chart showing a change over time of the document conveying speed, the document position and the light amount when a stepping motor is used. In the case of a stepping motor, the image reading speed and the light amount are also gradually reduced by gradually decreasing the speed from the document conveying speed V0, similarly to the motor speed. Further, after the document is stopped, the image is read with the light amount L1 during a period from time t0 to time t0 ″.

The adjustment of the light amount of the light source for document illumination includes a method of switching the current value of the light source, a method of controlling the ON duty of the applied voltage, and the like.

The present invention may be applied to a system composed of a plurality of devices, or may be applied to an apparatus composed of one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. In this case, by reading out a storage medium storing a program represented by software for achieving the present invention into a system or an apparatus, the system or the apparatus can enjoy the effects of the present invention.

FIG. 12 is a diagram showing a memory map of the ROM in the control unit 120 as a storage medium. Control unit 120
The ROM in FIG. 3 stores the image reading operation processing program modules of FIGS. 3, 4, and 5, the image reading operation processing program modules of FIGS. 8, 9, and 10, and the like. The storage medium for supplying the program module is not limited to the ROM, and may be, for example, a floppy (registered trademark).
A disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, DVD, nonvolatile memory card, or the like can be used.

[0062]

According to the present invention, the difference between the current speed and the target speed is determined when the reading operation of the document is temporarily interrupted, when the reading operation is restarted, or when the document conveying speed is switched. If the speed is equal to or higher than the predetermined value, the speed is changed stepwise or gradually, and furthermore, by adjusting the light amount of the document illumination according to the speed, even if the image is temporarily stopped in the middle of the image reading operation, a high quality image can be obtained. A read image can be obtained. Further, it can be realized at low cost.

[Brief description of the drawings]

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

FIG. 2 is a timing chart showing a change over time in a document conveying speed and a document position.

FIG. 3 is a flowchart illustrating an image reading operation processing procedure;

FIG. 4 is a flowchart showing the image reading operation processing procedure following FIG. 3;

FIG. 5 is a flowchart showing an image reading operation processing procedure following FIGS. 3 and 4;

FIG. 6 is a timing chart showing a change over time in a document conveying speed and a document position when a stepping motor is used as the motor 110;

FIG. 7 is a timing chart illustrating a change over time of a document conveyance speed, a document position, and a light amount in the second embodiment.

FIG. 8 is a flowchart illustrating an image reading operation processing procedure according to the second embodiment.

FIG. 9 is a flowchart illustrating an image reading operation processing procedure following FIG. 8;

FIG. 10 is a flowchart showing an image reading operation processing procedure following FIGS. 8 and 9;

FIG. 11 is a timing chart showing a change over time of a document conveying speed, a document position, and a light amount when a stepping motor is used.

FIG. 12 is a diagram showing a memory map of a ROM in a control unit 120 as a storage medium.

FIG. 13 is a diagram illustrating a configuration of a conventional image scanner.

FIG. 14 is a timing chart showing a change over time of a document conveying speed and a document position.

[Explanation of symbols]

 Reference Signs List 101 Image reading device 102, 105, 108, 118 Roller 103 Light source 107 Document 110 Motor 112 Document scanning speed setting unit 116 Photoelectric conversion element 120 Control unit 121 Image reading unit (CIS) 123 Light amount adjustment circuit 126 Timing generation unit

Claims (12)

[Claims] 1. An image reading apparatus comprising: photoelectric conversion means for converting light from a document into an electric signal; and document scanning means for relatively scanning the document with respect to the photoelectric conversion means. Means for changing the setting of the scanning speed with time if the difference between the scanning speeds is equal to or greater than a predetermined value when changing from the first document scanning state to the second document scanning state. apparatus. 2. The image reading apparatus according to claim 1, wherein when the document scanning unit temporarily stops the image reading operation, the setting of the scanning speed is reduced with time. 3. The apparatus according to claim 1, wherein the document scanning unit increases the setting of the scanning speed with time when resuming the image reading operation from the paused state.
The image reading device according to claim 1. 4. The document scanning means conveys the document to the fixed photoelectric conversion means,
2. The image reading apparatus according to claim 1, wherein the original is scanned. 5. The document scanning unit moves the photoelectric conversion unit with respect to the fixed document,
2. The image reading apparatus according to claim 1, wherein the original is scanned. 6. The image reading apparatus according to claim 1, wherein the operation timing of the photoelectric conversion unit is set according to a scanning speed set during an image reading operation. 7. An image signal transfer unit for sequentially transferring the electric signals converted by the photoelectric conversion unit, wherein a transfer timing of the electric signals is set according to the set scanning speed. The image reading device according to claim 6. 8. The image reading apparatus according to claim 6, further comprising storage means having a storage capacity for image data corresponding to at least the set scanning speed. 9. An illuminating means for illuminating the original, and a light amount adjusting means for adjusting an amount of light illuminated on the original by the illuminating means in accordance with the set scanning speed. The image reading device according to claim 6. 10. The image reading apparatus according to claim 9, wherein when the scanning of the document is stopped, the illumination unit is turned on for a predetermined time to perform an image reading operation in a stopped state. 11. An image reading method for reading an image of a document by relatively scanning the document with respect to a photoelectric sensor that converts light from the document into an electric signal, the method comprising: 2. The method according to claim 1, further comprising the step of changing the setting of the scanning speed with time if the difference between the scanning speeds is equal to or greater than a predetermined value when changing to the second original scanning state. 12. A program which is executed by a computer which controls an image reading apparatus which reads an image of a document and which scans the document relatively to a photoelectric sensor which converts light from the document into an electric signal is stored. In the storage medium, the program may include a step of changing the setting of the scanning speed with time when the difference in the scanning speed is equal to or more than a predetermined value when changing from the first document scanning state to the second document scanning state. A storage medium characterized by including.