JP2003179731A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the problem wherein a time to start original reading becomes late when data for black level correction and data for white level correction are sampled before starting reading an image. <P>SOLUTION: The image reader is provided with an image reading means for reading the image of an original by moving a scanner mounted with a lamp in a sub-scan direction, a means for executing data sampling processing for black level correction (S1-S3) for starting moving the scanner toward under a white reference board before starting reading the image and for sampling the data for black level correction by using black image data read in a state to turn off the lamp while moving the scanner toward under the white reference board and a means for executing data sampling processing for white level correction (S4-S7) for sampling the data for white level correction by using white image data when a white reference board is read by turning on the lamp in a prescribed timing before starting reading the image and after sampling the data for black level correction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for optically reading an image on a document.

[0002]

2. Description of the Related Art Image reading apparatuses are widely used in image forming apparatuses such as scanners, copying machines, and facsimiles. In the image reading device, an image of the original set on the platen glass platen is displayed by a CCD (Charge).
Coupled Device) There is a system in which an image sensor such as an image sensor is used for reading and scanning in the main scanning direction, while a scanning device called a carriage is used for reading and scanning in the sub scanning direction.

Generally, in an image reading apparatus, a correction process called black level correction and a correction process called white level correction (or light amount fluctuation correction) are performed on image data read from a document. The black level correction adjusts the output level (black level) of the device when the black part of the document is read, and the white level correction is the output level (white level) of the device when the white part of the document is read. To adjust. The correction data corresponding to this (hereinafter, black level correction data) is used for the black level correction, and the correction data corresponding to this (hereinafter, white level correction data) is also used for the white level correction.

The black level correction data is collected by using the black image data obtained when the white reference plate is read with the lamp off, and the white level correction data is the white reference when the lamp is on. It is sampled using white image data obtained when the plate is read. The white reference plate is a white plate having a uniform reflectance in the main scanning direction.

In the conventional image reading apparatus, the black level correction data collection and the white level correction data collection described above are performed every time when the image of the original is read in order to prevent the output variation with time as much as possible. Has been done. Data collection at that time is performed in the order of black level correction data → white level correction data before the start of image reading.

[0006]

Here, in the conventional image reading apparatus, in the case of collecting the black level correction data, the black reference data is read by reading the white reference plate with the lamp off, and the black image data is read. When collecting level correction data, the white image data is read by reading the white reference plate with the lamp turned on. On the other hand, the home position (standby position) of the scanning body is set to a position slightly (for example, about 20 mm) slightly advanced from the original image reading start position in the sub-scanning direction into the original image reading range, and the white reference plate is set. Is arranged at a position outside the document image reading range in the sub-scanning direction (usually under the document abutting guide).

Therefore, in the conventional image reading apparatus, before the start of image reading, first, the scanning body is moved from the home position to below the white reference plate so as not to be affected by outside light, and the lamp is turned off there. After collecting the black level correction data in this state, the lamp is turned on to collect the white level correction data. Further, since the fluctuation of the light amount at the rising is large immediately after the lamp is turned on, the white image data is fetched after waiting the time until the light amount of the lamp is stabilized (hereinafter, lamp light amount stable time). Therefore, the time from when the reading of the original image is instructed (for example, after the reading start button is pressed) until the reading of the original image is actually started (hereinafter, the original image reading start time) becomes long. There was a problem.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to collect a black level correction data and a white level correction data in sequence before reading an image. An object of the present invention is to provide an image reading device that can shorten the reading start time.

[0009]

A first image reading apparatus according to the present invention comprises an image reading means for reading an image of an original using a scanning body which is equipped with a lamp and is supported so as to be movable in the sub-scanning direction. , The black image data read with the lamp turned off while the scanning body starts moving toward the bottom of the white reference plate before the image reading starts and the scanning body moves toward the bottom of the white reference plate. And a black level correction data collecting means for collecting the black level correction data by using.

In the first image reading apparatus described above, before the start of image reading, the scanning body starts moving toward the bottom of the white reference plate, and while the scanning body moves toward the bottom of the white reference plate. , The black level correction data is collected using the black image data read with the lamp off, so the black level correction data is collected after moving the scanning body under the white reference plate as in the conventional case. Compared with the case, the document image reading start time is substantially shortened by the time required to collect the black level correction data. Further, in the first image reading apparatus, when the reading margin area outside the original image reading range in the main scanning direction is read while the lamp is off while the scanning body is moving toward the bottom of the white reference plate. By collecting the black level correction data using the black image data, the black image data is captured without being affected by outside light even if the document pressing member is open and the scanning body is moving.

A second image reading apparatus according to the present invention is an image reading unit for reading an image of an original using a scanning body which is equipped with a lamp and is supported so as to be movable in the sub-scanning direction, and before starting the reading of the image. At the same time, the scanning body is moved toward the bottom of the white reference plate, and the open / closed state of the document pressing member is detected before or after the movement of the scanning body is detected. While the scanning body is moving toward the bottom of the reference plate, a black level correction data sampling means for sampling black level correction data using the black image data read with the lamp off is provided. ing.

In the second image reading apparatus, the scanning member is started to move toward the bottom of the white reference plate before the image reading is started, and the document pressing member is also before or after the movement of the scanning member is started. The open / closed state of the scanner is detected, and when the document holding member is closed, black level correction is performed using the black image data read while the lamp is off while the scanner is moving under the white reference plate. To collect data,
The original image reading start time is shortened as compared with the case where the black image data is read after moving the scanning body under the white reference plate as in the related art. Further, when capturing the black image data while the scanning body is moving, since the external light is reliably blocked by the document pressing member, the black image data is captured without being affected by the external light.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration example of an image reading apparatus to which the present invention is applied. In the illustrated image reading apparatus 1, a platen glass 3 serving as a document table is attached to an upper portion of the apparatus main body 2, and a document abutting guide (document positioning member) 4 and a white reference plate 5 are further provided on the platen glass 3. It is installed.

The platen glass 3 is composed of a transparent and flat glass plate, and is attached in a state of being fitted into a rectangular opening formed in the upper portion of the apparatus main body 2. Further, the platen glass 3 is provided on the upper part of the apparatus main body 2.
An original pressing cover (not shown) for pressing the original set on the upper side is openably and closably attached. The document pressing cover is opened / closed by a user, and a cushion member for pressing the document is integrally provided on the lower surface side thereof. The cushion member is, for example, a sponge-like member, and a white thin sheet is attached to the pressing surface that actually presses the document.

The document abutting guide 4 is provided for positioning a document set on the platen glass 3, and is attached to the platen glass 3 together with the white reference plate 5. In this mounted state, the level difference between the platen glass 3 and the document abutting guide 4 is substantially 1 mm. Document abutting guide 4
2 indicates the main scanning direction (vertical direction in the figure; X
Direction) and a second document abutting guide 4B along the sub-scanning direction (left and right direction in the drawing; Y direction) are combined to form an overall L-shape. When the image reading device is viewed in a plan view, the main scanning direction X and the sub scanning direction Y are directions orthogonal to each other.

The first document abutting guide 4A regulates the position of the document in the sub scanning direction Y, and the second document abutting guide 4B regulates the position of the document in the main scanning direction X. Therefore, when setting a document on the platen glass 3, one side of the document that is perpendicular to each other is abutted against the first abutting guide 4A, and the other side of the document is a second document abutting guide 4B. By abutting, the document is positioned on the platen glass 3.

The white reference plate 5 is an elongated plate mainly used for collecting white reference data, and the first document abutting guide 4 is used.
It is arranged in parallel with the main scanning direction X while being covered by A. The white reference plate 5 is in the longitudinal direction (main scanning direction X).
A white reference surface having a uniform reflectance is provided over the entire surface of the platen glass 3.
Are placed in surface contact with. The original document abutting position by the first original document abutting guide 4A is the original image reading start position Ps in the sub-scanning direction Y. On the other hand, the white reference plate 5 is arranged at a position outside the document image reading range, which is deviated in one direction (leftward in the drawing) from the reading start position Ps in the sub-scanning direction Y. The original image reading range refers to an effective range when the image of the original set on the platen glass 3 is read by the image reading unit 6. Generally, when the document pressing cover is opened and the apparatus main body 2 is viewed in a plan view, the range in which the platen glass 3 is exposed except for the portion where the document abutting guide 4 is attached is the document image reading range.

On the other hand, inside the apparatus main body 2, an image reading section 6 for optically reading an image of a document is provided. The image reading unit 6 mainly includes an optical scanning system 7 and an imaging lens 8.
And a CCD image sensor 9.
The optical scanning system 7 is a full-rate carriage 1 serving as a scanning body.
0 and a half rate carriage 11. A lamp 12, a reflector 13 and a first mirror 14 are mounted on the full rate carriage 10, and a second mirror 15 and a third mirror 16 are mounted on the half rate carriage 11.

The lamp 12 and the reflector 13 irradiate line-shaped light along the main scanning direction X toward an irradiation object on the platen glass 3 (a manuscript set on the platen glass 3, the white reference plate 5, etc.). The reflected light from the irradiation object is sequentially reflected by the first mirror 14, the second mirror 15, and the third mirror 16 as shown by the arrow in the figure. The image forming lens 8 forms an image of the light reflected by the third mirror 16 on the light receiving surface of the CCD image sensor 9 at a predetermined magnification. The CCD image sensor 9 serves as a reading sensor for reading the image of the document, and generates an analog image signal according to the reflected light from the document.

The full-rate carriage 10 and the half-rate carriage 11 can be moved in the sub-scanning direction Y along the platen glass 3 by a guide mechanism (guide rail or the like) and a power transmission mechanism (for example, wire or pulley) which are not shown. Supported by. The carriages 10 and 11 are configured to move in the sub-scanning direction Y using a common carriage motor (for example, a pulse motor) as a drive source. The home position Ph of the full-rate carriage 10 in the sub-scanning direction Y is a position slightly (for example, about 20 mm) slightly advanced from one side of the document abutting guide 4 (4A) serving as the document image reading start position Ps into the document image reading range. Is set to. When moving in the sub-scanning direction Y, the half-rate carriage 11 moves at a moving amount (moving speed) that is half that of the full-rate carriage 10, whereby the carriages 10, 11 move to any position in the sub-scanning direction Y. Even in this state, the optical path length from the document surface on the platen glass 3 to the light receiving surface of the CCD image sensor 9 is always kept constant.

FIG. 3 is a block diagram showing a configuration example of a control system of the image reading apparatus according to the embodiment of the present invention. In FIG. 3, the CCD image sensor 9 is driven by a CCD driver (driver) 17. CCD image sensor 9
From, analog image data is output. This analog image data is supplied to the analog circuit section 18. The analog circuit section 18 includes a sample hold circuit, a gain control circuit, an offset control circuit, and an A / D.
It is provided with an (analog / digital) conversion circuit and the like. From the analog circuit section 18, digital image data converted by the A / D conversion circuit is generated.

The black level correction unit 19 performs a black level correction process using the black level correction data. More specifically, in the black level correction unit 19, the output level of the black image data among the image data offset-adjusted by the offset adjustment circuit of the analog circuit unit 18 finally matches the black level (zero) of the device. In this way, so-called subtraction processing is performed to subtract the offset adjustment amount. The subtraction value used in this subtraction process becomes the black level correction data. The black level correction data (subtraction value) used in the black level correction processing is given to the black level correction unit 19 from the controller 22 described later.

The white level correction section 20 is incorporated as one functional section of the shading correction circuit, and performs white level correction processing using the white level correction data. More specifically, in the white level correction unit 20, of the image data corrected by the black level correction unit 19, the output level of the white image data is appropriate so that the output level of the white image data does not vary due to the influence of the light amount variation of the lamp 12. Perform processing to match the white level. At the time of this level adjustment, the white reference data collected by reading the white reference plate when the device is turned on and the light amount reference value at that time are held in the shading correction circuit, and the white reference plate is read before starting image reading. It is performed by integrating the ratio (light amount variation ratio) between the measured light amount value and the above-mentioned light amount reference value to the white reference data. The light amount measurement value used for this level adjustment becomes white level correction data. The white level correction data (light amount measurement value) used in the white level correction processing is the controller 22 described later.
To the white level correction unit 20.

The image data fetching section 21 includes image data generated from the analog circuit section 18 and the black level correcting section 1.
The image data generated from 9 is taken in at a predetermined timing. The image data capturing unit 21 captures the image data (black image data) generated from the analog circuit unit 18 when collecting the black level correction data, and captures the black level correcting data when collecting the white level correction data. The image data (white image data) generated from the correction unit 19 is loaded. The image data captured by the image data capturing unit 21 is supplied to the controller 22.

The controller 22 includes, for example, a CPU (Central Processing Unit), a ROM (Read-Only Memory), and a RAM (R).
andom Access Memory) and performs various processes according to a control program given in advance. The controller 22 uses the above-mentioned C via the address bus, the data bus, the read / write signal line, etc.
CD drive unit 17, analog circuit unit 18, black level correction unit 19, white level correction unit 20, image data acquisition unit 21
Are interconnected with.

Further, the lamp 12 and the carriage motor 23 are connected to the controller 22 as one of control objects. The carriage motor 23 serves as a common drive source when moving the carriages 10 and 11 in the sub-scanning direction as described above. Further, to the controller 22, a registration sensor 24, a cover opening / closing sensor 25, and an operation panel 26 are connected as one of control information input means.

The registration sensor 24 is a carriage motor 23.
This is for detecting the position of the full rate carriage 10 in the sub-scanning direction Y when moving the carriages 10 and 11 in the sub-scanning direction Y by driving. The registration sensor 24 detects passage of the full-rate carriage 10 at one location (for example, near the home position Ph) or at a plurality of locations within the moving range of the full-rate carriage 10, and gives this detection signal to the controller 22. On the other hand, the controller 22 detects the position of the full rate carriage 10 in the sub scanning direction Y based on the detection signal from the registration sensor 24, and controls the drive of the carriage motor 23 based on the detection result. There is.

The cover open / close sensor 25 detects the open / closed state of the document pressing cover. A sensor sensing portion (for example, a rod-shaped actuator portion) of the cover opening / closing sensor 25 is arranged so as to project upward from the platen glass 3 by a predetermined dimension. When the document pressing cover is closed, the document pressing cover is pressed to detect the open / closed state of the cover. Cover open / close sensor 2
There are two cover open / close states that can be detected in step 5: the document pressing cover is open (open state) and the document pressing cover is completely closed (closed state). Can be detected.

The operation panel 26 is a user interface (UI) for the user of the image reading apparatus 1 to perform various operations. On the operation panel 26, together with various setting / operation buttons (or switches) for setting the reading magnification, etc., a reading start button for instructing the start of reading the original image A start button) is provided.

Next, the processing operation of the image reading apparatus 1 based on the control processing of the controller 22 will be described.

FIG. 4 is a flow chart showing the processing operation of the apparatus according to the first embodiment of the present invention. First, when the user sets a document on the platen glass 3 and presses the reading start button of the operation panel 26, the controller 22 receives the command and directs the full-rate carriage 10 to the lower side of the white reference plate 5 by driving the carriage motor 23. To start moving (step S1). The movement start position of the full rate carriage 10 at this time is the home position Ph. At the home position Ph, the size of the document in the main scanning direction is detected using the image data for one line read by instantaneously turning on the lamp 12.

Next, it is determined whether or not the elapsed time after the lamp 12 is turned off (lamp off time) is 30 ms (ms; milliseconds) or more (step S2).
The reason for checking the lamp extinguishing time here is to avoid the influence of afterglow after extinguishing the lamp. If it is determined in step S2 that the lamp extinction time has exceeded 30 ms, black level correction data is collected at that time (step S2).
3). Collection of the black level correction data is mainly performed by capturing the black image data and averaging the captured black image data. Of these, the black image data is captured by the image data capturing unit 21, and the black image data averaging process is performed by the controller 22.

At that time, conditions for capturing the black image data by the image data capturing section 21 will be described in detail. First, with the full-rate carriage 10 stopped at an arbitrary position in the sub-scanning direction Y (for example, the home position Ph), the reading range in the main scanning direction X that can be read by the CCD image sensor 9 is on the platen glass 3. Main scanning direction (transverse direction) X of the platen glass 3 excluding the pasted portion of the document abutting guide 4 (4A, 4B)
Over almost the entire length range. However, the reading range in the main scanning direction that can be substantially read by the CCD image sensor 9 is deeper than the document abutting position by the document abutting guide 4B in consideration of the dimensional tolerance and the assembly tolerance of the components. It is set so that it enters the document abutting guide 4B side). That is, the reading range in the main scanning direction X that can be read by the CCD image sensor 9 is the platen glass 3
It is set in a range in which a predetermined reading margin is added to the reading range of the original image above.

Therefore, during the actual reading, the image of the reading margin area Me (see FIG. 2) can be read together with the image of the original on the platen glass 3.
The document abutting guide 4B is provided in the reading margin area Me.
Is present, the back side of the document abutting guide 4B is read in the reading margin area Me. However, when the lamp 12 is turned off, the external light is blocked by the document abutting guide 4B, and thus the image data obtained when the reading margin area Me is read is as in the conventional case in which the lamp is turned off. It is equivalent to the image data obtained when the white reference plate is read, that is, the image data corresponding to the black image data.

Therefore, in the first embodiment, while the full-rate carriage 10 is moving toward the bottom of the white reference plate 5, the images of a plurality of lines along the main scanning direction X are sequentially read and obtained. Of the image data for a plurality of lines, the image data read in the reading margin area Me below the document abutting guide 4B is taken in as black image data. The black image data for a plurality of lines captured by the image data capturing unit 21 in this manner is supplied to the controller 22.

On the other hand, the controller 22 calculates the average data per pixel by using the black image data for a plurality of lines supplied from the image data capturing section 21. This average data is obtained by dividing the cumulative value of the black image data for a plurality of lines by the number of read lines and the number of read pixels in the read margin area Me. The average data calculated by the controller 22 in this way is given to the black level correction unit 19 as black level correction data. The black level correction data collection process is performed while the full-rate carriage 10 is moving below the white reference plate 5.

After that, in the controller 22, the full rate carriage 10 reaches below the white reference plate 5 based on the detection signal from the registration sensor 24 and the elapsed time from the start of carriage movement (for example, the value measured by a timer). The remaining time until is monitored (step S4). Then, when the remaining time reaches 30 ms, the lamp 12
Is turned on (step S5). Described here "30m
The time "s" is preset according to the time from the lighting of the lamp 13 until the light quantity of the lamp 13 stabilizes (lamp light quantity stabilization time).
Depending on the characteristics of No. 2, it may be set shorter or longer than 30 ms.

Thereafter, the controller 22 judges whether the full rate carriage 10 has reached below the white reference plate 5 based on the detection signal from the registration sensor 24 (step S6). At this time, white level correction data is collected (step S7). Collection of white level correction data is mainly performed by capturing white image data and averaging the captured white image data. Of these, the white image data is captured by the image data capturing unit 21, and the white image data averaging process is performed by the controller 22.

In collecting the white level correction data, first, the full rate carriage 1 is placed under the white reference plate 5.
In the state where 0 is stopped, one line of the image along the main scanning direction X (reference surface to be read of the white reference plate 5) is read, and the one line of white image data obtained by this is input to the image data capturing section 21. take in. The white image data captured at this time becomes image data that has been corrected by the black level correction unit 19 using the black level correction data collected in step S3. The one-line white image data thus captured is supplied from the image data capturing unit 21 to the controller 22.

On the other hand, the controller 22 uses the one-line white image data supplied from the image data capturing section 21 to obtain the average data for 100 pixels in the center of the pixel row of the CCD image sensor 9, for example. calculate.
This average data is obtained by dividing the cumulative value of the pixel data for the central 100 pixels by the number of pixels (100). The average data calculated by the controller 22 in this way is used as white level correction data by the white level correction unit 2.
Given to 0. When the white level correction data collection process is completed, the carriage motor 23 is driven to move the full rate carriage 10 from below the white reference plate 5 to the document reading area side (left side in FIG. 1) to read the document image. (Step S8). In this case, the image of the document in the stopped state set (positioned) on the platen glass (document platen) 3 is read by moving the full rate carriage 10 and the herb rate carriage 11 in the sub scanning direction Y.

In the processing operation of the apparatus according to the first embodiment described above, the full rate carriage 10 starts to move below the white reference plate 5 before the start of image reading, and
During the movement of the full rate carriage 10 toward the bottom of the white reference plate 5, black level correction data is collected using the black image data read with the lamp 12 turned off.
Compared to the case where the full-rate carriage is moved below the white reference plate to collect the black level correction data as in the conventional case, the original image reading start time is substantially equivalent to the time required to collect the black level correction data. Can be shortened.

Further, the reading margin area Me outside the original image reading area in the main scanning direction X is set as the reading target, and the image data read in the reading margin area Me is taken in as black image data. Even when the cover is open, black image data can be taken in without being affected by outside light while the full rate carriage 10 is moving.

Further, before collecting the white level correction data, the full rate carriage 1 is collected.
Since the lamp 12 is turned on before 0 reaches below the white reference plate 5, the full rate carriage 10 reaches below the white reference plate 5 (moves at the same time), and at the same time, white level correction data sampling processing is performed. Can start. This makes it possible to further reduce the original image reading start time.

After the black level correction data is collected, the remaining time until the full rate carriage 10 reaches below the white reference plate 5 is monitored, and at the timing when the remaining time coincides with the lamp light quantity stabilization time. Since the lamp 12 is turned on, when the full rate carriage 10 reaches below the white reference plate 5, the lamp 12 must be turned on.
The amount of light is stable. Therefore, it is possible to reliably prevent the variation of the white image data due to the light amount variation. This effect can be obtained even when the lamp 12 is turned on at a timing before the remaining time until the full-rate carriage 10 reaches below the white reference plate 5 matches the lamp light amount stable time (30 ms in this example).

FIG. 5 is a flow chart showing the processing operation of the apparatus according to the second embodiment of the present invention. First, when the user sets a document on the platen glass 3 and presses the reading start button of the operation panel 26, the controller 22 receives the command and directs the full-rate carriage 10 to the lower side of the white reference plate 5 by driving the carriage motor 23. After the start of the movement (step S11), it is determined whether or not the elapsed time after the lamp 12 is turned off (lamp off time) is 30 ms or more (step S12). The processing up to this point is the same as the processing in steps S1 and S2 in the first embodiment.

Subsequently, the controller 22 detects the open / closed state of the document pressing cover based on the detection signal from the cover open / close sensor 25 when the lamp extinction time exceeds 30 ms (step S13). The detection processing of the cover open / closed state may be performed before (immediately before) the movement of the full rate carriage 10 is started. Here, if the document pressing cover is in the closed state, the process proceeds to step S14,
If the document pressing cover is in the open state, the process proceeds to step S20.

In step S14, black level correction data is collected. In the black level correction data collection process in step S14, the entire platen glass 3 is covered with the document pressing cover, whereby the outside light is surely blocked. In this case, since it is not necessary to consider the influence of external light, the image data read in the area within the original image reading range in the main scanning direction X is directly captured by the image data capturing unit 21 as black image data. In step S14, black image data for a plurality of lines is captured as the full-rate carriage 10 moves. Then, average data per pixel is calculated by the controller 22 using the black image data for the plurality of lines, and the average data is sampled as black level correction data.

At this time, it is desirable that the black image data be taken in on the pressing surface (white sheet surface) of the cushion member of the closed document pressing cover. The reason is that when the original pressing cover is in the closed state, the pressing surface of the cushion member is in close contact with the surface of the platen glass 3, so that black image data can be taken in stably, while the pressing surface of the cushion member is At a position deviated from, that is, in the main scanning direction or the sub scanning direction Y, the document abutting guide 4 (4A
This is because black image data cannot be properly captured in the gap portion formed between 4B) and the cushion member.

After that, the processes of steps S15 to S19 are performed in the same manner as the processes of steps S4 to S8 in the first embodiment. That is, in step S15, the remaining time until the full rate carriage 10 reaches below the white reference plate 5 is monitored as in step S4, and in step S16, the lamp 12 is turned on as in step S5. Further, in step S17, step S
Similar to 6, it is determined whether the full rate carriage 10 has reached below the white reference plate 5 based on the detection signal from the registration sensor 24, and in step S18, step S7 is performed.
Similarly, the white level correction data is collected. Then, in step S19, the document image is read as in step S8.

On the other hand, in step S20, based on the detection signal from the registration sensor 24, it is determined whether or not the full rate carriage 10 has reached below the white reference plate 5,
When it is determined that the black level has been reached, black level correction data is collected at that time (step S21). In this case, each line image data when the white reference plate 5 is read over a plurality of lines with the lamp 12 turned off is taken in as black image data. Then, the average data per pixel calculated using the black image data for the plurality of lines is collected as the black level correction data.

After that, the lamp 12 is turned on and
Elapsed time from lighting is 30 ms (lamp light intensity stabilization time)
(Steps S22, S2
3) If it is determined that the arrival has been reached, white level correction data is collected at that time (step S18), and then the original image is read (step S19).

By the way, in the white level correction data sampling process in step S18, the white image data corrected by using the black level correction data sampled in step S14 or the black level sampled in step S21. White image data corrected using the correction data is captured by the image data capturing unit 21.

In the processing operation of the apparatus according to the second embodiment described above, the open / closed state of the document pressing cover is detected after the movement of the full rate carriage 10 is started (or before the movement is started), and at the time of this detection, the document pressing cover is closed. Is set, the full-rate carriage 10 oriented under the white reference plate 5
Since the black image data is read during the movement of, the start time of the original image reading can be shortened as compared with the case where the full rate carriage is moved below the white reference plate and then the black image data is read as in the conventional case. it can. Further, when the black image data is taken in while the carriage is moving, since the external light is blocked by the document pressing cover, the black image data can be taken in without being affected by the external light.

When the document pressing cover is in the open state, after the level correction data is collected in step S14, before the full rate carriage 10 reaches below the white reference plate 5 (before it is determined as Yes in step S17). Lamp 12
Is turned on, it is possible to start the process of collecting the white level correction data at the same time when the full rate carriage 10 reaches under the white reference plate 5 (stops moving). This makes it possible to further reduce the original image reading start time.

After the black level correction data is collected, the remaining time until the full rate carriage 10 reaches below the white reference plate 5 is monitored in step S15, and the remaining time matches the lamp light quantity stabilization time. Since the lamp 12 is turned on at the timing (the timing of determining Yes in step S15), the light amount of the lamp 12 is always stable when the full rate carriage 10 reaches below the white reference plate 5. Become. for that reason,
It is possible to reliably prevent the variation of the white image data due to the fluctuation of the light amount. This effect is the full rate carriage 1
Even when the lamp 12 is turned on at a timing before the remaining time until 0 reaches below the white reference plate 5 matches the lamp light amount stabilization time (30 ms in this example).

FIG. 6 is a schematic view showing another structural example of the image reading apparatus to which the present invention is applied. In describing the configuration of the image reading apparatus shown in FIG.
The same components as those of the device shown in FIG.

In the illustrated image reading apparatus 1, a document pressing cover 27 is provided on the upper part of the apparatus main body 2 so as to be openable and closable, and the document feeding device (automatic document. A feeder (ADF) 28 is installed. Document feeder 28
Is to automatically convey the original document 30 set on the original document tray 29 to an image reading position described later.
The conveyed document 30 is discharged to a discharge tray unit 31 using the upper surface of the document pressing cover 27. A cushion member (not shown) for pressing the original is provided on the lower surface of the original pressing cover 27. The cushion member is as described above.

The document feeder 28 can be opened and closed so that the document detection sensor 32 for detecting the presence or absence of the document 30 on the document tray 29 and the tip of the document 30 when the document 30 is set on the document tray 29 are abutted. A gate member 33, a feeding roll 34 for feeding the originals (original bundle) 30 set on the original tray 29 in order from the highest position (the lowest position depending on the apparatus configuration), and the original document 30 fed by the feeding roll 34. A pair of feed rolls 35 that separates and feeds the sheets one by one, a plurality of pairs of feed rolls 36 that feeds the document 30 fed by the pair of feed rolls 35 along a predetermined transport route, and the document 30 advances at appropriate places on the transport route It has a configuration including a switching gate 37 for switching the direction.

In the document feeder 28 having the above-mentioned structure,
After the document 30 set on the document tray 29 is delivered by the delivery roll 34, the delivery roll pair 35
Are separated one by one and sent out. The original document 30 sent out in this manner is sequentially delivered to each of the pair of transport rolls 36, and is transported according to the switching of the traveling direction by the switching gate 37. At this time, when reading an image recorded on one side of the original document 30, the original document 30 is conveyed in the order of arrow → → → and discharged to the discharge tray unit 31. Further, when reading images recorded on both sides of the original document 30, it is necessary to reverse the original document surface during conveyance and return the inverted original document surface to the original state. Therefore, the original document 30 is arrowed →→→→→ →
The sheets are conveyed in the order of →→→ and discharged to the discharge tray unit 31.

On the other hand, a platen glass 38 for image reading is attached to the upper part of the apparatus main body 2 separately from the platen glass 3 on the side opposite to the platen glass 3 with the document abutting guide 4 interposed therebetween. This platen glass 38
Is for reading an image of a document 30 conveyed by the document conveying device 28, and is composed of a transparent glass plate. When the image of the original 30 is read using the original conveying device 28, the image reading position is set at the substantially central portion of the platen glass 38 in the sub-scanning direction Y, and the original conveying device 28 causes the original 30 to pass through the reading position. Will be transported.

The image reading apparatus having the above-described configuration has a reading mode of 2 when the image of the original is read by the image reading unit 6.
It has two modes. One is the full rate carriage 10 under the platen glass 38 which is the image reading position.
Is a mode in which an image of a moving original 30 passing on the platen glass 38 is read by the original conveying device 28 (hereinafter, moving original reading mode), and the other is set on the platen glass 3. This is a mode for reading an image of a document (not shown) in a stopped state by moving the full-rate carriage 10 and the half-rate carriage 11 in the sub-scanning direction Y (hereinafter, a stopped document reading mode).

In the moving original reading mode, the image of the original is read and scanned (flow reading) in the sub-scanning direction Y in accordance with the movement of the original. In the stopped original reading mode, the image of the original is read by the carriage. By the movement of 10 and 11, reading and scanning are performed in the sub-scanning direction Y. The original image reading method based on the moving original reading mode is
It is also called a CVT (Constant Velocity Transport) method. When this moving original reading mode is applied, a plurality of originals 30 are sequentially conveyed to the reading position (on the platen glass 38) and images can be continuously read, so that the processing speed can be greatly improved. .

In the configuration of the control system when the image reading apparatus 1 shown in FIG. 6 is used, the detection signal of the presence / absence of a document by the document detection sensor 32 is input to the controller 22. It is similar to that shown in FIG.

Next, the processing operation of the apparatus executed according to the control processing of the controller 22 when the image reading apparatus 1 shown in FIG. 6 is used will be described.

FIG. 7 is a flow chart showing the processing operation of the apparatus according to the third embodiment of the present invention. First, the user sets the original 30 on the original tray 29 and sets the operation panel 26.
When the reading start button is pressed, the controller 22 receives the command and starts moving the full-rate carriage 10 below the white reference plate 5 by driving the carriage motor 23 (step S31). The movement start position of the full rate carriage 10 at this time is the home position. By the way, in FIG. 6, the full rate carriage 10 is in a state of being stopped at the home position.

Here, the reading mode applied by the image reading section 6 is switched by the controller 22 based on the detection signal of the document detection sensor 32 when the user presses the reading start button of the operation panel 26. Specifically, when the user presses the reading start button and the detection signal input from the document detection sensor 32 determines that there is a document in the document tray 29, the moving document reading mode is applied and the document tray 29 is used. If it is determined that there is no original document in, the stop original reading mode is applied. When the stopped original reading mode is applied, the size of the original in the main scanning direction is detected using the image data for one line read by instantaneously turning on the lamp 12 at the home position of the full rate carriage 10.

Next, it is judged whether or not the elapsed time after the lamp 12 is turned off (lamp off time) is 30 ms or more (step S32), and if it is determined that 30 ms or more has passed, the image reading unit 6 It is determined whether or not the moving original reading mode is applied as the original image reading mode (step S33). Depending on the determination result in step S33, the subsequent black level correction data sampling method is switched.

That is, in step S33, when it is determined that the moving original reading mode is applied, the process proceeds to step S34, and when it is determined that the moving original reading mode is not applied (in other words, the stopped original reading mode). (When it is determined that is applied), the process proceeds to step S40. By the way, the processing of steps S34 to S39 is
The processing is performed in substantially the same manner as the processing in steps S14 to S19 in the second embodiment. That is, in step S34, the black level correction data is sampled as in step S14, and in step S35, the remaining time until the full-rate carriage 10 reaches below the white reference plate 5 is monitored as in step S15. Further, in step S36, the lamp 12 is turned on as in step S16,
In step S37, it is determined whether the full rate carriage 10 has reached below the white reference plate 4 as in step S17. Further, in step S38, white level correction data is sampled as in step S18, and in step S39, a document image reading operation is performed as in step S19. However, in step S19, the original image is read in the stopped original reading mode, whereas in step S39, the original image is read.
The original image is read according to the moving original reading mode.

On the other hand, the processing of steps S40 to S43 is
The same process as steps S20 to S23 in the second embodiment is performed. That is, in step S40, it is determined whether or not the full rate carriage 10 has reached below the white reference plate 5 based on the detection signal from the registration sensor 24, as in step S20, and in step S41, it is black as in step S21. Collect level correction data. Further, in step S42, the lamp 12 is turned on as in step S22, and in step S43, the elapsed time since the lamp is turned on is 3 as in step S23.
It is determined whether or not 0 ms (lamp light amount stabilization time) has been reached. Here, steps S43 to S38, S
If the process proceeds to step 39, step S38 is followed by step S18.
After the white level correction data is collected in the same manner as in step S39, the original image is read in step S39 in the stopped original reading mode as in step S19.

In the processing operation of the apparatus according to the third embodiment, the black level correction data sampling method is selected according to the reading mode (moving original reading mode, stationary original reading mode) applied by the image reading unit 6. Since the switching is performed, the black level correction data can be collected by a method suitable for the reading mode at each time. Further, when the reading mode actually applied is the moving original reading mode, black image data is read while the full rate carriage 10 moving under the white reference plate 5 is moved. The original image reading start time can be shortened as compared with the case where the black image data is read after moving below the white reference plate.

Since the moving original reading mode is applied on the assumption that the original pressing cover 27 is closed,
Even when the full-rate carriage 10 is moving, outside light is blocked by the document pressing cover 27 when capturing black image data. Therefore, black image data can be captured without being affected by outside light.

Further, when the moving original reading mode is applied, after the black level correction data is collected in step S34, before the full rate carriage 10 reaches below the white reference plate 5 (determined as Yes in step S37). Since the lamp 12 is turned on (before the start), the white level correction data collection process can be started at the same time when the full rate carriage 10 reaches under the white reference plate 5 (stops moving). This makes it possible to further reduce the original image reading start time.

After the black level correction data is collected, the remaining time until the full rate carriage 10 reaches below the white reference plate 5 is monitored in step S35, and the remaining time matches the lamp light quantity stabilization time. Since the lamp 12 is turned on at the timing (determination of Yes in step S35), the light amount of the lamp 12 is always stable when the full rate carriage 10 reaches below the white reference plate 5. Become. for that reason,
It is possible to reliably prevent the variation of the white image data due to the fluctuation of the light amount. This effect is the full rate carriage 1
Even when the lamp 12 is turned on at a timing before the remaining time until 0 reaches below the white reference plate 5 matches the lamp light amount stabilization time (30 ms in this example).

The processing operation shown in FIG. 5 can be applied as the processing operation of the image reading apparatus equipped with the document feeder. When the reading mode applied by the image reading unit 6 is the stationary document reading mode (when No is determined in step S33), the same processing as steps S3 to S8 of the processing operation shown in FIG. 4 is applied. It is also possible to do so.

Further, as the configuration of the image reading apparatus provided with the document feeding device, an image reading position set on the document feeding route is located in an area outside the original image reading range in the main scanning direction (reading margin area). A white reference plate is provided separately,
It is also conceivable to adopt a configuration in which the white level correction data is acquired using the white reference data when the white reference plate is read. When such a configuration is adopted, moving the scanning body (full rate carriage) below the white reference plate and moving the scanning body below the image reading position are substantially the same operation. Is meant.

[0077]

As described above, the first aspect of the present invention
According to the image reading apparatus, the scanning body starts moving toward the bottom of the white reference plate before the image reading starts, and the lamp is turned off while the scanning body moves toward the bottom of the white reference plate. Since the black level correction data is collected using the black image data read in the state, compared to the case where the scanning body is moved below the white reference plate and then the black level correction data is collected as in the conventional case. It is possible to shorten the original image reading start time substantially by the time required to collect the black level correction data. Further, in the first image reading apparatus, while the scanning body is moving toward the bottom of the white reference plate, black is obtained when the reading margin area outside the original image reading range in the main scanning direction is read with the lamp off. By collecting the black level correction data using the image data, even if the document pressing member is in the open state and the scanning body is moving below the white reference plate, the effect of external light The black image data can be taken in without receiving the data. Further, in the case where the document feeding unit is provided, when the moving document reading mode using this document feeding unit is applied, the document pressing member is always in the closed state, so that the scanning body is positioned below the white reference plate. Even while moving toward, black image data can be captured without being affected by outside light.

Further, according to the second image reading apparatus of the present invention, before starting the reading of the image, the scanning member is started to move toward the bottom of the white reference plate, and the movement of the scanning member is started or The open / closed state of the document pressing member is detected after the start of movement, and when the document pressing member is in the closed state, the black image data read with the lamp off while the scanner is moving under the white reference plate is read. Since the black level correction data is collected using this method, the original image reading start time can be shortened compared to the case where the scanning body is always moved below the white reference plate and then the black image data is read as in the conventional case. it can. Further, when capturing the black image data while the scanning body is moving, the document pressing member reliably blocks the external light, so that the black image data can be captured without being affected by the external light.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of an image reading apparatus to which the present invention is applied.

FIG. 2 is a partial plan view of the image reading apparatus shown in FIG.

FIG. 3 is a block diagram showing a configuration example of a control system of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a processing operation of the device according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a processing operation of the device according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram showing another configuration example of an image reading apparatus to which the present invention is applied.

FIG. 7 is a flowchart showing a processing operation of an apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

1 ... Image reading device, 3 ... Platen glass (document table), 4
... document striking guide, 5 ... white reference plate, 9 ... CCD image sensor, 10 ... full rate carriage (scanning body),
12 ... Lamp, 19 ... Black level correction unit, 20 ... White level correction unit, 21 ... Image data acquisition unit, 22 ... Controller, 23 ... Carriage motor, 24 ... Registration sensor, 2
5 ... Cover open / close sensor, 26 ... Operation panel, 27 ... Original pressing member, 28 ... Original conveying device, 30 ... Original, 38 ...
Platen glass

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/407 H04N 1/40 101B F term (reference) 2H108 AA01 FA05 FA17 2H110 CC01 CC06 CC11 CD06 5B047 AA01 AB02 BA01 BA02 BB02 BC05 BC09 BC11 BC14 BC18 CA07 CA19 DA04 DC01 DC06 5C072 AA01 BA03 CA02 DA02 DA04 EA05 FB12 FB18 LA07 LA15 LA18 RA16 UA01 XA01 5C077 LL04 MM27 PP07 PQ11 PQ24 SS01 TT06

Claims (15)

[Claims] 1. An image reading unit for reading an image of an original by using a scanning body mounted with a lamp and movably supported in a sub-scanning direction, and the scanning body being a white reference plate before starting the reading of the image. Black that starts moving downward and collects black level correction data using the black image data read while the lamp is off while the scanning body is moving toward the bottom of the white reference plate. An image reading apparatus comprising: level correction data collection means. 2. The white level correction data is obtained by using the white image data when the lamp is turned on and the white reference plate is read before the image reading is started and after the black level correction data is collected. The image reading apparatus according to claim 1, further comprising white level correction data sampling means for sampling. 3. The black level correction data collection means,
While the scanning body is moving toward the bottom of the white reference plate, the black is obtained by using the black image data when the reading margin area outside the original image reading range in the main scanning direction is read with the lamp off. The image reading apparatus according to claim 1, wherein level correction data is collected. 4. The image reading apparatus according to claim 1, wherein the lamp is turned on after the black level correction data is collected and before the scanning body reaches below the white reference plate. 5. An original document conveying means for conveying an original document on a conveying route that passes an image reading position, wherein the image reading means sets the scanning member to one of the reading modes when reading an image of the original document. 2. The image reading apparatus according to claim 1, further comprising a moving original reading mode in which an image of a moving original passing through the reading position is read by the original feeding means in a state of being stopped below the reading position. 6. The remaining time until the scanning body reaches below the white reference plate is monitored while the scanning body moves toward the bottom of the white reference plate, and the remaining time stabilizes the lamp light amount. The image reading apparatus according to claim 4, wherein the lamp is turned on at a timing that coincides with time or a timing before that. 7. The black level correction data collecting means comprises:
The image reading apparatus according to claim 5, wherein a method of collecting the black level correction data is switched according to the reading mode applied by the image reading unit. 8. The black level correction data collection means comprises:
When the reading mode applied by the image reading unit is the moving original reading mode, an area within the original image reading range with the lamp turned off while the scanning body is moving below the white reference plate. 6. The image reading apparatus according to claim 5, wherein the black level correction data is acquired using black image data obtained when the image is read. 9. The black level correction data collecting means comprises:
9. The image reading apparatus according to claim 8, wherein the black image data is read within a region within the document image reading range and within a pressing surface of a cushion member for pressing a document. 10. An image reading unit for reading an image of an original by using a scanning body mounted with a lamp and movably supported in the sub-scanning direction; While moving downward, the open / closed state of the document pressing member is detected before or after the movement of the scanning body,
When the document pressing member is in the closed state, black level correction data is collected using black image data read while the lamp is off while the scanning body is moving toward the bottom of the white reference plate. And an image reading device for collecting black level correction data. 11. The white level correction data is obtained by using white image data when the lamp is turned on and the white reference plate is read before the image reading is started and after the black level correction data is collected. The image reading apparatus according to claim 10, further comprising white level correction data sampling means for sampling. 12. The lamp is turned on after the black level correction data is collected and before the scanning body reaches below the white reference plate when the document pressing member is in a closed state. The image reading apparatus according to claim 10. 13. The black level correction data collecting means, when the document pressing member is in a closed state, while the scanning body is moving toward the lower side of the white reference plate, the document is kept in a state where the lamp is turned off. 11. The image reading apparatus according to claim 10, wherein the black level correction data is sampled using black image data obtained by reading an area within the image reading range. 14. The remaining time until the scanning body reaches below the white reference plate is monitored while the scanning body is moving toward the bottom of the white reference plate, and the remaining time stabilizes the lamp light quantity. 13. The image reading apparatus according to claim 12, wherein the lamp is turned on at a timing that coincides with time or a timing before that. 15. The black level correction data collecting means reads the black image data in an area within the original image reading range and within a pressing surface of a cushion member for pressing the original. Item 14. The image reading device according to item 13.