JP2004194162A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an image reader which improves productivity in image reading without deteriorating image quality. <P>SOLUTION: An optical system unit (5 to 12) scans an original placed on the glass 1 of an original platen, an original image is photoelectrically converted into an electrical signal, and shading member 15 is used to apply shading correction to the electrical signal. The shading member 15 is arranged at a necessary minimum position (B) to accelerate the optical system unit to a position which is located between an original image reading start position (E) and a stop position (HP) of the optical system unit and at which the optical system unit gains a prescribed constant scanning speed that corresponds to an operation mode. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus, and is particularly suitable for use in an apparatus for improving productivity in image reading.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, there is a copying machine as an image reading device that reads an image of a document conveyed by a document conveying device. In this copying machine, after a document is placed at a predetermined position on a platen glass by a document feeder, light is emitted while scanning and moving an optical system unit equipped with an illumination light source with respect to the document. An image on a document is read based on the reflected light. Here, a conventional image reading apparatus will be described with reference to the drawings.
[0003]
FIG. 5 is a schematic sectional view of an image forming apparatus provided with a conventional image reading device, and FIG. 6 is a diagram showing a reading operation in the conventional image reading device. Here, the image forming apparatus is configured to include a document conveying device and an image reading device.
[0004]
The configuration of the document feeder and the flow of the document will be described as follows.
As shown in FIG. 5, the document feeder 4 conveys the document 30 placed on the document tray 31 to the paper feed / separation unit 25 by the pick-up roller 24, and further, after being separated by the paper feed / separation unit 25, The document is conveyed to the document conveying belt 3 by the pair 26 and 27 and placed on the document table glass 1. Then, after reading the image of the original 30 placed on the original table glass 1 by the image reading device, the original 30 is transported by the original transport belt 3 to the discharge roller pair 29 and discharged to the discharge tray 28. .
[0005]
Next, the configuration of the image reading apparatus and the method of reading a document will be described as follows.
A document (not shown) placed on the document glass 1 is illuminated by an illumination lamp 6 disposed on a first mirror table 5 serving as a scanning optical unit. Is reflected by the first mirror 7 disposed on the second and third mirror bases 8. Then, the light is reflected by the second mirror 9 and the third mirror 10, condensed by the lens 11, and formed into an image by the CCD sensor 12 as a reading element.
[0006]
The first mirror base 5, the second mirror base 8, and the third mirror base 8 are supported by rails (not shown), and are movable in the direction of the arrow with the rotation of the optical drive motor 13. A stepping motor is used as the optical motor, and the first mirror table 5 and the first mirror table 5 are controlled by a pulley or a wire (not shown) so that the optical path length from the surface of the document table glass 1 to the CCD sensor 12 is always constant. Second, the third mirror base 8 is driven. As described above, by moving the first mirror table 5, the image information on the document surface is converted into an electric signal and transferred to the image forming apparatus.
[0007]
Next, the reading operation of the conventional image reading apparatus will be described as follows.
As disclosed in Japanese Patent Laid-Open No. 4-340857, shading correction is performed on the first mirror base by the shading plate 14 arranged at the standby position (HP). In this configuration, from the end of shading correction to the start of scanning, the system stands by at the HP, the first mirror stand rises to the scanning speed by the forward scan start signal, and starts reading from the image front end (E). After reading to the maximum image position (G) corresponding to the reading size, the fall is started, and the first mirror stand stops at an arbitrary stop position (H). Subsequently, the back scan is started, and the first mirror stand stops at the HP. In the case of continuous scanning, reading is performed in a similar sequence after performing shading correction again.
[0008]
On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 2001-77980, when performing variable-magnification scanning, the scanning speed of the first mirror table is made variable according to the magnification to reduce the image memory. However, since the scanning speed is slower as the enlargement ratio is larger, it takes a longer time to move from the HP to the leading end of the image, and there is a demerit that productivity in image reading decreases.
[0009]
Therefore, as disclosed in Japanese Patent Application Laid-Open No. H8-77980, it is possible to make the scanning speed constant by temporarily reading the original, storing it in the image memory, and then changing the magnification. As a result, the moving time from the standby position (HP) to the leading end of the image becomes constant irrespective of the magnification, and the productivity in image reading can be improved. However, there is a demerit in that the cost is increased due to the increase in the memory capacity, and the image quality is reduced when the image is compressed to suppress the cost increase.
[0010]
[Patent Document 1]
JP-A-4-340857 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2001-77980 [Patent Document 3]
JP-A-8-77980
[Problems to be solved by the invention]
However, the above-described image reading apparatus has a problem of high productivity in image reading. Since the scanning speed of the scanning optical system unit varies according to each magnification, the rising distance also varies. As a result, the start-up distance becomes shorter at the time of enlargement, and becomes longer at the time of reduction. Therefore, when the start-up is performed from the standby position (HP) after the shading correction, the reading speed is reached at a position farther from the image front end (E) as the enlargement ratio is larger, and the image front end (E) is operated at a lower scanning speed. ). For this reason, the larger the enlargement ratio, the longer it takes to read the image, which poses a problem in improving the productivity in reading the image.
[0012]
There is also a problem of high image quality. As described above, when starting up from the standby position (HP), the productivity in image reading becomes a problem. Therefore, after performing shading correction at the standby position (HP), the robot moves to the startup position at high speed and waits. A sequence for performing the operation is also performed. However, the vibration generated when the scanning optical system is moved at a high speed deteriorates the image quality at the image front end (E), which is a problem in improving the image quality. Further, even if the shading correction for each scan is abolished, the image quality is degraded due to the fluctuation of the light amount in the job, and thus there is a problem in improving the image quality.
[0013]
Further, there is a problem of miniaturization of the device. Since the shading plate is arranged above the standby position (HP) on the same plane as the platen glass, in order to form the supporting member of the platen glass and the supporting member of the shading plate, the image leading end portion (E) is required. A space is required between the light source and the shading plate. For this reason, there is also a problem regarding miniaturization of the device.
[0014]
The present invention has been made in view of the above-described problems, and has as its object to realize an image reading apparatus that improves productivity in image reading without deteriorating image quality.
[0015]
[Means for Solving the Problems]
An image reading apparatus according to an aspect of the invention includes an optical unit that scans a document and photoelectrically converts a document image into an electric signal; a driving unit that scans and drives the optical unit; and a scan driving unit that scans the optical system unit with the driving unit. Control means for variably controlling a scanning speed when the scanning is performed, and correction means for performing shading correction on the electric signal using a shading member. The shading member includes a reading start position of the document image and the optical system. Between the stop position of the unit and a minimum required position for accelerating the optical system unit to a position at which a predetermined constant scanning speed according to the operation mode is obtained. is there.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an image reading device of the present invention will be described with reference to the accompanying drawings.
[0017]
(1st Embodiment)
FIG. 1 is a schematic cross-sectional view of an image forming apparatus provided with an image reading apparatus to which the first embodiment of the present invention is applied, and FIG. 2 is a diagram of the image reading apparatus to which the first embodiment of the present invention is applied. It is a figure showing a reading operation. Here, the configuration of the document feeder is the same as that of the conventional example, and the description is omitted.
[0018]
Next, the configuration of the image reading device will be described as follows.
A document (not shown) placed on the platen glass 1 is illuminated by an illumination lamp 6 arranged on a first mirror table 5 serving as a scanning optical unit. The light is reflected to the second and third mirror bases 8 by the first mirror 7 arranged at 5. Then, the light is reflected by the second mirror 9 and the third mirror 10, condensed by the lens 11, and formed into an image by the CCD sensor 12 as a reading element. Here, the above-described configurations 5 to 12 for scanning a document and photoelectrically converting the document image into an electric signal are referred to as an optical system unit.
[0019]
The first mirror base 5, the second mirror base 8, and the third mirror base 8 are supported by rails (not shown), and are movable in the direction of the arrow with the rotation of the optical drive motor 13. A stepping motor is used as the optical motor, and the first mirror table 5 and the first mirror table 5 are controlled by a pulley or a wire (not shown) so that the optical path length from the surface of the document table glass 1 to the CCD sensor 12 is always constant. The second and third mirror bases 8 are driven. As described above, by moving the first mirror table 5, the image information on the document surface is converted into an electric signal and transferred to the image forming apparatus.
[0020]
Next, the reading operation of the image reading apparatus will be described as follows.
At the time of the reduction scan, the first mirror base 5 waits at a position HP ′ near the standby position (HP) after performing the movement shading correction by the shading plate 14 arranged at the standby position (HP). In the present invention, since the moving shading correction method is used for the shading correction, the first mirror base 5 starts moving at the same time as the shading correction is started at the standby position (HP), and the image is moved in the direction of the image front end (E). The shading correction ends at the same time as stopping at the position of HP 'near the standby position (HP).
[0021]
Further, at the time of the same-size and enlargement scan, the image is moved to the position B ′ near the start-up start position (B) in the direction opposite to the image front end (E), and the shading plate 15 performs the movement shading correction. It stands by at the raising start position (B). Then, in response to the forward scan start signal, the first mirror base 5 rises up to the scan speed and starts reading from the image front end (E). Further, after reading is performed to the maximum image position (G) corresponding to the reading size, the fall is started, and the first mirror base 5 stops at an arbitrary stop position (H). Here, the stop position (H) differs according to the magnification, and in the present embodiment, as shown in FIG. 2, the stop is at H2 at the time of reduced scan and at H1 at the same size / enlarged scan.
[0022]
Subsequently, the back scan is started, and the first mirror base 5 stops at the standby position (HP) during the reduction scan. On the other hand, the first mirror base 5 stops at the position B 'during the same-size and enlarged scan. Then, in the case of continuous scanning, after performing the movement shading correction again, reading is performed in the same sequence as described above.
[0023]
(Second embodiment)
FIG. 3 is a schematic cross-sectional view of an image forming apparatus provided with an image reading apparatus to which the second embodiment of the present invention is applied, and FIG. 4 is a reading view of the image reading apparatus to which the first embodiment of the present invention is applied. It is a figure for explaining operation. Here, the configuration of the document feeder is the same as that of the conventional example, and the description is omitted.
[0024]
Next, the configuration of the image reading device will be described as follows.
A document (not shown) placed on the platen glass 1 is illuminated by an illumination lamp 6 arranged on a first mirror table 5 serving as a scanning optical unit. The light is reflected to the second and third mirror bases 8 by the first mirror 7 arranged at 5. Then, the light is reflected by the second mirror 9 and the third mirror 10, condensed by the lens 11, and formed into an image by the CCD sensor 12 as a reading element.
[0025]
The first mirror base 5, the second mirror base 8, and the third mirror base 8 are supported by rails (not shown), and are movable in the direction of the arrow with the rotation of the optical drive motor 13. A stepping motor is used as the optical motor, and the first mirror table 5 and the first mirror table 5 are controlled by a pulley or a wire (not shown) so that the optical path length from the surface of the document table glass 1 to the CCD sensor 12 is always constant. The second and third mirror bases 8 are driven. As described above, by moving the first mirror table 5, the image information on the document surface is converted into an electric signal and transferred to the image forming apparatus.
[0026]
Next, the reading operation of the image reading apparatus will be described as follows. The shading plate 14 according to the present embodiment is adhered so as to be sandwiched between the platen glass 1 and a double-sided tape attached to a document size indicator (not shown). The width D of the shading plate 14 satisfies the relationship of D ≧ A + | B−C | (the shading width required for shading is A, the minimum start position is B, and the maximum start position is C). Further, | EB | ≧ A1, | FC | ≧ A2 (E is the position of the image front end, F is the glass end position on the image front end E side, and A1 is the image front end E side width. Are arranged so that the width on the opposite side of the image front end portion E satisfies A2).
[0027]
At the time of the maximum reduction scan, the first mirror base 5 waits after performing shading correction by the shading plate 14 arranged at the standby position C (HP). Further, at the time of the maximum enlargement scan, it moves to the start-up position (B) and waits after performing shading correction by the shading plate 14. Here, the start-up standby position differs depending on the magnification, and in the present embodiment, the standby is performed between C and B as the reduction-to-enlargement is performed.
[0028]
Then, in response to the forward scan start signal, the first mirror base 5 rises up to the scan speed and starts reading from the image front end (E). Further, after reading is performed to the maximum image position (G) corresponding to the reading size, the fall is started, and the first mirror base 5 stops at an arbitrary stop position (H). Here, the stop position (H) differs depending on the magnification ratio, and in the present embodiment, the stop position (H) stops between H2 and H1 as the size decreases and expands.
[0029]
Subsequently, the back scan is started, and at the time of the maximum reduction scan, the first mirror base 5 stops at the standby position C (HP). On the other hand, at the time of the maximum enlargement scan, the first mirror base 5 stops at the position B. Here, the stop position differs depending on the magnification, and in the present embodiment, the stop is performed between C and B as the reduction proceeds to the enlargement. In the case of continuous scanning, after performing shading correction again, reading is performed in the same sequence as described above.
[0030]
According to the embodiment of the present invention, the shading plate 15 is moved between the reading start position (E) of the document image and the stop position (HP) of the optical system unit at a predetermined constant scanning speed according to the operation mode. Since the optical system unit is arranged at the minimum necessary position for accelerating the optical system unit to the position, the productivity in image reading can be improved without deteriorating the image quality. In particular, in the image reading at the time of the enlargement scan, as can be seen by comparing FIG. 2 and FIG. 6, the section between the position at which the predetermined constant scanning speed according to the operation mode is reached and the reading start position (E) is reduced. By doing so, productivity in reading an image can be improved.
[0031]
Further, when the optical system unit is driven in the continuous scan mode, the back scan stop position of the optical system unit in the Nth scan is set near the rising position of the optical system unit in the (N + 1) th scan. Since the shading correction for each scan can be performed without driving the image data at high speed, it is possible to prevent image quality deterioration at the reading start position (E) of a document image due to vibration or image quality deterioration due to light amount fluctuation in a job.
[0032]
In addition, the width D of the shading plate 14 in the driving direction of the optical system unit is represented by D ≧ A + | B−C | (A is a shading width required for shading, B is a minimum start start position, and C is a maximum start start position. ), Shading is performed at the shortest position from the reading start position (E) of the original image according to the magnification, and reading can be started in the shortest time. This solves the problem that the larger the enlargement ratio, the longer it takes to read an image, and the productivity in image reading can be improved.
[0033]
Further, the shading plate 14 is placed on the platen glass | E-B | ≧ A1, | FC− ≧ A2 (E is a reading start position of a document image, F is a glass end position on the reading start position E side, A1 Are arranged so as to satisfy the reading start position E side width and A2 is the width on the opposite side of the reading start position E), so that the shading plate 14 is supported by the platen glass 1 so that the image leading end portion (E) and the shading plate are supported. Since there is no need to provide a support member for supporting the shading plate in between, the size of the apparatus can be reduced.
[0034]
Examples of embodiments of the present invention are listed below.
[0035]
Embodiment 1 An optical system unit that scans a document and photoelectrically converts the document image into an electric signal,
Driving means for scanning and driving the optical system unit,
Control means for variably controlling a scanning speed when scanning and driving the optical system unit by the driving means,
Correction means for shading correction of the electric signal using a shading member,
The shading member is between a reading start position of the document image and a stop position of the optical system unit, and accelerates the optical system unit to a position where a predetermined constant scanning speed according to an operation mode is obtained. An image reading device, wherein the image reading device is arranged at a minimum necessary position.
[0036]
[Embodiment 2] When the driving unit drives the optical system unit in the continuous scan mode, the back scan stop position of the optical system unit in the Nth scan is set to the rising position of the optical system unit in the (N + 1) th scan. The image reading device according to the first embodiment, wherein the image reading device is located near the image reading device.
[0037]
[Embodiment 3] Assuming that a shading width required for shading is A, a minimum rising start position is B, and a maximum rising start position is C, the width of the optical system unit in the driving direction of the optical unit by the shading member. 3. The image reading apparatus according to claim 1, wherein D satisfies D ≧ A + | B−C |.
[0038]
[Embodiment 4] The reading start position of the document image is E, the glass end position on the reading start position side is F, and the shading width A is determined by the reading position and the reading start position side width A1 and the reading start position. The shading member is disposed on the platen glass so as to satisfy | EB | ≧ A1 and | FC | ≧ A2 in relation to the width A2. 4. The image reading device according to 3.
[0039]
【The invention's effect】
According to the present invention, it is possible to improve productivity in reading an image without deteriorating image quality. In particular, in image reading at the time of enlarged scanning, the productivity can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an image forming apparatus provided with an image reading device to which a first embodiment of the present invention has been applied.
FIG. 2 is a diagram illustrating a reading operation of the image reading apparatus to which the first embodiment of the present invention has been applied.
FIG. 3 is a schematic cross-sectional view of an image forming apparatus provided with an image reading device to which a second embodiment of the present invention has been applied.
FIG. 4 is a diagram illustrating a reading operation of an image reading apparatus to which a second embodiment of the present invention has been applied.
FIG. 5 is a schematic sectional view of an image forming apparatus provided with a conventional image reading device.
FIG. 6 is a diagram showing a reading operation in a conventional image reading device.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 original table glass 3 original transport belt 4 original transport device 5 first mirror table 6 illumination lamp 7 first mirror 8 second and third mirror tables 9 second mirror 10 third mirror 11 lens 12 CCD sensor 13 optical drive motor 14, 15 Shading plate 24 Pickup roller 25 Feed separation section 26, 27 Transport roller pair 28 Paper discharge tray 29 Paper discharge roller pair 30 Document 31 Document tray

Claims (1)

An optical unit that scans the original and photoelectrically converts the original image into an electric signal;
Driving means for scanning and driving the optical system unit,
Control means for variably controlling a scanning speed when scanning and driving the optical system unit by the driving means,
Correction means for shading correction of the electric signal using a shading member,
The shading member is between a reading start position of the document image and a stop position of the optical system unit, and accelerates the optical system unit to a position where a predetermined constant scanning speed according to an operation mode is obtained. An image reading device, wherein the image reading device is arranged at a minimum necessary position.

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