JPH09139813A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a local temperature rise in the case of discriminating an original color by a sheet through system. SOLUTION: The device moves a 1st mirror 324 of a scanner section 320 to a position at the end close to an entry of an original G or an inverted original G', and when a document feeder 330 feeds the original G or the inverted original G' to an original platen 321 and the original passes the position of the 1st mirror 324, the device reads an original image and uses an original discrimination means to discriminate whether the original is a black/white original or a color original. In this case, a lamp voltage control means reduces a lamp voltage at discrimination of an original color more than a lamp voltage of an exposure lamp 322 in the copy operation state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a color copying machine or a color facsimile, and more particularly to an image forming apparatus having a function of discriminating a black-and-white original or a color original.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus,
Prior arts having a function of discriminating a document color include, for example, Japanese Patent Publication No. 6-81235 and Japanese Patent Laid-Open No. 63-149657.
No. 6,086,045. In these prior arts, prescanning is performed in order to automatically determine whether a document is a color document or a black and white document prior to the copying operation. However, in these prior arts, there is a drawback that the time required for copying becomes long because pre-scanning is necessary before the copy operation in order to determine whether the original is a color original or a black-and-white original. is there. This drawback is a problem when using an ADF (Automatic Document Feeder) which requires high copy efficiency.

As a technique for solving this drawback, there is a technique disclosed in Japanese Utility Model Laid-Open No. 5-4665. That is, when an original is conveyed by the ADF, the carriage of the exposure device is moved so that the reading position is near the entrance of the original conveyance, and in this state, the original is read while the original is being conveyed to judge the original color, Then, a so-called sheet-through method is performed in which a copy operation is performed in a normal state with respect to a document stationary at a fixed position. According to this sheet-through method, it is not necessary to perform a prescan for determining the document color, and therefore the copying time can be shortened.

[0004]

Many color copying machines use a halogen lamp as a light source for reading. Therefore, as disclosed in Japanese Utility Model Laid-Open No. 5-4665, stopping the exposure device at one place for the purpose of determining the document color causes a local temperature rise of the document table, that is, the contact glass. . Therefore, the color material (color toner, thermal transfer ink, etc.) of the original is softened, and the ADF
It is causing a jam.

[0005]

According to the first aspect of the present invention,
The first mirror of the scanner unit is provided with an end portion near the entrance of the original document or the reverse original document, which has a document feeder, and feeds a reverse original document in the case of a mixed original of black and white and color or a double-sided original document. When the original document or the reverse original document is fed to the original table by the document feeder and passes through the first mirror position, the original image is read to determine whether it is a monochrome original or a color original. In the image forming apparatus, which has means for selecting the monochrome mode or the color mode as the image forming mode based on the discrimination result by the document discriminating means, the lamp voltage for discriminating the original color is more than the lamp voltage for the exposure lamp in the copying operation. It is characterized in that a lamp voltage control means for controlling so as to reduce the voltage is provided.

According to a second aspect of the present invention, a white reference plate for shading correction and a lamp voltage control means for controlling so as to reduce the lamp voltage at the time of discriminating the original color from the lamp voltage of the exposure lamp at the copying operation are provided. Provided.

According to a third aspect of the present invention, there is provided a first high reflectivity
When a copy with a high lamp voltage is provided, a white reference plate having at least two reference portions having different reflectances, which are the reference portion and the second and subsequent reference portions having a lower reflectance than the first reference portion, is provided. The shading correction is performed by the first reference portion having a high reflectance, and the shading correction is performed by the second and subsequent reference portions having a low reflectance when an original having a low lamp voltage is discriminated.

According to a fourth aspect of the present invention, a white reference plate having a uniform reflectance in the main scanning direction and a reflectance continuously changing in the sub scanning direction is provided, and shading correction is performed at a position with high reflectance when copying with a high lamp voltage. When the original having a low lamp voltage is discriminated, the shading correction is performed at the position where the reflectance is low.

According to a fifth aspect of the invention, a white reference plate having a uniform reflectance on the entire surface is provided so as to be inclined with respect to the document table, and when copying with a high lamp voltage, shading is performed at a position where the distance from the first mirror is short. When the original having a low lamp voltage is determined, the shading correction is performed at a position where the distance from the first mirror is long.

[0010]

An embodiment of the present invention will be described with reference to the drawings. The overall structure of the color copying machine will be described with reference to FIG. First, the scanner unit 320 is arranged on the printer unit 300, and the scanner unit 320
A document feeder 330 is arranged on the above.
The scanner unit 320 includes an exposure lamp 322 for illuminating the document G set on the document table 321, a reflection plate 323, and a first plate.
Mirror 324, second and third mirror 325, lens 32
6. It has a CCD (solid-state image sensor) 327 for reading an image. Also, beside the document table 321, the document feeder 330 serves as a reference when setting the document G.
A document scale 328 is provided to serve as a document feed guide when the document is used. A white reference plate 500 (see FIGS. 5 and 6) is provided between the original scale 328 and the original table 321. The white reference plate 500 is the first with high reflectance.
Reference portion 500a and second reference portion 500b having low reflectance
It consists of The second reference portion 500b may set a plurality of other regions by the region where the reflectance is changed.

The exposure lamp 322, the reflection plate 323, and the first mirror 324 move together along the document table 321, and the second and third mirrors 325 also move at half the speed thereof and terminate. Then, the state shown by the two-dot chain line is shown. At this time, the light beam H that scans the original G is input to the CCD 327 through the lens 326 through the path indicated by the alternate long and short dash line in FIG. The CCD 327 reads an image of the document G based on the light beam H, and is configured so that this image information is image-processed by the image processing unit 103 (see FIG. 1) and output to the printer unit 300.

Photosensitive drum 3 in printer unit 300
Around 01, a charging unit 302, a laser exposure unit 303, a black developing unit 304, color developing units 305, 306, 307 for each color of yellow, magenta, and cyan, and a cleaning unit 308 are arranged. The path 311 of the recording paper S from the paper feed cassette 309 to the paper output tray 310 includes:
A transfer unit 312 for transferring the black and color images formed on the photosensitive drum 301 and a fixing unit 313 are provided, and the image of the original G is printed on the recording paper S.

The document feeder 330 has a document table 331 on which a document G is placed, and the document table 3
In front of 31, a calling lever 332 and a calling roller 333 that prompt the user to feed the original G by operating the start key, a separating belt 334 and a separating roller 335 that feed only one lowermost sheet of the original G
Are arranged. These portions include a document detection sensor 336, a registration detection sensor 337 for detecting a document size and a document width detection sensor 337, and a pulse generator 33.
8, a document length detection sensor 339 is provided.

A transport belt 340 for transporting the fed document G is placed on the document table 321 by a driving roller 34.
1, a fixed roller 342 and a driven roller 343, and a plurality of pressure rollers 344 are arranged on the conveyor belt 340 to press the document G against the document table 321.

The transport belt 340 is driven when the document G is fed, and is stopped when the trailing edge of the document G passes the sensor 337 and the transport motor reaches a predetermined pulse, and the document G is moved to a designated position. set. A turn guide 345, a discharge roller 346, and a discharge tray 347 are provided at the end of the document table 321 so as to discharge the document G after the exposure processing. Further, inside the turn guide 345, in order to transport the two-sided inverted original G ′ to the original platen 321 again,
48, an inversion switching claw 349 is provided.

The control system of the present invention will be described with reference to FIG. First, the system control unit 100 receives an operation signal from the operation display unit 101. A drive signal is output from the system control unit 100 to the document feeder 330 to feed the original G or the inverted original G '. Also,
A driving signal is output to the scanner driving unit 102 and an exposure lamp lighting signal is output to the scanner unit 320 to start a scanning operation.

FIG. 4 shows a block diagram of a signal system of the scanner section 320. The scanner control unit 501 that receives a signal from the system control unit 100 operates the lamp regulator 503 via the D / A converter 502 to turn on the lamp 322 with the lamp voltage during copying. Next, the carriage is moved by the motor 504 of the scanner driving unit 102, and as shown in FIG. 5B, the shading correction is performed by the first reference portion 500a having high reflectance of the white reference plate 500, and the copying operation is started. .

The light from the scanner section 320 causes the CCD 327
The image information read in is input to the image processing unit 103 and various processing is performed, and the image processing unit 103 further outputs the image information to the laser exposure unit 303. On the other hand, a control signal is output from the system control unit 100 to the printer unit 300, and the printer unit 300 operates.

Further, in the above control system, the signal from the document detection sensor 336 of the document feeder 330, and the reversal signal of the reversal document G ′ in the case of a double-sided document are input to the system control unit 100. When the signal from the document detection sensor 336 is input, the system control unit 100 outputs a drive signal to the scanner drive unit 102 to expose the exposure lamp 322, the reflection plate 323, the first mirror 324, the second and third mirrors 325.
2 to move the first mirror 324 to the home position A as shown in FIG. 2, turn on the exposure lamp 323 at a low voltage for original color discrimination, and reflect the white reference plate 500 at the position shown in FIG. 5 (a). After the shading correction is performed by the second reference portion 500b having a low rate, it is moved to the position B at the end of the fixed roller 342 where scanning is possible and stopped, and the exposure lamp 322 is turned on.

When an inverted signal of the inverted original G'is input, the first mirror 324 and the like are moved to a position C near the driven roller 343 where the inverted original G'returns to the original table 321 again as shown in FIG. Similarly, the exposure lamp 322 is turned on.

When a document or color document discrimination signal is input from the image processing unit 103, the system control unit 100
Select a monochrome or color mode according to the document color.
Further, after selecting the mode, the system control unit 100
The scanner driving unit 102 outputs a control signal to return the first mirror 324 and the like to the original home position A.

As shown in FIG. 4, the output from the CCD 327 is sent to a shading correction unit 508 through an amplifier 505 and an A / D converter 507, and shading correction data at the time of copying is stored in a memory I 509 and the original document is read. The shading correction data at the time of determination is stored in the memory II 510. Further, the signal from the scanner control unit 501 causes D
A / D converter 507 via A / A converter 506
Is used to adjust the R, G, B balance and the like. The signal processing of the CCD 327 is omitted because it is the same as O or E (even number signal) of R, G, and B.

Even if there is an output value due to a difference in lamp voltage, a shading shape and a balance (not shown) of R, G, and B, the scanner data at the time of copying and at the time of original color discrimination have the same level after shading correction. Has become. As a matter of course, since the CCD output is smaller at the time of original color discrimination than at the time of copying, the S / N ratio is inferior. However, it is sufficient to distinguish between chromatic and achromatic colors.

Next, the operation of this embodiment will be described. First, when a mixed black-and-white and color original G is placed and set on the original table 331 of the document feeder 330, a detection signal from the original detection sensor 336 is input to the system control unit 100. Therefore, the scanner driving unit 102 causes the first mirror 324 of the scanner unit 320 to
As shown by the solid line in FIG. 2, the position is moved to the start position B where scanning is possible, and the exposure lamp 322 is turned on to enable scanning.

After that, when the start key on the operation display unit 101 is operated, the document feeder 330 is operated and the document G is sent onto the document table 321 by the separation roller 335 and the conveyor belt 340. At this time, while the conveyed document G passes through the position B, it is automatically scanned by the exposure lamp 322, the first mirror 324, etc.
The image of the document is read by 327 and the image processing unit 10
At 3, a black-and-white original or a color original is discriminated. Then, a predetermined image forming mode is selected by the system control unit 100 based on the determination result. That is, when the document G is conveyed by the document feeder 330, the color of the document is determined, and an appropriate mode is selected. After that, the first mirror 324 and the like move to return to the original home position A, and the normal scanning operation is performed.

In the case of a double-sided original, the first mirror 324 and the like move to the end position C as shown by the chain double-dashed line in FIG. Therefore, when the reverse original G ′ that is reversed and fed by the reverse roller 348 and the reverse switching claw 349 is sent to the original table 321 again and passes through the position C, the color of the reverse original G ′ is similarly changed. Then, the appropriate mode is selected.

When the mirror becomes dirty as time passes, the lamp voltage rises in order to obtain a CCD output equivalent to that at the initial stage. As a coping method in this case, FIG.
By performing the shading correction as in FIG. 5B as shown in FIG. 5B, an image equivalent to the initial image can be obtained. At this time, the shading correction position at the time of determining the document color is as shown in FIG.
In, the position is changed from the initial D to the position E (direction in which the reflectance of the white reference plate decreases). In this way, the scanner driver 1
02 can be controlled to keep the lamp voltage constant at the time of document discrimination.

In the white reference plate 500 in FIG. 6, the area 500a 'at the time of copying is the same as the first reference section 500a, and the area 500b' for the document color discrimination is the area 50.
Since it is inclined with respect to the original table 321 with the same reflectance as 0a ′, the reflectance when viewed from the original table 321 is the same in the main scanning direction, but from D to E in the sub scanning direction. The reflectance gradually decreases as it goes to.

Further, when the area 500a 'during copying and the area 500b' during original color discrimination are formed on the same surface, the reflectance changes uniformly in the main scanning direction and continuously changes in the sub-scanning direction. That is, that is, continuous gradation (gradation) is made in the sub-scanning direction, shading correction is performed at a position with high reflectance when copying with a high lamp voltage, and shading is performed at a position with low reflectance when a document with a low lamp voltage is determined. To do so.

[0030]

According to the first aspect of the present invention, the first mirror of the scanner unit is provided with the document feeder, and before feeding a mixed original of black and white and color or a reverse original in the case of a double-sided original. To the position of the end near the entrance of the original or the reverse original, and the original or the reverse original is fed to the original table by the document feeder and passes through the position of the first mirror to display the original image. In an image forming apparatus, which is equipped with a document discriminating means for reading and discriminating a black-and-white document or a color document, and which selects a black-and-white mode or a color mode as an image forming mode based on a discrimination result by the document discriminating device, exposure during a copying operation Since the lamp voltage control means for controlling so that the lamp voltage at the time of document color discrimination is lower than that of the lamp is provided, When the lamp is stationary to determine the original color with the sheet-through scheme, it is possible to reduce the local temperature rise of the platen, caused by the softening of the coloring material A
The cause of DF jam can be eliminated.

According to a second aspect of the present invention, a white reference plate for shading correction and a lamp voltage control means for controlling so as to reduce the lamp voltage at the time of original color discrimination as compared with the lamp voltage of the exposure lamp at the copying operation are provided. Therefore, the scanner output during copying can be made constant while reducing the local temperature rise of the document table.

According to a third aspect of the present invention, there is provided the first aspect of high reflectance.
When a copy with a high lamp voltage is provided, a white reference plate having at least two reference portions having different reflectances, which are the reference portion and the second and subsequent reference portions having a lower reflectance than the first reference portion, is provided. Since the shading correction is performed by the first reference portion having a high reflectance and the shading correction is performed by the second and later reference portions having a low reflectance when the original having a low lamp voltage is discriminated, the lamp voltage of the exposure lamp is lowered. The change in color temperature and the change in shading shape at that time can be corrected by performing shading correction with a white reference plate having a reflectance lower than that when the lamp voltage is raised, and the error rate of discriminating the original color can be suppressed to a low level.

According to a fourth aspect of the present invention, a white reference plate having a uniform reflectance in the main scanning direction and a reflectance continuously changing in the sub-scanning direction is provided, and shading correction is performed at a position with high reflectance when copying with a high lamp voltage. Since the shading correction is performed at the position where the reflectance is low when discriminating an original with a low lamp voltage, even if the lamp voltage during copying increases due to dirt on the mirror or the like, white with a low reflectance is discriminated when discriminating the original color. Since the shading correction is performed by the reference plate, the rise of the lamp voltage can be prevented.

According to a fifth aspect of the present invention, a white reference plate having a uniform reflectance on the entire surface is provided so as to be inclined with respect to the document table, and when copying with a high lamp voltage, shading is performed at a position where the distance from the first mirror is short. Since the correction is performed and the shading correction is performed at the position where the distance from the first mirror is long when the original having a low lamp voltage is discriminated, it is easy to manufacture the white reference plate whose reflectance continuously changes in the sub-scanning direction. It is something.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a control method of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view of a main part of the document feeder showing an operation state at the time of document color discrimination.

FIG. 3 is a vertical sectional side view showing an outline of the entire color copying machine.

FIG. 4 is a block diagram illustrating an example of a signal system of a scanner unit.

FIG. 5A is a partial vertical cross-sectional side view showing a shading correction state at the time of document color discrimination, and FIG. 5B is a partial vertical side view showing a shading correction state at the time of copying.

FIG. 6A is a partial vertical cross-sectional view showing another example of the shading correction state at the time of document color discrimination, and FIG. 6B is a partial longitudinal side view showing the other example of the shading correction state at the time of copying. It is a vertical side view.

7A is a graph showing a scanner output at the time of copying before shading correction, FIG. 7B is a graph showing a scanner output at the time of copying after shading correction, and FIG. 7C is at the time of document color discrimination before shading correction. And (d) is a graph showing the scanner output at the time of determining the document color after the shading correction.

[Explanation of symbols]

 320 Scanner 321 Document Plate 322 Exposure Lamp 324 First Mirror 330 Document Feeder G Document G'Reversed Document

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03G 15/01 112 G03G 15/01 112A 15/043 21/00 378 15/04 15/04 120 21 / 00 378

Claims (5)

[Claims] 1. A first mirror of a scanner unit is provided with a document feeder, and a first mirror of a scanner unit is used to feed a reversed original in the case of a mixed original of black and white and color or a double-sided original. When the document or the reverse document is fed to the document table by the document feeder and passes through the position of the first mirror by moving to the end position near the entrance, the document image is read to determine whether it is a monochrome document or a color document. In an image forming apparatus that includes a document discriminating unit that discriminates between the original color and the lamp voltage of the exposure lamp during a copying operation, in an image forming apparatus that selects a monochrome mode or a color mode as an image forming mode based on the discrimination result by the document discriminating unit. An image forming apparatus comprising: a lamp voltage control means for controlling so as to reduce a lamp voltage at the time of determination. 2. A first mirror of the scanner unit is provided with a document feeder, and the first mirror of the scanner section is used to feed the reverse original in the case of a mixed original of black and white and color or a double-sided original. When the document or the reverse document is fed to the document table by the document feeder and passes through the position of the first mirror by moving to the end position near the entrance, the document image is read to determine whether it is a monochrome document or a color document. In an image forming apparatus for selecting a black-and-white mode or a color mode as an image forming mode based on a determination result by the document determining means, a white reference plate for shading correction and an exposure lamp for copying operation are provided. Lamp voltage control means for controlling so as to reduce the lamp voltage at the time of document color discrimination compared to the above lamp voltage. An image forming apparatus comprising: 3. A first mirror of the scanner unit is provided with a document feeder, and the first mirror of the scanner section is used to feed the original or the reverse original before feeding a mixed original of black and white and color or a reverse original in the case of a double-sided original. When the document or the reverse document is fed to the document table by the document feeder and passes through the position of the first mirror by moving to the end position near the entrance, the document image is read to determine whether it is a monochrome document or a color document. In an image forming apparatus that includes a document discriminating unit that discriminates between the original color and the lamp voltage of the exposure lamp during a copying operation, in an image forming apparatus that selects a monochrome mode or a color mode as an image forming mode based on the discrimination result by the document discriminating unit. A lamp voltage control means for controlling so as to reduce the lamp voltage at the time of discrimination is provided, and the first reference portion having a high reflectance and the first reference portion are provided. Second, which has a lower reflectance than the reference part of No. 1
A white reference plate having at least two reference portions having different reflectances from the subsequent reference portions is provided, and when copying with a high lamp voltage, the shading correction is performed by the first reference portion having a high reflectance. An image forming apparatus characterized in that when a document is low, the shading correction is performed by the second and later reference parts having a low reflectance. 4. A first mirror of the scanner unit is provided with a document feeder, and the first mirror of the scanner section is used to feed the original document or the reverse original document before feeding the original document in which black and white and color are mixed or a double-sided original document. When the document or the reverse document is fed to the document table by the document feeder and passes through the position of the first mirror by moving to the end position near the entrance, the document image is read to determine whether it is a monochrome document or a color document. In an image forming apparatus that includes a document discriminating unit that discriminates between the original color and the lamp voltage of the exposure lamp during the copying operation in the image forming apparatus that selects the monochrome mode or the color mode as the image forming mode based on the discrimination result by the document discriminating unit. A lamp voltage control means for controlling so as to reduce the lamp voltage at the time of determination is provided so that the lamp voltage is uniform in the main scanning direction and continuous in the sub scanning direction. By providing a white reference plate whose reflectance changes continuously, shading correction is performed at a position with a high reflectance when copying with a high lamp voltage, and shading correction is performed at a position with a low reflectance when discriminating an original with a low lamp voltage. An image forming apparatus characterized by the above. 5. A first mirror of the scanner unit is provided with a document feeder, and a first mirror of the scanner unit is used to feed the original or the inverted original before feeding the original mixed with black-and-white and color or a double-sided original. When the document or the reverse document is fed to the document table by the document feeder and passes through the position of the first mirror by moving to the end position near the entrance, the document image is read to determine whether it is a monochrome document or a color document. In an image forming apparatus that includes a document discriminating unit that discriminates between the original color and the lamp voltage of the exposure lamp during a copying operation, in an image forming apparatus that selects a monochrome mode or a color mode as an image forming mode based on the discrimination result by the document discriminating unit. A lamp voltage control means for controlling the lamp voltage at the time of discrimination is provided, and a white reference plate with uniform reflectance on the entire surface is placed in front. Inclined with respect to the manuscript table,
When copying with a high lamp voltage, shading correction is performed at a position where the distance from the first mirror is short, and when a document with a low lamp voltage is determined, shading correction is performed at a position where the distance from the first mirror is long. Image forming apparatus.