JP2001077990A - Image reader and image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original reader, where a read time of an image of an original can be reduced by efficiently adjusting white balance of a CCD reading the image of the original. SOLUTION: When an original read section detects that an original cover 3 is open, the original read section starts black level correction and white level correction of a CCD. Accordingly, since a read preparatory processing is already been started when a user operates original image read start after finishing setting of an original to an original platen, the time taken until real image read processing is started can be reduced, the result that the time required for reading an image of the original can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading a document image by detecting reflected light from the document, and an image forming apparatus for forming a document image read by the image reading apparatus on a sheet.

[0002]

2. Description of the Related Art Conventionally, an image reading section for reading a document image by irradiating a document placed on a document table with a light source and detecting reflected light from the document by a CCD has been provided. 2. Description of the Related Art An image forming apparatus (copier) for forming (copying) an original image on paper has been put to practical use. In a conventional general image reading apparatus, a halogen lamp is used as a light source. However, since power consumption is large, a fluorescent lamp with low power consumption has recently been used. However, fluorescent lamps have poor light rise characteristics in low temperature environments.
There is a problem that it takes a long time to stabilize the quantity of light that can be copied after the light is turned on, which causes a reduction in work efficiency (it takes a long time until the completion of copying). A technique has been proposed in which a fluorescent lamp is always kept warm by a heater so that it can be obtained. However, when this technique is applied, the effect of reducing the power consumption, which is the original purpose of using the fluorescent lamp, is reduced (the above-mentioned heat keeping is not used). Requires power.)

[0003] Therefore, a function is provided for detecting signs that the apparatus body is to be used, and when the signs are detected, the heater is turned on to heat the fluorescent lamp, so that when a copy switch is operated, the original image is read. A technique has been proposed in which a stable light quantity is obtained as possible (Japanese Patent Laid-Open No. 9-15755). This publication discloses, as a function of detecting a precursor of the use of the apparatus main body, for example, detecting the presence or absence of a user with an infrared sensor, and detecting opening of a document table cover.

This technique is a technique for smoothly starting a reading operation of a document image in an image forming apparatus. If the image forming operation for forming the read document image on a sheet cannot be started smoothly, the reading operation is performed. , The time required until the copying operation is completed cannot be reduced efficiently. For example, in the case of an image forming apparatus that deflects and scans a laser beam on a photoreceptor using a polygon mirror, even if the reading operation of the original image is performed smoothly, the image forming operation is performed until the rotation of the polygon mirror is stabilized. Since it cannot be started, the time until the copying is completed becomes longer as a result. Therefore, a technique has been proposed in which the image forming operation can be started smoothly by starting the rotation of the polygon mirror when the opening of the document table cover is detected (Japanese Patent Laid-Open No. 9-25122).
No. 8).

[0005]

By the way, the copy processing time in the image forming apparatus (the time from when the copy switch is operated until the sheet on which the image is formed is discharged).
Is the image preparation time / image formation preparation time (preparation time)
And the actual reading time / actual image forming time (actual operation time). However, the above-described image reading preparation time includes a time for executing a white balance including black level correction, white level correction, and shading correction of the CCD. Techniques for shortening have not been proposed so far.

SUMMARY OF THE INVENTION It is an object of the present invention to read a document image.
An object of the present invention is to provide a document reading apparatus in which the time required for reading a document image is reduced by efficiently performing the white balance of a CD.

Another object of the present invention is to provide an image forming apparatus in which the time required for copying an original image is reduced by applying the original reading apparatus and efficiently performing a print preparation process. .

[0008]

An original reading apparatus and an image forming apparatus according to the present invention have the following arrangements to solve the above-mentioned problems.

(1) In an image reading apparatus provided with a light source for irradiating a document set on a document table and a CCD for reading a document image by detecting reflected light from the document, the document table is covered. Opening / closing detecting means for detecting opening / closing of the platen cover and reading preparation processing such as black level correction of the CCD are started when the opening / closing detecting means detects the opening of the platen cover.

In this configuration, when the opening / closing detecting means detects that the platen cover is opened, a reading preparation process (white balance) such as black level correction of the CCD is started. The original platen cover is opened in most cases because the user sets the original on the original platen.When the original image reading operation is performed after the original is set, the reading preparation process is already started. (The reading preparation process is started when the document platen cover is opened.) Therefore, the time until the actual image reading process is started can be reduced, and as a result, the time required for reading the document image can be reduced. Can be shortened.

(2) The CCD has a non-image area into which reflected light from the original does not enter when reading the original image, and executes the black level correction in the non-image area.

In this configuration, the black level correction is performed using the non-image area where the reflected light from the document does not enter when reading the document image, so that the black level correction can be performed without turning off the light source.

(3) The reading preparation processing includes white level correction of the CCD, and executes the white level correction in an image area other than a non-image area of the CCD.

With this configuration, since the black level correction and the white level correction can be performed simultaneously, the time required for the read preparation processing can be reduced.

(4) Black / white level correction means for repeating the black level correction and white level correction at regular intervals when the platen cover is closed, and black level correction executed with the opening of the platen cover as a trigger A stray light occurrence determining means for determining the presence or absence of the influence of the stray light based on the detected value of the black level correction and the detection value of the previous black level correction; and To read the original image.

In this configuration, the black level correction of the CCD is started with the opening of the platen cover as a trigger.
There is a possibility that disturbance light (stray light) enters the camera and proper black level correction cannot be performed. For this reason, when the platen cover is closed, the above black level correction and white level correction are repeatedly performed at regular intervals, and if the appropriate black level correction cannot be performed due to stray light, the result of the previous black level correction is used. The original image is read by utilizing this.

(5) The stray light occurrence judging means judges the presence or absence of the influence of the stray light based on the detected value of the white level correction executed with the opening of the document table cover as a trigger and the detected value of the previous white level correction. When it is determined that there is an effect due to the stray light, a document image is read using the result of the previous white level correction.

In this configuration, the white level correction of the CCD is started by triggering the opening of the platen cover.
If the ambient light (stray light) enters the camera, the white level correction cannot be performed properly. Therefore, the black level correction and the white level correction are repeated at predetermined time intervals when the cover of the document table is closed. When the level correction cannot be performed, the original image is read using the result of the previous white level correction.

(6) A document feeder for conveying a set document to a reading position of a document image, a light source for irradiating the document conveyed to the reading position, and detecting reflected light from the document. An image reading device having a CCD for reading a document image, a document set detecting means for detecting whether or not a document is set in the document feeding portion; and Then, reading preparation processing such as black level correction is started for the CCD.

In this configuration, when a document is set on the document feeder, the black level correction of the CCD is started, so that the same effect as the above (1) can be obtained. The act of setting a document on the document feeder is almost always a preparation operation performed by a user to read a document image on the document.

(7) An image forming apparatus comprising the image reading device according to any one of (1) to (6), wherein the image reading device forms an original image read by the image reading device on a sheet. The printing preparation process is started according to the start timing of the reading preparation process in the apparatus.

In this configuration, the printing preparation processing is started in accordance with the start timing of the reading preparation processing which is started when the opening of the document table cover or the setting of the document in the document feeder is detected. The time required until the image forming process is started can be reduced (the time required for the copying process can be reduced).

[0023]

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. A document table cover 3 that covers a document table 2 on which a document is placed is attached to the upper surface of the image forming apparatus 1 so as to be freely opened and closed with respect to the main body. The document table 2 is a platen glass, and an image reading unit 4 (an image reading device according to the present invention) that reads a document image placed on the document table below the platen glass (document table 2).
Is arranged. Below the image reading unit 4, there is provided an image forming unit 5 that forms an image on a sheet picked up from the sheet feeding unit 6 and taken in the main body, and discharges the sheet to the sheet discharging unit 7.

The image reading section 4 includes a light source 11 for irradiating a document.
And three mirrors 13 and lenses 14 for guiding the reflected light from the document to the CCD 12. Image forming unit 5
A semiconductor laser 21 for irradiating a laser beam in accordance with a document image read by the image reading unit 4;
And an optical system for guiding the laser light emitted from the light source 1 to the photosensitive drum 31. In this figure, a polygon mirror 22 and two mirrors 23 and 24 are shown as an optical system (a lens system such as an fθ lens is not shown). As is well known, a main charger 32 for charging the photosensitive drum 31 to a predetermined potential is provided around the photosensitive drum 31, and an electrostatic latent image formed on the photosensitive drum 31 is visualized as a toner image. And a transfer charger roller 34 for transferring a visualized toner image onto the fed paper. Further, the image forming unit 5
A pickup roller 35 for taking the paper stored in the paper supply unit 6 into the main body, a fixing roller 36 for fixing the toner image transferred onto the paper, a paper discharge roller 37 for discharging the paper to the outside of the main body, and the like. Is also provided.

Hereinafter, the operation of the image forming apparatus 1 according to this embodiment will be described. The image forming apparatus 1 of this embodiment turns on the light source 11 (fluorescent lamp) not only during the copying operation but also during standby. During standby, the polygon mirror 22 of the image forming unit 5 is also rotating. The timing for turning off the light source 11 and the timing for stopping the rotation of the polygon mirror 22 are when the power switch of the main body is turned off, and when the apparatus switches from the standby mode to the power saving mode. The power-saving mode is a state in which the power switch of the main body is turned on (except during an operation such as a copying process), and when no input operation is performed on the main body for a predetermined time or more, the display unit (not shown) This is a mode in which the power supply to the main body is stopped to reduce the power consumption of the main body.

Further, the image forming apparatus 1 of this embodiment
A structure for detecting the open / closed state of the document table cover 3 is provided. 2A and 2B are diagrams showing a configuration of opening / closing detection of the platen cover. FIG. 2A shows a state in which the platen cover is closed, and FIG.
Indicates that the document table cover is open. The platen cover 3 is rotatably attached to the main body 1. When in the closed state, the end of the platen cover 3 presses the lever 41 (presses down) to turn on the micro switch 42. When the platen cover 3 is in the open state, the spring 43 biases the lever 41 not pressed by the end of the platen cover 3 upward (pushed up) to turn off the micro switch 42. . The image forming apparatus 1 detects the open / closed state of the platen cover 3 from the on / off state of the microswitch 42.

Next, a document reading operation of the image forming apparatus 1 of this embodiment will be described. FIG. 3 is a flowchart showing the document reading operation. In the image forming apparatus 1 of this embodiment, when the platen cover 3 shifts from the closed state to the open state (when the opening of the platen cover 3 is detected), the optical system including the light source 11 and the like of the image reading unit 3 is operated. The light source 11 is moved to the home position (at this time, the light source 11 is lit), and the light source 1 is turned on.
It is determined whether or not 1 is a stable light amount at which a document image can be read (a light amount stability check is performed), and black level correction and white level correction for the CCD 12 are executed (n1 to n).
5). As is well known, the black level correction is a process of detecting a threshold level at which the output of the CDD 12 is set to be black when performing AD conversion, and the white level correction is a process of determining a threshold level at which the output of the CDD 12 is determined to be white when performing A / D conversion. This is the process of detecting the level.

Upon completion of the processing of n1 to n4, it is determined whether or not a copy switch (not shown) has been operated.
If the copy switch has been operated, the shading correction for the CCD 12 is performed, and the actual image reading process is executed (n5 to n7). When the white level correction is completed in n4, if the copy switch has not been operated yet, the processing after n6 is executed after the copy switch is operated. At this time, if the copy switch is not operated even after the predetermined time has elapsed (n9), the process returns to n1. Note that the shading correction is a well-known
The white balance of the CCD 12 is a general term for the black level correction, the white level correction, and the shedding correction.

As described above, in the image reading unit 4 according to this embodiment, the light amount stability check, the black level correction, and the white level correction are performed not when the copy switch is operated, but when the copy switch is operated.
Since it was performed when the platen cover 3 was opened,
The time from when the copy switch is operated to when the image reading unit 4 starts the actual image reading process is reduced. Specifically, as shown in FIG. 4, the actual image reading process (takes about 9 seconds)
Before the confirmation, the light amount stability confirmation (takes about 1 second), black level correction (takes about 0.75 seconds), white level correction (takes about 0.
It takes 75 seconds), and the shading correction (which takes about 1 second) is performed in this order (-is read preparation processing). However, after the copy switch shown in FIG. According to the conventional method, it took about 12.5 seconds from when the copy switch was operated to when the image reading unit 4 completed the actual image reading. However, in the image reading unit 4 of this embodiment, FIG. As shown in B), when the platen cover 3 is opened, confirmation of stable light quantity, black level correction, and white level correction are started.
The time required from when the copy switch is operated to when the image reading unit 4 completes the actual image reading processing is at least about 10 seconds (the time can be reduced up to about 2.5 seconds at the maximum).

After the platen cover 3 is opened,
If the copy switch is operated before the elapse of 2.5 seconds (after the start of the light quantity stability check), at this point at least the white level correction has not been completed, and the shading correction is performed after the white level correction is completed. The following processing is executed. Therefore, the time required from the operation of the copy switch to the completion of the actual image reading process in the image reading unit 4 exceeds 10 seconds. However, even in this case, the platen cover 3 is opened more than in the conventional method. And the time from when the copy switch is operated is reduced.

Further, in the image forming apparatus 1 of this embodiment, as shown in FIG. 4, the image reading section 5 also starts the print preparation processing when the document platen cover 3 is opened, and the copy switch is operated. It is possible to reduce the time from the completion of the printing until the printing of the document image read by the image reading unit 4 is completed (the time until the paper on which the image is formed on the paper discharging unit 7 is discharged). The print preparation process is a process for adjusting the rotation speed, potential, and the like of the photosensitive drum 31 and the transfer roller 34, as is well known. As described above, the print preparation process is also started when the platen cover 3 is opened, so that the time from when the copy switch is operated to when the sheet on which the document image is copied is discharged (copying time). Processing time) can be reduced. The figure shows the time for adjusting the print timing of the image on the paper (print timing adjustment time).
Is an actual image forming process.

Next, another embodiment of the present invention will be described. The image forming apparatus 1 of this embodiment is obtained by adding a configuration for simultaneously executing the black level correction and the white level correction of the CCD 12 to the above-described embodiment. The black level correction is a process of detecting the output level (black level) of the CCD 12 when there is no incident light amount in order to remove the influence of thermal noise due to heat generation of the CCD 12. The white level correction is a process of detecting an output level (white level) when detecting reflected light from a white plate irradiated by the light source 11 in order to remove the influence of thermal noise due to heat generation of the CCD 12. Regarding the influence of this thermal noise, since the variation in each pixel of the CCD 12 is small, the average output of about 100 pixels having no incident light amount is detected as the black level.

The image forming apparatus 1 according to this embodiment includes a CCD
12, an image area 51 where light reflected from the original enters, and a non-image area 52 where light does not enter on both sides of the image area 51, respectively.
(See FIG. 5). The CCD 12 of this embodiment has an image area 51 where the reflected light from the original enters 3400 pixels due to the optical system of the image reading unit 3, and a non-image area 5 of 800 pixels on both sides of which the reflected light from the original does not enter.
Two. As described above, the CCD 12 has a sufficiently large number of pixels than the number of pixels required for reading a document image. Hereinafter, the black level correction and the white level correction of the image forming apparatus 1 (image reading / reading unit 3) of this embodiment will be described.

As described above, the black level of the CCD 12 can be obtained by detecting the average output of about 100 pixels having no incident light amount. Since the CCD 12 has a non-image area 52 into which light does not enter due to the configuration of the optical system, the average output of about 100 pixels existing in the non-image area 52 can be detected as a black level. Moreover, since the non-image area 52 does not receive the reflected light from the light source 11, the black level correction can be performed while the light source 11 is turned on without turning off the light source 11 as in the related art. Note that even in the non-image area 52, light (light source 11) is applied to pixels near the boundary with the image area 51.
It is desirable to perform black level correction using pixels at both ends of the CCD 12 (for example, 50 pixels on one side and a total of 100 pixels) (using the black level correction area 53 shown in FIG. 5). It is desirable to perform black level correction.) In addition, since the black level correction can be performed while the light source 11 is turned on, the white level correction can be performed simultaneously using the pixels in the image area 51 that are not used in the black level correction.

As described above, in this embodiment, the CCD 12
Has more pixels than the number of pixels required for reading the original image, so that the black level correction and the white level correction of the CCD 12 can be executed simultaneously, and the time required for the white balance of the CCD 12 can be reduced. Yes (approx. 1. if black level correction and white level correction are performed separately.
Although it takes 5 seconds, it can be reduced to about 0.75 seconds if the black level correction and the white level correction are performed simultaneously. ).

Next, another embodiment of the present invention will be described. The image forming apparatus 1 of this embodiment is obtained by adding the following functions to one of the above two embodiments. As described above, the image forming apparatus 1 according to the above-described embodiment detects the opening of the platen cover 3 and
2 is a configuration for executing black level correction and white level correction. For this reason, the black level correction and the white level correction may be executed when the platen cover 3 is open. If the black level correction and the white level correction are executed while the platen cover 3 is open, the disturbance light passing through the platen 2 (contact glass) may enter the CCD 12 as stray light. If the black level correction and the white level correction are performed in a form including the stray light, the correction result becomes erroneous, and a problem such as poor image quality occurs. Therefore, the image forming apparatus 1 of this embodiment has a function of removing the stray light when the black level correction and the white level correction are affected by the stray light and appropriately reading the original image.

FIG. 6 is a flowchart showing a document reading operation of the image forming apparatus of this embodiment. In the image forming apparatus 1 of this embodiment, when the platen cover 3 is opened (n
11) The light source 11 is moved to the home position (n1
2) Execute the light quantity stability check of the light source 11 and execute the black level correction and white level correction of the CCD 12 (n13 to n1).
5). In addition, a timer (not shown) built into the main body
When it is detected that the predetermined time has passed without opening the platen cover 3, if the platen cover 3 is in the closed state (n11 → n22 → n23), the light source 11 is moved to the home position ( n24) After confirming the light amount stability of the light source 11 and performing black level correction and white level correction of the CCD 12, the timer is reset and the process returns to n11 (n25).
To n28).

As described above, the image forming apparatus 1 of this embodiment executes the black level correction and the white level correction of the CCD 12 every time a predetermined time elapses when the document table cover 3 is closed. The image forming apparatus 1 may be configured to execute the black level correction and the white level correction at the same time, or may be configured to execute the black level correction and the white level correction separately. Also, about 1 minute is appropriate as the fixed time.

Here, the CC executed at n26 and n27
In the black level correction and the white level correction of D12, the stray light does not occur because the platen cover 3 is always in the closed state, but the black level correction and the white level correction of the CCD 12 are performed in the platen cover 3 in n14 and n15. May be executed in the open state, and may be affected by stray light. The image forming apparatus 1 of this embodiment includes n14, n15
When the black level correction and white level correction of the CCD 12 are completed, it is determined whether or not there is an influence of stray light (n16).

Hereinafter, the CCD 12 in n14 and n15
A method for determining the presence or absence of the influence of stray light by the black level correction and white level correction will be described. As shown in FIG. 7A, when the light amount of the light source 11 is stable, CC
The output of D12 is also stable, but if stray light occurs regardless of black level correction and white level correction, the CCD 12
Output level greatly changes. Further, as shown in FIG. 7B, the white level may exceed the saturation level of the CCD 12 due to the generation of stray light, and the white level may not be adjusted. For the above reason, the black level and white level detected in the black level correction and white level correction executed in n14 and n15 differ from the black level and white level detected in the previous black level correction and white level correction by a predetermined amount or more. And that it is affected by stray light.

If the image forming apparatus 1 determines in step n16 that there is no influence of stray light, the image forming apparatus 1 uses the results of the black level correction and the white level correction executed in steps n14 and n15, and
The processing after n18 is executed (the processing of n6 to n8 shown in FIG. 3 is executed). On the other hand, when it is determined in step n16 that the image is affected by the stray light, the black level and the white level detected in the previous black level correction and white level correction are used (the black level correction and the white level executed in steps n14 and n15). Without using the detection result in the correction) (n1
7), execute the processing after n18 (n6 to n6 shown in FIG. 3)
The processing of n8 is executed. ).

As described above, in the image forming apparatus 1 of this embodiment, the black level correction and the white level correction of the CCD 12 are repeatedly performed at regular time intervals, and the black level correction and the white level correction performed at the time of reading the original image are stray light. The original image is read using the black level and white level detected by the previous black level correction and white level correction when the original image is affected, so that the original image is not affected by stray light. Can be read.

In some cases, the amount of stray light is small and the black level and the white level in the previous black level correction and white level correction do not change by a predetermined amount or more. In such a case, the shading correction executed in step n19 is performed. As a result, the influence of the stray light can be removed, and the original image can be read properly.

When the document cover 3 is opened, the CCD 12
It is possible to use the results of the previous black level correction and white level correction without executing the black level correction and white level correction of Since it is optimal to use the result of the level correction, in the above embodiment, only when stray light occurs (when the result of the black level correction and the white level correction performed immediately before reading cannot be used), The original image is read using the highly reliable previous detection result.

Next, another embodiment of the present invention will be described. The image forming apparatus 1 according to the above-described embodiment is of a so-called flat bed type in which the user opens the document table cover 3 and sets a document at a reading position, but the image forming apparatus 1 according to the present embodiment is set on a document table. And a document feeder for transporting the originals one by one. FIG. 8 is a diagram showing a configuration of a document feeder applied to the image forming apparatus of this embodiment. The document feeder 60 includes the document table 6
A conveyance path (a path shown by a broken line in the figure) for conveying the original set in 1 is formed.
The document is conveyed from the document placing table 61 to the document discharge section 65 by. In the middle of the transport path, a platen glass 6
6 and a document pressing plate 67 for pressing a document passing on the platen glass 66 against the platen glass 66. The document pressing plate 67 is urged downward by an elastic body such as a spring. Reference numeral 68 denotes a placement detection sensor that detects that a document is placed on the document placement table, and reference numeral 69 denotes a passage detection sensor that detects passage of the document. The size (length) of the original placed on the original placing table 61 is also detected by using the placement detection sensor 68 and the passage detection sensor 69, and the paper on which the read original image is printed is printed. It is used to select the size etc. Further, the document reading section 4 is arranged below the platen glass 66.

In the document feeder having the above configuration, the documents set on the document table 61 are conveyed one by one to the document discharge section 65. The original being conveyed is illuminated by the light source 11 when passing over the platen glass 66, and the CCD 12 detects the reflected light to read the original image. The transport roller 63 is a PS roller that adjusts the timing of reading a document image in the document reading unit 8. In this embodiment, the position of the document reading unit 3 is fixed, and a document image read by the document reading unit 3 is formed on a sheet in an image forming unit (not shown).

In the case of the image forming apparatus 1 to which the document feeder 60 having the above configuration is applied, when the placement detection sensor 68 detects that a document has been set on the document placement table 61 as shown in FIG. , The black level correction and the white level correction may be started. By doing so, the same effects as those of the image forming apparatus 1 of the above embodiment can be obtained.

Note that the image forming apparatus 1 of the above embodiment may be a multifunction peripheral having a printer function, a facsimile function, and the like in addition to a copying function.

[0049]

As described above, according to the present invention, when the opening / closing detecting means detects that the platen cover is opened,
Since the reading preparation (white balance) such as the black level correction of the CCD is started, when the user performs the operation of starting the reading of the document image after the completion of the setting of the document, the reading preparation process has already been started. Therefore, the time until the actual image reading process is started can be reduced, and as a result, the time required for reading the document image can be reduced.

Further, since a non-image area in which reflected light from the original does not enter when reading the original is provided in the CCD, and black level correction is performed using this non-image area, the black level can be adjusted without turning off the light source. Level correction can be performed. Further, since the black level correction and the white level correction can be performed at the same time, the time required for the reading preparation processing can be reduced.

If disturbance light (stray light) enters the CCD and proper black level correction and white level correction cannot be performed, the result of the previous black level correction and white level correction is used. The original image can be read without being affected by the image.

Further, when a document is set in the document feeder, preparation for reading (white balance) such as black level correction of the CCD is started, so that the user can start reading the document image after setting the document. When the operation is performed, the reading preparation processing has already been started. Therefore, the time until the actual image reading processing is started can be reduced, and as a result, the time required for reading the document image can be reduced.

Further, in the image forming apparatus of the present invention, the printing preparation process is started when the opening of the document platen cover or the setting of the document on the document feeder is detected, so that the actual printing process is started. Can be shortened, and as a result, the time required for copying can be shortened, and the working efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration for detecting an open / closed state of a document table cover.

FIG. 3 is a flowchart illustrating a document reading operation in the image forming apparatus according to the embodiment.

FIG. 4 is a diagram comparing operation timings of the conventional image forming apparatus and the image forming apparatus of the embodiment.

FIG. 5 is a diagram showing a configuration of a CCD applied to an image forming apparatus according to another embodiment of the present invention.

FIG. 6 is a flowchart illustrating a document reading operation in the image forming apparatus according to the embodiment.

FIG. 7 is a diagram showing a change in the output level of the CCD due to generation of stray light.

FIG. 8 is a diagram showing a configuration of a document feeder applied to another embodiment of the present invention.

FIG. 9 is a flowchart illustrating a document reading operation in the image forming apparatus according to the embodiment.

[Explanation of symbols]

 1-Image Forming Apparatus 2-Document Base 3-Document Base Cover 4-Document Reading Section 5-Image Forming Section 11-Light Source 12-CCD 42-Switch 60-Document Feeding Apparatus 68-Placement Detection Sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshikazu Kondo 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5B047 AA01 BB01 BC14 DA04 5C072 AA01 AA05 BA08 DA12 FB12 RA16 UA02 XA01

Claims (7)

[Claims] An image reading apparatus comprising: a light source for irradiating a document set on a document table; and a CCD for reading a document image by detecting reflected light from the document, wherein the document covering the document table is provided. An opening / closing detecting means for detecting opening / closing of a table cover, and an image reading apparatus for starting reading preparation processing such as black level correction of the CCD when the opening / closing detecting means detects opening of the document table cover. 2. The image reading device according to claim 1, wherein the CCD has a non-image area into which reflected light from the original does not enter when reading the original image, and executes the black level correction in the non-image area. apparatus. 3. The image reading apparatus according to claim 2, wherein the reading preparation processing includes white level correction of the CCD, and executes the white level correction in an image area of the CCD that is not a non-image area. 4. A black / white level correction means for repeatedly performing the black level correction and the white level correction at regular intervals when the platen cover is closed, and a black level correction unit which is triggered by opening the platen cover. A stray light generation determining means for determining the presence or absence of the influence of stray light based on the detected value and the detection value of the previous black level correction; and 4. The image reading device according to claim 3, wherein the image reading device reads a document image. 5. The stray light occurrence determining means determines whether or not there is an influence of stray light based on a detected value of white level correction executed with the opening of the document plate cover as a trigger and a detected value of previous white level correction. 5. The image reading apparatus according to claim 4, wherein when it is determined that the influence of the stray light is present, the reading of the document image is performed using the result of the previous white level correction. 6. A document feeder for conveying a set document to a document image reading position, a light source for irradiating the document conveyed to the reading position, and a document by detecting reflected light from the document. An image reading device comprising: a CCD for reading an image; a document set detecting unit for detecting whether a document is set in the document feeding unit; and An image reading apparatus that starts reading preparation processing such as black level correction for the CCD. 7. An image forming apparatus, comprising: the image reading device according to claim 1; and an image forming apparatus for forming an original image read by the image reading device on a sheet. An image forming apparatus that starts a print preparation process according to a start timing of the preparation process.