JP2001249581A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device by which the occurrence frequency of a defective image due to erroneous detection is suppressed by performing the automatic detection of an OHT sheet only at a required time. SOLUTION: This image forming device is provided with a first controlling means to perform the control of image formation under a normal plain paper processing condition in the case of detecting plain paper by a plain paper detecting part, a second controlling means to perform the control of the image formation under an OHT sheet processing condition which is different from a normal condition in the case of automatically detecting an OHT sheet by an OHT detecting part, a cardboard mode setting part to set a cardboard mode and a third controlling means to perform the control of the image formation by a cardboard processing condition in the case of setting the cardboard mode by the cardboard mode setting part, and in the case that the cardboard mode is set, the automatic detection of the OHT sheet is not performed.

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 for visualizing an electrostatic latent image with toner.

[0002]

2. Description of the Related Art <First Prior Art> When plain paper is detected by a plain paper detection unit, image formation is controlled under normal process conditions for plain paper. When the detection is automatically performed by the detection unit, the image forming control is performed under the process conditions for the OHT sheet different from the normal one. When the thick paper mode is set by the thick paper mode setting unit, the thick paper mode is set. Image formation is controlled under process conditions. There is known an image forming apparatus which always performs automatic detection of an OHT sheet even when a thick paper mode is set.

<Second conventional technology> When an OHT sheet is automatically detected by an OHT detection unit, image formation is controlled under OHT sheet process conditions, and a double-sided printing mode setting unit is used. When the double-sided printing mode is set, image formation is controlled under the process conditions for double-sided printing. There is known an image forming apparatus which always performs automatic detection of an OHT sheet even when a duplex printing mode is set.

<Third conventional technology> When an OHT sheet is automatically detected by an OHT detection unit, image formation is controlled under OHT sheet process conditions, and the paper size is set by a paper size setting unit. When set, the image formation is controlled under the process conditions for the predetermined paper size, and the automatic detection of the OHT sheet is always performed even when the paper size setting is other than A4 size or letter size. Forming devices are known.

[0005] <Fourth conventional technique> When an OHT sheet is automatically detected by an OHT detection unit, image formation is controlled under OHT sheet process conditions, and a double-sided printing mode setting unit performs double-sided printing. When the mode is set, image formation is controlled under the process conditions for double-sided printing, the double-sided printing mode is set, and automatic printing is performed when the medium is the OHT sheet during printing in the double-sided printing mode. Even if it is detected, no warning is displayed and the printing operation is not stopped
2. Description of the Related Art An image forming apparatus that performs duplex printing on an HT sheet is known.

<Fifth Prior Art> A thick paper mode can be selected. When the thick paper mode is operated, the thick paper mode is selected on the operation panel every time, and the image forming process conditions are set to set the image forming process. An image forming apparatus for performing the above is known.

<Sixth prior art> In addition, a glossy paper mode can be selected. When the glossy paper mode is operated, the glossy paper mode is selected on the operation panel every time to set an image forming process condition. 2. Description of the Related Art An image forming apparatus that forms an image on glossy paper is known.

<Seventh Prior Art> Further, in an electrophotographic image forming apparatus using a toner, a printing rate is low and output is low for a long period of time. An image forming apparatus used under conditions is known.

<Eighth Prior Art> Furthermore, in order to prevent the developing property from changing due to the surrounding humidity of the image forming apparatus and making it difficult to obtain a stable image, a process based on the surrounding humidity at that time is performed. 2. Description of the Related Art An image forming apparatus that controls conditions is known.

[0010]

[Problems to be Solved by the Invention]
As a problem of the conventional technology of the related art, the OHT detection unit always operates in the thick paper mode, which is not normally used for the OHT sheet.
When the automatic detection of the HT sheet is performed, there is a problem that the probability of the erroneous detection by the OHT detection unit increases. The present invention has been made in view of the above problems, and a first object of the present invention is to provide an image forming apparatus which stops automatic detection of an OHT sheet when thick paper mode is set, thereby preventing erroneous detection of the OHT sheet. Is to do.

<Second conventional problem>
Even in the double-sided printing mode in which the THT sheet is not used, there is a problem that if the OHT detection unit constantly performs the automatic detection of the OHT sheet, the probability of the OHT detection unit erroneously detecting increases. The present invention has been made in view of the above problems,
An object of the second invention is to set an OHT when the duplex printing mode is set.
An object of the present invention is to provide an image forming apparatus which stops automatic detection of a sheet and prevents erroneous detection of an OHT sheet.

<Problem of the third conventional technology>
The OHT detection unit always operates at O, even when the paper size is set to a size other than A4 size or letter sheet, which is not normally used for T sheets.
Since the automatic detection of the HT sheet is performed, there is a problem that the probability of erroneously detecting the OHT sheet of the OHT detection unit is increased even in the case other than the A4 size or the letter sheet. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a third object of the present invention is to stop automatic detection of an OHT sheet when the paper size setting is other than A4 size or letter size.
An object of the present invention is to provide an image forming apparatus that prevents erroneous detection of a sheet.

<Problem of the fourth conventional technique> As an example, when an OHT sheet is set from a manual feed tray and printing is performed, if the duplex printing mode setting is kept as it is, duplex printing is performed on the OHT sheet. Problem. The present invention has been made in view of the above problems, and a fourth object of the present invention is to provide a case where a double-sided printing mode is set and the medium is automatically detected as an OHT sheet during printing in the double-sided printing mode. An object of the present invention is to provide an image forming apparatus which issues a warning and prevents double-sided printing on an OHT sheet.

[0015] As a fifth problem of the prior art, when a user prints on thick paper, it is necessary to set a thick paper mode on the operation panel every time, and the operation is troublesome. In addition, if another user forgets to insert the cardboard into the image forming apparatus, there is a problem that desired print quality cannot be obtained. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of a fifth invention is to provide an image forming apparatus capable of outputting a good image on a thick paper with a simple operation without selecting the thick paper. .

<Sixth prior art problem> As a user prints on glossy paper, every time on the operation panel,
It is necessary to set the glossy paper mode, and the operation is troublesome. Further, if another user forgets to put glossy paper into the image forming apparatus, there is a problem that desired print quality cannot be obtained. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of a sixth invention is to provide an image forming apparatus capable of outputting a good image with a simple operation without selecting glossy paper.

<Seventh problem of prior art> In an image forming apparatus using toner, when used for a long time at an output with a low printing rate, toner in a developing device is not consumed much. There is a problem that the image density becomes unstable and the image density becomes unstable. The present invention has been made in view of the above problems, and an object of a seventh invention is to provide an image forming apparatus capable of outputting a stable image even when used for a long time at an output with a low printing rate.

As an eighth problem of the related art, when the humidity change is large, the image quality is affected. Specifically, a problem such as an excessive concentration or a decrease in concentration occurs. For this reason, conventionally, after a pause in which the change in humidity is relatively large, the execution interval of the test patch inspection is usually executed every 200 prints, every 50 prints. Further, the target value of the toner concentration in the developing device is also corrected according to the humidity at that time, but there is a problem that it is still insufficient. The present invention has been made in view of the above problems, and an object of an eighth invention is to provide an image forming apparatus capable of forming a stable image even when there is a change in humidity around the image forming apparatus.

[0018]

The object of the first invention is achieved by the following means.

(1) When plain paper is detected by the plain paper detection unit, first control means for controlling image formation under normal plain paper process conditions, and the OHT sheet is converted to OH
A second control unit for controlling image formation under process conditions for an OHT sheet different from the normal case when automatically detected by the T detection unit; a thick paper mode setting unit for setting a thick paper mode; A third control unit for controlling image formation under the process conditions for the thick paper when the thick paper mode is set by the mode setting unit, and the OHT sheet when the thick paper mode is set. An image forming apparatus that does not perform automatic detection of an image.

The object of the second invention is achieved by the following means. (2) When the OHT sheet is automatically detected by the OHT detection unit, a second control unit that controls image formation under process conditions for an OHT sheet that is different from a normal one, and duplex printing that sets a duplex printing mode. A mode setting unit; and a fourth control unit for controlling image formation under a process condition for the duplex printing mode when the duplex printing mode is set by the duplex printing mode setting unit. An image forming apparatus, wherein the automatic detection of the OHT sheet is not performed when a print mode is set.

The object of the third invention is achieved by the following means. (3) When an OHT sheet is automatically detected by the OHT detection unit, a second control unit that controls image formation based on the process conditions for the OHT sheet, a paper size setting unit that sets a paper size, When the paper size is set by the paper size setting unit, a fifth control unit that controls image formation under a process condition for a predetermined paper size is provided, and the paper size setting is A4 size or letter. An image forming apparatus, wherein the automatic detection of the OHT sheet is not performed when the size is other than the size.

The object of the fourth invention is achieved by any of the following means. (4) When the OHT sheet is automatically detected by the OHT detection unit, a second control unit that controls image formation under process conditions for the OHT sheet that is different from a normal one, and duplex printing that sets a duplex printing mode. A mode setting unit, and a fourth control unit for controlling image formation under the process conditions for duplex printing when the duplex printing mode is set by the duplex printing mode setting unit. When the medium is automatically detected as the OHT sheet during printing in the duplex printing mode, a warning is displayed on the warning display unit and the printing operation is stopped. An image forming apparatus comprising:

(5) When the OHT sheet is automatically detected by the OHT detection unit, a second control means for controlling image formation under process conditions for the OHT sheet different from the normal state, and a duplex printing mode are set. A double-sided printing mode setting unit, and a fourth control unit for controlling image formation under double-sided printing process conditions when the double-sided printing mode setting unit sets the double-sided printing mode. The duplex mode is set by the print mode setting unit. If the medium is automatically detected as an OHT sheet by the OHT detection unit during printing in the duplex mode, a warning is displayed on the warning display unit. And an image forming apparatus for temporarily suspending the printing operation and, when an instruction to continue the printing operation is issued, continuing the printing operation.

The object of the fifth invention is achieved by the following means. (6) a curl forming mechanism that conveys the rear end of the transfer paper to form a curl of the transfer paper for a predetermined time after the front end of the transfer paper is once stopped while conveying the transfer paper; A curl amount detecting unit for detecting a curl amount formed by the curl forming mechanism, a paper size detecting unit for detecting a paper size of the transfer paper, a curl amount detected by the curl amount detecting unit, and the paper size detecting unit A paper thickness calculating means for calculating the thickness of the transfer paper based on the paper size detected by the method, and controlling the image formation by a process condition based on the thickness of the transfer paper obtained by the paper thickness calculating means. 6
An image forming apparatus comprising:

The object of the sixth invention is achieved by the following means. (7) a specular / diffuse reflected light component detection unit for detecting a specular reflection light component and a diffuse reflection light component of the transfer paper, respectively, and a glossiness of the transfer paper based on a detection result by the specular / diffuse reflection light component detection unit An image forming apparatus comprising: a glossiness calculating means for calculating the glossiness; and a seventh control means for controlling image formation based on a process condition based on the calculated glossiness.

The object of the seventh invention is achieved by the following means. (8) a print dot number detection unit for detecting the number of print dots;
For each print, a toner amount calculating means for calculating the consumed toner amount based on the number of print dots detected by the print dot number detection unit, a print number integration unit for integrating the number of prints, and an integration of the calculated toner amount Calculating means for calculating the average toner consumption per print by integrating and averaging the toner amount during the predetermined printing based on the number of prints performed; and process conditions based on the calculation result of the calculating means. An image forming apparatus, comprising: eighth control means for controlling image formation.

The object of the eighth invention is achieved by the following means. (9) A time measuring unit for measuring the ON / OFF time of a power supply formed in the image forming apparatus, a humidity detecting unit for detecting a humidity around the image forming apparatus, and a humidity and time when the power is turned on. As a base point, humidity is detected at a predetermined cycle,
Humidity transition storage means for storing the elapsed time and humidity data as humidity transition data at any time;
Humidity transition estimating means for estimating a subsequent humidity transition around the image forming apparatus based on the power supply operation unit to be operated, the time and humidity at which the power is turned on, and the stored humidity transition data after the previous power on. An image forming apparatus comprising: a ninth control unit configured to control image formation based on a process condition based on a prediction result by the humidity transition prediction unit.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment according to claims 1 to 6, and claims 7 to 11 will be described.
An image forming apparatus according to a second embodiment will be described with reference to the drawings.

<First Embodiment> FIG. 1 is a diagram showing a configuration of an image forming apparatus according to a first embodiment, FIG. 2 is a block diagram showing a configuration relating to control of the image forming apparatus according to the first embodiment, and FIG. 4 is a main operation flowchart of the image forming apparatus according to the first embodiment.

As shown in FIG. 1, an operation panel 91 is a panel for operating the image forming apparatus, and can perform a copy start input, a thick paper mode setting input, a paper thickness mode setting input, a duplex printing mode setting input, and the like. The warning display section 17 displays various warnings to the user. The automatic document feeder 44 is a device that automatically supplies a document placed on the document table 41. Further, the image reading means 42 moves the reading optical system to read the image of the document by the CCD 43.

The image forming section 46 includes a known image writing section 4.
5, a photoconductor 47, a charging electrode 48, a developing device 49, a transfer electrode 50, a separation electrode 51, a fixing device 61, and the like. The image writing unit 45 emits light from the semiconductor laser and scans and exposes the photosensitive member 47 via a polygon mirror. The developing device 49 supplies toner. Further, the fixing device 6
Reference numeral 1 denotes a heating roller and a pressure roller, and the toner powder forming the toner image is melted and fixed on the transfer paper P by the heat and pressure of the pair of rollers.

The cleaning means 52 is provided for the photosensitive member 4 after the transfer.
7 is cleaned. Also, the first tray 57,
The second tray 58, the third tray 59, and the manual feed tray 62 are trays for storing transfer paper, such as plain paper, thick paper, and OHT sheets.

The first roller (registration roller) 71 temporarily stops the transfer paper P and causes the transfer paper P to enter the transfer area in synchronization with the image area where the toner image is present when the rotation is started.

The transfer electrode 50 is an electrode for transferring the toner image to the transfer paper P, and the separation electrode 51 is an electrode for separating the toner image from the surface of the photosensitive member 47.

When image formation is performed on both sides of the transfer paper P, the passage switching means 56 is a switching means for turning the transfer paper P recorded on one side downward after passing through the fixing device 61.

The transfer paper reversing means 60 is means for reversing the transfer paper fed toward the first roller 71 such that the unrecorded surface of the transfer paper is on the upper side. The paper discharging means 55 is means for discharging the transfer paper to the discharge tray 63.

The OHT detecting section 3 is a sensor for detecting the presence or absence of an OHT sheet, and the plain paper detecting section 1 is a sensor for detecting plain paper.

Here, a process for simply forming an image will be described. Image information of the document S read by the CCD 43 is stored, and based on the image data, a semiconductor laser forming the image writing unit 45 emits light, and scans and exposes the photosensitive member 47 via a polygon mirror. Prior to this exposure, a uniform potential is applied to the surface of the photoconductor 47 from the charging electrode 48, and an electrostatic latent image corresponding to image data is sequentially formed on the photoconductor 47. The electrostatic latent image is reversely developed by the developing device 49 to become a visible image. Before the leading end of the visible image reaches the transfer area due to the rotation of the photoconductor 47, the transfer paper is fed from the tray, and the transfer paper that has been in the standby state by the first roller 71 disposed before the transfer area. P is fed by the start of rotation of the first roller 71 and enters the transfer area in synchronization with the image area where the toner image exists. The transfer paper P on which the toner image has been transferred is separated from the surface of the photoreceptor 47 by the separation electrode 51, and the fixing device 6
It is transported toward 1. Then, the toner powder forming the toner image is melted and fixed on the transfer paper P by the heat and pressure bonding, and is discharged to the discharge tray 63 by the discharge means 55 including a pair of rollers. An image is formed on a transfer sheet as described above. Here, a configuration block relating to control of the image forming apparatus of the present invention will be described with reference to FIG. The plain paper detecting section 1 is a detecting section for detecting plain paper, and the OHT detecting section 3 is a detecting section for detecting an OHT sheet. The OHT detection unit 3 is located upstream of the writing start position, is located at a paper feed port of the manual feed tray 62 capable of automatically detecting OHT sheets before writing, and can automatically detect immediately after manual paper feeding.

The thick paper mode setting section 4 is a setting section for setting a thick paper mode, the double-sided printing mode setting section 9 is a setting section for setting a double-sided printing mode, and the paper size setting section 14 is a setting section for setting a paper size. And are provided on the operation panel 91 shown in FIG.

When the first control means 2 detects plain paper, it does not automatically detect an OHT sheet, but controls image formation under normal process conditions for plain paper. When the second control means 5 detects the OHT sheet,
Image formation is controlled under the process conditions for the T sheet.
When the thick paper mode is set, the third control means 6 does not automatically detect an OHT sheet, but controls image formation under thick paper process conditions.
Control means 11 when the double-sided printing mode is set,
The image formation is controlled under the process conditions for the duplex printing mode without performing the automatic detection of the OHT sheet. further,
The fifth control unit 15 is configured to set the OHT sheet to an OHT sheet when the paper size is set to a size other than A4 size or letter size.
Image formation is controlled under process conditions for paper sizes other than A4 size or letter size without performing automatic detection by the detection unit.

The CPU 8A is a central processing unit for controlling the first to fifth control means. The warning display section 17 indicates that the medium is OHT during printing in the duplex printing mode setting.
This is a display unit for issuing a warning display when a sheet is automatically detected. Further, the image forming means 12 includes plain paper, cardboard,
This is a means for forming an image on an OHT sheet or the like.

Next, the operation when the user has selected each mode will be described with reference to FIGS. 1, 2 and 3. FIG. FIG.
Various modes are selected from the operation panel 91 shown in FIG. First, it is determined whether the thick paper mode has been set (flow F01). If the thick paper mode has been set by the thick paper mode setting unit 4, a thick paper mode setting command is issued from the controller before the print command, and the OHT
Without performing automatic detection of the sheet, the process speed is reduced to half of the normal speed in order to secure the fixing property, and the image formation is performed under the process conditions different from the normal conditions such as charging, developing bias and transfer output ( Flow F02).

On the other hand, if the thick paper mode has not been set, it is next determined whether or not the duplex printing mode has been set (flow F03). Duplex printing mode setting section 9
If the duplex printing mode has been set, the controller issues a duplex printing mode setting command prior to the print command. The automatic detection of the OHT sheet is not performed, and the process is performed under the process conditions for the duplex printing. The speed is the same as usual, but once the transfer paper on which transfer and fixing have been completed is reversed, the transfer paper is guided to a two-sided conveyance path, transferred to the back surface, fixed, and discharged to the discharge tray 63 (flow F
04).

On the other hand, if the duplex printing mode has not been set, it is next determined whether or not the A4 size or letter size paper size has been set (flow F0).
5).

If the paper size of A4 size or letter size is not set, the automatic detection of the OHT sheet is not performed prior to the print command from the controller, and the image is formed under normal process conditions (flow F0).
7).

On the other hand, if the paper size of A4 or letter size is set, the automatic detection of the OHT sheet is performed. That is, the sheet feeding operation is performed, and the automatic determination of the OHT sheet is performed a predetermined time after the start of sheet feeding. If it is determined that the sheet is an OHT sheet, the rotation speed of the belt motor is reduced to 1/6.
, And a circuit speed of 1/6 is selected for the image data control circuit, and the writing operation is started (flow F06). Subsequently, it is determined whether or not the sheet is an OHT sheet (flow F08). If the sheet is not an OHT sheet, the flow F07 is performed.

On the other hand, in the case of an OHT sheet, the process speed is reduced to 1/6 of the normal speed in order to secure the transparency of the OHT sheet. The image is formed under the process conditions set differently from those at the time of thick paper or thick paper (flow F09).
This completes the copy operation.

Here, an example of the embodiment according to claim 4 will be described. Even when image formation is being performed in the duplex printing mode setting, an OHT sheet is automatically detected. If the medium is automatically detected as an OHT sheet,
A warning is displayed on the warning display section 17 shown in FIG. 1 and the operation of image formation is stopped. As described above, double-sided printing on the OHT sheet can be prevented.

Next, an example of the embodiment according to claim 5 will be described. The OHT sheet is automatically detected even while image formation is being performed in the duplex printing mode setting, and when the medium is automatically detected as an OHT sheet, a warning is displayed on the warning display unit 17 shown in FIG. "Cancel" and "Continue" are input and displayed. If the OHT sheet is erroneously detected, "continue" is input. If the OHC sheet is detected, "continue" is input after removing the OHT sheet. When the “continue” input key is pressed, a command to continue the printing operation is issued from the controller, and the printing operation is continued. As described above, erroneous detection of the OHT sheet can be prevented.

<Second Embodiment> FIG. 4 is a diagram showing a configuration of an image forming apparatus according to a second embodiment, FIG. 5 is a block diagram showing a configuration relating to control of the image forming apparatus according to the second embodiment, and FIG. FIG. 7 is an explanatory diagram of detecting a sheet thickness curl amount of a transfer sheet according to a second embodiment;
7 to 9 are other configuration block diagrams related to control of the image forming apparatus according to the second embodiment, FIG. 10 is an explanatory diagram of a prediction of a change in humidity according to the second embodiment, and FIG. FIG. 4 is another configuration block diagram related to control of the image forming apparatus.

As shown in FIG. 4, an operation panel 92 is a panel for operating the image forming apparatus, and includes a power supply operation unit 34, a copy start input, and the like.

The automatic document feeder 44 includes a document table 41
This is a device for automatically supplying a document placed on a document. Also,
The image reading means 42 moves the optical system to read the image
Means for reading.

The image forming section 46 includes a well-known image writing section 4.
5, a photoconductor 47, a charging electrode 48, a developing device 49, a transfer electrode 50, a separation electrode 51, a fixing device 61, and the like. The image writing unit 45 emits light from the semiconductor laser and scans and exposes the photosensitive member 47 via a polygon mirror. Developing device 4
9 develops the toner. Further, the fixing device 61 includes a heating roller and a pressure roller, and the toner powder for forming the toner image is melted and fixed on the transfer paper P by the heat and pressure of the pair of rollers.

The cleaning means 52 is provided for the photosensitive member 4 after the transfer.
7 is a means for cleaning the surface. The first tray 57, the second tray 58, the third tray 59, and the manual tray 62 are trays for storing plain paper, thick paper, and the like.

The first roller (registration roller) 71 is a roller that temporarily stops the transfer paper P, is fed by the start of rotation, and enters the transfer area in synchronization with an image area having a toner image.

The transfer electrode 50 is an electrode for transferring the toner image to the transfer paper P, and the separation electrode 51 is an electrode for separating the toner image from the surface of the photosensitive member 47.

When image formation is performed on both sides of the transfer paper P, the passage switching means 56 is a switching means for turning the transfer paper P recorded on one side downward after passing through the fixing device 61. The transfer paper reversing means 60 reverses the transfer paper fed toward the first roller 71 such that the unrecorded surface of the transfer paper is on the upper side. The paper discharging means 55 is means for discharging the transfer paper to the discharge tray 63.

The OHT detecting section 3 detects a presence or absence of an OHT sheet, the plain paper detecting section 1 detects a plain paper, and the regular / diffuse reflected light component detecting section 22 includes specular reflected light component and diffuse reflected light component. The sensor that detects the component, and the humidity detection unit 32 is a sensor that detects the humidity in the device. The curl amount detection unit 18 is a detection unit that detects the curl amount of the transfer paper. A schematic process for forming an image is the same as that in the first embodiment, and a description thereof will be omitted.

Next, a configuration block relating to control of the image forming apparatus according to the fifth aspect of the present invention will be described with reference to FIG. As shown in FIG. 5, the paper size detecting section 19 is a detecting section for detecting the paper size, and the curl amount detecting section 18 is a detecting section for forming a curl on the transfer paper and detecting the curl amount. Further, the paper thickness calculating means 20 includes the curl amount detecting unit 1.
The paper thickness is selected by a look-up table created in advance based on the amount of curl by No. 8 and the size of the transfer paper by the paper size detector 19, which will be described in detail later.

The sixth control means 21 controls the image formation by setting the process conditions based on the paper thickness selected by the paper thickness calculation means 20. The CPU 8B is a central processing unit that controls the paper thickness calculating means 20 and the sixth control means 21 described above. The image forming unit 12 forms an image.

Here, a method of obtaining the above-mentioned paper thickness will be described with reference to FIG. 6 as an example, in the case of a thick paper having a size smaller than B4 size. During the transfer of the transfer paper P having a size smaller than the B4 size, after the leading end Pa of the transfer paper P abuts against the stopped first roller pair 71, the transfer paper P is kept for a predetermined time.
The rear end side Pb is conveyed by the second roller pair 72 to form a curl C. Next, the curl amount detection unit 18 irradiates light from the side of the transfer paper P by the light emitting unit 18a and the light receiving unit 18b in a non-contact manner, and detects the curl amount h = 4 mm, which is the maximum height of the curl C of the transfer paper P. I do.

As a detection of the paper size, a case where a load is applied only to the second roller pair 72 after the transfer paper abuts against the first roller pair 71 in the second roller pair 72 and the third roller pair 73. Is paper size B4 or smaller,
If the load is also applied to the roller pair, the paper size is B4
Judgment is over.

As described above, the thickness of the transfer paper is determined by the look-up table shown in Table 1 prepared using the curl amount and the paper size as parameters.

[0064]

[Table 1]

The look-up table shown in Table 1 above is
For example, it is created in advance based on the following data. B
If the size is smaller than 4 sheets, the thick paper has a strong paper strain, so the second roller 72 slightly slips on the thick paper, and the loop amount becomes smaller than that of the plain paper. In the case of thick paper of B4 size or larger, the rear end of the paper is applied to the third roller 73. In this case, the third
The load of the roller 73 becomes a brake, and the loop amount h is 3 mm.
It becomes smaller as follows. A look-up table is created based on the above data.

Next, the main operation of the image forming apparatus of the present invention will be described. While the transfer paper P is being conveyed by the curl forming mechanism, the front end of the transfer paper P is once stopped by the first roller pair 71, and then the rear end of the transfer paper P is moved to the second roller for a predetermined time. The transfer paper P is conveyed in pairs 72 to form a curl C of the transfer paper P. Next, the curl amount detector 18 detects the loop amount h of the curl C formed by the curl forming mechanism. Further, the paper size of the transfer paper P is detected by the paper size detection unit 19. Here, the thickness of the transfer paper is obtained by the paper thickness calculation means 20 from the look-up table shown in Table 1 based on the loop amount h and the paper size. Next, based on the thickness of the transfer paper obtained by the paper thickness calculating means 20, the sixth control means 21 writes an image under process conditions in which a transfer current, a separation potential and a fixing speed are set.

Next, a description will be given, with reference to FIG. 7, of a configuration block relating to the control according to the sixth aspect of the present invention. As shown in FIG. 7, the specular / diffuse reflected light component detection unit 22 is a detection unit that detects a specular reflection light component and a diffuse reflection light component of the transfer paper, respectively. The gloss of the transfer paper is calculated from the result of the detection unit. The calculation is performed using the calculation formula s / d, where s is the specular reflected light component and d is the diffuse reflected light component.

Further, the seventh control means 24 controls the image formation by setting the process conditions based on the glossiness calculated by the glossiness calculation means 23. Further, the CPU 8
C is a central processing unit that controls the glossiness calculating means 23 and the seventh control means 24. The image forming unit 12 forms an image.

Here, the main operation of the image forming apparatus of the present invention will be described. The positive / diffuse reflected light component detection unit 22 detects the LE
D light is applied to the glossy paper and received by the photodiode.
The specular reflection component and the diffuse reflection component are obtained. Next, the glossiness calculating means 23 calculates the glossiness (s / d) based on the result of the regular reflection light component s and the diffuse reflection light component d. Further, based on the glossiness by the seventh control means 24,
An image is formed under process conditions in which a transfer current and a separation potential are set.

Next, a configuration block relating to the control of the seventh aspect of the present invention will be described with reference to FIG. As shown in FIG. 8, the print dot number detection unit 25 is a detection unit that detects the number of print dots, and the toner amount calculation unit 26 calculates the toner amount. The consumed toner amount is calculated based on the number of print dots counted for each print by the print dot number detection unit 25.

The print number accumulating section 27 is an accumulating section for accumulating the number of prints. Then, the average toner consumption per print is calculated by integrating and averaging. The eighth control means 29 is the calculation means 2
Based on the result of No. 8, the process conditions are set to control the image formation. It should be noted that the CPU 8D is a
6. A central processing unit that controls the calculating means 28 and the eighth control means 29. The image forming means 12 forms an image according to the process conditions of the eighth control means.

Here, the main operation of the image forming apparatus of the present invention will be described. The number of print dots is detected by the number-of-print-dots detection unit 25, the number of print dots D for each print is referred to by the toner amount calculation unit 26, and the toner amount T (= Dα) is calculated. Next, the number of prints is integrated by the print number integrating unit 27, and the consumed toner amount is integrated during the predetermined print based on the toner amount T calculated by the calculation unit 28 and the counted number of prints. This is referred to as STp. The average toner consumption Tave per print (= STp / P) is obtained by dividing the integration by the number of prints Pr and averaging.
r) is calculated. The eighth control means 29 determines the process conditions from a two-dimensional correction table including the average toner consumption Tave, the charge potential, and the correction amount of the developing bias, and controls the withstand voltage and the developing bias based on the determined conditions. Perform formation.

Next, a configuration block relating to the control of the eighth aspect of the present invention will be described with reference to FIG.
As shown in FIG. 9, the time measuring unit 31 is a measuring unit that measures time, and the humidity detecting unit 32 is a detecting unit that detects the humidity around the image forming apparatus. It is preferable that the humidity detecting section 32 is attached to a position which is not affected by printing or the operation state of the apparatus. The humidity transition storage means 33 is a time measurement unit 31
Power of the image forming apparatus is turned on based on the
The humidity is detected at a predetermined cycle based on the humidity and time at the time of the start, and the data of the elapsed time and the humidity are stored as humidity transition data as needed.

The power operation section 34 is a power operation section for turning on / off the power of the image forming apparatus. The humidity transition estimating means 35 is a power operation section 34, a time measurement section 31, a humidity detection section 32, and a humidity transition storage. Based on the means 33, the time and humidity at which the power of the image forming apparatus is turned on, and the humidity transition data, the subsequent humidity transition around the image forming apparatus is predicted.

The ninth control means 36 controls the image formation by setting the process conditions based on the predicted result of the humidity. The CPU 8E is a central processing unit that controls the humidity transition storage unit 33, the humidity transition prediction unit 35, and the ninth control unit 36. The image forming unit 12 forms an image.

Next, the main operation of the image forming apparatus of the present invention will be described. A time measuring unit 31 measures a time described later,
The humidity detecting section 32 detects the humidity around the image forming apparatus. Next, the humidity transition storage unit 33 detects the humidity at a certain point in time with a cycle of 5 minutes based on the humidity and the time when the power of the image forming apparatus is turned on, and stores the elapsed time and the data of the humidity. It is stored and stored as humidity transition data at any time. The storage ends when the change in the humidity reading falls within 5% for 30 minutes. The humidity transition data is always stored for the last 20 times. Next, when the power supply of the image forming apparatus is turned on, the difference between the start time and the humidity from the past 20 pieces of humidity change data based on the time and the humidity when the power of the image forming apparatus is turned on, The least data is extracted and used as humidity transition data. Based on this humidity transition data, the execution interval is determined depending on whether or not the subsequent humidity change is large. For example, as shown in FIG. 10, if the present time is point A shown in the figure, every 50 prints, and if point B, every 200 prints. The toner density is controlled in consideration of its responsiveness so that the target density is corrected at the predicted humidity after 10 minutes.

Next, the ninth control means 36 sets a response such as an execution interval of a test (also referred to as a patch test) using a test pattern and a target density of toner in accordance with the magnitude of the change in humidity based on the predicted data. The control is performed with respect to the control parameter having a weak characteristic to form an image.

Next, a description will be given of a configuration block relating to a control according to another eighth aspect of the present invention with reference to FIG. As shown in FIG. 11, the pause time calculating means 38 calculates the pause time during which the power is off from the power-off time and the power-on time. Developing unit empty number determination means 3
Reference numeral 9 denotes a unit that determines the number of idle times of the developing device based on the pause time by the pause time calculation unit 38. Further, the CPU 8F includes a humidity transition storage unit 33, a humidity transition prediction unit 35, and a tenth transition unit.
Is a central processing unit that controls the control means 16, the idle time calculation means 38, and the developing device empty number determination means. The image forming unit 12 forms an image.

Next, the main operation of the image forming apparatus will be described.
The time is measured by the time measuring unit 31, and the humidity around the image forming apparatus is detected by the humidity detecting unit 32. The humidity transition storage unit 33 detects the humidity in a 5-minute cycle based on the humidity and time when the power of the image forming apparatus is turned on, stores the elapsed time and the data of the humidity as humidity transition data. Remember. Next, when the power of the image forming apparatus is turned on by the power supply operation unit 34, the time measurement unit 31, and the humidity detection unit 32 by the humidity transition prediction unit 35,
Based on the time and the humidity, the data having the smallest difference between the time and the start humidity is extracted from the past 20 data and used as the prediction data. Based on the humidity transition data after the previous power-on, the subsequent humidity transition around the image forming apparatus is predicted.

Further, while the power is on, the time is stored in a non-volatile memory in a one-second cycle, and the pause time calculating means 38 subtracts the power-off time from the power-on time.
The pause time during which the power was turned off is calculated. In consideration of the change in the characteristics of the toner in the developing device according to the idle time, if the idle time exceeds a certain threshold value, the idle operation of the developing device is performed to recover the toner characteristics. Even if the threshold value is not exceeded, the target toner density is corrected according to the pause time. By the tenth control means 16,
Based on the prediction data obtained by the humidity transition prediction means 35, control is performed on control parameters with low responsiveness, such as the patch detection execution interval and the target density of toner, in accordance with the magnitude of the change in humidity.

[0081]

According to the above configuration, the following effects can be obtained. According to the first aspect of the present invention, when the thick paper mode is set, the image is formed under the process conditions for the thick paper without performing the automatic detection of the OHT sheet. An image forming apparatus capable of eliminating erroneous detection by the detection unit can be provided.

According to the second aspect of the invention, when the double-sided printing mode is set, the image is formed under the process conditions for the double-sided printing mode without performing the automatic detection of the OHT sheet. In addition, it is possible to provide an image forming apparatus that can eliminate erroneous detection of the OHT detection unit in the duplex printing mode.

According to the third aspect of the present invention, when the paper size setting is other than the A4 size or the letter size, the automatic detection of the OHT sheet is not performed.
It is possible to provide an image forming apparatus capable of eliminating erroneous detection by the OHT detection unit other than the medium size or the letter size.

According to the fourth aspect of the present invention, when the medium is automatically detected as an OHT sheet during printing in the duplex printing setting, a warning is displayed and the printing operation is stopped. An image forming apparatus that prevents double-sided printing on a sheet can be provided.

According to the seventh aspect of the present invention, since the thickness of the transfer sheet is detected from the curl amount and the size of the transfer sheet, and the process conditions based on the sheet thickness are set, the image is formed. The operation is simplified by automatically detecting the thick paper with. Further, for example, even if another user forgets to insert thick paper into the apparatus, it is possible to provide an image forming apparatus capable of obtaining a desired print.

According to the eighth aspect of the present invention, since the glossiness of glossy paper is detected and a process condition based on the glossiness is set to form an image, the glossiness is automatically detected in the apparatus. The operation is simple. Also, for example, it is possible to provide an image forming apparatus capable of obtaining a desired print even when another user forgets to insert glossy paper into the apparatus.

According to the ninth aspect of the present invention, an image is formed by changing the process conditions based on the result of the average toner consumption per print, so that the tendency of the printing rate of the image forming apparatus is reduced. By grasping and changing the process conditions such as the developing bias charging potential, it is possible to provide an image forming apparatus capable of outputting a stable image regardless of how the number of print dots is used.

According to the tenth aspect of the present invention, based on the time and humidity when the power of the apparatus is turned on and the previous humidity transition data, the subsequent humidity transition around the apparatus is predicted, and the process conditions are determined. Since image formation is performed by setting, an image forming apparatus that can stabilize image quality without being affected by a change in humidity around the apparatus can be provided.

[Brief description of the drawings]

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

FIG. 2 is a configuration block diagram related to control of the image forming apparatus according to the first embodiment.

FIG. 3 is a main operation flowchart of the image forming apparatus according to the first embodiment.

FIG. 4 is a diagram illustrating a configuration of an image forming apparatus according to a second embodiment.

FIG. 5 is a configuration block diagram related to control of an image forming apparatus according to a second embodiment.

FIG. 6 is an explanatory diagram of detecting a sheet thickness curl amount of a transfer sheet according to a second embodiment.

FIG. 7 is another configuration block diagram related to control of the image forming apparatus according to the second embodiment.

FIG. 8 is another configuration block diagram related to control of the image forming apparatus according to the second embodiment.

FIG. 9 is a block diagram illustrating another configuration related to control of the image forming apparatus according to the second embodiment.

FIG. 10 is an explanatory diagram of prediction of a change in humidity according to the second embodiment.

FIG. 11 is a block diagram illustrating another configuration related to control of the image forming apparatus according to the second embodiment.

[Explanation of symbols]

 Reference Signs List 3 OHT detection unit 4 Cardboard mode setting unit 5 Second control unit 6 Third control unit 9 Double-sided printing mode setting unit 11 Fourth control unit 14 Paper size setting unit 15 Fifth control unit 18 Curl amount detection unit 19 Paper size detection unit 20 Paper thickness calculation unit 21 Sixth control unit 22 Regular / diffuse reflection light component detection unit 23 Gloss degree calculation unit 24 Seventh control unit 25 Print dot number detection unit 27 Print number integration unit 26 Toner amount calculation Means 28 Calculation means 29 Eighth control means 34 Power supply operation unit 31 Time measurement unit 32 Humidity detection unit 33 Humidity transition storage means 35 Humidity transition prediction means 36 Ninth control means

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2H027 DA14 DA38 DA40 DC00 DC02 DC10 DC19 DD02 DE02 DE07 DE10 ED08 EE05 EE08 EF01 EF02 EH10 FA05 FA11 FA30 GA30 2H028 BB00 BB08 2H072 AA01 AA11 AA22 AB17 HA07 HA08 BB03 BB03 HH34 JJ35 KK42 LL09

Claims (11)

[Claims] When a plain paper is detected by a plain paper detecting unit, first control means for controlling image formation under normal plain paper process conditions and an OHT sheet are automatically detected by the OHT detecting unit. If detected, the second control means for controlling the image formation under the process conditions for the OHT sheet different from the normal, a thick paper mode setting section for setting a thick paper mode, and the thick paper mode setting section A third control unit for controlling image formation under the thick paper process condition when the mode is set, and automatically detecting the OHT sheet when the thick paper mode is set. An image forming apparatus which is not implemented. 2. When the OHT sheet is automatically detected by an OHT detection unit, a second control unit for controlling image formation under an unusual OHT sheet process condition and a duplex printing mode are set. A double-sided print mode setting unit, and a fourth control unit that controls image formation under process conditions for the double-sided print mode when the double-sided print mode is set by the double-sided print mode setting unit,
If the duplex printing mode is set, the OHT
An image forming apparatus that does not perform automatic sheet detection. 3. A second control means for controlling image formation based on an OHT sheet process condition when an OHT sheet is automatically detected by an OHT detection unit, and a paper size setting unit for setting a paper size. A fifth control unit for controlling image formation under a predetermined paper size process condition when the paper size is set by the paper size setting unit;
An image forming apparatus which does not automatically detect the OHT sheet when the paper size setting is other than A4 size or letter size. 4. When the OHT sheet is automatically detected by an OHT detection unit, a second control unit for controlling image formation under an unusual OHT sheet process condition and a duplex printing mode are set. A double-sided printing mode setting unit; and a fourth control unit for controlling image formation under double-sided printing process conditions when the double-sided printing mode setting unit sets the double-sided printing mode. The duplex mode is set by the print mode setting unit. If the medium is automatically detected as the OHT sheet during printing in the duplex mode, a warning is displayed on the warning display unit and the printing operation is performed. The image forming apparatus. 5. When the OHT sheet is automatically detected by the OHT detection unit, a second control unit for controlling image formation under an unusual OHT sheet process condition and a duplex printing mode are set. A double-sided printing mode setting unit; and a fourth control unit for controlling image formation under double-sided printing process conditions when the double-sided printing mode setting unit sets the double-sided printing mode. The duplex mode is set by the print mode setting unit. If the medium is automatically detected as an OHT sheet by the OHT detection unit during printing in the duplex mode, a warning is displayed on the warning display unit. And an image forming apparatus for temporarily suspending the printing operation and, when an instruction to continue the printing operation is issued, continuing the printing operation. 6. The OHT sheet according to claim 1, wherein the position of the OHT detection unit is located upstream of an image writing start position of the first color, and the OHT sheet can be automatically detected before image writing. The image forming apparatus according to any one of claims 1 to 5, wherein 7. A curl forming device for transporting the transfer paper to form a curl of the transfer paper by transporting the rear end of the transfer paper for a predetermined time after stopping the front end of the transfer paper for a predetermined time. A mechanism, a curl amount detecting unit for detecting a curl amount formed by the curl forming mechanism, a paper size detecting unit for detecting a paper size of the transfer paper, a curl amount detected by the curl amount detecting unit, and the paper size. Paper thickness calculating means for calculating the thickness of the transfer paper based on the paper size detected by the detection unit; and controlling the image formation by a process condition based on the thickness of the transfer paper determined by the paper thickness calculation means. An image forming apparatus comprising: a sixth control unit that performs the control. 8. A specular / diffuse reflected light component detection unit for detecting a specular reflection light component and a diffuse reflection light component of the transfer paper, respectively, An image forming apparatus comprising: a glossiness calculating means for calculating glossiness; and a seventh control means for controlling image formation based on a process condition based on the calculated glossiness. 9. A print dot number detection unit for detecting the number of print dots, and a toner amount calculation unit for calculating, for each print, the amount of toner consumed based on the number of print dots detected by the print dot number detection unit. A print number accumulating unit for accumulating the number of prints, and an average toner consumption per print by accumulating and averaging the toner amount during a predetermined print based on the calculated toner amount and the integrated print number. An image forming apparatus comprising: a calculating unit configured to calculate a value; and an eighth control unit configured to control image formation based on a process condition based on a calculation result of the calculating unit. 10. Turning on / off a power supply formed in an image forming apparatus
A time measuring unit that measures the OFF time, a humidity detecting unit that detects the humidity around the image forming apparatus, and a humidity detecting unit that detects the humidity at a predetermined cycle based on the humidity and the time when the power is turned on. A humidity transition storage means for storing the elapsed time and humidity data as humidity transition data at any time;
A power operation unit for performing N / OFF operation, a time at which the power is turned on, a humidity, and a humidity for predicting a subsequent humidity transition around the image forming apparatus based on the stored humidity transition data after the previous power-on. An image forming apparatus comprising: a transition estimating unit; and a ninth control unit that controls image formation based on a process condition based on a humidity estimation result by the humidity transition estimating unit. 11. An idle time calculating means for calculating an idle time during which the power is OFF from a power OFF time and an ON time of the power supply, and a developing device empty for obtaining the empty frequency of the toner in the developing device based on the idle time. A number-of-times determining means, and a tenth control means for controlling image formation based on a process condition based on the result of the humidity estimation by the humidity transition estimating means and the number of emptying times of the developing device by the number of emptying times of the developing device. The image forming apparatus according to claim 10, wherein: