JP2000181295A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of an increase in the burden of a cleaning section and the degradation in productivity even in the case of a cover mode by excluding the cover output in the cover mode from a count number of sheets for measurement of reference pattern forming intervals. SOLUTION: This apparatus has a function to hold prescribed paper into the tops of respective sections in the case of copying of the plural parts of plural sheets of originals. For example, the paper for copying an ordinary image is set in the first stage of a paper feed cassette and the paper for the cover is set in a manual insertion feed section 22 and before the ordinary image is outputted, the paper for the cover is outputted from the manual insertion feed section 22. When the cover mode is used, the reference pattern formation intervals are made shorter by as much as the number of sheets of the cover and the burden to the cleaning section is increased. The number of sheets of the display output considered to be low in an image ratio in the case of outputting of the cover at the time of the cover mode is, thereupon, precluded from the count number of sheets for the measurement of the reference pattern forming intervals. As a result, the reference pattern forming intervals are made longer and the increase in the burden on the cleaning section is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile or the like using an electrophotographic system, an electrostatic latent image of a reference pattern is formed on an image carrier (photoreceptor) and developed by a developing device. A method of controlling the image density by detecting the density of the visualized image with a reflection type photo sensor (P sensor) has been conventionally known.

In this image density control method, since a toner image is actually formed on an image carrier, it is easy to correct environmental factors and the like, but it is not mounted on a recording paper (recording on a recording paper). Since there is a toner image (not transferred) which needs to be cleaned, a load is imposed on the cleaning unit of the apparatus. In addition, it takes a certain time or more to create and detect a reference pattern image for controlling image density at the time between sheets during image formation.

[0004]

In recent years, as an additional function of the image forming apparatus, there is a cover mode in which a predetermined sheet is inserted at the head of each section when outputting a plurality of copies. For example, there is a usage method in which colored paper is set in a specific paper feed tray (cassette) and is fed as a cover.

Normally, the density detection of the reference pattern in the image density control method is performed every time a predetermined number of sheets are output. In this case, if the cover output in the cover mode is counted as the predetermined number of the reference pattern density detections, the detection interval becomes shorter by that amount, which causes an increase in the load on the cleaning unit and a decrease in productivity.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the conventional image forming apparatus and to provide an image forming apparatus which does not cause an increase in the load on the cleaning unit and a decrease in productivity even when the cover mode is used. And

[0007]

According to the present invention, there is provided an image carrier comprising an image carrier, a predetermined reference pattern formed on the image carrier, and the density thereof is detected by optical detection means. The image forming apparatus for controlling the density has a cover mode in which a cover is inserted at the head of the output, and this is solved by excluding the cover output in the cover mode from the sheet count for measuring the reference pattern creation interval.

In order to solve the above-mentioned problems, the present invention has a cover mode having a mode for forming an image on a cover and a mode for not forming the cover. It is proposed to add the cover output in the mode to the sheet count for measuring the reference pattern creation interval.

In order to solve the above-mentioned problem, the present invention has a stamp function for forming a predetermined image on all output sheets including a cover in the cover mode, and a stamp function in the cover mode. When used, it is proposed to add the cover output to the number of sheets for measuring the reference pattern creation interval.

Further, in order to solve the above-mentioned problem, the present invention has a stamp function for forming a predetermined image on all output sheets including a cover in the cover mode. When the stamp function is used in the cover mode when the data amount can be detected or registered, when the data amount of the stamp image is equal to or less than a predetermined amount, the cover output is excluded from the sheet count for measuring the reference pattern creation interval. Suggest to do.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of a digital copying machine according to an embodiment of the present invention. The digital copying machine shown in FIG. 1 includes a main body 1, a paper feed unit 2, an operation unit 3, an automatic document feeder (ADF) 4, and the like.

The main body 1 includes an image reading section and an image forming section. The image reading unit used in the digital copying machine of the present embodiment is a device having a function of irradiating a document with a light source, converting reflected light into an electric signal by a solid-state imaging device (CCD), and performing necessary image processing. It is. The image forming unit according to the present embodiment is an apparatus that forms an image image transmitted as an electric signal on a recording medium (transfer paper or the like) by an electrophotographic method. In addition, as an image forming method in the main body 1, in addition to electrophotography, a heat-sensitive method, a thermal transfer method,
An ink jet system or the like can be used.

A major feature of the digital copying machine according to the present embodiment is that when an image is converted into an electric signal and read, and when the electric signal is restored by the image forming unit, various changes occur.
By having a means for transmitting, it is possible to apply to uses other than the copying machine. The present embodiment also has functions as a facsimile and a printer in addition to a copying machine. In addition, the application range is very wide, such as a scanner (image reading device) and a filing system. Here, these extended functions are expressed as “applications”.

FIG. 2 is a plan view schematically showing the operation section (operation panel) 3. On the operation panel, a liquid crystal display 31 is arranged at the center, and numeric keys 32, a start key 33, a program registration / call key 34,
An application switching key 35 and the like are provided.
The numeric keypad 32 is used to make various settings and to assign a copy mode program. Start key 33
Is a key for instructing start of copying and the like. The program registration / call key 34 is used for registering and calling a program mode. Application switching key 35
Is a key for switching to each application of copy, facsimile, and printer, and transfers the operation unit display right to the application corresponding to the pressed key.

On the left side of the liquid crystal display 31, there are provided an initial setting key 36, a facsimile shortcut key group 37 and the like. The initial setting key 36 is a key used when performing initial setting. The FAX shortcut key 37 is used to assign a program in the facsimile mode.

Here, the initial setting is to change the initial setting value of each function or to set operation conditions in accordance with frequently used conditions. "Initial settings" include "system initial settings" for setting the functions of the copier system in general, "copy initial settings" for the copy mode functions only, and "fax initial settings" for the facsimile mode functions only. There is. For example, “system initial setting” includes “auto clear time setting” that returns to a state when the power is turned on when no operation is performed for a fixed time after a key operation. The "Initial Copy Settings" includes "Set Copy Set Limit", which changes the upper limit of the number of copies that can be set, and "Duplex Left Bind," which allows you to set the left binding margin on the back side in "Simplex → Duplex" copy Width ". "Fax initial setting" includes "receiving time printing setting" for selecting a function for printing the reception time, "destination registration" for registering a frequently used fax number of a partner, and the like.

In recent digital copiers, not only one application but also a plurality of applications have been installed simultaneously. This embodiment also has a copying machine, a facsimile, and a printer function. Functional units shared by multiple applications are expressed as "resources". A digital copying machine that shares one resource as in this embodiment is referred to as a “system”, and a controller that controls this system is referred to as a “system controller (system control)”. The system controller controls the system in resource units, and the resources managed by the digital copier include an image reading unit (image reading device), an image forming unit (image forming device), an operation unit, a memory, and a peripheral device (document feed). Equipment, sorters, etc.).

In this embodiment, in order to configure a multitasking system, functional units are treated as resources, and management for sharing one resource by a plurality of applications is performed. FIG. 3 shows a configuration example of system software according to the present embodiment.

In the block diagram of FIG. 3, the device control layer drives mechanical inputs / outputs such as clutches, sensors, and motors to actually operate the apparatus from logical instructions such as commands and control signals from the system control layer.・ The input is being converted. The application layer is a layer in which a plurality of applications such as a copy, a printer, and a facsimile can coexist as extended functions by a function provided from the system control layer.

The electric signal of the image converted by the image reading unit, the electric signal of the image input to the image forming unit, and the signal for synchronizing with the electric signal of the image are collectively referred to as “video”. Signal ”. And
In order to exchange a video signal between an image reading unit, an image forming unit, and an application, it is necessary to transmit information between the units, and a means for realizing this is expressed as "control signal" or "command" issuance.

FIG. 4 is a block diagram showing a configuration example of system hardware according to the present embodiment. As shown in this figure, in this embodiment, a CPU is provided for each application, and a system control layer and a device control layer
(System controller 10). Copy application 11, Printer application 12, FAX application 13
Each application and the image forming unit (image forming apparatus in the figure) and the image reading unit (image reading apparatus in the figure) of the main body
Are connected by an image forming signal bus 14. The operation unit of the main body and each application are connected by an operation unit control bus 15 for controlling the operation unit. The key card device is connected to the main body 1 by a control signal line 16, and in this embodiment, serial communication is used.

A hardware configuration is also possible in which a CPU is provided for each application, system control, and each resource, and a command from the system controller to each controller is transmitted through a control signal line. Further, it is possible to control the operation unit by exchanging commands using the control signal line 16. As described above, since the system hardware configuration can be freely configured, the configuration for realizing the system software in FIG. 3 is not particularly limited.

FIG. 5 is a block diagram showing the relationship between the application layer and the system control layer. The system control layer provides a function such that virtual resources exist individually for all applications when viewed from the application layer. With this function, it is not necessary to manage the system state in the application layer, and all the applications can be managed under the same condition in the system control layer. That is, the application sends a use request to the system control when a resource to be used occurs. In the system control, the result is sent to the requesting application, judging from the resource usage at that time.
The requesting application determines whether or not execution is possible based on the result, and if possible, executes the application. Basically, the execution right is managed by the same procedure.

In the configuration of FIG. 3, there is only one resource. For this reason, in the system control, when virtual resource use requests for each application conflict, it is necessary to perform exclusive control or time-division allocation in order to pass the actual resource use right. Whether to perform exclusive control or time-division allocation depends on the type of resource and user settings.

In FIGS. 6 and 7, the resources surrounded by broken lines are virtual resources, and are in a state where the execution right (display right in the case of the operation unit) is not taken. On the other hand, resources surrounded by solid lines indicate a state in which the execution right has been obtained.

FIG. 6 is a block diagram showing the interleaving operation between the copy application and the printer application. Here, the interleaving will be described. Normal image output is a series of operations (1
No other operation is performed until the job (job) is completed. For example, in a digital copying machine, the functions are combined, and the copying machine + FA
X or a printer or more
Can be consolidated on a table. But most of them are
For example, output is performed in functional units (job units) so as to switch to printer output after the copy function ends. On the other hand, inserting another job output into one job output and outputting the job output is referred to as “interleave” or “insertion output”. For example, the printer output is realized without stopping the machine operation during the output of the copying function.

In FIG. 6, the copy application is being executed with the execution right for all of the "operation unit", "image forming unit", and "image reading unit" resources. At this time, if only a request to use the “image forming unit” resource is received from the printer application, the interleave
If the mode is set to be enabled, the system control controls the “image forming unit” resources in a time-sharing manner. The time-sharing allocation control dynamically changes the execution right of a resource among a plurality of applications. As a result, the output from the "image forming unit"
Application output and printer / application output are mixed and output. During this time, the "image forming unit" can be changed without stopping, so that the waiting time of both can be minimized.

In FIG. 7, the FAX application has the display right of the operation unit, and the printer application and the FA
9 shows the parallel operation of the X application. The FAX application uses, for example, only the “operation unit” and “image reading unit” resources in a facsimile transmission mode or the like.
On the other hand, a printer application requires only an “image forming unit” resource such as a printer output. Therefore, F
Even if the AX application and the printer application make a resource request at the same time, resource conflict does not occur, so there is no need to perform exclusive or time-division allocation, and it is possible to accept the requests of both applications. Therefore, the operations of the FAX application and the printer application can be performed at the same time.

Next, with reference to FIG. 8, a mechanism in which an image is formed on a transfer sheet and transported in the copying machine of the present embodiment will be described. FIG. 8 is a diagram for schematically explaining the machine layout of each part of the copying machine, and the arrangement of each device is not the same as the device overview diagram of FIG.

The laser light generated by the LD unit 52 is expanded to the width of the image by the polygon mirror 53,
An electrostatic latent image is formed on the photoreceptor 54, and a developing unit 55 forms a visible image by attaching toner to the latent image portion, and is sent to a transfer unit. On the other hand, the transfer paper is
1 and is stopped temporarily by a registration roller 51 via a registration sensor (not shown) in order to match the timing with the leading edge of the image. The paper temporarily stopped by the registration roller 51 is conveyed from the registration unit at the timing when the leading edge of the image on the photoconductor 54 reaches the transfer unit,
The image is transferred onto the sheet by the transfer unit 57, is fixed by heat and pressure when passing through the fixing unit 58, and is discharged by the discharge roller 59.

Next, image density control using the reflection type photo sensor (hereinafter, P sensor) 60 will be described. In order to perform image density control, first, a photoconductor 54 for forming an image is formed.
An electrostatic latent image having a predetermined pattern (image density control reference pattern) is formed thereon, and the latent image is developed by a developing unit 55 to form a toner image. At this time, the portion where the toner image is not formed and the portion where the toner image is formed are detected using the P sensor 60, and the toner density of the toner image created is calculated from the ratio of the output values. The image quality is maintained by replenishing a predetermined amount of toner from the toner bottle 56 to the main body of the developing device so that the toner density obtained becomes an appropriate toner density.

The formation of the reference pattern has negative factors such as a large load on a cleaning unit (not shown) of the photoconductor because the toner not transferred onto the paper is developed on the photoconductor. Therefore, by managing the number of sheets passed and creating a reference pattern each time a predetermined number of sheets are passed, the accuracy of image density control and the protection of the cleaning unit are compatible. The processing relating to this image density control is shown in the flowcharts of FIGS.

In the flowchart of FIG. 9, when a sheet is passed, the number of sheets is incremented (S1,
2) When the number of passed sheets reaches a predetermined number, a flag for creating a toner image as a reference pattern is turned on (S
4) The number of sheets is cleared (S5). Then, as shown in the flowchart of FIG. 10, it is determined whether the toner image creation flag is set or not (S
2) If the flag is set, a predetermined toner image creation routine is executed (S3), and the flag is cleared (reset) (S4).

Next, the cover function and the stamp printing function of the digital copying machine of the present embodiment will be described. The cover function is a function of inserting a predetermined sheet at the top of each copy when it is desired to copy a plurality of copies of a plurality of originals.
For example, a sheet for copying a normal image is set in the first stage of the sheet feeding cassette, a cover sheet (colored sheet, etc.) is set in the manual sheet feeding unit 22 (FIG. 8), and the normal image is copied. Before output, the cover paper is output from the manual paper feed unit. FIG. 11 shows ordinary output sheets P _{1 to} P ₃
Is shown with the cover sheet Ph sandwiched in front of. FIG. 11 shows a mode in which an image is not formed on the cover Ph, but there is also a mode in which an image is formed on the cover Ph, as shown in FIG.

The stamp printing function is a function for adding a predetermined image (for example, “confidential”) to all outputs. FIG. 13 shows an example in which stamp printing of “R” is performed in the cover mode in which no image is formed on the cover Ph. FIG. 14 shows an example in which stamp printing is performed in the cover mode in which an image is formed on the cover Ph.

As described above, the creation of the reference pattern for controlling the image density by the P sensor imposes a burden on the cleaning unit. Therefore, it is desirable to set the creation interval as long as possible. However, there is a concern that the accuracy of the density control may decrease when the creation interval is long. In addition, when the cover mode is used, the reference pattern creation interval is shortened by the number of cover sheets, and the load on the cleaning unit increases. Therefore,
According to the present invention, when outputting a cover in the cover mode, the number of cover output sheets whose image ratio is considered to be low is excluded from the number of sheets for measuring the reference pattern creation interval, thereby reducing the reference pattern creation interval. The length is made longer to prevent the burden on the cleaning unit from increasing.

FIG. 15 shows a flowchart of the sheet count exclusion processing at the time of output of a cover. In this flowchart, when a sheet is passed, it is determined whether or not the cover mode is set (S2), and if not, the passed sheet is added to the number of sheets (for measuring a reference pattern creation interval). (S3). In the case of the cover mode, it is further determined whether or not the passing is the output of the cover (S4). If the output is not the cover output, the number of sheets is added. If the output is the cover, the addition of the number of sheets is not performed. To do. This allows
The cover output can be excluded from the addition of the sheet count.

As described above, there are two types of cover modes: a mode in which no image is formed on the cover (see FIG. 11) and a mode in which an image is formed on the cover (see FIG. 12). When the cover output in the image forming mode is excluded from the addition of the sheet count, there is a concern that the accuracy of the image density control is reduced. Therefore, as a second embodiment of the present invention, it is proposed that the cover output is excluded from the sheet count for measuring the reference pattern creation interval only in the cover mode in which no image is formed on the cover.

FIG. 16 is a flowchart showing the processing in the second embodiment. In this flowchart, when a sheet is passed, it is determined whether or not the cover mode is set (S2), and if not, the passed sheet is added to the number of sheets (for measuring a reference pattern creation interval). (S3). In the case of the cover mode, it is further determined whether or not the passing is a cover output (S4). In the case of cover output, the presence or absence of an image is also determined (S5). If there is an image, the number of sheets is added. If there is no image, the number of sheets is not added. As a result, it is possible to prevent a decrease in the accuracy of the density control while increasing the creation interval of the reference pattern toner image.

Next, a third embodiment of the present invention will be described. As described above, there is a stamp mode in addition to the cover mode as an additional function in the digital copying machine. Although it is possible to exclude the cover output in the cover mode from the number of sheets for counting the reference pattern creation interval as described in each of the above embodiments, the cover mode (particularly, the cover mode for forming an image on the cover) is described. When the stamp mode is used in combination with the stamp mode, the number of toner images created increases accordingly, and when the cover output is excluded from the number of sheets for the reference pattern creation interval measurement, the density control is not performed. There is a concern that the accuracy may decrease. Therefore, in this embodiment, when the cover mode and the stamp mode are used in combination, the cover output is added to the number of sheets for the reference pattern creation interval measurement,
When the cover mode other than the stamp mode is selected, the cover output is controlled so as to be excluded from the sheet count for measuring the reference pattern creation interval.

FIG. 17 is a flowchart showing the processing in the third embodiment. In this flowchart, when a sheet is passed, it is determined whether or not the mode is the stamp mode (S2). If the mode is the stamp mode, the count is unconditionally added to the number of sheets for measuring the reference pattern creation interval (S4). . If the mode is not the stamp mode, it is determined whether the mode is the cover mode (S3). If the mode is not the cover mode, the process proceeds to S4, and the passing is added to the number of sheets (for measuring the reference pattern creation interval). In the case of the cover mode, it is further determined whether or not the passing is the output of the cover (S5). If the output is not the cover output, the number of sheets is added. If the output is the cover, the number of sheets is not added. To do. Thus, the density control can be reliably performed in any of the cover mode and the stamp mode.

Next, a fourth embodiment of the present invention will be described. When both functions of the cover mode and the stamp mode are provided, when an image is formed on the cover output in the cover mode, or in the case of a stamp image in the stamp mode, the image ratio of both images is smaller than that of the normal output. Conceivable. Therefore, if the number of sheets is added to the sheet count for measuring the reference pattern creation interval when these are output, the reference pattern creation interval is shortened by adding the number of sheets even though the toner image is small, and cleaning is performed. The burden on the department is disadvantageous. Therefore, in the present embodiment, when the cover mode and the stamp mode are used in combination, the data amount of the image formed on the cover output is measured or registered, and the image ratio (paper area) is calculated from the data amount. If the image ratio is equal to or less than a predetermined value, it is determined that the influence on the density control is small, and the cover output is excluded from the number of sheets for the reference pattern creation interval measurement. If the image ratio is larger than the predetermined value, the cover output is added to the number of sheets for measuring the reference pattern creation interval to ensure the accuracy of the density control.

FIG. 18 is a flowchart showing the processing in the fourth embodiment. In this flowchart, when a sheet is passed, it is determined whether or not the cover mode is set (S2), and if not, the passed sheet is added to the number of sheets (for measuring a reference pattern creation interval). (S3). In the case of the cover mode, it is further determined whether or not the passing is a cover output (S4). In the case of cover output, it is also determined whether or not the mode is the stamp mode (S5).
If the mode is not the stamp mode, the cover output is excluded from the number of sheets for counting the reference pattern creation interval. In the case of the stamp mode in cover output, it is determined whether the specific image data amount formed on the cover is equal to or less than a predetermined amount (S
6) If the image data amount is large, the cover output is added to the number of sheets, and if the image data amount is small, the cover output is excluded from the number of sheets. Thus, it is possible to realize the accuracy of the density control while suppressing an increase in the load on the cleaning unit.

Although the present invention has been described with reference to the four embodiments based on a digital copying machine, the present invention is not limited to the above embodiments. For example, the number and types of “applications” to be mounted are not limited to “copiers”, “printers”, and “facsimiles”. In addition, the configuration of the "image reading unit" and the "image forming unit" or the configuration example of the system hardware can be arbitrarily set. And if you limit to basic control in cover mode,
The present invention can be implemented in an analog system. For example, it is possible to exclude the cover output in the cover mode from the sheet count for measuring the reference pattern creation interval by the analog method.

[0045]

As described above, according to the image forming apparatus of the present invention, the cover output in the cover mode is excluded from the sheet count for measuring the reference pattern forming interval. The interval does not become short, and an increase in the load on the cleaning unit can be prevented.

According to the second aspect of the present invention, in the mode for forming an image on the cover, the output of the cover is added to the number of sheets for measuring the reference pattern forming interval, so that the cleaning unit can be used without lowering the accuracy of the density control. This can prevent the burden on the user from increasing.

According to the third aspect of the invention, when the stamp function is used in the cover mode, the output of the cover is added to the number of sheets for measuring the reference pattern creation interval. Is not reduced.

According to the fourth aspect of the present invention, when the stamp function is used in the cover mode, when the data amount of the stamp image is equal to or less than a predetermined amount, the cover output is excluded from the sheet count for measuring the reference pattern creation interval. Further, even when the stamp function is used, it is possible to prevent an increase in the load on the cleaning unit without lowering the accuracy of the density control.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall configuration of a digital copying machine according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of an operation unit in the copying machine according to the embodiment.

FIG. 3 is a block diagram illustrating a configuration example of system software according to the embodiment;

FIG. 4 is a block diagram illustrating a configuration example of system hardware according to the present embodiment.

FIG. 5 is a block diagram showing a relationship between an application layer and a system control layer.

FIG. 6 is a block diagram showing an interleaving operation between a copy application and a printer application.

FIG. 7 is a block diagram illustrating a parallel operation of a FAX application and a printer application.

FIG. 8 is a diagram schematically illustrating a machine layout of each part of the copying machine according to the embodiment.

FIG. 9 is a flowchart illustrating a process related to the number of copies in the image density control.

FIG. 10 is a flowchart illustrating a process for creating a reference pattern in image density control.

FIG. 11 is a schematic diagram illustrating functions in a cover mode.

FIG. 12 is a schematic diagram illustrating a function of a cover mode for forming an image on a cover.

FIG. 13 is a schematic diagram illustrating functions in a stamp mode.

FIG. 14 is a schematic diagram illustrating a combination of a cover mode and a stamp mode for forming an image on a cover.

FIG. 15 is a flowchart of a sheet count exclusion process at the time of output of a cover in the embodiment.

FIG. 16 is a flowchart showing a process according to the second embodiment of the present invention.

FIG. 17 is a flowchart illustrating a process according to the third embodiment of the present invention.

FIG. 18 is a flowchart illustrating a process according to the fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copier main body part 2 Paper supply part 3 Operation part 4 ADF 10 System controller 11 Copy application 12 Printer application 13 FAX application 21 Paper supply cassette 54 Photoreceptor 60 P sensor (reflective photo sensor)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/36 H04N 1/00 108M H04N 1/00 108 1/04 106A 1/04 106 G03G 21/00 382 F-term (reference) 2C061 AP04 AQ06 HH13 HJ06 HK15 HN15 KK03 KK18 KK25 KK32 2H027 DA09 DA46 EC20 EE02 EE07 EF06 EF09 FA30 5C062 AA05 AB22 AC10 AC60 AC61 AF07 BA06 5C072 AA03 X05

Claims (4)

[Claims] An image forming apparatus comprising an image carrier, forming a predetermined reference pattern on the image carrier, and detecting the density of the reference pattern by an optical detecting means to control the image density. An image forming apparatus having a cover mode in which a cover is inserted, wherein a cover output in the cover mode is excluded from the number of sheets for measuring the reference pattern creation interval. 2. The cover mode has a mode for forming an image on the cover and a mode for not forming the cover. In a mode for forming an image on the cover, the cover output in the cover mode is set to:
The image forming apparatus according to claim 1, wherein the count is added to a count of sheets for measuring the reference pattern creation interval. 3. A stamp function for forming a predetermined image on all output sheets including the cover in the cover mode. When the stamp function is used in the cover mode, the cover output is performed by the reference pattern. The image forming apparatus according to claim 1, wherein the image count is added to a sheet count for measuring a creation interval. 4. A stamp function for forming a predetermined image on all output sheets including the cover in the cover mode, wherein a data amount of the stamp image in the stamp function can be detected or registered. When using the stamp function in cover mode,
2. The image forming apparatus according to claim 1, wherein when the data amount of the stamp image is equal to or less than a predetermined amount, the cover output is excluded from the number of sheets for measuring the reference pattern creation interval.