JPH063891A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent an electrification defect, image defect, and image formation inability, etc., due to an image forming operation with a process cartridge attached unsatisfactorily or without the cartridge from being occurred, by securely detecting whether the cartridge is correctly attached to the device main body or not, in the image forming device of a process cartridge attachment/ detachment system where an electrifying process means is a contact electrification means and the electrifying member of this means is disposed on the device main body side. CONSTITUTION:The process cartridge 30 is provided with at least an image carrier 1. The image forming device main body 20 is provided with the electrifying member 2 which is in contact with or adjuscent to the image carrier 1 of the cartridge 30 attached to the device main body 20 and to which a voltage is applied by a voltage application means 3; and means 15 (16, 17 and 18) which detect electrical load when the voltage is applied to the electrifying member 2, and detects a state in which the cartridge is attached to the device main body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge removable image forming apparatus.

[0002]

2. Description of the Related Art In image forming apparatuses such as electrophotographic copying machines, printers, electrostatic recording devices, etc.
Exchange of image carrier such as electrophotographic photoreceptor and electrostatic recording dielectric,
Maintenance work such as replenishment of developer and cleaning of the corona discharge wire of the corona charger as a charging (or discharging) process means is required, but this maintenance work is easy for the user side without resorting to a service person. As a device configuration for enabling the above, it is possible to collectively attach and detach the image forming process equipment and parts that require periodical replacement and maintenance such as the image carrier, the developing device, and the corona charger to the image forming device body. The so-called process cartridge detachable image forming apparatus is widely used, which is configured as a process cartridge, and is replaced with a new cartridge when the service life of the cartridge is exhausted.

Even when the process cartridge is in the middle of its durability, the process cartridge is detachably attached to the apparatus main body when necessary for removing jammed paper from the inside of the image forming apparatus main body, maintenance and inspection of the inside of the main body of the apparatus.

In the image forming apparatus of the process cartridge detachable type, for example, several kinds of process cartridges having different developing colors are prepared and used by exchanging with the apparatus main body to change the developing color or form a multicolor image. Also has the advantage that it can be done easily.

Of all the image forming process equipment / parts constituting the image forming apparatus, the equipment / parts to be equipped on the process cartridge side should be replaced with the minimum necessary consumable exchange equipment / parts in terms of cost and development maintenance. It is also desirable from the viewpoint of.

In a conventional process cartridge detachable type image forming apparatus, the corona charger as a charging process means has a great influence on the image performance due to the contamination and deterioration of the corona discharge line due to the progress of the durability. It is a device to be equipped with.

By the way, as a charging process means in an image forming apparatus, a corona discharge wire, which has been generally used in the past, is provided, and the surface of the object to be charged is exposed to the discharge current from the corona discharge wire. In place of the corona charger, which is a non-contact charging system that charges the battery, it has the advantages of being able to lower the power supply voltage, generating less ozone, etc.
A contact charging type charging device has been put into practical use in recent years.

FIG. 3 shows a schematic structure of an example of the contact charging type charging device.

Reference numeral 1 denotes a member to be charged, which is, for example, a rotating drum type photosensitive member as a member to be charged in an electrophotographic copying machine. This photoconductor is rotationally driven in the direction of the arrow at a predetermined peripheral speed.

Reference numeral 2 denotes a charging roller as a charging member which is arranged in parallel with the photosensitive member 1 and is in pressure contact therewith.
It is composed of a conductive elastic layer 2b which is concentrically and integrally formed in a roller shape on the outer periphery thereof.

The charging roller 2 may be driven to rotate following the rotation of the photoconductor 1, or may be driven to rotate in the forward or reverse direction of the rotation of the photoconductor 1, or may be a non-rotating roller body. Is also good.

By applying a charging bias from the charging bias applying power source 3 to the charging roller 2 through the core metal 2a, the peripheral surface of the rotary photosensitive member 1 is of a contact type and has a predetermined polarity.
It is charged to the electric potential.

Although not shown in the drawing, in addition to the charging means 2 and 3, the necessary image forming process equipment such as an exposing means, a developing means, a transferring means, a cleaning means, a fixing means and the like are provided around the photosensitive member 1. Are arranged to form an image forming apparatus,
Image formation is executed.

As the mechanism of contact charging, dielectric breakdown of air mainly occurs in the minute gaps d and d in the vicinity of the contact portion N between the charging roller 2 and the photosensitive member 1, which causes the charging roller 2 to move to the photosensitive member 1. The charge is transferred to.

The charging member 2 is not limited to the roller type described above,
Various shapes such as blade type, pad type, block type, rod type, and brush type can be used.

As a bias applying method for the charging member 2, there are a DC applying method and an AC applying method.

The DC application method is a method in which only a direct current (DC) voltage is applied to the charging member 2 to charge the member 1 to be charged.

The AC charging method is a method in which an oscillating voltage alternating voltage (an alternating voltage, a pulsating voltage; a voltage whose voltage value periodically changes with time) is applied to the charging member 2 to charge the charged body 1. That is, the AC voltage component of the oscillating voltage has the effect of converging the potential of the charged body to the DC voltage component.

In particular, the present applicant has previously proposed (Japanese Patent Laid-Open No. 63-
149668/149669, etc.), a DC voltage and an AC voltage having a peak-to-peak voltage that is at least twice the charging start voltage of the surface of the member to be charged 1 when only the DC voltage is applied to the charging member 2 are superimposed. The method of applying an oscillating voltage to the charging member 2 to charge the surface of the member to be charged 1 allows uniform charging, and removes the exposure memory and transfer memory of the photoconductor 1 in the image forming apparatus. The effect is obtained.

The waveform of the oscillating voltage (or AC voltage component) is a sine wave (sine wave), a rectangular wave, a triangular wave, a sawtooth wave, a pulse wave, or the like, and is formed by periodically turning on and off a DC power supply. It may be a rectangular wave voltage.

The charging member 2 may be arranged so as to float from the surface of the body to be charged 1 in contact with the body 1 to be charged as long as there is a minute gap d between the body 1 and the body to be charged which may cause dielectric breakdown of air. Of course, in the present invention, such a configuration is also included in the contact charging type charging device.

In this contact charging type charging device, the conductive rubber roller, the conductive rubber blade or the like as the charging member 2 is much more durable against dirt and deterioration than the corona discharge line of the corona charger. The charging member 2 such as a conductive rubber roller is expensive as a single charging member.

Therefore, in the case of a process cartridge detachable image forming apparatus in which the contact charging type charging device is adopted as the charging process means, it is desirable that the charging member 2 is a device / member on the image forming apparatus main body side.

[0024]

In a process cartridge detachable image forming apparatus in which a contact charging type charging device is adopted as a charging process means of an image carrier such as a photoconductor or a transfer charging means of the back surface of a transfer material, When the charging member 2 of the charging means is disposed on the image forming apparatus main body side, the image carrier 1 on the process cartridge side and the charging member on the apparatus main body side in the state where the process cartridge is mounted on the image forming apparatus main body. The device is designed so that 2 and 1 are in pressure contact with each other, or both 1 and 2 are opposed to each other with a predetermined gap.

In the contact charging type charging device, the contact state between the charged member and the charging member or the facing distance state has a great influence on the charging performance. Therefore, when the process cartridge is not sufficiently (incompletely) attached to the image forming apparatus main body. Is incorrect in the contact state or the facing gap state between the image carrier 1 and the charging member 2, and if the apparatus performs an image forming operation in this state, a poor charging state or an image defect occurs, and eventually the image carrier 1
May be damaged.

Therefore, in this type of image forming apparatus, it is confirmed that the process cartridge is properly attached to the image forming apparatus main body, that is, the image carrier 1 on the process cartridge side and the charging member on the apparatus main body side. It is important to confirm that 2 and 1 are in pressure contact with each other, or that both 1 and 2 are facing each other with a predetermined gap, and the image forming operation of the apparatus is executed based on the confirmation. Is.

Therefore, the present invention reliably detects whether or not the process cartridge is properly attached to the apparatus main body (including the forgotten attachment state) in such a process cartridge detachable image forming apparatus. In this way, it is an object of the present invention to strictly prevent the occurrence of charging failure, image failure, etc. due to the image forming operation of the apparatus in a state where the cartridge is insufficiently mounted or a state where the cartridge is forgotten to be mounted.

[0028]

The present invention is an image forming apparatus having the following configuration.

(1) In the process cartridge detachable image forming apparatus, the process cartridge has at least an image carrier, and the image forming apparatus body is in contact with the image carrier of the process cartridge mounted on the apparatus body. It has a charging member which is in close proximity and to which a voltage is applied by a voltage applying means, and has means for detecting an electrical load when a voltage is applied to the charging member and detecting a mounting state of the process cartridge with respect to the apparatus main body. An image forming apparatus characterized by.

(2) The image forming apparatus described in (1) is characterized in that the detection of the electrical load is detection of a current flowing through the charging member when a voltage is applied to the charging member.

(3) The detection of the electrical load is a detection of an output current at that time by driving a constant current circuit which causes a preset current to flow through the charging member. Image forming device.

(4) When the detection means detects / determines that the mounting state of the process cartridge to the apparatus main body is uncertain or not mounted, the image forming process execution operation of the apparatus is prohibited. The image forming apparatus according to (1).

(5) The image forming apparatus according to (1), wherein the charging member is a charging process means for the surface of the image carrier.

(6) The image forming apparatus according to (1), wherein the charging member is a transfer charging unit that transfers the transferable image on the surface of the image carrier to the surface of the transfer material.

[0035]

When the process cartridge is properly attached to the main body of the image forming apparatus, that is, when the charging member on the apparatus main body and the image carrier on the process cartridge side are in a predetermined contact or close state, the charging is performed. The detected value of the electric load when a voltage is applied to the member, and the process cartridge is not completely attached to the apparatus main body or is not attached, that is, the charging member on the apparatus main body side and the image carrier on the process cartridge side are This is different from the detected value of the electric load when a voltage is applied to the charging member when not in a predetermined contact or close state.

Therefore, by detecting the electric load when a voltage is applied to the charging member, the process cartridge is correctly mounted, imperfectly mounted or not mounted on the apparatus main body. It is possible to accurately detect and judge whether or not it is in a state where it is not.

With this, it is possible to strictly prevent the occurrence of charging failure, image failure, image output failure, etc. due to the image forming operation of the apparatus being performed in a state where the process cartridge is not sufficiently mounted or forgotten to be mounted in the apparatus body. You can

[0038]

【Example】

<Embodiment 1> (FIG. 1) FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. The apparatus of the present embodiment is a process cartridge detachable laser printer using an electrophotographic process.

Reference numeral 20 is a printer main body, 30 is a process cartridge detachably mountable in the printer main body 20,
The opening / closing side plate 21 of the printer body 20 is opened to open the inside of the printer body 20, and the process cartridge 30 is guided / supported by a well-known guide mechanism (not shown) to be attached / detached.

The opening / closing side plate 21 is provided with a well-known door switch mechanism (not shown), and when the side plate 21 is opened, the power supply circuit (not shown) is kept off, and electrical / mechanical safety is ensured. Sex is secured.

The process cartridge 30 of this embodiment is
A rotating drum type electrophotographic photosensitive member 1 as an image carrier,
The three process devices of the developing device 5 and the cleaning device 7 are built in the cartridge housing 31 in a predetermined positional relationship, and the three devices 1, 5, and 7 are collectively included in the printer body 20.
It is removable. When the process cartridge 30 is mounted in the printer body 20, the process cartridge 30 is mechanically and electrically coupled to the printer body 20 side to be in a printer drivable state.

When the process cartridge 30 is properly installed in the printer body 20, the reference numeral 2 makes contact with the surface of the photoconductor 1 looking through the window hole 32 of the installed process cartridge 30 with a predetermined pressing force. A charging roller as a contact charging member. The charging roller 2 is a device provided on the printer body 20 side, is rotatably supported at its both ends by bearings, and is pressed against the surface of the photoconductor 1 by pressing means (not shown) to rotate the photoconductor 1. Followed by the rotation. Reference numeral 3 is a power source for applying a charging bias to the charging roller 2.

Reference numeral 4 denotes a laser scanner, which outputs a laser beam L modulated in accordance with a time-series electric digital pixel signal of desired image information from a host device such as an image reading device, a word processor, a workstation, etc., and a mirror 4
a. The surface of the photosensitive member 1 is scanned and exposed through the exposure window 33 of the process cartridge.

Reference numeral 6 denotes a transfer corona charger as a transfer means facing the lower surface of the photoconductor 1, and reference numeral 8 denotes a transfer bias application power source for the charger. Reference numeral 9 is a paper feed tray (or paper feed cassette), 10 is a paper feed roller, 11 and 12 are transfer material guides, 13 is an image fixing device, and 14 is a paper discharge tray.

When the main power switch (not shown) of the printer main body is turned on, the rotation drive of the photoconductor 1 (previous multi-rotation drive) is started, and the cartridge 30 is removed by the process cartridge mounting state detecting means 15 described later. It is detected / determined whether the printer is properly mounted in the printer body 20.

When it is detected / determined that the printer is properly mounted, the image forming process execution operation is started based on the subsequent input of the print start signal. That is, a charging bias is applied to the charging roller 2 from the power source 3,
The peripheral surface of the rotary photosensitive member 1 is uniformly subjected to primary charging treatment by a contact charging method to a predetermined polarity and potential.

Laser scanning exposure L is performed by the laser scanner 4 on the surface of the rotary photoconductor 1 subjected to the primary charging, and an electrostatic latent image corresponding to the target image information is formed on the surface of the rotary photoconductor 1. . Then, the latent image is developed by the developing device 5 as a toner image.

On the other hand, one transfer material is fed from the paper feed tray 9 by the paper feed roller 10, passes through the guide 11, and is provided between the photoconductor 1 and the transfer corona charger 6 by the resist means (not shown). Is fed to the transfer portion at a predetermined timing.

When the transfer material is fed to the transfer portion, a predetermined bias voltage is applied to the transfer corona charger 6 from the power source 8 so that the back surface of the fed transfer material is a toner image on the side of the photoreceptor 1. The toner image on the surface of the photosensitive member 1 is transferred to the feeding transfer material surface side by being charged to the opposite polarity to the charging polarity of the toner.

The transfer material that has passed through the transfer portion is separated from the surface of the photosensitive member 1 and is guided to the fixing device 13 through the guide 12 to undergo image fixing, and is discharged to the paper discharge tray 14.

After the transfer of the toner image, the surface of the photosensitive member 1 is cleaned by a cleaning device 7 to remove residual contaminants such as transfer residual toner, and is repeatedly used for image formation.

Next, the process cartridge mounting state detecting means 15 will be described.

Reference numeral 16 is a current detecting means for detecting a current flowing through the charging roller 2, 17 is a controller circuit, and 18 is a warning lamp.

When the main power switch of the printer main body is turned on, the rotation driving (pre-multi-rotation) of the photosensitive member 1 is started and the voltage Va is applied from the charging bias applying power source 3 to the charging roller 2. .

The current detecting means 16 detects the current Ia flowing through the charging roller 2 by applying the voltage Va. When the detected current Ia is the set current, it is determined that the process cartridge 30 is properly attached to the printer body 20. In this case, as described above, the image forming process execution operation is started based on the subsequent input of the print start signal.

When the current Ia is not detected at all and is zero, it means that the photoconductor 1 and the charging roller 2 are not in contact with each other. Therefore, in this case, it is determined that the process cartridge 30 is not attached to the printer body 20 (forgetting to be attached), or even if it is attached, the attachment state is incomplete.

If the current Ia is detected but is much lower than the normal set current, the mounting state of the process cartridge 30 is determined to be incomplete in this case as well.

In these cases, the warning light 18 is turned on by the controller circuit 17, the rotational drive of the photoconductor 1 is stopped, and the execution of the image forming operation of the printer is kept in a prohibited state.

The warning light 18 makes the user recognize that the process cartridge 30 is incompletely mounted or that the process cartridge 30 has been forgotten, and prompts the user to redo the mounting or mount the forgotten cartridge 30.

By prohibiting the image forming operation of the apparatus, the process cartridge 30 is incompletely mounted or the printer operates without forgetting to mount the process cartridge 30.
Strictly prevent the occurrence of image defects and failure to output images.

When the process cartridge 30 is reattached or the forgotten cartridge is attached, the printer main body 20
When the cartridge 30 is properly reattached to the inside,
Since the detection current Ia becomes the set current, it is determined that the cartridge 30 is properly mounted, and the image forming process execution operation is started based on the subsequent input of the print start signal.

In this embodiment, an OPC photosensitive drum having an outer diameter of 30 mmφ and a length of 240 mm is used as the photoconductor 1, and a conductive rubber roller having an outer diameter of 12 mmφ and a length of 230 mm is used as the charging roller 2.
When 0 is properly mounted, a nip having a width of about 1 to 2 mm is formed at the contact portion between the photosensitive drum 1 and the charging roller 2.

When a process speed of 30 mm / sec was applied to the charging roller 2 and a DC voltage of -700 V AC voltage and a peak-to-peak voltage of 1400 V 200 Hz sine wave superimposed vibration voltage were applied,
Photoreceptor 1 was uniformly charged to approximately -700V.

At this time, a DC current of about 6 μA and an AC current of about 200 μA flowed.

If the current value is abnormally small even considering the fluctuations in the setting allowable values such as the electric resistance value of the voltage applying means 3 and the charging roller 2, the photoconductor 1 on the process cartridge 30 side and the charging roller on the printer body side. It can be determined that there is an abnormality in the contact state with 2, that is, the mounting of the process cartridge is insufficient.

Therefore, the controller circuit 17 is, for example, D
When a signal having a C current of 2 μA or less is received, the warning lamp 18 indicating that the process cartridge is not properly mounted is turned on.
As a result, even when the process cartridge 30 is not in the printer body 20 and the process cartridge 30 is not sufficiently mounted and the photoconductor 1 and the charging roller 2 are not accurately in contact with each other, the process cartridge 30 can be displayed to the user. Can be notified that the installation is bad.

Moreover, in this state, the execution of image formation is prohibited, so that it is possible to prevent the occurrence of image defects and the like.

<Second Embodiment> In the first embodiment, the DC current is detected as the current flowing through the charging roller 2 to determine the mounting state of the process cartridge 30, but in this embodiment, the AC current is detected. Is.

In this case, for example, it could be determined that the abnormality was 50 μA or less. Further, when detecting with AC current, a current determined by the resistance of the charging roller 2 and the capacitance component of the photoconductor 1,
Since a current that repeats charging and discharging due to discharge flows (most of the current is the former), the photoconductor 1 is not driven to rotate by turning on the main power switch of the printer body.
The current value can be detected while the rotation is stopped.

Further, in this case, the charging roller 2 and the photosensitive member 1
If the current value is detected with an AC voltage having a peak-to-peak voltage that is less than twice the voltage at which the discharge starts, the current that is determined by the resistance of the charging roller 2 and the capacitance component of the photoconductor 1 flows, and the discharge current Does not flow, it is possible to prevent the charging memory from being formed in the photoconductor 1 even when the photoconductor 1 is stopped rotating. However, in this case, since the AC voltage is lowered, it is necessary to lower the value of the AC current to be determined accordingly.

In the device of Example 1, the discharge start voltage was about 550V. Therefore, the AC voltage for detecting the mounting of the process cartridge 30 is set to the peak-to-peak voltage of 800V. At this time, if the wearing is normal, about 11
A current of 0 μA flows. Therefore, when a current of, for example, 30 μA or less is detected, the mounting of the process cartridge can be made defective.

<Embodiment 3> (FIG. 2) In this embodiment, as shown in FIG. 2, a contact charging roller 19 (transfer roller) is used as the transfer charging means instead of the corona charger 6 of FIG. The mounting state of the process cartridge 30 is detected by the amount of current flowing through.

The transfer roller 19 is a conductive rubber roller provided on the printer body side, and when the process cartridge 30 is properly mounted in the printer body 20, the lower surface side window hole portion 3 of the mounted process cartridge 30.
The lower surface of the photoconductor 1 which is viewed from 3 is contacted with a predetermined pressing force.

Both ends of the transfer roller 19 are rotatably supported by bearings, and the transfer roller 19 is pressed against the surface of the photosensitive member 1 by a pressing means (not shown). As the photosensitive member 1 rotates, the transfer roller 19 is driven or rotated. To be done.

When the image forming process is performed on the rotating photoconductor 1 and the leading end of the transfer material fed from the paper feed unit reaches the pressure contact nip portion (transfer unit) between the photoconductor 1 and the transfer roller 19, the transfer roller By applying a predetermined transfer bias from the power supply 8 to 19, the back surface of the feeding transfer material is charged by the contact charging method in a polarity opposite to the charging polarity of the toner of the toner image on the side of the photosensitive member 1. The toner image on the surface of the photoconductor 1 is transferred to the surface of the transfer material.

In this embodiment, the mounting state of the process cartridge 30 is detected by detecting the current flowing through the transfer roller 19.

That is, as in the case of the first embodiment, when the main power switch of the printer main body is turned on, the rotation driving of the photoconductor 1 is started, and the voltage Va from the power source 8 to the transfer roller 19 is started. Is applied.

The current detecting means 16 detects the current Ia flowing through the transfer roller 2 by applying the voltage Va.

As in the case of the first embodiment, when the detection current Ia is the set current, it is determined that the process cartridge 30 is properly mounted, and the image forming process is executed based on the subsequent input of the print start signal. The operation is started.

If the current Ia is not detected at all or is much lower than the set current, it is judged that the process cartridge has been forgotten to be mounted or incompletely mounted, and the control circuit 17 turns on the warning lamp 18. At the same time, the rotation drive of the photoconductor 1 is stopped, and the execution of the image forming operation is kept in a prohibited state.

In Examples 1 to 3 above, the contact charging member 2 or 19 is detected by detecting the current value when a voltage is applied to the contact charging member (charging roller 2 or transfer roller 19).
When the contact state between the image carrier 1 and the image carrier 1, that is, the mounting state of the process cartridge 30 is detected, a constant current circuit for flowing a preset current to the contact charging member 2 or 19 is driven, and the output at that time is output. Contact charging member 2 depending on the voltage value
Alternatively, it is possible to detect the contact state between 19 and the image carrier 1.

In short, it is sufficient to have a means for detecting a change in the contact state between the contact charging member 2 or 19 and the image carrier 1 as a change in electrical load.

Further, the process cartridge 3 shown in FIGS.
Although not shown in FIG.
Each opening 32, 33, 34 is provided with an opening / closing shutter plate, and when the cartridge 30 is taken out of the printer main body, each opening 32, 33, 34 is kept closed by the shutter plate. When the cartridge 30 is mounted in the printer body, the shutter plates are opened in association with the mounting, and the openings 32, 33, 34 are opened.

[0084]

As described above, according to the present invention, a process cartridge detachable image forming apparatus in which the contact charging means is used as the charging process means and the charging member of the charging means is disposed on the main body side of the image forming apparatus. Regarding, regarding whether the process cartridge is properly attached to the main body of the device, it is surely detected whether the process cartridge is improperly mounted or the cartridge is forgotten to be attached. It is possible to strictly prevent the occurrence of defects and inability to output images.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram of an image forming apparatus according to another embodiment.

FIG. 3 is a schematic configuration diagram of an example of a contact charging device.

[Explanation of symbols]

20 Printer Main Body 30 Process Cartridge 1 Rotating Drum Type Electrophotographic Photoreceptor as Image Carrier 2,19 Charging Roller or Transfer Roller as Contact Charging Member 3,8 Charging or Transfer Bias Applied Power Supply 4 Laser Scanner 5 Developer 6 Transfer Corona charger 7 Cleaning device 9 Paper feed tray 10 Paper feed rollers 11, 12 Transfer material guide 13 Fixing device 14 Paper ejection tray 15 Process cartridge mounting state detection means 16 Current detection means 17 Controller circuit 18 Warning light

Claims (6)

[Claims] 1. A process cartridge detachable image forming apparatus, wherein the process cartridge has at least an image carrier, and the image forming apparatus body is in contact with or in proximity to the image carrier of the process cartridge mounted on the apparatus body. And has a charging member to which a voltage is applied by the voltage applying means, and a means for detecting the electrical load when the voltage is applied to the charging member to detect the mounting state of the process cartridge with respect to the apparatus main body. A characteristic image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the detection of the electric load is detection of a current flowing through the charging member when a voltage is applied to the charging member. 3. The detection of the electrical load is a detection of an output current at the time of driving a constant current circuit for supplying a preset current to a charging member, and detecting the output current. Image forming apparatus. 4. The image forming process execution operation of the apparatus is prohibited when the detection means detects / determines that the mounting state of the process cartridge with respect to the apparatus main body is uncertain or not mounted. The image forming apparatus according to claim 1. 5. The image forming apparatus according to claim 1, wherein the charging member is a charging process unit for the surface of the image carrier. 6. The image forming apparatus according to claim 1, wherein the charging member is a transfer charging unit that transfers the transferable image on the surface of the image carrier to the surface of the transfer material.