JP2015001719A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of accurately detecting the presence/absence of a cartridge in a short time as much as possible regardless of fluctuation in an environment.SOLUTION: Control means for determining the presence/absence of a process cartridge attachable/detachable to/from an image forming apparatus main body is configured to repeat a detection timing for detecting the presence/absence of the process cartridge since power supply means starts the supply of power to charging means, and to determine that the process cartridge is mounted when it is detected that the cartridge is present in the detection timing, and to determine that the process cartridge is not mounted when it is not detected that the cartridge is present within a predetermined time or the predetermined number of times or less.

Description

  The present invention relates to an electrophotographic image forming apparatus such as a printer or a copying machine in which a process cartridge is detachably mounted.

  In an image forming apparatus such as a laser beam printer, an electrophotographic photosensitive member, a charging roller, a developing device, and the like are integrally accommodated in a cartridge container as a process cartridge, and are detachably disposed in a main body of the image forming apparatus. There is something that is.

  In the process cartridge, when the member in the cartridge container reaches the end of its life, the entire process cartridge is replaced, thereby facilitating the replacement work of the member in the cartridge container. For this reason, it is necessary to detect and confirm whether or not the process cartridge is mounted in the main body of the image forming apparatus.

  Therefore, conventionally, a technique as disclosed in Patent Document 1 is disclosed as a technique for detecting the presence or absence of a process cartridge in the apparatus main body. In Patent Document 1, an output current or an output voltage of a power supply unit that supplies power to a charging roller included in a process cartridge or a transfer roller provided in the apparatus body is detected, and the presence or absence of the process cartridge is determined from the magnitude of the detection result. ing.

JP-A-4-181266

  However, impedance components such as the charging roller and the transfer roller greatly vary depending on the installation environment. In particular, in a low temperature environment, the detection current for determining the presence or absence of the cartridge is significantly reduced due to the increase in resistance of the charging roller. If the threshold value for determining the presence / absence of a cartridge is set low with reference to the detection current that has significantly decreased in a low temperature environment, the S / N ratio between the detection current and the noise component cannot be increased, so there is no cartridge. Regardless of this, the possibility of false detection increases. Conversely, if the above-described threshold value is set higher to avoid this erroneous detection, when the change to the low temperature environment further progresses, the possibility of erroneous detection that there is no cartridge increases.

  Also, if the roller temperature rises along with the internal ambient temperature due to the influence of the heat source in the device body, such as after turning on the power to the device body, it is possible to increase the detection current until the roller resistance decreases and the presence or absence of the cartridge can be determined. is there. However, the degree of temperature rise varies greatly depending on the installation environment of the device before turning on the power, and if the timing at which current detection is possible in consideration of the temperature rise in the low temperature environment is uniformly set slower than the low temperature environment There is a problem that the start-up time in the temperature environment is delayed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of accurately detecting the presence / absence of a cartridge in the shortest possible time regardless of environmental changes.

  Other objects of the present invention will become apparent upon reading the following detailed description with reference to the accompanying drawings.

  In order to achieve the above object, the present invention includes an electrophotographic photosensitive member and a charging unit that contacts the electrophotographic photosensitive member and charges the electrophotographic photosensitive member, and is detachable from an image forming apparatus main body. A process cartridge provided in the main body of the image forming apparatus, transferring means for transferring the image formed on the electrophotographic photosensitive member in contact with the electrophotographic photosensitive member, and supplying power to the charging means or the transferring means. An image forming apparatus comprising: a power supply unit that supplies power; and a control unit that determines the presence or absence of the process cartridge based on information from the power supplied to the charging unit or the transfer unit supplied from the power supply unit. The control means repeats detection timing for detecting the presence or absence of the process cartridge after the power supply means starts supplying power, and the detection timing is repeated. It is determined that the process cartridge is mounted when it is detected that the cartridge is present, and if it is not detected that the cartridge is present within a predetermined time or within a predetermined number of times, it is determined that the process cartridge is not mounted. To do.

  According to the present invention, cartridge presence / absence detection can be performed in the shortest possible time regardless of environmental changes.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus. FIG. 3 is a block diagram illustrating a circuit configuration of a control unit according to the first embodiment. 3 is a flowchart illustrating control for detecting whether a cartridge is present in the first embodiment. 3 is a flowchart illustrating control for detecting whether a cartridge is present in the first embodiment. 5 is a timing chart of the control shown in FIG. FIG. 10 is a block diagram illustrating a circuit configuration of a control unit according to a second embodiment. 10 is a flowchart illustrating control of cartridge presence / absence detection according to the second exemplary embodiment. It is a timing chart of the control shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, what attached | subjected the same code | symbol in each drawing has the same structure or effect | action, The duplication description about these was abbreviate | omitted suitably. Here, the device configuration, components, dimensions, materials, shapes, and other relative arrangements described in the following embodiments are within the scope of the present invention unless otherwise specified. It is not intended to limit only to them.

[Example 1]
FIG. 1 schematically shows a schematic configuration of the image forming apparatus. In this embodiment, a laser beam printer will be described as an example of the image forming apparatus.

  As shown in FIG. 1, the image forming apparatus includes a photosensitive drum 100, a charging voltage generating circuit 500, a charging roller 700, a laser generating apparatus 300, a developing apparatus 400 including a developing sleeve 410, a transfer apparatus 800, a cleaning apparatus 900, and an engine controller. 600 etc.

  The photosensitive drum 100 is an electrophotographic photosensitive member for realizing an electrophotographic process. The charging voltage generation circuit 500 is power supply means for supplying power (current or voltage) to process means included in the process cartridge. Here, as the power supply means, a charging voltage generation circuit for supplying power to the charging roller 700 which is one of the process means is illustrated. The charging voltage generation circuit 500 generates a voltage obtained by superimposing a DC voltage on a normal sine wave, and places a uniform charge necessary for the electrophotographic process on the photosensitive drum 100.

  The charging roller 700 is a charging unit that is supplied with electric power from the charging voltage generation circuit 500 and contacts the photosensitive drum 100 to uniformly charge the drum surface. The laser generator 300 is an exposure unit that irradiates a laser beam on the photosensitive drum 100 according to image data to form an electrostatic latent image. The developing device 400 including the developing sleeve 410 is disposed to face the photosensitive drum 100, carries toner (developer), and develops the electrostatic latent image on the photosensitive drum 100. The transfer device 800 is a transfer unit that transfers the toner image on the photosensitive drum 100 to the recording medium P. The cleaning device 900 is a cleaning unit that removes toner remaining on the photosensitive drum 100 after transfer from the surface thereof.

  The engine controller 600 is a control unit that determines the presence or absence of a process cartridge based on information from an output current or output voltage from the charging voltage generation circuit 500 to the charging roller 700. The engine controller 600 includes a CPU, RAM, ROM, etc. (not shown). In the engine controller 600, the CPU executes each process by reading and executing a program from the ROM. The RAM holds data and the like necessary when the CPU executes the program. The ROM holds a program executed by the CPU for controlling the image forming apparatus.

  The image forming apparatus includes a process cartridge (hereinafter simply referred to as “cartridge”) that is detachable from the image forming apparatus main body. In this example, the cartridge integrally includes a photosensitive drum 100, a charging roller 700 as a process unit that acts on the photosensitive drum 100, and a cleaning device 900, and is detachable from the apparatus main body. is there. The cartridge that can be attached to and detached from the image forming apparatus main body is not limited to the above-described configuration. For example, the cartridge further includes a developing device (developing unit) 400 as a process unit that acts on the photosensitive drum. It may be.

  In the image forming apparatus having the above configuration, the photosensitive drum 100 uniformly charged via the charging roller 700 is irradiated with laser light from the laser generator 300 according to the image data to form an electrostatic latent image. The electrostatic latent image is developed by the developing device 400 to form a toner image, and transferred to the recording medium P by the transfer device 800. The recording medium P is conveyed to a fixing device 1000 including a heating unit 1010, where the toner image is fixed and discharged outside the device.

  FIG. 2 shows a charging voltage generation circuit 500 and an engine controller 600 of the image forming apparatus. In FIG. 2, an output signal PRACC from the engine controller 600 is a signal for applying an AC voltage from the charging voltage generation circuit 500 to the charging roller 700. The output signal PRACC from the engine controller 600 is usually a square wave of about 200 Hz to 1 kHz, and is determined by the engine process speed and the like. In this example, it is a square wave having a frequency of 470 Hz, a duty of 50%, and Vpp of 5 V, and the level is converted to Vpp 24 V by the transistor 502 and the resistor 503.

  The operational amplifier 501 converts the square wave signal PRACC input from the engine controller 600 into a sine voltage of Vpp20V. The voltage input to the transformer 511 is changed to a voltage corresponding to the winding of the transformer 511.

  A diode 509 and a capacitor 508 are a circuit for rectifying the sine voltage. The DC voltage 510 is a DC power source for shifting the central value of the charging AC voltage.

  A capacitor 519 connected to the secondary side of the transformer 511 is a capacitor for transmitting electric power to the photosensitive drum 100, and is converted into a current voltage by a resistor 520. Thereafter, only a positive voltage is extracted by the diode 521, and is peak-charged by the operational amplifier 522, the capacitor 524, and the resistor 523, and is input to the CRGSNS of the A / D input port of the engine controller 600. CRGSNS is a value obtained by applying a voltage from the charging voltage generation circuit 500 to the charging roller 700 and extracting the amount of current flowing from the charging roller 700 to the photosensitive drum 100 as a signal. The engine controller 600 repeats changing the current input as a signal to a voltage in this way, and in order to compare it with a specified value (specified voltage) for determining the presence or absence of a cartridge, an average value obtained by averaging the voltages (Detection voltage) is calculated.

  When the cartridge 200 is mounted on the apparatus main body, that is, when the cartridge 200 is present, the generated voltage is large because a large amount of current flows through the resistor 520 when power (AC voltage) is supplied from the charging voltage generation circuit 500. On the other hand, when the cartridge 200 is not attached to the apparatus main body, that is, when the cartridge 200 is not present, when electric power (AC voltage) is supplied from the charging voltage generation circuit 500, the current flowing through the resistor 520 is small. small. The engine controller 600 compares the generated voltage with a predetermined value (specified voltage) stored in advance to determine whether or not a cartridge is mounted. Here, the specified voltage (specified value) for determining whether or not the cartridge is mounted is set between a voltage generated when the cartridge is present and a voltage generated when the cartridge is not present.

  Next, the operation of detecting whether or not the cartridge is mounted will be described with reference to the flowchart of FIG.

  When a switch (not shown) of the main power supply of the printer main body is turned on, the photosensitive drum 100 starts to rotate (pre-multiple rotations) (S101), and the charging voltage generating circuit 500 applies a voltage to the charging roller 700. Is applied (S102).

  The engine controller 600 detects the presence / absence of a cartridge from the voltage at the CRGSNS input to the A / D input port by the current flowing through the charging roller 700 by the applied voltage (S103). That is, the engine controller 600 compares the input voltage in CRGSNS with a specified voltage (specified value) stored in advance in the engine controller 600 (S104), and determines the presence or absence of a cartridge.

  As a result of the comparison in step S104, the engine controller 600 determines that the process cartridge 200 is correctly attached to the printer body when the voltage at CRGSNS is equal to or higher than the specified voltage (S105). In this case, the engine controller 600 starts executing the image forming operation based on the subsequent input of the print start signal (S106).

  On the other hand, as a result of the comparison in step S104, the engine controller 600 determines that the process cartridge 200 is not attached to the printer body or the attachment state is incomplete when the voltage at CRGSNS is less than the specified voltage. (S107). In this case, the engine controller 600 stops the rotation of the photosensitive drum 100 (S108), turns on a warning lamp (not shown) (S109), and maintains the printer in a state in which execution of the image forming operation is prohibited.

  The warning light described above allows the user to recognize that the process cartridge 200 is incompletely attached or not attached, and prompts the user to reattach or forget to attach the process cartridge 200.

  When the user is prompted to turn on the warning light and re-installs the process cartridge 200 correctly in the printer body (S110), the voltage at CRGSNS becomes equal to or higher than the specified voltage in step S104. As a result, the engine controller 600 determines that the process cartridge 200 is correctly mounted, and starts executing the image forming operation based on the input of the subsequent print start signal (S106).

  In the present embodiment, after outputting PRACC, the engine controller 600 repeats voltage sampling in the CRGSNS for a certain period of time, and calculates an average value of the voltages sampled for the certain period of time. Then, the calculated average value (detection voltage) is compared with a predetermined value (specified voltage) stored in advance in the engine controller 600 to detect the presence or absence of the cartridge 200. The engine controller 600 has a plurality of detection timings for detecting the presence or absence of the process cartridge. Then, the engine controller 600 determines that the cartridge is correctly mounted when it detects that the cartridge is present at the detection timing, and stops the output of the PRACC. On the other hand, if the engine controller 600 does not detect the presence of a cartridge within a predetermined time (or within a predetermined number of times) at the detection timing, the engine controller 600 determines that the cartridge is not installed or is incompletely installed, and the PRACC Stop the output of. Hereinafter, this will be described in detail with reference to FIGS.

  FIG. 4 is a flowchart of cartridge presence / absence detection, and FIG. 5 is a time chart of cartridge presence / absence detection.

  The engine controller 600 activates the cartridge presence / absence detecting operation shown in FIG. 4 when the image forming apparatus is powered on or when the door is closed.

  First, the engine controller 600 outputs a signal PRACC to the charging voltage generation circuit 500 to drive the charging voltage generation circuit 500 (S201), and supplies electric power for cartridge presence / absence operation (here, voltage) to the charging roller 700. At the same time, while the charging voltage is being output to the charging roller 700, the sampling of the voltage at the CRGSNS of the A / D port in the engine controller 600 is repeated until the sampling time (fixed time) elapses (S202, S203). In this example, the sampling time is 400 msec. Data sampled during the sampling time is averaged, and the average value is used as a detection voltage (S204).

  The voltage sampling in the CRGSNS is continuously performed while the charging voltage is being output to the charging roller 700. In this embodiment, the detection voltage is compared with the specified voltage (0.7 V in this example) at regular intervals within the activation time of the cartridge presence / absence detection operation (S205). This comparison is the detection timing for detecting the presence or absence of the cartridge. As a result of this comparison, if the detected voltage (average value) exceeds the specified voltage (0.7 V), it is determined that there is a cartridge at that time, and a print waiting state is set (S206). Conversely, if the detected voltage (average value) does not exceed the specified voltage (0.7 V) as a result of the comparison, it is determined whether it is within the cartridge presence / absence detection operation time (within a predetermined time) (S207). If it is within the operation time, the process returns to step S202, and the above-described cartridge presence / absence detection operation is repeated at regular intervals. On the other hand, if it is not within the operation time, it is determined that the cartridge is not installed or is not installed completely, and the display means (not shown) is used to notify the user that there is no cartridge (S208). Then, after sampling is completed, the output of PRACC is stopped (S209).

  By the detection operation, accurate cartridge presence / absence detection can be performed in a short time regardless of the environmental temperature. FIG. 5 illustrates determination of the presence / absence of a cartridge by the detection operation when the environmental temperature changes. In FIG. 5, the case where environmental temperature is 30 degreeC, 15 degreeC, and 0 degreeC is illustrated. Further, FIG. 5 illustrates a case where the detection timing can be performed five times within the detection operation time, but the present invention is not limited to this.

  As shown in FIG. 5, when the environmental temperature is relatively high, 30 ° C., the average value (detection voltage) of the sampling voltage in the CRGSNS exceeds the specified voltage at the first detection timing. It can be determined that there is. Next, when the environmental temperature is 15 ° C., since the average value (detection voltage) of the sampling voltage in the CRGSNS exceeds the specified voltage at the second detection timing, it can be determined that there is a cartridge at that time. When the ambient temperature is 0 ° C., which is a relatively low temperature, the average value (detection voltage) of the sampling voltage in the CRGSNS exceeds the specified voltage at the fifth detection timing. be able to. If the average sampling voltage (detection voltage) does not exceed the specified voltage at each detection timing within the predetermined number of times, it can be determined that there is no cartridge. As described above, the presence / absence of a cartridge can be determined at a detection timing that can be repeatedly performed within a predetermined time regardless of a change in environmental temperature, and the presence / absence of a cartridge can be accurately detected in as short a time as possible.

  As described above, according to the present embodiment, it is possible to determine that the cartridge is correctly mounted at the time when the presence of the cartridge is detected at each detection timing that can be repeatedly performed every predetermined time within the activation time of the cartridge presence / absence detection operation. . Thus, the detection operation can be completed earlier when the installation environment is high, and the presence or absence of the cartridge can be determined according to the fluctuation of the roller resistance due to the influence of the heat source in the main body when the installation environment is low. Therefore, it is possible to minimize the control time while setting the threshold of the specified voltage for determining the presence / absence of the cartridge and the S / N ratio of the noise component to be high and preventing erroneous detection. Therefore, it is possible to detect the presence / absence of the cartridge as accurately as possible in a short time regardless of environmental changes.

[Example 2]
Next, Example 2 will be described with reference to FIGS. 6, 7, and 8. FIG. 6 is a block diagram illustrating a circuit configuration of a control unit according to the second embodiment. FIG. 7 is a flowchart showing the control for detecting the presence / absence of a cartridge in the second embodiment. FIG. 8 is a timing chart of the control shown in FIG. In addition, what attached | subjected the same code | symbol in each drawing makes the same structure or effect | action, and duplication description about these is abbreviate | omitted.

  The image forming apparatus according to this embodiment includes a temperature detection unit 1101 that detects the temperature of at least one of the inside and the outside of the image forming apparatus main body (see FIG. 6). In this embodiment, the standby time from the start of power supply from the charging voltage generation circuit 500 (after PRACC output) to the start of voltage sampling in the CRGSNS depends on the temperature detected by the temperature detection unit 1101. It has changed. That is, when the environmental temperature detected by the temperature detection unit 1101 is the first temperature, the engine controller 600 sets the waiting time until the start of sampling as the first waiting time, and the second temperature lower than the first temperature. In this case, the waiting time until the start of sampling is set as a second waiting time longer than the first waiting time. Accordingly, the detection timing for determining the presence / absence of the cartridge within the activation time of the cartridge presence / absence detection operation according to the detection temperature of the temperature detection means 1101 is earlier when the detection temperature of the temperature detection means is higher and as the detection temperature is lower. The detection of the presence / absence of the cartridge can be performed in as short a time as possible and still accurately.

  FIG. 6 shows a charging voltage generation circuit 500 and an engine controller 600 of the image forming apparatus in this embodiment.

  The engine controller 600 includes three terminals: a pulse output terminal PRACC, an A / D input port CRGSNS, and a temperature information TEMP terminal.

  FIG. 6 illustrates an in-machine temperature detection means 1101 for detecting the temperature inside the apparatus. The in-machine temperature detection means 1101 is connected to a thermistor 1102 and a resistor 1103, the side of the resistor 1103 not connected to the thermistor 1102 is connected to Vcc, and the side of the thermistor 1102 not connected to the resistor 1103 is connected to GND. Vcc is divided by the resistor 1103 and the thermistor 1102 and connected to the TEMP terminal of the engine controller 600.

  Since the resistance value of the thermistor 1102 varies depending on the temperature, the engine controller 600 can detect the environmental temperature by referring to the voltage input to the TEMP terminal. The voltage temperature conversion table is stored in the engine controller 600 in advance.

  Next, control when the engine controller 600 in the present embodiment detects the presence or absence of the cartridge 200 will be described with reference to FIGS.

  FIG. 7 is a flowchart of cartridge presence / absence detection, and FIG. 8 is a time chart of cartridge presence / absence detection.

  The engine controller 600 activates the cartridge presence / absence detection operation shown in FIG. 7 when the image forming apparatus is powered on or when the door is closed.

  First, the engine controller 600 outputs the signal PRACC to the charging voltage generation circuit 500 to drive the charging voltage generation circuit 500 (S301), and at the same time reads the temperature information input from the temperature detection means 1101 to the TEMP terminal (S302). .

  Next, a temperature range in which the temperature input to the TEMP terminal is predetermined (in this embodiment, temperature ≦ 5 ° C., 5 ° C. <temperature ≦ 10 ° C., 10 ° C. <temperature ≦ 15 ° C., temperature> 15 ° C.) Of which is included (S303 to SS305). Then, the standby time until sampling is started with respect to the voltage in CRGSNS is set as a standby time that is predetermined for each of the temperature ranges (25 seconds, 20 seconds, 5 seconds, 0.5 seconds in this embodiment). ) (S306 to S309).

  When it is determined that a predetermined standby time for each temperature range has elapsed (S310 to S313), voltage sampling at the CRGSNS of the A / D port in the engine controller 600 is started (S314). Then, the sampling of the voltage is repeated until the sampling time (fixed time) elapses (S315). In this example, the sampling time is 400 msec. Data sampled during this sampling time is averaged, and the average value is used as a detection voltage (S316).

  The voltage sampling in the CRGSNS is continuously performed while the charging voltage is being output to the charging roller 700. In this embodiment, the detection voltage is compared with the specified voltage (0.7 V in this example) at regular intervals within the activation time of the cartridge presence / absence detection operation (S317). If the detected voltage exceeds the specified voltage as a result of this comparison, it is determined that there is a cartridge, and a print standby state is set (S318). Conversely, if the detected voltage does not exceed the specified voltage (0.7 V) as a result of the comparison, it is determined that the cartridge is not installed or is not installed completely, and the display means (not shown) is used. The user is notified that there is no cartridge (S319). Then, after sampling is completed, the output of PRACC is stopped (S320).

  By the detection operation, it is possible to accurately detect the presence / absence of the cartridge in a short time according to the environmental temperature. FIG. 8 illustrates determination of the presence / absence of a cartridge by the detection operation when the environmental temperature changes. In FIG. 8, the case where environmental temperature is 30 degreeC, 15 degreeC, and 0 degreeC is illustrated. Further, FIG. 8 shows the detection timing of each temperature range according to the change of the environmental temperature.

  As shown in FIG. 8, when the environmental temperature is relatively high, 30 ° C., the temperature range becomes temperature> 15 ° C. Therefore, the waiting time until the start of sampling is the shortest time (0.5 sec), and the timing for determining the presence / absence of the cartridge is also the earliest timing (temperature> 15 ° C. in FIG. 8). Next, when the environmental temperature is 15 ° C. lower than 30 ° C., the temperature range is lower than the temperature range (temperature> 15 ° C. in FIG. 8) (10 ° C. <temperature ≦ 15 ° C. in FIG. 8). Therefore, the waiting time until the start of sampling is longer (5 sec) than the time (0.5 sec), and the timing for determining the presence or absence of the cartridge is later than the timing (temperature> 15 ° C. in FIG. 8) (FIG. 8). 10 ° C. <temperature ≦ 15 ° C.). When the environmental temperature is relatively low, 0 ° C., the temperature range is lower than the temperature range (10 ° C. <temperature ≦ 15 ° C. in FIG. 8) (temperature ≦ 5 ° C. in FIG. 8). Therefore, the waiting time until the start of sampling becomes longer (25 sec) than the time (5 sec), and the timing for determining the presence or absence of the cartridge is later than the timing (10 ° C. <temperature ≦ 15 ° C. in FIG. 8) ( In FIG. 8, temperature ≦ 5 ° C.). As described above, the detection timing for determining the presence / absence of the cartridge can be made early when the detection temperature is high according to the change in the environmental temperature, and can be delayed as the detection temperature is low. It can be detected accurately.

  As described above, in this embodiment, the timing for determining the presence or absence of the cartridge 200 is changed according to the detected temperature of the temperature detecting unit, so that the detection operation is terminated earlier when the installation environment is hot, and Can delay the timing of cartridge presence / absence determination according to a preset roller resistance fluctuation predicted value due to the heat source in the main body. Therefore, it is possible to minimize the control time while setting the threshold of the specified voltage for determining the presence / absence of the cartridge and the S / N ratio of the noise component to be high and preventing erroneous detection.

[Other Examples]
In the above-described embodiment, the configuration in which the engine controller 600 repeats the detection timing for detecting the presence / absence of a cartridge for a predetermined time is exemplified, but the present invention is not limited to this, and the detection timing may be repeated for a predetermined number of times. Even if it does in this way, the effect similar to the Example mentioned above is acquired.

  In the above-described embodiment, the case where the power supply unit supplies power to the charging unit has been described as an example. However, the present invention is not limited to this. The present invention is also effective in an image forming apparatus in which the power supply unit supplies power to the transfer unit. Even in this configuration, the same effect can be obtained by applying the present invention.

  In the above-described embodiments, the temperature detecting means for detecting the temperature inside the apparatus is exemplified as the temperature detecting means. However, the present invention is not limited to this. The temperature detecting means may be one that detects the temperature outside the image forming apparatus main body, or one that detects the temperature inside and outside the image forming apparatus main body.

  In the above-described embodiments, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as a copying machine or a facsimile machine, or another image forming apparatus such as a multi-function machine combining these functions. The same effect can be obtained by applying the present invention to these image forming apparatuses.

DESCRIPTION OF SYMBOLS 100 ... Photosensitive drum 200 ... Process cartridge 500 ... Charging voltage generation circuit 600 ... Engine controller 700 ... Charging roller 800 ... Transfer device 1101 ... Temperature detection means

Claims (5)

A process cartridge that includes an electrophotographic photosensitive member and a charging unit that contacts the electrophotographic photosensitive member and charges the electrophotographic photosensitive member, and is detachable from the image forming apparatus body;
A transfer unit provided in the image forming apparatus main body, for transferring the image formed on the electrophotographic photosensitive member in contact with the electrophotographic photosensitive member;
Power supply means for supplying power to the charging means or the transfer means;
Control means for determining the presence or absence of the process cartridge based on information from the power supplied to the charging means or the transfer means supplied from the power supply means;
In an image forming apparatus having
The control means repeats the detection timing for detecting the presence or absence of the process cartridge after the power supply means starts supplying power, and the process cartridge is mounted when the presence of the cartridge is detected at the detection timing. An image forming apparatus comprising: determining that a process cartridge is not installed when no cartridge is detected within a predetermined time or a predetermined number of times.   The control means repeats taking out the current flowing from the charging means or the transfer means to the electrophotographic photosensitive member as a signal and changing it to a voltage after the power supply means starts supplying power, The image forming apparatus according to claim 1, wherein an average value obtained by averaging the voltages is compared with a predetermined value stored in advance, and it is detected that a cartridge is present when the average value is larger than the predetermined value. A process cartridge that includes an electrophotographic photosensitive member and a charging unit that contacts the electrophotographic photosensitive member and charges the electrophotographic photosensitive member, and is detachable from the image forming apparatus body;
A transfer unit provided in the image forming apparatus main body, for transferring the image formed on the electrophotographic photosensitive member in contact with the electrophotographic photosensitive member;
Power supply means for supplying power to the charging means or the transfer means;
Control means for determining the presence or absence of the process cartridge based on information from the power supplied to the charging means or the transfer means supplied from the power supply means;
Temperature detecting means for detecting the temperature of at least one of the inside and the outside of the image forming apparatus main body;
In an image forming apparatus having
The control unit changes a standby time from when the power supply unit starts supplying power until detection of the presence or absence of the process cartridge to a standby time according to the temperature detected by the temperature detection unit. If it is detected that the cartridge is present at the detection timing for detecting the presence or absence of the process cartridge after the standby time has elapsed, it is determined that the process cartridge is mounted. If the presence of the cartridge is not detected, the process cartridge is determined. An image forming apparatus that determines that the camera is not mounted.   The control means sets the standby time as the first standby time when the temperature detected by the temperature detection means is the first temperature, and sets the standby time as the second temperature lower than the first temperature. The image forming apparatus according to claim 3, wherein the second standby time is longer than the first standby time.   The control means changes the current that has flowed from the charging means or the transfer means to the electrophotographic photosensitive member into a voltage after the standby time has elapsed since the power supply means has started supplying power. 5. The image forming apparatus according to claim 4, wherein an average value obtained by averaging the voltages is compared with a predetermined voltage stored in advance, and when the average value is larger than the predetermined voltage, it is detected that a cartridge is present. .

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