JP5159666B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus in which a process cartridge including at least a latent image carrier and developing means can be mounted, and in particular, a protective member is attached to the process cartridge during transportation, and the developing means is separated from the latent image carrier. The present invention relates to an image forming apparatus that maintains a state. Here, the image forming apparatus includes, for example, an electrophotographic copying machine, a facsimile machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), and a complex machine (multifunction printer) thereof.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image forming process, a process cartridge in which a latent image carrier and developing means provided so as to be able to contact with and separate from the latent image carrier are integrally formed in the main body of the image forming apparatus. A system that can be inserted and removed is adopted. Further, for the purpose of increasing the distribution efficiency of the image forming apparatus main body and the process cartridge, the image forming apparatus is packed and transported with the process cartridge mounted.

  For example, when transported in a state where the intermediate transfer member is in contact with the latent image carrier, scratches or the like that lead to image degradation may occur on the latent image carrier or the intermediate transfer member due to vibrations or the like generated during transport. In order to prevent this, a configuration is known in which a protective member can be attached to the contact portion between the latent image carrier and the intermediate transfer member, and a warning tag is installed to notify the user that the protective member has been forgotten to be removed. (For example, refer to Patent Document 1).

  Also, a configuration has been proposed in which a protective member attached to a process cartridge is detected in a state in which the process cartridge is mounted on the image forming apparatus main body in order to prevent inconveniences that occur during transportation (see, for example, Patent Document 2). ).

  However, in the above-described prior art, in the invention described in Patent Document 1, even if the warning tag is prominently provided, the user may not fully understand the method of removing the protective member. There was a possibility that the protective member would not be removed. Further, for example, in the invention described in Patent Document 2, since the detection of the protection member is performed using a sensor, the number of sensors increases in the configuration using a plurality of process cartridges such as a color image forming apparatus, which is costly. There was a disadvantage that was disadvantageous.

JP-A-11-218983 JP-A-8-314351

  The present invention has been made in view of the above inconveniences, and assumes an image forming apparatus in which a protective member is attached to a process cartridge during transportation, and the developing unit maintains a state of being separated from the latent image carrier. And in such an image forming apparatus, it aims at providing the technique which can suppress more reliably by simpler structure that an image forming apparatus is used without a protective member being removed after completion | finish of conveyance.

In order to achieve the above object, the present invention provides a latent image carrier and a latent image formed on the latent image carrier by contacting the latent image carrier and contacting the latent image carrier. A developing process unit integrally configured to be developed, and a protective member is attached when the process cartridge is transported with the process cartridge mounted, so that the developing unit is removed from the latent image carrier. An image forming apparatus configured to maintain a separated state and to remove the protective member during use,
Cartridge detecting means for detecting that the process cartridge is mounted in the image forming apparatus;
A driving unit that applies a driving force to the process cartridge during image formation or when the developing unit and the latent image carrier are in contact with or separated from each other;
Load measuring means for measuring a load when the driving means applies a driving force to the process cartridge, and
And a protection member detection unit configured to detect whether or not the protection member is attached to the image forming apparatus based on a detection result by the cartridge detection unit and a value of the load measured by the load measurement unit. It is characterized by.

  According to the present invention, whether or not the protective member has been removed based on the magnitude of the driving force applied to the process cartridge by the driving unit during image formation or during the contact / separation operation between the developing unit and the latent image carrier. Can be detected. As a result, since it is possible to detect forgetting to remove the protective member using a function necessary for the operation of the normal image forming apparatus, the image forming apparatus can be used more reliably with a simpler configuration without removing the protective member. Can be suppressed.

1 is a cross-sectional view of an image forming apparatus according to the present invention. FIG. 6 is a diagram illustrating a contact state and a separation state of the developing roller and the photosensitive drum according to the present invention. FIG. 3 is a schematic view of a developing roller contact / separation mechanism according to the present invention. FIG. 3 is a perspective view of a developing roller contact / separation mechanism according to the present invention. FIG. 3 is a diagram illustrating a mounting state of the process cartridge according to the present invention in the image forming apparatus. The figure for demonstrating the contact-separation mechanism of the charging drum which concerns on this invention. The figure which shows the mounting state of the protection member which concerns on this invention. The figure which shows the structural example for preventing the removal of the conventional protection member. The figure which shows the structure for forgetting removal of the protection member which concerns on this invention. FIG. 6 is a diagram showing torque fluctuation due to contact between the developing roller and the photosensitive drum according to the present invention. The figure which shows the torque fluctuation of the cam drive source in the drive of the contacting / separating mechanism which concerns on this invention.

  Embodiments of an image forming apparatus according to the present invention will be described below in detail with reference to the drawings.

〔overall structure〕
The color image forming apparatus according to the present embodiment shown in FIG. 1 can be mounted with process cartridges 7 a, 7 b, 7 c, and 7 d that can be inserted into and removed from the image forming apparatus main body 100. These four process cartridges 7a, 7b, 7c, and 7d have the same structure, but form images with toners of different colors, that is, yellow (Y), magenta (M), cyan (C), and black (BK). Is different. The process cartridges 7a, 7b, 7c, and 7d include drum units 4a, 4b, 4c, and 4d having photosensitive drums 1a, 1b, 1c, and 1d that are latent image carriers, and developing units 5a, 5b, and 5c that are developing units. 5d. Of these, the drum units 4a, 4b, 4c, and 4d are not shown, in addition to the photosensitive drums 1a, 1b, 1c, and 1d, charging rollers 2a, 2b, 2c, and 2d, and drum cleaning blades 8a, 8b, 8c, and 8d, respectively. A waste toner container.

  The developing units 5a, 5b, 5c, and 5d include developing rollers 50a, 50b, 50c, and 50d, and developer application rollers 51a, 51b, 51c, and 51d. Two scanner units 3a and 3b are arranged below the process cartridges 7a, 7b, 7c and 7d. The scanner unit 3a performs exposure based on the image signal for the photosensitive drums 1a and 1b, and the scanner unit 3b performs exposure based on the image signal. The photosensitive drums 1a, 1b, 1c, and 1d are charged to predetermined negative potentials by the charging rollers 2a, 2b, 2c, and 2d, and then electrostatic latent images are formed by exposure by the scanner units 3a and 3b, respectively. .

  The electrostatic latent image is reversely developed by the developing units 5a, 5b, 5c, and 5d to adhere negative toner, and Y, M, C, and BK toners are respectively applied to the photosensitive drums 1a, 1b, 1c, and 1d. An image is formed. Next, in the intermediate transfer belt unit 12, the intermediate transfer belt 12e is stretched around the drive roller 12f, the secondary transfer counter roller 12g, and the tension roller 12h, and the tension roller 12h is urged in the direction of arrow B to be intermediate. Tension is applied to the transfer belt 12e. The intermediate transfer belt unit 12 is provided with primary transfer rollers 12a, 12b, 12c, and 12d facing the photosensitive drums 1a, 1b, 1c, and 1d inside the intermediate transfer belt 12e. A transfer bias voltage is applied by a bias application device (not shown).

  Here, the photosensitive drums 1a, 1b, 1c, and 1d rotate in the direction of the arrow, and at the same time, the intermediate transfer belt 12 rotates in the direction of the arrow A by the operation of the driving roller 12f, and the primary transfer rollers 12a, 12b, 12c, and 12d are rotated. Is applied with a positive bias. As a result, the toner images formed on the photosensitive drums 1a, 1b, 1c, and 1d are primarily transferred onto the intermediate transfer belt 12e sequentially from the toner images on the photosensitive drum 1a, and the four color toner images overlap. In this state, it is conveyed to the secondary transfer unit.

  On the other hand, the feeding / conveying device 13 includes a paper feeding roller 9 that feeds the transfer material P from the paper feeding cassette 11 that houses the transfer material P, and a conveyance roller 10 that transports the fed transfer material P. Yes. Then, the transfer material P conveyed from the feeding / conveying device 13 is conveyed to the secondary transfer portion by the registration roller pair 17.

  In the secondary transfer portion, a four-color toner image on the intermediate transfer belt 12 is secondarily transferred to the transported transfer material P by applying a positive bias voltage to the secondary transfer roller 16. After the toner image is transferred, the transfer material P is conveyed to the fixing device 14 and heated and pressed by the fixing roller 141 and the pressure roller 142 to fix the toner image on the surface. The fixed transfer material P is discharged to the paper discharge tray 21 by the paper discharge roller pair 20.

  The toner remaining on the surfaces of the photosensitive drums 1a, 1b, 1c, and 1d after the toner image transfer is removed by the cleaning blades 8a, 8b, 8c, and 8d. Further, the toner remaining on the intermediate transfer belt 12 after the secondary transfer to the transfer material P is removed by the transfer belt cleaning device 22. The toner removed from the intermediate transfer belt 12 passes through a waste toner conveyance path (not shown) (part indicated by a broken line in the figure) and is collected in a waste toner collection container 23.

Next, FIG. 2 shows a detailed view of the process cartridge 7 in which the drum unit 4 and the developing unit 5 provided in the drum unit 4 so as to be able to contact and separate from the photosensitive drum 1 are integrally formed. FIG. 2A shows a state where the photosensitive drum 1 provided in the drum unit 4 and the developing roller 50 provided in the developing unit 5 are separated from each other. The developing unit 5 is rotatably supported by the developing unit support shaft 4p with respect to the drum unit 4. As shown in FIG. 2B described later, a pressing force T is always applied to the developing unit 5 in the direction of the drum unit 4 by a developing roller pressing member (not shown) made of an elastic body such as a spring.

  The developing unit 5 keeps the developing roller 50 and the photosensitive drum 1 in the separated state against the pressing force T by the contact / separation force FR from the contact / separation mechanism 6 described later acting on the contact / separation part 5r. FIG. 2B shows a state where the photosensitive drum 1 provided in the drum unit 4 and the developing roller 50 provided in the developing unit 5 are in contact with each other. As shown in FIG. 2B, when the contact / separation force FR from the contact / separation mechanism 6 does not act on the contact / separation portion 5r, the developing roller 50 contacts the photosensitive drum 1 by the pressing force T. .

[Details of contact / separation mechanism]
3 and 4 show details of the contact / separation mechanism 6 as the contact / separation device employed in this embodiment. The contact / separation mechanism 6 mainly includes an contact / separation lever 61 rotatably provided on the contact / separation lever shaft 61a, an contact / separation cam 62 that acts on the contact / separation lever 61 to rotate the contact / separation lever 61, and And a cam drive source 63 as drive means for rotating the contact / separation cam 62. And the cam control apparatus 64 which controls this cam drive source 63 is also included. The cam control device 64 includes a phase detection device (not shown) that detects the phase of the contact / separation cam 62, and the developing roller 50 is in contact with or separated from the photosensitive drum 1 based on the detection result of the phase detection device. The contact / separation cam 62 is controlled by the cam drive source 63 so as to be in the position.

  The contact / separation cam 62 is pivotally supported by the shaft 62a and acts on the contact / separation cam follower 61r of the contact / separation lever 61 at the contact / separation cam surface 62c to rotate the contact / separation lever 61. As shown in FIG. 4, the contact / separation lever 61 applies a contact / separation force FR to the contact / separation portion 5r via the development unit contact / separation member 61p, and the development unit 5 rotates around the development unit support shaft 4p. The roller 50 is separated from the photosensitive drum 1.

[Contact and separation when a process cartridge is installed]
Since the pressing force T that always contacts the developing roller 50 against the photosensitive drum 1 acts on the developing unit 5, the developing roller 50 comes into contact with the photosensitive drum 1 when the process cartridge 7 is removed from the main body. As shown in FIG. 5, the process cartridge 7 (7a, 7b, 7c, 7d) is provided with a mounting guide 4g. When the process cartridge 7 (7a, 7b, 7c, 7d) is mounted, the mounting guide 4g follows the guide rail 101 (101a, 101b, 101c, 101d (101d is not shown)) in the direction of the arrow in FIG. It is configured to move to. During the process of inserting / removing the process cartridge 7, the contact / separation portion 5 r acts on the mounting cam surface 60 a of the mounting guide 60 shown in FIG. 3 to rotate the developing unit 5 in a direction away from the photosensitive drum 1.

[Charging drum contact / separation mechanism]
FIG. 6 shows an example of a charging drum contact / separation mechanism 40 that contacts and separates the charging drum 2, which is an example of process means for executing a process related to latent image formation, with respect to the photosensitive drum 1. When the process cartridge 7 is shipped, the charging drum 2 is held in a state of being separated from the photosensitive drum 1 by the separation holding member 41. The separated holding member 41 is held in a separated state by, for example, the hook 41 a engaging with an engaging member (not shown) provided in the drum unit 4. The separation holding member 41 and the hook 41a constitute a holding means in this embodiment. During the contact operation of the developing unit 5, the developing unit 5 rotates about the developing unit support shaft 4p, and for example, the release member 52 interlocked with the rotating operation is rotated in the arrow direction. The release member 52 acts on the separation holding member 41 and releases the engagement between the hook 41 a and the engagement member, thereby releasing the separation state of the charging drum 2 from the photosensitive drum 1. As a result, the charging drum 2 comes into contact with the photosensitive drum 1 by the action of a biasing spring (not shown).

[Removal of protective member]
When the main body 100 of the image forming apparatus is shipped, the developing roller 50 is maintained in a state of being separated from the photosensitive drum 1 by the action of the contact / separation lever 61. For this reason, the charging drum 2 is also held in a state of being separated from the photosensitive drum 1. However, if the reaction force of the contact / separation force FR continues to act on the contact / separation cam 62 via the contact / separation lever 61 during transportation of the main body 100 of the image forming apparatus, the contact / separation cam 62 rotates due to vibration. There is. As a result, the developing roller 50 may come into contact with the photosensitive drum 1 while the main body 100 of the image forming apparatus is being transported.

  Further, during transportation of the main body 100 of the image forming apparatus, the process cartridge 7 may be loaded by several tens of times its own weight, and thus the process cartridge 7 may move inside the main body during transportation. Then, depending on the positional relationship between the process cartridge 7 and the contact / separation lever 61, the contact / separation force FR may not be applied to the contact / separation part 5r. As a result, during the transportation of the main body 100 of the image forming apparatus, the developing roller 50 may come into contact with the photosensitive drum 1 and the charging drum 2 may be released from the separated state from the photosensitive drum 1.

  Normally, it is difficult to prevent the process cartridge 7 from moving even when a load several tens of times its own weight is applied. Accordingly, the protective member 30 that is removable from the process cartridge 7 is provided so that the developing roller 50 and the photosensitive drum 1 can be maintained apart from each other even when an excessive load is applied to the main body 100 of the image processing apparatus. It is possible. The protective member 30 (30a, 30b, 30c, 30d) is a member that keeps the distance between the developing roller 50 and the photosensitive drum 1 at a certain level or more by being sandwiched between the developing unit 5 and the drum unit 4 as shown in FIG. This also prevents the separation between the photosensitive drum 1 and the charging drum 2 from being released.

  Since the developing roller 50 cannot be brought into contact with the photosensitive drum 1 in a state where the protective member 30 is mounted, it is necessary to remove the protective member 30 when the image forming apparatus is used after completion of transportation. If the user forgets to remove the protective member 30 during use of the image forming apparatus (for example, during image formation), there is a risk that an inconvenience such as an image not being output may occur. In order to prevent forgetting to remove the protective member 30, the tape 300 and the warning tag 301 provided on the protective member 30 as shown in FIG. 8 are displayed to the user even when the front door 102 of the main body 100 of the image forming apparatus is closed. It is conceivable to arrange at an easily understandable position. Examples of the position that can be easily understood by the user include the upper surface of the main body 100. It is also conceivable to temporarily fix the tape 300 to the front door 102 so as to remove the protective member 30 in conjunction with the operation of opening the front door 102.

  However, even if the configuration as described above is introduced, the user may remove the tape 300 without fully understanding the warning and operate the main body 100 without removing the protective member 30.

[Details of detection of forgetting to remove protective member]
As described above, when the user performs the removal operation of the protection member 30, even if an easy-to-understand procedure and warning are provided, it is difficult to sufficiently prevent forgetting to remove the protection member 30. Although a method of directly detecting that the protective member 30 is mounted by a sensor or the like is conceivable, a configuration using a plurality of process cartridges 7 such as a color image forming apparatus requires a large number of sensors and the like in terms of cost. There was a problem.

  Therefore, in this embodiment, as shown in FIG. 9, in order to detect forgetting to remove the protection member 30, a cartridge sensor 73 that detects that the process cartridge 7 is attached to the main body 100 of the image forming apparatus. It was decided to use. Further, a torque sensor 72 that measures the drive torque of the drive source 70 that drives the photosensitive drum 1 is used. Here, the drive source 70 corresponds to a drive unit in this embodiment. The torque sensor 72 corresponds to load measuring means.

  In this embodiment, when the main body 100 is turned on, the cartridge sensor 73 detects whether or not the process cartridge 7 is mounted on the main body. The cartridge sensor 73 has a light emitting part 73a and a light receiving part 73b, and the process cartridge 7 is optically determined depending on whether the light emitted from the light emitting part 73a is incident on the light receiving part 73b or blocked by the mounting guide 4g. It detects the presence or absence of. In addition, the cartridge sensor may be, for example, an electrical sensor provided so that the contact is energized when the process cartridge 7 is mounted on the main body. The cartridge sensor 73 constitutes a cartridge detection unit in this embodiment.

  Here, when it is detected that the process cartridge 7 is attached to the main body 100, the initialization of the main body 100 is continued. Then, the rotation of the driving source 70 is transmitted to the photosensitive drum 1 through the coupling 71, and the photosensitive drum 1 is rotationally driven.

  FIG. 10 shows a torque waveform of the driving source 70 when the driving source 70 rotates the photosensitive drum 1 and the developing unit 5 is driven after a predetermined period of time and the developing roller 50 and the photosensitive drum 1 come into contact with each other. . The horizontal axis represents time, and the vertical axis represents the torque of the drive source 70. Further, the waveform indicated by the solid line in FIG. 10 is a torque waveform when the standard process cartridge 7 is mounted. In addition, a broken line indicates a torque waveform when the process cartridge 7 having a torque that is substantially minimum among the variations and a torque waveform when the process cartridge 7 having the maximum torque among the variations are mounted. It is. The torque sensor 72 in the present embodiment is a sensor that measures a current value flowing in the drive source 70 by a magnetic field. The torque sensor 72 may measure the value of the current flowing in the drive source 70 by detecting the voltage across the reference resistor. Also, a sensor based on another principle, such as one that measures the amount of elastic deformation of the components of the coupling 71 that transmits driving force by a phase difference of a strain gauge or an encoder, may be used.

  In FIG. 10, since the developing roller 50 is separated from the photosensitive drum 1 at the start of the initial operation, the rotational load of the coupling 71 and the photosensitive drum 1 acts on the driving source 70 (regions t1, t2). t <b> 1 is an overshoot region of the drive source 70. The measurement of the torque of the drive source 70 is performed in the t2 region where the drive torque is stable. The contact driving of the developing roller 50 to the photosensitive drum 1 is performed at time tp. When the developing roller 50 contacts the photosensitive drum 1, the rotational load on the photosensitive drum 1 increases. Due to the influence of this load fluctuation, the drive source 70 once overshoots in the region t3. In the present embodiment, the torque of the drive source 70 after the contact between the developing roller 50 and the photosensitive drum 1 is measured after the drive source 70 is stabilized after the load change. If the torque of the drive source 70 after the contact driving between the developing roller 50 and the photosensitive drum 1 is larger than a predetermined threshold value, it is considered that the developing roller 50 and the photosensitive drum 1 are actually in contact. It is detected that the protective member 30 is removed. Here, the threshold value is obtained in advance by experiments or the like as a torque value that can be detected with sufficient accuracy whether or not the protective member 30 has been removed by the above-described method.

  Here, when the variation in the load due to the process cartridge 7 is small, the absolute value of the torque of the drive source 70 after the operation in which the developing roller 50 contacts the photosensitive drum 1 (after the contact / separation operation) as described above is used. The presence or absence of the protection member 30 may be detected. On the other hand, when the load variation due to the process cartridge 7 is large, the presence / absence of the protective member 30 is detected based on torque fluctuation amounts (ΔT0, ΔT1, ΔT2) before and after the contact of the developing roller 50 with the photosensitive drum 1 is driven. May be. In this case, when the torque fluctuation amount is larger than a predetermined threshold value, it is considered that the developing roller 50 and the photosensitive drum 1 are actually in contact with each other, so that it is detected that the protective member 30 has been removed. Is done. Here, the threshold value is obtained in advance by an experiment or the like as a value of a torque fluctuation amount that can be detected with sufficient accuracy whether or not the protective member 30 has been removed.

  In this embodiment, after the attachment of the process cartridge 7 to the main body 100 is detected, and after the driving of the developing roller 50 to contact the photosensitive drum 1, the increase in torque is equal to or less than the threshold value, the protective member It is determined that 30 is not removed. Then, a warning message is displayed to prompt the user to remove the protective member 30.

  As shown in FIG. 9, the cartridge sensor 73 and the torque sensor 72 are electrically connected to the control device 200, information on whether or not the process cartridge 7 is attached to the main body 100, and a drive source The torque information 70 is output to the control device 200. In the control device 200, it is detected from these pieces of information whether or not the protective member 30 has been removed. Therefore, in this embodiment, the control device 200 constitutes a protective member detection unit.

  In this embodiment, as described above, the absolute value of the torque of the drive source 70 after the contact operation (contact drive) of the developing roller 50 to the photosensitive drum 1 or the developing roller 50 to the photosensitive drum 1 is performed. The presence or absence of the protective member 30 was detected using the torque fluctuation amount before and after the contact drive. In contrast, the absolute value of the torque of the driving source 70 after the developing roller 50 is separated from the photosensitive drum 1 (separated driving) or the torque fluctuation amount before and after the developing roller 50 is driven to separate from the photosensitive drum 1 is used. The presence or absence of the protective member 30 may be detected. That is, in the present invention, the absolute value of the torque of the drive source 70 after the contact / separation operation (contact / separation drive) between the developing roller 50 and the photosensitive drum 1 or before and after the contact / separation drive between the developing roller 50 and the photosensitive drum 1 is performed. The presence / absence of the protective member 30 may be detected using the torque fluctuation amount.

  Next, a second embodiment of the present invention will be described. Here, only differences between the second embodiment and the first embodiment will be described. Unless otherwise indicated, the hardware configuration of the image forming apparatus in this embodiment is the same as that described in the first embodiment.

  In this embodiment, forgetting to remove the protection member 30 is detected by measuring the torque of the cam drive source 63 in the contact / separation mechanism 6 that performs the contact / separation operation between the developing roller 50 and the photosensitive drum 1. Here, when the developing unit 5 is separated from the photosensitive drum 1 in a state where the protective member 30 is not removed, the contact / separation force FR (reaction force) does not act on the contact / separation lever 61. Accordingly, no load other than the operating resistance necessary for driving the contact / separation mechanism 6 with no load acts on the cam drive source 63. Since the pressing force T of the developing unit 5 is determined by a spring or the like provided in the process cartridge 7, the contact / separation force FR is a stable value. Therefore, by measuring the torque of the cam drive source 63 when the developing roller 50 is separated from the photosensitive drum 1, it is possible to detect forgetting to remove the protective member 30 with high accuracy.

  FIG. 11 shows a torque waveform of the cam drive source 63 when the developing roller 50 is separated from the photosensitive drum 1. In FIG. 11, t <b> 4 is an overshoot period of the torque waveform of the cam drive source 63. Also in this embodiment, the initial operation of the main body 100 detects that the process cartridge 7 is mounted, and the torque of the cam drive source 63 when the developing roller 5 is once separated from the photosensitive drum 1 is below a predetermined threshold value. In this case, it is determined that the protective member 30 has not been removed. Here, the threshold value is obtained in advance through experiments or the like as a torque value that can be detected with sufficient accuracy whether or not the protective member 30 has been removed by the method according to the present embodiment. If it is determined that the protective member 30 has not been removed, a warning message is displayed to the user to prompt the user to remove the protective member 30.

In this embodiment, the torque of the cam drive source 63 can be measured in the cam control device 64 shown in FIG. Further, the torque value of the cam drive word 3 measured by the cam control device 64 is sent to the control device 200 and is compared with a threshold value by the control device 200 to detect whether or not the protective member 30 has been removed. . Therefore, also in the embodiment of the phone, the control device 200 constitutes a protective member detection means.

  In the present embodiment, due to the configuration of the contact / separation mechanism 6 shown in FIGS. 3 and 4, based on the torque of the cam drive source 63 when the developing roller 50 is separated from the photosensitive drum 1. Thus, it was detected whether or not the protective member 30 was removed. However, depending on the configuration of the contact / separation mechanism, torque may be required for the cam drive source 63 during the contact operation of the developing roller 50 with the photosensitive drum 1. In such a case, it is detected whether or not the protective member 30 has been removed based on the torque of the cam drive source 63 when the developing roller 50 is brought into contact with the photosensitive drum 1. Of course. That is, in the present invention, it is detected whether or not the protective member 30 has been removed based on the load when the cam drive source 63 applies a driving force to the process cartridge 7 during the contact / separation operation.

1 (1a, 1b, 1c, 1d) ... photosensitive drum 4 (4a, 4b, 4c, 4d) ... drum unit 4g ... installation guide 5 (5a, 5b, 5c, 5d) ... development unit 5r ... Separating part 6 ... contact / separation mechanism 7 (7a, 7b, 7c, 7d) ... process cartridge 30 ... protective member 50 (50a, 50b, 50c, 50d) ... developing roller 63 ... cam drive source 64 ... Control device 70 ... Drive source 72 ... Torque sensor 73 ... Cartridge sensor 100 ... Image forming apparatus body T ... Pressing force FR ... Contact / separation force ΔT ... Photosensitive drum drive at the time of developing roller contact and separation Torque difference tp ... Development roller contact start point

Claims (5)

A latent image carrier and a developing unit provided so as to be able to come into contact with and separate from the latent image carrier and developing the latent image formed on the latent image carrier by contacting the latent image carrier are integrally configured. The process cartridge can be mounted, and a protective member is attached when the process cartridge is transported with the process cartridge mounted, so that the developing means is kept away from the latent image carrier and is protected during use. An image forming apparatus configured to remove a member,
Cartridge detecting means for detecting that the process cartridge is mounted in the image forming apparatus;
A driving unit that applies a driving force to the process cartridge during image formation or when the developing unit and the latent image carrier are in contact with or separated from each other;
Load measuring means for measuring a load when the driving means applies a driving force to the process cartridge, and
The apparatus further comprises protection member detection means for detecting whether or not the protection member is attached based on a detection result by the cartridge detection means and a value of the load measured by the load measurement means. Image forming apparatus. The process cartridge is
Process means for detachably contacting the latent image carrier and performing a process relating to latent image formation by contacting the latent image carrier;
Holding means for holding the process means in a state of being separated from the latent image carrier,
2. The image forming apparatus according to claim 1, wherein the holding unit releases the holding of the state in which the process unit is separated from the latent image carrier when the developing unit contacts the latent image carrier. apparatus. The drive means is a drive source that rotationally drives the latent image carrier during image formation,
The protective member detecting means includes
The load measured by the load measuring means after the cartridge detecting means detects that the process cartridge is mounted on the image forming apparatus and the contacting and separating operation of the developing means and the latent image carrier. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus detects that the protective member is attached when the value is equal to or less than a predetermined threshold value. 4. The drive means is a drive source that rotationally drives the latent image carrier during image formation,
The protective member detecting means includes
The cartridge detecting means detects that the process cartridge is mounted on the image forming apparatus, and is measured by the load measuring means before and after the contacting and separating operation of the developing means and the latent image carrier. 3. The image forming apparatus according to claim 1, wherein when the load difference is equal to or less than a predetermined threshold, it is detected that the protective member is attached. The process cartridge further includes a contact / separation device for performing a contact / separation operation between the developing unit and the latent image carrier,
The drive means is a drive source that drives the contact / separation device during the contact / separation operation of the developing means and the latent image carrier,
The protective member detecting means includes
The load detected by the load measuring means when the cartridge detecting means detects that the process cartridge is mounted on the image forming apparatus and the contacting and separating operation of the developing means and the latent image carrier is performed. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus detects that the protective member is attached when the value is equal to or less than a predetermined threshold value. 4.

Images