JP2014092631A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce performance deterioration of a scanner unit 11.SOLUTION: An image forming apparatus in which the scanner unit 11 including a polygon mirror 61 is opened and closed together with a maintenance door 10 includes a lock mechanism capable of limiting that the maintenance door 10 is opened from its closed state during an image forming operation, an opening/closing operation detection mechanism detecting operation for opening the maintenance door 10, and decelerating means for decelerating the rotational speed of the polygon mirror 61, when the opening/closing operation detection mechanism detects the operation for opening, while the polygon mirror 61 is rotated. When the rotational speed of the polygon mirror 61 becomes a predetermined speed or less, the limitation by the lock mechanism is released and the maintenance door 10 can be opened.

Description

  The present invention relates to an image forming apparatus.

2. Description of the Related Art Conventionally, there has been known an image forming apparatus that forms an electrostatic latent image by scanning and exposing a laser beam to the surface of a photosensitive drum with an optical scanner unit (hereinafter simply referred to as a scanner unit) as an exposure unit including a rotating polygon mirror. It has been.
Patent Document 1 (FIGS. 11, 12, etc.) discloses a configuration in which a cartridge is accessed by opening an opening / closing cover that holds a scanner unit, and is detachable from an image forming apparatus. In this way, by holding the scanner unit on the opening / closing cover and moving the scanner unit together with the opening / closing cover, it is possible to easily secure a cartridge replacement work space.

Japanese Patent Laid-Open No. 5-281798

  However, in recent years, polygon mirrors used in scanner units have been rotated at a high speed. Therefore, when the opening / closing cover is opened while the polygon mirror is rotating at a high speed, the motor shaft and the bearing that rotate the polygon mirror may be worn or deformed due to changes in the attitude of the motor shaft and the bearing. In this case, there is a concern that the performance of the scanner unit may be deteriorated, such as shortening the life of the scanner unit. In particular, when a non-contact type bearing such as an air bearing is used for speeding up, the concern is increased.

  In view of the above problems, an object of the present invention is to reduce performance deterioration of a scanner unit as an exposure unit.

In order to achieve the above object, the present invention provides:
A door that can be opened and closed with respect to the device body;
An exposure unit comprising a rotary polygon mirror, and exposing the laser beam to the photosensitive member by irradiating the rotary polygon mirror with laser light; and
With
In the image forming apparatus in which the exposure unit opens and closes together with the door,
Lock means capable of restricting opening of the door from a closed state;
Detecting means for detecting an operation for opening the door;
A decelerating means for decelerating the rotational speed of the rotating polygon mirror when the detecting means detects the opening operation while the rotating polygon mirror is rotating;
With
When the rotation speed of the rotary polygon mirror becomes a predetermined speed or less by the speed reduction means, the restriction on the opening of the door by the locking means is released, and the door can be opened.

According to the present invention, it is possible to reduce performance deterioration of a scanner unit as an exposure unit.

1 is an external perspective view of an image forming apparatus according to Embodiment 1. FIG. 1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to a first embodiment. 1 is a schematic cross-sectional view of an image forming unit mounted on an image forming apparatus according to a first embodiment. 1 is an external perspective view of an image forming unit mounted on an image forming apparatus according to Embodiment 1. FIG. Enlarged perspective view of positioning portion between developing roller and photosensitive drum Schematic sectional view showing a state where the developing roller is in contact with the photosensitive drum Schematic sectional view showing a state where the developing roller is separated from the photosensitive drum External perspective view of polygon mirror and motor Schematic sectional view showing a state where the maintenance door is slightly opened in the first embodiment Schematic sectional view showing a state in which the maintenance door is opened in the first embodiment External appearance perspective view for demonstrating the structure of the locking mechanism which concerns on Example 1. FIG. Schematic perspective view for explaining the opening / closing operation detection mechanism according to the first embodiment. The external appearance perspective view which shows the state which the maintenance door opened in Example 2 The expanded perspective view for demonstrating operation | movement of the fixed arm which concerns on Example 2. FIG. The expanded perspective view for demonstrating the structure of the locking mechanism which concerns on Example 2. FIG. Enlarged perspective view for explaining an opening / closing operation detection mechanism according to the second embodiment. Flowchart diagram for releasing lock mechanism Flowchart diagram for releasing lock mechanism

  Hereinafter, the form of a present Example is illustrated with reference to drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not intended that the scope of the present invention be limited to the following embodiments.

(Configuration of Image Forming Apparatus According to Embodiment 1)
The image forming apparatus according to the first embodiment will be described with reference to FIGS. FIG. 1 is an external perspective view of the image forming apparatus according to the first embodiment. FIG. 2 is a schematic cross-sectional view illustrating the configuration of the image forming apparatus according to the first embodiment. FIG. 3 is a schematic cross-sectional view of an image forming unit mounted on the image forming apparatus according to the first embodiment. FIG. 4 is an external perspective view of the image forming unit mounted on the image forming apparatus according to the first embodiment. FIG. 5 is an enlarged perspective view of a positioning portion between the developing roller and the photosensitive drum according to the first embodiment. FIG. 6 is a schematic cross-sectional view showing a state where the developing roller is in contact with the photosensitive drum. FIG. 7 is a schematic cross-sectional view showing a state in which the developing roller is separated from the photosensitive drum. FIG. 8 is an external perspective view of the polygon mirror and the motor.

  The image forming apparatus 100 according to the first embodiment is a four-color full-color laser printer using an electrophotographic process. The image forming apparatus 100 forms an image on a recording medium such as a sheet based on an electrical image signal input from an external host device (not shown) such as a personal computer, an image reader, or a counterpart facsimile machine.

  In the following description, with respect to the image forming apparatus (hereinafter also referred to as the apparatus main body) 100, the direction in which the sheet feeding cassette 19 shown in FIG. 1 is pulled out is the front side (front side), and the opposite side is the rear side. Further, the direction from the rear side of the apparatus main body 100 to the front side is defined as the front direction, and the opposite direction is defined as the rear direction. In addition, a direction from right to left when the apparatus main body 100 is viewed from the front side is a left direction, and a direction from left to right is a right direction.

As shown in FIG. 2, the image forming apparatus 100 includes an image forming unit 200.
The image forming unit 200 includes a sub frame 31, a photosensitive unit 32, and an intermediate transfer unit 34. The sub frame 31 is detachably provided on the main frame 110 of the apparatus main body 100. The photosensitive units 32 are arranged in the subframe 31 at a predetermined interval. The intermediate transfer unit 34 is rotatably attached to the subframe 31, transfers a toner image as a developer image from the photosensitive unit 32, and transfers the toner image onto a sheet P that is a recording medium. Further, a developing cartridge 33 that supplies toner as a developer to the photosensitive unit 32 is connected to the image forming unit 200. The developing cartridge 33 that accommodates toner as a consumable is provided in the image forming apparatus in a replaceable manner by opening a maintenance door 10 that can be opened and closed provided in the image forming apparatus 100. The photosensitive unit 32, the developing cartridge 33, and the like are integrated into cartridges as first to fourth process cartridges PY to PK. Each color cartridge (yellow Y, magenta M, cyan C, black K) is accommodated in the developing cartridge 33 provided in each process cartridge PY, PM, PC, PK.

  As shown in FIG. 3, the subframe 31 temporarily holds an intermediate transfer frame 31a that supports the intermediate transfer unit 34, a photosensitive member support unit 31b that supports the photosensitive unit 32, and a developing cartridge 33 that is mounted on the image forming unit. A developing device connecting unit 31c. The intermediate transfer frame 31 a is configured to support both ends of the central shaft 34 a of the intermediate transfer unit except for the central portion that contacts the recording medium toward the main frame 110, and the developing cartridge 33 is connected to the photosensitive unit 32. It has a shape to guide.

  As shown in FIG. 3, the photosensitive unit 32 is connected to a photosensitive drum (photosensitive member) 32a as a first image carrier, a charging roller 32b, a cleaning device 32c, and a photosensitive member supporting unit 31b of the subframe 31. A photosensitive member case 32d. The charging roller 32b uniformly charges the surface of the photosensitive drum 32a. The cleaning device 32c removes the toner remaining on the surface of the photosensitive drum 32a. As shown in FIG. 3, a plurality of photosensitive drums 32 a are arranged at a predetermined interval with respect to the intermediate transfer unit 34.

  A drive output unit on the apparatus main body side is connected to a drive input unit of the photosensitive unit 32 to each photosensitive unit 32 mounted in the mounting position in the apparatus main body. The power supply system on the apparatus main body side is electrically connected to the electrical contacts of the photosensitive unit 32.

  As shown in FIGS. 3 and 4, the developing cartridge 33 has a developing device case 33a, a developing roller 33b, a developing device 33c, a supply roller 33d, a contact unit 33e, and a support means 33f. The developing device case 33 a is connected to the developing device connection unit 31 c of the subframe 31. The developing roller 33b is provided at one end of the developing device case 33a. As shown in FIG. 5, the developing roller 33b is supported while being engaged with both end portions of the rotation shaft so that the position relative to the photosensitive drum 32a is determined by the positioning means 39 provided in the photosensitive member case 32d. Has been. As shown in FIG. 6, in the first embodiment, the developing roller 33b is provided in contact with the photosensitive drum 32a. However, as shown in FIG. 7, the developing roller 33b may be configured to be separated from the photosensitive drum 32a. FIG. 7 shows a configuration in which a spacer 33f engaged with the end of the developing roller 33b is brought into contact with the photosensitive drum 32a so that the position is determined in a state where the developing roller 33b is kept at a certain distance from the photosensitive drum 32a. .

  The developing device 33c contains toner. The supply roller 33d supplies the toner stored in the developing device 33c to the developing roller 33b. The contact unit 33e presses the developing roller 33b against the photosensitive drum 32a with a predetermined pressure. The support means 33f supports the sub frame 31 so as to be stably held.

  As shown in FIG. 2, a paper feeding unit 18 is disposed below the image forming unit 200. The paper feed unit 18 includes a paper feed cassette 19, a paper feed roller 20, a separation pad 21, and the like. The paper feed cassette 19 is provided freely from the front side of the apparatus main body 100.

  As shown in FIG. 2, a fixing device 23 and a paper discharge roller pair 24 are disposed on the upper rear side in the apparatus main body 100. The fixing device 23 includes a fixing film unit 23a and a pressure roller 23b. The paper discharge roller pair 24 includes a paper discharge roller 24a and a paper discharge roller 24b. The upper surface of the apparatus main body 100 is a paper discharge tray 25.

  As shown in FIG. 2, a scanner unit 11 as an exposure unit integrated with the maintenance door 10 is provided in front of the developing cartridge 33 so as to move in accordance with the opening / closing operation of the maintenance door 10. Yes. The control unit 300 is a control unit that controls the lock mechanism of the maintenance door 10, which will be described in detail later, and includes an arithmetic device such as a CPU. As shown in FIG. 8, the scanner unit 11 includes a polygon mirror 61 as a rotary polygon mirror that can rotate around a rotation axis, and a motor 62 that rotates the polygon mirror 61.

  The polygon mirror 61 is integrally fixed to the rotating shaft 63 of the motor 62. A rotating shaft 63 of the motor 62 is supported by a fluid dynamic pressure bearing (not shown). The configurations of the polygon mirror 61 and the motor 62 are not limited to the above-described shaft rotation type. For example, the motor 62 may be a sleeve rotation type that rotates a sleeve fitted on a fixed shaft, and the polygon mirror 61 may be integrally fixed to the motor 62 sleeve. The scanner unit 11 outputs laser light L modulated in accordance with image information of each color input from an external host device, and scans and exposes each photosensitive drum 32a (on the photosensitive member). In scanning with the laser beam L, a polygon mirror 61 as a rotary polygon mirror provided in the scanner unit 11 is rotated by a motor 62, the laser beam L is irradiated onto the polygon mirror 61, and the laser beam L is left and right on the photosensitive drum 32a. Realized by shaking.

  The motor 62 is determined by the image forming speed and resolution of the image forming apparatus, the number of faces of the polygon mirror 61 (four faces in the example shown in FIG. 16), and the like, and rotates at a high speed of about several tens of thousands rpm.

  Here, when the maintenance door 10 is opened during the image forming operation, the posture of the scanner unit 11 changes while the polygon mirror 61 is driven to rotate at high speed. For this reason, there is a concern that a force is applied to the rotating shaft or bearing of the polygon mirror 61 in a direction orthogonal to the rotating shaft direction due to the inertia load, thereby reducing the life of the motor 62 due to wear, deformation, etc., and generating noise. In particular, when a non-contact type air bearing or the like is used for the bearing, the concern is increased. Further, in the configuration in which the maintenance door 10 is opened forward and easily falls freely when opened as in the first embodiment, there is a high possibility that damage to the bearing of the rotating shaft of the polygon mirror 61 will occur.

(Image Forming Operation of Image Forming Apparatus According to Embodiment 1)
Next, an image forming operation for the image forming apparatus according to the first embodiment to form a full color image will be described with reference to FIGS. The photosensitive drum 32a of each photosensitive unit 32 is rotationally driven at a predetermined control speed in the clockwise direction of the arrow in FIG. In synchronization with this drive, the charging roller 32b uniformly charges the surface of the photosensitive drum 32a to a predetermined polarity and potential at a predetermined control timing in each photosensitive unit 32. In synchronization with this drive, the scanner unit 11 is also driven. The scanner unit 11 performs scanning exposure with the laser light L modulated according to the image signal of the corresponding color on the surface of each photosensitive drum 32a, and the electrostatic latent image according to the image signal of the corresponding color on the surface of each photosensitive drum 32a. Form. The formed electrostatic latent image is developed as a toner image by supplying toner from the developing cartridge 33.

  By the image forming operation as described above, a Y toner image corresponding to the yellow component of the full color image is formed on the first photosensitive drum 32a of the first process cartridge PY, and the toner image is transferred onto the intermediate transfer unit 34. The primary transfer.

  An M color toner image corresponding to the magenta component of the full color image is formed on the second photosensitive drum 32a of the second process cartridge PM, and the toner image is already transferred onto the intermediate transfer unit 34. The toner image is superimposed and primarily transferred.

  A C color toner image corresponding to the cyan component of the full color image is formed on the third photosensitive drum 32a of the third process cartridge PC, and the toner image is already transferred onto the intermediate transfer unit 34. The toner image and the M color toner image are superimposed and primarily transferred.

  A K-color toner image corresponding to the black component of the full-color image is formed on the fourth photosensitive drum 32a of the fourth process cartridge PK, and the toner image is already transferred onto the intermediate transfer unit 34. The toner image is primary-transferred superimposed on the + M color + C color toner image.

  In this way, a four-color full-color unfixed toner image of Y color toner image + M color toner image + C color toner image + K color toner image is synthesized and formed on the intermediate transfer unit 34. The transfer residual toner remaining on the surface of the photosensitive drum 32a after the primary transfer of the toner image to the intermediate transfer unit 34 is removed by the cleaning device 32c.

  On the other hand, the paper feed roller 20 is driven at a predetermined timing. As a result, the paper P, which is a recording medium loaded in the paper feed cassette 19, is separated and fed by the cooperation of the paper feed roller 20 and the separation pad 21. The separately fed paper P is introduced into a nip portion (secondary transfer nip portion) between the secondary transfer roller 22 and the intermediate transfer unit 34. As a result, the four-color superimposed toner image on the intermediate transfer unit 34 is sequentially transferred onto the surface of the paper P (secondary transfer) in the course of the paper P being nipped and conveyed in the secondary transfer nip portion.

  The sheet P onto which the toner image has been secondarily transferred is separated from the surface of the intermediate transfer unit 34 and introduced into the fixing device 23, where it is heated and pressed at the fixing nip formed by the fixing film unit 23a and the pressure roller 23b. Is done. As a result, the color toner images are mixed and fixed onto the paper P.

  Then, the paper P exits the fixing device 23 and is discharged onto the paper discharge tray 25 by the paper discharge roller pair 24 as a full-color image formed product. In Example 1, the secondary transfer residual toner remaining on the surface of the intermediate transfer unit 34 after the paper P is separated is electrostatically applied to the surface of the photosensitive drum 32a in the primary transfer portion of the first process cartridge PY. And is removed by the cleaning device 32c.

(Lock mechanism in Example 1)
The image forming apparatus according to the first embodiment is locked by a lock mechanism so that the maintenance door 10 is not opened by a user operation during the above-described image forming operation. Hereinafter, a lock mechanism as a lock unit that can restrict opening of the maintenance door from a closed state will be described with reference to FIGS. 9 to 11. FIG. 9 is a schematic cross-sectional view illustrating a state where the maintenance door is slightly opened in the first embodiment. FIG. 10 is a schematic cross-sectional view illustrating a state in which the maintenance door is opened in the first embodiment. 11A and 11B are external perspective views for explaining the configuration of the locking mechanism according to the first embodiment. FIG. 11A is an external perspective view showing a non-locking state, and FIG. 11B is a locked state. It is.

  As shown in FIGS. 9 and 10, the maintenance door 10 is provided with a lock claw 47, and the main frame 110 of the image forming apparatus 100 is provided with a hook 45. In a state where the maintenance door 10 is closed, the hook 45 is biased by a spring 46 and meshes with the lock claw 47 to restrict the maintenance door 10 from opening.

  When the lock is not performed (hereinafter, when the lock is released), the lock pawl 47 resists the force of the spring 46 as in the state in which the maintenance door 10 is slightly rotated around the rotation center 41 shown in FIG. Then lift the hook 45 and get over it. Therefore, as shown in FIG. 10, the maintenance door 10 can be opened, and the developing cartridge 33 including the developing device 33c that stores toner as a consumable can be replaced.

  As shown in FIGS. 11A and 11B, the lock mechanism includes a solenoid 48, a shutter 49, and a torsion coil spring 50.

  When the lock is released, the shutter 49 is rotated by the action of the torsion coil spring 50 as shown in FIG. In this state, when the lock claw 47 gets over the hook 45, the engagement between the lock claw 47 and the hook 45 is released, and the maintenance door 10 can be opened. On the other hand, when locked, the shutter 49 is rotated by the operation of the solenoid 48 and moved onto the hook 45 as shown in FIG. As a result, the movement of the hook 45 is restricted, and even if the user tries to open the maintenance door 10, the lock claw 47 cannot get over the hook 45 and the engagement between the lock claw 47 and the hook 45 cannot be released. Therefore, the lock of the maintenance door 10 is maintained and opening is restricted.

  In addition, the image forming apparatus according to the first embodiment includes a deceleration unit that outputs a command for decelerating and stopping the rotation speeds of the polygon mirror 61 and the motor 62 during the image forming operation. In addition, the control unit 300 includes a rotation detection unit that can detect a value related to the rotation speed (the number of rotations per unit time) of the motor 62. In the image forming apparatus according to the first embodiment, the control unit 300 determines that the rotational speed of the polygon mirror 61 has become equal to or lower than a predetermined speed. The lock is released.

(Opening / closing operation detection mechanism in Embodiment 1)
Next, referring to FIG. 12, the opening / closing operation detection mechanism as a detection means for detecting the operation of the maintenance door 10 by the user that decelerates the rotation speed of the polygon mirror 61 and the motor 62 by the speed reduction means described above and triggers the stoppage. Will be described. FIG. 12 is a schematic perspective view for explaining the opening / closing operation detection mechanism according to the first embodiment. As shown in FIG. 12, the maintenance door 10 is provided with a handle 71, and a lever 72 is rotatably disposed therein. A sensor flag 73 is integrally provided at the end of the lever 72. The sensor flag 73 can be moved to a position where the light of the optical sensor 74 is shielded by the rotation of the lever 72. The opening / closing operation detection mechanism includes a sensor flag 73 and an optical sensor 74.

  The user puts his hand into the handle portion 71 to open the maintenance door 10 and pulls the lever 72 to rotate the lever 72 and the sensor flag 73 shields the optical sensor 74 from light. In this manner, the opening / closing operation detection mechanism detects an operation for opening the maintenance door 10 by the user (hereinafter referred to as an opening operation), that is, detecting that the user touches the handle 71 and pulls the lever 72. When the opening / closing operation detection mechanism detects that the lever 72 is pulled, it notifies (outputs) the detection to the control unit 300.

Next, the release of the lock mechanism when the user tries to open the maintenance door 10 during the image forming operation will be described with reference to the flowchart of FIG. The operation of this flowchart is executed by the control unit 300.

  First, the user pulls the lever 72 while the image forming operation is being performed and the maintenance door 10 is locked by the lock mechanism. The opening operation by the user is detected by the above-described opening / closing operation detection mechanism (S11) and notified to the control unit 300. Upon receiving the notification, the control unit 300 causes the image forming operation to be interrupted, and causes the motor 62 in the scanner unit 11 to perform a decelerating operation (stopping operation) using the decelerating unit (S12).

  The control unit 300 can detect a value related to the rotation speed (the number of rotations per unit time) of the motor 62 from the drive signal (FG signal) of the motor 62 and detect a value related to the rotation speed of the motor 62 ( S13). Then, by comparing the detected value related to the rotational speed of the motor 62 with a predetermined value stored in advance in a storage means (not shown), it is determined whether the rotational speed of the motor 62 is equal to or lower than the predetermined speed (S14). . The predetermined speed is set to a safe rotational speed with which the motor 62 is less likely to be damaged even when the maintenance door 10 is opened. The predetermined speed may be set to rotational speed = 0 in which the motor 62 is stopped. When it is determined that the detected value relating to the rotational speed is equal to or lower than the predetermined value, that is, when it is determined that the rotational speed of the motor 62 is equal to or lower than the predetermined speed, the maintenance door 10 is unlocked by the lock mechanism (S15). ). For this reason, the user can open the maintenance door 10 by pulling the handle 71. If it is determined in S14 that the rotational speed of the motor 62 is equal to or higher than the predetermined speed, the process returns to S13, and a value related to the rotational speed of the motor 62 is detected again (S13).

  Before the image forming operation is interrupted, an operation panel (not shown), an external host or the like is warned that an image is being formed, a warning sound, etc. In such a state, the image forming operation may be interrupted. With such a configuration, the user can inadvertently touch the lever 72 to prevent unexpected interruption of the image forming operation, and the operability is improved.

  Moreover, although the information regarding the rotational speed of the motor 62 is directly detected from the drive signal of the motor 62, it is not limited to this. As another method, information on the rotational speed of the motor 62 may be detected from the period of the BD signal output from a BD sensor (not shown) that detects the laser light L reflected by the polygon mirror 61. In this case, the laser beam L is emitted at a timing that can be detected by at least the BD sensor until it is determined that the rotation speed of the motor 62 is equal to or lower than the predetermined speed. When it is determined that the speed is equal to or lower than the predetermined speed, the emission of the laser light L is stopped before the maintenance door 10 is unlocked.

  Further, it is not necessary to determine the release of the lock based on the information on the rotation speed of the motor 62. Another method may be the method shown in the flowchart of FIG. Since S21, S22, and S25 are the same as S11, S12, and S15, description is abbreviate | omitted. The control unit 300 causes the control unit 300 to count the period after the start of the deceleration operation of the motor 62 in S23. Next, in S24, the count value is compared as a predetermined value to determine whether a predetermined period has elapsed since the motor 62 started the deceleration operation. The predetermined value is a value corresponding to a predetermined time from when the motor 62 starts a deceleration operation until the motor 62 falls to a safe rotational speed with little risk of damage even if the maintenance door 10 is opened. It is stored in storage means (not shown) in 300. If it is determined in S24 that the predetermined time has not elapsed since the motor 62 started the deceleration operation, the process returns to S23 and the count is continued.

In the present embodiment, the shutter 49 is rotated by the operation of the solenoid 48 and the movement of the hook 45 is restricted to be in the locked state, but the present invention is not limited to this. For example, as a mechanism for opening the maintenance door 10, the lock claw 47 may be interlocked with the lever 72. Specifically, when unlocked, the lock pawl 47 is retracted from the hook 45 by pulling the lever 72, the engagement is released, and the maintenance door 10 can be opened. Then, the shutter 49 is rotated by the operation of the solenoid 48 and the movement of the lock claw 47 or the lever 72 is restricted, so that the engagement between the lock claw 47 and the hook 45 is not released and the lock state is established.

  In the present embodiment, the opening operation of the maintenance door 10 is detected by detecting that the lever 72 is pulled and moved, but the present invention is not limited to this configuration. For example, the opening operation of the maintenance door 10 may be detected by detecting the movement of the lock claw 47 or the hook 45 or the maintenance door 10 itself when the lock claw 47 tries to get over the hook 45.

  As described above, in the first embodiment, when the rotation speed of the polygon mirror 61 becomes equal to or lower than the predetermined speed at which an excessive load is not applied to the motor 62 shaft or the like, the lock by the lock mechanism is released, and the maintenance door 10 is opened. It can be opened. As a result, it is possible to reduce wear and deformation of the motor 62 due to an inertia load accompanying a change in posture during high-speed rotation of the polygon mirror 61, and to reduce performance deterioration of the scanner unit 11 including the polygon mirror 61.

(Example 2)
Next, an image forming apparatus according to the second embodiment will be described with reference to FIGS. The present embodiment is the same as the first embodiment except for the unlocking method of the lock mechanism, and the other parts are the same. Therefore, the description of the same parts is omitted and the same reference numerals are given. FIG. 13 is an external perspective view illustrating a state in which the maintenance door is opened in the second embodiment. FIG. 14 is an enlarged perspective view for explaining the operation of the fixed arm according to the second embodiment. FIG. 15 is an enlarged perspective view for explaining the configuration of the locking mechanism according to the second embodiment. FIG. 15A shows a state in which the pendulum arm as the locking means is in the locking position. 15 (b) shows a state in which the pendulum arm is in the non-locking position. Here, the locking position is a position where the maintenance door 10 is locked to restrict the opening, and the non-locking position is a position where the maintenance door 10 is not locked.
The pendulum arm is in the locked position when the drive unit 400 is driven, and is in the unlocked position when the drive unit 400 is stopped. FIG. 16 is an enlarged perspective view for explaining the configuration of the opening / closing operation detection mechanism according to the second embodiment. Note that the configuration and operation related to the image forming operation of the image forming apparatus according to the second embodiment are the same as those described in the first embodiment. Omitted.

  As shown in FIG. 13, the image forming apparatus according to the second embodiment includes a fixed arm 81 on the maintenance door 10, and corresponds to the fixed arm 81 on the side wall of the opening of the apparatus main body 100 in a state where the maintenance door 10 is opened. A fixing hole 85 is provided.

  As shown in FIG. 14A, immediately before the maintenance door 10 is closed, the fixed arm 81 is pushed by the side wall of the opening of the apparatus main body 100 and passes while pushing the spring 82. Then, as shown in FIG. 14B, the fixing and fixing of the fixing arm 81 into the fixing hole 85 is completed by the force of the spring 82 with the maintenance door 10 closed.

  Furthermore, the locking mechanism as the locking means in the second embodiment will be described with reference to FIGS. As shown in FIGS. 15A and 15B, the image forming apparatus according to the second embodiment includes a pendulum drive gear 95, a pendulum arm 91 as a locking member, a pendulum gear 93, a pendulum load gear 94, and a pendulum. A rack 96 and a spring 92 are provided.

  The pendulum arm 91 is provided so as to rotate about the rotation axis of the pendulum drive gear 95. The pendulum gear 93 has a rotation shaft on the pendulum arm 91 and is provided so as to mesh with the pendulum drive gear 95. The pendulum load gear 94 is provided so as to mesh with the pendulum gear 93 when the pendulum arm 91 rotates upward in the drawing. The pendulum rack 96 is provided so as to mesh with the pendulum gear 93 when the pendulum arm 91 rotates downward in FIG. Further, the spring 92 is provided so as to bias the pendulum arm 91 in a direction in which the pendulum arm 91 is rotated downward in FIG.

  The pendulum drive gear 95 receives a rotational drive force from the drive unit 400 as a drive unit that is constantly rotating at the same time as the polygon mirror 61 rotates during the image forming operation, and rotates in the direction of the arrow in FIG. The pendulum gear 93 and the pendulum arm 91 rotate upward. At this time, since the tip of the pendulum arm 91 engages with the L-shaped portion of the tip of the fixed arm 81, the fixed arm 81 cannot be removed from the fixing hole 85, and the maintenance door 10 is locked.

  On the other hand, when the drive of the drive unit 400 is stopped, the pendulum arm 91 loses the torque that rotates upward as shown in FIG. 15B, and is pulled downward by the spring 92 and rotates downward. Then, the pendulum arm 91 and the fixed arm 81 are disengaged, and the maintenance door 10 is unlocked.

  In other words, the pendulum arm 91 is locked to limit the opening of the maintenance door 10 by the driving force from the driving means for rotating the polygon mirror 61 when the rotation speed of the polygon mirror 61 becomes higher than a predetermined rotation speed. It moves to the locking position shown in FIG. On the other hand, the pendulum arm 91 does not lock the maintenance door 10 to release the restriction on the opening of the maintenance door 10 when the rotation speed of the polygon mirror 61 becomes a predetermined rotation speed or less, as shown in FIG. Move to the unlocked position. FIGS. 15A and 15B show only a part of the drive unit 400. FIG. Further, the drive unit 400 includes at least one member for image formation such as the paper feed roller 20, the photosensitive drum 32a, the charging roller 32b, the developing roller 33b, the intermediate transfer unit 34, the fixing device 23, or the paper discharge roller 24a. As long as it drives one.

  Next, an opening / closing operation detection mechanism as detection means in the second embodiment will be described with reference to FIGS. 16 (a) to 16 (c). As shown in FIGS. 16A to 16C, the image forming apparatus according to the second embodiment includes a sensor flag 73, an optical sensor 74, a link lever 83, and a groove 86. The sensor flag 73 is provided integrally with a lever 72 provided on the maintenance door 10. The optical sensor 74 includes a cam lever 84 and is provided corresponding to the sensor flag. The link lever 83 is driven by the cam lever 84. One end of the link lever 83 is located in a groove 86 provided in the fixed arm 81.

  As shown in FIG. 16B, when the user grips the lever 72 and slightly rotates, the sensor flag 73 also rotates and is detected by the optical sensor 74. At this time, the link lever 83 is also driven by the cam lever 84, but the fixed arm 81 is not moved by the space provided in the groove 86. In the state where the above-described lock mechanism is operating, the fixed arm 81 is locked and the lever 72 cannot be pulled any more, and the maintenance door 10 is kept locked.

  When the locking mechanism is released, as shown in FIG. 16C, the lever 72 is further rotated, and the cam lever 84 and the link lever 83 are further rotated, whereby the fixed arm 81 is pulled out from the fixing hole 85 and maintenance is performed. The door 10 is unlocked and can be opened.

  With the configuration of the opening / closing operation detection mechanism described above, the release of the lock mechanism when the user tries to open the maintenance door 10 during the image forming operation will be described below. In this embodiment, the basic operation of the control unit 300 is the same as that in the flowchart shown in FIG. 17 except that the lock mechanism release method is different.

  First, the user pulls the lever 72 while the image forming operation is being performed and the maintenance door 10 is locked by the lock mechanism. This user operation is detected by the optical sensor 74. Then, the image forming operation is interrupted, and the deceleration means of the controller (not shown) performs the deceleration operation (stopping operation) of the polygon mirror 61 and the motor 62 in the scanner unit 11. At this time, the drive unit 400 continues to be driven at least to the extent that the lock of the lock mechanism is not released.

  If the controller 300 determines that the rotational speed of the polygon mirror 61 falls to a safe rotational speed that does not cause damage even if the maintenance door 10 is opened or has stopped, the drive unit 400 is stopped and the lock mechanism is locked. Canceled. When the lock mechanism is unlocked, the user pulls the handle 71 to open the maintenance door 10.

  As described above, in the second embodiment, when the rotational speed of the polygon mirror 61 becomes equal to or lower than a predetermined speed at which an excessive load is not applied to the axis of the polygon mirror 61, the lock mechanism is unlocked, and the maintenance door is released. 10 can be opened. As a result, it is possible to reduce wear and deformation due to an inertia load accompanying a change in posture during high-speed rotation of the polygon mirror 61, and to reduce performance deterioration of the scanner unit 11 including the polygon mirror 61.

  Furthermore, in the second embodiment, the performance of the scanner unit 11 can be reduced while reducing the cost by realizing a lock mechanism that uses the drive force of the drive unit 400 that is originally provided without using an actuator such as a dedicated solenoid. Deterioration can be reduced.

Maintenance door 10, scanner unit 11, photosensitive drum 32 a, developing device 33 c, polygon mirror 61, handle part 71, optical sensor 74, image forming apparatus 100

Claims (6)

A door that can be opened and closed with respect to the device body;
An exposure unit comprising a rotary polygon mirror, and exposing the laser beam to the photosensitive member by irradiating the rotary polygon mirror with laser light; and
With
In the image forming apparatus in which the exposure unit opens and closes together with the door,
Lock means capable of restricting opening of the door from a closed state;
Detecting means for detecting an operation for opening the door;
A decelerating means for decelerating the rotational speed of the rotating polygon mirror when the detecting means detects the opening operation while the rotating polygon mirror is rotating;
With
The image forming apparatus, wherein when the rotation speed of the rotary polygon mirror becomes equal to or lower than a predetermined speed by the speed reduction means, the restriction on the opening of the door by the locking means is released, and the door can be opened. . The locking means is
2. A locking member that is movable between a locking position that locks the door and restricts the opening of the door and a non-locking position that does not lock the door. The image forming apparatus described. A driving means for driving a member driven for image formation;
The image forming apparatus according to claim 2, wherein the locking member is in the locking position when the driving unit is driven and is in the non-locking position when the driving unit is stopped. A rotation detecting means for detecting a value related to a rotation speed of the rotary polygon mirror;
The restriction by the lock unit is released when a value related to a rotation speed of the rotary polygon mirror detected by the rotation detection unit becomes a predetermined value or less. The image forming apparatus described. Counting means for counting time since the deceleration means starts to decelerate the rotational speed of the rotary polygon mirror;
Storage means for preliminarily storing a time from when the deceleration means starts to reduce the rotational speed of the rotary polygon mirror until the speed decreases to the predetermined speed or less;
Have
4. The restriction according to claim 1, wherein when the time counted by the counting unit becomes longer than the time stored in the storage unit, the restriction by the locking unit is released. Image forming apparatus. A handle for opening and closing the door is provided,
The image forming apparatus according to claim 1, wherein the detection unit detects an operation for opening the handle when the handle is pulled.

Images