JPH11161118A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device by which a destaticizing means and a density detecting means are prevented from being soiled and also whose the cleaning property is improved by making them easy to be cleaned. SOLUTION: A duct 49 provided with a fan to take in outside air to an opening and closing cover 42a, a pre-exposure unit 51 and an optical sensor 50 are provided in the vicinity of the top end of the duct so that soiling caused by a toner or the like is prevented by sending in the air through the duct 49, the operating and closing cover 42a is attached at a box unit 40 by making a supporting member 46 a supporting point for turning it, and a locking mechanism is released and is opened to an open position shown by a double dotted chain line so that the preexposure unit 51 and the optical sensor 50 come out to the outside of the box unit, 40 and the cleaning is easily executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a color copying machine or a color printer of, for example, an electrophotographic type or an electrostatic recording type.

[0002]

2. Description of the Related Art Conventionally, as this type of image forming apparatus,
For example, there are a color copying machine and a color printer of an electrophotographic system or an electrostatic recording system.

A color laser beam printer will be described. There is an image carrying unit including a drum unit in which a photosensitive drum as an image carrying body is held in a holder integrated with a cleaner container.

[0004] The image forming apparatus further includes a pre-exposure unit serving as a charge removing means for stabilizing the surface potential of the photosensitive drum, an optical sensor serving as a density detecting means for stabilizing the toner density, and a charging means comprising a primary charging means.

There is also provided an exposing means constituted by a scanner unit for guiding image light emitted by a laser diode in response to an image signal to an image carrier via a polygon mirror, an image forming lens and a reflection mirror.

There is provided a fixed developing device having a sleeve and a blade, and a developing means comprising a plurality of rotary developing devices of a plurality of colors having a coating roller, a sleeve and a blade, which are attached to a developing rotary which rotates about a rotation axis. .

Further, there is provided a cleaning means having a cleaner container with a cleaner blade for cleaning residual toner on the photosensitive drum.

The image forming apparatus includes a cassette supply unit for feeding the sheets in the cassette to the image forming unit while guiding the sheets in the supply guide by rollers, and a supply unit having a supply device for supplying the sheets from outside the apparatus.

A transfer unit including a transfer roller for transferring a multiple toner image carried on an intermediate transfer member to a sheet, which receives multiple transfer of a toner image visualized by a developing device of each color, and a heater; And a fixing unit for fixing the toner image to the sheet by passing the sheet carrying the toner image through a nip portion between a fixing roller having a heater and a pressure roller having a heater.

The sheet that has passed through the fixing section is discharged onto a discharge tray by a discharge roller.

[0011]

However, in such a conventional technique, as the number of inserted sheets increases, toner or paper dust scattered in the apparatus adheres to the optical sensor or the LED surface of the pre-exposure unit. , Optical sensors and LEDs
When the surface is soiled, the space between the intermediate transfer member and each sensor is small due to the narrow space, and cleaning is difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to prevent the static elimination means and the density detecting means from being stained, and to further reduce the static elimination means and the density detecting means. An object of the present invention is to provide an image forming apparatus that is easy to clean and has improved cleanability.

[0013]

According to the present invention, there is provided a charge removing means for removing charge remaining on an image carrier, and a density detecting means for detecting an image density on an intermediate transfer member. And an air blowing means for sending air to at least one of the static elimination means and the density detecting means.

Therefore, it is possible to prevent dust such as toner from adhering to at least one of the static elimination means and the density detection means by blowing air.

The charge removing means for removing the remaining charge on the image carrier is provided so as to be movable from the use position where the charge is removed to a position away from the image carrier.

Thus, the cleaning unit can be easily moved by moving the static elimination means from the use position where the space is narrow.

The charge removing means is provided on a door that opens the inside of the apparatus. When the door is opened, the charge removing means is moved to a position away from the image carrier, and when the door is closed, the charge removing means is returned to the use position. Is preferably moved.

Thus, the static elimination means can be moved by opening and closing the door, and when the door is opened, it is exposed to the outside and cleaning becomes easy.

The density detecting means for detecting the image density on the intermediate transfer member is movably provided from a use position where the detection is performed to a position away from the intermediate transfer member.

Thus, the concentration detecting means can be moved from the use position where the space is narrow, and the cleaning can be easily performed.

When the density detecting means is provided on a door that opens the inside of the apparatus, when the door is opened, the density detecting means is moved to a position away from the intermediate transfer member, and when the door is closed,
It is preferable to move the density detecting means to the use position.

Thus, the density detecting means can be moved by opening and closing the door, and when the door is opened, it is exposed to the outside and cleaning can be easily performed.

It is preferable that a blower for blowing air into at least one of the static eliminator and the concentration detector is provided.

[0024] Thus, it is possible to prevent dust from adhering to at least one of them.

The static eliminator irradiates light emitted by power supply to the image bearing member to eliminate static electricity, and it is preferable that the blowing of the blower is synchronized with the power supply of the static eliminator.

Thus, simplification of power supply wiring and the like can be achieved.

[0027] Preferably, the blowing means is provided on the door.

Thus, the sending means can be moved by opening and closing the door.

It is preferable that a sheet feeding device for feeding a sheet is provided on the door.

Thus, the sheet feeding device can be moved by opening and closing the door.

[0031]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(Embodiment) FIG. 1 is a longitudinal sectional view of a color image forming apparatus showing an embodiment of the image forming apparatus according to the present invention.

The color image forming apparatus according to the present embodiment has an image forming unit including an image carrier that rotates at a constant speed, a fixed black developing device, and three rotatable color developing devices. An intermediate transfer member for holding the developed and multi-transferred color image and further transferring the color image to the sheet 2 fed from the feeding unit, and transporting the color image-transferred sheet 2 to the fixing unit 25; The color image is fixed on the sheet 2 and discharged to a discharge section 37 on the upper surface of the apparatus by a discharge roller.

The rotatable color developing device and the fixed black developing device are configured to be individually detachable from the printer main body.

The configuration of the color image forming apparatus according to the present embodiment includes an image carrier unit, a charging unit, an exposing unit, a developing unit, a cleaning unit, a cassette sheet feeding unit, a multi sheet feeding unit, an intermediate transfer body, a transfer unit, This will be described in detail sequentially for the fixing unit and the like.

[Image Carrier Unit] The drum unit 13 constituting the image carrier unit is integrally formed with a photosensitive drum 15 as an image carrier and a cleaner container 14 of a cleaning device which also serves as a holder for the photosensitive drum 15.
The drum unit 13 is detachably supported by the printer main body, and is configured so that the unit can be easily replaced according to the life of the photosensitive drum 15.

The photosensitive drum 15 according to the present embodiment is
An organic photoconductor layer is coated on the outside of an aluminum cylinder having a diameter of about 60 mm, and is rotatably supported by a cleaner container 14 of a cleaning device also serving as a holder for the photosensitive drum 15.

On the circumference of the photosensitive drum 15, a cleaner blade 16 and a primary charging means 17 are arranged.

A driving motor (not shown) is provided, and the driving force of the driving motor is transmitted to the photosensitive drum 15 so that the photosensitive drum 15 rotates counterclockwise in the figure in accordance with the image forming operation. I have to.

[Charging means] Charger 1 constituting charging means
Numeral 7 uses a contact charging method, in which a conductive roller is brought into contact with the photosensitive drum 15 and a voltage is applied to the conductive roller to uniformly charge the surface of the photosensitive drum 15. .

[Exposure Means] Exposure to the photosensitive drum 15
This is performed from the scanner unit 30 constituting the exposure unit.

When an image signal is given to a laser diode (not shown), the laser diode irradiates the polygon mirror 31 with image light corresponding to the image signal.

The polygon mirror 31 is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror 31 selectively exposes the surface of the photosensitive drum 15 rotating at a constant speed via the imaging lens 32 and the reflection mirror 33. As a result, an electrostatic latent image is formed on the photosensitive drum.

[Developing Means] The developing means includes three rotary developing devices 20Y, 20M, 20M, 20M, and 20M capable of developing the respective colors of yellow, magenta, and cyan in order to visualize the electrostatic latent image.
20C and one black developing unit 21B capable of developing black color.

The black developing unit 21B is a fixed developing unit, and a sleeve 21BS is arranged at a position facing the photosensitive drum 15 at a minute interval (about 300 μm) with respect to the photosensitive drum 15, and a visible image of black toner is formed on the photosensitive drum 15. To form

The black developing device 21B feeds toner toward the sleeve 21BS by a toner feeding mechanism in the container, and applies the toner to the outer periphery of the sleeve 21BS rotating clockwise in the figure by the application blade 21BB pressed against the outer periphery of the sleeve 21BS. A thin layer is applied and a charge is applied to the toner (frictional charging).

Further, by applying a developing bias to the sleeve 21BS, toner development is performed corresponding to the electrostatic latent image on the photosensitive drum 15.

On the other hand, three rotary developing devices 20Y, 20M,
20C is detachably held by a developing rotary 23 that rotates about a shaft 22. At the time of image formation, each rotary developing device is pivotally moved about the shaft 22 with the rotary developing device being held by the developing rotary 23. Is stopped at a position facing the photosensitive drum 15.

Further, after the developing sleeve is positioned so as to face the photosensitive drum 15 with a small interval (about 300 μm), a visible image is formed corresponding to the electrostatic latent image on the photosensitive drum 15.

When forming a color image, one of the intermediate transfer members 9
The developing rotary 23 rotates with each rotation, and a yellow developing device 20Y, a magenta developing device 20M, a cyan developing device 20C,
Next, a developing process is performed in the order of the black developing device 20B.

FIG. 1 shows a state in which the yellow rotary developing device 20Y is positioned at a position facing the photosensitive drum 15 and is stationary.

The rotary developing device 20Y feeds the toner in the container toward the coating roller 20YR by a feeding mechanism, and rotates the coating roller 20Y rotating clockwise in the figure.
R and the blade 2 pressed against the outer periphery of the sleeve 20YS
Sleeve 20Y that rotates clockwise in the figure by 0YB
A thin layer of toner is applied to the outer periphery of S, and a charge is applied to the toner (frictional charging).

By applying a developing bias to the sleeve 20YS facing the photosensitive drum 15 on which the latent image is formed, toner development is performed on the photosensitive drum 15 in accordance with the latent image. Magenta developing device 20M, cyan developing device 20
For C, toner development is performed by the same mechanism as described above.

Each of the rotary developing devices 20Y, 20M, 20C
Each of the sleeves is connected to a high-voltage power supply for each color development and a driving device provided in the printer main body when each of the developing units is rotated to the developing position, and a voltage is sequentially and selectively applied for each color development. And the driving force is connected.

[Cleaning Unit] The cleaning unit is configured to transfer the toner visualized on the photosensitive drum 15 by the developing unit to the intermediate transfer body 9 and then transfer the toner to the photosensitive drum 15.
This is for cleaning the remaining toner, and the cleaned waste toner (toner to be discarded) is stored in the cleaner container 14.

The amount of waste toner stored in the cleaner container 14 is shorter than the life of the photosensitive drum 15.
Therefore, the cleaner container 14 is simultaneously replaced when the life of the photosensitive drum 15 is replaced.

[Cassette Supply Section] The cassette supply section feeds the sheets 2 to the image forming section, and includes a cassette 1 containing a plurality of sheets 2, a feed roller 3, a feed roller 4, and a double feed. It mainly comprises a retard roller 5, a supply guide 6, and a registration roller 8 for prevention.

At the time of image formation, the feed roller 3 is driven and rotated in accordance with the image forming operation, separates and feeds the sheets 2 in the cassette 1 one by one, is guided by the supply guide 6, and passes through the transport roller 7. To the registration roller 8.

During the image forming operation, the registration roller 8 performs a predetermined sequence of a non-rotating operation for keeping the sheet 2 in a standby state and a rotating operation for conveying the sheet 2 toward the intermediate transfer member, and the next step is the transfer process. The image at the time of the process and the sheet 2 are aligned.

[Multi Supply Unit] The supply unit has a multi supply unit in addition to the cassette supply unit described above. The multi-supply unit 42 feeds the sheet 2 to the image forming unit, and includes a tray 45 on which a plurality of sheets 2 are stacked and a feeding roller 4.
3. These members constituting the multi-supply unit are attached to an opening / closing cover 42a mainly constituted by a separation pad 44 for preventing double feeding and serving as a door capable of opening and closing the opening 40a formed on the front side of the housing 40. Have been.

The opening / closing cover 42a is provided with a duct 49 provided with a fan (not shown) for taking in outside air, and a front portion serving as a static eliminator near the tip of the duct for eliminating the residual charge of the image carrier. An exposure unit 51 and an optical sensor 50 as density detecting means for detecting the image forming density on the intermediate transfer member are provided.

As a result, the pre-exposure unit 51 and the optical sensor 50 at the use position are prevented from being contaminated by toner or the like due to the supply of air from the duct 49. 52 is an air filter for preventing intrusion of dust and the like from outside the apparatus.

The pre-exposure unit 51 and the optical sensor 5
In the use position 0, the space was too small to be cleaned. However, as shown in FIG. 2, the opening / closing cover 42a rotates the support member 46 having a rotation axis in the same direction as the rotation axis of the intermediate transfer body 9. When the lock mechanism (not shown) is released as a fulcrum of movement and the lock mechanism (not shown) is released and opened to the open position shown by the two-dot chain line in FIG. 1, the pre-exposure unit 51 and the optical sensor 50 are moved, So that cleaning can be easily performed.

At the time of image formation, the feed roller 43 is driven and rotated in accordance with the image forming operation, separates and feeds the sheets 2 on the tray 45 one by one, and is guided by the guide plate 41 to reach the registration roller 8. During the image forming operation, the registration roller 8 performs a non-rotating operation of keeping the sheet 2 stationary and standby and a rotating operation of transporting the sheet 2 toward the intermediate transfer body in a predetermined sequence. And the sheet 2 are aligned.

In addition, the input or cutoff of the fan provided in the blower means is configured to synchronize the turning on or off of the LED of the pre-exposure unit and the electric timing with the electric timing, so that the distribution line can be simplified. Good.

[Intermediate Transfer Body] In the intermediate transfer body 9, during the color image forming operation, the toner image on the photosensitive drum 15 visualized by each developing device is printed four times (each image of four colors of Y, M, C, and B). ), The sheet 2 rotates clockwise in synchronization with the peripheral speed of the photosensitive drum 15, and the intermediate transfer body 9 having received the multiple transfer transfers the sheet 2 by the transfer roller 10 to which a voltage is applied. The toner images of the respective colors on the intermediate transfer body are simultaneously and multiplex-transferred onto the sheet 2 by sandwiching and conveying.

The intermediate transfer member 9 according to the present embodiment has a structure in which the outer circumference of an aluminum cylinder 12 having a diameter of 180 mm is covered with an elastic layer 11 such as a medium resistance sponge or medium resistance rubber.

The intermediate transfer member 9 is rotatably supported by intermediate transfer member holding members (not shown) on both sides, and is rotated by being driven by an integrally fixed gear (not shown).

[Transfer Section] The transfer section is constituted by a swingable transfer roller 10 and the like. Transfer roller 10 of the present embodiment
Is formed by winding a metal shaft with a medium-resistance foam elastic body, and is movable in a vertical direction in the figure by a drive mechanism (not shown).

While the four-color toner image is being formed on the intermediate transfer member 9, that is, while the intermediate transfer member 9 is rotated a plurality of times, the transfer roller 10 is not disturbed as shown by the solid line in FIG. Is located below and is separated from the intermediate transfer member 9.

After the formation of the four color toner images on the intermediate transfer member 9, the transfer roller 10 is moved to a position corresponding to the timing of transferring the color image onto the sheet 2 by a cam member (not shown). It is pressed against the intermediate transfer member 9 at a predetermined pressure via the sheet 2, that is, the sheet 2.

At this time, a bias is simultaneously applied to the transfer roller 10, and the toner image on the intermediate transfer body 9 is transferred to the sheet 2.

Here, since the intermediate transfer member 9 and the transfer roller 10 are respectively driven to rotate, the sheet 2 sandwiched between them is conveyed at a predetermined speed to the left in the figure at the same time as the transfer process is performed. Then, it is sent to the next step, a fixing device.

[Fixing Section] The fixing section 25 fixes the toner image formed on the sheet 2 via the intermediate transfer member 9 to the toner image formed by the rotary developing devices 20Y, 20M, 20C and the fixed developing device 21. As shown in FIG. 1, a fixing roller 26 for applying heat to the sheet 2 and a pressing roller 27 for pressing the sheet 2 against the fixing roller 26 are provided. Each roller is a hollow roller. With the heaters 28 and 29 inside, the sheet is rotated and driven at the same time.
Is transported.

That is, the sheet 2 holding the toner image is conveyed by the fixing roller 26 and the pressing roller 27, and the toner is fixed on the sheet 2 by applying heat and pressure.

Here, particularly, the parts deeply related to the present invention will be described again.

[Pre-exposure Unit] The pre-exposure unit serving as the charge removing means is mainly composed of LEDs, and is used to turn on and off the LEDs.
The fan provided in the duct is rotated in synchronization with turning off the light. Then, by irradiating the photosensitive drum with light emitted from the LED, the remaining charge on the surface of the photosensitive drum is eliminated, and the potential is stabilized to stabilize the image.

[Optical Sensor] The optical sensor 50 as a density detecting means is composed of an LED and a photodiode.
The light emitted in D is reflected and received by the photodiode to detect the density.

The optimum developing bias is determined from the detected density, and the fluctuation of the image density due to the deterioration of the photosensitive drum, the change of the environment, the deterioration of the toner and the like is suppressed.

In this configuration, in the multi-supply unit, the optical sensor unit 50 and the pre-exposure unit 51 are arranged near the end of the duct 49, and the adhesion of dirt due to toner or the like is prevented by the air path shown by the broken line in FIG.

At this time, the rotation speed (speed) of the fan of the blowing means is relatively low, and it is sufficient that a slight air path is ensured toward the inside of the apparatus. This is also desirable from the viewpoint of noise. .

When the sensor or the like becomes dirty, the open / close cover 42a of the multi-supply unit 42 is rotated to the open position indicated by the two-dot chain line in FIG.

The optical sensor unit 50 and the pre-exposure unit 51 on the openable cover 42a shown in FIG. 2 can be easily cleaned.

[0084]

According to the present invention, since air blowing means for feeding air to at least one of the charge removing means and the density detecting means is provided, it is possible to prevent dust such as toner from adhering.

The static elimination means for eliminating the residual charge on the image carrier is provided so as to be movable from a use position where static elimination is performed to a position away from the image carrier, so that the space is narrow and cleaning of the static elimination means is difficult. By moving the static eliminator from the use position to a position away from the image carrier, the space can be expanded and cleaning can be easily performed.

A door for opening the inside of the apparatus is provided with a static elimination means,
When the door is opened, the static eliminator is moved to a position away from the image carrier, and when the door is closed, the static eliminator is moved to the use position. Becomes possible.

The density detecting means for detecting the image density on the intermediate transfer member is provided so as to be movable from a use position for detection to a position away from the intermediate transfer member, so that the space is narrow and it is difficult to clean the density detecting means. By moving the density detecting means from the use position to a position away from the intermediate transfer member, the space can be expanded and cleaning can be easily performed.

When the door for opening the inside of the apparatus is provided with density detecting means, when the door is opened, the density detecting means is moved to a position away from the intermediate transfer member, and when the door is closed, the density detecting means is moved to the use position. For example, the density detecting means can be moved by opening and closing the door, and when the door is opened, the density detecting means is exposed to the outside, so that cleaning can be easily performed.

The provision of the air blowing means for blowing air into at least one of the static elimination means and the density detection means can prevent dust from adhering.

The static eliminator irradiates light emitted by power supply to the image carrier to eliminate static electricity. If the blowing of the blower synchronizes with the power supply of the static eliminator, the power supply wiring and the like can be simplified. Can be achieved.

Since the blower is provided on the door, the blower can be exposed to the outside when the door is opened, so that the blower can be easily cleaned.

Since the sheet feeding device for feeding the sheet is provided on the door, the sheet feeding device can be exposed to the outside when the door is opened, so that the sheet feeding means can be easily cleaned.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an image forming apparatus according to an embodiment.

FIG. 2 is a schematic sectional view showing a state where a door of the image forming apparatus according to the embodiment is opened.

[Explanation of symbols]

 2 sheet 9 intermediate transfer member 15 photosensitive drum 40 case 40a opening 42 multi-supply unit 42a opening / closing cover 43 feed roller 44 separation pad 45 tray 46 support member 49 duct 50 optical sensor 51 pre-exposure unit 52 air filter

Claims (9)

[Claims] 1. An image forming apparatus comprising: a charge removing unit for removing charge remaining on an image carrier; and a density detecting unit for detecting an image density on an intermediate transfer member. An image forming apparatus, comprising: a blower for sending air to at least one of the detectors. 2. An image forming apparatus according to claim 1, wherein said charge removing means for removing charge remaining on said image bearing member is movably provided from a use position where said charge removal is performed to a position apart from said image bearing member. 3. The apparatus according to claim 2, further comprising: a door for opening the inside of the apparatus, wherein the charge removing means is provided. When the door is opened, the charge removing means is moved to a position away from the image carrier, and when the door is closed, the charge removing means is moved to the use position. The image forming apparatus according to claim 2, wherein the charge removing unit is moved. 4. An image forming apparatus according to claim 1, wherein the density detecting means for detecting the image density on the intermediate transfer member is movably provided from a use position where the detection is performed to a position away from the intermediate transfer member. 5. The apparatus according to claim 1, wherein the density detecting means is provided on a door that opens the inside of the apparatus. When the door is opened, the density detecting means is moved to a position away from the intermediate transfer body, and when the door is closed, the use position is changed. The image forming apparatus according to claim 4, wherein the density detecting unit is moved first. 6. The image forming apparatus according to claim 2, further comprising a blower that blows air to at least one of the static eliminator and the density detector. 7. The static eliminator irradiates light emitted by power supply to the image carrier to perform static elimination, wherein the blowing of the blower synchronizes with the power supply of the static eliminator. The image forming apparatus according to claim 6. 8. The image forming apparatus according to claim 6, wherein the blower is provided on the door. 9. The image forming apparatus according to claim 6, wherein a sheet feeding device for feeding a sheet is provided on the door.