JPH06161280A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the collision of the holding member of a recording medium holding means with a developing means by separating the developing means from the recording medium holding means and then, rotating the recording medium holding means, in an initializing action at the time of applying a power source. CONSTITUTION:A photosensitive drum 21 as a latent image carrying means, an exposing device exposing the photosensitive body of the photosensitive drum 21, developing devices such as developing heads 60 as a developing means developing an electrostatic latent image transferred on a recording paper 71, etc., are disposed on the circumference of a clamping drum 11 as the recording medium holding means. In initialization after the power source of a printer is turned on, setting is attained so that the position of the cam of the developing head 60 is at a home position. In other words, after all of the developing heads 60 are separated from the surface of the clamping drum 11, the clamping drum 11 is rotated/driven. Therefore, a clamping pawl 12 never collides with each developing head 60 and the clamping pawl 12 and the developing heads 60 are not damaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile and a printer, and more specifically, a recording medium held and conveyed by a recording medium holding means arranged facing a latent image carrier. The present invention relates to an image forming apparatus that develops by contacting with.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus of this type, for example, the present applicant has filed a prior application (Japanese Patent Application No. 4-118373).
No.), a recording medium held by a holding member provided in a cylindrical recording medium holding means that is rotationally driven is disposed so that its surface is in contact with the recording medium holding means. It has been proposed that the latent image holding means, which is driven by rotation, transfers the latent image and develops the latent image by a developing means arranged so as to be in close contact with the recording medium.

[0003]

By the way, in this image forming apparatus, it is necessary to bring the developing means into close contact with the recording medium holding means in order to develop the latent image transferred to the recording medium. In addition, it is necessary to rotate the recording medium holding means in order to initialize the apparatus when the power is turned on. According to this configuration, when the developing unit is in close contact with the recording medium holding unit and the holding member of the recording medium holding unit is in the protruding state at the time of initial setting of the apparatus when the power is turned on, the recording medium holding unit is rotated. Therefore, there is a problem that the holding member of the recording medium holding means may collide with the developing means and damage the developing means.

The present invention has been made in view of the above problems, and an object of the present invention is to make a collision between a holding member of a recording medium holding means and a developing means at the time of initial setting of the apparatus when power is turned on. To provide an image forming apparatus that prevents the above.

[0005]

In order to achieve the above-mentioned object, the present invention holds a latent image holding means on which a latent image is formed and a recording medium to which the latent image is transferred, held by a holding member. In the image forming apparatus, the image forming apparatus is provided with a recording medium holding unit that is conveyed while being conveyed, and is arranged to face the latent image holding unit, and a developing unit that is in close contact with the recording medium and develops the latent image. Drive means for moving the recording medium holding means closer to and further away from the recording medium holding means, and for separating the developing means from the recording medium holding means during the initialization operation at power-on, and then holding the recording medium holding means. The control means for controlling the driving means is provided.

[0006]

In the present invention, during the initialization operation when the power is turned on, the recording medium holding means is rotated after the developing means is separated from the recording medium holding means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a color printer which is an image forming apparatus will be described below. FIG. 1 is a front view showing a schematic configuration of a color printer according to this embodiment. An electrostatic recording paper (hereinafter referred to as a recording paper) 71 as a recording medium is wound in a roll shape with the recording surface facing outside, and is mounted as a recording paper roll 70 in the printer body by a paper tube holder (not shown). The clamp drum 11 as a recording medium holding means for mounting the recording paper 71 fed out from the recording paper roll has an aluminum cylinder whose peripheral surface is coated with a conductive rubber, and further has a solvent resistant conductive material. Has a sex overcoat. Clamp drum 11
A flat surface portion 11b is formed on a part of the outer peripheral portion 11a of the paper, and the flat surface portion 11b includes a clamp claw 12 as a recording paper fixing member that holds the leading end of the recording paper 71 and a flat surface when the recording paper 71 is ejected. An eject pin 13 is provided to lift the recording paper 71 on the portion 11b. The clamp claw 12 and the eject pin 13 are integrally attached to respective rotary shafts provided inside the clamp drum 11, and the respective rotary shafts project outward from the end surface of the clamp drum 11. A cam-shaped lever (not shown) is attached to the shaft end of each rotary shaft outside the end surface of the flange portion of the clamp drum 11 in order to open and close the clamp claw 12 and move the eject pin 13 in and out. On the side plate side of the printer, a pin (not shown) that moves in the rotation axis direction of the clamp drum 11 is provided so as to come into contact with the cam-shaped lever as needed.

When mounting the recording paper 71 on the clamp drum 11, first, the clamp drum 11 is temporarily stopped when the flat surface portion 11b reaches the paper feeding position (almost the uppermost position). At this time, the clamp claw 12 is open. The leading edge of the recording paper 71 passes through the guide roller 72 and the cutter 73,
When it is inserted into the nip portion of the paper feed roller 74, the front end thereof is detected by a paper sensor (not shown). Then, the leading end of the recording paper 71 hits the clamp claw 12 to such an extent that it slightly buckles. After that, the clamp drum 11
When is rotated in the direction of the arrow, the cam-shaped lever of the clamp claw 12 is disengaged from the pin on the side plate side of the printer, the clamp claw 12 is closed to grip the recording paper 71, and the clamp drum 11 is further rotated. The recording paper 71 is wound around the clamp drum 11. Clamp drum 11
When the recording paper 71 is rotated to an angle at which the recording paper 71 is wound up to a predetermined length, the recording paper 71 is temporarily stopped, and the cutter 73 is operated to separate the recording paper 71 from the roll unit 70 side.

Around the clamp drum 11, a photosensitive drum 21 as a latent image carrying means, and a photosensitive drum 21.
An exposing device for exposing the photoconductor to the developing device, a developing device as a developing device for developing the electrostatic latent image transferred to the recording paper 71, and the like are provided. The exposure apparatus includes a laser diode (hereinafter referred to as LD), a polygon mirror 31 and the like which are not shown.
And a drive motor thereof, a beam expander (not shown), a lens group 32 such as an f-θ lens and a cylindrical lens, a first mirror 33, a second mirror 34, a synchronization detection mirror 35, a synchronization detection sensor 36, and the like. L
The laser light emitted from D is reflected by the surface of the polygon mirror 31, is focused through the lens group 32, is further reflected by the first mirror 33 and the second mirror 34, and the focused laser light is the photosensitive drum 21. The recording image reaches the surface and the recorded image is written on the photosensitive drum 21 as an electrostatic latent image. The optical path length from the LD to the surface of the photosensitive drum 21 is set so that the diameter of the laser beam focused by the lens group 32 is minimized. In this embodiment, the LD, the polygon mirror 31, the lens group 32, etc. are integrally formed on a base, and the optical path length is adjusted by moving the base in the left-right direction in FIG.

Photosensitive drum 21 on which an electrostatic latent image is formed
Is pressed by the recording paper 71 wound around the clamp drum 11, and is driven to rotate while a constant latent image transfer bias voltage is applied between both drums. As a result, the recording paper 7
The electrostatic latent image formed on the photoconductor is transferred onto the surface of the photosensitive member 1, and a mirror image latent image having a mirror image relationship with the electrostatic latent image is formed. The electrostatic latent image transferred to the recording paper 71 is visualized by the slit developing head (hereinafter referred to as a developing head) 60 of the developing device with the developer 10 which is a developer.

As shown in FIG. 2, the developing device comprises a developing head 60, a suction pump 61, an electromagnetic valve 62, a developing tank 64, a developing solution supply pipe 65, a developing solution recovery pipe 66 and the like. The developing head 60 includes yellow (y), magenta (m), cyan (c), black (b)
k), there are five special colors (sp), and they are formed in a shape so as to come into close contact with the surface of the clamp drum 11, and are radially arranged with a distance of about 2 mm from the clamp drum 11 when not developing. . Further, at least one developing groove 60a extending in the axial direction of the clamp drum 11 is engraved on the surface of the developing head 60 facing the clamp drum 11.

Further, as shown in FIG. 3, the developing head 60 is provided with cams 50 of the same shape at both ends in the longitudinal direction, and each cam shaft 50a is synchronized by a developing device vertical movement motor and a chain (not shown). It is driven to rotate. The cam 50 has such a shape that the developing heads 60 can be moved up and down separately for each 1/10 rotation. Also,
The cam follower 52 is fixed to the fixed shaft 53 by the developing head 60.
The cam follower 52 is attached at one end thereof so as to be rotatable around a rotation shaft 54 on the printer body side. And the cam follower 52
The roller 55 attached to the other end of the developing device is in contact with the outer peripheral surface of the cam 50, and is between the pin (not shown) provided on the printer body side and the pin 60b at the lower end of the developing head 60. By the spring 51 stretched around the developing head 6,
0, the cam follower 52 is pressed against the cam 50, so that the developing head 6 is rotated according to the rotation of the cam 50.
0 moves up and down. In FIG. 3, the reference numerals of the respective members provided corresponding to the colors of yellow, magenta, cyan, black, and special colors are y, m, c, bk, and s, respectively.
The subscript of p is attached.

At the time of development by the developing device, as shown in FIG. 1, the clamp drum 11 rotates in the direction of the arrow, and the leading end of the recording paper 71 on which the electrostatic latent image is formed is the developing head 60.
When passing through a position opposite to, the cam shaft 50a is rotated by 1/10 rotation by a drive motor (not shown), and the developing head 60 is clamped to the developing head 60 via the cam 50 fixedly mounted on the cam shaft 50a. Press on the 11th side and press the recording paper 7
Adhere to 1.

Then, the developing head 6 is moved by the recording paper 71.
With the development groove 60a of 0 being substantially sealed, the suction pump 6
1 makes the sealed developing groove 60a negative pressure,
The developer 10 is a developer tank 64, a developer supply pipe 65,
Development head 60, developer recovery pipe 66, suction pump 6
By circulating between 1 and the developing tank 64, the developing solution 10 is supplied to the developing groove 60a of the developing head 60, and the electrostatic latent image transferred onto the recording paper 71 is developed.

Then, after the rear end of the image forming portion of the recording paper 71 has passed the position facing the developing head 60, the electromagnetic valve 62
The supply of the developing solution 10 is stopped by the
A squeeze of 0 is performed. After this squeeze ends, the suction pump 61 is stopped and the cam shaft 50a moves to 1/1
The development head 60 rotates 0 revolutions, and the developing head 60 moves to the clamp drum 1.
Separated from 1. At this time, if the squeeze is not complete, the developing solution 10 remains on the rear portion of the recording paper 71, so the blotter roller 41 completely removes the remaining solution. Further, the recording paper 71 and the blotter roller 41 are dried by the fan 42.

After the above-described development, the residual potential remains on the recording paper 71, and in order to prevent color mixture in the next step, the static elimination scorotron 43 removes the residual potential to remove the residual potential. Then, when the development by all the developing heads 60 is completed, the clamp drum 11 is driven to the paper discharge position, the clamp claw 12 is opened, the eject pin 13 is projected, and the leading end of the recording paper 71 is clamped to the clamp drum 1.
1 and the recording paper 71 is ejected from the discharge table 77.
Is discharged to.

FIG. 4 is a block diagram of the control system of the color printer. As shown in FIG. 4, the control system of the color printer includes a printer control unit 1, a printer input unit 2, a printer output unit 3, an operation unit 4, and a writing unit 5.

FIG. 5 is a flowchart of control of the color printer. FIG. 6 is a detailed flowchart of the control of the initial setting (step 2) in FIG. When the power of the printer is turned on (step 1), the developing head 60,
The clamp drum 11 and the electrostatic latent image writing unit 5 are initialized (step 2). The developing head 6
In the initialization of 0, the developing head home position sensor of the printer input unit 2 in FIG. 4 detects the home position of the cam 50 of the developing head 60. here,
The home position means a state in which all the developing heads 60 are lowered and the developing heads 60 are moved up next.
Is a state in which the developing head 60 of the first color used in the image forming process is set.

When the printer is powered on as described above, the output of the developing head home position sensor is checked (step 201) as shown in FIG.
If the current position of is the home position, the drum drive motor is turned on to initialize the clamp drum 11 described later (step 205). On the other hand, when the current position of the cam 50 is not the home position, the developing device vertical movement motor driving the cam shaft 50a is turned on (step 202), and the cam 50 is operated. And
While the cam 50 is operating, the output of the developing head home position sensor is continuously checked (step 20).
3) If the cam 50 is at the home position, the developing device vertical movement motor is turned off (step 20).
4) After that, the drum drive motor is turned on to initialize the clamp drum 11, which will be described later, as in step 201.
N (step 205).

After the initialization of the developing head 60 is completed, the clamp drum 11 is initialized. The drum home position sensor of the printer input unit 2 in FIG. 4 detects the detection unit on the clamp drum 11. The drum drive motor is turned on (step 205), and the clamp drum 11 is rotationally driven until the drum home position sensor detects the detection portion on the clamp drum 11,
Confirm that the rotation position (angle) of the clamp drum 11 can be recognized. Then, the motor for the polygon mirror 31 is turned on to stabilize the rotation of the polygon mirror 31,
After that, the power source of the LD drive system is turned on.

Next, the clamp drum 11 continues to rotate,
At the specified position, turn on the paper feed solenoid and clamp the claw 1.
While opening 2, the clamp unit is moved to a position directly above, the clamp drum 11 is stopped, and the printer is put in the paper feed standby state (step 3). Next, in the paper feed standby state, the recording paper 71 is set on the clamp portion of the clamp drum 11, and the user presses a predetermined switch of the operation portion 4 to wind the recording paper 71 on the clamp drum 11. Be started. When the recording paper 71 is roll paper, a cutting operation is performed and the paper feeding operation is completed (step 4). Next, the clamp drum 11 continues to rotate, and in the state where the recording paper 71 is wound, it is stopped at the READY position waiting for the start of the electrostatic latent image writing operation (step 5).

Next, the user depresses a predetermined switch of the operation unit 4 to write and develop the electrostatic latent image (step 6). When the user presses the switch, the clamp drum 11 starts to rotate, and the charge removing LED 24, the power supply for the charging charger 23, etc. arranged around the photosensitive drum 21 are turned on. The clamp drum 11 continues to rotate, the detection unit on the clamp drum 11 is detected by the write start position detection sensor, and the detected value is input to the printer control unit 1. At this time, a write start signal is output from the printer control unit 1 to the writing unit 5, and formation of an electrostatic latent image on the photoconductor drum 21 is started. Further, the electrostatic transfer power supply used for transferring the electrostatic latent image from the photosensitive drum 21 to the recording paper 71 on the clamp drum 11 is turned on. After the formation and electrostatic transfer of the electrostatic latent image for one sheet of the recording paper 71 are completed, the power supply for the charging charger 23 and the electrostatic transfer power supply are turned off, and the electrostatic latent image forming operation is completed.

The leading end of the electrostatic latent image on the recording paper 71 is formed just before the photosensitive drum 21 at the time when the electrostatic latent image forming operation is completed, and the clamp drum 21 continues to rotate, The clamp portion of the clamp drum 21 is sent to the position of the developing head 60. 5 developing heads 6
When the developing head to be used out of 0 (hereinafter referred to as an active developing head) reaches the developing head raising position between the clamp portion on the recording paper 71 and the leading end portion of the electrostatic latent image, the drive motor for the cam shaft 50a. Is turned on to raise the active developing head. At this time, the clamp drum 11
There is a method of temporarily stopping the process and waiting for the active developing head to rise, and a method of raising the active developing head without stopping the clamp drum 11. This method
It can be selected depending on whether or not the distance between the clamp portion on the recording paper 71 and the tip of the electrostatic latent image can be sufficiently set. For example, when the distance is sufficient, the clamp drum 11 is not stopped and is activated. There is no problem even if the developing head is raised.

When the active developing head is completely raised, the developing device vertical movement motor for rotating the cam shaft 50a is stopped, the clamp drum 11 is rotated, and the pump 61 and the solenoid valve corresponding to the raised active developing head. 6
Turn on 2. As a result, the developing solution 10 begins to circulate inside the active developing head, and development is started. When the development is started, the blower fan 42 is turned on. As the development is continued, the clamp part of the recording paper 71 reaches the position of the static elimination scorotron 43, and at that time, the power source of the static elimination scorotron 43 is turned on.
To do.

When the development is completed, the electromagnetic valve 62 is turned off to collect the developing solution 10, and when the collection is completed, the pump 61 is collected.
And the active developing head is lowered. When the clamp portion of the recording paper 71 reaches the position of the static elimination scorotron 43 again, the recording paper static elimination power source and the blower fan 42 are turned off.

After the writing and development of the electrostatic latent image for the first color is completed, the clamp drum 11 continues to rotate as it is, and the writing and development of the electrostatic latent image corresponding to the next color are started. When the writing and development of the electrostatic latent image are completed, the recording paper discharging operation is started (step 7).

In the recording paper discharge operation, the discharge solenoid is turned on at a position where the clamp portion has passed just above, the clamp claw 12 is opened at the discharge position, and the clamp drum 11 remains as it is.
Is continued by continuing the rotation (step 8). After that, the clamp drum 11 continues to rotate,
It stops at the paper feeding position as after the initial setting.

In the above printer control, the rotation speed of the clamp drum 11 at the time of writing and developing the electrostatic latent image is restricted by the process conditions, but at other times, it can be rotated at an arbitrary speed. Therefore, in order to shorten the printing operation time, it is effective to rotate the clamp drum 11 at a high speed except when writing the electrostatic latent image and developing the electrostatic latent image. Further, when the rotation speeds of the clamp drum 11 at the time of writing the electrostatic latent image and at the time of developing can be made equal to each other, the writing and developing of the electrostatic latent image can be performed at the same time to shorten the printing operation time. it can. In that case, the clamp drum 11 is not stopped when the active developing head is raised, and the electrostatic latent image writing operation and the developing operation are performed in the same circulation.

As described above, according to the present embodiment, by setting the position of the cam 50 of the developing head 60 to the home position at the time of initial setting after the power of the printer is turned on, each developing head is set. Clamp drum 11 for all 60
Since the clamp drum 11 is rotationally driven after being separated from the surface, the clamp claw 12 does not collide with each developing head 60 and the clamp claw 12 and each developing head 60 are not damaged.

[0030]

According to the first aspect of the present invention, during the initialization operation when the power is turned on, the recording medium holding means is rotated after the developing means is separated from the recording medium holding means. There is an effect that the collision between the holding member of the holding unit and the developing unit can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a color printer according to an embodiment.

FIG. 2 is a piping system diagram of a developing solution in the developing device of the color printer.

FIG. 3 is a schematic configuration diagram of a lifting mechanism for a developing head of the developing device.

FIG. 4 is a block diagram of a control system of the color printer.

FIG. 5 is a flowchart of control of the color printer.

FIG. 6 is a detailed flowchart regarding initial setting in FIG.

[Explanation of symbols]

 1 Printer Control Section 2 Printer Input Section 3 Printer Output Section 4 Operation Section 5 Writing Section 10 Developer 11 Clamp Drum 11a Outer Part 11b Flat Surface 12 Clamp Claw 13 Eject Pin 21 Photosensitive Drum 23 Charger Charger 24 Static Elimination LED 31 Polygon Mirror 32 lens group 33 first mirror 34 second mirror 35 synchronization detection mirror 36 synchronization detection sensor 41 blotter roller 42 blower fan 43 static eliminator scorotron 50 cam 50a cam shaft 51 spring 52 cam follower 53 cam follower fixed shaft 54 cam follower rotation shaft 55 roller 60 development Head 60a Developing groove 61 Suction pump 62 Electromagnetic valve 64 Developing tank 65 Developing solution supply pipe 66 Developing solution recovery pipe 70 Recording paper roll 71 Electrostatic recording paper 72 Guide roller 73 Cutter 74 Paper feed roller 77 Paper ejection table

Claims (1)

[Claims] 1. A latent image holding means for forming a latent image on the surface,
The recording medium on which the latent image is transferred is conveyed while being held by a holding member, and the recording medium holding means arranged facing the latent image carrying means and the recording medium are brought into close contact with each other to develop the latent image. In an image forming apparatus provided with a developing means, a driving means for moving the developing means toward and away from the recording medium holding means, and a developing means for performing the initializing operation when the power is turned on. An image forming apparatus, comprising: a control unit that controls the recording medium holding unit to drive the recording medium holding unit after the recording medium holding unit is separated from the recording medium holding unit.