JPH03287282A - Separating charger controller - Google Patents

Abstract

PURPOSE:To keep a voltage impressed on a separating charger to an irreducible minimum and to effectively utilize a both-face printing function by making the voltage impressed on a separating charger at the time of separating the 1st side of a recording paper different from at the time of separating the 2nd side of the recording paper and controlling it. CONSTITUTION:In an ordinary state (also when a paper does not pass through), only the control line (1) is true, the voltage set at an ordinary level is impressed from a high voltage power-supply device 29 by a controller 28 for controlling the impressed voltage on the separating charger. When the paper is fed from a position for feeding the paper again, only the control line (2) is made true by a CPU, the voltage higher than the ordinary one is impressed on the separating charger 24 by the controller 28, and corona discharging is performed by the charger with the impressed voltage enough for separating a recording paper at the time of printing on the 2nd side, and then, the recording paper is rapidly separated. And when the action of printing on the 2nd side is finished and the recording paper is ejected, the voltage impressed on the separating charger is returned in the ordinary state by the CPU. Thus, even in the case of the recording paper having a printed 1st side, the recording paper can be separated without the occurrence of jamming such as winding around a photosensitive body, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a separate charger control device for an image forming apparatus capable of double-sided printing.

(Prior Art) FIG. 4 shows a schematic configuration diagram of a laser printer as an example of an image forming apparatus having a double-sided printing function in the main conveyance type of recording paper. Laser printer body 1 as shown in the figure
0 and a double-sided machine 17 disposed on the side and top of the main body, and the entire operation is controlled by a controller 1 and a roller 26.

To explain the operation outline of this laser printer, recording paper 2 fed in the direction of the arrow from a paper feeder 1 is timed by a pair of registration rollers 3 and transferred to a latent image carrier consisting of a photoreceptor 4 on a drum. transported to. The photoreceptor 4 is
The photoreceptor 4 is rotated counterclockwise, its surface is charged by the charger 5, and is irradiated with laser light from the laser optical system 6 to form an electrostatic latent image on the photoreceptor 4.

When this latent image passes through the developing device 7, it is made visible by the toners 1 to 2, and this visible image is transferred to the recording paper 2 conveyed to the photoreceptor 4.
The image is transferred by the transfer charger 8. The transferred visible image on the recording paper is fixed by a fixing device 9. Then, the recording paper 2 that has exited the fixing device 9 is transferred to the first paper ejection roller pair 1.
1. The paper is conveyed in the direction of arrow B via the second paper ejection roller pair 12, and is ejected to the paper ejection tray 13'2.

On the other hand, residual toner is removed from the photoreceptor 4 after the visible image has been transferred by a cleaning device having a cleaning blade 14 . The toner removed from the photoreceptor 4 is collected in a 1-toner collection tank 15 and stored there.

The above is the time to print on one side of the recording paper 2.

When printing on both sides of the recording paper 2, the visible image on the recording paper 2 is fixed in the same way as above, and the conveyance path is switched by the first switching claw 18 after passing the ↓ pair of paper ejection rollers 11. and is conveyed in the direction of arrow C toward the duplexer 17.

After that, the first. Second. Third conveyor roller pair 19.20°21
Then, it is conveyed in the direction indicated by the arrow by the reversing roller pair 22. The reversing roller pair 22 is such that the rear end of the recording paper 2 is connected to the reversing roller pair 22.
2, that is, the recording paper 2 is stopped and reversed. Then, the conveyance path of the recording paper 2 is switched by the second switching claw 23, and the recording paper 2 is re-fed in the direction of arrow A. Thereafter, the recording paper on which double-sided printing is performed is discharged onto the paper discharge tray 13 through the same process as that for single-sided printing 1-.

FIG. 5 shows an enlarged view of the suction conveyance portion (FIG. 4) that conveys the recording paper upward to the photoreceptor 4. That is, the developed image on the photoreceptor 4 is recorded on the recording paper 2 by the transfer charger 8. The electrostatic adhesion force between the recording paper and the surface of the photoreceptor generated by this electrostatic transfer is reduced by a separation charger 24 such as a corona generator, thereby separating the recording paper tinged with 1 henna from the photoreceptor. When conveying the recording paper from the photoconductor to the fixing device 7, the recording paper is sucked and conveyed from above by the suction fan 25, which may cause the recording paper to wrap around the photoconductor or not be conveyed properly to the fixing device. This prevents jams from occurring.

In other words, in conventional electrostatic transfer and separation, the toner image formed on the photoconductor is transferred from the photoconductor to the recording paper by electrostatically attracting it from the photoconductor to the recording paper by applying a voltage of opposite polarity to the toner from the back side of the recording paper. The recording paper is then subjected to a corona discharge using a separation charger to reduce the electrostatic charge holding the recording paper on the photoreceptor, and then separated by an appropriate separation method, such as separation by the recording paper's own weight, or as in this example. Furthermore, in the case of conveyance, the transfer paper is separated from the photoreceptor by separation using a suction fan or the like.

(Problems to be Solved by the Invention) 3-4- However, in a laser printer that forms images on both sides of recording paper, the recording paper printed on the first side (front side) must be re-fed to perform double-sided printing. The recording paper is transported toward the paper side (fourth direction), but in the transportation process up to that point, the image is fixed by the fixing device 9, and the first switching claw (
Due to switching of the conveyance path to the duplexer 17 by the fourth embodiment (18), curling occurs in the direction of shrinking toward the second side.

When printing on the second side (back side) in this state, the photoreceptor 4
When separating the recording paper stuck to the paper, the recording paper curls downward, so the recording paper is not separated properly, and with the help of its own weight, it falls downward as shown in Figure 5. The toner may fall down and get wrapped around the photoreceptor 4 (, ia), or may not be conveyed correctly to the fixing device 9 (jb), causing a jam.

In this way, when the second side of the recording paper is separated during double-sided printing, the first side has been printed and has gone through processes such as passing through the fixing device and being conveyed to the reversing unit, so the recording paper is slightly separated. Because both of the recording paper curled and became easily wrapped around the photoreceptor, the recording paper could not be separated completely with the same voltage applied to the separation charger as when separating the first side recording paper, causing the jam as described above. .

If the voltage applied to the separated charger is constantly adjusted to the worst conditions and separated by a high applied voltage, the above problems will disappear, but this will place a load on the separated charger and shorten its lifespan, as well as increase power consumption. It becomes impossible to ignore.

In order to solve the above-mentioned conventional problems, the present invention controls the voltage applied to the separation charger by changing it when separating the recording paper on the first side and when separating the recording paper on the second side, thereby increasing the separation efficiency and increasing the voltage applied to the separation charger. The purpose is to reduce the applied voltage to the necessary minimum and effectively utilize the double-sided printing function.

(Means for Solving the Problems) In order to achieve another object of the present invention, in an image forming apparatus capable of double-sided printing, the voltage applied to the separation charger supplied from the high-voltage power supply is changed during printing on the first side. In comparison, it is characterized by having a controller that sets the setting higher when printing on the second side.

(Function) The present invention increases the voltage applied to the separation charger when separating the recording paper on the second side to improve the separation efficiency, thereby preventing the occurrence of jams, and preventing image formation and recording paper when printing on the second side. Separation is ensured.

(Embodiment) Figure 2 is a block diagram showing the configuration of an embodiment of the present invention, in which 26 is a controller (see Figure 4) of an image forming apparatus (laser printer), and a controller (see Figure 4) sends data from a host machine (not shown). Converts incoming print data into a printable image signal. Reference numeral 27 denotes an engine driver, and only the parts related to the present invention are shown, and 27-1 is a microcomputer (CPU) that detects and controls machine states such as paper feeding, paper ejection route selection, image forming sequence, and errors. 28 is an applied voltage controller to the separate charger 24, and the above C
The voltage applied to the separate charger is controlled by the signal from PU27-1. The separation charger 24 separates the recording paper 2 from the photoreceptor 4 with separation efficiency increasing in proportion to the applied voltage.

FIG. 2 is a block diagram showing a specific example of FIG.
Control lines (1) and (2) are connected from -1 to control lines (1) and (2), and voltage control signals applied to the separate charger 24 during printing on the first and second sides are transmitted to these control lines (1) and (2), respectively. be done. 29 is a high-voltage power supply that supplies the separation charger 24, and the control line (1).

Due to the applied voltage control signal from (2), a higher voltage is supplied from the high-voltage power supply during printing on the second side than during printing on the first side.

Next, the operation of this embodiment will be explained using the flowchart shown in FIG.

When the print operation starts (1), the CPU 27
-1 is to determine from which paper feeding position the paper is fed 2),
If the paper feeding position is the paper refeeding position of the duplexer 17, (3)
, the CPU switches the control line (1) input to the separate charger applied voltage controller 28 that drives the separate charger 24 and sets it as the control line (2).
4).

Specifically, this will be explained using FIG. 2. In Fig. 2, control 1 is normally used (even when using illegal paper)? ．． Only (1) is true, and the voltage set to the normal level is applied from the high voltage power supply 29 by the separate charger applied voltage controller 28. When paper is fed from the paper refeeding position, only the control line (2) becomes true by the CPU, and a voltage higher than normal is applied to the separation charger 24 by the controller to control the recording paper during printing on the second side. The charger generates a corona discharge with an applied voltage sufficient for separation, and can quickly separate the recording paper.

The printing operation for the second side is completed and the recording paper is ejected (5
) and the CPU returns the voltage applied to the separate charger to normal (makes only the control line (1) true) (6).

As described above, the voltage applied to the separation charger is controlled when separating the recording paper on the first side and when separating the recording paper on the second side.

(Effects of the Invention) As explained above, the present invention provides a voltage applied to the separation charger so that the separation efficiency is improved when separating the recording paper on the second side of the recording paper than when separating the recording paper on the first side of the recording paper. By controlling the paper, even recording paper that has been printed on the first side and has gone through processes such as passing through the fixing device and being transported to the reversing unit, curling and making it difficult to separate properly, can be transferred to the photoreceptor. The recording paper can be separated without causing jams such as wrapping around the paper.

In addition, since the voltage applied to the separate charger is kept to the minimum necessary except when necessary, it does not put a burden on the separate charger and shorten its lifespan. I! The first order can also be minimized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing a specific example of FIG. 1, FIG. 3 is an operation flowchart of this embodiment, and FIG. FIG. 5 is a partial enlarged view of the schematic configuration diagram of the laser printer shown in FIG. 4, which has a main conveyance type double-sided printing function. 4...Photoconductor, 8...Transfer charger, 9...
...Fixing device, 24... Separation charger, 25...
Adsorption fan, 26... Controller, 27...
Engine driver, 27-1... Microcomputer (CPU), 28... Separate charger applied voltage controller, 29... High voltage power supply, (1), (2)... Control line (1, ), (2).

Claims (1)

[Claims] A separate charger in an image forming apparatus capable of double-sided printing, comprising a controller that sets a voltage applied to the separate charger supplied from a high-voltage power supply to be higher during printing on the second side than during printing on the first side. Control device.