JPS61215565A - Electrostatic recording device - Google Patents

Abstract

PURPOSE:To charge a no-image formation area electrostatically to a potential at which no toner sticks and to prevent the waste of toner by using a discharging device which switches a voltage applied to a grid to set a discharging current to an opposite-polarity voltage or ground voltage when discharging is not necessary. CONSTITUTION:When a drum type photosensitive body 1 begins to rotate, a switch 6 is placed at the side of a power source 8 and the photosensitive body 1 is not electrostatically charged. When the front end of the image formation area on the photosensitive body 1 reaches an electrostatic charger 2, the switch 6 is charged over to the side of a power unit 7 to electrostatically charge the photosensitive drum. The surface of the charged photosensitive body 1 is processed by the incidence of image light 9, development, etc., and when the rear end of the image formation area passes by the charger 2, the switch is returned to the side of the power source 8, so that the charging of the photosensitive body 1 is stopped. Consequently, the no image formation area is not charged substantially and the charge of the no-image area need not be erased before development.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic recording device using a discharge device having a grid.

[Prior art]

2. Description of the Related Art Electrostatic recording devices using a discharge device having a grid as a charger for a photoreceptor are known. In this electrostatic recording device as well, the charger uniformly charges the surface of the photoreceptor both on the part where the image light is incident and on the part where the image light does not enter, just as in the case without a grid. It was used to apply a voltage of the same polarity as the one used to adjust the uniform charging potential of the photoreceptor. Therefore, conventional electrostatic recording devices include those that use a charger with a grid, To eliminate the unnecessary charge on the part of the photoreceptor where the image light does not enter, which causes waste of toner, etc., a static elimination lamp such as a fluorescent tube, LED, E L lamp, tungsten lamp, etc. is installed between the charger and the position where the image light enters. If the document is erased using the platen cover, or if the original on the platen glass is irradiated with an exposure lamp and the reflected light is incident as image light, the document holding surface of the platen cover or the platen glass may The lower surface of the side end or the lower surface of the scale plate provided at the side end was made white, and the light reflected from these white surfaces was used to erase the static electricity. Electrical recording devices become larger and more expensive, and those that use reflected light from the white surface of an exposure lamp have the problem of creating unnecessary charged areas that are not erased. However, there is also the problem that the photoreceptor is susceptible to deterioration since it is impossible to remove the charge with light after it has been charged.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned problems in conventional electrostatic recording devices, and the present invention has been made in a state where a discharge device having a grid such as a charger does not substantially discharge while a discharge voltage is applied to the discharge electrode. This makes it easy to prevent charging of the photoreceptor from unnecessary areas where image light is not incident, or to use a common power source for discharge electrodes such as chargers and transfer devices. And, it is an object of the present invention to provide an electrostatic recording device in which the life of a high-voltage power supply device can be extended because the number of times the discharge voltage is applied to the discharge electrode is turned on and off can be reduced.

[Structure of the Invention] The present invention provides an electrostatic recording device using a discharge device having a grid, in which the voltage applied to the grid is switched between when discharge of the discharge device is required and when discharge is not required. The above-mentioned object is achieved by an electrostatic recording device characterized in that it uses a discharge device that applies a voltage with a polarity opposite to that of the discharge current or a ground voltage when the discharge current is not required.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

Fig. 1 is a graph showing the relationship between the voltage applied to the grid and the charged potential of the photoreceptor, Fig. 2 is a schematic side view showing an example of the electrostatic recording device of the present invention, and Fig. 3 is a graph showing the electrostatic recording device of the present invention. It is a block diagram which shows the example of the discharge device used.

In the present invention, when a discharge device having a grid as a charger is used, the charging potential on the surface of the photoreceptor changes significantly as shown in FIG. 1 as the bias voltage applied to the grid changes. It was discovered and done.

FIG. 1 shows a drum-shaped photoreceptor 1 shown in FIG. 2 with an organic photoconductor layer, ie, an OPC photoreceptor layer, having a thickness of 15 μm on its surface, moving in the direction of the arrow at a surface speed of 125 m/8 (A). The charger 2 rotates, and the charger 2 has the configuration shown in detail in FIG. ．． Otm, and the high-voltage power supply 5 applies a discharge voltage to the discharge electrode 4 made of stainless steel wire with a diameter of 60 μm so that a discharge current of 600 μA flows.
2 shows changes in the surface potential of the photoreceptor charged by the charger 2 when the grid bias voltage applied to the charger 2 is changed. As can be seen from FIG. 1, the grid bias voltage applied to the grid 3 is reduced to the ground voltage, which has a greater effect of shielding the passage of ions. By setting the voltage to have the opposite polarity to the current, the charged potential of the photoreceptor is erased by the reflected light from the blank part of the document.
The voltage can be lowered to a blank paper potential of about -70 to -100V. The embodiment of the present invention shown in FIGS. 2 and 3 utilizes this variation of FIG.

First, the operation of the electrostatic recording apparatus shown in FIG. 2 will be explained.

The drum-shaped photoreceptor 1 is uniformly charged by a charger 2, exposed to image light 9 to form an electrostatic image, and the electrostatic image is developed by a developing device IO. After the toner image formed by development is transferred to a transfer paper by a transfer device 11, the transfer paper is separated from the photoreceptor 1 by a separator 12, and the residual toner on the photoreceptor 1 is cleaned by a cleaning device 13.

The operation of the charger will be explained with reference to FIG.

The charger 2 has a discharge electrode 4 and a grid 3, and the discharge electrode 4 is connected to a high voltage 11# device 5. Further, the grid 3 is connected via a change-over switch 6 to a power source 8 for preventing discharge or a power source device 7 for controlling charging consisting of a varistor or a Zener diode. A power source 8 for blocking discharge is a power source that generates a voltage with a polarity opposite to that of the discharge current. As shown in Fig. 1, even when the voltage of the voltage #i8 is set to zero, that is, the grid is grounded, the surface of the photoreceptor 10 remains at the same level as when the electrical charges are erased by the light reflected from the white paper. Since the potential is approximately -too v, which is approximately equal to the surface potential, a circuit in which the power supply 8 is omitted and the grid 3 is grounded may be used. However, as far as grounding is concerned, charging of the photoreceptor 1 can be more effectively prevented by keeping the grid 3 at a voltage with a polarity opposite to that of the discharge current. The voltage of the power source 8 may be set to an optimum value in relation to a+ factors such as the characteristics of the photoreceptor used and process conditions such as development.

In the electrostatic recording apparatus shown in FIG. 2, first, when the drum-shaped photoreceptor 10 starts rotating, the switch 6 is connected to the power source 8 side, and the photoreceptor 1 is not charged.

When the tip of the image forming area of the photoreceptor 1 reaches the position of the charger 2, the switch 6 is switched to the power supply device 7 side, and charging is performed. The surface of the charged photoreceptor 10 undergoes processes such as incidence of image light 9 and development. When the rear end of the image forming area of the photoreceptor 1 passes the position of the charger 2, the switch is switched again to the power source 8 side, thereby preventing the photoreceptor 1 from being charged.

As a result, the non-image forming area is not substantially charged, and there is no need to erase the charge in the non-image area before development.

For the grid 3 of the charger 2, stainless steel wires or tungsten wires with a diameter of 80 to 120 μm are usually used, but instead of the parallel wires, meshes or metal plates slit or etched may also be used. Can be used. In addition, the discharge electrode 4 has a diameter of 50 to 80 μm.
A stainless steel wire, a tungsten wire, a gold-plated tungsten wire, or the like is used, and a negative high voltage of -5 to -7 kV is applied by a high voltage power supply 5. Even if the conditions are changed within this range, results that are almost the same as those in FIG. 1 can be obtained, so the effects of the present invention described in FIG. 2 remain unchanged.

Above, we have described an example in which the charger discharges negatively, but it goes without saying that the charger may discharge positively. Needless to say, it will become. Further, in the example shown in FIG. 3, the charge control power supply device 7 and the discharge prevention power supply 8 are separated, but they may be integrated. In other words, when the photoreceptor needs to be charged by the integrated grid control device, a voltage of the same polarity as the discharge current is applied to the grid, and when charging is not required, a ground voltage or a voltage of the opposite polarity to the discharge current is applied to the grid. All you have to do is apply it.

Furthermore, since the present invention puts the discharge device into a substantially inoperable state by applying a discharge voltage to the discharge electrode and the voltage applied to the grid, it is possible to reduce the number of times the voltage is applied to the discharge electrode on and off. This can extend the life of the high-voltage power supply, and it is also possible to share the high-voltage power supply that applies to the discharge electrodes of discharge devices such as the charger 2, transfer device 10, or separator 11 shown in FIG. Make it. The effect of extending the life of the high-voltage power supply device can be obtained even if the discharge device having a grid in the present invention is not a charger but a transfer device or a separator, and the high-voltage power supply device can be shared. This effect can be obtained without any problem even if the transfer device or separator does not have a grid as shown in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the non-image forming area of the photoconductor where the image light is not incident is set to a potential at which toner does not adhere, thereby preventing wastage of toner, and using a charge erasing means such as a charge eliminating lamp. It is possible to eliminate the need for the high-voltage power supply, extend the life of the photoreceptor, extend the life of the high-voltage power supply of the discharge device, and easily share the high-voltage power supply with the charger, transfer device, etc. It can have excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between the voltage applied to the grid and the charged potential of the photoreceptor, Fig. 2 is a schematic side view showing an example of the electrophotographic apparatus of the present invention, and Fig. 3 is a graph showing the relationship between the voltage applied to the grid and the charged potential of the photoreceptor. FIG. 2 is a configuration diagram showing an example of a discharge device. 1... Photoreceptor, 2... Charger, 3...
Grid, 4... Discharge electrode, 5... High voltage power supply, 6... Changeover switch, 7... Charge control power supply, 8... Discharge prevention power supply, 9... Image light, 10...
Developing device, 11... Transfer device, 12... Separator, 13... Cleaning device. Patent applicant: Konishiroku Photo Industry Co., Ltd. Figure 1 Figure Z

Claims (2)

[Claims] (1) In an electrostatic recording device using a discharge device having a grid, when the voltage applied to the grid is switched between when discharge of the discharge device is required and when discharge is not required, when discharge is not required. An electrostatic recording device characterized in that it uses a discharge device that generates a voltage with a polarity opposite to that of the discharge current or a ground voltage. (2) The electrostatic recording device according to claim 1, wherein the discharge device is a charger that charges a photoreceptor by discharge.