JPS61283561A - Multi-needle electrode head type electrostatic recorder - Google Patents

Abstract

PURPOSE:To prevent the generation of unwanted phenomena due to toner adhesion on a needle electrode, by providing a power supply means establishing the electric potential of a multi-needle electrode head higher than the precharged electric potential of a transfer medium under the condition free from a printing signal. CONSTITUTION:When a recording paper 6 with the toner is fed to fixing rollers 9 and released from a dielectric belt 2, the toner is removed from the recording paper 6 by a cleaning device 11 after being electrostatic-discharged by a collotron 10 for electrostatic-discharge. At this time, a printing signal detecting circuit 31 sends a drive signal DS after confirming the absence of a printing signal 30, allowing a voltage higher than the precharged electric potential to be supplied to an electrode head 3 by a non-printing voltage circuit 32. Accordingly, an electric charge leak from the dielectric belt 2 to the head 3 is not occured, enabling the prevention of the black lines caused by the unwanted phenomena.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a multi-needle electrode head type electrostatic recording device, and in particular, a multi-needle electrode head type electrostatic recording device that takes into consideration the potential applied to the multi-needle electrode head. Regarding.

[Conventional technology]

The multi-needle electrode head has a plurality of needle-like electrodes 40 arranged linearly at regular intervals in an insulating holder 41-41, as shown in FIG. 4 cited from JP-A-56-87057, for example. This is what I did. A discharge is selectively generated between the electrode 40 and the recording medium 43 to form an electrostatic latent image. In addition,
The electrode 40 in FIG. 4(b) has a flat surface in contact with the recording medium 43, and has a control electrode 44.

As a recording method using such a multi-needle electrode head, an electrostatic latent image is formed on a recording medium made of dielectric material (for example, see Japanese Patent Laid-Open No. 57-11349) using a multi-needle electrode head, and then developed. A transfer type method is known in which a hard copy is obtained through the steps of transfer fixation and cleaning.

In this type of electrostatic recording device, methods such as fur brush cleaning, blade cleaning, and web cleaning are used as a cleaning process to remove residual toner from the developing process.

However, in general, in electrostatic recording devices, the multi-needle electrode that forms the electrostatic latent image comes into contact with the dielectric belt, so even the slightest cleaning failure causes toner to adhere to the multi-needle electrode, resulting in poor image quality on the recording paper. causing a decline.

1. As shown in FIG.
This is thought to be due to the fact that when the toner 9 adheres, the uniformly charged surface charge passes through the residual toner 49 and escapes (leak) when the toner is in a non-printing state.

In other words, a phenomenon occurs due to the potential drop accompanying this leakage, resulting in the occurrence of black streaks on the recording paper.

In addition, 45 in FIG. 5 is a spacer.

For this reason, for example, as shown in FIG.
92136), cleaner box 60, and this box 6
A doctor blade 62 disposed in the upper part of the interior and having one end in contact with the dielectric belt 61, and a seal film 63 that receives the toner scraped off by this blade 62.
A wiper blade 64 is disposed below this film 63 and has one end that contacts the dielectric belt in the opposite direction to the doctor blade, and a seal film 65 receives the toner scraped off by this blade 64. An apparatus has been proposed that includes a discharge device 66 for discharging the toner scraped off by the blades 62, 64.

This device is designed to be miniaturized by combining two blades 62 and 64, and to improve cleaning performance by arranging the blades in opposite directions.

Furthermore, as described in "Ricoh Technical Report J, October 1983 issue, page 16 onwards, there is also a method of applying bias to both the needle electrode 40 and the control electrode 44 as shown in FIG. Proposed.

The transfer-type recording method described above requires more complicated equipment than the direct-type method, in which an electrostatic latent image is formed directly on special electrostatic recording paper using a multi-needle electrode head and then developed and fixed. It has the advantage that it can record on plain paper without requiring electrostatic recording paper, has low running costs, and can write on recording paper.
3 [Problems to be Solved by the Invention] However, according to the method shown in FIG. Unnecessary development occurs, and the image quality eventually begins to deteriorate.

In addition, according to the latter bias application method, the reduction in contrast is prevented by controlling the bias application;
Unnecessary development due to toner stains on the needle electrode cannot be prevented. Furthermore, since the bias voltage is as high as 250 V, the power supply device is also expensive and uneconomical.

[Means and effects for solving the problems] This invention has the following features:
This was developed based on the above circumstances, and fundamentally prevents unnecessary development from occurring due to toner adhesion to needle electrodes in transfer-type electrostatic recording devices using multi-needle electrodes. Therefore, it is an object of the present invention to provide a multi-needle electrode head type electrostatic recording device that is equipped with a power supply means that makes the potential of the multi-needle electrode head higher than the precharge potential of the transfer medium (recording medium) when there is no print signal.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals in each figure indicate similar objects.

FIG. 1 shows an electrostatic recording device according to an embodiment of the invention.

In the figure, 1 is a pre-charge corotron, 2 is a dielectric belt which is a transfer medium, 3 is a multi-needle electrode head, 4 is a developing device, 5 is a pre-transfer corotron, 6 is a recording paper, and 7
1 is a supply roller for supplying recording paper to the apparatus, 8 is a transfer corotron, 9 is a fixing device such as a heat roller, 10 is a corotron for static elimination, 11 is a cleaning device, and 12 is a power supply device.

The precharge corotron 1 uniformly charges the surface of the dielectric belt 2 to a predetermined potential (50V) to set the potential of the non-image area.

The multi-needle electrode head 3 has a configuration as shown in FIG.
4) or the same as that explained in FIG.

A square wave voltage of -280V is applied from the power supply 12 to the needle electrode 40 of the head 3, and the control electrodes 44-44
A square wave voltage of +350V is applied to. By applying such a voltage, the space 20 directly under the electrode has approximately (50+2
A potential difference of 80 + 350 = )680 V occurs. This space 20 is approximately 5 μm thick by the spacers 45-45.
, which satisfies Paschen's discharge conditions.

Therefore, a discharge occurs in the space 20, forming an electrostatic latent image of 1150 cm on the dielectric belt 2.

The developing device 4 supplies toner, which is a magnetic component developer having a polarity opposite to that of the electrostatic latent image, onto the dielectric belt 2 to perform development.

The corotrons 5, 8, 10, supply roller 7, and thermal transfer roller 9 are well known.

As the cleaning device 11, for example, the one explained in FIG. 6 is used.

The power supply device 12 is as shown in FIG. 3, and includes a print signal detection circuit 31, a non-print voltage circuit 32, a control voltage circuit 33,
A printing voltage circuit 34 and a needle electrode drive circuit 35 are provided.

The print signal detection circuit 31 detects that the print signal 30 has disappeared for a certain period of time or more, determines that it is in a non-printing state where no printing is being performed, generates a drive signal DS, and activates the non-printing voltage circuit. 32 is activated, and when there is a print signal 30, the control voltage circuit 33 and the print voltage circuit 34 are activated.

The non-printing voltage circuit 32 supplies a voltage similar to or higher than the precharge potential (50V) of the precharge corotron 1 to the multi-needle electrode head.

The control voltage circuit 33 and the printing voltage circuit 34 apply a voltage (+350
V and -280V).

The print signal 30 is supplied to a needle electrode drive circuit 35 to selectively discharge each needle electrode.

Next, the operation of this embodiment will be explained.

When the device is started, the dielectric belt 2 is charged to a precharge potential by the precharge corotron 1. Thereafter, a discharge corresponding to the print signal 30 is generated by the multi-needle electrode 3 to charge the dielectric belt 2 and form an electrostatic latent image. Toner is attached to this electrostatic latent image by a developing device 4, and a fixing process is started on the recording paper 6 by corotrons 5, 8 and a fixing roller 9.

When the recording paper 6 is transferred to the fixing roller 9 and peeled off from the dielectric belt 2, the static electricity is eliminated by the static eliminating corotron 10, and then the toner is removed by the cleaning device 11. At this time, the print signal detection circuit 31 detects the print signal 30
It confirms that the drive signal DS does not arrive, and sends out the drive signal DS.

Therefore, the electrode head 3 is supplied with a voltage higher than the precharge potential by the non-printing voltage circuit 32.

Therefore, no charge leaks from the dielectric belt 2 to the head 3, and no black streaks are formed due to unnecessary development.

〔Effect of the invention〕

As explained above, the multi-needle electrode head type electrostatic recording device of the present invention includes a power supply means for making the potential of the multi-needle electrode head higher than the precharge potential of the transfer medium (recording medium) when there is no print signal. This makes it possible to fundamentally prevent unnecessary development from occurring due to toner adhesion to the needle electrodes in a transfer type electrostatic recording device using multi-needle electrodes.

[Brief explanation of the drawing]

Fig. 1 is a detailed explanatory diagram of the present invention, Figs. 2 and 3 are explanatory diagrams of main parts of the embodiment shown in Fig. 1, and Fig. 4 (al, (b)).
5 is an explanatory diagram of an example of a multi-needle electrode, FIG. 5 is an explanatory diagram of the operation of a conventional device, and FIG. 6 is an explanatory diagram of a conventional cleaning device. Explanation of symbols 1 ・----1--Precharge corotron 2 ---
-------1 transfer medium 3 ----1 multi-needle electrode rad 4...Developer 5----Pre-transfer corotron 6----
----1 recording paper 7----supply roller 8
・・−・−・Corotron 9 for transfer −−−−−−− Constant fixing roller 10・−−−−−
・・Corotron II for static elimination・・・・−Cleaning device 12・・・・・Power supply device Patent applicant Fuji Xerox Co., Ltd. Agent Patent attorney Shin Matsubara 2 Same as Seiji Muraki Same Same as Tadao Hirata Same Same as Jun Ueshima Figure 2, Figure 3, Figure 1, Figure 4 (a). (b) Ward 5, Figure 6

Claims (1)

[Claims] An electrostatic latent image is formed on a transfer medium made of a dielectric material by a multi-needle electrode head, toner is attached to the transfer medium and developed, and after transfer to recording paper, the image is transferred to the transfer medium. A multi-needle electrode head type electrostatic recording device for cleaning a long-needle electrode head, characterized in that the long-needle electrode head is equipped with a power source that makes the potential of the multi-needle electrode head higher than the precharge potential of the transfer medium when there is no print signal. type electrostatic recording device.