JPS6117273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-stylus device used in electrostatic recording.

Conventionally, in the electrostatic recording method, a multi-stylus head has been used as a means of forming an electrostatic latent image, but in general, a multi-stylus head is used as shown in Fig. 1a.
As shown in the figure, a large number of electrodes A are arranged in a line.
With such a head, even in the so-called rise-up method in which a latent image is created by electrode A on an initially uncharged surface, the charge can be partially removed by electrode A from the uniformly charged surface. It is said that good results can be obtained even with the so-called pull-out method. However, 200mm per second
Given the relative speed between the latent image receiving surface and the multi-stylus, it is difficult to fill the small gap between the electrodes A.

Further, such defects are not detected when a relative speed of about 1000 mm per second is applied. This is considered to be a special phenomenon involving the ionization of the air gap and the drift speed of ions due to the electric field.

In order to avoid such a phenomenon, it is conceivable to arrange the electrodes A in a staggered manner as shown in FIG. At this time, even if direct current or pulse voltage is applied to all of the electrodes A, contamination will still occur between the wires, and in extreme cases, only every other electrode may be activated. This phenomenon occurs particularly when the thickness of the electrode A is large.

As a result of detailed analysis of this phenomenon, we found the following. For example, if thin metal wires with a diameter of 0.12 mm are insulated with a thickness of 0.009 mm and are closely arranged in a row, the electrode A will be DC, AC, etc. as long as it is operated at a relative speed of 200 mm/s. Alternatively, good results cannot be obtained no matter which pulse is applied. If the applied voltage is increased until the line remaining between the electrodes A and A can be erased, the line width will become thicker, making it impossible to accurately express fine lines. Also,
Even if the staggered arrangement is used, the diameter of electrode A is a as shown in Figure 3.
The results are even worse when the electrodes A and A are placed at intervals of The more the electrode A works, the worse it becomes, and for example, at a speed of 50 mm/sec, it hardly works.

As a result of investigating the cause of this, it was first discovered that the problem with electrodes A arranged in a row was basically as follows. First, as shown in FIG. 4, when two electrodes A are lined up and a voltage is applied to both electrodes, the distribution of electric lines of force formed on the charge receiving surface B is as shown in the figure. As a result, the lines of electric force tend to bulge outside the two pins, and if you try to reduce the thickness of the lines, the small area between the lines will not be able to be completely charged. In other words, it was found that a kind of interference occurred between the electrodes A.

Next, when we arrange the staggered arrangement as shown in Figure 3, considering that electrode A runs first and electrode A runs next, there is a problem because it acts on the new charge-receiving surface B. If the latent image, shown schematically in FIG. 5, is already present, a fairly narrow gap must be filled in, if the latent image is already present. The electric charge coming out from this point generates an induced charge, which effectively lowers the electric field strength between electrode A and charge-receiving surface B even if the same voltage is applied to electrode A as to electrode A. It was found that due to this, electrode A malfunctioned.

The present invention was developed in view of the above points, and it is possible to express thin lines even if the relative running speed between the latent image receiving surface and the multi-stylus head is slowed down, and the attached mechanisms such as the developing device are made larger. The objective is to obtain a multi-stylus device that does not require

The present invention provides a multi-stylus head that faces a latent image receiving surface and forms an electrostatic latent image on the latent image receiving surface, and the electrodes of this multi-stylus head are arranged in a staggered manner so that the electrodes running first are arranged in a staggered manner. The thickness is set to be thinner than the thickness of the electrode running later, and the electrode running first and the electrode running later are set to be adjacent to each other, so that when the electrode running first operates, the electrode running later is sure to operate. Since the same voltage is applied to these electrodes, even if the electrode running first operates, no induced charge will be generated in the electrode running later, and this eliminates mutual interference between the front and rear electrodes. The structure is such that an electrostatic latent image can be formed.

An embodiment of the present invention will be described based on FIGS. 6 to 8. First, the conductive drum 1 is formed of aluminum into a cylindrical shape and is electrically grounded, and its surface, polished to a flatness of 1 μm or less, has a latent image formed by a heat-shrinkable polyester film about 20 μm thick. It has a charged body 2 coating that serves as a receiving surface. A corona charger 3, a multi-stylus head 4, a developing electrode 5, a transfer section 6, and a cleaning brush 7 are arranged around the conductive drum 1 in accordance with the electrostatic recording process. Here, the corona charger 3 is applied with a shield electrode 8 biased with a voltage of DC-500V and a voltage of AC4KV. It consists of a wire-shaped discharge electrode 9. Moreover, the multi-stylus head 4 has a large number of electrodes 10.
₁ , 10 ₂ , ...10n are arranged in a staggered manner at a density of, for example, 6 lines/mm, and each print signal is a pulse signal in which characters, symbols, figures, etc. are decomposed into point images or line images. Electrodes 10 ₁ , 10 ₂ ...
... Switching transistors 11 ₁ , 11 ₂ connected to the collector side and serving as a drive circuit
11n base. A voltage of +250V is commonly applied to the collector sides of the switching transistors 11 ₁ , 11 ₂ , . . . 11n. The tip of the multi-stylus head 4 and the conductive drum 1 are maintained at a constant distance (approximately 20 microns). The developing electrode 5 is biased with a voltage of -200V, which has the same polarity as the charged potential of the charged body 2 but has a relatively opposite polarity, and positively charged toner particles as a developer are transferred to the multi-stylus head 4. Toner is supplied to the formed electrostatic latent image to form a toner image that becomes a visible image. Furthermore, the cleaning brush 7 is for removing residual toner on the conductive drum 1, and is made of urethane rubber or the like.

Further, a charging belt 12 is provided in contact with the conductive drum 1 at the transfer section 6 and is supported by a plurality of rollers 13 . The charging belt 12 is made of conductive rubber and has an insulating film of 20 to 30 μm thick on its surface, and is provided with a corona charger 14 that uniformly charges the charging belt 12 positively. In this case, the setting is such that more charges are applied than the negative charges to the charged body 2 by the corona charger 3. A roll of recording paper 15 is provided on the paper feeding side of the transfer unit 6, and is set to be fed to the transfer unit 6 side by a motor 17 based on a signal from a position detector 16. . Here, a rotary cutter 18 is provided for cutting the recording paper 15 into a predetermined length before reaching the transfer section 6. Furthermore, a fixing section 19 is provided for the recording paper 15 having been transferred and carrying a toner image, which is fed by the charging belt 12 . The fixing section 19 includes belts 20 and 21 arranged vertically, and a flash lamp 22 such as a halogen lamp for thermally fixing the toner image on the recording paper 15.

Therefore, the electrodes 10 ₁ , 10 ₂ . . . 10n
Since the electrodes 10 ₁ , 10 ₃ . . . with an even number of suffixes are arranged in a staggered manner as described above, the electrodes 10 1 , 10 3 . electrode 10
₂ , 10 ₄ . . . are assumed to run later, and their diameters are set large. This state is shown in Figure 8a,
The electrode portion and the printed state are shown separately in FIG.

Note that the minimum thickness of the printed line is, for example, the thin electrode 10 ₁ and the thick electrode 10 ₂ that are adjacent to each other.
The electrode 10 that runs first
If any one of electrodes 10 ₂ , 10 4 , . . . operates, the corresponding electrodes 10 ₂ , 10 ₄ , _.

In such a configuration, the charged body 2 of the conductive drum 1 is uniformly negatively charged by the corona charger 3. As described above, when the charged body 2 passes through the multi-stylus head 4 with a surface potential of -500V, a printing signal is applied to only the switching transistors _11Y corresponding to the electrodes _10Y necessary for recording to turn them ON. As a result, the potential of the electrode _10Y becomes zero, and the electric charge of the charged body 2 is not affected by this electrode _10Y . On the other hand, the switching transistor _11N for the electrode _10N corresponding to the non-image portion not required for recording remains in the OFF state. As a result, the potential of the electrodes _10N becomes +250V, and the negative charge on the portion of the charged body 2 that these electrodes _10N face is removed or reduced, and the potential is raised from the initial -500V to about -100 to 0V. . Therefore, after passing through the multi-stylus head 4,
On the charged body 2, the original - is recorded only in the part to be recorded.
A negative potential of 500V remains, which forms an electrostatic latent image. Next, as the conductive drum 1 rotates and faces the developing electrode 5, the positively charged toner particles are electrically attracted to and adhere to the -500V electrostatic latent image. On the other hand, in the non-image area, the potential of the charged body 2 is between -100 and 0V, which is more than 100V higher than the developing electrode 5 at -200V and exhibits a positive polarity, so the positively charged toner particles are in this area. Then, it is electrically repelled and does not adhere to the charged body 2. In this way, only the electrostatic latent image portion on the charged body 2 is developed with toner particles and becomes a visible image, and this toner image reaches the transfer section 6.

On the other hand, the recording paper 15 is being sequentially fed by the motor 17 that operates based on the signal from the position detector 16.
It is cut into a predetermined length by a rotary cutter 18 and sent onto the charging belt 12. Here, each cut recording paper 15 is synchronized with the print signal, development timing, etc., and when transferred to the transfer section 6 by the charging belt 12, the toner image on the charged body 2 is transferred to the recording paper. transferred onto the surface of 15. and,
The image is transferred to the fixing unit 19 side. In this transfer process, since the charged belt 12 is charged with many positive charges by the corona charger 14 so as to have the opposite polarity to the charged body 2, the recording paper 15 is attracted by electrostatic force, and the conductive drum 1 and can be easily peeled off and transferred. When the recording paper 15 carrying the toner image reaches the fixing section 19, the toner image is thermally fixed by the flash lamp 22.

Therefore, when forming an electrostatic latent image using the multi-stylus head 4 as described above, the first electrode 1
0 ₁ , 10 ₃ ..., the potential interval of the charged body 2 is quite wide, and the subsequent electrodes 10 ₂ , 1
0 _{4 .} . ., it is also possible to perform solid printing as required, as shown in FIG. 7.

In the present invention, as described above, the electrodes of the multi-stylus head facing the latent image receiving surface are arranged in a staggered manner, and the thickness of the electrodes running first is set to be thinner than the thickness of the electrodes running later. There is no interference between the electrodes during image formation, and as a result, extremely good images can be obtained.

[Brief explanation of the drawing]

Figures 1a and b are explanatory diagrams showing the electrodes and the printed state, Figure 2 is a bottom view of the staggered electrodes, Figure 3 is a partial bottom view showing the arrangement, and Figure 4 is the electrical FIG. 5 is an explanatory diagram showing the potential of the latent image receiving surface; FIG. 6 is a side view showing an embodiment of the present invention; FIG. 7 is a circuit diagram; FIG. 8 a, b FIG. 2 is an explanatory diagram showing the relationship between electrodes and printed states. 2... Charged body (latent image receiving surface), 4... Multi-stylus head, 10 ₁ , 10 ₂ , 10 ₃ ......
10n...electrode.

Claims (1)

[Claims] 1. A multi-stylus head is provided facing the latent image receiving surface and forming an electrostatic latent image on the latent image receiving surface,
The electrodes of this multi-stylus head are arranged in a staggered manner, and the thickness of the electrodes running first is set to be thinner than the thickness of the electrodes running later, so that the electrodes running first and the electrodes running later are adjacent to each other. A multi-stylus device characterized in that when the electrode running first in a pair is operated, the electrode running later is always operated and the same voltage is applied to these electrodes.