JPS6236222A - Device for conveying powder body - Google Patents

Abstract

PURPOSE:To properly convey powder bodies having the same polarity, as with the polarity of a particle such as said powder body by providing a means of controlling an alternating deriving voltage applied to an electrode. CONSTITUTION:Electrodes 2 have the same structure as an ordinary electric field curtain and are set in parallel and at equal intervals on a substrate 1. Three-shape voltage wave forms are outputted from a driving power source and a control means 3 and each phase is applied to every third electrode 2 in order. Accordingly, the arrangement of phases in the order of PHI1, PHI2, PHI3 is repeated corresponding to the arrangement of the electrodes. When a driving voltage is applied to each electrode, a particle 4 having negative toribo-polarity is conveyed in the direction of the arrow while a particle 5 having position toribo-polarity is conveyed in the opposite arrow direction. Thus, the powder body particles on the electric field curtain can be separated according to their toribo-polarity, due to the action of the particle the conveying direction of which is differentiated by its toribo-polarity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder conveying device, and relates to an entire device for conveying general powder.

(Prior art) Powder conveyance has conventionally been used for coating, developing electrostatic latent images, etc. In the field of development in particular, electric field curtain methods using electric fields are disclosed in Japanese Patent Publication No. 47-47811 and Japanese Patent Publication No. 47-47811. Publication No. 54-12667, Special Publication No. 57-985
This method is disclosed in Japanese Patent Application Laid-Open No. 58-202217, etc. ” These publications are related to powder conveying devices that convey powder only in one predetermined direction or repel powder, and specifically, use a traveling wave device that uses multiphase sinusoidal AC as a driving source. The powder is transported in the direction of movement using the electric field.

However, these powder conveyances are difficult due to the charging state of the powder,
In particular, because the process was carried out regardless of polarity, powders of different polarities could □ berries during transportation, causing transportation failures, and powders of unnecessary polarities being mixed together, which could cause many problems in the future. There are drawbacks such as the fact that

(Objective of the present invention) The purpose is to provide a device that can be transported easily.

(Summary of the present invention) The present invention achieves the object, and its feature is that the potential difference between adjacent electrodes in one direction where a plurality of electrodes are arranged at a predetermined distance from each other is The potential difference between adjacent electrodes on the side opposite to the one direction side where the electrodes are arranged is such that the voltage threshold is positive in the one direction and can move the negatively charged particles. The present invention includes means for controlling the alternating drive voltage applied to the electrodes so that the voltage threshold is negative and allows the movement of the positively charged particles.

The purpose and summary of the present invention will be understood from the following description.

(Example) In the following description, a configuration in which n-phase in-phase electrode groups are formed by electrically connecting every n electrode groups is referred to as an electric field curtain. Hereinafter, the principle of the powder separation method and the specific device configuration will be explained with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which numeral 1 represents an electric field curtain substrate made of a dielectric, numeral 2 an electrode, and numeral 3 a block including a drive power source and its control means for performing tripo polarity separation.

Electrode 2 has the same structure as a normal electric field curtain, and the substrate l
They are placed parallel and evenly spaced above. A three-phase voltage waveform as shown in FIG. 2 is outputted from the drive power supply/control means 3, and each phase is sequentially applied to each electrode 2 every two times as shown in the figure. Therefore, each phase (Φ1
,Φ2.

Φ3) are lined up sequentially from the left side as Φ1.

The arrangement is such that Φ2 and Φ3 are repeated in this order.

The voltage waveform output from the drive power supply/control means 3 is a rectangular wave whose cycle consists of alternating - times and then temporarily maintaining zero potential, and has a positive potential.

It changes every 1/3 period in the order of negative potential and zero potential. This output consists of three phases Φ1, Φ2, and Φ3, and the phases of each phase are shifted by 1/3 period as shown below.

Φl=Φ1 (t) Φ2=Φ+ (t=T/3) Φ3=Φ+ (t = 2 T/3) where t
indicates time, and T indicates period.

The peak value a of the drive voltage is limited to such that even if a potential difference of this peak value occurs between the electrodes, the charged particles do not move to the adjacent electrode portion, and conversely, it is twice the peak value, that is,
The peak/peak value 2a of the drive voltage is set to ensure that charged particles can be moved to the adjacent electrode section. That is, in this case, it is necessary to set the force configuration so that the voltage threshold for particle movement between the electrodes is between the peak value and the peak-to-peak value of the drive voltage.

When such a driving voltage is applied to each electrode as described above, as a result of the trypo polarity separation principle described later, the particles 4 with negative trypo polarity are moved in the direction of the arrow (towards one side with respect to the electrode arrangement direction), that is. The particles 5 with positive trypo polarity are transported in the opposite direction of arrow β (opposite direction with respect to the electrode arrangement direction), that is, to the left as seen. The powder particles on the electric field curtain are separated according to their tripo polarity by changing the transport direction depending on the tripo polarity of the particles.

Here, while explaining the potential difference that occurs between each electrode when the rectangular wave patterns of Φl, Φ2, and Φ3 in Figure 2 are applied, the movement of the negative polarity object e and the positive polarity powder ■ shown in Figure 3 will be explained. do.

Regarding the principle of trypo polarity separation.

l) Applying a potential difference opposite to the predetermined polarity (potential drop for the positive electrode, potential increase for the negative electrode) only in a certain direction; 2) Setting the voltage threshold for particle movement between the electrodes during the alternating electric field. Applying a potential difference between electrodes that exceeds

is important. In FIGS. 2 and 3, t and -t8 indicate the elapsed time in sequence and correspond to 1/3 period of the rectangular wave pattern, and the lines in FIG. 3 indicate the electrodes.

First, at t1, a positive polarity particle and a negative polarity particle are Φ
On the 1-phase electrode and the Φ1-phase electrode and its positive electrode (Φ2 and Φ3
) (each polar particle is shown as ee)
, this position is indicated by position g10 in FIG. 3, and its movement is shown in a top view.

At this point, there is no potential difference 2a between adjacent electrodes, so the bipolar powder does not move.

At the next tz, the square wave pattern Φl changes from 0 potential to positive potential, Φ2 goes from negative potential to zero potential, and Φ3 goes from positive potential to negative potential, and the square wave patterns Φ1 and Φ2 of the electrode part where the powder particles are located change. Since a potential difference 2a exceeding the threshold for particle movement between the electrodes occurs between the electrodes, only the positive particles are attracted to the negative potential and the adjacent rectangular wave pattern Φ3
Move onto the electrode where 5 is given. Furthermore, at t3, Φl has a negative potential, Φ2 has a positive potential, and Φ3 has a zero potential, and a potential difference 2a exceeding the threshold occurs between the rectangular wave patterns Φ1 and Φ2 of the electrode part where the negative particles are located, so the Φl electrode is Only the negative particles left above and in the vicinity are attracted to the positive potential and move onto the adjacent Φ2 electrode. At t4 of the 0th order, Φ1 is at zero potential, Φ? is a negative potential and Φ3 is a positive potential, and a potential difference 2a exceeding the threshold is generated between the square wave pattern Φ2 of the electrode part where the negative particles are located and the square wave pattern Φ3 of the electrode part where the positive particles are located. is attracted to the negative potential of Φ2 and moves from the Φ3 electrode to the adjacent Φ2 electrode, and at the same time the negative particle is attracted to the positive potential of Φ3 and moves from Φ2 to the neighboring Φ2 electrode.
As shown in the figure, the plus and minus particles move in the same way after t5 of the 0th order moving from the top of the electrode to the next Φ3 electrode, so the plus and minus particles end up in each phase as shown below. It will move on the electrode.

If we look at the trajectories of these positive particles and negative particles in units of time (the electrode positions are shown side by side for each time period so that we can compare them), they move as shown in Figure 3.

In other words, if the electrodes of each phase are lined up as shown in FIG. 1, the positive particles will move in the β direction, and the negative particles will move in the α direction.

FIG. 4 is a block diagram of an embodiment of the drive-type coining means and the alternating drive voltage control means according to the present invention, and is an implementation configuration of the so-called tribo polarity classification drive power source that outputs the three-phase voltage waveform for the tribo polarity classification described above. An example is shown. A method is adopted in which a tribo polarity classification waveform is generated by the reference pulse generation circuit 14 in the signal generation circuit 15 and then amplified.

FIG. 5 shows an embodiment of the signal generation circuit described above, mainly J
- consists of a flip-flop 6 (74LS112), an AND logic 7 (74LSO8), and a photocoupler 8. The peak value of the output signal is determined by variable resistor 9-1.
It can be controlled by 0.

In this embodiment, a three-phase tribo polarity separation drive voltage is used, but the voltage is not limited to three phases, and it is also possible to use four-phase, five-phase, and n-phase voltages. However, the n-phase tribo polarity separation drive voltage type is alternated once per cycle in order to have a tribo polarity separation effect, and the alternation time t a
f) One cycle is n/2 times or more, and the alternating timing of each phase may be sequentially shifted by half of the alternating time ta. - For example, tribo polarity of 5 phases of rectangular and shaped pulse waveforms Φl to Φ5. Figure 6 shows the separate drive voltage waveforms and the wiring and connections to the electrodes of each phase.

In this case as well, the peak value of the drive voltage is such that the inter-electrode movement threshold (voltage) is greater than the peak value and less than or equal to the peak-to-peak value (twice the peak value) of the drive voltage in order to create the tribo-separation effect described above. Furthermore, when the wave height value becomes smaller than 1/2 of the threshold value, powder particles are not moved or transported at all, and the wave height value becomes larger than the threshold value. The powder particles are transported only in one direction (in the case of this example, the α direction) regardless of their tribo polarity, and the tribo sorting effect may be lost. It is preferable that

Moreover, the tripo polarity separation drive voltage waveform is shown in FIG.

The present invention is not limited to the example shown in FIG. 6, but a similar effect can be obtained using the type shown in FIG.

The difference is that the former (Figures 2 and 6) alternate in the order of plus and minus, while the latter (Figure 7) alternate in the order of minus and plus. When the driving voltage shown in FIG. 7 is directly applied to the electric field curtain shown in FIG. 1, particles of plus and minus polarities are transported in directions completely opposite to the arrows (α, β) in the figure.

Further, in this embodiment, a rectangular waveform is used as the tripo polarity separation drive voltage waveform, but a curvilinear waveform or a triangular waveform as shown in FIG. 8 may also be used.

FIG. 9 shows an example in which a tripo polarity separation electric field curtain is applied to a developing device of an electrostatic recording device, in which 11 is an electrostatic latent image carrier, 12 is a toner hopper, and 13 is a positive polarity electrostatic latent image. .

Here, one side of the tripo polarity separation electric field curtain faces the latent image carrier, and each phase electrode of the electric field curtain has positive particles β
The direction is set so that the minus particles are transported in the α direction. Therefore, when toner is supplied from the hopper 12 onto the electric field curtain, toner particles with positive polarity are transported in the β direction, and those with negative polarity are transported in the α direction. In this case, the negative toner particles transported in the α direction eventually reach the development area sandwiched between the latent image carrier and the electric field curtain facing it, and in this case, the toner particles are affected by the alternating electric field due to the alternating drive voltage. It is attracted onto the electrostatic latent image while being subjected to so-called jumping development (
(See Japanese Patent Publication No. 58-32375).

Generally, for development of electrostatic recording, a toner having a polarity opposite to that of the electrostatic latent image is used, but some toner particles having the same polarity as the latent image are included in the toner. These toner particles are called "reverse toner" and are the cause of so-called "background fog", which degrades image quality. However, by using a tripo polarity separating electric field curtain as in this embodiment, this reversed toner tip can be removed and development can be carried out with only toner particles of the required polarity, resulting in good image quality without "background fog".

On the other hand, when the latent image is of negative polarity in the embodiment shown in FIG. 9, if a rectangular wave pulse is applied as shown in FIG. 2, the direction of movement of the charged powder is reversed and proper development can be performed.

As explained above, by using a waveform that has a tripo polarity separation effect for the driving voltage of the electric field curtain, the transport direction of the powder particles can be varied depending on the tripo polarity of the powder particles.
This has the effect of sorting the particles into tripopolar groups.

Furthermore, if this tripo polarity separation electric field curtain is applied to a developing device for electrostatic recording, good image quality without so-called "background fog" can be obtained.

(Effects) Since the present invention can distinguish the polarity of charged particles, it is possible to solve the problem caused by the coexistence of charged particles of both polarities.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a tripo polarity separation electric field curtain, Fig. 2 is a driving voltage waveform diagram of the electric field curtain, Fig. 3 is an explanatory diagram of movement of charged particles according to Figs. 1 and 2, and an example of each electric field curtain. 7 and 8 are respectively different types of electric field curtain drive voltage waveform diagrams, and FIG. 9 is a side view of an example of application of the electric field curtain to an electrostatic recording and developing device. 1 is an electric field curtain substrate (dielectric material), 2 is an electrode, 3 is a tripo polarity separation drive power source, 4 is a negative particle, 5 is a positive particle, 6 is a flip-flop logic for J-, 7 is an AND logic, 8 is a photocoupler, 9. lO is a variable resistance,
11 is an electrostatic layer, an image carrier, 12 is a toner hopper, 13
is an electrostatic latent image. hφ, f26ζ, both h and φ1

Claims (1)

[Claims] (1) a plurality of electrodes arranged at predetermined intervals, and means for applying alternating driving voltages to the electrodes;
In a device for transporting charged particles, the potential difference between adjacent electrodes in one direction on which the electrodes are arranged is positive in that one direction and becomes a voltage threshold that can move the negatively charged particles. and so that the potential difference between adjacent electrodes on the side opposite to the one direction on which the electrodes are arranged is negative in the opposite direction and becomes a voltage threshold at which the positively charged particles can be moved. 1. A powder conveying device comprising means for controlling an alternating drive voltage applied to an electrode, and separating powder according to particle charge polarity.