JPS58215673A - Electrostatic image developing method - Google Patents

Abstract

PURPOSE:To perform high-density, fog-free development efficiently, by providing an electrode for producing an alternating electric field where ink mist moves along an image carrier surface. CONSTITUTION:An ultrasonic oscillator 4 is provided in an ink reservoir 3 at the lower part of a developing device 2 provided so that its upper opening surface 2a is close to the surface of the image carrier 1a, and a high-voltage electrode 5 such as a parallel stylus electrode whose tip faces a liquid surface is provided at a lower part close to the liquid level of the ink in the ink reservoir 3. The ink in the ink reservoir 3 is oscillated by the ultrasonic oscillator 4 to generate the ink mist and the discharge atomization phenomenon by the high-voltage electrode 5 is made effective to activate the production of the mist more; and particles of the mist are fine and electrified sufficiently to perform high-density, fog- free development efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electrostatic image developing method using ink mist.

Conventionally, there is no known method of developing an electrostatic image using ink mist by guiding an ink mist generated using ultrasonic vibration or the like along the surface of an image carrier on which an electrostatic image is formed. There is. Such a developing method using ink mist has the following problems: (1) It is difficult to apply sufficient charge to the ink mist during the ink mist generation process using ultrasonic vibration, etc. (2) It is difficult to apply sufficient charge to the ink mist during the ink mist generation process by ultrasonic vibration, etc.; Difficult to control and maintain to prevent fogging, ■
Therefore, the development efficiency is poor and the development speed cannot be increased.
This method has the disadvantage that development is performed that provides low-density image quality, or that fog is observed. Therefore, a method has been proposed in which a corona discharge means is provided in the ink mist passage so as to charge the ink mist.
Even so, it is not possible to provide a satisfactory charge, and it is still difficult to control the retention of ink mist.

An object of the present invention is to maintain ink mist at high density along the surface of an image carrier, or to apply appropriate force toward the surface of the image carrier, so that development can be carried out efficiently with high density and without fogging. It provides the development method to be carried out.

The developing method of the present invention is characterized in that an electrode is provided in a portion of the ink mist along the image holder surface to generate an alternating electric field, and this feature achieves the above-mentioned object.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIGS. 1 and 4Z are cross-sectional views showing an example of the apparatus for carrying out the method of the present invention, and FIGS.
In the example shown in the figure, the ink mist is held in the development area and development is performed 6. A principle diagram showing the state in which development is performed. FIG. 5 is a principle diagram showing the state in which development is performed in the example shown in FIG. FIG. 7 is a partial configuration diagram showing an example in which the voltages applied to the m poles are different.

In the figure, / is an image carrier having an electrostatic image holding layer /a made of Se, ZnO, etc. on its surface, which moves in the direction of the arrow, and is connected to a charge imparting device (not shown) provided on the right side of the figure or further. An electrostatic coating is formed on the electrostatic image holding layer/a by an exposure device. λ is a developing device using ink mist, and is provided so that the upper open surface 2a is close to the surface of the image carrier l. This developing device i\λ is equipped with an ultrasonic oscillator in the ink reservoir 3 below, and also
At the bottom near the liquid surface of the ink that accumulates, there are parallel needle-like electrodes with the tips facing the liquid surface as shown in Figure 1, or plate-shaped electrodes with the sharp ends facing the liquid surface, as shown in Figure ψ. A high-voltage electrode j, such as a wire electrode shown in FIG. Such a high-voltage electrode S does not necessarily have to be always below the liquid level, but rather is preferably provided close to the liquid level so that it appears above the liquid level due to undulating fluctuations in the liquid level. In the example shown in FIG. 1, such a state of the high voltage electrode j is caused by the fact that the amount of ink replenished from the ink supply tank 6 is controlled by the liquid level control valve 7 to reduce the level of ink accumulated in the ink reservoir 3. In the example shown in FIG. q, the liquid level is maintained at the open lower end position of the ink supply pipe t'. However, the invention is not limited to these, and for example, a liquid level detection means may be provided in the ink reservoir 3,
The high voltage electrode S may be displaced upward or downward based on the information, or the current flowing through the high voltage electrode S may be detected,
The upper and lower positions of the high voltage electrode j may be controlled so that the current is constant.

The illustrated ink mist generating device has the above-described configuration, and in such an ink mist generating device, when only the ultrasonic oscillator≠ is oscillated, the ink accumulated in one ink reservoir 3 vibrates, On the other hand, if a high voltage of the same polarity or different polarity as the ink charge is further applied to the high voltage electrode j, the discharge mist generated by the high voltage electrode 3 will be generated. With the addition of the oxidation phenomenon, the generation of ink mist becomes even more active.
Moreover, the particles of the mist are fine and sufficiently charged. For example, if you use water-based ink with a viscosity of 6 to lθapS and a resistivity of /θ6 to /θ8Ω・Fu, and generate ink mist using only an ultrasonic oscillator, the ultrasonic The oscillation of the oscillator V is 3θW18If MHz
When carried out under the following conditions, ink mist charged to about -0,/μO/g is generated at a rate of about xr mcC/sea. For that, without using an ultrasonic oscillator, the diameter! When a gold-plated wire of 0 μm is used as the high-voltage electrode j, and a DC voltage of about 10 kV with the opposite polarity to that of the electrostatic coating is applied to the high-voltage electrode j, the electrostatic atomization phenomenon occurs. Ink mist charged to about lθμC/g is generated at a rate of about several mCC/SeC. Furthermore, the ultrasonic oscillator ψ is set to 30W1HφMHz as mentioned above.
When oscillating at More charged ink mist is generated than the combination of both effects, and the particles of the ink mist are finer than those produced by the ultrasonic oscillator 1 alone.

In the illustrated apparatus, the ink mist is generated by the oscillation of the ultrasonic oscillator q and the discharge atomization phenomenon by the high-voltage electrode j as described above, and the generated ink mist is caused by the rising air current accompanying the generation of the ink mist. Accordingly, in the illustrated example, the air is further conveyed to the upper open surface 2awI of the developing device λ by the air sent from the air inlet r, and there it comes along the surface of the image carrier. In addition, the air inlet l is
In the example shown in FIG. 1, the ink reservoir 3 is provided above the ink liquid level, and in the example shown in FIG. The air sent from such an air inlet t is
0. ．． It is preferable that the amount is such that an upward air current of about 2 m/sea is generated in order to avoid fogging during development.

At the upper open surface λa portion of the developing device 1.2 where the ink mist follows the surface of the image carrier, a control electrode such as a perforated electrode or a mesh electrode is provided in parallel to the surface of the image carrier. Reference numeral 9 denotes a developing device t forming an ink mist passage between the surfaces of the image carrier/which is shaped to close the upper open surface 2a, the inner top plate wall of 2, and the 2b portion, that is, the control electrode. A counter electrode /θ is provided below each of the electrodes 9 to face it. In the example shown in FIG. 7, the counter electrode lθ is provided separately from the inner top wall 2b of the developing device λ, but in the example shown in FIG.・Since it is made of a magnetic material, it is used as the counter electrode/θ. Between such a control electrode and the counter electrode lθ, there are
As shown in the figure, ground the control electrode and
By applying an AC voltage or a superimposed voltage of an AC voltage and a DC voltage to θ, or as shown in Figs. By applying a DC voltage or a superimposed voltage of DC voltage and AC voltage to the counter electrode /θ,
An alternating electric field is generated.

As mentioned above, the charged ink mist is introduced into the alternating electric field between the control electrode 9 and the counter electrode /θ, and there, under the action of the alternating electric field, it vibrates in the direction in which both electrodes face each other. As a result, the particles can be held stably at high density and for a long time along the surface of the image carrier. Then, when the electrostatic coating of the image carrier / enters this area, the ink mist is attracted by the electric attraction force of the electrostatic coating, passes through the control voltage w89, and adheres to the electrostatic coating. Therefore, development can be carried out efficiently and at high density without causing fog. This point will be further explained with reference to Fig. λ, Fig. 3, Fig. 3, etc.

Each of the figures shows an example in which the electrostatic image formed on the electrostatic image holding layer/a of the image carrier/is negatively charged and the ink mist is positively charged. Figure 3 is
Similar to Fig. M7, an example is shown in which an alternating electric field is generated between the grounded control electrode 9 and the counter electrode /θ by an alternating current voltage applied to the counter electrode /θ. ,
Similarly, FIGS. 6 and 7 show examples in which an alternating electric field is generated between the control electrode 9 and the counter electrode /θ by an alternating current voltage applied to the control electrode W. In the cases of FIGS. V to 7, an alternating electric field is also generated between the control electrode 9 and the image carrier l, and the control electrode 9 and the counter electrode in the case of FIG. The alternating electric field between lθ is an alternating electric field in which alternating electric fields generated by alternating voltage applied to both electrodes are superimposed.

In the examples shown in Figs. It is repulsed and moves toward the grounded control electrode 9 as shown by the arrow in Fig. 2, and when the voltage at the opposing north pole/θ is in a negative state, the voltage attracted by the third
It begins to move toward the counter electrode IO as indicated by the arrow in the figure. As a result, the ink mist is stably maintained in a floating state between both electrodes. Then, when the negatively charged static WL image of the image carrier l enters this region, the voltage of the counter electrode lθ becomes positive! When it became lK,
Due to the effects of the repulsive force caused by the voltage and the attraction force caused by the electrostatic image, the ink mist passes through the control electrode 9 and adheres to the electrostatic image as shown in FIG.

As a result, as mentioned above, high-density development without fogging is achieved. In this case, the AC voltage applied to the counter electrode /θ is ! A sine wave, rectangular wave, or pulsed wave of 00 Hz ”-□-2kHz is used, and the voltage is
Although it is related to the distance to the control electrode 9 and the distance between the control electrode and the surface of the image carrier, for example, when the former distance is about 3 fins and the latter distance is Q, 2 vm, the mountain A sufficient effect can be obtained by setting the voltage width vp-p of the trough to about 1 soo-, 2ooo v. However, it is preferable that this voltage be set as high as possible within a range that does not cause dielectric breakdown. and,
By superimposing a DC voltage on the AC voltage applied to the counter electrode /θ, the amount of ink mist passing through the control electrode 9 can be controlled by the DC voltage component, and FIG. 1 shows an example of this. ing.

In the example shown in Fig. S, the ink mist guided between the control electrode 9 and the counter electrode /θ is also affected by the alternating electric field between the two electrodes, which is generated by applying an alternating voltage to the control electrode. The image will be captured between the two, and will be held stably and at a high density. When the negatively charged electrostatic image of the image carrier / enters this area, the ink mist passes through the control electrode 9 due to the electrical attractive force of the electrostatic image and adheres to the electrostatic image. I come to do it. Moreover, in this example, since an alternating electric field is also generated between the image bearing member and the control electrode 9, the ink mist passing through the control electrode and adhering to the electrostatic image is also subjected to vibrating force here. Therefore, the electrostatic image is stably held in close proximity to the surface of the image carrier, and therefore, when an electrostatic image is received, high-density, fog-free development is performed. The reason why the ln current voltage is applied to the control electrode by superimposing it on the alternating current voltage is as follows.
This is to prevent fog from occurring when the image carrier / has a residual potential other than that of an electrostatic image, and the DC voltage applied to the counter electrode /θ is as shown in FIG.

Similar to the superimposed DC voltage described in connection with FIG. 3, the control voltage 9
This is to control the amount of ink mist that passes through.

In the examples shown in FIGS. 6 and 7, the same effect as in the example shown in FIG. 3 can be obtained. In the example shown in FIG. 7, the strength, frequency, etc. of the alternating electric field between the control electrode 9 and the counter electrode /θ can be significantly different from those between the image carrier / and the control electrode 90, thereby increasing the efficiency. to ensure that the development is done properly.
K ink mist can be stably held.

In the examples shown in FIG. 3, FIG. 6, and FIG. 7, the AC voltage applied to the control electrode 9 is as shown in FIG.

When applied to the counter electrode /θ in the example of Figure 3 or Figure 1, the same AC voltage can be used, and the DC voltage that is 1 tatami higher than the AC voltage is determined appropriately depending on the relationship with the cover. Voltage is used.

The DC voltage applied to the counter electrode /θ is determined in relation to the development density. For example, image carrier/and control electrode 9
When the distance between is 0.2, the distance between the control electrode 9 and the counter electrode to is 3, the maximum potential of the electrostatic image on the image carrier l is -1000V, and the residual potential of the non-image area is 1100V. When a superimposed voltage of a sinusoidal AC voltage with a vp-p of /300 to 000 and a DC voltage of -2001 is applied to the control electrode, and a DC voltage of 0 to 50V is applied to the counter electrode, a clear fog is observed. No development is performed.

As described above, development with ink mist is performed, but in the apparatus shown in FIG. 1 and FIG. On the exit side, I try to change the questions on the introduction and exit sides, as shown in 3 questions. By doing this, the electric field strength between the two electrodes changes, and the ink mist can be appropriately advanced from the inlet side to the outlet side. It also becomes easier to flow. Then, the oncoming lightning, including the ink mist that could not be developed and passed through the above-mentioned development area, and the ink that adhered to the control electrode and fell, was exposed to lightning at a polarity of 10K.
The deposited ink is returned to the ink reservoir 3 through the return path l/ to the ink reservoir 3.

As is clear from the above description, according to the method of the present invention, ink mist can be held at a high density in the portion along the image carrier surface, and the amount of ink mist sent toward the image carrier surface can also be controlled appropriately. Since it can be controlled, the development speed can be increased, and excellent effects such as high density and fog-free development can be obtained. Note that the present invention is not limited to the illustrated example in which the ink mist generating means uses an ultrasonic oscillator, nor is it limited to the illustrated example in which the ink mist is circulated in one direction.

Also, Figures 1 to 1. The control electrode 9 can be omitted in the example shown in FIG. 3, and the counter electrode 9 can be omitted in the example shown in FIGS.
It is also possible to omit θ, and the effects of the present invention can still be obtained to a considerable extent.

Example 1 The diameter of the ink reservoir 3 of the developing device shown in FIG. 1 is Sθ.
φ, the distance from the bottom surface of the ink reservoir 3 where the ultrasonic oscillator t is installed to the surface of the image carrier is 100 mm, the control height of the ink liquid level is 3θ, and the needle tip of the needle-shaped high voltage electrode is ink. A grid electrode is used as the control electrode 9 slightly below the control height of the liquid level, and the distance between the grid electrode and the surface of the image carrier is 0. ．． 2 fl, counter electrode/θ is the distance from the grid electrode on the ink mist introduction side and the distance on the ink mist exit side in 3θ width! iJi E Kagome, a ZnO photoreceptor is used for the electrostatic image holding layer /a of the image carrier l, and the moving speed of the image carrier / in the direction of the arrow is 100 wa/s
ec, the ink is water-based and has a resistivity of θ6 to 108Ω.
The oscillation output of the ultrasonic oscillator t is 3θW and the frequency is 4/
MHz % The voltage applied to the high voltage electrode j is 10 kV, and the velocity of the rising air that carries the generated ink mist is 0. z m/5eas
Opposing, tunfi! The voltage applied to ii/θ is! ;00Hz
, 1I00 Vrms of sinusoidal alternating current voltage, and the potential of the electrostatic image formed on the image carrier l was -tnov, and the development was performed to a reflection density of O0.

In this development, the density tended to be proportional to the potential of the electrostatic image and the development time, that is, the reciprocal of the moving speed of the image carrier, and a recorded image with excellent gradation was obtained.

Example 2 A force developing device as shown in Fig. ψ was used. The device is
The high-voltage electrode j is a gold-plated wire electrode with a diameter of 30 μφ stretched slightly below the ink level control height of the ink reservoir 3, and the counter electrode /θ is connected to the inner top plate wall 2b of the developing device λ. The device has almost the same shape and dimensions as the device shown in FIG. 1, except that it is different from the device shown in FIG. The moving speed of the image carrier and the potential of the electrostatic image were also set to the same conditions as in Example 1, and the control electrode 9 was
-p is /300 to 2000 V (7) A voltage obtained by superimposing a DC voltage of -100 V on a sine wave AC voltage is applied, and a DC voltage of 5θV is applied to the counter electrode to form the same ink and mist as in Example 1. When I developed it under the conditions where it occurred,
Excellent results similar to those of Example 1 were obtained.

[Brief explanation of the drawing]

FIGS. 1 and q are cross-sectional views showing an example of an apparatus for carrying out the method of the present invention, and FIGS. 2 and 3 are cross-sectional views showing an example of the apparatus shown in FIG. Figure S is a principle diagram showing the state in which development is performed in the example shown in Figure ψ. Figures 6 and 7 are different in the voltage application to the control electrode and counter electrode. FIG. 2 is a partial configuration diagram showing an example. l...image carrier, ■...electrostatic image,! ...
Developing device, 3... Ink reservoir, j... Ultrasonic oscillator, S... High voltage electrode, B... Ink supply tank, 6'... Ink supply pipe, 7... Liquid level control. Valve, g...Air inlet, 9...Control electrode, /θ...Counter electrode, //...Return im path. Patent applicant: Atsushi Konishi Roku Photo Industry Co., Ltd. Figure 41 Figure 5 66 Figure 7

Claims (1)

[Claims] In the method of developing the electrostatic image by guiding an ink mist along the surface of the image carrier on which the electrostatic image is formed, an electrode is provided in a portion where the ink mist follows the surface of the image carrier to generate an alternating electric field. An electrostatic image developing method characterized by: