JPS6063574A - Electrostatic image recording device - Google Patents

Abstract

PURPOSE:To execute satisfactorily a development, and also to prevent effectively a trouble such as clogging caused by an ink bubble, by using ink having >=34dyn/cm surface tension as ink converted into a mist. CONSTITUTION:Developing ink 4 is contained in an ink tank 3, and an ink mist 4' is generated by an operation of an ultrasonic vibrator 6, and absorbed and developed to an electrostatic latent image from a slit 2 through a pump 5. Also, as for the ink 4 to be used, the upper limit of an adding quantity of an interfacial active agent is set to about 0.1wt%, and an ink surface tension is set to >=34dyn/cm. According to such a constitution, a good development is executed easily, and also a trouble such as clogging caused by an ink bubble, etc. can be prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an electrostatic photographic recording apparatus that develops an ink by forming it into a mist and depositing it on an electrostatic recording medium on which an electrostatic latent image is formed.

An example of a developing device in an electrostatic photographic recording apparatus using ink mist developing method is explained from FIG. 1. (1) is a vertically installed ring-shaped duct, (2) is a duct (1) A developing slit (3) formed at a part of the upper end of the duct (1) is an ink tank connected to the lower part (1) of the duct (1), and stores the developing ink (4). (5) is a pump installed in a part of the duct (1), and (6) is an ultrasonic vibrator fixed to a part of the outer surface of the ink tank (3). The slit (2) is arranged opposite to a part of the movement path (8) of the electrostatic recording medium (7) on which the electrostatic latent image is formed.

The developing device (9) basically performs the following operations, namely:
When the ultrasonic vibrator (6) is actuated to apply ultrasonic vibration to the ink (4) in the ink tank (3), the surface of the ink (4) is atomized and an ink mist (4') is generated. Combined with this, when the pump (5) is activated, the ink mist (4) is generated.
') circulates within the duct (1) in the direction of the arrow shown. In this state, when the electrostatic recording medium (7) on which the electrostatic latent image is formed near the slit (2) is run, ink mist (4゛) near the slit (2) appears on the charged part of the electrostatic latent image. Development is performed by electrostatic adsorption. Such an ink mist developing method has the advantage that development is completed at the stage of adhesion of the ink mist (4'), and therefore (2) no fixing process is required, making it easy to use and advantageous in terms of equipment.

By the way, one of the conditions for performing development using the ink mist printing method with good contrast is the appropriate range of the particle size of the ink mist, and this appropriate value is an average particle size of approximately 3.
~10 μm. The generation of such ink mist having an average particle size of 3 to IO μm is adjusted by the input power of the ultrasonic vibrator. This input power has a valid range,
If the power is lower than the effective range, the generation of ink mist will become unstable, making it impossible to supply an appropriate ink mist with uniform particle size, resulting in poor print density, image quality, etc.

Furthermore, if the surface tension of the ink used in the ink mist printing method is high, the state of adhesion to the recording paper will be uneven, resulting in blurring and the like, degrading the image quality. Therefore, it is advantageous in terms of print image quality and print density to lower the surface tension by adding a surfactant to the ink as long as the image quality does not bleed.

(3) By the way, if too much surfactant is added to the ink, small bubbles will be generated on the ink surface as ink mist is generated, and these bubbles will increase and cover the ink surface and prevent the generation of ink mist. However, there were problems such as bubbles rising and clogging the duct of the developing device.

OBJECT OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an electrostatic photographic recording apparatus that solves the problems.

21. Constitution of the Invention The present invention is characterized in that an ink having a surface tension of 34 dyn/c- or more is used in an apparatus that prints by making ink into a mist. As a result of investigating the appropriate range of the amount of surfactant added to the ink used in the ink mist method, the inventor found that if the surfactant is added so that the surface tension of the ink is less than 34 dyn/cm. It has been found that the amount of bubbles generated with the generation of ink mist increases noticeably, and at 34 dyn/c+w or higher, even if bubbles are generated, the amount is small enough to cause no problem. Therefore (4
) The present invention provides an electrostatic photographic recording device using ink under the above conditions, and when developing with such an ink using an ink mist printing method, it is easy to obtain a high-quality image, and the eye of the developing device is also improved. Travel caused by blockages is also eliminated.

E, Example Examples will be described below.

The ink used is JIW-1000 from Dai B Hon Ink Co., Ltd.
, Sodium dodecylbenzenesulfonate was used as a surfactant to be added, and a developing device as shown in Fig. 1 was used, with a developing slit width of 3 mm, a developing speed of 0.75 cm/s, an ink liquid temperature of 30°C, and an ink mist flow rate. 1m/3, humidity 40%
When development was carried out under the following conditions while changing the amount of surfactant added, the results shown in FIG. 2 were obtained. Further, the relationship between the amount of the surfactant added to the ink (-1/%) and the surface tension (dyn/Cm) of the added ink is shown in FIG. 3. However, 2TI! The horizontal axis in J is the input power (W) of the ultrasonic transducer, and the vertical axis is the relative level of contrast of the image developed on the electrostatic recording medium (5), and the higher the vertical axis, the better the image. to show that

Curve a in FIG. 2 shows the case where the amount of surfactant added is OWt/% (surface tension 52 dyn/cs), and it can be seen that sufficiently good development can be achieved if conditions such as development speed are set. The curve b s C% d s e in Figure 2 shows that the amount of surfactant added is 0.02 Wt/%, 0.04 Wt/%, and 0.08 Wt.
/%, 0.11t The results are shown by increasing the amount little by little to 7%.

The curve f shows the result of increasing the amount of addition to 0.12 Wt/%, and in the case of 0.12 Wt/%, there is a noticeable amount of bubbling on the ink surface, resulting in poor development or inability to develop. Therefore, the upper limit of the amount of surfactant added to perform good development is approximately 0.IWt/%, and the surface tension of the ink at this amount of addition is approximately 34
It can be seen that it is dyn/c-.

In fact, when we carried out development by varying the ink mist flow rate in the range of 0.4 to 2 m/s, we found that when the amount of the above-mentioned surfactant added exceeds 0.1 @t/%, the mist flow becomes small when the mist flow is slow. Clogging occurred due to bubbles, and when the mist flow was high (6), the bubbles jetted from the slits could fly off near the electrostatic recording medium and stain the electrostatic recording medium.

However, 0. If the IWt is 7% or less, there will be no clogging due to bubbles even after long-term operation, and ink mist adhering to the electrostatic recording medium will not aggregate and cause blurring, resulting in good quality images. In addition, good results were obtained in that the ink had a high degree of absorption into the electrostatic recording medium and the ink did not stick to the hands even immediately after development.

Almost the same results were obtained even if the type of ink and the type of surfactant were changed.

9. Effects of the Invention As described above, according to the present invention, it becomes easier to perform development using the ink mist printing method, and troubles such as clogging due to ink bubbles in the developing device are reduced, making maintenance easier. A high-quality electrostatic photographic recording device that is easy to manage can be realized.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view showing an example (7) of a developing device in an electrostatic photographic recording apparatus, and FIGS. 2 and 3 are experimental results and ink characteristic diagrams for explaining the present invention. (4) --- Ink, (7) --- Electrostatic recording medium. (8)

Claims (1)

[Claims] (1) In a device in which a mist of ink is selectively attached to an electrostatic recording medium on which an electrostatic latent image is formed for development, an ink having a surface tension of 34 dyn/c- or more is used as the ink. An electrostatic photographic recording device characterized by: