JPS6332633B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic recording method using an electrostatic recording head for single-sided control.

FIG. 1 is a conceptual diagram showing the basic configuration of the printing section of an electrostatic recording device using a conventionally known electrostatic recording head for single-sided control (hereinafter simply referred to as a recording head), in which 1 is a recording stylus. In this example, a large number of needles are arranged in a direction perpendicular to the plane of the paper, and control electrodes 2 each divided into a predetermined number of recording needles 1 are provided on both sides of the needles. An electrostatic recording paper 6 consisting of a conductive base paper 4 and a dielectric layer 5 is pressed against the head surface of the recording head 3 having such a structure with a rubber roller 7 as shown in the figure. Under this condition, normally, a negative recording needle voltage V _N is applied to the recording needle 1 and a positive control voltage V _C is applied to the control electrode 2 at the same time, and the surface of the dielectric layer 5 of the electrostatic recording paper 6 is A charge image is formed thereon. The charge image formed on the electrostatic recording paper 6 is developed with toner by a developing device 8, and the toner is melted and fixed by a heat fixing device 9.

Figure 2 shows V _N in this conventional recording method,
In the waveform diagram of V _C , V _P is the potential of the conductive base paper 4 directly under the control electrode 2 to which V _C is applied. Figure 3 shows an approximate equivalent circuit of the control electrode when such V _C is applied, where C _S1 is the capacitance of the dielectric layer 5 directly under the control electrode 2 to which V _C is applied, and C _S2 is The capacitance of the dielectric layer 5 in contact with the control electrode 2 next to the control electrode 2 to which this V _C was applied, R _G is the conductive base paper 4 from the control electrode 2 to which V _C was applied to the ground point. resistance value,
R _S is the resistance value of the conductive base paper between the two control electrodes. This potential V _P has a waveform as shown by curve a in FIG. 2, for example. That is, C _S1 ×
The differential waveform of V _C , which has a time constant of R _G R _S /R _G + R _S ), almost matches the waveform of V _P. R _G that governs this time constant
Since both R and _S decrease rapidly as temperature and humidity rise, V _P peaks at the rise of V _C and then rapidly decays at high temperatures and humidity, as shown by modeled curve b in Figure 2. Resulting in. A charge image is formed on the surface of the dielectric layer 5 by this V _P and the recording needle voltage V _N , but in the case of multi-needle electrode recording, many recording needles are connected in parallel by grouping. The capacitance between the recording needles is 150 to 400 _P.
The value is as large as F. For this reason, the recording needle voltage
The time constant τ _N for the rise of V _N is longer than the time constant τ _C for the rise of the control voltage V _C , and therefore the attenuation speed of V _P becomes somewhat faster. Under high temperature and high humidity conditions where V _P exhibits the characteristics shown in curve b in Figure 2, V _P attenuates to a small value before V _N reaches its saturation value, resulting in a significant drop in recording density, and eventually This results in the disadvantage that recording becomes impossible. The biggest disadvantage of this method is that the recording density decreases in a high-temperature, high-humidity atmosphere, which cannot be avoided by conventional methods.

This invention was made with the aim of eliminating the drawbacks of such conventional methods, and involves applying a control voltage V _C of reverse polarity and forward polarity for one cycle, and prior to application of the control voltage of forward polarity, Further, the recording voltage of the opposite polarity is applied while the voltage induced in the recording medium directly under the control electrode by the control voltage of the opposite polarity remains.

FIG. 4 is a diagram showing an example of the application pattern of the control voltage and recording voltage according to the present invention, and FIG. 5 is a waveform diagram for explaining the mode of change in the potential V _P when such a voltage application pattern is used. For convenience of explanation, the time from time B when the application of the control voltage V _C1 of reverse polarity is removed to time C when the control voltage V _C2 of forward polarity is next applied is made longer. The characteristic curve a shown by the broken line in the figure shows the change characteristics of V _P at low humidity.
The characteristic curve b shown by the dashed-dotted line shows the change characteristics of V _P at high humidity. First, when a first control voltage pulse V _C1 of negative polarity is applied at time A,
At low humidity, as shown in characteristic curve _a1 , the
At high humidity, it decays rapidly as shown in characteristic curve _b1 .
As can be seen from the equivalent circuit in Figure 3, considering the state immediately after the application of V _C1 is removed and point A is grounded, V _P is the electrostatic recording paper directly below the control electrode to which V _C1 was applied. The capacitance C _S1 of the dielectric layer of is reversed to the positive polarity side by the charged voltage. This state is shown by curves a ₂ and b ₂ between BC in FIG. The magnitude of this reversal voltage becomes larger at times of high humidity, where V _P is significantly attenuated. The present invention utilizes this property to prevent a decrease in recording density at times of high humidity. That is, the recording stylus voltage pulse V _N is also applied between times BC when the reversal voltage appears in FIG.
By performing printing _twice , it is possible to prevent a decrease in recording density at times of high humidity. Figure 6 is a characteristic diagram showing the change characteristics of V _P when time BC is set short. When time BC is shortened, the reversal voltage between BC due to V _C1 (curves a ₂ and b ₂ ) is sufficiently attenuated. The second control voltage pulse V _C2 is applied during this period. Therefore, CD with V _C2 applied
Since the voltages induced by both are weighted between them, the peak value of V _P rises to a voltage higher than the voltage of V _C2 as shown in curves a ₃ and b ₃ . Since the peak value of V _P is higher at high humidity, where potential attenuation is large, it is not only possible to completely prevent a decrease in recording density, but also to increase the recording density at high humidity. I can even do it. In the embodiment shown in FIG. 6, consideration is given to allowing the inversion voltage between BC to be fully utilized by advancing the point of application of V _N from point B by the rise time of V _N. In this way, the synergistic effect that high humidity is recorded in both b ₂ and b ₃ makes it possible to more completely compensate for high humidity. This invention can be implemented in many ways, as shown below, but the essential condition is that the recording needle voltage must be maintained within the time period during which the reversal voltage caused by the previously applied control voltage pulse appears. This is to apply a pulse _VN .

FIGS. 7A to 7D each show a modification of the electrostatic recording method of the present invention. First, A in the figure shows an example of changes in the timing of V _N application, and a is V _C1
Simultaneously with the application of , b precedes the application of V _C2
This is an example in which _VN is applied. In this way, the timing of application of V _N precedes the start of application of V _C2 , and as long as V _N is applied before the inversion voltage Vp due to V _C1 attenuates, wide changes are possible. Figure B is
This is an example in which V _N is divided and added, and in this case, the recording density can be controlled by controlling the pulse width T _N1 .
In this way, V _N is not limited to a single pulse. Figure C shows an example in which the pulse width t _C1 of V _C1 is made shorter than that of V _C2 . In this case, the inversion voltage of V _C1 can be controlled by t _C1 , and the humidity dependence of recording density can be controlled. have. The present invention is not limited to a specific pulse width, pulse voltage, or waveform as long as V _C1 and V _C2 are pulses of opposite polarity. FIG. 2 shows an example in which V _C1 and V _C2 are divided into three pulses and applied, and the control voltage pulse can be divided into an arbitrary number of pulses in this way. Furthermore, it is of course possible to combine any of these.

FIG. 8 is an example of a circuit for generating control voltage pulses of opposite polarity according to the present invention, where 1
0 and 11 are NPN and PNP transistors respectively,
Reference numeral 12 indicates load resistors 13 and 14 representing positive and negative power supplies, respectively.

In the explanation of this invention, for convenience, an electrostatic recording paper having a two-layer structure of a dielectric layer and a conductive base paper was explained, which is the simplest. Its features are also highlighted when used in combination with structured electrostatic recording paper, and the electrostatic recording paper is not limited to those having a specific structure.

Furthermore, the present invention does not limit the recording medium to electrostatic recording paper; for example, electrostatic recording media using a plastic film-based electrostatic recording medium, an electrostatic recording medium formed on a cylindrical drum, etc. Needless to say, it can be widely applied to recording devices.

Also, the polarities of V _N , V _C1 , V _C2, etc. in the above explanation are relative, and it goes without saying that the same effect can be obtained even if the polarities of V _C and V _P are reversed. Nor.

As detailed above, according to the method of this invention,
It is possible to completely eliminate the decrease in recording density at times of high humidity.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing the basic configuration of a printing section of an electrostatic recording device using an electrostatic recording head for single-sided control;
Figure 2 is a waveform diagram of the recording needle voltage V _N and control voltage V _C in the conventional single-sided electronic control method, Figure 3 is an approximate equivalent circuit diagram of the control electrode section, and Figure 4 is the control voltage according to the present invention. FIG. 5 is a waveform diagram for explaining the mode of change in the potential V _P of the conductive base paper of the electrostatic recording paper in this invention, and FIGS. 7A to 7D are waveform diagrams of other embodiments of the present invention, and FIG. 8 is a diagram showing an example of a control voltage application circuit. In the figure, 1 is a recording needle electrode, 2 is a control electrode,
3 is an electrostatic recording head for single-sided control, and 6 is an electrostatic recording paper. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Voltages of opposite polarity are simultaneously applied to the recording needle electrode and the control electrode of a single-sided control electrostatic recording head having a recording needle electrode and a control electrode arranged in parallel to the recording head. In an electrostatic recording method in which a latent charge image is formed on a dielectric layer of a recording medium in contact with the recording medium, a first control pulse voltage is applied to the control electrode, and then a second control pulse voltage of the opposite polarity is applied. , prior to the application of the second control pulse voltage and while the voltage induced in the recording medium directly under the control electrode by the first control pulse voltage remains, the first control pulse voltage is applied to the recording needle electrode.
An electrostatic recording method characterized in that a recording pulse voltage having the same polarity as a control pulse voltage is applied.