JPS6133712B2 - - 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. A charge image is formed thereon. The charge image formed on the electrostatic recording paper 6 is converted into a toner by a developing device 8, and the toner is melted and fixed by a heat fixing device 9.

FIG. 2 shows V _N ,
In the waveform diagram of VC and _VC , _VP is the potential of the electrostatic recording paper 4 directly below the control electrode 2 to which _VC is applied. Third
The figure 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 this V
The capacitance of the dielectric layer 5 that is in contact with the control electrode 2 next to the control electrode 2 to which _C is applied, and R _G is the resistance of the conductive base paper 4 from the control electrode 2 to which V _C is applied to the ground point. The value R _S is the resistance value of the conductive base paper between the two control electrodes. This potential V _P is, for example, the second
The waveform becomes as shown by curve a in the figure. That is, V with a time constant of C _S1 ×R _G R _S /(R _G +R _S )
The differential waveform of _C almost matches the waveform of V _P . Both R _G and R _S , which govern this time constant, decrease rapidly as the temperature and humidity rise, so V _P changes at the rise of V _C at high temperature and high humidity, as shown in the model as curve b in Figure 2. After showing a peak, it rapidly decays. 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~
This is a large value of about 400pF. Therefore, the time constant τ _N of the rise of the recording needle voltage V _N is longer than the time constant τ _C of the rise of the control voltage V _G , and therefore the decay time constant of V _F becomes smaller. Under high temperature and high humidity conditions where V _P exhibits characteristics as shown in the second curve b, V _P decays to a small value before V _N reaches its saturation value, resulting in a significant decrease in recording density, and eventually recording becomes impossible. This results in the disadvantage that . The first drawback that conventional methods cannot avoid is a decrease in recording density in such a high temperature and high humidity atmosphere.

Furthermore, the conventional method has a second drawback of appearance of a coast image due to voltage leakage to adjacent control electrodes as described below. FIG. 4 shows an example of the most basic circuit configuration used in the conventional method. Here, 101 is a recording stylus electrode in which a large number of recording stylus electrodes are arranged in a line, and 201 is a control electrode divided into units of a predetermined number of recording stylus 101 and arranged on both sides of the recording stylus. Here, for convenience of explanation, an example is shown in which the recording needles 101 are divided into every five recording needles. Further, the recording needles 101 are alternately connected in parallel to groups A and B every five needles so as to form a total of 2n blocks. In this configuration, A ₁
When recording a block, a recording needle voltage _VN is applied from the recording signal source 10a for group A according to a predetermined recording pattern in _A1 , and at the same time as _VN , _S1 and S of the control electrodes 201 are applied. A control voltage V _G is applied to ₂ from the control voltage source 11. Recording is performed only in the portion where both V _N and V _C are applied simultaneously, that is, block _A1 . Below, when recording A _k , apply V C to S _2k-1 and S _2k , and when recording B _o , apply V _C to S _2k and S _2k+1 , and record one line one by one. finish.

Now, considering the state where pulse voltage V _G is applied to S _2k-1 and S _2k , the control electrodes S _2k-2 and S on both sides
As illustrated by curves a and b in FIG. 5, the potential V _g of the electrostatic recording paper directly under the _2k+1 electrode increases due to the leakage of V _C , producing a ghost voltage V _g . Here, curves a and b correspond to V _g under low humidity and high humidity conditions, respectively. The reason why V _g increases rapidly on the high humidity side is that in the equivalent circuit shown in Fig. 3, R _S becomes smaller due to the decrease in the conductive base paper of the electrostatic recording paper, so the capacitance C _S2 of the adjacent control electrode This shortens the charging time constant and increases V _g . For this reason, while printing should be performed only with A _k in FIG. 4, recording will be performed simultaneously with A _k+1 or A _k-1 . This extra recorded image is called a ghost image, and the appearance of this image was the second drawback of the conventional method. The present invention provides an electrostatic recording method that can completely eliminate the drawbacks of such conventional methods.

FIG. 6 shows a typical relationship between the control voltage V _C and the recording needle voltage V _N in the present invention. The feature of this method is that the control voltage V _E is positive and negative.
It consists of a combination of pairs of pulses. That is, a first control voltage pulse V _C1 of the same polarity as V _N is applied, and then a control voltage pulse V _C2 of opposite polarity to V _N (positive polarity on this side) is applied and superimposed on this second pulse. By applying V _N within a certain period of time (simultaneously in this example), the above-mentioned two drawbacks of the conventional method are removed.

FIG. 7 shows a model of changes in the potential V _P of the conductive base paper of electrostatic recording paper, in order to explain the effect of removing the decrease in recording density under high humidity conditions by the method of the present invention. It is something. Here, the curve a
and b show the temporal changes in V _P at low humidity and high humidity, respectively. First, when the first control voltage pulse V _C1 of negative polarity is applied at time A and turned off at time B, V
As shown in curves a ₁ and b ₁ between AB, _P decays slowly at low humidity and rapidly at high humidity. As can be seen from the equivalent circuit in Figure 3, when considering the state in which V _C1 is cut off and point A is grounded, the capacitance C _S1 of the dielectric layer of the electrostatic recording paper directly under the control electrode to which V _C1 was applied is charged. V _P is reversed to the positive polarity side by the amount of voltage applied. This state is shown by the curve between BC in Figure 7.
The magnitude of the reversal voltages a ₂ and b ₂ becomes larger on the high humidity side where the attenuation of V _P is higher. The present invention utilizes the property that this reversal voltage becomes larger on the high humidity side to prevent a decrease in recording density. V _C1
A second control voltage pulse V _{C2 having a polarity opposite to that of V C1 is} applied immediately after turning off, or at time C delayed by td time, and is turned off at times L and D. By applying V _C2 , V
As for _P , the voltage due to V _C2 is superimposed on the inverted voltage due to V _C1 , and V _P becomes a larger value than when only V _C2 is added. The value of this V _P is the curve a ₃ , b ₃ between C and D
As shown in , the peak value on the high humidity side automatically becomes larger. Curve ab in the same figure shows the V P waveform at low humidity and high humidity in the case of no V _C1 in the conventional method shown in Figure 2, and as shown in curve b, V _P waveform on the high humidity side. Although the attenuation of _P increases, in the method of this invention, b ₃ becomes more a ₃ than a 3 at the inversion voltage.
Since it becomes larger, a decrease in recording density can be completely prevented. Also, due to the presence of this inversion voltage, V
It also has the advantage that the recording density is higher in all atmospheres than in the case of only _C2 .

Note that since the V _C1 newly introduced in this invention has the same polarity as the recording needle voltage V _N , recording is not performed and no trouble occurs due to the introduction of V _C1 .

FIG. 8 shows the temporal change in the potential V _g of the conductive base paper of the electrostatic recording paper directly under the adjacent control electrode, in order to explain the ghost removal effect according to the present invention. When a negative V _C1 pulse is applied, V _g rises to the negative polarity side as shown by curves a ₁ and b ₁ under low humidity or high humidity conditions, respectively. Next, when V _C2 is applied at point C, V _g starts to reverse, but V _C1 and V _C
Since the induced voltages of ₂ are in the direction of canceling each other, V _C2
The values a ₂ and b ₂ of V _g on the same polarity side can be made extremely small as shown in the figure. The waveform of V _g obtained by the conventional method becomes curves a and b in low humidity and high humidity, and its effect is clear from comparison with curve a ₂ b ₂ . In this invention, the smaller the delay time td between V _C1 and V _C2, the better, but it was confirmed that the ghost reduction effect can be observed even when td is set to several times the pulse width of V _C1 or V _C2 .

Figure 9 shows a method for completely removing V _g even when td exists. By making the pulse width of V _C1 longer than V _C2 , the V g at the end of V _C2 pulse application is reduced. It is possible to make _g almost zero voltage. A similar effect can also be achieved by making the peak value of the pulse of V _C1 larger than that of V _C2 . Conversely, even if the voltage or pulse width of the V _C1 pulse was made smaller than that of V _C2 , the above-mentioned drawbacks of the conventional method could be eliminated. In this way, in the present invention, as long as V _C1 and V _C2 are pulses of opposite polarity, their waveforms or the timing of their application are not limited to any particular relationship.

Furthermore, in this invention, for convenience of explanation, it is assumed that the electrostatic recording paper has the simplest two-layer structure of a dielectric layer and a conductive base paper. This feature can be exhibited even when using an electrostatic recording paper formed in multiple layers such as three layers, and is not limited to a specific structure of the electrostatic recording paper.

Furthermore, the method of the present invention can be applied to all control methods in which the potential of a conductive layer is controlled by a control electrode via a dielectric layer, and it is possible to apply the method to any control method that attempts to control the potential of a conductive layer by using a control electrode through a dielectric layer, and can be applied to any control method that attempts to control the potential of a conductive layer by using a control electrode through a dielectric layer. This is effective regardless of the grouping method, division method, etc.

Furthermore, the method of the present invention does not limit the recording medium to electrostatic recording paper; for example, an electrostatic recording medium based on a plastic film, or an electrostatic recording medium formed on the same cylindrical drum that can be controlled on one side. All can be used as control methods such as

Further, in the above explanation, each of V _C1 and V _C2 is assumed to be one pulse, but each may be a combination of any n number of pulses. Further, the polarities of V _N , V _C1 and V _C2 are relative, and it goes without saying that the same effect can be obtained even if a direct current or pulse voltage is applied to the entire recording section.

As detailed above, the method of the present invention makes it possible to completely eliminate the decrease in recording density and the appearance of ghost images at high humidity, and can be used in a wide range of applications such as facsimiles and electrostatic recording printers.
It exhibits extremely excellent features such as recording stability and improved image quality.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing an example of the basic configuration of the printing section of an electrostatic recording device using an electrostatic recording head for single-sided control, and Fig. 2 shows the recording needle voltage V _N and control in the conventional recording method. A waveform diagram showing the relationship with the voltage V _C , Fig. 3 is an approximate equivalent circuit of the control electrode section, Fig. 4 is a circuit diagram showing a basic configuration example used in the conventional recording method, and Fig. 5 is a diagram showing the basic configuration example used in the conventional recording method. , a waveform diagram of a ghost voltage appearing in the conventional recording method, FIG. 6 is a waveform diagram showing the relationship between V _N and V _C in the present invention, and FIG. 7 is a waveform diagram showing the relationship between V N and V C in the present invention. FIG. 8 is a diagram for explaining changes in paper potential V _P , and FIG. 9 is a waveform diagram of ghost voltage V _g in this embodiment.
FIG. 5 is a waveform diagram of V _C1 , V _C2 and V _g in another embodiment of the invention. In the figure, 1 is a recording needle, 2 is a control electrode, 3 is an electrostatic recording head for single-sided control, 6 is electrostatic recording paper, and 7
is a roller, 8 is a developing device, 9 is a fixing device, 10a, 1
0b is a recording signal source, and 11 is a control voltage source.

Claims (1)

[Scope of Claims] 1. A single-sided control electrostatic recording head having a recording needle electrode and a control electrode arranged in parallel with the recording needle electrode is driven to cause a charge in the dielectric layer of a recording medium that is in contact with the recording head. When forming an image, a first
A control pulse voltage is applied, and then a second control pulse voltage of opposite polarity is applied, and at the same time, a recording pulse voltage of opposite polarity to the second control pulse voltage is applied to the recording needle electrode. An electrostatic recording method characterized by: 2. The electrostatic recording method according to claim 1, wherein the potential difference of the first control pulse voltage with respect to ground is made larger than that of the second pulse voltage. 3. The electrostatic recording method according to claim 1, wherein the application time of the first control pulse voltage is longer than that of the second control pulse voltage.