JPS604987B2 - Two-color electrostatic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention develops positive and negative electrostatic latent images formed on recording paper with different colored toners charged with negative and positive polarities, respectively, to create a two-color visible image. This relates to a two-color electrostatic recording device which is designed to obtain two-color electrostatic recording devices, and in particular, it is caused by the potential difference generated in the developing space between the recording paper and the developing device due to the high voltage applied to the charging section in the developing section. This is to prevent soiling.

FIG. 1 is a configuration explanatory diagram showing an example of a conventional two-color electrostatic recording device of this type, in which 1 column of recording paper, 20 a charging section, 3
0 is a developing section.

A low resistance layer 11 is formed on one side of the recording paper 10, and a high resistance layer 12 is formed on the other side. Charging section 20
is composed of a counter electrode 21 and a discharge electrode 22, in which the counter electrode 21 is arranged so as to be in contact with the low resistance layer 11 of the recording paper 10, and the discharge electrode 22 is arranged so as to face the high resistance layer 12. It is located in Note that these counter electrodes 2
1 and discharge electrode 22 are complementary connected to a power source V and ground via switches S, S2, which are controlled in response to polarity designation signals, respectively. The developing section 30 is composed of a paper pressing roll 31 and a developing device 32,
The paper pressing roll 31 is arranged so as to contact the low resistance layer 11 of the recording paper 10 and press the recording paper 10 toward the developing device 32, and the developing device 32 has a magnetic brush 32b formed by a magnetic roll 32a. A developer 32c containing a toner charged to a negative polarity and a toner charged to a negative polarity is placed on a recording paper 1.
Magnetic so that it can be applied to the high resistance layer 12 of 0. Rule 32a
The magnetic brush 32b is arranged between the magnetic brush 32b and the recording paper 10 to maintain a developing space. Note that this developing section 32 is grounded. In such a configuration, the recording paper 10 moves in the direction of arrow A.

As a result, electrostatic latent images of positive polarity and negative polarity are formed on the recording paper 10 in the charging section 2, and these electrostatic latent images are developed and visualized in the developing section 30. Figure 2 is the first
FIG. 2 is an explanatory diagram illustrating an example of the operation of the apparatus shown in the figure in terms of an equivalent circuit, and shows a case where a negative electrostatic dew image is formed on a recording paper 10 by a charging section 20.

In FIG. 2, R is the contact resistance between the counter electrode 21 and the low resistance layer 11 of the recording paper 10, R3 is the contact resistance between the paper pressing roll 31 and the low resistance layer 11 of the recording paper 10, r , are these counter electrodes 21, paper presser roll 31, and recording paper 1.
This is the internal resistance of the recording paper 10 between the contact points with the low resistance layer 11 of zero. As shown in FIG. 2, a voltage V is applied to the counter electrode 21, and the discharge electrode 22 is grounded, so that a negative electrostatic latent image is formed on the recording paper. but,
Here, a current flows from the counter electrode 21 to the paper pressing roll 31 via the low resistance layer 11 of the recording paper 10.
As a result, a positive development bias voltage Vo caused by the voltage applied to the counter electrode as shown in equation {1-1] is generated in the development space. Then, due to this developing bias voltage Vo, negatively charged toner adheres to the recording paper, resulting in background stains.

On the other hand, when forming a positive electrostatic latent image, the counter electrode 2
1 is grounded, the developing bias voltage Vo of the '1' equation becomes zero. As a result, striped background stains occur in response to the polarity switching of the static latent image, resulting in a significant deterioration in recording quality. The present invention prevents such scumming, and will be described in detail below with reference to the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention, in which a is an explanatory diagram of the configuration and b is an equivalent circuit diagram of a.

Note that the same parts as in Fig. 1 are given the same reference numerals.
In FIG. 3, four conductors are connected to the charging section 20 and the developing section 3 so as to contact the low resistance layer 11 of the recording paper 10.
0 and is commonly connected to the magnetic roll 32a. Ro and RB are externally added resistors, and these resistors RG and R8 are connected in series. One end of the resistor RG is connected to the connection point D between the conductor 40 and the magnetic roll 32a, one end of the resistor RE is grounded, and the resistor Rc
A paper presser roll 31 is connected to a connection point G between and RE. R2 is the conductor 40 and the low resistance layer 1 1 of the recording paper 10
The contact resistance between the counter electrode 21 and the conductor 4, r2 is
W is the internal resistance of the recording paper 10 between the contact points between 0 and the low resistance layer 11 of the recording paper 10, and W is the internal resistance between the contact points of the conductor 40 and the paper pressing roll 31 and the recording paper 10. Note that X is the connection point between the internal resistance r2 and the contact resistance R2, and C is the connection point between the internal resistance and the contact resistance R3. In such a configuration, in order to prevent background smearing in the developing section 3, the resistors RG and RE are set so as to cancel out the developing bias voltage generated in the developing space.

That is, first, in order to reduce the potential difference between X and G, R, + and R8 are made large, and the combined resistance between
R20Rc) (r30R3)/{(ne+R3)10(R2
10Rc)}. In order to make the potential difference between C and D zero, the resistances R2, Ro, r3, and R between X and G are
Set the relationship 3 so that it satisfies. According to experiments, by setting the resistor R to 100 megohms and the resistor RG to 20 kilohms, the above-mentioned striped background stains were hardly observed and recording quality sufficient for practical use was obtained. Fourth
The figures are diagrams showing other embodiments of the present invention, in which a is an explanatory diagram of the configuration and b is an equivalent circuit diagram of a.

Note that, like FIG. 3, parts equivalent to those in FIG. 1 are given the same reference numerals.

In FIG. 4, 40 is a conductor similar to that in FIG. 3, which is arranged so as to be in contact with the low resistance layer 11 of the recording paper 10, and is commonly connected to the magnetic roll 32a. Rx
, RB are external additional resistors, one end of the resistor Rx is connected to the connection point D between the conductor 40 and the magnetic roll 32a, the other end is grounded, and one end of the resistor RB is connected to the paper pressing roll 31. There is. In such a configuration, the developing bias voltage Vc-D generated in the developing space is as follows.

Therefore, by setting the resistors RB and Rx so that R2(R30R8)=r3·RX, the bias voltage can be canceled and background smear can be prevented.

According to experiments, by setting the resistance Rx to 10 megohms and the resistance RB to 3 megohms, it was possible to obtain a record free from background stains. FIG. 5 is also a diagram showing another embodiment of the present invention, in which a is an explanatory diagram of the configuration and b is an equivalent circuit diagram of a.

Note that, like FIGS. 3 and 4, parts equivalent to those in FIG. 1 are given the same reference numerals. In FIG. 5, the counter electrode 21
is always grounded, a voltage of a predetermined polarity is applied to the discharge electrode 22, and an electrostatic latent image of a predetermined gutter type is formed in accordance with the polarity of the voltage applied to the discharge electrode 22. Even in such a configuration, the background smear as described above occurs due to current flowing from the discharge electrode 22 through the high resistance layer 12 of the recording paper 10 to the low resistance layer 11. This background smudge is proportional to the number of discharge electrodes 22 to which a voltage is simultaneously applied, and is also proportional to the size of the recording dot.
In order to prevent such scumming, a conductor 40 similar to that shown in FIGS. 3 and 4 is placed in contact with the low resistance layer 11 of the recording paper 10. This conductor 40 is a magnetic roll 32a
Further, this common connection point D is grounded via an external additional resistor Rx. Note that R4 is the contact resistance between the discharge electrode 22 and the high resistance layer 12 of the recording paper 10. Further, the paper pressing roll 31 is directly grounded. Then, the resistance Rx is expressed as RX = student
(4) By setting r3, the voltage between C and D becomes equal, and it is possible to prevent the occurrence of scumming.

Note that in these Examples, examples of dry development have been described, but similar effects can be obtained in the case of wet development.

As explained above, according to the present invention, a conductor grounded via an externally added resistor is brought into contact with the low resistance layer of the recording paper to shunt the current inside the recording paper, and a voltage is generated by this current and the externally added resistor. Since the development bias voltage caused by the high voltage applied to the charging part is canceled out by the drop, an external power supply is not required, and a two-color electrostatic recording device with excellent recording quality can be realized with an extremely simple circuit configuration. , the practical effect is great.

[Brief explanation of drawings]

1 and 2 are configuration explanatory diagrams showing an example of a conventional two-color electrostatic recording device, FIG. 3 is a configuration explanatory diagram showing an embodiment of the present invention, and FIGS. 4 and 5 are configuration explanatory diagrams showing an example of a conventional two-color electrostatic recording device. It is a side construction explanatory diagram showing another example. 10...Recording paper, 11...Low resistance layer,
12... High resistance layer, 20... Charged part,
21... Counter electrode, 22... Discharge electrode, 30...
...Development section, 31...Paper presser roll, 32.
...Magnetic brush, 40...Conductor, RG, R
E, Rx, RB... External additional resistance. Multi figure Younger brother Z figure Hair 3 figure Younger brother 4 figure Elephant Ta figure

Claims (1)

[Claims] 1 A recording paper with a low resistance layer formed on one side and a high resistance layer on the other side, and electrostatic latent images of positive polarity and negative polarity are formed on the recording paper by the potential difference between the discharge electrode and the counter electrode. The recording paper is equipped with a charging section for forming the electrostatic latent images, and a developing section for making the electrostatic latent images visible by attaching a developer containing positively and negatively charged toners of different colors to the recording paper on which these electrostatic latent images have been formed. In a two-color electrostatic recording device, a conductor that is grounded via an externally added resistor is arranged between the charging section and the developing section so as to be in contact with the low resistance layer of the recording paper. The two-color electrostatic charger is characterized in that the current inside the recording paper is shunted, and the developing bias voltage generated between the recording paper and the developing section is canceled by this current and a voltage drop caused by the external additional resistor. Recording device.