JPS6157353A - Electrostatic recording apparatus - Google Patents

Abstract

PURPOSE:To form a synthetic image such as a multicolor image, by providing a plurality of recording heads and applying signal voltage to the respective electrodes of said recording heads from a common image signal voltage source. CONSTITUTION:Each of recording head 1a, 1b, 1c has 16 drive electrodes and 210 signal electrodes and the signal electrodes of each head are respectively connected to 210 common signal sources in parallel. Recording medii 2a, 2b, 2c are respectively formed into a drum shape and images are formed while said recording medii are rotated to the direction shown by the arrow. Then, the timing of the driving of the recording heads 1a, 1b, 1c and the operation of the signal electrodes is taken to form a synthetic image wherein the images recorded by the heads are not overlapped and does not receive positional shift. The electrostatic image formed to the recording medium 2a by the recording head 1a is developed by toner when opposed to a developing device. Other images are developed in the same way. Color toner images are transferred to transfer paper 16 in a superposed state by transfer corona discharge devices 15a-15c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic recording device that forms an electrostatic image on an electrostatic recording medium using ions flying in response to an image signal.

[Background technology]

An electrostatic recording device that uses a recording head to fly ions in response to an image signal and forms an electrostatic image on a recording medium using the ions is disclosed in Japanese Patent Laid-Open Nos. 49-98735, 54-3533, and 54-78134. Disclosed in the official gazette.

As an example, a recording head based on the ion generation principle of the recording head disclosed in Japanese Patent Laid-Open No. 54-78134 will be schematically explained with reference to FIGS. 5 and 6.

Fig. 5 is a top view of the recording head, and Fig. 6 is a cross section along A-A, showing the main parts of the recording medium and drive circuit. A recording medium 2 on which an electrostatic image is formed are placed facing each other. The recording head 1 has band-shaped drive electrodes 3.1 to 34 on the upper surface of the insulating layer 4, and band-shaped signal electrodes 51, 5□, .
is placed. Insulating spacers 6 and screen electrodes 8 are arranged on the lower surfaces of the signal electrodes 51, 52, . . . . Signal electrodes 51, 5, .・An open lower part is provided in the insulating spacer 6 and the screen electrode 8, which serves as a flow path for ions. The electrostatic recording medium 2 has a structure in which a conductive layer 10 is covered with a dielectric layer 11. Between the drive electrodes 3 to 34 of the recording head 1 and the screen electrode 8, there is an AC power supply EAC as an alternating voltage power supply (each AC power supply EAC connected to the drive electrodes 3 to 33 is not shown), and the screen electrode 8. A DC power source Eoc as a screen voltage power source is connected between the recording medium 2 and the conductive layer 10 of the recording medium 2. Further, the signal electrodes 5, 5□-... are connected to an image signal source V. Note that the AC power source may be connected between the drive electrode and the signal electrode.

When an AC voltage is applied to the drive electrode 31 from the AC power source EAC, positive and negative ions are generated alternately in the area facing the opening 7 of the signal electrode. Since a negative voltage is applied to the screen electrode 8 from the DC power source Eoc, the electrostatic recording medium 2
Negative ions are selected as ions that can fly up to (earth potential), and positive ions are discharged between the screen electrode 8 and do not contribute to electrostatic recording. When a signal from H'' is applied to the signal electrode 52 and the potential of the signal electrode 5□ is higher than the potential of the screen electrode 8, negative ions are discharged between the signal electrode 52 and the 0 image. When a signal of "Yes" is applied to the signal electrode 5z from the signal source V and the potential of the signal electrode 52 is lower than the potential of the screen electrode 8, negative ions are attracted to the ground potential of the conductor 510 and the dielectric The layer 11 is charged. That is, the recording medium 2 is negatively charged by the L'' signal from the image signal source V. AC voltage is sequentially applied to the drive electrodes 3I to 34 for a certain period of time and switched, and each pixel is recorded correspondingly to the signal electrodes 51 and 52. Depending on whether or not the image signal is selected and applied, the recording medium 2 moves in the direction of the arrow and the secondary image signal is applied.

The original electrostatic image is formed. This electrostatic image (negative) is.

Developing is performed using regular toner supplied from a developing device (not shown in this figure).

This electrostatic image recording method is capable of relatively high-speed operation;
Since matrix driving is performed using a combination of drive electrodes and signal electrodes, the number of drive elements can be reduced. Further, since the recording head is small, it is easily possible to use a plurality of recording heads to perform multicolor printing.

Therefore, an electrostatic recording device equipped with such a recording head that can form a composite image such as a multicolor image is desired.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above, and an object thereof is to provide an electrostatic recording device that can form a composite image such as a multicolor image with a simple configuration.

[Means for solving problems]

In order to solve the above problems, the electrostatic recording device of the present invention includes:
A method is adopted in which a plurality of recording heads are provided and a signal voltage is applied from a common image signal voltage source to each signal electrode of the plurality of recording heads.

[Effect]

By adopting the above method, when a composite image such as a multicolor image is formed using multiple recording heads, the signal voltage is applied from a common signal source, so the number of driving elements used for the signal source can be reduced. It can be suppressed.

〔Example〕

FIG. 1 shows an electrostatic recording apparatus to which the present invention is applied, which can print in multiple colors. Three electrostatic recording media 2a/2
b*2c, recording heads 1a, 1b, and IC, respectively.
and a developing device 13as 13b1113C are arranged.

The recording heads 1a and 1belc have the same shape as the recording heads already explained in FIGS. 5 and 6. Specifically, each recording head La * lb / lc has 18 drive electrodes and 210 signal electrodes, and records at a density of 16 pixels per l over the entire length (in the depth direction on the paper) of 210 + am width. be able to. The 210 signal electrodes of the recording head 1a, the 210 signal electrodes of the recording head 1b, and the 210 signal electrodes of the recording head IC each have a common 21
0 signal source in parallel. Therefore, when connecting each recording head to a separate signal source, the number of driving elements is 630 (f
In this example, the number of drive elements is 210 (l!I
will be sufficient. An AC voltage having a peak voltage of 1.9 KV at 800 KHz is applied to each of the 18 drive electrodes while being sequentially switched at a rate of about 13 g See. Then, the image signal voltage is applied to the signal electrode corresponding to the drive electrode to which the AC voltage is applied.

The recording media 2a, 2b-2c each have a drum-like configuration as shown in FIG.
The electrostatic image formed on the recording medium 2a in step a is transferred to the developing device 13a.
The toner is developed when facing the object. The electrostatic image formed by the recording head 1b is developed with toner of a different color in a developer 13b, and the electrostatic image formed by the recording head IC is further developed with toner of a different color in a developer 13c. . The transfer paper 16 is conveyed by a mesh-like conveyor belt 20, and the toner images of each color on the recording media 2a, 2b, and zC are superimposed and transferred onto the recording media 2a, 2b, and zC by transfer corona dischargers 15a, 15b, and 15c. Recording by the heads 1a, 1b, and 1c is started at different timings so that the leading edges of the images coincide with each other in synchronization with the feeding of the transfer paper.

The signal electrodes of the recording head 1a, the signal electrodes of the recording head 1b, and the signal electrodes of the recording head IC are each connected in parallel to a common signal source, so the operation timing with the signal electrodes is determined as follows. By rad la @ to each record
In this embodiment, there are two main methods for determining the timing.

The time chart of the ml method is shown in FIG. First, 16. of the record 1a. wooden drive electrode 3
A driving AC voltage is applied to aI・3a2...113a16 one after another, and then the drive electrodes 3bl 13b,*・of the head ib are
・Apply driving AC voltage to 3b and 6 in the same way. And drive electrode 3C1◆3c2 of head IC ・Φ・3C1
Apply the driving AC voltage to the recording head 6 in the same way, then return to the recording head la and repeat the same process.In this way, when any one of the recording heads 1a, 1b, and IC is being driven, the common An image signal voltage is applied from a signal source.

FIG. 3 shows a time chart of the second method for determining the operation timing. First, a drive AC voltage is applied to the drive electrode 3al of the recording head 1a, then to the electrode 3b1 of the head tb, then to the electrode 3cI of the head lc, and then to the drive electrode 3a2 of the recording head 1a. In the following order → Electrode 3b2 → Electrode 3C2 → Electrode 3a3 → Electrode 3b3 →
・A drive AC voltage is applied in the order of →electrode 3b, 6→electrode 3c16. In this way, the recording heads 1a*1b/l
When any one of c is being driven, an image signal voltage is applied from a common signal source.

The state in which electrostatic image dots are formed on a recording medium by the above two methods will be explained with reference to FIG. Now record the drive electrode 31 and signal electrode 51 of Rad 1 (Fig.
It is assumed that a dot 22 is formed on the recording medium z by the method shown in FIG. Since the recording medium 2 is moving in the direction of the arrow, at the time when the dot 222 is formed, the dot 22. has moved to the position of dot 22□' (indicated by a dotted line). The distance xi between the dots 22 and 222 in the image advancing direction is the distance between the drive electrodes. The rMI interval between the dots 222 and 22, / in the image advancing direction must be an integral multiple of one pixel pitch.

When the pixel pitch is d, this interval is nXd.

How many times it should be multiplied is decided as appropriate depending on the design of the recording head. Making this wider makes it easier to manufacture the drive electrodes and reduces the risk of short circuits between electrodes, but it complicates signal processing because the image data to be processed spans a wide range.

If the cycle until the drive electrode 3I is driven again next time is T, and the moving speed of the recording medium is V, then vx''r=d.1
If the number of drive electrodes in one recording head is N, and the number of recording heads to which signal electrodes are connected in common is M, then dot 22
In the case of the first driving method (see FIG. 2), the interval α between 1 and 22,' becomes v XT /M X N. nd
From =Q+a, the distance between the drive electrodes is (n-1/MXN)
Become Xd.

However, as shown in Figure 1, this is a case where voltage is applied to the drive electrode from the leading edge in the recording medium's traveling direction (downstream in terms of device movement) to the rear edge, and the order of voltage application is reversed. The distance measurement when performed from the rear end side to the front end side is (n+
1/MXN)Xd.

In the case of the second driving method (see figure m3), the distance α between dots 22z and 22+ (7) is v X M X T / M
X N It becomes. The distance between the drive electrodes is (n-1/N)
When the order of application is from the rear end to the front end, the interval intersection may be (n+l/N)Xd.

As can be seen from the above explanation, even if the spacing (nd) between dots formed by adjacent drive electrodes is the same, the relationship between the order of voltage application to the drive electrodes and the direction of movement of the recording medium , it is necessary to change the distance between the drive electrodes. In order to increase the recording density and keep n small, it is possible to increase the driving speed by applying voltage to the drive electrodes from the front end in the recording medium's traveling direction (downstream side in terms of device movement) to the rear end. It is now possible to widen the spacing between electrodes,
This facilitates manufacturing and prevents problems of dielectric breakdown. This applies not only to the case of having a plurality of print heads as explained so far, but also to the case of a single print head. In that case, it is sufficient to set M=1. The difference in drive direction disappears.

Recording media 2a and 2b0 recorded by such an operation
The electrostatic image on 2C is developed, transferred to transfer paper 16, and fixed by a fixing device (not shown) to obtain a multicolor hard copy. The recording media 2a, 2b, and 2C are cleaned of residual toner by respective cleaning devices 17a to 17b* 17c, and their potentials are made uniform by static eliminators 18a, Φ18b, and 18c, and used repeatedly.

〔effect〕

As explained above, according to the present invention, since a plurality of recording heads are provided and a signal voltage is applied to them by a common signal source, a composite image can be generated while suppressing the number of driving elements used for the signal source. can be formed. Therefore, it is possible to provide an electrostatic recording device that can record multicolor images with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an embodiment of an electrostatic recording device to which the present invention is applied, Figs. 2 and 3 are time charts explaining the operation of the drive electrode, and Fig. 4 shows recording intervals of electrostatic image dots. 5 is a top view of the recording head, and FIG. 6 is a top view of the recording head.
It is an A sectional view. 1#la#lb#IC is written t2 H/D, 2*2a・
2b-2C is an electrostatic recording medium; 3.・3□0-・Drive electrode, 5I Φ5z-Φ・ is a signal electrode, 8 is a screen electrode, 10 is a conductive layer, 11 is ? A conductor layer 13a* 13
bs 13c is a developing device, and 221, 221', and 222 are electrostatic image dots.

Claims (1)

[Claims] 1. Among the positive and negative ions generated by applying voltage alternately to the drive electrode, positive or negative ions are selected which should fly to the electrostatic recording medium by applying a positive or negative screen voltage between the screen electrode and the electrostatic recording medium. Alternatively, a recording head that selects negative ions and records an electrostatic image on an electrostatic recording medium controls the flight of the ions by applying an image signal voltage to a signal electrode provided on the flight path of the ions. What is claimed is: 1. An electrostatic recording device comprising: a plurality of recording heads; and a signal voltage is applied to each signal electrode of the plurality of recording heads from a common image signal voltage source.