JPS6329870B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-stylus electrostatic recording scanning system, and for example, to an electrostatic recording scanning system using a multi-stylus head in a recording apparatus such as a facsimile machine or a printer.

In general, solid-state scanning is the mainstream recording means for electrostatic recording devices in order to achieve faster recording speed and higher resolution. Solid-state scanning systems include a same-side control system and a back-side control system in which recording is controlled from the front or back side of electrostatic recording paper. Both of these types consist of a plurality of control electrodes and recording electrode needles. Then, high voltage pulses are selectively applied to these electrodes under electronic circuit control to main scan one line of electrostatic recording paper. At the same time, the recording paper is moved every predetermined distance, and each time a main scan is performed to obtain a charge image for one sheet of recording paper, and this is visualized to obtain a recorded image.

In the following explanation, an electrostatic recording method using same-plane control will be explained.

FIG. 1 is an external view of an electrostatic recording head using the same-plane control method, which is the background of this invention, FIG. 2 is a schematic cross-sectional view of electrostatic recording paper, and FIG. FIG. 4 is a diagram showing the matrix configuration of the head; FIG. 4 is a waveform diagram showing the voltages applied to the recording electrodes and control electrodes during recording;
The figure is an illustrative diagram showing the configuration of the electrostatic recording head surface and the distribution of recorded image density corresponding thereto.

First, referring to FIG. 1, an electrostatic recording head 1 is provided with recording electrode needles 2 and a plurality of control electrodes 3 arranged in one row. Then, the recording layer of the electrostatic recording paper 4 is pressed against the electrode surface of the electrostatic recording head 1 to obtain a charge image.

As shown in FIG. 2, the electrostatic recording paper 4 includes a recording layer 5 that holds a charge image and a base paper resistance layer 6 that is made of a base paper that has conductivity. Generally, the resistance value of the base paper resistance layer 6 is defined by the water content.

Referring to FIG. 3, the electrostatic recording head 1 has a matrix configuration, and the recording electrode needles 2 are divided into groups A and B, and each recording electrode needle group is divided into two control electrodes 3, 3. It is placed close to each other. Recording electrode needle groups A and B are driven by two drive circuits 7 and 8. The drive circuit groups 7 and 8 apply recording electrode voltages to the recording electrode groups A and B in accordance with the recording signal. Further, a control voltage is applied to each control electrode 3 from a drive circuit 9 . Here, block B _K is connected to control electrode CP _K and CP _K+1
This is a group of recording electrodes sandwiched between.

When forming a charge image on the electrostatic recording paper 4, for each recording electrode needle group, each recording electrode needle 2 of block B _K and control electrodes CP _K and CP _K+1 are connected as shown in FIG. This is done by simultaneously applying a recording electrode voltage -V _N (approximately -300V) and a control electrode voltage +V _C (approximately +300V) for a predetermined time _tr . As a result, the charge image is visualized with toner, and this is fixed to obtain a recorded image.

In the conventional antistatic recording apparatus, a recorded image is obtained as described above, but the image quality is greatly influenced by the atmosphere, and especially in low humidity, density unevenness occurs in each block. The results of observing this density unevenness are shown by the solid line in FIG. 5b. FIG. 5a is a schematic enlarged view of the electrostatic recording head surface, and FIG. 5b shows the optical reflection density of the electrostatically recorded image corresponding to each block _BK . In Figure 5b, solid line 1
0, 11, and 12 show the respective recording density distributions in different atmospheres, each at 20°C and 65%.
This is an example of image density at RH, 50°C%RH, and 30°C%RH.

This decrease in recorded image density and density unevenness are caused by changes in the base paper resistance value of the electrostatic recording paper 4 as the temperature and humidity of the atmosphere change, and as the humidity decreases, the resistance increases and the density unevenness becomes noticeable. It's summery. This is due to the recording layer 5 of the electrostatic recording paper 4 due to the recording electrode needle 2.
This is due to the charging characteristics of the capacitor capacity. That is,
As can be easily inferred from the configuration of _the electrostatic recording head surface _{in FIG .} This is because the current flowing through the base paper resistance layer 6 to the block _BK of the electrode needle group and charging the recording layer 5 is larger at the ends of the block _BK than at the center.
In other words, when recording with all the recording electrode needles 2 of block B _K , the block resistance is higher than the base paper resistance value from the control electrodes CP _K and CP _K+1 to the center of block B _K.
This means that the resistance value up to the end of _BK is smaller. This can also be easily derived by calculating the resistance value. After all, in electrostatic recording, there is a charging characteristic of the recording layer capacity as described above, and if the base paper resistance value of electrostatic recording paper is small, the block
The charging time is sufficiently short even for the main parts of _BK ,
The charging potential of the recording layer 5 by each recording electrode needle 2 becomes uniform. However, as the resistance value of the base paper increases, the charging time constant of the recording layer increases, gradually causing unevenness in the amount of charged charge, which appears as density unevenness.

In order to reduce this density unevenness, a method has been proposed in which the recording timings of adjacent recording electrode needles in a recording electrode group that are to record a plurality of dots at the same time are made different from each other.

FIG. 6 is a waveform diagram showing the relationship between control voltage and recording voltage in a conventional recording method for removing density unevenness, FIG. 7 is a schematic equivalent circuit diagram of electrostatic recording paper, and FIG. FIG. 3 is a waveform diagram showing the base paper potential of the base paper resistance layer of an electrostatic recording paper to which a control electrode voltage is applied.

First, in FIG. 6, waveform 13 shows the control electrode voltage +V _C when recording with block B _K of the recording electrode needle group, and waveform 14 shows, for example, the control electrode voltage +V C when recording with block B _K of the recording electrode needle group.
The waveform 15 is the recording electrode voltage _-VN applied to the recording electrode needle 2 at the odd-numbered position, and the waveform 15 is the recording electrode voltage at the even-numbered position. and,
As shown in FIG. 6, when recording with block B _K , control voltage +V _C is applied to control electrodes CP _K and CP _K+1.
The timings of the recording electrode voltages to be applied to the odd-numbered recording electrodes and the even-numbered recording electrodes are made different while the voltage is being applied. When recording is performed in this manner in each block, in addition to uneven density due to the high resistance value of the base paper of the electrostatic recording paper 4, the base paper resistance layer 6 to which the control electrode voltage is applied
Concentration unevenness appears due to potential attenuation.

In other words, the recording density by the odd-numbered recording electrode needles 2 to which the recording electrode voltage was applied first is higher than the recording density by the even-numbered recording electrode needles 2 to which recording is performed later, and every other recording electrode needle 2 This results in a difference in concentration. The reason for this will be explained with reference to FIGS. 7 and 8. In FIG. 7, the electrostatic recording paper 4 has a recording layer capacitance C _t directly below each control electrode 3.
, the base paper resistance r between the control electrode 3 and the control electrode 3
The resistance R _g from the base paper resistance layer directly below to the ground electrode
, and generally r≫R _g holds from the configuration of the device. For example, when recording with block B _K , control electrode voltage +V _C is set to control electrode CP _K and
When applied to CP _K+1 , the control voltage +V _C charges the recording layer capacitance C _t located at the adjacent control electrodes CP _K-1 and CP _K+2 via the resistor r, and the block to be recorded B _K It is estimated that the base paper potential 16 corresponding to point P of the portion has a differential waveform with a time constant r (≈1/2 C _t r). The base paper potential 16 at point P is shown by the broken line in FIG. As is clear from this Figure 8, the control voltage +
When the time t ₀ ends after the application of V _C , the base paper potential 16 decreases by ΔV _C , so the image density due to the recording electrode voltage −V _N applied earlier is higher than the recording electrode voltage −V applied later. The image density will inevitably be lower than the image density due to _N. Therefore, in order to prevent a difference in recording density before and after the recording, as shown by the broken line in FIG.
It is necessary to increase the control electrode voltage or the recording electrode voltage by +ΔV _C or -ΔV _N. Moreover, since the decay time constant τ of the base paper potential 16 in FIG. 8 changes with the change in the base paper resistance value r, the change in the base paper resistance value r _is detected _and Values need to be adjusted. This inevitably results in a disadvantage that the recording device becomes complicated.

Furthermore, the image density when a recorded image is obtained by compensating the control voltage +ΔV _C or the recording electrode voltage −ΔV _N as described above is shown by solid lines 9 and 10 in FIG. 5b.
The results obtained under similar environmental conditions are shown by broken lines 16 and 17 in FIG. 5b. As is clear from FIG. 5b, although the image density unevenness was reduced by the conventional method, it was found that the density unevenness was still noticeable corresponding to each recording electrode needle group.

Therefore, it is an object of the present invention to provide a multi-stylus electrostatic recording scanning system that can further reduce the above-mentioned recording density unevenness and obtain high-quality recorded images regardless of the environment.

In summary, the present invention includes a multi-stylus electrostatic recording head in which a plurality of control electrodes and recording electrode groups correspondingly divided into a plurality of groups are arranged, and each recording electrode group at a predetermined position is charged with a charge. In an electrostatic recording device that forms an image, m (≧4) groups (g ₁ , g ₂ ... g _n ) of adjacent recording electrode needles are arranged in each recording electrode group.
, select multiple groups of non-adjacent groups G _n , and further divide them into n (≧2) groups G (G ₁ ,
G ₂ ...G _o ) is formed, a charge image is formed in any one group G _o in each recording electrode group in the first stage recording scan, and a recording main scan is constructed from the n stage recording scan. , the amount of charge charged by each recording electrode needle is approximately uniform.

The above objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

FIG. 9 is an illustrative diagram showing the configuration of an electrostatic recording head surface according to an embodiment of the present invention, and FIG. 10 is a diagram similarly showing an example of recorded image density.

First, referring to FIG. 9, in one embodiment of the present invention, two recording electrode needles included in each recording electrode needle group are arranged so as to span one control electrode.
Each of the four adjacent groups g ₁ , g ₂ ,
It is divided into g ₃ and g ₄ . These groups g ₁ , g ₂ ,
Among g ₃ and g ₄ , non-adjacent groups, i.e. groups g ₁ and g ₃ and g ₂ and g ₄ are grouped respectively.
It constitutes G ₁ and G ₂ . For example, when recording in block B _K of the recording electrode needle group, control voltage +V C is applied to control electrodes CP _K and CP _K+1 , and at the same time, the control voltage +V _C is applied to the recording electrode needle group _G1 or _G2 . Of any group of groups, each group g ₁ and g ₃ or g ₂
and g ₄ , the recording electrode voltage − depending on the recording signal
Apply _VN .

When actually recording and scanning, it is performed in two stages. That is, in the first stage recording scan, each control electrode CP _K-1 , CP _K , CP _K+1 , CP _K+2 is energized,
Groups included in group G ₁ of block B _K-1
Groups g ₁ and g ₃ included in group G1 of block B _{K and} g _{1 and g 3 included in} group G1 of block B _K+1 are selected according to the recording signal. The first stage of recording is performed using a recording electrode needle. Next, each control electrode CP _K-1 , CP _K , CP _K+1 ,
When CP _K+2 is energized, groups g ₂ and g ₄ included in group G2 of block B _K-1 and groups g 2 and _{g 4 included} in group G1 of block B _K and block B _K+1 are connected.
Groups g ₂ and g ₄ included in group G 2 are selected, and recording is performed using recording electrodes selected according to recording signals. An example of the recorded image density according to this embodiment is shown by a solid line 19 in FIG. This solid line 1
The concentration distribution shown in FIG. 9 was carried out under the same environmental conditions as the concentration distribution shown by the solid line 12 in FIG. 5b. As is clear from FIG. 10, the density unevenness is subdivided and evened out compared to the conventional recording method. Even when the recorded image is actually observed, the density unevenness is less noticeable and the quality is higher than in the conventional recorded image.

Next, the effects obtained in the embodiments of this invention will be explained. First, by halving the number of recording electrode needles 2 to be recorded in the first scan and reducing the recording layer capacity to obtain a charge image, the charging time of this recording layer is shortened, and the electrostatic An effect similar to that obtained by reducing the resistance value of the recording paper base paper resistance layer 6 by approximately half can be obtained. Moreover, as a result of recording for each second group and concentrating the charging current,
From g ₁ to g ₄ , it became possible to make the amount of charge almost uniform between the center and the ends. Furthermore, as a result of recording groups G ₁ and G ₂ in the same block independently, unlike the conventional recording method shown in FIG. 6, the control voltage +ΔV _C required in the conventional method is
Alternatively, it has become possible to remove density unevenness without applying a compensation voltage equal to the recording electrode voltage -ΔV _C.

In this way, as the number of the first groups and the number of second groups in the recording electrode groups described above are increased, the recording density unevenness is subdivided, and moreover, the unevenness of the recording density is subdivided, and moreover, the unevenness of the recording density becomes smaller in the central part and the edge part of each group. The amount of charge will be made uniform. As a result of the experiment, it was possible to obtain a recorded image of sufficiently high quality and without density unevenness in the above-described embodiment.

In the above-described embodiments, the present invention is applied to an electrostatic recording head using the same-side control method, but it goes without saying that the present invention is not limited to this and can also be applied to a back-side control method.

As described above, according to the present invention, among recording electrode needles included in each group in which a large number of recording electrode needles are divided into a plurality of groups so as to span adjacent control electrodes, a plurality of adjacent recording electrode needles are Divide each book into m (≧4) groups (g ₁ , g ₂ ...gn), select multiple non-adjacent groups gm, and further divide n (≧2) groups G (G ₁ , g 2 ...gn).
G ₂ ...Gn), energizes each control electrode in the first stage recording scan, and also energizes any one group Gn to form a charge image, and records by n stage recording scan. Since the main scan is performed, the charging time of the recording layer capacitor in one scan can be shortened, and the amount of charge charged by each recording electrode needle can be made almost uniform. Therefore, it is possible to subdivide recording density unevenness that appears as a result of changes in environmental humidity and to flatten it. This makes it possible to obtain high-quality recorded images regardless of environmental changes.

[Brief explanation of the drawing]

FIG. 1 is an external view of a coplanar control type electrostatic recording head, which is the background of the present invention. FIG. 2 is also a schematic cross-sectional view of the electrostatic recording paper. FIG. 3 is a diagram showing a matrix configuration of an electrostatic recording head. FIG. 4 is a waveform diagram showing voltages applied to the recording electrode and control electrode during recording. Fifth
The figure is an illustrative diagram showing the configuration of the electrostatic recording head surface and the distribution of recorded image density corresponding thereto. FIG. 6 is a waveform diagram showing the relationship between control voltage and recording voltage in a conventional recording method for removing density unevenness. FIG. 7 is a schematic equivalent circuit diagram of electrostatic recording paper. FIG. 8 is a waveform diagram showing the base paper potential of the base paper resistance layer of the electrostatic recording paper to which the control electrode voltage is applied. FIG. 9 is an illustrative view of an electrostatic recording head surface for explaining one embodiment of the present invention. FIG. 10 is a diagram showing the density distribution of a recorded image corresponding to the electrostatic recording head. In the figure, 1 is an electrostatic recording head, 2 is a recording electrode needle, 3 is a control electrode, 4 is electrostatic recording paper, g ₁ to
g ₄ indicates the first group, and G ₁ and G ₂ indicate the second group.

Claims (1)

[Scope of Claims] 1. A multi-stylus electrostatic recording head including a plurality of control electrodes, in which a large number of recording electrode needle groups are grouped and arranged so as to span adjacent control electrodes, and recording electrode needle groups at predetermined positions. In the multi-stylus electrostatic recording scanning method that forms a charge image on electrostatic recording paper every time, the recording electrode needles included in each group are:
Divide the adjacent recording electrode needles into m (≧4) groups (g ₁ , g ₂ ...gn), select multiple non-adjacent groups gm, and then divide them into n (≧2) groups. constitute a group G (G ₁ , G ₂ . . . Gn), and in the first stage recording scan, the plurality of control electrodes are energized and one of the groups Gn
The multi-stylus static is characterized in that a charge image is formed by energizing the stylus, the main scan of recording is made up of n-stage recording scans, and the amount of charge charged by each recording electrode needle is made almost uniform. Electrographic scanning method.