JPH0160984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrostatic recording apparatus, and more particularly to an electrostatic recording control method for controlling recording operations by an electrostatic recording head.

Conventional Structure and Problems Therewith FIG. 1 is a schematic diagram schematically showing a typical electrode arrangement on an electrostatic recording head. In the figure, 1 is a recording needle (needle electrode), and 2 is a control electrode. By selectively applying a pulse voltage to the control electrode 2, a specific recording needle 1 is selected, and the selected recording needle 1 is
By applying an image signal to the recording paper, an electrostatic latent image of the image can be recorded on the recording paper.

In an electrostatic recording device using such an electrostatic recording head, in order to reduce the number of recording stylus drive circuits, the recording stylus is divided into blocks with a predetermined number of consecutive recording stylus blocks, and each block is divided into two blocks every other block. An electrostatic recording control method is adopted in which the blocks are divided into groups and all blocks in the same group are driven at once by a common drive circuit.

FIG. 2 is a circuit diagram of such a conventional electrostatic recording control system. In the same figure, S ₁ , S ₂ ,
S ₃ , . . . , S _2o+1 each indicate a pair of opposing control electrodes 2 in FIG. These control electrodes S ₁ to _{S 2o+1} are selectively driven by a control electrode drive circuit 3.

The recording needle 1 moves blocks A ₁ , A ₂ , ..., A _o , B ₁ , B ₂ , ... every predetermined number (every 4 in FIG. 2).
..., B _o , blocks A ₁ to _{A o} are grouped into group A, and blocks B ₁ to _{B o} are grouped into group B. The corresponding recording needles of each block in the group are connected in parallel and connected to the recording needle drive circuit 4a, and similarly, the corresponding recording needles of each block in group B are also connected in parallel and connected to the recording needle drive circuit 4b. Connected.

FIGS. 3 and 4 are explanatory diagrams of block selection control in the conventional electrostatic recording control system.

In the case of FIG. ₃ , the control electrode drive circuit 3
By supplying a pulse voltage to the control electrodes S ₁ and S ₂ from the recording needle drive circuit 4a to select block A ₁ , and simultaneously supplying image signals to all blocks A ₁ to A _o of group A at once. , perform recording with the recording needle of block _A1 . At the next time t ₂ , the control electrode S ₂ ,
Select block B ₁ by supplying pulse voltage to S ₃ ,
The recording needle drive circuit 4b supplies recording signals to all blocks _B1 to _B0 of group B, and recording is performed by block _B1 . Similarly, blocks A ₂ , B ₂ ,
Blocks are selected in the order of A ₃ , B ₃ , . . . , A _o , B _o and one line is recorded.

In the case of Fig. 4, all blocks A ₁ to A _o of block A are sequentially selected one by one during the period from time t ₁ to time _{t o} to perform the recording operation, and from time t _{o +1} to time t _{2 o} . During the period, all blocks B ₁ to B _o of group B are sequentially selected one by one and a recording operation is performed.

Next, the drawbacks of the block selection control system as shown in FIG. 3 will be explained with reference to FIGS. 5 and 6.

FIG. 5 is a cross-sectional view of the electrostatic recording paper, where 5 is a dielectric layer and 6 is a low resistance layer. Figure 6a is the control electrode
Waveform diagram of pulse voltage applied to S _2k , Figure 6b
is a waveform diagram showing potential changes in a portion of the low resistance layer 6 located directly below the control electrode S _2k .

When selecting block Ak (time t _2k-1 in Figure 3),
When the first pulse voltage V ₁ is applied to the control electrode S _2k , the potential of the low resistance layer 6 rapidly rises to V ₁ , and then changes to the time constant of the recording circuit system including the electrostatic recording paper. Therefore, when the pulse voltage _V1 is turned off, the potential is reversed to _-V2 , and then gradually increases toward the 0 volt potential according to the above-mentioned time constant. When the second pulse voltage V ₂ is applied to the control electrode S _2k to select the block Bk at the time when the same potential rises to -V ₃ , the potential of the low resistance layer 6 becomes V ₄ (=V ₁ -V ₃ ). In other words, 1
Compared to the time when the first pulse voltage V ₁ is applied, the potential induced in the low resistance layer 6 directly under the control electrode S _2k shifts to the negative side when the second pulse voltage V ₂ is applied. On the other hand, at the same time as this second pulse voltage V ₂ is applied, a pulse voltage is also applied to the control electrode S _2k+1 facing the block Bk, and the low resistance layer 6 immediately below it is applied.
The potential of rises to V ₁ . Therefore, among the recording needles belonging to block Bk, those facing control electrode S _2k and those facing control electrode S _2k+1 ,
The difference in potential between the electrostatic recording paper and the recording paper causes variations in recording density, resulting in striped recording unevenness. If the time interval between the first and second pulse voltages applied to the same control electrode is made sufficiently long, such recording unevenness can be prevented from occurring, but this will significantly reduce the recording speed.

As described above, the method of selecting blocks as shown in FIG. 3 has the drawbacks that recording unevenness tends to occur and the recording speed is limited to a low level.

Although the block selection method shown in FIG. 4 can prevent uneven recording because adjacent blocks are not selected consecutively, it has the following drawbacks in terms of the quality of recorded images.

FIG. 7 is a diagram showing the positional relationship of pixels recorded by the recording needles of block Ak and blocks Bk _-1 and Bk on both sides thereof. Circles indicate individual pixels.

When recording is performed while moving the electrostatic recording paper, the pixel recording position by block Bk _-1 on the left is △ _dL compared to the pixel recording position by block Ak.
The pixel recording position according to the block Bk on the right is shifted by _ΔdR . Blocks Bk _-1 and Bk are the (n-1)th block and nth block, respectively, counting from block Ak, so if the electrostatic recording paper is moved by the pixel diameter d within the recording time of one line,
The deviation rates Δd _L /d and Δd _R /d are as follows: Δd _L /d=(n-1)/2n Δd _R /d=1/2. That is, the recording position shifts by approximately half a pixel between adjacent blocks. Moreover, as shown in the figure, the recording positions are shifted in a staggered manner in block units. For this reason, the recorded image becomes unnatural, and in particular, an image including a straight line in the scanning direction gives a strong visual sense, which is undesirable.

In addition to those mentioned above, there is "Electrostatic Recording Electronic Control Method" in Japanese Patent Application Laid-Open No. 55-4048. This means that once a block in one group is selected, a block in the other group that is not adjacent to that block is selected. This prevents recording rams and also reduces the deviation in recording position for most blocks. . However, if a pause time is not inserted within the scanning period, the recording position of some blocks will be significantly shifted, and block selection control is considerably more complicated than in the above two methods. The disadvantage is that it becomes complicated.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
It is an object of the present invention to provide an electrostatic recording control system capable of recording high-quality images with little recording unevenness at high speed without complicating block selection control.

Structure of the Invention The present invention is a method of continuously arranging a predetermined number of recording needles on an electrostatic recording head to produce 2n recording needles (n is an even number of 4 or more).
The 2n blocks are divided alternately in the order of their arrangement and belong to the first group and the second group, respectively, and the n blocks belonging to the first group are divided into two blocks.
Blocks arranged up to the n/2th block counting from one end are placed in the first subgroup,
The blocks arranged from n/2+1st to nth belong to the second subgroup, and after selecting one arbitrary block, the block is moved one block away without selecting an adjacent block. An electrostatic recording control device that selects and records blocks, which first selects the blocks belonging to the first subgroup in the order of their arrangement from one end to the n/2th block, and then selects the blocks belonging to the first subgroup in order of arrangement. Select all the blocks belonging to the second subgroup in the order of arrangement from one end, and finally select the blocks following the second subgroup from the n/2+1st to the nth in order of arrangement to perform the recording operation, The time interval from selecting an arbitrary block belonging to the selected block to selecting a block adjacent to this block is made to be one-fourth or less of the recording time of one line by the electrostatic recording head.

As will be described later, this condition of approximately 1/4 or less is determined from the permissible limit of pixel recording position deviation between adjacent blocks that must be satisfied in order not to impair the naturalness of the recorded image. If the selection time interval between blocks is further reduced, the quality of the recorded image will further improve.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 8 is a circuit diagram of an electrostatic recording control system according to an embodiment of the present invention, and FIG. 9 is an explanatory diagram of block selection control in the electrostatic recording control system. For convenience of explanation, it is assumed that the electrode arrangement and the number of electrodes of the electrostatic recording head are the same as in the prior art example, and parts equivalent to those in FIGS. 1 and 2 are represented by the same reference numerals.

In FIG _. 8, the recording needles 1 are divided into blocks of four each, and blocks A ₁ , A ₂ . . _. , An/ ₂ , .
n/2,...B _o is classified into group B. The recording needles of all blocks in group A were connected in parallel with each other and connected to the recording drive circuit 10a, and similarly, the recording needles in all blocks in group B were connected in parallel with each other. It is connected to the recording needle drive circuit 10b at the top. Control electrode 2 (S ₁ ,
S ₂ , ...S _2o+1 ) are connected to the control electrode drive circuit 11 . The control electrode drive circuit 11 selectively applies a pulse voltage to the control electrode 2 and performs block selection in the order shown in FIG. The recording needle drive circuits 10a and 10b apply the same image signal (for four pixels) to all blocks in the corresponding group in synchronization with block selection. This image signal is the one selected by the control electrode drive circuit 11.
Although electrostatic recording is performed using two blocks of recording needles, the recording principle is the same as the conventional one, so a description thereof will be omitted.

Among the blocks A ₁ -A _o in the group A, the first half blocks A ₁ -An/2 are classified into the subgroup SA ₁ , and the latter blocks An/2+1 - _{A o} are classified into the subgroup SA ₂ . Similarly, group B
is divided into subgroups SB ₁ and SB ₂ , and the block
Blocks B ₁ to Bn/2 are classified into subgroup SB ₁ , and blocks Bn/2+1 to _Bo are classified into subgroup SB ₂ , respectively.

Next, block selection control will be explained with reference to FIG.

In this embodiment, the recording time of one line (from time _t1 to time _t2o ) is a time interval T1 from time _t1 to time tn/2, a time interval _T2 from time tn/2+1 to time t0, _and a time interval T2 from time tn/ ₂₊₁ to time _{t0. +1} to time t3n/ ₂ , and time interval _T4 from time t3n/2+1 to time _t2o . and,
Time interval T ₁ is subgroup SA ₁ , time interval T ₂ is subgroup SB ₁ , time interval T ₃ is subgroup
SB ₂ and time interval T ₄ are respectively assigned to subgroup SA ₂ . Within each subgroup, during the time interval assigned to that subgroup,
Each block is sequentially selected according to the order of arrangement.

That is, in the time interval _T1 , block _A1 is selected at time _t1 , block _A2 at time _t2 , etc., and block An/2 at time tn/2, in this order. The same applies to the other subgroups SA ₂ , SB ₁ , and SB ₂ .

If we pay attention to block _A2 , its left neighbor block _B1 is selected as the (n/2-1)th block counting from block _A2 , and the right neighbor block B1 is selected as the (n/2-1)th block counting from block A2.
B ₂ is selected at the n/2 block. The total number of blocks is 2n, and these are selected at regular time intervals so as to go around within one line recording time. Therefore, if the electrostatic recording paper is moved by the pixel diameter d within one line recording time, the deviation rate of the pixel recording position between block A ₂ and blocks B ₁ and B ₂ is △
d _L /d, △d _R /d are △d _L /d=(n/2-1)/2n=1/4-1/2n △d _R /d=(n/2)/2n=1 /4.

The same is true for other blocks, and the deviation rate of pixel recording positions between adjacent blocks is 1/4 or less.

As a result of actually observing and examining recorded images, it was concluded that if the deviation rate is approximately 1/4 or less, the visual discomfort is tolerable. Furthermore, since adjacent blocks are not selected consecutively, uneven recording does not occur. As described above, according to the present embodiment, it is possible to record high-quality images at high speed without recording unevenness and without causing visual discomfort.

Further, block selection is performed by the control electrode drive circuit 11, and since the block selection order is extremely simple and regular as described above, the control electrode drive circuit 11 can have a simple configuration. moreover,
As a result, the recording needle drive circuits 10a, 10b
Control on the side is also simple, and the circuit does not become complicated.

Furthermore, the deviation rate of pixel recording positions between adjacent blocks is less than (1/4 to 1/2n), and images with natural image quality can be recorded. Furthermore, since adjacent blocks are not selected consecutively, uneven recording does not occur. The block selection order is also regular, and the control electrode drive circuit and recording needle drive circuit are not complicated.

In the explanation up to this point, we have used the deviation rate of pixel recording positions between adjacent blocks, but since the electrostatic recording paper is generally fed by the pixel diameter within one line recording time, this deviation rate is determined by the deviation rate when a certain block is selected. It is equal to the ratio of the time interval from when the block is selected until the adjacent block is selected to the recording time of one line. Therefore,
The selection interval of adjacent blocks is approximately 1/4 of one line recording.
If the following is achieved, the deviation rate of pixel recording positions between adjacent blocks will generally be approximately 1/4 or less,
It is possible to obtain recorded images of natural image quality without any discomfort.

Effects of the Invention As explained above, according to the present invention, it is possible to record high-quality images without recording unevenness or visual discomfort at high speed, and in addition, the order of the pulse voltages applied to the control electrodes is possible. regularity can be ensured, and there is no need to complicate the control electrode or recording needle drive circuit.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the electrode arrangement of an electrostatic recording head, Figure 2 is a circuit diagram of a conventional electrostatic recording control system, and Figures 3 and 4 are diagrams of a conventional electrostatic recording control system. Explanatory diagram of block selection control, fifth
The figure is a cross-sectional view of the electrostatic recording paper, Figure 6 is a waveform diagram showing the pulse voltage applied to the control electrode and the potential change of the low resistance layer of the electrostatic recording paper located directly below the control electrode, and Figure 7 is an explanatory diagram of the deviation of pixel recording position, No. 8
The figure is a circuit configuration diagram to which the electrostatic recording control method according to the present invention is applied, and FIG. 9 is an explanatory diagram of block selection control in the same embodiment. 1... Recording needle, 2 (S ₁ , S ₂ , ..., S _2o ,
_S2o+1 )...Control electrode, 10a, 10b...Recording needle drive circuit, 11...Control electrode drive circuit, _A1 ,
B ₁ ..., A _o , B _o ... block, A, B ... group, SA ₁ , SA ₂ , SB ₁ , SB ₂ ... subgroup.

Claims (1)

[Claims] 1 A predetermined number of recording needles on an electrostatic recording head are continuously arranged to form 2n blocks (n is an even number of 4 or more), and these 2n blocks are alternately divided into n blocks in the order of arrangement. The blocks are assigned to the first group and the second group, respectively, and furthermore, the blocks arranged up to the n/2nd block counting from one end of the n blocks belonging to the first group are assigned to the first group. In the subgroup, n/2+1
The blocks arranged from the th to the nth are
An electrostatic recording control device that selects one arbitrary block by making it belong to a subgroup, and then selects and records a block one block apart without selecting an adjacent block, First, the blocks belonging to the first subgroup are selected from one end to the n/2th in order of arrangement, then all the blocks belonging to the second group are selected from one end in order of arrangement, and finally the Blocks belonging to the second subgroup are n/2
The recording operation is performed by selecting blocks from +1st to nth in the order of arrangement, and the time interval from selecting any block belonging to each group to selecting a block adjacent to this block is equal to An electrostatic recording control method characterized in that the recording time of one line by a recording head is one-fourth or less.