JPH0780314B2 - Electrostatic recording method and device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording method and an apparatus therefor used in a printer, a facsimile, etc., and in particular, it generates ions according to an image signal to electrostatically The present invention relates to an electrostatic recording method and apparatus for recording an image.

[Conventional technology]

Conventionally, as this type of electrostatic recording device, there is the following one. That is, as shown in FIG. 14, the electrostatic recording head 101 is arranged so as to face the surface of the dielectric drum 100, and a desired electrostatic latent image is formed on the surface of the dielectric drum 100 by this electrostatic recording head 101. Form.

As shown in FIGS. 15 and 16, the electrostatic recording head 101 includes a plurality of drive electrodes 103, 103 ... On the surface of an insulating substrate 102.
Are provided in parallel with each other, and a plurality of control electrodes 10 are provided on the back surface thereof so as to intersect these drive electrodes 103, 103 ...
4 are provided, and the electrodes 103, 103 ... And 104, 104 ... Form a matrix. Then, the control electrode 10
Openings 105, 105 ... Are formed as discharge generating regions at positions intersecting the drive electrodes 103, 103. Openings 105, 105 ... Formed in these control electrodes 104, 104 ...
Are provided at the intersections of the drive electrodes 103, 103 ... And the control electrodes 104, 104 ... Which make up the matrix, and therefore these openings 105, 105 ... Also, as shown in FIG.
It constitutes a matrix.

Further, as shown in FIGS. 17 and 18, screen electrodes 107 are provided on the lower surfaces of the control electrodes 104, 104 ... Through an insulating layer 106, and the insulating layers 106 and the screen electrodes 107 are provided with the screen electrodes 107. As shown in FIG. 18, the control electrode 104,
The openings 10 are provided at positions corresponding to the openings 105, 105 ...
8 and 108 and openings 109 and 109 for extracting ions are formed.

Then, the electrostatic recording head 101 applies an alternating electric field to the drive electrodes 103 and a DC voltage to the screen electrodes 107, as shown in FIG. Also, control electrode 1
A high voltage corresponding to the image signal is applied to 04, 104 ... In a pulse form.

By doing so, a creeping corona discharge is generated in the openings 105, 105, between the drive electrodes 103, 103, ... And the control electrodes 104, 104, to which a voltage is selectively applied, as shown in FIG. The ion stream generated by the creeping corona discharge is accelerated or absorbed by the electric field formed between the control electrodes 104, 104 ... And the screen electrode 107, and the ion emission is controlled to control the dielectric drum 100. An electrostatic latent image by ions is formed on the upper surface in accordance with an image signal.

At that time, since the openings 105, 105 ... Of the control electrodes 104, 104 ... Which generate ions form a matrix, by controlling the emission of ions from these openings 105, 105. ... and control electrodes 104, 1 so that a desired electrostatic latent image can be formed on the dielectric drum 100.
04 ... is driven as follows in synchronization with the rotation of the dielectric drum 100.

That is, as shown in FIG. 14, an encoder 110 is attached to the rotation shaft of the dielectric drum 100, and the rotation speed or position of the dielectric drum is detected by this encoder 110. Then, while the pulse from the encoder 110 is output for one period T, as shown in FIG. 20, a plurality of drive electrodes 103, 103 ... Are provided with a predetermined pulse width Tw and pulse interval Td. A pulse voltage is applied to the control electrodes 104, 104 ... Which record the electrostatic latent images in synchronization with the sequential driving. By doing so, a creeping corona discharge is generated in the openings 105, 105 ... Between the drive electrodes 103, 103 ... and the control electrodes 104, 104 ... to which a voltage is applied, and the ions generated by this creeping corona discharge are generated. The flow is accelerated or absorbed by an electric field formed between the control electrodes 104, 104 ... And the screen electrode 107, and the emission of ions is controlled to form an electrostatic latent image by the ions on the dielectric drum 100 as an image signal. To be formed according to.

In this way, the electrostatic latent image formed on the dielectric drum 100 is developed by the developing device 111 into a toner image as shown in FIG. 14, and this toner image is formed on the dielectric drum 100 and the same. An image is recorded on the recording paper 113 by fixing the recording paper 113 simultaneously with the transfer on the recording paper 113 supplied to the nip portion between the pressure roller 112 and the pressure roller 112. In the figure, 114 is a cleaner for removing the toner remaining on the surface of the dielectric drum 100 after the toner image is transferred as described above, and 115 is a static eliminator for erasing the electric charges remaining on the surface of the dielectric drum 100. Shown respectively.

[Problems to be Solved by the Invention]

However, the above conventional technique has the following problems. That is, the head drive signal applied to the drive electrodes 103, 103 ... And the control electrodes 104, 104 ... Is composed of a drive electrode signal 111 and a control electrode signal 112, as shown in FIG. Ions are emitted in a dot shape only from the openings 109, 109 ... To which the signals 111 and 112 are simultaneously applied, and an electrostatic latent image is formed.

In FIG. 21, when the pulse voltage is simultaneously applied to the first drive electrode 103 and the first control electrode 104,
Dot d1 is printed. And, as shown in FIG. 20,
During one period T of the pulse output from the encoder 110, the drive electrode signal 111 is sequentially driven from the first to the fifth with a predetermined pulse width Tw and pulse interval Td, and the control electrodes 104, 104 ... The dots d1, d2, d3, d4, d5 are sequentially printed by being driven in synchronization with the drive electrode signal 111. In addition, next to these dots d1, d2, d3, d4, d5
d1 ', d2', d3 ', d4', d5 'will be printed.

Next, when the next pulse is output from the encoder 110 as shown in FIG. 20 with the rotation of the dielectric drum 100, the first drive electrode 103 is sequentially driven in the same manner as above. At that time, since the dielectric drum 100 is rotating,
The second dot d1 previously recorded by the electrostatic recording head 101 is placed at the adjacent position along the rotation direction A of the dielectric drum 100.
As shown in FIG. 1, dots d6 are printed. After that, every time a pulse is output from the encoder 110 for one cycle as the dielectric drum 1 rotates, the dots d11, d16, d21, d2
6, d31, d36, d41 are sequentially printed in a matrix along the rotation direction A of the dielectric drum 100, and desired images are recorded. As a result, the 41st dot d41 is printed next to the 5th dot d5 ′ printed by the first pulse output from the encoder 110.

By the way, when the encoder 110 outputs a pulse once, the print dots d1 and d recorded by the drive electrode signal 111 sequentially output at a predetermined pulse width Tw and pulse interval Td.
The positions of 2, ... d5 are the drive electrodes 103, 10 of the electrostatic recording head 101.
While the pitch is basically determined by the pitch of 3, ..., The positions of the dots d1, d6, d11, ... Which are sequentially recorded every time the encoder 110 outputs a pulse along the rotation direction A of the dielectric drum 100 are , Determined by the pitch of the pulse output from the encoder 110.

Therefore, due to an error in manufacturing the electrostatic recording head 101, the drive electrodes 103, 103, ...
If there is an error in the number of pulses output from the encoder 110 or a dimensional error in the diameter of the dielectric drum 100, as shown in FIG. 21, the adjacent drive electrodes 1 of the electrostatic recording head 101 are
The pitch d of the dots printed by 03 and 103 and the pitch P of the dots sequentially printed according to the pulse output from the encoder 110 are set to a predetermined integer n (n = n in the illustrated example).
2) The multiplied ones do not match each other. Therefore, for example, the dot d41 that should be printed next to the dot d5 '
However, the dielectric drum is not printed next to the dot d5 '.
The print is misaligned in the rotation direction A of 100. Therefore, the 22nd
As shown in the figure, for example, when recording a character of "Kanji" of Chinese character, the horizontal line of the character is regularly deformed and printed in a sawtooth shape, which causes a problem that image quality is significantly deteriorated.

A numerical examination of this problem is as follows.

That is, assuming that one cycle of the pulse output from the encoder 110 is T and the recording time per dot by the electrostatic recording head 101 is TD = (Tw + Td), one cycle T and 1 of the pulse output from the encoder 110. The recording time TD per dot can be expressed as follows.

T = P / v (1) TD = T / N = P / Nv (2) Here, as shown in FIG. 8, P is printed adjacent to the dielectric drum 100 along its rotation direction A. The dot pitch, v is the peripheral speed of the dielectric drum 100, and N is the drive electrode 10.
The number is 3, 103.

Since the print dots are recorded in the order of d1, d2, d3, ... d5, the drive electrodes 103, 103 ... Are sequentially driven with a predetermined pulse width Tw and pulse interval.
When driven at Td, the dielectric drum 100 rotates during that time, so the interval d between the dots d1 and d2 recorded on the dielectric drum 100 is an integer n of the dot pitch P (nn = n in the illustrated example).
2) Doubled, but this distance d is
At the geometrical spacing d'of the drive electrodes 103, 103 ... on 101,
Since the distance 2 is equal to the sum of the movement distances of the dielectric drum 100 during the time TD, this interval 2 is given by the following equation (2): d = nP = d '+ vT D = d' + P / N ( 3) can be expressed as Therefore, the pitch P is determined by P = d '/ (n-1 / N) (4) by modifying the equation (3).

On the other hand, the pitch P ′ determined by the pulse output from the encoder 110 is the diameter of the dielectric drum 100 being l,
The number of pulses generated per revolution of the encoder 110 is NE
Then, it is given by ∴P '= πl / NE (5).

If the pitch P of dots adjacently printed on the dielectric drum 100 along the rotation direction A and the pitch P'determined by the pulse output from the encoder 110 match, the print image is printed. There will be no deviation.

The electrostatic recording head is such that the distance d'of the drive electrodes 103, 103 on the electrostatic recording head 101 on the dielectric drum 100 is 0.2 mm, n is 2, and the number N of the drive electrodes 103, 103 is 5. 101
On the dielectric drum 100 with a diameter of 200 mm using 10 dots
Consider the case of printing / mm. At that time, the number of pulses NE output by the encoder 110 used per rotation is 6000.
Then, the pitch P given by the equation (4) is P = 0.2 / (2-1 / 5) ≈0.111.

On the other hand, the pitch P'given by (5)
Becomes P ′ = 200π / 6000≈0.105.

Therefore, a difference of 0.006 mm is generated between both pitches P and P ', and a step difference of d41 and d5' is eight times that, that is, 0.048 mm.

This step difference occurs because the pitch P of dots that are adjacently printed on the dielectric drum 100 along the rotation direction A and the pitch P ′ determined by the pulse output from the encoder 110 do not match.

Therefore, the step is caused by the drive electrode 10 of the electrostatic recording head 101.
3, 103 ... Variations in the distance d'of each other and encoder 110
If the error of the number NE of pulses output from the device or the error of the diameter of the dielectric drum 100 becomes larger, the error further expands.

Therefore, as described above, when the image is recorded, the horizontal lines of the characters are regularly deformed and printed in a sawtooth shape, which causes a problem that the image quality is significantly deteriorated.

[Means for Solving the Problems]

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to determine the pitch of the drive electrodes of the electrostatic recording head and the pitch of the pulses output from the encoder. An object of the present invention is to provide an electrostatic recording method and an apparatus therefor capable of recording a high-quality image without causing a shift in a recorded image even when there is a difference.

That is, according to the electrostatic recording method of the present invention, the electrostatic latent image is recorded on the rotating latent image carrier by the electrostatic recording head that records the electrostatic latent image by emitting ions in a matrix according to the image signal. In the electrostatic recording method for recording an image by forming an image and developing this electrostatic latent image to make it visible, the rotational speed of the latent image carrier is detected and the detected latent image is detected. The rotation speed signal of the image carrier is corrected to match the dot pitch in the rotation direction of the latent image carrier of the electrostatic recording head, and the electrostatic recording head is corrected according to the corrected rotation speed signal of the latent image carrier. It is configured to control the drive timing of.

The electrostatic recording apparatus according to the present invention includes an electrostatic recording head that discharges ions in a matrix according to an image signal to record an electrostatic latent image, and an electrostatic recording head formed by the electrostatic recording head. A rotatable latent image carrier that carries a latent image, pulse generation means that generates a pulse for controlling the output of the electrostatic recording head at a predetermined cycle with the rotation of the latent image carrier, and the pulse generation. Pulse cycle correction means for correcting the cycle of the pulse output from the means so as to match the dot pitch in the rotation direction of the latent image carrier of the electrostatic recording head, and the correction pulse corrected by the pulse cycle correction means. An electrostatic recording head control means for controlling the output timing of the electrostatic recording head is provided.

The pulse cycle correction means includes, for example, cycle measurement means for measuring the pulse cycle, correction rate setting means for setting the correction rate of the cycle, and multiplication means for multiplying the pulse cycle by the correction rate. Things are used.

As the pulse cycle measuring means, for example, this pulse cycle is measured every time the pulse generating means generates an output control pulse, and the pulse cycle correcting means measures the latest pulse cycle measured by the pulse cycle measuring means. The one configured to correct the pulse period using the pulse period of is used.

[Action]

In the electrostatic recording method according to the present invention, the rotational speed or position of the latent image carrier is detected, the detected rotational speed or position of the latent image carrier is corrected, and the latent image carrier after correction is detected. Since it is configured to control the drive timing of the electrostatic recording head according to the rotational speed or position, it can be adjusted between the drive electrode pitch of the electrostatic recording head and the detected rotational speed or position of the latent image carrier. Even if there is a difference in the values, the detected rotational speed or position of the latent image carrier is corrected, and the drive timing of the electrostatic recording head is controlled according to the corrected rotational speed or position of the latent image carrier. Therefore, it is possible to drive the electrostatic recording head so as to match the pitch of the drive electrodes of the electrostatic recording head, and thus it is possible to prevent positional deviation from occurring in the recorded image.

Further, in the electrostatic recording apparatus according to the present invention, an electrostatic recording head that ejects ions into a matrix to record an electrostatic latent image according to an image signal, and a static recording head formed by the electrostatic recording head. A rotatable latent image carrier that carries an electrostatic latent image, pulse generation means that generates an output control pulse of the electrostatic recording head at a predetermined cycle as the latent image carrier rotates, and the pulse generator. A pulse cycle correction means for correcting the cycle of the pulse output from the means, and is configured to control the output of the electrostatic recording head by the correction pulse corrected by the pulse cycle correction means. Even if there is a difference between the pitch of the drive electrodes of the electrostatic recording head and the detected rotational speed of the latent image carrier, the correction pulse corrected by the pulse cycle correction means is used to Since the output control of the electrographic recording head can be performed, the pitch of the drive electrodes of the electrostatic recording head and the pitch of the pulses output from the pulse generating means can be made to coincide with each other, resulting in a positional deviation in the recorded image. Can be prevented.

Further, as the pulse cycle measuring means, this pulse cycle is measured every time the pulse generating means generates an output control pulse, and the pulse cycle correcting means measures the latest pulse cycle measured by the pulse cycle measuring means. By using a device configured to correct the pulse cycle by using, it is possible to perform optimum output timing control of the electrostatic recording head according to the rotation state of the latent image carrier at that time.

〔Example〕

 The present invention will be described below based on the illustrated embodiments.

FIG. 2 shows an embodiment of the electrostatic recording apparatus according to the present invention. In the figure, reference numeral 1 denotes a dielectric drum as a latent image carrier, and the dielectric drum 1 can be rotated in the direction of the arrow by a driving means (not shown). An electrostatic recording head 2 is arranged above the dielectric drum 1 so as to face each other with a predetermined gap.

As shown in FIG. 3, the electrostatic recording head 2 includes a first insulating substrate 3 having a rectangular shape in plan view. As shown in FIG. 4, a plurality of linear drive electrodes 4, 4, ... Are provided in parallel with each other on the front surface of the first insulating substrate 3, and on the back surface of the insulating substrate 3, Drive electrodes 4, 4 ...
A plurality of control electrodes 5, 5, ... Are provided so as to intersect with, and a matrix is formed by both electrodes 4, 4 ,. As shown in FIG. 3 and FIG. 4, the control electrodes 5, 5, ... Circular openings 6, 6 as space regions where creeping corona discharge is generated at positions intersecting the drive electrodes 4, 4 ,. ... is provided. Since the drive electrodes 4, 4, ... And the control electrodes 5, 5, ... Form a matrix, these openings 6, 6, ... Are provided at the intersections of these electrodes 4, 4 ,. The openings 6, 6 ... Also form a matrix as shown in FIG. Then, the first insulating substrate 3, the drive electrodes 4, 4, ... And the control electrodes 5, 5, ... Form an ion generating section 7 as shown in FIG.

As shown in FIG. 5, a screen electrode 9 is provided on the lower surface of the control electrodes 5, 5, ... Of the ion generator 7, with a spacer layer 8 serving as a second insulating substrate interposed.
As shown in FIG. 6, the spacer layer 8 is formed in a plane rectangular shape having a length that is substantially the same as that of the first insulating substrate 3 and a width that is slightly narrower. It is fixed to 3. As shown in FIG. 5, the spacer layer 8 has openings 10 larger than the openings 6, 6 ... at positions corresponding to the openings 6, 6 ,.
10 ... is provided. In addition, the screen electrode 9 has
Similarly, openings 11, 11, ... As ion derivation regions are provided at positions corresponding to the openings 6, 6, ... Of the control electrodes 5, 5 ,.

In FIG. 4, reference numeral 12 denotes a head substrate that covers the surfaces of the drive electrodes 4, 4, ....

Further, as will be described later, a pulsed drive signal is applied to the drive electrodes 4 and the control electrodes 5, and the drive electrodes 4, 4, ... And the control electrodes to which a voltage is selectively applied. As shown in FIG. 7, a creeping corona discharge R is generated in the openings 6, 6 between the slits 5, 5, ... And the ion current S generated by the creeping corona discharge R is applied to the control electrodes 6, 6. Is accelerated by an electric field formed between the screen electrode 9 and the screen electrode 9, and the ion current S is controlled and emitted from the openings 11, 11 ... Are formed according to the image signal.

The head drive signal applied to the drive electrode 4 and the control electrode 5 is composed of a drive electrode signal and a control electrode signal, as will be described later, and an opening portion to which both electrode signals are applied at the same time.
Ions are ejected in a dot shape only from 11, 11. In FIG. 8, when the pulse voltage is simultaneously applied to the first drive electrode 4 and the first control electrode, the dot d1 is printed. Then, as will be described later, while the pulse is output once from the encoder, the drive electrode signals are from the 1st to the Nth (N is the number of drive electrodes 4; 5 in the illustrated example) at a predetermined interval Td. The dots d1, d2, d3, d4, d5 are sequentially printed because the control electrodes are driven sequentially and are driven in synchronization with their respective timings. Then, the next pulse from the encoder accompanying the rotation of the dielectric drum 1 sequentially drives from the first drive electrode, and the dot d6 is printed at the position adjacent to the dot d1 as the dielectric drum 1 rotates. It After that, the pulses are sequentially printed as d11, d16, d21, d26, d31, d36, d41 for each pulse output from the encoder as the dielectric drum 1 rotates. As a result, the d41'th dot is printed side by side next to d5 'printed fifth by the first pulse from the encoder.

By driving the drive electrodes 4 and the control electrodes 5 forming the matrix as described above, for example, letters of the alphabet E are printed as shown in FIG.

Thus, the electrostatic recording head 2 causes the dielectric drum 1 to move.
The electrostatic latent image formed on the surface of is, as shown in FIG.
The toner image is visualized by the developing device 16 arranged on the side of the dielectric drum 1 to form a toner image. The toner image formed on the surface of the dielectric drum 1 is fixed at the same time as being transferred onto the recording paper 17 supplied in synchronization with the rotation of the dielectric drum 1 from a paper feeding device (not shown).

Transfer and fixing of the toner image is performed as follows.
That is, the pressure roller 18 is pressed against the surface of the dielectric drum 1 at a predetermined pressure (for example, 150 to 200 kg / cm ² ),
By supplying the recording paper 13 to the nip portion between the dielectric drum 1 and the pressure roller 18, the toner image formed on the dielectric drum 1 is simultaneously fixed onto the recording paper 17 by the pressure transfer. Has become.

As described above, the cleaner 19 removes the toner and the like remaining on the surface of the dielectric drum 1 for which the toner image transfer and fixing process has been completed, and the static eliminator 20 erases the charges remaining on the surface.

By the way, in this embodiment, a pulse generating means for generating an output control pulse of the electrostatic recording head at a predetermined cycle with the rotation of the latent image carrier is provided. That is, as shown in FIG. 10, the above-mentioned dielectric drum 1 has an encoder serving as a pulse generating means on its rotary shaft 21.
22 is attached, and the rotational speed of the dielectric drum 1 is detected by this encoder 22.

As shown in FIG. 11, the encoder 22 is fixed to the rotary shaft 21 of the dielectric drum 1, and a rotary disk 23 having slits 23a, 23a ... Engraved on its outer peripheral edge at a predetermined pitch. The slits 23a, 23 are arranged on the outer peripheral edge of the rotating disk 23.
Transmissive optical sensor 24 that optically detects the passage of a ...
And the output of this optical sensor 24 is amplified and the slits 23a, 23a
It is composed of an amplifier 25 that outputs a pulse signal synchronized with the passage of a.

The encoder 22 is a rotary shaft of the dielectric drum 1.
The optical sensor 24 detects the rotation of the rotary disk 23 fixed to the optical disk 21, and the amplifier 25 outputs a pulse signal in synchronization with the rotation of the rotary disk 23 to detect the rotational speed of the dielectric drum 1. The output control pulse of the electrostatic recording head 1 is generated at a predetermined cycle.

The block diagram in FIG. 2 shows the signal processing unit of the electrostatic recording apparatus according to this embodiment. In the figure, 26 is an image memory for storing print data sent from a host computer (not shown), and 27 is print data stored in the image memory 26 for the drive electrodes 4, 4, ... And control electrodes of the electrostatic recording head 2. A data assembler for rearranging according to a matrix of 5, 5, ..., 28 is an image buffer for temporarily holding print data sent from the data assembler 27 to the electrostatic recording head 2, and 29 is an electrostatic recording head 2.
, A timing generator for generating a timing signal for driving based on the print data held in the image buffer 28, and 30 is a predetermined voltage applied to the drive electrodes 4, 4 ... Reference numeral 31 denotes a drive circuit for applying and driving the pulse signal, and 31 denotes a pulse cycle correction circuit for correcting the cycle of the pulse signal output from the encoder 22.

FIG. 1 shows the structure of the pulse period correction circuit in detail. In the figure, 32 is an encoder cycle measuring circuit that measures the cycle T of the pulse signal output from the encoder 22 based on a reference clock, 33 is a latch circuit that latches the measurement value from the encoder cycle measuring circuit 32, and 34 is the encoder cycle. An increase / decrease value setting circuit that sets a correction value to be added to the pulse cycle measured by the measuring circuit 32, and a latch circuit 35 based on the correction value set in the increase / decrease value setting circuit 34.
A multiplying circuit for multiplying the pulse period latched by 33, 36
Is a selector for switching whether to add or subtract the correction value calculated by the multiplication circuit 35 to the pulse period T measured by the encoder period measuring circuit 32, and 37 designates whether the correction value is added or subtracted by the selector 36. A set circuit, 38 is an addition / subtraction circuit for adding or subtracting the correction value calculated by the multiplication circuit 35 to the measured value of the cycle T from the encoder fixed to the latch circuit 33, and 39 is a value latched by the addition / subtraction circuit 38 In the electrostatic recording apparatus according to this embodiment, an image is electrostatically recorded in the following manner. That is, as shown in FIG. 2, the print data sent from the host computer (not shown) and written in the image memory 26 is rearranged by the data assembler 27 in accordance with the matrix of the electrostatic recording head 2 and the image buffer 28. Entered in. And this image buffer 28
The print data input to is output to a drive circuit 30 according to a timing signal generated by a timing generator 29, and the drive circuit 30 drives the electrostatic recording head 2 to record an electrostatic latent image. Is done.

At that time, the generation of the timing signal by the timing generator 29 is determined based on the pulse signal 40 output from the encoder 22, but is not determined by the pulse signal 40 itself output from the encoder 22, It is determined based on the pulse cycle corrected by the pulse cycle correction circuit 31 as follows.

That is, the pulse cycle correction circuit 31 measures the cycle T of the pulse signal 40 output from the encoder 22 by the encoder cycle measurement circuit 32 based on the reference clock, as shown in FIG. Then, the period signal of the pulse signal 40 output from the encoder 22 measured by the pulse period measuring circuit 32 is sent to the multiplying circuit 35 while being latched by the latch circuit 33, and the multiplying circuit 35 increases / decreases the value setting circuit. A multiplication operation is performed based on the value preset in 34. The increase / decrease value setting circuit 34 sets the increase / decrease value so that the pitch of the drive electrodes 4, 4, ... Of the electrostatic recording head 2 and the pitch of the pulse output from the encoder 22 become equal. Next, the correction value calculated by the multiplication circuit 35 is sent to the selector 36, and the selector 36 switches whether the correction value is added or subtracted as set in the set circuit 37.

Next, the correction value is latched by the adder / subtractor circuit 35.
The value latched in 33 is added or subtracted. The added / subtracted value is output to the timing generator 29 via the latch circuit 39.

Then, in this timing generator 29, based on the corrected pulse signal 41 sent from the pulse period correction circuit 31, based on the pulse width Tw and pulse interval Td preset in the timing generator 29, A timing signal for driving the electrostatic recording head 2 is generated according to the print data as follows.

That is, the drive signal of the electrostatic recording head 2 is composed of the drive electrode signal 38 and the control electrode signal 39 as shown in FIG. 12, and the drive electrode signal 38 and the control electrode signal 39 are turned on at the same time. When it is turned on, a latent image is printed. Then, the drive electrode signal 38 is synchronized with the rising of the pulse T ′ corrected by the pulse period correction circuit 31, such as the first drive electrode 41, the second drive electrode 42, and the third drive electrode 43. It is turned on sequentially. At that time, the drive electrode signal 38 is sequentially turned on based on the preset pulse width Tw, is output from the encoder 22, and is synchronized with the rising edge of the pulse of the period T ′ corrected by the pulse period correction circuit 31. The first drive electrode signal 381 has a pulse width T
Only w is turned on, but after that, when the interval Td between the pulse signals sent from the control circuit 31 has elapsed, the second drive electrode signal 382 is turned on by the pulse width Tw. Thereafter, the same process is repeated to print the latent image of one line. At that time, a control electrode signal 39 is applied to the control electrode 5 in a pulse form in accordance with the print data and in synchronization with the drive electrode signal 38.

By the way, the corrected pulse output signal 41 output from the pulse cycle correction circuit 31 has the cycle T of the pulse output from the encoder 22 corrected based on the value set in the increase / decrease value setting circuit 34. It has become a thing. Therefore, even if there are variations in the intervals between the drive electrodes 4, 4, ... Of the electrostatic recording head 2 or there is an error in the number of pulses output from the encoder 22 or an error in the diameter of the dielectric drum 1, the electrostatic recording head The pitch d of the dots printed by the two adjacent drive electrodes 4 and 43 and the pitch P of the dots sequentially printed according to the pulse output from the encoder 22.
The values obtained by multiplying by a predetermined integer n can be matched with each other.

That is, the adjacent drive electrodes 4, 4 of the electrostatic recording head 2 are
The pitch P, which is 1 / n of the pitch d of the dots printed by ... Is given by the above-mentioned equation (4), as shown in FIG.

P = d ′ / (n−1 / N) (4) This value P is printed at the geometrical spacing d ′ between the drive electrodes 4, 4, ... Of the electrostatic recording head 2 and at this dot spacing d ′. The number n of dots and the drive electrodes 4, 4, ... Of the electrostatic recording head 2.
It is determined by the number N of N.

On the other hand, the pulse signal output from the encoder 22
The cycle T of 40 is corrected by the pulse cycle correction circuit 31 so as to match the pitch of the drive electrodes 4, 4, ... Of the electrostatic recording head 2.

That is, the adjacent drive electrodes 4, 4 of the electrostatic recording head 2 are
Is 1 / n the pitch d of the dots printed by, the distance d ′ between the drive electrodes 4, 4, ... On the electrostatic recording head 2 on the dielectric drum 1 is 0.2 mm, and n is 2,
The electrostatic recording head 10 in which the number N of the drive electrodes 103, 103 ... Is 5
10 dots on a dielectric drum 100 with a diameter of 200 mm using 1.
Consider the case of printing mm. At this time, if the number of pulses NE output from one rotation of the encoder 110 used is 6000, the pitch P given by the equation (4) is P = 0.2 / (2-1 / 5) ≈0.111.

On the other hand, the uncorrected value of the pitch P'given by the above-mentioned equation (5) is P '= 200π / 6000≈0.105, and there is a difference of 0.006 mm between both pitches P and P'. .

Therefore, the pulse cycle correction circuit 31 corrects the cycle T of the pulse from the encoder 22 by increasing it by 5.71%. By doing so, the corrected pitch P ′ of the pulse output from the encoder 22 becomes P ′ = 0.105 + 0.105 × 0.0571≈0.1109955.

As a result, the difference between the pitch P and the corrected pitch P ′ is 0.111−0.109955 = 0.0000045 mm, which is 0.048 mm (48 μm) before the correction of dot position deviation, that is, 1/2 dot is displaced, After that 0.000036mm (0.036μm)
In other words, there is a deviation of only about 1/3000 dot, which is a practically negligible value.

Then, by the pulse 41 corrected by the pulse period correction circuit 31 in this way, as shown in FIG.
A signal is sent to the timing generator 29 to control the drive of the electrostatic recording head 2. FIG. 7B shows a case where a negative correction is performed.

By the way, in this method, since the signal 40 from the encoder 22 is corrected by the pulse period correction circuit 31 to newly generate the pulse signal 41, what is different between the pulse signal 40 from the encoder 22 and the corrected pulse signal 41? The cycle may also be different. Therefore, in this embodiment, the correction signal
This is prevented by using the period measured when 41 is output for the next pulse.

To further explain this, as shown in FIG. 13 (a), when the correction pulse T1 'is output, the period T1 of the pulse 40 is measured, and this is corrected to create the pulse signal 41 of the period T2'. To do. Then, when outputting the pulse signal 41 of the cycle T2 ′,
When the period T2 of the pulse 40 is measured and the pulse signal 41 of the period T3 'is output, one period T3 of the pulse 40 is skipped and the period T4 of the pulse 40 is measured. Therefore, the deviation of the cycle between the pulse signal 40 from the encoder 22 and the corrected pulse signal 41 is within 1 to 2 pulses, and therefore the number of cycles of the pulse signal 40 from the encoder 22 and the corrected pulse signal 41 There is no problem of slipping.

FIG. 13 (b) shows a case where the correction is made to the minus side. In this case, however, the cycle T3 of the pulse 40 is measured twice because the cycle of the corrected pulse signal 41 becomes shorter. hand,
We are adjusting the timing.

This timing control is performed as follows, for example. That is, the operation of measuring the encoder cycle in the latch 39 and writing a new cycle is performed every time, and the circuit of the printing portion takes out the new cycle stored in the latch when printing is completed.

By doing so, as shown in FIG. 13 (a), when printing is long, a new cycle is always written in the latch, so that printing is performed at the latest cycle. That is, if printing is in progress, the old cycle is erased from the latch, the new cycle is latched, and this is repeated in another cycle. On the contrary, as shown in FIG. 13 (b), when the printing becomes short, old data is repeatedly read from the latch and printed on the printing side until a new cycle is latched.

In this case, it is confusing if new data is sent to the latch at the very moment when the latch data is being read, in which case the latch is disabled so that the data cannot be written.

As described above, the pitch P obtained by halving the pitch 2 of the dots printed by the adjacent drive electrodes 4 and 4 of the electrostatic recording head 2 and the pitch P ′ determined by the pulse output from the encoder 22 are set. Even if there is a difference between the two, it is possible to correct the period of the pulse output from the encoder 22 so that the two pitches P and P ′ coincide with each other, and there is no positional deviation in the printed dots. , Can record high quality images.

As described above, in the electrostatic recording apparatus according to this embodiment, the electrostatic recording head 2 that records the electrostatic latent image by ejecting ions in a matrix according to the image signal, and the electrostatic recording head 2 A rotatable dielectric drum 1 for carrying an electrostatic latent image formed by the above, and an encoder 22 for generating an output control pulse of the electrostatic recording head at a predetermined cycle with the rotation of the dielectric drum 1. And a pulse period correction circuit 31 for correcting the period T of the pulse 40 output from the encoder 22, and the output control of the electrostatic recording head 2 is performed by the correction pulse 41 corrected by the pulse period correction circuit 31. Since it is configured to perform, even if there is a difference between the pitch P of the drive electrodes 4, 4, ... Of the electrostatic recording head 2 and the detected rotation speed of the dielectric drum 1, the pulse cycle correction is performed. Times Since the correction pulse 41 corrected by 31 can control the output of the electrostatic recording head 2, the drive electrodes 4 electrostatic recording head 2
Since the pitch P of ... and the pitch P'of the pulse 40 output from the encoder 22 can be made to coincide with each other, it is possible to prevent the occurrence of positional deviation in the recorded image, and perform high-quality image recording. You can

〔The invention's effect〕

The present invention has the above-mentioned configuration and operation, and even if there is a difference between the pitch of the drive electrodes of the electrostatic recording head and the pitch of the pulses output from the encoder, the recorded image is not displaced. It is possible to provide an electrostatic recording method and an apparatus therefor capable of recording a high quality image.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an electrostatic recording apparatus according to the present invention, and FIG. 2 is a configuration diagram showing an electrostatic recording apparatus to which the electrostatic recording apparatus according to the present invention can be applied, FIGS. FIG. 4 is a plan view and a cross-sectional view showing an ion generating portion of the electrostatic recording head,
5 and 6 are sectional and plan views showing the electrostatic recording head, FIG. 7 is a sectional view showing the operation of the electrostatic recording head, and FIGS. 8 and 9 are the same recording by the electrostatic recording head. FIG. 10 is a perspective view showing an end portion of the dielectric drum, FIG. 11 is a configuration diagram showing an encoder, FIG. 12 is a timing chart showing a printing operation, FIG. 13 (a),
(B) is a timing cheat showing the operation of this embodiment,
FIG. 14 is a block diagram showing a conventional electrostatic recording device, FIG. 15 and FIG.
FIG. 16 is a plan view and a sectional view showing the ion generating part of the electrostatic recording head, FIGS. 17 and 18 are a plan view and a sectional view showing the electrostatic recording head, and FIG. 19 is an operation of the electrostatic recording head. 20A and 20B are timing charts and explanatory diagrams showing the recording operation of the electrostatic recording head, and FIG. 22 is an explanatory diagram showing a recorded image. [Description of symbols] 1 ... Dielectric drum 2 ... Electrostatic recording head 4 ... Drive electrode 5 ... Control electrode 11 ... Opening 22 ... Encoder 31 ... Pulse period correction circuit 32 ... Pulse period measurement Circuit 35 ... Multiplier circuit

Claims (4)

[Claims] 1. An electrostatic latent image is formed on a rotating latent image carrier by an electrostatic recording head which records an electrostatic latent image by ejecting ions in a matrix according to an image signal, and the electrostatic latent image is formed. In the electrostatic recording method for recording an image by developing and visualizing the latent image, the rotational speed of the latent image carrier is detected, and the detected rotational speed signal of the latent image carrier is detected. Is corrected so as to match the dot pitch in the rotation direction of the latent image carrier of the electrostatic recording head, and the drive timing of the electrostatic recording head is controlled according to the corrected rotational speed signal of the latent image carrier. An electrostatic recording method characterized by. 2. An electrostatic recording head for recording an electrostatic latent image by ejecting ions in a matrix according to an image signal, and a rotatable rotatable electrostatic latent image formed by the electrostatic recording head. A latent image carrier, pulse generating means for generating a pulse for controlling the output of the electrostatic recording head in a predetermined cycle with the rotation of the latent image carrier, and a pulse output from the pulse generating means. The output of the electrostatic recording head is corrected by a pulse cycle correcting means for correcting the cycle so as to match the dot pitch in the rotation direction of the latent image carrier of the electrostatic recording head, and the correction pulse corrected by the pulse cycle correcting means. An electrostatic recording apparatus comprising: an electrostatic recording head control unit that performs timing control. 3. The pulse cycle correction means, a cycle measurement means for measuring the cycle of the pulse, a correction rate setting means for setting a correction rate of the cycle, and a multiplication means for multiplying the pulse cycle by the correction rate. The electrostatic recording apparatus according to claim 2, wherein the electrostatic recording apparatus comprises: 4. The pulse cycle measuring means measures the pulse cycle each time the pulse generating means generates an output control pulse, and the pulse cycle correcting means measures the latest pulse cycle measured by the pulse cycle measuring means. 4. The electrostatic recording apparatus according to claim 3, wherein the pulse period is corrected using the pulse period.