JPS6042457B2 - printing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an intermediate device using a liquid crystal light valve.

[Prior art]

FIG. 1 shows the configuration of an intermediate device using a liquid crystal light valve.

Light is written onto the photosensitive drum 102 by an optical signal generating section 101 using a liquid crystal light valve. At this time,
The photosensitive drum 102 is charged in advance by a corona charger 110. The optical signal at this time usually includes, for example, characters, in which light is generated corresponding to the part of the characters. This forms an electrostatic latent image, which is developed with toner by the magnetic brush developer 103. The developing method at this time is usually reversal development. Thereafter, the toner is transferred onto plain paper 104 by a transfer corona discharger 105 and fixed by a fixing device 106. The toner remaining on the photosensitive drum after transfer is removed by a blade 108, and the electrostatic latent image is neutralized by a static elimination lamp 109, and the process is completed. FIG. 2 shows the configuration of the optical signal generator (optical writing unit). The optical signal generating section includes a light source 111 such as a fluorescent lamp, a liquid crystal light valve, and an imaging lens 115.
The liquid crystal light valve consists of a substrate 114 on which a liquid crystal panel 112 and a liquid crystal drive circuit 113 are mounted. The light emitted from the light source is modulated by a liquid crystal light valve. This optical signal 116 is transmitted to the photosensitive drum 1 by an imaging lens 115.
The image is formed on 02. An erect image can be obtained by using a focusing optical fiber array as the imaging lens. Third
The structure of the liquid crystal panel is shown in FIG. The liquid crystal panel includes a glass substrate 1 having common signal electrodes 119 and 120.
17 and signal electrodes 121 and 122
18 and spacer 126, and polarizing plates 123 and 12 are placed on both sides of the glass substrate.
It consists of 4. The common signal electrode consists of a transparent electrode 119 and an optically opaque metal electrode 120, and the signal electrode 12
1 and 122 are transparent electrodes. Polarizing plates 123 and 124
are arranged so that their polarization planes are orthogonal to each other.

The light is modulated at the micro-shutter portion formed by the transparent portion 119 of the common electrode and the signal electrode. As a liquid crystal composition, an optically active substance 4-(2-Methylbulyl)- is added to the nematic liquid crystal of Japanese Patent Application No. 55-14108.
A high-speed liquid crystal light valve can be obtained by using a long-period cholesteric liquid crystal obtained by adding 3% by weight of 4"-Cyan Oblphenyls. The frequency characteristics of the dielectric anisotropy of this liquid crystal are shown in Figure 5. The frequency at which the dielectric anisotropy is zero is called the crossover frequency and is expressed by FC.The frequency lower than Fc is n, and the frequency higher than Fc is Fh.
This nl:d. The liquid crystal light valve operates by applying a signal with a frequency of Fh to each signal electrode. In such a liquid crystal light valve, in order to perform high-quality printing, it is necessary to arrange microshutters at a high density of about 10 per sugar, and in order to print on A-shaped, it is necessary to arrange them in a width of 2h. Therefore, the number of microshutters is 20 (1).

Therefore, in the method described above, the number of signal electrodes is 200, and the number of drive circuits and their mounting terminals is 2000 and 200.
There was a problem that the production yield was reduced. To solve this problem, conventionally, as shown in FIG. 6, a plurality of common electrodes 401 and 402 are used, and each signal electrode 403
- 406 each include a plurality of micro shutter windows 410,
411 was established. However, with the structure of the microshutter shown in Figure 6, the dot positions are shifted by half a pitch in the direction of travel of the photoreceptor between the part written in the first half of one cycle and the part written in the second half, making it impossible to draw a straight line in the horizontal direction. There were flaws.

〔the purpose〕

The present invention overcomes the above problems, and provides a printing device for a liquid crystal light valve having a plurality of rows of common electrodes.
- It is an object of the present invention to provide a printing device in which variations in dots on a line are prevented by determining the arrangement of microshutters depending on the relationship between the rotational speed of the printing device and the drum.

[Embodiment] FIG. 8 shows various signal waveforms applied to the liquid crystal light valve.

The common electrode signal 420 has a repetition period of Tf'(7-Ta
'(1-Tb are the selection period and non-selection period, respectively.
In the 11 time division, the first half 421 and the second half of one cycle of the common electrode signal 420 are respectively selected.

The signal waveform of 420 is named Cl, and the signal waveform of 42l is named C2.

The selection signal is composed of a high frequency stop having a frequency higher than the cross frequency Fc and a frequency n lower than Fc, and each time is n<5Tc. When not selected, only low frequency 1 is available. On the other hand, the signal waveform applied to the signal electrode side is that the microshutter opening signal (FOn) is 4222, the closing signal (
Foff) is 423.

Both FOnFOfl have the same period as the selection period Ta of the common electrode signal C1 or C2. The open signal FOn is C1 (or C
It is composed of a high frequency part that has the same length (Th) as the high frequency part in 2) and has an opposite phase, and a low frequency part that has an opposite phase to the low frequency of C1 (or C2). The close signal FOff is C1 (or C2
) is only a low frequency wave with an opposite phase to the resistive frequency wave n. Now, when C2 is applied to the common electrode signals Cl and 4O2 in FIG. 6, and FOn or FOff is applied to the signal electrode according to the data, the voltage waveform applied to the microshutter 410 is shown in FIG. . Furthermore, FIGS. 9A, b, c, and d show the light transmission characteristics of the microshutter corresponding to the applied waveforms of FIGS. 8A, b, c, and d. The horizontal axis of each graph in FIG. 9 is time, which corresponds to T1], Ta, and Tf in FIG. 8.
The vertical axis is the light transmittance i when two polarizing plates are stacked in parallel.
This is the transmittance of the micro shutter when it is set to 00%.
The results in Figure 9 show that Fh is 130KHz. ．． f1 is 2KH
z1 applied voltage is 30■, Tf is 2rT1SeC, . Ta
was obtained in 1 msec and 1Th in 0.7 msec. 43
Each transmission characteristic of 0,431,432,433 is 4
24, 425, 426, and 427 signal voltage poles.

Since the drive is performed in full 11 divisions, there are the following four types of waveforms applied to the signal electrode during one repetition period.

For example, in the case of the signal electrode 403, the micro shutter 41
0,411 are ON-OFF, ON-ON, O, respectively.
There are four states, FF-OFF and 0FF-ON, which correspond to 424, 425, 426, and 427 in FIG. 8, respectively.
In this way, 0N, 0 for one microshutter
There are two types of voltages applied to each FF.
However, in the case of the liquid crystal used in the present invention, as shown in FIG. 9, the difference in transmittance due to the difference in the two types of applied voltages for ON and OFF can be almost ignored. That is 424 and 4
It is considered that there is no difference in transmittance due to the 25. The same applies to the 0FF signals 426 and 427.

Now, as shown in Figure 10, the common electrodes Cl, 5Ol, C2, 5O
2, signal electrode 503 and micro shutter 504,
505 and drive it in the manner described above.

It is assumed that the photoreceptor moves from 504 to 505 in the direction of the arrow. If a signal as shown in FIG. 11 506 is applied to the signal electrode 503 using the method described above, the common signal C
In combination with l and C2, the signals actually applied to the microshutters 504 and 505 are 507 and 50, respectively.
It will be like 8. 509 and 514 are periods selected by C1 and C2, and 510 and 513 are non-selected periods.

509, 511, 512 are 0N, 0N, 0FF respectively
The signal waveforms 513, 515, and 516 are 0FF and 0FF, respectively.
There are signal waveforms of 0N and 0FF.

If the interval between the micro shutter windows 504 and 505 is 11, the writing cycle is T1, and the moving speed of the photoreceptor is V, then now 1
Consider the case when =O. If you want to draw a straight line in the horizontal direction, both adjacent microshutters are 0N, but those on the same signal electrode, such as 504 and 505, are 0N.
0N at timing 15. 515 is 1 more than 511
12T1 time is different, during which time the photoreceptor is 11 liver, ■
This means that these two dots are 11.
This results in a deviation of 2T1■ from the direction of travel.

Figure 12a shows this situation. Since one microshutter moves with a period of T1, Tl on the photoreceptor is
Dots are formed at a pitch of V, but adjacent dots are always shifted by 11 pitches, V1, that is, by a half pitch. Therefore, by setting the interval to 1=117 fV1V and shifting the dots by half a pitch from the beginning, uniform dots as shown in FIG. 12b can be obtained. As explained above, l is arbitrary as long as it satisfies I=(m+112)TlV. However, m is an integer, and in the case of 11n time division, adjacent dots will be shifted by 11nT1V, so as shown in FIG. (
m+112) TlV. 520 to 525 are common signal electrodes, and 526 is a signal electrode.

This time, the writing cycle T1 is 2m) Se with 11 time division drive.
The speed of the CL photoreceptor V=5C1n/S1 Considering the ease of manufacturing the panel, the area of the micro shutter, etc., m was set to 2, so 1 was set to 250 pm. Here, m is an integer determined by the distance to be taken between the designed common electrodes. In this case, since the data is intentionally delayed by two lines, one data is written with a delay in order to match the written data of adjacent dots. An example of a circuit for delaying data is shown in FIG. Serial data from the interface 600 is transferred from the control unit 601 to the clock 60.
2 as is and the inverted version by an inverter 604, and input them into shift registers 605 and 607. The data entered in 605 is sent as a latch signal 603
The data is latched into latch 606, but the data that has entered 607 passes through shift registers 608 and 609 and is then latched into latch 606.
It is latched to 10.

As described above, one side of the data is delayed by two lines. [
[Effect] As described above, the present invention allows the photoconductor to be moved at an interval of l that satisfies the following relationship, where the photoconductor moving speed is ■, the data write cycle for one row to the micro-shutter array is T1, and m is a natural number. Since the plurality of micro-shutter arrays are arranged in the moving direction of It has the effect of allowing horizontal lines to be drawn on the photoreceptor.

[Brief explanation of the drawing]

FIG. 1 shows the principle of a printer constructed using a liquid crystal micro-shutter array as an optical write signal section, and FIG. 2 shows an optical write signal generation section. FIGS. 3 and 4 are diagrams showing the structure of a liquid crystal panel.
FIG. 5 shows the frequency characteristics of the dielectric anisotropy of the liquid crystal material. FIG. 6 is a diagram showing a configuration of common electrodes in multiple rows. FIG. 7 shows liquid crystal driving waveforms according to the present invention, 420 and 421 are common electrode signal waveforms, and 422 and 423 are open and closed signal waveforms, respectively. 8A, b, c, and d are voltage waveforms actually applied to the liquid crystal. FIGS. 9A, b, c, and d are diagrams showing the light transmission characteristics of the liquid crystal light valve. 1st
FIG. 0 is a diagram of an embodiment of the liquid crystal light valve of the printing apparatus of the present invention. FIG. 11 is a signal waveform diagram applied to the liquid crystal light valve. FIGS. 12A and 12b are diagrams showing images printed by the liquid crystal light valve. FIG. 13 is a diagram showing the structure of a liquid crystal light valve having n rows of common electrodes. FIG. 14 shows an embodiment of a circuit for driving the liquid crystal light valve of the present invention. 401,402...
Common electrode, 403, 406...signal electrode, 504,
, 505...Micro shutter window, 526...
...Signal electrode, 520-525...Common electrode, 5
27-532...Micro shutter window.

Claims (1)

[Claims] 1. A liquid crystal light valve consisting of a plurality of micro-shutter windows in which a liquid crystal is sealed in a pair of opposing substrates, N rows of common electrodes on one of the substrates and a plurality of signal electrodes on the other;
In a printing device having a photoreceptor that is installed under the liquid crystal light valve and moves at a speed V in response to optical writing on the liquid crystal light valve, the period for writing data to the micro shutter array for one row is T_1, When the integer m is
A printing device characterized in that the plurality of micro-shutter arrays are arranged in the moving direction of the photoreceptor at intervals of 1 that substantially satisfy the relationship 1=(m+_1/N)VT_1.