JPS6338691B2 - - Google Patents

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a printing device.

[Prior art]

FIG. 1 shows the configuration of the optical writing unit including the liquid crystal light valve. The optical writing unit consists of a light source 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 driving circuit 113 are mounted. The light emitted from the light source is modulated by a liquid crystal light valve. This optical signal 116 is imaged onto the photosensitive drum 102 by an imaging lens 115. An erect image can be obtained by using a focusing optical fiber array as the imaging lens. FIGS. 2 and 3 show the structure of the liquid crystal panel. The liquid crystal panel includes a liquid crystal composition 125 sealed between a glass substrate 117 having common signal electrodes 119 and 112, a glass substrate 118 having signal electrodes 121 and 122, and a spacer 126, and polarizing plates 123 on both sides of the glass substrate. and 124.
The common signal electrode consists of a transparent electrode 119 and an optically opaque metal electrode 120, and the signal electrodes 121 and 122 are transparent electrodes. Polarizing plates 123 and 12
4 are arranged so that their polarization planes are orthogonal to each other. The light is modulated by the microshutter 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-
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 (methylbulyl)-4'-cyanobiphenyls. The frequency characteristics of the dielectric potential sotropy of this liquid crystal are shown in FIG. The frequency at which the dielectric anisotropy is zero is called the crossover frequency and is expressed by fc. Let the frequency lower than fc be fL, and the frequency higher than fc be fH. The liquid crystal light valve operates by applying signals of frequencies fL and fH to each signal electrode. FIG. 5b shows the response of the applied signal and the light transmitted through the liquid crystal light valve a. A signal at time fH indicated by T2 and a signal at time fL at T3 are applied. T1 is called a write period, T2 is called an opening time, and T3 is called a non-opening time. The liquid crystal light valve opens by applying the fH signal, and closes by the fL signal. By the method described above, we were able to obtain a revolutionary high-speed liquid crystal light valve. However, in order to print a high-quality seal, it is necessary to arrange microshutters at a high density of about 10 per 1mm, and in order to print on A4 paper, they must be arranged in a width of 20cm, so the number of microshutters increases. becomes 2000 pieces. Therefore, in the method described above, the number of signal electrodes is 2,000, and the number of drive circuits and their mounting terminals are also 2,000 and 2,000, which has the disadvantage of lowering manufacturing yield and increasing cost. However, by using the 1/2 time division dynamic drive method, we were able to reduce the number of signal electrodes by half.

First, the structure of the electrode is shown in FIG. 401 and 40
2 are common signal electrodes, 403 to 405 are signal electrodes, and 410 and 412 are microshutters. Next, various signal waveforms are shown in FIG. The common electrode signal 420 has a repetition period Tf, and Ta and Tb each have a half period. In 1/2 time division, the first half 421 and the second half of one cycle of the common electrode signal 420 are selected, respectively. 420 signal waveform C
1,421 is named C2. The selection signal is composed of a high frequency fH having a frequency higher than the crossover frequency fc and a low frequency fL having a lower frequency than fc, and the respective times are Th and Tc. Low frequency fL when not selected
Only.

On the other hand, the signal waveform applied to the signal electrode side is a signal 422 for opening the microshutter (FON) and a signal 423 for closing the microshutter (Foff). The open signal FON, in which both FON and Foff have a period Ta or Tb that is half the period of the common electrode signal C1 or C2, has a high frequency part that is the same Th as the high frequency part of C1 or C2 and has an opposite phase, and a high frequency part that is opposite in phase to the low frequency part of C1 or C2. consists of low frequencies. The closing signal Foff is only a low frequency wave having an opposite phase to the low frequency fL of C1 or C2.

Now, the common electrode signal C1 is applied to the common electrode 401 in FIG.
FIGS. 8a, b, c, and d show voltage waveforms applied to the microshutter 410 when C2 is applied to each of the microshutters 402 and FON or Foff is applied to the signal electrode according to the data. Further, microshutter light transmission characteristics corresponding to the applied waveforms shown in FIG. 8 are shown in FIGS. 9a, b, c, and d. The horizontal axis of each graph in Figure 9 is time, and Th, Ta, Tf in Figure 8
corresponds to The vertical axis is the transmittance of the microshutter when the light transmittance when two polarizing plates are stacked in parallel is 100%. The result in Figure 9 is fh=
130KHz fL=5KHz, applied voltage ±30V, Tf=3m
sec, Ta=1 msec, and Th=0.7 msec conditions were obtained. The transmission characteristics of 430, 431, 432, 433 are 424, 425, 426, 42, respectively.
7 signal voltages.

In the electrode structure shown in FIG. 6, the pitch between the microshutters and the pitch between the signal electrodes are unclear, so there is a problem that high density and high resolution cannot be obtained.

〔the purpose〕

The present invention overcomes the above problems, and
Multiple microshutters within one signal electrode are
It is an object of the present invention to provide a printing device that can obtain high density and high resolution by arranging photoreceptors in a diagonal and horizontal direction with respect to the moving direction of the photoreceptor.

〔Example〕

FIGS. 10a, b, and c show the signal electrodes, common electrodes, and their combinations in this embodiment. a is the second
In the signal electrode 500 formed on the glass, the electrodes other than the shaded area are transparent electrodes, and the shaded area 501 is a metal film that blocks light. The electrode terminals extend in the vertical direction of the drawing in an interdigital manner, and the pitch P1 between the electrodes on one side is 400 μm, and there are 500 on each side. This improves reliability in high-density mounting of electrode terminals.
Spacing 50 between adjacent electrodes near center line 503
2 is 10 μm. b is a common signal electrode formed on the first glass. Common signal electrodes 504 and 505 are divided with respect to a center line 507, and the interval 508 is 10 μm. The shaded area is a metal electrode, and the microshutter 506 is a transparent electrode. The microshutters are arranged in a staggered pattern with 2000 pieces at a pitch of P ₂ = 100 μm (1000 pieces at a pitch of 200 μm on each side). Figure c shows these two glasses stacked so that the center lines 503 and 507 are aligned. The shaded area slightly cuts the light, and the light transmitted through the microshutter 511 is modulated. Therefore, light leakage from parts other than the microshutter causes background noise, which is undesirable.
Light leakage from the spacing 508 between the two common signal electrodes is geometrically unavoidable. Therefore, in this embodiment, a portion 501 of the signal electrode is masked with metal to minimize the portion 512 that causes light leakage to the extent that it does not pose a practical problem. Moreover, since the sides of the signal electrodes intersect at right angles to the center line, the distance between the signal electrodes can be maximized with respect to the light leakage portion 512 in a certain area, which is advantageous in panel manufacturing.

Next, by making the signal electrode 500 transparent except for the shaded portion 501, when combined with the first glass, it is possible to increase the error margin in both the vertical direction and improve the yield.

In addition, the interval l between the two rows of microshutter arrays arranged in a staggered manner (Figure b) is determined by the writing speed and photoconductor movement speed, since the written dots do not shift by half a pitch when driving in 1/2 time division. That is, it is limited by the pitch of the written dots in the moving direction of the photoreceptor. This time, I wrote at a pitch of 100 μm, so l = 250 μm. To do this, it is only necessary to delay the data for one side of the microshutter by two lines, while increasing the margin when creating the panel.

Next, FIG. 11 shows the overall profile of the signal electrode. I have included the dimensions of the panel I made this time (units are mm), but if something of this shape were constructed only from transparent electrodes, the impedance of the terminals themselves would be too large to be ignored. Therefore, as shown in the figure, a metal film was formed on a certain portion of the terminal to lower the impedance of the terminal.

〔effect〕

As described above, the present invention provides a liquid crystal light valve having a multi-digit common electrode, since the plurality of microshutters in one signal electrode are arranged diagonally horizontally with respect to the moving direction of the photoreceptor. However, since the pitch between the microshutters can be set to the minimum distance, it has the effect of obtaining high resolution.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical write signal generating section.
FIGS. 2 and 3 are diagrams showing the structure of a liquid crystal panel. FIG. 4 is a diagram showing the frequency characteristics of dielectric anisotropy of the liquid crystal material used in the present invention. Figure 5a,
b is a diagram showing the response characteristics of the liquid crystal material used in the present invention and the driving signal at that time. FIG. 6 is a diagram showing the electrode configuration used in the present invention. FIG. 7 is a liquid crystal drive waveform diagram according to the present invention, 420,
421 are common electrode signal waveforms, 422, 4
23 are open and close signal waveforms, respectively. FIGS. 8a to 8d are diagrams of voltage waveforms actually applied to the liquid crystal, and the combination of the common electrode waveform and the signal electrode waveform results in four types of waveforms as shown in the figures. 9A to 9D are graphs showing the light transmission characteristics of the microshutter when the four types of signals shown in FIG. 8 are applied. 424 becomes 430, 425 becomes 43
1, 426 corresponds to 432, and 427 corresponds to 433, respectively. 10a to 10c are diagrams showing the shapes of electrodes constituting the microshutter, in which a is a signal electrode, b is a common signal electrode, and c is a diagram in which the above two are superimposed. FIG. 11 is a schematic diagram of the entire signal electrode.

Claims (1)

[Claims] 1 A liquid crystal is sealed in a pair of transparent substrates, and a plurality of common electrodes are arranged on one of the substrates, and a plurality of signal electrodes are arranged on the other side to cross the common electrodes, thereby forming a plurality of microshutters. In a printing device having a photoconductor that moves in a direction perpendicular to the longitudinal direction of a liquid crystal light valve and a common electrode, a plurality of microshutters in one signal electrode are arranged in a direction perpendicular to the longitudinal direction of the photoconductor. A printing device characterized by being arranged diagonally and horizontally.