JPS6187136A - Liquid crystal light valve - Google Patents

Abstract

PURPOSE:To obtain a rapid and highly regenerative optical transmitting characteristic by applying a low frequency signal to liquid crystal to form the starting point of the closed status of a microshutter, applying a high frequency signal to turn the microshutter to the opened status and then applying the low frequency signal to return the microshutter to the starting point of the closed status. CONSTITUTION:A driving circuit for driving a liquid crystal light valve to be used for optical transfer device is an integrated circuit and about 30V is required as its operating voltage at amplitude. A printing signal obtained by combining a common signal (c) and a picture element signal (d) is applied to the liquid crystal and transmissibility (a) is obtained. As to the common signal (c), a signal having frequency higher than that of the period fc of an opening signal time 188 out of a writing period and lower than that of the period fc of a residual time is used. Since the picture element signal (c) is opened in accordance with the opening signal (e), high and low frequency having a reversed phase against the common signal (c) is used, and to shield light, a low frequency 192 signal is used. Consequently, almost 100% optical transmissibility can be always obtained at the opening of the light valve inspite of high speed operation.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to the structure of a liquid crystal light bulb.

[Prior art]

FIG. 1 shows an example of the configuration of an optical printing device using a liquid crystal light valve. Optical writing is performed on the photosensitive drum 102 by an optical signal generating section 101 using a liquid crystal light bulb. At this time, the photosensitive drum 102 is connected to the corona charger 1.
10 and is pre-charged. At this time, when printing characters, the light signal is usually generated in correspondence with the character portions. This forms an electrostatic latent image, which is developed with toner by a magnetic brush developer 105. The developing method at this time is usually reversal development. Thereafter, the toner is transferred onto plain paper 104 by the transfer corona discharger 105, and the toner is transferred to the plain paper 104 by the transfer corona discharger 105.
Fixed by 6. The toner remaining on the photosensitive drum after transfer is removed by a blade 108, and the static image is neutralized by a static elimination lamp 109, and the process ends.

FIG. 2 shows the configuration of the optical signal generator. The optical signal generator is
It consists of a light source 111 such as a fluorescent lamp, a liquid crystal light valve, and an imaging lens 115, and the liquid crystal light valve consists of 14 panels 112, a substrate 117 on which a liquid crystal driving circuit 115 is mounted, and a polarizing plate 114. 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 7 ray for the lens 1'*.

Next, the general operation of a liquid crystal panel using nematic liquid crystal will be described.

The M2S diagram is a schematic diagram of a cross section of a liquid crystal panel.

Two glass substrates 200 with transparent grooves [m 202] are supported by a sole 201 and sealed, and liquid crystal compositions 205 and 204 are contained therein.

A voltage is applied to opposing portions of the transparent conductive film 202 by a power source 205 . Liquid crystals have dielectric anisotropy. The dielectric constants of the liquid crystal molecules in the long sleeve direction and the direction perpendicular to this, that is, the short sleeve direction, are different, and are on tI and ε, respectively. This is shown in Figure 4. The dielectric constants of the liquid crystal molecules 210 in the long axis direction 211 and the short axis direction 212 are respectively ε
, and on C. Further, a value above ε, -1 is defined as dielectric anisotropy, and is expressed as ΔC. In the case of Δt ) O and Δt (O, the dielectric anisotropy is called positive and negative, respectively. When a voltage is applied to the liquid crystal panel, the liquid crystal molecules have a large Jt ratio with respect to the direction of the electric field, so the dielectric anisotropy is called positive and negative, respectively. In other words, if the dielectric anisotropy is positive, a force acts to make the long sleeve direction of the liquid crystal molecules parallel to the electric field direction, and if the dielectric anisotropy is negative, the long axis direction A force is exerted that is perpendicular to the direction of the electric field.

The fifth example is a case where the dielectric anisotropy is positive, and the liquid crystal molecules 204 in the portion to which the electric field is applied are parallel to the direction of the electric field. The liquid crystal molecules 205 in the portion to which no electric field is applied are oriented sideways because they have been previously aligned fL so that they are parallel to the glass substrate. When the voltage of the power supply 205 is set to 6 ov, the liquid crystal molecules 204 naturally return to their initial alignment due to the alignment force generated due to the alignment treatment performed on the glass substrate (in this case, the surface of the transparent conductor) and the elastic force between the liquid crystal molecules. Arrange parallel to the glass substrate.A state in which they are arranged parallel to the glass substrate is called homogeneous orientation (
or array).

The above describes the electrical effects on the arrangement of liquid crystal molecules. Next, we will discuss optical anisotropy-birefringence, which is another property of a liquid crystal element having an electro-optic effect.

Liquid crystal molecules have a geometrically rod-like structure, so when observed when sealed between glass substrates, they have refractive index anisotropy, and nematic liquid crystals have a uniaxial crystal that is optically positive. It exhibits similar behavior, and furthermore; (the long sleeve direction of liquid crystal molecules and the optical width are almost the same. Therefore, the change in the electrical arrangement changes the optical characteristics and produces an electro-optic effect. Twisted nematic display elements are currently being widely applied using the characteristic of f
Many attempts have been made to apply the L-air optical effect to liquid crystal element all-optical printing devices, but what has not yet been put into practical use is the response speed, stability, etc. required for original printing Hrt. This is because there are major problems in this respect. In order to realize an optical printing device ft using liquid crystal, the following performance is required of the liquid crystal light valve. These are high speed and high exposure, as well as ease of manufacturing and stability in the operating environment in order to achieve the above two items.

A method of using a liquid crystal composition in which an optically active substance is added to a nematic liquid crystal that causes a dielectric relaxation phenomenon as a liquid crystal light valve that meets the above requirements (Japanese Patent Application No. 55-141085
etc.).

However, in this method, (1) Significant wavelength dependence.

+21 It depends significantly on the thickness of the liquid crystal layer of the fi crystal panel.

(3: High temperature dependence.

(4) High angle dependence to function as a light bulb.

There were some gaps.

From a practical point of view, the above-mentioned items +21 and 131 are major drawbacks in production and use. Also, from the point of view of its function as a light valve, it must open and close light with large amounts of energy. In other words, in order to use light from a light source efficiently, it is necessary to be able to use it in a certain wavelength range, have high transmittance in the open state, and be able to use light from a wide angle. , 141 does not satisfy this requirement. Furthermore, in the above (11 to 41), if the respective conditions are not met, the transmitted light energy decreases when opening, light leakage occurs when light is blocked, and the valve does not function as a light valve.

〔the purpose〕

The present invention overcomes the above-mentioned problems, and is made by applying a stratified wave signal in which a liquid crystal is homogeneously aligned in a two-frequency diagonal system, and the liquid crystal produces a birefringence effect and has a high voltage level. After setting the micro-shutter as the starting point for the closed state, applying a high-frequency signal to the liquid crystal to bring the micro-shutter into the open state, and applying the low-frequency signal to return the micro-shutter to the starting point for the closed state. The purpose of the present invention is to provide a liquid crystal light bulb that can obtain light transmission characteristics with good reproducibility over time.

FIG. 5 shows the arrangement of a liquid crystal panel and a linear polarizing plate used in the present invention. In this figure, the common signal ′
A glass substrate 121 with a pole ft is placed on the lower side, and a glass substrate 120t with a pixel signal is placed on the upper side. The surface of each glass substrate was rubbed with absorbent cotton so that the liquid crystal molecules were aligned. Arrows 150 and 151 are the friction directions of the upper and lower glass substrates, respectively, and are opposite to each other (the up and down directions do not matter in any direction as long as they are opposite). By this alignment treatment, the liquid crystal molecules are homogeneously aligned along the friction direction. Set the polarization plane of the linear polarizer at 45° to this processing direction at 152.155°.
Place it like this. 132 is above the upper glass substrate 120, and 155 is below the lower glass substrate 121, and are orthogonal to each other; the vertical relationship between bc 152 and 155 may be interchanged). The layout diagram in FIG. 5 corresponds to the diagonal position when observing refractive index anisotropy.

As mentioned above, the light transmittance in the diagonal direction is expressed as sin'' (·πdΔn/λ), where d is the thickness of the liquid crystal layer, λ is the wavelength of the incident light, and Δn is the birefringence index of the liquid crystal. In nematic night crystals, the long axis direction of the liquid crystal molecules almost coincides with the optical axis, and the apparent value of Δn can be changed by changing the tilt angle of the liquid crystal molecules. can be changed.

This principle was used in the above @ Kaisho 56-115277
However, the change in transmittance due to variations in the variables in the above equation remains a drawback. The above-mentioned drawbacks (1) wavelength dependence and (2) thickness dependence are directly variable variables. In addition, (3) temperature dependence and (4) angle dependence are
Vary Δn.

FIG. 6 shows the relationship between the voltage applied to the liquid crystal and the transmittance. In this example, a nematic liquid crystal with positive dielectric anisotropy has a threshold voltage of about 2V and Δn! Q, 16. This is the case when the thickness of the liquid crystal layer is about 6 μm. 154 is light wavelength λ = 548n%, half width 12n, 15th is λ = 451 nm, half width 8n
This was measured using a s interference filter. In the above-mentioned Japanese Patent Application Laid-Open No. 56-115277, λ=548n+
In the case of ys, the voltage Voff in FIG. 6 is used to turn off light, and the voltage von is used to switch to light transmission. As a result, a transmittance of almost 0 when extinction is obtained and a transmittance of nearly 100 when transmitting light is obtained, and it functions as a 7-layer. However, when the wavelength is λ = 45 I n s, a voltage of Vo + n is applied. When the Vott voltage is applied, the transmittance becomes lower than when the Vott voltage is applied, and the relationship between extinction and transmission is reversed. Additionally, the most important extinction state for light bulbs has disappeared. Although the example of FIG. 6 shows a change in only the wavelength, a similar phenomenon occurs also when the thickness of the liquid crystal and the f of the vortex type change.

As one means to solve this drawback, if we focus on ensuring the extinction state, the voltage level shown by the arrow 156 in Fig. 146,
Alternatively, by applying a voltage higher than this, it should be possible to always obtain a quenched state.

Therefore, FIGS. 7 and 8 show the signals applied to the liquid crystal using this method and the time response characteristics of the transmittance to the signals. FIG. 8 shows the applied signal.

Using a square wave with a voltage of 20V before 140 and after 141,
Between 140 and 141 is Ov. Corresponding to this signal, the transmittance changes as shown in FIG. λ=548n+
% case 142 and λ-g451n% case ' 4 S
It is. The characteristics required for a liquid crystal light bulb are a short response time and a large amount of light transmitted (111), that is, a large time integrated value of transmittance (before exposure to the photoreceptor).7th In the row shown in the figure, the response time is long and the transmittance is not high. However, when extinction occurs [when 'rIL pressure is applied]
The transmittance is satisfactory, and although the response characteristics themselves differ depending on the wavelength, there is an advantage that the above-mentioned exposure amount hardly changes. Although FIG. 7 shows only wavelength dependence, there is almost no change with respect to liquid crystal thickness or temperature changes, as well as wavelength.

Now, consider the operation of the liquid crystal in response to the signals shown in FIG. When a voltage is applied, the liquid crystal molecules are aligned approximately perpendicular to the glass substrate.

(The long sleeve direction of the liquid crystal molecules is perpendicular to the glass substrate; in reality, it is tilted by about 10° to 5° from the vertical when measured from the transmittance.) Nematic liquid crystals exhibit behavior similar to optical-axial crystals, Furthermore, the long sleeve direction and optical axis of liquid crystal molecules are
They are exactly in agreement. Therefore, when arranged perpendicularly to the glass substrate as described above, birefringence does not occur,
The transmittance is almost 0%. When the applied voltage is reduced to Ov from this state, the liquid crystal molecules return to the initial alignment (homogeneous alignment 9). The speed of return at this time is proportional to the viscosity of the liquid crystal and inversely proportional to the elastic modulus, and the liquid crystal gradually relaxes naturally and returns to its initial state. For this reason, it takes a long time to enter the light-transmitting state, which does not meet the requirement for high-speed response. Furthermore, the maximum value of the transmittance in Fig. 7 is at most 60
It is about %.

Normally, we should be able to expect about 100% as shown in Figure 6, but this means that in the thickness direction of the liquid crystal layer,
It can be inferred that this phenomenon occurs because the slope is not uniform over time. This is also considered to be due to natural relaxation caused only by the elastic force of the liquid crystal.

Table 1 shows an example of a nematic liquid crystal composition that exhibits dielectric relaxation at low frequencies. In the specification of the present invention, the nematic liquid crystal composition shown in Table 1 is used. (All including the above-mentioned FIGS. 6 and 7t-, measurement diagrams, and liquid crystal compositions used in the examples) The frequency characteristics of the dielectric constant of objects are shown. The measurement temperature is 50°C. 153 is on t, 15
4 indicates tI.

As shown in the figure, t becomes smaller as dielectric relaxation occurs and the frequency becomes more painful. 154 has an inflection point, and at this frequency, the imaginary dielectric constant 155 in the long sleeve direction reaches its peak. This frequency is 157ft relaxation frequency (abbreviated as fr)
It is called. In the case of this liquid crystal composition, it is 5.7 K HZ. The dielectric anisotropy becomes zero at a frequency (fc) 156 where C and ε intersect. This frequency is the crossover frequency, and at frequencies lower than this, △c>0. At high frequencies, Δt (0). For this liquid crystal composition, f
c is 8KEz. When a nematic liquid crystal with such dielectric constant characteristics is used, and a signal with a frequency lower than fc is applied, a force that aligns the liquid crystal molecules perpendicular to the glass substrate moves, and when a signal with a frequency higher than fc is applied, the liquid crystal molecules move in parallel. The power to arrange it is persistent.

6 and 47 in the conventional example described above, the nematic liquid crystal composition in Table 1 was used, the temperature was set at 40°C,
It is operated at a frequency (2 KHz) below fc. On the other hand, Fig. 11 shows a drive signal using a signal with a higher frequency than fc to force the liquid crystal molecules to align parallel to the glass substrate, and Fig. 10 shows the measurement data of the light transmittance at that time. Ahhh.

! [ is set to 40C. Its wavelength is 548 nm.

In FIG. 11, there are signals of 2 KHz lower than fQ before arrow 140 and after arrow 141, arrow 140 and arrow 14.
1, a 150 KHz signal higher than fc is used for 142. The voltage is 20V. The change in transmittance for this signal (FIG. 10) is significantly faster than that in FIG. 7.

The daytime speed performance required of liquid crystal light valves used in optical printing devices is that the writing cycle (the minimum time for the light valve open/close signal) is short, and that the exposure amount is always the same for the opening signal. Ami.

Figure 12 (a), (b), (c) shows the transmittance,
The liquid crystal applied voltage and aperture signal are shown. The symbol ○ in the aperture signal indicates an aperture, and the symbol X indicates a light shield. In contrast to this [6, the applied signal (
b) is 15QKEz (142) when the mark is O, and 1 when the mark is
A signal with a frequency of KHz is used. Transmittance at this time (
In a), the pattern becomes uneven, and the stability of the exposure amount required for a liquid crystal light valve used in an optical printing device is not satisfied. Therefore, in order to stabilize the exposure amount, a column using both high-frequency and low-frequency signals as the aperture signal is shown in Figure 15 (a).
, : (b) , 1(c). Once, the wavelength of the 40C0 light is 5A8nyn, and the voltage of the applied signal is 26V. The aperture signal (c) is the same as the aperture signal (C) in FIG. On the other hand, the applied signal (b) uses a high frequency (150 KHz) 142 and a low frequency of 2 KHz when the mouth is open, and a low frequency ZKBZ when the mouth is closed. Transmittance at this time (a
) has the same response to any aperture signal,
The amount of exposure is also uniform. The reason why the four-light shield becomes constant in this manner is that the alignment state of the liquid crystal before the high frequency signal is applied is always kept constant by applying the low frequency signal. By applying a signal with a frequency lower than fc, the long axis direction of the liquid crystal molecules is aligned perpendicular to the glass substrate.

Starting from this alignment state, when a signal with a higher frequency than fc is applied, the long axis direction of the liquid crystal molecules receives a force that makes them parallel to the glass substrate, and is tilted to some extent. This inclination angle changes the apparent birefringence Δn and changes the transmittance.

When this transmittance is almost at its peak, apply a low frequency,
By returning to the alignment state in which the long axis direction of the liquid crystal molecules is perpendicular to the glass substrate, it functions as a liquid crystal light bulb in response to one opening signal. In this way, since the arrangement state of the liquid crystal molecules is the same before and after one aperture signal is applied, it is possible to realize a liquid crystal light bulb in which the i fog light amount is always the same.

What has been described above is the basic idea of the present invention. Here, to summarize the above once again, (1) nematic liquid crystal that undergoes dielectric relaxation and reverses dielectric anisotropy, (2) is homogeneously oriented, (3) polarizing plates are arranged diagonally, Create a light shielding state by applying a signal with a frequency lower than +41fc (5) To create a single opening state, tilt the liquid crystal molecules with a signal with a frequency higher than fc, and then apply a signal with a frequency lower than fc. The purpose is to realize a liquid crystal light valve with high speed and stable exposure amount by returning to the initial state.

The present invention is the first to realize an epoch-making liquid crystal light bulb by satisfying each of the above-mentioned items at the same time.

Next, the electrode configuration 1 tail motion signal, etc. in the practical aspect of the above-mentioned basic operating method of the liquid crystal light valve used in the optical printing apparatus of the present invention will be described.

As described above, the method of operating the liquid crystal light valve of the present invention is to apply a signal with a frequency lower than fc to bring the liquid crystal light bulb into a light-blocking state. Therefore, only the opposing parts of the electrodes wired on the two glass substrates (the part to which the limit is applied) are in a light-shielded state, and the other parts are in a state in which light leaks. Since this does not function as a light bulb, it is necessary to partially block this light leakage. Therefore, the liquid crystal panel used in the present invention will be explained below.

FIGS. 14 and 15 show an example of the structure of a liquid crystal panel. This is an example in which the number of common signal electrodes is one (N-1). The liquid crystal panel includes a glass substrate 4i1 having a common signal electrode 122.
20, a glass substrate 121 including a pixel signal 'gi (j124), and a spacer 125, a liquid crystal composition 126
It consists of enclosed. A micro-shutter hole 1 is formed in a portion where the common signal 7ji 12'2 and the pixel signal electrode 124 face each other.
27 is provided. At least the common signal electrode and the pixel signal electrode in the portion where the micro-shutter hole is formed need to be made of a transparent conductive material, and this is used. Furthermore, it is necessary to use an optically opaque material for parts other than the micro-shutter hole to prevent light leakage.

In the example of FIG. 14, the metal film 12 with a thickness of 1000X or more
5 as a common signal! It is exquisitely formed. As another method, a black pigment dispersed in a phenol resin may be fired to form the micro-7 hole 127 as an optical mask. In this case, there is an advantage that it can be formed on either glass substrate. The light passing through the micro-shutter hole is modulated by the arrangement of liquid crystal molecules in this area and the combination of the two polarizing plates, and functions as a light shutter.

FIG. 16 is an example in which the number of common wL electrodes=4. Only the electrodes are shown. The pixel signal electrode 175 uses an optically opaque metal thin film as the base of the transparent conductive film except for the micro-shutter 176. Common signal type +4170~175
In this example, a metal film 177 is used to prevent light leakage between pixel signal electrodes, mainly consisting of a transparent conductive film.

Next, we will discuss the signals that actually apply voltage to the liquid crystal.

In order to operate as a liquid crystal light valve, 9g is required.
The *motion signal 161 shown in FIG. 15 may be used. In other words, as shown in FIGS. 14 and 15, a single common electrode is used, and a drive signal 161 (FIG. 15) that oscillates +/- with respect to the potential of this common electrode is applied to each pixel signal t. It works by stamping =. However, in the example of FIG. 15, the drive voltage is ±26V. The amplitude is 52V.

This voltage is a little too high. Furthermore, since a frequency of 150KHz is used, in order to suppress the distortion of the signal waveform,
It is desirable that the drive circuits be of complementary type. Furthermore, the number of liquid crystal lights/microshutters used in the optical printing device is approximately 2000, and in order to drive them, the driving circuit must be an integrated circuit, so the operating voltage needs to be approximately SOV in amplitude.

The method shown in FIGS. 17(a) to (e) makes this possible. A print signal (b) is applied to the liquid crystal by the combination of the common signal (c) and the pixel signal (a), and the transmittance of (a) is obtained accordingly. The common signal (c) is
Of the writing cycle (Tw) 187, when opening signal +ji
'l (T O) A signal with a higher frequency than fc during 188 (here 150KEZ), and a signal with a higher frequency than fc for the remaining time 189
A signal with a lower frequency (here 2K)lz) is used. (If N=1, the writing cycle and the allocated time match) The pixel signal Td) is the aperture signal (e)
(Similar to FIG. 15(c)) to open the opening.
Using high and low frequencies (191) that are in opposite phase to the common signal,
A low frequency wave 192 is used to block light. The high frequency portions of the common signal and the pixel signal are in opposite phase, and the pixel signal always uses a low frequency wave having an opposite phase with respect to the low frequency signal of the common signal.

Always using this low frequency is one of the most important driving methods of the present invention. This is 195 of the applied signal (b)
As shown in the figure, a low frequency is always applied at the soaking period. The transmittance (a) almost matches that of FIG. 1(a). The transmittance 185 when light is transmitted is exactly the same as that shown in FIG. 15, and the transmittance 186 when light is blocked shows that there is some light leakage, but it provides a sufficient function as the intended light shutter. Next, a driving method using eight common signals, which is another feature of the present invention, will be described.

The necessary functions of a liquid crystal light bulb for an optical printing device have been described above. In order to put optical printing 1Iit into practical use using a liquid crystal light valve, there is another important point, and that is that the price is low. As mentioned earlier, the liquid crystal light valve used as an optical printing device has 20
Approximately 0.00 microshutters are required, and in the above-described driving method, one driving circuit is required for each pixel signal electrode. The biggest component in the price structure of a liquid crystal light valve is the integrated circuit for the drive circuit and the connections between the drive circuit and the electrodes on the glass substrate. Ordinary liquid crystal display elements, thermal printers, etc. also perform time-division driving to compensate for this. The present invention performs time division by using the above-mentioned sA drive method to transmit both high frequency and low frequency signals, and is an essential drive method for reducing costs.

FIGS. 18b) to 18(e) show drive signals for an example having N common signal electrodes (referred to as N time division).

1st common signal (a), 2nd common signal +b) N-
This is the first common signal (c). Each common signal is a signal temporally shifted by 1/N of the soaking period (T w ) 505. Therefore, the configuration of the first common signal will be explained. The common signal is repeated with a period of Tw, and of 'rW,
The proportion time (TD) 506 is the time that can be used for light transmission or light shielding. This Tn is the aperture signal time (To
) 507, a signal with a frequency higher than fc is used, and the remaining time a signal with a frequency lower than fc is used. Furthermore Tw
During periods other than TD, a signal with a frequency lower than fo is used. Next, pixel signals will be described. By switching the light-transmitting frame number (d) and the light-blocking signal (e) in units of 'fD, a light-transmitting and light-blocking state can be created. This is similar to the case in FIG. 17. What is important here is that the low frequency part indicated by 513 is the same in all common signals, and furthermore, in the pixel signal, both the light-transmitting and light-blocking signals are the same, and the phase is opposite to the common signal. There is a thing. Furthermore, in the part indicated by 512, the high frequency of the common signal is in opposite phase to the high frequency of the light-transmitting pixel signal, and the low frequency of the common signal is in opposite phase to the low frequency of the light-blocking pixel signal. be. Due to the above signal requirements, the low frequency part of the common signal is divided into two classes, one of which is the part indicated by 515 (
S09 and 511), and the other is the part 310 corresponding to 512. By using the above drive signals, the number of pixel signal electrodes and pixel signal drive circuits can be reduced to 1/N. The electrode and microshutter configuration at this time is shown in Fig. 16 (in the case of N=4).
042. % Gansho 56-7Q44. Patent application 1986-7045
For details, please refer to the specification of the same application.

As described above, the present invention provides an inexpensive liquid crystal light valve for use in f2 optical printing at high speed and with a uniform exposure amount.

Next, an embodiment of an optical printing apparatus using the above liquid crystal light valve will be described.

<Example 1> When the optical printing device was operated under the settings and conditions shown in Table 2, a clear image was formed according to the aperture signal. The dots formed had a pitch of 100 μm both vertically and vertically. However, in image a, brightness unevenness occurred corresponding to the brightness unevenness of the NO-Rogen lamp.

By the way, one A4 sheet of paper was printed in 6 seconds.

At this time, the irradiation energy of one light pulse irradiated onto the photoreceptor was 8 lux seconds.

<Example 2> When the optical printing device was operated under the settings and conditions shown in Table 5, a uniform and clear image was formed. Similar to Example 1,
One A4 sheet of paper was printed in 6 seconds.

At this time, the irradiation energy u of one light pulse irradiated onto the photoreceptor was 5 erg/d.

Example 5 When the optical printing device was operated under the settings and conditions shown in Table 4, a uniform and clear image was formed. 4 common signal electrodes
Example 1 of the pixel signal drive circuit according to the book
It was possible to reduce the amount by half compared to 2 and 2. At this time, the irradiation energy of one light pulse irradiated onto the photoreceptor is:
It was 2 erg/crA. This energy is about half of that in Example 2, but the photoreceptor has a light wavelength of 540
nm (Table 2 Optical signal generating part (a) Q crystalline pulp (i) Liquid crystal panel liquid crystal Table 1 Nematic liquid crystal composition Nose liquid crystal thickness 5.4 μm α5μ
Corner common signal is pole a2 Pixel signal 1 Number of poles 1000° Number of microshutters 2000 Microshutter pitch 200μm x Z row microshutter hole dimensions
Horizontal 80μs Time (TD) One corner second opening signal time (To)
CL 6 corner seconds (b) Light source No. logeno lamp 4 [20 million cd/i Photoreceptor OdS Table 5 Optical signal generating section (a) Liquid crystal light valve (i) Liquid crystal panel liquid crystal Table 1 Nematic liquid crystal composition 9 Of course liquid crystal f - Thickness 5.4±[1
5 μs Common signal electrode number 2 Pixel signal electrode number 1000 Micro shutter number 2000 Micro shutter pitch 200 μm x Z row micro 7 X hole dimensions
Horizontal 80μn% x fd11ooμm (11) Relationship between polarizing plate arrangement and liquid crystal alignment direction Arrangement in Figure 5 (+i) Number of time divisions of H crystal drive signal 2 Signal amplitude voltage 26V Writing period (Tw) 2 When allocating seconds +1
J1 (TD) 1 meter second opening signal time (TO)
α5 class (1)) Light source Fluorescent lamp
Hexagonal aluminate OeMgAjHOl:
7b" Emission peak wavelength 548nm Radiance 250W/strm' Photoreceptor
as-Te (10%)60. US Photoreceptor circumferential speed 5 cm/sec Table 4 Optical signal generation section (q1 Liquid crystal light bulb (i) Liquid crystal panel Liquid crystal Table 1 Nematic liquid crystal composition Nose liquid crystal 1- Thickness 5.4 × α5 μ Corner common signal! Number of poles 2 Pixel signal Electrode a Number of 1000 microshutters 2000 microshutter pitch 200μs XZ row microshutter hole dimensions
Horizontal 110μm
TD) α5 million second opening signal @關(To)
152ms (b) Light source Fluorescent wrap
Hexagonal aluminate BaMgAjl@O,,:Ku
” ”, Mn” ” Emission peak wavelength 450 nm Radiation $ 200 W/st, rm' Table°
5 Optical signal generating section (a) Liquid crystal light valve (i) H crystal panel liquid crystal Nematic liquid crystal in Table 1 =, L liquid crystal 1 - Thickness 5.4±CL
5. us common signal 1 pole wi4 pixel signal! Number of poles: 500 Number of microshutters: 2000 Microshutter pitch: 400μ+s
(11) Relationship between polarizing plate arrangement and liquid crystal alignment direction υ Arrangement in Figure 5 (+Ii) fl! Crystal drive drive signal division factor 4 Signal amplitude voltage 29V Writing period (TV) 211L seconds allocated time (TD) [lL5 horse seconds opening signal time (To
) [lL32mstb) Light source Fluorescent lamp Hexagonal aluminate BaMgAjx6
0@, 1: Eu! ", Mn" emission peak wavelength
450nm radiance K 200 W/s tr
yr/photoreceptor 8. e-To (10%)6
Since the 45Qnz (this example) is about twice as large as the 0 μm example 2), the sensitivity of the photoreceptor and the energy product of the irradiated light matched, and a similar image could be formed.

<Example 4> When the optical printing device was operated under the settings and conditions shown in Table 5, a uniform and clear image was formed. This example has almost the same settings as Example 5, and is an example in which the printing speed is doubled by increasing the number of common poles to two. By the way, A4 size paper 1
[Effect] As described above, the present invention applies a low frequency signal having a voltage level that does not cause the liquid crystal to have a birefringence effect, and then uses the liquid crystal as the starting point for the closed state of the micro shutter. A high-frequency signal is applied to the micro-shutter to make it open, and a low-frequency signal is applied to return it to the starting point of the closed state. Therefore, even though the light valve is opened at high speed, it takes about 100 degrees to open the light valve. It has the effect of constantly reproducing light transmittance. Furthermore, light leakage during light shielding can be completely prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of an optical printing device. FIG. 2 is a diagram showing an example of the configuration of the optical signal generating section. FIG. 5 is a diagram showing the operation of the liquid crystal. FIG. 4 is a diagram showing how to determine the dielectric constant of liquid crystal. FIG. 5 is a diagram showing the relationship between the alignment direction of the liquid crystal and the optical surface of the polarizing plate. The 'I/X6 diagram is a diagram showing the voltage applied to the liquid crystal and the transmittance corresponding to the voltage. FIG. 7 and FIG. 8 are diagrams showing the response characteristics of the liquid crystal and the liquid crystal drive signal at that time. FIG. 9 is a diagram showing the frequency a characteristic of the dielectric constant of the nematic liquid crystal composition used in the present invention. FIG. 10 and FIG. 11 are diagrams showing the response characteristics of the liquid crystal and the liquid crystal drive signal at that time. Figures 1Z(a) to (c) are diagrams showing response characteristics of liquid crystal. FIGS. 15(a) to 15(c) are diagrams showing basic liquid crystal drive signals used in the present invention and response characteristics of the liquid crystal to the basic liquid crystal drive signals. FIG. 11i and FIG. 15 are diagrams showing an example of a cross-sectional view and a plan view of a liquid crystal panel used in the present invention. . FIG. 16 is a diagram showing an electrode configuration in the case of four common electrodes. FIGS. 17(a) to 17(e) are diagrams showing an example of the liquid crystal drive signal of the present invention and the response characteristics of the liquid crystal to the signal. FIGS. 18(a) to 18(e) are diagrams showing liquid crystal drive signals of the present invention. 102... Photosensitive s 105... Developing section 106
... Fixing section 111 ... Light source 112 ... Liquid crystal panel 114 ... Linear deviation ft',! ! 1115
...Liquid crystal drive circuits 120 and 121...Glass substrate 126...Liquid crystal composition 156...Cross frequency 1
25.170, 171, 172 and 175...
Common signal electrodes 124 and 175...Pixel signal electrode 505...Writing period 5.06...Pa allocation time 507...Aperture signal time 508...Signals with a higher frequency than fc 509 and 51
0...Signal board with frequency lower than fc Upper Fig. 4 Fig. 3 Fig. 6 Interval (1 second), Fig. 1I Fig. 12, Fig. 1-b, Fig. 1-7

Claims (1)

[Claims] The dielectric anisotropy changes depending on the frequency, and the crossing frequency fc
In a liquid crystal light valve having a micro-shutter in which a liquid crystal exhibiting dielectric anisotropy that is positive for a signal of a lower frequency and negative for a signal of a higher frequency than the frequency fc is homogeneously aligned, a voltage level is set at which the liquid crystal does not produce a birefringence effect. After applying a low frequency signal to the liquid crystal to set the microshutter as the starting point of the closed state, applying a high frequency signal to the liquid crystal to set the microshutter in the open state, and applying the low frequency signal to return the microshutter to the starting point of the closed state. A liquid crystal light bulb that is characterized by: