JPH0143295B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a recording device using a liquid crystal light shutter using an electro-optic effect in an optical recording section, and particularly to a novel time-division liquid crystal light shutter driving method. [Prior Art] So-called impact printers, which perform mechanical printing by striking a ribbon on paper, have been considered the industry standard as computer output terminals for many years. This impact printer has good printing quality and is highly reliable. However, in terms of recording speed and recording density, as the amount of information increases, it is no longer possible to fully satisfy customer demands. In contrast, electrostatic development, without mechanical printing,
So-called non-impact printers that create images by heat-sensitive development or the like can record in free format, making it easy to record at high density. The recording methods of this non-impact printer include optical recording, magnetic recording, electrostatic recording, and thermal recording.
Optical recording is the best method as it can be used in a wide range of applications from low speed to high speed. In this optical recording method, lasers, OFTs, LEDs,
A light conversion element such as an LCD is used, but when a laser is used, the optical scanning system is complicated and expensive, and there are also problems in stabilizing the laser light output. on the other hand
When OFT is used, it is difficult to downsize the
When LEDs are used, the manufacturing yield of monolithic LED arrays is low and the light output varies widely. In addition, when using lasers and LEDs, their emission wavelengths are around 630 to 820 nm, so
There is a deviation from the spectral sensitivity range of the photoconductive recording medium, and insufficient sensitivity of the photoconductive recording medium is always a problem. Furthermore, if the long wavelength side sensitivity of the photoconductive recording material is sensitized, there is a drawback that the recording material becomes sensitive to environmental conditions such as temperature changes. Therefore, research has been carried out on techniques using liquid crystals as optical recording devices. A recording device using such a liquid crystal is a liquid crystal optical shutter in which a plurality of microshutters are arranged in dots, and a light source emits light from a light source, and the individual microshutters are opened and closed according to the image information. The light that has passed through the shutter is irradiated onto a photoconductive recording medium to form a latent image, and the drive for opening and closing is performed by dividing a plurality of microshutters into n groups, as shown in Figure 1. Group selection signal like
Time-division driving was performed using _A1 to An, and the microshutters in each group were opened and closed only during selected periods, and remained closed during non-selected periods. [Problems with the Prior Art] In the time-division driving performed as described above, the number of time divisions, writing period, etc. are determined by the response speed of the liquid crystal element, the magnitude of the light source energy, the number of drivers for driving, etc. By performing n time division driving, the period assigned to the selected group is equal to the write cycle.
If it is TW, it is shorter than TW/n. Therefore, if the liquid crystal light shutter is driven in n time divisions using the conventional method, the opening time of each microshutter will be reduced by 1/
At the same time, the amount of exposure that the photoreceptor receives becomes less than 1/n, and as the time division number n increases, the image writing speed increases, but the problem of insufficient light amount occurs. [Object of the Invention] In view of the above-mentioned conventional drawbacks, the present invention substantially achieves It is an object of the present invention to provide a recording device which can perform an operation similar to static drive and which does not reduce the opening time of each microshutter. [Summary of the Invention] In order to achieve the above object, the present invention has an optical recording section that performs optical writing corresponding to an image signal on a photoconductive recording medium, and the optical recording section includes a light source, a plurality of recording signals, A liquid crystal optical shutter comprising an electrode and a plurality of write selection signal electrodes, and a plurality of microshutters formed by these electrodes arranged in a dot arrangement;
Recording comprising an imaging optical system and selectively driving the plurality of microshutters at two frequencies, one higher than a specific frequency fc at which the dielectric anisotropy of the liquid crystal composition becomes zero, and one lower than the specific frequency. In the apparatus, a write selection signal consisting of a frequency f _H higher than the specific frequency f _C and a frequency f _L lower than the specific frequency f C is sequentially written to the plurality of write selection signal electrodes at a cycle.
a first supply means for supplying the signals with different phases by a period T _{W /} n _, which is obtained by dividing T _W into _n ; and a second supply means for supplying a recording signal having the same amplitude as the write selection signal, and the recording signal supplied from the second supply means has a period obtained by dividing the write period T _W by n.
Either the f _L signal has a predetermined phase over the entire region T _W /n, or the front part of the period T _W /n is the f _H signal of the predetermined phase, and the rear part is the f _L signal of the predetermined phase, and the first supply means The write selection signal supplied from the write selection signal is an _fH signal having an opposite phase to the _fH signal of the predetermined phase during the selection period in which the microshutter is selected by the write selection signal, and the microshutter is Non-selection period not selected by write selection signal,
The signal waveform applied to _{the microshutter} during the selection period has _a frequency over the entire selection period due to the write selection signal and the recording signal. f _L and
A superimposed waveform of f _H , or a superimposed waveform where the front part of the selection period is a frequency f _H and the rear part is a superimposed waveform of frequencies f _L and f _H ,
This signal waveform sets the microshutter in an open or closed state, and the signal waveform applied to the microshutter during the non-selection period has a frequency f after the non-selection period due to the write selection signal and the recording signal. At _L , the front part is a waveform containing a superimposed waveform of frequencies f _L and f _H or a 0 V waveform, and this signal waveform drives the microshutter to substantially continue the open/closed state set in the previous selection period. It is characterized by doing. [Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, the recording operation of a liquid crystal optical shutter using a liquid crystal as an image information recording device will be described with reference to FIGS. 2 to 4. In FIG. 2, the surface of a photoconductive recording medium 1 (hereinafter referred to as photoreceptor) is uniformly charged by a charging section 2 provided in advance at a constant distance from the photoreceptor 1. The optical recording section 3 is driven by a recording control section 4 that receives image recording information and controls timing and the like, performs electro-optical conversion of the information, and performs recording on the surface of the photoreceptor 1 for optical writing. Optical writing is performed on the surface of the photoreceptor 1 by irradiating light from the optical recording section 3. The electrostatic latent image thus formed on the photoreceptor 1 is developed with toner and made into a visible image in a developing section 5 provided close to the photoreceptor 1. The paper 6 is fed by a paper feed roll 7, temporarily stopped at a standby roll 8, synchronized with the toner image, and the toner image is transferred onto the paper 6 at a transfer section 9. Next, the paper 6 is separated from the photoreceptor 1 at a separation section 10, and the toner image is fixed on the paper 6 at a fixing section 11, and then sent out by a paper discharge roller 12. On the other hand, the photoconductor 1 has a static eliminator 13 provided close to the photoconductor 1.
After the toner charge is neutralized in step , the remaining toner is cleaned in the cleaning section 14 , and the surface charge on the photoreceptor 1 is neutralized in the eraser 15 . FIG. 3 shows the structure of the optical recording section 3 used in the configuration of the copying machine that performs the above operations. The optical recording section 3 includes a light source 16 and a liquid crystal light shutter 1.
7. It is composed of a condensing lens 18, and the light from the light source 16 is irradiated onto the photoreceptor 1 via the liquid crystal light shutter 17 and the condensing lens 18. As shown in FIG. 4, the liquid crystal light shutter 17 is composed of two glass substrates 19 and 20 sealed with a dual-frequency drive liquid crystal or a mixture thereof, and the glass substrate 19 is provided with signal electrodes 21 alternately. A common electrode 22 is provided on the glass substrate 20. The microshutter 23 is constructed of a transparent electrode made of indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), etc., with the necessary size and shape at the intersection of the signal electrode 21 and the common electrode 22. . Generally, electrophotographic recording devices are desired to have a recording density of 9.4 dots/mm or more, and the microshutter 23 is approximately
It is desirable that the thickness is 100 μm ^or less. By disposing at least one polarizing plate on the liquid crystal panel 24 configured in this manner, the liquid crystal light shutter 17 is activated, and the irradiated light from the light source 16 is modulated and focused by the microshutter 23 based on the recording signal. The light is irradiated onto the photoreceptor 1 through the optical lens 18. Typical liquid crystal light shutters used in the present invention are the guest-host type (hereinafter referred to as GH type) and the twisted nematic type (hereinafter referred to as TN type).
This is a liquid crystal light shutter, and its operating principle will be explained with reference to FIG. FIGS. 5a and 5b are diagrams explaining the GH type mode, and FIGS. 5c and 5d are diagrams explaining the TN type mode. The GH type liquid crystal cell 25 is made of a guest dye dissolved in a host liquid crystal for dual-frequency driving, and a liquid crystal mixture in which a p-type dichroic dye is dissolved as the dye is placed between transparent electrodes provided on glass or the like. It is constructed by sandwiching the liquid crystal molecules 26 and arranging them homogeneously. 1 so that the polarization axis is parallel to the liquid crystal molecules 26 of the GH type liquid crystal cell 25 configured in this way.
The liquid crystal light shutter 28 is constructed by arranging the polarizing plates 27. In FIG. 5a, incident light 29 is linearly polarized by a polarizing plate 27 and enters a GH type liquid crystal cell 25. In FIG. The arrangement of the dye molecules 30 changes in conjunction with the liquid crystal molecules 26. In p-type dichroic dyes, absorption in the long axis direction is greater than in the short axis direction, so the incident light 2
When 9 is monochromatic light having the same absorption wavelength as the p-type dichroic dye, most of the polarized light 31 that enters the dye molecules 30 arranged parallel to the liquid crystal molecules 26 is absorbed by the dye molecules 30. Therefore, the emitted light 32 almost disappears. Therefore, the liquid crystal light shutter 28 is in a closed state. On the other hand, in the state where a low frequency voltage is applied, that is, the state shown in FIG. The liquid crystal light shutter 28 is in an open state, and is emitted almost as is. Next, in the TN type liquid crystal cell 33 shown in c and d of the same figure, a liquid crystal mixture in which an optical rotation agent is dissolved in a liquid crystal for dual-frequency driving is sandwiched between transparent electrodes, and the liquid crystal molecules 34 are screwed at 90 degrees between both electrodes. Polarizing plates 3 are arranged on both sides of the TN type liquid crystal cell 33.
5 and 36, the liquid crystal light shutter 40 is constructed. This TN type liquid crystal cell 33 has the property that when a low frequency voltage is applied to the liquid crystal layer, molecules align in the direction of the electric field, and return to their original state when a high frequency voltage is applied or the electric field is removed. In the figure c, the incident light 37 is transmitted to the polarizing plate 35.
The light is linearly polarized and enters the TN type liquid crystal cell 33. When a low frequency voltage is not applied here, that is, when the liquid crystal molecules 34 are twisted by 90 degrees, the output light 38 from the TN type liquid crystal cell 33 undergoes optical rotation because it has an optical rotation of 90 degrees. The deflection plane of the light is rotated by 90 degrees and the light is incident on the polarizing plate 36. In this case, since the polarization plane of the output light 38 and the polarization axis of the polarizing plate 36 are parallel, the output light 38 can pass through the polarizing plate 36 and output light 39 is generated. Therefore, the liquid crystal light shutter 4
When set to 0, it becomes an open state. On the other hand, when a low frequency voltage is applied as shown in d of the same figure, that is, when the liquid crystal molecules 34 are aligned in the direction of the electric field, output light 38 that is not optically rotated is output, and the light is aligned with the polarization axis of the polarizing plate 36. Since they are perpendicular to each other, they cannot pass through and the liquid crystal light shutter 40 is in a closed state. Next, a two-frequency drive method using a liquid crystal light shutter having the above properties will be explained below. The dual-frequency drive used in the present invention attempts to reverse the dielectric anisotropy Δε by changing the frequency of the electric field, thereby rearranging the liquid crystal molecules. According to Figure 6, the dielectric anisotropy of the liquid crystal for dual-frequency driving is △
Let's talk about ε. The dielectric anisotropy △ε is determined by the dielectric constant in the long axis direction of the liquid crystal molecules (hereinafter referred to as △ε ₁ ) and the permittivity in the orthogonal direction (hereinafter referred to as △ε ₂ ), △ε = △ε ₁ − △ε ₂
It is expressed as The liquid crystal molecules are aligned parallel to the electric field direction when Δε>0, and are aligned perpendicularly when Δε<0. Here, the frequency when Δε=0 is called a cross frequency (hereinafter referred to as fc). Therefore, at frequencies lower than fc (hereinafter referred to as f _L ), △ε = △εL, indicating positive dielectric anisotropy, and at frequencies higher than fc (hereinafter referred to as f _H ), △ε = △εH, indicating negative dielectric anisotropy. Since it exhibits dielectric anisotropy, as mentioned above, by applying the f _L signal, the liquid crystal molecules can be aligned parallel to the electric field, and by the f _H signal, they can be aligned perpendicularly.
As explained in FIG. 5, it can be used to open and close a liquid crystal optical shutter. The dielectric anisotropy Δε shown in Figure 6 is sensitive to viscosity;
Therefore, it changes greatly depending on the temperature. As the temperature increases and the viscosity decreases, fc increases, and the Δε characteristic in FIG. 6 shifts to the right (high frequency side). As a specific example, when the temperature rises from 20℃ to 40℃, fc will change from 5KHz.
It increases by nearly an order of magnitude to 46KHz. In the same figure,
If the liquid crystal cell is turned on and off at f _L and f _H at room temperature, as the temperature rises, Δε on the f _H side becomes smaller and the off-side conditions for the liquid crystal cell become stricter. If the viscosity is low, the movement of the liquid crystal molecules becomes faster and a high-speed response is expected, so it is desirable to use the liquid crystal at a certain temperature. Furthermore, since it is heated by the light source, it is desirable to set the temperature within the range of 40°C to 65°C from the viewpoint of temperature control. Now, a necessary condition for a liquid crystal light shutter is that it has a high contrast ratio between open and closed states. As shown in Figure 5 a and b, GH type liquid crystal cell 2
5 and one polarizing plate 27
The optical modulation characteristics of No. 8 will be explained with reference to FIGS. 7 and 8. Figure 7 shows the absorption polarization spectrum of a GH type cell made of a liquid crystal mixture containing a p-type dichroic dye.
and B2 indicate the absorbance when linearly polarized light is incident parallel and perpendicularly to the director of a homogeneously aligned liquid crystal in which a dye is dissolved. The dichroic ratio CR of a dichroic dye is expressed as CR=B1/B2, and the larger the CR, the larger the contrast ratio. Therefore, λ shown in the same figure
B1 reaches a maximum at a wavelength of m, and the dye exhibits maximum absorption. FIG. 8 shows the spectral characteristics when constructed with the GH type liquid crystal optical shutter 28 as shown in FIGS. 5a and 5b. C1 and C2 in the figure are spectral characteristics corresponding to FIGS. 5a and 5b, respectively, where C1 shows the transmittance when the liquid crystal molecules 26 are homogeneously aligned, and C2 shows the transmittance when the liquid crystal molecules 26 are homeotropically aligned. Hereinafter, the state shown in FIG. 5a or C1 in FIG. 8 will be referred to as the off state of the liquid crystal cell, and the state shown in FIG. 5b or C2 in FIG. 8 will be referred to as the on state of the liquid crystal cell. Similarly, the state of the TN type liquid crystal cell 33 in FIG.
The state d in the figure will be referred to as the on state. As shown in FIG. 8 C1, when the liquid crystal cell is in the off state, the minimum transmittance at the wavelength λm is P1, which indicates the transmittance when the liquid crystal light shutter 28 is closed. P2 indicates the transmittance at λm when the liquid crystal cell is in the on state, and indicates the transmittance when the liquid crystal light shutter 28 is in the open state. Incidentally, dyes generally tend to deteriorate when exposed to short wavelength light, particularly ultraviolet light, and this light resistance can be solved by simultaneously providing the polarizing plate 27 with UV cut characteristics. Figure 8 C1, C
2 shows the spectral transmittance of the liquid crystal light shutter when a polarizing plate with UV cut property is used, and D1 and D2 show the spectral transmittance of the liquid crystal light shutter when using a polarizing plate without UV cut property. For this reason, Figure 5 a,
It is desirable that the polarizing plate 27 b is installed on the incident light side of the GH type liquid crystal cell 25, that is, on the light source side. As shown in FIG. 8, since the transmittance of the liquid crystal light shutter 28 using the GH type liquid crystal cell has a large dependence on wavelength, it is desirable that the polarized light 31 has a spectrum as narrow as possible. An aluminate fluorescent lamp is a suitable light source for this purpose, and its spectral distribution characteristics are shown in FIG. In this case, the aforementioned polarizing plate 27 can also have the characteristic of cutting off light having a peak around 480 nm and below, and as can be seen from FIG. 8, the contrast ratio is further improved. Regarding the long wavelength side, if there is a problem due to the characteristics of the shutter, a filter can be added to cut it. In addition, UV cut characteristics are provided to the polarizing plate, and for wavelengths with other spectral peaks, multiple dyes with different wavelengths λm of maximum absorption are added.
The flat part of the spectral transmittance characteristic shown in the figure can be widened. Up to now, we have described the compatibility conditions between the light source and the liquid crystal light shutter using the GH type cell, and the compatibility conditions with the photoreceptor 1 will be described below. A wide variety of materials are used for electrophotographic photoreceptors, including selenium (Se), cadmium sulfide (CdS), and zinc oxide (ZnO) materials. As mentioned above,
In optical recording using lasers or LED media, their emission wavelengths are near long wavelengths, while the electrophotographic photoreceptors have low sensitivity in this vicinity, so sensitization is required, which increases the complexity of the process. has become a problem. However, the GH mentioned above
The liquid crystal light shutter allows you to select the light source and dye and determine the wavelength that matches the characteristics of the photoreceptor, so you can use the photoreceptor used in electrophotographic copying machines.
Therefore, other electrophotographic processes can be used with little modification. In FIG. 8, the transmittance P1 when the liquid crystal light shutter is off at wavelength λm is determined by the polarization rate of the polarizing plate 27 and the absorbance B1 of the dye, and the transmittance when it is on
P2 is determined by the transmittance of the polarizing plate 27, the absorbance B2 of the dye, etc. The curves C1 and C2 in the figure are shifted up and down depending on the transmittance of the polarizing plate and the dye concentration.
Since contrast depends on transmittance, the dichroic ratio CR=B1/B2 of the dye is an important factor. Next, the contrast ratio of the liquid crystal light shutter 40 using the TN type liquid crystal cell 33 shown in FIGS. 5c and 5d will be described. In this case, the contrast ratio is 3
3 and is determined by the polarizing plates 35 and 36. Figure 10 shows the spectral characteristics of a liquid crystal light shutter using a TN type liquid crystal cell, with curves E1 and E
2 correspond to FIG. 5c and d, respectively, where curve E1 shows the spectral transmittance characteristic when the liquid crystal cell is in the off state, and curve E2 shows the spectral transmittance characteristic when the liquid crystal cell is in the on state. Also here, since the liquid crystal is an organic substance, it is a good idea to provide the polarizing plate 35 on the incident light side with UV cut characteristics at the same time. The TN type liquid crystal light shutter has the advantage of being able to use a light source with a wider range of wavelengths than the GH type liquid crystal light shutter mentioned above. Next, the condenser lens 18 used in the present invention will be described. In order to record using large paper such as A3 size, there is a liquid crystal light shutter 17 and a condensing lens 18.
requires an effective length of approximately 300mm. A self-occurring lens (manufactured by Nippon Sheet Glass) is a condensing lens 18 suitable for this purpose. The brighter the self-occurring lens, the greater the chromatic aberration, and the conjugate length of the lens changes greatly depending on the wavelength. Therefore, there is no problem with GH-type liquid crystal light shutters, but in the case of TN-type liquid crystal light shutters, it is desirable to use a light source that is close to monochromatic light, or to convert the light beam to near-monochromatic light using a filter or the like. Next, the differences between the GH type and TN type liquid crystal light shutters described above will be explained below.
The GH type liquid crystal light shutter 28 is normally off (closed) when there is no signal and when the f _H signal is applied, as shown in Figure 5a, and turned on (opened) when the f _L signal is applied, as shown in b. It is a shaped light shutter. on the other hand
The TN type liquid crystal optical shutter 40 is a normally-on type that turns on when there is no signal and when the f _H signal is applied, as shown in c of the same figure, and turns off when the f _L signal is applied, as shown in d of the same figure. The operation is completely opposite to that of the GH type. Due to this difference, the GH type LCD optical shutter and the TN type
The configuration of the liquid crystal panel required is somewhat different between the type liquid crystal light shutter and the type liquid crystal light shutter. This difference will be explained with reference to FIG. In the liquid crystal panel 24, liquid crystal is also present in areas other than the micro-shutter section 23. Therefore, if a normally-off type GH type liquid crystal light shutter is used, no special treatment is required because the liquid crystal part, where the liquid crystal cell is not formed by electrodes, has no signal and is always closed. of
When using a TN type liquid crystal light shutter, the liquid crystal part, which does not constitute a liquid crystal cell, is always open even though there is no signal, so all parts except the microshutter 23 must be optically masked with an opaque material.
Therefore, the GH type liquid crystal light shutter is more desirable from a structural standpoint. Figure 11 shows the liquid crystal light shutter 1 shown in Figures 3 and 4.
7. It is a diagram showing the liquid crystal panel 24 in more detail. In the figure, a gap is maintained between two glass substrates 19 and 20 by a spacer 41, and a liquid crystal mixture 42 for dual-frequency driving is sealed between them. The signal electrode 21 includes a transparent electrode 43 and a metal electrode 4
4, the common electrode 22 is composed of a transparent electrode 45 and a metal electrode 46, and the metal electrode 4
The micro shutter 2 is removed by the removal section 47 of 4 and 46.
3 is formed. By placing a polarizing plate 48 thereon, a GH type liquid crystal light shutter 12 is constructed. The method for driving the liquid crystal light shutter used in the present invention will be described below. Figures 12a to 12d explain the dual-frequency drive in more detail using the GH type liquid crystal shutter, and Figure 12a shows the driving waveform of the liquid crystal light shutter. The frequencies f _H and f _L are repeated every time. Figure 12b shows the behavior of relative light transmittance at this time.
The fall time takes longer than the rise time. Grounding one electrode of the liquid crystal light shutter and applying an alternating voltage to the other electrode as shown in Figure 12a increases the cost of the drive unit, and
According to the use with LCD liquid crystal display), it is the first
As shown in Figure 2c, a signal with a voltage of 1/2 V and a phase of S is applied to one electrode, and a voltage of 1/2 V is applied to the other electrode.
If C is applied at V and the phase is opposite to S, the liquid crystal light shutter can equivalently be driven as shown in FIG. 12a. In Fig. 12c, *f _H and *f _L represent opposite phases to f _H and f _L , respectively. Specifically, this circuit is shown in Fig. 12 d. Become. Here SG is the data signal 4
9 is an inverter circuit, 50 is a high voltage output buffer circuit, and 51 is a liquid crystal light shutter. By the way, in an actual device, as shown in FIG. 4, many microshutters 23 are connected to a common electrode 22 via a signal electrode 21. This situation is shown in FIG. 13, where S1 to S4 are segment signals, C1 is a common signal, and 52 to 55 are microshutters. In this case, it is impossible to apply a common signal C1 that is always in opposite phase to the segment signals as shown in FIG. 12c. In order to consider this matter, we conducted the following experiment.
The results are shown in FIG. In the figure, one electrode will be referred to as S and the other as C. Figure 14 d shows the f _L signal indicated by b being applied to electrode S.
shows the response characteristics when electrode S and electrode C are grounded after the *f _L signal with the opposite phase is applied and the response becomes stable. Figure 14e shows the falling part of Figure 14d, This is an enlarged display of the time after time T ₀ . Figure 14 f shows the response characteristics when electrodes S and C are grounded after the f _L signal of b is applied to electrode S and the *f _H signal of opposite phase to a is applied to electrode C. After the response has stabilized, electrodes S and C are grounded. , and g is an enlarged display of the falling part of f, after time _T0 . In FIG. 14d, since an alternating voltage of voltage V and frequency f _L is applied until time T ₀ , the liquid crystal light shutter opens and stabilizes at light transmittance P ₂₀ . At time T ₀ , there is no signal, but as understood from d and e, it does not close immediately. In FIG. 14f, the superimposed signal 56 of f _L and f _H shown in c is applied until time T ₀ , and the light transmittance stabilizes at P ₃₀ . There is no signal at time T ₀ , and its behavior is shown in f and g, and P ₂₀ and P ₃₀ for d and e.
They behave in almost the same way, with the only difference being the start level of the fall. In this way, the liquid crystal light shutter can also be opened by the f _L and f _H superimposed signals (hereinafter referred to as f _L + f _H signals), and when compared with the light transmittance for the f _L signal, P ₃₀ /P ₂₀
×100=88%. This is important;
Driving using the method shown in FIG. 13 suggests that it is possible to apply the common signal C1 with an antiphase f _H , that is, an *f _H signal. Figure 14 d~
The light transmittance _P10 shown in g is due to light leakage when there is no signal, that is, when the GH type liquid crystal optical shutter is off, and this level is approximately equal to the level when the f _H signal, which is an off signal, is continuously applied. The repeated responses of the liquid crystal light shutter to the f _H signal and the f _L +f _H signal are shown in FIGS. 15a and 15b. In Fig. 15a, the f _H signal is applied for a period of T ₁ , and f _L + f _H
Repeat applying the signal for a period of _T2 . 15th
Figure b shows the response characteristics at this time. G's response is
This shows the case where T ₁ +T ₂ ≫ 1 ms, and the f _L + f _H signal can be substituted for the f _L signal in Fig. 14 f,
This shows the expected response based on the results shown in g. However, if, for example, T ₁ =T ₂ =1 ms, the light transmittance is fixed at the level of P ₁₀ as shown by H in FIG. 15b, and there is no on-response. The level of P ₁₀ is the light transmittance when the f _H signal is continuously applied as described above. When the ratio of T ₁ and T ₂ is changed so that T ₁ < T ₂ , a response as shown in J is shown, and it gradually shifts to the G side, but T ₂ = 0.5 ms,
When T ₂ =1 ms, it finally approaches the level of P ₃₀ , but it is far from a G-like response. From the above, it can be said that the f _L + f _H signal immediately after the f _H signal has little effect as an f _L signal, and gradually becomes effective as an f _L signal, and this operation is caused by the liquid crystal light in the present invention. This is important in determining the drive of the shutter. However, the cumulative effect of such f _H signals can be harmful in some cases. 16th
By inserting the f _L signal during the period T ₃ as shown in figure a, a response as shown in b can be obtained, and the accumulation effect caused by the f _H signal can be blocked. V = 30V, f _L = 5KHz,
f _H = 300KHz, T ₁ = 1ms, T ₂ = 0.5 at 45℃
ms, and the above was confirmed under the conditions of T ₃ =0.2 ms. It can be seen that driving with good repeat response can be achieved by inputting the f _L signal within such a fixed writing cycle and opening the liquid crystal optical shutter. Next, FIG. 17 shows a driving example in which the f _L signal is input within a constant period T even in the repetition of the f _L +f _H signal.
P ₂₀ and P ₃₀ correspond to Fig. 14, respectively, f _L signal,
This is the light transmittance when the f _L + f _H signal is continuously applied. Figure 18 shows a drive signal a in which part of the f _L + f _H signal is replaced with no signal, a drive signal b in which part of the f _H signal is replaced with no signal, and their response characteristics are shown in c. be. After that, the no-signal part is

It will be expressed as [0]. The response according to Figure 18a is indicated by K in Figure 18c, and in this case

[0] Period of T ₂ during which the signal is given,
As shown in FIG. 14 f and g, the light transmittance decreases, but if T ₂ is sufficiently short, there is no large drop. Further, the period T ₂ may be the f _L +f _H signal or the fL signal. The response according to Figure 18b is the first
In this case, it is shown in L of Figure 8 c.

During the period _T2 when the [0] signal is applied, the liquid crystal light shutter is already closed, so there is no problem. It goes without saying that the _fH signal may be used during the period _T2 . Furthermore, within this T ₂ period, f _L
When +f _H signal is applied, it rises early as shown in M shown in FIG. 18c. here,

This suggests the possibility that a nearly closed state can be maintained by combining the [0] signal and the f _L +f _H signal, and such a state can be effectively utilized when performing the time-division drive of the present invention. can. Figure 19 is

[0] When there is no signal, Figure 20 shows the common signal C ₁ and segment signal in the case where there is
S ₁ , S ₂ , and the signals S ₁ -C ₁ , S ₂ -C ₁ applied thereby to the liquid crystal light shutter, and their responses N, Q or R, U are shown in FIGS. 19 a to f and respectively. Shown in Figures 20a-f. FIGS. 21 and 22 show examples of drive circuits corresponding to FIGS. 19 and 20, respectively. Here, 57 is f _H signal,
58 represents the f _L signal, and 59 represents recording data. 21st
60 in figure a is the timing signal shown in b, and the 22nd
Reference numerals 61, 62, and 63 in Figure a indicate timing signals corresponding to those in Figure b. In the circuit configuration of FIG. 21, the f _H signal 57 is input to an AND circuit (hereinafter referred to as AND circuit) 64, and the f _L signal 5
8 is input to AND circuits 65 and 66, and record data 59 is input to a logic NOT circuit 67 (hereinafter referred to as a NOT circuit) and an AND circuit 66. AND circuit 6
The outputs of 4 and 65 are input to an OR circuit 68 (hereinafter referred to as an OR circuit), and the output of the OR circuit 68 is NOT.
It is input to a circuit 69 and an AND circuit 70. Also NOT
The output of the circuit 69 outputs a signal C via a buffer circuit 71. The outputs of the AND circuits 70 and 66 are input to an OR circuit 72, and the output of the OR circuit 72 is input to a buffer circuit 73.
It outputs a signal S via. On the other hand, the timing signal 60 is ANDed through an AND circuit 64 and a NOT circuit.
input to circuit 65; Furthermore, in the circuit configuration shown in FIG. 22, the f _H signal 57 and timing signal 61 are input to an AND circuit 74, the f _L signal 58 and timing signal 63 are input to an AND circuit 75, and the recording data 59 is input to an AND circuit 76. However, the timing signal 62 is input to an AND circuit 77. Also, the f _H signal 57 is NOT in the AND circuit 77.
input via circuit 78. On the other hand, AND circuit 79
The f _H signal 57 and timing signal 63 are NOT
is input through the circuit 80, and the f _L
Both signal 58 and timing signal 63 are input.
The outputs of AND circuits 79 and 81 are input to an OR circuit 82. Also, the input of the AND circuit 83 is an OR circuit 8.
2 and NOT circuit 84 are connected, and the outputs of AND circuits 83 and 76 are input to OR circuit 85,
The output of the OR circuit 85 outputs a signal S via a buffer circuit 86. On the other hand, the NOR circuit 87, which is a negative circuit of the OR circuit, has AND circuits 74, 75, 77.
The output of the NOR circuit 87 is inputted, and the output of the NOR circuit 87 outputs the signal C via the buffer circuit 88. In Figures 18 and 20

[0] Signal is high frequency
In addition to the purpose of reducing the power consumption of the liquid crystal by the f _H signal, when attempting to perform time-division driving, there is also a purpose of attempting to perform the cumulative response effect of the immediately preceding signal by combining signals. In Fig. 23, the drive shown in Fig. 20 is performed by the circuit shown in Fig. 22, and data is recorded as shown in Fig. 23a. The purpose is to record black dots. In this example, white −
One writing cycle is indicated by T, which records black-white-black-black-white. FIG. 23c shows the response characteristics. As mentioned above, the light is not completely cut off during the period during which black dots should be recorded. For example, Ta
Looking at the period between -Tb, not only is there a quantitative light leakage indicated by _P10 , but also a considerable amount of light is transmitted during the period indicated by Ta and Tb, and is irradiated onto the photoreceptor. Unless the absolute power is large, such as a laser beam, in other words, if the optical power is within the range where the so-called reciprocity law in silver halide photography or electrophotography almost holds true, the electrostatic charge on the surface of the photoreceptor will increase depending on the total exposure amount. Since the attenuation of the charge is determined, it becomes possible to form black dots. In addition, if many white areas are recorded and black areas become thin in the sub-scanning direction, that is, in the moving direction of the photoreceptor, the shape of the microshutter 24 in the sub-scanning direction shown in FIG. 4 may be shortened or changed. It is also possible to treat it by letting it happen. As mentioned above, the GH type liquid crystal light shutter has the characteristic of being normally off, and has the great advantage of being able to be visualized in the regular development process, making it extremely valuable for industrial use. It is a well-known fact that when a discharge lamp such as a fluorescent lamp is used as a light source, the constant light amount of the photoreceptor cannot be reached unless the temperature of the tube wall rises to a certain degree. For this purpose, preheat the lamp with a heater or turn on the lamp in advance. When warming up the equipment by turning on the lights in advance, if the machine is stopped, i.e. if the photoreceptor is not rotating, some parts of the photoreceptor will be exposed to a large amount of light and deteriorate due to light fatigue. Take measures to prevent light from hitting the photoreceptor by rotating the photoreceptor or installing a shutter during warm-up. However, since the liquid crystal light shutter used in the present invention is a normally-off type liquid crystal light shutter, it is closed when there is no signal. Therefore, there is an advantage that there is no need for any means to rotate the photoreceptor or to prevent the photoreceptor from being exposed to light during warm-up. Furthermore, if the heater is preheated while the light is turned on, the time required for stabilization can be further shortened. Next, the operation of the recording control section 4 for controlling information recorded on the liquid crystal shutter will be explained. 24 and 25a and 25b show a block diagram and timing chart of the liquid crystal optical shutter drive section 90 and print control section 91, respectively. The liquid crystal light shutter driving section 90 receives recording data 92 from the print control section 91 and executes driving of the liquid crystal light shutter. Recorded data 92 is a shift pulse 93
The signal is serially taken into the shift register 94 in synchronization with . The shift register 94 is a shift register that performs serial-in and parallel-out operations. When one row of data is taken into the shift register 94, a latch pulse 95 is sent to the data latch 96, and the data in the shift register 94 is read into the data latch 96, freeing the shift register 94 and moving the shift register 94 to the next row. Waiting to receive data for minutes. The data read into the data latch 96 is selected by the data selector 99 as either the ON drive signal 97 or the OFF drive signal 98, so that when the ON drive signal is input, the logic level output is output to the level shifter and high voltage driver. 100, and this signal becomes the segment drive signal for the microshutter 101. On the other hand, on the common electrode side of the microshutter 101, the common electrode signal 102 is converted into a drive signal by a level shifter and high voltage driver 103, and this drive signal is output to the common electrode of the microshutter 101. The output 104 of the shift register 94 can also be used as an output signal to the next stage shift register, allowing multi-stage connection. Next, the print control section 91 shown in FIG. 25 will be described. The external interface unit 105 exchanges various information such as commands and status with external CPUs and controllers in order to receive image information from the outside, and receives video signals. The video signal timing control section 106 controls the serial transfer of the recording data 92 to the liquid crystal optical shutter driving section 90 in synchronization with the writing cycle, so that the video signal timing control section 106 receives a signal from the liquid crystal optical shutter driving signal generating section 107 for one writing period T.
A signal 108 (b in the same figure) corresponding to is received. 9
3 and 95 are the aforementioned shift clock and latch pulse, and their respective timings are shown in FIG. 25b. The output of the oscillator 199 is frequency-divided by the divider 109 and sent to the liquid crystal optical shutter drive signal generator 107. Here, in addition to the above-mentioned role, a signal for driving the liquid crystal optical shutter, an on-drive signal 97,
An off drive signal 98 and a common electrode signal 102 are also generated and sent to the liquid crystal light shutter drive section 90. Incidentally, the image recorded by the recording apparatus shown in FIG. 2 is recorded on paper as shown in FIG. 26. The recording section where information is actually recorded on the paper 110 is 1.
It is 11. In this way, images are rarely recorded on the entire surface of the paper 110, and are recorded on the leading margin 112, the trailing margin 113, and the left and right margins 114, 115.
is often taken. Similar margins are often provided in electronic copying machines for various reasons, and as a means for this, some machines are equipped with an erasing lamp capable of full or partial exposure between the charging section and the developing section. However, the left and right margins 114, 11
5 differs depending on the type of recording paper 110, so it is necessary to divide the erase lamp into several blocks and selectively turn them on to erase the surface charge on the necessary portions. In addition, in the recording device, the interval 116 of the recording paper 110 is
is a margin for avoiding collision with the next recording paper due to slips, skews, etc. of the recording paper 110, and the smaller it is, the higher the actual recording speed will be. As described above, the recording portion 1 on the recording paper 110
The area other than 11 and the paper interval 116 are irradiated with light while the charging unit 2 is operating in FIG. It is desirable to do so.
It will be appreciated that for this purpose, the microshutter of the liquid crystal light shutter 17 of the recording device can be opened and used in place of the erase lamp.
Further, by using the liquid crystal light shutter 17, there is no need for an erasing lamp, and there is an advantage that each of the above-mentioned blank areas can be precisely controlled. Now, the size of recording paper handled by the recording device is A3.
Approximately 3000 when the recording density is 10 dots/mm.
A dot/row microshutter is required. Static driving of a liquid crystal optical shutter with such a large recording capacity increases the number of drive elements, the number of wiring lines, and the mounting area, which causes an increase in costs.In addition, as the recording density increases, difficulties arise in mounting technology such as wiring and connections. accompanies. Therefore, it may be possible to compensate for the above drawbacks by performing time-division driving. Next, problems when time-division driving is performed on a liquid crystal light shutter will be described with reference to FIG. 27, although the problems overlap with those of the prior art. The microshutters 117 arranged in a straight line are
The write selection electrode is C1.
~Cn and n recording signal electrodes S1~Sm
It consists of m pieces. It is assumed that the direction of movement of the photoreceptor, that is, the sub-scanning direction, is the direction of the arrow shown by c in the figure, and time-division driving is performed as shown in b in the figure. The write selection electrodes C1, C2,...Cn are 121, 1, respectively.
Timing signals 22, . . . 123 are input. Micro shutters 11 lined up in a straight line like this
7, due to the difference in recording time due to time-division driving, a time delay occurs due to time-division driving when recording should be performed as shown by the dotted line 118 in FIG.
The image is recorded obliquely on the photosensitive surface of the photoreceptor, as shown in FIG.
The skew angle 120 is within the moving distance of the photoreceptor corresponding to the time-division writing period Tw. As described above, when a liquid crystal optical shutter is used as a recording device, time-division driving in the same manner as a display device is unsatisfactory in terms of a reduction in exposure amount and recording quality. The present invention takes these points into consideration and provides a new time-division drive system. The n time division drive according to the present invention will be explained below. For ease of explanation, the minimum time division is n=
An example where n=2 or n=3 will be described below. FIG. 28 shows the configuration of a liquid crystal light shutter based on two-time division drive with n=2. Here, transparent electrodes are placed at the intersections of the two write selection electrodes 124 and 125 and the recording signal electrodes 128 to 131, which are placed alternately in order to increase the aperture ratio of the shutter and to facilitate later wiring. The formed micro shutters 136, 137, etc. are provided. 163 represents the moving direction of the photoreceptor, that is, the sub-scanning direction. As mentioned above, let us take an example in which, according to the conventional two-time division drive, white-black-white-white-black is recorded on the microshutters 136, 137, etc. on the write selection electrodes 124, 125, respectively. Recording signals are provided to recording signal devices 128-131 to indicate the optical response as shown in FIG. Here, Tw indicates the write cycle. As can be understood from the figure, in the conventional n time division drive, the recording operation can only be performed within the selected period Tw/n.
Therefore, the shutter is always closed within the period of Tw/n, and the shutter is closed during the non-selection period (1-1/n).
n) Tw is closed. In the time-division drive of the present invention, the write selection signal does not cause the shutter to close within the selection period Tw/n, and during the non-selection period (1-1/n) Tw, the recording state is based on the recording signal at the time of the previous selection. The driving method is described below. In FIG. 28, write selection electrodes 124,1
25 has a write selection signal 126 shown in FIG.
127 and allocate the first half or the second half of Tw to the selection period, respectively. Recording signal electrode 128-1
The recording signal given to 31 is given as one of 132 to 135 as shown in FIG. Recording signal 1
32 turns on the microshutter 136 when the write selection electrode 124 is selected, and also turns on the write selection electrode 1
This is an on-on recording signal that turns on the microshutter 137 when No. 25 is selected. Similarly, the recording signal 133 is on-off, 134 is off-on,
135 is an off-off recording signal. The drive signal applied to the microshutter 136 on the write selection electrode 124 is as shown in FIG.
8, on-off drive signal 1 by 133-126
39, 134-126, an off-on drive signal 140, an off-off drive signal 198, 135-126. The drive signal applied to the microshutter 137 on the write selection signal electrode 125 is Tw/
It is equivalent to two phases delayed. Such drive signals are transmitted to the micro shutter 136.
The photoresponse characteristics when given to 141 to 14 are shown in the same figure.
Shown as 4. On-on drive signal 13 respectively
8 to off-off drive signal 198.
Here, the response of 142 which tends to close with an on signal and the response of 143 which tends to open with an off signal is that during the non-selection period 145, there is no signal.

This depends on whether [0] is given or the superimposed signal f _L +f _H is given. When capturing the microshutter 136, if the on response 142 can be made to the same level as 141 and the off response 143 to the same level as 144, then
During the non-selection period, it is possible to drive so that the recording state at the time of the previous selection continues until the next selection, resulting in apparently static drive despite the time-division drive, and the exposure time is reduced by 1/2.
longer than n, sufficiently exposing the photosensitive surface of the photoreceptor,
The effect is great. In the recording signals 132 to 135 shown in FIG. 31, a period in which the f _L signal is applied is provided at the end of the first half and the second half of Tw/2, as indicated by TL. As shown in FIG. 30, the second half TL period corresponds to the TL period 146 of the write selection signal 126, and the first half corresponds to the TL period 241 of the write selection signal 127, and the f _L signal is applied at the end of the write period Tw. This is to drive the liquid crystal light shutter to open, and the steps to cut out the hysteresis caused by high frequencies are the same as those described above. Write selection signals 126, 127 shown in FIG.
has a selection period 148, 149 indicated by the *f _H signal, and more precisely a period 1 corresponding to the TL period.
The period 196,150 excluding the period 47,195 becomes the actual selection period. The drive signal in the non-selection period 145 in the two-time division driving example shown in FIG. 32 is the f _H signal in the non-selection period 151 of the write selection signal 126 in FIG.
It is generated by recording signals 132 to 135 shown in FIG. The second half of recording signals 132 to 135 Tw/
Although it is impossible to change the signal between the second half and the first half, the write selection signals 126 and 127 can change the signal during the non-selection period to some extent, and the following study was carried out. As described in Figures 14 to 16, after opening the liquid crystal light shutter,

In order to further pursue the phenomenon that the signal does not close immediately with the [0] signal, and that it does not immediately open with the f _L +f _H signal immediately after closing with the f _H signal, the I tried changing the signals in the selection periods 151 and 152. Note that the write selection signal 127 in FIG. 30 is in phase with 126.
Since the effect is the same with only a difference of 180°, the write selection signal 126 will be described below. Waveforms 153 to 156 in FIGS. 33 to 36 show a situation in which part of the f _H signal portion 151 during the non-selection period of the write selection signal 126 in FIG. 30 is replaced with the f _L signal, and the f _L signal portion is 156a, 156b, 156
Each is represented by c. The optical response characteristics when such write selection signals 153 to 156 are applied are shown in FIGS. 33 to 36b, respectively. The light transmittances P ₁₀₀ , P ₂₀₀ , and P ₃₀₀ are determined when the f _H signal is continuously applied, and when the f _L signal is continuously applied, respectively.
It shows the optical response when the f _L + f _H signal was continuously applied. Photoresponse 141a, 141b, 141ac, 14
1bc is the on-on recording signal 132 in FIG. 31,
Photoresponse 142a, 142b, 142ac, 142
bc is the on-off signal drive 133, the photoresponse 14
3a, 143b, 143ac, 143bc are off-
The on recording signal 134 is transmitted to the optical responses 144a, 144.
b, 144ac, and 144bc are the results when the off-off recording signal 135 is applied, respectively, and the behavior of the photoresponse characteristics during the selection period 0 to Tw/2 and the non-selection period Tw/2 to Tw is shown at 141 in Fig. 32. ~14
A comparison with those of 4 is as follows. The signal applied to the liquid crystal light shutter during the non-selection period Tw/2 to Tw is the recording signal 1 shown in FIG.
When the write selection signal 126 in FIG. 30 is used for 138 to 135 as shown in FIG.
There are two types of signals such as 141, and one example of FIG. 36 is shown in FIG. 37 when other write selection signals 153 to 156 are used as shown in each a of FIGS. They are shown as waveforms 157-160. Here again, there are two types of drive signals, 161 and 162, in the non-selection period from Tw/2 to Tw, that is, in n time division driving, 2 ^n-1 combinations are generated. As mentioned above, if the write selection signal in FIG. 30 is used, one of the on-responses 14 in FIG.
2. One of the off responses 143 was unsatisfactory,
By changing a part of the non-selection period f _H signal portions 151 and 152 of the write selection signals 126 and 127 shown in FIG. 30 to the f _L signal, the optical response as shown in FIGS. 33 to 36 is obtained. 36, on-response 141b and 142b or 141bc and 1
42bc, off response 143b and 144b or 1
43bc and 144bc operate in almost the same way. As already mentioned, when the light intensity is within the range where the reciprocity law in silver halide photography and electrophotography is approximately satisfied, the attenuation of the electrostatic charge on the surface of the photoreceptor is determined by the total amount of exposure. By setting the on-response or off-response to approximately the same level as described above, white or black dots can be recorded in the same manner, respectively. As described above, in n time division driving, according to the driving method of the present invention, there are 2 ^n-1 combinations of drive signals given during the non-selection period, and no matter what kind of driving is performed during the selection period, During the non-selection period, the state of the selection period Tw/n is changed to the non-selection period (1-1/n) by effectively utilizing the cumulative effect of the liquid crystal.
The effect is great because the exposure time can be continued for Tw, which looks similar to static drive, and the exposure time is not reduced to 1/n. Furthermore, the 30th
In Figures 1 to 36, driving was performed at f _H =300 KHz, f _L =5 KHz, voltage 30 V, Tw = 2 ms, and liquid crystal temperature 45°C. In the two time division drive configuration shown in FIG.
The writing cycle is Tw, and the micro shutter 136
white-black-white-white-black, micro shutter 137
FIG. 38 shows optical responses as waveforms 163 and 164 when driven to record white-black-black-white-black dots, respectively. When compared with the optical response by conventional two-time division drive shown in Fig. 29, the selection period Tw/2 (generally
It can be seen that since the shutter is not always closed after Tw/n) and the period of one given write cycle Tw is effectively utilized, it appears to be close to static drive. In FIG. 28, microshutters 136 and 1
37 in the sub-scanning direction 163 is set to a length explained below. In the write period Tw, as described above, the write selection signal of the microshutter 137 is applied with a delay of Tw/2 relative to that of the microshutter 136. Therefore, during this Tw/2, the photoreceptor also advances by Tw/2 in the sub-scanning direction 163, and as shown in FIG.
In order to record on a straight line as shown in 118, the micro shutter 137 is
Letting the recording density in 63 be D, l=(k+
1/2) It is easy to understand that it needs to be D. Here, k is an integer of 0, 1, 2, .
Recording density D is given by D=V・where V is the sub-scanning speed.
Since Tw, it can be expressed as l=(k+1/2)V・Tw. When k=0, it means that the recording data given to the microshutter 137 is data on the same line as that given to the microshutter 136, but k≠
When it is 0, the recording data given to the microshutter 137 must be given k lines later than that given to the microshutter 136, so a data delay circuit, line buffer, etc. are required. In general, the interval l between staggered microshutters in n time-division driving is l=(k+1/n)D=(k+1/
n) can be expressed as V・Tw, the 28th, 4th
As shown in FIG. 1, even in n-time division driving, if microshutters are arranged in a staggered manner and recording data is applied as described above, recording can be performed in a straight line as shown at 118 in FIG. 27c. The liquid crystal optical shutter drive circuit in time-division driving will be described below. In FIG. 28, the micro shutter 136,1
37 in the sub-scanning direction 163 is l=(k+
1/n)D (n=2 in this example), and unless k≠0, the data recorded to the microshutter 137 is delayed by k lines, that is, k·Tw, from that of the microshutter 136. As already stated, it must be done. In view of these circumstances, the configuration of a liquid crystal light shutter drive circuit in time division driving will be described using FIG. 39, taking two time division driving as an example. The drive circuit has two functions depending on how recording data is given.
One method is shown in FIG. The total number of liquid crystal light shutters 197, 165 is assumed to be m (m is an even number). Microshutters 197 and 165 correspond to 136 and 137, respectively, in FIG. The liquid crystal optical shutter drive circuit 166 includes an m-bit shift register 167 and an m-bit data latch 16.
8. Consists of an m-bit data selector 169, a level shifter, and high-voltage drivers 170, 171, and alternately receives m bits of recording data for the microshutter 197 and recording data for 165 delayed by k lines within the write cycle Tw. I do. Based on the mixed recording data transferred to the data latch 168, the data selector 169 selects one of the recording signals 172 and sends it to the level shifter and high voltage driver 170. The recording signal 172 is 132 to 135 in FIG.
This corresponds to Write selection signal 173
is the level shifter and high voltage driver 1
71 becomes the write selection drive signals 174 and 175, which correspond to, for example, the signals 154 and 154 in FIG. 34a delayed by Tw/2, and the second
The write selection electrodes 124 and 125 shown in FIG. 8 are respectively driven. Reception of recorded data is the 39th
As shown in the figure, the mixed recording data 177 is received into the m-bit shift register 167 as described above in synchronization with the write period signal 176, and the latch pulse 17
8, the data is transferred to the data latch 168. Another example of a liquid crystal light shutter drive circuit is shown in 179, and m/2 bit shift register 180, m/2
Consisting of a bit data latch 181, m/2 bit data selector 182, level shifter and high voltage drivers 170, 171, the recording data to the microshutter 197 and the recording data to the microshutter 165 delayed by k lines are stored in the write cycle Tw. Reception is performed separately in the first half and second half. The data selector 18 receives the separated recording data transferred to the data latch 181.
2, one of the recording signals 183 is selected and sent to the level shifter and high voltage driver 170. The recording signal 183 is 132, 13 in FIG.
This corresponds to 5. As shown in FIG. 39, the recording data 186 separated into waveforms 184 and 185 as described above is received by the shift register 180 in synchronization with the write synchronization signal 176, and is transferred to the data latch 181 by the latch pulse 187. . The recorded data 184 is for the microshutter 197, and the recorded data 312 is for the microshutter 16 separated by an interval l.
5 is delayed by k lines. As shown in the two examples above, no matter which driving method is used, 2 ^n-1 driving signals will be applied in the non-selected state. Next, the operation during n time division driving will be explained using an example of three time division driving. FIG. 40 shows the optical response characteristics during three time division driving. Here, the optical response waveforms 191, 192, and 193 when the microshutters 188, 189, and 190 shown in FIG. 41 are driven to record white-black-white-white-black-black are shown, respectively. . The selection periods given to the write selection electrodes 194, 195, 196 are 191a, 192, respectively.
a, 193a, and can be generally expressed as Tw/n. Regardless of whether 166 or 172 shown in FIG. 39 is used as the drive circuit, 1 shown in FIG.
Selection period 191 for 91, 192, 193
a, 192a, and 193a, that is, the non-selection period (1-1/n) Tw is the selection period Tw/n.
By providing a drive that produces an appropriate cumulative effect so that the drive state continues, it appears to behave like static drive, and it is possible to prevent a significant decrease in exposure time. Liquid crystal light shutter drive circuit 166, 1 in FIG.
In the example of No. 79, recording data is received serially, but it is of course possible to receive it in parallel (for example, 8-bit parallel), and parallel reception has the advantage of shortening the transfer time of recording data. Next, an example of actual printing using the above-mentioned recording device will be described. As shown in Figure 11, a liquid crystal mixture containing 1.5% by weight of a disazo dichroic dye was prepared using Merck &Co.'s ZLI-2461 dual-frequency driving liquid crystal, with a liquid crystal layer thickness of 4.
It was kept at ~5 μm and sealed. Microshutters of 90 μm square were arranged at a density of 10 pieces/mm as shown in FIG. 28, and the staggered interval l was 250 μm. An 18W aluminate fluorescent lamp is used as the light source, and a Japanese sheet glass self-occurring lens (θ) is used as the condensing lens.
= 20°) was used. A functionally separated organic photoreceptor was used as the photoreceptor, and the photoreceptor was moved at a rate of 50 mm/sec. Store the liquid crystal light shutter at 40 to 45°C, and in the two-time division drive shown in Fig. 37, T ₁ = 0.8 ms, T ₂ = 0.2 ms, f _L = 5K.
Hz, f _H = 300KHz, voltage V = 30V, write cycle
After optical writing was performed at Tw=2 ms, an image with a recording density of 10 dots/mm at approximately 100 μm ⁰ □ was obtained by regular development. According to the time-division driving method of the present invention described above, it is possible to open and close a liquid crystal light shutter without significantly reducing the exposure time, and it has great industrial utility value. Although the present invention has been described in relation to a normally-off type liquid crystal light shutter using a GH type liquid crystal, the present invention is not limited to this, and the present invention can be used to open and close a liquid crystal light shutter of other configurations, such as a TN type. It is also possible. [Effects of the Invention] According to the present invention configured as described above, it is possible to provide an optical recording device using a liquid crystal optical shutter that enables optical writing regardless of the brightness of the light source, and further provides a high recording density and high speed. This has the effect that an optical recording device with high recording quality can be constructed in a small size, with high reliability, and at low cost.

[Brief explanation of drawings]

Fig. 1 is a timing chart using the conventional liquid crystal shutter driving method, Fig. 2 is a block diagram of the recording device, Fig. 3 is a block diagram of the liquid crystal light shutter section of the recording device, and Fig. 4 is the liquid crystal display of the recording device. Panel configuration diagram; Figures 5a and 5b are diagrams showing the operating modes of guest-host type liquid crystal; Figures 5c and d are diagrams showing the operating mode of TN type liquid crystal; Figure 6 is for dual-frequency drive. Dielectric anisotropy characteristic diagram of liquid crystal, Figure 7 is absorbance characteristic diagram of liquid crystal in which dichroic dye is dissolved, Figure 8 is spectral transmittance characteristic diagram of the guest-host liquid crystal shutter used in the present invention, and Figure 9. 10 is a spectral characteristic diagram of the aluminate fluorescent lamp used in the present invention, FIG. 10 is a spectral transmittance characteristic diagram of a TN type liquid crystal light shutter whose polarizing plate has UV cut characteristics, and FIG. 11 is a spectral transmittance characteristic diagram of the aluminate fluorescent lamp used in the present invention. A cross-sectional view of the GH type liquid crystal light shutter used, Figures 12a-d are configuration diagrams explaining the basics of response characteristics by dual-frequency drive,
The figure is a circuit diagram for examining the driving method for reducing the number of common electrodes to one, Figures 14a to 14g are waveform diagrams showing experimental examples for examining the driving method used in the present invention, and Figure 15a is , b, Fig. 16 a, b, Fig. 17 a,
b, FIGS. 18a and b are waveform diagrams of driving examples used in the present invention, FIG. 18c is a light transmittance characteristic diagram, and FIGS. Waveform diagrams illustrating a driving example in more detail, FIG. 21a,
b, Figures 22a and b are respectively Figures 19 and 20.
23a and 23b show driving examples according to the present invention, c is a waveform diagram showing the response characteristics of the GH type liquid crystal optical shutter, and FIG. 24 is a block diagram showing an example of the configuration of the FP type control section. 25a and 25b are the liquid crystal optical shutter drive unit used in the present invention, a timing diagram and a waveform diagram, and FIG. 26 is a configuration diagram for explaining the control of the effective image area on recording paper according to the present invention. FIG. 27 is a configuration diagram for explaining the n-time division drive, FIG. 28 is a configuration diagram for explaining the configuration of the microshutter in the two-time division drive, and FIG.
The figure is a photoresponse characteristic diagram for conventional two-time division drive, Figure 30 is a write selection signal waveform diagram for explaining two time division drive according to the present invention, Figure 31 is a recording signal waveform diagram, and Figure 32 is a drive Waveform diagrams showing signals and their optical response characteristics; Figures 33 to 36 are waveform diagrams illustrating consideration of write selection signals in two-time division driving according to the present invention; Figure 37 is a waveform diagram showing one drive signal; FIG. 38 is a waveform diagram showing the optical response characteristics when the driving method shown in FIG. 37 is used, and FIG. 39 is a driving block diagram of the liquid crystal optical shutter used in the present invention. FIG. 40 is a waveform diagram illustrating the optical response by three time division driving according to the present invention, and FIG. 41 is a diagram showing the configuration of the microshutter according to the present invention. 1... Photoconductive recording body, 2... Charging section, 3...
Optical recording section, 4... Recording control section, 5... Development section, 6
... Recording paper, 7 ... Paper feed roll, 8 ... Standby roll, 9 ... Transfer section, 10 ... Separation section, 11 ... Fixing section, 12 ... Paper discharge roller, 13 ... Static elimination section, 1
4...Cleaning section, 15...Eraser, 16
... Light source, 17, 28, 40, 51 ... Liquid crystal light shutter, 18 ... Condensing lens, 19, 20 ... Glass substrate, 21 ... Signal electrode, 22 ... Common electrode, 23, 188, 189, 190... Micro shutter brush, 24... Liquid crystal panel, 25...
GH type liquid crystal cell, 26, 34...liquid crystal molecule, 2
7, 35, 36, 48...polarizing plate, 29, 37...
...Incoming light, 30...Dye molecules, 31...Polarized light,
32, 38, 39... Output light, 33... TN type liquid crystal cell, 41... Spacer, 42... Liquid crystal mixture for dual frequency drive, 43, 45... Transparent electrode, 44,
46...Metal electrode, 47...Removal section, 49...Inverter circuit, 50...Buffer circuit, 52,5
3, 54, 55, 101, 117, 136, 13
7,165,188,189,190,197...
...Micro shutter, 56...Superimposed signal, 57...
...f _H signal, 58...f _L signal, 59, 92...Record data, 60, 61, 62, 63...Timing signal, 64, 65, 66, 70, 74, 75, 7
6, 77, 79, 81, 83...AND circuit, 6
7, 69, 78, 80, 84... logical negation circuit,
68, 72, 82, 85...OR circuit, 71,
73... Buffer circuit, 90... Liquid crystal light shutter drive section, 91... Print control section, 93... Shift pulse, 94, 167, 180... Shift register, 95, 178, 187... Latch pulse, 9
6,168,181...data latch, 97...
On drive signal, 98...Off drive signal, 99,1
69,182...Data selector, 100,10
3,170,171...High voltage driver, 102...Common electrode signal, 104...Final output, 105...Interface section, 106...
Timing control section, 107... Signal generation section, 10
8... Signal, 109... Divider, 110...
Recording paper, 111... Recording section, 112... Leading edge margin, 113... Trailing edge margin, 114, 115...
Left and right margins, 116...paper spacing, 118...dotted line, 119...solid line, 120...skewness, 12
1, 122, 123...timing signal, 12
4,125...Write selection electrode, 126,12
7,173...Write selection signal, 128-131
...recording signal electrode, 132-135,172,1
83...recording signal, 138...on-on drive signal, 139...on-off drive signal, 140...
Off-on drive signal, 198...Off-off drive signal, 142...Waveform that tends to close with an on signal, 143...Waveform that tends to close with an off signal,
145...Non-selection period, 146...TL period, 1
47,195...Period corresponding to the TL period, 14
8,149...selection period, 150,196...actual selection period, 151,152...non-selection period,
153, 156...f _L signal replacement waveform, 157~1
60... Waveform, 161, 162... Drive signal, 1
63,164...Photoresponse waveform, 166,179...
...Liquid crystal optical shutter drive circuit, 174, 175...
Write selection drive signal, 176...Write synchronization signal, 177...Mixed recording data, 184, 18
5... Separated recording data, 186... Recording data, 191-193... Optical response waveform.

Claims (1)

[Claims] 1. An optical recording section that performs optical writing corresponding to an image signal on a photoconductive recording medium, the optical recording section includes a light source, a plurality of recording signal electrodes, and a plurality of writing selection signal electrodes. a liquid crystal light shutter in which a plurality of microshutters formed by these electrodes are arranged in dots; an imaging optical system; In a recording device that selectively drives at two frequencies, a frequency higher than a specific frequency fc and a frequency lower than the specific frequency, the plurality of write selection signal electrodes are driven at a frequency fH higher than the specific frequency _fC and a frequency f lower than the specific frequency _fC . a first supply means that sequentially supplies a write selection signal consisting of _L with a phase different by a period T _W /n obtained by dividing the write period T _W by n _; or a second supply means for supplying a recording signal consisting of f _H and f _L and having the same amplitude as the write selection signal, and the recording signal supplied from the second supply means is The f _L signal has a predetermined phase over the entire period T _W /n obtained by dividing the write cycle T _W into n, or the front part of the period T _W /n has a predetermined phase.
The latter part of the _fH signal is the _fL signal having the predetermined phase, and the write selection signal supplied from the first supply means is used for the selection period during which the microshutter is selected by the write selection signal. of phase
The f _H signal is an f _H signal having an opposite phase, and includes a non-selection period in which the microshutter is not selected by the write selection signal, a frequency f _H and a frequency f _L having an opposite phase to the frequency f _L ; The signal waveform applied to the microshutter during the selection period is determined by the write selection signal and the recording signal to be a superimposed waveform of frequencies f _L and f _H over the entire selection period, or a waveform of frequency f _H at the front part of the selection period. The rear part is a superimposed waveform of frequencies f _L and f _H , and this signal waveform sets the microshutter in the open or closed state, and during the non-selection period,
The signal waveform applied to the microshutter is
Due to the write selection signal and the recording signal, the rear part of the non-selection period is a waveform with frequency f _L and the front part is a waveform including a superimposed waveform of frequencies f _L and f _H or a 0V waveform, and this signal waveform causes the microshutter to be immediately What is claimed is: 1. A recording device that is driven to substantially continue an open/closed state set during a selected period of time. 2 The write selection signal in the non-selection period is a combination signal of the f _H signal of the predetermined phase, the f _H signal of the same phase, and the f _L signal of the predetermined phase in the front part, and the f _L signal of the predetermined phase in the rear part. The recording device according to claim 1, characterized in that the f _L signal is of opposite phase.