JPH02125228A - Optical write liquid crystal light valve and image output device using the same - Google Patents

Abstract

PURPOSE:To write and project an image from the same side by forming a dichroic filter which transmits light with long wavelength in a certain wavelength range between a ferroelectric liquid crystal layer and a photoconductive layer and reflects light with short wavelength. CONSTITUTION:The upper limit of the wavelength range of light projected on a liquid crystal light valve is >=100nm different from the wavelength of writing light to the liquid crystal light valve and the dichroic filter 7 which transmits the wavelength of the writing light, but reflects the wavelength of the projected light is arranged. Namely, the dichroic filter 7 in the liquid crystal light valve is nearly 100% in transmissivity in the transmission range and almost 0 in transmissivity in the reflection range. Consequently, the writing to the liquid crystal light valve is performed from the same side with the projection of the projected light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical writing type liquid crystal light valve, and a high-definition digital image output device and printer using the same.

[Summary of the invention]

The present invention uses a ferroelectric liquid crystal having threshold characteristics and bistable memory properties in the liquid crystal layer, and maintains the directors of liquid crystal molecules uniformly aligned over the entire surface by applying a DC bias voltage that is sufficiently larger than the threshold voltage. After passing through the first step, an image is written by optical scanning using a radar beam or LED while applying a voltage that has the opposite polarity to the first step and is below the threshold voltage when in the dark and above the threshold voltage when irradiated with light. The second step is to create a liquid crystal light valve that represents the digital image signal as a two-dimensional image, and to obtain an output image by projecting and exposing the image written on the liquid crystal light valve onto another photosensitive zone and developing it. In the image output device, the wavelength sense between the wavelength of the writing light source of the liquid crystal light valve and the wavelength used for the projection exposure is 100 nm.
By setting a gap of at least m or more and using a wavelength filter that transmits the writing light and reflects the projection light through the total reflection film used in the liquid crystal light valve, the four-way insertion and projection of the liquid crystal light valve can be performed from the same side. , thereby realizing miniaturization of the entire image output word.

[Conventional technology]

For liquid crystal light valves that use light as a light source, various addressing methods and display modes of the liquid crystal used have been proposed. Addressing methods include an optical writing type that combines liquid crystal and a photoconductive film, and a thermal writing type that uses laser light.The display mode of liquid crystal is SmA phase transition.

These include Ne-ah phase transition, DSN, TN, STN, etc.

In the case of the laser thermal aging type, it takes several microseconds or more to image one pixel, and it takes many minutes to age a large screen at high density, so its applications are limited. . In the case of the optical writing type, the intensity is one to two orders of magnitude higher than that of the old laser heating type, so it is possible to perform high-speed writing, and it is expected to be used for video display, etc. However, in conventional optical writing type liquid crystal light valves, the visible light transmittance of the photoconductive layer is extremely low in most cases. It is a reflective liquid crystal light valve that has a light reflective layer formed on top of the film, irradiates projection light from the side opposite to the reading side, and projects and displays the image information reflected by the reflective layer on a screen, etc. Ta. Therefore, as the projection light at this time, light with a spectrum covering the entire visible light range is often used, and as the writing light, a laser diode with a near-infrared oscillation wavelength is often used, and the light reflecting layer is The one that almost completely reflects the entire visible light range was used.

FIG. 4 shows a configuration diagram of an image output device using such a reflective optical writing type liquid crystal light valve.

In FIG. 4, the liquid crystal light valve 17 is first
The image is scanned by the laser scanner 51. At this time, the main scanning direction of the laser scanner 51 is perpendicular to the plane of the paper, and the sub-scanning direction is the direction of arrow A in the figure.After writing the 0 image, the liquid crystal light valve 17 , and move to position 11 according to arrow B, and the image thereof is projected onto microcapsule paper 20 by a projection optical system. This projection optical system includes a light source, 10° condenser lenses 11 and 14. Heat ray cut filter 12, color filter 13. Field lens 15. Polarizing plates 16 and 18. Consisting of a projection lens 19,
The polarizing plates 16 and 18 are set so that they are in a crossed nicol state when no image is written on the liquid crystal light valve 17. Therefore, a bright and dark pattern is formed on the microcapsules 20 according to the image stored in the liquid crystal light valve 17.

As shown in FIG. 5, the microcapsules 20 have three types of microcapsules 20 a and 20 on a sheet.
b, 20c are dispersed and coated, and the microcapsules are 450nm, 550nm, and 550nm, respectively.
It is photocurable with maximum sensitivity at 650 nm,
Each contains leuco dyes that produce yellow, magenta, and cyan colors. Therefore, the microcapsule Gion 2
When 0 is illuminated, some parts of the microcapsules harden and others do not harden, depending on the light and dark pattern. This process is 3f! Prepare a type 1 color filter and the corresponding image data and repeat 51.Next, this microcapsule paper and a receiver paper coated with a coloring agent are layered and pressed together with a pressure roller to remove the uncured microcapsules. The dye flows out and reacts with the coloring agent, forming a colored image on the Lember Gi.

[Problem to be solved by the invention]

However, in the conventional image output device using a liquid crystal light valve as described above, as can be seen from Figure 4, a reading optical system such as a laser scanner is placed above the liquid crystal light valve, and a reading optical system such as a laser scanner is placed below the liquid crystal light valve. A projection optical system was disposed at , and the overall shape of =2 was large in the vertical direction.

[Means to solve the problem]

Therefore, in the optical writing liquid crystal light valve of the present invention and the image output device using the same, in order to perform writing and projection of the optical writing liquid crystal light valve from the same side, the upper limit of the wavelength range of the projection light irradiated to the liquid crystal light valve is In addition to separating the wavelength of the writing light into the liquid crystal light valve by at least 100 nm, a dichroic filter is installed in place of the total reflection mirror of the nuclear liquid crystal light valve, which transmits the wavelength of the writing light and reflects the wavelength of the projection light. Established.

[Effect]

The dichroic filter in the above-mentioned liquid crystal light valve has a transmittance close to 100% in the transmission region, and has a transmittance of nearly 100% in the reflection region.
3 pass rate can be approximately O. Therefore, writing to the liquid crystal light valve can be performed from the same side as the projection light irradiation.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a liquid crystal light valve according to the present invention. A non-reflective coating 2 is applied to the outside of the transparent substrate 1, and a transparent electrode 3a is applied to the inside of the transparent substrate 1.
, a liquid crystal alignment film 4a is formed.

Further, on the inside of the substrate 5, an opposing transparent TL pole 3b, an optical exclusive layer 6. Dichroi Fuku Filter 7. A liquid crystal alignment film 4b is formed. These pair of substrates are overlapped by a peripheral seal 8 containing a spacer material such as glass fiber,
A ferroelectric liquid crystal 9 is sealed in the gap. Two transparent electrodes 3 of the liquid crystal light valve formed in this way
A suitable bias voltage is applied between a and 3b, and image information to be projected and displayed is written with light from the side of the transparent substrate 1 using an optical writing means such as a laser beam or an LHD.

Light s irradiated? ? trpt 6 generates carriers and enters a low resistance state, and the applied bias voltage is applied to the liquid crystal layer in a resistance-divided manner to excite the liquid crystal molecules. The region that is not irradiated with light maintains a high 1° resistance, so that almost no voltage is applied to the liquid crystal molecules, and the liquid crystal molecules are not excited.

An optically written liquid crystal light valve using a ferroelectric liquid crystal with threshold characteristics and bistable memory properties cannot take an intermediate state and is always in an on state or an off state. Unless a voltage higher than the threshold voltage is applied, strong pressure, or a temperature high enough to cause a change in the liquid crystal layer, it is maintained semi-permanently. The image captured in this manner can be projected and displayed on a screen using a reflective projection device as shown in FIG. 4, or can be projected and exposed onto another flashing body.

Below, we will specifically explain the differences between this embodiment and the conventional example. For example, the dichroic filter 7 in FIG. Obtained by forming a film. Therefore, if an image is written using a semi-five-body laser with a wavelength of 780 nm as a writing light source, the captured light will pass through the guichroic filter 7 at approximately 100 Vo (approximately 100 Vo), reach the light guide tFJ 6, and write. .

Note that the original thick conductive layer 6 may be an organic photoconductive film, a Se-based film,
An a-St-based photoconductive film or the like can be used.

Next, if projection irradiation is performed using the optical system shown in FIG. 4 using light with a wavelength of 600 rv or less, the projection light will be reduced to approximately 100 Vo by the dichroic filter 7, without affecting the written image. , the image can be projected. Therefore, by placing a microcapsule paper on the projection image plane, for example, 420nm, 490n+w,
Using three types of light sources with a peak emission power at 560 nm, it is possible to obtain a color image by projecting an image that has been captured according to each light source and performing pressure development, as in the conventional example. can. Incidentally, as an example of this microcapsule paper, Cycolor paper has been released by Mead Company of the United States. Further, the three types of light sources described above can be obtained, for example, by passing the light from one light source through a 34 mm wavelength selection filter.

The configuration of the optical system of the image output device at this time is shown in Figure 2.
The projection optical system is the same as the conventional example shown in FIG. However, since writing can be done from the same side as the projection lens, the laser scanner 51 is placed on the same side of the liquid crystal light valve 17 as the projection lens. Note that here a laser scanner is used as the image capture gTl, but
Optical writing devices, such as LED scanners and fortune-telling scanners using liquid crystal heads, are available for recording purposes.

〔Effect of the invention〕

As described above, by using the liquid crystal light valve of the present invention, image writing and projection can be performed from the same side. The size of the device in the axial direction can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the image output device of the present invention, FIG. 2 is a cross-sectional view showing the structure of the liquid crystal light valve of the present invention, and FIG. 3 is a graph showing the spectral 133yI ratio characteristic of the dichroic filter. Figure 4 is a configuration diagram of a conventional image output device.
FIG. 5 is a conceptual diagram showing the structure of microcapsule paper. 3a, 3b・4a, 4b・6・・・7・・・・8・・・・9・・10・・・11・・・・12・・・Transparent electrode Liquid crystal alignment film Photosensitive layer Gicroic filter outer periphery seal strength Dielectric liquid crystal light source condenser lens heat ray cant filter J3・ ・ ・ ・ ・ 14・ ・ ・ ・ 15・ ・ ・ ・ 16. 18・ ・ 17・ ・ ・ ・ ・ 19・ ・ ・ 20・ ・ ・ ・ 20a, 20b, 20c 51・・・・・・・・Color filter condenser lens・field lens・polarizing plate・liquid crystal light valve・projection lens・microcapsule paper...microcapsule laser scanner Applicant Seiko Electronic Industries Co., Ltd. Agent Patent attorney Hayashi Takayuki Sukemoto Genro, n 2, 2, 2, 2, 2, 2, 2, 2, 1 coach, 4, 5, 5, 1 town C; Lf rUi giant craftsmanship

Claims (2)

[Claims] (1) A photoconductive layer, a liquid crystal alignment layer, a voltage applying means, a ferroelectric liquid crystal layer having threshold characteristics and bistable memory properties between the light transmittance and the applied voltage; The first step is to apply a sufficiently large DC bias voltage to maintain the alignment of liquid crystal molecules, and the first step is to apply a DC bias voltage that is opposite in polarity to the first step and is implicitly below the threshold voltage, but becomes above the threshold voltage when irradiated with light. In an optical writing type liquid crystal light valve driven by a second step of forming an image by an optical writing means while applying a bias voltage, within a wavelength range between the ferroelectric liquid crystal layer and the photoconductive layer. A liquid crystal light valve characterized by forming a dichroic filter that transmits approximately 100% of long wavelength light and reflects approximately 100% of short wavelength light. (2) An image writing means by light irradiation such as a laser beam or an LED, a first image medium on which an image is written by the image writing means, a projection means for projecting the image written on the image medium, and a projected image thereof. In an image output device comprising a second photosensitive image medium that is exposed to light, and a developing means for the second image medium, the first image medium is a liquid crystal light according to claim 1. The wavelength of the writing light used by the image writing means and the upper limit of the wavelength range of the projection light irradiated onto the liquid crystal light valve are separated by 100 nm or more, and the image writing means is placed in the direction of the liquid crystal light valve. An image output device characterized in that it is disposed on the same side as a projection means.