JPH04232978A - Electronic printing system using feroelectric liquid crystal optical switch - Google Patents

Abstract

PURPOSE: To use individually addressable ferroelectric liquid crystal elements as a multiple gate optical switch by making a driving means spatially modulate a parallel light beam and send the modulated output beam out through the projection surface of a prism. CONSTITUTION: The sheet type parallel light beam 56 is sent in the incidence surface 68 of a prism at a certain angle ∓ of incidence from a laser light source 66. Then a driving circuit 60 supplies a driving voltage to a selected electrode 46 to generate an electric field nearby the selectively addressed electrode 46, thereby changing a relative ferroelectric liquid crystal material into an open or closed state. Therefore, the incident beam 52 is sent out of the projection surface 70 of the prism completely as an internal reflected beam 72 according to variation in the reflective index of the layer 42, or enters the layer 42 and is sent out of the projection surface 70 as a switched beam 71.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION This invention relates to line printing systems and, more particularly, to printing systems that utilize a plurality of individually addressable ferroelectric liquid crystal elements as multi-gate optical switches.

[0002] Optical switches using ferroelectric liquid crystal materials are 1
U.S. Patent No. 4,81, issued May 21, 989.
No. 3,771. The present invention provides improvements to prior art switch elements and the application of the results to line printing systems. In particular, the present invention provides a method for processing data according to a series of sequential input data samples containing numerical values representing the magnitude of exposure values of pixels on sequential lines of an image.
An electronic line printer for printing said image on a photosensitive recording medium, comprising: a substrate formed on one side thereof; a plurality of individually addressable electrodes; a first surface parallel to said electrode surface of said substrate; and a ferroelectric liquid crystal layer sandwiched between the prism and the substrate in close contact with each other on both sides; means for passing a sheet of collimated light through a surface and into an interaction region of said optical switch; and applying said input data samples to said individually addressable electrodes to sequentially create a ferroelectric field pattern. generated within the liquid crystal layer,
driving means for changing the transmittance and refractive index of the layer in the region, the driving means spatially modulating the parallel light beam and transmitting the modulated output to the exit surface of the prism. This invention relates to a printer characterized in that it sends out data through a printer.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a ferroelectric optical switch according to the prior art. FIG. 2 is a side view of an electro-optic line printer using ferroelectric liquid crystal optical switches. FIG. 3 is an enlarged bottom view of the printer of FIG. FIG. 4 is an enlarged perspective view of the optical switch of FIG. 2. Figure 5
3 is an enlarged view of the optical switch of FIG. 2 seen from the bottom; FIG.

[Description of the Invention] FIG. 1 is an explanatory diagram of the operation of a ferroelectric optical switch according to the prior art. A thin (typically 2 micron) layer 10 of ferroelectric liquid crystal material forms two prisms 1
Each prism has a transparent conductive film 16, 18 on its inner surface. These inner surfaces are also provided with an organic polymer alignment control layer (typically less than 1 micron) for controlling the alignment of liquid crystal molecules. The smectic layer is oriented at an angle to the plane of incidence of the optical path of the incident light beam 20, so that the ferroelectric liquid crystal lies in this plane of incidence, at least preferably in one of two alternating orientations. either in the vertical plane or in the vertical plane. This orientation control results in the greatest change in the refractive index of the layers that the beam 20 encounters. If the refractive index of the liquid crystal layer 10 matches the refractive index of the prism 12, the effect of a change in the refractive index on the beam is whether the beam is completely reflected from the prism 12 as an output beam 22 by total internal reflection or not. ,
or is either incorporated into layer 10 and transmitted as output beam 24.

Referring now to FIGS. 2 and 3, an electro-optic line printer 30 is illustrated that utilizes a multiple gate optical switch 32 for exposing a photoconductive drum 34. Optical switch 32 (enlarged view from the side and bottom is shown in Figure 4)
and FIG. 5) includes a prism 36 having a transparent conductive layer 38 on the bottom surface. A layer of ferroelectric liquid crystal material 42 includes prisms 36 and a plurality of individually addressable electrodes 4.
6 and a silicon integrated circuit 44 having 6 . A liquid crystal alignment control layer is applied to both the surface of the prism and the surface of the integrated circuit. Electrodes 46 are individually addressed by a driver circuit 60 that receives data input signals from a controller 62. As shown, the light beam 52 from the laser light source 66 illuminates substantially the entire width of the electro-optic element 32 and, as it passes through the electro-optic element 36, is brought into phase plane according to a series of sequential input data samples. Gives modulation. The data sample includes numerical values indicating the magnitude of the exposure value of each pixel in a sequential line of the image. In the preferred embodiment, the drive control circuit is incorporated by reference to U.S. Pat.
, 450,459. The contents of this patent are incorporated herein by reference. The encoder and multiplexer cooperate to sequentially apply differentially encoded data to electrodes 46 at a rate consistent with the data rate.

When the device is started, a sheet-shaped collimated light beam 56 is sent from a laser light source 66 to an entrance surface 68 of the prism 36 at a certain angle of incidence θ. This angle θ does not have to be a grazing incidence angle as in the prior art systems described above. Drive circuit 60 applies a drive voltage to selected electrodes 46 . An electric field is generated in the vicinity of the selectively addressed electrodes to change the state of the associated ferroelectric liquid crystal material to an open or closed state. Thus, depending on the change in the refractive index of layer 42, the incident beam 52 will either be transmitted out of the exit face 70 of the prism 36 entirely as an internally reflected beam 72, or will enter the layer 42 and exit the exit face 70 as a switched beam 71. sent from. It is desirable that the surface of the chip 44 be roughened. This also leads to roughening of the electrode 46 in order to scatter the beam. If so, the schlieren optics 80, including the field lens 82, the control diaphragm 84, and the cylindrical lens 86, can be configured to select one of the beam commands for imaging onto the receiver drum 34. It is possible. It may also be desirable to insert a half-wave plate between the laser source and the prism to achieve variation in the polarization state of the input light beam.

Although the invention is illustrated in reflection mode,
It is also possible to implement it as a transmission type, in which case the silicon integrated circuit 44 may also be replaced by a transparent layer. The integrated circuit will then be replaced by a thin film transistor, and this combination will be able to provide a higher control ratio.

[Brief explanation of the drawing]

FIG. 1 is a top side view of a ferroelectric optical switch according to the prior art.

FIG. 2 is a side view of an electro-optic line printer using ferroelectric liquid crystal optical switches.

FIG. 3 is an enlarged bottom view of the printer of FIG. 2;

FIG. 4 is an enlarged perspective view of the optical switch of FIG. 2.

FIG. 5 is an enlarged bottom view of the optical switch of FIG. 2.

[Explanation of symbols]

10 layers, 12, 14 prisms, 16, 18
Transparent conductive film, 20 Incident light beam, 22, 24
Output beam, 30 Line printer, 32 Multi-gate optical switch, 34 Photoconductive drum, 36 Prism, 38 Conductive layer, 43 Liquid crystal material layer, 44
Integrated circuit, 46 Electrode, 52 Light beam, 56
Parallel light beam, 60 Driver circuit, 62
controller, 66 laser light source, 68 incidence plane,
70 exit surface, 71 switched beam, 72
Internally reflected beam, 80 Schlieren optics, 82
Field lens, 84 Control diaphragm, 86 Cylindrical lens

Claims (1)

[Claims] 1. An electronic line printer that prints an image on a photosensitive recording medium according to a series of sequential input data samples containing numerical values representing the magnitude of exposure values for pixels on a sequential line of the image, a prism having a substrate formed therein; a plurality of individually addressable electrodes; a prism having a first surface parallel to and opposing the electrode surface of the substrate; a multi-gate switch comprising closely sandwiched ferroelectric liquid crystal layers, the line printer further directing a sheet of collimated light through the entrance face of the prism and into the interaction region of the optical switch. means for applying said input data samples to said individually addressable electrodes to generate a pattern of sequential electric fields within said laminated ferroelectric liquid crystal layer, thereby increasing the transmittance within said region of said layer; and a drive means for changing the refractive index, said drive means spatially modulating said collimated light beam and directing said modulated output beam through an exit face of said prism.