JPH022038A - Medium contrast printing system of liquid crystal electrophotographic printer - Google Patents

Abstract

PURPOSE:To perform arbitrary medium contrast printing by providing a pair of polarizing plates, a plurality of liquid crystal shutter arrays inserted therebetween to change the quantity of transmitted light and a plurality of control circuits. CONSTITUTION:Transmitted light 9 is emitted from a light source 1 and passes through the first polarizing plate 2, the first and second liquid cristal shutter arrays 3, 4 and the second polarizing plate 5 to irradiate a photosensitive drum 8. The photosensitive drum 8 has potential corresponding to the quantity of the light allowed to irradiate said drum 8. In the first and second liquid crystal shutter arrays 3, 4, the respective liquid shutters thereof are individually driven by the first and second control circuits 6, 7 and, when the transmissivities of the liquid crystal shutters are respectively set to theta1, theta2, 100% of transmissivity is set to the black printing density level of a usual liquid crystal electrophotographic printer and theta1.theta2 of the transmissivity is set to a white printing density level, medium contrast printing becomes possible on the basis of theta1, theta2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application in Beach Industry) The present invention relates to a liquid crystal electrophotographic printer, and more particularly to a halftone display method using a plurality of liquid crystal shutter arrays.

(Prior Art) Conventionally, this type of liquid crystal electrophotographic printer uses one liquid crystal shutter array to transmit/block light from a light source by each liquid crystal shutter by utilizing its electro-optical effect characteristics.
A binary printing method in which a photosensitive drum is irradiated has been known.

(Problems to be Solved by the Invention) The conventional liquid crystal electrophotographic printer described above uses a binary printing method of transmitting/blocking the liquid crystal shutter, so that
There is a drawback that it is not possible to print halftones between the two values.

An object of the present invention is to eliminate the above-mentioned drawbacks by providing a liquid crystal shutter array having several electro-optic effect characteristics in a liquid crystal shutter head to realize halftones, and to print an arbitrary halftone. An object of the present invention is to provide a halftone printing method for a liquid crystal electrophotographic printer.

(Means for Solving the Problems) The halftone printing method of a liquid crystal electrophotographic printer according to the present invention is configured to include a pair of polarizing plates, a plurality of liquid crystal arrays, and a plurality of control circuits.

A pair of polarizing plates are placed between the light source and the photosensitive drum, and serve as slanted plates that limit the direction of polarization.

A plurality of liquid crystal shutter arrays are inserted between a pair of polarizing plates and are used to change the amount of transmitted light.

The plurality of control circuits is a sixth one that controls the plurality of liquid crystal shutter arrays.

(Example) Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of a halftone printing method of a liquid crystal electrophotographic printer according to the present invention.

Referring to FIG. 1, 1 is a light source, 2 is a first polarizing plate, 3 is a first liquid crystal shutter array, 4 is a second liquid crystal shutter array, 5 is a second polarizing plate, and 6 is a first polarizing plate. Control circuit, fu@2
8 represents a photosensitive drum, and 9 represents transmitted light.

The second river is an explanatory diagram showing the relationship between the amount of light transmitted from the liquid crystal shutter head and the potential of the photosensitive drum 8. Although the amount of transmitted light is not necessarily proportional to the potential of the photosensitive drum 8,
For the sake of explanation, it is assumed that there is a proportional relationship. Therefore, the higher the potential of the photosensitive drum 8, the higher the print density.

In FIG. 1, transmitted light 9 is emitted from a light source 1, passes through a first polarizing plate 2, first and second liquid crystal shutter arrays 3.4, and a second polarizing plate 5, and passes through a photosensitive drum. 8 is irradiated. The photosensitive drum 8 has a potential depending on the amount of light irradiated onto the photosensitive drum 8.

In the first and second liquid crystal display arrays 3 and 4,
Each liquid crystal shutter is connected to a first and second control circuit 6.
, 7 individually.

When no driving voltage is applied to the liquid crystal shutter, the liquid crystal shutter array transmits light almost completely, and when a driving voltage is applied, the transmittance of the liquid crystal shutter array decreases.

In the first and second liquid crystal shutter arrays 3 and 4,
The transmittance of the liquid crystal shutter is θ1 and θ!, respectively. Suppose it was. In this case, the transmittance is 100% due to the combination of driving voltages, θl, θ.

There are four types, θl and θ, and the transmitted light amount level is also four.

100% of the transmittance is normally set as the black print density level of a liquid crystal electrophotographic printer, and 01·H2 of the transmittance is set as the white print density level. Therefore, halftone printing is possible for θ1 and θ■.

(Effects of the Invention) As explained above, the present invention provides a liquid crystal shutter array having several electro-optic effect characteristics in the liquid crystal shutter head to realize halftones, thereby making it possible to easily print halftones. This has the effect of improving versatility.

[Brief explanation of the drawing]

FIG. 1 shows an example of the halftone printing method of the liquid crystal electrophotographic printer according to the present invention. It is a system diagram showing example J. FIG. 2 is an explanatory diagram showing the relationship between the amount of light transmitted to the photosensitive drum and the potential of the photosensitive drum in FIG. 1. 1ee fist light source 2.5 battle・・Polarizing plate 3.4・Fist・Liquid crystal shutter array 6,F・Kisten control circuit 8-・O photosensitive drum 9・Transmitted light patent

Claims (1)

[Claims] a pair of polarizing plates placed between the light source and the photosensitive drum to limit the direction of polarization; a plurality of liquid crystal shutter arrays inserted between the pair of polarizing plates to change the amount of transmitted light; 1. A halftone printing method for a liquid crystal electrophotographic printer, comprising: a plurality of control circuits for controlling a liquid crystal shutter array;