JPH0282220A - lcd shutter - Google Patents

Abstract

PURPOSE:To improve image quality by providing one common electrode and plural signal electrodes to the liquid crystal shutter and zigzag arraying the microshutters formed in opposite crossing parts. CONSTITUTION:The common electrode C is constituted of one piece in parallel with the longitudinal direction of an upper glass substrate 14a and the signal electrodes S1, S2... Sn are extended from the central part of a glass substrate 14b alternately to both sides of the glass substrate 14b. Both the electrodes L, S1 to Sn in the region except the opposite crossing parts of both the electrodes C, S1 to Sn are constituted by forming metallic films of chromium, etc., on a transparent conductive film and the part of only the transparent conductive film allows the transmission of light. The opposite crossing parts are the microshutters 15, 16 of two-row constitution (row A, row B). These microshutters 15, 16 are arranged zigzag. The emission (leakage) of the light of a light source 4a from the parts except the microshutters 15, 16 is obviated in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a liquid crystal shutter used in a liquid crystal printer.

[Prior Art] A liquid crystal shutter is controlled to open and close based on image data output from an external host device, and is built into a liquid crystal printer and used as an image forming device.

FIG. 8 is a diagram showing the configuration of a conventional liquid crystal shutter. The two common electrodes 26a and 26b shown in the figure are formed on a common electrode substrate (glass substrate) not shown.
Signal electrodes 27a and 27b are arranged on a signal electrode substrate (glass substrate) (not shown) in a direction substantially orthogonal to a and 26b.
, ... are formed. Common electrodes 26a, 26
b, signal electrodes 27a, 27b, . . . are all constructed by forming a metal film such as chromium on a predetermined area on a transparent conductive film, and the common electrode 26a is formed only of a transparent conductive film.
, 26b (micro shutters 28a, 28b are located at the overlapping portions of signal electrodes 27a, 27b, . . . formed only of transparent conductive films).

The liquid crystal shutter with this configuration is irradiated with light from a light source (not shown), and as described later, the light passes only through the micro shutters 28a and 28b, which are driven to an open state, and irradiates the light onto, for example, a photosensitive surface, causing electrostatic form an image.

FIG. 9 is a diagram illustrating a drive signal for setting the micro shutters 28a, 28b to the open or closed state.

The above-mentioned common electrode 26a has a common signal (COM
I) is supplied, and the common type 126b is supplied with a common signal (C0M
2) is supplied to the signal electrode 27a.

27b, . . . are supplied with a recording signal (PTI or PT2). As can be seen from the figure, COMI and C0M2 are both the same waveform signals, but the phase is shifted by a period Tw /2, which is half of one write period T, A, and C0M1 is I
T in the first half of M-included period T8.

/2 is used to open or close the micro shutter 28a. Further, C0M2 is also used to open or close the micro shutter 28b during the first half of one write cycle T-. COMI and C0
The remaining period T8/2 of each of M2 is the first half Tw mentioned above.
Micro shutters 28a, 28 set to a period of /2
b is used to maintain the open or closed state.

Also, the recording signal PTI is set to the micro shutter 2 days a or 2 days.
The recording signal PT2 is a signal that is output when the micro shutter 8b is set to the open state, and the recording signal PT2 is a signal that is output when the micro shutter 28a or 28b is set to the closed state. This is a signal that is selectively output according to data. Micro shutters 28a, 28
The superimposed signals 5EGI and 5EG2 of the above-mentioned signals applied to the picture electrodes 26a, 26b and 27a, 27b, - are applied to the picture electrodes 26a, 26b, 27a, 27b, -, and set to the open or closed state.

For example, the micro shutter 28a shown in FIG. 8 is controlled to open, open and close as shown in FIG.
8b is controlled to open and close as shown in the figure, the signal electrode 27a receives a PTI signal - PTI signal - PTI signal - PT2T2 signal T2T2 signal T2T2 every Tl, l/2.
The signal T1 signal is applied to create a superimposed signal 5EGI shown in the same figure, which is applied to the micro shutter 28a, and the superimposed signal 5EGI shown in the same figure is generated.
EG2 is created and applied to the micro shutter 28b.

On the other hand, during the remaining periods T1 and 1/2 to maintain the open or closed state set to each micro shutter 28a, 28b, the superimposed signal shown in the figure is activated to maintain the set open or closed state. Part of the waveform signals a, b, c, etc. are applied.

[Problems with conventional technology]

The following problems occur with the conventional liquid crystal shutter described above.

b) First, as shown in FIG.
Each electrode 26a, 26b, 2
Predetermined areas 7a, 27b, . . . are made of a metal film, but the shaded area 29 in the figure is for insulation, so common electrodes 26a, 26b1 signal electrodes 27a, 27b, .
・This is an area that cannot be covered with a metal film. For this reason, light leaks from this region 29 and, for example, is irradiated onto the photosensitive surface, thereby reducing the quality of images created by a printer using this liquid crystal shutter.

Furthermore, in order to drive the micro-shutters 28a and 28b as described above, ■ the above-mentioned process of always maintaining the once-set open or closed state of the micro-shutters during the Tw/2 period in the latter half of the writing cycle 3tl'rw; a.

Waveform signals such as b and c are applied. However, as can be seen from the figure, this waveform signal is
28b cannot be maintained in the same open or closed state, resulting in poor contrast in the image produced. Also, unlike the case where a superimposed signal for setting the open or closed state is applied for the entire period of one write period TW, the waveform signals a to c described above completely close the micro shutters 28a and 28b during the write period Tw. cannot be maintained in the open or closed position.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a liquid crystal shutter that eliminates light leakage from the liquid crystal shutter and also reliably maintains the set open or closed state of the shutter at the same level during the writing cycle. .

[Key points of the invention]

According to the present invention, a liquid crystal material is sealed between two glass substrates, one common electrode is provided on the liquid crystal material side of one of the glass substrates, and a common electrode is provided on the liquid crystal material side of the other glass substrate. The present invention is achieved by providing a liquid crystal shutter characterized in that a plurality of signal electrodes are provided in the common electrode and cross-opposed to each other, and the micro-shutters formed in the cross-opposed portions are arranged in a staggered manner.

〔Example〕

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

FIG. 2 is a schematic diagram of a liquid crystal printer having a liquid crystal shutter according to an embodiment. In the figure, a liquid crystal printer 1 includes a photoreceptor drum 2, a charger 3, a liquid crystal head 4, a developer 5, and a transfer device 6, which are sequentially arranged near the circumferential surface of the photoreceptor drum 2.
, cleaner 7, etc.

The charger 3 applies an initial charging voltage to the photosensitive surface of the photosensitive drum 2 rotating in the direction of the arrow, the liquid crystal head 4 is a device that exposes the photosensitive surface based on print data, which will be described later, and the developer Reference numeral 5 converts the electrostatic latent image formed on the photosensitive surface by the above-mentioned exposure into a toner image, and the transfer device 6 carries out the paper from the paper cassette 8 by the paper feed roller 9, and then transports the paper by the slip roll 10 and the standby roll 11. This is a device that transfers a toner image onto P. The cleaner 7 is a device for removing toner remaining on the photosensitive surface, and the toner image transferred onto the paper P is thermally fixed by a fixing roll 12.

The liquid crystal head 4 includes a light source 4a and a liquid crystal shutter 4.
b, an imaging lens array 4C is provided, and a liquid crystal shutter 4
b refers to a micro-shutter formed in the liquid crystal shutter 4b that is driven to open and close as described later, so that light from the light source 4a is irradiated (exposed) onto the photosensitive surface through the open micro-shutter and the imaging lens array 4C. It is. FIG. 3 is a perspective view of the above-mentioned liquid crystal shutter 4b. The liquid crystal shank 4b includes glass substrates 14a and 14b arranged above and below,
It is composed of a liquid crystal agent sealed between the glass substrates 14a and 14b, and a common electrode is disposed on the back surface of the glass substrate 14a. On the upper surface of tfi, 14b, there is a signal electrode Sl that crosses and opposes this common electrode in a direction approximately perpendicular to the common electrode.
, S2+...Sfi are arranged. FIG. 1 is a diagram showing this electrode configuration.

The common electrode C is arranged parallel to the longitudinal direction of the upper glass substrate 14a.
Consisting of books, signal electrodes S+, S2, ...S
, , extend alternately from the center of the glass substrate 14b to both sides of the glass substrate 14b. This picture electrode C, S+
, 32. . . . Image electrode in area other than the cross-opposing portion of S7, S+, 32. ...Sn is composed of a metal film such as chromium formed on a transparent conductive film, and therefore only the portion of the transparent conductive film can transmit light. This cross-opposed section has two rows of micro shutters 1 (A row and B row).
5.16, and these micro shutters 15.16 are arranged in a staggered manner as shown in the figure. Therefore, the common electrode C is composed of one electrode, and since the parts other than the micro-shutter 15.16 are covered with a metal film, the light from the light source 4a is emitted from other than the micro-shutter 15.16 (leakage occurs). ) FIG. 4 is a circuit diagram of a drive circuit that supplies recording signals to the signal electrodes S, . However, the figure only shows the circuit configuration of the signal electrodes 5234, . . . that supply recording signals to the micro shutters 16 arranged in row B. The drive circuit 17 includes a data switching circuit 18, a shift register 19, a latch circuit 20, and a flip-flop 2.
1 consists of a waveform selection circuit 22 and a driver 23, and includes signal electrodes Sz, Sz, S6 . ... has a waveform selection circuit 22
The configuration is such that a PTI' signal (open signal) or PT2' (close signal) selected in , which will be described in detail later, is input. The data switching section 18 is composed of AND gates 18a, 18b, and an inverter 18c, and print data of "0" or "1" is transferred to the shift register 19 according to a clock signal (CKO).
Or signal electrodes Sl, Sl.

. . . is output to a drive circuit (not shown) on the side. That is,
As shown in FIG. 5, print data rl'', r3'', and r5'' are output from a control circuit (not shown).

... to the AND game) 18a in synchronization with the high level of the clock signal (CKO), and print data "2", r
4'', r5'', . . . are output to the AND gate 18b in synchronization with the low level of the clock signal M (CKO), and print data ``1'', ``3'', ``5'', . . . are output to the AND gate. 1
The print data r2'', F4'', '6J, . . . input to the AND gate 18b, which is output from the drive circuit on the side of the signal electrodes S+, S*, . The signals are sequentially output to the shift register 19 in synchronization with the rising edge. The shift register 19 has an area for writing print data of m focus, and inputs the above-mentioned print data r2. ．． r4J, r5. .

. . . are sequentially shifted to the right with respect to the figure.

Print data of m bits or more is output to the next stage shift register via the buffer 24 (cascade output). After that, the above-mentioned 8 columns and 1547 worth of print data are transferred to the drive circuit 1.
When written to the shift register 19 etc. on the 7 side, the input terminal D of the latch circuit 20 is synchronized with the clock signal (CK2).
The print data for one line described above is output to ID, etc. At this time, the print data of the previous line, which was latched in the latch circuit 20, is output to F and F21. F, F
21, the arrangement positions of the micro shutters 15 and 16 are at a distance l(
(Fig. 1) Because of the misalignment, F and F21 are placed on the drive circuit 17 side.
This is a circuit for shifting the timing of exposure of the photosensitive surface between the micro shutters 15 and 16 and exposing the same line of the photosensitive surface in the sub-scanning direction d. In this example, F and F21 are shifted by two dots, so that the signal electrodes s, st, s, and F21 have a two-stage configuration.

,... side drive circuits are not provided with corresponding circuits.

The print data delayed by a predetermined time at F and F21 as described above is output to the waveform selection circuit 22, and either the PTl' signal or the PT2' signal is selected. Waveform selection circuit 2
2 includes a selection circuit 25 shown in FIG. 6 corresponding to each dot.
is provided, and when the print data input from the input terminal Therefore, for example, input terminals X, , X2.X□.

The print data input to ... is "l"', "0''.

1",..., the PTl' signal is output to the output terminal W, the PT2' signal is output to the output terminal W2, the PTI" signal is output to the output terminal W3, and the other outputs Similarly selected PTI' for terminal W4 and subsequent terminals.
signal or PT2' signal is output.

This PTI' signal is a signal for driving the micro shutter 16 to open, and as shown in FIG. 7, it is composed of a low frequency (fL) of 5K) fz. Further, the PT2' signal is a signal for driving the micro shutter 16 to close,
As shown in the figure, the PTI' signal or PT2' signal selected by the waveform selection circuit 22 is transmitted to the corresponding signal electrode via the driver 23. 32, 34, etc. As shown in FIG. 7, the common signal at the ground level ("O'" level) is supplied to the common electrode C.
The PTI' and PT2' signals are applied as superimposed signals to the micro shutter 16, and the micro shutter 16 to which the PTI' signal is input is driven to open, and the micro shutter 16 to which the PT2' signal is input is driven to close.

Moreover, the superimposed signal applied to the micro-shutter 16 at this time is the same as the conventional one, such as the above-mentioned a-c mixed with the rt-multiplied signal fH signal for maintaining the open or closed state during the -writing period T+, +. It does not include waveform signals.

Therefore, the micro shutter 16 can be driven to open or close completely.

Note that the signal electrodes SS3.・
It goes without saying that the micro shutter 15 on the A row side to which the corresponding superimposed signal is applied by the recording signal from .

〔Effect of the invention〕

As explained in detail above, according to the present invention, since the common electrode is composed of one electrode, there is no area where light leaks from the liquid crystal shutter as in the conventional case, and the liquid crystal shutter of the present invention can be used. It is possible to increase the contrast of the image and improve the image quality.

In addition, since the signal for driving the micro shutter to open or close can be applied throughout the writing period T, the micro shutter can be set to the completely open or closed state, and by using the liquid crystal shutter of the present invention, a clear image can be obtained. be able to.

Furthermore, the signal supplied to the common electrode may be a ground level signal, eliminating the need to create a special common signal and making it possible to easily configure a circuit for creating a drive signal to the liquid crystal shutter.

[Brief explanation of the drawing]

FIG. 1 is an electrode configuration diagram of a liquid crystal shutter according to an embodiment, FIG. 2 is a schematic configuration diagram of a liquid crystal printer using a liquid crystal shutter according to an embodiment, and FIG. 3 is a perspective view of a liquid crystal shutter according to an embodiment. Figure 4 is a driving circuit diagram of the liquid crystal shutter of one embodiment, Figure 5 is a timing chart showing the output status of print data and clock signals, Figure 6 is a circuit diagram of the selection circuit in the waveform selection circuit, and Figure 7 is A waveform diagram of the PTI' signal and a PT2' signal, FIG. 8 is a schematic configuration diagram of a conventional liquid crystal shutter, and FIG. 9 is a driving waveform diagram of the conventional liquid crystal shutter. b 14a. 15゜l 7 ・ 18 ・ l 9 ・ 20 ・ 21 ・ 22 ・ C・ ・ SI+ ... Liquid crystal shutter, 14b ... Glass substrate, 16 ... Micro shutter, ... Drive circuit, ... Data switching circuit, ...Shift register, ...Latch circuit, ...F, F. ...Waveform selection circuit, -Common electrode, S2...Signal electrode. Patent applicant Casio Electronics Industries Co., Ltd. Same as above
Casio Computer Co., Ltd.Figure 1Figure 1Figure 1

Claims (1)

[Claims] a common electrode with a liquid crystal substance sealed between two glass substrates and provided on the liquid crystal substance side of one of the glass substrates;
A liquid crystal shutter comprising a plurality of signal electrodes provided on the liquid crystal substance side of the other glass substrate and intersectingly opposing the common electrode, and having micro shutters formed in the intersectingly opposing portion arranged in a staggered arrangement. .