JPH05216056A - Liquid crystal optical shutter array element - Google Patents

Abstract

PURPOSE:To suppress the dulling of driving voltage waveforms and to decrease the operation fluctuations of microshutters by decreasing the load resistance- components with the increase in the number of the microshutters of the scanning electrode substrate of the liquid crystal optical shutter array element to be used for an electrophotographic printer. CONSTITUTION:The connecting points of the scanning electrodes 151 to 154 and 181 to 184 on the scanning electrode substrate 12 and a scanning electrode driving circuit 17 are provided also in the central parts exclusive of both end of the scanning electrode substrate 12 in the case of, for example, the 1/4 time- divided driving type liquid crystal optical shutter array. As a result, the respective scanning electrodes eventually have the four connecting points. The connecting points with the scanning electrode driving circuit 17 are provided also in the central parts of the scanning electrode substrate for respectively 8 pieces of the scanning electrodes at both ends of the scanning electrode substrate 12 in the case of the 1/8 time-divided driving type liquid crystal optical shutter array. The load resistance at the time of driving of the scanning electrode driving circuit 17 is thus halved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal optical shutter array element, and more particularly to a liquid crystal optical shutter array element used in an electrophotographic printer head.

[0002]

2. Description of the Related Art Liquid crystal optical shutter array elements are widely applied to printer heads, optical logic elements, etc., but all use a function of spatially modulating the intensity of incident light. The case where the liquid crystal optical shutter array element is used in the printer head will be described below as an example.

As shown in FIG. 3, the liquid crystal printer head generally includes a light source lamp 34 and a liquid crystal optical shutter array element 3.
1, a selfoc lens array 32, and a photoconductor 33.

In the liquid crystal optical shutter array element 31, micro shutters for transmitting and blocking light by applying a voltage are arranged in a line or in a staggered pattern.

As a method for driving the above-mentioned micro-shutter, time-division driving is performed in order to reduce the number of driving circuits, and normally, several blocks are arranged in the direction in which the micro-shutters are arranged. The time division drive is performed separately.

FIG. 4 shows the basic structure of the time division drive type liquid crystal optical shutter array element. This time division drive type liquid crystal optical shutter array element is a 1/8 time division drive type, and the scanning electrodes are divided into eight, and the scanning electrode 45 represents one of them.

The overall structure is such that a signal electrode substrate 41 and a scanning electrode substrate 42 are opposed to each other, and a liquid crystal material 48 is sealed between them, and each electrode is connected to a signal electrode driving circuit 46 and a scanning electrode driving circuit 47. ing. Although FIG. 4 shows one end side of the electrode substrate, the connection pattern on the scanning electrode substrate at the other end is usually symmetrical with that shown in the drawings.

[0008]

In the above-mentioned conventional time-division drive type liquid crystal optical shutter array element, the connecting portions between the scanning electrodes and the scanning electrode driving circuits are usually located at both ends of the glass substrate. That is, the same scan electrode is connected to the same scan electrode drive circuit at two points. This state is shown in FIG. FIG. 5 shows a liquid crystal optical shutter array element when the number of time divisions is 4, and the scanning electrodes 51 to 54
However, both ends of the scan electrode substrate 59, which is a glass substrate, are connected to the respective scan electrode driving circuits 57.

In recent years, the number of micro-shutters 60 tends to increase due to the increase in resolution of electrophotographic printers and the lengthening of liquid crystal optical shutter array elements accompanying the expansion of output paper width.

The electrodes of the micro shutter portion of this liquid crystal optical shutter array element are made of ITO (indium tin oxide).
And the increase in the number of micro shutters means that the electric resistance component of the ITO portion increases.

Further, by lengthening the liquid crystal optical shutter array element, the total length of the connecting lines between the micro-shutters on the glass substrate becomes longer, and the electric resistance of the connecting line portion increases. Cr (chromium) or Ni (nickel) is used for this connecting wire. Therefore, by accumulating the electric resistance of the connection line between the ITO part and the micro-shutter, the drive voltage becomes difficult to rise and the drive voltage waveform becomes blunt as the distance from the connection point between the scan electrode and the scan electrode drive circuit increases. become. As a result, there is a drawback that the switching speed of the liquid crystal molecules becomes slow, the operation of the micro-shutter varies, and the print quality deteriorates.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal optical shutter array element that eliminates the above-mentioned drawbacks and eliminates the variation in the operation of the micro shutter to suppress the deterioration of the print quality.

[0013]

A liquid crystal optical shutter array element of the present invention has a structure in which liquid crystal is injected between a pair of transparent electrodes on a substrate with signal electrodes and a transparent electrode on a substrate with scanning electrodes. The four micro shutters connected to the signal electrodes are arranged in a row or in a staggered manner, and micro shutters for controlling transmission blocking of light entering the photoconductor at intersections of the signal electrodes and the scanning electrodes. In a 1/4 time division drive type liquid crystal optical shutter array element for sequentially writing data to a shutter, at least four connection points between the scan electrodes and the scan electrode drive circuit are provided on the same scan electrode.

The liquid crystal optical shutter array element of the present invention has a structure in which liquid crystal is injected between a pair of transparent electrodes on a substrate with signal electrodes and a transparent electrode on a substrate with scanning electrodes. Micro shutters for controlling transmission blocking of light entering the photoconductor at the intersections with the scanning electrodes are arranged in an example or in a staggered pattern, and data is sequentially provided to the eight micro shutters connected to the signal electrodes. In a 1/8 time-division drive type liquid crystal optical shutter array element for writing, at least four connection points between the scan electrodes and the scan electrode drive circuit are provided on the same scan electrode.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing a structure of a liquid crystal optical shutter array element of a first embodiment of the present invention divided into a signal electrode substrate side and a scanning electrode substrate side.

The embodiment of FIG. 1 shows an example of a liquid crystal optical shutter array element of a 1/4 time division drive system, and a signal electrode substrate 11
The transparent electrode formed above is the signal electrode 14, and this electrode is made of ITO. Since the signal electrode substrate 11 in FIG. 1 is viewed from the surface opposite to the surface on which the signal electrode 14 is present, the signal electrode 14 is represented by a broken line. Each signal electrode is connected to a common signal electrode drive circuit 16.

On the other hand, the micro shutter 13, the scanning electrode lines 15, the scanning electrodes 151 to 154, and the scanning electrodes 181 to 18
The glass substrate on which 4 is formed is the scanning electrode substrate 12,
Here, the view seen from the surface on which the micro shutter 13 and the like are formed is shown.

A liquid crystal optical shutter array element is constructed by laminating the signal electrode substrate 11 and the scanning electrode substrate 12 described above via a spacer and enclosing the liquid crystal between the two substrates. An alignment film is applied to the surfaces of these two substrates on which the electrodes are arranged.

The micro-shutter 13 is made of ITO like the signal electrode 14, and its shape is a square with one side of 55 (μm). The gap between the micro shutters is 10 (μm).

The micro shutter 13 overlaps one signal electrode. The micro shutters are connected by the scanning electrode lines 15, and the scanning electrode lines 15 and the scanning electrodes 151 to 154 and the scanning electrodes 181 to 18 are connected.
4 is formed by vapor deposition using Cr (chrome). The scan electrodes are divided into four corresponding to the number of time divisions, and are connected to the scan electrode drive circuit 17 at both ends of the scan electrode substrate 12.

Furthermore, even in the central portion of the scanning electrode substrate 12,
A connection point corresponding to each scanning electrode is provided, and the scanning electrode is divided into two parts on the scanning electrode substrate.
That is, in this case, each scan electrode is connected to the scan electrode drive circuit 17
And will have four connection points. As a result, the total length of the scan electrode lines and the scan electrodes driven by the scan electrode drive circuit 17 becomes half the length of the case where only the both ends of the scan electrode substrate 12 are connected.

When the connecting line length on the substrate is shortened as described above, the cumulative resistance value that is a burden on the drive circuit is reduced, and the rounding of the drive voltage waveform is reduced.

By the way, as a liquid crystal material used for a liquid crystal optical shutter array element, application of a ferroelectric liquid crystal having a characteristic of high speed response has been studied, and the liquid crystal molecules have a response speed within a certain range. It has the characteristic of being proportional to the applied voltage. Therefore, if the driving voltage waveform is rounded, the driving voltage varies depending on the location of the micro-shutter, so that the response speed of the liquid crystal molecules is not uniform and, as a result, the print quality varies. In particular, as the micro shutter is located farther from the connection point with the scan electrode drive circuit, the rounding of the drive voltage waveform becomes more prominent. The basic feature of the present invention is to reduce variations in print quality by reducing the waveform rounding of the drive voltage waveform.

FIG. 2 is a plan view showing the structure of the liquid crystal optical shutter array element of the second embodiment of the present invention divided into the signal electrode side and the scanning electrode side. FIG. 2 shows an example of a 1/8 time-division drive type liquid crystal optical shutter array element, and the overall configuration is the same as that of the 1/4 time-division drive type liquid crystal optical shutter array element of the first embodiment described above. The difference from the case of the liquid crystal optical shutter array element of the 1/4 time division driving system is that the scanning electrode substrate 2 corresponds to the 1/8 time division driving system.
Scan electrode lines 25 and scan electrodes 251-2 formed on
58, the scanning electrodes 281 to 288 are divided into eight. Further, the number of signal electrodes 24 on the signal electrode substrate 21 is eight.
It is designed to overlap with individual micro shutters.
Also in this case, the material of the signal electrode 24 and the micro shutter 23 is ITO, and the scanning electrode line 25 and the scanning electrodes 251 to 251.
The material for the scanning electrodes 258 and 281 to 288 is Cr.
The shape of the micro shutter 23 is 55 (μ
m) square, the gap between the micro-shutters is 1
It is 0 (μm).

In this 1/8 time division driving type liquid crystal optical shutter array element, the scanning electrode is divided into two, as in the case of the 1/4 time division driving type liquid crystal optical shutter array element. In addition to both ends of the scan electrode substrate 22, a connection point with the scan electrode driving circuit 27 is provided in the central portion of the substrate. Therefore, each of the eight scan electrodes has four connection points with the scan electrode drive circuit, and the load resistance component in driving the scan electrode drive circuit is reduced.

Next, specific design specifications of the 1/8 time-division drive type liquid crystal optical shutter array element in the first embodiment will be described.

Signal electrode 24 and micro shutter 23
The thickness of ITO is 0.1 (μm), the sheet resistance of ITO is about 35 (Ω / m ² ), the thickness of Cr of the scanning electrode 25 is 0.2 (μm), and the volume resistivity of Cr is 5.14 x 10 ^-7
If it is (Ω · m), the electric resistance of one micro shutter including the scanning electrode line is about 130 (Ω). The total number of micro shutters of this liquid crystal optical shutter array element is 4096, and since this is driven by eight scanning electrodes, the number of micro shutters driven by one scanning electrode is 4096/8 = 512 (pieces). Becomes Therefore,
In driving when electrodes are connected at both ends of the scanning electrode substrate, 130 (Ω) × 512 (pieces) = 66.56 (KΩ)
Is a load of the drive circuit, but the load of the drive circuit can be halved by driving by connecting the electrodes also from the central portion of the scan electrode substrate as in the present embodiment. Further, the more connection points between the scan electrodes and the scan electrode drive circuits are provided, the less the rounding of the drive voltage waveform becomes.

[0029]

As described above, according to the present invention, by providing at least four connection points between the scan electrodes and the scan electrode drive circuit on the same scan electrode, the rounding of the waveform of the scan electrode drive voltage is reduced. Since it is possible to reduce the variation in the operation of the micro shutter due to the decrease in the switching speed of the liquid crystal molecules, it is possible to significantly suppress the deterioration of the print quality in the electrophotographic printer using the liquid crystal optical shutter array element in the printer head. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a liquid crystal optical shutter array element of a first embodiment of the present invention divided into a signal electrode substrate side and a scanning electrode substrate side.

FIG. 2 is a plan view showing a configuration of a liquid crystal optical shutter array element of a second embodiment of the present invention divided into a signal electrode substrate side and a scanning electrode substrate side.

FIG. 3 is a side view showing a configuration of a liquid crystal printer head.

FIG. 4 is a perspective view showing a basic structure of a conventional time division drive type liquid crystal optical shutter array element.

FIG. 5 shows a configuration of a conventional 1/4 time-division drive type liquid crystal optical shutter array element in which the signal electrode substrate side and the scanning electrode substrate side are
It is a top view which divides and shows.

[Explanation of symbols]

 11 signal electrode substrate 12 scanning electrode substrate 13 micro shutter 14 signal electrode 15 scanning electrode line 16 signal electrode driving circuit 17 scanning electrode driving circuit 21 signal electrode substrate 22 scanning electrode substrate 23 micro shutter 24 signal electrode 25 scanning electrode line 26 signal electrode driving Circuit 27 Scan electrode drive circuit 31 Liquid crystal optical shutter array element 32 Selfoc lens array 33 Photoconductor 34 Light source lamp 41 Signal electrode substrate 42 Scan electrode substrate 43 Polarizing plate 44 Signal electrode 45 Scan electrode 46 Signal electrode drive circuit 47 Scan electrode drive circuit 48 liquid crystal material 51-54 scan electrode 55 signal electrode 56 signal electrode drive circuit 57 scan electrode drive circuit 58 signal electrode substrate 59 scan electrode substrate 60 micro shutter 151-154 scan electrode 181-184 scan electrode 251-258 scan electrode 281-288 scanning electrodes

Claims (2)

[Claims] 1. A liquid crystal is injected between a pair of transparent electrodes on a substrate with signal electrodes and a transparent electrode on a substrate with scanning electrodes, and a photoconductor is provided at the intersection of the signal electrodes and scanning electrodes. Micro shutters for controlling transmission blocking of light incident on a line are arranged in a row or in a staggered pattern, and data is sequentially written into the four micro shutters connected to the signal electrodes. A liquid crystal optical shutter array element, wherein at least four connection points between the scan electrodes and the scan electrode driving circuit are provided on the same scan electrode. 2. A structure in which liquid crystal is injected between a pair of transparent electrodes on a substrate with signal electrodes and a transparent electrode on a substrate with scanning electrodes, and a photoconductor is provided at the intersection of the signal electrodes and the scanning electrodes. Micro shutters for controlling transmission blocking of light entering the light source are arranged in an example or in a staggered manner, and data is sequentially written to the eight micro shutters connected to the signal electrodes. 1/8 time division drive type A liquid crystal optical shutter array element, wherein at least four connection points between the scan electrodes and the scan electrode driving circuit are provided on the same scan electrode.