JPS6157931A - Liquid crystal printer head - Google Patents

Abstract

PURPOSE:To enable connection of high density between a liquid crystal cell and a driving circuit system by using aluminium ultrasonic wire bonding. CONSTITUTION:In the case of a pattern for 16-pel 1/2 duty at the connection between of a liquid crystal shutter array, the pitch of an external connection electrode terminal becomes 125mu, and the terminal structure of the liquid crystal cell 10 side is made to three-layer structure of ITO film 350 Angstrom , Cr film 600 Angstrom , Al film 1mu. By connecting a group of terminals of such minute pitch and a group of terminals of IC mounted substrate 12 side by Al ultrasonic wire bonding 13, the best characteristic that do not cause short-circuit between adjoin ing terminals and low in resistance of the connection can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a printer head capable of providing optical information to a photoreceptor used in, for example, an electrophotographic printer, and more particularly to an optical shutter array using liquid crystal.

[Background of the invention]

Conventionally, a Lede beam printer is well known as a device that applies an electrical image signal in the form of light to an electrophotographic photoreceptor and visualizes it. In addition, in recent years, new types of liquid crystals have been developed that make full use of the optical modulation function of liquid crystals, arrange the modulation sections in an array, shine light on them, and use the transmitted light to send optical image signals to the photoreceptor.
Optical shutter arrays have been proposed.

The advantages of this liquid crystal-optical shutter array are: 1. The device as a printer can be made smaller; 2.
Unlike the I-ribbon scanners used in Ledebeam printers, there are no mechanically driven parts, so there is no noise, and the requirements for strict mechanical precision are small.

However, such liquid crystal-optical shutters have serious obstacles in realizing cost reduction. When arranging the apertures, for example, the pixel density of the formed image is 1r: 10
If the shutter array is designed to have dots/m and a short side length of A4, approximately 2000 signal electrodes will be required, and the number of drivers for each T-drive will also be 2000. For this reason, electrical connection with an external IC circuit has been difficult.

This will be explained below with reference to the drawings. FIG. 3 shows an example of a liquid crystal shutter array configuration that will be most easily understood.

As shown in FIG. 3, a shutter opening 1 is provided, and other hatched areas are usually masked to prevent light from leaking. The liquid crystal consists of a signal electrode 3 (3m, 3b+3a+3d...) provided on the inner wall surface of the substrate 2 and this signal electrode 3.
and a common electrode 4 arranged to face each other.

The common electrode 4 is formed on a substrate (not shown) made of a transparent plate such as glass or silastic, and the substrate 2 on which the signal electrode 3 is provided is also made of a glass or plastic plate. A transparent sheet metal can be used, and the substrates are kept at a constant distance by a sealing spacer such as a polyester film, an epoxy adhesive mixed with glass fiber, or a fritted glass.

The signal electrode 3 and the common electrode 4 can be formed of a transparent conductive film such as iridium oxide, tin oxide, or ITO (iridium oxide containing 5 wt% tin oxide), and the lead hems 5 and 6 are drawn out, respectively. , shutter array drive circuit (
(not shown).

FIG. 4 is a sectional view of the liquid crystal-optical shutter array shown in the plan view of FIG. 3, and shows an example of the operation of this shutter array.

The opening and closing of this shutter array is performed by applying voltage to the signal electrode 3.
By selecting (3a, 3b, 3c,...), the alignment state of the liquid crystal 9 between the signal electrode 3 and the opposing common electrode 4 is controlled, and the transmitted light T is determined with respect to the irradiation light weight. be able to.

In FIG. 4, the polarizing plates 7 and 8 are arranged in a cross-niffle state, and the two substrates are arranged so that the initial alignment direction of the liquid crystal 9 is 45 degrees with respect to the polarization direction of the polarizing plates 7 and 8. Orientation treatment is performed using methods such as rubbing treatment. At this time, the liquid crystal 9 is a liquid crystal with positive dielectric anisotropy (
P-type liquid crystal) is used.

Under such settings, the signal electrodes 3a, r, 3b.

3c... is selected, and the common electrode 4 is normally grounded.

In the figure, a relatively large voltage is applied to the signal electrode 3b,
In this case, for example, the P-type liquid crystal molecules are aligned almost perpendicularly to the cell surface.

At this time, the irradiation light I does not pass through the signal electrode 3b portion.

On the other hand, when zero or relatively small voltage is applied to the signal electrodes 3a and 3c, the P-type liquid crystal molecules in these portions change their alignment state, and the irradiated light I becomes transmitted light T and is transmitted. In this operating method, a greater contrast can be obtained by using monochromatic light as the irradiation light intensity, but a white light source can also provide contrast.

By repeating the above operations, the shutter array provides image signals to the photoreceptor.

vJS diagrams (a) and (b) show a structure for connecting a conventional liquid crystal cell and a drive circuit system. In the figure, 10 is the substrate of the liquid crystal cell,
11 is a zebra connector, and 12 is a mounted circuit board. As shown in FIG. 5(b), the zebra connector 11 has an insulating part 1
1 & and conductive portion 11 b i-.

As described above, conventionally, the liquid crystal cell and the drive circuit system have been electrically connected by pressure bonding using an elastic material such as a zebra connector. However, the pitch of current zebra connectors is limited, making it impossible to connect them at minute pitches such as those for liquid crystal printer heads. Furthermore, the electrical resistance value of the connector itself also adversely affects the characteristics.

[Purpose of the invention]

An object of the present invention is to provide a liquid crystal printer head including a liquid crystal cell as described above and a drive circuit system for operating the liquid crystal cell.
Our goal is to provide all types of devices in which liquid crystal cells and drive circuit systems are connected in high density.

[Summary of the Invention] A liquid crystal printer head according to the present invention has an electrode structure having a plurality of signal electrodes and a counter electrode facing the signal electrodes, and both Tl! It is characterized in that an electrical contact point between a liquid crystal cell containing a liquid crystal disposed between poles and a substrate equipped with a drive circuit system for driving the liquid crystal cell is formed by aluminum ultrasonic wire bonding. .

[Embodiments of the invention]

The first part shows an embodiment of the connection part between the liquid crystal cell and the drive circuit system in the liquid crystal printer head according to the present invention. In Figure 1,
10 is a liquid crystal cell substrate, 12 is a mounting circuit board, 13 is an aluminum ultrasonic wire bonding wire, and 14 is an IC
Show i. In the illustrated example, in the case of 16 pel 1/+duty lean, the pitch of the external connection electrode terminals is 125μ, and the terminal structure on the liquid crystal cell side is also made of ITO film 3501, Cr.
The film has a three-layer structure of 600×Atl [1μ]. In this way, by connecting this terminal group and the terminal group on the IC mounting board side by At ultrasonic wire ending, there is no short-circuit with adjacent terminals, and the resistance value of the connection part is low, resulting in the best characteristics. is obtained.

Note that there is also a method of using Au wire for wire bonding, but in this case, heating is required that may cause a negative shadow on the liquid crystal board during the work), and the Au portion that comes into contact with the micro pitch may be damaged by AA wire. This is to spread the current, so there is a high possibility of a short circuit.

From the above, At wire bonding is effective for liquid crystal shutter arrays.

FIG. 2 shows a cross-sectional view of a liquid crystal printer head formed in this manner. In Maki 2 diagram, 22 is a light source, which is a fluorescent lamp, 21 is a reflective shade, which is useful for improving lighting efficiency, and 2
3 is a condenser lens, 24 is a polarizing beam splitter 125
26 is an IA wavelength plate, 27 is a liquid crystal that changes birefringence, 28 is an analyzer, and 29 is an optical signal generated from a liquid crystal switching element. An imaging optical system that forms an image on a photoreceptor 30 is shown.

The light beam emitted from the light source 22 is transmitted through the reflective shade 21 and the condenser lens-e.
A polarizing beam splitter is passed through a condensing element consisting of 23
The light enters at 24. The polarizing beam splitter 24 has the function of splitting the naturally polarized light into two polarized light components, the tP acid component and the S component, transmitting the light of one polarization component and reflecting the light of the other polarization component, as shown in FIG. have. The transmitted light from the polarizing beam splitter passes straight through the polarizing beam splitter 24 in the second polarizing beam splitter 1, and illuminates the liquid crystal 27. On the other hand, the S component reflected by the polarizing beam snoritter 24 is reflected by the mirror 2.
5 and converted into a P component by a 14-wave plate 16.
Similarly, the liquid crystal 27 is illuminated. Assuming that the illuminated liquid crystal 27 rotates the polarization component when a driving voltage is applied and does not change the polarization component when no voltage is applied, P
When the analyzer 28t, which blocks the component (transmits the S component), is installed, light reaches the photoreceptor 30 through the imaging element 19 when the liquid crystal 27 is turned on. Also, when the voltage is off, analyzer 2
The light is cut off at step 8 and does not reach the photoreceptor 30.

In the above optical system, the numerical aperture of the imaging element 19 is designed to be larger than the angle at which the liquid crystal 27 is illuminated by the mirror 25. Therefore, the light from the light source 22 is utilized by the polarizing beam splitter.
24 and A wavelength plate, nearly 100% of the light is directed to the liquid crystal, and the imaging element 29 changes the numerical aperture to the mirror 25.
By increasing the angle of , the light can be used, and the transmission efficiency between the liquid crystal and the photoreceptor can be greatly improved, even if the amount of light is lost by the analyzer.

〔Effect of the invention〕

As described above, according to the present invention, the electrical connection between the liquid crystal cell in the liquid crystal printer head and the substrate equipped with the driving circuit system for driving t''L is formed by aluminum ultrasonic wire bonding. Density connections are possible.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are a plan view and an h-plane view with the liquid crystal cell and drive circuit system disconnected according to the present invention, Figure 2 is a sectional view of the #crystal printer head, and Figure 3 is a diagram of the liquid crystal shutter. FIG. 4 is a sectional view of the liquid crystal shutter array shown in FIG. 3. FIGS. 5(a) and 5(b) are diagrams showing the connection between a conventional liquid crystal cell and a drive circuit system. It is. l... Shafter opening 2... Board 3... Signal electrode 4... Common electrode 10... Liquid crystal cell board 11... Zebra connector 12... Mounted circuit board 13... Wire plug Ding line 14...IC
21... Reflective shade 22... Light source 23... Condensing lens 24
...Polarized beam splinter 25...Reflection mirror 2
6...1/2 wavelength plate 27...Liquid crystal 28...
Analyzer 29...Crystal optical system 30...Photoreceptor (Fig. 1 Cb') Fig. 2

Claims (1)

[Claims] An electrode structure having a plurality of signal electrodes and a counter electrode facing the signal electrodes, a liquid crystal cell including a liquid crystal disposed between the two electrodes, and an electrical contact point between a substrate equipped with a drive circuit system for driving the liquid crystal cell. A liquid crystal printer head characterized by being formed by aluminum ultrasonic wire bonding.