KR20000016294A - Large-area fiber optic display using piezoelectric shutters - Google Patents

Abstract

PURPOSE: Disclosed is a fiber optic display using a piezoelectric shutter as piezoelectric bimorphs. CONSTITUTION: A piezoelectric shutter (24) is arranged in a comb pattern (26) and presents a core. The comb is provided with at least one tooth constituting the shutter, the bore being arranged with elevation allowing the displacement of the shutter by the piezoelectric effect. The device is remarkable in that it comprises at least one bimorph (14) arranged on the support, capable of being raised with respect to the support by the piezoelectric effect.

Description

Large Area Fiber Optic Display with Piezo Shutters

Large area displays such as an animated scoreboard of an athletic stadium and the like are of course well known in the art. Typically, such displays are in the form known as secondary emission displays where light is emitted from sources such as cathode ray tubes (CRTs) and television screens. Phosphorescent light emission from such displays is problematic in that the intensity is limited, and therefore they provide low contrast and poor visibility in high ambient light conditions.

The use of twin optical modulators is known, at least in theory, to overcome some of the problems with conventional large area displays. Such systems are disclosed, for example, in US Pat. Nos. 4,844,577 and 5,052,777, which are assigned and registered to Sportssoft, Burnaby, Canada. The advantage of these systems is that displays using paired bodies are not limited in light intensity at each pixel location by the physical properties of all secondary emission materials such as phosphors. In addition, such displays can send light from a light source to a very large number of pixels by means of optical channels such as fiber optic light guides, thereby deflecting the electron beam to raster scan the entire display. It can be made very large because there is no need to make it.

The approach chosen by the Sportsoft patent and such an approach is problematic in that the assembly of these twin system systems is too complicated and requires a large labor force, and as a result, the system has difficulty in market competitiveness. Thus, there is a need for an improved twin system suitable for simpler and automated manufacturing methods than prior art systems.

FIELD OF THE INVENTION The present invention relates to the use of optical shutters to switch light from fiber ends, and more particularly to the use of piezoelectric bimorphs as optical shutters for display screen applications.

1 shows a piezoelectric shutter system constructed in accordance with the principles of the present invention.

2 is a cross-sectional view showing a piezoelectric paired body used as an optical fiber shutter.

3 is a waveform diagram showing the output of the optical sensor disposed in front of the optical fiber / shutter.

4 is a perspective view of a preferred embodiment of the present invention.

FIG. 5 is an elevational view showing additional details of the light source in the embodiment of FIG. 4.

6 illustrates pixel arrangement for a screen module constructed in accordance with the principles of the present invention.

7A is a side view illustrating a single paired body attached to a mounting insert.

Fig. 7B is a plan view showing a single paired body attached to the mounting insert.

8A is a side view illustrating the twin comb portion constructed in accordance with the principles of the present invention.

8B is a plan view of the paired comb teeth constructed in accordance with the principles of the present invention.

FIG. 9 is a front view of the protruding stop that makes contact with the twin body in the open and closed positions. FIG.

FIG. 10 is a perspective view showing an embodiment in which an infrared coating is used on the rear side of the shutter as the paired body of the present invention.

FIG. 11 is a perspective view similar to FIG. 10, showing another embodiment in which an infrared reflecting foil is used on the rear side of the shutter as the underbody of the present invention.

12 is a cross-sectional view of the twin of the present invention in an open (“on”) position.

FIG. 13 is a cross-sectional view similar to FIG. 12 showing the twin of the present invention in a closed (“off”) position. FIG.

The present invention relates to a piezoelectric shutter disposed in a comb pattern, the piezoelectric shutter including a central structure having one or more teeth forming the shutter, wherein the central structure comprises: Lifting enables the displacement of the shutter by the piezoelectric effect. This approach is very effective in minimizing labor costs and improving quantitative production capacity.

The means known in the art have serious drawbacks. The present invention aims to solve these disadvantages.

That is, the present invention proposes that one or more paired bodies can be disposed on the support and lifted against the support by the piezoelectric effect to enable the shutter action.

According to a preferred embodiment, each of the paired bodies described above is attached to the comb support.

According to a preferred embodiment the adhesive material is administered dropwise to enable the capillary effect to the extent that the displacement action can take place. As a result, the ultralight pairs can be properly aligned to achieve precise position control, which makes the shutter system very reliable.

According to a more preferred embodiment the selected adhesive material is a material which can be polymerized. That is, when the polymerization reaction of the adhesive material occurs after the adhesion treatment occurs shrinkage action.

According to a more preferred embodiment the adhesive material is photosensitive to ultraviolet radiation. That is, when radiation is applied on the bonding region, fixation is achieved by adhesion of each pair.

According to a particular embodiment of the present invention, each paired body can be bent in any direction as desired, at a certain angle or more at one end thereof, but is preferably bent in the direction of the support described above. This structure allows for a direct shutter action by the pair itself. The piezoelectric effect causes a momentary rise of the paired bodies to enable the passage of light or to allow the shutter to act as a descending position.

According to a more specific embodiment of the present invention, each pair is bent at essentially right angles to enable an easy shutter effect.

According to a more preferred embodiment a stop is arranged in the device to limit the upward stroke of the paired body to prevent erroneous vibrations.

According to a preferred embodiment of the present invention, the stops described above are protruded so that the bent ends of the paired bodies do not strike the stops and are disposed from the bent ends of the paired bodies to the opposite ends. In this way, the bent edges of the pair can be stuck to the stopper during opening and closing of the shutter, thereby preventing the shutter from operating properly.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention, together with additional features and advantages thereof, will be better understood by reference to the following description in conjunction with the accompanying drawings.

The present invention can be used mainly in large area optical fiber display devices in which piezoelectric shutters according to the present invention can be used. The availability of new polymeric piezoelectric materials has made it possible to develop new, lightweight shutters with high brightness. When used to switch light at an optical fiber end, a large video color display device can be conceived.

The development of xenon for the efficient and uniform supply of small fiber bundles (bundles) has now made it possible to develop display devices with very high brightness. This type of system is described below.

Piezoelectric materials are well known. These materials include crystals such as crystals and ceramics such as PZT. Piezoelectric phenomena result from the presence of permanent internal polarization in the dielectric. Mechanical stresses change the dipole moment, resulting in an external electric field. Conversely, when an external magnetic field is applied, the dipoles rearrange themselves, causing mechanical deformation.

Recently, piezoelectric polymers have been developed. These polymers are available in sheet and roll states with thicknesses between 9 microns (μm) and 1 millimeter (mm) and are used in many applications (primarily as light gates).

Referring now to FIG. 1, two sheets of piezoelectric polymers 10 and 12 having different polarities are bonded to form a bending element or pair 14.

When a stress is applied to generate an applied voltage, one of the ground layers 10, 12 expands or expands, while the other layer contracts, causing the assembly to bend or flex. If stress is applied in reverse polarity, the pair will bend in the opposite direction. The dimeric structure translates a small change in length into the motion of the end 16 of the dimeric body.

If the end 16 is bent at a right angle and the assembly is placed on the optical fiber 18 as shown in FIG. 1, the end switches the light emitted from the closed and open optical fibers, respectively.

As shown in FIG. 2, an experiment was performed on the bending / bending of the paired body showing the effect of the adhesive layer on the metal constituting the inherent layers of the paired body. Once the model is extracted from it, the model results in selection criteria for length, adhesive, and metal thickness.

3 is a graph showing the waveform recording the output of an optical sensor disposed in front of an optical fiber / shutter constructed in accordance with the principles of the present invention. The rise and fall time appears to be 3 milliseconds (msec). The tip deflection is 2.5 mm for an active length of 25 mm and an applied voltage of 250 volts (V). Models with non-uniform thicknesses and widths have also been developed. Analytical formulas are very complex and solutions are approximated using approximation methods and symbolic programming. Inconsistent dimensions have not been shown to improve in rise time or bending.

When a device is used, it begins by considering that the screen consists of many modules of relatively small size (eg 180 mm × 180 mm).

The basic element of each module 20 (FIG. 5) consists of a plate 22. Each plate 22 itself is a certain number, for example 30 optical fibers 18, 30 paired shutters 24 arranged in a comb pattern, PCB printed circuit wafer and shutters. Contact points for controlling them. This assembly is shown exploded in FIG. 4. Each pair 14 is attached to a rigid or flexible mounting insert 27 (FIGS. 7A, 7B, 8A, 8B) to assemble a plurality of pairs into the comb assembly 26. Thirty plates are preferably made of thirty optical fiber networks with optical fibers having a periodicity of 6 mm by configuring the module 20 as shown in FIG. 5. The optical fibers are gathered into three separate bundles 28 at the rear end of the module (upstream with respect to the direction of transmission of the passing light), and each plate is connected to a control printed circuit wafer. In addition, red, green and blue dichroic filters 30 are placed in front of each individual bundle.

The illumination is preferably provided as a 60 Watt metal halide discharge lamp 40 (FIG. 5). Light is combined in mixer 42, which allows for maximum and uniform illumination of red, green, and blue bundles on each module. The illumination of module 20 ranges from peak white to 20,000 nits (Candela / m ² per square meter). Each module surface is shown in FIG. 5 to ensure the required contrast and viewing angle. It is protected by a louvered optical network as described above, which is designed to enable thermal insulation of the module 20 by using a sandwich arrangement with an air gap.

When assembling, the spacing from module to module maintains a spacing of approximately 6 mm between the optical fibers, with no visible gaps or gaps between them.

As shown in FIG. 6 with respect to the placement of the pixels 50 and the generation of the gray scale, each of the pixels consists of three per color and thus nine optical fibers. The naked eye is less sensitive to the diagonal structure, so the colors are arranged along the diagonal structure. The spacing of successive pixels is preferably approximately 18 mm.

Since the paired bodies of the present invention are basically on-off devices, gray levels can be generated by modulation of the pulse width. Due to the limited dynamics of the dimorphs, the image period can be converted to 40 images per second in a PAL or NTSC system using digital filtering. In general, only 3 gray levels can be generated in known devices. Problems also arise in terms of image refresh rate, given the bandwidth limitations of the mechanical frequency response of the pair.

Since the apparatus uses three optical fibers of different sizes per color in one pixel, it is possible to increase the number of gray levels if the optical fibers are made at the correct ratio to avoid redundancy and have a uniform level of spacing. In this embodiment, a surface ratio of 1 to 3 is used. That is, if three levels per fiber are used, 27 levels per color can be generated. This translates to approximately 5 bits per color.

In operation, each optical fiber 18 has an upper position at which the optical fiber 18 is opened relative to one or more upper stops or protrusions 60 (FIGS. 9 and 12) and one or more lower stops or protrusions 62 (FIG. 9). And by operating the dipole 14 between the lower positions where the shutter 24 covers the distal end of the optical fiber 18 and prevents light from being emitted from the end by closing the optical fiber 18 with respect to FIG. It can be selectively turned on and off (blocked). The twin is only in contact with the protruding stop in the open and closed positions.

An important aspect of the present invention is shown in FIG. The upper protrusion 60 is placed in the critical region as shown in FIG. 12 so that all types of excitation oscillations of the moving pair can be braked.

10 and 11 show another preferred concept of the invention, i.e., by applying an infrared coating 70 (FIG. 10) or an infrared reflecting foil 80 (FIG. 11) by means of an adhesive or the like on the back of the shutter. Attach and use. This infrared coating or foil reflects heat generated from the light source, thereby preventing the shutter 24 from being damaged by overheating.

Another embodiment is obtained by using an algorithm that distributes multilevel error spreading with threshold modulation. The image rate can be high enough to avoid flicker. Critical flickering frequency increases with brightness or brightness and surface dimensions. Also, the naked eye is less sensitive to flicker of lines when they are diagonal. This effect was used as shown in FIG. 6, which produces significant results.

According to the screen structure, the module 20 is arranged in the sub-screens of the 48 modules. The subscreens are combined to form a screen of any dimension or shape. The frontal surface is uniform and there is no visible boundary between the modules and each subframe.

While the invention has been described with respect to particular examples and embodiments, it should be understood that the invention is not limited to these examples and embodiments, but may be practiced in various ways within the scope of the following claims.

Claims (15)

In a piezoelectric shutter having a support structure and disposed in a comb pattern provided with at least one tooth projection, the support structure is arranged to be lifted to enable displacement of the shutter by a piezoelectric effect, And one or more paired bodies disposed on the support and constituting a shutter that can be lifted with respect to the support by a piezoelectric effect. The piezoelectric shutter according to claim 1, wherein the paired bodies include two sheets attached to each other and having different characteristics. The piezoelectric shutter of claim 1, wherein the paired body is adhered to the comb support. The piezoelectric shutter according to claim 1, wherein each paired body is bent at a predetermined angle or more in a direction of the support at one end of the shutter. 5. A piezoelectric shutter according to claim 4, wherein each pair is bent at substantially right angles. 6. The piezoelectric shutter according to claim 5, wherein a stop is disposed in the device so as to limit the stroke of the paired body to prevent vibration. 7. The piezoelectric shutter according to claim 6, wherein the stop is protruded and deeply disposed from the bent end to the opposite end of the paired body so that the angled portion does not strike the stop. The piezoelectric shutter according to claim 1, wherein a nail member is provided to prevent the paired body from escaping out of the gauge. The piezoelectric shutter according to claim 1, further comprising one tooth protrusion in the comb teeth. 10. The piezoelectric shutter according to claim 9, comprising four tooth protrusions in the comb teeth. The piezoelectric shutter of claim 1, wherein the stop is provided within a limit of a critical stop area. 12. The piezoelectric shutter of claim 11, wherein the stop is configured of a minimum protrusion. The piezoelectric shutter of claim 1, wherein the paired support is transparent to which ultraviolet radiation can pass to obtain instantaneous adhesion. The piezoelectric shutter according to claim 1, wherein an additional coating is provided for the paired body as a connecting member or a coating. 15. The piezoelectric shutter of claim 14, wherein the coating strongly reflects infrared radiation and visible light.