JP2005300746A - Information display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose an information display device in which a moving picture is displayed with sufficient brightness and at high speed, in which no color breakup phenomenon is produced, further which is little influenced by temperature rise and which is stably operable for a long period of time so as to stand outdoor use. <P>SOLUTION: In the information display device equipped with a light source 1, a color filter 2, a light shutter 3 and an optical fiber bundle 4 on which light passed through the light shutter 3 is made incident and of which the output side is used as an information display part, the color filter 2 is a color wheel, a plurality of optical switching elements are one dimensionally or two dimensionally arrayed on the light shutter 3, the optical switching elements are formed by using a ferroelectric liquid crystal which shows a polymer stabilized V shaped switching characteristic, the light shutter 3 is disposed by being separated from the color filter 2, and the information display device is equipped with a control circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information display device, and more particularly to an information display device that switches light using an optical fiber and an electro-optic element.

Many information display devices using LEDs, CRTs, LCDs, and PDPs have been proposed and put into practical use as information display devices. However, it has been pointed out that they are not bright enough for outdoor use.
On the other hand, in order to obtain sufficient brightness, an incandescent lamp is used as a light source, and the light is guided to a display unit with an optical fiber.

FIG. 9 is a conceptual diagram of an example of such an information display device according to the prior art.
As shown in the figure, the light from the light source A1 is condensed on the optical shutter A3 by the lens A2. In the optical shutter A3, optical switching elements are two-dimensionally arranged, light is switched for each pixel, and an output thereof enters an optical fiber A4 corresponding to the pixel. The emission side of the bundle of optical fibers A4 is used as the display unit A5.

FIG. 10 is a conceptual perspective view of the optical shutter A3 of FIG.
As shown in the figure, a filter A6 that passes a predetermined color among red (R), green (G), and blue (B) is provided for each pixel, and light is switched for each pixel. An optical switching element A7 is provided. By switching light for each pixel, a color image can be displayed on the display portion A5.

  In this type of information display device, the optical shutter is realized using nematic liquid crystal. However, nematic liquid crystals have a slow switching time. Nematic liquid crystal has a practical switching time of 12 to 300 milliseconds. Therefore, this type of information display device can be used to display still images or character information, but cannot display brightly changing images or moving images.

  If an optical switching element with a slow switching time is used, it cannot be used for displaying moving images. In addition, when a viewer shakes his / her head, a so-called “color break phenomenon” occurs in which red, blue or green colors appear for a moment as noise.

  Further, the optical shutter A3 having such a structure not only has a high manufacturing cost because a fine filter A6 must be made for each pixel, but also the temperature tends to rise because each filter A6 absorbs light. The temperature of the optical switching element provided close to the filter is raised. As a result, there is a problem that the temperature characteristics of the nematic liquid crystal may be affected.

  Therefore, the present invention is bright enough to withstand outdoor use, can display moving images at high speed, does not cause “color break-up phenomenon”, is less affected by temperature rise, and is stable for a long time. It is an object of the present invention to propose an information display device that can be operated automatically.

The above-described problem has been solved by the information display device according to claim 1.
Specifically, the optical shutter uses a polymer-stable ferroelectric liquid crystal with V-shaped switching characteristics instead of the conventional nematic liquid crystal, and the optical shutter and the color filter are arranged separately. It was done.

  That is, a light source, a color filter that passes light of a specific color in the light from the light source, an optical shutter that switches light that has passed through the color filter, and light that has passed through the optical shutter is incident on its output side In an information display device comprising a bundle of optical fibers that use as an information display section, the color filter has a plurality of optical filters that allow light of different specific colors to pass therethrough, and the light from the light source sequentially passes through the optical filters. And a ferroelectric liquid crystal in which a plurality of optical switching elements are arranged in a one-dimensional or two-dimensional manner on the optical shutter, and the optical switching elements exhibit polymer-stable V-shaped switching characteristics. The optical shutter is disposed separately from the color filter, and the color filter It was resolved by the information display device comprising a control circuit for controlling synchronizes the serial optical shutter.

  According to the information display device according to the present invention described above, it is possible to realize an information display device that is bright enough to withstand outdoor use and that can display moving images and that does not cause color breakup. . Further, in the present invention, since a structure that reduces the influence of temperature on the liquid crystal material is employed, it is possible to operate stably for a long time.

Hereinafter, the best mode for carrying out the above-described information display device according to the present invention will be described in detail with reference to the drawings.
In this specification, “V-shaped characteristics” or “V mode” means that the light transmittance is symmetric from zero to positive and negative voltages when the voltage applied to the liquid crystal is increased from zero to the plus and minus directions. This means an increasing characteristic.

  There are the following two methods for manufacturing a ferroelectric liquid crystal having a V-shaped characteristic stabilized by a polymer.

In the first method, a photopolymerizable monomer is added to a ferroelectric liquid crystal, and ultraviolet irradiation is performed while an AC voltage is applied in a smectic C * phase. As a result, the ferroelectric liquid crystal molecules are stabilized by the side chain polymer.
This method is described in detail in the following literature.
"Y. Miyazaki, et al: Mol. Cryst. Liq. Cryst. 364 (2001) 491."

The second method is a method in which, in the smectic A phase, photopolymerization is performed by irradiating ultraviolet rays without applying an electric field, thereby stabilizing the polymer.
This method is reported in detail in both of the following documents.
"S. Kataokoa, et al: Mol Cryst. Liq. Cryst. 292 (1997) 333."
"M. Shikada, et al: Jpn. J. Appl. Phys. 40 Pt. 1 (2001) 5008."

The present inventor reports the production and electrical characteristics of a polymer-stabilized V-mode ferroelectric liquid crystal electro-optical element in the following literature.
FIG. 1 is an experimental example of V-mode characteristics of an optical switching element reported in the magazine.
“S. Kobayashi, et al: Proceedings of SPIE Vol. 5003, 88 (2003). ]

FIG. 2 is a conceptual diagram of an embodiment of an information display device according to the present invention.
As shown in this figure, light from a light source 1 such as a white light is irradiated to an optical shutter 3 via a color wheel 2, and light that has passed through the optical shutter 3 is transmitted through an optical fiber provided on the back of the optical shutter. It enters the bundle 4. The exit of the optical fiber bundle 4 is used as the information display unit 5.

FIG. 3 is a conceptual diagram of another embodiment of the information display device according to the present invention.
As shown in this figure, the lens 1 a can be disposed between the light source 1 and the color wheel 2 or between the color wheel 2 and the optical shutter 3 as necessary. In addition, a mirror 1b can be arranged behind the light source 1.
By arranging the light condensing means including these lenses 1a or mirror 1b, the amount of light can be increased and the brightness of the display device can be increased.

  The light source 1 is preferably an incandescent lamp whose light spectrum covers almost the entire visible light. Even if it is not an incandescent lamp, if it is a light source having a spectrum including at least light components in the red, green and blue regions, almost full color display is possible.

FIG. 4 is a conceptual perspective view of the color wheel 2 and the optical shutter 3 described above.
As shown in this figure, in the color wheel 2, the red filter (R), the green filter (G), and the blue filter (B) are arranged on the rotating wheel 2a so as to divide the circle, and the rotation driving means 2b It is intended to rotate. When the white light W is incident on the color wheel 2, if the rotating wheel 2a is rotated, the red light (R), the green filter (G), and the blue filter (B) are sequentially passed through, so that the output light is sequentially red. Light R, green light G, and blue light B are incident on the optical shutter 3.

When the white light W passes through the red filter (R), the green filter (G), and the blue filter (B), the temperature of the filter tends to increase due to light absorption. There was a problem that the temperature increased.
However, in the present invention, since the color wheel 2 and the optical shutter 3 are disposed separately as described above, the problem of temperature rise in the optical shutter 3 is greatly reduced. Of course, the color wheel 2 and / or the optical shutter 3 can also be cooled by air cooling or water cooling.

  Depending on which of the red filter (R), the green filter (G), and the blue filter (B) the white light W has passed through, the optical switching element corresponding to each pixel in the optical shutter 3 Change the transmittance. Therefore, it is necessary to know which filter has passed at a certain moment. For this reason, the rotation driving means 2b is realized by a digitally controlled pulse motor, the rotation angle is controlled by the control circuit 6, or is realized by a normal analog motor, and a marker 2c is attached to the rotating wheel 2a to provide a sensor. The light from the light source is received by the photo sensor 2d, etc., the rotation angle of the rotating wheel 2a is detected, the detection signal is sent to the control circuit 6, and the control circuit 6 knows which color filter has passed.

  In the optical shutter 3, optical switching elements 7 corresponding to the respective pixels are arranged one-dimensionally or two-dimensionally. Then, the image corresponding to the color of the light that has passed through the filter is sequentially formed by the optical switching element 7.

FIG. 5 is a conceptual cross-sectional view of one optical switching element 7 taken out. FIG. 5A shows a state where no voltage is applied, and FIG. 5B shows a state where a voltage is applied.
This optical switching element 7 is provided inside a pair of glass substrates 8a and 8b, transparent conductor films 9a and 9b provided on the inner surfaces of both glass substrates 8a and 8b, and both transparent conductor films 9a and 9b. An alignment film 10a, 10b, a polymer-stable ferroelectric liquid crystal 11 having V-shaped switching characteristics filled between the alignment films 10a, 10b, and a polarization plane disposed outside the glass substrates 8a, 8b. Consists of a pair of polarizing plates 12a and 12b orthogonal to each other.

The light transmittance is changed by applying a voltage between the transparent conductor films 9a and 9b.
FIG. 5A shows a state in which no voltage is applied, and FIG. 5B shows a state in which a voltage is applied. As shown in the figure, the liquid crystal state changes depending on the voltage, so the transmittance of the light L changes. To do.

  Usually, the transparent conductor films 9a and 9b are made of, for example, ITO (Indium Tin Oxide), and the alignment films 10a and 10b are made of a polyimide film. The functions of these members, the liquid crystal 11, the polarizing plate 12, and the like are well known to those skilled in the art. Therefore, further explanation is omitted.

In the polymer stable ferroelectric liquid crystal 11 used in the present invention, as shown in FIG. 1, the applied voltage and the light transmittance have V-shaped switching characteristics. That is, the transmittance can be continuously changed from zero, and the light transmittance has no hysteresis characteristic. Accordingly, the display color can be continuously changed to operate in full color.
In addition, FIG. 1 shows the light transmittance (vertical axis) with respect to the applied voltage (horizontal axis) measured at various temperatures (25 ° C., 40 ° C., 55 ° C.). However, the light transmittance is shown on an arbitrary scale.

  Moreover, in the case of the conventional nematic liquid crystal, the practical switching time is 12 to 300 milliseconds as described above, whereas in the liquid crystal used in the present invention, it is an order of magnitude in 100 to 300 microseconds. It is fast.

FIG. 6 is a conceptual diagram of an optical shutter when the optical shutter is realized as a simple matrix of optical switching elements.
As shown in the figure, the transparent conductor films 9a, 9b provided on the lower surface of the pair of glass substrates 8a and the upper surface of the glass substrate 8b, respectively, are formed in a plurality of parallel strips that are electrically separated from each other. The direction of the linear transparent conductor film of one glass substrate and the direction of the linear transparent conductor film of the other glass substrate are orthogonal, so that the optical switching elements are arranged one-dimensionally or two-dimensionally. An optical shutter is formed.

  In synchronization with the color of the light passing through the color wheel 2, by selecting one line-shaped transparent conductor film on each glass substrate and applying an appropriate voltage, the color corresponding to a specific pixel is selected. The transmittance can be changed.

FIG. 7 is a conceptual perspective view of an example of an optical shutter in which the optical shutter is realized as an active matrix of thin film transistors.
As shown in the figure, a transparent conductor film 9b provided on one of the glass substrates 8a and 8b is formed on a plurality of island-like portions 9c that are electrically separated from each other and are arranged one-dimensionally or two-dimensionally. A thin film transistor is formed on each island-like portion 9c, and a transparent conductor film 9a is uniformly formed on the other glass substrate 8a, so that the optical switching elements are arranged in a one-dimensional or two-dimensional manner. Has been.

  When the optical shutter is realized as an active matrix of a thin film transistor, an optical shutter having 1000 × 1000 pixels or more can be easily realized. By selecting a thin film transistor in synchronization with the color of light passing through the color wheel 2 and applying an appropriate voltage, the transmittance of that color corresponding to a specific pixel can be changed. Various driving methods for the thin film and the transistor matrix have been proposed and are well known to those skilled in the art, so further explanation is omitted.

  When the entrance of the optical fiber 4 is arranged at the back of each optical switching element 7, as shown in FIG. 8A, it is possible to arrange one optical fiber 4 for each optical switching element 7. As shown in (b), a plurality of optical fibers 4 can be arranged for each optical switching element 7.

  Since the information display apparatus according to the present invention has a large amount of light, a lens may be provided at the exit of the optical fiber 4 to form the information display unit 5 that projects information on the screen.

  The embodiment of the information display device according to the present invention has been described above. However, the present invention is not limited to the embodiment described above, and the technical idea of the present invention described in the claims. It goes without saying that various modifications and changes can be made within the range described above.

It is the figure which showed the experimental example of the V mode characteristic of an optical switching element. It is a conceptual diagram of embodiment of the information display apparatus which concerns on this invention. It is a conceptual diagram of other embodiment of the information display apparatus which concerns on this invention. It is a conceptual perspective view of the part of a color wheel and an optical shutter. It is a conceptual sectional view showing one optical switching element taken out, (a) shows a state where no voltage is applied, and (b) shows a state where a voltage is applied. It is a conceptual diagram perspective view of an optical shutter when an optical shutter is realized by a simple matrix of optical switching elements. It is a conceptual perspective view of an example optical shutter which realized an optical shutter as an active matrix of a thin-film transistor. It is a conceptual sectional view showing the relationship between each optical switching element and an optical fiber, where (a) shows a case where one optical fiber is arranged for each optical switching element, and (b) A case where a plurality of optical fibers are arranged is shown. It is a conceptual diagram of an example of the information display apparatus by a prior art. It is a conceptual perspective view of the optical shutter by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 1a Lens 1b Mirror 2 Color wheel 3 Optical shutter 4 Optical fiber 5 Information display part 6 Control circuit 7 Optical switching element 8a, 8b Glass substrate 9a, 9b Transparent conductor film 10a, 10b Orientation film 11 It has V-shaped switching characteristic Polymer stable ferroelectric liquid crystal 12a, 12b Polarizing plate

Claims (6)

  A light source, a color filter that passes light of a specific color in the light from the light source, an optical shutter that switches the light that has passed through the color filter, and light that has passed through the optical shutter is incident and the output side is information In an information display device including a bundle of optical fibers used as a display unit, the color filter includes a plurality of optical filters that allow light of a specific color different from each other, and a mechanism that sequentially passes light from the light source through the optical filters. Using a ferroelectric liquid crystal in which a plurality of optical switching elements are arranged in a one-dimensional or two-dimensional manner on the optical shutter, and the optical switching elements exhibit polymer-stable V-shaped switching characteristics. Formed, the optical shutter is disposed separately from the color filter, the color filter and the optical shutter. Characterized in that it comprises a control circuit for controlling synchronizes the data, information display device.   The color filter includes a rotating plate in which a red filter, a green filter, and a blue filter are arranged in a circle, and a rotation drive system that rotates the rotating plate, and sequentially turns red light, green light, and blue light to the optical shutter. The information display device according to claim 1, wherein the information display device is a color wheel that is fed to   The information display device according to claim 1, further comprising a condenser lens between the light source and the color filter and / or between the color filter and the optical shutter.   The optical switching element is filled between a pair of glass substrates, a transparent conductor film provided on the inner surfaces of the glass substrates, an alignment film provided on the inner sides of the transparent conductor films, and the alignment films. A polymer-stable ferroelectric liquid crystal having V-shaped switching characteristics and a pair of polarizing plates arranged on the outside of each glass substrate and having polarization planes orthogonal to each other, and a voltage is applied between the transparent conductor films. The information display device according to claim 1, wherein the light transmittance is changed by applying the information.   The transparent conductor film provided on each of the pair of glass substrates is formed in a plurality of parallel wires that are electrically separated from each other, and the direction of the transparent conductor film on one glass substrate and the other glass substrate 5. The information according to claim 4, wherein an optical shutter in which the optical switching elements are arranged one-dimensionally or two-dimensionally is formed by making the directions of the transparent conductive film filaments orthogonal. Display device.   A transparent conductor film provided on one of the two glass substrates is formed in a plurality of electrically isolated island portions arranged one-dimensionally or two-dimensionally, and a thin film transistor is formed on each island-shaped portion. 5. The information display device according to claim 4, wherein an optical shutter in which the switching elements are arranged one-dimensionally or two-dimensionally is formed.

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