RU2563120C2 - Optical modulator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: in an optical modulator each pixel or subpixel comprises superimposed fixed flat polariser and movable flat polariser, which is magnetised in the plane of the polariser at a given angle to the transmission plane of the polariser and configured to turn about an axis perpendicular to the polarisers. The optical modulator has means of reading the position of movable polarisers, which include sensors of the direction of the magnetic field (direction of the magnetic induction vector) of each movable polariser and means of retrieving information from the sensors.

EFFECT: reduced image flicker and saving power.

9 cl, 2 dwg

Description

The invention relates to the field of information processing: to the design of optical modulators, which are an integral part of screens, “electronic paper” and optical switch-converters (switching with simultaneous modulation), and, in particular, to the design of their reading and writing means.

Known screens in which the image is formed by scanning a light beam using micromirrors, driven by microelectromechanical drives (actuators) [U.S. Pat. No. 6856445, 7116462, 7102808, 7016099, RU 2276774, 2277265]. They need to illuminate the mirrors with directional light sources with high-frequency regulation of its intensity and color manipulation, also high-frequency. The processes of formation of dynamic and static images do not differ in them.

A screen is known in which the image is formed by flipping flaps in the form of flags with a fixed axis of rotation, overlapping or opening microholes for the passage of light [US 20040080484 A1]. Its disadvantage is the need to adjust the brightness of each pixel individually using an additional device.

A screen is known, each pixel of which contains an optical microelectromechanical regulator in the form of a shutter that moves due to the unequal lengthening of the two consoles during unequal heating and overlapping partially or fully the light flux through the hole [U.S. Pat. No. 6775048, 6967761, 7151627].

Its disadvantage is the complexity of the design and manufacturing technology, the need to create three-dimensional microelectromechanical structures and microelectronic structures within each pixel, image loss when the power is turned off, the difficulty of combining a backlight lens system that focuses the entire light flux on a multitude of microholes, and a similar lens system for image formation after the light passes through the optical regulators.

The closest analogue of the proposed optical modulator is the screen [Pat. RF No. 2473935, WO / 2010/114417], containing optical regulators corresponding to each pixel, characterized in that the optical regulator is made in the form of two flat polarizers superimposed on one another, one of which is stationary, the second has an area that covers the area of the pixel, and made with the possibility of rotation relative to the first around a fixed axis normal to their planes, and also contains means for implementing such a rotation. The screen has means for reading, processing and transmitting information about the position of the movable elements of the regulators in the form of a capacitance monitoring unit between the stationary electrodes and the electrodes deposited on the movable polarizers. A variant of the screen is also described in which the moving polarizers are magnetized. A pen with a permanent magnet or an electromagnet is proposed as one of the means of image formation on the described screen, creating a local magnetic field parallel to the screen plane in the region of the writing end.

The disadvantage of the prototype, namely, the disadvantage of its reading means containing many capacitive electrodes (capacitor plates) for each pixel, is the need for electronic interrogation of a large number of capacitive sensors and the associated time and energy costs. Another disadvantage is the technological complexity of the exact positioning of the created contacts, which is associated with the small size of the contacts and high requirements for their relative positioning.

The aim of the invention is to improve the operational characteristics of the screen and increase manufacturability.

This goal is achieved by the fact that each pixel (subpixel) of the optical modulator (hereinafter referred to as the pixel) comprises a stationary flat polarizer and a movable flat polarizer superimposed magnetized in the plane of the polarizer at a given angle to the plane of transmission of the polarizer and can be rotated around perpendicular polarizers axis (real or imaginary), and also contains means of reading, providing a determination of the direction of magnetization of the moving polarizer of each pi mudflow. The optical modulator may also comprise means for recording (forming) an image.

Reading information about the degree of opening of the optical shutters (pixels) of the optical modulator is based on the fact that the brightness of each pixel is determined by the angle of rotation of the moving polarizer relative to the stationary one. Due to the fact that the moving polarizer has magnetization in the direction perpendicular to its axis of rotation, the direction of the magnetic field of the moving polarizer can be used to judge the magnitude of the angle between its transmission plane and the transmission plane of the stationary polarizer. To determine the direction of the magnetic field (the direction of the magnetic field induction vector) of the moving polarizer, any known magnetic field sensor can be used to judge the direction of the magnetic induction vector of this field. In the embodiment of the invention, the sensors, the magnetic field direction of the moving polarizers are sensors, the resistance of which depends on the direction and / or magnitude of the magnetic, including sensors, the action of which is based on:

- either on the magnetoresistive effect [Hari Singh Nalwa Handbook of thin film materials: Nanomaterials and magnetic thin films. - Academic Press, 2002. - Vol. 5. - P.514. - 633 p. - ISBN 9780125129084; RF No. 2279737],

- either on a giant magnetoresistive effect [The Nobel Prize in Physics 2007 (eng.). The Official Web Site of the Nobel Prize; Nikitin S.A. Giant magnetoresistance // Soros heating journal. - 2004. - T.8. - No. 2. - S. 92-98. US 5159513; WO 00/79298; EP 0905523],

- either on the colossal magnetoresistive effect [Colossal Magnetoresistance, Charge Ordering and Related Properties of Manganese Oxides / Ed. by C. N. R. Rao and B. Raveau. - World Scientfic Publishing Co., 1998. - P.1-2. - 356 p.- ISBN 978-981-02-3276-4],

- either on the tunnel magnetoresistive effect [S.S.P. Parkin, S. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant, S.-H. Yang, Giant tunneling magnetoresistance at room temperature with MgO (100) tunnel barriers, Nat. Mat. 3: 862-867 (2004); RF No. 2392697].

The sensors are located in the zone of action of the magnetic field of the moving polarizer so that the action of the fields of adjacent moving polarizers does not affect the sensor signal or affect it to a minimum. This zone is determined for each specific case, taking into account the degree of magnetization of the moving polarizers and the sensitivity of the sensors, theoretically, experimentally, or a combination of these approaches.

The conclusions of each sensor are connected - directly or through the elements of electrical isolation of the circuits - with the corresponding conductive buses (with buses of "columns" and "rows", "address" and "bit", with address bus and data bus), connected, in turn, with a reader electronics. The use of address and bitmap matrices is widely used in memory matrices, including operational, in LCD screens, etc. [for example, US 6531371 B2]. Their disadvantage is the possible blurring of targeting due to, for example, current spreading: the recording signal penetrates beyond the node to which the signal is addressed, due to the large number of interconnects between the buses. Known means of galvanic isolation of nodes in the form of a field effect transistor connected in series with the interrogated node [US 6462388 B1; A stackable cross point phase change memory. DerChang Kau et al. Intel Corporation, Technology and Manufacturing Group, SC9-09, 2200 Mission College Blvd, Santa Clara, CA 95054 USA §: Numonyx B.V., R&D - Technology Development, 2550 N. 1st Street, Suite 250, San Jose, CA 95131]. The disadvantage of the latter means is the need for numerous operations for the manufacture of transistors and the limited miniaturization of the design features of transistors.

To prevent current spreading along the bus matrix in the proposed optical modulator, a diode is connected in series with the magnetic field sensors of each pixel. At the same time, during reading, any other path for the current, except for the path through the selected address and bit buses and the sensor at their intersection, is excluded by the on-board diodes. An element decoupling the circuit is not required for use in the proposed device, but, with certain design parameters of the device, it can significantly improve the accuracy of reading. The resulting dependence on radiation is not critical, because Under the influence of radiation, the reverse conductivity of the diodes only increases (and that only at the moment the ionizing particle passes through this diode), which only theoretically reduces the efficiency of increasing accuracy, but does not interfere with reading. (Corresponding electronic reading and imaging units are assumed to be made by integrated technology, i.e., unlike the optical modulator, they are small in size, and it is not necessary to see them, therefore they can be protected from radiation by placing, for example, in a lead case .)

In an embodiment of the invention, the movable polarizer is rotatable around its axis within 90 °, and the magnetoresistive sensor is made in the form of a fixed strip located near the surface of the movable polarizer, which intersects, in plan, the region of the movable polarizer, and is connected by its findings directly or via an electric element decoupling circuits - with the corresponding conductive busbars, and the sensor is oriented so that in one extreme position of the moving polarizer the direction of its vector The impedance was parallel to the direction of the maximum sensitivity of the field sensor, and at its other extreme position it was perpendicular. The strip may contain additional auxiliary layers (adhesive, insulating, tribo-resistant, etc.).

To eliminate or reduce the influence of magnetoresistive reading strips on optical transmission, they can be made either transparent, or partially transparent, or banded, and / or in the form of a meander oriented along or across the strip forming the sensor. When using the latter option (meander), the sensitivity of the sensor can be increased. In order to prevent a critical decrease in optical transmittance (the usual criterion is a change in e times) when using opaque sensors, their width, if they have the shape of a strip crossing the pixel area, should not exceed a third of the diameter of the moving polarizer, and when using sensors of a different topology, the sensor area must exceed the third of the pixel area.

In an embodiment of the proposed screen, a recording means, i.e. Means for rotating the movable polarizers and readings contain a unit for comparing recording signals with signals about the position of the moving polarizers and outputs signals to the recording system that correct the position of the corresponding moving polarizers in cases where correction is required and does not produce if not required.

The image recording means, in addition to the option using electronically controlled actuators, can be performed in the form of an external magnetic field source: either local (magnetic stylus), or scanning, or distributed in a predetermined manner. Using a magnetic stylus provides the ability to write-erase or draw on the screen, a reading system allows you to save the image created on the screen. An image on a screen can be created by scanning a controlled source of a magnetic field across the screen or by simultaneously applying a magnetic field to a screen with a specified configuration (pattern) - these are options that make it easy to replicate images in electronic paper (as is done with printers or photo printing).

Mobile magnetic polarizers may contain - to ensure magnetic properties - magnetic inclusions in the volume of the moving polarizer, magnetic coatings on the surface or on the surfaces of the moving polarizer (either partially or completely transparent, or occupying only part of the surface of the moving polarizer, etc.), magnetic elements mounted on the surface of a moving polarizer, or other known means of ensuring magnetization (for example, a polarizer made of a material that is simultaneously a magnet).

The screen may contain other well-known components and units, for example: structural walls; designs to facilitate and provide rotation of the movable polarizers; structures for specifying the distribution of mobile polarizers on the surface; a matrix of pigment or dichroic filters arranged in a predetermined order in accordance with the arrangement of color subpixels; backlight (back or front); rear diffuse or mirror reflector; a mask for overlapping areas outside the pixels; layers to reduce friction between friction surfaces; layers to reduce wear of the rubbing elements; hardening layers; layers for protecting external surfaces from mechanical stress; antireflective and anti-reflective layers; elements for setting the distance between layers; single-layer or multi-layer installation layers; nodes alignment layers; attachment points and / or gluing areas with an adhesive layer and others.

Figure 1 schematically shows the main elements of the proposed device in the lumen version (the stationary polarizer is not shown, as well as auxiliary layers and nodes, including elements for restricting rotation within 90 ° and for defining gaps between the layers).

Figure 2 shows a fragment of the proposed device corresponding to one pixel in section.

The numbers in figure 1 and figure 2 denote:

1 - layer with slots for mobile polarizers, which can also be a polarizer;

2 - movable magnetized polarizer;

3 - magnetic field direction sensor;

4 - address bus;

5 - bit bus;

6 - diode;

7 - direction of the magnetization vector of the moving polarizer at one of its possible positions (shown only for clarity);

8 - fixed polarizer;

9 - transparent solid or flexible walls, on one of which magnetoresistive sensors and read buses are formed.

An example of a specific embodiment in the “electronic paper” variant (for writing with a stylus, for example, and reading) is a 10-inch screen with a format of 600 × 800 pixels, the fixed polarizer of which is made in the form of a polarizing banded silver coating (Optiva polarizer) 2 μm thick a flexible polymer opaque back wall 0.2 mm thick. Mobile polarizers with a diameter of 20 μm and a thickness of 5 μm are, with a gap of 1 μm, in the nests of the same sheet of the polarizer, which includes ferromagnetic particles with the same direction of magnetization. The "address" and "bit" buses are made with a thickness of 0.5 μm by sputtering of chromium (coated with CrO _x to reduce reflection) on the surface of the stationary polarizer facing the moving polarizers. The magnetoresistive sensor is made of indium antimonide in the form of a strip 0.5 μm thick and 3 μm wide that intersects the region above the movable polarizer, and is connected at one end to the "address" bus, and the other via a diode to the "bit" bus. A film diode with dimensions in the plan of 3 × 3 μm and a thickness of 0.5 μm is made polymer [RF No. 2214651]. The spacing elements are sprayed with CrO _x . The layers are bonded by spot bonding. The outer walls are made of transparent flexible plastic with a thickness of 200 microns and coated with a layer of titanium nitride with a thickness of 0.5 microns to protect against scratches. The electronic components of the means of recording and reading are made in integrated silicon design.

The screen allows you to use it as electronic paper, demonstration boards (with the ability to read and save information), for the manufacture of multi-page notebooks, and when using a recording tool, for example, in the form of actuators, then also as a multi-page display with a touch screen. It does not require power to save the image, when viewing the image (reading) and making and saving notes by hand. Handwritten notes made with a magnetic stylus can be read electronically, both during recording and later.

The proposed optical modulator retains all the advantages of the prototype: non-volatility, the relative simplicity of the manufacturing technology (compared, for example, with liquid crystal, LED or gas discharge screens), the ability to control the saturation of the tone when using the stylus (unlike screens on "electronic ink"), large limits permissible temperatures, high radiation resistance (due to the absence of semiconductor active and passive elements in the composition of the pixel optical regulators lei), high reliability, lack of liquid in the screen (in particular, frost resistance, resistance to mechanical damage, reliability, expandability of application), etc., as well as additional advantages: simplicity and speed of reading, no need for generating and analyzing the variable signal (in the prototype it is used to read the image by analyzing the capacitance between the respective electrodes).

The proposed optical modulator, like the prototype, contains all the means necessary for switching optical signals, therefore, it can be used as a switch. To maintain the already established switching, it does not need power. It also creates the ability to modulate it simultaneously with the switching of the signal.

When forming moving images, the proposed optical modulator allows you to not apply unnecessary control signals to pixels that are already in the desired state, which reduces image flicker and saves energy.

Claims (9)

1. An optical modulator, each pixel or subpixel of which contains a stationary flat polarizer and a movable flat polarizer superimposed magnetized in the plane of the polarizer at a given angle to the transmission plane of the polarizer and rotatable around an axis perpendicular to the polarizers, characterized in that it contains means reading the position of the moving polarizers, including sensors of the direction of the magnetic field (the direction of the vector of magnetic induction) of each moving yarizatora and means for reading information from the sensors. 2. The screen according to claim 1, characterized in that each magnetic field direction sensor comprises a sensor, the action of which is based either on the magnetoresistive effect, or on the giant magnetoresistive effect, or on the colossal magnetoresistive effect, or on the tunnel magnetoresistive effect, and which is located in the magnetic field of the moving polarizer, and the conclusions of each sensor are connected to the means of information retrieval. 3. The screen according to claim 2, characterized in that the magnetic field sensor is located, in plan, within the area of the moving polarizer and occupies no more than a third of this area. 4. The screen according to claim 2, characterized in that the sensor is made transparent or partially transparent. 5. The screen according to claim 2, characterized in that the movable polarizer is rotatable around its axis within 90 °, and the magnetoresistive sensor is made in the form of a stationary strip located near the surface of the movable polarizer, intersecting, in plan, the region of the movable polarizer, and connected by its terminals, either directly or through an electrical isolation element, to the corresponding address and bit buses, the sensor being oriented so that it is directed in one extreme position of the moving polarizer its magnetization vector was parallel to the direction of the maximum sensitivity of the field sensor, and at its other extreme position it was perpendicular. 6. The screen according to claim 1, characterized in that it comprises means for rotating each movable polarizer and an electronic unit that generates recording control signals in accordance with the signals from the magnetic field direction sensors of each movable polarizer. 7. The screen of claim 1 or claim 6, wherein the recording and reading means comprise a memory unit of the last packet of image forming signals and a unit for comparing this packet with a packet of signals about the current position of the moving polarizers. 8. The screen according to claim 1, characterized in that the recording means is made in the form of an external source either local (magnetic stylus), or scanning, or a magnetic field distributed in a predetermined manner. 9. The screen according to claim 1, characterized in that the means for acquiring information contain electrical isolation elements in the form of diodes, each of which is connected in the same transmission direction between the address bus and the data bus in series with the magnetic field sensor of each pixel or subpixel.

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