RU130093U1 - DMD MATRIX FOR VISIBLE AND INVISIBLE RADIATION SPECTRA - Google Patents

Abstract

DMD matrix for visible and invisible emission spectra, containing a silicon crystal complementary metal-oxide-memory semiconductor with a structure formed on it, consisting of square aluminum micromirrors installed with the possibility of rotation by an angle of at least 10-12 ° to one and the other side from the neutral provisions for directing reflected radiation through a transparent window located above the indicated micromirrors in the matrix housing, characterized in that in the transparent window its central part is cut out with an image aniem frame of quartz glass, and the resulting plate is inserted into the opening of zinc selenide for transmission of radiation at infrared wavelengths from 1.5 to 15 microns, and radiation in the visible spectrum, which is glued to the end walls of the end walls of the quartz glass frame.

Description

The utility model relates to the field of microelectronics, in particular, it considers the design of the DMD-IR matrix, which is a modernized version of the DMD matrix, improved for operation in the infrared (IR) spectrum of radiation. The DMD chip (Digital Micromirror Device, a digital micromirror matrix) has been improved for use in the field of microelectronics and light control, and has undergone changes that later allowed its use in simulators, both in the visible and invisible radiation spectrum.

The DMD microcircuit is known from the prior art — it is a silicon crystal of CMOS memory (complementary metal-oxide-memory semiconductor) (Fig. 1), on which a matrix consisting of square aluminum micromirrors 1 is formed (PC Magazine / Russian Edition, Ivan Rogozhkin, article “Projector from the inside: DLP technology”, publication date: 04/06/2007) (adopted as a prototype), capable of rotating one way or another in a certain angle. If you place the light source so that in one position the micromirror 1 will direct the beam into the lens aperture, and in the other - past it, an image of light and dark pixels will be formed on the projector screen (depending on the position of the corresponding micromirror 1). Each mirror of a DMD matrix can be in three positions (neutral and two tilted), only two tilted ones are really used to form a picture in a DLP projector. Since the angle of rotation of the mirror is determined by the geometric parameters of the structure, and it is formed using accurate silicon photolithography, all elements of the DMD matrix are almost identical. The size of the mirror was originally chosen 16x16 microns, in today's matrices the size of the mirror depends on their resolution, and the deflection angle reached 12 °. Each micromirror 1 is located on a column 2, rigidly attached to a swinging beam 3, which, in turn, is suspended between two fixed columns 4 on a thin, extremely elastic and strong flexible tape 5, so that the DLP matrix can work reliably for many years (by According to Texas Instruments, the time to failure of a DMD chip in a three-matrix projector reaches 76 thousand hours. To control the rotation of micromirrors 1, the phenomenon of electrostatic attraction between the address electrode 6 mounted on the table is used ike 7, and with a yoke micromirrors 1 (assembled).

Information about the state of each pixel in the picture is recorded in its corresponding memory cell 8 - an ordinary trigger. Its antiphase outputs are connected to the address electrodes 9 of the microstructure, and therefore the contents of the memory cell affect the position of the mirror.

The operation of the DMD matrix provides for six different states. In the state of readiness of memory, all matrix triggers are loaded with the necessary information (loading is carried out sequentially, in rows). In the reset state, all micromirrors are attracted to the address electrodes 9 by a high-voltage pulse supplied to the bias bus 10, i.e. on the mirrors themselves. The state of liberation is achieved when all the mirrors are released, lining up in a neutral position, i.e. in one plane. The differentiation state provides for the supply of an intermediate voltage (between a logical zero and one) to the bias bus 10, at which the electrostatic fields between the address electrodes 6, 9 and the micromirror 1 push the freed mirror in the necessary direction, determined by the contents of memory cell 8. In the landing state on the bias bus 10, a voltage is applied at which the mirrors are rapidly attracted to the address electrodes 9, turning to a maximum angle, while the limiting protrusions 11 of the rocker arm abut in the "landing" zone 12. In the state (process) of loading the memory, the micromirrors remain motionless in one of two inclined positions, and the contents of the memory cells are updated in rows.

During operation, the DMD matrix alternately goes through six phases: reset, release, differentiation, landing, memory loading, memory readiness. The reset phase helps to overcome the sticking forces. With the small size of the mechanical structure, they are so large that the elasticity of the belt suspension alone is not enough to release the mirror. Texas Instruments realized a very original idea - to store energy of elasticity, like a crossbow, pulling a bowstring. In the discharge phase, a strong attractive electrostatic field is created, the elastic tip of the address electrode bends, and when the electrostatic field is removed and the release phase sets in, the elastic force is not only enough to push the micromirror up, but also to tear the beam from the “landing” zone.

A logic unit voltage is present on one address electrode (for five-voltage CMOS structures, approximately +5 V), and a logic zero (about 0 V) is supplied to the other. In the differentiation phase, the bias bus is grounded. The resulting force of electrostatic attraction cannot turn the mirror all the way, it only tilts it slightly in the right direction. Further, in the landing phase, a negative voltage is already applied to the bias bus, which creates a moment of force sufficient to overcome the elasticity of the suspension and rotate the mirror to a full angle. In this phase, both electrodes attract the mirror, but tend to rotate it in different directions and with different strengths. The control of mirrors on a DMD matrix is achieved by a filigree change in the voltage on the bias bus, which is formed by special electronic circuits located outside the DMD crystal. At some moments, the electrostatic field presses all the mirrors against the matrix, at others it allows them to free themselves and begin to turn, and sometimes, together with the sticking force, does not allow them to move, despite the fact that the voltage between the address electrodes can be reversed. All mirrors in the structure rotate synchronously, which favorably affects the dynamic properties of the matrix, i.e. she conveys movement well.

The heart of DLP video projectors is DMD chips (Digital Micromirror Device) (Popular Mechanics Magazine, Alexander Grek, article “My Light, Mirror: DLP Projector”, April 2003), manufactured by Texas Instruments. About 1.3 million microscopic mirrors are located on the surface of a DMD crystal, each of which is five times smaller than a section of a human hair and is responsible for one pixel in the projected image. Each spring-loaded mirror controlled by its own video memory cell, when voltage is applied to it, can deviate by a small angle (10-12 °). The actual image on the screen turns out like this: a bright light source is sent to a DMD crystal. Those micromirrors to which an electric signal is applied turn and reflect the light flux into the lens, which forms the further picture on the screen. Micromirrors, which are “inactive”, reflect light into a special black trap, the task of which is to absorb light as much as possible. The greater the angle of deviation of the mirrors, the higher the contrast: no parasitic illumination of the screen.

At the same time, the DMD matrix operates in the mode of visible and invisible emission spectra. This is due to the fact that quartz glass is used as a mirror, reflecting the incident beam in these ranges. A DMD matrix is a mirror that reflects any signal, including IR waves. The DMD matrix has no inertia of heating of the reflecting surface, which directly affects the frequency (speed) of frame changes during image transmission in the infrared range. But in order to register an image created on the basis of a DMD matrix in the infrared range, a thermal imager is needed, or rather a balometer, which is part of any equipment with a thermal imaging sensor. In order for the ballometer to be able to read the image from the DMD matrix in IR radiation with a wavelength of more than 1 μm, it is necessary to increase the thermal sensitivity of the mirror, which would allow thermal imaging sensors to respond to IR radiation signals.

This utility model is aimed at achieving a technical result consisting in improving the performance of a DMD matrix by replacing a quartz glass of a mirror with a zinc silinide plate to transmit infrared waves while maintaining the possibility of functioning and in the transmission mode of radiation in the visible range.

The indicated technical result is achieved in that, in the DMD matrix for the visible and invisible emission spectra containing a silicon crystal, a complementary metal oxide-oxide semiconductor memory with a structure formed on it consisting of square aluminum micromirrors installed with the possibility of rotation by an angle of at least 10-12 ° to one and the other side from the neutral position, for directing reflected radiation through a transparent window located above the indicated micromirrors in the matrix body, in a transparent center window its entire part is cut out with the formation of a quartz glass frame, and a zinc selenide plate is inserted into the resulting opening to transmit radiation in the infrared wavelength ranges from 1.5 to 15 μm and in the visible radiation spectrum, which is glued to the end walls of the quartz frame by the end walls glass.

These features are significant and are interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

The present utility model is illustrated by a specific example of execution, which, however, is not the only possible one, but clearly demonstrates the possibility of achieving the required technical result.

Figure 1 shows the structure of a DMD chip according to the prototype;

figure 2 - matrix DMD with replaced by ZnSe (zinc selenide) window.

According to this utility model, the construction of a DMD matrix for visible and invisible emission spectra is considered, which includes a silicon crystal a complementary metal-oxide-memory semiconductor with a structure formed on it, consisting of square aluminum micromirrors 1 installed with the possibility of rotation by an angle of at least 10 -12 ° to one and the other side from the neutral position, for directing reflected radiation through a transparent window 13 located above the specified micromirrors 1 in metallized Nominal housing 14 of the matrix at a distance of 1.1 mm.

Each micromirror of the DMD matrix (Fig. 1) can be in three positions (neutral and two tilted), but only two tilted positions are working for image formation in a DLP projector. Each micromirror 1 is located on a column 2, rigidly attached to a rocking beam 3, which, in turn, is suspended between two fixed columns on a thin, extremely elastic and strong flexible tape 5. To control the rotation of the micromirrors, the phenomenon of electrostatic attraction between the address electrode 6 and micromirror 1, mounted on the beam 3. This counter is described in relation to the prototype.

In the production of DMD matrices, standard silicon technology is used. A matrix of storage elements of size 8004600, 10244768 or larger with two metallization layers for interconnects is formed on the crystal. The third metallization layer forms the address electrodes 9 and the bias bus 10 with the "landing" zones 12. From above, a structure is created in which the space between the metal elements is first filled with a layer of organic matter, which is subsequently removed in the plasma etching unit. The fringing of the micromirror field is blackened so that there is no spurious illumination around the screen of the DLP projector. The finished crystal is placed in a ceramic-metal case 14 with a transparent window 13 made of quartz glass in place of the top cover. The contact pads 15 around the perimeter of the crystal are connected to the findings of the housing by thin gold conductors. On the reverse side of the case in the center is a rectangular metallized field for heat removal from the DMD matrix, and gilded contact pads are placed around the perimeter.

In order to provide the DMD matrix with expanding qualities in terms of the possibility of detecting IR waves according to this utility model, it is proposed to replace the existing window 13 (quartz glass) with a material that would transmit IR waves. Waves of infrared radiation transmit such materials as: fluorites (barium fluoride, calcium fluoride, potassium fluoride), germanium and zinc silicide. Of all the above, only zinc silicide (ZnSe) transmits both the invisible spectrum of IR waves and the visible spectrum of light waves. When replacing the quartz glass of the matrix window with a ZnSe plate (zinc selenide), it becomes possible to use the matrix in a wide range of IR waves: from near (1-1.5 microns) to far (up to 12-15 microns). This upgrade will allow the use of DMD matrix in projectors and simulators working with different ranges of infrared waves.

To do this, in the transparent window, its central part is cut out to form a frame 16 from the remaining part of the quartz glass, and a zinc selenide plate 17 is inserted into the obtained opening, which is glued to the end walls of the quartz glass frame by the end walls.

Improvement of the DMD matrix was carried out as follows. To implement the utility model, a DMD matrix from an Acer XI 261 projector was taken. The glass on the matrix was replaced using a self-cooling disk with galvanic diamond spraying. The quartz glass of the matrix is located above the level of the contact conductors by 1.1 mm, which allows you to make a neat cut around the perimeter of the window without damaging the contacts of the matrix. Then the glass is removed from the matrix and a 1 mm thick ZnSe plate is glued in its place. A 15x18 mm ZnSe plate is glued around the perimeter to the matrix window using a heat-conducting electrically insulating Compound casting grade KPTD-1 / 1T-5.50 (K1). Performance control is carried out by installing a new matrix in the projector to check the matrix’s performance.

Claims (1)

DMD matrix for visible and invisible emission spectra, containing a silicon crystal complementary metal-oxide-memory semiconductor with a structure formed on it, consisting of square aluminum micromirrors installed with the possibility of rotation by an angle of at least 10-12 ° to one and the other from the neutral provisions for directing reflected radiation through a transparent window located above the indicated micromirrors in the matrix body, characterized in that in the transparent window its central part is cut out with an image aniem frame of quartz glass, and the resulting plate is inserted into the opening of zinc selenide for transmission of radiation at infrared wavelengths from 1.5 to 15 microns, and radiation in the visible spectrum, which is glued to the end walls of the end walls of the quartz glass frame.

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