RU2265964C2 - Method for forming light flow on external screen for full color video information display system and device for realization of said method - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: spatially homogenous, collimated, serially including additional spectrum of main frequencies, light flow, which frequencies are used to form full color image, is formed directly inside light source by pulse excitation of emitting ducts, with controlled amplitude, allocated in emission volume of emitters with light production, necessary for comfortable observation of image on external screen with surface zone many times greater than light modulator area, and emitting serially light in narrow spectral ranges, appropriate for main colors. Formed light flow is controlled by means of synchronization of processes of selection of spectral components of light flow with concurrent control of its brightness level and spatial modulating by means of light flow light modulator device.

EFFECT: general simplification and higher cost effectiveness.

2 cl

Description

The present invention relates to systems for outputting a dynamic image to a screen, and in particular, image output systems using light modulators based on the principle of spatial modulation of incoherent light flux, as well as using special light sources with high efficiency. The latter circumstance makes it effective to use the present invention, in particular, for small-sized video information display devices.

Systems for outputting a dynamic image to an external screen, based on the principle of spatial modulation of light radiation, have recently been increasingly used. The most widely used devices with liquid crystal (LCD) and micromirror (DMD) light modulating matrices. Each such matrix performs spatial modulation of light by creating at each given moment in time such a spatial configuration of the states of the matrix elements "on", "off", which corresponds to a given image frame.

Each of these devices has its advantages and disadvantages. In particular, LCD matrices differ from DMD matrices in higher contrast, relative simplicity and manufacturability. On the other hand, LCD matrices are not suitable for controlling intense light fluxes, since they absorb a significant part of the light source radiation.

Micromirror DMD devices that can control significantly more intense light fluxes using more than 90% of the power of the light flux incident on them are currently preferred.

There is a method of generating light flux on an external screen for a full-color video information display system (US Patent No. 5467146), which includes creating a spatially uniform, collimated light flux having a series of fundamental frequencies that are used to form a full-color image, and controlling the created light flux using synchronization processes of separation of the spectral components of the light flux with simultaneous control of its brightness level and spatial modulus Hovhan light flux.

A device for generating light flux on an external screen for a full-color video information display system (see ibid.), Comprising a light source and an optically coupled modulator, a light flux control unit, a lens for projecting and focusing an image on an external screen

The luminous flux is created using a white light source (for example, a xenon lamp with a power of 1000 W), and image formation is carried out by synchronizing the processes of extracting the necessary spectral composition of the luminous flux and its spatial control.

To form an image, an array of digital micromirrors (DMD) is used, each of which is installed above a memory cell. Depending on the data in the memory cells, each mirror is rotated by a certain angle, while it can be tilted so as to be in the "on" state or in the "off" state. Light from mirrors in the “on” state passes through the lens and creates an image on the screen. Light from mirrors in the "off" state is reflected without entering the lens. Thus, the luminous flux incident on the surface of the DMD micromirror array is modulated.

To create a full-color image, one of the known methods is used, which consists in the sequential use of color filters that cut out the red, green or blue spectral component of the light flux from white light, which are then modulated by a micromirror matrix, after which each component of the generated image is displayed sequentially on the screen.

To form the luminous flux, several sets of lenses are used:

- the first set of lenses is used to receive the light flux from the source and the direction of the light through the composite filter, designed to highlight the three primary colors indicated above from the light flux,

- the second set of lenses is used to receive the light flux from the color filter and further focus the light on the prism used to deflect the light flux to the reflective surfaces of the micromirrors,

- a collimator lens located at the entrance of the prism serves to create a light beam with a small divergence, approximately equal in size to the size of the array of micromirrors,

- the lenses of the projection lens are designed to project light reflected from micromirrors onto an external screen.

The above prism is used to receive the light flux from the second set of lenses and to deflect it to the reflective surfaces of the micromirrors. Between the prism and the first set of lenses to control the brightness of the light transmitted to the prism, an optical shutter is placed, which is an electro-optical cell on liquid crystals.

The disadvantages of the known method and device are:

1. Low efficiency and high complexity, since the use of powerful white light lamps as a radiation source:

- leads to the need for the formation of a full-color image to select from white light and use only the red, green and blue spectral component of the light flux, for which it is necessary to use composite filters with the electromechanical principle of movement of its constituent filters;

- requires due to their inertia the use of a complex system for modulating the intensity of the light flux;

- requires the removal of excess heat with the help of electromechanical fans, which, in turn, is associated with an increase in size, an increase in noise levels, the occurrence of unwanted vibrations, as well as an increase in power consumption to a level that excludes the possibility of autonomous (on batteries) power supply of this device.

2. The use of composite filters with the electromechanical principle of moving the constituent filters to isolate the main spectral components of the image from the white light stream complicates the synchronization and image formation circuit, increases the noise level, leads to an increase in size, and also creates harmful vibrations that are very undesirable.

3. The use of an electro-optical cell on liquid crystals as a damper controlling the intensity of the light flux leads to additional absorption of the intensity of light radiation, but it does not completely solve the problem of the contrast of the light flux, since in the best case, a decrease in its intensity in the off state occurs until values not less than 1% of the initial radiation intensity.

The technical problem that the invention solves is the creation and control of the luminous flux in the process of forming a full-color dynamic image on an external screen with dimensions equivalent to a monitor screen with a diagonal of at least 6 inches, with a brightness sufficient for comfortable viewing of the image on such a screen in natural lighting, i.e. with a brightness of at least 500 cD / m ² , combined with a low level of energy consumption (units of watts), which allows the use of stand-alone power supplies with low weight and small dimensions.

The problem is solved in that a spatially uniform, collimated luminous flux, having a sequence of fundamental frequencies that are used to form a full-color image, is created directly inside the light-emitting body by means of amplitude-controlled pulsed excitation of the radiative transitions corresponding to the main colors, uniformly distributed in the light-emitting body of the emitters, sequentially emitting a collimated luminous flux with a light output necessary for comfortable observation of the image on an external screen with an area much larger than the area of the light modulator.

The created luminous flux is controlled by synchronizing the processes of isolating the spectral components of the luminous flux while simultaneously controlling its brightness level and spatial modulation using a light flux light modulator. For this, the control unit is configured to generate amplitude-controlled voltage pulses required to power the light source, and control pulses of the light modulator, synchronized with each other.

The technical advantage of the invention is:

- improving contrast in a system based on the use of a pulsed light source with a variable wavelength,

- increasing the frequency of image formation in a system based on the use of the above light source and, accordingly, the absence of the need to use a composite light filter with the electromechanical principle of moving the light filters included in it;

- reducing the size of the imaging device due to the lack of a composite filter with the electromechanical principle of moving the light filters included in it, a liquid crystal shutter and an associated optical system consisting of the first and second set of lenses, a collimator lens, fans for heat dissipation;

- reducing noise and unwanted vibrations associated with the absence of electromechanical devices with light filters and fans for heat dissipation;

- increasing the efficiency of converting electric energy into light in this method of forming a light flux for outputting an image to an external screen, associated with the above design features.

To create a luminous flux with the above properties, you can use a light source containing as a light-emitting body:

- electroluminophores placed in a matrix excited by electric current, a particular case of which are cathodoluminophores placed in a matrix excited by an electron beam created using thermionic or field emission effects;

- microcrystals with pn junctions placed in the matrix, excited using the injection of charge carriers;

- a gas discharge plasma in a matrix excited by an electric field.

Technically, you can use any of the above options for a light source. It depends on the purpose and purpose of the device in which this image forming method will be used. Their features are described in more detail below.

As a light modulator, you can use:

- a system of silicon controlled microvalves forming a matrix with a given number of elements that form the image;

- a system of silicon controlled micromirrors forming a matrix with a given number of elements that form the image;

- high-contrast high-speed liquid crystal display, working on the transmission of the light flux;

- high-contrast high-speed liquid crystal display, working on the reflection of the light flux;

- a system of controlled microvalves made of a material with a shape memory effect forming a matrix with a given number of image forming elements.

Technically, you can use any of the above light modulator options. It depends on the purpose and purpose of the device in which this image forming method will be used. Their features are described in more detail below.

In the future, the invention is illustrated by specific examples of its implementation and the accompanying drawings, in which:

figure 1 depicts a block diagram of a device for generating light flux on an external screen for a full-color video display system;

figure 2 - diagram of the formation of the light flux on the external screen for a full-color video display system with a light modulator in the form of a system of silicon controlled microvalves;

figure 3 is the same with the light modulator in the form of a system of silicon controlled micromirrors;

4 is the same, with a light modulator in the form of a liquid crystal display, operating on the transmission of the light flux;

5 is the same, with a light modulator in the form of a liquid crystal display operating on the reflection of the light flux;

6 is the same, with a light modulator in the form of a system of silicon controlled microvalves from a material with a memory effect;

7 is a block diagram of a device for generating light flux on an external screen for a full-color video display system with a light modulator located inside the light source.

The proposed method of forming a light flux for a full-color system for displaying video information on an external screen is as follows.

The luminous flux with the properties necessary for the formation of a full-color dynamic image: homogeneous, collimated, controlled by brightness, having a series of fundamental frequencies R, G, B (red, green, blue) in series is created directly inside the light source 1 (Fig. 1) by means of the amplitude of the pulse excitation of radiative transitions uniformly distributed in the light-emitting body of the emitters with a light output necessary for comfortable observation of the image on an external screen with an area of many Olsha svetomodulyatora area, and successively emitting collimated light at the respective primary colors of narrow spectral ranges.

To obtain the required collimated luminous flux, matrices (photonic crystals) are used with the necessary set of allowed energy levels - emitters placed in such a matrix emit light quanta in strictly specified directions, regardless of the specific nature of the emitted emitter (electroluminophore, pn junction microcrystal, molecule gas). By varying the amplitude of the external exciting pulse, various (corresponding to the main colors of the spectrum) energy levels are excited, thereby changing the wavelength of the emitted light. Changing the duty cycle of the pulses, change the brightness of the light flux.

Source 1 of a collimated luminous flux with a variable radiation wavelength allows you to replace several elements intended in the known method to obtain an intense luminous flux with the necessary spectrum.

Acting on the basis of the principles described above, source 1 with a variable wavelength operates in a mode of increased (≥ 30,000 kD / m ² ) brightness in a pulsed mode. With each pulse, source 1 generates collimated light radiation corresponding to red, green, or blue. The size of the light flux corresponds to the size of the light modulator 2, which forms a multi-color, high-brightness miniature image (no more than 20 × 20 mm) projected by the lens 3 onto the external screen 4.

In order to implement the proposed method, the emitted light flux must have the maximum possible intensity, in the required spectral intervals, at the lowest possible cost of electric energy, and at the same time it must be incoherent, as otherwise light interference would be destructive with respect to the generated image that violates the correct image transmission.

Among the many embodiments of the light source 1, the present invention provides:

- electroluminescent matrix, in particular a matrix with cathodoluminescent microcrystals emitting a light flux under the action of electrons emitted by field-emission cathodes,

- a matrix with microcrystals containing pn junctions emitting a light flux under the influence of injected electrons,

- a matrix with micropores containing a gas discharge plasma excited by an electric field and emitting a light flux.

In electroluminescent lamps, a light-emitting body is a specially selected high-performance phosphors, placed in a matrix with a modulated refractive index, allowing to realize, with sufficiently intense irradiation with high-energy electrons, the above principles of building a light source.

Particularly promising is the option of a planar pulsed electroluminescent lamp containing a matrix with phosphors excited by electrons emitted by field-emission cathodes. Using a lamp with autoelectronic cathodes makes it possible to produce a light source with an energy conversion efficiency of 30%, which makes it possible to achieve high brightness and at the same time compact source 1 with a variable wavelength, while working well in a pulsed mode.

Recently, great successes have been achieved in creating solid-state injection light sources - LEDs. The small size, high brightness and durability of the LEDs make it possible to consider the use of an LED matrix as a light source 1 in the patented method.

It should be noted that the low efficiency of pn junctions emitting in the blue region of the spectrum narrows their applicability in the claimed method.

From the point of view of using bright light sources, sources containing a gas-discharge plasma excited by an electric field can also be promising.

The light sources proposed in the patented method, in accordance with the principles of their construction, work well in pulsed modes, which is very important for improving the contrast and frequency of the image, since this allows you to get rid of composite filters with the electromechanical principle of moving the light filters that make up it, and from the liquid crystal shutter , and the associated optical system used in the known method.

The created luminous flux is controlled by synchronizing the processes of pulse excitation, which are controlled by the amplitude of voltage pulses, energy levels necessary to obtain the required spectral components and spatial modulation of the light flux by applying voltage control pulses to the light modulator 2.

By synchronizing the pulse control of the light modulator 2 and the light source 1, it is possible to bring the intensity of the light flux in the off state to zero, whereas in the known method, the intensity in this state does not drop to values less than 1% of the maximum value.

Due to the absence of the indicated LCD shutters and other parts listed above, the electrical control circuit of the system is simplified and the absorption of light inside it is reduced. This, of course, increases the reliability of the system and makes a positive contribution to increasing its efficiency.

The block diagram of the device is presented in figure 1.

The proposed device consists of a field emission source 1 of light containing, as a light-emitting body, an electroluminescent matrix, a light modulator 2, a lens 3, a control and synchronization unit 5, and a power source (not shown in FIG.).

The device uses the technology of sequential wavelength changes of the light source (FSC-field sequential colors), when a full-color image frame is formed of three main components, for which the light source 1 in accordance with the incoming sync pulse emits a luminous flux consisting of three main pulses colors - red, green and blue.

As the electron source in the light source 1, a composite field-based cathode based on carbon materials (graphite, carbon, single-walled or multi-walled carbon nanotubes, etc.) is used. Autoelectronic cathodes made of carbon materials are able to operate for a long time under conditions of high technical vacuum (10 ^-6 -10 ^-7 mm Hg), which is achieved in conventional sealed devices, while ensuring high emissivity.

The use of modern phosphors makes it possible to obtain high brightness (~ 30000 kD / m ² ) of luminescence, which makes it possible to sharply reduce the dimensions of the light source by making its emitting part ~ 20 × 20 mm in size equal to the size of the light modulator 2.

As the light modulator 2, you can use any controlled matrix of trace elements, a variable configuration of which modulates the light flux from the light source 1.

In the present invention, as a light modulator 2, it is proposed to use a controlled matrix consisting of silicon microvalves 6 (FIG. 2) operating in the transmission or reflection mode of the light flux in which the matrix openings are overlapped by microvalves. Microvalves are made of silicon according to microtechnology and have electrostatic control (Scherbakov N.A., Eremenko A.N., Gornev E.S., Zaitsev A.N. et al. "Research and development of manufacturing technology for microsystem products" // Microsystem Engineering. 2002, No. 5, pp. 5-7; US Patent No. 5079544). The matrix, consisting of a sufficient number of such microvalves 6, is very promising as a light modulator. This is due to the fact that in the transmission position the micro valves are not heated by the intense light flux, which improves the stability of the device and, all other things being equal, makes it preferable.

In addition, the use of microvalves makes it possible to simplify the optical circuit of the device compared to the known method, since it is possible to refuse not only the components listed above, but also the special prism necessary in the known method for introducing light flux onto a micromirror DMD matrix.

In the case of using microvalves, you can get the best combination of advantages of the proposed method of forming the light flux.

Widespread as a light modulator 2 received a system of micromirrors 7 (figure 3), forming a matrix with a given number of elements that form the image (see ibid.). Each element, working on the reflection of light, changes the direction of the light beam, with a frequency sufficient to create a dynamic image. Between the matrix of micromirrors 7 and lens 3, a prism 8 is installed to receive the light flux from the source 1 and to deviate it to the reflective surfaces of the micromirrors 7.

LCD competitors 9 and 10 (FIGS. 4 and 5) compete with them, which, due to electro-optical effects in liquid crystals, can create dynamic configurations of matrix elements operating both for transmission (US patent No. 08/146385) and light reflection ( U.S. Patent No. 6,375,330). It should be noted their high contrast and relative ease of manufacture, but it should be said about their significant drawback. In the case of the displays 7 transmitting the light flux, they absorb a significant portion of the light energy and, thereby, significantly reduce the efficiency of the system, which can be a determining factor, especially for small-sized and mobile image output devices.

In the case of the LCD display 10 (FIG. 4), which operates on the reflection of the light flux, the absorption of light energy is reduced, however, the above-described problem of complicating the optical circuit arises due to the need for introducing the light flux onto the reflective surface of the display using an additional prism 11.

Another option for using microvalve matrices proposed in this method is a variant with a microvalve system 12 made of a material with shape memory (AS USSR No. 1609371), which also operates in the mode of transmitting or not transmitting the light flux described above, in which the matrix openings are blocked by microvalves . The difference in controlling microvalves from a material with shape memory is that it is carried out by heating with an electron beam. The advantages of such a microvalve matrix are the simplicity of its manufacture, compatibility with electrovacuum devices, in particular with an electroluminescent lamp with autocathodes described above.

This circumstance can be used in the proposed method when creating a new, more compact version of the device.

The compactness of the device is also achieved due to the fact that the light modulator 13 (Fig. 7) is placed inside the source body 14, and the electron beams from the autocathode system are used both to excite a composite phosphor in an electroluminescent matrix and, accordingly, to create a modulated light flux and to control a matrix of microvalves from a material with a shape memory controlling the luminous flux.

In this case, a composite phosphor is deposited on the boundary 15 of the aluminum layer 16, which acts as a mirror reflecting the excited light to the light modulator 13, and a matrix of a transparent dielectric 17 with microchannels, acting as a photonic crystal. Through matrix autocathodes containing emitting elements 18 located at the interface of the matrix with microchannels 17 and a transparent dielectric 19 on one side and on a transparent dielectric 19, which allows galvanic separation of the emitting elements 18 of the composite autocathode on the other, the collimated light passes through the light modulator 13. Electrical The excitation pulses of the phosphor of the electroluminescent matrix 17 of the light source and the control of the light modulator 13 are fed respectively to the emitting elements of the composite autocathode from the electronic synchronization and control unit 20, performed similarly to block 5. Depending on the amplitude of the pulse, the corresponding radiating transition of the composite phosphor is excited, thereby achieving color control.

Block 5 (figure 1) is made in accordance with the principles set forth in US patent No. 5467146, and works as follows. Amplitude-controlled voltage pulses are generated that are required for the light source to work and create a light flux, while these pulses are electronically synchronized with the video pulses controlling the light modulator 2, as described in US Pat. No. 5,467,146, forming an image.

Having thus realized a sufficiently high efficiency of converting the energy of the power source into the energy of light radiation, it is important not to lose the intensity of the light flux when it is controlled and formed in the process of creating the image. For this purpose, it is most expedient to use a system of silicon control microvalves operating in the transmission / reflection mode of light as a light modulator.

Thus, this device circuit turns out to be much simpler than that used in the prototype, which allows us to significantly simplify the electronic component of the device and, accordingly, the synchronization circuit of pulses including a light source with a packet of video pulses supplied to the light modulator to form a frame-by-frame image. Unlike the prototype, in which the signals that control the rotation of the composite filter are synchronized with the signals that control the LCD shutter and the video pulses supplied to the light modulator, in the proposed device it is sufficient to synchronize the on and off pulses of the light source with the video pulses, the principles of formation of which are described in the patent prototype.

The brightness and contrast of the image are controlled by changing the amplitude of the pulses applied to the emitting elements of the light source autocathode.

The result is a compact, low-power, projection device with the light characteristics necessary for comfortable viewing of the image, with dimensions comparable to the sizes of cell phones.

Such a device can be used both in mobile devices requiring information output (for example, laptops), and in stationary or portable devices, drastically reducing the used workspace.

Claims (21)

1. A method of generating a light flux for a full-color system for displaying video information on an external screen, including creating a spatially uniform, collimated light flux having a sequence of fundamental frequencies that are used to form a full-color image, controlling the created light flux by synchronizing the processes for isolating the spectral components of the light flux with simultaneous control of its brightness level and spatial modulation using a light mode a light flux radiator, characterized in that a spatially uniform, collimated, having a sequence of fundamental frequencies spectrum, light flux with a controlled level of its brightness, is created directly inside the light-emitting body by means of amplitude-controlled pulsed excitation corresponding to the main colors of the radiative transitions uniformly distributed in the light-emitting body emitters sequentially emitting a collimated luminous flux with a light output necessary for a comfortable observational Denia image on the external screen area much larger area svetomodulyatora. 2. The method according to claim 1, characterized in that to create a luminous flux, an electroluminescent lamp with an electroluminescent matrix is used as a light-emitting body. 3. The method according to claim 1, characterized in that to create a luminous flux, an electroluminescent lamp with an electroluminescent matrix is used as a light-emitting body excited by autoelectronic cathodes. 4. The method according to claim 1, characterized in that to create a luminous flux using a light source containing an LED matrix as a light-emitting body. 5. The method according to claim 1, characterized in that to create a luminous flux using a plasma panel with a plasma excited in the matrix as a light-emitting body. 6. The method according to any one of claims 1 to 5, characterized in that for spatial modulation using a system of silicon controlled microvalves that form a matrix with a given number of elements that form the image. 7. The method according to any one of claims 1 to 5, characterized in that for spatial modulation using a system of silicon controlled micromirrors, forming a matrix with a given number of elements that form the image. 8. The method according to any one of claims 1 to 5, characterized in that for spatial modulation using a high-contrast high-speed liquid crystal display, operating on the transmission of the light flux. 9. The method according to any one of claims 1 to 5, characterized in that for spatial modulation using a high-contrast high-speed liquid crystal display that operates on the reflection of the light flux. 10. The method according to any one of claims 1 to 5, characterized in that for spatial modulation using a system of controlled microvalves from a material with a shape memory effect, forming a matrix with a given number of image forming elements. 11. A device for generating light flux on an external screen for a full-color video information display system, comprising a light source, a light-emitting body emitting a light flux and an optically coupled light modulator, a light flux control unit, an electrically coupled light modulator, a lens for projecting and focusing the image on external screen, characterized in that the light source is configured to be controlled by the amplitude of the pulsed excitation of radiative transitions, distributed emitters defined in the light-emitting body with light output necessary for comfortable viewing of the image on an external screen with an area much larger than the light modulator, and emitting sequentially collimated light in narrow spectral intervals corresponding to the main colors, and the control unit is configured to generate voltage pulses controlled by the amplitude necessary for excitation of radiating transitions, and control pulses of the light modulator, synchronized with each other. 12. The device according to claim 11, characterized in that the light source contains an electroluminescent lamp containing an electroluminescent matrix as a light-emitting body. 13. The device according to claim 11, characterized in that the light source contains an electroluminescent lamp containing an electroluminescent matrix as a light-emitting body with auto-electronic cathodes. 14. The device according to claim 11, characterized in that the light source contains LEDs distributed in a matrix with injection-excited radiative transitions in it as a light-emitting body. 15. The device according to claim 11, characterized in that the light source comprises a plasma panel with plasma excited in the matrix as a light-emitting body. 16. The device according to any one of paragraphs.11-15, characterized in that as a light modulator contains a system of silicon controlled microvalves that form a matrix with a given number of elements that form the image. 17. The device according to any one of paragraphs.11-15, characterized in that as a light modulator contains a system of silicon controlled micromirrors forming a matrix with a given number of elements that form the image. 18. The device according to any one of paragraphs.11-15, characterized in that as a light modulator contains a high-contrast high-speed liquid crystal display, operating on the transmission of the light flux. 19. The device according to any one of paragraphs.11-15, characterized in that as a light modulator contains a high-contrast high-speed liquid crystal display that operates on the reflection of the light flux. 20. The device according to any one of paragraphs.11-15, characterized in that as a light modulator contains a system of controlled microvalves of material with a shape memory effect, forming a matrix with a given number of image forming elements. 21. A device according to any one of claims 11-15, characterized in that the light modulator comprises a system of electron-controlled micro-valves made of a material with a shape memory effect forming a matrix with a given number of elements forming an image located inside an electroluminescent lamp with an auto-electronic cathode, electronic beam from which is used to control microvalves.

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