KR100817786B1 - Display systems incorporating light-emitting diode light source - Google Patents

Abstract

The display system has a light source consisting of at least two LED sources with somewhat different peak wavelengths of light emission. Individual LED sources are combined into a single beam with increased lumen output that rarely increases or increases in size. Such combined sources of different sources (eg red, green and blue) are useful as light engines in display systems with a limited range, resulting from the use of small light modulator panels, for example.

Description

DISPLAY SYSTEMS INCORPORATING LIGHT-EMITTING DIODE LIGHT SOURCE}

TECHNICAL FIELD The present invention relates to display systems, and more particularly, to display systems incorporating light-emitting diode (LED) light sources using a combination of LEDs of different wavelengths.

The increasing availability and increasing lumen output of LEDs of various colors (eg, red, green and blue) have generated interest in producing commercial products for lighting and display applications. .

For example, it has been proposed to combine red, green and blue light emitting LEDs to generate a white light source for general lighting purposes. See US Patent No. 5,851,063.

It is also proposed to use red, green and blue light emitting LEDs as light sources in a direct view miniature display mounted on a helmet or a pair of glasses, operating as a single light modulator panel in frame-sequential mode. Has been. See US Patent No. 5,808,800. Due to the relatively small size of the LEDs, their low power consumption, and their ability to switch on and off at frame rates fast enough to allow viewers to integrate individual color images into a full color image, Is suitable for such applications.

These same characteristics make LEDs suitable for other applications. In particular, small LEDs allow the LEDs to be suitable for use in systems having a limited etendue, such as projection systems using one or more small liquid crystal light modulator panels.

However, despite advances made in increasing the lumen output of LEDs, at this stage of development, each LED provides a less desired lumen output for some applications. A slight increase in lumen output is possible by combining several separate LEDs into an array or cluster, but it becomes even less desirable, especially for projection display systems, and further increases are limited by the size of the system.

It is therefore an object of the present invention to provide a display system using an LED based light source with increased lumen output.

This object is achieved by the display system according to the invention as defined in claim 1.

In the present invention, a separate LED has output beams, which output beams are characterized by a relatively narrow spectrum (such as about 20 nm) and can be generated to have any desired peak wavelength within a wide range, different but in proximity. It is based on the recognition that the output beams of LEDs of well-spaced peak wavelengths (1 nm or more apart) can be combined into one beam of larger lumen output with little or no increase in size. Here, a combination of two or more such LEDs is referred to as a "LED set."

Further advantageous embodiments are defined in the dependent claims.

According to the present invention, a dichroic is included for combining each output beam from each LED in the set into a better lumen output beam with little or no increase in size. There is provided a light source for a display system that also includes means such as a filter.

An advantage of the display according to the invention is that the lumen output is increased without increasing the lumen output of each LED of the light source.

Each output beam may be generated by each LED or by a cluster or array of LEDs having approximately the same peak wavelength of emission. Here, each of these LEDs, LED clusters and arrays will be referred to collectively as "LED beam source" or "LED source".

In one embodiment of the display system light source of the present invention, the LED set is combined with one or more LED beam sources and / or LED sets of different colors to produce a combined light output depending on the wavelength of the component color. To change the color and / or brightness of the display, a control circuit for changing the power level of the color and / or a control circuit for periodically switching on and off the color may be provided.

According to a preferred embodiment of the present invention, there is provided a display system incorporating a light source, said light source comprising separate primary channels of red, green and blue beams, wherein at least one of said primary channels is provided by an LED set. And the light source is modulated by one or more light modulator panels to produce a color display.

The different peak wavelengths in each LED set should be separated from each other by at least 1 nm, preferably about 20 nm, and the larger separation is determined by the desired spectral characteristics of the combined beam.

For example, a green channel may consist of a set of two LED beam sources, one source consisting of one or more 530 ± 10 nm LEDs, and the other source consisting of one or more 550 ± 10 nm LEDs. . The red channel may, for example, consist of a source of 595 ± 10 nm and a source of 615 ± 10 nm, while the blue channel may, for example, consist of a source of 450 ± 10 nm and a source of 470 ± 10 nm.

1 shows an inventive LED set showing dichroic mixing of two red LED source beams into a single red beam.

2 shows an LED source comprising a cluster of each LED.

3 illustrates a light source of the present invention comprising a green LED set.

4 shows a color projection display system incorporating the light source of the invention.

Referring now to FIG. 1, one embodiment of an LED set 10 including two LED sources 11 and 12 and a dichroic mixing arrangement in accordance with the present invention is shown. Each of the red LED sources 11 and 12 includes a single LED 13, 14 located within the reflectors 15, 16 and emitting a source beam at different peak wavelengths 595 and 615 nm, respectively. The source beams are each directed at an angle of incidence of 45 degrees on the opposing face of the dichroic filter 19 supported in the optical element 18. Filter 19 is designed to transmit a 595 nm beam and reflect a 615 nm beam. The transmitted and reflected beams deviate from the optical element 18 along a common path with a combined beam 2 that increases in lumen output but does not change in size.

Alternatively, the LED sources 11 and 12 may each comprise a cluster or array of respective LEDs, as schematically shown in FIG. LED source 20 includes an array 23 of respective LED packages. Each package includes an LED 22 that is received on a substrate 24, encapsulated in a dome-shaped element 26, and fixed within a lens 28. Collector lens 30 directs light from the array to a target 32, such as an electro-optic light modulator panel.

The combined beam can be used as a standard single color beam of wider spectrum, and can be mixed or combined with other color beams sequentially for display purposes.

For example, where fixed-size red, blue, and green channels are combined to produce white light, the current LED technology does not allow the production of green LEDs with sufficient lumen output, which is more tightly balanced. The total lumen output of the red and blue LEDs cannot be used without the desired color balance broken. By combining two green LED sources of different but closely spaced peak wavelengths, such as wavelengths of 530 nm and 550 nm, the lumen output of the green beam is nearly doubled, which also causes the red and blue beams to achieve higher lumen output. Being driven results in almost twice the combined white light output.

Such a light source is shown schematically in FIG. 3, where the green LED sources L1 and L2 with beams G1 and G2 having peak wavelengths of 530 ± 10 and 550 ± 10 nm, respectively, are dichroic mirrors M1. ) Into a single beam. This combined green beam is then combined with the red beam R from the LED source L3 by the dichroic mirror M2. The combined red and green beams are then combined with the blue beam B from the source L4 by the dichroic mirror M3 to produce a white light output beam W.

An exemplary three panel color projection display system of the present invention is shown schematically in FIG. The green beams G1 and G2 from the sources L1 and L2, respectively, are combined into a single beam by the dichroic mirror M1. Similarly, the red beams R1 and R2 from the sources L3 and L4 are combined by the mirror M2. The green and red beams are then directed by the dichroic mirror M3 along the common axis to the light modulator panel P and here from to the projection lens PL. Blue beams B1 and B2 from sources L5 and L6 are combined by dichroic mirror M4 and then directed by dichroic mirror M5 along the common axis of the red and green beams. The red, green and blue beams are each modulated by the light modulator panel P according to separate display signals. For example, in a known frame sequential drive configuration for playing color video signals, panel P is addressed as a separate primary color component of the video signal at a video frame rate, such as 60 Hz, and the LED sources L1 to L6. Is pulsed on and off synchronously by illuminating the panel P with a color corresponding to the color of the primary color component being addressed. It is preferable that panel P is a liquid crystal display device.

The actual order of dichroic mirrors need not be shown. The present invention allows the beams to be mixed in any sequence that matches good filter and optical path design criteria.

The present invention has been described with respect to a limited number of embodiments. Other embodiments, modifications to the embodiments, and embodiments recognized in the art will be apparent to those skilled in the art and are intended to be embraced within the scope of the invention, as set forth in the appended claims.

As noted above, the present invention is used in display systems, and more particularly in display systems incorporating light emitting diode (LED) light sources using a combination of LEDs of different wavelengths.

Claims (11)

As a light source comprising one LED set 34, the LED set 34 comprises two basically same color LED sources L1 and L2, each LED source L1 and L2 being A peak wavelength of the LED sources L1 and L2 of the other same color of the LED set 34 and different output beams, and are spaced at a predetermined distance from the LED sources L1 and L2 of the other same color to be provided at a predetermined angle. And the light source further comprises dichroic filtering means (M1) for combining the individual output beams into a single beam; And One control means 39 for controlling the light from the light source in accordance with the display signal Including, display system. The light source of claim 1, wherein the light source comprises one or more LED sources 36, 38 of different colors coupled with the LED set 34 to produce a combined light output that depends on the wavelength of the component color. Display system further comprising one or more dichroic filtering means (M2, M3) coupled with the LED source (36, 38). 3. Display system according to claim 2, wherein the control means (39) comprises means (48) for independently controlling the input power for each of the colors to change the color and / or brightness of the display. 3. The same color LED sources L1 and L2 emit green light, the LED source 36 emits red light, and the LED source 38 emits blue light to produce a display. Emitting display system. The light source of claim 1, wherein the light source comprises one or more sets of LEDs (42, 44) of different colors combined with LED sets (40) to produce a combined light output that depends on the wavelength of the component color. Display system further comprising one or more dichroic filtering means M2, M3, M4, M5 in combination with sets 40, 42, 44, wherein the LED set 40 is the same as the LED set 34. . delete Display system according to claim 1, wherein the control means (39) comprises at least one light modulator panel (P). 8. Display system according to claim 7, wherein the light modulator panel (P) is a liquid crystal display device. 8. The light source of claim 7, wherein the light source comprises three separate sets of LEDs 40, 42, 44, each forming a primary channel of red, green, and blue beams, each channel generating a color display. Display modulated by a light modulator panel (P). 10. Each of the LED sets 40, 42, 44 consists of two LED sources L1, L2, L3, L4, L5, L6, wherein the green channel LED sources L1, L2 are each about It has peak wavelengths of 530 ± 10 nm and 550 ± 10 nm, and the red channel LED sources L3 and L4 have peak wavelengths of about 595 ± 10 and 615 ± 10 nm, respectively, and the blue channel LED sources L5 and L6 are about respectively. Display system having peak wavelengths of 450 ± 10 and 470 ± 10nm. 6. The LED set (40) according to claim 5, wherein the LED set (40) comprising LED sources (L1 and L2) emits green light, the LED set (42) comprising LED sources (L3 and L4) emits red light, A display system wherein the set of LEDs (44) comprising LED sources (L5 and L6) emits blue light.

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