TW201643540A - Laser LED hybrid light source for projection display - Google Patents

Abstract

A light source for a projection display comprising: a heat sink; a phosphor composition provided on said heat sink, wherein said phosphor composition is a phosphor powder, a ceramic phosphor or a liquid phosphor; one or more lasers directed at said phosphor composition; an electronic circuit connected to said one or more lasers to regulate power output to said one or more lasers; and a power source connected to said electronic circuit, wherein when said one or more lasers are activated exciting said phosphor composition the light emitted from said phosphor composition is said light source for said projection display.

Description

Laser LED hybrid light source for projection display

The present invention discloses the use of a blue or UV laser to excite a phosphor of a system to increase its brightness. More particularly, the present invention relates to a laser LED hybrid light source for use in a projection display.

The advantage of a white LED being used in a projection display is that it is simpler than combining red, green and blue LEDs and can reduce the cost of the system. The output of the projector is limited by the brightness of the LED, and recycling the unused LED light to the LED itself increases the output brightness, thus increasing the output of the projector. In order to increase this output, a new mode is needed.

According to an embodiment of the present invention, a light source for a projection display is specifically provided, comprising: a heat sink; a phosphor composition is provided on the heat sink, wherein the phosphor composition is a phosphorescent powder, a ceramic Phosphor, or a liquid phosphor; one or more lasers are directed to the phosphor composition; an electronic circuit coupled to the one or more lasers to modulate the one or more lasers a power output; and a power source coupled to the electronic circuit; wherein when the one or more lasers are activated to excite the phosphor composition, the light emitted by the phosphor is the light for the projection display Light source.

Figure 1 shows the basis for using a laser to generate light from phosphorescence.

Figure 2 shows the construction of a white LED.

Figure 3 illustrates the use of a recovery loop to cause a portion of the unused output to be reflected back to the LED to increase brightness.

Figure 4 shows that the added UV or blue laser light is directed to the phosphor layer of the LED to excite the phosphor.

Figure 5 illustrates an embodiment of a light pipe system.

Figure 6 shows another embodiment of a light pipe system.

Figure 7 shows a typical DLP projector system.

Figure 8 illustrates an embodiment of a DLP projector system.

Figure 9 illustrates an embodiment of a light source driven by a laser input.

Figure 10 shows another configuration of the recovery loop.

Figure 11 shows another configuration of a recovery loop having a parabolic shape.

Figure 12 illustrates an embodiment using a tapered light pipe or CPC.

Figure 13 shows another embodiment in which the splitter is selected to be replaced by a selection filter.

Figure 14 illustrates another embodiment in which more than one phosphorescent illumination region can be accommodated.

Figure 15 shows another embodiment in which the light pipe is reverse tapered.

Figure 16 shows an embodiment in which a cone-shaped light pipe is added.

Figure 17 shows a laser-excited phosphor system with a layer of phosphor on top of a heat sink.

Fig. 18 shows an example of the configuration of the laser source.

Figure 19 shows another configuration in which the recovery loop is parabolic.

Figure 20 shows the configuration of the laser source around the recovery loop.

Figure 21 illustrates another configuration in which a plurality of laser sources are used to excite the phosphor.

Figure 22 shows an example of a configuration with three laser sources and three small mirrors surrounding the edges of the output beam.

Figure 23 shows various different configurations of the phosphor.

Figure 1 shows the basis for using a laser to generate light from phosphorescence. Most lasers can be used to increase this brightness.

2 shows the construction of a white LED comprising a blue LED and a phosphor layer that is excited by the blue light to produce red and green light. The phosphorescent system is adjusted such that a total output consisting of red, green, and blue light causes a white light output.

Figure 3 illustrates the use of a recovery loop to cause a portion of the unused output to be reflected back to the LED to increase brightness. A portion of the reflected light is coupled to the output to increase the brightness.

Figure 4 shows that the added UV or blue laser light is directed to the phosphor layer of the LED to excite the phosphor, thereby causing the original LED to cause an added output and increasing the brightness of the system. As shown in this figure, one or more lasers can be used depending on the desired output, the light processing capabilities of the white LED, the heat dissipation capabilities of the LED, and the life expectancy of the system. The laser can be mounted on the recovery ring. The laser can also be external to the recovery ring and its beam can be directed to the white LED via one of the holes in the ring.

In another embodiment, the white LED can be simply replaced with a phosphor layer coated on a heat sink substrate. In this case, it will be a pure laser system.

In another embodiment, the recovery loop is not used in lower output, lower cost systems.

Figure 5 shows a system using a light pipe. The excitation laser light has a different wavelength than the output blue light, so a beam splitter can be used to separate the excitation laser light from the output blue light, as well as the red and green light.

Using an alternative reflective surface as shown in the figure, a portion of the output is reflected back to the LED, increasing the brightness of the output.

In other embodiments similar to Figures 5 and 6, the white LED can be simply replaced with a phosphor layer coated on a heat sink.

In another embodiment, a phosphorescent material having other colors can be used to produce colored light. For example, a green phosphor can be used to produce green light. The laser excitation increases the green light output and increases its brightness. In another embodiment, a red phosphor can be used.

In another embodiment as shown in Figure 6, a different wavelength of phosphorescence energy is used to increase the output of a particular color. For example, a green LED with a wavelength of 540 nm will be used with a green phosphor that will transmit 540 nm but absorb UV and or blue light, so more green light will be generated by the excitation, thus increasing the output brightness. .

In yet another embodiment, a red phosphor can be used to increase the brightness of red light similar to the green color described above.

In summary, any color LED can be used, and its brightness can be as The foregoing is increased by directing the excitation laser onto the transparent phosphor.

The increase in brightness using colored LEDs can also be implemented using a light pipe system as shown in Figures 5 and 6.

Figure 7 shows a typical DLP projector system in which this laser/LED source can be used. The same light source can also be used on a 3LCD and LCOS projector system.

Figure 8 illustrates an embodiment of a DLP projector system. The output of light recovered by the white LED will be collimated. A beam splitter can be used to direct the excited laser light to the white LED via the collimating lens. The final output is focused in the light tunnel and finally forwarded to the DLP panel for projection.

Additional information

Figure 9 illustrates an embodiment of a light source driven by a laser input. The laser can be made of a semiconductor material, a solid state, or other laser material, including a gas laser, for UV or blue laser light. The laser input is reflected towards the phosphor, which absorbs the laser radiation and emits light of a different color depending on the material used. For example, white, red, green, blue or other colors can be produced. The phosphorescent material is placed on top of a heat sink so that the phosphor temperature will remain low for efficient operation. One or more phosphorescent materials having different colors can be used as a mixture or spatially disposed on the heat sink so that the desired color can be obtained. The heat sink is also made reflective so that the laser light and the light emitted by the phosphor are all directed into the direction of the output. The output from the phosphor is generally bright and contains many high angles of emitted light. In this embodiment, the contoured emitted light is reflected back to the phosphor by the reflective ring. The shape of the ring A developing device can be formed for the spherical surface to return the phosphorescent image to itself. Through the aperture of the recovery loop, the output is collimated by the lens 1. The output emission pupil is transmitted through the selection filter, which transmits light emitted by the phosphor and reflects the laser light. The output parallel beam can also be focused to a small point using the alternative focusing lens 2.

Figure 10 illustrates another configuration of the recovery loop having a parabolic shape such that light reflected by the surface is parallel to the heat sink and is again reflected back to the phosphor by the ring. In this configuration, the phosphorescent system is placed at the focus of the parabolic surface.

Figure 11 shows another configuration of the recovery ring having a parabolic shape. In this example, the phosphorescent system is placed at the focus of the parabolic reflector so that the light is reflected back toward the heat sink and perpendicular to the heat sink. A reflector is placed in parallel or placed on top of the heat sink such that the parallel beam is reflected toward the parabolic reflector and then focused back to the phosphor for recovery.

Figure 12 illustrates an embodiment using a tapered light pipe or CPC. The laser light is incident on the selective beam splitter such that the laser light is reflected toward the cone of light and impinges on the phosphor. Light emitted by the phosphor will be coupled into the tapered tube and into the selective beam splitter such that the light is transmitted through toward the output. All six sides of the selective beam splitter are polished to function as a waveguide and total internal reflection occurs at the triangular faces of the turns forming the splitter. The output face of the tapered light pipe is substantially the same size as the input face of the beam splitter. The output face of the beam splitter can be partially covered by a reflective surface such that a portion of the output can be coupled back The phosphor is for recycling. An alternative reflective polarizer, not shown, can be placed at the output aperture to allow unused polarized light to be recovered.

Figure 13 illustrates another embodiment in which the selective beam splitter is replaced with a selection filter such that the laser light is reflected toward the phosphor, and light output by the phosphor is transmitted through the selection filter. Light. The output face of the tapered light pipe may also be partially coated with a reflective coating leaving an aperture for output.

Figure 14 illustrates another embodiment in which more than one phosphorescent illumination region can be accommodated. In this case, the region without the phosphor can be coated with a reflective surface M1 such that the recovered light is reflected back toward the output outside of the phosphor regions. In another configuration, the heat sink reflector is coated differently, and the input face of the light pipe can be coated with a reflective object such as M2.

Figure 15 illustrates another embodiment wherein the light pipe is reversely tapered such that high angle emitted light from the phosphor is reflected back to the phosphor for recovery. In the case of a solid reverse tapered light pipe, the outer side surface must be coated with a reflective coating.

Figure 16 shows an embodiment in which a tapered light pipe is added so that the output face size and the angle of the light output can be adjusted.

Although Figures 15 and 16 show that the embodiments have tapered light tubes, solid or hollow, they can also be made using solid or hollow CPCs. Also, if a solid CPC is used, its exterior must be coated with a reflective coating.

Further information

Phosphorescent materials for laser excitation can be broadly classified into three depending on their power handling capabilities.

1. Phosphorescent powders are composed of phosphorescent powders bonded together with organic materials such as glues, epoxy resins, etc., so a thin layer can be placed on top of a substrate, such as glass, metal, etc. And was formed. The limitation is the heat dissipation of the phosphor and the burning of the glue by the excited laser.

2. Ceramic phosphors are composed of phosphorescent powders bonded together with inorganic materials such as glass, and are usually solid and exhibit a sheet such as a ceramic phosphor. Because there is no "glue", it can withstand much higher temperatures at higher laser power.

3. A liquid phosphor is composed of a unit having a phosphorescent powder suspended in a liquid. The phosphor can be made flowing, so thermal energy is quickly removed to increase the power handling capability of the system.

The following disclosure describes the phosphor on top of a heat sink, but these configurations can be applied to systems containing the above three phosphors.

Figure 17 shows a laser-excited phosphor system with a layer of phosphor on top of a heat sink. The phosphor layer of the layer may be any of the above three configurations. A spherical recovery ring is placed such that its center of curvature is substantially at the phosphor position so that light emitted by the phosphor will be reflected back to itself. A portion of the light emitted by the phosphor will exit the aperture of the recovery ring to form the output of the system. The portion of the light that does not exit the aperture will be reflected back to the phosphor by the recovery ring. The portion of the light that is incident on the phosphor will be re-emitted and exit the aperture as an output of the system, and a portion of the light will again be reflected back to the phosphor by the recovery ring. The light system emitted by the phosphor is passed through a smaller aperture by an excitation laser source disposed around the recovery ring so that the laser beam can enter without loss.

An example of the configuration of the laser source is shown in FIG. In this particular example, six laser sources will be used and they are evenly placed around the recovery loop. The number of lasers can be adjusted to provide the total laser power required. For efficient operation, the pores for the laser beam are made small relative to the size of the recovery loop, so a minimum amount of surface area available for recovery can be removed.

Figure 19 shows another configuration in which the recovery loop is parabolic and therefore requires two reflections. The first reflection will collimate the beam, and the second reflection will focus the beam back to the phosphor. In this example, the excitation laser source causes the beam to enter the aperture and is reflected by the other side of the parabolic reflector and focused on the phosphor. Therefore, the configuration of the laser source around the recovery ring must be adjusted as shown in Figure 20 so that the laser sources do not directly oppose each other.

Figure 21 illustrates another configuration in which a plurality of laser sources are used to excite the phosphor. In this case, a plurality of lenses will be used to collect and collimate the light emitted by the phosphor, such as lens 1 and lens 2 as shown. The laser source is disposed outside the output of the side such that the laser beam is reflected by a small mirror toward the phosphor as shown, because the mirror is small and matches the size of the laser beam, The amount of output blocking is small.

Figure 22 shows an example of this configuration having three laser sources and three small mirrors surrounding the edge of the output beam. Depending on the exact wavelength considered, the mirror can be made to have a dichroic coating that reflects the laser beam and transmits the output emitted by the phosphor to reduce the barrier loss of the system.

Figure 23 shows various different configurations of the phosphor with (a) phosphorescent powder The final/glue or ceramic phosphor is on top of a heat sink, (b) the phosphor is suspended in the liquid, and (c) the phosphor is on a rotating wheel to increase the surface area, reduce the effective area, and increase the total power handling capacity. .

Claims (10)

A light source for a projection display, comprising: a heat sink; a phosphor composition is provided on the heat sink, wherein the phosphor composition is a phosphorescent powder, a ceramic phosphor, or a liquid phosphor; More lasers are directed to the phosphor composition; an electronic circuit is coupled to the one or more lasers to regulate power output to the one or more lasers; and a power source is coupled to the electronic circuit Wherein when the one or more lasers are activated to excite the phosphor composition, the light emitted by the phosphor is the light source for the projection display. The light source for a projection display of claim 1, further comprising a light emitting diode disposed between the heat sink and the phosphor. The light source for a projection display of claim 1, further comprising a recovery ring having a reflective inner surface, an outer surface, and a light output aperture near the center thereof, the ring being fixed above the heat sink and surrounding The phosphorescent composition is such that light exiting the light exiting aperture of the recovery ring that is emitted by the phosphor is reflected back to the phosphor composition. A light source for a projection display of claim 3, wherein the one or more laser systems are mounted on the outer surface of the recovery ring. The light source for a projection display of claim 1, further comprising a beam splitter, wherein the beam splitter controls the laser guided to the phosphor composition The wavelength of light emitted by the light and the light emitted by the phosphor. The light source for a projection display of claim 1, wherein the projection display is a DLP projector system, a 3LCD projector system, and an LCOS projector system. A light source for a projection display of claim 1, further comprising one or more lenses that focus light emitted by the one or more lasers and after being excited by the one or more lasers The light emitted by the phosphor. The light source for a projection display of claim 1, further comprising a light pipe, wherein the light pipe has an inner surface, an outer surface, a first end, a second end and an output aperture at the second end The first end is disposed above the phosphorescent composition, and the second end has a reflective inner surface. A light source for a projection display of claim 8, wherein the inner surface of the light pipe is reflective. The light source for a projection display of claim 8, wherein the light pipe further comprises a beam splitter, wherein the beam splitter is disposed on the inner surface adjacent to the second end.